Large Etendue Solid-State-Lidar with MEMS-Resonant Mirror Assisted Diffractive Beam Steering by Digital Micro Mirror Devices

Abstract

By combining a Micro Electro Mechanical System based resonant mirror and a Digital Micromirror Device, we demonstrate a large scan angle, fast scan rate, and high resolution beam steering for the lidar applications. Laser beam steering achieved with low-inertia MEMS-resonant mirror and DMD enables a complete solid-state lidar system without the bulky mechanical devices. The proposed optical architecture keeps large Etendue of DMD-based diffractive beam steering with a synchronized short-pulsed laser while maintaining high scan speed possible due to high speed pattern rate (>32 kHz) of DMD. The coarse scanning of MEMS-resonant mirror duplicated in each diffraction order provides high resolution and therefore yields increased angular resolution. Furthermore, thanks to its large aperture area, a second DMD is employed to actively match the sub FOVs of the transmitter which enables long range detection. A microcontroller is used to trigger and control all components and the time of flight value is measured and sent to Matlab. Matlab sorts the TOF values into an array according to the scanning sequence to demonstrate lidar image reconstruction where it represents target’s distance and location. System performance such as diffraction efficiency, distance accuracy, distance resolution, and angular resolution is evaluated. Also, we demonstrate lidar image of still targets and moving targets.