Novel Hadamard transform spectrometer realized using a dynamically driven micromirror array as a light modulator

Hanf, Marian; Schaporin, Alexey V.; Hahn, Ramon; Doetzel, Wolfram; Geßner, Thomas

doi:10.1117/12.590335

Cited by 2 publications

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Full-frame programmable spectral filters based on micromirror arrays

Love

Graff

2014

J. Micro/Nanolith. MEMS MOEMS

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Rapidly programmable micromirror arrays, such as the Texas Instruments Digital Light Processor (DLP ® ) digital micromirror device (DMD), have opened an exciting new arena in spectral imaging: rapidly reprogrammable, high spectral resolution, multiband spectral filters that perform spectral processing directly in the optical hardware. Such a device is created by placing a DMD at the spectral plane of an imaging spectrometer and by using it as a spectral selector that passes some wavelengths down the optical train to the final image and rejects others. Although simple in concept, realizing a truly practical DMD-based spectral filter has proved challenging. Versions described to date have been limited by the intertwining of image position and spectral propagation direction common to most imaging spectrometers, reducing these instruments to line-by-line scanning imagers rather than true spectral cameras that collect entire two-dimensional (2-D) images at once. Here, we report several optical innovations that overcome this limitation and allow us to construct full-frame programmable filters that spectrally manipulate every pixel, simultaneously and without spectral shifts, across a full 2-D image. So far, our prototype, which can be programmed either as a matched-filter imager for specific target materials or as a fully hyperspectral multiplexing Hadamard transform imager, has demonstrated over 100 programmable spectral bands while maintaining good spatial image quality. We discuss how diffraction-mediated trades between spatial and spectral resolution determine achievable performance. Finally, we describe methods for dealing with the DLP's 2-D diffractive effects and suggest a simple modification to the DLPs that would eliminate their impact for this application. Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micromirror arrays Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Love and Graff: Full-frame programmable spectral filters based on micro...

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Full-frame programmable spectral filters based on micromirror arrays

Love

Graff

2014

J. Micro/Nanolith. MEMS MOEMS

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Programmable matched filter and Hadamard transform hyperspectral imagers based on micromirror arrays

Love

2009

SPIE Proceedings

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Hyperspectral imaging (HSI), in which each pixel contains a high-resolution spectrum, is a powerful teclmique that can remotely detect, identify, and quantify a multitude of materials and chemicals. The advent of addressable micro-mirror arrays (MMAs) makes possible a new class of programmable hyperspectral imagers that can perfonn key spectral processing functions directly in the optical hardware, thus alleviating some ofHSI ' s high computational overhead, as well as offering improved signal-to-noise in certain important regimes (e.g. when using uncooled infrared detectors). We have built and demonstrated a prototype UV-Visible micro-mirror hyperspectral imager that is capable not only of matched filter imaging, but also of full hyperspectral imagery via the Hadamard transfonn teclmique. With this instrument, one can upload a chemical-specific spectral matched filter directly to the MMA, producing an image showing the location of that chemical without further processing. Target chemicals are changeable nearly instantaneously simply by uploading new matched-filter patterns to the MMA. Alternatively, the MMA can implement Hadamard mask functions, yielding a full-spectrum hyperspectral image upon inverting the transfonn. In either case, the instrument can produce the 2D spatial image either by an internal scan, using the MMA itself, or with a traditional external push-broom scan. The various modes of operation are selectable simply by varying the software driving the MMA. The design and perfonnance of the prototype will be discussed, along with experimental results confmning the signal-to-noise improvement produced by the Hadamard technique in the noisy-detector regime . Requirements for a possible future extension to the long-wave infrared will also be examined.

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Novel Hadamard transform spectrometer realized using a dynamically driven micromirror array as a light modulator

Cited by 2 publications

References 1 publication

Full-frame programmable spectral filters based on micromirror arrays

Full-frame programmable spectral filters based on micromirror arrays

Programmable matched filter and Hadamard transform hyperspectral imagers based on micromirror arrays

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