| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive, compact and thin optical system and to provide electronic equipment using the same. SOLUTION: The optical system at least includes a stop 2, at least two reflecting surfaces 12, 22, 23 inclined from an optical axis, at least one rotationally asymmetric aspherical refraction surface 11, 13, 21, 24, and an image pickup device 3. Regarding all reflecting surfaces inclined from the optical axis 1, when the reference plane for each reflecting surface is given by a plane defined by an entrance-side on-axis chief ray and a reflection-side on-axis chief ray regarding each reflecting surface, at least two reflecting surfaces 12, 22, 23 have rotationally asymmetric aspherical shape, and when the reference plane for one reflecting surface 12 of the reflecting surfaces and the reference planes for the other reflecting surfaces 22, 23 cross at an optional angle and the cross line of the reflecting surface and its reference plane is set as the cross line of each reflecting surface, all the reflecting surfaces having the rotationally asymmetric aspherical shape of the reflecting surfaces satisfy a condition (1) related to the ratio of the radius of curvature in the cross line direction of each reflecting surface to the radius of curvature direction perpendicular to the cross line direction. COPYRIGHT: (C)2006,JPO&NCIPI
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