3D-printed scanning micromirror with improved mechanical and thermal properties for LiDAR applications

This study presents a 3D-printed electromagnetic scanning micromirror with enhanced mechanical and thermal properties for LiDAR applications. Increasing the resonant frequency of 3D-printed polymer-based scanning micromirrors is typically challenging due to the low Young's modulus of printed materials, which also degrade mechanically at elevated temperatures, leading to variations in elastic modulus and reduced resonant frequency. To address these challenges, we employed digital light processing 3D printing of a high-temperature-resistant polymer resin to fabricate core structural part of the scanning micromirror, and investigated the effect of 3D printing orientation and surface topology on mechanical performance. We identified a 45° printing orientation as optimal, achieving a maximum optical scan angle of 34° at 1450 Hz with an input current of 170 mA_rms, without the need for external cooling. A tensile test was conducted to accurately predict and analyze device performance. By incorporating the experimentally determined Young's modulus values into the finite element analysis, the discrepancy between the predicted and measured resonant frequencies was reduced from over 30 % to 8.19 %. Structural modifications, including the addition of heat-isolating anchors and thermal via holes, were implemented to enhance thermal stability. These changes limited the resonant frequency drop to less than 250 Hz as the input current increased from 10 mA_rms to 170 mA_rms, while maintaining a linear increase in the optical scan angle. This work highlights the importance of optimizing mechanical, thermal, and printing parameters to improve the performance and reliability of 3D-printed micromirrors for high-precision optical systems such as LiDAR sensors.