AFOCAL ATTACHMENT FOR PROJECTION LENS

摘要

A projection apparatus has a spatial light modulator to modulate illumination from a laser light source. A base projection lens has, from its long conjugate side to its short conjugate side, a first lens group with negative focal length and with a first lens element that has a negative focal length and a second lens element of positive focal length, a second lens group of negative focal length and spaced apart from the first lens group and having one or more cemented lens elements, and a third lens group spaced apart from the second lens group and having a lens with a positive focal length. The base projection lens has a first field of view and is telecentric in its short conjugate. An afocal attachment to the base projection lens alters the first field of view by the same amount in both of two orthogonal directions.