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.
Proc. SPIE. 11765, Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) II
KEYWORDS: Light emitting diodes, Modulation, Multiplexing, Semiconductor lasers, Field effect transistors, Digital micromirror devices, Field emission displays, Prototyping, Resolution enhancement technologies, RGB color model
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.
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.
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 étendue 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 étendue.
Bullet-shaped LEDs are commonly used in self-luminous traffic signs as LED-dotted matrices due to their low cost, simplicity, robustness, and ease of installation. We proposed a simple low-cost method that creates a model suitable for the high manufacturing tolerance found in bullet-shaped LEDs. The method starts from measuring multiple one-dimensional angular intensity patterns at interested distances from multiple LEDs to form a database, including distances at 10, 15, 20, 25, 35, 50, and 100 mm. Their normalized cross-correlations are then calculated to find the batch that has the most similarity and base our model off that batch. Finally, we validate the model via Monte Carlo simulations in comparison to the original one-dimensional angular intensity patterns in the database. The platform demonstrated to obtain an average of 99% in normalized cross correlation between different batches of the same model LED, and a model of that LED is currently under development.