Sapphire Crystal Window Sapphire windows are used in some non-ornamental applications, including infrared optical components, such as in scientific instruments; high-durability windows and movement bearings;Due to sapphire's remarkable hardness (third hardest mineral, right behind diamond and moissanite). Features of Sapphire Crystal 1. High-hardness - abrasion resistance 2. Transparency - in the range from ultraviolet to infrared light (0.15 - 5.5 �µm) 3. Chemical resistance and heat resistance - resist almost all kinds of acid and alkaline, heat up to 2000 �ºC. 4. Suitable for the application of insulation property required. Sapphire Crystal Property Crystal structure: Hexagonal Lattice: a=4.785�?, C=12.991�? Density: 3.98g/cm3 Transmission Range: 150-5500nm Melting Point: 2040�°C Specific Heat: 0.418 W.s/g/K Thermal Conductivity: 25.12 W/m/K Thermal Shock Resistance: 790 W/m Thermal Expansion Coefficient: 5.8x10E-6/K dn/dT: 13x10E-6/K @633nm Hardness: 9 Mohs Refractive Index: 1.83 @0.26mm, 1.76 @0.63mm, 1.58 @5.57m Sapphire Crystal Applications - UV and IR Optics - Windows for High Temperature and Pressure, Corrosion Resistance, Abrasion Resistance - Heat Sink and Thermocouplers; Semiconductor Wafer Carriers - Electrical Insulators - Thin Film Deposition - Transparent Electronic Substrate - Silicon on Sapphire Wafers; Superconductor Substrate Sapphire Crystal Window Specifications Diameter Tolerance(mm): +0.0/-0.2 (General), +0.0/-0.1 (High Precision) Thickness Tolerance(mm): �±0.2 (General), �±0.05 (High Precision) Clear Aperture: >75% (Small Size), >90% (Large Size) Parallelism: 3 min. (General), 10 sec. (High Precision) Surface Quality: 80/50 (General), 40/20 (High Precision) Flatness (per 25mm@633nm): �»(General), �»/4 (High Precision) Bevel (face width x 450 0)