High-speed Digital Micromirror Device Research Articles

Snapshot compressive structured illumination microscopy.

We propose a snapshot compressive structured illumination microscopy (SoSIM) system to increase the number of reconstructed resolution-enhanced (RE) images per second and reduce the data bandwidth by capturing compressed measurements. In this system, multiple low-resolution images are encoded by a high-speed digital micro-mirror device with random binary masks. These images are then captured by a low-speed camera as a snapshot compressed measurement. Following this, we adopt an efficient deep neural network to reconstruct nine images with different structured illumination patterns from a single measurement. The reconstructed images are then combined into a single-frame RE image using the method of spectral synthesis in the frequency domain. When the camera operates at 100 frames per second (fps), we can eventually recover dynamic RE videos at the same speed with 100 fps.

Video-rate dual-modal photoacoustic and fluorescence imaging through a multimode fibre towards forward-viewing endomicroscopy

Multimode fibres (MMFs) are becoming increasingly attractive in optical endoscopy as they promise to enable unparallelled miniaturisation, spatial resolution and cost. However, high-speed imaging with wavefront shaping has been challenging. Here, we report the development of a video-rate dual-modal photoacoustic (PA) and fluorescence microscopy probe with a high-speed digital micromirror device (DMD) towards forward-viewing endomicroscopy. Optimal DMD patterns were obtained using a real-valued intensity transmission matrix algorithm to raster-scan a 1.5 μm-diameter focused beam at the distal fibre tip for imaging. The PA imaging speed and spatial resolution were varied from ∼2 to 57 frames per second and from 1.7 to 3 μm, respectively. Further, high-fidelity PA images of carbon fibres and mouse red blood cells were acquired at unprecedented speed. The capability of dual-modal imaging was demonstrated with phantoms. We anticipate that with further miniaturisation of the ultrasound detector, this probe could be integrated into medical needles to guide minimally invasive procedures.

Bat algorithm-enabled binary optimization for scattered light focusing

We introduce a novel global optimization algorithm–bat algorithm (BA) for wavefront shaping to focus light through highly scattered media. Compared with the well-known genetic algorithm, BA-based binary wavefront shaping achieves a higher enhancement with less time in noisy environments, which is validated by simulation and experiment. Using a high-speed digital micromirror device, the BA enables quick formation of single or multiple focal spots through a highly scattering layer. The BA offers a competitive algorithm for wavefront shaping in turbid media, which might benefit biomedical imaging in deep tissues.

Fourier single-pixel reconstruction of a complex amplitude optical field.

Based on a Fourier single-pixel imaging (SPI) technique and interference between an unknown field and a reference beam, we implement amplitude and phase reconstruction of the unknown complex field. In this Letter, we use a chessboard pattern to divide the unknown field into the signal and reference parts. A high-speed digital micro-mirror device is used to modulate the relative phase between the reference and signal fields, and the SPI method is used to acquire the Fourier spectrum of the signal field. We experimentally reconstruct a 103×103-pixel complex amplitude field with a resolution of 68.4μm. The single-pixel real-time wavefront detection is also implemented in the rate of four frames per second.

Complex wavefront reconstruction with single-pixel detector

Wavefront sensing is an essential tool in wide research areas. However, the auxiliary reference beam and the pixel-array detector are indispensable in most of the wavefront sensing schemes. Here, we introduce a method to simultaneously measure the amplitude and the phase of an unknown complex wavefront using a single-pixel detector. A checkerboard pattern is used to sample the complex field and the reference beam, which makes sure that our scheme is free from the intensity distribution of the unknown complex amplitude field. In the experiments, various complex fields with discretized pixels of 64 × 64 and 128 × 128 at the corresponding pixel size of 109.44 × 109.44 μm2 and 54.72 × 54.72 μm2 are reconstructed. Using a high-speed digital micromirror device, we implement the complex wavefront reconstruction of 32 × 32 pixels with a frame rate of 6 Hz.

Shaping the Wavefront of Incident Light with a Strong Robustness Particle Swarm Optimization Algorithm☆☆Supported by the National Key Research and Development Program of China under Grant No 2017YFB1104500, the Natural Science Foundation of Beijing under Grant No 7182091, the National Natural Science Foundation of China under Grant No 21627813, and the Fundamental Research Funds for the Central Universities under Grant

We demonstrate a modified particle swarm optimization (PSO) algorithm to effectively shape the incident light with strong robustness and short optimization time. The performance of the modified PSO algorithm and genetic algorithm (GA) is numerically simulated. Then, using a high speed digital micromirror device, we carry out light focusing experiments with the modified PSO algorithm and GA. The experimental results show that the modified PSO algorithm has greater robustness and faster convergence speed than GA. This modified PSO algorithm has great application prospects in optical focusing and imaging inside in vivo biological tissue, which possesses a complicated background.

