Ultra-lightweight, Deployable 1m-Class Optical Telescope for SSA Applications

Deployable Optical/IR telescopes must be lightweight and rugged enough to withstand being placed from one location to another, in mostly adverse environments. This requires unique materials that are light, stiff and dimensionally stable in most any environment including a space environment. Continuous fiber reinforced polymer (CFRP) composite materials have been used to produce ultra-lightweight optical telescopes. Their thermal/mechanical properties offer advantages over conventional materials in terms of thermal expansion, stiffness and strength. The anisotropic nature of the material allows for weight and stiffness-optimized designs of dimensionally stable structures, ideal for telescopes. Optical mirrors can be produced from CFRP composites as well; yielding 1m diameter rigid primary mirrors weighing 12 kg. Presented will be unique telescope and mirror fabrication leading to extremely lightweight OTA systems up to 1.4m for the Navy Prototype Optical Interferometer, NPOI. The 1.4m NPOI Telescope, being produced by CMA, is required to be deployable along the baselines of the interferometer. We present the design of this system and how it evolved from various deployable concepts for optical telescopes. 2. CFRP MATERIAL ADVANTANGES Carbon Fiber Reinforced Polymer (CFRP) composite materials offer many of the same advantages of SiC and Beryllium and certainly greater advantages over more conventional telescope materials. Unidirectional laminates are appropriate for low CTE structures such as strut tubes. Multi-angle laminates are used to produce plate elements with “quasi-isotropic behavior. CFRP material allows for tailoring properties of structures and mirrors. See figure X for graphic representation of ply-orientations. The following are advantages for using CFRP materials to produce lightweight, deployable optical systems