Christopher Wilcox, (Naval Research Laboratory), Jonathan R. Andrews (Naval Research Laboratory), Sergio R. Restaino (Naval Research Laboratory), Ty Martinez (Naval Research Laboratory), Scott W. Teare (New Mexico Institute of Mining and Technology), Robert
Romeo (Composite Mirror Applications), Don M. Payne (Narrascape)
Keywords: Optical telescope, Adaptive Optics
Abstract:
A 0.4 meter Carbon-Fiber Reinforced Polymer (CFRP) Optical Telescope Assembly (OTA) has been developed as a prototype by the Naval Research Laboratory (NRL) and Composite Mirror Applications (CMA). All components of this OTA have been made from the CFRP material, including the optics, and this has dramatically reduced the weight of the overall structure. The only components of this OTA that are not CFRP are the metal fittings, screws and the silvered mirror surfaces. The use of this material increases the portability of this OTA and can reduce the cost of future telescopes. However, because this material is more lightweight than the materials traditionally used in OTA construction, the vibration characteristics are different and obtaining optical surface quality is non-trivial. This paper investigates certain structural properties of this OTA through the use of accelerometers attached and measurements taken statically and dynamically. Some measurements include the movement of the telescope at different speeds indoors and outdoors, as well as on and off a traditional tripod. Also, an impulse response measurement is obtained by tapping a weight to the OTA structure and the damping time is measured through the oscillations measured by the accelerometers. This OTA prototype is being developed for two future projects. The first being the development a 1.4 meter CFRP OTA for the upgrade of the Naval Prototype Optical Interferometer and the second being a lightweight deployable 0.4 meter CFRP OTA with adaptive optics. Furthermore, the properties of this CFRP material not only reduce the weight of the OTA, but the coefficient of thermal expansion is controlled such that this approach is very attractive for space-based telescopes which, because of the light weight, can be deployed into space at a dramatically lower cost than traditional telescopes.
Date of Conference: September 10-14, 2006
Track: Poster