26 September 2007 Reconfigurable mask for adaptive coded aperture imaging (ACAI) based on an addressable MOEMS microshutter array
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Coded aperture imaging has been used for astronomical applications for several years. Typical implementations use a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. More recent applications have emerged in the visible and infra red bands for low cost lens-less imaging systems. System studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. We report on work to develop a novel, reconfigurable mask based on micro-opto-electro-mechanical systems (MOEMS) technology employing interference effects to modulate incident light in the mid-IR band (3-5μm). This is achieved by tuning a large array of asymmetric Fabry-Perot cavities by applying an electrostatic force to adjust the gap between a moveable upper polysilicon mirror plate supported on suspensions and underlying fixed (electrode) layers on a silicon substrate. A key advantage of the modulator technology developed is that it is transmissive and high speed (e.g. 100kHz) - allowing simpler imaging system configurations. It is also realised using a modified standard polysilicon surface micromachining process (i.e. MUMPS-like) that is widely available and hence should have a low production cost in volume. We have developed designs capable of operating across the entire mid-IR band with peak transmissions approaching 100% and high contrast. By using a pixelated array of small mirrors, a large area device comprising individually addressable elements may be realised that allows reconfiguring of the whole mask at speeds in excess of video frame rates.
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Mark E. McNie, Mark E. McNie, David J. Combes, David J. Combes, Gilbert W. Smith, Gilbert W. Smith, Nicola Price, Nicola Price, Kevin D. Ridley, Kevin D. Ridley, Keith L. Lewis, Keith L. Lewis, Chris W. Slinger, Chris W. Slinger, Stanley Rogers, Stanley Rogers, } "Reconfigurable mask for adaptive coded aperture imaging (ACAI) based on an addressable MOEMS microshutter array", Proc. SPIE 6714, Adaptive Coded Aperture Imaging and Non-Imaging Sensors, 67140B (26 September 2007); doi: 10.1117/12.735894; https://doi.org/10.1117/12.735894

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