Patent ID: 6853493
Filing Date: 2005-02-08
Classification: G02B

Abstract:
1. A projection lens for forming an enlarged image of a pixelized panel on a screen, said projection lens having an optical axis, a long conjugate side, a short conjugate side, and an effective focal length f 0 , said lens comprising in order from the long conjugate side to the short conjugate side: (A) a first lens unit having a negative power and comprising a plurality of lens elements, wherein: (B) a reflective surface for folding the projection lens' optical axis; and (C) a second lens unit having a positive power and comprising a plurality of lens elements, wherein:   S 1-2 /f 0 >3.5, where the mechanical spacing is the smaller of the center-to-center distance and the edge-to-edge distance between S 1 and S 2 for an unfolded optical axis; and where (i) the red-blue and red-green relationships are satisfied over the full field in the short conjugate focal plane, (ii) the blue-green relationship is satisfied over at least 95% of the full field in the short conjugate focal plane, and (iii) the red, green, and blue wavelengths are 0.62 micrometers, 0.55 micrometers, and 0.46 micrometers, respectively.