Plano-convex lenses
These are the lenses of the simplest shape: flat on the one side, spherical on the other side. These lenses are widely used in telescopes, microscopes, collimators, optical transmitters, spoils and many other optical systems.
These lenses can be made of various materials: BK7 type glass, fused silica UV FS, calcium fluoride (CaF2). There is a possibility to sputter appropriate anti-reflection coating adapted to specific wavelength or broadband. The lenses have positive focal length from 25 mm up to 10 meters. Standard diameters are 12.5 mm, 25 mm, 40 mm, 50 mm in metric system and 1/2", 1", 1.5", 2" in imperial system.