A Monolithic Forward-View MEMS Laser Scanner with Decoupled Raster Scanning and Enlarged Scanning Angle for Micro LiDAR Applications

This paper reports the design, fabrication, and characterization of a forward-view optical scanner realized by two vertical 2-axis MEMS mirrors integrated on a Silicon Optical Bench (SiOB). The mirror plate sizes of the first and second MEMS mirrors are 0.6× 0.7 mm2 and 1.2× 1.4 mm2, respectively. With the second MEMS mirror larger, the optical beam will not be truncated even during large-angle dynamic scanning. This dual-mirror configuration also enables multiple scanning modes, e.g., an enlarged 2D field of view (FoV) by combining the scans of both mirrors, and a decoupled raster scanning by actuating the two mirrors separately. Experiments show that the enlarged 2D FoV reached 28°(h) × 31° (v) and the FoV of the decoupled raster scanning reached 38°(h) × 8° (v). The measured first resonances of the two mirrors were 2.09 kHz and 0.85 kHz, respectively. The overall size of the MEMS scanner was only 5.3× 5.8× 3.0 mm3, and its weight was 20 mg. This 2-axis forward optical scanner is much smaller and lighter than other two-mirror scanning modules, giving it a great potential for applications in miniature LiDAR for micro-robotics. [2020-0081].