Proceedings Volume 8254

Emerging Digital Micromirror Device Based Systems and Applications IV

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Proceedings Volume 8254

Emerging Digital Micromirror Device Based Systems and Applications IV

View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 21 March 2012
Contents: 10 Sessions, 25 Papers, 0 Presentations
Conference: SPIE MOEMS-MEMS 2012
Volume Number: 8254

Table of Contents

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Table of Contents

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  • Front Matter: Volume 8254
  • Picoprojectors: Systems and Components: Joint Session with Conference 8252
  • Biomedical Imaging and Cell Manipulation using a Digital Micromirror Device II: Joint Session with Conference 8225
  • Biomedical Imaging and Cell Manipulation using a Digital Micromirror Device III: Joint Session with Conference 8225
  • Holographic Implementation
  • Rapid Prototyping
  • 3D Measurement Systems Using Structured Light
  • Advanced Display
  • Laser Beam Shaping
  • Dynamic Spectral Imaging and Attenuation
Front Matter: Volume 8254
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Front Matter: Volume 8254
This PDF file contains the front matter associated with SPIE Proceedings Volume 8254, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
Picoprojectors: Systems and Components: Joint Session with Conference 8252
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Network-based multisensor optical 3D acquisition of complex structures
G. Frankowski, R. Hainich
We present new developments in optical 3d sensors using pico DLP as well as DSP technology. We use enhanced, high-powered pico DLP projection units and compact processing hardware to create likewise compact, light-weight measuring heads, which can perform the acquisition as well as the evaluation of 3D data without external computing power. Moreover, their drastically reduced cost and their networking ability also allows for an economical combination of a multitude of individual sensors into complex configurations. The entire form even of large and complex shapes can hereby be scanned in a very short time. New calibration strategies, integrating all individual sensor coordinate systems into a single, calibrated, global one, lead to an immediate combination of all sensor data into a single, complete point cloud. We show the principle and actual realization of sensors, calibration strategies and procedures, and examples of first realized multi-sensor measuring systems utilizing this new technology.
Biomedical Imaging and Cell Manipulation using a Digital Micromirror Device II: Joint Session with Conference 8225
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Hyperspectral imaging in the operating room: what a surgeon wants
Sara L. Best
Visualization is the key to surgery, but limiting one's "vision" to visible light images received by the human eye ignores a lot of available data. Imaging technology such as hyperspectral and infrared imaging can greatly expand the amount and type of information available to the surgeon. We propose several areas in which this type of technology can be useful in medicine, paying particular attention to the way in which this technology might be best integrated into current operating room setups.
Evaluation of a novel laparoscopic camera for characterization of renal ischemia in a porcine model using digital light processing (DLP) hyperspectral imaging
Ephrem O. Olweny, Yung K. Tan, Stephen Faddegon, et al.
Digital light processing hyperspectral imaging (DLP® HSI) was adapted for use during laparoscopic surgery by coupling a conventional laparoscopic light guide with a DLP-based Agile Light source (OL 490, Optronic Laboratories, Orlando, FL), incorporating a 0° laparoscope, and a customized digital CCD camera (DVC, Austin, TX). The system was used to characterize renal ischemia in a porcine model.
Spatial frequency domain imaging (SFDI): a technology overview and validation of an LED-based clinic friendly device
We present an overview of Spatial Frequency Domain Imaging (SFDI), a non-contact near infrared (NIR) imaging approach that enables rapid, quantitative determination of the optical properties and in vivo concentrations of chromophores over a wide field-of-view. SFDI is capable of rapidly rendering quantitative two-dimensional maps of oxy and deoxy hemoglobin, total hemoglobin (related to blood volume), tissue oxygen saturation, water content, and scattering coefficient (related to tissue structure).
Biomedical Imaging and Cell Manipulation using a Digital Micromirror Device III: Joint Session with Conference 8225
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Digital-micromirror-device-based confocal 4D microscopy
M. Schellenberg, M. Kloster, J. Napier, et al.
Digital Micromirror Device based microscopy combines fast confocal 4D-microscopy along with conventional methods for light microscopy and new technological approaches to a versatile tool for the observation of in vivo processes in living biological cells and measurement of technical surfaces. Due to the use of variable size pinholes and adjustable scan patterns conditions for confocal measurement can easily be optimized to the prerequisites of the sample "on the fly".
