THORLABS ITC502, ITC510 Operation Manual

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Operation Manual

Thorlabs Instrumentation

Laser Diode Combi Controller

ITC502 (-IEEE) ITC510 (-IEEE)

2006

Version: 2.16

Date: 25.07.2006

2006, Thorlabs

Contents page

1 General description of the ITC5xx controller 1

1.1 Packing List 1

1.2 Safety 1

1.3 Features 4

1.4 Mode of operation 6

1.5 Technical Data 7

1.5.1 Technical data ITC502 7

1.5.2 Technical data ITC510 10

1.6 Operating elements at the front panel 14

1.7 Operating elements at the rear panel 15

1.8 Pre-settings 16

1.8.1 Setting the limit of the laser current I

LD LIM

1.8.2 Setting the limit value of the TEC current 16

1.8.3 Setting the temperature window 16

1.8.4 DIP switch for “wake up“ preset 17

1.9 Connecting components 20

1.9.1 Pin assignment for the laser diode output 20

1.9.2 Pin assignment of the TEC output jack 22

1.9.3 Connecting a thermistor 23

1.9.4 Connecting a temperature sensor AD590 or AD592 24

1.9.5 Connecting a temperature sensor LM135 or LM335 25

1.9.6 Connecting a TEC element 25

1.9.7 Connecting the status indicator 27

1.9.8 Connecting laser- and monitor diode 27

1.9.9 Connecting interlock and status LED 29

1.9.10 Temperature tune input 30

2 Operating the ITC5xx 31

2.1 Mains voltage selector 31

2.2 Mains switch 31

2.3 Main setting knobs 31

2.4 Display 32

2.5 Select the value to be displayed 33

2.6 Operating Mode of the laser diode (MODE) 34

2.7 Polarity of the laser diode (LD POL) 36

2.8 Polarity of the monitor diode (PD POL) 36

2.9 Bias voltage of the monitor diode (BIAS) 36

2.10 Adjusting the bias voltage of the monitor diode 38

2.11 Adjusting the power display of an internal monitor diode 38

2.12 Temperature window protection 40

2.13 Selecting the temperature sensor 40

2.14 Polarity check of the TEC element 41

2.15 Setup and function of temperature controllers 42

2.15.1 Statements and implications 42

2.15.2 Demands to the ideal temperature control loop 43

2.15.3 Influences on the real temperature control loop 43

2.15.4 PID adjustment 45

2.16 Analog modulation input 48

2.17 Analog output (ILD) 49

2.18 Laser and TEC current ON/OFF 50

2.19 CP gain 51

2.20 BNC connector TEMP OUT 51

2.21 BNC connector Temp tune 52

2.22 Using the interlock input 52

2.22.1 Examples of various protection functions 53

2.23 Laser voltage measurement 54

3 Remote control by a PC (ITC5xx-IEEE) 55

3.1 IEEE488 Interface 56

3.1.1 Interface specifications 56

3.1.2 Setting up the Interface 57

3.1.3 Connecting the Instrument 59

3.1.4 IEEE488 bus commands 60

3.2 Before Programming 62

3.2.1 Nomenclature 62

3.2.2 Program and response messages 62

3.2.3 Data format 63

3.3 Common commands and queries 65

3.3.1 Identification query 65

3.3.2 Reset 65

3.3.3 Self-test query 65

3.3.4 Set Operation-complete bit 65

3.3.5 Operation-complete query 66

3.3.6 Wait 66

3.3.7 Event-Status-Enable-Register (ESE) 66

3.3.8 Query Standard-Event-Status-Register (ESR) 66

3.3.9 Service-Request-Enable-Register (SRE) 67

3.3.10 Query Status-Byte-Register (STB) 67

3.4 System command group 68

3.4.1 Answer mode 68

3.4.2 Error-LED mode 68

3.4.3 Querying the error queue 69

3.4.4 Averaging rate 69

3.5 Status command group 70

3.5.1 Query Device-Error-Condition-Register (DEC) 70

3.5.2 Query Device-Error-Event-Register (DEE) 70

3.5.3 Device-Error-Event-Enable-Register (EDE) 70

3.6 ITC5xx specific commands 71

3.6.1 Operation mode (MODE) 71

3.6.2 Laser diode polarity (LDPOL) 71

3.6.3 Photo diode polarity (PDPOL) 72

3.6.4 Reading the state of the temperature protection (TP) 72

3.6.5 Switching the bias voltage on and off (PDBIA) 73

3.6.6 Turn the output on and off (LASER) 74

3.6.7 Reading the laser diode hardware limit (LIMCP) 75

3.6.8 Laser diode current (ILD) 75

3.6.9 Monitor diode current (IMD) 76

3.6.10 Calibrating a photo diode (CALPD) 77

3.6.11 Optical power (POPT) 78

3.6.12 Reading the optical power from the display (POPTP) 79

3.6.13 Reading the laser diode voltage (VLD) 79

3.6.14 Reading the bias voltage (VBIAS) 79

3.6.15 Temperature Sensor (SENS) 80

3.6.16 Switching the TEC on and off (TEC) 80

3.6.17 Temperature (only AD590) (TEMP) 81

3.6.18 Resistance of the thermistor (RESI) 82

3.6.19 Reading the TEC current hardware limit (LIMTP) 83

3.6.20 Reading the TEC current (ITE) 83

3.6.21 Reading the temperature/resistance window (WIN) 83

3.6.22 Reading the TEC voltage (VTE) 83

3.7 Error messages of the ITC5xx 84

3.7.1 General errors 84

3.7.2 ITC5xx operation error messages 87

3.8 Status reporting 90

3.8.1 Standard event status register (ESR) 90

3.8.2 Standard event status enable register (ESE) 93

3.8.3 Status byte register (STB) 93

3.8.4 Service request enable register (SRE) 94

3.8.5 Reading the STB by detecting SRQ 94

3.8.6 Reading the STB by *STB? command 94

3.8.7 Reading the STB by serial poll 94

3.8.8 Device error condition register (DEC) 95

3.8.9 Device error event register (DEE) 96

3.8.10 Device error event enable register (EDE) 96

3.9 Hints for setting up control programs 97

4 Maintenance 100

4.1 Repair 100

4.2 Cleaning 100

4.3 Selecting the line voltage 100

4.4 Exchanging the line fuse 101

4.5 Trouble-shooting 103

5 Service 106

5.1 Exchange of internal fuses 106

6 Appendix 107

6.1 Warranty 107

6.2 Certifications and compliances 108

6.3 Thorlabs “End of Life” policy (WEEE) 109

6.3.1 Waste treatment on your own responsibility 110

6.3.2 Ecological background 110

6.4 List of acronyms 111

6.5 List of figures 113

7 Addresses 114

We aim to develop and produce the best solution for your application in the field of optical measurement technique. To help us to come up to your expectations and develop our products permanently we need your ideas and suggestions. Therefore, please let us know about possible criticism or ideas. We and our international partners are looking forward to hearing from you.

Thorlabs

This operation manual contains specific information on how to operate the laser

diode controller ITC502 and ITC510. A general description is followed by

explanations of how to operate the unit manually. You will also find informations

about remote control via the IEEE 488 computer interface.

Attention

This manual contains “WARNINGS” and “ATTENTION” label in this

form to indicate dangers for persons or possible damage of

equipment.

Please read these advises carefully!

NOTE

This manual also contains “NOTES” and “HINTS” written in this form.

1.1 Packing List

ITC500 / page 1

1 General description of the ITC5xx controller

1.1 Packing List

1 ITC502 or ITC510 packed in plastic form parts

1 power cord, connector according to ordering country

1 operation manual

1 CD-ROM with Drivers (for ITC5xx-IEEE)

1 Connection cable CAB 400

1 Connection cable CAB 420-15

1.2 Safety

 Attention 

All statements regarding safety of operation and technical data in

this instruction manual will only apply when the unit is operated

correctly.

Before applying power to your ITC5xx system, make sure that the

protective conductor of the 3 conductor mains power cord is

correctly connected to the protective earth contact of the socket

outlet!

Improper grounding can cause electric shock with damage to your

health or even death!

Also make sure that the line voltage setting marked on the rear panel

agrees with your local supply and that the corresponding fuses are

inserted. If not, please change the voltage (see 4.3) and.

the mains fuse (see section 4.4)

Prior to operation make sure that the correct line voltage is set and

the appropriate fuse inserted.

All in- or outputs must only be operated with duly shielded

connection cables.

1.2 Safety

ITC500 / page 2

Only with written consent from Thorlabs may changes to single

components be carried out or components not supplied by Thorlabs

be used.

This precision device is only dispatchable if duly packed into the

complete original packaging including the plastic form parts. If

necessary, ask for a replacement package.

 Attention 

Semiconductor laser modules can deliver up to several 100mW of

(maybe) invisible laser radiation!

When operated incorrectly, this can cause severe damage to your

eyes and health!

Be sure to pay strict attention to the safety recommendations of the

appropriate laser safety class!

This laser safety class is marked on your external laser source used.

 Attention 

Mobile telephones, handy phones or other radio transmitters are not

to be used within the range of three meters of this unit since the

electromagnetic field intensity may then exceed the maximum

allowed disturbance values according to EN 50 082-1.

To connect the unit to the mains, only use the supplied mains cable

with safety mains plug. The unit is grounded via the protective

conductor of this cable. To avoid electrical shock the plug of the

mains cable is to be inserted into a correctly grounded socket.

1.2 Safety

ITC500 / page 3

To guarantee a safe operation of the ITC5xx always pay attention to keep the

ventilation slots on the sides and the fan air inlet at the rear of the unit free from

obstacles.

 Attention 

The unit must not be operated in explosion endangered

environments!

The user must not open the unit during operation. An internal adjustment as well as a

replacement of parts is only to be carried out by respectively trained service

personnel. Parts must not be exchanged when the unit is switched on.

Dangerous voltages may even be present with the unit off line and the power cord

removed!.

1.3 Features

ITC500 / page 4

1.3 Features

• Key-operated power switch

Protection against unauthorized or accidental use.

• Defined states after switch-on

When switching on the ITC5xx with the mains switch the laser and TEC current

outputs are always switched off. The ITC5xx will always wake up in a mode that

can be selected via a DIP switch at the rear.

• Softstart

The switch on delay of the softstart function protects the laser diode against

undesired transients.

• Limit for the laser diode- and the TEC current (hardware limit)

Manually adjustable current limits restrict the maximum allowed current. The limit

values are set with two 25-turn potentiometers at the front panel.

• Interlock The interlock input realizes several protective functions simultaneously.

• Safety lock to prevent unintentional use

• Cable damage monitoring

• An external emergency switch may be connected

• Application of external automatic protection equipment, e.g. for the temperature

of cooling water

• ON/OFF LED of the laser diode

The laser can only be operated with the interlock input being duly closed.

• Contact protection of the laser diode (open circuit)

If the cable connecting the laser should be interrupted even for a short time during

operation, an emergency switch turns off laser current immediately.

• Contact failure display of the TEC element (open circuit)

Cable damage, bad contact or too high resistive TEC element is displayed with a

LED. The output will remain switched on since also a wrong TEC element can still

provide cooling and thus further protects the laser diode.

1.3 Features

ITC500 / page 5

• Protection of the DUT against sensor failure

Protection against use of an incorrect temperature sensor / protection against line

interruption to the temperature sensor.

• Electronic short-circuit switch for the laser diode

With the current module off an electronic switch will short-circuit the laser diode to

protect against static discharges etc.

• Control LED of laser- and TEC current being active

If the current is switched on an LED lights up to indicate device is on.

• Temperature window protection of the laser diode

Operation in a specified temperature range.

