Implementation of hexagonal micromirror arrays as phase-mostly spatial light modulators

Publisher Website
Google Scholar
Abstract
Hexagonal micromirror arrays and associated test structures have been fabricated using a commercial surface-micromachining process. The hexagonal micromirrors are 50 micrometers across and are arranged in a hexagonal array of 127 mirrors with 75 micrometers center-to-center spacing between nearest micromirrors. Each micromirror is supported by three flexure hinges, each of which surrounds one third of the micromirror perimeter. Each micromirror in the array can be displaced independently through a vertical distance of over 1 micrometers by a voltage applied to an underlying address electrode. The flexures and other highly diffracting or poorly reflecting areas can be covered by a statinary reflecting plate with holes that expose the moving micromirrors. These micromirror arrays function as efficient phase-mostly spatial light modulators. Applications for these micro-opto-electro-mechanical systems include optical processing, coherent beam shaping, and adaptive optics. This design has several important advantages. First, the hexagonal micromirror and array geometries maximize the active surface area of the array. Second, the use of three flexures instead of four, as is typical for square phase-mostly micromirrors, lowers the required drive voltage. Third, the reflecting cover plate ensures that light efficiency is maximized and that a substantial stationary coherent reference plane is provided. Design considerations for fabricating the arrays in commercial surface mciromachining processes are discussed. The deflection versus voltage behavior of the hexagonal micromirror is determined analytically and experimentally. Test results are used to design the next generation array.

This publication has 0 references indexed in Scilit: