This PDF file contains the front matter associated with SPIE Proceedings Volume 7932, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Digital Light Processing (DLP®) hyperspectral imaging (HsI) is a non-invasive method used to construct a highly sensitive, real-time tissue oxygenation map through the measurement of the percentage of oxyhemoglobin. We have demonstrated that this technology can detect the oxyhemoglobin in the blood vessels on the surface of the kidney and we have used this to monitor renal perfusion during kidney cancer operations, where the blood supply to the kidney is interrupted for a period of time. This technology may allow us to "personalize" surgery based on the oxygenation profile.

Visible DLP® hyperspectral reflectance imaging in medical applications is limited by the lack of penetration of visible light for visualization of deeper vessels and tissues. The longer, near infrared (NIR) wavelengths, capable of facilitating chromophore and fluorophore visualization, penetrate deeper allowing visualization of anatomical structures in surgical settings. Digital micromirror device (DMD) chips allow for digital programming of complex spectral illuminations with bandwidths as low as 7nm. Furthermore, fluorescence can be maximized by programming the DMD chip to illuminate with light precisely configured to contain excitation spectra. We have developed a "mid-range" system that extends from the visible light range into the NIR (525nm - 1050nm) and has been characterized and configured for fluorescence of indocyanine green (ICG). The DMD-based light source was found to be within the manufacturer's spectral specifications and proved to be very versatile in both spectral behavior and application. Fluorescence of ICG was successfully optimized by this system and demonstrated in capillary tubes and excised tissue.

DLP® hyperspectral reflectance imaging in the visible range has been previously shown to quantify hemoglobin oxygenation in subsurface tissues, 1 mm to 2 mm deep. Extending the spectral range into the near infrared reflects biochemical information from deeper subsurface tissues. Unlike any other illumination method, the digital micro-mirror device, DMD, chip is programmable, allowing the user to actively illuminate with precisely predetermined spectra of illumination with a minimum bandpass of approximately 10 nm. It is possible to construct active spectral-based illumination that includes but is not limited to containing sharp cutoffs to act as filters or forming complex spectra, varying the intensity of light at discrete wavelengths. We have characterized and tested a pure NIR, 760 nm to 1600 nm, DLP hyperspectral reflectance imaging system. In its simplest application, the NIR system can be used to quantify the percentage of water in a subject, enabling edema visualization. It can also be used to map vein structure in a patient in real time. During gall bladder surgery, this system could be invaluable in imaging bile through fatty tissue, aiding surgeons in locating the common bile duct in real time without injecting any contrast agents.

There are numerous medical conditions which may benefit from hyperspectral imaging. The imagers used for these conditions will need to have the performance validated to ensure consistency, gain acceptance and clear regulatory hurdles. NIST has been developing a Digital Light Processing (DLP)-based Hyperspectral Image Projector (HIP) for providing scenes with full spectral content in order to evaluate multispectral and hyperspectral imagers. In order for the scene to be projected, a dimensionality reduction is performed in order to project spectra efficiently. The number of eigenspectra needed to best represent a scene is an important part in the recombining of the image. This paper studies the spectral diversity between different medical scenes collected by a DLP based hyperspectral imager. Knowledge gained from this study will help guide the methods used for hyperspectral image projection of medical scenes in the future.

Hyperspectral retinal imaging can measure oxygenation and identify areas of ischemia in human patients, but the devices used by current researchers are inflexible in spatial and spectral resolution. We have developed a flexible research prototype consisting of a DLP®-based spectrally tunable light source coupled to a fundus camera to quickly explore the effects of spatial resolution, spectral resolution, and spectral range on hyperspectral imaging of the retina. The goal of this prototype is to (1) identify spectral and spatial regions of interest for early diagnosis of diseases such as glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR); and (2) define required specifications for commercial products. In this paper, we describe the challenges and advantages of using a spectrally tunable light source for hyperspectral retinal imaging, present clinical results of initial imaging sessions, and describe how this research can be leveraged into specifying a commercial product.

The printed circuit board (PCB) industry has long used a lithography process based on a polymer mask in contact with a large, resist-coated substrate. There is a limit to this technique since both the masks and PCB substrates themselves may undergo distortion during fabrication, making high resolution or tight registration difficult. The industry has increasingly turned to digital lithography techniques which, in addition to eliminating the masks, can actively compensate for distortions. Many of these techniques rely on a "dot-matrix" style exposure technique that uses "binary" pixels and small pixel or dot spacing to achieve the required resolution. This results in limitations in write speed and throughput, since many small pixels or dots must be written over a relatively large area PCB substrate. A patented gray level technique¹ based on a commercially available digital micro-mirror device (DMD) achieves required resolutions with a relatively large projected pixel size, and thus offers a higher speed alternative to conventional digital techniques. The technique described is not limited to PCB, but may be applied to any lithography or printing-based application where high speed and accurate registration are concerns.

