2.3.2 Optical Assembly
The Optical Assembly is the part of the instrument which collects solar radiation as input and generates the spectral information as output. This occurs in the Optical Unit (OU). For maintaining the specified thermal conditions, the OA includes Radiator A and the Thermal Bus Unit. The Optical Unit is organised into two levels. Entrance optics, pre-disperser prism, calibration unit and channels 1 & 2 are contained in level 1 facing in the flight direction (fig. 2-5). Channels 3-8 are located in level 2 (fig. 2-6). All components are mounted onto the OBM which serves as the structural platform and maintains overall alignment between modules. By combining optical components described below, various optical paths (‘trains’) from external and internal light sources to detectors can be established (fig. 2-7).