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Applications of digital micromirror device for lidar are overviewed. A large Lagrange invariant value makes DMD as one of the attractive beam steering transmitter and receiver solutions for a time-of-flight lidar, especially with its an extended angular throw by synchronized pulsed laser illumination.

The recently reported “Angular Spatial Light Modulator” (ASLM) light engine, using pulsed illumination synchronized to a Digital Micromirror Device (DMD), shows significant promise to enhance pixel counts of Near-to-Eye Displays (NED) without increasing package volume, but requires an uncommon illumination driver. We present a field effect transistor based constant-current driver that is fast, compact, and scalable to RGB illumination. The digital-to-analog convertor modulates intensity on-the-fly for illumination-based multiplexing. The driver outputs 100 ns pulses, up to 24 kHz repetition rate. The circuit is demonstrated for two laser diodes and for two LEDs in an ASLM-enhanced pixel count display.

Desirable fields-of-view, angular resolutions, and form factors of near-to-eye AR/VR/MR displays require order-ofmagnitude increases in pixel count and pixel density of spatial light modulators (SLM). We present an in-plane angularspatial light modulation technique to increase the independent output display pixels of a DMD by three orders of magnitude to achieve gigapixel output from a sub-megapixel device. Pulsed illumination synchronized to a DMD’s micromirror actuation realizes pixel-implemented and diffraction-based angular modulation, and fine source array control increases angular selectivity. The gigapixel output is demonstrated in a 1440-perspective display, each perspective having the DMD’s full native XGA resolution, across a 43.9°×1.8° FOV viewing angle. 8-bit multi-perspective videos at 30 FPS are demonstrated, and pixel-implemented multi-focal-plane image generation is realized. Implications for near-to-eye displays are discussed.

We introduce our recent work on the occlusion-capable near-to-eye display. Our implementation uses only a single digital micromirror device (DMD) both for the real scene masking and virtual image display. The real scene imaging onto the DMD and the mixed scene projection toward the eye are achieved using a single optics of polarization-based double-path configuration. These single DMD and the shared optics feature contributes to the reduction of the overall system volume. In the presentation, we explain the principle and introduces our recent experimental results demonstrating 60Hz display of color virtual images with per-pixel occlusion in over 90% maximum occlusion ratio.

Orders-of-magnitude increases are desired in the pixel count and density of spatial light modulators (SLMs) for next-gen displays. We present in-plane and simultaneous angular-spatial light modulation by a micro electro mechanical system (MEMS)-based SLM, a digital micromirror device (DMD), to generate gigapixel output by time and angular multiplexing. Pulsed illumination synchronized to the micromirror actuation achieves pixel-implemented and diffraction-based angular modulation, and source multiplexing increases angular selectivity. We demonstrate 1440-perspective image output across a 43.9 ∘ × 1.8 ∘ FOV, 8-bit multi-perspective videos at 30 FPS, and multi-focal-plane image generation. We discuss scalability to terapixels and implications for near-to-eye displays.

Occlusion of a real scene by displayed virtual images mitigates incorrect depth cues and enhances image visibility in augmented reality applications. In this Letter, we propose a novel optical scheme for the occlusion-capable optical-see-through near-eye display. The proposed scheme uses only a single spatial light modulator, as the real-scene mask and virtual image display simultaneously. A polarization-based double-pass configuration is also combined, enabling a compact implementation. The proposed scheme is verified by optical experiments which demonstrate a 60 Hz red-green-blue video display with a 4-bit depth for each color channel and per-pixel dynamic occlusion of a 90.6% maximum occlusion ratio.

The “Angular Spatial Light Modulator” (ASLM) utilizes digital micromirror device (DMD) as a binary patterned programmable blazed grating to increase number of output pixels of a DMD by merging geometric and diffractive optical capabilities of the DMD. We demonstrate series of capabilities of the ASLM for beam and pattern steering. In particular, a single-chip beam steering lidar, an extended FOV display, a light-field projector, and a multi-view display which can be implemented into AR/VR systems. We also present our metrology results of wavefront distortion of DMD while micro mirrors are transitioning over between on and off states.

