Compact high-resolution imaging spectrometer (CHRIS) design and performance

Abstract

This paper describes a Compact High Resolution Imaging Spectrometer (CHRIS) developed at Sira. The imaging spectrometer is flying on PROBA, a small agile satellite, which was launch in 2001. This paper provides details of the instrument design and performance. The main purpose of the instrument is to provide images of land areas, particularly the measurement of the Bi-directional Reflectance Distribution Function (BRDF) properties for selected targets on the Earth surface using multi-angle observations. The platform provides pointing in both across-track and along-track directions, for target acquisition, BRDF and aerosol measurements and slow pitch during imaging in order to increase the integration time of the instrument. This increase in integration time enhances the target radiometric resolution. The spectral range covered by the instrument extends from 400nm to 1050nm. The platform orbits the Earth with an apogee of 673km and a perigee of 560km. The spatial sampling interval at apogee is approximately 17m. In this mode it is possible to readout 19 spectral bands. The location and width of the spectral bands are programmable. Selectable on-chip integration can increase the number of bands to 63 for a spatial sampling interval of 34m. The swath width imaged is 13km at perigee.