Newport 6000 Operation And Maintenance Manual

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Model 6000 Laser Controller
Operation and Maintenance Manual
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Corporate Headquarters Canada Italy Netherlands Taiwan R.O.C.
France Japan Switzerland United Kingdom
Telephone: 949-863-3144 Telephone: 1-60 91 68 68 Telephone: 03-5379-0261 Telephone: 01-740-2283 Telephone: 01635-521757 Facsimile: 949-253-1800 Facsimile: 1-60 91 68 69 Facsimile: 03-5379-0155 Facsimile: 01-740-2503 Facsimile: 01635-521348
Belgium
Germany
Telephone: 016-402927 Telephone: 06151-36 21-0 Facsimile: 016-402227 Facsimile: 06151-36 21-52
Newport Corporation, Irvine, California, has been certified compliant with ISO 9002 by the British Standards Institution.
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Limited Warranty
Newport warrants that this product will be free from defects in materials and workmanship for a period of two years from the date of shipment. If any such product proves defective during the applicable warranty period, Newport, at its option, either will repair the defective product with charge for parts and labor or will provide a replacement in exchange for t he defective product.
In order to obtain service under this warranty, the customer must notify Newport of the defect before the expiration of the warranty period and make suitable arrangements for the performance of service. In all cases the customer will be responsible for packaging and shipping the defective product back to the service center specified by Newport, with shipping charges prepaid. Newport shall pay for the return of the product to the customer if the shipment is within the continental United States, otherwise the customer shall be responsible for all shipping charges, insurance, duties and taxes, if the product is returned to any other location.
This warranty shall not apply to any defect, failure or damage caused by improper use or failure to observe proper operating procedures per the product specification or operators manual or improper or inadequate maintenance and care. Newport shall not be obligated to furnish service under this warranty 1) to repair damage resulting from attempts by personnel other than Newport’s representatives to repair or service the product; 2) to repair damage resulting from improper use or connection to incompatible equipment; 3) to repair damage resulting from operation outside of the operating or environmental specifications of the product.
NEWPORT’S LIABILITY FOR THE MERCHANTABILITY AND USE OF THE PRODUCT IS EXPRESSLY LIMITED TO ITS WARRANTY SET OUT ABOVE. THIS DISCLAIMER AND LIMITED WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL REPRESENTATIONS AND WARRANTIES EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR OF FITNESS FOR PARTICULAR PURPOSE, WHETHER ARISING FROM STATUTE, COMMON LAW, CUSTOM OR OTHERWISE. THE REMEDY SET FORTH IN THIS DISCLAIMER AND LIMITED WARRANTY SHALL BE THE EXCLUSIVE REMEDIES AVAILABLE TO ANY PERSON. NEWPORT SHALL NOT BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF THIS PRODUCT OR CAUSED BY THE DEFECT, FAILURE OR MALFUNCTION OF THIS PRODUCT, NOR ANY OTHER LOSSES OR INJURIES, WHETHER A CLAIM FOR SUCH DAMAGES, LOSSES OR INJURIES IS BASED UPON WARRANTY, CONTRACT, NEGLIGENCE, OR OTHERWISE. BY ACCEPTING DELIVERY OF THIS PRODUCT, THE PURCHASER EXPRESSLY WAIVES ALL OTHER SUCH POSSIBLE WARRANTIES, LIABILITIES AND REMEDIES. NEWPORT AND PURCHASER EXPRESSLY AGREE THAT THE SALE HEREUNDER IS FOR COMMERCIAL OR INDUSTRIAL USE ONLY AND NOT FOR CONSUMER USES AS DEFINED BY THE MAGNUSOM-MOSS WARRANTY ACT OR SIMILAR STATE CONSUMER WARRANTY STATUTE.
©1996, Newport Corporation Irvine, California, USA Part No. 22169-01 IN-02961 Rev. D Printed 2-Dec-98
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EC DECLARATION OF CONFORMITY
Model 6000 Laser Controller
We declare that the accompanying product, identified with the “ ” mark, meets all relevant requirements of Directive 89/336/EEC and Low Voltage Directive 73/23/EEC.
Compliance was demonstrated to the following specifications:
EN50081-1 EMISSIONS:
Radiated and conducted emissions per EN55011, Group 1, Class A
EN50082-1 IMMUNITY:
Electrostatic Discharge per IEC 1000-4-2, severity level 3 Rated Emission Immunity per IEC 1000-4-3, severity level 2 Fast Burst Transients per IEC 1000-4-4, severity level 3 Surge Immunity per IEC 1000-4-5, severity level 3
IEC SAFETY:
Safety requirements for electrical equipment specified in IEC 1010-1
.
VP European Operations General Manager-Precision Systems
Zone Industrielle 1791 Deere Avenue
45340 Beaune-la-Rolande, France Irvine, Ca. USA
______________________ ______________________
Alain Danielo Jeff Cannon
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Table of Contents
1.
General Information ____________________________________________1
1.1 Introduction________________________________________________________ 1
1.2 Product Overview___________________________________________________ 1
1.3 Available Options and Accessories _____________________________________ 3
1.4 Safety Terms and Symbols____________________________________________ 4
1.4.1
Terms ________________________________________________________________ 4
1.4.2
Symbols ______________________________________________________________ 4
1.5 General Warnings and Cautions_______________________________________ 4
2.
System Operation _______________________________________________7
2.1 Introduction________________________________________________________ 7
2.2 Installation_________________________________________________________ 7
2.2.1
AC Power Considerations_________________________________________________ 7
2.2.2
Tilt-Foot Adjustment ____________________________________________________ 8
2.2.3
Rack Mounting _________________________________________________________ 8
2.2.4
Ventilation Requirements _________________________________________________ 8
2.2.5
Power-Up Sequence _____________________________________________________8
2.3 Introduction to the 6000 Front Panel ___________________________________ 9
2.3.1
Model 6000____________________________________________________________ 9
2.3.2
Model 6000M and 6000MF ______________________________________________ 10
2.4 General Operation _________________________________________________ 11
2.4.1
Display Elements ______________________________________________________ 11
2.4.1.1 Static Fields ________________________________________________________ 11
2.4.1.2 Non-Editable Data Fields ______________________________________________ 11
2.4.1.3 Editable Data Fields __________________________________________________ 11
2.4.1.3.1 Changing Data Fields______________________________________________ 11
2.4.1.4 Soft Keys __________________________________________________________ 12
2.4.2
Function Keys_________________________________________________________ 13
2.4.3
Menu Structure ________________________________________________________ 14
2.4.4
Master Display ________________________________________________________15
2.4.5
MOPA Master Display__________________________________________________ 15
2.4.6
Main Menu ___________________________________________________________ 15
2.4.7
Configure Menu _______________________________________________________ 16
2.4.8
System Configure Screen ________________________________________________ 17
2.4.9
Save/Recall Screen _____________________________________________________ 18
2.4.10 Linking Screen ________________________________________________________ 18
2.4.11 Calibration Screen _____________________________________________________ 20
2.4.12 Configure Communications Screen ________________________________________ 20
2.4.12.1
Error Message Control ______________________________________________ 20
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2.5 Rear Panel Familiarization __________________________________________21
2.5.1
GPIB Connector_______________________________________________________ 21
2.5.2
RS-232 Connector _____________________________________________________ 21
2.5.3
Input Power Connector _________________________________________________ 21
2.5.4
GND Post____________________________________________________________ 22
2.6 Warm Up and Environmental Consideration ___________________________ 22
3.
Principles of Operation _________________________________________23
3.1 Introduction_______________________________________________________23
3.2 Laser Module Theory of Operation____________________________________ 24
3.2.1
Laser Interface ________________________________________________________ 24
3.2.2
Limit DAC___________________________________________________________ 25
3.2.3
Set Point DAC ________________________________________________________ 25
3.2.4
A/D Converter ________________________________________________________ 25
3.2.5
Current Source Voltage _________________________________________________ 25
3.2.6
Output Shorting _______________________________________________________ 25
3.2.7
Modulation/Voltage Control Input Port _____________________________________ 25
3.2.8
Photodiode Feedback Amplifier __________________________________________ 26
3.2.9
Constant Current, High Bandwidth Mode ___________________________________ 26
3.2.10 Constant Current, Low Bandwidth Mode ___________________________________ 26
3.2.11 Constant Power Mode __________________________________________________ 27
3.3 TEC Module Theory of Operation ____________________________________29
3.3.1
TEC Interface_________________________________________________________ 29
3.3.2
Limit DAC___________________________________________________________ 29
3.3.3
Set Point DAC ________________________________________________________ 30
3.3.4
A/D Converter ________________________________________________________ 30
3.3.5
Sensor Select _________________________________________________________ 30
3.3.6
Difference Amplifier ___________________________________________________ 30
3.3.7
Proportional Amplifier and Integrator______________________________________ 30
3.3.8
Bipolar Output Stage ___________________________________________________ 31
3.3.8.1 Current Limiting ____________________________________________________ 31
3.3.8.2 Current Limit Condition Sensing________________________________________ 31
3.3.8.3 Voltage Controlled Current Source ______________________________________ 31
3.3.8.4 Voltage Limit Condition Sensing________________________________________ 31
3.3.9
TEC Control Modes____________________________________________________ 31
3.3.9.1 T Mode ___________________________________________________________ 31
3.3.9.2 R Mode ___________________________________________________________ 32
3.3.9.3 ITE Mode __________________________________________________________ 32
3.4 Microprocessor Board ______________________________________________33
3.4.1
Microprocessor _______________________________________________________ 33
3.4.2
Memory _____________________________________________________________ 34
3.4.3
Serial Interface________________________________________________________ 34
3.4.4
Front Panel Interface ___________________________________________________ 34
3.4.5
GPIB Interface________________________________________________________ 34
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3.5 Power Supplies ____________________________________________________ 34
3.5.1
Module Power Supplies _________________________________________________ 34
3.5.2
Main Supply __________________________________________________________ 35
3.6 Interlock Operation ________________________________________________ 35
3.6.1
Laser Interlock ________________________________________________________35
4.
Laser Diode Driver Module Operation _____________________________37
4.1 Laser Diode Driver Module__________________________________________ 37
4.1.1
Introduction __________________________________________________________ 37
4.1.2
Installation ___________________________________________________________ 37
4.1.3
Laser Diode Protection Requirements ______________________________________ 38
4.2 Laser Safety Features_______________________________________________ 40
4.2.1
Conditions Which Can Automatically Shut Off the Laser Output._________________40
4.2.2
Key switch Interlock____________________________________________________ 40
4.2.3
Turn On Delay ________________________________________________________ 41
4.3 The Laser Connectors ______________________________________________ 41
4.3.1
Modulation ___________________________________________________________ 42
4.3.2
Photodiode Bias Control_________________________________________________ 42
4.3.3
Photodiode ___________________________________________________________ 42
4.3.4
Interlock _____________________________________________________________ 42
4.4 Connecting to Your Laser ___________________________________________ 42
4.4.1
Laser Diode Connections and Shielding_____________________________________ 43
4.4.2
Photodiode Feedback Connections _________________________________________ 44
4.4.3
Grounding Consideration ________________________________________________46
4.5 Laser Module Operation ____________________________________________ 46
4.5.1
Quick Start ___________________________________________________________ 46
4.5.2
Laser Main Screen _____________________________________________________ 46
4.5.3
Laser Setup Screen _____________________________________________________ 47
4.5.3.1 Mode ______________________________________________________________ 49
4.5.3.2 Bandwidth__________________________________________________________ 50
4.5.3.3 Modulate (MOPA Modules Only) _______________________________________ 50
4.5.3.4 Io Lim_____________________________________________________________50
4.5.3.5 Vcomp ____________________________________________________________ 50
4.5.3.6 Im Lim ____________________________________________________________ 51
4.5.3.7 Po Lim ____________________________________________________________ 51
4.5.3.8 Tol Time and Tol Iop _________________________________________________ 51
4.5.3.9 Intermittent Contact (Int Contact)________________________________________ 51
4.5.3.10
PD Resp _________________________________________________________ 51
4.5.3.11
PD Zero__________________________________________________________52
4.5.3.12
The  and Soft Keys_____________________________________________ 52
4.5.4
Link Conditions _______________________________________________________ 52
5.
Temperature Controller Operation ________________________________53
5.1 Temperature Controller (TEC) Module________________________________ 53
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5.2 TEC Safety Features________________________________________________ 53
5.2.1
Conditions Which Will Automatically Shut Off the TEC Output _________________ 53
5.3 The TEC Connectors________________________________________________ 53
5.3.1
TEC Grounding Consideration ___________________________________________ 54
5.4 TEC Module Operation _____________________________________________ 54
5.4.1
Quick Start___________________________________________________________ 54
5.4.2
TEC Main Screen______________________________________________________ 54
5.4.3
TEC Setup Screen _____________________________________________________ 55
5.4.3.1 Sensor ____________________________________________________________ 56
5.4.3.2 Mode _____________________________________________________________ 56
5.4.3.2.1 Constant Temperature Mode (Const T) _______________________________ 56
5.4.3.2.2 Constant Resistance/Reference Mode (Const R/Const v/Const i)____________ 56
5.4.3.2.3 Constant Current Mode (Const ITE) __________________________________ 57
5.4.3.2.4 Effects of Calibration on TEC modes_________________________________ 57
5.4.3.3 Gain ______________________________________________________________ 57
5.4.3.4 Limits_____________________________________________________________ 58
5.4.3.4.1 TE Current Limit (Limit ITE) _______________________________________ 58
5.4.3.4.2 Temperature Limits (Limit THI and Limit TLO) _________________________ 58
5.4.3.4.3 Resistance/Reference Limits (Limit RHI/vHI/iHI and Limit RLO/vLO/iLO)______ 58
5.4.3.5 Tolerances (Tol Time and Tol Temp) ____________________________________ 58
5.4.3.6 C1, C2, C3, and Ro __________________________________________________ 59
5.4.3.7 The  and Soft Keys ______________________________________________ 59
5.4.4
Link Conditions _______________________________________________________ 59
5.4.4.1 Thermistor and Thermistor Current Selection ______________________________ 60
5.4.4.1.1 Introduction_____________________________________________________ 60
5.4.4.1.2 Thermistor Range ________________________________________________ 60
5.4.4.1.3 Temperature Resolution ___________________________________________ 61
5.4.4.1.4 Selecting Thermistor Current _______________________________________ 62
5.4.4.1.5 Selecting Thermistors _____________________________________________ 62
5.4.4.1.6 The Steinhart-Hart Equation________________________________________ 63
5.4.4.1.7 Table of Constants _______________________________________________ 65
5.4.4.2 AD590 and LM335 __________________________________________________ 66
5.4.4.2.1 General ________________________________________________________ 66
5.4.4.2.2 AD590 Sensor___________________________________________________ 66
5.4.4.2.3 LM335 Sensor___________________________________________________ 67
5.4.4.2.4 Determining C1 and C2 for the AD590 and LM335______________________ 68
5.4.4.3 RTD Sensors _______________________________________________________ 69
5.4.4.3.1 RTD Constants __________________________________________________ 70
6.
Maintenance__________________________________________________71
6.1 Introduction_______________________________________________________71
6.2 Fuse Replacement __________________________________________________ 71
6.3 Cleaning __________________________________________________________ 71
7.
Calibration ___________________________________________________73
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7.1 Calibration Overview_______________________________________________ 73
7.1.1
Environmental Conditions _______________________________________________ 73
7.1.2
Warm-Up ____________________________________________________________73
7.2 Laser Calibration __________________________________________________ 73
7.2.1
Recommended Equipment _______________________________________________ 73
7.2.2
Drive Current Load Resistor Selection______________________________________ 74
7.2.3
Local Operation Current Source Calibration _________________________________ 74
7.2.4
Remote Operation Current Source Calibration________________________________ 75
7.2.5
Local Operation IPD Current Calibration_____________________________________ 76
7.2.6
Remote Operation IPD Current Calibration ___________________________________ 77
7.2.7
Local Operation Laser Voltage Measurement Calibration _______________________ 78
7.2.8
Remote Operation Laser Voltage Measurement Calibration _____________________ 79
7.3 TEC Calibration ___________________________________________________ 80
7.3.1
Recommended Equipment _______________________________________________ 80
7.3.2
Local Operation Thermistor Calibration_____________________________________ 80
7.3.3
Remote Operation Thermistor Calibration ___________________________________ 81
7.3.4
Local Operation AD590 Sensor Calibration__________________________________ 82
7.3.5
Remote Operation AD590 Sensor Calibration ________________________________ 82
7.3.6
Local Operation LM335 Sensor Calibration__________________________________ 83
7.3.7
Remote Operation LM335 Sensor Calibration________________________________ 83
7.3.8
Local Operation RTD Calibration _________________________________________ 84
7.3.9
Remote Operation RTD Calibration________________________________________84
7.3.10 RTD Lead Resistance Calibration (Offset Null)_______________________________ 85
7.3.11 Local Operation ITE Current Calibration ____________________________________ 85
7.3.12 Remote Operation ITE Current Calibration, Single Channel TEC _________________ 86
8.
Factory Service________________________________________________89
8.1 Introduction_______________________________________________________ 89
8.2 Obtaining Service __________________________________________________ 89
9.
Error Messages _______________________________________________93
9.1 Introduction_______________________________________________________ 93
10. Specifications _________________________________________________97
10.1
Laser Diode Driver (LDD) Modules _________________________________ 97
10.2
MOPA Laser Diode Driver Module _________________________________ 98
10.3
Temperature Controller (TEC) Specifications________________________ 100
10.4
Mainframe And General Specifications _____________________________ 101
Tables
Table 1 - Laser Connector Pinouts___________________________________________________41 Table 2 - MOPA Laser Connector Pinouts_____________________________________________41
