This PDF file contains the front matter associated with SPIE Proceedings Volume 10117, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The implementation of spatial light modulators (SLMs) in quantum gas experiments has allowed the realization of ever more complex trapping geometries. As ultracold atoms may be sensitive to perturbations of the trapping potential at the 1% level, the high contrast ratios of digital micromirror devices are proving advantageous for use in optical trapping. Our laboratory pursues configurable traps based on the direct (nearly diffraction limited) imaging of a digital micromirror device (DMD). We achieve highly flexible potentials using commercially available microscope objectives external to our vacuum chamber that directly project the DMD to the atom plane, producing optical traps over an area of 130 μm × 200 μm, with a resolution of 630(10) nm full width at half maximum (FWHM) at 532 nm illumination. We combine these potentials with a horizontally propagating TEM00 or TEM01 Hermite-Gaussian optical sheet that provides vertical confinement. With the dynamic control enabled by the maximum full-frame rate of 20 KHz and on-board storage of <13,000 frames of the DMD, we study the transport of atoms and superfluid dynamics in configurable trapping geometries. Using the fast frame rate of the DMD we also produce intermediate grey levels that complement half-toning techniques for producing optimized grayscale patterns.

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a DMD based approaches to realize energetically efficient light coupling into a multi-core fiber realizing a unique design for in-fiber optical neural networks. Neurons and synapses are realized as individual cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in Erbium-doped cores mimics synaptic interactions. In order to dynamically and efficiently couple light into the multi-core fiber a DMD based micro mirror device is used to perform proper beam shaping operation. The beam shaping reshapes the light into a large set of points in space matching the positions of the required cores in the entrance plane to the multi-core fiber.

Different chemical photo-reactive emulsions are used in screen printing for stencil production. Depending on the bandwidth, optical power and depth of field from the optical system, the reaction / exposure speed has a diverse value. In this paper, the emulsions get categorized and validated in a first step.

After that a mathematical model gets developed and adapted due to heuristic experience to estimate the exposure speed under the influence of digitally modulated ultra violet (UV) light. The main intention is to use the technical specifications (intended wavelength, exposure time, distance to the stencil, electrical power, stencil configuration) in the emulsion data sheet primary written down with an uncertainty factor for the end user operating with large projector arc lamps and photo films.

These five parameters are the inputs for a mathematical formula which gives as an output the exposure speed for the Computer to Screen (CTS) machine calculated for each emulsion / stencil setup. The importance of this work relies in the possibility to rate with just a few boundaries the performance and capacity of an exposure system used in screen printing instead of processing a long test series for each emulsion / stencil configuration.

Digital micromirror devices (DMDs) have found many scientific research applications. We present adaptive optics techniques exploiting the point spread function (PSF) of a DMD pixel to enhance the fidelity of image-projection-based laser machining. Femtosecond laser pulses with intensity profiles spatially shaped by a DMD were demagnified to a sample via a microscope objective, with ~10 DMD mirrors, each of width ~10µm, approximately projecting to the optical setup diffraction limit of ~1µm. A single DMD mirror then scales geometrically to dimensions well below the diffraction limit, permitting various techniques to enhance machining. By digitally shifting an intensity mask on the DMD between pulses while the sample remains static, machined features with resolutions below the single-exposure diffraction limit are produced (similar to pitch splitting multiple exposure techniques), with a reduction of <2.5x achieved in nickel. By combining digital image shifts with real-time sample image recognition algorithms, point-to-point positional accuracy is camera-resolution-limited (~500nm) rather than translation stage-limited. Furthermore, the PSF allows near-continuous intensity distributions rather than binary on/off intensity patterns, and have been used to produce variable-depth surface texturing (up to 40nm depth changes with 2µm period demonstrated in metals) features via single shots. Algorithms have been used to automate optical proximity corrections for arbitrary intensity masks in order to reduce machining errors due to optical filtering. These techniques are being combined to produce <1cm2 size, highly complex substrates for the production of biologically-friendly cell growth assays, with the viability of human bone stem cells on flexible substrates demonstrated.

