A plano-convex lens has a positive focal length and converges incident light rays. It can form a real image (an image formed on paper) or a virtual image (when used as a magnifying glass, it can form a virtual image on the same side as the object). It is widely used in telescopes, collimators, optical transceivers, magnifying glasses, radiometers and condensers. The commonly used materials for plano-convex lenses are BK7 (optical glass), fused silica, ZnSe, Zns, Ge and other infrared materials.