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Proceedings Paper

Hard transparent domes and windows from magnesium aluminate spinel
Author(s): Anthony A. DiGiovanni; Larry Fehrenbacher; Don W. Roy
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Paper Abstract

Transparent magnesium aluminate spinel is an attractive material for use in a wide range of optical applications including windows, domes, armor, and lenses, which require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the everincreasing performance requirements of current and next-generation IR imaging systems. Future designs in missile technology will require materials that can meet stringent performance demands in both optical and RF wavelengths. Loss characteristics for spinel are being investigated to meet those demands. Technology Assessment and Transfer Inc. (TA&T), have established a 9000 ft2 production facility for optical quality spinel based on the traditional hot-pressing followed by hot isostatic pressing (HIPing) route. Additionally, TA&T is developing pressureless sintering - a highly scalable, near net shape processing method based on traditional ceramic processing technology - to fabricate optical components. These two main processing approaches allow the widest variety of applications to be addressed using a range of optical components and configurations. The polycrystalline nature of spinel facilitates near net shape processing, which provides the potential to fabricate physically larger optical parts or larger quantities of parts at significantly lower costs compared to single crystal materials such as sapphire. Current research is focused at optimizing the processing parameters for both synthesis routes to maximize strength and transparency while minimizing the cost of fabrication.

Paper Details

Date Published: 18 May 2005
PDF: 8 pages
Proc. SPIE 5786, Window and Dome Technologies and Materials IX, (18 May 2005); doi: 10.1117/12.603953
Show Author Affiliations
Anthony A. DiGiovanni, Technology Assessment & Transfer (United States)
Larry Fehrenbacher, Technology Assessment & Transfer (United States)
Don W. Roy

Published in SPIE Proceedings Vol. 5786:
Window and Dome Technologies and Materials IX
Randal W. Tustison, Editor(s)

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