OPTICAL ELEMENT AND SURFACE LIGHT SOURCE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical element and a surface light source device which can achieve uniform surface emission while keeping a short distance in emission direction in a system where a light source is provided just below the optical element.SOLUTION: An optical element 30 comprises at least one prism group formed by a plurality of prism apexes 32 spirally extending from a central axis 31 toward the outer edge, on the surface of a flat plate.