Grisan Enrico, Frassetto Fabio, Da Deppo Vania, Naletto Giampiero, Ruggeri Alfredo
Department of Information Engineering, University of Padova, Via Gradenigo 6/B, I-35131 Padova PD, Italy.
Conf Proc IEEE Eng Med Biol Soc. 2005;2005:3173-6. doi: 10.1109/IEMBS.2005.1617149.
Adaptive optics has been recently applied for the development of ophthalmic devices, with the main objective of obtaining higher resolution images for diagnostic purposes or ideally correcting high-order eye aberrations. The core of every adaptive optics systems is an optical device that is able to modify the wavefront shape of the light entering a system: once the shape of the incoming wavefront has been estimated, by means of this device it is possible to correct the aberrations introduced along the optical path. The aim of this paper is to demonstrate the feasibility, although in a simulated system, of estimating and correcting the wavefront shape simply by means of an iterative software analysis of a single point source image, thus avoiding expensive wavefront sensors or the burdensome computation of the PSF of the optical system. To test the proposed algorithm, a simple optical system has been simulated with a ray-tracing software and a program to estimate the Zernike coefficients of the simulated aberration from the analysis of the source image has been developed. Numerical indexes were used to evaluate the capability of the software of correctly estimating the Zernike coefficients. Even if only defocus, astigmatism and coma were considered, the very satisfactory results obtained confirm the soundness of this new approach and encourage further work in this direction, in order to develop a system able to estimate also spherical aberration, tilt and field curvature. An implementation of this aberration estimation in a real AO system is also currently in progress.
自适应光学最近已应用于眼科设备的开发，其主要目标是获取更高分辨率的图像用于诊断目的，或者理想地校正高阶眼像差。每个自适应光学系统的核心是一个能够改变进入系统的光的波前形状的光学器件：一旦估计出入射波前的形状，借助该器件就可以校正沿光路引入的像差。本文的目的是证明，尽管是在模拟系统中，但仅通过对单点源图像进行迭代软件分析来估计和校正波前形状的可行性，从而避免使用昂贵的波前传感器或光学系统点扩散函数的繁重计算。为了测试所提出的算法，使用光线追踪软件模拟了一个简单的光学系统，并开发了一个程序，用于从源图像分析中估计模拟像差的泽尼克系数。使用数值指标来评估软件正确估计泽尼克系数的能力。即使仅考虑散焦、散光和彗差，所获得的非常令人满意的结果也证实了这种新方法的合理性，并鼓励在这个方向上进一步开展工作，以便开发一个能够估计球差、倾斜和像场弯曲的系统。目前也正在进行在实际自适应光学系统中实现这种像差估计的工作。