A single Digital Micromirror Device with a single illumination source projects multiple, independent patterns into corresponding directions across a nearly-doubled angular extent by time multiplexing and by nanosecond illumination pulse synchronization for a binary patterned programmable blazed grating. The resulting “Angular Spatial Light Modulator” (ASLM) system nearly-doubles the etendue of a DMD-type SLM and creates a multiplication factor for the output pixel count and effective pixel density. We demonstrate an extended FOV display, a light-field projector, and a multi-view display which can be implemented into AR/VR systems. We present an implementation update using the DLP7000 DMD, increasing output pixel count by and effective pixel density orders-of-magnitude beyond traditional SLM systems while achieving an extended field-of-view and/or eye-box size due to the increased etendue.

Small pixel pitch with a large array size is highly anticipated for solid-state lidar transmitter and receiver. We demonstrate 2D beam steering with reduced effective pixel pitch by harnessing transitional state of the mirror array.

High-speed, monolithic and MEMS-based lidar and a large pixel count micro display device for AR display optics leverages a Digital Micromirror Device with a pulsed illumination that simultaneous modulates light in space and angular domain.

Occlusion of real scene by displayed virtual images is an important feature of augmented reality display devices. We propose and demonstrate a novel occlusion scheme which uses a single digital micromirror device for the real scene masking and virtual image display.

The “Angular Spatial Light Modulator” (ASLM) achieves simultaneous angular and spatial light modulation at a plane by combining Digital Micromirror Device (DMD) based programmable blazed grating beam steering and binary pattern sequencing. The ASLM system multiplies the number of effective output pixels of the DMD for increased spatial and/or angular degrees of freedom, and nearly-doubles the etendue output of the DMD. We implement multiple illumination and projection schemes to demonstrate ASLM-based extended FOV display, light-field projection, and multi-view display. We also implement time-multiplexed pupil segmented illumination to extend the pattern steering to two dimensions.

Laser beam steering technology is essential for modern consumer and scientific optical devices including displays, microscopy, and Light Detection and Ranging (LIDAR) systems. Along with mechanical and completely non-mechanical beam steering approaches, Micro Electro Mechanical Systems (MEMS) are emerging beam steering devices that are especially suitable for LIDAR systems due to their fast scan rate and large scan angle. A class of MEMS-based devices, the Digital Micromirror Device (DMD), has been demonstrated for beam steering too by synchronizing its mirror movement to laser pulse. The tilt movement of micromirrors synchronizes with multiple pulses from multiple laser sources that sequentially redirect the pulses to multiple diffraction orders within μs. Based on the beam steering principle, multi-beam and multi-pulse beam steering in single-chip DMD LIDAR architecture provides a pathway to fast distance range finding having over 1M samples/s scan rate by leveraging a commercially available DMD, laser diodes and drivers. As a proof of concept, 3.34kHz and 15 points of range finding is demonstrated by using three pulsed laser diodes operating at 905nm. Additionally, multi-pulse beam steering for 5 points with an increased scanning rate of 6.63kHz demonstrates further enhancement of the scanning speed. The approach opens up a pathway to achieve a LIDAR system with a scanning rate over 1M samples/s while leveraging a state of the art DMD and a moderate number of laser sources.

The sampling rate and angular resolution of diffraction-based beam steering employing a digital micromirror device (DMD) can be simultaneously enhanced by at least an order of magnitude by synchronizing multiple nanosecond laser sources and pulses during each DMD actuation. A time-of-flight single-chip DMD lidar with three sources measures a range at a 3.34 kHz sampling rate and a 3.4° angular resolution across a 48° field of view. Employing multiple diffraction orders of the DMD improves the sampling rate at least by a factor of 2 and up to the number of diffraction orders supported by the DMD. An improved sampling rate of 6.68 kHz with a 9.6° angular resolution is experimentally demonstrated by illuminating micromirrors multiple times within a single transition period of the micromirrors.

