Description: Lightweight, steady and stiff mirrors are necessary to decrease cost of telescopes such as IXO and GenX used in special NASA missions. Low-density materials are ideal for use as mirrors in such applications. Beryllium has been traditionally considered ideal for lightweight mirrors requiring high rigidity. The toxicity of beryllium poses a major problem. Polished Silicon Carbide (SiC), prepared by Chemical Vapor Deposition (CVD), is the current material of choice for fabrication of mirrors in lightweight telescopes. However, CVD is a complex and expensive technique and the quality of SiC produced is very sensitive to the processing conditions. MMI proposes to utilize a novel displacement reaction to obtain fully dense B4C based composite mirrors with unique microstructural features. Phase I will involve preparing the lightweight optical mirror material and evaluating their mechanical, thermal and optical properties. Phase II will involve optimization of the processing, consolidation and polishing procedures for the composite. In collaboration with industrial partners, who manufacture special purpose optics, mirrors will be fabricated and tested in Phase II for use in various applications.

Benefits: - optical mirror for vacuum ultraviolet (VUV) and X-ray applications - used in UV telescopes for space astronomy because of its high normal incidence reflectance - space applications with adequate cryogenic stability and high resistance to degradation from atomic oxygen, trapped charges such as electrons, protons and high energy photons

- laser focusing mirror applications (LIDAR) - optical materials for synchrotron applications (mirror used for synchrotron radiation in large electron storage rings must withstand high X-ray flux without degradation or excessive thermal distortion, which affects transmission and energy resolution.)