Patent ID: 8810711

Claim:
A catadioptric optical system comprising: an aperture stop; a first imaging optical system configured to collect a light beam from an object and to form an intermediate image of the object; and a second imaging optical system configured to project the intermediate image on an image plane, wherein the first imaging optical system includes a first optical element that has a light transmissive portion provided on a periphery of an optical axis and a reflective portion provided on a surface at an object side, and a second optical element that has a light transmissive portion provided on the periphery of the optical axis and a reflective portion provided on a surface at an image side, wherein the light beam from the object emits to the second imaging optical system after passing through, in order, the light transmissive portion of the first optical element, the reflective portion of the second optical element, the reflective portion of the first optical element, and the light transmissive portion of the second optical element, and wherein the aperture stop is disposed between the first optical element and the second optical element.