Use of micro-electro-mechanical deformable mirrors to control aberrations in optical systems: theoretical and experimental results

Micro-electro-mechanical deformable mirrors (MEM-DMs) are solid-state electronic devices with small, movable reflective surface elements that can be used to manipulate the phase of optical wavefronts. MEM-DMs differ from more conventional continuous-facesheet deformable mirrors in that the movable surface of a MEM-DM consists of a set of segmented moving surfaces. The segmented, reflective surfaces of a MEM-DM give rise to larger diffraction effects than those provided by continuous-facesheet deformable mirrors. However, MEM-DMs are still attractive due to their low cost and the low drive voltages. We explore the theoretical limits of performance of MEM-DMs for controlling fixed aberrations in optical systems, and we present laboratory results demonstrating reduction of a fixed aberration using a MEM-DM device. Results presented here show that while a MEM-DM does provide some degree of aberration control, diffraction effects arising from the static support structures of the MEM-DM surface are significant. An alternative design that uses a lenslet array in conjunction with the MEM-DM is shown through theoretical studies to provide superior aberration correction with lower residual effects due to diffraction.