Focal Reducer/Wide-Field Corrector for the C.E. Kenneth Mees Telescope
Laurie Tuttle
Abstract
Introduction of CCD astronomical imaging has had a tremendous impact on the astrophysical community. The greatest advantage to CCD astronomical imaging is the phenomenal increase in efficiency when compared to photographic plate imaging. Images which previously required exposure times in the range of several hours can be captured in a matter of seconds using a CCD astronomical imaging system. The disadvantage to using a CCD for astronomical imaging is the loss of information capture due to the change in size of the detector area. Originally equipped with a Boller and Chivens 3" x 5" photographic plate, the Mees telescope provided a 0.4 degree full-field angle.
The purpose of
the research was to design a focal reducer to reduce the
focal ratio of the telescope system from f/13.5 to f/4.5 to enable a larger
field of view to be imaged onto the smaller CCD detector area with a
9-
Several focal reducer/wide-field corrector designs were configured using OSLO. None of the designs using only readily available lens database components met the design criterion. Determination has been made to abandon the restriction to the lens database components in favor of a customized focal reducer/wide-field corrector design. Preliminary research suggests two possible design configurations for the customized focal reducer/wide-field corrector. The first design would consist of a 6" diameter, f/2 collimating lens located at the telescope mounting flange followed by a f/4.5 fully corrected camera system. A second design would consist of a symmetrical Biotar focal reducer design. The Biotar design would require extensive optimization using OSLO. Preliminary research suggests the Biotar design might provide a more fully corrected system.