PROPERTIES OF INDIUM-ANTIMONIDE DETECTORS FOR USE AS TRANSFER STANDARDS FOR DETECTOR CALIBRATIONS

The properties of 4-mm-diameter and 7-mm-diameter liquid-nitrogen-cool ed indium antimonide detectors were investigated to determine their su itability as transfer standards (i.e., reference detectors) for the de tector calibration facility at the National Research Council of Canada . The spectral responsivity of the InSb detectors in the spectral rang e 1000-3000 nm was determined by a two-step procedure involving the us e of germanium transfer standards and suitably characterized thermopil es. It is shown that the long-term reproducibility of the InSb detecto r calibrations is approximately +/-1%. The uniformity and linearity as a function of wavelength, as well as the background current noise and drift of the two detectors, are compared. It is shown that the 7-mm-d iameter detector is clearly superior to the 4-mm one for use as a tran sfer standard. It is estimated that the overall accuracy of the calibr ations of the two InSb detectors is +/-2% in the range 1200-2800 nm. ( C) 1998 Optical Society of America.