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Table 3 - Laser Link Conditions ____________________________________________________ 52 Table 4 - TEC Connector Pintouts __________________________________________________ 54 Table 5 - TEC Link Conditions _____________________________________________________ 60 Table 6 - Comparison of Curve Fitting Equations ______________________________________ 64 Table 7 - Thermistor Constants_____________________________________________________ 65 Table 8 - RTD Constants__________________________________________________________ 70 Table 9 - Recommended Test Equipment______________________________________________ 73 Table 10 - Drive Current Load Resistor Selection ______________________________________ 74 Table 11 - Recommended Test Equipment_____________________________________________ 80 Table 12 - Error Codes ___________________________________________________________ 93
Figures
Figure 1 - Model 6000 Front Panel __________________________________________________ 9 Figure 2 - A Sample Screen with Various Data Fields ___________________________________ 13 Figure 3 - Model 6000 Menu Structure_______________________________________________ 14 Figure 4 - Master Display _________________________________________________________ 15 Figure 5 - MOPA Master Display___________________________________________________ 15 Figure 6 - Main Menu ____________________________________________________________ 16 Figure 7 - Configure Menu ________________________________________________________ 16 Figure 8 – System Configure Screen_________________________________________________ 17 Figure 9 - Save/Recall Screen______________________________________________________ 18 Figure 10 - Link Screen___________________________________________________________ 18 Figure 11 - Communications Screen_________________________________________________ 20 Figure 12 - Rear Panel ___________________________________________________________ 21 Figure 13 - 6000 Block Diagram ___________________________________________________ 23 Figure 14 - Laser Module Block Diagram ____________________________________________ 24 Figure 15 - Constant Current - High Bandwidth Mode __________________________________ 26 Figure 16 - Constant Current - Low Bandwidth Mode ___________________________________ 27 Figure 17 - Constant Power Mode __________________________________________________ 28 Figure 18 - TEC Board Module Diagram_____________________________________________ 29 Figure 19 - Microprocessor Board Block Diagram _____________________________________ 33 Figure 20 - Power Supply Block Diagram ____________________________________________ 35 Figure 21 - Laser Diode Protection Circuit ___________________________________________ 40 Figure 22 - Common Laser Cathode / Photodiode Cathode_______________________________ 45 Figure 23 - Common Laser Cathode / Photodiode Anode ________________________________ 45 Figure 24 - Common Laser Anode / Photodiode Cathode ________________________________ 45 Figure 25 - Common Laser Anode / Photodiode Anode __________________________________ 45 Figure 26 - Laser Main Screen _____________________________________________________ 46 Figure 27 - Laser Setup Screens ____________________________________________________ 48 Figure 28 - MOPA Laser Setup Screens ______________________________________________ 49 Figure 29 - TEC Main Screen ______________________________________________________ 54 Figure 30 - TEC Setup Screens_____________________________________________________ 56 Figure 31 - Thermistor Temperature Range ___________________________________________ 61 Figure 32 - Thermistor Resistance versus Temperature __________________________________ 64 Figure 33 - AD590 Nonlinearity ____________________________________________________ 67 Figure 34 - IPD Calibration Circuit __________________________________________________ 76
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CHAPTER 1
1. General Information
1.1 Introduction
This chapter describes the features, options, accessories, and specifications of the Model 6000.
1.2 Product Overview
PRODUCT FEATURES
Two fully isolated module slots, with first module bay user replaceable.  GPIB/IEEE 488.2 and RS-232C Interfaces  Link feature allows inter-module programming control not found in any
other products.
Built-in Temperature Controller (TEC) Module
• Model 6000 and 6000M: 32 Watt (4A/8V), ultra stable bipolar output
• Model 6000MF: 45 Watt (2.5A/18V), ultra stable bipolar output
• Thermistor, AD590, LM335, and Pt RTD sensors Laser Diode Driver (LDD) Modules
• 500 mA to 6 Amp low noise outputs
• External analog modulation
• Adjustable photodiode bias voltage
• Comprehensive laser diode protection features MOPA Driver Module (Model 6000M and 6000MF Only)
• 500 mA oscillator and 4 Amp amplifier low noise outputs
• External analog modulation, with oscillator/amplifier
• Standard SDL DB-15 connector
• Comprehensive laser diode protection features
The Model 6000 Modular Controller is a result of Newport’s continuing commitment to provide advanced laser diode instrumentation at affordable prices.
Advanced designs guarantee that the Model 6000 will accommodate future laser modules making this controller the most complete instrument for laser diode control, characterization, and testing far into the future.
High Power Temperature Controller Fulfills All Your Thermo Electric (TE) Cooling Needs
The 32 Watt Temperature Controller is offered to meet your most demanding TE cooling needs. It may be operated in one of three modes:
Constant Tempe rature
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2 Chapter 1 General Information
Constant Resistance
Constant TE Current
Short term stability is less than 0.0005°C while long term stability is better than
0.001°C. Four sensor types are compatible with this TEC module:
Thermistors
AD590 series
LM335 series
100
Platinum RTDs
With the sensor’s calibration constants, the actual laser diode temperature is displayed in °C on the front panel.
Full Featured LDD Modules Offer Complete Test and Characterization Capabilities
Advanced circuit designs and careful layout of 6500 series modules provide you with an extremely low noise, highly stable output current. Current outputs range from 500 mA to 6 Amps. An external analog modulation input allows precision control of the laser output for a variety of applications including power level control and wavelength tuning. A monitor photodiode may be zero biased for CW low noise applications or reversed biased up to -5 volts for high frequency modulation. All laser diode parameters are accessible with 16-bit resolution including the laser diode’s forward voltage for full characterization using any of the 6500 series modules.
Comprehensive Safety Features Protect Your Laser Diode
Time tested laser diode protection safety features are incorporated into every Laser Diode Driver offered. Input power module filters provide first stage protection against transients. Additional filtering and power regulation stages coupled with high speed transient detection circuits let you operate your laser diode worry free from transients. A slow turn-on sequence, multiple output shorting circuits, and an independent current limiting feature provide the superior protection you demand from all your laser diode instrumentation.
Intuitive Controls and Character LCD Display Simplify Control and Test Procedures
Improved data presentation and system control are achieved using a character LCD display. A MASTER display shows the entire system configuration as well as each module’s status. “Soft Keys” guide you through initial system setup routines and the operation of each module. Real-time control of an output is accomplished either by
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Chapter 1 General Information 3
entering the set point via the cursor keys or control knob. MENU and FUNC keys access saved system configurations and repetitive procedures. All controls are clearly marked and instructions easily understood for simple operation.
GPIB/IEEE-488.2 and RS232 Interfaces Gives Power to Remotely Control and Collect Data.
For ultimate control a GPIB/IEEE-488.2 interface is available. All control and measurement functions are accessible via the GPIB interface. In addition, standard serial RS-232C ports allow simpler interfacing to a PC. As your instrumentation needs change the Model 6000 Modular Controller will adapt to all your new laser diode applications giving you the ultimate in flexible laboratory equipment.
1.3 Available Options and Accessories
Model 6000 Modular Controller Mainframe
Model 6000 Laser Diode Driver (LDD) Modules 6505 500 mA Laser Diode Driver Module 6510 1,000 mA Laser Diode Driver Module 6530 3,000 mA Laser Diode Driver Module 6560A 6,000 mA Laser Diode Driver Module 6540M 4,000 mA/500mA MOPA Laser Diode Driver Module
Accessories 300-02 Temperature Controller Cable 300-04 Temperature Controller/Mount Cable
300-16 10.0 k
thermistor (± 0.2°C) 300-22 AD592CN IC Sensor 500-02 Laser Diode Driver Cable 500-04 Laser Diode Driver/Mount Cable 6000-RACK Rack Mount Kit
Newport Corporation also supplies temperature controlled mounts, lenses, and other accessories. Please consult with your representative for additional information.
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4 Chapter 1 General Information
1.4 Safety Terms and Symbols
1.4.1 Terms
The following safety terms are used in this manual:
The
WARNING
heading in this manual explains dangers that could result in
personal injury or death.
The
CAUTION
heading in this manual explains hazards that could damage the
instrument.
In addition, a
NOTES
heading gives information to the user that may be beneficial in
the use of this instrument.
1.4.2 Symbols
The following symbols are used in this manual and on the instrument:
!
Refer to the documentation.
Earth Ground
1.5 General Warnings and Cautions
The following general warning and cautions are applicable to this instrument:
WARNING
This instrument is intended for use by qualified personnel
who recognize shock hazards or laser hazards and are
familiar with safety precautions required to avoid possible
injury. Read the instruction manua l thoroughly before
using, to become familiar with the instrument’s operations
and capabilities.
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Chapter 1 General Information 5
WARNING
The American National Safety Institute (ANSI) states that a shock hazard exists when probes or sensors are exposed
to voltage levels greater then 42 VDC or 42V peak AC.
Do not exceed 42V between any portion of the Model
8000 (or any attached detector or probe) and earth ground
or a shock hazard will result.
CAUTION
There are no serviceable parts inside the Model 8000.
Work performed by persons not authorized by Newport
Corporation may void the warranty. For instructions on
obtaining warranty repair or service please refer to
Chapter 8 of this manual.
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7
CHAPTER 2
2. System Operation
2.1 Introduction
This chapter describes how to operate the 6000 mainframe. Module specific details can be found in the module's manual. Unless otherwise noted, “6000” or “Model 6000” refers to the Model 6000, the Model 6000M, and the Model 6000MF. Sections that deal with a specific model will be indicated as such.
2.2 Installation
CAUTION
Although ESD protection is designed into t he 8000, operation in a static-fee work area is recommended.
CAUTION
Do not plug-in or unplug a mod ule with
the AC power on.
2.2.1 AC Power Considerations
The 6000 can be configured to operate at a nominal line voltage of 100, 120, 220, or 240 VAC. Normally, this is done at the factory and need not be changed before operating the instrument. However, be sure that the voltage setting is correct on the power input module and correct fuses are installed per section 6.2 before connecting to an AC source. The 6000 is shipped set for 120 VAC and a caution sticker is placed on the input power connector.
CAUTION
Do not exceed 250 VAC on the line input.
Do not operate with a line voltage that is not within ±10%
of the line setting. Too low of an input voltage may cause excessive ripple on the DC supplies. Too high of an input
voltage will cause excessive heating.
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8 Chapter 2 System Operation
WARNING
To avoid electrical shock hazard, connect the
instrument to properly earth-grounded, 3-prong
receptacles only. Failure to observe this precaution
can result in severe injury or death.
2.2.2 Tilt-Foot Adjustment
The 6000 has front legs that extend to make it easier to view the LCD display. To use them, place the 6000 on a stable base and rotate the legs downward until they lock into position.
2.2.3 Rack Mounting
The 6000 may be rack mounted by using a 6000 rack mount kit. All rack mount accessory kits contain detailed mounting instructions.
2.2.4 Ventilation Requirements
Rear panel area needs 2 to 4 inches of clearance for air circulation.
2.2.5 Power-Up Sequence
With the 6000 connected to an AC power source, set the power switch to “I” to supply power to the instrument and start the power-up sequence.
During the power-up sequence, the following takes place. For about 5 seconds an initialization screen is displayed. The software version is displayed in the lower left corner of the screen. During this time a self-test is performed to ensure that the 6000 hardware and software are communicating. If the 6000 cannot successfully complete this test, an error message will be displayed.
After this test, the 6000 is configured to the state it was in when the power was last shut off and displays the master display.
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Chapter 2 System Operation 9
2.3 Introduction to the 6000 Front Panel
2.3.1 Model 6000
Described below are the functions of each area of the Model 6000 front panel, as shown in Figure 1. See the following section for the Model 6000M and 6000MF.
Figure 1 - Model 6000 Front Panel
1.
Power On/Off Switch
- Switches on/off the AC power to the unit.
2.
Laser Enable On/Off Switch
- Safety key-switch that enables/disables laser
output. See sections 3.6 and 4.3.4 for additional information on laser interlock.
3.
Laser Active LED
- Indicates laser output is on.
4.
LDD On Button
- Turns the laser output on/off.
5.
TEC Active LED
- Indicates TEC output is on.
6.
TEC On Button
- Turns the TEC output on/off.
7.
Display Soft Keys
- These are the two dark keys located to the right of the display. T he function of these keys varies depending on what menu is displayed. See section 2.4.1.4 for a complete description of soft keys.
8.
MASTER Key
- switches to the master display from any screen in the system
(see section 2.4.2).
9.
Cursor Control Keys
- Moves cursor up or down between editable data fields. The left arrow decrements values in numerical entry fields, or as a previous choice in a multi-choice entry field. The right arrow increments values in numerical entry fields, or as a next choice in multi-choice entry fields. See section 2.4.1.3 for a description of data fields.
10.
MENU Key
- Switches to the main menu from any screen in the system (see
section 2.4.6).
11.
FUNCTION Key
- Used to execute user macros and special functions (see
section 2.4.2).
12.
SHIFT Key
- Toggles between the outer and inner set of soft keys.
13.
Remote LED
- Indicates 6000 is in remote mode.
14.
Knob
- Used to continuously vary certain parameters. The knob has an
acceleration factor that causes the rate of change to increase as the knob is turned
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10 Chapter 2 System Operation
faster. Turning slowly allows for a fine adjustment at the smallest displayed decimal place.
2.3.2 Model 6000M and 6000MF
The only physical difference on the front panel for the Model 6000M and Model 6000MF is the TEC On button has been replaced by the MOPA Amplifier On button, which allows independent control of each MOPA channel, and the LDD On button has been renamed to OSC On button. The TEC On button was moved to the lower soft key on the Master Display.
Only elements that differ on the 6000M and 6000MF are described below. See the section above for a description of the other elements on the front panel.
3.
Oscillator Active LED
- Indicates MOPA oscillator output is on.
4.
OSC On Button
- Turns the MOPA oscillator output on/off.
5.
Amplifier Active LED
- Indicates MOPA amplifier output is on.
6.
AMP On Button
- Turns the MOPA amplifier output on/off.
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Chapter 2 System Operation 11
2.4 General Operation
2.4.1 Display Elements
The Model 6000 uses a character display to depict information about the current state of the system. The display can be broken down into four basic elements: static fields, non-editable data fields, editable data fields, and soft key labels.
2.4.1.1 Static Fields
Static fields are elements on the display which do not change from moment to moment. These can include screen titles and error messages.
2.4.1.2 Non-Editable Data Fields
Non-editable data fields are used mainly to display read back information, such as temperature, laser current, etc. These fields can have a prefix or suffix label, such as “
Io=
” or “mA”, and are periodically updated by the system.
2.4.1.3 Editable Data Fields
Editable data fields are used for module and system settings such as current set point, temperature set point, display contrast, etc. An editable field has three distinct display states: focused, non-focused, and read-only.
The focused state indicates that the field has the input “focus.” When the a field has the focus, a right pointing arrow () is placed to the left of the field. Any keyboard entry or knob adjustment will be applied to the field, and only one field at a time on the display can have focus. Move between fields using the up and down arrow keys.
The non-focused state indicates that the field is editable, but does not currently have the focus. These fields are indicated with a right pointing triangle () to the left of the field. Using the up and down arrows, focus can be moved to these fields.
When the editable data field is in the read-only state, it looks and acts exactly like a non-editable data field. Like the non-editable data field, it cannot have focus, and the up or down arrow keys will skip over the field. This state is used primarily to lockout specific data elements from front panel change when the Model 6000 is in remote mode. Any IEEE-488 or RS-232 communication will place the unit in remote mode, and editable fields that are protected during remote operations change to the read only state.
2.4.1.3.1 Changing Data Fields
A data field can only be changed from the front panel when the field is the focus. Some fields are numeric-based, such as current set point or temperature limits. Other
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12 Chapter 2 System Operation
fields are multi-choice fields, such as Yes/No fields. Both types are changed with the left and right arrows or the knob.
2.4.1.4 Soft Keys
Soft key labels are labels for the two gray buttons located to the immediate right of the display. Each label either indicates the action that is performed when the corresponding key is pressed (such as changing screens), or the state of a data element in the system (such as laser PD zero). In the first case, pressing the corresponding soft key will cause the action to happen, such as changing to the setup screen when the
Setup
soft key is pressed from a module’s main screen. In the second case, pressing the soft key will change the associated state, such as setting the laser’s PD zero value.
Like the editable data fields above, certain soft keys are programmed to enter a “display-only” mode when the unit enters remote mode. Display-only soft keys are displayed in lower case, and will not function until the unit returns to local mode.
On some screens, such as the main menu, there are more than two soft key selections. In this case, the active soft keys have a left pointing arrow () to the right of the soft key label. Pressing the
SHIFT
key will toggle between the outer and inner two soft
keys.
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Chapter 2 System Operation 13
Figure 2 - A Sample Screen with Various Data Fields
2.4.2 Function Keys
The
FUNC
button serves two purposes on the 6000: first, as a quick navigation method that speeds switching between laser module and TEC screens; and second, as a method of setting up and executing user defined macros and special functions.
Using the
FUNC
key for navigation allows the user, with two or three keystrokes, to switch to the single display of either the laser module or TEC section. This works simply by pressing the
FUNC
button and then pressing the top soft key for the laser, or the bottom soft key for the TEC. For example, to switch to the single screen display of the laser, press and release
FUNC
and then press the top soft key. This
quick navigation works anywhere in the system.
For macros and special functions, the
FUNC
key is used both to execute and to enter the setup screen on the particular function. For example, if the 6000 supported a special function assigned to the up arrow key, to enter the setup screen of this function, pr ess and hold the
FUNC
key, then press the up arrow key, then release both. This would enter the setup screen for this function. To execute this function, press and release the
FUNC
key, then press and release the up arrow key. If functions are not setup/supported for a particular key, the 6000 will beep. The 6000 supports assignment of macros to the arrow keys, the
MASTER
key, the
MENU
key, the
LDD
key, and the
TEC
key.
LDD
→→→→
Io= 450.00 mA Po= 0.00 mW TEC

