Abstract
The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.
Highlights
Adaptive optics (AO) allows for the measurement and control of monochromatic aberrations in optical instruments
We propose to correct non-common path aberrations (NCPAs) in scanning AO ophthalmoscopes through the maximization of an image sharpness metric while the confocal detection aperture is temporarily removed from the optical path
This is in agreement with our observation about the point spread function (PSF) calculation, in that it is the monochromatic aberrations in the illumination path that have the most impact in the image sharpness
Summary
Adaptive optics (AO) allows for the measurement and control of monochromatic aberrations in optical instruments. In AO ophthalmoscopes with wavefront sensors, a portion of the optical path leading to the wavefront sensor is inevitably different from that leading to the imaging detector(s). This gives rise to non-common path aberrations (NCPAs) that could lead to non-negligible performance degradation if left uncorrected [28,30]. These NCPAs can be due to optical element theoretical performance, manufacturing imperfections or distortion due to mechanical mounting with excessive pressure. In mechanically and thermally stable AO ophthalmoscopes, NCPAs can be considered static unless the relative focus between the imaging and wavefront sensor channels is changed [30,31]
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