Abstract
Significant reduction in weight of optomechanical systems is possible through the use of three new technologies: metal matrix composite materials, Meinel type telescope structures, and shape optimization of mirror substrates. These technologies are successfully employed in a 400 mm aperture f/1.5 dual channel visible/infrared catadioptric telescope system designed and built at the Optical Science Center, University of Arizona. This system is designed for remote control and is operated in an environment characterized by wide temperature shifts as well as severe mechanical vibration. The telescope is a 400 mm aperture f/5 Ritchey-Chretien, with a 1 degree field of view. A Meinel type telescope structure is employed in combination with a single arch sandwich mirror to reduce telescope weight to about 7 kg. An aluminum reinforced with silicon carbide metal matrix composite is used thorughout the telescope, with a metal matrix composite foam as the shear core of the sandwich primary mirror. The dual channel optical bench employs a high performance focal reducer and is constructed of the same type of metal matrix composite used in the telescope. A passive athermalization scheme provides optical aberration correction over a wide range of temperatures, and is combined with a motorized internal focus to avoid moving the telescope secondary. Design and construction of the telescope was facilitated by a process of interactive optical design, computer aided mechanical layout, and finite element analysis. System performance was successfully simulated prior to final assembly using results from actual optical tests. The final system displayed good performance and represents a successful first use of a number of technologies, including the foam core single arch metal matrix composite primary mirror.