We designed a precision laser beam shaper using a Texas Instruments digital micromirror device (DMD) with a telescope system containing a pinhole low-pass filter. The performance of the beam shaper was measured by comparing the intensity and wave-front uniformity to the target function and by the energy conversion efficiency. We demonstrated flattop and other laser beam profiles with 1-1.5% root-mean-square (RMS) error for a raw camera image and nearly flat phase. A noise analysis of the system revealed that lower error is possible and that most of the error came from coherent speckle noise in the camera. A previous experiment using a 1064 nm single-mode fiber (SMF) laser produced around 7% beam power conversion efficiency. Here we report improvements in system automation and laser source flexibility that result in increasing both the speed of the system to calculate and produce a beam, and the beam uniformity and energy conversion efficiency. A LabVIEW program was written to accelerate the speed of the iterative process for beam profile refinement. A 760 nm super-luminescent light emitting diode (SLED) and a 781 nm Laser Diode (LD) were used as light sources in order to reduce the beam coherence and approach the ultimate performance of the shaper. Both sources greatly reduced the speckle noise and increased measured intensity uniformity. Experiments achieved less than 0.9% RMS error over the entire flattop area with a diameter of 1.32 mm. In addition, simulations were conducted to determine the optimized wavelengths for different types of DMDs. For the .7XGA DMD, the 5th diffraction order matches 750-800 nm. Matching the laser diode to this wavelength increased the power conversion efficiency (input beam to output beam) to 19.8%.

In this paper, Sun Innovations demonstrates an innovative emissive projection display (EPD) system. It is comprised of a fully transparent fluorescent screen with a UV image projector. The screen can be applied to glass windows or windshield, without affecting visible light transmission. The UV projector can be based on either a DLP (digital light processor) or a laser scanner display engine. For a DLP based projector, a discharge lamp coupled to a set of UV filters can be applied to generate a full color video image on the transparent screen. UV or blue-ray laser diodes of different wavelengths can be combined with scanning mirrors to generate a vector display for full windshield display applications. This display combines the best of both worlds of conventional projection and emissive display technologies. Like a projection display, the screen has no pixel structure and can be manufactured roll to roll; the display is scalable. Like an emissive display (e.g. plasma or CRT), the quality of the image is superior, with very large viewing angles. It also offers some unique features. For example, in addition to a fully transparent display on windows or windshields, it can be applied to a black substrate to create the first front projection display on true "black" screen that has superior image contrast at low projection power. This fundamentally new display platform can enable multiple major commercial applications that can not be addressed by any of the existing display technologies.

Next-generation infrared multi-object spectrographs (MOS) for ground-based and space telescopes could be based on MOEMS programmable slit masks. This astronomical technique is used extensively to investigate the formation and evolution of galaxies. ESA has engaged a study for a technical assessment of using a DMD from Texas Instruments for space applications. The DMD features 2048 × 1080 mirrors on a 13.68μm pitch, where each mirror can be independently switched between an ON (+12°) position and an OFF (-12°) position. For MOS applications in space, the device should work in vacuum, at low temperature, and each MOS exposure would last for typically 1500s with micromirrors held in a static state (either ON or OFF). A specific thermal/vacuum test chamber has been developed for test conditions down to -40°C at 10^-5 mbar vacuum. Imaging capability for resolving each micromirror has also been developed for determining degradation in any single mirror. Our first tests reveal that the DMD remains fully operational at -40°C and in vacuum. A 1038 hours life test in space conditions, Total Ionizing Dose radiation, thermal cycling and vibrations/shocks have also been successfully completed. These results do not reveal any concerns regarding the ability of the DMD to meet environmental space requirements. Detailed analysis of micromirror throughputs has also been studied for a whole set of tests, and shows a rather low variation and no impact of the space environment. We have also developed a bench for MOS demonstration using MOEMS devices. DMD chip has been successfully tested revealing good contrast values as well as good functionality for applying any mask pattern, demonstrating its full ability for space instrumentation, especially in multi-object spectroscopy applications.

In this paper, we provide a thorough overview of recent advances in 3D surface imaging technologies. We focus particularly on non-contact 3D surface measurement techniques based on structured illumination. The high-speed and high-resolution pattern projection capability offered by the digital light processing (DLP) technology, together with the recent advances in imaging sensor technologies, may enable new generation systems for 3D surface measurement applications that provide much better functionality and performance than existing ones, in terms of speed, accuracy, resolution, size, cost, and ease of use. Performance indexes of 3D imaging systems in general are discussed and various 3D surface imaging schemes are categorized, illustrated, and compared. Calibration techniques are also discussed since they play critical roles in achieving the required precision. Benefits and challenges of using DLP technology in 3D imaging applications are discussed. Numerous applications of 3D technologies are discussed with several examples.

As crime prevention and national security remain a top priority, requirements for the use of fingerprints for identification continue to grow. While the size of fingerprint databases continues to expand, new technologies that can improve accuracy and ultimately matching performance will become more critical to maintain the effectiveness of the systems. FlashScan3D has developed non-contact, fingerprint scanners based on the principles of Structured Light Illumination (SLI) that capture 3Dimensional data of fingerprints quickly, accurately and independently of an operator. FlashScan3D will present findings from various research projects performed for the US Army and the Department of Homeland Security.

