... special needs SpecificationsMaterialSapphire, Silicon, GemaniumRadiusR≥3.0Surface FinishN<3,N≥λ/4Centration≥1’Diameter≥3.0 ±0.01mmT/D1/10Surface Quality20 ... GlassRadiusR≥1.5Surface FinishN<2,N≥λ/8Centration≥1’Diameter≥3.0 ±0.01mmT/D1/10Surface Quality20/10Bevel0.25mm at ... also can be make professionally:plano-convex lense, plano-concave lense,double convex lense,double concave lense,meniscus lense, ...