Research On The Measurement Techniques Of Detector Spectral Response Based On Cryogenic Radiometer

Cryogenic radiometer, acknowledged the most accurate method in optic radiation measurement techniques in the world, has become the emphasis of research in most of national metrology institutes (NMIs). Nowadays, the development of cryogenic radiometer mainly includes improving the measuring accuracy of cryogenic radiometer, and expanding the measurement range. Meanwhile, the correlative characters of trap detector and transfer standard detector also become the focus of research as the main means for maintaining and disseminating the values.The window transmittance and the cavity absorbance of cryogenic radiometer are significant correction factors and components of uncertainty. It is necessary to study the relevant features to improve the measurement accuracy. In order to know the exact cavity absorbance, we designed an integrating sphere which can be used in different ways. The simulation cavity at633nm is measured, and the combined standard uncertainty is1×10﹣5. In addition, we designed a special device to investigate the influence of vacuum on the transmittance of Brewster window. The results indicate that the difference of the transmittance between measuring in the air and vacuum is1×10-5. It is also verified the accuracy of the measurement of transmittance in the air.A series of special experiments are applied to investigate the parameters of trap detectors including:spatial uniformity, polarization character, angular variation and integrated factors. The effect on quantity transfer process and application range have been obtained.At1310nm wavelength, we have studied two kinds of reference detectors which are used for standard and calibration of fiber optic power meters, including spatial uniformity, angular variation and the effect between parallel light and diverging light. The first type is a10mm diameter single InGaAs photodiode. In the second type, a3mm diameter InGaAs photodiode is fitted into a50.8mm diameter integrating sphere. A plane window suitable for infrared window transmittance measurement is designed, whose window direction perpendicular to the incident beam. The result indicates that infrared window transmittance measurement method is feasible and the measurement error is within the uncertainty limits.