THORLABS LDM9T User manual

LDM9T
Laser Mount with TEC
and Controller
User Guide

LDM9T
Table of Contents
Chapter 1 Warning Symbol Definitions ...........................................1
Chapter 2 Safety.................................................................................2
Chapter 3 Description........................................................................3
3.1. Package Contents .......................................................... 4
Chapter 4 Setup..................................................................................5
4.1. Setup Instructions .......................................................... 5
4.2. Special Note for 4-Pin Laser Diodes ................................ 6
4.3. Laser Diodes without a Monitor Photodiode .................. 6
4.4. Mount Power and TEC Control ....................................... 7
4.5. Thorlabs LDC Series Laser Controller Connection ............ 7
4.6. Using a Third-Party Laser Controller............................... 8
Chapter 5 Operation...........................................................................9
5.1. General.......................................................................... 9
5.2. RF Modulation............................................................... 9
5.3. Status and Interlocks ................................................... 10
5.4. Active Cooling System.................................................. 10
5.5. Safe Operating Area (SOA)........................................... 11
5.6. Maintaining the LDM9T ............................................... 12
Chapter 6 Making Safety Interlock Connections ..........................13
Chapter 7 Trouble Shooting............................................................14
Chapter 8 Specifications.................................................................15
Chapter 9 Mechanical Drawing.......................................................19
Chapter 10 Regulatory.......................................................................20
Chapter 11 Thorlabs Worldwide Contacts.......................................21

LDM9T Chapter 1: Warning Symbol Definitions
Rev G, Jan 22, 2017 Page 1
Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your
device.
Symbol
Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation
Caution: Spinning Blades May Cause Harm

LDM9T Chapter 2: Safety
Page 2 15827-D02
Safety
WARNING
Make sure the laser diode is installed correctly and the polarity switches on the
mount are set as per the laser diode pin configuration provided by the
manufacturer. Connecting the LD driver to mount with incorrect installation may
damage the laser diode.
WARNING
The RF input is directly coupled to the laser. Any excessive transients or noise
will be coupled into the laser and may cause the laser to be overdriven. Also,
the laser can be easily overdriven if excessive RF power is applied to this input.
Use the RF modulation input with care to avoid damaging your laser or mount.

LDM9T Chapter 3: Description
Rev G, Jan 22, 2017 Page 3
Description
Features
•Ø5.6 mm (TO-56) and Ø9 mm (TO-9) Laser Diodes Compatible
•Integrated TEC Controller
•Bias-T Adapter for RF Modulation of Laser Current up to 1 GHz
•TEC Element Prolongs LD Life and Stabilizes Output Power and
Wavelength
The LDM9T is a laser diode mount that features an integrated thermo-electric
cooler (TEC) and temperature controller to precisely regulate the operating
temperature of a laser diode. This mount is designed for users who wish to
temperature control laser diodes without the need for an external TEC controller.
By integrating the TEC, the PID loop settings have to be tuned specifically for the
mount at the factory. The temperature range is limited to approximately 20 to
30 °C due to the size of the package. The TEC control circuit provides a stable,
cost effective, temperature platform for laser diodes. This, combined with current
control, can be used to stabilize or tune the laser diode wavelength.
The LDM9T is compatible with Thorlabs series of LDC controllers. A four pin
socket accepts all Ø9 mm (TO-9) and Ø5.6 mm (TO-56) laser diodes packages.
Easy to use polarity switches allow the laser mount to be configured for the laser
pin assignments shown in the image below. The laser can be directly modulated
to >1GHz using a 50 RF bias-T.
The mount’s safety and protection features include reverse bias protection
diodes, remote safety interlock connection, and a TEC lockout circuit that
prevents enabling of the laser diode unless the temperature controller is also
enabled. The TEC lockout can easily be bypassed by setting an on-board
jumper.
The LDM9T mount has a compact design, with a low speed fan to increase the
cooling capacity, and still offers the features typical to our other products. The
mounting options include multiple #8-32 (M4-0.7 on the /M version) mounting
holes, 30 mm cage system mounting holes, and SM1 threaded aperture.

