Diffractive optical element, optical apparatus using the same, and method for manufacturing diffractive optical element

A method for manufacturing a diffractive optical element including a first resin layer formed on a substrate and having a diffraction grating shape including a plurality of wall surfaces and a plurality of slopes, and a second resin layer stacked in this order on the substrate, and a high refractive-index portion formed on the plurality of wall surfaces and having a higher refractive index than the first and the second resin layers, the method comprising:

• forming the first resin layer having the diffraction grating shape including the plurality of wall surfaces and the plurality of slopes on the substrate;
• forming the high refractive-index portion having a higher refractive index than the first and the second resin layers, on the plurality of wall surfaces of the first resin layer;
• forming a close contact portion discontinuous with the high refractive-index portion on the plurality of slopes of the first resin layer so that a thickness of the close contact portion becomes smaller than a height of the plurality of wall surfaces;
• and
• forming the second resin layer on the first resin layer.