Abstract
An adaptive optics scanning laser ophthalmoscope (AO-SLO) set-up with two deformable mirrors (DM) is presented. It allows high resolution imaging of the retina on a 4°×4° field of view (FoV), considering a 7 mm pupil diameter at the entrance of the eye. Imaging on such a FoV, which is larger compared to classical AO-SLO instruments, is allowed by the use of the two DMs. The first DM is located in a plane that is conjugated to the pupil of the eye and corrects for aberrations that are constant in the FoV. The second DM is conjugated to a plane that is located ∼0.7 mm anterior to the retina. This DM corrects for anisoplanatism effects within the FoV. The control of the DMs is performed by combining the classical AO technique, using a Shack-Hartmann wave-front sensor, and sensorless AO, which uses a criterion characterizing the image quality. The retinas of four healthy volunteers were imaged in-vivo with the developed instrument. In order to assess the performance of the set-up and to demonstrate the benefits of the 2 DM configuration, the acquired images were compared with images taken in conventional conditions, on a smaller FoV and with only one DM. Moreover, an image of a larger patch of the retina was obtained by stitching of 9 images acquired with a 4°×4° FoV, resulting in a total FoV of 10°×10°. Finally, different retinal layers were imaged by shifting the focal plane.
Highlights
Imaging of the retina is limited by the eye itself
adaptive optics (AO) relies on a correcting device (usually a deformable mirror (DM)) in the optical train that corrects for the wave-front error (WFE), and provides diffraction limited performance over the corrected field of view (FoV) [5,6,7]
The resulting correction is uniform within the FoV but not efficient as the WFE is only decreased by ~0.2 μm compared to the non-corrected case
Summary
Imaging of the retina is limited by the eye itself. Most of the ophthalmic techniques have been combined with AO: flood illumination fundus imaging [8], scanning laser ophthalmoscopy (SLO) [9] and optical coherence tomography (OCT) [10]. More details on the individual techniques can be found in recent review articles [11,12,13,14]. With such techniques, microscopic structures of the eye, that were previously only visible ex-vivo with histology [15], can be revealed in vivo, and in a non invasive way
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