Page 1
MANUAL-LDC1000 Valid from S/N:1122
Nov 2012 Rev.9.1
Laser Diode Controller
LDC1000
Operating Instructions
Page 2
2
Page 3
3
Contents
1 General ............................................................................................................... 4
1.1 Warranty and Assistance ..................................................................................... 4
1.2 Maintenance ........................................................................................................ 4
1.3 General Safety Considerations ............................................................................. 4
1.4 Laser Safety ......................................................................................................... 4
1.4.1 Laser Radiation........................................................................................................ 4
1.4.2 Laser Class .............................................................................................................. 4
1.5 System contents ................................................................................................... 6
2 Introduction ....................................................................................................... 7
3 Installation ......................................................................................................... 8
4 Operation ........................................................................................................... 9
4.1 Elements of the instrument at the front panel ....................................................... 9
4.2 Elements of the instrument at the rear panel ...................................................... 10
4.3 Laser diode controller ......................................................................................... 11
4.3.1 Instrument switch-on, display menu ......................................................................11
4.3.2 LASER Menu .........................................................................................................12
4.3.3 TIMING Menu ........................................................................................................13
4.3.4 EXT. INPUTS Menu ..............................................................................................13
4.4 Thermoelectric cooler controller ......................................................................... 14
4.4.1 TEMPERATURE Menu .........................................................................................14
4.4.2 COOLER Menu......................................................................................................15
4.5 Instrument settings ............................................................................................. 17
4.5.1 PILOT LASER Menu .............................................................................................17
4.5.2 CALIBRATION Menu .............................................................................................17
4.5.3 CONFIG Menu .......................................................................................................17
4.5.4 Interlock .................................................................................................................17
4.6 Error Messages .................................................................................................. 18
5 Connectors pin-out ......................................................................................... 20
5.1 Laser diode ........................................................................................................ 21
5.2 Thermoelectric cooler 1 ...................................................................................... 22
5.3 Thermoelectric cooler 2 ...................................................................................... 23
5.4 Interlock, Pilot Laser, Power Monitor .................................................................. 24
5.5 Serial interface ................................................................................................... 25
6 Interfaces command description ................................................................... 26
6.1 Serial interface ................................................................................................... 26
7 Specifications .................................................................................................. 30
Page 4
4
1 General
The information given in this document is subject to change without notice.
Copyright LASER ELECTRONICS 2012.
All rights reserved. Reproduction, adaptation, or translation without prior written permission is
prohibited, except as allowed under the copyright laws.
1.1 Warranty and Assistance
This instrument manufactured by LASER ELECTRONICS is warranted against defects in material and
workmanship for a period of 12 months from date of shipment to the customer. During the warranty
period, LASER ELECTRONICS will, at its option, either repair or replace products which prove to be
defective.
The warranty does not apply to defects resulting from improper use or maintenance by the buyer, from
unauthorized modifications or operation outside the environmental specifications and from
electrostatic discharge (ESD).
For warranty service or repair, the instrument should be sent to LASER ELECTRONICS in appropriate
packing. Please enclose a detailed fault report including instrument type and serial number(s).
1.2 Maintenance
The instrument does not require special maintenance if it is used correctly.
Servicing should only be performed by trained service personnel.
1.3 General Safety Considerations
Before switching on the instrument, make sure it has been properly grounded through the supplied AC
power cable to a socket outlet with a protective earth contact. Any interruption of the grounding can
result in personal injury.
This instrument must be used under normal conditions and as specified, otherwise the protection
provided by the instrument could be impaired.
Always replace blown fuses with the same rating and acting speed.
ESD: Electrostatic discharge (ESD) on or near the connectors can damage electronic devices inside
the instrument. Personnel should touch the metal frame of the instrument for a second before touching
any connector.
1.4 Laser Safety
1.4.1 Laser Radiation
This instrument is designed to control laser diodes. Please read also very carefully the operating
instructions given by the manufacturer of the laser diode.
The radiation of the used laser diode may be visible or invisible. These products emit radiation in the
630 to 1560nm spectral region.
Use caution to avoid hazardous exposure to the beam. Take precautions to eliminate exposure
to a direct or reflected beam. Do not look directly into the beam of the laser diode under
conditions which exceeds the specified limits. Never observe the laser beam through optical
instruments.
1.4.2 Laser Class
The laser safety classification and the relevant parameters of the laser diode for normal operation are
indicated on the top of the laser diode. The laser radiation is emitted through the optics at the side of
the laser diode where the warning label is placed or at the fibre connector. The laser diodes are
classified according to EN 60825-1:94.
Page 5
5
General warning label for laser radiation:
Label for laser radiation:
Label for relevant parameters (example) of the laser diode for normal operation and its statements:
Average radiant power at max. rep. frequ.: P
o
Peak radiant power: Pp
Pulse width: t
Max. pulse repetition frequency: F
Wavelength laser radiation: λ
LASER RADIATION
AVOID EYE OR SKIN EXPOSURE TO
DIRECT OR SCATTERED RADIATION
CLASS 4 LASER PRODUCT
EN 60825-1:94
Po=50W
Pp=100W
t=1ms
F=500Hz
λ=808nm
Page 6
6
1.5 System contents
Control Unit (Laser Diode Controller)
Cable for serial interface (RS232, D-Sub 9) for interconnecting instrument with PC
Connector (D-Sub 15) for interlock loop, pilot laser and power monitor
AC Power Cable
Manual
Optional:
Heat sink, air-cooled, including cables for connecting the laser diode.
Laser diode mounted on heat sink.
Second cooler controller board, ±5V / ±3A, max.15W for driving a second heat sink.
LD-cable for connecting a laser diode.
Heat sink cable for connecting a heat sink.
Sensor cable for connecting sensors.
Short-circuit bridge for the connector at the cable for the laser diode
Page 7
7
2 Introduction
The instruments of the Laser Diode Controller series are compact control units for driving mediumpower and high-power laser diodes.
The Laser Diode Controller delivers, depending on the version, a current up to 60 A at a voltage of
maximum 12 V.
