THORLABS LDC340 User manual

Operation Manual
Thorlabs Blueline™ Series
Laser diode controller
LDC340 (-IEEE)
2006

Version: 2.23
Date: 20.06.2006
Copyright©2006, Thorlabs GmbH, Germany

Contents Page
1General Information 1
1.1 At a Glance 1
1.2 Safety 4
1.3 Ordering codes and Accessories 6
2Getting Started 7
2.1 Unpacking 7
2.2 Preparation 7
2.3 Operating elements 8
2.3.1 Front panel 8
2.3.2 Rear panel 9
2.4 First operation 10
3Operating the LDC340 11
3.1 Presettings 11
3.1.1 DIP switch for “wake up“ preset 11
3.1.2 Setting the limit of the laser current ILD LIM 13
3.1.3 Setting the limit of the monitor diode current IPD LIM 13
3.1.4 Adjusting the power display of an internal monitor diode 14
3.2 Connecting components 15
3.2.1 Pin assignment of the output jack 15
3.2.2 Using the interlock input 16
3.2.3 Connecting the monitor diode 17
3.2.4 Laser voltage measurement 18
3.2.5 Temperature window protection input (WIN IN) 19
3.3 Display 19
3.4 Main setting knob 20
3.5 Mode Select 20
3.6 Display select 21
3.7 Analog modulation input 21
3.8 Analog output 22
3.9 Setup of polarities and bias voltage 22
3.9.1 Polarity of the Laser diode (LD POL) 22
3.9.2 Polarity of the internal monitor diode (PD POL) 23
3.9.3 Bias voltage of the monitor diode (PD BIAS) 23
3.9.4 Adjusting the bias voltage of the monitor diode 24
3.10 Laser current ON/OFF (LD ON) 25
3.11 CP gain 26
4Communicating with a control computer (LDC340-IEEE) 27
4.1 General remarks 27

4.2 IEEE488 Interface 28
4.2.1 Interface specifications (IEEE 488 subsets) 28
4.2.2 Setting up the Interface 29
4.2.3 Connecting the Instrument 31
4.2.4 IEEE488 bus commands 32
4.3 Before Programming 34
4.3.1 Nomenclature 34
4.3.2 Program and response messages 34
4.3.3 Data format 35
4.4 Common commands and queries 36
4.4.1 Identification query 36
4.4.2 Reset 36
4.4.3 Self-test query 36
4.4.4 Set Operation-complete bit 36
4.4.5 Operation-complete query 37
4.4.6 Wait 37
4.4.7 Event-Status-Enable-Register (ESE) 37
4.4.8 Query Standard-Event-Status-Register (ESR) 37
4.4.9 Service-Request-Enable-Register (SRE) 38
4.4.10 Query Status-Byte-Register (STB) 38
4.5 System command group 39
4.5.1 Answer mode 39
4.5.2 Error-LED mode 39
4.5.3 Querying the error queue 40
4.5.4 Oversampling rate 40
4.6 Status command group 41
4.6.1 Query Device-Error-Condition-Register (DEC) 41
4.6.2 Query Device-Error-Event-Register (DEE) 41
4.6.3 Device-Error-Event-Enable-Register (EDE) 41
4.7 LDC340 specific commands 42
4.7.1 Operation mode (MODE) 42
4.7.2 Laser diode polarity (LDPOL) 42
4.7.3 Photo diode polarity (PDPOL) 43
4.7.4 Photo diode range (PDRANGE) 43
4.7.5 Switching the bias voltage on and off (PDBIA) 44
4.7.6 Switching the output on and off (LASER) 45
4.7.7 Reading the laser diode hardware limit (LIMCP) 45
4.7.8 Laser diode current (ILD) 46
4.7.9 Monitor diode current (IMD) 47

