US 12,117,633 B2
Optical filter
Kengo Sasayama, Tokyo (JP)
Assigned to Asahi Kasei Microdevices Corporation, Tokyo (JP)
Filed by Asahi Kasei Microdevices Corporation, Tokyo (JP)
Filed on Jul. 5, 2023, as Appl. No. 18/346,857.
Application 18/346,857 is a continuation of application No. 17/656,275, filed on Mar. 24, 2022, granted, now 11,740,396.
Application 17/656,275 is a continuation of application No. 16/833,672, filed on Mar. 30, 2020, granted, now 11,320,572, issued on May 3, 2022.
Claims priority of application No. 2019-220521 (JP), filed on Dec. 5, 2019.
Prior Publication US 2023/0358933 A1, Nov. 9, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 5/28 (2006.01); G01N 21/3504 (2014.01); G01N 33/00 (2006.01)
CPC G02B 5/281 (2013.01) [G01N 21/3504 (2013.01); G01N 33/0047 (2013.01); G02B 5/285 (2013.01); G01N 2201/062 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An optical filter for an optical device comprising:
a substrate and a multilayer film having a plurality of layers with different refractive indexes formed on at least one side of the substrate; wherein
the multilayer film has a structure in which a first layer and a second layer are alternately stacked, the first layer has a refractive index of 1.2 or more and 2.5 or less in a wavelength range of 6 μm to 10 μm, and the second layer has a refractive index of 3.2 or more and 4.3 or less in a wavelength range of 6 μm to 10 μm; and
the optical filter includes a wavelength range having an average transmittance of 70% or more with a width of 50 nm or more in a wavelength range of 6 μm to 10 μm, and has a maximum transmittance of 10% or more in a wavelength range of 12.5 μm to 20 μm.