| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection optical system which is bright, wide angle, and well corrected for aberrations, and features reduced size and cost of a lens group closest to an image display element to minimize chances of causing interference with an illumination optical system and the like.SOLUTION: A projection optical system is for magnifying and projecting an image displayed on an image display element LV onto a screen, and is configured to have an F-number of F1.77 or less and a half view angle ω of 35.0° or greater and to be non-telecentric on the reduction side. The projection optical system has a first lens group G1 on the magnification side of an aperture stop ST located in a middle section of the optical system and a second lens group G2 on the reduction side of the aperture stop ST. The first lens group G1 includes at least two aspherical lenses La, Lb, while the second lens group G2 includes at least one aspherical lens Lc. A composite focal length f1 of the first lens group G1, a composite focal length f2 of the second lens group G2, and a composite focal length f of the entire system satisfy the following conditional expressions: [1] 4.5<f1/f<9.5, [2] 3.1<f2/f<4.4.SELECTED DRAWING: Figure 2 |