Ts= 25.00 °C
T = 23.50 °C
S
tatic Field
Non-editable data field
Focused editable data field
Non-focused editable data field
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14 Chapter 2 System Operation
2.4.3 Menu Structure
Figure 3 - Model 6000 Menu Structure
Master Display
Modules
Main Menu
System
Configure Menu
Save/Recall
Linking
Communications
Local
Setup
Calibration
TEC
Laser/M OPA Osc
Setup
MOPA Amp
Setup
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Chapter 2 System Operation 15
2.4.4 Master Display
The Master Display is shown in Figure 4. This is the highest level display and indicates the general status of both the laser module and TEC in the system at the same time.
LDD
→→→→
Io= 450.00 mA Po= 0.00 mW TEC

Ts= 25.00 °C
T = 23.50 °C
Figure 4 - Master Display
The Master Display can be accessed from any screen in the system by pressing
MASTER
. If there is no laser module detected in the system, the text “Not installed”
will appear in place of the laser module’s status information.
2.4.5 MOPA Master Display
OSC
→→→→
Io= 1.66 mA
AMP Im= 0.0 µA

Io= 741.6 mA
TEC T = 25.00 °C OFF
Figure 5 - MOPA Master Display
The MOPA Master Display is used on Model 6000M and 6000MF controllers. The Master Display can be accessed from any screen in the system by pressing
MASTER
. The lower soft key controls the TEC on/off state. The soft key indicates
the current state of the TEC output.
2.4.6 Main Menu
The Main Menu is shown in Figure 6. This is the second highest menu and is used to access four general system functions:
TEC On/Off soft key
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16 Chapter 2 System Operation
1.
MODULES
- Pressing the adjacent soft key gives access to the laser module and TEC for setup and control of each module.
2.
COMM
- Pressing the adjacent soft key gives access to
the GPIB and RS232 parameters.
3.
LOCAL
- When the unit is in remote mode, either
through GPI B or RS-232C communications, the
Local
soft key will be available. Pressing it returns the 6000 to a local state. When in local mode, this key does not appear on the display. The 6000 is placed in remote mode through GPI B or RS232 communication, or during the execution of a macro or special function.
4.
CONFIG
- Pressing the adjacent soft key gives access to the general configuration menu, with soft keys to access system configure, save/recall, linking, and calibration screens.
Main Menu MODULES
←←←←
COMM LOCAL CONFIG
←←←←
Figure 6 - Main Menu
2.4.7 Configure Menu
The configure menu provides access to the system configuration, save and recall, and linking screens.
Config SYSTEM
←←←←
LINKING CAL SAV/RCL
←←←←
Figure 7 - Configure Menu
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Chapter 2 System Operation 17
2.4.8 System Configure Screen
→→→→
Contrast= 11 %

Brightness= 100 %

Lockout dial= No

Lockout pad= No
→→→→
Audible beep= Yes


On Delay= 3.0 S

Key Rate= Fast

Dial Rate= Fast
Figure 8 – System Configure Screen
The system configure screen controls basic operation of the 6000 system.
Brightness
varies the backlighting intensity.
Contrast
is used to optimize the viewing angle.
Lockout dial
disables the dial to avoid accidental changes in active data fields when
the dial is bumped.
Lockout pad
locks out the left and right arrow keys, the data entry portion on the
keypad. Navigation keys, such as up and down,
MENU, MASTER
, and
FUNC
continue to work.
Note that both the Lockout dial and Lockout pad settings are temporarily suspended while in the Configure System Screen, allowing the dial and keypad lockout settings to be changed while in this screen..
Audible Beep
controls the system’s audible beeper. The beeper indicates errors, invalid data entry, and other situations where the 6000 needs to alert the user. Each press of the
MASTER
button will clear one error.
On Delay
controls the delay time from the moment a Laser Diode Driver is turned on by the user to the actual time the output is energized. The delay time is programmable from 0 seconds to 30 seconds. The default setting is 3 seconds.
Key Rate
- this controls the speed at which, when a key is held down, it repeats.
Settings are
Slow, Medium
, and
Fast
.
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18 Chapter 2 System Operation
Dial Rate
- like the
Key Rate
setting, this controls the acceleration of the dial as it is
turned. Settings are
Slow, Medium
, and
Fast
.
2.4.9 Save/Recall Screen
Save/Recall SAV
→→→→
Bin=1
RCL
Figure 9 - Save/Recall Screen
The Save and Recall functions are used to store and retrieve 6000 setup configurations for future use. For example, a specific test setup may be saved for later use, and then another setup may be used presently. Then, when the user desires to perform the specific test, its setup is simply recalled.
Non-volatile memory is used for saving the instrument parameters. When a save operation is performed, all of the parameters which are currently in effect on the 6000 are stored. The user selects a “bin” number (1 - 5) for saving the parameters. Then, when that “bin” number is recalled, the 6000 is restarted and the parameters are reconfigured to the previously stored values.
A special “bin 0” is reserved for the reset state. Recalling bin 0 will reset all modules in the system to factory defaults.
The save/recall bin information will be lost upon detecting any change in the module configuration (such as installing a new module).
2.4.10 Linking Screen
# Sr Cnd Act Tg A
→→→→
1

On

n5

2 PREV
B

No CLR
C

No
Figure 10 - Link Screen
The linking screen allows the conditions of the laser module and TEC to affect and control each other.
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Chapter 2 System Operation 19
The headings were abbreviated because of space limitations, and the full names are Source, Condition, Action, and Target. In addition, the condition and action values were also abbreviated. See the tables below for the full text of each abbreviation:
Laser Conditions
TEC Conditions
Abbrev
Full Text
Abbrev
Full Text
On
On
On
On
Off
Off
Off
Off
Out
Out of tolerance
Out
Out of tolerance
In
In tolerance
In
In tolerance
IoL
Current limit
I L
Current limit
VfL
Voltage compliance limit
V L
Voltage limit
ImL
Photodiode current limit
T L
Temperature limit
PoL
Photodiode power limit
ThL
Temperature high limit
Lck
Interlock open
TlL
Temperature low limit
Opn
Open circuit
R L
R limit
Sho
Short circuit
Opn
Module or sensor open
Actions Abbrev
Full Text
Off
Turn off
f#
Turn off in # seconds
On
Turn on
n#
Turn on in # seconds
The
CLR
soft key allows clearing of all defined links. To clear a single link, simply
change the source field to No. The system supports up to 24 links.
Each condition is evaluated approximately once per second. Links are edge triggered, which means that the action of a link is done the first time the condition goes true, not whenever the condition is true. The action will not be done a second time until the condition first goes false and then returns to true.
As an example of linking, consider a system where the TEC module cannot operate when the laser is off because condensation will form on the laser and may damage it. However, the TEC must be turned on whenever the laser is on to protect it from overheating. First, program the TEC high and low temperature limits to the operating range of the laser. The following three links will then ensure these conditions are met:
#
Source Condition Action Target
A 1 On Turn On 2
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20 Chapter 2 System Operation
B 1 Off Turn Off 2 C 2 T Lim Turn Off 1
Link #1 turns on the TEC whenever the laser is on. Link #2 turns off the TEC whenever the laser is off. Link #3 turns off the laser if the TEC exceeds its temperature limits. There is no need to define a fourth link to turn off the TEC on a T Lim condition because if Link #3 turns off the laser, Link #2 will automatically turn off the TE C.
As shown in the example above, it is possible to setup a level of control that would normally only be possible with a computer-based monitoring system.
When the unit enters remote mode, the linking screen is not accessible.
2.4.11 Calibration Screen
Pressing the
Cal
soft key displays a module selection screen exactly like the screen
shown after pressing the
Modules
soft key from the main menu. Press the upper soft key for the laser or the lower soft key for the TEC. On Model 6000M and 6000MF controllers, a second selection screen will appear to select the oscillator or amplifier section of the MOPA module. The calibration screen is then displayed. See sections
7.2 and 7.3 for Laser and TEC calibration, respectively.
2.4.12 Configure Communications Screen
→→→→
Err While Rmt= No

