| 摘要 |
PROBLEM TO BE SOLVED: To provide an image pickup optical system for an endoscope which has an approximately spherical observation window enabling a cost reduction and enables the acquisition of a sufficiently excellent image quality. SOLUTION: The image pickup optical system is comprised of a transparent observation window 16, an objective lens 18 of which the side of the image is a nonspherical surface and a solid image pickup device 23, and satisfies the following conditions to a substance B on the surface of the observation window 16:ΔS/f<SB>L</SB><0.4 orΔM/f<SB>L</SB><0.4, where f<SB>L</SB>is the focal length of the image pickup optical system,ΔS is the width in a direction of an optical axis of a sagittal image plane in the range from IH/2 to IH, when a distance from the center to the farthest position in an effective image pickup area in the image pickup surface of the solid image pickup device is defined as IH, andΔM is the width in the direction of the optical axis of a meridional image surface in the range from IH/2 to IH. COPYRIGHT: (C)2007,JPO&INPIT |