• Over-temperature protection

The ITC5xx contains an automatic over-temperature protection in case that the

allowed internal operating temperature of the ITC5xx should be exceeded. In this

case the output is turned off. After internal temperature drop of about 10 °C the

output current of the ITC5xx can be switched on again.

• Mains filter

Protection against line failures (protection against transients) and other

electromagnetic interference's.

• Line failure monitoring

In case of line failure/line interruption the ITC5xx will wake up again with the laser

output switched off.

1.4 Mode of operation

ITC500 / page 6

1.4 Mode of operation

A fixed adjustable hardware limit limits the maximum deliverable laser current in each

operating mode.

The laser diode is sourced unipolar against ground (anode or cathode to ground may

be selected). This is of advantage regarding the stability of the laser current, noise

and RF influences.

The monitor diode input is a transimpedance amplifier (input impedance 0 Ω). Both

polarities of the monitor diode can be selected. The monitor diode may either be

operated photovoltaic (without bias voltage) or photoconductive, i.e. with bias voltage

(selectable in a range from 0 ... 10 V).

The limit value for the TEC current and the temperature window are set with screw-

driver potentiometers.

The TEC element always operates against ground. This is of considerable advantage

regarding the safety of the TEC element and the stability of the TEC current.

The sensor input is designed for different types of temperature sensors.

A missing sensor or the selection of a incorrect type will be detected.

The ITC5xx has an input for an IC temperature sensor of the AD590/592 or

LM35/135/335 series as well as an input for a thermistor. If a thermistor is used you

can choose between two resistance ranges (maximum resistance of the thermistor 20 kΩ or 200kΩ).

The set values for the temperature and the thermistor resistance are set with the 10-

turn main dial knob.

The P-, I- and D-share of the analog control loop are set with „thumb-nail“-

potentiometers.

All settings are done by the operating elements or via the IEEE488-interface (ITC5xx-

IEEE) and a PC. Only the hardware limits for the currents must be set manually. No

manual settings are required during automatic tests using a PC.

1.5 Technical Data

ITC500 / page 7

1.5 Technical Data

(The technical data are valid at 23 ± 5°C and 45 ±15% rel. humidity)

1.5.1 Technical data ITC502

General Data

Line voltage 100 V / 115 V / 230 V (-10%, +15 %) (fixed)

Line frequency 50 ... 60 Hz

Max. power consumption 90 VA

Supply mains overvoltage Category II (Cat II)

Operating temperature 1) 0 ... +40°C Storage temperature -40°C ... +70°C

Relative Humidity Max. 80% up to 31°C, decreasing to 50% at 40 °C

Pollution Degree (indoor use only) 2 Warm up time for rated accuracy ≤ 10 min

Operation altitude < 3000 m Weight < 7 kg

Dimensions (W x H x D) including operating elements 220 x 120 x 376 mm3

without operating elements 220 x 110 x 351 mm3

Current control

Range of laser current ILD 0 ... ± 200 mA Compliance voltage > 6 V Setting resolution (manual / remote control) 10 µA / 3 µA Measurement resolution (manual / remote control) 10 µA / 1 µA Accuracy ± 100 µA Noise without ripple (10 Hz ... 10 MHz, rms), typ. < 1.5 µA Ripple (50/60 Hz, rms), typ. < 1.5 µA Transients, typ. < 0.2 mA Drift, 24 hours, typ. (0…10Hz, without changing the ambient temperature) < 10 µA Temperature coefficient ≤ 50 ppm/°C

Power control

Range of monitor current IPD 5 µA ... 2 mA

Setting resolution (manual / remote control) 0.1 µA / 0.03 µA

non condensing

other ranges on request

1.5 Technical Data

ITC500 / page 8

Measurement resolution (manual / remote control) 0.1 µA / 0.01 µA Accuracy ± 2 µA

Photodiode bias voltage 0 ... 10 V

Laser voltage Measurement principle 4-wire

Measurement range 0 ... 10 V

Measurement resolution (manual / remote control) 1 mV / 0.1 mV Accuracy ± 20 mV

Analog control output

Load resistance ≥ 10 kΩ

Output voltage for 0 ... I

LD MAX

0 ... ± 10 V

Transmission coefficient 50 V/A ± 5%

LD Current limit

Setting range I

LIM

0 ... ≥ 200 mA

Measurement resolution (manual / remote control) 10 µA / 1 µA Accuracy ± 0.5 mA

Analog modulation input

Input impedance 10 kΩ

Small signal 3 dB bandwidth (CC mode) DC ... 500 kHz

Laser diode modulation coefficient (CC mode) 20 mA/V ± 5%

Laser diode modulation coefficient (CP mode) 0.2 mA/V ± 5%

Current output TEC element

Control range - 2 A ... + 2 A

Maximum output power 16 W Compliance voltage > 8 V

Measurement resolution (manual / remote control) 1 mA / 0.1 mA

Measurement accuracy ± 10 mA Noise and ripple (typ.) < 1 mA

Measurement resolution TEC voltage (manual / remote control) 1 mV / 0.1 mV

Measurement accuracy TEC voltage ± 40 mV

sign depends on selected polarity

1.5 Technical Data

ITC500 / page 9

TEC Current limit

Setting range 0 ... ≥ 2 A

Measurement resolution (manual / remote control) 1 mA / 0.1 mA Accuracy ± 20 mA

Temperature sensors AD590, AD592, LM135, LM335

Control range (AD590, LM135) - 45 °C ... + 145 °C

Control range (AD592) - 25 °C ... + 105 °C

Control range (LM335) - 40 °C ... + 100 °C

Setting resolution (manual / remote control) 0.01 °C / 0.003 °C

Measurement resolution (manual / remote control) 0.01 °C / 0.001 °C Accuracy ± 0.1 °C Temperature stability (24 hours) ≤ 0.001 °C

Thermistor (2 kΩ / 20 kΩ range) Measurement current 100µA / 10 µA Control range 10 Ω ... 19.99 kΩ / 100 Ω ... 199.9 kΩ Setting resolution (manual control) 1 Ω / 10 Ω Setting resolution (remote control) 0.3 Ω / 3 Ω Measurement resolution (manual control) 1 Ω / 10 Ω Measurement resolution (remote control) 0.1 Ω / 1 Ω Accuracy ± 5 Ω / ± 50 Ω

Temperature stability (24 hours) 1) ≤ 0.5 Ω / ≤ 5 Ω

Temperature control input

Input resistance 10 kΩ

Control voltage -10 ... +10 V

Transmission coefficient IC-sensors

2 °C/V ±5%

Transmission coefficient thermistor (20 kΩ / 200 kΩ range)

0.2 kΩ/V / 2 kΩ/V ±5%

Due to the nonlinear conversion from Ω to °C the stability in °C depends on the operating conditions

and the characteristics of the thermistor. E.g. for a typical thermistor at a set point of 10kΩ (25°C), a

0.5Ω stability translates into about 1mK temperature stability. At a set point of 5kΩ (38°C), the stability

is about 2mK.

1.5 Technical Data

ITC500 / page 10

Temperature control Output

Load resistance > 10 kΩ

Output voltage

0 ... ± 10 V

Transmission coefficient IC sensors 50 mV / °C ± 5% Transmission coeff. thermistor (20 kΩ / 200 kΩ range) 500 mV/ kΩ / 50 mV/kΩ ± 5%

Temperature window protection

Setting range T

WIN

0.5 °C ... 20 °C

Setting range R

WIN

(20 kΩ / 200 kΩ range) 50 Ω ... 2 kΩ / 500 Ω ... 20 kΩ

Computer Interface

Setting resolution 16 Bit

Measurement resolution 12 ... 18 Bit 1)

1.5.2 Technical data ITC510

General Data

Line voltage 100 V / 115 V / 230 V (-10%, +15 %) (fixed)

Line frequency 50 ... 60 Hz

Max. power consumption 150 VA

Supply mains overvoltage Overvoltage category II (Cat II)

Operating temperature 2 0 ... +40°C Storage temperature -40°C ... +70°C

Relative Humidity Max. 80% up to 31°C, decreasing to 50% at 40 °C

Operation altitude < 3000 m

Pollution Degree (indoor use only) 2 Warm up time for rated accuracy ≤ 10 min Weight < 7 kg

Dimensions 220 x 120 x 377 mm

in High Resolution mode, at reduced measurement speed

non condensing

1.5 Technical Data

ITC500 / page 11

Current control

Range of laser current ILD 0 ... ± 1 A Compliance voltage > 6 V Setting resolution (manual / remote control) 100 µA / 15 µA Measurement resolution (manual / remote control) 100 µA / 10 µA Accuracy ± 1 mA Noise without ripple (10 Hz ... 10 MHz, rms, typ.) < 5 µA Ripple (50/60 Hz, rms, typ.) < 3 µA Transients (typ.) < 1 mA Drift (24 hours, 0…10Hz, at constant ambient temperature, typ.) < 30 µA Temperature coefficient ≤ 50 ppm/°C

Power control

Range of monitor current IPD 5 µA ... 2 mA

Setting resolution (manual / remote control) 0.1 µA / 0.03 µA Measurement resolution (manual / remote control) 0.1 µA / 0.01 µA Accuracy ± 2 µA

Photodiode bias voltage 0 ... 10 V

Laser voltage Measurement principle 4-wire

Measurement range 0 ... 10 V

Measurement resolution (manual / remote control) 1 mV / 0.1 mV Accuracy ± 20 mV

Analog control output

Load resistance ≥ 10 kΩ

Output voltage for 0 ... I

LD MAX

0 ... ± 10 V

Transmission coefficient 10 V/A ± 5%

LD Current limit

Setting range I

LIM

0 ... ≥ 1 A

Measurement resolution (manual / remote control) 100 µA / 10 µA Accuracy ± 2.5 mA

other ranges on request

sign depends on selected polarity

1.5 Technical Data

ITC500 / page 12

Analog modulation input

Input impedance 10 kΩ

Small signal 3 dB bandwidth (CC mode) DC ... 200 kHz

Laser diode modulation coefficient (CC mode) 100 mA/V ± 5%

Laser diode modulation coefficient (CP mode) 0.2 mA/V ± 5%

Current output TEC element

Control range - 4 A ... + 4 A

Maximum output power 32 W Compliance voltage > 8 V

Measurement resolution (manual / remote control) 1 mA / 0.1 mA

Measurement accuracy ± 20 mA Noise and ripple (typ.) < 2 mA

Measurement resolution TEC voltage (manual / remote control) 1 mV / 0.1 mV

Measurement accuracy TEC voltage ± 40 mV

TEC Current limit

Setting range 0 ... ≥ 4 A

Measurement resolution (manual / remote control) 1 mA / 0.1 mA Accuracy ± 40 mA

Temperature sensors AD590, AD592, LM135, LM335

Control range (AD590, LM135) - 45 °C ... + 145 °C

Control range (AD592) - 25 °C ... + 105 °C

Control range (LM335) - 40 °C ... + 100 °C

Setting resolution (manual / remote control) 0.01 °C / 0.003 °C

Measurement resolution (manual / remote control) 0.01 °C / 0.001 °C Accuracy ± 0.1 °C Temperature stability (24 hours) ≤ 0.001 °C

