| 摘要 |
PROBLEM TO BE SOLVED: To provide a capsule type endoscope which can largely take an angle of field for an objective optical system while maintaining a miniaturization, and can perform an observation of a wide range of, e.g., 140°or higher. SOLUTION: This capsule type endoscope 3 is constituted by being built-in a sealed capsule having an illumination unit 37, an imaging means such as a CMOS imager 24 which picks up the image of an area illuminated by the illumination unit 37, the objective optical system 23 in front of the imaging means, and a transparent cover 17 which covers at least the front side of the objective optical system 23. For the capsule type endoscope 3, the outer diameter of the most distal end lens 41 of the objective optical system 23 is made larger than the lens outer diameters of a second lens 42 and a third lens 43 which are located behind the most distal end lens 41, and also, the most distal end lens 41 is formed into a shape which protrudes to the objective side. More preferably, the most distal end lens 41 of the objective optical system 23 is formed into a meniscus shape which protrudes to the objective side so as to have a negative refraction. COPYRIGHT: (C)2005,JPO&NCIPI
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