Patent ID: 6529336
Filing Date: 2003-03-04
Classification: G02B

Abstract:
A projection lens system for use with a cathode ray tube, said projection lens system having a long conjugate side and a short conjugate side and comprising in order from its long conjugate side:(a) a first lens unit which primarily corrects aperture dependent aberrations, said first lens unit having a short conjugate side and comprising at least one aspherical surface; (b) a second lens unit having a positive optical power; (c) a corrector lens unit comprising at least one aspherical surface; and (d) a third lens unit which is associated with the cathode ray tube during use of the lens system and which provides correction for the field curvature of the lens system, said third lens unit having a long conjugate side; wherein the lens system includes at least one diffractive optical surface which at least partially corrects the axial color of the lens system and which is located between the short conjugate side of the first lens unit and the long conjugate side of the third lens unit.