Integration And Testing Of An Imaging Spectrometer For Earth Observation

The DLR Earth Sensing Imaging Spectrometer (DESIS) is a space-based hyperspectral instrument developed by Deutsches Zentrum fur Luft- und Raumfahrt (DLR). The optical system of the spectrometer was fabricated and pre-aligned by the Fraunhofer-Institut fur Angewandte Optik und Feinmechanik (IOF).The paper describes the manufacturing, integration, and testing of this optical system. It was realized as an all reflective system using metal-based mirrors and a modular, so-called snap-together approach, which allows to simplify the integration of optical systems considerably. Measured r.m.s. wavefront errors of the complete system are in the range of 63 nm to 120 nm, which is compliant with the instrument's requirements.