The optical part of the Raman Laser Spectrometer (RLS) instrument for ExoMars consists of an excitation laser, an optical harness, an optical head and a spectrometre. The optical harness delivers the green radiation generated by the laser to the optical head which, in turn, focuses the laser radiation on the sample of interest and collects the Raman emission from the sample. The optical head then separates excitation light and Raman emission by a filter setup and sends the isolated Raman signal to a reception fiber, which delivers it to the spectrometer of the instrument. This paper concentrates on the innovative technologies applied for the excitation path of the instrument, the laser, the optical harness with its new compact fiber optic connectors and the Raman optical head; and describes their design, the design driving requirements and the status these units have reached by now. The spectrometer of the system with its transmission grating design will be presented separately.
Using fiber optical components and assemblies for space flight applications brings several challenges for the design and the qualification process. Good knowledge of the system and environmental requirements is needed to derive design decisions and select suitable components for the fiber optical subsystem. Furthermore, the manufacturing process and integration limitations are providing additional constraints, which have to be considered at the beginning of the design phase. Besides Commercial off the shelf (COTS) components, custom made parts are often necessary.
The Meteosat Third Generation (MTG) program will ensure the continuity and enhancement of meteorological data from geostationary orbit as currently provided by the Meteosat Second Generation (MSG) system. OHB-Munich, as part of the core team consortium of the industrial prime contractor for the space segment Thales Alenia Space (France), is responsible for the Flexible Combined Imager – Telescope Assembly (FCI-TA) as well as the Infrared Sounder (IRS).
Gary L. Peterson (Breault Research Organization) presented a simple analytical model for in- field stray light evaluation
of axial optical systems. We exploited this idea for more complex optical instruments of the Meteosat Third Generation
(MTG) mission. For the Flexible Combined Imager (FCI) we evaluated the in-field stray light of its three-mirroranastigmat
telescope, while for the Infrared Sounder (IRS) we performed an end-to-end analysis including the front
telescope, interferometer and back telescope assembly and the cold optics. A comparison to simulations will be
presented. The authors acknowledge the support by ESA and Thales Alenia Space through the MTG satellites program.