Wide-angle, high-resolution three-dimensional (3D) imaging using non-mechanical beam steering

A common non-mechanical method for generating wide-angle, high-resolution 3D images is to use two multi-megapixel cameras to capture wide field of view (FOV) stereoscopic images. Such images, when viewed by a human, provide detailed 3D information that can easily be used to plot a course or avoid an obstacle. For a robot or autonomous vehicle, however, it takes considerable computation to convert the imagery into data that can be used for navigation and control. This processing demand can be an issue for small platforms needing real-time 3D data in a dynamic operating environment. With 3D time-of-flight (TOF) sensors (indirect TOF cameras and lidars), depth information can be acquired with minor processing, but high resolution over a large angle is not readily and inexpensively achieved without steering the illumination source, or receiver, or both. Mechanical beam steering systems (including MEMS) have been the answer to this problem for many years, but a truly no-moving-parts solution, using polarization gratings (PGs) combined with liquid crystal (LC) switches,1 offers some unique features while reducing costs when scaled to large volume manufacturing. This paper discusses the advancement and demonstration of wide-angle, large-aperture PG-based scanners incorporated into TOF sensors to improve resolution and range.