Michiko Nakanishi

Compensation of model eye's aberration by using deformable mirror

This paper reports on compensation for human eye aberration using a membrane deformable mirror(DM) which is fabricated by the MEMS process. The DM consists of a silicon(Si) membrane formed by processing of an SOI wafer and 85 electrodes. The diameter of Si membrane is 12mm and the maximum displacement is 16μm at a driving voltage of 180V. We have successfully demonstrated compensation for a model eyes aberration by using the DM. The model eyes aberration measured by the Shack-Hartmann wavefront sensor was expanded into Zernike polynomials and the driving voltages for the DM were decided so that the membrane shape would cancel out the eyes aberration by using appropriate voltage arrangements for each of the Zernike polynomials, these arrangements being predetermined experimentally. We have corrected the aberration of the model eye to less than 0.1μm-RMS. In this experiment, the effective diameter of the DM was 7.5mm, and the pupil of the model eye was 8.5mm.

A widely-variable optical attenuator for multimode fibers with a MEMS micromirror

MEMS-based variable optical attenuators (VOAs) using a shutter, a mirror, or a grating have been proposed in the field of optical telecommunication [1]. The MEMS-based VOAs used in optical telecommunication, however, are not suitable for optical instruments, in which a light beam is not always single mode ( i.e. is low spatially coherent) and optical power to be regulated can substantially vary (≫ 40 dB).