Imaging optical system having bending optical element

摘要

An imaging optical system includes a bending optical element which bends an object-emanating light bundle, a post-bending lens system on a post-bending optical axis defined by the bending optical element, and an image sensor. An effective optical surface of a large-diameter lens element, having a greatest axial light bundle effective radius, is formed into a non-circular shape by making a length of the effective optical surface from the post-bending optical axis toward a side opposite from the object side smaller than the axial light bundle effective radius, with reference to the axial light bundle effective radius lying on a plane which extends orthogonal to a plane including both the post-bending optical axis and a pre-bending optical axis of the imaging optical system and includes the post-bending optical axis.

主权项

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:
RU>RL, (RU+RL)<2RH, and0.5<{(RU+RL)/2RH}<0.09, 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.