The author is most grateful to the Ecole Polytechnique Fédérale de Lausanne and its Laboratoire de Systèmes Energetiques - LASEN for the opportunity to present the present thesis. Particular thanks to Prof. G. Sarlos, head of the LASEN, for accepting and carrying the function of thesis director, and to Dr. J.-A. Hertig who first supported the idea of this dissertation and followed it all along with extremely useful discussions and comments. My warm thanks also to C. Alexandrou for his careful reading of the draft and helpful suggestions.
I thank Prof. H. van der Laan, previous director of ESO, for his encouragement to propose this thesis and his recommendation to EPFL. My employment at ESO for 9 years on the development of the Very Large Telescope observatory constituted a great professional opportunity.
This research work is quite inter- and pluri-disciplinary and integrates results obtained in collaboration with several ESO colleagues in the framework of the VLT project: the contributions of L. Noethe on the evaluation of optical quality of a deformed mirror and the one of F. Plötz in the evaluation of telescope performance under wind, are particularly acknowledged. I also thanks M. Sarazin for the many exchanges of information and views on the issues of atmospheric turbulence and seeing, as well as Ph. Diericks who is the author of the computer program SuperIMAQ which has been invaluable for this work.
Many experimental results reported in this work have been obtained during contracts to various laboratories issued by ESO and coordinated by the author. I would like to cite in particular the Technical University of Aachen (Dr. A. Ruscheweyh), the LASEN itself, and the Danish Maritime Institute (Dr. T. Reynold).
A special acknowledgement shall go to the CFHT observatory and its director Dr. Couturier for making available the data log files recording the image quality of 3 full years of observation. Those data represent the most complete experimental measurements done so far on the local seeing problem and the author is very grateful for the possibility of analyzing them. Many thanks also to Dr. F. Rigaut of the CFHT who transmitted me the data and answered many questions on their correct interpretation.