IR Window/Lens Materials for IR Sensors 2/7/11 Polyethylene Cost: $ Max Transmission (4-8um): 96% Min Transmission (4-8um): 35% Notes: High transmission with exception of 6-7um Polypropylene Cost: $ Max Transmission (4-8um): 92% Min Transmission (4-8um): 2% Notes: Transmittance is good below 5.5um Fresnel Tech Poly IR® 2 http://www.fresneltech.com/ Cost: $ Max Transmission (4-8um): 78% Min Transmission (4-8um): 0% Notes: Good transmission with exception of ~7um Sapphire (Al2O3) Cost: $$ Max Transmission (4-8um): 85% Min Transmission (4-8um): 0% Notes: Durable Material, flat response until 6um Calcium Fluoride (CaF2) Cost: $$$ Max Transmission (4-8um): 93% Min Transmission (4-8um): 92% Notes: Very flat transmission response, water soluble material Germanium (Ge) Cost: $$$ Max Transmission (4-8um): 99% Min Transmission (4-8um): 96% Notes: Requires anti-reflection coating, not reliable above 100C Zinc Selenide (ZnSe) Cost: $$$ Max Transmission (4-8um): 97% Min Transmission (4-8um): 96% Notes: Requires anti-reflection coating, soft material, easily damaged