THORLABS Blueline Series User manual

Operation Manual
Thorlabs Blueline™ Series
Laser Diode Controller
LDC2xx
2006

Version: 1.11
Date: 20.06.2006
Copyright© 2006, Thorlabs GmbH, Germany

Contents page
1General Information 1
1.1 At a Glance 1
1.2 Safety 3
1.3 Ordering codes and accessories 5
2Getting Started 6
2.1 Unpacking 6
2.2 Preparation 6
2.3 Operating elements 7
2.3.1 Operating elements on front panel 7
2.3.2 Operating elements on rear panel 8
2.4 First operation 9
3Operating the LDC2xx 10
3.1 Connecting components 10
3.1.1 9-pole SUB-D output jack 10
3.1.2 Interlock and control LED for LASER ON 11
3.1.3 Connecting the laser diode and photodiode 12
3.1.4 Analog control output for the laser current 14
3.2 Setting the current limit "ILIM" 15
3.3 Selecting the laser diode polarity 15
3.4 Constant current mode (CONST I) 17
3.5 Constant power mode (CONST P) 18
3.5.1 Changing the "IPD" setting range 20
3.6 Calibrating the optical power display 21
3.7 Analog modulation of the laser diode 21
3.8 Over-temperature-protection of the LDC2xx 22
4Remote control 23
5Maintenance and Repair 24
5.1 Maintenance 24
5.2 Line voltage setting 25
5.3 Replacing the mains fuse 26
5.4 Internal Fuse Replacement 27
5.5 Troubleshooting 28
6Appendix 30
6.1 Warranty 30
6.2 Certifications and compliances 31
6.3 Technical data 33

6.3.1 Common Data 33
6.3.2 Individual data LDC200V 34
6.3.3 Individual data LDC201U 35
6.3.4 Individual data LDC202B 36
6.3.5 Individual data LDC205B 37
6.3.6 Individual data LDC210B 38
6.3.7 Individual data LDC220 39
6.4 Thorlabs “End of Life” policy (WEEE) 40
6.4.1 Waste treatment on your own responsibility 40
6.4.2 Ecological background 41
6.5 List of acronyms 42
6.6 List of figures 42
6.7 Addresses 43

We aim to develop and produce the best solution for your application in the
field of optical measurement technique. To help us to live 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 GmbH
This part of the instruction manual contains all the specific information on how to
operate a current module LDC2 xx. A general description is followed by explanations
on how to operate the unit manually. You will also find information about a simple
remote control of the unit.
Attention
This manual contains “WARNINGS” and “ATTENTION” labels in this
form, to indicate personal danger or possible damage to equipment.
Please read these advises carefully!
NOTE
This manual also contains “NOTES” and “HINTS” written in this form.

1.1 At a Glance
LDC2xx / page 1
1 General Information
1.1 At a Glance
The laser diode controllers of the series LDC200 by Thorlabs GmbH are extremely
precise controllers for laser diodes and LEDs. If a temperature controller by Thorlabs
GmbH is used additionally the injection current or the optical output power and the
temperature of the connected laser diode can be controlled simultaneously.
The LDC200V is designed for safe operation of VCSEL laser diodes.
The LDC201U provides ultra low noise current (<0.2µA RMS).
The new suffix “B” controllers offer an enhanced compliance voltage (>10V) for use
with blue laser diodes.
To protect the laser diode against dam age the LDC2xx provides the following
protection circuits:
• Softstart function
• Adjustable limitation of injection current
• Interlock (open circuit monitoring of the laser diode mount connection)
• Electronic shortcircuit for the laser diode in off-mode
• Separate key to switch the laser diode current on and off
• Monitoring LED for LASER ON mode
The LDC2xx is easy to use due to the clearly structured front panel.
Operating parameters are shown on an illuminated 4½-digit LCD display. The
parameter to be displayed is selected with a toggle switch.
The switch on/off delay and the softstart function protect the laser diode against
undesired transients.
An independent hardware limit for the inject ion current can be set with a 20-turn
potentiometer. This protects the laser diode against operating errors.
With the output open the laser diode is shortcircuited electronically so no voltage is
applied to the laser diode.

1.1 At a Glance
LDC2xx / page 2
When turned on the laser diode controller L DC2xx is automatica lly in LASER OFF
mode. The laser current can be switched on/off with a separate key at the front panel.
Laser diode and photodiode are connec ted by a 9-pin D-sub jack at the rear of the
unit. The output for the laser diode and the input for the photodiode are bipolar, thus
all polarities of commercial available laser diodes can be connected.
With a control signal at the output jack an external LED can be used to indicate
LASER ON.
The injection current or the optical output power of the laser diode can be modulated
via a modulation input at the rear of the unit.
For monitoring purposes a voltage proportional to the laser diode current is provided
at an analog control output at the rear.
If an error occurs or the limit for the la ser current is reached, the corresponding LED
lights up and a short beep gives a warning.
The installed mains filter and careful tr ansformer shielding provide low ripple and
noise at the output.
The internal cooling of the LDC200 with a fan protects the unit against overheating in
case of high environmental temperatures.
With free air circulation a safe operation of the unit is guaranteed up to 40 °C ambient
temperature.
Attention
Do not obstruct the air-ventilation slots in the housing!
If a laser diode head and the corresponding cable (CAB 400) by Thorlabs GmbH is
used, damages caused by wrong connections are impossible.

