In this article, a low power and compact scanning micromirror for LiDAR (light detection and ranging) system is designed, fabricated, and characterized. A 5 mm-diameter scanning micromirror is electromagnetically actuated with multi-turn copper winding formed on the gimbal and magnet assembly formed under the silicon substrate. A unique magnetic circuit that generates an asymmetric radial magnetic field has been designed and analyzed. A series-connected double spring-mass system consisting of a gimbal and a mirror plate has been used to amplify the deflection angle. An analytic model of the system has been developed and verified with finite element analysis. Also, a reinforcement rim structure is utilized to reduce the dynamic deformation of the reflective surface down to 19.3 nm _rms . An optical scan angle of 30 ^o is obtained at 690 Hz, 17.4 mA _rms input, and corresponding power consumption is 7.8 mW _rms . A prototype scanning system with 180 ^o x 30 ^o field-of-view has been demonstrated with fabricated scanning micromirror as the vertical scanner. The proposed approach provides a simple and compact design for a large diameter scanning micromirror, which can potentially be utilized in various LiDAR applications.

In this paper, the newly developed 3D-constructed AlScN piezoelectric MEMS mirror is presented. This paper describes the structure and driving mechanism of the proposed mirror device, covering its driving characteristics in both quasi-static and resonant scan modes. Particularly, this paper deals with various achievable scan patterns including 1D line scan and 2D area scan capabilities and driving methods to realize each scanning strategy. Bidirectional quasi-static actuation along horizontal, vertical, and diagonal scanning directions was experimentally characterized and even under a low voltage level of ±20 V, a total optical scan angle of 10.4° was achieved. In addition, 1D line scanning methods using both resonant and non-resonant frequencies were included and a total optical scan angle of 14° was obtained with 100 mV_pp under out-of-phase actuation condition. Furthermore, 2D scan patterns including Lissajous, circular and spiral, and raster scans were realized. Diverse scan patterns were realized with the presented AlScN-based MEMS mirror device even under a low level of applied voltage. Further experiments using high voltage up to ±120 V to achieve an enhanced quasi-static scan angle of more than 20° are ongoing to ensure repeatability. This multi-functional MEMS mirror possesses the potential to implement multiple scanning strategies suitable for various application purposes.

A new type of piezoelectric scanning micromirror using single crystal lead magnesium niobate-lead titanate (PMN-PT) is presented in this paper. The micromirror is designed for one-dimensional (1D) scanning and has a large aperture with a 5 mm diameter reflective surface. The micromirror has single crystal PMN-PT plates directly laminated onto micromachined silicon cantilever structures, and two different device geometries with varying PMN-PT planar dimensions have been designed. Mechanical amplification structures are utilized to achieve a maximum optical scan angle of over 30° at a low driving voltage. Finite element analysis was used to optimize the micromirror design, which was then fabricated using deep reactive ion etching of a silicon-on-insulator substrate and lamination of separately prepared PMN-PT plates. The driving characteristics of the fabricated devices were measured using out-of-phase actuation of the two piezoelectric cantilevers with forward and backward frequency sweeps at various input voltages. An optical scan angle of 31.38° at 3.514 kHz with 4 V _pp input has been achieved with model A in an ambient environment. The scan angle sensing capability was tested using a single cantilever for actuation and the other for sensing, and a relatively linear relationship was observed between the optical scan angle and the sensor output voltage with a measured average sensitivity of 0.158 V _rms /°. The uniformity of the PMN-PT lamination process was verified by testing multiple samples. The maximum optical scan angle before device failure was also measured, which was 72° at 34 V _pp input at 3.843 kHz.

In this paper, a piezoelectrically driven quasi-static MEMS mirror is developed for a scanning LiDAR system. Finite element method (FEM) simulations are used to optimize the design of the MEMS scanner. With special emphasis on the shape and thickness of the actuators, they are optimized to reach a maximum static total optical scan angle (TOSA) of 30°. Their influence on the resonance frequency at dynamic modes and the material stress are investigated. In this study, two designs are compared with respect to their FEM simulation results. Currently, the devices are manufactured in the cleanroom. The manufactured samples will be characterized and the measurement results will be published in future works.

This paper presents the optical system design for the MEMS mirror-based SPAD LiDAR system. The transmitter of the proposed LiDAR system consists of related optics for incident beam expansion and a piezoelectric MEMS mirror for a wide-scanning field of view. For the receiver unit, an SPAD array is utilized to collect the laser beam reflected from the target objects at a smart factory. The optical system of the proposed LiDAR system is presented, designed, and analyzed in various ways.