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C-Mount Laser Mount with Temperature Stabilization

  • Laser Mount for C-Mount Semiconductor Lasers
  • TEC Cooled with Temperature Stabilization for >20 W of Heat Dissipation
  • SM1, 30 mm & 60 mm Cage System, and 1/4"-20 (M6) Post Compatible


Application Idea

LDMC20 with C-Mount Laser and C037TME-E Lens in a S1TM09 Adapter

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Figure 1: LDMC20's Mounting Platform and Copper Heat Sink
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Figure 2: Side View of the LDMC20


  • Laser Mount for C-Mount Semiconductor Lasers
  • Integrated TEC Element for Active Temperature Control when Used with Our QCL Controllers
  • Provides >20 W of Heat Dissipation at 25 °C
  • Supports Single-Tab and Dual-Tab C-Mount Laser Configurations (See the Specs Tab for Details)
  • 30 mm and 60 mm Cage System Compatible
  • SM1 Threaded for Aspheric Lens Adapters, Fiber Adapters, and Ø1" Lens Tubes
  • Six 1/4"-20 (M6) Tapped Holes for Easy Post Mounting
  • Includes Current and TEC Cables for QCL Controllers and External Power Supply for Fan

Thorlabs' LDMC20(/M) C-Mount Laser Mount is designed to work with our line of Fabry-Perot (FP) and Distributed Feedback (DFB) C-mount semiconductor lasers. Internal electronics provide active temperature stabilization capable of dissipating heat loads of at least 20 W at 25 °C, making this mount ideal for temperature-controlled operation of C-mount lasers. The C-mount laser is mounted against a copper heat sink and held in place by a cap screw included with the mount (see the Installation tab for assembly instructions). The LDMC20(/M) is compatible with select single-tab and dual-tab laser configurations; please refer to the Specs tab for diagrams of compatible C-mount devices.

A TEC control circuit provides a stable temperature environment for the laser and the mount is air cooled, utilizing an automatic fan speed control to actively cool the heat sink. The fan is vibrationally isolated and designed to run only as needed for temperature stabilization so as to minimize vibrational coupling. When combined with proper current control, the mount can be used to stabilize or tune the laser's wavelength. The fan can be run via an external power supply (included with the mount) if the TEC driver being utilized cannot supply power to the fan.

The laser is held in the mount such that the emission facet is nominally centered in the SM1-threaded (1.035"-40) port. This port is intended for mounting aspheric lenses for collimation purposes, using the proper adapter and lens. Z translation is achieved by rotating the adapter in the SM1 port with a spanner wrench. A pair of knurled knobs provides fine X-Y translation of this port so that the emitted laser beam can be precisely centered within it. This makes centering the laser beam onto collimating optics quick and easy. The translation is accomplished through the utilization of a flexure design. The front cover plate of the LDMC20 is equipped with eight 4-40 tapped holes for our 30 mm or 60 mm cage systems.

Laser protection features include optional grounding configurations, and the TEC Lockout circuit* that prevents enabling the laser unless the TEC controller is active. The built-in thermoelectric cooler enables temperature-controlled operation of the laser diode.

*TEC Lockout only functions with Thorlabs' current and temperature controllers and can be easily bypassed if not required.

Recommended Current and Temperature Controllers
For temperature and current control, we recommend using this mount with the ITC4002QCL or ITC4005QCL dual current and temperature controllers. These controllers are designed with high compliance voltages of 17 V or 20 V, respectively, and maximum operating currents of 2 A or 5 A, respectively, to support our MIR C-mount lasers.

The LDMC20 mount ships with current and TEC cables that are compatible with all of our LDC current controllers and ITC dual current and temperature controllers, including the ITC4002QCL and ITC4005QCL.

Handling C-Mount Lasers
Proper precautions must be taken when handling and using C-mount lasers. Since these lasers are sensitive to electrostatic shock, they should always be handled using standard static-avoidance practices. Additionally, these lasers do not have a built-in monitor photodiode and should be used with a high-quality, constant current driver specifically designed for use with laser diodes.

Unlike TO can and butterfly packages, the laser chip of a C-mount laser is exposed to air; hence, there is no protection for the delicate laser chip. Contamination of the laser facets must be avoided. Do not blow on the laser or expose it to smoke, dust, oils, thermal grease, or adhesive films. The laser facet is particularly sensitive to dust accumulation. Do not use thermal grease with this package, as it can creep, eventually contaminating the laser facet. Acceptable alternatives to thermal grease include pyrolytic graphite and solder.