This paper presents our research findings on high-speed 3D imaging using digital light processing (DLP) technologies. In particular, we compare two different sinusoidal fringe generation techniques using the DLP projection devices: direct projection of 8-bit computer generated sinusoidal patterns (a.k.a, the sinusoidal method), and the creation of sinusoidal patterns by defocusing binary patterns (a.k.a., the binary defocusing method). This paper mainly examines their performance on high-accuracy measurement applications under precisely controlled settings. Two different projection systems were tested in this study: the commercially available inexpensive projector, and the DLP development kit. Experimental results demonstrated that the binary defocusing method always outperforms the sinusoidal method if a sufficient number of phase-shifted fringe patterns can be used.

Optical 3D measurement techniques are state-of-the-art for highly precise, non-contact surface scanners - not only in industrial development, but also in near-production and even in-line configurations. The need for automated systems with very high accuracy and clear implementation of national precision standards is growing extremely due to expanding international quality guidelines, increasing production transparency and new concepts related to the demands of the fourth industrial revolution. The presentation gives an overview about the present technical concepts for optical 3D scanners and their benefit for customers and various different applications – not only in quality control, but also in design centers or in medical applications. The advantages of DMD-based systems will be discussed and compared to other approaches. Looking at today’s 3D scanner market, there is a confusing amount of solutions varying from lowprice solutions to high end systems. Many of them are linked to a very special target group or to special applications. The article will clarify the differences of the approaches and will discuss some key features which are necessary to render optical measurement systems suitable for industrial environments. The paper will be completed by examples for DMDbased systems, e. g. RGB true-color systems with very high accuracy like the StereoScan neo of AICON 3D Systems. Typical applications and the benefits for customers using such systems are described.

Traditional methods for calibrating structured light 3D imaging systems often suffer from various sources of error. By enabling our projector to both project images as well as capture them using the same optical path, we turn our DMD based projector into a dual-purpose projector and single-pixel camera (SPC). A coarse-to-fine SPC scanning technique based on coded apertures was developed to detect calibration target points with sub-pixel accuracy. Our new calibration approach shows improved depth measurement accuracy when used in structured light 3D imaging by reducing cumulative errors caused by multiple imaging paths.

To enable in-process inspection of industrial manufacturing processes, measuring devices need to fulfill time and space constraints, while also being robust to environmental conditions, such as high temperatures and electromagnetic fields. A new fringe projection profilometry system is being developed, which is capable of performing the inspection of filigree tool geometries, e.g. gearing elements with tip radii of 0.2 mm, inside forming machines of the sheet-bulk metal forming process. Compact gradient-index rod lenses with a diameter of 2 mm allow for a compact design of the sensor head, which is connected to a base unit via flexible high-resolution image fibers with a diameter of 1.7 mm. The base unit houses a flexible DMD based LED projector optimized for fiber coupling and a CMOS camera sensor. The system is capable of capturing up to 150 gray-scale patterns per second as well as high dynamic range images from multiple exposures. Owing to fiber crosstalk and light leakage in the image fiber, signal quality suffers especially when capturing 3-D data of technical surfaces with highly varying reflectance or surface angles. An algorithm is presented, which adaptively masks parts of the pattern to reduce these effects via multiple exposures. The masks for valid surface areas are automatically defined according to different parameters from an initial capture, such as intensity and surface gradient. In a second step, the masks are re-projected to projector coordinates using the mathematical model of the system. This approach is capable of reducing both inter-pixel crosstalk and inter-object reflections on concave objects while maintaining measurement durations of less than 5 s.

