Optical MEMS for space spectro-imagers

Abstract

In addition to their compactness, scalability and specific task customization, optical MEMS could generate new functions not available with current technologies and are thus candidates for the design of future space instruments. Most mature components for space applications are the Digital Mirror Device (DMD) from Texas Instruments (TI), the micro-deformable mirrors, the Programmable Micro Diffraction Grating and the tiltable micro-mirrors. Among 20-30 MEMS-based payloads concepts, two concepts are selected. The first concept is a programmable slit for straylight control for space spectro-imagers. This instrument is a push-broom spectro-imager for which some images cannot be exploited because of bright sources in the field-of-view. The proposed concept consists in replacing the current entrance spectrometer slit by an active row of micro-mirrors. The MEMS will permit to dynamically remove the bright sources and then to obtain a field-of-view with an optically enhanced signal-to-noise ratio. The second concept is a push-broom imager for which the acquired spectrum can be tuned by optical MEMS. This system is composed of two diffractive elements and a TI’s DMD component. The first diffractive element spreads the spectrum. A micro-mirror array is set at the location of the spectral focal plane. By putting the micro-mirrors ON or OFF, we can select parts of field-of-view or spectrum. The second diffractive element then recombines the light on a push-broom detector. Dichroics filters, strip filter, band-pass filter could be replaced by a unique instrument.