Deep ultraviolet double concave lens crescent lens, this product is a calcium fluoride (CaF ₂) double concave lens/crescent lens, using ultraviolet grade single crystal material, with excellent transmission in the deep ultraviolet to mid infrared band (190nm~7 μ m). Surface PV ≤ 30nm, RMS ≤ 3nm, roughness Sa ≤ 0.2nm, eccentricity<15 ", smoothness better than 40/20, center thickness tolerance 0.02mm. Supports strict structural customization such as D/R<1.3. Widely used in deep ultraviolet lithography, laser systems, spectral analysis, and quantity detection equipment, it can be customized according to non-standard drawings.