<title>Utilization of absolute radiometer for calibration of selective detectors</title>

Abstract

A high-precision absolute electrical substitution radiometer with a thermally stabilized cavity as a receiving element was designed at VNIIOFI and used to derive the Russian Special Standard of the solar irradiance. This nonselective radiometer is used in the measuring range from 50 to 2000 W/m<SUP>2</SUP> with uncertainty of 0.1% and from 1 to 50 W/m<SUP>2</SUP> with uncertainty not more than 0.5%. Measurement and data processing in the radiometer are completely automated. The method using this absolute radiometer was realized for calibration of solar cells and other selective detectors. For example we have calibrated different detectors based on photodiodes with filters used for measuring the solar irradiance in spectral regions: 0.29 - 0.34 micrometers , 0.34 - 0.39 micrometers , 0.38 - 1.10 micrometers . This method includes the relative measurements of spectral sensitivity of photodetectors, filters transmittance, spectral irradiance of sources of radiation, and absolute calibration of photodetectors using the absolute radiometer.