Circular polarization filter and application therefor

Patent metadata

Field	Value
Publication number	US-2016103015-A1
Application number	US-201514974969-A
Country	US
Kind code	A1
Filing date	Dec 18, 2015
Priority date	Jun 21, 2013
Publication date	Apr 14, 2016
Grant date	—

Abstract

Provided are a circular polarization filter including a circularly-polarized light separating layer (preferably, a layer having a cholesteric liquid crystalline phase fixed therein or a laminate including a reflective linear polarizer and a λ/4 phase difference layer), in which the circularly-polarized light separating layer selectively transmits either right-handed circularly polarized light or left-handed circularly polarized light in a specific wavelength region, a transparent medium which is transparent with respect to light in the specific wavelength region is provided at least on one surface side of the circularly-polarized light separating layer, and the transparent medium has an inclined surface which forms an angle of 1° to 30° relative to the surface on the transparent medium side of the circularly-polarized light separating layer, and sensor system using the circular polarization filter. The circular polarization filter of the invention is capable of providing circularly polarized light with a high circular polarizance, or improving sensitivity in the sensor system using circularly polarized light.

First claim

What is claimed is:

1 . A sensor comprising a circular polarization filter and a light receiving element, the circular polarization filter comprising a circularly-polarized light separating layer,
wherein the circularly-polarized light separating layer selectively transmits either right-handed circularly polarized light or left-handed circularly polarized light in a specific wavelength region, a transparent medium which is transparent with respect to light in the specific wavelength region is provided at least on one surface side of the circularly-polarized light separating layer, and the transparent medium has an inclined surface which forms an angle of 1° to 30° relative to the surface on the transparent medium side of the circularly-polarized light separating layer, and
the light receiving element being capable of detecting light having a wavelength in the specific wavelength region

2 . The sensor according to claim 1 ,
wherein the circularly-polarized light separating layer is a layer having a cholesteric liquid crystalline phase fixed therein.

3 . The sensor according to claim 1 ,
wherein the circularly-polarized light separating layer is a laminate including a reflective linear polarizer and a λ/4 phase difference layer.

4 . The sensor according to claim 1 ,
wherein the transparent medium is directly brought into contact with or directly adhered to the circularly-polarized light separating layer.

5 . The sensor according to claim 1 ,
wherein the transparent medium is a uniform medium.

6 . The sensor according to claim 5 ,
wherein the difference between a refractive index of the transparent medium and an average in-plane refractive index of the circularly-polarized light separating layer is not greater than 0.05.

7 . The sensor according to claim 1 ,
wherein the inclined surface is an outermost surface.

8 . The sensor according to claim 2 ,
wherein the inclined surface is an outermost surface.

9 . The sensor according to claim 1 , which has the transparent medium on both surfaces of the circularly-polarized light separating layer and has a uniform film thickness.

10 . The sensor according to claim 2 , which has the transparent medium on both surfaces of the circularly-polarized light separating layer and has a uniform film thickness.

11 . The sensor according to claim 1 ,
wherein the specific wavelength region is a wavelength region, having a width of at least 50 nm or greater, within a range of 800 nm to 1500 nm.

12 . The sensor according to claim 2 ,
wherein the specific wavelength region is a wavelength region, having a width of at least 50 nm or greater, within a range of 800 nm to 1500 nm.

13 . The sensor according to claim 1 , further comprising:
a light blocking layer which blocks light in at least a part of a wavelength region excluding the specific wavelength region.

14 . The sensor according to claim 11 , further comprising:
a light blocking layer which blocks light in a wavelength region, having a width of 50 nm or greater, within a range of 380 nm to 780 nm.

15 . The sensor according to claim 12 , further comprising:
a light blocking layer which blocks light in a wavelength region, having a width of 50 nm or greater, within a range of 380 nm to 780 nm.

16 . The sensor according to claim 1 ,
wherein the light receiving element, the circularly-polarized light separating layer, and the transparent medium are disposed in this order.

17 . A sensor system comprising:
the sensor according to claim 1 ; and a light source which emits light having a wavelength in the specific wavelength region.

18 . A sensor system comprising:
the sensor according to claim 16 ; and a light source which emits light having a wavelength in the specific wavelength region.

19 . The sensor system according to claim 17 ,
wherein the light source, the circularly-polarized light separating layer, and the transparent medium are disposed in this order.

20 . The sensor system according to claim 18 ,
wherein the light source, the circularly-polarized light separating layer, and the transparent medium are disposed in this order.

Assignees

• Fujifilm Corp

Inventors

• Ichihashi Mitsuyoshi

Classifications

• G01N21/23

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• G01N21/8422

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• G01N2021/216

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• G01N21/8806

  Specially adapted optical and illumination features · CPC title

• G01N21/958

  Inspecting transparent materials {or objects, e.g. windscreens (for conveyed flat sheet or rod G01N21/896)} · CPC title