| 摘要 |
PROBLEM TO BE SOLVED: To provide a flat and compact imaging optical system that can image a wide area under close-up imaging and has a substantially telecentric incident ray on an object side. SOLUTION: The imaging optical system, which includes an image forming optical system having at least one positive lens, and an imaging element, is provided with a planar element group having a positive refractive power on an object side of the image forming optical system, and satisfies conditional expression (1): LL/AFL<3.4, where AFL is the focal length of the imaging optical system and LL is an air-equivalent distance of the overall length of the imaging optical system. COPYRIGHT: (C)2009,JPO&INPIT
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