Bi-Concave Spherical Lenses

Thorlabs' N-BK7, N-SF11, UV-fused silica, calcium fluoride, and zinc selenide bi-concave lenses are popular for many applications. Bi-concave lenses have a negative focal length and are best used to diverge a converging beam. Bi-concave lenses can diverge a collimated beam to a virtual focus and are commonly used in Galilean-type beam expanders. For more information on these substrates, please visit our Optical Substrates page.