DIFFRACTION OPTICAL ELEMENT, DESIGN METHOD OF DIFFRACTION OPTICAL ELEMENT

Japanese Patent JP2021076779

A

To provide a diffraction optical element capable of suppressing reduction in diffraction efficiency of high order diffraction light even when the high order diffraction light is diffracted at high angle to suppress zero-order light, and a design method of the diffraction optical element.SOLUTION: A diffraction optical element 10 has a diffraction grating which has a pattern in which when viewed from a normal direction of a surface on which a rugged shape is formed comprising a high refractive index part including a protrusion 11, and a low refractive index part including a recess 12 having lower refractive index than the protrusion 11, a boundary between the protrusion 11 and the recess 12 includes at least one of a curve and a polygonal line connecting a plurality of lines. When the height of the protrusion 11 is denoted by H, the width of the protrusion 11 by WP, an aspect ratio of the protrusion 11 by arP=H/WP, the relation of 3.8