System integration of hybrid large aperture micro scanner array for fast scanning LiDAR sensors

This article presents the design and system integration of a hybrid MEMS scanner array (MSM) developed for a real time 3D imaging with a panoramic optical field of view (FOV) of 360° × 60° (horizontal × vertical). The pulsed ToF LiDAR system targets on a distance measurement range of 100 m with a video-like frame rate of 10 Hz. The fast vertical scan axis is realized by a synchronous scanning MSM array with large receiver aperture. It increases the scanning rate to 3200 Hz, which is four times faster in comparison to state-of-the-art fast macroscopic polygon scanning systems used in actual LIDAR systems. A hybrid assembly of frequency selected scanner elements was chosen instead of a monolithic MEMS array to guaranty high yield of MEMS fabrication and a synchronous operation of all resonant MEMS elements at 1600 Hz with large FOV of 60°. The hybrid MSM array consists of a separate emitting mirror for laser scanning of the target and 22 reception elements resulting in a large reception aperture of Deff = 23mm. All MSM are driven in parametric resonance to enable a fully synchronized operation of all individual MEMS scanner elements. Therefore, piezo-resistive position sensors are integrated inside the MEMS chip used for position feedback of driving control. The paper focus on the MEMS system integration including the synchronized operation of multiple MEMS scanning elements. It presents technical details to meet the narrow tolerance budgets for (i) micro assembly and (ii) synchronous driving of multiple MEMS scanner elements.