Low Cost IR Windows for High Stress Environments

A revolutionary sparse aperture IR window for the extreme thermodynamic environments encountered by atmospheric interceptors is proposed. The novel window consists of a window bed material that provides passive cooling during the exposure to thehypersonic environment and sparsely distributed optical ports that effectively image the optical signature during the threat vehicle engagement. This window system is conceptually easy to manufacture and consists of components that are relativelyinexpensive compared with current monolithic window materials such as sapphire. Initial estimates suggest that this new IR window is an order of magnitude less expensive than current window technology. In the Phase I effort, a preliminary window designemphasizing tradeoffs between sparse aperture imaging and passive cooling techniques will be developed and assessed. Furthermore, using existing algorithms, detailed simulations of sparse aperture imaging will be undertaken to establish the technicalfeasibility of the concept. The Phase II effort would center on the testing of the sparse aperture window concept with and without representative thermal loads. The proposed revolutionary IR window concept is directly applicable to all hypersonicinterceptors operating in the atmosphere. This includes existing systems for endo-atmospheric interceptors, new concepts focused on boost-phase intercepts, and other futuristic trans-atmospheric vehicles with speeds ranging from 3 to 8 km/s. The passivecooling technique is also applicable to thermal protection of high-speed interceptors. The window is attractive on a manufacturing and a cost basis compared with monolithic windows.