Comparison experiment of cryogenic radiometer of different calibration optical path

Cryogenic radiometer currently is used as the supreme standard for the measurement of light power, whose accuracy evaluation can be acquired through the results between different cryogenic radiometer equipment. With trap detector serving the transfer standard and the calibration optical path in cryogenic radiometer being distinct, a comparison experiment was carried out between two equipments for the first time in China. The absolute spectral responsivity of transfer standard was calibrated at 633 nm wavelength. The results show that the consistence of absolute spectral responsivity is 3.610-3 and the combined uncertainty is 3.310-4(k=1). It is proved that the two cryogenic radiometer equipments are of high reliability and accuracy.