Patent ID: 6297860
Filing Date: 2001-10-02
Classification: G02B

Abstract:
A projection lens system for use with a cathode ray tube, said system having an image side and comprising in order from said image side:a) a corrector lens unit of weak optical power, said unit comprising in order from said image side:i) a first lens element which has a negative power on axis and comprises at least one aspherical surface, said first lens element being composed of a high dispersion material; andii) a second lens element which has a positive power and is composed of a low dispersion material;b) a power lens unit providing most of the positive optical power of the lens system;c) a lens unit of weak optical power comprising at least one aspherical surface; andd) a lens unit which has a strong negative power, is associated with the cathode ray tube during use of the lens system, and provides most of the correction to the field curvature of the lens system.