200*232*12mm Ge window(coating DLC/BBAR) Effective aperture (%): 90.00 dimensional tolerance (mm): +0.0/-0.1 Thermal expansion coefficient CTE (10-6/C): 6.1 density (g/cm3): 5.33 Refractive index nd: 4.002 @ 11 m Knoop hardness (kg/mm2): 780.00 Parallelism (arc points):