Plano Concave Spherical lens

Plano-Concave Spherical Lens has a negative focal length and is typically used to cause a collimated beam to diverge as in a Galilean type beam expander or Telescope. Because the spherical aberration of the Plano-Concave lens is negative, it can be used to balance the aberration of other lenses.This lens is widely use in optical display systems, projection optics systems, imaging and laser measureemnt systerms;

Double-Concave Spherical Lens, also named Bi-Concave Lens, is used to divergent light. The Bi-Concave lens is best used when the input beam is converging. It is used in beam expanders,. Projection optics systems, optical viewers and optical charater readers etc.