GPIB Address= 4

Speed= 9600 Baud

Terminal Mode= No
Figure 11 - Communications Screen
The
GPIB Address
is the IEEE-488 device address assigned to the 6000. Valid addresses are 1 to 31. See the Computer Interfacing Manual for additional information on
Terminal Mode
and
Speed
.
2.4.12.1 Error Message Control
Error messages may appear on the display when error conditions occur which force the output off or reflect hardware errors in the 6000. Chapter 9 contains an explanation of the error message which may be reported by the 6000. Display of error messages on the 6000 screen may be disabled while in remote mode by setting
Err While Rmt
to No, or by using the GPIB command
REMERR
to set this value
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Chapter 2 System Operation 21
remotely. Errors will continue to accumulate in the error queue, but will not be displayed on-screen.
2.5 Rear Panel Familiarization
Figure 12 - Rear Panel
2.5.1 GPIB Connector
The GPIB connector, located on the back panel, allows full remote control as described in the Computer Interfacing Manual. It accepts a standard IEEE-488 cable for remote control, and uses Metric lock screws.
2.5.2 RS-232 Connector
The 6000 has an RS-232 connector located on the back panel. See the Computer Interfacing Manual for a more complete description of the RS-232 interface.
2.5.3 Input Power Connector
Accepts a standard line cord for AC input. Also selects one of four AC input settings: 100V, 120V, 220V, and 240V. The cord must be removed to change the setting. A small screwdriver will open the top of the module and expose the rotary switch. Select the range that is closest to your expected nominal RMS line voltage. The voltage selection is set for 120 VAC prior to shipping. A caution sticker is then placed over the input power connector to help insure the customer checks for proper voltage.
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22 Chapter 2 System Operation
CAUTION
Do not exceed 250 VAC on the line input.
Do not operate with a line voltage that is not within ±10%
of the line setting. Too low of an input voltage may cause excessive ripple on the DC supplies. Too high of an input
voltage will cause excessive heating.
2.5.4 GND Post
Provides access to chassis ground, which is also an earth ground as long as a standard 3-wire line cord is used. This is a protective conductor terminal to be used to achieve chassis grounding requirements when the main connectors don’t provide an earth ground terminal. Use a minimum of 18 gauge wire to connect to this terminal.
2.6 Warm Up and Environmental Consideration
Operate the 6000 at an ambient temperature in the range of 0 to +40°C. Storage temperatures should be in the range of -20 to +60°C. To achieve rated accuracy, let the 6000 warm up for 1 hour. For greatest accuracy, recalibrate when ambient temperature changes more than a few degrees.
CAUTION
Operating above +40°C can cause excessive heating and
possible component failures.
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23
CHAPTER 3
3.
Principles of Operation
3.1 Introduction
A functional block diagram of the 6000 is shown in Figure 13. In each of the following sections there are functional block diagrams for the various circuit boards of the 6000.
GPIB/RS232
Front Panel
Microprocessor
Parallel Bus
Serial Bus
Laser
Optical
Interface
Laser
Control
Laser
Output
TEC
Optical
Interface
TEC
Control
TEC
Output
TEC Module
Laser Module
Main
Power
Supply
Module
Supply
Module
Supply
Power Supplies
Laser
TEC
Figure 13 - 6000 Block Diagram
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24 Chapter 3 Principles of Operation
3.2 Laser Module Theory of Operation
Figure 14 shows the functionality of the Laser Module. The following sections detail the theory of operation for each of the blocks in Figure 14.
The circuit block diagrams for each laser mode of operation are shown in Figure 15, Figure 16, and Figure 17. The theory of operation for each mode of operation is discussed in Sections 3.2.9 - 3.2.11.
Optically
Isolated
Serial
Bus
icroprocessor
To
Limit DAC
Fault Monitors
A/D Converter
Output On/Off
and
Slow Turn-On
Unregulated DC
Voltage
Regulator
Pass
Transistor
Output
Shorting
Output
Laser
Current
Sensing
Diode
Current
Feedback
Set Point
DAC
Modulation
Input Port
Photodiode
+
-
Voltage
Sensing
Figure 14 - Laser Module Block Diagram
3.2.1 Laser Interface
The laser interface provides optically isolated serial communications between the laser board and the microprocessor. Control signals are passed to the laser board to set the laser board status, current limit, current set points, and photodiode feedback functions. Instructions and data are sent over the serial interface to the optical barrier. Status and data are serially passed back to the microprocessor.
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Chapter 3 Principles of Operation 25
3.2.2 Limit DAC
The microprocessor loads the current limit value into the 12-bit DAC. The Limit DAC converts a digital limit signal from the microprocessor to a voltage which becomes the Limit Set Point voltage for the Output Stage. The current limit value is updated at power-up, at a "bin" recall, and whenever a LIM I value is changed.
3.2.3 Set Point DAC
The microprocessor loads the current set point value into the 16-bit DAC. The Set Point DAC converts a set point value from the microprocessor to a voltage which becomes the current or I
PD
set point input to the laser output stage. The laser current set point value is updated at power-up, at a "bin" recall, and whenever a laser set point value is changed.
3.2.4 A/D Converter
The 16-bit A/D converter measures the limit current, actual current, and photodiode current.
3.2.5 Current Source Voltage
The current source voltage is formed by taking the unregulated DC volt age from the power supply and passing it through a regulator and the associated circuitry.
3.2.6 Output Shorting
A relay shorts the LD ANODE and LD CATHODE terminals whenever the laser output is turne d off. At the same time a FET is switched on to shunt any current which may appear at the output. When the laser outp ut is turned on, t he shunt circuit and short are removed gradually, and in two stages. This ensures transient protection of the laser output.
3.2.7 Modulation/Voltage Control Input Port
The rear panel MOD input connector drives a precision wide-band instrumentation amplifier allowing the differential control signal applied to this port to use a different ground than the laser output terminals. However, due to the input common-mode voltage restrictions the MOD input should be within ±10 volts of the laser output terminals.
Each 100 mV change in the modulation input is equal to 1% of the maximum drive current of the module. For example, 100 mV input on a 6560A module (6 A driver) would equate to 60 mA of drive current. However, regardless of the input voltage, the current cannot exceed the current limit.
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26 Chapter 3 Principles of Operation
3.2.8 Photodiode Feedback Amplifier
Photodiode feedback is amplified by a precision instrumentation amplifier. When constant Power mode is selected, the photodiode feedback signal is used to control the laser output.
3.2.9 Constant Current, High Bandwidth Mode
This mode of laser operation is shown in Figure 15. In this mode, current feedback is used to control the laser output. The bandwidth is between 50 kHz and 500 kHz, depending on the model.
3.2.10 Constant Current, Low Bandwidth Mode
This mode of laser operation is shown in Figure 16. In this mode, current feedback is used to control the laser output.
In this mode, capacitors are switched into the circuit. These capacitors act as a filter and therefore prevent the laser output from changing too rapidly. This gives added laser diode protection. This also limits the laser output bandwidth to about 10 kHz. In the Low Bandwidth - CW mode, the bandwidth is further limited to 30 Hz.
Unregulated DC
Voltage
Regulator
Pass
Transisto r
Modulation
Input Port
Current Set Point
Laser Diode
Current
Sense
Output
Shorting
Figure 15 - Constant Current - High Bandwidth Mode
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Chapter 3 Principles of Operation 27
Unregulated DC
Voltage
Regulator
Pass
Transistor
Modulation Input
Curre nt S e t Po in t
Laser Diode
Output
Shorting
Current
Sense
Figure 16 - Constant Current - Low Bandwidth Mode
3.2.11 Constant Power Mode
In constant P mode the laser circuit is configured as shown in Figure 17. Photodiode feedback is used to control the laser output and the bandwidth is held low.
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28 Chapter 3 Principles of Operation
Unregulated DC
Voltage
Regulator
Pass
Transistor
Modulation Input
Current Set Point
Laser Diode
Photodiode Input Amp
+
-
Output
Shorting
Current
Sense
Figure 17 - Constant Power Mode
Page 39
Chapter 3 Principles of Operation 29
3.3 TEC Module Theory of Operation
Figure 18 shows the functionality of the TEC module. The following sections detail the theory of operation for each of the blocks in Figure 18.
Optically
Isolated
Serial Bus
Bipolar Output
Stage
Limit DAC
Proportional Amp
Integral Amp
Differential
Sensor
Select and
TEC
Sensor Lines
A/D
Converter
Limit Set Point
PI Loop
Set
Set Point
DAC
Actual
Heat/Cool Lines
Current
Amps
Amp
To Microprocessor
Figure 18 - TEC Board Module Diagram
3.3.1 TEC Interface
The TEC interface provides optically isolated serial communications between the TEC board and the microprocessor. Control signals are passed to the TEC board to set the TEC board status, current limit, and temperature set points. Instructions and data are sent over the serial interface to the optical barrier. Status and data are serially passed back to the microprocessor.
3.3.2 Limit DAC
The microprocessor loads the digitally stored current limit value into the current limit 12-bit DAC. The Limit DAC converts the digital limit signal from the microprocessor to a voltage which becomes the limit voltage for the Bipolar Output
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30 Chapter 3 Principles of Operation
Stage. The current limit value is updated at power-up, at a "bin" recall, and whenever the LIM I
TE
value is changed.
3.3.3 Set Point DAC
The microprocessor loads the digitally stored current set point value into the set point 16-bit DAC. The Set Point DAC converts a digital set point signal from the microprocessor to a voltage which becomes the set temperature input to the PI control loop. The TEC current set point value is updated at power-up, at a "bin" recall, and whenever a TEC set point value is changed.
3.3.4 A/D Converter
The 16-bit A/D converter measures the sensor voltage and the current of the bipolar output stage. The sensor measurement is used by the microprocessor in the calculation of temperature or thermistor resistance. The current measurement is used for the I
TE
value.
3.3.5 Sensor Select
Sensor selection is accomplished in the Sensor Select block of the TEC board. Precision 100µA and 10µA current sources may be selected for thermistor control. RTD, LM335 and AD590 IC temperature sensors may also be selected. The AD590 has a +5 VDC bias voltage, the LM335 has a 1 mA bias current, and the RTD has a precision 1 mA current source.
The output of the Sensor Select block of the TEC board is a voltage which is proportional to the actual temperature. This voltage is fed to the A/D converter which provides a digital measurement to the microprocessor, and to the PI control loop to close the feedback loop when temperature is being controlled.
3.3.6 Difference Amplifier
Differential amp provides a proportional difference signal to the PI control. This signal is the difference between set temperature and actual temperature voltage.
3.3.7 Proportional Amplifier and Integrator
The proportional amplifier is part of a digitally controlled gain stage consisting of the analog switches and their associated resistors. The analog switches vary the ratio of resistance in the feedback circuit to change the gain.
The signal from the difference amplifier is sent to an integrator which reduces the difference between the set point temperature and the actual temperature to zero, regardless of the gain setting. An analog switch discharges the integrating capacitor whenever integration is not required to prevent unnecessary difference signal integration.
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Chapter 3 Principles of Operation 31
3.3.8 Bipolar Output Stage
The Bipolar Output Stage consists of circuits which limit the TEC output, sense the TEC output polarity, sense voltage and current limit conditions, as well as supply the bipolar TEC output. The following sections discuss these functions of the Bipolar Output Stage.
3.3.8.1 Current Limiting
The output of the proportional amplifier and integrator together form the control signal. Output current limiting is effected by bounding the control signal so that it is always less than the limit current. The limit current is set with the front panel controls or through the GPIB. The bipolar current limit levels are established by the output of the current Limit DAC.
3.3.8.2 Current Limit Condition Sensing
Comparators sense the output to determine when output current limiting is occurring. When this condition occurs, the I Limit signal is sent to the microprocessor.
3.3.8.3 Voltage Controlled Current Source
The bounded output control signal is applied to an amplifier. This amplifier and the current sensing amplifier form the output voltage controlled current source. The output of this stage directly drives the externally connected TE cooler module.
3.3.8.4 Voltage Limit Condition Sensing
Comparators sense the output to determine when the TEC output compliance voltage limiting is occurring. This condition occurs whenever the TEC output is open or connected to a high resistance. If this condition occurs, the V Limit error signal is passed to the microprocessor.
3.3.9 TEC Control Modes
The 6000 provides three control modes for operation, constant T (temperature), constant R (resistance, voltage, or curr ent), and co nst ant I
TE
(current) modes. Each
of these modes is discussed in the following sections.
3.3.9.1 T Mode
In constant T mode the TEC is driven to the set point temperature. This temperature is monitored by the sensor in the TEC. In the case of a thermistor sensor, the thermistor's resistance is used to determine TEC's temperature by using the Steinhart­Hart conversion equation. The resistance is determined by measuring the voltage across the thermistor (with a known current of 10µA or 100µA). The I
TE
current is also measured and saved. The TEC's output current is sensed across a resistor and the voltage is converted to an ITE current value.
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32 Chapter 3 Principles of Operation
When an LM335 sensor is used, a two-point conversion equation is used to determine the temperature. Its voltage is measured as well as the I
TE
current.
When an AD590 sensor is used, another two-point conversion equation is used to determine the temperature. Its reference current is sensed across a resister, and this voltage is measured. The I
TE
current is also measured.
3.3.9.2 R Mode
In constant R mode, the TEC is driven to the set point resistance, voltage, or current. This resistance, voltage, or current is measured and converted to a temperature. The I
TE
current is also measured.
3.3.9.3 I
TE
Mode
In constant I
TE
mode, the TEC is driven with a constant current, at the ITE set point
value. The I
TE
current is sensed across a resistor and the voltage is converted to ITE
current.
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Chapter 3 Principles of Operation 33
3.4 Microprocessor Board
The Microprocessor Board contains the microprocessor, memory, the serial interface to the TEC and Laser Modules, front panel interface, and circuitry which monitors the AC line voltage and saves the state of the 6000 at power down. The block diagram of the Microprocessor Board is shown in Figure 19.
Power Failure
and Watch Dog
Failure Detection
80188 EB
Microprocessor
RAM ROM
EEPROM
Data Bus
Address Bus
Module
Interface
Front Panel
Interface
GPIB
Interface
RS 232
Interface
To GPIB Port
To Front Panel RS 232 Ports To Modules
Power Fail/Reset
Watchdog Reset
Figure 19 - Microprocessor Board Block Diagram
3.4.1 Microprocessor
The 6000 uses a CMOS 80188EB microprocessor to control its internal operations. The 6000 provides a fail-safe timer which generates a reset in the event of a malfunction. A 1 Hz watch-dog pulse is normally present. If for any reason this clock pulse fails to appear it will reset the 6000.
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34 Chapter 3 Principles of Operation
3.4.2 Memory
The 6000 uses three types of memory. RAM memory is retained only while power is applied to the unit. ROM memory contains the firmware. The third type of memory is electrically erasable programmable memory: EEPROM.
EEPROM stores calibration constants and other data which must be retained even when power is removed from the unit, and does not require battery backup. Examples of data stored in this memory include the TEC and laser parameters and calibration constants.
3.4.3 Serial Interface
The 80188 communicates with the TEC and laser modules through a serial. Parallel data from the microprocessor is converted to bi-directional serial data at the asynchronous serial interface. Also provided is the RS-232 communication.
3.4.4 Front Panel Interface
Provides parallel communication with the front panel.
3.4.5 GPIB Interface
Provides parallel communication with the GPIB port.
3.5 Power Supplies
AC power is suppl i ed through the rear panel i nput power connector which provides in-line transient protection and RF filtering. The input power connector contains the fuses and the switch to select series or parallel connection of the transformer primaries for operation at 100 VAC, 120 VAC, 220 VAC, or 240 VAC.
3.5.1 Module Power Supplies
There are two separate module power supplies, one for each module which contains the laser driver and TEC controller. These linear supplies provide analog and digital circuit power to each module as well as laser/TEC drive and photodiode bias.
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Chapter 3 Principles of Operation 35
Rectifiers
and Filters
Regulators
Transformer
Rectifiers
and Filters
Regulators
Transformer
Rectifiers
and Filters
Regulators
LDD Module
Supply
TEC Module
Supply
Main
Supply
Power Entry
Module
Figure 20 - Power Supply B lock Diagram
3.5.2 Main Supply
This supply provides digital circuit power for all functions except the laser module and TEC. It also provides fan power.
3.6 Interlock Operation
The back panel laser input/output connector has interlock connections which must be connected before the laser output will be enabled. See section 4.3.4 for additional information.
3.6.1 Laser Interlock
On the laser input/output connector pins 1 and 2 form the interlock path. If there is not a connection between these pins the laser output will not be enabled. When this path is broken, the laser Interlock Error condition/event will be reported in the laser Condition Status Register and the Laser Event Status Register.
This interlock is a safety feature for laser protection. It requires that the connecting cable be secure before the laser output is enabled. A secure connection significantly reduces the possibility of an intermittent open circuit to the laser drive current.
Page 46
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37
CHAPTER 4
4. Laser Diode Driver Module Operation
4.1 Laser Diode Driver Module
4.1.1 Introduction
The 6500 Series laser modules are precision current source modules for use in the 6000 Modular Controller.
Features of the 6500 Series include:
Service-free modularity (calibration information is stored on the module)
Closed-case calibration
High-stability, low noise design
Flexible setup with 6000 Save/Recall front panel functions
Photodiode feedback control mode
Modulation input
Fault detection
Current and voltage limiting
Special Configurati on for MOPA La sers (65xxM modules)
4.1.2 Installation
This section describes the procedures for installing and removing a module from the
6000.
NOTE
The save/recall bin information will be lost upon detecting
any change in the module configuratio n (such as installing
a new module).
CAUTION
Although ESD (electrostatic discharge) p rotection is
designed into the module, operation in a static-fee work
area is recommended.
CAUTION
Do not plug i n or unplug a modul e with
the AC power on.
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38 Chapter 4 Laser Diode Driver Module Operation
To install the module into the 6000, follow these steps:
1.
Turn the 6000 power off.
Installing a module with the 6000 on can damage the
module and the 6000.
2. Place the module into the open bay on the back of the 6000 and slide the module into place. There are tracks at the top and bottom of the bay which guide the module into place. Screw the module locking screws into the back panel to secure the module.
To remove the module from the 6000, follow these steps:
1.
Turn the 6000 power off.
Removing a module with the 6000 on can damage the
module and the 6000.
2. Unfasten the module locking screws which secure the module to the 6000 back panel.
3. Grasp the module by the handle which extends from the bottom of the back panel. Gently, but firmly, pull the module out.
4.1.3 Laser Diode Protection Requirements
Laser diodes are extremely sensitive to electrostatic discharge and current spikes (transients). Damage can result in reduced output power, shift in threshold current, changes in beam divergence, and ultimately failure to lase (LED-like output only).
Newport precision current sources and controllers offer the most advanced laser protection features available, including power line filters, clamping current limits, and slow-start-up circuits.
However, no instrument can protect against all conditions, especially ESD at the laser. In order to optimize immunity from radiated or conducted electromagnetic energy, e.g. static discharge, the following guidelines for the laser diode must be adhered to:
ESD is the primary cause of premature laser failure. As a minimum, use anti-
static wrist straps (grounded with 1 MΩ resistor), anti-static floor coverings, grounded soldering irons, and grounded work areas. Ionized air blowers are also recommended.
Laser diode leads should be shorted whenever the laser is transported or stored. Select a driver module with the lowest possible current rating that still exceeds
the laser’s maximum operating current. For example, a laser with a maximum operating current of 150 mA should be driven by the 6505 500mA laser driver module.
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Chapter 4 Laser Diode Driver Module Operation 39
Recess the laser diode inside a metal shielded enclosure, such as a Model 700C
laser diode mount, recessed at least ¼” with the minimum aperture necessary to allow beam exit (less than 0.125”).
If industrial loads are switched in or near your laboratory, use isolation
transformers and/or surge suppresser power strip with your laser current source.
Isolate your laser current driver with a surge suppresser when using a common
line with laboratory power supplies, soldering irons, or other electronic instruments. Avoid using such devices on the same surge suppresser as your laser source.
Make sure the all cables to the laser diode are securely fastened. Avoid
“bundling” cur rent source cables with other cables in your la boratory,
Set current and voltage limits to appropr iate levels, following the laser
manufacturer’s recommendations (or to just above the expected operating current). Suggestions inc l ude setting the compliance volta ge no more than 10% above Vf, and setting the current limit at or below the maximum operating current of the laser diode.
Avoid ground loops. Don’t ground the LDD cable shield to the enclosure in
which you mount the laser diode.
Added protection from electrostatic surges or surges from the circuitry can be obtained by inserting ferrite beads and capacitors near the laser diode as shown below.
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40 Chapter 4 Laser Diode Driver Module Operation
4.2 Laser Safety Features
4.2.1 Conditions Which Can Automatically Shut Off the Laser Output.
Laser Open Circuit
1
Laser Compliance Voltage Limit
1
Laser Hard Current Limit
1
Laser Interlock State Changed
1
Laser Photodiode High Current Limit
Laser Photodiode High Power Limit
Laser Intermittent Contact (if enabled, default disabled)
A Linked Function
With the exception of the linked functions, some of these conditions can be disabled by clearing the appropriate bits in the Laser OUTOFF register. See the Computer Interfacing Manual for additional information on the OUTOFF register.
4.2.2 Key switch Interlock
The
LASER ENABLE
key switch on the front panel will shutoff, or not allow to be
turned on, any laser outputs while in the OFF position, per CDRH requirements.
1
This condition will always shutdown the laser output, and cannot be disabled.
PD Anode
(pin 7)
.1 uF
.01 uF
LD Anode (pin 8,9)
LD Cathode (pin 4,5)
(pin 6) PD Cathode
EGND (pin 3)
LDD Connector
D-Sub 9
.1 uF
LD
PD
1
2
3
3.5 uH Ferrite Beads Mouser P/N 542-FB73-287
Figure 21 - Laser Diode Protection Circuit
When applying high speed modulation to the laser diode, this circuit will reduce the maximum modulation frequency.
Note: The temperature controlled mount is earth grounded through pins 5 and 6 of the TEC connector D-sub 15.
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Chapter 4 Laser Diode Driver Module Operation 41
4.2.3 Turn On Delay
The 6000 is CDRH Compliant with a user programmable turn on delay. The default turn on delay is three seconds, but is user programmable from 0 to 30 seconds. The delay setting is in the system configure screen, which can be reached by pressing the
MENU
button, followed by the
Config
soft key, then the
System
soft key. The fi eld
is labeled
On Delay
.
4.3 The Laser Connectors
On all laser modules, except the MOPA, a 9-pin female D-connector is used for input and output connections, as shown by the pin-out diagram below. See Figure 12 for an illustration of the back panel.
Pin
Description
1,2
Interlock
3
Chassis Ground
4,5
Laser Cathode
6
Photodiode Cathode (+)
7
Photodiode Anode (-)
8,9
Laser Anode
Table 1 - Laser Connector Pinouts
For MOPA modules, a 15-pin male D-connector is used for the MOPA cable and a 9­pin male connector is used for the TEC jumper cable, as shown below.
MOPA Connector
TEC Strap Connector
Pin
Description
Pin
Description
1
TE-
1,2
TE+
2
Analog Ground
5
Ground
3
OSC-/LAS-
6,7
TE-
4
OSC+
8
Therm+
5
+12V Fan
9
Therm-
6
LAS+
7
N/C
8
TE+
9
Interlock+
10
Therm-
11
Therm+
12
MPD+
13
MDP-
14
LED+
15
LED-
Table 2 - MOPA Laser Connector Pinouts
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42 Chapter 4 Laser Diode Driver Module Operation
4.3.1 Modulation
CAUTION
Do not connect or disconnect a signal to the modulation
input with the laser on.
A BNC connector is provided for an external modulation signal. See section 4.5.3.2 for a description of modulation bandwidth.
Each 100 mV change in the modulation input is equal to 1% of the maximum drive current of the module. For example, 100 mV input on a 6560A module (6 Amp driver) would equate to 60 mA of drive current. However, regardless of the input voltage, the current cannot exceed the current limit.
4.3.2 Photodiode Bias Control
An adjustment is provided for 0V to 5V reverse bias adjust, except MOPA modules, which do not have a photodiode bias control and have fixed bias at either 0V or -5V.
4.3.3 Photodiode
CAUTION
Do not disconnect the photodiode with the laser on.
A BNC connector is provided for photodiode connections, with the center pin the anode connection and the outer shell the cathode connection. It is the same input as pins 6 and 7 in the 9-pin D connector with the anode on the shell. MOPA modules do not have this B NC connector.
4.3.4 Interlock
Except on MOPA modules, the interlock pins, 1 and 2, must be connected together to complete the circuit and allow the laser operation. Pin 1 is connected to a +5V supply through a 10 kΩ resistor, and pin 2 is connected to ground through a 1 kΩ resistor. On MOPA modules, the interlock pin 9 is connected to pin 2.
4.4 Connecting to Your Laser
When connecting laser diodes and other sensitive devices to the module, we recommend that the 6000 be powered-up and the laser output be off . In this condition, a low impedance shunt is a ctive across the output terminals. When disconnecting devices, it is only necessary to turn the laser output off.
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Chapter 4 Laser Diode Driver Module Operation 43
Except for MOPA modules, pins 4 and 5 of the 9-pin D-connector are the negative output, and pins 8 and 9 are the positive output current connections. These pins are jumpered to provide greater contact area for the output connection.
NOTE
Whenever external connections are made to the output at
pins 4 and 5, and 8 and 9, these connector leads should be
jumpered to ensure the greatest laser diode safety.
We also recommend the use of the 9-pin D-connector for your interface rather than binding posts, or loose wires. This will insure the best connection.
4.4.1 Laser Diode Connections and Shielding
CAUTION
Before connecting the laser diode to the module, be sure
that the
LASER ENABLE
is in the OFF position. Before
turning on the laser output, be sure that the current limit
and voltage compliance limit have been correctly set.
NOTE
The cable connections to the laser must be secure to avoid an open circuit, should they be jostled or bumped. Should
an open circuit occur during laser operations, the laser
output will normally be turned off automatically.
Except for MOPA modules, special circuits in the laser
module are present for detecting intermittent contacts and
connections. These circuits detect the abrupt change in
current that occurs when the output circuit is opened, and
the 6000 will generate an E-503 error.
Experience indicates that should an open circuit occur
during laser operation, the laser may be damaged.
Therefore, secure cabling is important.
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44 Chapter 4 Laser Diode Driver Module Operation
NOTE
Although the intermittent contact circuitry works well in
helping to protect the laser diode, there is still a danger in
having poor connections, as no circuit can protect
completely.
NOTE
It is possible with some modes of modulation, especially
square-wave, to trigger the intermittent contact circuit and
cause a shut-down. If this is the case for you, the
intermittent contact feature may be disabled in the laser
set up menu, with reduced laser protection in the case of
poor connections.
It is recommended that the connections to the module output be made using twisted wire pairs with an earth-grounded shield available at pin 3, except MOPA modules. For the MOPA module, use the ground post on the mainframe. The output terminals of the module are left floating relative to earth ground to suppress AC power­on/power-o ff transients that may oc cur through an e arth-ground path. If the output circuit is earth-grounded at some point (such as through the laser package and mount), the user must be careful to avoid multiple earth grounds in the circuit. Multiple earth grounds may short out the driver and may damage the laser.
See section 4.1.3 for additional information on laser diode pro tection.
4.4.2 Photodiode Feedback Connections
The photodiode signal is input at the 9-pin D-connector at pins 6 and 7, or the photodiode BNC. For MOPA modules, the photodiode signal is input at pins 12 and 13 of the 15-pin D-connector.
Many laser diode modules contain an internal photodiode that monitors the back­facet emission of the laser. Usually, one side of the photodiode is internally connected t o either the lase r anode or cathode. Figure 22 through Figure 25 show the recommended connections and shielding for the various configur ations of laser diode modules and photodiode feedback schemes. The photodiode circuit is isolated from ground and the laser circuit. Therefore, when using a 4-pin package with no common connections, place a 1 M resistor between the laser diode cathode and the photodiode anode to provide a bias return for the photodiode circuit. The output connector shown below is the 9-pin D-sub on standard laser modules.
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Chapter 4 Laser Diode Driver Module Operation 45
7 6
8,9
4,5
3
+
-
Output
6500 module
Bias
Earth Ground
L.D.
P.D.
+
-
Figure 22 - Common Laser Cathode / Photodiode Cathode
7 6
8,9 4,5
3
+
-
Output
6500 module
Bias
Earth Ground
L.D.
P.D.
+
-
Figure 23 - Common Laser Cathode / Photodiode Anode
7 6
8,9 4,5
3
+
-
Output
6500 module
Bias
Earth Ground
L.D.
P.D.
+
-
Figure 24 - Common Laser Anode / Photodiode Cathode
7 6
8,9 4,5
3
+
-
Output
6500 module
Bias
Earth Ground
L.D.
P.D.
+
-
Figure 25 - Common Laser Anode / Photodiode Anode
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46 Chapter 4 Laser Diode Driver Module Operation
4.4.3 Grounding Consideration
The laser outputs of the module are isolated from chassis ground allowing either output terminal to be grounded at the user's option.
4.5 Laser Module Operation
4.5.1 Quick Start
After the power-on sequence is complete, the 6000 goes to the Master display. To set up a laser module, press the
MENU
button, then the
Modules
soft key, then
select the laser driver, and finally, the
Setup
soft key. At this point, the display shows all laser parameters. Using the cursor keys and knob, select the desired functions and set the parameter values. When finished, return to laser display with  (previous) soft key.
Enter the desired set point value using the cursor keys or the knob. Press the
LDD
ON
key to operate the laser. The LED illuminates to indicate laser operation. To
turn the laser off, press the
LDD ON
key. For Model 6000M or 6000MF controllers,
use the
OSC ON
or
AMP ON
key to control the oscillator or amplifier outputs,
respectively.
4.5.2 Laser Main Screen
The laser main screen in shown in Figure 26 and described in detail below. Certain features are not available on some modules.
→→→→
Io= 50.01 mA <LDD> Im= 0.0 uA Vf= 0.000 V I M P O S InT SETUP
←←←←
Figure 26 - Laser Main Screen
Io=, Im=
or
Po=
- When these fields are editable, such as the
Io=
field in the figure
above, they indicate the corresponding set point. Non-editable fields, such as the
Im=
and
Vf=
fields above, indicate measured values, such as laser current or voltage,
photodiode current, or photodiode power.
SETUP
- Pushing the adjacent soft key activates the setup screen.
The bottom line on the display has 6 “LED” elements, each indicating a particular state of the laser. They are defined as:
Page 57
Chapter 4 Laser Diode Driver Module Operation 47
I
When illuminated, indicates the unit is current limiting.
M
When illuminated, indicates the unit has exceeded the monitor photodiode current limit.
P
When illuminated, indicates the unit has exceeded the monitor photodiode power limit.
O
When illuminated, indicates the system has detected an open circuit. Only detected when the unit is on.
S
When illuminated, indicates the system has detected a short circuit. Only detected when the unit is on.
InT/OutT
When illuminated, indicates the unit is out of tolerance or in tolerance as defined by the
Tol Time
and
Tol Iop
setings in the
Laser Setup Screen.
4.5.3 Laser Setup Screen
The laser setup screen for the Model 6000 is shown in Figure 27 and described in detail below. The Model 6000M and 6000MF laser setup screens are shown in Figure 28. Channel B of the MOPA module is shown here to illustrate every element. The oscillator channel does not have a power mode, so Im Lim, Po Lim, PD Resp and PD Zero elements are not displayed, and the mode is fixed at Io.
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48 Chapter 4 Laser Diode Driver Module Operation
→→→→
Mode = Io


