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.

• CryoRad III Radiometers User Manual
• CryoRad III Product Information Sheet