The Laser Diode Controller is designed for cw and pulsed operation. With pulsed operation, various
settings of duty-cycle, pulse duration and number of pulse events are possible.
The Laser Diode Controller also features external inputs for analogue modulation of the laser diode
and external triggering of the laser diode.
Besides controlling the current of the laser diode, the Laser Diode Controller also features one or two
optional built-in controllers for thermoelectric coolers (Peltier elements). With an optional air-cooled
heatsink (please contact LASER ELECTRONICS) the laser diode can easily be kept at constant
temperature. The heatsink consists of a heat spreader on which the laser diode is mounted, several
peltier elements for heat transportation and a large heatsink profile with fans for sufficient air flow.
The unit consists of several modules. The heart is a microprocessor based central unit which controls
all other power units and provides the link to the display, keyboard and the PC interfaces. All
parameters can be set with only a few push keys and a rotary knob and are shown on the display.
Additionally the parameters can be set and controlled via an interface to a PC. For driving the laser
diode the Laser Diode Controller uses a constant current power supply which is followed by a
sophisticated designed current controlling stage. For driving the thermoelectric cooler a separate high
efficient power supply is used.
The Laser Diode Controller provides maximum laser diode protection by using AC-line filtering,
transient suppression, soft-start, short-circuiting of the output when switched off and setting of
permanent current and temperature limits.
Page 8
8
3 Installation
Please read the whole operating instructions before using this instrument together with a laser diode.
Installation of the instrument
Before installation check the local mains voltage. The instrument is equipped with auto-ranging power
supplies for a continuous input voltage from 85 to 264 V AC @ 50 - 60 Hz. If the primary fuses are
blown these can easily be replaced by the user.
Connect the instrument to the mains. Do not switch on the instrument yet.
Plug in the interlock, pilot laser, power monitor connector to the appropriate connector at the rear side
of the instrument as described in the section Connectors pin-out. This connector provides a closed
loop for the interlock feature.
Installation of the laser diode
Connect the laser diode to the leads of the provided cable as described in the section Connectors pinout.
Plug in the cable to the connector labeled Laser at the rear panel of the instrument. Fix the connector
with the locking ring.
Note: The instrument must be turned off before the cable is plugged in.
ESD: Electrostatic discharge (ESD) on or near the connectors can damage electronic devices inside
the instrument. Personnel should touch the metal frame of the instrument for a second before touching
any connector.
Laser diodes are extremely sensitive to electrostatic discharge. Follow the instructions
supplied with the laser diode very carefully.
Installation of the Heat Sink
Connect the heat sink cable and the sensor cable (optional) to the leads of the provided cable as
described in the section Connectors pin-out.
Plug in the cable to the connector labeled Cooler and Sensors at the rear panel of the instrument. Fix
the connector with the locking ring.
Note: The instrument must be turned off before the cable is plugged in.
Page 9
9
4 Operation
After installation of the laser diode, the thermoelectric cooler and the temperature sensor (respectively
the heat sink) and providing the appropriate connections including installation of the Dummy interlock
connector to the instrument the Laser Diode Controller is ready to be switched on.
Please read the whole operating instructions before using this instrument together with a laser diode.
4.1 Elements of the instrument at the front panel
1. Display
2. Keys for setting instrument (Up, Down, Left, Right, Enter)
3. Laser diode on indicator (yellow)
4. Key for turning on laser diode
5. Rotary knob for setting laser diode current and various settings within the menus
6. Power on indicator (green)
7. Power switch mains
8. Connector for input of analogue modulation signal
9. Connector for input of trigger signal
10. Connector for output of trigger signal
Page 10
10
4.2 Elements of the instrument at the rear panel
1. Mains fuse
2. Connector for AC line
3. Connector for Serial Interface (RS232)
4. Connector for Interlock, Pilot Laser (optional) and Power Monitor (optional)
5. Connector for Temperature Sensors and Cooler 2 (optional)
6. Connector for laser diode
7. Connector for Cooler 1 (Heat Sink - thermoelectric cooler 1, temperature sensor 1, fan)
Page 11
11
4.3 Laser diode controller
Attention:
Before using the Laser Diode Controller with a laser diode, make sure that the current limit is set to the
specific value of the laser diode to be used, see section LASER Menu. The current applied to the laser
diode must not exceed the maximum current specified by the manufacturer of the laser diode.
The emitted optical power of a laser diode also depends on the temperature. Make sure that with the
selected temperature of the laser diode and the emitted optical power is also within a specified range.
4.3.1 Instrument switch-on, display menu
The instrument is switched on with the Power switch (7). The green light emitting diode (LED) (6)
indicates that all relevant components inside the instrument are supplied with power. On the backlighted display the message „LASER ELECTRONICS“ appears for a short time and the display
changes to the following window:
Above left it shows the measured laser diode current and voltage, the displayed power is calculated
from the laser diode current and the calibration points (see menu calibration).
Above in the middle it shows the measured laser diode temperature T1 and the temperature of a
second cooler T2 (optional).
I1 is the current of cooler 1. “+” means heating current, and “-“ cooling current.
On the right there is the menu. By pressing the Up or Down key the menu will be changed. Below left
the parameters of selected menu will be shown.
By pressing the Left key the first parameter within selected menu will be selected for change. A small
arrow appears besides the parameter.
By pressing the Up, Down, Left and Right keys the parameters can be selected. The value of a
parameter can be changed by the rotary knob.
After changing confirm with the Enter key. Every input which is followed by pressing the Enter key (2)
is acknowledged by a short double-beep.
By pressing the Right key (one or more times) the arrow disappear and you leave the parameter
selection of the actual menu. After that you can change the menu again.
LASER
COOLER
P = 80.0W
I = 28.5A
V = 7
.2V
T1=25.0°C
I1=+9.5 A
V
1=+12
V
MENU
LASER
TEMPERATURE
TIMING
COOLER
PILOT LASER
EXT. INPUTS
CALIBRATION
CONFIG
Set Laser
>P: 80.0 W
I: 28.5 A
Mode: CW, No Time Limit
Laser Current Limit: 40.0A
Page 12
12
4.3.2 LASER Menu
Within the laser menu you can set the optical power, the laser current, the laser mode and the laser
current limit.
