Slitfunction measurement optical stimulus
article
For the calibration of OMI (= Ozone Monitoring Instrument, to be launched in 2004 on the NASA EOS-AURA satellite) a slitfunction measurement stimulus has been developed. The slitfunction is the monochromatic image of the entrance slit of the spectrometer on the detector. Accurate knowledge of this slitfunction for all wavelengths and field angles is very important both for the spectral calibration and for the DOAS (= Differential Optical Absorbtion Spectroscopy) retrieval algorithm. Determination of this function with a spectral line source is inaccurate, because of the detector resolution and incomplete, because of the limited number of discrete spectral lines, that are available. For accurate and complete measurement of the slitfunction an echelle monochromator has been developed, that offers a number of spectral lines, that can be scanned with a small wavelength step over the entire spectral range of OMI (270 - 500 nm). The spectral bandwidth of these lines (FWHM) is about 0.1 x the spectral resolution of OMI and the wavelength step during scanning is even smaller. The wavelength scanning is performed by accurate rotation of the echelle. In this paper the scientific background of the slitfunction measurement, the stimulus and first OMI slitfunction calibration measurements are described.
TNO Identifier
953639
ISSN
0277786X
Source
Proceedings of SPIE - The International Society for Optical Engineering, 4881, pp. 511-520.
Publisher
SPIE
Pages
511-520
Files
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