A pico projector source for confocal fluorescence and ophthalmic imaging
Matthew S. Muller
A Pico digital light projector has been implemented as an integrated illumination source and spatial light modulator for confocal imaging. The target is illuminated with a series of rapidly projected lines or points to simulate scanning. Light returning from the target is imaged onto a 2D rolling shutter CMOS sensor. By controlling the spatio-temporal relationship between the rolling shutter and illumination pattern, light returning from the target is spatially filtered. Confocal retinal, fluorescence, and Fourier-domain optical coherence tomography implementations of this novel imaging technique are presented.
Medical devices in dermatology using DLP technology from Texas Instruments
M. Kock, F. Lüllau
The market of medical devices is growing continuously worldwide. With the DLP™ technology from Texas Instruments Lüllau Engineering GmbH in Germany has realized different applications in the medical discipline of dermatology. Especially a new digital phototherapy device named skintrek™ PT5 is revolutionizing the treatment of skin diseases like psoriasis , Vitiligo and other Eczema. The functions of the new phototherapy device can only be realized through DLP™ technology which is not only be used for the selective irradiation process. In combination with other optical systems DLP™ technology undertakes also other functionalities like 3D-topology calculation und patient movement compensation.
Implementation of an LED-based clinical spatial frequency domain imaging system
Amaan Mazhar, Seyed A. Sharif, Steve Saggese, et al.
Spatial Frequency Domain Imaging (SFDI) is a non-contact imaging method that uses multiple frequency spatial illumination to generate two dimensional maps of tissue optical properties (absorption and reduced scattering) and chromophore concentrations. We present phantom validation and pilot clinical data of a deployed light-emitting diode (LED) based system. The system employs four LED wavelengths (658 nm, 730 nm, 850 nm, 970 nm) to quantitatively assess tissue health by measurement of common tissue constituents. Phantom validation results and maps of oxyhemoglobin, deoxy-hemoglobin, water content, reduced scattering, and surface topography will be presented for pilot studies assessing burn severity and efficacy of port wine stain treatment.
Holographic Implementation
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Real time 3D holographic display
Luigi Loreti, R. Ceccarelli, A. Loreti, et al.
In this article is described a Real Time 3D video display of holographic images based on the principle of sequential scanning of holograms with HPO (horizontal parallax only) generated by a high speed computer and sent at high frame rate to DMD, and visualized by an anamorphic optical group. The device displays binary amplitude and phase modulated images opportunely synchronized and scanned by a galvanometric mirror or polygonal mirror driven by the control electronic circuitry. The elementary holograms are generated by a resident hardware which, through interpolation, generates single elementary holograms starting from images and depth map. The device operates with incoherent light (integral images) or with coherent light (holographic display) by changing the optical visualization group.
Suppression of the zero-order diffraction beam from computer-generated holograms produced by a DLP spatial light modulator
Sih-Ying Wu, Jinyang Liang, Michael F. Becker
We present a new optical technique to suppress the unwanted zero-order diffraction (ZOD) in holograms produced by the digital micromirror device (DMD). The proposed optical architecture consists of two light beams illuminating the DMD in an interferometer configuration. The two beams are incident from different angles, +24° and -24°, in order to utilize light diffracted from all the pixels to produce a binary Fresnel hologram. The relation between these two beams diffracting from the DMD was found to be complementary, and they both generated the same reconstructed image pattern. With π phase difference between the two beams, the diffracted beams had their ZOD components out of phase while the reconstructed holograms were identical and in phase. Experiments were conducted to demonstrate ZOD suppression by destructive interference and simultaneous hologram enhancement by constructive interference. The method was shown to suppress the ZOD by a factor of 2.9 in a Fresnel hologram.
Rapid Prototyping
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DLP-based light engines for additive manufacturing of ceramic parts
M. Hatzenbichler, M. Geppert, S. Gruber, et al.
In the framework of the European research project PHOCAM (http://www.phocam.eu) the involved partners are developing systems and materials for lithography-based additive manufacturing technologies (AMT) which are used for shaping advanced ceramic materials. In this approach a ceramic-filled photosensitive resin is selectively exposed layer by layer. By stacking up the individual layers with a typical layer thickness between 25 and 50μm, a three-dimensional part is built up. After structuring, a solid part consisting of a ceramic filled polymer is obtained. The polymer is afterwards burnt off and in a last step the part is sintered to obtain a fully dense ceramic part. The developed systems are based on selective exposure with DLP projection (Digital Light Processing). A key element of the developed systems is a light engine which uses digital mirror devices (DMD) in combination light emitting diodes (460nm) as light source. In the current setup DMDs with 1920x1080 pixels are used. The use of LEDs in combination with a customized optical projection system ensures a spatial and temporal homogeneity of the intensity at the build platform which is significantly better than with traditionally used light engines. The system has a resolution of 40μm and a build size of 79x43x100mm. It could be shown that this system can fabricate dense ceramic parts with excellent strength. In the case of alumina densities up to 99.6% of the theoretical density were achieved, yielding a biaxial strength of 510MPa. Besides technical ceramics like alumina it is also possible to structure bioceramics, e.g. tricalcium phosphate.
