Biaxial resonant MEMS mirrors with large field of view for LiDAR systems

Future industrial production will be characterized by the collaborative work of humans and robots, sharing the same factory area (almost) simultaneously. To realize this cooperation in an efficient and safe way, powerful LiDAR systems with a large field of view are essential in order to permanently supervise the human-robot interaction and give instructions for the robotic motion based on the current human behavior. Piezoelectrically driven, resonant MEMS mirrors are often at the heart of such LiDAR systems, due to their high speed, electric power efficiency, and compactness. However, not only the achievable optical field of view, but also the resonant frequencies of the mirror eigenmodes are key parameters that need to be suitable for the specific application scenario and the system components, such as the laser. In this study, we present the FEM-simulation-based development of biaxial MEMS mirrors with 3 mm aperture, specifically optimized for the use in a LiDAR system to monitor and control the human-robot collaboration. The gimbal-less mirrors of Design 1 (and Design 2) exhibit a diminishing coupling between the two resonant modes at 2.4 kHz (2.3 kHz) and 5.6 kHz (5.0 kHz). This enables the individual control of the mirror movement along the two orthogonal axes and a very good light density. The two presented mirrors realize scanned field of views of 60 degrees x 32 degrees and 42 degrees x 42 degrees rectangles, respectively, showing almost no pincushion distortions. Due to the reduced mechanical coupling and mutual influence, the sensing signals possess a high signal-to-noise ratio, enabling the precise determination of the mirror position.