Lightweight optical telescope structures fabricated from CFRP composites

Abstract

CFRP (carbon fiber reinforced plastic) is an attractive material for fabrication of optical systems. The stiffness-to-weight ratio of CFRP is high, the coefficient of thermal expansion is low, the structure thermalizes rapidly, and many of the structural properties can be tailored to the application. We have used CFRP and CFRP-aluminum sandwich panels extensively in the structures of astronomical, optical telescopes up to 1.5m diameter aperture. In designing the optical structures, we have chosen some key fabrication techniques with CFRP that take advantage of the mechanical properties. This paper discusses the design and fabrication of 2 major telescope projects. The 1m ULTRA telescope has both the optics and the OTA fabricated from CFRP. This telescope has been recently installed at the SDSU Mt. Laguna Observatory near San Diego. A 1.4m telescope for the Naval Research Lab is being designed and fabricated at CMA. The optics, OTA, and the mount are all being fabricated using CFRP composites. The result is a lightweight structure which can be moved or deployed as necessary.