1.2 Safety
LDC2xx / page 3
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 LDC2xx 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 the line voltage setting marked on the rear panel
agrees with your local supply and that the corresponding fuses are
inserted. If not, please have a service technician change the voltage
(see section 5.2).
Changing of the mains fuse can be done by the customer (see
section 5.3, Replacing the mains fuse)
The unit must not be operated in explosion endangered environ-
ments!
Laser and photodiodes must only be connected with duly shielded
connection cables.
Only with written consent from Thorlabs GmbH may changes to
single components 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.

1.2 Safety
LDC2xx / page 4
Attention 
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.

1.3 Ordering codes and accessories
LDC2xx / page 5
1.3 Ordering codes and accessories
Ordering-code Short description
LDC200V Laser diode controller, current range 0 ... 20 mA / 6 V
LDC201U Laser diode controller, current range 0 ... 100 mA / 2.5 V
Ultra Low Noise
LDC202B Laser diode controller, current range 0 ... 200 mA / 10 V
LDC205B Laser diode controller, current range 0 ... 500 mA / 10 V
LDC210B Laser diode controller, current range 0 ... 1 A / 10 V
LDC220 Laser diode controller, current range 0 ... 2 A / 4 V
laser diode heads for different laser diode packages:
TCLDM9 Temperature controlled laser diode head for 3- and 4-pin
TO18-packages (9 mm CD, 5.6 mm CD)
LDM21 Miniature sized temperature controlled laser diode head for 3- and
4-pin TO18-packages (9 mm CD, 5.6 mm CD)
LM14S2 laser diode head for laser modules in a 14-pin butterfly-package
(programmable pinning)
Shielded cable:
CAB400 Cable to connect the laser di ode controller LDC200 to a Laser
Diode Head

2.1 Unpacking
LDC2xx / page 6
2 Getting Started
2.1 Unpacking
Inspect the shipping container for damage.
If the shipping container seems to be dam aged, keep it until you have inspected the
contents and you have inspected the LDC2xx mechanically and electrically.
Verify that you have received the following items:
1. 1 LDC2xx
2. 1 power cord, connector according to ordering country
3. 1 operation manual
4. 1 Connection cable CAB 400
2.2 Preparation
Prior to starting operation with a laser diode controller LDC2xx, check if the line
voltage specified on the letter plate agr ees with your local supply and if the
appropriate fuse is inserted. (To change t he line voltage see 5.2, “Line voltage” on
page 25)
Connect the unit to the line with the provided mains cable. Turn the unit on by means
of the line switch (L11).
Via the connector jack of the chassis ground (R 4) the external optical build-up can be
connected to ground potential, if required. The ground pi n of the laser diode is
internally connected to chassis ground.

2.3 Operating elements
LDC2xx / page 7
2.3 Operating elements
2.3.1 Operating elements on front panel
Figure 1 Display- and operating elements at the front panel
L1 LED "AG" Selected polarity of the laser: anode grounded
L2 LED "CG" Selected polarity of the laser: cathode grounded
L3 4½-digit LCD display
L4 LED "mA" Current display in mA
L5 LED "mW" Power display in mW
L6 LED "OPEN" No laser diode connected
L6 LED "ERR" No LD connected, Interlock open, OTP (only B version)
L7 LED "LIM" Adjusted current limit reached
L8 LED "ON" Laser current is switched on
L9 Switch "ON" On/off switch for the laser current
L10 Knob to enter set values
L11 Mains switch
L12 LIM I Potentiometer for setting the current limit
L13 CAL Potentiometer for calibrating the power display
L14 LED "PLD" Displaying the optical output power
L15 LED "IPD" Displaying the photodiode current
L16 LED "ILD" Displaying the laser current
L17 LED "ILIM" Displaying current limit
L18 DOWN Select the displayed value
L19 UP Select the displayed value
L20 LED "P" Constant power mode
L21 LED "I" Constant current mode
L22 Key "P" Select constant power mode
L23 KEY "I" Select constant current mode
L24 PD RANGE Potentiometer for setting the photodiode current range
L11 L12 L13 L14 L15 L16 L17 L18 L19 L20 L21 L22 L23 L24
L1 L2 L3 L4 L5 L6 L7 L8 L9 L10
IO

2.3 Operating elements
LDC2xx / page 8
2.3.2 Operating elements on rear panel
Figure 2 Operating elements on the rear panel
R1 Modulation input/ analog control input "MOD IN", -10V … +10 V
R2 Analogue control output "CTL OUT", 0 … ±10V
R3 Fan
R4 Connector for chassis ground
R5 Connector "LD OUT" for laser diode, photodiode, interlock, status-LED
R6 Switch "LD POL" for selecting the laser diode polarity
R7 Serial number of the unit
R8 Letterplate showing allowed and set mains voltage ranges
R9 Mains connector and fuse holder

