| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-size high-performance projection optical system.SOLUTION: A refractive optical system is configured to satisfy 0.6<D/Did<0.8 (conditional expression 1) and 2.5<Did/F<6 (conditional expression 2), where Did represents a maximum paraxial image height of an intermediate image in a focusing state in which a projection image is maximum, D represents a maximum value of distance between an optical axis and an intersection of a paraxial image surface and a light beam passing the center of an aperture stop of the refractive optical system 4, and F represents focal length of the refractive optical system 4 in a focusing state in which the projection image is maximum. The refractive optical system 4 includes at least one aspheric lens and forms an intermediate image having a barrel form distortion between a concave mirror 6 and the refractive optical system 4. The barrel form distortion of the intermediate image is corrected by a free curved surface of the concave mirror 6 and projected onto a screen or the like. By satisfying the above conditions, a small-sized high-performance projection optical system can be established. |
