Patent ID: 6476974
Filing Date: 2002-11-05
Classification: G02B

Abstract:
A projection lens having an aperture stop, an optical axis, a long conjugate side, a short conjugate side, a power &PHgr;0, and a back focal length BFL, said projection lens being adapted to form an image of a pixelized panel and consisting in order from said long conjugate side to said short conjugate side of:(A) a first lens unit having a power &PHgr;U1 and comprising at least one aspheric surface; and (B) a second lens unit having a power &PHgr;U2 and consisting in order from said long conjugate side to said short conjugate side of: (i) a first lens subunit having a power &PHgr;S1; (ii) a second lens subunit having a power &PHgr;S2 and an overall meniscus shape which is concave towards the short conjugate; and (iii) a third lens subunit having a power &PHgr;S3 and a surface S3 at its long conjugate side; wherein: (a) &PHgr;U1<0; (b) &PHgr;U2>0; (c) &PHgr;S1>0; (d) &PHgr;S2<0; (e) &PHgr;S3>0; (f) BFLâ€¢&PHgr;0&gE;1.0; and (g) the aperture stop is either within the third lens subunit or spaced from surface S3 in the direction of the long conjugate by a distance D which satisfies the relationship: Dâ€¢&PHgr;0&lE;0.1.