1.5 Technical Data

ITC500 / page 13

Temperature stability (24 hours) 1) ≤ 0.5 Ω / ≤ 5 Ω

Temperature control input

Input resistance 10 kΩ

Control voltage -10 ... +10 V

Transmission coefficient IC-sensors

2 °C/V ±5%

Transmission coefficient thermistor (20 kΩ / 200 kΩ range) 0.2 kΩ/V / 2 kΩ/V ±5%

Temperature control Output

Load resistance > 10 kΩ

Output voltage

0 ... ± 10 V

Transmission coefficient thermistor 500 mV/ kΩ / 50 mV/kΩ ± 5%

Transmission coefficient IC sensors 50 mV / °C ± 5%

Temperature window protection

Setting range T

WIN

0.5 °C ... 20 °C

Setting range R

WIN

(20 kΩ / 200 kΩ range) 50 Ω ... 2 kΩ / 500 Ω ... 20 kΩ

Computer Interface

Setting resolution 16 Bit

Measurement resolution 12 ... 18 Bit 2)

Due to the nonlinear conversion from Ω to °C the stability in °C depends on the operating conditions

and the characteristics of the thermistor. E.g. for a typical thermistor at a set point of 10kΩ (25°C), a

0.5Ω stability translates into about 1mK temperature stability. At a set point of 5kΩ (38°C), the stability

is about 2mK.

in High Resolution mode, at reduced measurement speed

1.6 Operating elements at the front panel

ITC500 / page 14

1.6 Operating elements at the front panel

Figure 1 Operating elements at the front panel

Display

Sensor

Selection

Mains control

switch ON /Standby

PID settings

Display

Selection

Main Dial

TEC

TEC ON / OFF

Modulation Input

nalog Output

Setup

Main Dial

LDC

Laser ON / OFF

Display

Selection

Remote Control

I I

1.7 Operating elements at the rear panel

ITC500 / page 15

1.7 Operating elements at the rear panel

Interface jack Temperature Tune input Analog temp. control output Mains voltage selector

Mains jack with fuse Laser diode output TEC output DIP switch for interface configuration CP gain DIP switch for „wake up“ preset

Figure 2 Operating elements at the rear panel

The rear panel of the combi controller ITC5xx contains the mains connector with

fuse, the output jacks (9/15pin D-SUB), the analog temperature control output, the

preset DIP switch bank and the PD gain control potentiometer.

If the ITC5xx is equipped with the IEEE488.2 there is an additional DIP switch bank

to set the IEEE 488 device address. You will also find the 24pin IEEE488 jack.

TEMP OUTAUX

TUNE IN

1.8 Pre-settings

ITC500 / page 16

1.8 Pre-settings

To protect the laser diode the maximum possible current at the output of the ITC5xx

can be limited.

To protect the TEC element and the other components of the setup the maximum

allowed TEC current, the maximum temperature as well as an operating temperature

window may be selected.

1.8.1 Setting the limit of the laser current I

LD LIM

This hardware limit is set via the 25-turn potentiometer marked ADJ that is located

next to the LED I

LD LIM

at the front of the ITC5xx. The hardware limit is displayed

continuously on the display if the display I

LD LIM

is selected.

1.8.2 Setting the limit value of the TEC current

• Check the maximum allowed TEC current in the datasheet of your TEC element.

• Select the display I

TEC LIM

• Change the limit value of the TEC current to the desired value with the

screwdriver-potentiometer besides the LED I

TEC LIM

1.8.3 Setting the temperature window

• Check the type of temperature sensor in your setup.

• Select this sensor in the field marked “SENSOR“.

• Decide upon the range of the temperature window (or equivalent resistance

window of your thermistor).

• Select the display T

WIN

• Change the size of the window to the desired value with the screwdriver-

potentiometer next to the LED T

WIN

. The display shows a “plus-minus“ – value, so

if you select i.e. 5.000°, the window will reach from 5° below the set value to 5°

above the set value.

• Activate this function with DIP switch 5

 (Refer to chapter 1.8.4, “DIP switch for “wake up“ preset“ starting on page 17)

1.8 Pre-settings

ITC500 / page 17

1.8.4 DIP switch for “wake up“ preset

By means of these 8 switches you can define several preset functions to determine

the wake up mode of the ITC5xx when switched on.

SW1 selects the default (wakeup) mode of operation:

SW1 function

up const I

down const P

You can select between constant current (I) or constant power (P) mode.

SW2 selects the default (wakeup) laser diode polarity:

SW2 function

up CG

down AG

SW3 selects the default (wakeup) photo diode polarity:

SW3 function

up CG

down AG

1.8 Pre-settings

ITC500 / page 18

SW4 defines if the bias voltage is automatically switched on:

SW4 function

up bias off

down bias on

 Attention 

Before activating this function make sure, that the monitor diode

polarity is set correctly when switching on

(SW4 must be set correctly).

If the monitor diode is forward biased with a voltage the resulting

current may damage or even destroy the monitor diode (= the laser

module).

SW5 defines whether the laser diode temperature window protection is on or off, indicated by the LED WIN in the field SETUP:

SW5 function

up WIN off

down WIN on

SW6 defines which potentiometer for the TEC current is active:

SW6 function

up VAR

1.8 Pre-settings

ITC500 / page 19

down FIX

SW7 and SW8 select the default (wakeup) sensor type:

SW7 SW8 function

up up AD 590

up down AD 590

down up TH <20kΩ down down TH <200kΩ

1.9 Connecting components

ITC500 / page 20

1.9 Connecting components

1.9.1 Pin assignment for the laser diode output

Figure 3 Pinning of the laser diode connector

Pin Connector

Interlock, status display 1 output for interlock and status LASER ON/OFF 5 digital ground for pin 1

Laser diode 7 laser diode cathode (with polarity AG) 8 laser diode anode (with polarity CG) 3 ground for laser diode

Monitor diode 2 ground potential for monitor diode 4 monitor diode input

Measurement input for laser diode voltage 9 laser diode anode 6 laser diode cathode

1.9 Connecting components

ITC500 / page 21

We recommend to use separate wires drilled in pairs (twisted pair) in a common

shield for laser diode current, monitor diode current and laser voltage measurement

respectively. The shield has to be grounded.

1.9 Connecting components

ITC500 / page 22

1.9.2 Pin assignment of the TEC output jack

Figure 4 Pinning of the TEC connector

Pin Connector

TEC element 5,6,7 TEC element (+) 13,14,15 TEC element (-), ground 2 Voltage detector TEC element (+) 9 Voltage detector TEC element (-)

Status indicator 1 Status-LED (+) 8 Status-LED (-), ground

Temperature sensor 3 Thermistor (-), ground 4 Thermistor (+) 10 AD590/592 (-) 11 AD590/592 (+)

12 Supply voltage for Thorlabs-mounts

1.9 Connecting components

ITC500 / page 23

The TEC element and the temperature sensor are to be connected according to the

shown pin assignment with shielded cables to the output jack at the rear of the

ITC5xx.

The shielding of the cable has to be put on ground potential (pin 13,14,15).

1.9.3 Connecting a thermistor

The thermistor is set up between pin 3 and pin 4. The polarity is unimportant if the

thermistor is floating. If one pin of the thermistor is grounded (for example in a laser

module), this pin has to be connected to pin 3.

Using a thermistor, all temperatures are shown in ohms, therefore you have to look

for the corresponding temperature in the datasheet of the thermistor.

Figure 5 Connecting a thermistor

When the actual temperature "T

ACT" is chosen for display the thermistor resistance is

shown. The DIP switches (SW7, SW8, Figure 2) select the resistance range of the thermistor, see 1.8.4 “DIP switch for “wake up“ preset”. In position "TH < 20 kΩ” the maximum thermistor range is 20 kΩ and the measurement current 100 µA. In position "TH < 200 kΩ” the maximum thermistor resistance is 200 kΩ and the measurement current 10 µA.

The dependency of resistance on temperature and vice versa of an NTC-thermistor

is described by the formula:

1.9 Connecting components

ITC500 / page 24

val

RTeRTR

val

=⇔∗=

−

)ln(*

)()(

)

(

(temperatures in Kelvin)

with: R0: Thermistor nominal resistance at temperature T

: Nominal temperature (typ. 298.15 K = 25°C)

val

: Energy constant

For R0 and B

val

refer to the data sheet of the thermistor.

Evaluate the thermistor resistance for the desired set temperature.

Select with the display selection keys (see Figure 1) the display value "TSET" to show

the set value and set the evaluated resistance value with the TEC main dial knob.

If the thermistor characteristic R(T) is given in the data sheet the desired resistance

can be read directly.

1.9.4 Connecting a temperature sensor AD590 or AD592

An IC-temperature sensor of the AD590 family is set up between pin 10 and pin 11.

These sensors will map the temperature into an equivalent current that can be

displayed and set directly in °C.

Figure 6 Connecting an AD590 or AD592

1.9 Connecting components

ITC500 / page 25

1.9.5 Connecting a temperature sensor LM135 or LM335

The IC-temperature sensor LM335 is set up between pin 8, 10 and 11. These

sensors will map the temperature into an equivalent voltage that can be displayed

and set directly in °C.

Figure 7 Connecting a LM135 or LM335

NOTE

When connecting a LM135 or LM335 you must select AD590 as

temperature sensor !

1.9.6 Connecting a TEC element

The plus pole of the TEC must be connected to the pins 5,6,7 – the minus pole to the

pins 13,14,15 of the jack.

NOTE

Always connect all three pins of the output jack!

If the voltage of the TEC element is to be measured and displayed as well, two

additional cables must be connected directly from the two poles of the TEC element

to pin 2 and 9 of the jack. (4-point measurement).

Pin 2 and pin 9 may also be left open but this will lead to a small measurement error.

The displayed voltage will always be slightly too high.

1.9 Connecting components

ITC500 / page 26

5 6

Figure 8 Connecting a TEC

 Attention

A TEC element connected with wrong polarity may lead to thermal

runaway and destruction of the connected components.

1.9.6.1 Polarity check of the TEC element

• Connect TEC element and temperature sensor. The sensor must have good

thermal contact to the active surface of the TEC element.

• Switch on the ITC5xx.

 Now follow the steps described in chapter 1.8, “Pre-settings” on page 16

• Select the display T

SET

and select a suitable temperature (resistance).

• Select the display T

ACT.

• Switch on the output (press TEC ON) and observe the actual temperature

(resistance).

 If the temperature T

ACT

is continually running away from T

SET

the TEC element is

reverse connected. Change the polarity and repeat the procedure.

1.9 Connecting components

ITC500 / page 27

 If T

ACT

is settling up and down evenly around the value T

SET

the TEC element is

connected correctly however the values for the P-, I- and D-share of the control

loop are still incorrect.

 (Refer to chapter 2.15.4, "PID adjustment" starting on page 45)

If T

ACT

is settling properly to the value T

SET

the TEC element is connected correctly

but the values for the P-, I- and D-share of the control loop might still be improved.

1.9.7 Connecting the status indicator

To indicate the operating status a standard LED may be switched between pin 1 and

pin 8. The LED will light up if the output for the TEC current has been switched on.

Figure 9 TEC status display

Poling and value of the TEC current is insignificant here.

1.9.8 Connecting laser- and monitor diode

Connect laser and monitor diode to the connector jack of the ITC5xx.

 (Refer to chapter 1.9.1, "Pin assignment for the laser diode output" on page 20)

When measuring the voltage of the laser diode the wires for voltage measurement

(pin 6 and pin 9) have to be connected as close as possible to the laser diode to

avoid measurement errors.

The ground pin for the monitor diode (pin 2) may be connected to the ground pin of

the laser diode (pin 3). If this should be necessary (e.g. with laser diodes with

1.9 Connecting components

ITC500 / page 28

integrated monitor diode and shared ground connector) use two separate wires for

pin 2 (PD ground) and pin 3 (LD ground) and connect them only once as close as

possible to the laser diode to avoid measurement errors when measuring the monitor

diode current.