LDM9T Chapter 3: Description
Page 4 15827-D02
Figure 1 Supported Pin Configurations
3.1. Package Contents
•LDM9T Mount
•Ø9 mm LD Flange
•Ø5.6 mm LD Flange
•Replacement Screws
•HK564 5/64" Hex Key
•Operating Manual

LDM9T Chapter 4: Setup
Rev G, Jan 22, 2017 Page 5
Setup
4.1. Setup Instructions
•Unpack the laser mount and remove the four 2-56 socket head screws
from the top cover using a 5/64" hex driver.
•Remove the two 2-56 socket head screws securing the Ø9 mm flange to
the copper cold plate with a 5/64" hex driver.
•Determine the laser pin configuration from the laser diode
manufacturer’s data sheets and set the LD (Laser Diode) and PD
(Photodiode) switches on the inside of the LDM9T.
Figure 2 Polarity Switch Settings
•The four sockets comprising the laser diode connector are through-hole-
type sockets.
•Most laser diodes are three pins with the case tied to one of the laser
pins and also to one of the photodiode pins. The other laser and
photodiode pin will be isolated from the case. The LDM9T was designed
to operate the laser case at ground potential therefore this common pin
will be inserted into either the 9 o’clock or the 3 o’clock position of the
laser connector, marked G (Ground). Locate the isolated laser pin and
insert it in the 6 o’clock position, marked LD. The isolated photodiode
should now be in the 12 o’clock position, marked PD.
Figure 3 Laser Diode Socket

LDM9T Chapter 4: Setup
Page 6 15827-D02
•Make sure the laser diode is flush with the cold plate. Install the
appropriate mounting flange, either Ø5.6 mm or Ø9 mm, over the laser
diode and secure in place using the provided screws. A spare set of
screws is provided with the mount.
•Lastly, reattach the cover plate using the two 2-56 socket head screws.
WARNING
Make sure the laser diode is installed correctly and the polarity switches on the
mount are set as per the laser diode pin configuration provided by the
manufacturer. Connecting the LD driver to mount with incorrect installation may
damage the laser diode.
4.2. Special Note for 4-Pin Laser Diodes
The LDM9T also supports 4-pin laser diodes. Insert the laser into the 4-pin
socket and note which laser pin is in the 6 o’clock position (laser anode or
cathode). Also, note which photodiode pin is in the 12 o’clock position (anode or
cathode). The mount will tie the laser and photodiode pins located at 9 o’clock
and 3 o’clock together and also to ground. By noting which polarity pins are
inserted in the socket, you can convert the 4-pin layout to one of the 3-pin layouts
in Figure 2 on page 5. Set the LD and PD polarity switches accordingly.
4.3. Laser Diodes without a Monitor Photodiode
Laser diodes without a monitor photodiode will also work with the LDM9T. The
laser diode pins must be positioned between the LD and G positions. Some 2 pin
packages will not align with the laser diode socket, but 3 pin versions can be
mounted.
Pin style G is a special case. To properly operate this laser diode style, the
internal jumper JP2 needs to be installed. This will short the PD pin to G. The
user will need to determine if they want to operate with the LD anode or cathode
grounded. The laser diode needs to be oriented so that the preferred grounded
LD pin is oriented to the PD pin. This will align the remaining laser diode pin into
the LD socket. The laser diode pin oriented toward the PD pin will determine the
switch position.
Laser Lead in PD Socket
LD Switch
PD Switch
Anode
AG
CG
Cathode
CG
AG
It should be noted that both PD pins will now be grounded giving erroneous
readings on controllers with photodiode measurement circuits.

LDM9T Chapter 4: Setup
Rev G, Jan 22, 2017 Page 7
4.4. Mount Power and TEC Control
•Locate the included power supply module and the supplied line cord.
Install the line cord into the power supply and plug into an appropriate
wall socket.
•Plug the power supply output plug into the LDM9T power input
receptacle located on the side of the unit.
•Power the mount using the slide switch located on the top of the unit.
The fan should immediately turn on and the Power LED should light.
•As soon as the unit is powered on the temperature will start stabilizing
to the setpoint determined by the “TEMP ADJ” knob. Allow a couple of
minutes for the temperature to stabilize whenever the unit is powered up
or the laser diode average power level is changed.
•To adjust the temperature setpoint simply adjust the Temp Adj knob
located on the top of the mount.
4.5. Thorlabs LDC Series Laser Controller Connection
•The LDM9T is compatible with all Thorlabs LDC laser diode controllers.
Thorlabs’ ITC series combination controllers (LD and TEC) may also be
used however the TEC control provided will not be used. It may be
necessary to adjust the protection settings to allow operation without the
TEC protection provided by the ITC. Appropriate cables are included
with our controllers and ensure that the controllers cannot be connected
incorrectly.
•The nomenclature for the Laser Diode polarity switch on the LDC40xx
and ITC40xx drivers and the LDM9T are consistent with each other. For
example, if the laser polarity on the driver is set to “AG” (anode
grounded), then the LD polarity switch on the LDM9T should also be set
to AG.
•The nomenclature for the Photo Diode polarity switch on the
LDC40xx/80xx and ITC series drivers and the LDM9T is as follows: The
photodiode polarity switch on the LDM9T must always be set to “CG”.
The photodiode polarity should be set with the internal Laser controller
switch only. For more information on how to set Polarity settings on the
Laser controller, please refer to the appropriate Laser Controller
manual.
Note: The LDC and ITC series controllers can be used to monitor the photodiode
current “IPD”. If the sign of the photodiode current “IPD” is negative, the photodiode
is reversed. Please double check the laser diode pin configuration and polarity
switches before turning on the unit.

