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