| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system for an image projection device capable of excellently correcting a trapezoidal distortion of a projected image with a compact configuration.SOLUTION: An optical system for an image projection device PL magnifies an image displayed on an image display element and projects the magnified image in an oblique direction onto a predetermined projection surface. The optical system comprises: an optical element group G1 having mirrors or lenses rotationally symmetric with respect to a central axis; a free-curved surface lens group G2 having free-curved surface lenses rotationally asymmetric with respect to the central axis; and a free-curved surface mirror M2 rotationally asymmetric with respect to the central axis, arranged in this order from an image display element side along an optical axis. The optical element group G1 includes an aspherical mirror M1 which has a reflecting surface in an aspherical shape and is rotationally symmetric with respect to the central axis. |
