Bi-convex lens element

BK7UV

Thorlabs' BK7, UV-fused silica, ZnSe, and calcium fluoride bi-convex lenses are popular for many finite imaging applications. Bi-convex lenses are most suitable where the object and image are on opposite sides of the lens and the ratio of the image and object distances (conjugate ratio) is between 0.2 and 5.