Laser Current Limit
Set the laser current limit to the indicated maximum current value of the laser diode which can be
found in the individual data sheet. Setting the appropriate current limit protects the laser diode from
being overloaded electrically and optically.
Confirm the value with the Enter key. The value of the laser current limit is stored permanently in a
non-volatile memory, even when the instrument is switched off.
Remark: The maximum possible laser current limit is predefined by the instrument.
I - Laser Current
After schwitching on the instrument the set laser current is 0. It can be set up to laser current limit and
must not be confirmed with the Enter key.
The laser diode is turned on by pressing the Laser key (4) and the desired current is applied to the
laser diode. The lighting yellow LED (3) nearby the Laser key indicates that the laser diode output is
turned on. The actual current that is applied to the laser diode is displayed above left at the display.
The current applied to the laser diode can also be varied when the laser diode is turned on by
modifying the desired current with the Rotary knob (5).
The laser diode is turned off by pressing the Laser key (4) again.
P - Optical Power
After schwitching on the instrument the set optical power is 0. The set optical power will calculated into
the laser current by the calibration points (see menu calibration). After changing you must not confirm
with the Enter key. The calculated laser current will be shown immediately on position set laser
current. The optical power can also be varied when the laser diode is turned on. In this case the
calculated laser current is applied to the laser diode immediately.
Laser Mode
The operational mode should only be changed when the laser diode is turned off. Nevertheless when
changing the operational mode, the laser diode is turned off automatically.
The following four operational modes can be selected and combined:
CW, No Time Limit The laser diode is operated with a continuous current. The duration of the
operation is not time limited internally. The laser diode is turned on and off by
pressing the Laser key.
CW, Time Limit The laser diode is operated with a continuous current. The duration of the
operation is time limited according to the time limit, see menu TIMING. The
laser diode is turned on by pressing the Laser key and turned off
automatically after the set time limit.
Pulse, No Time Limit The laser diode is operated with a pulsed current, see menu TIMING. The
duration of the operation is not time limited internally. The laser diode is turned
on and off by pressing the Laser key.
Pulse, Time Limit The laser diode is operated with a pulsed current. The duration of the
operation is time limited according to the time limit, see menu TIMING. The
laser diode is turned on by pressing the Laser key and turned off
automatically after the set time limit.
Confirm the value with the Enter key. The desired mode is stored permanently in a non-volatile
memory, even when the instrument is switched off.
Page 13
13
4.3.3 TIMING Menu
Within the Timing menu it can be set the pulse width, the pulse period and the time limit.
Confirm the value with the Enter key. The desired value is stored permanently in a non-volatile
memory, even when the instrument is switched off.
Notes:
The two parameters “pulse width” and “pulse period” depend on each other. The instrument will
automatically force the other parameter within the valid range depending on the change of the
selected parameter.
Values of the pulse width which are larger than the pulse period are not accepted by the instrument.
The pulse width must be within the range of 5.0 ms to 490 ms.
The pulse period must be within the range of 10 ms to 500 ms.
The time limit must be within the range of 0.1 s to 99.9 s.
4.3.4 EXT. INPUTS Menu
The Laser Diode Controller provides an external analogue modulation input, an external triggering
input and an external triggering output.
Analogue Input
The analogue modulation signal is applied to the Analog In connector (8) at the front panel. The valid
range for the signal is 0 V to +5 V. The transfer function for the applied signal voltage to the laser
diode current is 20 A / V. The modulation bandwidth is DC to 100 Hz. E.g.: A signal voltage of 2.5 V
refers to a laser diode current of 50A.
For maximum protection of the laser diode the current of the laser diode is limited to the selected
current limit. Therefore it might happen that the analogue modulated laser light is distorted due to the
clipping of the maximum applied current to the laser diode. In order not to distort the analogue
modulated laser light, pay attention not to exceed the valid analogue modulation signal level according
to the transfer function for the current.
The laser diode should be turned on with the Laser key (4) prior to the external inputs.
Change the input setting between ENABLE and DISABLE with the Rotary knob. Confirm the value
with the Enter key. The desired external input mode is stored permanently in a non-volatile memory,
even when the instrument is switched off.
Trigger Input
The trigger signal is applied to the Trig In connector (9) at the front panel. The valid range for the
signal is according the specifications for TTL signals (Low: 0 V < U < 0.8V, High: 2.4 V < U < 5 V). The
bandwidth is DC to 100 Hz. An applied TTL-low signal leads to a turned off laser. An applied TTL-high
signal leads to a turned on laser with the set laser diode current, see menu LASER. E.g.: If the laser
diode current is set to „I = 25A“, this current is applied to the laser diode when a TTL-high signal is
detected as external trigger signal.
The laser diode should be turned on with the Laser key (4) prior to the external inputs.
Change the input setting between ENABLE and DISABLE with the Rotary knob. Confirm the value
with the Enter key. The desired external input mode is stored permanently in a non-volatile memory,
even when the instrument is switched off.
Trigger Output
The signal on the trigger output connector Trig Out (10) provides a synchronization between the
internally generated pulses, as specified by the pulse operational mode, and the external trigger. The
output is according to the specifications for TTL signals.
Page 14
14
4.4 Thermoelectric cooler controller
The Laser Diode Controller contains one or two optional built-in controllers for thermoelectric coolers.
Cooler 1 is usually used for cooling the laser diode and delivered up to ±13A@±48V. The cooler 2 is
optional and is used for customized applications (e.g.: laser crystal cooling). It delivered up to
±3A@±5V. If a cooler is enabled, see menu COOLER, the appropriate temperature controller
immediately starts operating after switching on the instrument. The temperature controller attempts to
set the approptriate cooler temperature to the desired temperature which may take up to several
minutes depending on the difference of the actual temperature and the desired temperature. Due to
the large heat capacity and heat load of medium power and high power laser diodes and the needed
heatsinks, it may take some minutes until a stable operating point is reached.
