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|1. (WO2018135500) DIFFRACTION LENS AND VEHICULAR LAMP USING SAME|
|Applicants:||MAXELL JOEI TECH CO., LTD.
|Title:||DIFFRACTION LENS AND VEHICULAR LAMP USING SAME|
The purpose of the present invention is to provide a diffraction lens that is thin with excellent forming properties and can excellently form an image of a cutoff line for low beams in a vehicular lamp using a white light source. Provided is a diffraction lens having a protruding shape on both the light ray incident side and exit side, wherein the lens has an exit diffraction surface with an absolute value for the order of diffraction of 5 or greater disposed on the exit side, and has a shape such that the absolute value of the curvature at the surface apex of the envelope surface for the exit diffraction surface is smaller than the absolute value of the curvature at the surface apex on the incident surface, or the absolute value of the sag amount in the direction of the optical axis at the outer peripheral part of the envelope surface for the exit diffraction surface is smaller than the maximum absolute value for the sag amount in the direction of the optical axis at the outer peripheral part of the incident surface.