PROJECTION OPTICAL SYSTEM AND VIDEO-ENLARGING AND PROJECTING SYSTEM USING PROJECTION OPTICAL SYSTEM, AND VIDEO PROJECTOR, AND PROJECTION TELEVISION

摘要

PROBLEM TO BE SOLVED: To provide a projection optical system capable of inexpensively achieving thinning of housing by using an aspherical mirror, and a video-enlarging and projecting system or the like using the projection optical system.;SOLUTION: The projection optical system which enlarges and projects the image of a spatial modulation element 1 to a screen 4 is equipped with one aspherical mirror 3, turning its convex surface to the screen 4 and symmetric with respect to an optical axis; and a dioptric system 2, constituted of a plurality of lenses including an aspherical surface and a spherical surface, in this order starting from the screen 4. Assuming that the minute displacement in the radial direction of the aspherical mirror 3 is Y, the minute displacement in a direction orthogonal to the radial direction is sag on the cross section, including the optical axis of the aspherical mirror 3, and the tilt of the tangent of the cross section is sag/Y, the maximum value |max(sag/Y)| of the absolute value of sag/Y, from the vicinity of the optical axis of the aspherical mirror to the maximum effective radius of the aspherical mirror, satisfies 0.48|max(sag/Y)|0.7.;COPYRIGHT: (C)2007,JPO&INPIT