Investigations and optimization of positioning dynamics of a vectorial MEMS scanning mirror

Miniaturized vectorial beam steering mirrors are required in numerous applications like (i) LIDAR, (ii) diagnostic imaging or (iii) miniaturized therapeutic laser systems. This article presents an update on electrostatically driven, 2D quasi-static vectorial MEMS scanning mirrors with monolithically integrated position sensors. These vectorial MEMS scanners have been specially optimized to meet the requirements of compact therapeutic photocoagulation laser systems used to treat retinal eye diseases. These therapeutic laser systems require a highly miniaturized MEMS scanning system to position the treatment laser vectorially with precision and speed, with a positioning time of ≤ 3 ms. To measure and control the actual beam position piezoresistive position sensors are monolithically integrated into the MEMS chips. In this paper we investigate and optimize the open loop positioning dynamics of the vectorial MEMS scanning mirrors by increasing (i) the eigen-frequency and (ii) the damping of the MEMS actuator and (iii) optimizing the open-loop control. Finally, we demonstrate the flexibility and usability of various dynamic scan patterns enabled by the new vectorial MEMS scanning mirrors, which makes them interesting for a variety of medical and sensorics laser applications.