The performance of an adaptive optical system is strongly dependent upon correctly measuring the wavefront of the arriving light. The most common wavefront measurement techniques used to date are the shearing interferometer and the Shack-Hartmann sensor. Shack-Hartmann sensors rely on the use of lenslet arrays to sample the aperture appropriately. These have traditionally been constructed using ULM or step and repeat technology, and more recently with binary optics technology. Diffractive optics fabrication methodology can be used to remove some of the limitations of the previous technologies and can allow for low-cost production of sophisticated elements. We have investigated several different specialized wavefront sensor configurations using both Shack-Hartmann and shearing interferometer principles. We have taken advantage of the arbitrary nature of these elements to match pupil shapes of detector and telescope aperture and to introduce magnification between the lenslet array and the detector. We have fabricated elements that facilitate matching the sampling to the current atmospheric conditions. The sensors were designed using a far-field diffraction model and a photolithography layout program. They were fabricated using photolithography and RIE etching. Several different designs will be presented with some experimental results from a small-scale adaptive optics brass-board.

Principles of Adaptive Optics covers the basic principles of optics, wavefront sensing, controls, and wavefront correction that encompass the specialized field called adaptive optics. This book is composed of eight chapters that summarize the fundamental technology developments and the basic understanding of the various disciplines used in adaptive optics. After briefly reviewing the history, background, and developments of adaptive optics, this book goes on discussing the many sources of phase aberrations addressed by adaptive optics systems, such as linear effects due to turbulence, optical manufacturing, and misalignments, as well as errors that result from nonlinear thermal effects and fluid properties. The subsequent chapter deals with the performance enhancing role of adaptive optics systems in various disturbances. Other chapters describe the wavefront sampling, sensing, and correction subsystems. The concluding chapters explore the fundamental principles behind the adaptive optics control system and present summary expressions to determine the basic system parameters of an adaptive optics atmospheric compensation system. Communication scientists and engineers will find this work invaluable.

This is a practical book on wavefront sensing. Emphasis is on principles and techniques, rather than detailed mathematical analysis of such systems. The goal is to provide the reader with a qualitative understanding of wavefront sensor operation.

This book by one of the leaders in adaptive optics covers the fundamental theory and then describes in detail how this technology can be applied to large ground-based telescopes to compensate for the effects of atmospheric turbulence. It includes information on basic adaptive optics components and technology, and has chapters devoted to atmospheric turbulence, optical image structure, laser beacons, and overall system design. The chapter on system design is particularly detailed and includes performance estimation and optimization. Combining a clear discussion of physical principles with numerous real-world examples, this book will be a valuable resource for all graduate students and researchers in astronomy and optics.

The 4th International Workshop on Adaptive Optics for Industry and Me- cine took place in Munster, ̈ Germany, from October 19 to October 24, 2003. The series of International Workshops on Adaptive Optics for Industry and Medicine beganwiththe?rstworkshopinShatura/Russiain1997,thesecond workshop took place in Durham/England in 1999, and the third workshop was held in Albuquerque/USA in 2001. The workshop series started out as a true grassroots movement and kept an informal spirit throughout all four workshops. Many personal friendships and scienti?c collaborations have been formed at these meetings. This fourth workshop was supposed to be held in Beijing, China. H- ever, the program committee decided in May 2003 to move the workshop to Munster ̈ due the general perception that the SARS (Severe Acute R- piratory Syndrome) cases reported in China could lead to a large epidemic. Despite this rather short notice the workshop in Munster ̈ was attended by about 70 people. Incidentally, the workshop coincided with the 50th anniv- sary of adaptive optics, because it was October 1953 when Horace Babcock published his famous paper “The possibilities of compensating astronomical seeing” in the Publications of the Astronomical Society of the Paci?c.