Miniature high-resolution imaging system with 3-dimensional MOEMS beam scanning for Mars exploration

A compact confocal imaging instrument is described that makes use of a high-performance bi-axial Silicon torsion mirror, in concert with a reflective dynamic parabolic membrane mirror to provide three-dimensional beam scanning. This beam scan engine is incorporated into a confocal imaging Raman spectrometer under development for exploration of Martian rocks and soil, designed to achieve optical resolution of 1 mum at lambda = 850 nm, with a field of view of 300 mum and focus control of more than 200 mum. Fast x-y beam scanning is achieved with the bi-axial scanner, while the parabolic membrane provides both static and dynamic focus control (z-position) for grass instrument focus as well as on-the-fly field curvature correction or substrate contour tracing. In this paper we describe the MOEM elements as well as the overall instrument architecture. We also present initial imaging results using the torsion mirror scanner, and we describe the dynamic focus element fabrication, modeling and preliminary experimental characterization.