OPTRA is developing a next-generation digital micromirror device (DMD) based two-band infrared scene projector (IRSP) with infinite bit-depth independent of frame rate and an order of magnitude improvement in contrast over the state of the art. Traditionally DMD-based IRSPs have offered larger format and superior uniformity and pixel operability relative to resistive and diode arrays, however, they have been limited in contrast and also by the inherent bitdepth / frame rate tradeoff imposed by pulse width modulation (PWM). OPTRA's high dynamic range IRSP (HIDRA SP) has broken this dependency with a dynamic structured illumination solution. The HIDRA SP uses a source conditioning DMD to impose the structured illumination on two projector DMDs -one for each spectral band. The source conditioning DMD is operated in binary mode, and the relay optics which form the structured illumination act as a low pass spatial filter. The structured illumination is therefore spatially grayscaled and more importantly is analog with no PWM. In addition, the structured illumination concentrates energy where bright object will be projected and extinguishes energy in dark regions; the result is a significant improvement in contrast. The projector DMDs are operated with 8-bit PWM, however the total projected image is analog with no bit-depth / frame rate dependency. In this paper we describe our progress towards the development, build, and test of a prototype HIDRA SP.
OPTRA is developing a next generation digital micromirror device (DMD) based two-band infrared scene projector (IRSP) with infinite bit depth independent of frame rate and an order of magnitude improvement in contrast over the state of the art. Traditionally, DMD-based IRSPs have offered larger format, superior uniformity, and pixel operability relative to resistive and diode arrays. However, they have been limited in contrast and also by the inherent bit depth/frame rate tradeoff imposed by pulse width modulation (PWM). OPTRA's high dynamic range IRSP (HIDRA SP) has broken this dependency with a dynamic structured illumination solution. The HIDRA SP uses a source-conditioning DMD to impose the structured illumination on two projector DMDs-one for each spectral band. The source-conditioning DMD is operated in binary mode, and the relay optics that form the structured illumination act as a low-pass spatial filter. The structured illumination is, therefore, spatially grayscaled and more importantly is analog with no PWM. In addition, the structured illumination concentrates energy where bright objects will be projected and extinguishes energy in dark regions; the result is a significant improvement in contrast. The projector DMDs are operated with 8-bit PWM; however, the total projected image is analog with no bit depth/frame rate dependency. We describe our progress toward the development, building, and testing of a prototype HIDRA SP. Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms
Abstract. A number of optical techniques are available to perform active standoff trace explosive detection. Integrating a laser scanner provides the ability to detect explosives over a wide area as well as to assess the full extent of a threat. Risley prism laser-beam steering systems provide a robust alternative to conventional scanner solutions and are ideal for portable and mobile systems due to their compact size, low power, large fieldof-view, and fast scan speed. The design of a long-wave infrared Risley prism-scanned diffuse reflectance spectroscopy system along with data obtained from a prototype system is presented for both simulant and live explosive materials.
OPTRA is currently developing a modular, reconfigurable matched spectral filter (RMSF) spectrometer for the monitoring of greenhouse gases. The heart of this spectrometer will be the RMSF core, which is a dispersive spectrometer that images the sample spectrum from 2000 -3333 cm -1 onto a digital micro-mirror device (DMD) such that different columns correspond to different wavebands. By applying masks to this DMD, a matched spectral filter can be applied in hardware. The core can then be paired with different fore-optics or detector modules to achieve active in situ or passive remote detection of the chemicals of interest. This results in a highly flexible system that can address a wide variety of chemicals by updating the DMD masks and a wide variety of applications by swapping out fore-optic and detector modules. In either configuration, the signal on the detector is effectively a dot-product between the applied mask and the sample spectrum that can be used to make detection and quantification determinations. Using this approach significantly reduces the required data bandwidth of the sensor without reducing the information content, therefore making it ideal for remote, unattended systems. This paper will focus on the design of the RMSF core.
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