Optical, Mechanical And Thermal Properties Of Calcium Lanthanum Sulphide Compared With The Properties Of Current 8-12 µm Window Materials

The physical property data reported for calcium lanthanum sulphide indicates that it would be an attractive material for high performance 8-12 μm FLIR window applications. However, a number of other available materials may also be considered for aircraft windows operating at temperatures up to 200°C. These are low resistivity germanium (70°C to 100°C), gallium arsenide, multi spectral and standard grade zinc sulphide, zinc sulphide/zinc selenide laminate and zinc selenide. A comparison is presented of the transmittance properties of these materials at room temperature and at 175°C together with room temperature data on the reported optical, mechanical and thermal properties. A qualitative assessment of the likely effectiveness of calcium lanthanum sulphide as a FLIR window material in relation to these existing materials is presented.