Front-window replacement and performance characterization of a commercial digital micro-mirror device for use in the infrared spectrum

In this paper, a validated procedure to replace the protective front-window of a commercial digital micro-mirror device (DMD) from Texas Instruments (TI) to allow its use over a large spectral range is presented. This reworking process was required since the original window employed for encapsulation is made from glass with an anti-reflection coating designed for a specific spectral range, incompatible with the required large spectral range of the demonstrator under development. In addition, a characterisation of the DMD performance in terms of spectral transmission, as well as switching time and pointing stability is presented. The motivation behind this study lies within the development of a novel instrument in the frame of the EU H2020 funded SURPRISE project. The project aims at developing a super-resolved compressive imager operating in the visible-near infrared (VNIR) and mid-wave infrared (MWIR) spectral ranges for space applications, especially targeting Earth Observation. The instrument concept is based on the use of a spatial light modulator (SLM), in this case a digital micromirror device (DMD), as a core element of its architecture to enable data acquisition and compression in single step based on the compressive sensing principle. Even though one of the long-term objectives is to develop a European-based SLM solution, a commercial SLM component has been selected for the demonstrator This allows reducing the development cost and initiating the development of the demonstrator in parallel to the development of a European-based solution.