Adaptive optics for ophthalmic applications using a pyramid wavefront sensor

Stéphane R Chamot,Simone Esposito,Chris Dainty

doi:10.1364/opex.14.000518

Abstract

A new adaptive optics system for the eye using a pyramid wavefront sensor interfaced in closed-loop with a piezoelectric deformable mirror is presented. Sensing parameters such as CCD integration time, pupil sampling and beam steering amplitude are tested on the bench and in vivo on several volunteers to optimize real-time optical correction. The system allows closed-loop operation at a frame rate of 55 Hz and reduces ocular aberration up to lambda/5 residual RMS over a 6 mm pupil. Aberration correction and mirror control stability clearly increase when smaller beam steering amplitudes synonymous of higher wavefront sensing sensitivity are used. This result suggests that using pyramid wavefront sensors can improve the performance of adaptive-optics system for ophthalmic applications.

Highlights

Since a first implementation in 1997 [1], adaptive optics (AO) systems for ophthalmic applications [2, 3, 4, 5, 6] have always relied on Shack-Hartmann sensors (SHS) [7] to perform wavefront sensing
Comparative simulations of the effectiveness of this mirror for ophthalmic use can be found in [15]. This deformable mirror was itself optically conjugated to a steering mirror (FSM-300, Newport, Irvine, CA, USA) positioned in the wavefront sensing arm, whose movement was controlled with two sinusoidal signal (100 Hz) of same amplitude A 0 and π/2 phase difference
Consistent with the results presented above, the best aberration correction was obtained at the smallest modulation amplitude for all tested lenses with an average root mean square (RMS) residual improvement of 0.026 μm between corrections operated at 7 λ /D and 28 λ /D

Summary

Introduction

Since a first implementation in 1997 [1], adaptive optics (AO) systems for ophthalmic applications [2, 3, 4, 5, 6] have always relied on Shack-Hartmann sensors (SHS) [7] to perform wavefront sensing. While this choice was obviously successful in most cases, one could think of alternative wavefront sensing approaches to achieve this task with possibly higher efficiency and greater flexibility. Considering the absence of an adequate statistical description of ocular aberration allowing performance simulation for an AO system using a PS, we built such an optical setup and studied its performance for ophthalmic applications

Apparatus

Open-loop bench test of sensing accuracy

In vivo operation

Findings

Conclusion