There are several military or commercial systems operating in very harsh environments that require rugged
windows. On some of these systems, windows become the single point of failure. These applications
include sensor or imaging systems, high-energy laser weapons systems, submarine photonic masts, IR
countermeasures and missiles. Based on the sea or land or air based platforms the window or dome on
these systems must withstand wave slap, underwater or ground based explosions, or survive flight through
heavy rain and sand storms while maintaining good optical transmission in the desired wavelength range.
Some of these applications still use softer ZnS or fused silica windows because of lack of availability of
rugged materials in shapes or sizes required. Sapphire, ALON and spinel are very rugged materials with
significantly higher strengths compared to ZnS and fused silica. There have been recent developments in
spinel, ALON and sapphire materials to fabricate in large sizes and conformal shapes. We have been
developing spinel ceramics for several of these applications. We are also developing β−SiC as a transparent
window material as it has higher hardness, strength, and toughness than sapphire, ALON and spinel. This
paper gives a summary of our recent findings.