4.7.10 Calibrating a photo diode (CALPD) 48
4.7.11 Optical power (POPT) 49
4.7.12 Reading the optical power from the display (POPTP) 50
4.7.13 Reading the laser diode voltage (VLD) 50
4.7.14 Reading the bias voltage (VBIAS) 50
4.7.15 Reading the monitor diode limit current (LIMMP) 51
4.7.16 Reading the internal photo diode current (IPDI) 51
4.7.17 Reading the external photo diode current (IPDE) 51
4.8 Error messages of the LDC340-IEEE 52
4.8.1 General errors 52
4.8.2 LDC340 operation error messages 55
4.9 Status reporting 57
4.9.1 Standard event status register (ESR) 59
4.9.2 Standard event status enable register (ESE) 59
4.9.3 Status byte register (STB) 60
4.9.4 Service request enable register (SRE) 60
4.9.5 Reading the STB by detecting SRQ 61
4.9.6 Reading the STB by *STB? command 61
4.9.7 Reading the STB by serial poll 61
4.9.8 Device error condition register (DEC) 62
4.9.9 Device error event register (DEE) 63
4.9.10 Device error event enable register (EDE) 63
4.10 Hints for setting up control programs 64
5Maintenance and repair 67
5.1 Maintenance 67
5.2 Selecting the line voltage 68
5.3 Exchanging the line fuse 68
5.4 Exchange of internal fuses 70
5.5 Troubleshooting 71
6Appendix 73
6.1 Warranty 73
6.2 Certifications and compliances 74
6.3 Technical data 76
6.4 Thorlabs “End of Life” policy (WEEE) 79
6.4.1 Waste treatment on your own responsibility 79
6.4.2 Ecological background 80
6.5 List of acronyms 81
6.6 List of figures 82
6.7 Addresses 83

We aim to develop and produce the best solution for your application in the
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Thorlabs GmbH
This part of the instruction manual contains specific information on how to operate a
laser diode controller LDC340. A general description is followed by explanations of
how to operate the unit manually. You will also find the information about remote
control of the LDC340-IEEE 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 equip-
ment.
Please read these advises carefully!
NOTE
This manual also contains “NOTES” and “HINTS” written in this form.

1.1 At a Glance
LDC340 / Page 1
1 General Information
1.1 At a Glance
The LDC340 is a compact laser driver with optional IEEE488.2 interface for driving
laser diodes up to 4A laser current.
The LDC340 especially excels in:
•Very low noise
•Two current ranges
•The universal possibilities of connecting components
•The operating comfort of its compact construction
•Extensive protections for the laser diode
•The possibility to drive two lasers in series at the same time
•Two independent monitor diode inputs
•CW mode with modulation input up to 50 kHz
•Interlock for automatic switch-off by an external control signal (e.g. cooling loop
monitoring)
•LabVIEW®- and LabWindows/CVI®instrument drivers.
The laser diodes can be operated in constant current as well as in constant power
mode.
In remote operation (LDC340-IEEE only) all settings except the limits and 2
calibration values can be done from the PC.

1.1 At a Glance
LDC340 / Page 2
A wide variety of protection features protect the laser diode from damage.
These features are:
•Key-operated power switch
Prevents unauthorized switching on of the laser diode.
•Softstart
The switch on delay of the softstart function protects the laser diode against
undesired peaks.
•Limit for the injection current (hardware limit)
A manually adjustable current limit limits the maximum allowed laser current. The
limit value can be set with a 25-turn potentiometer on the front panel.
•Interlock
The interlock input enables to realize several protection 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 closed.
(Refer to chapter 3.2.2, “Using the interlock input“ starting on page 16)
•Contact protection of the laser diode (open circuit)
If the line to the laser is interrupted even for a short time during operation an
emergency switch off is immediately released.
•Electronic short-circuit switch for the laser diode
With the current module switched off an electronic switch will shortcircuit the laser
diode so that no voltage is applied to the laser contacts.
•Control LED for laser current being active
When the laser current is switched on an LED in the switch LD ON lights up.

1.1 At a Glance
LDC340 / Page 3
•Temperature-window protection of the laser diode
Operation in the specified temperature range. (Only in combination with a Thorlabs
GmbH TED 350)
•Over-temperature protection
The LDC340 has an automatic over-temperature protection in case that the allowed
internal operating temperature should be exceeded. In this case the output will switch
off and after temperature decay of about 10 °C the output current of the LDC340 can
be switched on again.
•Defined states after switch-on
When switching on the LDC340 with the mains switch the laser current output is
always switched off. The LDC340 will always wake up in a mode that can be selected
with a DIP switch at the rear.
•Mains filter
Protection against line failure or transients.
•Line failure monitoring
In case of line failure/line interruption the LDC340 will wake up anew as if it has been
switched on. So the laser output remains switched off.

1.2 Safety
LDC340 / Page 4
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 LDC340 system, make sure that the
protective conductor of the 3 conductor mains power cord is cor-
rectly connected to the protective earth contact of the socket outlet!
Improper grounding can cause electric shock with damages to your
health or even death!
Also make sure that your line voltage agrees with the voltage indi-
cated by the switch setting on the back of the unit and that the right
fuse has been inserted!
Only with written consent from Thorlabs GmbH Munich changes to
single components may be carried out or components not supplied
by Thorlabs GmbH 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.
The LDC340 must not be operated in explosion endangered environ-
ments!