Development of Zinc Sulfide Seeker Window Material

Ground based interceptors require the use of dual color focal planes or wideband seekers for improved target acquisition and target discrimination. The transmission capabilities of the current window material have a limited waveband. A material which has the ability to transmit at higher wavelengths may be required. An analysis conducted on alternate seeker window materials using rigorous computational fluid dynamics to predict the worst case aerodynamic heating combined with finite element thermal and structural analysis was used to construct a statistical analysis model. This model, supported by test data, was used to predict window reliability incorporating size effects. The results showed that multispectral zinc sulfide exceeded the current THAAD requirements. In addition to the performance attributes of an alternate seeker window, zinc sulfide offers significant cost benefits and it is estimated that the current seeker window cost would be reduced by 70-80%. This effort will establish statistical flexural strength data for multispectral zinc sulfide material fabricated using the same procedures as the current window material. The data will be measured at ambient, worst case, and intermediate temperature levels. The information will be used to substantiate multispectral zinc sulfide as a candidate replacement window material for the THAAD interceptor.