| 摘要 |
PROBLEM TO BE SOLVED: To provide an endoscope which has an expanded depth of field and a simple structure and keeps optimum parameters. SOLUTION: In the endoscope having an imaging optical system 4 for forming the image of a photographic subject and an image pickup element, a crystal optical element 5 is arranged on the optical path of the imaging optical system, double foci F1, F2 are formed in the optical axis 9 direction of the imaging optical system, and the following conditional expression is satisfied. 2≤Δz/(Fno×P)≤9 (1). Here,Δz: amount of a deviation of focal position in the optical axis direction at the screen center, Fno: effective F number of the imaging optical system, P: pixel pitch of the image pickup element. COPYRIGHT: (C)2007,JPO&INPIT
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