Contamination Control Cover
MIRI incorporates several optical surfaces (mirrors, filters, gratings) which are vulnerable to surface contamination. Potential sources of contamination are: out-gassing of the ISIM during cool down, ISIM decontamination cycles, or unexpected external contamination sources. The CCC is accommodated inside the Optical Bench Assembly (OBA) and located between the Pick-Off Mirror (POM) and the First Fold Mirror along the telescope light path. In case of a potential contamination it shall be closed within 30 seconds to protect the optical surfaces of MIRI against surface layers.
The CCC comprises a light-weight aluminium alloy cover plate that is profiled to provide a face-to-face labyrinth seal when a combined with a static facial plate that is mounted within the optical aperture. The cover plate is mounted on a support frame that merges into two drive arms. The arms are pivoted by double bearings at a common hinge. At each of the drive arms there is an interface with one of the pusher mechanisms. Both mechanisms are fully independent.
Find out more at the Paul Scherrer Institut website: