Concentric optical system

摘要

A concentric optical system usable as either an imaging optical system or an ocular optical system, which has an F-number of 1.5 to 3 and enables a flat and clear image to be photographed or observed at a view angle of up to 60 DEG or more with substantially no aberration. The concentric optical system includes at least two semitransparent reflecting surfaces (2) and (3) each having a center of curvature disposed in the vicinity of a pupil (1) and a concave surface directed toward the pupil. The semitransparent reflecting surfaces are disposed so that each semitransparent reflecting surface passes each particular bundle of light rays at least once and reflects them at least once, thereby providing a flat image surface (4).