Monolithic Deformable Membrane Mirror for High Energy Laser Applications

To address the high-speed, low-cost, low-weight, and compact requirements of space- and air-borne high-energy-laser adaptive optical systems, this Phase I program will design test and fabricate a monolithic, high-resolution, deformable, thin-filmMEMS-actuator-driven phase-only spatial light modulator mirror. The modulators will be built atop a VLSI driver chip, and in the Phase II program a six-inch wafer will provide four modulators with 512x512 pixels on 10-micron centers. In particular, thePhase I will focus on the problems of electrostatic MEMS actuator design and fabrication, high-voltage VLSI-MEMS driver chip design and fabrication, and prototype modulator assembly and testing to establish feasibility. The proposed modulator designoffers: large phase dynamic range (large stroke), low-voltage and low power operation, low weight, scalability to millions of actuators, fast rise time (10 microseconds), electrically-independent actuators, excellent surface figure, high laser power damagethreshold, compatibility with system architectures that reduce the computations necessary to compensate wavefront distortion, and low manufacturing cost. Anticipated BenefitsBecause of its unique design, the modulator is a nearly ideal phase corrector element. We expect the modulator to: offer at least 4d radians of phase correction (2d radians of displacement) at near-infrared wavelengths, operate at electronics-limitedframing rates on the order of 4 kHz, offer more accurate phase correction at potentially higher rates than other modulators because of its 100% fill factor, be ultra-compact and extremely lightweight enough to be mounted into telescopes, airframes,missiles, satellites, and medical equipment without significant modification, be scalable to larger wafer sizes without any performance degradation due to the massively parallel nature of the feeding signals, and to yield low system cost becausewafer-scale fabrication is being used.Potential Commercial ApplicationsCommercial applications of the proposed MEMS phase modulator and its intensity counterpart include (1) large-screen projection displays, (2) low-cost wavefront correctors (such as retinal imagers and supernormal human vision systems) for the commercialand amateur astronomy markets, (3) low-cost mirror shutters for general-purpose use, and for applications in laser radar and printing, and (4) spatial light modulators for optical signal processing applications.