| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small-sized door camera which is small in the diameter of an incident surface and is short in an overall length by having an optical element which has the incident surface, reflection surfaces having plural curvatures and an image forming effect consisting of an exit surface and an image picking up element. SOLUTION: The luminous flux 2 from an object is regulated in its incident light quantity by a diaphragm 9 after passage through protective glass 3 and is made incident on the incident surface S1 of the optical element 5. After the luminous flux is reflected by the reflection surface S2 and S3, the luminous flux primarily forms an image. The luminous flux is thereafter successively reflected by the reflection surfaces S4 and S5 and are emitted from the exit surface S6, thereby forming the image on a solid-state image pickup plate 8 via an optical correction plate 6. The direction of the incident optical axis incident on the optical element 5 and the direction of the exit optical axis emitted therefrom are parallel and the same. The optical element 5 has the function as an image forming lens to form the real image over the entire part having the desired optical performance by the refracting power by the incident and exit surfaces S1 and S6 and the refracting power by the plural reflection surface S2 to S5 among these surfaces. The reflection surface S2 to S5 consist of eccentric systems.
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