Canon Patent Application: New type of Diffractive Optics element

Canon over the years continues to research diffractive optics, but this is the first time that I've seen something that they are doing differently to the actual diffractive structure. In this patent application, Canon is looking to reduce the flare that is due to the shape of the grating by adding elements onto the wall surface and also on the sloped surface.

In Canon's words;

A first resin layer having a diffraction grating shape composed of a plurality of wall surfaces and a plurality of slopes and a second resin layer are sequentially laminated on a base material, and a refractive index is higher than the first resin layer and the second resin layer. In a diffractive optical element in which a high refractive index portion having a high refractive index is formed on a wall surface, a contact portion that is discontinuous with the high refractive index portion is formed on the slope. Further, the thickness of the contact portion is made smaller than the height of the wall surface.

The patent goes into the methods of how to manufacture such an element.

Japan Patent Application 2020-027130