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.

Inhalt

I: Basic principles.- to Fourier Optics and Coherence.- Optical Propagation and Image Formation Through the Turbulent Atmosphere.- Radio Telescopes: Basic Concepts.- Continuously Movable Telescopes for Optical Interferometry.- II: Module and phase estimation, image reconstruction.- Amplitude Estimation from Speckle Interferometry.- Notes on Noise Calibration of Speckle Imagery.- Amplitude Estimation from Diluted Array Interferometry.- First Order Imaging Methods: An Introduction.- Speckle Imaging with the Papa Detector and the Knox-Thompson Algorithm.- Phase Closure Imaging - Theory & Practice.- Speckle Masking, Speckle Spectroscopy, and Optical Aperture Synthesis.- Merits of Phase Restoration Methods.- Pupil-Plane Interferometry.- Real-Time Wavefront Sensing and Adaptive Optics.- Differential Interferometry.- Image Restoration.- Deconvolution Ancient and (Very) Modern.- III: Scientific and technical prospects.- Astrophysical Programs for High Angular Resolution Optical Interferometry.- Frontiers of Interferometry.- Perspectives in Optical Interferometry.- IV: Contributed seminars and posters.- Cophasing Telescope Arrays.- Some Thoughts on the Combination of Beams in Interferometers Using Telescopes of Unequal Size.- Real-Time Image Sharpening.- Scasis, Diffraction-Limited Imaging Using a Redundant Pupil Plane-Interferometer.- Aperture Synthesis in Space: Overview and Results from the Esa Study Group.- Estimation and Reconstruction from Aberrated Amplitude Interferometer Measurements.- Lunar Occultations or Milliarcsecond Resolution and Their Relation to Interferometric Techniques at Present and in Future.- List of posters.