Patent ID: 8254038
Filing Date: 2012-08-28
Classification: A61B,G02B

Abstract:
1. An optical element, that is part of an optical system, and that is made of a transparent medium that is rotationally symmetric relative to the central axis with a refractive index greater than 1, wherein the transparent medium has a first transmissive surface arranged at the outermost periphery relative to the central axis, a first reflective surface arranged at the side of the central axis relative to the first transmissive surface, a second reflective surface arranged at the side opposite to the image plane relative to the first reflective surface and a second transmissive surface arranged at the image plane side relative to the second reflective surface, that the flux of light entering the transparent medium goes into the transparent medium by way of the first transmissive surface so as to be reflected to the side opposite to the image plane by the first reflective surface and then to the image plane side by the second reflective surface to form an optical path before going out from the transparent medium at the image plane side by way of the second transmissive surface in the order of forward ray tracing and that the optical path is formed only at a side relative to the central axis, and the meridional cross section of the second transmissive surface represents negative power and that the optical element satisfies the condition of where P2 is the power of the second transmissive surface and Pm is the power of the entire optical system in which the optical element is included at the meridional cross section of the central principal ray of light.