The actual temperatures of cooler 1 “T1” (usually the laser diode), cooler 2 “T2”(optional) and the
current of cooler 1 “I1” are displayed above in the middle of the display.
The sign “+” means heating current, and “-“ cooling current of ”I1”.
Note:
The output of the thermoelectric controllers are bipolar, that means they can cool and heat.
Trouble-shooting:
After preparing the connection of the thermoelectric coolers and the temperature sensors according to
the section Connector pin-out and switching on the Laser Diode Controller, it might happen that the
temperature controller doesn’t seem to control the temperature, i.e. the measured temperature doesn’t
approach the desired temperature after some time or the laser diode is heated up instead of cooled
down.
In this case the polarity of the thermoelectric cooler referred to the pin-out as shown in the section
Connectors pin-out has to be changed. Simply change the connection of the two leads of the
thermoelectric cooler, even if the occurring labelling „Plus“ to „Minus“ doesn’t match obviously.
After this change the measured temperature should approach the desired temperature.
4.4.1 TEMPERATURE Menu
Within the temperature menu it can be set the temperature, the upper and lower temperature limit and
the control loop parameters of the PID-temperature controller for the first and second (optional) cooler.
Temperature
The value of the temperature can only be changed within the valid temperature range as defined by
the upper and lower temperature limit. The value for the temperature must be within 0°C to 50°C.
Confirm the value with the Enter key. The desired temperature is stored permanently in a non-volatile
memory, even when the instrument is switched off.
Temperature limits
The operating laser diode and also the optional custom application should be protected by operating
setting temperature limits according to the specific datasheet provided by the manufacturer.
If the temperature of cooler 1 or cooler 2 (provided they are enabled) are out of the selected range, the
laser diode turned off automatically and an error message appears on the display, see section Error
messages.
Confirm the value with the Enter key. The desired temperature limits are stored permanently in a nonvolatile memory, even when the instrument is switched off.
Note:
The instrument accepts only inputs where the temperature of the upper limit is higher than the
temperature of the lower limit.
The value for the upper and lower temperature limit must be within 0°C to 50°C.
Page 15
15
PID-Temperature control-loop parameters
The temperature controller is realized as a PID control loop for optimum performance (P means
proportional, I means integral and D means differential portion).
The control loop parameters can be set to values between 0 and 100. The default settings which
provide usually good controlling are as follows:
Cooler 1
Cooler 2
Portion
Value
Portion
Value
P 30 P 70
I 10 I 3
D 0 D 0
Confirm the value with the Enter key. The desired control loop parameter is stored permanently in a
non-volatile memory, even when the instrument is switched off.
If the control loop is not stable after some minutes of active operating, e.g. the temperature is
oscillating between two values which differ about 0.5 °C, the P-portion should be decreased.
If the measured temperature does not become equal to the desired temperature, the I-portion should
be increased.
Remark:
In general a larger P-portion or a smaller I-portion speeds up the settling time of the control loop, but
with the first the controller might oscillate and with the latter there might be a permanent difference
between the actual temperature and the desired temperature.
Due to the large heat capacity and heat load of high power laser diodes and the needed heatsinks, it
takes some minutes until a stable operating point is reached.
4.4.2 COOLER Menu
The Laser Diode Controller can work without, with one or with two cooler controllers. Before working,
the appropriate cooler must be enabled.
Attention
Before you enable a cooler, make sure that:
- the Laser Diode Controller was purchased with the appropriate cooler controller, see menu CONFIG
- the correct sensor type is connected on the correct connector, see section Connectors pin-out,
- the correct sensor type is selected by software, see menu COOLER,
- the appropriate cooler current limit is set, see menu COOLER.
Cooler 1/2
Change the setting between ENABLE and DISABLE with the Rotary knob. Confirm the selection with
the Enter key. The desired cooler setting is stored permanently in a non-volatile memory, even when
the instrument is switched off.
Page 16
16
Sensor 1/2
The Laser Diode Controller can work with three several temperature sensor types: NTC, PT100,
PT1000.
Attention
Before changing the sensor type, make sure that:
- the appropriate cooler controller is disabled, see menu COOLER,
- the correct sensor type is connected on the correct connector, see section Connectors pin-out.
Change the setting between NTC, PT100 and PT1000 with the Rotary knob. Confirm the selection
with the Enter key. The desired sensor setting is stored permanently in a non-volatile memory, even
when the instrument is switched off.
I
max
– cooler current limit 1/2
Cooler 1 is usually used for cooling the laser diode and delivered up to 600W ±13A@±48V. The cooler
current limit can be set from 0 .. 12A or 0 .. 13A.
Cooler 2 is usually used for customized applications (e.g.: laser crystal cooling) and delivered up to
±3A@±5V. The cooler current limit can be set from 0 .. 3A.
Always set the current limit to the maximum current value which can be found in the data sheet of the
heat sink. Setting the appropriate current limit protects the peltier elements from being overloaded
electrically.
Note:
The set limit acts in both direction. E.g. current limit 2,5A means a current range –2,5A …+2,5A.
Confirm the selection with the Enter key. The desired current limit is stored permanently in a non-
volatile memory, even when the instrument is switched off.
Fan
Normally the heat sink is provided with a powerfully fan. In most cases the full fan power will not be
used. For that reason the fan voltage can varied between 0 .. 100% of 12V in steps of 10. Confirm the
selection with the Enter key. The desired fan voltage is stored permanently in a non-volatile memory,
even when the instrument is switched off. If cooler 1 is set disable the fan is switch off.
Note:
Only do reduce the fan voltage either if the laser diode is in operation for short periods or with reduced
power. Increase the fan voltage if the cooler cannot held the set temperature.
Page 17
17
4.5 Instrument settings
4.5.1 PILOT LASER Menu
The Laser Diode Controller can drive a pilot laser up to 300mA. Before you enable, make sure that
your Laser Diode was purchased with the appropriate pilot laser, see Delivery Note. This source
deliver constant voltage (+5,0V) for a build in pilot laser (with integrated small driver). Do not drive a
laser diode on this source directly.
