Material：BK7 Optical glasses,CaF2,BaF2,
                                           MgF2,Ge,Si,Fused Silica
                                 Diameter Tolerance :+0.0/-0.02mm
                                 Thickness Tolerance : ± 0.01mm
                                 Surface Accuracy : λ/4 @632.8nm
                                 Surface Quality : 20-10
                                 Centration : 1'
                                 Clear Aperture : > 90%
                                 Bevel : 0.2×45°
                                 Coating: user-defined