All-MEMS Lidar Using Hybrid Optical Architecture with Digital Micromirror Devices and a 2D-MEMS Mirror.

In a lidar system, replacing moving components with solid-state devices is highly anticipated to make a reliable and compact lidar system, provided that a substantially large beam area with a large angular extent as well as high angular resolution is assured for the lidar transmitter and receiver. A new quasi-solid-state lidar optical architecture employs a transmitter with a two-dimensional MEMS mirror for fine beam steering at a fraction of the degree of the angular resolution and is combined with a digital micromirror device for wide FOV scanning over 37 degree while sustaining a large aperture area of 140 mm squared. In the receiver, a second digital micromirror device is synchronized to the transmitter DMD, which enables a large FOV receiver. An angular resolution of 0.57°(H) by 0.23° (V) was achieved with 0.588 fps for scanning 1344 points within the field of view.

Gigapixel and 1440-perspective extended-angle display by megapixel MEMS-SLM.

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.

Single-chip holographic beam steering for lidar by a digital micromirror device with angular and spatial hybrid multiplexing.

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.

Fast laser beam steering into multiple diffraction orders with a single digital micromirror device for time-of-flight lidar.

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.

Occlusion-capable optical-see-through near-eye display using a single digital micromirror device.

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.

Wide-angle MEMS-based imaging lidar by decoupled scan axes.

We present an optical architecture for a scanning lidar in which a digital micromirror device (DMD) is placed at an intermediate image plane in a receiver to decouple the trade-offs between scan angle, scan speed, and aperture size of the lidar's transmitter and receiver. In the architecture, the transmitter with a galvo mirror and the receiver with a DMD scan the horizontal and vertical fields of view, respectively, to enable an increased field of view of 50°, centimeter transmitter beam diameter, and video frame rate range finding captures. We present our optimized system and discuss the adjustable parameter trade-offs.

Angular and spatial light modulation by single digital micromirror device for multi-image output and nearly-doubled étendue.

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 étendue 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.

Single chip lidar with discrete beam steering by digital micromirror device.

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.