Patent ID: 7317180

Claim:
An imaging optical system including an optical axis, the imaging optical system comprising: a spherical or nearly spherical transparent viewing port; an objective lens that includes at least one aspheric surface and that optically forms an image of an object along said optical axis; and a solid-state image sensor for converting said image into an electronic signal and having an image-receiving surface perpendicular to said optical axis and intersecting said optical axis at the center of an effective imaging area of the image-receiving surface; wherein at least one of the following conditions is satisfied Δ S/fL <0.4 Δ M/fL <0.4 where ΔS is the distance in the direction of said optical axis between points of a sagittal image surface of said image at distances IH/2 and IH from said optical axis along straight lines perpendicular to said optical axis, and the point at the distance IH is the farthest point from said optical axis within said effective imaging area; fL is the focal length of the entire imaging optical system; and ΔM is the distance in the direction of said optical axis between points of a meridional image surface of said image at distances IH/2 and IH from said optical axis along straight lines perpendicular to said optical axis, and the point at the distance IH is the farthest point from said optical axis within said effective imaging area.