Plano-concave Lens

A plano-concave lens has a flat surface on one side and a concave surface on the other, with the middle part thinner than the two sides. Having a negative focal length, used to diverge a beam of parallel light. A beam of parallel light can be converted into divergent light, which will focus in the opposite direction at the virtual focal point of the lens. Used for applications such as beam collimation, increasing (decreasing) focal length, or enlarging (reducing) images.