Pilot Laser
Change the pilot laser setting between ON and OFF with the Rotary knob. Confirm the value with the
Enter key.
Power
The pilot laser power can be reduced by a PWM (pulse width modulation) of its supply voltage. It can
be set to values between 1% and 100%. Confirm the selection with the Enter key. The desired value
is stored permanently in a non-volatile memory, even when the instrument is switched off.
4.5.2 CALIBRATION Menu
Calibrations Points
Because the laser diode current and its optical output power are approximately linear to each other,
it is possible to calculate the optical power from the current if the user set two measured pairs of laser
current / optical power.
E.g. the user set current to 20A and measured 30W optical power by a power meter. I1=20A,
P1=30W.
Then he set current to 30A and measured 55W optical power. I2=30A, P2=55W.
Note: The deviations from the correct value can increase with distance from the measured value.
Confirm the selection with the Enter key. The desired value is stored permanently in a non-volatile
memory, even when the instrument is switched off.
Power Monitor
If the laser diode is provided with a power monitor (photo diode), the power monitor voltage will be
shown. So, the calibrating can be made without a power meter.
E.g. the user increases laser current up to the power monitor voltage is 1,2V. From the laser diode
data sheet the user read 1,2V = 55W optical power. The actual laser current is 30A. I=30A, P=55W.
4.5.3 CONFIG Menu
The config menu appears the laser diode driver and cooler driver configuration.
4.5.4 Interlock
The Laser Diode Controller is equipped with an interlock feature. The interlock is realized with a loop
which has to be provided via the interlock connector, see section Connector pin-out.
The interlock loop must be realized either with the provided dummy connector (permanent closed
loop) or a peripheral device. It is prior to the Laser key at the front panel. The laser diode can only be
turned on with pressing the Laser key at the front panel if the interlock loop is closed. If the interlock
loop is opened while the laser diode is on, the laser diode is immediately turned off and a error
message appears on the display. The laser diode can only be turned on again by closing the interlock
loop.
Page 18
18
4.6 Error Messages
Interlock error
If interlock loop is opened, the laser is turned off immediately and the following message appears on
the display:
The error massage must be confirmed by pressing the Enter key.
After the interlock loop is closed again, the laser diode can be turned on again by pressing the Laser
key. If the interlock loop is still opened, the error message appears again after the Laser key is
pressed.
Temperature sensor error
If an temperature sensor circuit is shortened or opened, the laser diode and the thermoelectric coolers
are turned off immediately. One of the following messages appears on the display:
The error massage must be confirmed by pressing the Enter key.
After the Laser Diode Controller detects the temperature sensor again, the temperature controller
starts working again according to the parameters as before the error occurred. The laser diode must
be turned on again by pressing the Laser key. If the error is still present, the error message appears
again after the Laser key is pressed.
Remarks:
The error concerning the temperature sensor also appears if the connector for the thermoelectric
cooler and the temperature sensor (also named connector for the heat sink) is not connected to the
instrument. Before providing this connection, the Laser Diode Controller has to be turned off.
ERROR
INTERLOCK OPEN
ERROR
TEMPERATURE SENSOR 2
NOT DETECTED
ERROR
TEMPERATURE SENSOR 1
SHORTED
ERROR
TEMPERATURE SENSOR 1
NOT DETECTED
ERROR
TEMPERATURE SENSOR 2
SHORTED
Page 19
19
Temperature range error
If the temperature of a cooler is out of the range as defined with the temperature limits in
TEMPERATURE menu, the laser diode and the thermoelectric coolers are turned off immediately.
One of the following messages appears on the display:
The error massage must be confirmed by pressing the Enter key.
After the laser diode reaches the allowed temperature range again, the laser diode can be turned on
again by pressing the Laser key. If the error is still present, the error message appears again after the
Laser key is pressed.
Overload error
If a device module of the Laser Diode Controller overloaded, the laser diode and the thermoelectric
coolers are turned off immediately. One of the following messages appears on the display:
Case Temperature error
If the case temperature falls below 0°C or exceeds 50°C, the laser diode and the thermoelectric
coolers are turned off immediately. The following message appears on the display:
The second error can be caused by defect case fan, blocked ventilation slots at the bottom or by to
high ambition temperature.
Controller Unit error
If the controller detects an internal error on the controller unit, the laser diode and the thermoelectric
coolers are turned off immediately. The following message appears on the display:
If this error occurs, please contact LASER ELECTRONICS for repair.
ERROR
TEMPERATURE 2
OUT OF RANGE
ERROR
TEMPERATURE 1
OUT OF RANGE
ERROR
LASER DRIVER
OVERLOAD
ERROR
COOLER DRIVER 1
OVERLOAD
ERROR
COOLER DRIVER 2
OVERLOAD
ERROR
CASE TEMPERATURE TO HIGH
WORKING RANGE 0..50°C
ERROR
CASE TEMPERATURE TO LOW
WORKING RANGE 0..50°C
ERROR
CONTROLLER UNIT
ERROR
Page 20
20
5 Connectors pin-out
As an option the instrument comes with the appropriate cables for the connectors used. At one end
the cable jacket is stripped off and the leads are separated.
Please connect the leads as shown in the following subsections.
Fix the leads to the appropriate connectors supplied with your laser diode.
If the instrument comes with a heat sink provided by LASER ELECTRONICS, only the wiring between
the laser diode and the two coloured leads (red and black) at the heat sink according the subsection
„laser diode“ has to be done.
If the instrument comes with a heat sink and an already mounted laser diode provided by LASER
ELECTRONICS, remove the short-circuit bridge at the connector of the cable for the laser diode and
simply plug in the connectors for the laser diode and the heat sink.
Attention -1-:
Double-check if the wiring was done the right way. A mismatch destroys the laser diode within
microseconds in a unrecoverable way!
Laser diodes are extremely sensitive to electrostatic discharge. Follow the instructions
supplied with the laser diode very carefully.
The instrument must be turned off before making the connection to the output for the laser
diode, the thermoelectric controller and the temperature sensor.
