Patent ID: 7988306

Claim:
A projection apparatus comprising: a) at least one spatial light modulator disposed to modulate illumination from a laser light source; b) a base projection lens comprising, from its long conjugate side to its short conjugate side along an optical axis: (i) a first lens group having a negative focal length and having at least a first lens element that has a negative focal length and a second lens element that has a positive focal length; (ii) a second lens group spaced apart from the first lens group and having one or more lens elements, wherein the second lens group has a negative focal length; (iii) a third lens group spaced apart from the second lens group and comprising a lens having a positive focal length; wherein the base projection lens has a first field of view and is telecentric in its short conjugate; and c) an afocal attachment to the base projection lens that alters the first field of view by substantially the same amount in both of two orthogonal directions.