No abstract

Surface plates and blocking tools are commonly made of granite because of its good stability. But how stable is the granite, and which type of material is optimal? We have explored several materials and manufacturing processes for a 4-m aspheric reference surface that would serve as a tool for laying up composite optics. In this paper, we discuss the materials selection, stability to thermal and moisture effects, and parameters for processing the surface to give sub-micron accuracy and stability.

For many years, lightweighted sandwich-style mirror blanks made from Corning's Ultra-Low Expansion glass (ULE ™ ) have been used in space telescope systems that demand superior optical performance. Despite the superior performance of this technology, the historically high cost and long schedule to procure such a blank has limited their use to only the most elite missions. Future missions, such as JWST, will seek to dramatically reduce the historical cost/schedule paradigm for ULE ™ blanks by capitalizing on economies-of-scale associated with a multi-segment design. However, for this blank technology to become accessible to a broader range of missions, fundamental changes in technical and business approaches are needed. Over the last four years, ATK COI has worked to develop the requisite technologies to produce ULE ™ mirror blanks in-house, with an emphasis on reducing cost and schedule. Our focus has been in three areas: process development to enable reclamation of ULE ™ glass residuals, glass fusion process qualification, and tooling cost reduction. The status of each of these areas is presented, and conclusions drawn about possible future costs of lightweight ULE ™ mirror blanks. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/29/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 5179 19 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/29/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx