Multi-segment tapered optical mirror for MEMS LiDAR application

In this work, we present a novel and simple optical solution for MEMS LiDARs. The idea is based on increasing the collection optics throughput by removing the MEMS mirror from the path of the collected light, while inserting a multisegment tapered structure to collect the light from a wide angle. The tapered also converts the large size optical spot captured to a small area compatible with the requirement of low detector noise dimensions. The expected improvement in the collected power is analyzed versus the tapering angle of a single tapered structure. A multi-segment optical system, or multiple tapered structure arranged in parallel, is also introduced allowing for the optimization of the acceptance angle and the power improvement ratio. Using a 3-segment mirror, the expected improvement is about 15x with an acceptance angle of +/- 30 degrees. The design of a single element taper section is fabricated using aluminum-coated acrylic and tested experimentally showing an improvement of about 7x in the coupled power through an angle of +/- 10 degrees in good agreement with the theoretical expectations.