Current-generation adaptive optics scanning laser ophthalmoscopes (AOSLO) are typically able to compensate for the optical aberrations of the human eye and achieve diffraction-limited illumination over a wide vergence range. However, to maximize the light collection efficiency of such a system, it is also necessary to have a collection path that is diffraction-limited for each imaging channel. Although it is trivial to achieve a high collection efficiency for a single channel AOSLO or a multi-channel AOSLO with minimal vergence differences between channels, for larger vergence differences, a careful consideration of the collection optics and their position and orientation within the collection path is needed. We present a methodology and system design for achieving diffraction-limited performance in both the illumination and collection paths of a multi-color AOSLO. The system consists of three imaging channels spanning different wavelength ranges (543 ± 11 nm, 680 ± 11 nm, and 840 ± 6 nm, respectively) and one near-infrared wavefront sensing channel (940 ± 5 nm). The maximum vergence difference between channels (measured at the exit pupil of the system) is ~1.2 diopters to compensate for the chromatic focal shift of the human eye. Preliminary imaging results from a healthy human adult volunteer demonstrate the system’s ability to resolve the foveal cone mosaic in all three imaging channels.
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