In this case the following pin assignment of the output jack will be valid:

(pins in () for voltage measurement)

Figure 10 Connecting laser- and monitor diode

(LD) = laser diode (PD) = monitor (photo-) diode

(6) 7 4 (6) 7 4 (9) 8 4 (9) 8 4

(9)

2 (PD) 3 (LD)

(9)

2 (PD) 3 (LD)

(6)

2 (PD) 3 (LD)

(6)

2 (PD) 3 (LD)

1.9 Connecting components

ITC500 / page 29

1.9.9 Connecting interlock and status LED

Interlock, cable damage monitoring

Pin 1 and pin 5 of the connector jack will serve as test connectors to determine

whether the current output for the laser diode may be switched on. Between the two pins a low resistive (<100Ω) connection must be maintained. Also short-circuiting is

permitted. With the contacts open the current module cannot be switched on. Should

the contact open during operation the output will be switched off immediately.

Status LED

It is also possible to switch a LED with a 0.5 kΩ resistor in parallel between the two

pins. The LED will light up if the current output is switched on.

Here are the two possibilities for the pin assignment:

about 0.5 kΩ <100 Ω

Figure 11 Interlock and status LED

NOTE

A 0.5 kΩ- resistor without LED (or the LED is incorrectly poled) may lead

to malfunction as the status of the interlock is then undetermined.

1.9 Connecting components

ITC500 / page 30

1.9.10 Temperature tune input

The ITC5xx is equipped with a temperature tune input, e.g. to externally lock the

laser temperature.

The input is a BNC-jack at the rear panel above the Sub-D laser diode output

connector.

Attention

Maximum input voltage of ± 10 V must not be exceeded!

The input resistance is10 kΩ and the maximum input voltage is ± 10 V. The sensitivity with an AD590: 1°C / V, with a thermistor < 20 kΩ: 0.2 kΩ / V and with a thermistor < 200 kΩ: 2 kΩ / V.

2.1 Mains voltage selector

ITC500 / page 31

2 Operating the ITC5xx

2.1 Mains voltage selector

The ITC5xx can operate with mains voltages of AC 100V, 115V or 230V. Please set

the mains voltage selector at the rear of the unit to the proper value and change the

fuse to the appropriate value before switching the ITC5xx on. Off factory the unit is

configured for the mains voltage ordered.

2.2 Mains switch

With the mains switch (key-operated power switch) the ITC5xx is switched on and off.

NOTE

Do not switch off the unit with the key-operated power switch if the laser

current is still switched on.

2.3 Main setting knobs

Through the 10-turn setting knob of the current source the set values for laser

current, monitor current or optical power are set according to operating mode and

status.

If the laser current is switched off the LED "PRESET" will light up. The set value of

the selected parameter is displayed.

If the laser current is switched on the LED "PRESET" will remain off. The actual value

of the selected parameter is displayed.

Through the 10-turn setting knob of the temperature controller the value for the

temperature is set. As a protection against unintentional temperature adjustments the

ITC5xx offers the possibility to set the temperature value via the 20-turn

potentiometer labeled ADJ. The LED "FIX" or "VAR" indicates which potentiometer is

in use. To change the potentiometer use the corresponding dip switch at the rear.

 (Refer to chapter 1.8.4, “DIP switch for “wake up“ preset“ starting on page 17)

2.4 Display

ITC500 / page 32

2.4 Display

The display consists of a 4 ½ digit display and 16 LED's

The display continuously shows the value selected in the field “DISPLAY“.

If the value to be shown is a set value (i. e. the laser current with the output switched

off) this is indicated with the LED “PRESET“ lighting up.

If the value to be shown is a measurement value (i. e. the laser current with the

output switched on) the LED “PRESET“ will not light up.

Seven LED's show the unit of the selected values (°C, kΩ, A, V, mA and mW)

Eight LED's indicate errors:

TEC OPEN lights up if the TEC element has a too high impedance or is not

connected

WIN lights up, if the actual TEC temperature leaves the window

OTP lights up if the internal temperature of the LD- or the TEC controller is

too high. Wait until the LED extinguishes. Then the ITC5xx can be

operated again.

NO SENSOR lights up if no or a wrong temperature sensor is connected

LIMIT lights up if the laser current limit value is reached

LD OPEN lights up if the wiring to the laser is interrupted while the laser is

switched on or if the compliance voltage is too low (i. e. driving two

lasers in series requiring more than the capable compliance voltage of

the ITC5xx)

INTERLOCK lights up if the interlock loop is open.

2.5 Select the value to be displayed

ITC500 / page 33

2.5 Select the value to be displayed

Twelve different values can be displayed. The value is selected with the buttons “⇓“ and “⇐ ⇒“ in the field “DISPLAY“:

Left Display:

• TEC current limit I

TEC LIM

• TEC set temperature T

SET

• TEC current I

TEC

• Temperature window T

WIN

• Actual temperature T

ACT

• TEC voltage U

TEC

Right Display:

• Laser diode current limit I

LD LIM

• Laser diode current I

• Laser diode voltage U

• Internal monitor diode current I

• Optical power measured with the monitor diode P

• Monitor diode bias voltage BIAS

2.6 Operating Mode of the laser diode (MODE)

ITC500 / page 34

2.6 Operating Mode of the laser diode (MODE)

Two modes of operation can be selected

• Constant current

• Constant power mode using a (laser-internal) monitor diode

A corresponding LED indicates the selected mode.

Constant current mode

In constant current mode the laser diode current is kept constant. Thermal changes

in the active zone of the laser will lead to a change of the output power and the

central wavelength.

 Attention 

If in constant current mode the laser is cooled down during

operation, the efficiency of the laser will increase. With some types

of lasers this may cause the optical output power to exceed the

allowed range and lead to a permanent damage of the laser.

2.6 Operating Mode of the laser diode (MODE)

ITC500 / page 35

Constant power mode

In constant power mode the current in the monitor diode (= the optical output power)

is kept constant. Thermal changes of the active zone of the laser do not entail a

change of the output power, however, a change of the central wavelength.

 Attention 

Should in constant power mode some lasers fail in a laser bar or

laser stack, a laser current runaway may happen without being

recognized, leading to more and more destruction in the laser pile.

Therefore, we urgently recommend to set the limit value for the laser

current carefully.

NOTE

For "constant power" mode a monitor diode is required.

2.7 Polarity of the laser diode (LD POL)

ITC500 / page 36

2.7 Polarity of the laser diode (LD POL)

The laser diode can either be operated with anode or cathode connected to ground.

If you have chosen the right pins of the output jack, you also have to select the right

polarity with the button LD POL in the field SETUP at the front panel.

AG means laser diode anode is connected to ground. CG means laser diode cathode is connected to ground.

The corresponding LED indicates the selection.

2.8 Polarity of the monitor diode (PD POL)

The monitor diode can either be operated with anode or cathode connected to

ground. If you have chosen the right pins of the output jack, you also have to select

the right polarity with the button PD POL in the field SETUP at the front panel.

If the polarity has been chosen correctly the display of the photo current is positive.

If the chosen polarity is wrong the display of the photo current is negative when

driving the laser diode above the threshold current. In this case you must never

switch on the bias voltage.

2.9 Bias voltage of the monitor diode (BIAS)

If required the monitor diode may be driven with a bias voltage of 0 ... 10 V.

By pressing the button PD POL again the bias voltage is in standby, indicated by the LED BIAS in the field SETUP at the front panel. The LED PRESET indicates that the

bias voltage is switched on and off simultaneously with the laser diode current. When

the bias voltage is present, the LED PRESET extinguishes.

2.9 Bias voltage of the monitor diode (BIAS)

ITC500 / page 37

The button PD POL repeatedly toggles between four different settings:

CG (monitor diode cathode grounded) CG + BIAS (monitor diode cathode grounded with bias voltage) AG (monitor diode anode grounded) AG + BIAS (monitor diode anode grounded with bias voltage) CG

. . .

Toggling values follows always this order. If the “wake up“ default is AG, the setting after pressing PD POL once will be AG + BIAS. If the “wake up“ default is AG + BIAS, the setting after pressing PD POL once will be CG, etc...

 Attention 

Before switching on the bias voltage make sure that the monitor

diode polarity is set correctly.

If the monitor diode is forward biased with a voltage the resulting

current can damage or even destroy the monitor diode (= the laser

module).

2.10 Adjusting the bias voltage of the monitor diode

ITC500 / page 38

2.10 Adjusting the bias voltage of the monitor diode

The bias voltage of the internal monitor diode may be adjusted in a range between 0

and 10 V. It is displayed continuously when selecting the display BIAS and can be set

with the potentiometer marked ADJ located next to the LED "BIAS".

NOTE

The right polarity of the monitor diode can be checked this way:

• Set a correct limit value of the laser current (I

LD LIM

)

• Set an allowed laser current above the threshold current and switch the

laser on

• Select the display of the monitor current IPD and check the polarity of

the display. If you see a negative sign (-) the polarity is wrong. If you

measure a positive value, the polarity is right and the bias voltage may

be adjusted to the desired value.

2.11 Adjusting the power display of an internal monitor diode

The optical power can be displayed if PLD is selected for display.

Therefore the monitor current is transferred into a power display that can be

calibrated with the 25-turn potentiometer marked ADJ located next to the LED P

the front of the ITC5xx.

The position of the potentiometer determines the calibration factor.

NOTE

This is the description of how to calibrate the power display in local mode

using the display of the ITC5xx. When using the IEEE488 interface the

calibration of the optical power is done completely different. The CAL

potentiometer does not affect the value measured via the interface.

 (Refer to chapter 3, “Remote control by a PC“ starting on page 55)

2.11 Adjusting the power display of an internal monitor diode

ITC500 / page 39

Adjustment

During the whole procedure the laser remains switched off.

Select the operating mode PLD and the display IPD at the ITC5xx.

Take the nominal optical output power and the corresponding monitor current from

the datasheet of the laser diode.

Set the preset value for the monitor current to this value.

Switch to the display P

so that the power belonging to the set monitor diode is

shown. Use the potentiometer ADJ next to the LED PLD to adjust this display to the

corresponding value of the output power.

2.12 Temperature window protection

ITC500 / page 40

2.12 Temperature window protection

The ITC5xx offers the possibility to control the TEC temperature within a user defined

range.

 (Refer to chapter 1.8.3, “Setting the temperature window“ on page 16)

There are two LED’s related to the temperature protection:

The LED "WIN" in the field SETUP lights if the window protection is activated.

 (Refer to chapter 1.8.4, “DIP switch for “wake up“ preset“ starting on page 17)

The control LED in the display lights if the TEC temperature moves out off the

specified window, regardless if the window protection is active or not.

If the temperature window protection is switched on the laser diode will be switched

off if the temperature leaves the window.

2.13 Selecting the temperature sensor

Three different types of sensors can be selected by toggling with the “⇓“ button :

• AD590 family

• Thermistor (two ranges)

A LED indicates the selected sensor.

2.14 Polarity check of the TEC element

ITC500 / page 41

2.14 Polarity check of the TEC element

Pre-settings

• Connect TEC element and temperature sensor. The sensor must be in good

thermal contact to the active surface of the TEC element.

• Switch on the ITC5xx.

 Now follow the steps described in chapter 1.8, “Pre-settings“ starting on page 16.

• Select the display T

SET

and select a suitable temperature (resistance).

• Select the display T

ACT.

• Switch on the output (press TEC ON) and observe the actual temperature

(resistance).

 If the temperature T

ACT

is continually running away from T

SET

, The TEC element is

reversed poled. Change polarity and repeat the procedure.

 If T

ACT

is oscillating around the value T

SET

, the TEC element has been connected

correctly, however, the values for the P-, I- and D-share of the control loop are still

incorrect.