LDM9T Chapter 4: Setup
Page 8 15827-D02
4.6. Using a Third-Party Laser Controller
When using a third-party controller, a custom cable will have to be made to
properly interface to the laser mount. Please refer to the table below for laser
connections.
Figure 4 LD Controller DB9 Connection
Pin
Signal
Description
1
Interlock and
Status Pin
(LDC Specific)
This pin is the input to the LD Status indicator and interlock
circuits. When using Thorlabs’ LDC controllers, no external
circuitry is required.
2
Photodiode
Cathode
This pin is connected to the 12 o’clock pin on the laser
socket when the PD polarity switch is set to AG (anode
grounded). It is attached to ground and the 9 o’clock and 3
o’clock pins on the laser socket when the PD polarity switch
is set to CG (cathode grounded).
3
Laser Ground
(Case)
This pin is connected to the 9 o’clock and 3 o’clock pins on
the laser socket and corresponds to the settings of the LD
and PD polarity switches. i.e., If the LD and PD switches are
set to AG, then this pin grounds the anode of the laser diode
and photodiode.
4
Photodiode
Anode
This pin is connected to the 12 o’clock pin on the laser
socket when the PD polarity switch is set to CG (cathode
grounded). It is attached to ground and the 9 o’clock and 3
o’clock pins on the laser socket when the PD polarity switch
is set to AG (anode grounded).
5
Interlock and
Status Return
This pin is the return side of the Status and Interlock
circuitry.
7
Laser Diode
Cathode
This pin is connected to the 6 o’clock pin on the laser socket
when the LD polarity switch is set to AG (anode ground).
Otherwise it is floating.
8
Laser Diode
Anode
This pin is connected to the 6 o’clock pin on the laser socket
when the LD polarity switch is set to CG (cathode ground).
Otherwise it is floating.
6, 9
NC
These pins are typically used to monitor LD voltage when
used with the Thorlabs LDC series controllers. This mount
does not support this feature.

LDM9T Chapter 5: Operation
Rev G, Jan 22, 2017 Page 9
Operation
5.1. General
Once the laser diode is mounted in the LDM9T and a Laser Diode Current
Controller is connected, the device is ready to operate. Please refer to the
operating instructions for the laser controller for specific operating instructions.
The LDM9T may be modulated at low bandwidth through the laser controller.
This mount includes a high bandwidth bias T circuit that allows RF modulated
signals to be added to the laser controller signal. See RF Modulation below for
more details.
The TEC control circuit is always active when powered. The cold plate
temperature will stabilize to the set point temperature indicated on the TEMP
ADJ knob. There is no tuning of PID setting for this system as long as the unit is
operated within the safe operating area as described in section 5.5, page 11.
5.2. RF Modulation
The LDM9T has an RF input for modulating the laser with an external RF source
from 200 kHz to 1 GHz. This is a 50 Ω input that is AC-coupled directly to the
laser through the Bias-T network. To calculate the desired RF power to modulate
the laser, determine the amount of modulating current needed from the laser
manufacturer’s data sheets and use the following calculations:
RF Voltage = (Laser Diode Modulating Current) x 50 Ω
It is strongly recommended that you start off conservatively by a factor of 10
below the calculated modulating voltage and slowly bring the RF power up until
the desired depth of modulation is reached.
Use the laser controller to establish the DC operating point of the laser.
WARNING
The RF input is directly coupled to the laser. Any excessive transients or noise
will be coupled into the laser and may cause the laser to be overdriven. Also,
the laser can be easily overdriven if excessive RF power is applied to this input.
Use the RF modulation input with care to avoid damaging your laser or mount.

LDM9T Chapter 5: Operation
Page 10 15827-D02
5.3. Status and Interlocks
This unit is equipped with a remote interlock circuit, a temperature lockout
interlock circuit and an LED that indicates if the laser diode is enabled. All three
circuits are designed to interface with Thorlabs’ laser and TEC controllers with no
external circuitry. These circuits do not directly interface with the laser diode
control lines. They are meant to provide a fault to the laser diode controller,
which will then safely shut down laser diode operations.
If third-party controllers are used to drive the laser diode, these features may not
be used. In this case the onboard interlocking features will not be active and the
laser controllers interlocking features must be implemented to provide the
required safety protocols. Below is a schematic of the interlock feature.
Figure 5 Interlock Connection Schematic
If you wish to make full use of all of the Status and Interlock features with your
third-party drivers, please contact Thorlabs and an engineer will help you
determine if this is possible and how to implement these features.
5.4. Active Cooling System
The LDM9T incorporates a fan in the heat sink to improve the heating/cooling
capacity of the mount. The fan speed is actively controlled to provide the best
overall performance when high power loads are installed and to keep noise and
vibration to a minimum when light loads are applied. Do not block the fan or
prevent it from spinning. This will cause the mount to possibly overheat and go
into a thermal runaway condition.

LDM9T Chapter 5: Operation
Rev G, Jan 22, 2017 Page 11
5.5. Safe Operating Area (SOA)
The safe operating area for the mount is basically the area at which the thermal
power of the laser diode can be removed and dissipated by the LDM9T. How
much power the mount can dissipate depends on a number of factors, ambient
temperature and set point temperature being the most important. The graph
below can be used to determine how much power the mount can efficiently
remove and maintained proper stabilization. Most low and medium power laser
diodes will fall within this curve.
To calculate the thermal power of the installed laser diode two factors need to be
known, forward operating voltage (VF) and the operating current (Iop). Both are
typically published in all laser diode spec sheets.
 󰇛󰇜
Blue and violet laser diodes tend to have much higher forward voltage drops
meaning they produce more thermal power that needs to be dissipated than a
standard laser diode.
Figure 6 Power Dissipation vs. Ambient Temperature

LDM9T Chapter 5: Operation
Page 12 15827-D02
5.6. Maintaining the LDM9T
There are no serviceable parts in the LDM9T. The housing may be cleaned by
wiping with a soft, damp cloth. If you suspect a problem with your LDM9T, please
call Thorlabs and an engineer will be happy to assist you.

LDM9T Chapter 6: Making Safety Interlock Connections
Rev G, Jan 22, 2017 Page 13
Making Safety Interlock Connections
The LDM9T is equipped with a Remote Interlock connector located on the side
panel. In order to enable the laser source, a short circuit must be applied across
the terminals of the Remote Interlock Connector. In practice this connection is
made available to allow the user to connect a remote actuated switch to the
connector (i.e., an open door indicator). The switch, which must be normally
open, has to be closed in order for the unit to be enabled. Once the switch is in
an open state, the laser diode must automatically shut down.
All units shipped from Thorlabs are configured with a shorting device installed in
the interlock connector. If you are not going to use this feature, then you can
leave the shorting device installed and the unit will operate normally as described
in the procedures in this manual. If you wish to make use of the interlock feature,
you will need to acquire the appropriate connector mate and wire it to your
remote interlock switch. Next, remove the shorting device by unscrewing it from
the input and install the connector into the interlock input.
The interlock feature does not directly control the laser connections. It only
affects the interlock lines on pins 1 and 5 for the laser controller connection. An
appropriate laser controller with interlocking support must be used for this feature
to operate.
The interlock input only accepts a 2.5 mm mono phono jack. This connector is
readily available at most electronics stores (Radio Shack, Digikey, Mouser,
Allied, etc.).
The electrical specifications for the interlock input are as follows:
Specification
Value
Type of Mating
Connector
2.5 mm Mono Phono Jack
Open Circuit Voltage
+5 VDC with Respect to Chassis Ground
Short Circuit Current
~8 mA DC
Connector Polarity
Tip is +5 V, Barrel is Ground
Interlock Switch
Requirements
Must be N.O. Dry Contacts. Under no
circumstances should any external
voltages be applied to the Interlock Input
Figure 7 Remote Interlock Connector

