Preface

Chapter 8 **A Unified Approach to Analysing the Anisoplanatism of**

**Adaptive Optical Systems 191** Jingyuan Chen and Xiang Chang

**VI** Contents

For over four decades there has been continuous progress in adaptive optics technology, theory, and systems development. Recently there also has been an explosion of applications of adaptive optics throughout the fields of communications and medicine in addition to its original uses in astronomy and beam propagation. This volume is a compilation of research and tutorials from a variety of international authors with expertise in theory, engineering, and technology.

The first section, Integrated Adaptive Optics Systems, contains a chapter by Zoran Popovic, Jörgen Thaung, Per Knutsson and Mette Owner-Peterson from Sweden that describes in great detail the challenges, system development, and success of high resolution retinal imag‐ ing. The second chapter in this section, Deqing Ren and Yongtian Zhu from China present a design and detailed performance analysis of a solar adaptive optics system.

The second section, Devices and Techniques, goes into more detail in various areas. Bonora, Zawadzki, Naletto, Bortolozzo, Residori describe a number of algorithms to assist an adap‐ tive optics system that does not directly use wavefront sensors. The Italian team show the principle applied to a number of applications such as conventional imaging, optical coher‐ ence tomography, and laser processing.

A broad tutorial chapter by Chinese reseachers Xuan, Cao, Mu, Hu, and Peng presents an overview of liquid crystal technology with the applications to wavefront correction. The chapter describes many of the benefits as well as the limitations of liquid crystals with sup‐ porting theory and analysis.

Over the past 20 years, micromachined deformable membrane mirrors have been advancing rapidly, and because of their low cost, they have become commonplace. Europeans Thomas Ruppel et al. present a chapter to bring us up to date on the technology, manufacture, and applications of the devices.

The final chapter of this section by Aubailly and Vorontsov discusses the limitations of con‐ ventional adaptive optics in terms of field-of-view and anisoplanatism. Then the American collaborators present a novel approach the does not use a wavefront measurement alone, but rather a measure of the entire received complex electromagnatic field to synthesize the images.

The third and last section to the volume, Optical and Atmospheric Effects, explores the ap‐ plication of adaptive optics to complex wave phonomena. Russian researchers Garanin, Starikov, and Malakhov present a discussion of optical vortices, showing how they appear in actual atmospheric propagation. Through analysis and simulation, the authors devote the better part of the chapter to describe sensing the vortices and applying a phase correction.

The final chapter, by Jingyuan Chen and Xiang Chang of Yunnan Observatory in China, ad‐ dresses the problem of combined and coupled effects of various types of anisoplanatism. Rigorous analysis is used in a number of special cases to provide guidelines for analyzing system performance and designing telescope concepts.

> **Robert K. Tyson, Ph.D.** University of North Carolina at Charlotte, North Carolina, USA

**Section 1**

**Integrated Adaptive Optics Systems**

**Integrated Adaptive Optics Systems**

in actual atmospheric propagation. Through analysis and simulation, the authors devote the better part of the chapter to describe sensing the vortices and applying a phase correction. The final chapter, by Jingyuan Chen and Xiang Chang of Yunnan Observatory in China, ad‐ dresses the problem of combined and coupled effects of various types of anisoplanatism. Rigorous analysis is used in a number of special cases to provide guidelines for analyzing

**Robert K. Tyson, Ph.D.**

North Carolina, USA

University of North Carolina at Charlotte,

system performance and designing telescope concepts.

VIII Preface

**Chapter 1**

**Dual Conjugate Adaptive Optics Prototype for Wide**

Retinal imaging is limited due to optical aberrations caused by imperfections in the optical media of the eye. Consequently, diffraction limited retinal imaging can be achieved if optical aberrations in the eye are measured and corrected. Information about retinal pathology and structure on a cellular level is thus not available in a clinical setting but only from histologi‐ cal studies of excised retinal tissue. In addition to limitations such as tissue shrinkage and distortion, the main limitation of histological preparations is that longitudinal studies of dis‐

Adaptive optics (AO) is the science, technology and art of capturing diffraction-limited im‐ ages in adverse circumstances that would normally lead to strongly degraded image quality and loss of resolution. In non-military applications, it was first proposed and implemented in astronomy [1]. AO technology has since been applied in many disciplines, including vi‐ sion science, where retinal features down to a few microns can be resolved by correcting the aberrations of ocular optics. As the focus of this chapter is on AO retinal imaging, we will

The general principle of AO is to measure the aberrations introduced by the media between an object of interest and its image with a wavefront sensor, analyze the measurements, and calculate a correction with a control computer. The corrections are applied to a deformable mirror (DM) positioned in the optical path between the object and its image, thereby ena‐

Modern telescopes with integrated AO systems employ the laser guide star technique [2] to create an artificial reference object above the earth's atmosphere. Analogously, the vast ma‐

> © 2013 Popovic et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 Popovic et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ease progression and/or results of medical treatment are not possible.

focus our description to this particular field.

bling high-resolution imaging of the object.

**Field High Resolution Retinal Imaging**

Zoran Popovic, Jörgen Thaung, Per Knutsson and

Additional information is available at the end of the chapter

Mette Owner-Petersen

http://dx.doi.org/10.5772/53640

**1. Introduction**
