Adaptive fundus imaging using a micromachined membrane deformable mirror

摘要

We have investigated the use of a 19-channel micromachined membrane deformable mirror (MMDM) for correcting aberrations of the eye to improve the resolution of fundus imaging. A Hartmann-Shack wavefront sensor (HSWS) and the MMDM are used to measure and correct aberrations existing in the anterior segments of the eye, respectively. Zernike polynomials are used to represent the MMDM surface shape as well as the optical wavefront shape. In order to control the MMDM, which has nonlinear and coupled responses to electrostatic controls, we have developed an adaptive control algorithm to iteratively adjust the control voltages of all channels, thus modulating the shape of the MMDM to reduce the variance of the optical wavefront measured using the HSWS. Experimental results using an artificial eye show that the adaptive system can compensate for low-order and some high- order aberrations, thereby improving the resolution of retinal images. The capability for correcting ocular aberrations is limited by the number of channels and the deflection range of the MMDM. Our new adaptive control algorithm allows effective use of the low-cost, compact MMDM, making adaptive optics a viable and practical technique for clinical high-resolution fundus cameras and other ophthalmic imaging instruments.