Printing of biomolecules on substrates has developed tremendously in the past few years. The existing methods either rely on slow serial writing processes or on parallelized photolithographic techniques where cumbersome mask alignment procedures usually impair the ability to generate multi-protein patterns. We recently developed a new technology allowing for high resolution multi protein micro-patterning. This technology named “Light-Induced Molecular Adsorption of Proteins (LIMAP)” is based on a water-soluble photo-initiator able to reverse the antifouling property of polymer brushes when exposed to UV light. We developed a wide-field pattern projection system based on a DMD coupled to a conventional microscope which permits to generate arbitrary grayscale patterns of UV light at the micron scale. Interestingly, the density of adsorbed molecules scales with the dose of UV light thus allowing the quantitative patterning of biomolecules. The very low non specific background of biomolecules outside of the UV-exposed areas allows for the sequential printing of multiple proteins without alignment procedures. Protein patterns ranging from 500 nm up to 1 mm can be performed within seconds, as well as gradients of arbitrary shapes. The range of applications of the LIMAP approach extends from the single molecule up to the multicellular scale with an exquisite control over local protein density. We show that it can be used to generate complex protein landscapes useful to study protein-protein, cell-cell and cell-matrix interactions.

Optical diffraction tomography (ODT), using an interferometric microscopy technique, can quantitatively measure the three-dimensional (3-D) refractive index (RI) distribution in transparent samples. ODT features unique advantages such as non-invasive, label-free, and high-resolution imaging; these capabilities have been increasingly explored recently, particularly in the field of cell biology. Normally, the RI map is reconstructed by solving the inverse scattering problem using more than one hundred holograms, which correspond to various angles of illumination. Current reconstruction methods all require that each hologram is created by only one illumination angle. Therefore, the number of measurements must be equal to the number of needed illumination angles, thus limiting ODT for video-rate or real-time imaging applications. To overcome this issue, we propose a new ODT system together with a new reconstruction algorithm. In the proposed optical system, the illumination is multiplexed by coding a digital micromirror device to display a series of Lee holograms, each of which corresponds to a plane wave of a specific incident angle in the sample plane. On the other hand, the reconstruction algorithm uses the beam propagation method to model the sample scattering process, as well as the error propagation method to train the artificial neural network which represents the RI distribution of the sample. This novel method is expected to reduce the measurement time by a factor of 4-6, which is crucial for video rate or even real time tomography imaging applications such as label-free 3-D imaging cytometry.

We present a biomedical application of Digital Micro-mirror technologies by adapting the DLP4500 module for quasi real-time intraoperative tumor imaging. Fluorescence image guided surgery has been increasingly popular due to its ability to inform surgeons about tumor boundaries in real-time. We have extended this technique to provide 3D tomographic images of a tumor, by adapting a DLP4500 device to illuminate the surgical field with spatially modulated near-infrared (NIR) light. We combine the digital micro-mirror device (DMD) with two simultaneously triggered CMOS cameras to realize a spatial frequency domain imaging system. Spatial frequency domain imaging utilizes sinusoidally modulated illumination at different spatial frequencies and three different phases; corresponding signals are readily demodulated, and analyzed to derive a 3D fluorescence image. Our DMD device is commercially modified and equipped with high-power (5W) NIR diode laser. We present a brief discussion of data acquisition using DLP4500 module, and corrections for spatial inhomogeneity and gamma adjust in order to create linear/desired sinusoidal illumination of NIR light. We discuss results from a tissue phantom study and in-vivo experiments.

Localization based super resolution images of a biological sample is generally achieved by using high power laser illumination with long exposure time which unfortunately increases photo-toxicity of a sample, making super resolution microscopy, in general, incompatible with live cell imaging. Furthermore, the limitation of photobleaching reduces the ability to acquire time lapse images of live biological cells using fluorescence microscopy. Digital Light Processing (DLP) technology can deliver light at grey scale levels by flickering digital micromirrors at around 290 Hz enabling highly controlled power delivery to samples. In this work, Digital Micromirror Device (DMD) is implemented in an inverse Schiefspiegler telescope setup to control the power and pattern of illumination for super resolution microscopy. We can achieve spatial and temporal patterning of illumination by controlling the DMD pixel by pixel. The DMD allows us to control the power and spatial extent of the laser illumination. We have used this to show that we can reduce the power delivered to the sample to allow for longer time imaging in one area while achieving sub-diffraction STORM imaging in another using higher power densities.

