Patent ID: 9435507
Filing Date: 2016-09-06
CPC Classification: F21V,F21Y

Claim Text:
1. An optical element, comprising: a light receiving surface which is configured to cover a light source disposed on a plane, and an exit surface which covers the light receiving surface, the optical element being configured such that light from the light source passes through the light receiving surface and the exit surface and goes to the outside for illumination, wherein when an axis which passes through the center of the light source and which is perpendicular to the plane is designated as an optical axis and the point of intersection of the optical axis and the light receiving surface is designated as O1, the light receiving surface is concaved around the optical axis with respect to the periphery, and wherein in a cross section of the optical element, the cross section containing the optical axis and being perpendicular to the plane, when an angle which a normal to the light receiving surface on a point P on the light receiving surface forms with the optical axis is designated as φh and distance in the optical axis direction from the point O1 to the point P is designated as z, the light receiving surface is configured such that φh has at least one local maximum value and at least one local minimum value with respect to z while the point P is moved along the light receiving surface from the point O1 to the plane.