LASER ELECTRONICS is not responsible for any damage arising from a mismatch in wiring.
Attention -2-:
The output pin „laser diode anode, plus, „+“ „ which is connected to the anode (A) of the laser diode is
internally connected to any internal power supply voltage of the instrument.
Please be aware that most of all medium and high power laser diodes have their housing electrically
connected to the anode of the laser diode.
Therefore in order to avoid any grounding loops when applying external instruments to the Laser
Diode Controller unit it is recommended to isolate the housing of the laser diode from the chassis
(earth).
Remark: If the laser diode is mounted to the heat spreader of the heat sink provided by LASER
ELECTRONICS it is already isolated from chassis ground (earth).
Page 21
21
5.1 Laser diode
The instrument must be turned off before making the connection.
Up to 70A laser driver current the instrument comes with a laser diode connector. For higher currents
the cables are fixed connected at the device.
The connector for the laser diode (5) is located at the rear panel of the instrument and it is a male
type.
The pin-out is shown when facing the connector (male) mounted to the rear panel directly.
Pin number Designation Wire Colour
1, 5, 6 Laser diode anode (plus, „+“) red
2, 4, 7 Laser diode cathode (minus, „-“) black or brown
3 not connected (n.c.)
For best performance some pins have the same designation.
1 2
3 4 5
6 7
Page 22
22
5.2 Thermoelectric cooler 1
The instrument must be turned off before making the connection.
The connector for the cooler 1, the temperature sensor 1 (type: NTC) and the fan (as of the heat sink)
(6) is located at the rear panel of the instrument and it is a female type.
The pin-out is shown when facing the connector mounted to the rear panel directly.
Pin number Designation Wire Colour
1 Thermoelectric cooler 1 (Peltier) minus blue
2 Thermoelectric cooler 1 (Peltier) plus red
3 Temperature sensor 1 (type NTC) white
4 Temperature sensor 1 (type NTC) grey
5 Fan plus brown
6 Fan minus black
Center Pin Earth green-yellow
The green-yellow lead (earth) is connected to the base plate of the heatsink, do not connect it to the
laser diode housing or to the heatspreader on which the laser diode is directly mounted.
4 3
5 2
6 1
Page 23
23
5.3 Thermoelectric cooler 2
The instrument must be turned off before making the connection.
The connector for the cooler 2 and for the temperature sensors (4) is located at the rear panel of the
instrument and it is a 25 pol. SUB-D female type.
25pol. Sub-D female Function Wire Colour
1 (NTC-1A),
3 (PT100-1A),
5 (PT1000-1A)
Cooler 1 Sensor pin A
14 (NTC-1B)
16 (PT100-1B)
18 (PT1000-1B)
Cooler 1 Sensor pin B
2 (NTC-2A)
4 (PT100-2A),
6 (PT1000-2A),
Cooler 2 Sensor pin A green
15 (NTC-2B)
17 (PT100-2B),
19 (PT1000-2B),
Cooler 2 Sensor pin B yellow
10 Cooler 2 Peltier +
brown
23
12 Cooler 2 Peltier - white
25
Trouble-shooting:
After preparing the connection of the thermoelectric cooler and the temperature sensor according to
the section Connector pin-out and switching on the Laser Diode Controller, it might happen that the
temperature controller doesn’t seem to control the temperature, i.e. the measured temperature doesn’t
approach the desired temperature after some time or the laser diode is heated up instead of cooled
down.
In this case the polarity of the thermoelectric cooler referred to the pin-out as shown in the section
Connectors pin-out has to be changed. Simply change the connection of the two leads of the
thermoelectric cooler, even if the occurring labelling „Plus“ to „Minus“ doesn’t match obviously.
After this change the measured temperature should approach the desired temperature.
13 1
25 14
Page 24
24
5.4 Interlock, Pilot Laser, Power Monitor
The connector for the interlock, pilot laser and power monitor (3) is located at the rear panel of the
instrument.
The connector at the rear panel is a D-Sub 15, female.
The pin-out is shown when facing the connector mounted to the rear panel directly.
Pin number Designation Remark
1 Interlock - IN (+5V = open, GND = short ) galvanically isolated
Input
2 Interlock - GND
3 Pilot Laser + (+5V, max. 300mA) galvanically isolated
output
4 Pilot Laser - GND
5 Power Monitor auxiliary voltage (+5V/10mA)
6 Power Monitor Signal+
7 Power Monitor - GND
8 - 15 n.c.
The interlock is realized with a loop as shown in the diagram below. It shows the condition when the
interlock loop is closed. The interlock is prior to the Laser key at the front panel.
If the interlock loop is opened, the laser diode is immediately turned off and a error message appears
on the display. The laser diode can only be turned on again by closing the interlock loop.
The Laser Diode Controller comes with a Dummy connector (D-Sub 15) which provides the interlock
loop. When realizing the interlock loop with a peripheral device, open the dummy connector, remove
the jumper from Pin1 to Pin2 and apply the cable coming from the peripheral device.
Instead of realizing a (passive) closed loop it is also possible to apply a TTL-level signal to Pin1
referred to Pin2.
Pin1 = High (U > 2.4 V) Interlock loop open (Laser turned off)
Pin1 = Low (U < 0.8 V) Interlock loop closed (Laser turned on)
8 1
15 9
Pin 1
Pin 2
Norm ally closed
contact (opening
contact) at
peripheral device
Page 25
25
Pin2 = Reference (Signal Ground)
Some laser diode modules include a pilot laser. The LDC1000 is provided with a pilot laser control
feature. It can deliver 5V at max. 300mA. Please note, that this power supply is a constant voltage
power supply and can not drive laser diodes directly. The pilot laser power adjustment is realized by
pulse width modulation.
In addition some laser diode modules are provided with a power monitor (photo diode). The LDC1000
can display this power monitor voltage for calibrating the P/I curve.
5.5 Serial interface
The connector for the serial interface (2) is located at the rear panel of the instrument.
The instrument must be turned off before making the connection.
The connector at the rear panel is a D-Sub 9, male.
