DETERMINING BANDPASS FUNCTIONS IN ARRAY SPECTRORADIOMETERS

摘要

The bandpass of scanning spectroradiometers is easily determined and recent advances in correction techniques make the correction of spectra straight forward. Array spectroradiometers have their own unique problems in the determination of bandpass and then in the correction of spectra. Each pixel corresponds to a wavelength but intervals are not equal. Moreover, the bandpass shape varies considerably with wavelength. So, rather than a measurement being made with constant triangular bandpass at even wavelength intervals, the array spectroradiometer gives a measurement with variable bandpass shape and wavelength interval. Methods for determining the bandpass are described and compared. The indirect method is shown to be equivalent to the direct method and the Ohno-Young algorithm provides an excellent fit to the bandpass function. Bandpass shapes with respect to wavelength are determined for real instruments and a measurement of a LED is corrected using the derivative method and interpolated bandpass functions for each pixel.