Spectral method for variable temperature standard blackbody calibration

Variable temperature standard blackbody (VTSBB) is used as the standard radiation source in laboratory to calibrate working blackbodies. Calibration of VTSBB is difficult for higher requirement in emissivity and temperature. Null Balance Radiation Comparator for comparison of two IR-sources is a sensitive system, but the temperature of the source under test must be got first by other methods for emissivity calculation. The extra procedure of temperature test does not satisfy the requirement of calibration accuracy of VTSBB. By using spectral method, the emissivity and the temperature of a VTSBB will be deduced simultaneously from a series of ratios of radiance measurement. Experiment apparatus consists of five parts: IR-spectroradiometer, IR-collimator, slide stage, freezing point blackbodies (FPBB), and VTSBB. FPBB and VTSBB are laid parallel on slide stage to insure the same distances between their apertures to the IR-spectroradiometer. Radiance of two blackbodies is obtained respectively at points of selected wavelength. According to the principle of least square, emissivity and temperature of VTSBB are solutions of two radiation equations. Wavelength ranges of test are 3 mu m to 5 mu m and 8 mu m to 14 mu m. The experiment standard deviations are 0.0013 for emissivity and 0.3K for temperature.