Patent ID: 9465199
Filing Date: 2016-10-11
CPC Classification: G02B

Claim Text:
1. An imaging optical system, comprising: a bending optical element which bends a light bundle emanating from an object; a post-bending lens system arranged on a post-bending optical axis defined by an optical axis of said imaging optical system being bent by said bending optical element; and an image sensor, on which an image of said object is formed via said post-bending lens system; wherein an effective optical surface of a large-diameter lens element, having an axial light bundle effective radius that is greatest among those of all lens elements of said post-bending lens system, is configured into a non-circular shape by a length of said effective optical surface from said post-bending optical axis toward a side opposite from the object side being smaller than said axial light bundle effective radius, with reference to said axial light bundle effective radius lying on a plane which includes said post-bending optical axis and extends orthogonal to a plane including both said post-bending optical axis and a pre-bending optical axis of said imaging optical system, wherein said non-circular shape of said effective optical surface satisfies the following conditions: wherein when viewed in a direction along said post-bending optical axis, where an upper direction designates a direction parallel to a pre-bending optical axis and travelling toward the object side, a lower direction designates a direction opposite to said upper direction, and a horizontal direction designates a direction that is orthogonal to a plane on which both said pre-bending optical axis and said post-bending optical axis lie, wherein RU designates a distance between said post-bending optical axis and an outermost point of said effective optical surface of said large-diameter lens element in said upper direction within the axial light bundle effective radius, wherein RL designates a distance between said post-bending optical axis and an outermost point of said effective optical surface of said large-diameter lens element in said lower direction within said axial light bundle effective radius, and wherein RH designates a distance between said post-bending optical axis and an outermost point of said effective optical surface of said large-diameter lens element in said horizontal direction within said axial light bundle effective radius.