3D Measurement Systems Using Structured Light
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Measurement of human subjects using structured light
Matthew W. Bellis, Daniel L. Lau
Phase measurement profilometry is a well-known technique for making 3D measurements. The technique involves the projection of patterns with a sinusoidally varying spatial intensity. This approach has been used extensively to make highly accurate measurements of static images. The use of structured light to make highly accurate measurements on human subjects is more difficult because of the inherent motion of the subject under test. In this paper, we discuss the implementation of LUT based processing in combination with novel architectures to enable accurate measurements of human subjects. Two specific applications are reviewed: human body scanning and intra-oral dental scanning.
Face recognition via a projective compressive sensing system
Brant M. Kaylor, Charlie J. Keith, Peter A. Roos, et al.
A projective compressive sensing system for face recognition is presented. The Fisherfaces method was utilized for classification of the face images. The system uses a digital micromirror device to project measurement vectors onto the scene and a single photodetector to collect the backscattered illumination. Experimentally, the system accuracy was 95.5% using only 32 measurements per image; this performance matches the simulation results. The total number of image pixels was 5,736 (84 × 64) resulting in a compression factor of 168 over a conventional imaging system.
High-speed 3D measurement system using DMD-based projector for industrial applications
Yasumoto Mori, Keisuke Saito, Kenji Homma, et al.
Higher accuracy and reliability are indispensable especially in the field of industrial 3D measurement applications. 3D measurement based on the phase shifting technique applies to various applications of imaging system. We developed a DMD projector for the projection of fringe patterns for the phase shifting technique. A DMD projector has a lot of advantages compared with other devices such as LCD. We focus on the specifications of speed, intensity linearity and brightness of the DMD. We show, in this paper, our DMD-based 3D measurement system satisfies requirements which come from industrial applications, and also show two representative applications and feasibility of our phase shifting system to these applications.
Volumetric 3D display using a DLP projection engine
In this article, we describe a volumetric 3D display system based on the high speed DLPTM (Digital Light Processing) projection engine. Existing two-dimensional (2D) flat screen displays often lead to ambiguity and confusion in high-dimensional data/graphics presentation due to lack of true depth cues. Even with the help of powerful 3D rendering software, three-dimensional (3D) objects displayed on a 2D flat screen may still fail to provide spatial relationship or depth information correctly and effectively. Essentially, 2D displays have to rely upon capability of human brain to piece together a 3D representation from 2D images. Despite the impressive mental capability of human visual system, its visual perception is not reliable if certain depth cues are missing. In contrast, volumetric 3D display technologies to be discussed in this article are capable of displaying 3D volumetric images in true 3D space. Each "voxel" on a 3D image (analogous to a pixel in 2D image) locates physically at the spatial position where it is supposed to be, and emits light from that position toward omni-directions to form a real 3D image in 3D space. Such a volumetric 3D display provides both physiological depth cues and psychological depth cues to human visual system to truthfully perceive 3D objects. It yields a realistic spatial representation of 3D objects and simplifies our understanding to the complexity of 3D objects and spatial relationship among them.
Advanced Display
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Considerations for DMDs operating in the infrared
The evolution of the DMD has enabled the development of a broad range of technologies from sensors to various types of devices such as projectors and displays. The low cost and excellent reliability has made the DMD an ideal choice for most applications requiring a spatial light modulator. The aluminum micromirrors can be used over a broad spectral range with an appropriate window; DMD-based systems have therefore been realized across the ultraviolet through and including the longwave infrared. Of particular interest for scene projector, compressive imaging, and spectrometer applications is the use of the DMD in the infrared where diffraction, instrument radiance, and optical resolution impose performance limits. Diffraction and instrument radiance, among other factors, impact the highest achievable contrast, and constraints on the lowest practical illumination and projection f/# limit the ability to resolve a single micromirror at longer wavelengths. In this paper, we present analytical models addressing these issues as well as demonstrated solutions in a DMD-based midwave infrared (MWIR) scene projector as well as a MWIR compressive imaging camera.