 (Refer to chapter 2.15.4, "PID adjustment" starting on page 45)

 If T

ACT

is settling properly to the value T

SET

, the TEC element has been connected

correctly, the values for the P-, I- and D-share of the control loop might still be

improved.

 (Refer to chapter 2.15.4, "PID adjustment" starting on page 45)

2.15 Setup and function of temperature controllers

ITC500 / page 42

2.15 Setup and function of temperature controllers

A temperature difference between two points in a room (thermal slope) results in a

thermal flow trying to compensate the temperature differences.

When devices are tempered the following components will normally be involved:

• The component to be tempered (i.e. a laser diode)

• A sensor measuring the temperature of the laser

• A heat source or sink (air or water / cooling element)

• A heat conductor connecting the component to the source/sink (copper, alu)

• A "propulsion" to lead the flow of temperature (TEC element)

laser

sensor

copper bloc

TEC element

heat sink

Figure 12 Typical thermal set-up of a diode laser

2.15.1 Statements and implications

• The temperature of the laser can be measured with the sensor.

• In the copper bloc is a heat flow between laser and TEC element.

• In the TEC element is a heat flow between copper bloc and heat sink.

• In the heat sink is a heat flow between TEC element and environment.

• The difference in temperature in the TEC element can be controlled via the TEC

current. This will directly influence the heat flow in the copper bloc and in the heat

sink.

2.15 Setup and function of temperature controllers

ITC500 / page 43

 So the temperature of the laser can be influenced with the TEC current. The

quantity of heat flowing from the laser into the copper bloc and the size of the

block effects the thermal settling time of the setup.

Usually very small components (laser diodes) are tempered with relatively extensive

cooling elements (TEC elements). Thus the thermal energy is lead away quickly and

the components are as far as possible kept at a constant temperature.

2.15.2 Demands to the ideal temperature control loop

1. Knowledge of the absolute laser temperature

2. Stability of the laser temperature under any influence

3. Immediate settling to a new laser temperature when changing the set value of the

temperature

2.15.3 Influences on the real temperature control loop

To 1: Offset and gain errors of the sensor will only allow a relative knowledge about

the laser temperature.

The sensor will never be fixed to the laser chip in such a way that it will

exclusively measure its temperature. So the temperature in the copper bloc

being inhomogeneous due to the heat flow will be measured as well. Even

within the laser chip the temperature will not be the same in all spots.

Possibility of optimization: calibration of sensor

To 2. If the internal power dissipation changes (e.g. the laser current is changed)

also the temperature gradient between laser and sensor will change. This

results in a measurement error depending on the mechanical setup

laser/sensor. Changes in the ambient temperature, however, will be

compensated well from the control loop since they will almost only have an

effect on the heat slope between TEC element and cooling element.

Possibility of optimization: best possible thermal design

2.15 Setup and function of temperature controllers

ITC500 / page 44

To 3. The transient response by setting a new temperature is limited since the heat

transport in the copper bloc is relatively slow. Furthermore, the temperature

slope in the copper must form anew. The sensor (which also possesses a

significant heat capacity) must settle to the laser temperature.

Possibility of optimization: PID adjustment

2.15 Setup and function of temperature controllers

ITC500 / page 45

2.15.4 PID adjustment

Temperature control loops are comparatively slow control loops with control

oscillations in the Hertz range.

The PID adjustment will optimize the dynamic behavior. With the ITC5xx the three

parameters P, I and D may be selected independently.

2.15.4.1 Example of a PID adjustment

(Preconditions: All limit values have been set correctly, all polarities are correct, a

suitable sensor is connected and selected.

1. Set the P- I- and D-share to 0 (7 o'clock)

2. Switch on the output (button TEC ON) and observe the actual temperature.

(In some cases it is useful to connect a storage oscilloscope to the TEMP OUT

output)

2.15.4.2 P-share

3. Change the set temperature repeatedly between values of ambient

temperature +2°C and ambient temperature -2°C and observe the settling

behavior of the actual temperature.

Increase the P-share gradually by turning the corresponding potentiometer

clockwise.

Higher values will increase the settling speed, at the same time the stability

reserve will be decreased so that number and amplitude of the overshoots will

increase.

The P-share has been set correctly when the actual temperature remains

stable near the set temperature after only 2-3 overshoots.

2.15 Setup and function of temperature controllers

ITC500 / page 46

2.15.4.3 D-share

4. Change the set temperature repeatedly between values of ambient

temperature +2°C and ambient temperature -2°C and observe the settling

behavior of the actual temperature.

Increase the D-share gradually by turning the corresponding potentiometer

clockwise.

Higher values will decrease the amplitude of the overshoots.

The D-share has been set correctly when the actual temperature remains

stable near the set temperature after a minimum of overshoots.

2.15.4.4 I-share

5. Change the set temperature repeatedly between values of ambient

temperature +2°C and ambient temperature -2°C and observe the settling

behavior of the actual temperature.

Increase the I-share gradually by turning the corresponding potentiometer

clockwise.

Higher values will accelerate the settling to the set temperature.

The I-share has been set correctly when the actual temperature settles in

shortest time to the set temperature.

2.15 Setup and function of temperature controllers

ITC500 / page 47

2.15.4.5 I-Share disconnection

For some cases, particularly for slow thermal loads, this procedure will not work

satisfactory.

Please follow the steps listed below to obtain a better adjustment.

 Attention 

This procedure should only be done by qualified service personnel!

Hazardous voltages exist within the device. As shipped from the

factory, all parts carrying line voltage are covered to reduce the

likelihood of contact. Use only isolated tools and be careful not to

touch any Mains..

• Pull the line plug

• Remove the cover of the ITC5xx

• Set jumper JP8 on the mainboard

• Adjust the P- and D-share as usual

• Remove the jumper JP8 again

• Adjust the I-share at last

• Reinstall the cover

2.16 Analog modulation input

ITC500 / page 48

2.16 Analog modulation input

The laser diode controller ITC5xx has an input to modulate the laser diode current in

constant current mode.

As the internal set value for the laser diode current is modulated all laser protections

remain active (!).

The modulation input is designed for input voltages between -10V ... 10V and

specified for small signal operation. In large signal operation the 3 dB bandwidth is

reduced. (See datasheet for version dependent bandwidth)

Commonly you will select a DC current with the main dial knob and modulate this

current with the modulation input. Please note that this DC current and the

modulation current are added, so you will use a modulation voltage without a DC

share!

The modulation coefficient is version dependent.

 (See chapter 1.5, “Technical Data“ starting on page 7)

As modulation source you can use any commercially available function generator or

any signal source with output voltage in the specific range.

NOTE

Over-modulation is defined as producing a set value for the laser diode

current of below 0 mA, above the limit value or above the maximum

current your ITC5xx can deliver.

To guarantee a proper operation of the ITC5xx please avoid over-

modulation because it can lead to overshoots in the laser current.

If you are uncertain please try with a high current rectifier instead of the

laser diode and watch the analog output. You should never see

overshoots!

2.17 Analog output (ILD)

ITC500 / page 49

2.17 Analog output (ILD)

At the analog output (BNC jack) a voltage directly proportional to the laser current is

available.

Due to the wide bandwidth the output is an exact replica of the laser current.

Possible deviations of the control output from control input are due to limited

bandwidth and rise time of the laser output.

The transmission coefficient of this output depends on the type of ITC5xx.

10 V correspond to the maximum output current, so e.g. for a 1 A ITC510 10 V

correspond to 1 A and the transmission coefficient is 10V / 1A = 10 V/A.

(Respectively for LD polarity AG: 0 ... -10 V)

2.18 Laser and TEC current ON/OFF

ITC500 / page 50

2.18 Laser and TEC current ON/OFF

The laser current and/or the TEC current can be switched on by pressing the button

ON in the corresponding ADJUST field. When the ITC5xx is switched on with the

mains switch, the currents are always OFF to prevent the laser to be activated

unintentionally.

The laser current cannot be switched on if:

• the interlock loop is not closed

• the ITC5xx is overheated (display OTP)

• no laser has been connected or the wiring to the laser is interrupted (display LD

OPEN when trying to switch on)

• the temperature window protection is activated and the temperature is outside the

window

 (Please refer to chapter 2.12, “Temperature window protection“ on page 40)

The TEC current cannot be switched on if:

• no or a wrong temperature sensor is connected

• the ITC5xx is overheated (display OTP)

 Attention 

Before switching on the laser or TEC current first set the appropriate

current limit I

LD LIM

and I

TEC LIM

for the connected devices with a

screwdriver.

2.19 CP gain

ITC500 / page 51

2.19 CP gain

With this potentiometer the speed of the regulation loop in constant power mode can

be adapted to the setup.

This potentiometer will usually be in a 7 o'clock position for standard speed.

If the speed is too high and overshoots occur, please turn the potentiometer

clockwise to achieve a slower settling time.

If you want to have a faster settling time, please turn the potentiometer

counterclockwise.

Nevertheless the settling time also depends on the set power.

2.20 BNC connector TEMP OUT

An analog output TEMP OUT is provided at the rear of the ITC5xx. Here a voltage

proportional to the actual temperature "TACT" is applied for monitoring purposes, e.g.

to supervise the settling behavior of the temperature control loop.

voltage range sensor

0 ... 10 V 0 ... 20 kΩ thermistor 0 ... 10 V 0 ... 200 kΩ thermistor

-2.5 V ... +7.5 V -45 °C ... +145 °C AD590, LM335

External devices to supervise the operation may be connected to this output, e.g. to

see if certain temperature limits of the device under test are exceeded.

The output TEMP OUT operates against ground. Thus an oscilloscope or a strip

chart recorder can be connected directly. Devices connected to these outputs should have an internal resistance of ≥ 10 kΩ.

2.21 BNC connector Temp tune

ITC500 / page 52

2.21 BNC connector Temp tune

This BNC connector is the temperature tuning input.

This input allows tuning of the temperature with an external voltage of max. ±10 V

e.g. to lock the temperature to an external process.

Attention

Maximum input voltage of ± 10 V must not be exceeded!

2.22 Using the interlock input

The interlock consists of two pins that have to be connected (closed) in operation.

These are pin 1 and pin 5 of the 9pin D-SUB jack respectively pin 6 and pin 15 of the

15pin HD jack at the rear of the unit.

If the connection is open (Interlock loop open) the laser cannot be switched on.

Furthermore, if the interlock is open a red LED "INTERLOCK" on the front panel of

the ITC5xx will light.

If the interlock open's with the laser on there will be an acoustic signal and the laser

is switched off immediately.

It is possible to connect several switches in series to the pins of the interlock setting

up a closed loop that can be opened by each switch. Thus different protection

functions can be realized simultaneously via the interlock.

2.22 Using the interlock input

ITC500 / page 53

2.22.1 Examples of various protection functions

2.22.1.1 External Emergency key in the lab

An external emergency key (opener) is connected to the two pins of the interlock.

If there are other safety switch functions connect all switches in series.

2.22.1.2 Temperature control

Sometimes you may want to monitor the cooling loop of a high-power diode laser,

e.g. the temperature of the cooling water. A suitable setup offers a switch that will

open in case of an error.

If only a certain temperature range is to be monitored, a suitable (fast) thermo switch

can be used.

This switch (opener) is connected between the two pins of the interlock.

 (Please see also chapter 2.12, “Temperature window protection“ on page 40)

2.22.1.3 Safety-door monitoring

If the laser is to be operated in a closed setup (lab) a switch should be installed in a

suitable position, interrupting when the setup (lab-door) is opened.

This switch (opener) is connected to the two pins of the interlock.

2.23 Laser voltage measurement

ITC500 / page 54

2.22.1.4 Cable damage monitoring

If the interlock line is installed in parallel to the line for the laser current, a cable

damage monitoring may be realized as well.

