These plano-convex spherical lenses are manufactured from VUV transmitting Calcium Fluoride and are supplied uncoated. Anti-reflection coated lens simply append the desired wavelength in nanometers to the product number. Specifications Material: UV Fused Silica or VUV grade CaF2 Surface Flatness: UVFS:< λ/10 @ 633nm CaF2: < λ/4 @ 633nm Surface Quality : UVFS:<10/5 CaF2: <20/10 Centration Error: ≤3 arcmin Focal Length Tolerance ： <±0.5% Diameter Tolerance: <+0.00/-0.20mm Thickness Tolerance: <±0.25mm Clear Aperture : ≥85% of diameter