Biconvex lenses
All the biconvex lenses are symmetrical, with the same radius of curvature on both sides. They are recommended for virtual imaging of real objects. Since both sides of the lens have influence on its power, it has a shorter focal length than plano-convex lens of equal diameter and surface radius.
These lenses can be made of various materials: BK7 type glass, fused silica UV FS, calcium fluoride (CaF2). There is a possibility of applying a suitable anti-reflective layer adapted to a specific wavelength or broadband. These lenses have a positive focal length from 12.7 mm up to 120 centimeters. Standard diameters are 12.5 mm, 25 mm, 40 mm, 50 mm in the metric system and 1/2 ", 1", 1.5 "and 2" in the imperial system.
