Patent ID: 9709706
Date: 2017-07-18
CPC Classifications: G02B

Claim:
1. An optical unit, comprising: a wave surface that has a wavelength equal to or shorter than a wavelength of visible light, wherein the wave surface has a curved plane which curves in a recessed shape between an apex portion of the wave surface and a bottom portion of the wave surface, and wherein the wave surface includes a single inflection point of an area of a cross section through the wave surface in a plane perpendicular to a direction of an amplitude variation of the wave surface, wherein the single inflection point is positioned toward the bottom portion of the wave surface from a center of the amplitude variation, wherein a volume va of the wave surface in a first range from a maximum position of the amplitude variation of the wave surface to a first position separate from the maximum position by a distance of a/10, and a volume vb of the wave surface in a second range from a minimum position of the amplitude variation of the wave surface to a second position separate from the minimum position by a distance of a/10 satisfy a relationship va<vb, wherein a is an amplitude of the wave surface, wherein a ratio ((va/V)×100) of a volume va of the wave surface to a volume V of the wave surface is 10% or lower, wherein the volume V of the wave surface is in a third range from the minimum position of the amplitude variation of the wave surface to the maximum position of the amplitude variation of the wave surface.