MOEMS spatial light modulator development at the Center for Adaptive Optics

Abstract

The National Science Foundation Center for Adaptive Optics (CfAO) is coordinating a program for the development of spatial light modulators suitable for adaptive optics applications based on micro-optoelectromechanical systems (MOEMS) technology. This collaborative program is being conducted by researchers at several partner institutions including the Berkeley Sensor & Actuator Center, Boston Micromachines, Boston University, Lucent Technologies, the Jet Propulsion Laboratory, and Lawrence Livermore National Laboratory. The goal of this program is to produce MEMS spatial light modulators with several thousand actuators that can be used for high-resolution wavefront control applications that would benefit from low device cost, small system size, and low power requirements. The two primary applications targeted by the CfAO are astronomy and vision science. In this paper, we present an overview of the CfAO MEMS development plan along with details of the current program status.

High-aspect-ratio microelectromechanical systems deformable mirrors for adaptive optics

“…7 Previous research efforts in MEMS "high-stroke" actuators for DMs have used the Sandia ultraplanar, multilevel MEMS technology 8 (SUMMiT) to fabricate segmented AO mirrors and the MEMSCAP polysilicon surface micromachining process 9 to fabricate continuous-facesheet AO mirrors. 10 A limitation of MEMS DMs currently fabricated using surface micromachining is the stroke (<6 μm) for continuous-facesheet mirrors. The current commercial MEMS DMs being developed for AO are from Boston Micromachines Corporation 11 (BMC) and IrisAO.…”

A 45-element continuous facesheet surface micromachined deformable mirror for optical aberration correction

“…A 1 kHz bandwidth can satisfy astronomical and ophthalmic instrumentation requirements. 16 In addition, unlike segmented facesheets, continuous facesheets have a special parameter, called the influence function or actuator coupling, because continuous facesheets can produce deformation, resulting in the deflection of adjacent unactuated actuators around the actuated actuator. The ratio of these two deflections is defined as the actuator coupling and a 5-12% actuator coupling offers the best correction capability.…”

“…The aberration in the eye can be obtained statistically and a 10 μm stroke is sufficient. 16 Second, the number of actuators or degrees of freedom determines the order of the compensation that the DM can produce. Also, the spatial frequency of the actuators should be higher than the spatial frequency of the aberration.…”

“…Also, the spatial frequency of the actuators should be higher than the spatial frequency of the aberration. Several hundred and several thousand actuators are appropriate for ocular AO and astronomical imaging applications, 16 respectively. Third, because of Rayleigh's quarter wavelength rule, 17 the surface flatness should be less than half this value.…”

Large-stroke self-aligned vertical comb drive actuators for adaptive optics applications

“…Each adaptive optics (AO) application has its own set of requirements for this deformable element. In the case of a vision science AO system, the requirements can be seen in Table 1 [3].…”