LDMC20 Specifications
Supported Laser Diode Packagesa Single-Tab C-Mount
Dual-Tab C-Mount
Laser Current (Max) 20 A
TEC Current (Max)b 11.1 A
TEC Voltage (Max) 14.5 V
Heat Dissipation Capacityc >20 W at 25° C
X-Y Translation Range ±1.0 mm
X-Y Translation Resolution 250 µm/rev
Center Threads SM1 (1.035"-40) Threads
0.535" (13.5 mm) Deep
Temperature Sensorsd 10 kΩ ± 2.2% Thermistor @ 25 °C
β = 3984
Operating Temperature
10 to 40 °C (Non-Condensing)
Electrical and Physical Specifications
Laser Interface 7W2 Mixed Female D-Sub Jack
TEC Interface 7W2 Mixed Male D-Sub Jack
Fan Input 12 VDC, 500 mA
Power Supply Connector 2.1 mm Power Jack
Interlock Connector 2.5 mm Phono Jack
Indicators Green LED when Laser Enabled
Size (L × W × D) 4.00" × 4.00" × 4.05"
(101.6 mm × 101.6 mm × 102.9 mm)
Weight 1543 g (3.4 lbs)
  • Only select configurations of single-tab or dual-tab C-mount lasers are supported. Please refer to the diagrams below to determine if your laser is supported.
  • When using the LDMC20 with the ITC4005QCL controller, the mount will typically draw 8 A.
  • See the Graphs tab for sample measurements of the heat dissipation at other temperatures.
  • We recommend setting the temperature sensor to "Thermistor (low)" when operating with Thorlabs ITC series controllers.
Engraved Back of OAP
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LDMC20 Mechanical Drawing

Supported C-Mount Laser Configurations

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Incompatible C-Mount Laser Configurations

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The graph above shows the heat dissipation of the LDMC20 with the fan turned off. Data was taken at three different ambient temperatures.
Engraved Back of OAP
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The graph above shows the heat dissipation of the LDMC20 with the fan turned on. Data was taken at three different ambient temperatures.
Engraved Back of OAP
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The graph above shows the resistance value of the LDMC20's thermistor as a function of temperature. For this thermistor, β = 3984.
Engraved Back of OAP
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Figure 1: To begin installation, use a balldriver to remove the four socket head screws from the front face. The LDMC20 utilizes 6-32 screws, which can be removed using the included 7/64" hex key, whereas the LDMC20/M has 2-56 screws and uses the included 5/64" hex key.
Engraved Back of OAP
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Figure 2: Carefully insert the C-Mount laser into position within the mount. Using a 5/64" balldriver, secure the laser with the 2-56 socket head screw. 
Engraved Back of OAP
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Figure 3: The black plastic brackets seen above are used to ensure proper electrical contact between the C-Mount's tabs and the LDMC20. Using a 3/32" balldriver, tighten the two 4-40 socket head screws until the tabs are held securely against the small copper blocks. These screws only need to be snug. Do not overtighten as it can cause damage to the mount or laser. For single-tab C-Mount lasers, the included 4-40 screw and washer needs to be set into either the "Anode To Body" or "Cathode To Body" location (dependent on laser configuration) indicated by the red circles.
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Figure 4: Replace the front face of the mount.
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Figure 5: Install the desired lens and adapter. This image shows the LDMC20 with a C037TME-E aspheric lens with an S1TM09 aspheric lens adapter. The SPW909 can be used to insert the adapter into the SM1-threaded port. This port is intended for mounting aspheric lenses for collimation purposes, using the proper adapter and lens. A pair of knurled knobs provides fine XY translation of the port so that the beam can be precisely centered, while Z translation is achieved by rotating the adapter in the SM1 port with the spanner wrench. For optimization in Z, rotate the assembly by 1/4 or 1/2 turn at a time, and then check the beam quality (preferably by using a camera) some distance away from the LDMC20(/M).
Caution: Optimization in Z should be done with care. Over-rotating the assembly may cause contact between the lens assembly and the C-mount laser, which can result in damage, especially if the laser is operating. Please refer to Section 5.6 in the manual for more information.

Laser Pin Connections

7W2 Mixed Female D-Sub Jack

Connector Drawing

A1 Laser Cathode 3 Not Connected
A2 Laser Anode 4 Laser Voltage (Anode)
1 Interlock and Status Return 5 Laser Voltage (Cathode)
2 Interlock and Status Pin

TEC Pin Connections

7W2 Mixed Male D-Sub Jack

Connector Drawing

A1 TEC (+) 3 Fan Power
A2 TEC (-) 4 TEC Lockout (+)
1 Thermistor (+) 5 Ground
2 Thermistor (-)

Posted Comments:
lukas.perner  (posted 2018-06-23 16:17:37.923)
Just a remark on the Imperial C-Mount laser mount: Mounting to any base, e.g. kinetic or magnetic, or even a ball-bearing stage, would be a lot easier if the spacing of the outside 1/4"-20 threads on the side would be 1.00" instead of 1.05". Construction-wise this can't be a problem, as the metric ones have a 25.0mm spacing for their respective threads (being M6 on them). This change would result in a far better compatibility with ThorLabs mountig options as the standard spacing of breadboards, stages, mounts etc. is 1".
YLohia  (posted 2018-06-25 12:23:11.0)
Hello, thank you for your valuable feedback. I have posted this on our internal engineering forum for further consideration.
user  (posted 2018-05-06 15:05:23.557)
Does the integrated LDMXY make this product suitable for vertical mounting using the 60 mm cage system or will the weight (heat sink etc.) press the slip plate against the xy-positioner and prevent the latter from being moved with the screws?
YLohia  (posted 2018-05-07 04:26:46.0)
Hello, thank you for contacting Thorlabs. The integrated LDMXY is suitable for vertical mounting using the cage system. The screws are as adjustable in this configuration as they are in a typical post-mounted configuration.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
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