Conventional temporal focusing-based multiphoton excitation microscopy (TFMPEM) can offer widefield optical sectioning with an axial excitation confinement (AEC) of a few microns. Herein, a developed TFMPEM with a digital micromirror device (DMD), acting as the blazed grating for light spatial dispersion and simultaneous patterned illumination, has been extended to implement spatially modulated illumination at structured frequency and orientation. By implementing the spatially modulated illumination, the beam coverage at the back-focal aperture of the objective lens can be increased. As a result, the AEC can be condensed from 3.0 μm to 1.5 μm in full width at half maximum for a 2-fold enhancement. Furthermore, by using HiLo microscopy with two structured illuminations at the same spatial frequency but different orientation, biotissue images according to the structured illumination with condensed AEC is obviously superior in contrast and scattering suppression.

In this work, we explore the use of compressive sensing for the rapid acquisition of two-dimensional optical spectra that encodes the electronic structure and ultrafast dynamics of condensed-phase molecular species. Specifically, we have developed a means to combine multiplexed single-element detection and single-shot and phase-resolved two-dimensional coherent spectroscopy. The method described, which we call Single Point Array Reconstruction by Spatial Encoding (SPARSE) eliminates the need for costly array detectors while speeding up acquisition by several orders of magnitude compared to scanning methods. Physical implementation of SPARSE is facilitated by combining spatiotemporal encoding of the nonlinear optical response and signal modulation by a high-speed digital micromirror device. We demonstrate the approach by investigating a well-characterized cyanine molecule and a photosynthetic pigment-protein complex. Hadamard and compressive sensing algorithms are demonstrated, with the latter achieving compression factors as high as ten. Both show good agreement with directly detected spectra. We envision a myriad of applications in nonlinear spectroscopy using SPARSE with broadband femtosecond light sources in so-far unexplored regions of the electromagnetic spectrum.

Coded aperture compressive spectral imagers sense a three-dimensional cube by using two-dimensional projections of the coded and spectrally dispersed source. These imagers systems often rely on FPA detectors, SLMs, micromirror devices (DMDs), and dispersive elements. The use of the DMDs to implement the coded apertures facilitates the capture of multiple projections, each admitting a different coded aperture pattern. The DMD allows not only to collect the sufficient number of measurements for spectrally rich scenes or very detailed spatial scenes but to design the spatial structure of the coded apertures to maximize the information content on the compressive measurements. Although sparsity is the only signal characteristic usually assumed for reconstruction in compressing sensing, other forms of prior information such as side information have been included as a way to improve the quality of the reconstructions. This paper presents the coded aperture design in a compressive spectral imager with side information in the form of RGB images of the scene. The use of RGB images as side information of the compressive sensing architecture has two main advantages: the RGB is not only used to improve the reconstruction quality but to optimally design the coded apertures for the sensing process. The coded aperture design is based on the RGB scene and thus the coded aperture structure exploits key features such as scene edges. Real reconstructions of noisy compressed measurements demonstrate the benefit of the designed coded apertures in addition to the improvement in the reconstruction quality obtained by the use of side information.

Current and upcoming massive astronomical surveys are expected to discover a torrent of objects, which need groundbased follow-up observations to characterize their nature. For transient objects in particular, rapid early and efficient spectroscopic identification is needed. In particular, a small-field Integral Field Unit (IFU) would mitigate traditional slit losses and acquisition time. To this end, we present the design of a Digital Micromirror Device (DMD) multi-purpose spectrograph camera capable of running in several modes: traditional longslit, small-field patrol IFU, multi-object and full-field IFU mode via Hadamard spectra reconstruction. AIUC Optical multi-purpose CAMera (AIUCOCAM) is a low-resolution spectrograph camera of R~1,600 covering the spectral range of 0.45-0.85 μm. We employ a VPH grating as a disperser, which is removable to allow an imaging mode. This spectrograph is envisioned for use on a 1-2 m class telescope in Chile to take advantage of good site conditions. We present design decisions and challenges for a costeffective robotized spectrograph. The resulting instrument is remarkably versatile, capable of addressing a wide range of scientific topics.

