M5 Detector circuit overlay

M5 Thermopile Detector

A thin film-based thermopile offering very low noise and a small 0.5mm diameter active area in a TO-5 package. This is one of the lowest noise thermopiles you can buy and provides a time constant 28ms time constant with Argon encapsulation gas.

Excellent for non-contact temperature measurement.

Small active area with medium signal-to-noise ratio.


  1. See Standard Windows and Filters (PDF) for list of optical filter options
  2. Internal aperture precisely defines active area for applications with FOV and/or spot size requirements. See Aperture Options (PDF) for available sizes.
  3. See Thermopile Configuration Table for more options.


For more detailed information see the datasheet M5 (PDF).

Specifications apply at 23°C with KBr Window and Argon encapsulating gas.

Parameter Min Typical Max Symbol Units Comments
Active Area size   Ø.5mm Dia.   AA mm Hot junction size, per element.
Element Area   .196   A mm2  
Number of Junctions
10       Per element.
Number of Channels
1       Per detector package.
Output Voltage 22 35 45 Vs μV DC,  H=330μW/cm2 (3)
Signal-to-Noise Ratio 2,716 5,000 7,895 SNR √Hz DC, SNR=Vs/Vn
Responsivity 34.0 54.1 69.6 V/W DC, =Vs/HA  (2)
Resistance 2.0 3.0 4.0 R Detector element
Temperature Coefficient of   -.36     %/°C Best linear fit, 0° to 85°C (1)
Temperature Coefficient of  R   -.2     %/°C Best fit, 0° to 85°C (1)
Noise Voltage 5.7 7.0 8.1 Vn nV/√Hz Vn2=4kTR
Noise Equivalent Power .08 .13 .24 NEP nW/√Hz DC,  NEP= VnHA/Vs (2)
Detectivity 1.9 3.4 5.4 D* 108√Hz/W DC,  D*=Vs/ VnH√A  (2)
Time Constant   28   Τ ms Chopped, -3dB point (1)
Field of View   64°/78°   FOV Degrees See Assembly Drawings for FOV Description.
Package Type   TO-5       Standard package hole size:Ø.080
Operating Temperature -50   100 Ta °C  
General Specifications:

Flat spectral response from 100nm to > 100µm. Linear signal output from 10-6 to 0.1W/cm2. Maximum incident radiance 0.1W/cm2 , damage threshold ≥ .5W/cm2

  1. Parameter is not 100% tested. 90% of all units meet these specifications.
  2. A is detector area in cm2.
  3. Test Conditions: 500K Blackbody source; Detector active surface 10cm from 0.6513cm Diameter Blackbody Aperture.

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