Optical design of a giant telescope: aspheric versus spherical design

Eli Atad-Ettedgui

doi:10.1117/12.566204

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7 July 2004 Optical design of a giant telescope: aspheric versus spherical design

Eli Atad-Ettedgui

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Proceedings Volume 5382, Second Backaskog Workshop on Extremely Large Telescopes; (2004) https://doi.org/10.1117/12.566204
Event: Second Backaskog Workshop on Extremely Large Telescopes, 2003, Backaskog, Sweden

Abstract

The optical design of a giant telescope depends on a large number of parameters. A system approach is necessary in which these parameters are listed and studied. One of the main parameter is the number of segments filling the primary mirror: is the aperture filled with a few large segments (8-m class segments) or a large number of medium size segments (1 to 2-m)? We will evaluate the pro's and con's of these two options. The second parameter is the asphericity of the primary mirror: a giant spherical mirror (>30-m) is easier to manufacture in mass production by filling the aperture with identical segments, making it easy to replace and test but the spherical aberration introduced is very large and need to be compensated by adding extra optical components which are large and difficult to manufacture. The aspherical mirror simplifies the optical design but is difficult to manufacture and test. We will review these two options. Optical design concepts of a giant telescope are shown and a comparison is made between the Spherical, the Ritchey-Chretien and the Gregorian optical models.

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Eli Atad-Ettedgui "Optical design of a giant telescope: aspheric versus spherical design", Proc. SPIE 5382, Second Backaskog Workshop on Extremely Large Telescopes, (7 July 2004); https://doi.org/10.1117/12.566204

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