Compact prism spectrometer of pushbroom type for hyperspectral imaging

Abstract

Imaging spectrometers featuring a grating disperser allow for a compact system design. However, due to the limited diffraction efficiency of the grating these instruments suffer from low throughput and high sensitivity to polarization. Prism spectrometers do not have these disadvantages, but they show a low angular dispersion with noticeable non-linearity, which is the main driver of the overall spectrometer dimensions. The envelope of a prism spectrometer can be significantly decreased when prisms with curved surfaces are used. They allow for a reconfiguration of the concentric Offner relay which is well known for its good imaging quality and its low distortion. In the document at hand a novel type of compact Offner spectrometers with curved prisms is presented. As an example the optic design of EnMAP, a German space born hyperspectral imager is given.