Full color high contrast front projection on black emissive display
Front digital projection (FDP) displays have the features of being portable, economical and scalable for large size displays. Unfortunately, existing FDP technologies suffer with poor image contrast in well-lighted environments, due to the "black-level" issues of the conventional white diffusive screens. More powerful projectors can be applied to enhance contrasts by increasing the brightness, at the expenses of significantly increased cost, weight, power consumption, and viewer eye fatigue due to the bright projection. In this joint paper, we demonstrate an innovative full color, high contrast front projective display system on a black emissive screen (BES). It comprises of a novel transparent fluorescent screen on pitch-black substrate, and a digital image projector with optic output that excite the fluorescent screen. The fluorescent layered screen is comprised of at least 3 layers of RGB emissive materials, which are made in fully transparent form. The "excitation" projector is based on DLP® projector platform, where a UHP lamp is filtered by a color filter wheel which sequentially excites the RGB emissive layers resulting in RGB emissions from the screen. This display combines the best of both worlds of front projection and emissive display technologies. Like projection displays, it is scalable and economic at large displays, the screen has no pixel structure and can be manufactured using a roll to roll method. Like emissive displays (e.g. plasma or field emission displays with phosphor screen), the quality of the emissive images on black back-plate is superior, with large viewing angles and superior contrasts in any environments. The new projection display can favorably compete with existing flat panel displays and other projection displays.
Laser Beam Shaping
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Multimode fiber-based high-power laser distribution using DLP technology
Adèle Morisset, Elodie Durbize, Bruno Chassagne, et al.
Directing high laser power spatially and temporally is of major interest for various applications. We developed a compact and efficient system based on a DMD and consisting of a homemade multimode high-brightness fiber splitter and a 60-Watt laser diode. This design enables computer-controlled distribution of several Watts of laser power to each or several optical fibers in the bundle consisting of 7 fibers in this paper (but it can be extended to 19, 37 or more fibers). The coupling efficiency and extinction ratio were measured and optimized. An overall efficiency of about 9% was demonstrated by considering all losses due to DMD efficiency, geometric fill factor and fiber coupling efficiency, with extinction ratios between 20 and 45dB.
Bandwidth-limited laser image projection using a DMD-based beam shaper
Jinyang Liang, Sih-Ying Wu, Rudolph N. Kohn Jr., et al.
A digital micromirror device (DMD) laser beam shaper was implemented for projecting spatial bandwidth-limited laser images with precisely controlled intensity. A telescope images the binary DMD pattern with an adjustable pinhole low-pass filter that controls the system bandwidth and converts the binary pixelated image back to grayscale. Images with arbitrary but bandwidth-limited spatial frequency content are formed. System performance was evaluated by examining the spatial frequency response in terms of RMS intensity error by generating sinusoidal-flattop beam profiles with different spatial periods. This system evaluation was used as a reference to predict the error level of arbitrary output beam profiles. In addition, we demonstrated band-limited laser image projection for different spatial bandwidths using a grayscale image superimposed on a flattop laser beam profile. Optimized system bandwidth was simulated by considering the tradeoff between image precision and spatial resolution. Experimental results demonstrated that the RMS error of output beam profiles was consistent with the system evaluation reference. The major residual error in the output beam profile came from the sharp-edged pinhole low-pass filter. Error histograms had a Gaussian distribution with mean value of zero and standard deviation equal to the value of the RMS error. We plan to apply this technique to generate programmable optical trap shapes in ultracold atom experiments.
Application of DMD: laser speckle control for rough surface photofabrication
Vincent Brissonneau, Ludovic Escoubas, François Flory, et al.
Digital Micromirror Devices are mainly known for display in video projectors. More and more, they are used in industrial or research applications. DMD is a versatile tool for lithography allowing photoresist exposure with easy-changing masking step in direct-patterning. Any application where light shaping is necessary can be considered by using DMD. We here show photofabrication of random rough surfaces using an indirect modified beam exposure. A laser beam is enlarged and scattered by a diffusing element. The scattering from this diffusing surface allows the creation of a speckle pattern with a random light distribution. The intensity is then recorded on a photoresist coated substrate. The patterned photoresist is next developed and an etching step enables the transfer on the silicon. It can be shown that the statistical properties of the speckle pattern can be controlled. The intensity distribution is modified by the number of exposures and the correlation function is linked to the spatial distribution of the laser beam. Some examples of such photofabrication can be found using a Gaussian unmodified beam leading to Gaussian correlation photofabricated surfaces. In order to design random rough surfaces having a non Gaussian correlation we need to modify the laser beam shape. This modification is achieved using a DMD. The experimental processes from photoresist deposition to modified exposure are discussed in this paper.
