Lightweight, optically flat micromirrors for fast beam steering

Abstract

We have demonstrated flat, lightweight micromirrors with high resonant frequencies for fast beam steering. The low mass of these tensile-optical-surface (TOS) micromirrors, which consist of tensile polysilicon membranes stretched across stiff, single-crystal silicon-rib structures, enables the mirrors to have both high resonant frequencies and large DC deflection angles. The TOS mirrors can scan at frequencies up to 68.2 kHz while limiting dynamic deformation to be less than -70 nm, (approximately U10 at the measurement wavelength of 688 nm). Dynamic deformation as low as 20 nm has been shown on a lower-frequency design having a wider support rib. The effect of adding a 50 nm-thick layer of gold to improve reflectivity is negligible on the deformation of the micromirror.

Gimbal-Less Monolithic Silicon Actuators for Tip–Tilt–Piston Micromirror Applications

“…Equations governing these types of comb fingers follow from above, approximating the area change and therefore torque as (5) When used in capacitive sensing circuits, reference capacitors are fabricated on chip utilizing the same layout in order to insure matched capacitances.…”

High Aspect Ratio Micromirrors With Large Static Rotation and Piston Actuation

“…Of interestwastoaddverticalcombdrives.Vertically staggered SOI comb drives perform well for single-sided rotation applications [2], [3], [8] and demonstrated advantages of SOI-MEMS such as flatness, speed, and robustness, with respect to surface-micromachined examples of vertical comb drives [11], [12]. However, in these previous SOI comb drive processes, no isolation is available between comb drive fingers in either upper or lower comb drives, thus, one-sided rotation was demonstrated.…”

<title>Optical measurement methods to study dynamic behavior in MEMS</title>

“…Figure 6a shows a SEM photograph of a surface-micromachined mirror and Figure 6b demonstrates the measured mirror deformation at 3120Hz (at 0rad phase delay compared to the input signal). Details of BSAC investigations of micromirrors have been published in [5,6,16,17]. The first full three-dimensional motion characterization with MSIS was performed to study a hard-disk drive [18].…”