Patent ID: 8098320

Claim:
An imaging device comprising: a housing including a first photographing aperture and a second photographing aperture which are open toward opposite directions; an image pickup device provided in said housing; a main optical system which forms first incident light from said first photographing aperture onto an imaging surface of said image pickup device, said main optical system defining a main optical axis extending from said first photographing aperture to said image pickup device; and an insertable optical element which has a refractive power, and which is movable in an inserting/removing direction between an insertion position in an optical path of said main optical system and a removed position out of said optical path of said main optical system, wherein said insertable optical element constitutes at least a part of a sub-optical system which forms second incident light from said second photographing aperture onto said imaging surface of said image pickup device when said insertable optical element is positioned at said insertion position, said sub-optical system defining a sub-optical axis extending from said second photographing aperture to said image pickup device via said insertable optical element, wherein, when said insertable optical element is positioned in said insertion position, said sub-optical axis is offset from said main optical axis toward said removed position of said insertable optical element in said inserting/removing direction, wherein said image pickup device is mounted to a wall of said housing which includes said first photographing aperture, wherein said main optical system comprises: a first reflecting member which reflects said incident light from said first photographing aperture at a substantially right angle; and a second reflecting member which reflects said light reflected by said first reflecting member at a substantially right angle toward said image pickup device, wherein said insertable optical element includes a third reflecting member which is inserted into and removed from an intermediate optical path of said main optical system between said first reflecting member and said second reflecting member, and said third reflecting member reflects said incident light from said second photographing aperture toward said second reflecting member when said third reflecting member is inserted in said intermediate optical path of said main optical system, and wherein said inserting/removing direction of said insertable optical element is orthogonal to a plane defined by an intermediate optical axis of said main optical axis that extends from said first reflecting member to said second reflecting member and an exit optical axis of said main optical axis that extends from said second reflecting member to said image pickup device.