Dynamic Spectral Imaging and Attenuation
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Study of an NIR digital micromirror device-based snapshot spectral imaging system
Yuehao Wu, Iftekhar O. Mirza, Gonzalo R. Arce, et al.
We discuss the design of a Digital Micromirror Device-based Snapshot Spectral Imaging (DMD-SSI) system for NIR wavelengths. A pair of low/high dispersion glasses was selected for building an NIR relay-lens and a double-Amici prism, which are needed for generating Compressive Sensing (CS) measurements in experimental settings. Aberrations of the system were simulated using the Zemax software, which were considered in a numerical model of the system. CS measurements were generated using this model accounting for those aberrations. We evaluated the quality of the spatial/spectral data-cubes reconstructed using those non-ideal CS measurements and discuss possible solutions of enhancing the reconstruction quality.
Flat spectral response all-digital broadband variable fiber optic attenuator
The Texas Instruments (TI) digital micromirror device (DMD) is inherently a two dimensional (2-D) blaze grating that causes wavelength-dependent angular spreading of reflected broadband light limiting its use as a broadband variable fiber optic attenuator (VFOA). In this paper, we propose a novel design that utilizes a double-reflection architecture to counter angular spreading while at the same time eliminates the need to use any narrowband components such as wave plates thus delivering a truly flat spectral response VFOA. The key feature of this design is that the DMD, instead of being oriented in the Littrow retro-reflective configuration for the center wavelength, is oriented at a different angle to the input beam such that the blaze condition is still satisfied albeit for a different diffraction order n. The only wavelength dependent loss (WDL) in this design is due to the fact that the blaze condition is satisfied only for a center wavelength λc at which the diffraction efficiency is maximum while at other wavelengths, the blaze condition is not perfectly satisfied resulting in a loss in diffraction efficiency. Simulation results show a WDL of only 0.01 dB over the C-band compared to the previously reported experimental value of ±0.37 dB thus resulting in a truly flat spectral response VFOA.
Demonstrator of a multi-object spectrograph based on the 2048x1080 DMD
Frederic Zamkotsian, Paolo Spano, William Bon, et al.
Multi-Object Spectrographs (MOS) are the major instruments for studying primary galaxies and remote and faint objects. Current object selection systems are limited and/or difficult to implement in next generation MOS for space and ground-based telescopes. A promising solution is the use of MOEMS devices such as micromirror arrays which allow the remote control of the multi-slit configuration in real time. We are developing a Digital Micromirror Device (DMD) - based spectrograph demonstrator. We want to access the largest FOV with the highest contrast. The selected component is a DMD chip from Texas Instruments in 2048 × 1080 mirrors format, with a pitch of 13.68μm. Such component has been also studied by our team in early phase EUCLID-NIS study. Our optical design is an all-reflective spectrograph design with F/4 on the DMD component, including two arms, one spectroscopic channel and one imaging channel, thanks to the two stable positions of DMD micromirrors. This demonstrator permits the study of key parameters such as throughput, contrast and ability to remove background and spoiler sources, PSF effect. This study will be conducted in the visible with possible extension in the IR. The breadboard has been designed and is under realization before integration on a bench simulating an astronomical FOV. The demonstrator is of prime importance for characterizing the actual performance of this new family of instruments, as well as investigating the operational procedures on astronomical objects. If this demonstrator is successful, next step will be a demonstrator instrument placed on the Telescopio Nazionale Galileo.
Hyperspectral image projector applications
For the past several years NIST has been developing, along with several collaborators, a Hyperspectral Image Projector (HIP). This scene projector produces high-resolution programmable spectra and projects them into dynamic two-dimensional images. The current digital micromirror device (DMD) based HIP prototype has a spatial resolution of 1024 x 768 pixels and a spectral range of 450 nm to 2400 nm, with spectral resolution from 2 nm in the visible to 5 nm in the short-wave infrared. It disperses light from a supercontinuum fiber source across two DMDs to produce the programmable spectra, which then globally-illuminate a third DMD to form the spatial images. The HIP can simulate top-of-the atmosphere spectral radiance over a 10 mm x 14 mm, f/3 image, and this can be collimated to stimulate remote sensing instruments. Also, the spectral radiance of the projected scenes can be measured with a NIST-calibrated spectroradiometer, such that the spectral radiance projected into each pixel can be accurately known. The HIP was originally developed for applications in multi-spectral and hyperspectral imager testing, calibration, and performance validation, and examples of this application will be reviewed. Conceivable applications for the HIP in photovoltaic device characterization and optical medical imaging will also be discussed.