| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect a focus in high accuracy using a phase difference detection system. <P>SOLUTION: In a focus detector employing an internal measurement type phase difference detection system, a secondary image forming lens 12 has a pair of lens elements 12a and 12b on a plane including the optical axis L of an imaging lens 1 and an optical axis L1 folded by a first mirror 7, the pair of lens elements have an asymmetrical form relative to a plane which is perpendicular to the plane and includes the axis of light incident to the secondary image forming lens, and the lens element 12b on a side far from the optical axis L1 comprises an aspheric lens whose refractive power decreases with the distance from the optical axis L2. <P>COPYRIGHT: (C)2012,JPO&INPIT |