An interruption of this line will open the interlock.

2.22.1.5 Laser ON/OFF-Display

The interlock can also be closed by switching a LED with the anode to pin 1 and the cathode to pin 5 of the 9pin D-SUB jack in parallel with a 500 Ω resistor. The current

is about 7 mA, this will make any commercially available LED light up.

This LED (only one LED is allowed) may be looped in at any point into the interlock

line and may thus serve as an independent ON/OFF display.

2.23 Laser voltage measurement

The ITC5xx constantly measures the laser voltage at the output jacks of the unit. For

a precise measurement connect pin 6 directly to the LD-cathode and pin 9 directly to

the LD-anode (respectively pin 11 and pin 14) to avoid measuring the voltage drop of

the wiring (4 pole measurement).

We recommend to use “twisted pair“ wiring for the monitor diode current, bias voltage

and laser voltage measurement respectively in a common shield. The shield has to

be connected to ground (pin 3).

 (Refer to chapter 1.9.1, “Pin assignment for the laser diode output“ on page 20)

2.23 Laser voltage measurement

ITC500 / page 55

3 Remote control by a PC (ITC5xx-IEEE)

NOTE

The following operating elements are still working with the remote control

active:

• The display

• The display selection

• all potentiometers except the main dial knob

NOTE

All analog values are read and written in SI units, i.e. A (not mA), W (not

mW) etc. Letters may be small or capital letters.

 Attention 

Before programming an ITC5xx first set the limit value of the laser

diode current I

LD LIM

(hardware limit) for the applied laser diode with a

screwdriver.

The corresponding potentiometer is marked ADJ and located next to

the LED I

LD LIM

situated at the front of the ITC5xx.

The value I

LD LIM

is constantly measured and can be checked if the

LED I

LD LIM

selects the display of the limit current.

3.1 IEEE488 Interface

ITC500 / page 56

3.1 IEEE488 Interface

The IEEE488 interface of the ITC5xx-IEEE is based on the IEEE488.2 standard. This

includes the IEEE488.1 standard for the hardware settings. There is a standard 24-

pin IEEE488 jack at the rear of the unit. The address of the ITC5xx must differ from

that of other devices on the IEEE488 bus.

 (Please refer to chapter 3.1.2, “Setting up the Interface“, starting on page 57)

3.1.1 Interface specifications

Function Part set

Source Handshake SH1

Acceptor Handshake AH1

Talker T6

Listener L4

Service Request SR1

Remote/Local RL1

Parallel Poll PP0

Device Clear DC1

Device Trigger DT0

Electrical Interface E1

3.1 IEEE488 Interface

ITC500 / page 57

3.1.2 Setting up the Interface

Address

The device address of the ITC5xx can be changed by using the IEEE488 DIP switch

at the rear panel of the ITC5xx. SW1 to SW5 have to be set according to this table:

Address SW5 SW4 SW3 SW2 SW1

Off Off Off Off Off

Off Off Off Off On

Off Off Off On Off

Off Off Off On On

Off Off On Off Off

Off Off On Off On

Off Off On On Off

Off Off On On On

Off On Off Off Off

Off On Off Off On

Off On Off On Off

Off On Off On On

Off On On Off Off

Off On On Off On

Off On On On Off

Off On On On On

Continued next page

3.1 IEEE488 Interface

ITC500 / page 58

Address SW5 SW4 SW3 SW2 SW1

On Off Off Off Off

On Off Off Off On

On Off Off On Off

On Off Off On On

On Off On Off Off

On Off On Off On

On Off On On Off

On Off On On On

On On Off Off Off

On On Off Off On

On On Off On Off

On On Off On On

On On On Off Off

On On On Off On

On On On On

On or Off

NOTE

The device address is valid after

switching off and on again.

String Terminator

The string terminator of the ITC5xx is preset to <LF><EOI>. This is fixed and cannot

be changed.

The ITC5xx will accept any combination of <LF> and <EOI> as string terminator.

3.1 IEEE488 Interface

ITC500 / page 59

3.1.3 Connecting the Instrument

• Connect the ITC5xx and the PC to the line

• Connect the units with shielded IEEE488 cables

• Switch on all units on the bus and the control computer

To guarantee a safe transmission of data the IEEE488 cable between two units

should not be longer than 2 meters and the total cable length should not be more

than 20 meters.

The ITC5xx will automatically enter REMOTE mode after the first character is

transferred to the ITC5xx.

NOTE

Programming the control software will vary with the type of computer, the

user interface, the programming language, the interface card used as well

as with the driver software and the correspondingly supplied software

interfaces. Please refer to the documentation of these components.

 (Also refer to chapter 3.9, "Hints for setting up control programs" on page 97)

3.1 IEEE488 Interface

ITC500 / page 60

3.1.4 IEEE488 bus commands

To communicate via the IEEE488 bus the standard control signals [MLA], [MTA],

[UNL], [UNT], [ATN], [REN], [SPE], [SPD] are used.

If the control program for the ITC5xx is written in a higher programming language as

e.g. BASIC, then these IEEE488 control signals are automatically transmitted to the

ITC5xx according to the used driver software and do not have to be explicitly

produced in the control program.

Also in the LabVIEW®- or LabWindows/CVI

-drivers from Thorlabs these functions

are implemented.

When receiving the IEEE488 bus commands [GET], [LLO], [GTL],

[DCL] and [SDC

] the ITC5xx will execute the following functions:

[LLO] Local Lockout

The command [LLO] will disable the button . Return to LOCAL mode (manual

operation) will only be possible with the command [GTL] (see below).

[GTL] Go To Local

The command [GTL] will bring the ITC5xx into LOCAL mode (manual operation). The

previously set values for laser current, laser power etc. will no more be valid. The set

values are determined by the main dial knob.

3.1 IEEE488 Interface

ITC500 / page 61

[DCL] Device Clear

The command [DCL] will clear the input buffer and output queue. It will also reset the

parser unit and the execution unit

NOTE

The command [DCL] will set back all units connected to the IEEE488 bus.

[SDC] Selected Device Clear

The command [SDC] will clear the input buffer and output queue. It will also reset the

parser unit and the execution unit

NOTE

In contrast to the command [DCL] the command [SDC] will only set back

the device addressed.

3.2 Before Programming

ITC500 / page 62

3.2 Before Programming

3.2.1 Nomenclature

Program messages (PC ⇒ ITC5xx) are written in inverted commas: "*IDN?" Response messages (ITC5xx ⇒ PC) are written in brackets: [MODE CC] There is a decimal point: 1.234 Parameters are separated with comma: "PLOT 2,0"

3.2.2 Program and response messages

Blocks of message data are transferred between the controller and the ITC5xx during

communication. Messages sent from the controller to the ITC5xx are called program

messages, and messages sent back from the ITC5xx to the controller are called

response messages. If a program message contains a query command, i.e. a

command which requests a response, the ITC5xx returns a response message.

Program messages

With program messages, settings are effected (command) at the ITC5xx and

response messages are selected (query). Program messages can be separated with

semicolon. All program messages are executed sequentially (one by one).

Examples:

":MODE CC" select the mode “constant current“

(command)

"*IDN?" request the identification (query) ":LDPOL CG;:PDPOL AG" select the laser diode polarity and the

photodiode polarity.

Response messages

With response messages, measurement values and status information is transferred

to the PC. All response messages are generated when the query (program message)

is parsed.

Example:

[:ILD:ACT 7.123456E-05] measure the actual laser current

3.2 Before Programming

ITC500 / page 63

3.2.3 Data format

According to the IEEE488.2 specifications all data variables are divided into 4

different data formats:

Character response data (<CRD>)

Is a single character or a string. Examples:

A or ABGRS or A125TG or A1.23456A

 (Refer to IEEE488.2-1992 standard, chapter 8.7.1)

Numeric response data Type 1 (<NR1>)

Is a numerical value with sign in integer notation. Examples:

1 or +1 or -22 or 14356789432

 (Refer to IEEE488.2-1992 standard, chapter 8.7.2)

Numeric response data Type 2 (<NR2>)

Is a numerical value with or without sign in floating point notation without exponent.

Examples:

1.1or +1.1 or -22.1 or 14356.789432

 (Refer to IEEE488.2-1992 standard, chapter 8.7.3)

3.2 Before Programming

ITC500 / page 64

Numeric response data Type 3 (<NR3>)

Is a numerical value with or without sign in floating point notation with exponent with

sign. Examples:

1.1E+1 or +1.1E-1 or -22.1E+1 or 143.56789432E+306

 (Refer to IEEE488.2-1992 standard, chapter 8.7.4)

3.3 Common commands and queries

ITC500 / page 65

3.3 Common commands and queries

The common commands are independent of the instrument’s functions, and are

specified in the IEEE488.2 standard.

3.3.1 Identification query

Syntax: "*IDN?" Response: [PROFILE, ITC510, 0, 2.17]

Description: A reply consists of the following sequence:

3.3.2 Reset

Syntax: "*RST"

Description: All outputs are switched off. All values are set to default.

3.3.3 Self-test query

Syntax: "*TST?" Response: [0]

Description: 0: Self-test finished.

3.3.4 Set Operation-complete bit

Syntax: "*OPC"

Description: The ITC5xx will set the OPC-bit in the Standard-Event-Status-

3.3 Common commands and queries

ITC500 / page 66

3.3.5 Operation-complete query

Syntax: "*OPC?" Response: [1]

Description: 1: Operation completed.

3.3.6 Wait

Syntax: "*WAI"

Description: The ITC5xx will wait until the last operation is completed.

3.3.7 Event-Status-Enable-Register (ESE)

Programming:

Syntax: "*ESE <NR1>" Valid Range: 0..255

Default Value: 0

Description: Sets the Event-Status-Enable-Register (ESE).

Reading:

Syntax: "*ESE?" Response: [<NR1>]

Description: Queries the Event-Status-Enable-Register (ESE) and returns the

content in decimal notation. The content is not modified.

3.3.8 Query Standard-Event-Status-Register (ESR)

Syntax: "*ESR?" Response: [<NR1>]

Description: Queries the Standard-Event-Status-Register (ESR) and returns the

content in decimal notation. The content is cleared.

3.3 Common commands and queries

ITC500 / page 67

3.3.9 Service-Request-Enable-Register (SRE)

Programming:

Syntax: "*SRE <NR1>" Valid Range: 0..255

Default Value: 0

Description: Sets the Service-Request-Enable-Register (SRE).

Reading:

Syntax: "*SRE?" Response: [<NR1>]

Description: Queries the Service-Request-Enable-Register (ESE) and returns the

content in decimal notation. The content is not modified.

3.3.10 Query Status-Byte-Register (STB)

Syntax: "*STB?" Response: [<NR1>]

Description: Queries the Status-Byte-Register (STB) and returns the content in

decimal notation. Bit 6 (MSS) is set to 0, the other bits keep

unchanged.

3.4 System command group

ITC500 / page 68

3.4 System command group

3.4.1 Answer mode

Programming:

Syntax: ":SYST:ANSW FULL" ":SYST:ANSW VALUE"

Default Value: FULL

Description: When switched to "VALUE" the ITC5xx will send only the requested

parameter without designator.

Example: When requesting the actual laser diode current with ":ILD:ACT?"

the ITC5xx will only send [5.123456E-02] instead of

[:ILD:ACT 5.123456E-02]. This is  not  according to the

IEEE488.2 standard but useful, if you want to increase speed.

Reading:

Syntax: ":SYST:ANSW?" Response: [:SYST:ANSW FULL] [:SYST:ANSW VALUE]

Description: Queries the answer mode.

