Patent ID: 6195209
Filing Date: 2001-02-27
Classification: G02B

Abstract:
A projection lens for forming an image of an object which consists in order from its image end to its object end of:(A) a first lens unit U.sub.1 having a negative power and comprising three lens elements E.sub.P, E.sub.N, and E.sub.N', arranged in any order and having focal lengths f.sub.U1/P, f.sub.U1/N, and f.sub.U1/N', V-values V.sub.U1/P, V.sub.U1/N, and V.sub.U1/N', and Q-values Q.sub.U1/P, Q.sub.U1/N, and Q.sub.U1/N', respectively;(B) a second lens unit having a positive power; and(C) an optional field lens unit;wherein E.sub.N or E.sub.N' is made of glass and wherein:f.sub.U1/P >0,f.sub.U1/N <0,f.sub.U1/N' <0,V.sub.U1/N >V.sub.U1/P,V.sub.U1/N' >V.sub.U1/P,Q.sub.U1/N >0,Q.sub.U1/N >Q.sub.U1/P,Q.sub.U1/N >V.sub.U1/N,Q.sub.U1/N' >0, andQ.sub.U1/N >Q.sub.U1/P.