BW = Low

Io Lim = 260 mA

Vcomp = 6.989 V
→→→→
Im Lim = 2500 uA


Po Lim = 1500 mW

Tol T = 1.000 S

Tol Iop= 10.0 mA
→→→→
IntCont= Disable


PD Resp= 0.00

PD Zero= 0.00 uA
PD ZERO
Figure 27 - Laser Setup Screens
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Chapter 4 Laser Diode Driver Module Operation 49
6540M: Chan B (AMP)

→→→→
Mode = Io

Modulate = Osc

Io Lim = 250 mA
6540M: Chan B (AMP)

→→→→
Vcomp = 5.000 V

Im Lim = 10000 uA

Po Lim = 6000 mW
6540M: Chan B (AMP)


Tol T = 0.000 S

Tol Iop= 0.0 mA
6540M: Chan B (AMP)


PD Resp= 0.00

PD Zero= 0.00 uA
PD ZERO
Figure 28 - MOPA Laser Setup Screens
4.5.3.1 Mode
The
Mode
setting controls how the laser driver current is controlled. There are three
modes: Io, Im, and Po. The oscillator channel of the MOPA module only supports
Io
, so the
Mode
setting is fixed in the Io mode.
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50 Chapter 4 Laser Diode Driver Module Operation
In the Io mode, the active set point is the actual drive current. A set point of 1000 mA will cause the module to drive 1000 mA through the laser diode, assuming the
Io
Lim
is set at or above 1000 mA.
In Im mode, the set point is the desired amount of photodiode current, in µA. Unlike the Io mode, Im mode will drive whatever current is necessary though the laser diode, up to the limit, to achieve the set point photodiode current.
Po
mode is simply an extension on the Im mode, allowing the user to operate the system in milliwatts of power. The photodiode power set point, in mW, is converted to photodiode current using the
PD Resp
value from the setup screen.
4.5.3.2 Bandwidth
This setting is used to control noise and laser current modulation rates. Allowable settings are
Low, Low CW
, and
High. Low CW
allows a maximum modulation rate
of 30 Hz, and operates with the least noise.
Low
allows up to 10 kHz modulation,
while
High
allows full bandwidth modulation. Modulation is disabled in Im and Po
modes. The MOPA module does not have the bandwidth setting.
4.5.3.3 Modulate (MOPA Modules Only)
This setting is used to select which laser driver is modulated by the external modulation input. The choices are
Osc
for the oscillator driver, or
Amp
for the
amplifier driver.
4.5.3.4 Io Lim
As one of the safety features of the Laser modules, the
Io Lim
sets a maximum allowable current drive for the laser diode. The system will also limit current set points to this value when operating in the Io mode. Two conditions can be generated when the driver reaches this limit. The lesser of the two is the soft current limit. The soft limit, indicated by I on the status line of the Laser Main Screen, indicates that the laser module is limiting the current drive to the laser diode, but otherwise operating as normal. The second condition is a hard limit, which indicates that the current drive attempted to exceed the current limit faster than the circuitry could limit it. This condition causes the laser module’s output to be shutdown. Both of these conditions are monitored in circuitry on the module itself, and in the case of the hard limit, shutdown is within microseconds of the condition being detected. See section 4.1.3 for additional information on laser diode protection.
4.5.3.5 Vcomp
The voltage compliance setting controls the shutdown of the laser module output when the forward voltage of the laser exceeds the compliance setting. Like the current limit described above, the voltage compliance is monitored in circuitry on the module itself, allowing for shutdown within microseconds of the condition. See section 4.1.3 for additional information on laser diode protection.
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Chapter 4 Laser Diode Driver Module Operation 51
4.5.3.6 Im Lim
The photodiode current limit is a software monitored limit on the current delivered from the photodiode. Because this limit is a software monitored limit, shutdown can occur up to a second after the condition is true. The oscillator channel of the MOPA module does not support this setting.
4.5.3.7 Po Lim
Like the
Im Lim
, the photodiode power limit is a software monitored limit on the
power delivered from the photodiode. For this limit to function, the user must set a
PD Resp
value other than zero. Because this limit is a software monitored limit, shutdown can occur up to a second after the condition is true. The oscillator channel of the MOPA module does not support this setting.
4.5.3.8 Tol Time and Tol Iop
The
Tol Time
and
Tol Iop
elements are used for determining when the laser is “in
tolerance.” The
Tol Time
value is expressed in seconds, and can range from 0.001
seconds to 50 seconds. The
Tol Iop
value is displayed in mA, and can range from 0.1
mA to 100 mA. When operating in Im or Po modes, The
Tol Iop
setting is ignored, and fixed values of 50 µA and 50 mW, respectively, are used. The laser is considered in tolerance after it has been within the tolerance setting for the set number of seconds. If at any time it goes outside the tolerance range, the time restarts at zero.
As an example, if the
Tol Time
is set to 5 seconds, the
Tol Iop
is set to 2 mA, and the current set point was 1000 mA, the laser module would have to stay within 998 mA and 1002 mA to be within tolerance. Out of tolerance is indicated by a
OutT
status field on the bottom of the Laser Main Screen.
4.5.3.9 Intermittent Contact (Int Contact)
The
Int Contact
setting controls the detection of intermittent contacts caused by faults cables or connectors. An intermittent contact, if enabled, will shutdown the laser with an open circuit error. The system allows the user to disable the circuit when working in an electrically noisy environment that might cause a false detection. The circuit is automatically disabled when in high bandwidth mode. The MOPA module does not have an intermittent contact circuit, so it does not support this setting.
4.5.3.10 PD Resp
The
PD Resp
element is the conversion factor between photodiode current and photodiode power, and is expressed in µA per mW. If this value is zero, the system will not operate in Po mode. The oscillator channel of the MOPA module does not support this setting.
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52 Chapter 4 Laser Diode Driver Module Operation
4.5.3.11 PD Zero
The
PD Zero
element is the photodiode offset that is removed from the photodiode read back before any values are displayed, and conversely, is added to any photodiode set point. The photodiode offset is a combination of any dark current or stray light picked up while the laser is off. Pressing the
PD Zero
soft key sets this element to the photodiode current that is present on the photodiode input. To clear it, simply press the
PD Zero
soft key a second time. The oscillator channel of the
MOPA module does not support this setting.
4.5.3.12 The
and Soft Keys
Pushing the

(previous) soft key returns to the previous screen, while pressing the
(next) soft key advances to the next screen.
4.5.4 Link Conditions
The laser module supports the following link conditions:
Condition
Description
On
Laser output is on
Off
Laser output is off
Out Tol
Laser is out of tolerance
In Tol
Laser is in tolerance
Io Lim
Laser is current limiting
Vf Lim
Laser has reached its voltage limit
Im Lim
Laser has exceeded photodiode current limit
Po Lim
Laser has exceeded photodiode power limit
Interlock
Laser interlock is not closed
Open
Laser module is open circuit
Short
Laser module is shorted
Table 3 - Laser Link Conditions
See the section 2.4.10 for a complete description of the linking process.
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53
CHAPTER 5
5. Temperature Controller Operation
5.1 Temperature Controller (TEC) Module
The Temperature Controller is a precision thermoelectric cooler control module that is an integral part of the Model 6000 Controller. Features of module include:
Close-case calibration
Operational with most thermistors, IC and RTD temperature sensors
Flexible setup with 6000 Save/Recall front panel functions
High temperature stability
Current Limit
5.2 TEC Safety Features
5.2.1 Conditions Which Will Automatically Shut Off the TEC Output
High Temperature Limit
Low Temperature Limit
R Limit
Sensor Open
TEC Module Open
Sensor Select changed
Sensor Shorted
Mode Change
Any Linked Functi ons
With the exception of the linked functions, each of these conditions can be disabled by clearing the appropriate bits in the TEC OUTOFF register. See the Computer Interfacing Manual for additional information on the OUTOFF register.
5.3 The TEC Connectors
On the TEC Module, a 15-pin D-connector is used for input and output connections to the series 700 mounts, as shown by the pin-out diagram below.
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54 Chapter 5 Temperature Controller Operation
Pin
Description
1,2
TE+
3,4
TE-
5,6
Ground
7
Sensor+
8
Sensor-
Table 4 - TEC Connector Pintout s
5.3.1 TEC Grounding Consideration
The TEC output of the module is isolated from chassis ground, allowing either output terminal to be grounded at the user's option.
5.4 TEC Module Operation
5.4.1 Quick Start
After the power-on sequence is complete, the 6000 goes to the Master display. To set up a TEC module, press the
MENU
button, then the
Modules
soft key, then
select the TEC module, and finally, the
Setup
soft key. At this point, the display shows all TEC parameters. Using the cursor keys and knob, select the desired functions and set the parameter values. When finished, return to TEC display with

(previous) soft key.
Enter the desired set point value using the cursor keys or the knob. Press the
TEC
ON
soft key to operate the TEC. The LED illuminates to indicate TEC operation. To
turn the TEC off, press the
TEC ON
key again.
5.4.2 TEC Main Screen
The TEC main screen is shown Figure 29 and described below.
→→→→
Ts= 25.00 °C T= 25.00 °C Ite= 0.000 A I V T R C InT SETUP
←←←←
Figure 29 - TEC Main Screen
Is=, Ts=, Rs=, is=, vs=
- Indicates the set point value of current, temperature, resistance, AD590 sensor current, or LM335 sensor voltage. In the screen shown above, the Ts is shown.
Is, Rs, is,
and vs would be seen when operating in those
modes.
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Chapter 5 Temperature Controller Operation 55
I=, T=, R=, i=, v=
- Indicates the measured value of current, temperature, resistance,
AD590 sensor current, or LM335 sensor voltage. An
err
indicates a sensor error, usually caused by the senso r not hooked up or the wrong sensor selected. In the screen shown above, the T is shown. I,
R, i
, and
v
would be seen when operating in
those modes.
SETUP
- Pushing the adjacent soft key activates the setup screen.
CAL
- Pushing the adjacent soft key switches to the calibration menu, where I
TE
,
Sensor, and RTD cable null can be selected.
LINK
- Pushing the adjacent soft key activates the linking screen. This establishes any interaction that may be desired between different modules. See the Model 6000 main manual for a description of the linking process.
The bottom line on the display has 6 “LED” elements, each indicating a particular state of the TEC. They are defined as:
I
When illuminated, indicates the TEC module is in current limit.
V
When illuminated, indicates the TEC module has reached it’s voltage limit.
T
When illuminated, indicates the TEC module is outside the temperature limits defined by T
HI
and TLO in the setup screen.
R
When illuminated, indicates the TEC module is outside the reference limits defined by R
HI/vHI/iHI
and RLO/vLO/iLO in the
setup screen.
C/H
When illuminated, indicates that the TEC is cooling or heating.
OutT/InT
When illuminated, indicates that the TEC is out of tolerance or in tolerance as defined by
Tol Time
and
Tol Temp
in the setup
screen.
5.4.3 TEC Setup Screen
The TEC Setup screen is shown in Figure 30. Each section is described below in detail.
→→→→
Sens = RTD


Mode = Const T

Gain = 30 Fast

Lim Ite= 2.00 A
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56 Chapter 5 Temperature Controller Operation
→→→→
Lim Th= 50.00 °C


Lim Tl= 10.00 °C

Tol Time= 5.000 S

Tol Temp= 0.20 °C
→→→→
C1= 3.9080 x 10-3


C2=-0.5802 x 10-6

C3=-4.272 x 10-12

R0= 100.00
ΩΩΩΩ
Figure 30 - TEC Setup Screens
5.4.3.1 Sensor
Selects the temperature sensor type used in your TEC mount. If the
None
is selected,
only the I
TE
mode is allo wed . This type is i ntended for applica t ions running without a temperature sensor. After selecting desired sensor, press ENTER. See the following sections for discussions of the various sensor types. TEC modules support the thermistor sensors (1 0µA and 100µA range), AD590, LM335, and RTD sensors.
5.4.3.2 Mode
5.4.3.2.1 Constant Temperature Mode (Const T)
This mode holds the TEC at a constant temperature based on feedback from the sensor in the TEC mount, using “
Ts=
” and “T=” variables. In this mode, the 6000 uses a control loop comparing the sensor input to the temperature set point, driving the I
TE
current positive or negative to reach and maintain that set point. The sensor’s
input is converted to temperature for display of actual TEC temperature. The I
TE
current is also displayed in this mode.
5.4.3.2.2 Constant Resistance/Reference Mode (Const R/Const v/Const i)
This mode operates identically to the Const T mode, but the sensor input is not converted to temperature, and is displayed in unconverted form. Likewise, the set point is used directly, not converted from temperature. Thermistor and RTD sensors use resistance (Const R mode, “
Rs=
” and “R=” variables), LM335 sensors use
millivolts (Const v mode, “
vs=
” and “v=” variables), and AD590 sensors use
microamps (Const i mode, “
is=
” and “i=” variables). Const R, Const v, and Const i
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Chapter 5 Temperature Controller Operation 57
are primarily intended for users who know a sensor set point in “sensor” units, not in
º
C. I
TE
current is also displayed in these modes.
5.4.3.2.3 Constant Current Mode (Const I
TE
)
Unlike the modes above, the Const I
TE
mode allows the operator to explicitly set the
amount and dir ection of current flow through the TEC, using “
Is=
” and “
Ite=
” variables. If a sensor has been selected, the TEC temperature will be displayed. Although temperature is not a factor in the amount or dir ection or current flow, the high and low temperature limits are observed, and will shutdown the output if exceeded, in Const I
TE
mode if a sensor is selected. For no temperature limits, set the sensor type to “None.” Use caution when limits are not active, as the temperature may exceed your TEC or Laser’s thermal limits.
5.4.3.2.4 Effects of Calibration on TEC modes
On startup, the TEC performs an auto-calibration to eliminate most of the error in ADC and DAC values. After this auto-calibration, each sensor type supported by the module has an offset calibration, while the I
TE
set point and read back has a two point calibration. These calibration constants are then used to calibration a set point or read back value. This includes “cross-mode” values, such as displaying actual current while in constant temperature mode. While the current set point calibration has no effect in Const T mode, the read back calibration is used to more accurately display the actual current.
5.4.3.3 Gain
The Gain function controls two parameters of the hybrid PI control loop; proportional gain and integration time.
When the actual temperature and the set point are different, an error voltage is generated. This error voltage is directly related to the difference in the actual and set point temperatures. The error voltage is then amplified by the proportional gain. This amplified error voltage controls the amount o f current dri ven through the T EC. The higher the gain, the more current will be driven for any given temperature difference, with the maximum current being determined by the current limit.
The error voltage also drives an integrator. The integrator’s output also controls the amount of curre nt being driven t hrough the TE C. The integr ator is an ampli fi er whose gain is proportional to time. T he longer a given error voltage is present, the more current will be driven thro ugh the TEC, with the maximum current being determined by the current limit. The speed at which the integrator’s output increases is the integration time, which can be “Slow” or “Fast”. Some TEC modules do not support the Slow setting, and therefore omit the Fast designator in the range of settings.
The allowed Gain values are: 0.2 Slow, 0.6 Slow, 1 Slow, 1 Fast, 2 Slow, 3 Fast, 5 Fast, 6 Slow, 10 Slow, 10 Fast, 20 Slow, 30 Fast, 50 Fast, 60 Slow, 100 Fast or 300
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58 Chapter 5 Temperature Controller Operation
Fast. The number actually defines the proportional loop gain. The slow/fast suffix indicates the speed at which the integrator’s output increases. The slow setting allows for larger masses or greater distance between the sensor and the thermo-electric cooler by slowing the speed of the integrator.
Both the proportional gain and the integration time must be matched to the thermal characteristics of the TE cooler and sensor. If the settings are incorrect, the temperature set point will take an excessive amount of time to settle, or it will oscillate around the set point and never settle.
The Gain setting depends on the type of T E cooler that you are using, but we can suggest guidelines for selecting the proper ga in. Set the gain to 1 fast and increase it until the actual temperature oscillates around the set temperature. Then reduce the gain to the next lower value.
To read the Gain setting, go to the setup. The display will show the value of the Gain setting. In Consta nt I
TE
mode the Gain setting has no effect.
5.4.3.4 Limits
5.4.3.4.1 TE Current Limit (Limit I
TE
)
This sets the maximum drive current the module will allow. This maximum applies to all modes (constant I
TE
/R/T).
5.4.3.4.2 Temperature Limits (Limit T
HI
and Limit TLO)
The TEC supports both a low and high temperature limit, and can be programmed to turn the TEC output off in the event those limits are exceeded (default state). The temperature limits are monitored regardless of the mode of the module. This has the added safety feature of shutting down the module in Const I
TE
or Const R mode when the temperature limit is exceeded (if the output off bits are enabled for this condition).
Caution: these limits do not apply if the sensor type is set to “None.”
5.4.3.4.3 Resistance/Reference Limits (Limit R
HI/vHI/iHI
and Limit RLO/vLO/iLO)
Like the temp erature limits, the TEC also supports both a low and high resistance/reference limit, and can be programmed to turn the TEC output off in the event those limits are exceeded, although by default this is disabled. These limits are monitored only while in Const R/v/i mode.
5.4.3.5 Tolerances (Tol Time and Tol Temp)
The
Tol Time
and
Tol Temp
elements are used for determining when the TEC is “in
tolerance,” where the actual temperature has stayed within
Tol Temp
of the set point
for at least
Tol Time
seconds. The
Tol Time
value is expressed in seconds, and can
Page 69
Chapter 5 Temperature Controller Operation 59
range from 0.001 seconds to 50 seconds. The
Tol Temp
value is displayed in ºC (the most common usage), and can range from 0.01 to 10.00. If at any time it goes outside the tolerance range, the time restarts at zero.
As an example, if the
Tol Time
is set to 5 seconds, the
Tol Temp
is set to 0.2ºC, and
the temperature set point was 25.0ºC, the TEC module would have to stay within
24.8ºC and 25.2ºC to be within tolerance. Out of tolerance is indicated by a
OutT
status field on the bottom of the TEC Main Screen.
The out of tolerance condition is most often used to shutdown laser outputs when a TEC is not operating within tolerance. This can be done in one of two ways. The first, and simplest, would be to define a link condition with the T E C module as the source,
Out
as the condition,
Turn Off
as the action, and the laser module as the
target.
Alternately, if the system was being operated over IEEE-488 or RS-232, once the TEC was within tolerance, its OUTOFF register could be set to turn the TEC off when out of tolerance. Then enable the TEC OFF bit in the laser’s OUTOFF register. This will cause the TEC to shutdown when it goes out of tolerance, and the laser to shutdown because the TEC is OFF. The disadvantage of this second method would be that the laser would shutdown if any TEC were off, which might no t be the desir ed operation. Also, you would have to disable the Out of Tolerance bit in the TEC’s OUTOFF register before you could turn the TEC back on.
5.4.3.6 C1, C2, C3, and Ro
See the section of each of the sensors for a description of how C1, C2, C3, and Ro are used.
5.4.3.7 The
and Soft Keys
Pushing the

