Adaptive Optics to Simulate Vision with a Liquid Crystal Spatial Light Modulator

Summary

Adaptive optics for the human eye has two main applications: to obtain high-resolution images of the retina and to produce aberration-controlled retinal images to simulate vision. We built an adaptive optics prototype specially designed for visual testing based on the use of a liquid crystal spatial light modulator (Hamamatsu X8267). The system consists of a measurement channel with switchable red (633 nm) or infrared (780 nm) illumination, a real time Hartmann-Shack sensor (25 Hz), and an additional channel allowing subjects to perform visual tasks in green light through the adaptive optics system. We tested the modulator, both as aberration generator and as corrector, first in an artificial eye and then routinely in different living eyes. This device has advantages in terms of effective stroke and mode independence allowing production and compensation of a larger range of aberrations than with other correcting devices. This opens new possibilities for visual applications of adaptive optics. However, a low temporal response and diffraction effects may be important drawbacks of the modulator for some particular applications. Examples of the performance of the system and a discussion of its limitations and potential for performing visual optics experiments will be presented.