LDM9T Chapter 7: Trouble Shooting
Page 14 15827-D02
Trouble Shooting
Laser Driver Will Not Enable
If you are using Thorlabs’ Laser controller with your LDM9T:
Possible Solution
Directions
Remote interlock is
open
Make sure that either the shorting device is installed in the
REMOTE INTRLK connector on the side of the LDM9T. If
you have a remote interlock switch connected to this
REMOTE INTRLK connector, it must be in a closed
position.
The LDM9T is powered
off
The power must be enabled to allow the laser to operate.
The power is only supplied to operate the TEC controller,
however an internal TEC Lockout will prevent the laser
diode form operating when there is no active TEC control.
Laser Wavelength or Power is Unstable
Possible Solution
Directions
LD is not fully seated
Make sure your laser diode is fully inserted into the LDM9T
laser socket and its body is in full contact with the copper
cold plate.
LD is mode hopping
The laser diode may be operating on a mode transition. Try
adjusting the temperature to shift the laser diode to a more
stable operating point.
Mount is set outside
safe operation area
Verify the thermal power of the laser diode is operating
within the SOA as described in Section 5.5, page 11.
The LDC Series Laser Driver Indicates an “Open Circuit” Alarm When You
Try to Enable the Laser
Possible Solution
Directions
LD and PD polarity
switch settings are
incorrect
Refer to Figure 2 on page 5 and the data sheet for your
specific diode to ensure the proper settings. The LD polarity
switch setting on the mount must match the LD polarity
switch setting on the rear panel of your LDC series laser
diode controller.
LD orientation may be
incorrect in the socket
Refer to Figure 2 on page 5 and the laser diode data sheet
for you specific diode to ensure proper orientation.
If you still have problems or questions regarding the operation of your LDM9T,
please feel free to call Thorlabs and ask for Technical Support.

LDM9T Chapter 8: Specifications
Rev G, Jan 22, 2017 Page 15
Specifications
Performance Specifications
Lasers Supported
Ø5.6 mm and Ø9 mm Laser Diodes
Max Laser Current
200 mA (Tambient = 25 °C, VLD = 3 V)
Laser Diode Compliance Voltage
7.5 V
Laser Pin Configurations
All LD Packages Except Style “F”
LDC Modulation Frequency
DC to 200 kHz
RF Modulation Frequency1
200 kHz to 1 GHz
RF Input Impedance
50 Ω
Maximum RF Power
250 mW
Maximum TEC Current
1 A (Internally Regulated)
TEC Heating/Cooling Capacity
0.5 W (Tambient = 25 °C, TLD = 20 °C)
See SOA Curve, page 12
Typical Temperature Range
20 to 30 °C
Temperature Stability
<0.02 °C (1 hour)
<0.05 °C (24 hour)
Typical Settling Time
<2 min heating, <3 min cooling
Temperature Sensors
10 kΩ Thermistor ±2% @ 25 °C, NTC
Operating Temperature
10 to 30 °C
Storage Temperature
-20 to 70 °C
Power Supply Specifications
TEC Power Supply
Desktop Switching Supply
Supply Input
12 W
Supply Voltage Output
5 VDC
1
Modulate Low Frequencies Through LD Controller

LDM9T Chapter 8: Specifications
Page 16 15827-D02
Physical Specifications
Laser Polarity Select
Internal Slide Switches
Laser Interface
DB9 Female
Power Supply Connector
2.5 mm Power Jack
RF Input Connector
SMA Jack
Interlock Connector
2.5 mm Phono Jack
Indicators
LD Enabled, Power On Green LED
Size (L x W x H)
3.09" x 2.89" x 1.79"
(78.4 mm x 73.3 mm x 45.5 mm)
Weight
0.56 lbs (1.55 lbs ship weight)
Mounting Threads
3x #8-32 (3x M4-0.7 for LDM9T/M)

LDM9T Chapter 8: Specifications
Rev G, Jan 22, 2017 Page 17
Typical Temperature Response Times
Figure 8 Typical Heating Response
Figure 9 Typical Cooling Response

LDM9T Chapter 8: Specifications
Page 18 15827-D02
RF Modulation
RF modulation can be accomplished in one of two ways. For low frequencies
(below ~200 kHz), the RF modulator should be connected to the LD controller.
Figure 10 shows the performance using the LDC202C. Above 200 kHz, the
modulator should be connected to the mount’s SMA connector. The mount has
been tested up to 1 GHz, (see Figure 11 below).
Figure 10 Low Frequency Modulation Through LD Controller
Figure 11 RF Modulation Through SMA Connector on LM9LP