Patent ID: 7542211

Claim:
A catadioptric system comprising: at least three reflecting surfaces; wherein when said three reflecting surfaces are defined as a first reflecting surface, a second reflecting surface, and a third reflective surface in order along a light path, these reflecting surfaces forming a reflecting optical system; at least one lens positioned in an entrance-side light path of said reflecting optical system; and at least one lens positioned in an exit-side light path of said reflecting optical system; at least one of said first and second reflecting surfaces being a rotationally symmetric aspherical surface; said first reflecting surface and said third reflecting surface being connected to each other with a step interposed therebetween; said first reflecting surface and said third reflecting surface facing approximately in a same direction; and said three reflecting surfaces being positioned such that when an optical axis of an optical path from said entrance-side lens to said first reflecting surface, an optical axis of an optical path from said first reflecting surface to said second reflecting surface, an optical axis of an optical path from said second reflecting surface to said third reflecting, surface and an optical axis of an optical path from said third reflecting surface to said exit-side lens are each projected onto a virtual surface including an optical axis of said entrance-side light path and an optical axis of said exit-side light path, wherein the respective optical axes do not intersect.