Improved spectral radiance responsivity calibration of charge-coupled-device (CCD) imaging spectrometer with an internally illuminated integrating sphere

A technique for calibrating the spectral radiance responsivity of the CCD imaging spectrometer with an internally illuminated integrating sphere is described. The spectral radiance of the integrating sphere is obtained by two steps. Firstly, a Spectralon panel diffuser and an ultraviolet spectrometer are combined into a new spectral radiometer which transfers the spectral irradiance of a NIST standard of spectral irradiance to that of the receiving aperture of the integrating sphere. Subsequently, the spectral radiance of the integrating sphere is derived from heat transfer theory for Lambertian radiators. The overall uncertainty of determining the spectral radiance of the integrating sphere is ±2.3%. On the basis of known spectral radiance, the radiance calibration of an available Czerny-Turner imaging spectrometer in our laboratory has been completed in 200-400nm with an uncertainty of about ±2.7%.