Large deflection angle resonant 1D scanning micromirror fabricated with multi jet fusion 3D printed parts

Abstract

This paper presents a one-dimensional scanning micromirror, utilizing Multi Jet Fusion three-dimensional (3D) printed polyamide 12 as its core material, with a gold-coated silicon mirror in a half-circle extension shape (4.2 mm x 15 mm). The micromirror serves as a horizontal scanner in a two-dimensional scan module for light detection and ranging. It features a self-supported coil for electromagnetic actuation, and its design is validated through analytical and finite element analyses. The magnetic circuit design is assessed with three magnet configurations. Forced air cooling and salt bath annealing processes are performed to mitigate the effect of Joule heating in the coil and improve the mechanical characteristics of the 3D printed structure. A maximum optical scan angle of 34 degrees was achieved at 1,432 Hz with 90.8 mArms under forced air cooling. The salt bath annealing enhances the long-term reliability significantly, with a 12-hour operational test showing a 1.2% variation in resonant frequency.