Full-frame programmable spectral filters based on micromirror arrays

Abstract

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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“…Differing from the fixed filter approach, the filter created by the DMD is programmable such that any arbitrary spectral filter can be created. 11 This has been shown to allow two very similar spectrums to be very well separated at presentation speeds up to half the pattern rate of the system. 12 The two spectrums separated and the filter displayed on the DMD are shown in Figure 7.…”

Adaptive hyperspectral imaging with a MEMS-based full-frame programmable spectral filter

“…11 MAHI's programmable spectral filter is based on a new optical design concept that enables the simultaneous spectral filtering of the entire 2-D scene without disturbing the underlying image formed at the camera. The central insight, depicted in Fig.1, is that by moving the dispersive element from its traditional position in a collimated pupil plane to an image plane it becomes possible to isolate the spatial scene information in the spatial domain while the spectral information is encoded into the light field angles (orthogonal to the image).…”

“…11 Based on a new optical design capable of modifying the spectral content of the entire two-dimensional field of view simultaneously, our spectral filter is capable of converting broadband, COTS cameras into spectral cameras. These cameras are capable of rapidly reprogrammable operational modes that include broadband and color imaging, multispectral and hyperspectral imaging and multi-band matched-filter imaging.…”

Digital micromirror device-based ultrafast pulse shaping for femtosecond laser

“…In addition, the DMD typically operates at high frame rates (4-32 kHz) and a broad wavelength range (e.g., from ultraviolet to near infrared) with appropriate coatings. The cost is also relatively low when compared with an LCSLM and an AOM.DMDs have been used in some pulse shaping applications, such as the generation of ultrafast pulse bursts [10], where the DMD was used as a spectrum filter [11]. For phase modulation, spatial beam shaping with a synthetic binary hologram was first demonstrated in 1967 [12].…”

“…DMDs have been used in some pulse shaping applications, such as the generation of ultrafast pulse bursts [10], where the DMD was used as a spectrum filter [11]. For phase modulation, spatial beam shaping with a synthetic binary hologram was first demonstrated in 1967 [12].…”