A High-Resolution Adaptive Optics Fundus Imager

The spatial resolution of retinal images is limited by the presence of time-varying aberrations present within the eye. A low-order adaptive optics system using a Shack-Hartmann wavefront sensor and a bimorph deformable mirror is described. Using a standard Hitachi video camera and a PC running Windows 2000, control of low-order aberrations within the eye can be achieved, enabling high resolution images to be obtained. The wavefront sensor employs a novel dithered reference technique to reduce speckle recorded in the hartmannogram. As a measurement of the residual errors within the image is known, it is possible to use post-processing techniques to further improve the resolution of the image. Example images of retinas taken with the system and then post-processed are shown, demonstrating the ability to calculate near diffraction-limited images. Data on the performance of the system are presented.