D.M. Alloin – författare

A few years ago, a real break-through happened in observational astronomy: the un­ derstanding of the effect of atmospheric turbulence on the structure of stellar images, and of ways to overcome this dramatic degradation. This opened a route to diffraction-limited observations with large telescopes in the optical domain. Soon, the first applications of this new technique led to some outstanding astrophysical results, both at visible and infrared wavelengths. Yet, the potential of interferometric observations is not fully foreseeable as the first long-baseline arrays of large optical telescopes are being built or cOIIllnissioned right now. In this respect a comparison with the evolution of radio-astronomy is tempting. From a situation where, in spite of the construction of giant antennas, low angular resolution was prevailing, the introduction of long baseline and very long baseline interferometry and the rapid mastering of sophisticated image reconstruction techniques, have brought on a nearly routine basis high dynamic range images with milliarcseconds resolution. This, of course, has completely changed our views of the radio sky.

For many astronomers, Adaptive Optics is something like a dream coming true. Sinee 1609 and the first observations of celestial bodies performed with the help of an optieal teleseope, astronomers have always fighted to improve the 'resolving power' of their instruments. For a long time, engineers have trimmed the optieal quality of the teleseopes, until they finally reaehed the barrier set by the atmospherie turbulence, a few seconds of are. At that point, the intrinsic quality of the site beeame a major issue to establish new observatories with modern telescopes, and astronomers started to desert the urban skies and to migrate toward mountains and deserts. This quest has been sueeessful and a few privileged sites, where the average natural 'seeing' is close to 0. 5", are now hosting clusters of giant telescopes of the 4 m and soon 10 m class. Yet, this atmospherie limit corresponds in the visible wavelength range to the diffraetion limit of a 20 em telescope only. The loss was severe: a faetor 20 in angular and several hundred in peak energy eoncentration, i. e. in deteetivity of resolution very faint objeets. In the beginning of the seventies, two doors half opened to provide a way out of this dead-end. First, the technique of speckle interferometry (and its various related developments) has allowed to restore the diffraetion limit of large telescopes at visible and infrared wavelengths (see, e. g.

The observation and understanding of extra-solar planetary systems has become a topic that poses challenges to many fields of human knowledge. A few years after the first observational evidence of planets outside the Solar System, this field of research has experienced spectacular developments. One of the characteristics of the field is that it draws together researchers from a variety of fields such as astrophysics, geophysics and biochemistry and opens up new areas for their interactions. This work sets out a synthesis of the advances and points of view of this adventure.

The observation and understanding of extra-solar planetary systems has become a topic that poses challenges to many fields of human knowledge. A few years after the first observational evidence of planets outside the Solar System, this field of research has experienced spectacular developments. One of the characteristics of the field is that it draws together researchers from a variety of fields such as astrophysics, geophysics and biochemistry and opens up new areas for their interactions. This work sets out a synthesis of the advances and points of view of this adventure.

The blossoming of adaptive optical techniques has brought about a revolution in the field of astronomical observation. Coupled with the new generation of large, ground-based telescopes, it allows us to achieve an unprecendented angular resolution in the analysis of faint astronomical sources at optical wavelengths. This book provides the basic concepts of adaptive optics, discusses the possible instrumental strategies and the state-of-the-art technical achievements of this development and presents the key astrophysical programs which will most benefit from it. Over fifteen well-known experts have contributed to making this volume a comprehensive one, with steady progression as well as full coverage of the various aspects of the field. Students graduating in optical sciences and astrophysics, astronomers, engineers interested in atmospheric turbulence compensation will find this book a reference text on the subject.