Full-SiC derotator optics for METimage: preliminary design and verification approach

Abstract

METimage is an advanced multispectral radiometer for weather and climate forecasting developed by Airbus Defence & Space under the auspices of the German Space Administration (DLR) for the EUMETSAT Polar System-Second Generation (EPS-SG). The instrument is equipped with a continuously rotating scan mirror with a 1.7s period followed by a static telescope. The scan mirror permits an extended Earth view of 108° per revolution and regular views to on-board calibration sources. A derotator assembly, which is half-speed synchronised with the scanner, is inserted in the optical beam after the telescope to compensate the image rotation in the focal plane. The derotator optical arrangement is a fivemirror concept that minimises the polarisation sensitivity. The derotator design is constrained by optical performance, mass and compactness, which led to the selection of a full silicon carbide (SiC) concept. This paper describes the preliminary design and verification approach of the derotator optics.

Full-SiC derotator optics for METimage: detailed design and early model results

“…A discussion of the AIV activities and GSE was presented in [4]. The AIV sequence is recalled in the following chart for reference.…”

METimage instrument development status

“…The interface between mechanism and optics is realized by an Invar ring for CTE matching. The derotator optics is realized by of a system of 5 planar mirrors to minimize the polarization impact [2]. The mirrors as well as the baseplate are realized in SiC technology to secure the demanding stability requirements.…”