Model optical systems for 8-m telescopes

This report considers the optics of single versatile telescopes, rather than MMTs and interferometers. There are many new points to consider in the optical design which make the problems of the eight-meter different from those of previous telescopes. A wide-field focus is required at 6-8 ft, but should not conflict with the need to switch between Cassegrain and Nasmyth positions; this can lead to a new type of design. It is not necessary to use either of the textbook optical systems, Cassegrain or Ritchey-Chretien (R-C), at the f-number, but all possibilities must be considered. The present paper describes detailed possibilities for systems of the R-C type, and further work in progress on conventional Cassegrain and intermediate systems is outlined for completeness and comparison.