3.4.2 Error-LED mode

Programming:

Syntax: ":SYST:ERRLED OFF" (default) ":SYST:ERRLED ON"

Default Value: OFF

Description: When "ON" the ITC5xx will switch on the interface ERRor LED as

long as there are errors in the error queue. When switched to "OFF"

the interface ERRor LED is dark.

Reading:

Syntax: ":SYST:ERRLED?" Response: [:SYST:ERRLED OFF] [:SYST:ERRLED ON]

Description: Queries the Error-LED mode.

3.4 System command group

ITC500 / page 69

3.4.3 Querying the error queue

Syntax: ":SYST:ERR?" Response: [0, "No Error"]

Description: Queries the error queue of the ITC5xx. The reply consists of the

following sequence: <Error No.>, "<Error text>". If the error queue is

empty: [0, "No error"]is given.

 (Please refer to chapter 3.7, “Error messages of the ITC5xx“, starting on page 84)

3.4.4 Averaging rate

Programming:

Syntax: ":SYST:OSR <NR1>"

Valid Range: 0..7

Default Value: 5

Description: Sets the ITC5xx averaging rate (see table below).

Reading:

Syntax: ":SYST:OSR?" Response: [<NR1>]

Description: Queries the averaging rate.

Sampling rate Resolution Measurement speed

0 11 Bit + sign 18 / s

1 12 Bit + sign 13 / s

2 13 Bit + sign 10 / s

3 14 Bit + sign 8 / s

4 15 Bit + sign 6 / s

5 16 Bit + sign 4 / s

6 17 Bit + sign 3 / s

7 18 Bit + sign 2 / s

3.5 Status command group

ITC500 / page 70

3.5 Status command group

 (Refer to chapter 3.8, "Status reporting" on page 90)

3.5.1 Query Device-Error-Condition-Register (DEC)

Syntax: ":STAT:DEC?" Response: [:STAT:DEC <NR1>]

Description: Queries the Device-Error-Condition-Register (DEC) and returns the

content in decimal notation. The content is not modified.

3.5.2 Query Device-Error-Event-Register (DEE)

Syntax: ":STAT:DEE?" Response: [:STAT:DEE <NR1>]

Description: Queries the Device-Error-Event-Register (DEE) and returns the

content in decimal notation. The content is cleared.

3.5.3 Device-Error-Event-Enable-Register (EDE)

Programming:

Syntax: ":STAT:EDE <NR1>" Valid Range: 0...65535

Default Value: 0

Description: Sets the Device-Error-Event-Enable-Register (EDE).

Reading:

Syntax: ":STAT:EDE?" Response: [:STAT:EDE <NR1>]

Description: Queries the Device-Error-Event-Enable-Register (EDE) and returns

the content in decimal notation. The content is not modified.

3.6 ITC5xx specific commands

ITC500 / page 71

3.6 ITC5xx specific commands

3.6.1 Operation mode (MODE)

Programming:

Syntax: ":MODE CC" ":MODE CP"

Assumption: The laser diode output is switched off.

Description: Changes the mode of operation. Sets the laser diode current, the

photo diode current and the optical power to default values.

Reading:

Syntax: ":MODE?" Response: [:MODE CC] [:MODE CP]

Description: Queries the mode of operation.

3.6.2 Laser diode polarity (LDPOL)

Programming:

Syntax: ":LDPOL CG" ":LDPOL AG"

Assumption: The laser diode output is switched off.

Description: Switches the laser diode polarity. Sets the laser diode current, the

photo diode current and the optical power to default values.

Reading:

Syntax: ":LDPOL?" Response: [:LDPOL AG] [:LDPOL CG]

Description: Queries the polarity of the laser diode.

3.6 ITC5xx specific commands

ITC500 / page 72

3.6.3 Photo diode polarity (PDPOL)

Programming:

Syntax: ":PDPOL CG" ":PDPOL AG"

Assumption: The laser diode output and the bias voltage is switched off.

Description: Selects the photo diode polarity. Sets the laser diode current, the

photo diode current and the optical power to default values.

Reading:

Syntax: ":PDPOL?" Response: [:PDPOL AG] [:PDPOL CG]

Description: Queries the polarity of the photo diode.

3.6.4 Reading the state of the temperature protection (TP)

Syntax: ":TP?" Response: [:TP OFF] [:TP ON]

Description: Queries the state of the temperature protection.

3.6 ITC5xx specific commands

ITC500 / page 73

3.6.5 Switching the bias voltage on and off (PDBIA)

Programming:

Syntax: ":PDBIA OFF" ":PDBIA ON"

Assumption: The laser diode output is switched off.

Description: Switches the photo diode bias voltage on or off.

Reading:

Syntax: ":PDBIA?" Response: [:PDBIA OFF] [:PDBIA ON]

Description: Queries the state of the photo diode bias voltage.

 Attention 

Before switching on the bias voltage make sure that the monitor

diode polarity is set correctly.

If the monitor diode is forward biased with a voltage the resulting

current may damage or even destroy the monitor diode (= the laser

module).

 (For checking the right polarity please refer to chapter 2.10, "Adjusting the bias

voltage of the monitor diode" on page 38)

3.6 ITC5xx specific commands

ITC500 / page 74

3.6.6 Turn the output on and off (LASER)

Programming:

Syntax: ":LASER OFF" ":LASER ON"

Default Value: OFF

Assumption: To switch the output on there must be no device errors (interlock

open, open circuit, over temperature, ...).

Description: Switches the laser diode output on or off.

Reading:

Syntax: ":LASER?" Response: [:LASER OFF] [:LASER ON]

Description: Queries the state of the laser diode output.

NOTE

To switch on the laser while a “open circuit“ error is present (see Device

Error Condition Register), you have to reset the “open circuit“ error with

the command: “:LASER ON“. With the next command

“:LASER ON“ the laser will switch on again.

3.6 ITC5xx specific commands

ITC500 / page 75

3.6.7 Reading the laser diode hardware limit (LIMCP)

Syntax: ":LIMCP:ACT?" Response: [:LIMCP:ACT <NR3>]

Description: Queries the laser diode limit current (adjusted via potentiometer).

 (Refer to Chapter 1.8.1, "Setting the limit of the laser current I

LD LIM

" on page 16)

3.6.8 Laser diode current (ILD)

Programming:

Syntax: ":ILD:SET <NR3>"

Valid Range: Depends on the instrument type.

Default Value: 0 A

Assumption: The operation mode is switched to constant current.

Description: Sets the laser diode current. Unit: [A].

Reading the set current:

Syntax: ":ILD:SET?" Response: [:ILD:SET <NR3>]

Description: Queries the programmed laser diode current. Unit: [A].

Reading the minimum current:

Syntax: ":ILD:MIN?" Response: [:ILD:MIN <NR3>]

Description: Queries the minimum allowed laser diode current. Unit: [A].

Reading the maximum current:

Syntax: ":ILD:MAX?" Response: [:ILD:MAX <NR3>]

Description: Queries the maximum allowed laser diode current. Unit: [A].

Reading the actual current:

Syntax: ":ILD:ACT?" Response: [:ILD:ACT <NR3>]

Description: Queries the actual laser diode current. Unit: [A].

3.6 ITC5xx specific commands

ITC500 / page 76

3.6.9 Monitor diode current (IMD)

Programming:

Syntax: ":IMD:SET <NR3>"

Valid Range: Depends on the instrument type.

Default Value: 0 A

Assumption: The operation mode is set to constant power.

Description: Sets the photo diode current. Unit: [A].

Reading the set current:

Syntax: ":IMD:SET?" Response: [:IMD:SET <NR3>]

Description: Queries the programmed photo diode current. Unit: [A].

Reading the minimum current:

Syntax: ":IMD:MIN?" Response: [:IMD:MIN <NR3>]

Description: Queries the minimum allowed photo diode current. Unit: [A].

Reading the maximum current:

Syntax: ":IMD:MAX?" Response: [:IMD:MAX <NR3>]

Description: Queries the maximum allowed photo diode current. Unit: [A].

Reading the actual current:

Syntax: ":IMD:ACT?" Response: [:IMD:ACT <NR3>]

Description: Queries the actual photo diode current. Unit: [A].

3.6 ITC5xx specific commands

ITC500 / page 77

3.6.10 Calibrating a photo diode (CALPD)

Programming:

Syntax: ":CALPD:SET <NR3>"

Valid Range: Depends on the instrument type.

Default Value: 1.0 A/W

Assumption: The laser diode output is switched off. Description: Sets the sensitivity (η) of the monitor diode. Unit: [A/W].

Reading the set sensitivity:

Syntax: ":CALPD:SET?" Response: [:CALPD:SET <NR3>]

Description: Queries the programmed sensitivity of the monitor diode. Unit: [A/W].

Reading the minimum sensitivity:

Syntax: ":CALPD:MIN?" Response: [:CALPD:MIN <NR3>]

Description: Queries the minimum allowed sensitivity of the monitor diode.

Unit: [A/W].

Reading the maximum sensitivity:

Syntax: ":CALPD:MAX?" Response: [:CALPD:MAX <NR3>]

Description: Queries the maximum allowed sensitivity of the monitor diode.

Unit: [A/W].

NOTE

This calibration is used for the command POPT. It differs from the

calibration factor set with the potentiometer located next to the LED PLD

that is responsible for the 4 ½ digit display. If the value on the display shall

be equal to that read back via the interface, a manual calibration has to be

done too.

 (Refer to chapter 2.11, “Adjusting the power display of an internal monitor diode“ on

page 38)

3.6 ITC5xx specific commands

ITC500 / page 78

3.6.11 Optical power (POPT)

Programming:

Syntax: ":POPT:SET <NR3>"

Valid Range: Depends on the instrument type and the programmed sensitivity of the

monitor diode.

Default Value: 0 W

Assumption: The operation mode is set to constant power.

Description: Sets the optical power. Unit: [W].

Reading the set power:

Syntax: ":POPT:SET?" Response: [:POPT:SET <NR3>]

Description: Queries the programmed optical power. Unit: [W].

Reading the minimum power:

Syntax: ":POPT:MIN?" Response: [:POPT:MIN <NR3>]

Description: Queries the minimum allowed optical power. Unit: [W].

Reading the maximum power:

Syntax: ":POPT:MAX?" Response: [:POPT:MAX <NR3>]

Description: Queries the maximum allowed optical power. Unit: [W].

Reading the actual power:

Syntax: ":POPT:ACT?" Response: [:POPT:ACT <NR3>]

Description: Queries the actual optical power. Unit: [W].

 (See note at command CALPD on page 77)

3.6 ITC5xx specific commands

ITC500 / page 79

3.6.12 Reading the optical power from the display (POPTP)

Syntax: ":POPTP:ACT?" Response: [:POPTP:ACT <NR3>]

Description: Queries the actual optical power, that is calculated from the position of

the potentiometer marked ADJ next to the LED PLD. This is the optical

power shown on the display. Unit: [W]

NOTE

This queries the optical power measured by the internal monitor diode that

is displayed on the 4 ½ digit display.

3.6.13 Reading the laser diode voltage (VLD)

Syntax: ":VLD:ACT?" Response: [:VLD:ACT <NR3>]

Description: Queries the actual laser diode voltage. Unit: [V]

3.6.14 Reading the bias voltage (VBIAS)

Syntax:

":VBIAS:ACT?"

Response: [:VBIAS:ACT <NR3>]

Description: Queries the actual photo diode bias voltage. Unit: [V]

NOTE

This query always tells the bias voltage set with the potentiometer ADJ

next to the LED PD BIAS even with the bias voltage switched off.

3.6 ITC5xx specific commands

ITC500 / page 80

3.6.15 Temperature Sensor (SENS)

Programming:

Syntax: ":SENS AD" (AD590 family) ":SENS THL" (thermistor, 20 kΩ range) ":SENS THH" (thermistor, 200 kΩ range)

Assumption: The TEC output is switched off.

