* Material：
Optical Glass, Quartz, BK7, CaF2, Sapphire, MgO, ZnS, Ge, Si, BaF2
* Diameter Tolerance: +/-0. 15 mm
* Angle Tolerance: +/-3arc minutes
* Surface Figure: λ/2 @632. 8nm
* Surface Quality: 20-10
* Clear Aperture: Central 90% of diameter