Development of digital micromirror devices (DMDs) for far-UV applications

Digital micromirror devices (DMDs) can be used as rapidly reconfigurable "slit mask" object-selectors in space- based UV multi-object spectrometers (MOS). There are several missions currently in the planning process, which are developing concepts for multi-object spectrometers. For example, both LUVOIR and HabEx plan to include such an instrument, working into the deep UV. Currently, DMDs are the only alternative technology to microshutter arrays, which were developed for the infrared MOS on the James Webb Space Telescope. However, the deep UV (100 - 300 nm) reflectivity of DMDs needs to be substantially higher for efficient mission operation. We have re-coated commercially available DMDs (which use aluminum alloy mirrors) with high reflectivity aluminum, which is protected from oxidation by a AlF3 overcoat. We found that DMDs remain functional after being re-coated and show a dramatic reflectance improvement in the region of 100 - 300 nm. The scattering properties of re-coated DMDs can be further improved by masking the gaps between individual micromirrors during the coating process.