[OPTICAL REVIEW Vol. 15, No. 3 (2008) 173-180]
© 2008 The Optical Society of Japan

Adaptive Optics Fundus Camera Using a Liquid Crystal Phase Modulator

Tatsuo YAMAGUCHI, Naoki NAKAZAWA, Kenichiro BESSHO1, Yoshiyuki KITAGUCHI1, Naoyuki MAEDA2, Takashi FUJIKADO1, and Toshifumi MIHASHI*

Topcon Corporation, 75-1 Hasunuma-cho, Itabashi-ku, Tokyo 174-8580, Japan
1Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
2Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan

(Received November 14, 2007; Accepted March 21, 2008)

We have developed an adaptive optics (AO) fundus camera to obtain high resolution retinal images of eyes. We use a liquid crystal phase modulator to compensate the aberrations of the eye for better resolution and better contrast in the images. The liquid crystal phase modulator has a wider dynamic range to compensate aberrations than most mechanical deformable mirrors and its linear phase generation makes it easy to follow eye movements. The wavefront aberration was measured in real time with a sampling rate of 10 Hz and the closed loop system was operated at around 2 Hz. We developed software tools to align consecutively obtained images. From our experiments with three eyes, the aberrations of normal eyes were reduced to less than 0.1 μm (RMS) in less than three seconds by the liquid crystal phase modulator. We confirmed that this method was adequate for measuring eyes with large aberrations including keratoconic eyes. Finally, using the liquid crystal phase modulator, high resolution images of retinas could be obtained.

Key words: adaptive optics, liquid crystal phase modulator, Shack–Hartmann wavefront sensor, retina, fundus camera

*E-mail address: mihashi@opt.topcon.co.jp