In recent years, there has been an increasing interest in miniature spectrometers for research and development. Especially, filter-array-based spectrometers have advantages of low cost and portability, and can be applied in various fields such as biology, chemistry and food industry. Miniaturization in optical filters causes degradation of spectral resolution due to limitations on spectral responses and the number of filters. Nowadays, many studies have been reported that the filter-array-based spectrometers have achieved resolution improvements by using digital signal processing (DSP) techniques. The performance of the DSP-based spectral recovery highly depends on the prior information of transmission functions (TFs) of the filters. The TFs vary with respect to an incident angle of light onto the filter-array. Conventionally, it is assumed that the incident angle of light on the filters is fixed and the TFs are known to the DSP. However, the incident angle is inconstant according to various environments and applications, and thus TFs also vary, which leads to performance degradation of spectral recovery. In this paper, we propose a method of incident angle estimation (IAE) for high resolution spectral recovery in the filter-array-based spectrometers. By exploiting sparse signal reconstruction of the L1- norm minimization, IAE estimates an incident angle among all possible incident angles which minimizes the error of the reconstructed signal. Based on IAE, DSP effectively provides a high resolution spectral recovery in the filter-array-based spectrometers.

Multi-pixel imaging devices such as CCD, CMOS and Focal Plane Array (FPA) photo-sensors dominate the imaging world. These Photo-Detector Array (PDA) devices certainly have their merits including increasingly high pixel counts and shrinking pixel sizes, nevertheless, they are also being hampered by limitations in instantaneous dynamic range, inter-pixel crosstalk, quantum full well capacity, signal-to-noise ratio, sensitivity, spectral flexibility, and in some cases, imager response time. Recently invented is the Coded Access Optical Sensor (CAOS) Camera platform that works in unison with current Photo-Detector Array (PDA) technology to counter fundamental limitations of PDA-based imagers while providing high enough imaging spatial resolution and pixel counts. Using for example the Texas Instruments (TI) Digital Micromirror Device (DMD) to engineer the CAOS camera platform, ushered in is a paradigm change in advanced imager design, particularly for extreme dynamic range applications.

Imaging systems based on microstructured illumination and single-pixel detection offer several advantages over conventional imaging techniques. They are an effective method for imaging through scattering media even in the dynamic case. They work efficiently under low light levels, and the simplicity of the detector makes it easy to design imaging systems working out of the visible spectrum and to acquire multidimensional information. In particular, several approaches have been proposed to record 3D information. The technique is based on sampling the object with a sequence of microstructured light patterns codified onto a programmable spatial light modulator while light intensity is measured with a single-pixel detector. The image is retrieved computationally from the photocurrent fluctuations provided by the detector. In this contribution we describe an optical system able to produce full-color stereoscopic images by using few and simple optoelectronic components. In our setup we use an off-the-shelf digital light projector (DLP) based on a digital micromirror device (DMD) to generate the light patterns. To capture the color of the scene we take advantage of the codification procedure used by the DLP for color video projection. To record stereoscopic views we use a 90° beam splitter and two mirrors, allowing us two project the patterns form two different viewpoints. By using a single monochromatic photodiode we obtain a pair of color images that can be used as input in a 3-D display. To reduce the time we need to project the patterns we use a compressive sampling algorithm. Experimental results are shown.

A new paradigm of digital projection is on the horizon, based on innovative emissive screen that are made fully transparent. It can be readily applied and convert any surface to a high image quality emissive digital display, without affecting the surface appearance. For example, it can convert any glass window or windshield to completely see-through display, with unlimited field of view and viewing angles. It also enables a scalable and economic projection display on a pitch-black emissive screen with black level and image contrast that rivals other emissive displays such as plasma display or OLED.