Patent ID: 7408703

Claim:
A wide-angle imaging optical system comprising: a refractive optical system having one or more lenses; a reflective optical system; and an image-forming optical system, wherein the reflective optical system and the image-forming optical system are arranged in the indicated order as seen from a longer conjugate distance side and constitute a first optical system, and the refractive optical system and the image-forming optical system are arranged in the indicated order as seen from the longer conjugate distance side and constitute a second optical system, wherein the reflective optical system comprises a first reflection surface that directly reflects rays of light from an object, and a second reflection surface that reflects rays of light from the first reflection surface, wherein the refractive optical system comprises at least one lens located on an object side of the second reflection surface, wherein an open portion is provided between the first reflection surface and the second reflection surface, and rays of light from the object enter the open portion, wherein a light-transmitting portion is provided in the second reflection surface and transmits rays of light that have entered the refractive optical system, and wherein an aperture is provided in the first reflection surface and allows rays of light from the second reflection surface and rays of light that have entered the light-transmitting portion from the refractive optical system to enter the image-forming optical system, and wherein no intermediate image is formed inside the wide-angle imaging optical system.