2.4 First operation
LDC2xx / page 9
2.4 First operation
Turn the unit on by means of the line switch (L11).
Via the connector jack of the chassis ground (R 4) the external optical build-up can be
connected to ground potential, if required. The ground pi n of the laser diode is
internally connected to chassis ground.
After switching on the unit, the LCD display (L3) must get visi ble and a LED must
light up indicating the selected parameters (L14 ... L17). If no display is shown please
check line voltage and line fuse.
By using the keys (L18) and (L19) you can select the desired value to be displayed at
any time.
The LDC2xx is immediately ready to use after turning on. The rated accuracy is
reached, however, after a warming-up time of approx. 10 minutes.

3.1 Connecting components
LDC2xx / page 10
3 Operating the LDC2xx
3.1 Connecting components
3.1.1 9-pole SUB-D output jack
The laser diode controller LDC2xx by Thorlabs GmbH can (according to the version)
drive all laser diodes up to a maximum current rate of 2 A.
If laser mounts by Thorlabs GmbH are used just connect the input "LD DRIVER" of
the laser mount to the output jack "LD OUTPUT" (R5) with the cable CAB400.
If a laser mount TCLDM9 by Thorlabs is used, the polarity of laser diode and
photodiode must additionally be set with two s lide switches inside the laser mount
(refer to the individual operation manual).
If other laser diode mounts are used connec t the laser diode and if provided the
photodiode with shielded cables to "LD OUTPUT" (R5) according to the pin
assignment shown in Figure 3.

3.1 Connecting components
LDC2xx / page 11
Figure 3 Pin assignment of the "LD OUTPUT"jack (female)
pin connection
open circuit monitoring, status display:
1 interlock and status LASER ON/OFF
5 digital ground for pin 1
laser diode:
7 laser diode cathode (at AG)
8 laser diode anode (at CG)
3 laser diode ground
photodiode:
2 photodiode cathode
4 photodiode anode
3.1.2 Interlock and control LED for LASER ON
Pin 1 and pin 5 of the "LD OUTPUT" jack (R5) are test contacts to determine whether
a laser diode is connected or not or if the connection to the laser diode has been
interrupted during operation.
Figure 4 Connecting the interlock with and without monitoring LED
5-4-3-2-1
9-8-7-6

3.1 Connecting components
LDC2xx / page 12
Pin 1 and pin 5 must be connected externa lly by a wire (total resistance <430 Ω).
When opening this connection, the LDC2xx swit ches automatically into LASER OFF
mode.
A LED can be connected in parallel to a resistor of <470 Ω between pin 1 and pin 5.
This LED lights up when the laser current is switched on (LASER ON).
With the LDC2xxB the LED ERR (L6) lights up if the interlock is open.
3.1.3 Connecting the laser diode and photodiode
Connect laser diode and photodiode according to Figure 5 to the LDC2xx.
The ground connection of the laser diode (pin 3) may be connected to the anode of
the photodiode (pin 4) or to the cathode of the photodiode (pin 2). This connection
should be as close as possible to the laser diode to avoid measuring errors.
If the polarity selected with the switch "LD POL" (R6) and the c onnection of the laser
diode do not agree, no current is flowing through the laser diode.
LD POL: AG AG CG CG
Figure 5 Connecting laser diode and photodiode

3.1 Connecting components
LDC2xx / page 13
The laser diode is always sourced with re spect to ground. Compared to a floating
driver stage, this operation mode has the advantages of higher security for the laser
diode and better stability of the laser current.
If the photodiode shall be operat ed with bias voltage a battery can be connected in
series to the photodiode.
With polarity AG connect the positive terminal of the battery to the cathode of the
photodiode and the negative terminal of the battery to pin 2.
With polarity CG connect the negative terminal of the battery to the anode of the
photodiode and the positive terminal of the battery to pin 4.
+
-pin 2 +
-
pin 4
A
G with Bias CG with Bias
Figure 6 Connecting laser diode and photodiode
Attention 
A wrong polarity of the battery may destroy the photodiode due to a
forward current flowing through it!

3.1 Connecting components
LDC2xx / page 14
3.1.4 Analog control output for the laser current
At the output "CTL OUT" (R2) a volt age proportional to the laser current "I LD" is
available.
E.g. a recorder, an oscilloscope or an A/D converter card can be connected directly
to the output.
The output "CTL OUT" (R2) provides a voltage of 0 ... ±10 V for ILD = 0 ... ILD MAX.
With laser polarity "CG" the output voltage is positive (0 … +10 V), with laser polarity
"AG" the output voltage is negative (0 … -10 V).
The output "CTL OUT" (R2) is grounded.
Devices connected to this output should have an input resistance ≥10 kΩ.
When connecting a load avoid ground loops.