Adaptive optics fundus camera using a liquid crystal phase modulator

• Published in: Optical review (Tokyo, Japan) Japan), 2008-05, Vol.15 (3), p.173-180
• Main Authors: Yamaguchi, Tatsuo, Nakazawa, Naoki, Bessho, Kenichiro, Kitaguchi, Yoshiyuki, Maeda, Naoyuki, Fujikado, Takashi, Mihashi, Toshifumi
• Format: Article
• Language: English
• Subjects: Aberrations; Atomic; Biological and medical sciences; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); General aspects, investigation technics, apparatus; Geometrical optics; Lasers; Lenses, prisms, and mirrors; Microwaves; Molecular; Optical and Plasma Physics; Optical Devices; Optical elements, devices, and systems; Optics; Photonics; Physics; Physics and Astronomy; Quantum Optics; Regular Papers; RF and Optical Engineering; Tissues, organs and organisms biophysics
• ISSN: 1340-6000; 1349-9432
• DOI: 10.1007/s10043-008-0028-6

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.