In the framework of many EL-OP projects there was increasing interest in large optical windows for protecting infrared
There are many solutions for dual visible and midwave infrared windows, but for windows larger than 300 mm in
diameter only clear Zinc Sulfide is available. When large area windows are required Zinc Sulfide becomes heavy, costly,
and with significant optical scattering.
Sapphire and ALON<sup>TM</sup> (Aluminum -oxynitride) were chosen as candidates for the transparent ceramic due to their high
strength, availability and low optical scattering. As mentioned above these materials are not available in the form of large
windows thus a joining technique was necessitated.
Three main joining processes were investigated: Adhesive Bonding, Optical Glass Bonding -OGB and diffusion
bonding, which were expected to result in good optical transmittance and moderate to good mechanical performance.