| 摘要 |
<p>A compact and bright imaging optical system having a high resolution. The imaging optical system comprises three reflectors, i.e. a first reflector (1), a second reflector (2) and a third reflector (3), arranged in the order of optical path of incident light not to shield the incident light. In the imaging optical system, light beams reflected on the three reflectors form an image forming plane (4). A convex mirror is employed in any one of the first reflector (1) or the third reflector (3) and a concave mirror is employed in the other, the vertexes of a triangular dipyramid (6) are defined for a central main light beam (5) by an appropriate point on the central main light beam (5) which enters to the first reflection surface, the reflecting point of each central main light beam on the first through third reflection surfaces, and the image forming point of the central main light beam. A plane including three reflection points of the central main light beam on the first through third reflection surfaces matches a plane sticking two triangular pyramids forming the triangular dipyramid (6).</p> |
