Design of a spectrometer system for measurements on Earth atmosphere from geostationary orbit

摘要

Remote sensing of a range of pollutants in the lower Earth atmosphere requires high spectral resolution (0. 1nm to 1 nm) and high signal to noise ratios, in UV, visible and near-IR spectral bands. Sensing of large Earth areas from Geostationary orbit (GEO) has critical advantages in monitoring the origins and transport of pollution on hourly time scales. The sensor concept is a pushbroom imaging spectrometer using a common all-mirror telescope with a set of three grating spectrometers and area-array detectors. The challenges in optical design include requirements for excellent colour correction to achieve spatial registration over wide spectral bands, and operation at high relative aperture. These aims are achieved by use of novel spectrometer design concepts, including use of a convex diffraction grating in a concentric configuration. Calibration concepts, including a ratioing technique for absolute measurements, are briefly described.