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Proceedings Paper

Recent developments in transparent spinel ceramic and composite windows
Author(s): Shyam Bayya; Guillermo Villalobos; Woohong Kim; Jas Sanghera; Geoff Chin; Michael Hunt; Bryan Sadowski; Fritz Miklos; Ishwar Aggarwal
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Paper Abstract

The U.S. Naval Research Laboratory has pioneered the development of sintering processes for making highly transparent optical ceramics. For example, we have demonstrated the fabrication of record low absorption loss spinel as an exit window for High Energy Laser systems and rare earth doped Y2O3 and Lu2O3 for solid-state ceramic lasers. We have also developed thick spinel windows for submarine photonic masts and predicted the performance of an imaging system using testing and modeling. More recently, we have developed a novel approach of hot pressing where a transparent ceramic is produced in the net shape without requiring post polishing. This technology will result in significant cost savings associated with polishing the final optical element. We are also developing motheye structures on spinel surface to provide rugged anti-reflective solutions. We had earlier identified a Barium GalloGermanate (BGG) glass with matching index and expansion coefficient to spinel. We had demonstrated fabrication of a laminated dome for the Joint Air to Ground Missile (JAGM) program and the technology was transitioned to industry. We have pushed this technology further by developing a BGG glass – spinel ceramic transparent micro-composite, which can be processed well below spinel sintering temperatures. To address the relatively lower strength of BGG glass compared with spinel, we developed an ion-exchange process and achieved strengths up to 450 MPa. This paper gives a summary of our recent findings.

Paper Details

Date Published: 30 September 2013
PDF: 9 pages
Proc. SPIE 8837, Material Technologies and Applications to Optics, Structures, Components, and Sub-Systems, 88370V (30 September 2013);
Show Author Affiliations
Shyam Bayya, U.S. Naval Research Lab. (United States)
Guillermo Villalobos, U.S. Naval Research Lab. (United States)
Woohong Kim, U.S. Naval Research Lab. (United States)
Jas Sanghera, U.S. Naval Research Lab. (United States)
Geoff Chin, University Research Foundation (United States)
Michael Hunt, University Research Foundation (United States)
Bryan Sadowski, Sotera Defense Solutions, Inc. (United States)
Fritz Miklos, Sotera Defense Solutions, Inc. (United States)
Ishwar Aggarwal, Sotera Defense Solutions, Inc. (United States)

Published in SPIE Proceedings Vol. 8837:
Material Technologies and Applications to Optics, Structures, Components, and Sub-Systems
Joseph L. Robichaud; Matthias Krödel; William A. Goodman, Editor(s)

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