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

Abstract

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 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 1.2×1.4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 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 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , 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.