Stray light correction for solar measurements using array spectrometers

A stray light matrix correction method for array spectrometers is presented that is specifically tailored for solar spectral measurements. A stray light distribution function based on a single laser line measurement is approximated by an analytical function using three parameters only. This function is the basis for the stray light correction matrix. One cutoff filter is then used to adjust an offset parameter such that stray light corrected data are spectrally flat and around zero below the cutoff wavelength. This parameter also accounts for the IR contribution and has to be adjusted individually for each type of spectrum. A solid validation is given by intercomparison of calibrated solar spectra with a double-monochromator spectroradiometer. An agreement of 5% for wavelengths down to 307 nm and solar zenith angle smaller than 70 degrees is achieved.