next up previous contents
Next: Acknowledgements Up: Title Page Previous: Title Page



Modern astronomy requires ever better performances from its instruments. A main limitation of ground-based telescopes is due to the thermal and aerodynamic disturbances in the atmosphere surrounding the telescope, which are largely caused by the telescope itself and its enclosure.

This thesis presents in a comprehensive manner the issues related to the interaction of a modern telescope with its local atmospheric environment, which is a key aspect in the design of astronomical observatories. Several new notions and methods are described which allow a better understanding of the turbulent phenomena occurring near and inside different types of telescope enclosure. The knowledge acquired on these effects is then applied to new procedures for a global evaluation of telescope performance and contributes to the general progress of the engineering of telescope enclosures.

The wind effects on a large telescope in different enclosure types are described. Wind turbulence affects on the one hand the guiding performance and on the other hand may cause on the relatively thin primary mirrors of large telescopes dynamic deformations resulting on significant optical aberrations. The central topic of this work is the study of local "seeing" effect due to turbulent fluctuations of the refraction index close to the telescope and in particular on the primary mirror. The derivation of theoretical parameterizations, similarity scales and empirical laws applicable to the different phenomena of local "seeing" allows to interpret and compare measurements done by several researchers at scales and with very different conditions. This possibility to quantify and understand all aerodynamic and seeing effects allows to take into account in the design of the observatory all the dynamic and optical effects that affect the telescope performance.

Copyright © 1994 by Lorenzo Zago and EPFL

Lorenzo Zago,, Sun Feb 26 22:57:31 GMT+0100 1995