Flat convex lenses are an ideal choice for focusing parallel light rays onto a point, and these lenses can be used for various applications. They have proven focal lengths and have near optimal shapes for conjugate applications at infinity and finite distances. A plano convex lens can converge a collimated beam at the back focal point, or turn a point light source into a collimated beam. The flat convex lenses produced by Dingxinsheng are usually made of K9 glass, and their anti reflective coating is designed for the wavelength range of 400-700 nanometers. UV quartz is also used as the substrate for processing. When UV quartz is used as the substrate, it has good transmittance and low expansion coefficient in the UV region, and can be coated with UV AR film for special use.