Next-generation infrared multi-object spectrographs (MOS) for ground-based and space telescopes could be based on
MOEMS programmable slit masks. This astronomical technique is used extensively to investigate the formation and
evolution of galaxies.
ESA has engaged a study for a technical assessment of using a DMD from Texas Instruments for space applications.
The DMD features 2048 × 1080 mirrors on a 13.68μm pitch, where each mirror can be independently switched between
an ON (+12°) position and an OFF (-12°) position. For MOS applications in space, the device should work in vacuum,
at low temperature, and each MOS exposure would last for typically 1500s with micromirrors held in a static state
(either ON or OFF). A specific thermal/vacuum test chamber has been developed for test conditions down to -40°C at
10-5 mbar vacuum. Imaging capability for resolving each micromirror has also been developed for determining
degradation in any single mirror. Our first tests reveal that the DMD remains fully operational at -40°C and in vacuum.
A 1038 hours life test in space conditions, Total Ionizing Dose radiation, thermal cycling and vibrations/shocks have
also been successfully completed. These results do not reveal any concerns regarding the ability of the DMD to meet
environmental space requirements. Detailed analysis of micromirror throughputs has also been studied for a whole set
of tests, and shows a rather low variation and no impact of the space environment.
We have also developed a bench for MOS demonstration using MOEMS devices. DMD chip has been successfully
tested revealing good contrast values as well as good functionality for applying any mask pattern, demonstrating its full
ability for space instrumentation, especially in multi-object spectroscopy applications.