A digital micromirror device (DMD) based holographic beam steering technique is reported that multiplexes fine-steering binary amplitude gratings with a coarse-steering programmable blazed grating. The angular spatial light modulation (ASLM) technique encodes the spatial pattern of the binary amplitude grating at the same plane as the angular modulation set by a phase map of the DMD-based beam steering technique. The beam steering technique is demonstrated at 532 nm and implemented into a 905 nm lidar system. The results of the lidar system tests are presented, achieving a 44° field-of-view, 0.9°×0.4° (H×V) angular resolution, 1 m max distance, 1.5 kHz sampling, and 7.8 FPS video. Scalability techniques are proposed, including max distance increases to over 100 m.

A novel method of beam steering, utilizing a mass-produced Digital Micromirror Device (DMD), enables a reliable single chip Light Detection and Ranging (LIDAR) with a large field of view while having minimum moving components. In the single-chip LIDAR, a short-pulsed laser is fired in a synchronous manner to the micromirrors rotation during the transitional state. Since the pulse duration of the laser pulse is substantially short compared to the transitional time of the mirror rotation, virtually the mirror array is frozen in transition at several discrete points, which forms a programmable and blazed grating. The programmable blazed grating efficiently redirects the pulsed light to a single diffraction order among several while employing time of flight measurement. Previously, with a single 905nm nanosecond laser diode and Si avalanche photo diode, a measurement accuracy and rate of

An imaging lidar system is presented which combines the high speed of a Digital Micromirror Device (DMD) and the higher range of a 1D collimated scanning output. The system employing 1D line object illumination along with DMD placed at focal plane enables flexible optimization of system metrics, such as field of view, angular resolution, maximum range distance and frame rate.

Spatial light modulators (SLMs) that operate in a phase modulation mode enable beam steering with higher diffraction efficiency compared to amplitude modulation mode, thus potentially be used for an efficient beam steering with no moving part. Currently, Twisted Nematic phase SLMs are widely adopted for phase modulation. However, their refresh rate is typically in the range below kilohertz. Recently, a new method for binary and spatial phase modulation using Digital Micromirror Device (DMD) was proposed by a research group in Germany. In the method, complemental self-images of DMD, corresponding to on- and off-pixels, are formed by two auxiliary optics while adding a pi phase shift between two images. The optics function as recycling of light in a coherent manner. The method enables over kilohertz refresh rate and higher diffraction efficiency in binary phase modulation mode to conventional amplitude binary modulation. As alternatives to the binary phase modulation, we propose and experimentally evaluated high-speed beam steering by DMD based on light recycling. In our experiment, with binary phase modulation mode, system output efficiency reaches 8%. It can be doubled to 16% with light recycling method. Efficiency is still low compared to the reported value of 27% without light recycling. To further increase beam efficiency, system loss was analysed.

A novel Digital Micromirror Device (DMD) based beam steering enables a single chip Light Detection and Ranging (LIDAR) system for discrete scanning points. We present increasing number of scanning point by using multiple laser diodes for Multi-beam and Single-chip DMD-based LIDAR.

A novel method of beam steering enables a large field of view and reliable single chip light detection and ranging (lidar) by utilizing a mass-produced digital micromirror device (DMD). Using a short pulsed laser, the micromirrors’ rotation is frozen in mid-transition, which forms a programmable blazed grating. The blazed grating efficiently redistributes the light to a single diffraction order, among several. We demonstrated time of flight measurements for five discrete angles using this beam steering method with a nano second 905nm laser and Si avalanche diode. A distance accuracy of < 1 cm over a 1 m distance range, a 48° full field of view, and a measurement rate of 3.34k points/s is demonstrated.