5 1
9 6
The pin-out is shown when facing the connector mounted to the rear panel directly.
Pin number Designation Remark
2 RXD (receive) galvanically isolated
In-/Output
3 TXD (transmit)
5 GND
1, 4, 6, 7, 8, 9 n.c.
The instrument comes with a suitable cable for connecting it to a free serial port of a computer. Only
use so-called interconnecting serial cables with two female connectors where the leads for pin 2 and 3
are crossed on both ends. A simple extension cable does not work.
Page 26
26
6 Interfaces command description
The instrument can be remotely controlled by a PC. All parameters can be set and read-out with a
choice of commands including turning on and turning off of the laser diode.
6.1 Serial interface
Please make the appropriate connection with the provided cable from a free serial port of the PC to
the serial interface connector of the Laser Diode Controller. Then switch on the instrument.
Any program which provides the transfer of commands via a serial communication port of a PC can be
used. Select the correct port (e.g. COM 1).
Set the serial port parameters as follows:
Baud-rate 38.400
Data-bits 8
Stop-bits 1
Parity none
Description of the format of the transfer protocol:
First, there are two keywords which represent the action of writing or reading of information to and
from the Laser Diode Controller:
• Write keyword: set
• Read keyword: get
These keywords are followed by a command, separated by a space. Some commands require the
additional input of a parameter and maybe also a unit.
• Writing a command
set ccc <Enter>
e.g. Turning on or turning off the laser diode depending on the condition before the command was
sent out (toggle function): set LAS <Enter>
• Writing a command with a parameter
set ccc vv.v <Enter>
e.g. Setting the current of the laser diode to 12.5 A: set SLC 12.5 <Enter>
e.g. Setting the pulse width to 100 milliseconds: set PUW 100ms <Enter>
After modifying the parameter the value will be send back to the PC automatically as
acknowledgement.
e.g. After setting the current of the laser diode to 12.5 A: s SLC 12.5 <Enter> the string “12.5A”
will be send back.
• Reading a value or condition
get ccc <Enter>
e.g. Reading the actual temperature of the laser diode (channel 1): get at1 <Enter>
In response the instrument sends out to the PC for example the string 25.3 °C.
Page 27
27
The Laser Diode Controller accepts only parameter values which are within the predefined range or
within the limits which have been set.
Note: The word <Enter> represents the ENTER key on the PC keyboard.
The following parameters can be read or read and set:
Command
Abbreviation
Parameter
required
Read
only
Key-in
unit
required
Used
unit
Laser On/Off LAS - Laser operating mode LMO
∗
- -
Pulse width (5.0ms < PUW < 490 ms) PUW
∗
ms ms
Pulse period (10 ms < PUP < 500 ms) PUP
∗
ms ms
Time limit (0.1 s < TIL < 99.9 s) TIL
∗
s s
Laser actual voltage ALV
∗
- V
Laser actual current ALC
∗
- A
Laser set current SLC
∗
- A
Laser actual power ALP
∗
- W
Laser set power SLP
∗
- W
P1 – power of calibration point 1 P1P
∗
- W
I1 – current of calibration point 1 P1I
∗
- A
P2 – power of calibration point 2 P2P
∗
- W
I2 – current of calibration point 2 P2I
∗
- A
Power Monitor POM
∗
- V
Laser current limit LCL
∗
- A
Analog input enable AIE
∗
- -
Trigger input enable TIE
∗
- -
Actual temperature cooler 1 AT1
∗
- °C
Set temperature cooler 1 ST1
∗
- °C
Upper temperature limit cooler 1 UT1
∗
- °C
Lower temperature limit cooler 1 LT1
∗
- °C
P - control loop parameter cooler 1 PV1
∗
- -
I - control loop parameter cooler 1 IV1
∗
- -
D - control loop parameter cooler 1 DV1
∗
- -
Actual temperature cooler 2 AT2
∗
- °C
Set temperature cooler 2 ST2
∗
- °C
Upper temperature limit cooler 2 UT2
∗
- °C
Lower temperature limit cooler 2 LT2
∗
- °C
P - control loop parameter cooler 2 PV2
∗
- -
I - control loop parameter cooler 2 IV2
∗
- -
D - control loop parameter cooler 2 DV2
∗
- -
Cooler 1 enable CE1
∗
- -
Cooler 1 sensor CS1
∗
- -
Cooler 1 current (set current in %) CC1
∗
- %
Cooler 1 current limit CL1
∗
- A
Cooler 1 actual current AC1
∗
- A
Cooler 1 actual voltage AV1
∗
- V
Cooler 1 fan voltage (0, 10, 20…100) FV1
∗
- %
Cooler 2 enable CE2
∗
- -
Cooler 2 sensor CS2
∗
- -
Cooler 2 current (set current in %) CC2
∗
- %
Cooler 2 current limit CL2
∗
- A
Pilot laser enable PLE
∗
- -
Pilot laser power PLP
∗
- %
Page 28
28
Actual case temperature ATC
∗
- °C
Error status ERR
∗
- -
Remark:
Some terminal programs send out the corresponding code right after the key was hit. Therefore a
wrong input must be finished with hitting the ENTER key on the PC and the input must be repeated.
Note:
The value for the temperatures, the upper and lower temperature limits must be within 0°C to 50°C.
Specific associations:
• Laser operating mode (set LMO v)
Following associations of parameter values to be typed in are valid:
Value v Laser operating mode Remark
0 CW, NO TIME LIMIT Default
1 CW, TIME LIMIT
2 PULSE, NO TIME LIMIT
3 PULSE, TIME LIMIT
• Get condition laser (get LAS)
Following associations of values which will be returned are valid:
Value v Condition laser diode
0 Laser diode off
1 Laser diode on
• Set condition laser (set LAS)
The command for setting the condition (turning on or turning off) of the laser diode has a toggle
function. Each time the command set LAS is sent out the condition of the laser diode changes.
For example if the laser diode is presently turned off (as for example when the Laser Diode
Controller is just switched on with the Power switch), the laser diode will be turned on when the
command set LAS is sent out. On the other hand if the laser diode is presently turned on and the
command set LAS is sent out, the laser will be turned off.
