Optical filters complementary angular blocking regions

Patent metadata

Field	Value
Publication number	US-11899230-B2
Application number	US-202217746170-A
Country	US
Kind code	B2
Filing date	May 17, 2022
Priority date	Oct 18, 2016
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

An example optical filter may include an angle blocking layer having a first angular light blocking range θAL relative to a normal axis, and an interference filter adjacent the angle blocking layer having a second angular light blocking range θIF relative to the normal axis. θIF and θAL at least partially overlap. The example optical filter has a predetermined light transmission zone comprising angles from 0° to a maximum light transmission angle θTmax relative to a normal axis of the major surface. The example optical filter has a predetermined angular light blocking zone θB, a union of θIF and θAL. An example optical filter may include an interference filter having an incidence angle-dependent reflection band and an absorbing layer having an absorption band. The incidence angle-dependent reflection band and the absorption band may overlap at at least one wavelength at at least one angle of incidence.

First claim

The invention claimed is:

1. An optical filter comprising:
an angle blocking layer having a first angular light blocking range θ AL relative to the normal axis, wherein the first angular light blocking range θ AL has an upper limit less than 90°, wherein the angle blocking layer has a predetermined light leakage angular transmission zone, and wherein the predetermined light leakage angular transmission zone θ AL extends from the upper limit of the first angular light blocking range θ AL to 90°;
an interference filter having an incidence angle-dependent reflection band, wherein the interference filter has a second angular light blocking range θ IF relative to the normal axis, wherein θ B is a union of θ IF and θ AL , wherein θ IF and θ AL at least partially overlap, and wherein the predetermined light leakage angular transmission zone of the angle blocking layer is covered by the second angular light blocking range θ IF of the interference filter; and
an absorbing layer having an absorption band, wherein the incidence angle-dependent reflection band and the absorption band overlap at at least one wavelength at at least one angle of incidence.

2. The optical filter of claim 1 , wherein the interference filter comprises one or both of a birefringent multilayer optical film or an isotropic film.

3. The optical filter of claim 1 , wherein the interference filter has a characteristic transmission spectrum comprising the incidence angle-dependent reflection band, wherein the angle-dependent reflection band has a band edge that shifts lower when an angle of incidence is reduced.

4. The optical filter of claim 3 , wherein the angle-dependent reflection band of the interference filter includes a wavelength transmitted by the absorbing layer.

5. The optical filter of claim 1 , wherein the interference filter comprises a wavelength selective absorber.

6. The optical filter of claim 1 , wherein the absorbing layer comprises a wavelength selective absorber.

7. A system comprising:
a sensor; and
an optical filter of claim 1 .

8. The system of claim 7 , further comprising a light source.

9. The system of claim 7 , further comprising a reflector, wherein the reflector defines one or more of a specular reflecting surface, a diffuse reflecting surface, or a retroreflective surface.

10. A system comprising:
a light source; and
an optical filter of claim 1 .

11. The system of claim 10 , further comprising a reflector, wherein the reflector defines one or more of a specular reflecting surface, a diffuse reflecting surface, or a retroreflective surface.

Assignees

• 3M Innovative Properties Company

Inventors

• Wheatley John A
• Du Guanglei
• Benoit Gilles J
• Biernath Rolf W

Classifications

• G02B5/28 Primary

  Interference filters · CPC title

• G02B5/003

  Light absorbing elements · CPC title

• G02B5/045

  Prism arrays · CPC title

• G02B5/208

  for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation · CPC title

• G02B2207/123

  Optical louvre elements, e.g. for directional light blocking · CPC title