Abstract

First introduced by Preston¹ in 1968, deformable mirror SLMs incorporating a highly reflective membrane as the light modulating element have generated interest within the applied optics community as good candidates for both adaptive optics and projection display applications.^2-4 These SLMs exhibit very fast response times, can be read out with high optical efficiency, and in principle can incorporate a very large number of resolution elements. Since a deformable mirror SLM is essentially a two-dimensional phase modulating element with large phase dynamic range, it is well-suited to adaptive optics applications such as wavefront correction and beam steering. With appropriate pixelization of the membrane surface, intensity modulation may be accomplished via the Schlieren readout schemes employed by projection display systems such as the Eidophor⁵ (G.E.) and the γ-Ruticon⁶ (Xerox). The construction of a membrane light modulator (MLM) is such that a membrane is deposited over an array of wells with an addressable electrode at the bottom of each well. Thus, the well and its electrode define an individual pixel. The membrane is coated with a thin electrode material held at a static potential. A pixel is activated by establishing a potential difference between the well electrode and the membrane electrode, causing the membrane to deform into the well region in response to electrostatic forces. Hence, the pixel driving voltage induces a local phase modulation on the readout wavefront reflected by the membrane mirror surface.

© 1990 Optical Society of America