(previous) soft key returns to the previous screen, while pressing the
(next) soft key advances to the next screen.
5.4.4 Link Conditions
The Laser module supports the following link conditions:
Condition
Description
On
TEC output is on
Off
TEC output is off
Out Tol
TEC is out of tolerance
In Tol
TEC is in tolerance
I Lim
TEC is current limiting
V Lim
TEC has reached its voltage limit
T Lim
TEC has exceeded temperature limit (low or high)
Th Lim
TEC has exceeded high temperature limit
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60 Chapter 5 Temperature Controller Operation
Tl Lim
TEC has exceeded low temperature limit
R Lim
TEC has exceeded R limits (high or low)
Open
TEC module is open
Table 5 - TEC Link Conditions
See the section in the main Model 6000 manual of linking for a complete description of the linking process.
5.4.4.1 Thermistor and Thermistor Current Selection
5.4.4.1.1 Introduction
Choosing the ri ght sensing current depends on the range of tempera ture you want to measure and the resolution you require at the highest measured temperature. To correctly set the thermistor current you must understand how the thermistor and the 6000 interact and how temperature range and resolution values are inherent in the nature of thermistors.
5.4.4.1.2 Thermistor Range
Thermistors can span a wide temperature range, but their practical range is limited by their non-linear resistance properties. As the sensed temperature increases, the resistance of the thermistor decreases significantly and the thermistor resistance changes less for an equivalent temperature change. Consider the temperature and sensitivity figures below.
Temperature
Sensitivity
-20°C 5600 ohms/°C 25°C 439 ohms/°C 50°C 137 ohms/°C
In the 6000 the practical upper temperature limit is the temperature at which the thermistor becomes insensitive to temperature changes. The lower end of the temperature range is limited by the maximum A/D input voltage of the 6000. Thermistor resistance and voltage are r elated thro ugh Ohm's Law (V = I x R). The 6000 supplies current to the thermistor, either 10 µA or 100 µA , and as the resistance changes a changing voltage signal is available to the thermistor inputs of the 6000. The 6000 will over-range when the input voltage exceeds about 5 Volts. Figure 31 graphically shows the lower temperature and upper voltage limits for a typical 10 k Ohm thermistor. The practical temperature ranges for a typical 10 K thermistor (a 10 K thermistor has a resistance of 10 k Ohms at 25°C) are given in the table below.
Sensing Current
Temperature Range 10 µA -51 to 40°C 100 µA -10 to 100°C
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Chapter 5 Temperature Controller Operation 61
Figure 31 - Thermistor Temperature Range
5.4.4.1.3 Temperature Resolution
You must also consider measurement resolution since the resolution decreases as the thermistor temperature increases. The 6000 uses an A/D converter that has a maximum resolution of about 76 µV. The microprocessor converts this digital number to resistance, stores this resistance, then converts it to a temperature using the Steinhart-Hart equation, and stores this temperature. A temperature change of one degree centigrade will be represented by a greater resistance increase (and therefore more A/D counts) at a lower temperature than at a higher temperature because of the non-linear resistance of the thermistor. Resolution figures for a typical 10 k Ohm thermistor are given below.
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62 Chapter 5 Temperature Controller Operation
Temperature
Voltage at 10 µA Resolution
-20 °C 56.0 mV/°C 0.018 °C/mV 25 °C 4.4 mV/°C 0.230 °C/mV 50 °C 1.4 mV/°C 0.700 °C/mV
For this thermistor, a temperature change from -20°C to -19°C will be represented by 737 A/D counts (if supplied with 10µA). The same thermistor will only change about 18 A/D counts from 49°C to 50°C.
5.4.4.1.4 Selecting Thermistor Current
To select the current setting for a typical 10 K thermistor, determine the lowest temperature you will need to sample and select the current according to the range limits given above. If the temperature you want to sample is below -10°C you should use the 10µA setting.
With the current set to 10µA the best resolution you will see will be a 1.0°C temperature change. If, for example, the lower limit is 0°C you can choose either setting, but there is a tradeoff in terms of resolution. If you need better than 0.1°C measurement resolution you will have to change to 100µA.
If you need high resolution over a narrow range, for a very accurate measurement, you can set the current setting for the maximum resolution. For example, at a high temperature of 15°C, you require a measurement resolution of at least 0.05°C. This resolution is within the range of either setting, but at the 10µA setting the resolution is only 0.2°C while at the 100 µA setting the resolution is better than .05 °C.
Generally, it is best to use the 100µA setting for all measurements of -10°C or greater with a 10 K thermistor.
5.4.4.1.5 Selecting Thermistors
The type of thermistor you choose will depend primarily on the operating temperature range. These guidelines for selecting the range and resolution will apply to any thermistor. 10 K thermistors are generally a good choice for most laser diode applications where high stability is required near room temperatures. Similarly, 10 K thermistors are often a good choice for cooling applications where you want to operate at temperatures from -40°C to room temperature.
If you require a different temperature range or the accuracy you need can't be achieved with either current setting, select another thermistor. Thermistor temperature curves, supplied by the manufacturer, show the resistance verses temperature range for many other thermistors. Newport, Inc. will also offer help for your specific application.
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Chapter 5 Temperature Controller Operation 63
5.4.4.1.6 The Steinhart-Hart Equation
The Steinhart-Hart equation is used to derive temperature from the non-linear resistance of an NTC (Negative Temperature Coefficient) thermistor.
The following section contains an explanation of the Steinhart-Hart equation and the values of these constants for some common thermistors.
Two terminal thermistors have a non-linear relationship between temperature and resistance. The resistance verses temperature characteristics for a family of similar thermistors is shown in Figure 32. It has been found empirically that the resistance verses temperature relationship for most common negative temperature coefficient (NTC) thermistors can be accurately modeled by a polynomial expansion relating the logarithm of resistance to inverse temperature. The Steinhart-Hart equation is one such expression and is given as follows:
1/T = A + B (Ln R) + C (Ln R)
3
Where T is in KELVIN. To convert T to °C, subtract 273.15.
Once the three constants A, B, and C are accurately determined, only small errors in the calculation of temperature over wide temperature ranges exist. Table 6 shows the results of using the equation to fit the resistance verses temperature characteristic of a common 10 k Ohm (at room temperature) thermistor. The equation will produce temperature calculation errors of less than 0.01°C over the range -20 °C to 50 °C.
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64 Chapter 5 Temperature Controller Operation
Figure 32 - Thermistor Resistance versus Temperature
----------Error T (°C)---------- R
2
T Actual
First Order
Fit. Eq. 2
3
Third Order
Fit. Eq. 1
4
97072
-20.00
-0.00
-0.32
55326
-10.00
0.00
-0.06
32650
0.00
-0.00
0.09
19899
10.00
-0.00
0.15
12492
20.00
-0.00
0.13
10000
25.00
0.00
0.08
8057
30.00
0.00
0.01
5326
40.00
0.00
-0.20
3602
50.00
-0.00
-0.50
Table 6 - Comparison of Curve Fitting Equations
2
Resistance of a 10K, Fenwal UUA41J1 thermistor.
3
Constants A' = 0.963 * 10-3, B' = 2.598 * 10-4
4
Constants A = 1.125 * 10-3 (C1 = 1.125)
B = 2.347 * 10
-4
(C2 = 2.347)
C = 0.855 * 10
-7
(C3 = 0.855)
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Chapter 5 Temperature Controller Operation 65
In practi ce we have found that t he constants A, B and C for virtually all common thermistors lie within a narrow range. Consequently, we have define d the constants C1, C2, C3 as fo llows:
C1 = A * 10
+3
C2 = B * 10
+4
C3 = C * 10
+7
The consta nt s C1, C2, and C3 may all be expressed in the form n.nnn simplifying entry into the 6000.
If high accuracy is not required, the Steinhart-Hart equation may be simplified to a first order polynomial:
1/T = A' + B' * Ln R
This equation is easier to solve and often provides adequate results. The table also shows that the use of the simp lified equation introduces temperature errors of less than 0.5°C over the range -20 °C to 50 °C. Once the constants A' and B' are determined, the 6000 is programmed with the following values of C1, C2 and C3:
C1 = A' * 10
+3
C2 = B' * 10
+4
C3 = 0.000
5.4.4.1.7 Table of Constants
We have listed some common thermistors and included the appropriate calibration constants for the temperature range -20 °C to 50 °C in Table 7. The Model 6000, by default, uses the BetaTHERM 10K3A2 thermistor values.
Manufacturer C1 C2 C3
BetaTHERM 10K3 1.129241 2.341077 0.877547
BetaTHERM 0.1K1 1.942952 2.989769 3.504383 BetaTHERM 0.3K1 1.627660 2.933316 2.870016 BetaTHERM 1K2 1.373419 2.771785 1.999768 BetaTHERM 1K7 1.446659 2.682454 1.649916 BetaTHERM 2K3 1.498872 2.379047 1.066953 BetaTHERM 2.2K3 1.471388 2.376138 1.051058 BetaTHERM 3K3 1.405027 2.369386 1.012660 BetaTHERM 5K3 1.287450 2.357394 0.950520 BetaTHERM 10K3 1.129241 2.341077 0.877547 BetaTHERM 10K4 1.028444 2.392435 1.562216 BetaTHERM 30K5 0.933175 2.213978 1.263817 BetaTHERM 30K6 1.068981 2.120700 0.901954 BetaTHERM 50K6 0.965715 2.106840 0.858548 BetaTHERM 100K6 0.827111 2.088020 0.805620 BetaTHERM 1M9 0.740239 1.760865 0.686600
Table 7 - Thermistor Constants
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66 Chapter 5 Temperature Controller Operation
5.4.4.2 AD590 and LM335
5.4.4.2.1 General
The 6000 uses two constants (C1 and C2) for calibrating the two linear thermal sensing devices, the AD590 and the LM335. C1 is used as the zero offset value, and C2 is used as the slope or gain adjustment. Therefore, C1 has a nominal value of 0, and C2 has a nominal value of 1 when using the AD590 or LM335. In order to calibrate a linear sensor device, the sensor must be operated at an accurately known, stable temperature. For example, the sensor may be calibrated at 0 °C if the sensor is placed in ice water until its temperature is stable. A highly accurate temperature probe, thermometer, environmental chamber, etc., may also be to determine the known temperature for calibration.
5.4.4.2.2 AD590 Sensor
The AD590 is a linear thermal sensor which acts as a current source. It produces a current, i, which is directly proportional to absolute temperature, over its useful range (-50 °C to + 150 °C). This nominal value can be expressed as:
i = 1 µA / K
where i is the nominal current produced by the AD590, and K is in Kelvin.
The 6000 uses i to determine the nominal temperature, T
n
, by the formula:
T
n
= (i/(1 µA / K) ) - 273.15
where T
n
is in °C.
The displayed temperature, T
d
= C1 + (C2 * Tn), is then computed, where C1 and C2 are the constants stored in the 6000 for the AD590. The AD590 grades of tolerance vary, but typically without adjusting C1 and C2, the temperature accuracy is ±1°C over its rated operating range. However, the AD590 is not perfectly linear, and even with C1 accurately known there is a non-linear absolute temperature error associated with the device. This non-linearity is shown in Figure 33, reprinted from Analog Devices specifications, where the error associated with C1 is assumed to be zero.
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Chapter 5 Temperature Controller Operation 67
Figure 33 - AD590 Nonlinearity
If a maximu m absolute error of 0.8°C is tolerable, the one point calibration of C1 should be used. If a greater accuracy is desired, the two point method of determining C1 and C2 should be used. Note however, the absolute error curve is non-linear, therefore the constant C2 will vary for different measurement points.
5.4.4.2.3 LM335 Sensor
The LM335 is a linear thermal sensor which acts as a voltage source. It produces a voltage, v, which is directly proportional to absolute temperature, over its useful range (-40°C to + 100°C). This nominal value can be expressed as:
v = 10mV / K
where v is the voltage produced by the LM335 and K is Kelvin.
The 6000 uses v to determine the nominal temperature, T
n
, by the formula:
T
n
= ( v / ( 10mV / K) ) - 273.15
where T
n
is in °C.
The temperature, T
d
, which is displayed by the 6000 is calculated as follows:
T
d
= C1 + (C2 * Tn)
where C1 and C2 are the constants stored in the 6000 for the LM335.
When the LM335 is calibrated to 25°C, C1 = 0 and C2 = 1, and the temperature accuracy is typically ±0.5°C over the rated operating range. However, the LM335 is
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68 Chapter 5 Temperature Controller Operation
not perfectly linear, and even with C1 accurately known there is a non-linear absolute temperature error associated with the device. This non-linearity caused error is typically ±0.3°C, with the error associated with C1 assumed to be zero.
If a maximum absolute erro r of ±0.3°C can be tolerated, the one point calibration of C1 should be used. If a greater accuracy is desired, the two point method of determining C1 and C2 should be used. Note however, the absolute error associated with the constant C2 may vary ove r different temperature ranges.
5.4.4.2.4 Determining C1 and C2 for the AD590 and LM335
The nominal values of C1 and C2 are 0 and 1, respectively, for both types of devices. These values should be used initially for determining C1 and C2 in the methods described below.
The One Point method is easiest, but it ignores the non-linearity of the device. It is most useful when a high degree of temperature accuracy is not required.
The Two Point method can achieve a high degree of accuracy over a narrower operating temperature range, but requires two accurate temperature measurements.
5.4.4.2.4.1 One Point Calibration Method
The calibration described in this section is independent of the calibration procedure described in sections 7.3.4 and 7.3.6. Those sections deal with the internal calibration of the TEC module, while the following calibration procedure is for calibrating the external AD590 or LM335 sensor. For the most accurate possible results, both calibration procedures should be performed.
The accuracy of this procedure depends on the accuracy of the externally measured temperature. It is used to determine the zero offset of the device, and it assumes that the gain (slope) is known.
1. Allow the 6000 to warm up for at least one hour. Select the desired sensor type in the setup menu.
2. Set the C1 parameter to zero. Set the C2 parameter to 1.
3. Place the sensor at an accurately known and stable temperature, T
a
. Connect the sensor to the 6000 for normal Constant temperature operation. Allow the 6000 to stabilize at the known temperature, T
a
and read the displayed temperature, T
d
.
4. Determine the new value of C1 from the formula:
C1 = T
a
- Td
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Chapter 5 Temperature Controller Operation 69
and enter the new C1 value.
5.4.4.2.4.2 Two Point Calibration Method
The calibration described in this section is independent of the calibration pro ced ure described in sections 7.3.4 and 7.3.6. Those sections deal with the internal calibration of the TEC module, while the following calibration procedure is for calibrating the external AD590 or LM335 sensor. For the most accurate possible results, both calibration procedures should be performed.
The accuracy of this procedure depends on the accuracy of the externally measured temperature. It is used to determine the zero offset of the device and the gain (slope).
1. Allow the 6000 to warm up for at least one hour. Select the desired
sensor type in the setup menu.
2. Set the C1 parameter to zero. Set the C2 parameter to 1.
3. Place the sensor at an accurately known and stable temperature, T
a1
. Connect the sensor to the 6000 for normal Constant temperature operation. Allow the 6000 to stabilize at the known temperature, T
a1
and read the displayed temperature, T
d1
. Record these values.
4. Repeat Step 3 for another known temperature, T
a2
, and the
corresponding displayed temperature, T
d2
. The two known temperatures should at the bounds of the intended operating range. For best results, make the range between T
a1
and Ta2 as narrow as possible.
5. Determine the new value of C1 and C2 from the following calculations.
C2 = (T
a1
- Ta2) / (Td1 - Td2), and
C1 = T
a1
- (Td1* C2)
6. Enter the new C1 and C2 values.
5.4.4.3 RTD Sensors
The following equation is used in temperature to resistance conversions:
R
T
= R0 [1 + C1 x T - C2 x T2 - C3 x (T-100) x T3) for T < 0°C
R
T
= R0 [1 + C1 x T - C2 x T2) for T >= 0°C
where: R
T
is the resistance in at temperature T.
T is the temperature in °C.
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70 Chapter 5 Temperature Controller Operation
5.4.4.3.1 RTD Constants
The constants entered for an RTD depend on the type of curve it has. Table 8 shows three standard types.
Curve
TCR
(
ΩΩΩΩ/ΩΩΩΩ/°°°°
C)
C1
C2
C3
R0
Laboratory .003926 3.9848x10-3 -0.58700x10-6 4.0000x10
-12
100.00
US .003910 3.9692x10
-3
-0.58495x10-6 -4.2325x10
-12
100.00
European .003850 3.9080x10
-3
-0.58019x10-6 -4.2735x10
-12
100.00
Table 8 - RTD Constants
The Ro constant also applies for RTD sensors. It is nominally 100.00 , but can be varied from 95.00 to 105.00 Ω.
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71
CHAPTER 6
6.
Maintenance
6.1 Introduction
Module specific calibration can be found in the module's manual. There is no calibration on the main frame. Do not attempt to remove the cover.
6.2 Fuse Replacement
The fuses are accessible on the back panel of the 6000. Before replacing a fuse, turn power off and disconnect the line cord. Use only the fuses indicated below.
Line Volta ge
Fuse Replacement 90-110 VAC 2.5 Amp, 3 AG, Slo-Blo, 250V 108-132 VAC 2.5 Amp, 3 AG, Slo-Blo, 250V 198-242 VAC 1.25 Amp, 3 AG, Slo-Blo, 250V 216-250 VAC 1.25 Amp, 3 AG, Slo-Blo, 250V
6.3 Cleaning
Use mild soap solution on a damp but not wet cloth. Disconnect AC power before cleaning.
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73
CHAPTER 7
7. Calibration
7.1 Calibration Overview
The 6000 performs an automatic DAC calibration on power-up. This removes the majority of calibration error. However, if it is desired to completely calibrate the system, the following procedures will do so.
All calibrations are done with the case closed. The instrument is calibrated by changing the internally stored digital calibration constants.
All calibrations may be performed locally or remotely.
7.1.1 Environmental Conditions
Calibrate this instrument under laboratory conditions. We recommend calibration at 25°C ± 1.0°C. When necessary, however, the 6000 may be calibrated at its intended use temperature if this is within the specified operating temperature range of 0°C to 40°C.
7.1.2 Warm-Up
The 6000 should be allowed to warm up for at least 1 hour before calibration.
7.2 Laser Calibration
This chapter describes how to calibrate the 6500 Series laser modules.
7.2.1 Recommended Equipment
Recommended test equipment for calibrating the module is listed in Table 1. Equipment other than that shown in the table may be used if the specifications meet or exceed those listed.
Description
Mfg./Model
Specification
DMM
HP 34401A
DC Amps @ 1.0 A): ±1% Resistance (@ 10 ohms): 0.02%
Resistor
High Power, Low Temperature Coefficient
1 , 50 W; 2 , 25 W; 5 , 10 W; 10 , 5 W; 30 , 2 W
Optical Isolator
NEC PS2501-1
or equivalent, 6-pin
Connector
D-sub
9-pin male
Table 9 - Recommended Test Equipment
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74 Chapter 7 Calibration
7.2.2 Drive Current Load Resistor Selection
Laser Drive Current
Resistor
200 mA
30 , 2 W
500 mA
10 , 5 W
1,000 mA
5 , 10 W
3,000 mA
2 , 25 W
6,000 mA
1 , 50 W
Table 10 - Drive Current Load Resistor Selection
7.2.3 Local Operation Current Source Calibration
a. With the output off, connect a load resistor, as selected Table 10, and a
calibrated ammeter in series across the laser output terminals. If an ammeter with the appropriate current ratings is unavailable, connect a calibrated DMM across the laser output terminals to measure the voltage across the resistor. Calculate the current in the following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the slot soft key that corresponds to the
module to be calibrated.
c. Press the
Setup
soft key and set the laser current limit (
Io Lim
) to one-
half scale plus 100 mA and output bandwidth as desired. Press the
soft key to return to the single display.
d. Press the
LDD ON
key to turn the laser output on, if it is not on already. If a laser on delay has been set, wait that amount of time to allow the laser output to engage.
b. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Io
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft
key is pressed at any point prior to completing the calibration.
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Chapter 7 Calibration 75
7.2.4 Remote Operation Current Source Calibration
