P/N 202292

THz detector for power measurements up to 25 µW.


Traceable calibration:

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Product family key features

Relative Measurements from 0.1 to 30 THz

Broadband, room temperature operation, easier to use and less expensive than a Golay cell

Wide Dynamic Range from nW to mW

With state of the art pyroelectric sensors, measure down to 50 nW with 1 nW resolution.

Several Sensor Sizes Available

Choice of 5 mm and 9 mm diameter

Calibrated at 0.63 µm

THZ-B detectors are calibrated at a single wavelength (0.63 µm) and include typical wavelength correction data from 0.25 to 440 µm. They are used for relative measurements outside that range.

SDC-500 Optical Chopper

All THZ-B detectors require the use of an optical chopper, like our SDC-500, to sync the signal at either 5 Hz (DA models) or 25 Hz (DZ models).

Compatible stand

Compatible displays & PC interfaces

  • T-Rad-Analog T-Rad-Analog

    Analog (BNC) power module, to interface THZ-B heads with oscilloscopes and lock-in amplifiers.

Measurement capabilities

  • Maximum average power

    25 μW
  • Noise equivalent power

    1 nW
  • Spectral range1

    10 - 3000 μm
  • Frequency2

    0.1 - 30 THz
  • Typical rise time

    0.2 s
  • Typical power sensitivity

    70 kV/W
  • Chopping frequency3

    5 Hz
  • Minimum repetition rate

    1000 Hz
    • 1. Projected spectral range. From 10 to 440 μm, spectrometer measurement. From 440 to 3000 μm, relative measurement only. This spectral range is subject to change.
    • 2. Projected spectral range. From 10 to 440 μm, spectrometer measurement. From 440 to 3000 μm, relative measurement only. This spectral range is subject to change.
    • 3. SDC-500 digital optical chopper sold separately

Damage thresholds

  • Maximum average power density

    0.01 W/cm²

Physical characteristics

  • Aperture diameter

    5 mm
  • Absorber

  • Dimensions

    66.0Ø x 46.5D mm
  • Weight

    0.23 kg



Here is a basic analog set up that would be useful if the optical power of the source was about 5 µW or greater. The output of the THZ5B-BL-DA detector would be approximately 600 mV @ 5 Hz chopping frequency, giving plenty of signal for an oscilloscope. Simply read the voltage output and divide by the Rv factor (V/W) of the detector to measure the intensity of the source in Watts. Also consider applying a wavelength correction factor under certain circumstances.


This is another analog set-up option that we recommend if you have to measure very low power levels (i.e. less than 5 ?W) where the signal may be buried in the broadband noise. The voltage output of the analog THZ-B-DA detector, powered by our T-RAD-ANALOG, is routed to the Lock-In Amplifier input, and the Sync Output of our SDC-500 Chopper is connected to the reference input. The Lock-In Amplifier will lock on the chopping frequency and you can dial in a long integrating time and measure a very low RMS voltage. The voltage divided by our Voltage Responsivity (V/W) equals the power of the source.

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