Therefore we recommend to use the following programming structure:
First get the condition of the laser diode whether it is turned on or turned off with the command get
LAS. Depending on the returned value and the desired action by the user the decision to send the
command set LAS should be done.
• Enable parameters (set AIE v)
The value for setting a “enable” parameter:
Value v “enable” parameter
0 DISABLE
1 ENABLE
E.g. set AIE 1 enabled the analog input.
Page 29
29
• Sensor type (set CS1 v)
The value for setting sensor type:
Value v Sensor type
0 NTC
1 PT100
2 PT1000
E.g. set CS1 0 sets cooler sensor 1 of NTC.
• Error status (get ERR)
Following associations of values which will be returned are valid:
Value v Error status
0 No error
1 Interlock open
2 Temperature sensor 1 not detected
3 Temperature sensor 2 not detected
4 Temperature sensor 1 shorted
5 Temperature sensor 2 shorted
6 Temperature 1 out of range
7 Temperature 2 out of range
8 Laser driver overload
9 Cooler driver 1 overload
10 Cooler driver 2 overload
11 Key switch off
12 Controller error
13 Case temperature to low (< 0 °C)
14 Case temperature to high (> 50 °C)
Note:
If an error occurs, the error status keep its value until the device receive the error reset command:
set ERR 0.
Notation for the format of the transfer protocol:
The keywords and the commands can be written either in lower case or upper case. We used lower
cases for the keywords and upper cases for the commands right here.
The keywords, the commands and the parameters must be separated by a space.
The command ccc consists of a three digit word.
The parameter ppp consists of a one to three digit value with or without a separation dot. The
following variations are possible: p, pp, ppp, p.p, pp.p
The use of units is only required for the input of the pulse width, the pulse period and the time limit.
The unit must follow the parameter value without a space.
Page 30
30
7 Specifications
Laser Diode Controller
Power Laser Diode Driver
(corresponding order)
300 W 600 W 1.500 W
Max. Laser Diode Current 60A 70A 50A 100A 120A 150A 55A 65 A 100A 125A
Max. Laser Diode Voltage 5 V 3,6V 12V 6 V 5 V 3,6 V 28V 24 V 15 V 12 V
Ripple / Noise (rms) [mA] 100 100 100 200 200 200 100 100 200 200
Current Limit Range 0 … Max. Laser Diode Current
Current Adjustment Accuracy 100 mA
Temperature Coefficient < 100 ppm/°C
Short Term Stability (1hr) < 30 ppm
Long Term Stability (24hr) < 75 ppm
Repetition Rate 0 … 100 Hz
Pulse Width (*) > 5 ms
Rise- / Fall- Time (*) < 2ms (10 % – 90 % of max. current)
Analog Modulation
Input (BNC connector)
0 … 5 V, 1 kΩ
Transfer function 20 A/V up to 70 A max. laser current
40 A/V above 70 A max. laser current
Bandwidth 0 … 100 Hz
Trigger
Input (BNC connector) TTL-level (High: U>2.4 V, Low: U<0.8 V)
Output (BNC connector) TTL-level (High: U>2.4 V, Low: U<0.8 V)
Transfer function for TTL high Iout = I set
Transfer function for TTL low Iout = 0 A
Bandwidth 0 … 100 Hz
Pilot Laser
Pilot Laser Voltage 5 V
Pilot Laser Current max. 300mA
Pilot Laser Power Adjustment 1 … 100 %
Power Monitor
Input Voltage 0 … 10,00 V
Input Resistance
1MΩ
Page 31
31
TEC Controller
Temperature Range 0 ... 50 °C
Temperature Stability < 0,1 K
Temperature Adj. Accuracy 0,1 K
Control Loop PID
Output
Cooler 1
TEC Output Power (corresponding order) 300 W 600 W
TEC Current
0.. ±7 A 0.. ±12 A 0.. ±14 A 0.. ±13 A
TEC Voltage
0.. ±48 V 0.. ±28 V 0.. ±24 V 0.. ±48 V
TEC Current Limit Range 0.. 7 A 0.. 12 A 0.. 14 A 0.. 13 A
Ripple 100 mA
Fan Voltage Adjustment Range (manual) 6 ... 12 V
Fan current max. 1 A
Output
Cooler 2 (optional)
TEC Output Power 15 W
TEC Current
0 ... ±3 A
TEC Voltage
0 ... ±5 V
TEC Current Limit Range 0 ... 3 A
Ripple 50 mA
Temperature Sensors
Sensor Types Thermistor / PT100 / PT1000
Thermistor
NTC, 10 kΩ @ 25°C, current: 100 µA
Power Supply
Line Voltage 85 - 264 V AC, autoranging
Frequency 50 - 60 Hz
Power Consumption 1.500 W
Fuses rating for 115V AC 16A slow acting (5x20mm)
Fuses rating for 230V AC 8A slow acting (5x20mm)
General Characteristics
Ambient Temperature, operating 0 ... 30 °C
Relative Humidity, operating 30 ... 70 %
Weight 11,1 kg
Dimensions
465 x 150 x 500 (W x H x D, mm3)
Notes:
(*) The risetime, the falltime and the pulsewidth may be prolonged by long cables between the power
supply and the laser diode.
The signal ground (shielding) of the BNC-connectors of the trigger input, the trigger output and the
analogue modulation input BNC-connector are isolated from the chassis ground (earth).
Attention:
The output pin „laser diode anode, plus, „+“ „ which is connected to the anode (A) of the laser diode is
internally connected to any internal power supply voltage of the instrument.
Please be aware that most of all medium and high power laser diodes have their housing electrically
connected to the anode of the laser diode.
Therefore in order to avoid any grounding loops when applying external instruments to the Laser
Diode Controller unit it is recommended to isolate the housing of the laser diode from the chassis
(earth).
Remark: If the laser diode is mounted to the heat spreader of the heat sink provided by LASER
ELECTRONICS it is already isolated from chassis ground (earth).
Loading...