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The digital micromirror device (DMD) is a micro-optical-electro-mechanical structure (MOEMS) consisting of an array of 16.tm x l6jtm square mirrors positioned on a 17 jim pitch. Each individual mirror can be tilted +1-10 degrees relative to the DMD substrate; the tilt is along the diagonal direction of the micromirror. The device was invented and manufactured by Texas Instruments (TI), Inc. TI packages the DMD as an OEM product for use in projection displays. We are investigating the use of the DMD as a spatial light modulator for precision imaging and spectroscopy applications. This includes optical characterization of the device, as well as systems engineering to operate the device. Some of the performance metrics to be considered are the diffraction efficiency, optical-switching contrast, background scattering properties, mirror crosstalk, and the modulation transfer function (MTF). DIGITAL MICROMIRROR DEVICESAt the RIT Center for Imaging Science, our research involves the development and implementation of innovative imaging instrumentation for use in astronomical imaging and spectroscopy. The goal of this characterization effort is to understand the performance limits of DMD devices for use in precision imaging instrumentation. We are particularly interested in understanding the scattering properties, the diffraction efficiency, and the MTF. With this information we intend to develop a set of design rules for incorporating a DMD device into an optical imaging chain. DMD architectureThe Digital Micromirror Device (DMD) was developed by Texas Instruments (TI), and is the first large-scale commercial implementation of a micro-optical-electro-mechanical system (MOEMS)1'2. The device consists of an array of micromirrors, 16j.tm x l6jim square, mounted on a 17 im pitch. Each mirror is mounted on a post, and can tilt along the diagonal direction. The mirror is tilted by electrostatic attraction towards biased landing pad/electrodes under the mirror. These landing pads constrain the mirror to fixed rotation angles of +1-10 degrees relative to the substrate. The mirror assemblies are mounted atop a CMOS circuit which is used to latch the input mirror state. The device is marketed by TI as an OEM board set for use in projection display devices. The complete DMD and board set are termed, by TI, a Digital Light Processor (DLP) . The DLP consists of a 640 x 480 pixel DMD (VGA format; an SVGA format is also now available) mounted on a driver/formatter board, and also includes the required PC interface boards. Reports in the trade press suggest that a DMD configured for use in digital printers and film writers is also forthcoming3'4. TI also makes the DLP available in kit form for use in research applications. In accordance with current usage, we will use the acronym DMD in this paper to mean the entire board set as well as the DMD proper.Author contact information -kjk5423 @ritvax.rit.edu SPIE Vol. 3292 • 0277-786X/98/$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/14/2015 Terms of Use: http://spie...

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Abstract-The planned tracking upgrade of the STAR experiment at RHIC includes a large-area GEM tracker used to determine the charge sign of electrons and positrons produced from W +(−) decays. For such a large-scale project commercial availability of GEM foils is necessary. We report first results obtained with a triple GEM detector using GEM foils produced by Tech-Etch Inc. of Plymouth, MA, USA. Measurements of gain uniformity, long-term stability as well as measurements of the energy resolution for X-Rays are compared to results obtained with an identical detector using GEM foils produced at CERN. A quality assurance procedure based on optical tests using an automated high-resolution scanner has been established, allowing a study of the correlation of the observed behavior of the detector and the geometrical properties of the GEM foils. Detectors based on Tech-Etch and CERN produced foils both show good uniformity of the gain over the active area and stable gain after an initial charge-up period, making them well suited for precision tracking applications.