GFM has developed and constructed DLP-based optical 3D measuring devices based on structured light illumination. Over the years the devices have been used in industrial metrology and life sciences for different 3D measuring tasks. This lecture will discuss integration of DLP Pico technology and DSP technology from Texas Instruments for mass market optical 3D sensors. In comparison to existing mass market laser triangulation sensors, the new 3D sensors provide a full-field measurement of up to a million points in less than a second. The lecture will further discuss different fields of application and advantages of the new generation of 3D sensors for: OEM application in industrial measuring and inspection; 3D metrology in industry, life sciences and biometrics, and industrial image processing.

We build up a new type of 3D metrology system for measuring the 3D shape of micro-structures and for reverse engineering techniques. The measurement principle is an active triangulation with a high dynamic range. The optical imaging is realized with a stereomicroscope. This features a field of view from square-centimeters down to square-millimeters at a constant triangulation angle. One port of the stereomicroscope is used to project measurement labels onto a measurement object and the second port to observe them by a camera. A calibration enables the assignment of 3D coordinates to the position of a measurement label in the camera image. To generate measurement labels we use a projection device that consists of a collimated, white light power LED illuminating a digital mirror device (DMD). The use of a DMD features the quick generation of user definable measurement labels with high brightness and contrast. Due to working with different magnifications and examining surfaces with different properties, the size and the spacing of projected measurement labels has to be adaptable. During a measurement as many measurement labels as possible should be visible in the camera image. Therefore the acquisition of measurement data from bright and dark surface areas requires a high dynamic range. The measurement labels in the camera image are distinguished with a temporal coding. This identification enables the adaption of the brightness of each measurement label in the projection pattern. As a result the dynamic of the measurement system is expanded by the dynamic of the projection device.

In three-dimensional (3-D) measurement systems based on triangulation, a stereoscopic angle between two distinct viewpoints encodes the depth information. This angle generally generates some distortion known as keystone distortion. In this paper an original 3-D optical configuration in addition with a digital light processing system (DLP) is presented which prevents keystone distortion, resulting in less calibration and post-processing work. The DLP is used to project incoherent white light fringes pattern at high frame rate (30 Hz) on a specimen and a CCD camera dynamically captures this projected pattern. Using a phase shifting algorithm, the reconstruction of the 3-D shape of the specimen is finally computed. This optical configuration is based on an « out of axis » aperture method combined with an afocal design for both projection and acquisition. With the combination of these two properties, the stereoscopic effect is obtained without any keystone distortion and a unique objective lens instead of two in a classical 3-D measurement system is used. As a result of this unique objective lens, the global volume of the measurement device can be easily minimized. This system was designed with the optical software Zemax to limit geometric and chromatic aberrations and to control the diffraction effect. Experiments showed that high surface profile accuracy can be obtained on a variety of surfaces, allowing reverse engineering on micro-scaled objects or precise 3-D measurements of macro-scaled objects. Also a depth resolution value under 2 μm for a scanned area around 7.5x5.5mm is obtained under experimental conditions.

We report progress on the construction of an optical sectioning programmable array microscope (PAM) implemented with a digital micro-mirror device (DMD) spatial light modulator (SLM) utilized for both fluorescence illumination and detection. The introduction of binary intensity modulation at the focal plane of a microscope objective in a computer controlled pixilated mode allows the recovery of an optically sectioned image. Illumination patterns can be changed very quickly, in contrast to static Nipkow disk or aperture correlation implementations, thereby creating an optical system that can be optimized to the optical specimen in a convenient manner, e.g. for patterned photobleaching, photobleaching reduction, or spatial superresolution. We present a third generation (Gen-3) dual path PAM module incorporating the 25 kHz binary frame rate TI 1080p DMD and a newly developed optical system that offers diffraction limited imaging with compensation of tilt angle distortion.

By two-photon time-resolved confocal 4D-microscopy it is possible to image fluorescent objects at a high spatial and temporal resolution. The usage of femtosecond-laser light creates a two photon effect and therefore reduces bleaching of the fluorophore. With this technique 4D-visualization of dynamic processes in living cells is possible.

We report the development of a Digital-Micromirror-Device (DMD)-based Compressive Sampling Hyperspectral Imaging (CS-HSI) system. A DMD is used to implement CS measurement patterns, which modulate the intensity of optical images. The 3-dimensional (3-D) spatial/spectral data-cube of the original optical image is reconstructed from the CS measurements by solving a minimization problem. Two different solvers for the minimization problem were examined, including the GPSR (Gradient Projection for Sparse Reconstruction) and the TwIST (Two-step Iterative Shrinkage/Thresholding) methods. The performances of these two methods were tested and compared in terms of the image-reconstruction quality and the computer run-time. The image-formation process of the DMD-based spectral imaging system was analyzed using a Zemax model, based on which, an experimental prototype was built. We also present experimental results obtained from the prototype system.

Spectral transmission and reflectance are critical parameters for the evaluation of pigments, textiles and coatings on a number of product surfaces, including active displays. In this paper, we evaluate the usage of a DLP®- based spectral source as a tool in such observations noting its advantages not only in synthesizing individual band-passes but also full continua present in nature. We discuss how such capabilities are advantages for determining product effectiveness in conditions of real world usage as well as its limitations and future objectives.