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10.12.2018 10:42

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Криогенный радиометр CryoRad III



The CryoRad III is the next generation universal cryogenic electrical substitution radiometer, designed for convenient detector calibrations with both laser and lamp or monochromator illumination. Its novel cavity design enables use with beams as fast as f/8 without changing or moving the receiver. Its fast cavity time response removes background drifts and provides noise thresholds below 2 nW, even with an f/8 entrance aperture and viewing an ambient-temperature window. The highest accuracy (< 0.005 %) is achieved in laser beam measurements with a Brewster-angled window. In monochromator measurements, the sensitivity and accuracy are a factor 5 – 10 better than achieved with room temperature ESR’s. CryoRad versions are available optimized for laser, monochromatic, synchrotron, or low-background IR applications. Custom versions have been developed to cover full scale optical power ranges from 100 mW down to 1 nW.


  • Accepts laser, lamp or monochromator sources – no need to change receivers
  • Active receiver response increases measurement speed and helps to remove drift in lamp & monochromator inputs
  • Low-noise AC-bridges for high signal to noise operation
  • Germanium resistance thermometry (GRT) for superior sensitivity
  • LabVIEW based control software via Ethernet interface

Standard Specifications*

Spectral Range 0.20 – 30 µm
Receiver Thermal Response Time (1/e) (1/e) < 8 seconds
Servo Settling Time (to 0.01 % of signal) 40 seconds
Receiver Responsivity 2 ±0.25 K/mW
Minimum Dynamic Range 1µW to 1 mW
Noise (rms for 30 samples over) < 2 nW (varies with operating power)
Absolute Accuracy
Cryostat Dimensions ~30 cm D × ~70 cm (H)
Cavity aperture 6 mm – 8 mm
Cavity operating temperature 4 K – 9 K
Cavity absorptance > 0.9999 (at 632.8 nm)
Initial cool down time 12 hrs
Run Time after cool down Continuous

* nominal values — modifications upon request to meet other requirements