MEMS scanners for display and imaging applications

Abstract

Dynamic display and imaging applications demand high performance scanners, which has high frequency (exceeding 10KHz), large scan-angle-mirror-size product (>+/-10deg.mm), good optical surface quality (<lambda/20 static and dynamic flatness), high sensitivity position sensors, and high-torque actuators that are compact and low power. This paper discusses the resolution and other optical performance requirements for diffraction-limited and non-diffraction-limited light sources in a scanning system. A set of analytical formulas is presented for calculating the torsion and other four fundamental oscillation mode vibration frequencies. The formulas include the effects of material anisotropy in orthotropic materials, such as Silicon and effective mass and inertia of the flexures. The validity range of formulas are extended by introducing a correction factor based on flexure width and flexure length ratios. The formulas are very efficient for performance trades and optimization. For scanner actuation, we present two compact scanner actuation mechanisms: out-of-plane comb actuator and novel two-coil electromagnetic actuator.