We have constructed a new version of retinal imaging system with chromatic aberration concerned and the correlated
optical design presented in this article is based on the adaptive optics fundus camera modality. In our system, three
typical wavelengths of 550nm, 650nm and 480nm were selected. Longitude chromatic aberration (LCA) was traded off
to a minimum using ZEMAX program. The whole setup was actually evaluated on human subjects and retinal imaging
was performed at continuous frame rates up to 20 Hz. Raw videos at parafovea locations were collected, and cone
mosaics as well as retinal vasculature were clearly observed in one single clip. In addition, comparisons under different
illumination conditions were also made to confirm our design. Image contrast and the Strehl ratio were effectively
increased after dynamic correction of high order aberrations. This system is expected to bring new applications in
functional imaging of human retina.
The optical design of a confocal scanning laser ophthalmoscope based on adaptive optics (AOSLO) is described in
this paper. Spherical mirrors are used for pupil relay and astigmatism compensation. The main optical system
achieves diffraction-limited performance through the entire scanning angle (6mm pupil, 3 degree on pupil plane).
The adaptive optics (AO) retina imaging was performed with contrast enhancement by characterizing polarization
parameters of the living retina. A removable pair of polarization state generating unit near the optical source and analysis
unit near the CCD camera was incorporated into the basic 37-channle deformable mirror AO microscopic
ophthalmoscope. Double-pass imaging polarimetry of the human eye was carried out, then incomplete Mueller matrix
was calculated and analyzed to optimize the retina imaging condition using polarized light, which caused the subretinal
structures with different polarization properties to emerge from the scattering light background, so the contrast of the
image can be substantially enhanced. This method is demonstrated briefly and its validity was tested in the laboratory.
The high-resolution images of ocular fundus are compared with 8-frame-averaging images we obtained prior to this
method. The experiment results now show improved visualization of fundus structures to some extent without greatly
sacrificing image resolution.