| 摘要 |
PROBLEM TO BE SOLVED: To provide a novel projection zoom optical system which offers zooming capability by combining a dioptric lens system and a convex mirror.SOLUTION: A projection zoom optical system constitutes a projection optical system of an image display device, which projects an image displayed on an image display surface of an image display element onto a projection surface as a magnified image, and comprises a dioptric system including four or more lens groups (G1 through G4, and G5 or more) and located on the image display element side, and a convex mirror M1 located on an expansion side of the dioptric system and having negative refractive power, where the entire system has positive refractive power. Magnification is changed by moving some lens groups of the dioptric system along an optical axis. |