a. With the output off, connect a load resistor, as selected Table 10, and a
calibrated ammeter in series across the laser output terminals. If an ammeter with the appropriate current ratings is unavailable, connect a calibrated DMM across the laser output terminals to measure the voltage across the resistor. Calculate the current in the following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Select the channel via the
LAS:CHAN
command. Set the current limit
to one-half scale plus 100 mA via the
LAS:LIM:LDI
command, output
bandwidth as desired via the
LAS:MODE:I, LAS:MODE:ICW
, or
LAS:MODE:ILBW
command, and current set point to one-half scale
via the
LAS:LDI
command.
c. Enter the
LAS:OUTPUT ON
command to turn the laser output on.
d. Enter the laser LDI calibration mode by issuing the
LAS:CAL:LDI
command.
e. Input the actual (measured) laser output current (as an <nrf value>) via
the
LAS:LDI <nrf value>
command.
The 6000 will be ready to receive the current value when, after a
LAS:CAL:LDI?
query is sent, the response from the 6000 is "1".
f. Once the actual current value is entered via the
LAS:LDI
command, the 6000 will apply a new current equal to approximately one-fourth (¼) the previous set point.
The 6000 will be ready to receive the second current value when, after a
LAS:CAL:LDI?
query is sent, the response from the 6000 is "1".
g. Input the second actual (measured) laser output current as in Step e.
h. Once the actual current value is entered via the second
LAS:LDI
command, the 6000 leaves the current calibration mode.
If, at any time prior to the second
LAS:LDI,
a command other than
LAS:LDI
or
LAS:CAL:LDI?
is sent to the 6000, the 6000 will cancel
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76 Chapter 7 Calibration
the calibration mode and then process the command(s).
The *
OPC?
query may be used to determine when the calibration is
completed.
The operation complete flag (bit 0 of the Standard Event Status
Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
7.2.5 Local Operation IPD Current Calibration
This procedure calibrates the feedback circuits for constant IPD and constant PPD modes. The user enters the actual value of the current, as measured by an external DMM. The 6000 then automatically calibrates the laser feedback circuits. MOPA modules have photodiode feedback circuits on channel B only.
The I
PD
calibration circuit is diagrammed below. Use Table 10 above to select a value for the R2 resister that matches the maximum drive current of the laser diode module.
R1
100
R2
NEC PS2501-1
R3
100
V
A
Ipd Current
Ammeter
Voltmeter
4,5 8,9
6 7
D Cathode
D Anode
D Anode D Cathode
9 Pin D-Sub
4 3
1 2
Figure 34 - I
PD
Calibration Circuit
a. With the laser output off, connect a calibrated ammeter to the PD
Anode output of the module and connect the circuit of Figure 34 to the laser and PD outputs.
If a calibrated ammeter (with 0.1 µA resolution) is not available, place a
calibrated DMM (with 0.1 mV resolution) to measure the voltage across the resistor, R3, as shown in Figure 34. Calculate the current in the following steps by using Ohm's Law:
I = V / R
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Chapter 7 Calibration 77
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the slot soft key that corresponds to the
module to be calibrated.
c. Press the
Setup
soft key, change the
Mode
to Im (Photodiode constant
current mode), and set the laser current limit (
Io Lim
) to maxi mum.
Press the
soft key to return to the single display.
d. Press the
LDD ON
key to turn the laser output on. If a laser on delay has been set, wait that amount of time to allow the laser output to engage.
e. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Im
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft
key is pressed at any point prior to completing the calibration..
7.2.6 Remote Operation IPD Current Calibration
a. With the laser output off, connect a calibrated ammeter to the
photodiode anode output of the module and connect the circuit of Figure 34 to the laser and photodiode outputs.
If a calibrated ammeter (with 0.1 µA resolution) is not available, place a
calibrated DMM (with 0.1 mV resolution) to measure the voltage across the resistor, R3, as shown in Figure 34. Calculate the current in the following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Select the channel via the
LAS:CHAN
command. Set the laser current
limit to full scale via the
LAS:LIM:LDI
command. Set the photodiode
current set point to ½ full scale via the
LAS:MDI
command. Place the
unit into constant photodiode current mode via the
LAS:MODE:MDI
command.
c. Enter the
LAS:OUTPUT ON
command to turn the laser output on.
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78 Chapter 7 Calibration
d. Enter the
LAS:CAL:MDI
command to place the 6000 in its laser
photodiode current calibration mode.
e. After a few seconds, the 6000 will be ready for the actual photodiode
current to be entered via the
LAS:MDI
command. The measured value
of the current should not be entered until the 6000 is ready to receive it.
The 6000 will be ready to receive the current value when, after a
LAS:CAL:MDI?
query is sent, the response from the 6000 is "1".
f. Once the actual photodiode current value is entered via the
LAS:MDI
command, the 6000 will apply a new photodiode current equal to approximately one-fourth (¼) the previous set point.
The 6000 will be ready to receive the second current value when, after a
LAS:CAL:MDI?
query is sent, the response from the 6000 is "1".
g. Input the second actual (measured) photodiode current as in Step e.
h. Once the actual photodiode current value is entered via the second
LAS:MDI
command, the 6000 leaves the current calibration mode.
If, at any time prior to the second
LAS:MDI,
a command other than
LAS:MDI
or
LAS:CAL:MDI?
is sent to the 6000, the 6000 will
cancel the calibration mode and then process the command(s).
The *
OPC?
query may be used to determine when the calibration is
completed.
The operation complete flag (bit 0 of the Standard Event Status
Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
7.2.7 Local Operation Laser Voltage Measurement Calibration
a. With the output off, connect a calibrated voltmeter, in parallel with a
load resistor, as selected Table 1 0, to the laser output terminals.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the slot soft key that corresponds to the
module to be calibrated.
c. Press the
Setup
soft key and set the laser current limit (
Io Lim
) to 80%
of the maximum current plus 100 mA and the laser voltage compliance
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Chapter 7 Calibration 79
limit (
Vcomp
) to 5.0 V, and output bandwidth as desired. Press the
soft key to return to the single display.
d. Press the
LDD ON
key to turn the laser output on, if it is not on already. If a laser on delay has been set, wait that amount of time to allow the laser output to engage.
e. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Vf
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft
key is pressed at any point prior to completing the calibration.
7.2.8 Remote Operation Laser Voltage Measurement Calibration
a. With the output off, connect a calibrated voltmeter, in parallel a load
resistor, as selected Table 10, to the laser output terminals.
b. Select the channel via the
LAS:CHAN
command. Set the voltage limit
to full scale via the
LAS:LIM:LDV
command, and the current set point necessary to read approximately 80% of full scale voltage. For example, with a 6560A module, with a resistance of 1 , set the current to 4,800 mA. Place the unit into constant current mode via the
LAS:MODE:LDI
command.
c. Enter the
LAS:OUTPUT ON
command to turn the laser output on.
d. Enter the laser voltage calibration mode by issuing the
LAS:CAL:LDV
command.
e.
Input the actual (measured) laser voltage (as an <nrf value>) via the
LAS:LDV <nrf value>
command.
The 6000 will be ready to receive the value when, after a
LAS:CAL:LDV?
query is sent, the response from the 6000 is "1".
f. Once the actual voltage value is entered via the
LAS:LDV
command, the 6000 will apply a new current equal to approximately one-fourth (¼) the previous set point.
The 6000 will be ready to receive the second voltage value when, after
a
LAS:CAL:LDV?
query is sent, the response from the 6000 is "1".
g. Input the second actual (measured) voltage as in Step e.
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80 Chapter 7 Calibration
h. Once the actual voltage value is entered via the
LAS:LDV
command,
the 6000 leaves the current calibration mode.
If, at any time prior to the second
LAS:LDV,
a command other than
LAS:LDV
or
LAS:CAL:LDV?
is sent to the 6000, the 6000 will
cancel the calibration mode and then process the command(s).
The *
OPC?
query may be used to determine when the calibration is
completed.
The operation complete flag (bit 0 of the Standard Event Status
Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
7.3 TEC Calibration
This chapter describes how to calibrate the TEC modules.
7.3.1 Recommended Equipment
Recommended test equipment for calibrating the module is listed in Table 11. Equipment other than that shown in the table may be used if the specifications meet or exceed those listed.
Description
Mfg./Model
Specification
DMM
HP34401A
DC Amps @ 1.0 A): ±1% Resistance (@ 10 ohms): 0.02%
Resistors
Metal Film
20 kΩ for 100µA calibration 200 kΩ for 10µA calibration 3 kΩ for LM335 sensor calibration 16 kΩ for AD590 sensor calibration 100 Ω for RTD sensor calibration
Resistor
High Power
1 Ω, 50 W, for current calibration
Connector
D-sub
15-pin male
Table 11 - Recommended Test Equipment
7.3.2 Local Operation Thermistor Calibration
a. Measure and record the exact resistance of your metal film resistor. Use
nominal values of 20 kΩ for the 100µA setting, and 200 kΩ for the
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Chapter 7 Calibration 81
10µA setting. With the TEC output off, connect the metal film resistor to the sensor input of the TEC Module.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the appropriate thermistor (10µA or
100µA) as the sensor type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Sensor
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft key is pressed at any point prior to completing the calibration.
7.3.3 Remote Operation Thermistor Calibration
a. Measure and record the exact resistance of your metal film resistor. Use
nominal values of 20 kΩ for the 100µA setting, and 200 kΩ for the 10µA setting. With the TEC output off, connect the metal film resistor to the sensor input of the TEC Module.
b. Enter the
TEC:CHAN
command to select the channel to be calibrated.
Send
TEC:SENS 1
100µA thermistor, or
TEC:SENS 2
for the 1 0µA
thermistor, followed by the
TEC:CAL:SEN
to enter sensor calibration
mode.
The 6000 will be ready to receive the resistance when, after a
TEC:CAL:SEN?
query is sent, a “1” is returned.
c. Input the actual resistance of the metal film resistor, in kΩ, (as an <nrf
value>) via the
TEC:R <nrf value>
command.
If, at any time prior to
TEC:R,
a command other than
TEC:R
or
TEC:R?
is sent to the 6000, the 6000 will cancel the calibration mode
and then process the command(s).
Once the
TEC:R
value is sent, the
OPC?
que ry may be used to determine when the calibration is completed. The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
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82 Chapter 7 Calibration
7.3.4 Local Operation AD590 Sensor Calibration
a. With the TEC output off, connect a precision 16 kΩ metal film resistor
and a precision ammeter in series at the sensor input of the TEC Module.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the AD590 as the Sensor Type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Sensor
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft key is pressed at any point prior to completing the calibration.
7.3.5 Remote Operation AD590 Sensor Calibration
a. With the TEC output off, connect a precision 16 kΩ metal film resistor
and a precision ammeter in series at the sensor input of the TEC Module.
b. Enter the
TEC:CHAN
command to select the channel to be calibrated.
Enter the
TEC:SEN 4
and
TEC:CAL:SEN
to select the AD590 sensor
and enter sensor calibration mode.
The 6000 will be ready to receive the current value when, after a
TEC:CAL:SEN?
query is sent, the response from the 6000 is “1”.
c. Input the actual current measured, in µA, by the external ammeter (as
an <nrf value>) via the
TEC:R <nrf value>
command.
If, at any time prior to
TEC:R,
a command other than
TEC:R
or
TEC:R?
is sent to the 6000, the 6000 will cancel the calibration mode
and then process the command(s).
Once the
TEC:R
value is sent, the
OPC?
que ry may be used to determine when the calibration is completed. The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
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Chapter 7 Calibration 83
7.3.6 Local Operation LM335 Sensor Calibration
a. Use a 3 kΩ metal film resistor. With the TEC output off, connect the
metal film resistor in parallel with a precision voltmeter to the sensor input of the TEC Module.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the LM335 as the Sensor Type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Sensor
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft key is pressed at any point prior to completing the calibration.
7.3.7 Remote Operation LM335 Sensor Calibration
a. With the TEC output off, connect a 3 kΩ metal film resistor and a
precision voltmeter in parallel at the sensor input of the TEC module.
b. Enter the
TEC:CHAN
command to select the channel to be calibrated.
Enter the
TEC:SEN 3
and
TEC:CAL:SEN
to select the LM335 sensor
and enter sensor calibration mode.
The 6000 will be ready to receive the voltage value when, after a
TEC:CAL:SEN?
query is sent, the response from the 6000 is "1".
c. Input the actual voltage, in mV, measured by the external voltmeter (as
an <nrf value>) via the
TEC:R <nrf value>
command.
If, at any time prior to
TEC:R,
a command other than
TEC:R
or
TEC:R?
is sent to the 6000, the 6000 will cancel the calibration mode
and then process the command(s).
Once the
TEC:R
value is sent, the
OPC?
que ry may be used to determine when the calibration is completed. The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
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84 Chapter 7 Calibration
7.3.8 Local Operation RTD Calibration
a. Measure and record the exact resistance of your 100 Ω metal film
resistor. With the TEC output off, connect the metal film resistor to the sensor input of the TEC Module.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the RTD as the Sensor Type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
Sensor
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft key is pressed at any point prior to completing the calibration.
7.3.9 Remote Operation RTD Calibration
a. Measure and record the exact resistance of your 100 Ω metal film
resistor. With the TEC output off, connect the metal film resistor to the sensor input of the TEC Module.
b. Enter the
TEC:CHAN
command to select the channel to be calibrated.
Send
TEC:SENS 5
to select the RTD sensor, followed by the
TEC:CAL:SEN
to enter sensor calibration mode.
The 6000 will be ready to receive the resistance when, after a
TEC:CAL:SEN?
query is sent, a “1” is returned.
c. Input the actual resistance, in ohms, of the metal film resistor (as an
<nrf value>) via the
TEC:R <nrf value>
command.
If, at any time prior to
TEC:R,
a command other than
TEC:R
or
TEC:R?
is sent to the 6000, the 6000 will cancel the calibration mode
and then process the command(s).
Once the
TEC:R
value is sent, the
OPC?
que ry may be used to determine when the calibration is completed. The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
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Chapter 7 Calibration 85
7.3.10 RTD Lead Resistance Calibration (Offset Null)
Because the RTD sensor reflects changes in temperature with small changes in resistance, even a small lead resista nc e (resistance c aused by the wire running between the TEC module and the RTD sensor) can cause significant temperature offset. The lead resistance may be taken out of the RTD reading as follows:
a. With the TEC output off, short the sensor wires as close to the RTD
sensor as possible.
b. Go to the single module display by first pressing the
MENU
button,
then the
Modules
soft key, then the TEC module soft key.
c. Press the
Setup
soft key and select the RTD as the Sensor Type.
d. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
RTD Null
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft key is pressed at any point prior to completing the
calibration.
7.3.11 Local Operation ITE Current Calibration
The following procedure is for calibrating the ITE constant current source for both polarities of current.
a. With the output off, connect a 1 , 50 W resistor and a calibrated
ammeter in series across the laser output terminals. If an ammeter with the appropriate current ratings is unavailable, connect a 1 , 50 W resistor across the laser output terminals and use a calibrated DMM to measure the voltage across the resistor. Calculate the current in the following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Go to the calibration display by first pressing the
MENU
button, then
the
Config
soft key, then the
Cal
soft key, then the channel to be
calibrated. At the calibration screen, press the
I
TE
soft key. Follow the on-screen instructions to complete the calibration. The calibration can be terminated without affecting the stored constants if the
Term
soft
key is pressed at any point prior to completing the calibration.
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86 Chapter 7 Calibration
7.3.12 Remote Operation ITE Current Calibration, Single Channel TEC
a. With the output off, connect a 1 , 50 W resistor and a calibrated
ammeter in series across the laser output terminals. If an ammeter with the appropriate current ratings is unavailable, connect a 1 , 50 W resistor across the laser output terminals and use a calibrated DMM to measure the voltage across the resistor. Calculate the current in the following steps by using Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b.
Enter the
TEC:CHAN
command to select the channel to be calibrated.
Send
TEC:CAL:ITE
to enter I
TE
calibration mode.
The module will be placed in I
TE
mode, limit set to 50% of full scale
plus 100 mA, and the I
TE
set point set to 50% of full scale.
The 6000 will be ready to receive the first measured current value
when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
c. Input the actual current (as an <nrf value>) via the
TEC:ITE <nrf
value>
command. The 6000 will then drive the current to 25% of the
initial set point.
The 6000 will be ready to receive the second measured current value
when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
d. Input the second actual current (as an <nrf value>) via the
TEC:ITE
<nrf value>
command. The 6000 will then drive the current to the
negative current value of the initial set point.
The 6000 will be ready to receive the third measured current value
when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
e. Input the third actual current (as an <nrf value>) via the
TEC:ITE <nrf
value>
command. The 6000 will then drive the current to 25% of the
negative current value of the initial set point.
The 6000 will be ready to receive the fourth measured current value
when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
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Chapter 7 Calibration 87
f. Input the fourth actual current (as an <nrf value>) via the
TEC:ITE
<nrf value>
command.
If, at any time prior to the last
TEC:ITE,
a command other than
TEC:ITE
or
TEC:ITE?
is sent to the 6000, the 6000 will cancel the
calibration mode and then process the command(s).
Once the
TEC:ITE
value is sent, the
OPC?
que ry may be used to determine when the calibration is completed. The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger an interrupt. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register and using the
*OPC
command.
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89
CHAPTER 8
8.
Factory Service
8.1 Introduction
This section contains info rmation regar ding obtaining factory service for the Model
6000. The user should not attempt any maintenance or service of this instrument and/or accessories beyond the procedures given in chapters 6 and 7. Any problems which cannot be resolved using the guidelines listed in chapters 6 and 7 should be referred to Newport Corporation factory service personnel. Contact Newport Corporation or your Newport representative for assistance.
8.2 Obtaining Service
To obtain information concerning factory service, contact Newport Corporation or your Newport representative. Please have the following information available:
1. Instrument model number (On front panel)
2. Instrument seri al number (On rea r panel)
3. Description of the problem.
If the instrument is to be returned to Newport Corporation, you will be given a Return Materials Authorization (RMA) number, which you should reference in your shipping documents as well as clearly marked on the outside of the shipping container.
Please fill out the service form, located on the following page, and have the information ready when contacting Newport Corporation. Return the completed service form with the instrument.
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