Patent ID: 11394175

Abstract:
A proximity sensor which uses very narrow divergent beams from Vertical Cavity Surface Emitting Laser (VCSEL) for the illumination source is disclosed. Narrow divergent beams in the range 0.5 to 10 degrees can be achieved to provide high proximity sensing accuracy in a small footprint assembly. One approach to reducing the beam divergence is to increase the length of the VCSEL resonant cavity using external third mirror. A second embodiment extends the length of the VCSEL cavity by modifying the DBR mirrors and the gain region. Optical microlenses can be coupled with the VCSEL to collimate the output beam and reduce the beam divergence. These can be separate optical elements or integrated with the VCEL by modifying the substrate output surface profile or an added a transparent layer. These methods of beam divergence reduction are incorporated into various embodiment configurations to produce a miniature proximity sensor suitable for cell phones and tablets.