Micro-mirror array for multi-object spectroscopy in cryogenic environment

Next-generation infra-red astronomical instrumentation for space and ground-based telescopes requires MOEMS-based programmable slit masks for multi-object spectroscopy (MOS) usable in a cryogenic environment. A 100x200 mum2 micro-mirror array was successfully designed, fabricated and tested, with tilting angle of 20deg at 100 V. In parallel we have developed and implemented a high-resolution Twyman-Green interferometer and a cryo-chamber for full surface and operation characterization. The micromirrors could be successfully actuated before, during and after cryogenic cooling. Surface deformation of gold coated mirrors at 300 K and below 100 K shows a slight increase from 35 nm to 50 nm PtV, still well suited for MOS application.