US 12,147,058 B2
Diffractive optical element, projection device, and measurement device'
Ryota Murakami, Fukushima (JP); and Motoshi Nakayama, Fukushima (JP)
Assigned to AGC INC., Tokyo (JP)
Filed by AGC INC., Tokyo (JP)
Filed on Nov. 1, 2022, as Appl. No. 18/051,738.
Application 18/051,738 is a continuation of application No. 17/114,985, filed on Dec. 8, 2020, granted, now 11,536,981.
Application 17/114,985 is a continuation of application No. PCT/JP2019/022570, filed on Jun. 6, 2019.
Claims priority of application No. 2018-110909 (JP), filed on Jun. 11, 2018.
Prior Publication US 2023/0108188 A1, Apr. 6, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 5/18 (2006.01); G01B 11/25 (2006.01); G02B 27/42 (2006.01); G02B 27/44 (2006.01)
CPC G02B 27/4222 (2013.01) [G01B 11/2513 (2013.01); G02B 27/44 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A diffractive optical element comprising:
a substrate;
a protrusion and recess portion that is formed on one surface of the substrate and imposes predetermined diffraction on incident light; and
an antireflection layer provided between the substrate and the protrusion and recess portion, wherein:
an effective refractive index difference Δn in a wavelength range of the incident light between a first medium constituting a protrusion of the protrusion and recess portion and a second medium constituting a recess of the protrusion and recess portion is 0.70 or more;
an exit angle range θout of diffraction light exiting from the protrusion and recess portion when the incident light enters the substrate from a normal direction of the substrate is 60° or more; and
reflectance of the antireflection layer for at least particular polarized light in a wavelength range of 360 nm to 370 nm, incident on the antireflection layer at 20° or less with respect to a normal direction of the substrate, is 1.0% or less.