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| Substrate Material: | High purity UV fused silica (semiconductor std VIOSIL, used for photomask substrate) |  
| Outer Diameter: | 67.0,-0.5/+0.0mm |  
| Thickness: | 12.0, +/-0.2mm |  
| Surface Quality: | Double side polished (40-20 scratch and dig, MIL Standard) |  
| Surface Flatness: | <Lambda/10 @ 632.8nm over 25mm area on two surfaces over clear aperture |  
| Parallemism: | <1 arc minute |  
| Clear Aperture | >90% of outer diameter |  
| Edge Surface: | 1.0mm x 45-deg protection chamfer |  
| Surface Coating: | Double side, extra-low absortption full dielectric/high damage threshold AR coating @ 1064nm,R<0.2% @1064nm(0-deg AOI); High energy laser applications |  
| Packing: | 1pc/pack (vacuum packed) |  |