Qualitative real-time range extraction for preplanned scene partitioning using laser beam coding

This paper proposes a novel technique to extract range using a phase-only filter for a laser beam. The workspace is partitioned according to M meaningful preplanned range segments, each representing a relevant range segment in the scene. The phase-only filter codes the laser beam into M different diffraction patterns, corresponding to the predetermined range of each segment. Once the scene is illuminated by the coded beam, each plane in it would irradiate in a pattern corresponding to its range from the light source. Thus, range can be extracted at acquisition time. This technique has proven to be very efficient for qualitative real-time range extraction, and is mostly appropriate to handle mobile robot applications where a scene could be partitioned into a set of meaningful ranges, such as obstacle detection and docking. The hardware consists of a laser beam, a lens, a filter, and a camera, implying a simple and cost-effective technique.