Double stage FPCB scanning micromirror for laser line generator

Abstract

This paper presents a laser line generator consisting of an electrostatic scanning micromirror utilizing a Double-Stage Flexible Printed Circuit Board (DS-FPCB). It consists of two stages with the rotating electrode in the 1st stage, and the mirror plate in the 2nd stage. Due to both rotating electrode being much closer to the rotational axis and the rotational amplification effect between the two stages, the DS-FPCB micromirror can have a 90% higher maximum rotation angle, in comparison to previously developed single stage FPCB micromirrors, while retaining benefits of low cost (a few dollars) and high surface quality (high flatness, radius of curvature (ROC) >10 m, good roughness of nanometers). The DS-FPCB micromirror is modeled and prototypes are fabricated and tested, achieving a 3.25° optical rotation at 100 V (sinusoidal wave driving signal) and 10.87° at 150 V (square wave driving signal), both at 117 Hz. A laser line generator based on the DS-FPCB micromirror is developed and tested, whose laser power density along the line is uniform and independent on the projection distance, while the conventional laser line generator's laser power density varies along the laser line and is highly dependent on the projection distance.