Expanded Exit-Pupil Holographic Head-Mounted Display With High-Speed Digital Micromirror Device

Recently, techniques involving head-mounted displays (HMDs) have attracted much attention from academia and industry owing to the increased demand for virtual reality and augmented reality applications. Because HMDs are positioned near to users’ eyes, it is important to solve the accommodation-vergence conflict problem to prevent dizziness. Therefore, holography is considered ideal for implementing HMDs. However, within the Nyquist region, the accommodation effect is limited by the space-bandwidth-product of the signal, which is determined by the sampling number of spatial light modulators. In addition, information about the angular spectrum is duplicated over the Fourier domain, and it is necessary to filter out the redundancy. The size of the exit-pupil of the HMD is limited by the Nyquist sampling theory. We newly propose a holographic HMD with an expanded exit-pupil over the Nyquist region by using the time-multiplexing method, and the accommodation effect is enhanced. We realize time-multiplexing by synchronizing a high-speed digital micromirror device and a liquid-crystal shutter array. We also demonstrate the accommodation effect experimentally.

In vivo retinal imaging for fixational eye motion detection using a high-speed digital micromirror device (DMD)-based ophthalmoscope.

Retinal motion detection with an accuracy of 0.77 arcmin corresponding to 3.7 µm on the retina is demonstrated with a novel digital micromirror device based ophthalmoscope. By generating a confocal image as a reference, eye motion could be measured from consecutively measured subsampled frames. The subsampled frames provide 7.7 millisecond snapshots of the retina without motion artifacts between the image points of the subsampled frame, distributed over the full field of view. An ophthalmoscope pattern projection speed of 130 Hz enabled a motion detection bandwidth of 65 Hz. A model eye with a scanning mirror was built to test the performance of the motion detection algorithm. Furthermore, an in vivo motion trace was obtained from a healthy volunteer. The obtained eye motion trace clearly shows the three main types of fixational eye movements. Lastly, the obtained eye motion trace was used to correct for the eye motion in consecutively obtained subsampled frames to produce an averaged confocal image correct for motion artefacts.

Holographic 3D display observable for multiple simultaneous viewers from all horizontal directions by using a time division method.

A holographic three-dimensional display system with a viewing angle of 360°, by using a high-speed digital micromirror device (DMD), has been proposed. The wavefront modulated by the DMD enters a rotating mirror tilted vertically downward. The synchronization of the rotating mirror and holograms displayed on the DMD allows for the reconstruction of a wavefront propagating in all horizontal directions. An optical experiment has been demonstrated in order to verify our proposed system. Binocular vision is realized from anywhere within the horizontal plane. Our display system enables simultaneous observation by multiple viewers at an extremely close range.

Laser Doppler phase shifting using a high-speed digital micromirror device

Here we demonstrate the use of a binary spatial light modulator (Texas Instruments Digital Micromirror Device) to impart a phase shift to the beams of a laser Doppler velocimeter. Advantages of this approach to laser Doppler phase shifting include low cost, low power consumption, a precisely known phase-stepping frequency and the capability of working with a broad range of optical wavelengths. In the implementation shown here velocities of order 1cm/s are measured.

Approaching real‐time terahertz imaging with photo‐induced coded apertures and compressed sensing

Photo-induced coded-aperture imaging (PI-CAI) based on compressed sensing (CS) at 590 GHz using a WR-1.5 (500-750 GHz) vector network analyser is demonstrated. For a 256-pixel (16 × 16) frame, the acquisition time can be reduced by 40%, as compared with PI-CAI without CS, while maintaining high imaging quality. On the basis of this approach, it is envisioned that real-time (26 fps) THz imaging with 1000 pixels (32 × 32) can be realised using high-speed digital micromirror device chipsets and optimised data-acquisition software.

Vertical viewing angle enhancement for the 360 degree integral-floating display using an anamorphic optic system.

We propose a 360degree integral-floating display with an enhanced vertical viewing angle. The system projects two-dimensional elemental image arrays via a high-speed digital micromirror device projector and reconstructs them into 3D perspectives with a lens array. Double floating lenses relate initial 3D perspectives to the center of a vertically curved convex mirror. The anamorphic optic system tailors the initial 3D perspectives horizontally and vertically disperse light rays more widely. By the proposed method, the entire 3D image provides both monocular and binocular depth cues, a full-parallax demonstration with high-angular ray density and an enhanced vertical viewing angle.

Resolution enhancement of integral‐imaging three‐dimensional display using directional elemental image projection

Abstract— A new approach to resolution enhancement of an integral‐imaging (II) three‐dimensional display using multi‐directional elemental images is proposed. The proposed method uses a special lens made up of nine pieces of a single Fresnel lens which are collected from different parts of the same lens. This composite lens is placed in front of the lens array such that it generates nine sets of directional elemental images to the lens array. These elemental images are overlapped on the lens array and produce nine point light sources per each elemental lens at different positions in the focal plane of the lens array. Nine sets of elemental images are projected by a high‐speed digital micromirror device and are tilted by a two‐dimensional scanning mirror system, maintaining the time‐multiplexing sequence for nine pieces of the composite lens. In this method, the concentration of the point light sources in the focal plane of the lens array is nine‐times higher, i.e., the distance between two adjacent point light sources is three times smaller than that for a conventional II display; hence, the resolution of three‐dimensional image is enhanced.

Digital holographic three-dimensional display of <inline-formula><math display="inline" overflow="scroll"><mrow><mn>50</mn><mtext>-</mtext><mi>Mpixel</mi></mrow></math></inline-formula> holograms using a two-axis scanning mirror device

The current limitation in pixel count of a single spatial light modulator SLM is one of the technological hurdles that must be over- come to produce a holographic 3-D display with a large image size. A conventional approach is to tile subholograms that are predivided from a reconfigurable computer-generated hologram CGH with a high pixel count. We develop a new approach to achieve a 50 Mpixel display by tiling reconstructed subholograms computed from a predivided 3-D ob- ject. The tiling is done using a two-axis scanning mirror device with a new tiling sequence. A shutterless system design is also implemented to enable effective tiling of subholograms. A high-speed digital micromirror device DMD at 6 kHz with 19201080 pixels is utilized to reconstruct the subholograms. Our current system shows the potential to tile up to 120 subholograms, which corresponds to about 240 Mpixels. The ap- proach we demonstrate gives a scalable solution to achieve a gigapixel- level display in the future. © 2010 Society of Photo-Optical Instrumentation

Differential high-speed digital micromirror device based fluorescence speckle confocal microscopy

We report a differential fluorescence speckle confocal microscope that acquires an image in a fraction of a second by exploiting the very high frame rate of modern digital micromirror devices (DMDs). The DMD projects a sequence of predefined binary speckle patterns to the sample and modulates the intensity of the returning fluorescent light simultaneously. The fluorescent light reflecting from the DMD's "on" and "off" pixels is modulated by correlated speckle and anticorrelated speckle, respectively, to form two images on two CCD cameras in parallel. The sum of the two images recovers a widefield image, but their difference gives a near-confocal image in real time. Experimental results for both low and high numerical apertures are shown.

2P2-E15 高速DMDプロジェクタを用いた動きボケの少ない映像投影(VRとインタフェース)

This paper describes a video projection system with reduced motion blur using a high-speed DMD (Digital Micromirror Device) projector. Conventional DMD devices suffer from motion artifacts, which are observed as blurred moving objects, because of eye motion. A DMD projector displays grayscale brightness by pulse-width modulation and requires many patterns for a frame. In a motion video, image positions are updated per frame, which causes large motion blur. To address this issue, we propose a method in which image positions are updated per pattern. To examine whether the proposed method can give an improved result, an evaluation experiment was conducted. The result of the t-test applied to this evaluation experiment proved that there was significant difference at p<.001 between the proposed method and the conventional one, and the motion blur reduction was successful

Development of DMD Reflection-Type CCD Camera for Phase Analysis and Shape Measurement

Phase-shifting method effectively attains high resolution and high accuracy in analyzing phase information on a projected grating. It is difficult to apply dynamically, however, because it usually requires several images. We developed a camera based on digital micromirror device (DMD) technology for high-speed phase analysis and shape measurement, called a DMD reflection-type CCD camera or DMD camera. Implementing DMD technology enables accurate control of intensity reaching the imaging detector of a camera. Moiré is used to adjust pixel-to-pixel correspondence highly accuracy. We introduce a controllable high-speed DMD operation board to control DMD mirrors at high-speed, so each DMD mirror operates as a controllable high-speed shutter for the corresponding CCD pixel. In experiments with an application, we conducted DMD integrated phase-shifting method using correlation to analyze phase distributions of projected gratings from images recorded by the DMD camera. We then discuss principles and experimental results under dynamic conditions. This paper is a revised version of one presented at the SPIE International Symposium on Optomechatronic Technologies (ISOT 2005), December 4-7, 2005 at the Sapporo Convention Center, Japan. That paper appears in SPIE Proceedings Vol.6049, 60490I.