Newport 6000 Operation And Maintenance Manual

i

Model 6000 Laser Controller

Operation and Maintenance Manual

Corporate Headquarters Canada Italy Netherlands Taiwan R.O.C.

Newport Corporation Telephone: [phone] Telephone: [phone] Telephone: [phone] Telephone: [phone]
1791 Deere Avenue Facsimile: 905-567-0392 Facsimile: 02-923-2448 Facsimile: 030-6570242 Facsimile: 2-2769-9638
Irvine, CA 92714

France Japan Switzerland United Kingdom

Telephone: [phone] Telephone: [phone] Telephone: [phone] Telephone: [phone] Telephone: [phone]
Facsimile: 949-253-1800 Facsimile: 1-60 91 68 69 Facsimile: 03-5379-0155 Facsimile: 01-740-2503 Facsimile: 01635-521348

Belgium

Germany

Telephone: [phone] Telephone: [phone]
Facsimile: 016-402227 Facsimile: 06151-36 21-52

Newport Corporation, Irvine,
California, has been certified
compliant with ISO 9002 by the
British Standards Institution.

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

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

i

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

ii

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

iii

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

iv

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

v

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

vi

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

1

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

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

Ω

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

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

Ω

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.

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.

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.

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.

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.

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

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.

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

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.

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

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

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

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

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

.

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.

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

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

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.

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.

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

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.

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.

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

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.

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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 MΩ 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.

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

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:

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.

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

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.

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.

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.

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.

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.

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.

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

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

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

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

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

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

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.

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.

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.

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)

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

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.

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

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

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 Ω at temperature T.

T is the temperature in °C.

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 Ω, but can be
varied from 95.00 Ω to 105.00 Ω.

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.

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 Ω, 50 W; 2 Ω, 25 W; 5 Ω, 10 W;
10 Ω, 5 W; 30 Ω, 2 W

Optical
Isolator

NEC PS2501-1

or equivalent, 6-pin

Connector

D-sub

9-pin male

Table 9 - Recommended Test Equipment

74 Chapter 7 Calibration

7.2.2 Drive Current Load Resistor Selection

Laser Drive Current

Resistor

200 mA

30 Ω, 2 W

500 mA

10 Ω, 5 W

1,000 mA

5 Ω, 10 W

3,000 mA

2 Ω, 25 W

6,000 mA

1 Ω, 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.

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

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

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.

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

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 Ω, 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.

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

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.

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.

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.

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.

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 Ω, 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 Ω, 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.

86 Chapter 7 Calibration

7.3.12 Remote Operation ITE Current Calibration, Single Channel
TEC

a. With the output off, connect a 1 Ω, 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 Ω, 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.

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.

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.