Description: Selects the type of temperature sensor. Sets the programmed

temperature / resistance to default values.

Reading:

Syntax: ":SENS?" Response: [:SENS AD] [:SENS THL] [:SENS THH]

Description: Queries the type of the temperature sensor.

3.6.16 Switching the TEC on and off (TEC)

Programming:

Syntax: ":TEC OFF" ":TEC ON"

Default Value: OFF

Assumption: To switch the TEC on there must be no device errors (no sensor, TEC

open, over temperature, ...).

Description: Switches the TEC output on or off.

Reading:

Syntax: ":TEC?" Response: [:TEC OFF] [:TEC ON]

Description: Queries the state of the TEC output.

3.6 ITC5xx specific commands

ITC500 / page 81

3.6.17 Temperature (only AD590) (TEMP)

Programming:

Syntax: ":TEMP:SET <NR3>"

Valid Range: Depends on the instrument type.

Default Value: 25 °C

Assumption: The temperature sensor is set to AD590.

Description: Sets the TEC temperature. Unit: [°C].

Reading the set temperature:

Syntax: ":TEMP:SET?" Response: [:TEMP:SET <NR3>]

Assumption: The temperature sensor is set to AD590.

Description: Queries the programmed temperature. Unit: [°C].

Reading the minimum temperature:

Syntax: ":TEMP:MIN?" Response: [:TEMP:MIN <NR3>]

Assumption: The temperature sensor is set to AD590.

Description: Queries the minimum allowed temperature. Unit: [°C].

Reading the maximum temperature:

Syntax: ":TEMP:MAX?" Response: [:TEMP:MAX <NR3>]

Assumption: The temperature sensor is set to AD590.

Description: Queries the maximum allowed temperature. Unit: [°C].

Reading the actual temperature:

Syntax: ":TEMP:ACT?" Response: [:TEMP:ACT <NR3>]

Assumption: The temperature sensor is set to AD590.

Description: Queries the actual temperature. Unit: [°C].

3.6 ITC5xx specific commands

ITC500 / page 82

3.6.18 Resistance of the thermistor (RESI)

Programming:

Syntax: ":RESI:SET <NR3>"

Valid Range: Depends on the instrument type and the selected temperature sensor.

Default Value: Depends on the selected thermistor range.

Assumption: The temperature sensor is set to thermistor (high or low range). Description: Sets the TEC thermistor resistance. Unit: [Ω].

Reading the set resistance:

Syntax: ":RESI:SET?" Response: [:RESI:SET <NR3>]

Assumption: The temperature sensor is set to thermistor (high or low range). Description: Queries the programmed thermistor resistance. Unit: [Ω].

Reading the minimum resistance:

Syntax: ":RESI:MIN?" Response: [:RESI:MIN <NR3>]

Assumption: The temperature sensor is set to thermistor (high or low range). Description: Queries the minimum allowed thermistor resistance. Unit: [Ω].

Reading the maximum resistance:

Syntax: ":RESI:MAX?" Response: [:RESI:MAX <NR3>]

Assumption: The temperature sensor is set to thermistor (high or low range). Description: Queries the maximum allowed thermistor resistance. Unit: [Ω].

Reading the actual resistance:

Syntax: ":RESI:ACT?" Response: [:RESI:ACT <NR3>]

Assumption: The temperature sensor is set to thermistor (high or low range). Description: Queries the actual thermistor resistance. Unit: [Ω].

3.6 ITC5xx specific commands

ITC500 / page 83

3.6.19 Reading the TEC current hardware limit (LIMTP)

Syntax: ":LIMTP:ACT?" Response: [:LIMTP:ACT <NR3>]

Description: Queries the actual TEC current hardware-limit. Unit: [A]

 (Refer to Chapter 1.8.2, "Setting the limit value of the TEC current" on page 16)

3.6.20 Reading the TEC current (ITE)

Syntax: ":ITE:ACT?" Response: [:ITE:ACT <NR3>]

Description: Queries the actual TEC current. Unit: [A]

3.6.21 Reading the temperature/resistance window (WIN)

Syntax: ":WIN:ACT?" Response: [:WIN:ACT <NR3>]

Description: Queries the actual temperature/resistance window. Depending on the

temperature sensor the temperature window or the resistance window is retuned. Unit: [°C], [Ω]

3.6.22 Reading the TEC voltage (VTE)

Syntax: ":VTE:ACT?" Response: [:VTE:ACT <NR3>]

Description: Queries the actual TEC voltage. Unit: [V]

3.7 Error messages of the ITC5xx

ITC500 / page 84

3.7 Error messages of the ITC5xx

Devices following the IEEE488.2 standard provide an error queue storing errors one

by one.

An Error may occur as result of a program message (refer to chapter 3.2.2, “Program

and response messages“ on page 62).

Errors are divided into four categories (refer to chapter 3.8.1, “Standard event status

Every query ":SYST:ERR?" will read out one error from the error queue until the

error queue is empty (refer to 3.4.3, “Querying the error queue“ on page 69).

The error queue can keep 32 errors.

If the queue is empty, the error message [0, "No error“] is sent to the PC

3.7.1 General errors

[0, "No errors"]

Category: None

Possible reason: The error queue is empty.

[100, "Unknown command"]

Category: Command Error Possible reason: ":HELLO WORLD". This string sent to the ITC5xx was not

recognized as valid command.

[101, "Invalid character"]

Category: Command Error Possible reason: "!". This character sent to the ITC5xx does not belong to the

allowed set of characters.

[102, "Invalid numeric parameter"]

Category: Command Error Possible reasons: ":ILD:SET 1.2a3". This parameter is not valid.

3.7 Error messages of the ITC5xx

ITC500 / page 85

[103, "Invalid text parameter"]

Category: Command Error Possible reasons: ":SENS hhh". This parameter is not valid.

[109, "Wrong compound"]

Category: Command Error Possible reason: ":ILD:ERR?". This combination is not allowed.

[110, "Unknown compound"]

Category: Command Error Possible reason: ":ILD:XXX?". This compound is not known.

[111, "Wrong parameter"]

Category: Command Error Possible reason: ":LASER CG". This compound is not valid for this command.

[190, "Parser buffer overflow"]

Category: Command Error

Possible reason: The string sent to the ITC5xx was too long for the parser.

[200, "Data out of range"]

Category: Execution Error Possible reason: ":ILD:SET 10E+30" sent to the ITC5xx but this current is

much too high.

[300, "Hardware error"]

Category: Device Error

Possible reason: Many. Device must probably be maintained.

[301, "Software error"]

Category: Device Error

Possible reason: Unexpected error. Please contact Thorlabs.

[302, "Not implemented yet"]

Category: Device Error

Possible reason: Feature not enabled. Please contact Thorlabs.

3.7 Error messages of the ITC5xx

ITC500 / page 86

[303, "Key emulation error"]

Category: Device Error

Possible reason: Internal communication problem. Please contact Thorlabs.

[400, "Too many errors"]

Category: Device Error

Possible reason: Error queue overflow (32 errors max).

[410, "Query interrupted"]

Category: Query Error

Possible reason: More than one query sent to the ITC5xx before the read

command.

[420, "Query unterminated"]

Category: Query Error

Possible reason: There is no data in the output buffer.

[500, "IEEE488 receive buffer overflow"]

Category: Device Error

Possible reason: The string sent to the ITC5xx was too long for the IEEE488

receive buffer (250 char max).

3.7 Error messages of the ITC5xx

ITC500 / page 87

3.7.2 ITC5xx operation error messages

[1301, "Interlock is open"]

Category: Execution Error

Possible reason: Try to switch on the output while the Interlock line is open.

 (Refer to chapter 2.22, "Using the interlock input" on page 52)

[1302, "Open circuit"]

Category: Execution Error

Possible reason: Try to switch on the output while the able to the laser diode has

opened or the compliance voltage is not high enough.

[1303, "Over temperature"]

Category: Execution Error

Possible reason: Try to switch on the output while the internal temperature is too

high. Wait until the ITC5xx has cooled down. Maintain proper air

flow.

[1304, "Internal power failure"]

Category: Execution Error

Possible reason: Try to switch on the output while an internal power failure

occurred.

[1306, "No calibrating of PD during laser on"]

Category: Execution Error

Possible reason: The monitor diode cannot be calibrated during the laser diode

output is switched on.

[1307, "No setting of ILD during constant power mode"]

Category: Execution Error

Possible reason: The set value of the laser diode current can not be changed

during constant power mode.

3.7 Error messages of the ITC5xx

ITC500 / page 88

[1308, "No setting of IMD during constant current mode"]

Category: Execution Error

Possible reason: The set value of the monitor diode current and the optical power

cannot be changed during constant current mode.

[1309, "No LD polarity change during laser on"]

Category: Execution Error

Possible reason: The polarity of the laser diode can not be changed during the

laser diode output switched on.

[1310, "No PD polarity change during laser on"]

Category: Execution Error

Possible reason: The polarity of the monitor diode can not be changed during the

laser diode output switched on.

[1311, "No mode change during laser on"]

Category: Execution Error

Possible reason: The operating mode CC or CP cannot be changed during the

laser diode output is switched on.

[1312, "Wrong or no sensor"]

Category: Execution Error

Possible reason: The ITC5xx detected no sensor at the output jack.

[1313, "Wrong command for this sensor"]

Category: Execution Error

Possible reason: The released command does not fit to the connected sensor.

[1314, "No sensor change during TEC on allowed"]

Category: Execution Error

Possible reason: The type of sensor may not be changed during the output

switched on.

3.7 Error messages of the ITC5xx

ITC500 / page 89

[1315, "Attempt to switch on laser while temperature is

out of window"]

Category: Execution Error

Possible reason: The actual temperature of the laser diode is outside the

temperature window.

[1317, "Limit of temperature/resistance reached"]

Category: Execution Error

Possible reason: The set value of the temperature/resistance reached the

temperature limit.

[1318, "No bias change during laser on"]

Category: Execution Error

Possible reason: The bias voltage may not be switched on or off during laser on.

[1319, "No PD polarity change during bias on"]

Category: Execution Error

Possible reason: The polarity of the monitor diode may not be changed with the

bias voltage on.

3.8 Status reporting

ITC500 / page 90

3.8 Status reporting

The ITC5xx provides four 8 bit registers ESR, STB, ESE and SRE and three 16 bit

registers DEC, DEE and EDE to program various service request functions and

status reporting.

 (Please refer to the IEEE488.2-1992 standard chapter 11)

3.8.1 Standard event status register (ESR)

The bits of this register mirror the following standard events:

Power on This event bit indicates, that an off to on transition has

occurred in the power supply. So it is high after switching

on the device for the first time.

User request (Not used)

Command error A command error occurred.

Execution error An execution error occurred.

Device error A device dependent error occurred.

Query error A query error occurred.

Request control (Not used)

Operation complete Can be set with "*OPC".

The ESR can be read directly with the command "*ESR?". This read command

clears the ESR. The content of the ESR can not be set.

The bits are active high.

3.8 Status reporting

ITC500 / page 91

Figure 13 ITC5xx Status registers ESR, ESE, STB and SRE

Output buffer

ERROR Queue

or serial poll

Service

Request

Generation

{

3.8 Status reporting

ITC500 / page 92

Figure 14 ITC5xx Status registers DEC, DEE and EDE

(:STAT:DEC ? )

ower supply error

No or wrong sensor

Open Circuit (TEC)

Temperature out of window

Current limit

Interlock open

Open circuit (LD)

Over temperature

THORLABS ITC502, ITC510 Operation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual