CN111247405A - Polarization camera device - Google Patents

Polarization camera device Download PDF

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Publication number
CN111247405A
CN111247405A CN201880068721.2A CN201880068721A CN111247405A CN 111247405 A CN111247405 A CN 111247405A CN 201880068721 A CN201880068721 A CN 201880068721A CN 111247405 A CN111247405 A CN 111247405A
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group
ring
carbon atoms
photoreactive
single bond
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CN111247405B (en
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坂本盛嗣
野田浩平
小野浩司
川月喜弘
筒井皇晶
后藤耕平
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Nissan Chemical Corp
Nagaoka University of Technology NUC
University of Hyogo
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Nissan Chemical Corp
Nagaoka University of Technology NUC
University of Hyogo
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/447—Polarisation spectrometry
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/02—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J4/00—Measuring polarisation of light
    • G01J4/04—Polarimeters using electric detection means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B11/00—Filters or other obturators specially adapted for photographic purposes

Abstract

The invention provides a polarization imaging device capable of utilizing snapshot to perform polarization imaging measurement without a mechanical working part, in particular a polarization imaging device without high-precision alignment of a polarization element, and more particularly a polarization imaging device which is low in cost. The present invention provides a polarization imaging apparatus, comprising: an anisotropic diffraction grating element, a lens element, and a light receiving element, in which optical anisotropy is periodically modulated.

Description

Polarization camera device
Technical Field
The present invention relates to a polarization imaging apparatus including an anisotropic diffraction grating.
Background
Various methods have been reported since ancient times for measuring the polarization state.
The most representative methods of polarization measurement include a rotary analyzer method and a rotary phase shifter method using a rotating polarizer and a wave plate. In these methods, a time waveform of light intensity corresponding to the polarization state of incident light is observed while rotating a polarizing element. And further carrying out Fourier analysis on the obtained time waveform to recover the information of the Stokes parameters. The method is characterized by long research history, reduced errors and high measurement precision. However, since information required for recovery of the stokes parameter is acquired in multiple times while temporally rotating the polarization element, it is not suitable for an object whose polarization state changes temporally. When polarization measurement is applied to medical devices, remote sensing, and the like, the necessity of measuring the polarization state of a dynamic object is extremely high, and polarization spatial distribution measurement using a snapshot is required.
As a polarimetric method of a polarization camera that makes polarization spatial distribution measurement using a snapshot possible, there are several precedents before the present invention.
An example thereof is: a wave plate and/or a polarizing plate that divides the optical axis direction thereof into 4 directions are distributed on the light receiving element array, and measurement corresponding to a rotary analyzer method and/or a rotary phase shifter method is performed for every 4 pixels (non-patent document 1 or 2). In the method, a mechanical working part for rotating the polarization element is not required, and further, information required for acquiring the stokes parameter can be obtained by one-time image acquisition, so that static imaging polarization measurement by using a snapshot is possible. However, it is necessary to accurately match the positions of the array of light receiving elements and the array of polarizing elements, and the manufacturing is not easy. Further, there is a concern that diffracted light which is not preferable in measurement may be generated due to discontinuity of the phase difference generated at the boundary portion of the polarizer array.
Another example of past research that has made polarization imaging with snapshots possible is: an imaging polarimeter using a polarization savart plate using a spatial carrier when polarized light interferes (non-patent document 3).
In this method, the influence of diffraction as in the case of the array element described above is not generated. However, this method requires expensive optical elements such as a savart board, and thus has a problem of increasing the cost.
Documents of the prior art
Non-patent document
Non-patent document 1: sato, T.Araki, Y.Sasaki, T.Tsou, T.Tadokoro, and S.Kawakami, "Compact encapsulating a static polar module with attached polar and wave-plate elements," appl.Opt.46,4963-4967(2007).
Non-patent document 2: g.myhre, w.l.hsu, a.peidino, c.lacase, n.brock, r.a.chip, and s.pau, "Liquid crystal polymer full-stocks division of focal plane polar analyzer," opt.express 20, 27393-.
Non-patent document 3: luo, K.Oka, E.DeHoog, M.Kudenov, J.Schiewgerling, and E.L.Dereniak, "Compact and minor snap imaging polar", appl.Opt.47,4413-4417(2008).
Disclosure of Invention
Problems to be solved by the invention
Accordingly, an object of the present invention is to provide a polarization imaging apparatus capable of performing polarization imaging measurement using a snapshot without requiring a mechanical working unit, in particular, a polarization imaging apparatus not requiring high-precision alignment with respect to a polarization element, and more particularly, a polarization imaging apparatus which is relatively inexpensive in terms of cost.
Means for solving the problems
The present inventors have found the following invention.
< 1 > a polarization imaging apparatus having: an anisotropic diffraction grating element, a lens element, and a light receiving element, in which optical anisotropy is periodically modulated.
In the case of < 2 > or < 1 >, it is preferable that the anisotropic diffraction grating element has an anisotropic diffraction grating having a plurality of lattice vectors with different directions from each other, and at least the anisotropic orientation or birefringence of the lattice vectors is periodically modulated.
In the above-mentioned < 1 > or < 2 > of < 3 >, it is preferable that the anisotropic diffraction grating element has: and an anisotropic diffraction grating for spatially separating information of Stokes parameters of incident light according to the distribution of anisotropic azimuth and birefringence and converting the information into intensity information.
< 4 > any of the above < 1 > -to < 3 >, it is preferable that the anisotropic diffraction grating element comprises an anisotropic diffraction grating having a photoreactive polymer film having photoreactive side chains that undergo at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
In any of the above-mentioned items < 5 > to < 1 > to < 4 >, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating formed of a photoreactive polymer film.
In any one of < 6 > to < 1 > to < 5 >, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating having:
I) a first transparent substrate layer; and
II) a first photoreactive polymer membrane having a first photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
< 7 > any one of the above < 1 > - < 4 > and < 6 >, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating having:
III) a second transparent substrate layer; and
IV) a second photoreactive polymer membrane having a second photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization,
the II) first photoreactive polymer film and the IV) second photoreactive polymer film are disposed to face each other, and (B) a low molecular liquid crystal layer is disposed between the II) first film and the IV) second film.
In any of the above-mentioned < 8 > and < 4 > - < 7 >, it is preferable to use an anisotropic diffraction grating that forms an arbitrary diffraction pattern on a photoreactive polymer film by subjecting the polymer film to interference exposure with desired polarized light, thereby spatially separating information on stokes parameters of light incident on the polymer film according to the distribution of the birefringence and the anisotropic azimuth formed in the polymer film and converting the information into intensity information.
< 9 > any of the above < 1 > to < 8 >, it is preferable that the anisotropic diffraction grating element has an anisotropic diffraction grating having a good diffraction efficiency for light of + -1 order.
< 10 > any one of the above-mentioned < 4 > -to < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having 1 type of photoreactive side chain selected from the group consisting of the following formulas (1) to (6)
(wherein A, B, D each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
s is C1-C12 alkylene, and hydrogen atoms bonded on the S are optionally substituted by halogen groups;
t is a single bond or C1-12 alkylene, and hydrogen atoms bonded on the T are optionally substituted by halogen groups;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
Y2is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y1The same definition;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
cou represents coumarin-6-yl or coumarin-7-yl, the hydrogen atoms bonded to which are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
one of q1 and q2 is 1 and the other is 0;
q3 is 0 or 1;
p and Q are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-8 alicyclic hydrocarbon, and combinations thereof; wherein, in the case where X is-CH-CO-O-, -O-CO-CH-and P or Q on the side to which-CH-is bonded is an aromatic ring, when the number of P is 2 or more, P is optionally the same as or different from each other, and when the number of Q is 2 or more, Q is optionally the same as or different from each other;
l1 is 0 or 1;
l2 is an integer of 0 to 2;
when l1 and l2 are both 0, A represents a single bond when T is a single bond;
when l1 is 1, B represents a single bond when T is a single bond;
h and I are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, and combinations thereof. ).
Figure BDA0002461194880000051
< 11 > any one of the above-mentioned < 4 > -to < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having any 1 type of photoreactive side chain selected from the group consisting of the following formulas (7) to (10)
(wherein A, B, D each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a benzene ring or naphthalene having a valence of 1A ring of a C5-8 alicyclic hydrocarbon, a biphenyl ring, a furan ring, a pyrrole ring, or 2-6 rings selected from these substituents, which may be the same or different, bonded via a linking group B, wherein the hydrogen atoms bonded to these rings are each independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12;
m represents an integer of 0 to 2, m1 and m2 represent an integer of 1 to 3;
n represents an integer of 0 to 12 (wherein, when n is 0, B is a single bond);
Y2is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y1The same definition).
Figure BDA0002461194880000061
< 12 > any one of the above-mentioned < 4 > -to < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having any 1 type of photoreactive side chain selected from the group consisting of the following formulas (11) to (13)
(wherein A's each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 represents an integer of 1 to 3;
r represents a ring selected from among 1-valent benzene rings, naphthalene rings, biphenyl rings, furan rings, pyrrole rings and C5-8 alicyclic hydrocarbons, or a group in which 2 to 6 identical or different rings selected from among these substituents are bonded via a linking group B, and hydrogen atoms bonded to each of these are independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2and-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, or R represents a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms).
Figure BDA0002461194880000071
< 13 > any of the above-mentioned < 4 > -to < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having a photoreactive side chain represented by the following formula (14) or (15)
(wherein A's each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
l represents an integer of 1 to 12, and m1 and m2 represent an integer of 1 to 3).
Figure BDA0002461194880000081
< 14 > any of the above < 4 > - < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having a photoreactive side chain represented by the following formula (16) or (17) (wherein A represents a single bond, -O-, -CH)2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, and m represents an integer of 0 to 2).
Figure BDA0002461194880000082
< 15 > any one of the above-mentioned < 4 > -to < 9 >, it is preferable that the photoreactive polymer film has a photoreactive polymer having any 1 kind of photosensitive side chain selected from the group consisting of the following formulas (18) and (19)
(wherein A, B each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
one of q1 and q2 is 1 and the other is 0;
l represents an integer of 1 to 12, m1 and m2 represent an integer of 1 to 3;
R1to representHydrogen atom, -NO2、-CN、-CH＝C(CN)2and-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms).
Figure BDA0002461194880000091
In any of the above-mentioned items < 16 > to < 4 > to < 9 >, the photoreactive polymer film preferably has a photoreactive polymer having a photoreactive side chain represented by the following formula (20)
(wherein A represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0(in the formula, R0Hydrogen atom or C1-5 alkyl group), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, and m represents an integer of 0 to 2).
Figure BDA0002461194880000092
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide a polarization imaging apparatus capable of performing polarization imaging measurement using a snapshot without requiring a mechanical working unit, in particular, a polarization imaging apparatus not requiring high-precision alignment with respect to a polarization element, and more particularly, a polarization imaging apparatus which is relatively inexpensive in terms of cost.
Drawings
Fig. 1 shows a schematic diagram of a multiple recording anisotropic diffraction grating.
FIG. 2 shows diffraction characteristics of PL-based gratings IA±、IB±、IC±Graph of the dependence of the amplitude ratio angle Ψ for incident polarized light.
Fig. 3 is a diagram illustrating an outline of the polarization imaging apparatus of the present invention.
Fig. 4 is a diagram illustrating a configuration of a polarization imaging device used in the embodiment.
Fig. 5 is an image of the result of image measurement performed using the polarization imaging device used in the example, using a blackish green tortoise (Mimela spleenens) as a subject.
FIG. 6 illustrates extraction of-1 order light component (I) from the image obtained in FIG. 5 by image processing-1) And +1 order light component (I)+1) And S obtained by performing difference calculation3The imaged image of (1).
Detailed Description
< polarization camera device >
The present application provides a polarization imaging device provided with an anisotropic diffraction grating.
"polarization," which is a property of an electromagnetic wave in which the trajectory of an electric field vector is shifted, is widely used as one of characteristics of an electromagnetic wave. When an electromagnetic wave interacts with a substance (reflection, scattering, absorption, etc.), the polarization state of the electromagnetic wave changes, and the change in polarization includes various information unique to the substance. That is, by measuring the polarization characteristics of the object, information specific to the substance can be investigated in a non-contact and non-destructive manner. The polarization imaging apparatus of the present application can perform imaging measurement of the spatial distribution of stokes parameters (parameters describing the polarization state) of scattered light from an object by using a snapshot.
The polarization imaging device of the application comprises: an anisotropic diffraction grating element, a lens element, and a light receiving element, in which optical anisotropy is periodically modulated.
It is preferable that the lens element, the anisotropic diffraction grating element, and the light receiving element are arranged in this order from the object side. Other elements than the above-described elements may be arranged as necessary.
< Anisotropic diffraction grating element >
The polarization imaging apparatus of the present application includes an anisotropic diffraction grating element in which optical anisotropy is periodically modulated. The principle of stokes parameter measurement using the anisotropic diffraction grating element will be described below.
The polarization state of electromagnetic wave can be represented by a Stokes vector (S) consisting of 4 elements0，S1，S2，S3) And (4) showing.
Here, S0Indicates the total light intensity, S1Represents the difference S between the 0deg linearly polarized light component and the 90deg linearly polarized light component2Shows the difference S between the 45deg linear polarized light component and the-45 deg linear polarized light component3The difference between the right-handed circularly polarized light component and the left-handed circularly polarized light component is expressed and called the stokes parameter.
When the amplitude ratio angle and the phase difference between the 0deg linear polarized light component and the 90deg linear polarized light component are assumed to be Ψ and Δ, respectively, each stokes parameter is defined by the following formula (1).
Figure BDA0002461194880000111
These 4 elements are obtained from the intensity information of the light reflected, scattered, and transmitted from the object, and the polarization characteristics of the object can be clarified.
The polarization imaging apparatus of the present application is characterized in that these stokes parameters can be measured by imaging with 1 image acquisition. The principle of polarization detection of the present device is based on an anisotropic diffraction grating element that periodically modulates the optical anisotropy.
Before the description of the configuration of the device and the like, the diffraction characteristics of the anisotropic diffraction grating produced by polarization hologram recording will be described.
In general, in a recording material having polarization sensitivity, the orientation of optical anisotropy and the magnitude of birefringence are recorded in accordance with the polarization orientation and the ellipticity of polarized light with which polarized light is irradiated. Now, it is considered that 2 pieces of 0deg linearly polarized light (i.e., p-polarized light) having mutually equal amplitudes are interfered with each other by giving a certain intersection angle, and the formed photoelectric field is irradiated to the polarization recording material (in the present application, unless otherwise specified, this case is referred to as PL interference (parallel line polarization interference)). In this case, assuming that the magnitude of the induced anisotropy is proportional to the light intensity, the Jones matrix representing the distribution of the induced anisotropy is represented by the following formula (2). Here, Δ γ is ═ pi Δ nd/λ, Δ n is the maximum value of polarization-induced birefringence, d is the film thickness of the recording material, and λ is the wavelength of diffracted light.
Figure BDA0002461194880000121
Here, when the equation (2) is expanded in the fourier series, the Jones matrix component contributing to the ± 1 st diffraction order is expressed by the following equation (3). Here, when the Jones vector of the incident light is defined as the following formula (4), I represented by the following formula (5) is obtained using the following formulas (3) and (4)PL ±The intensity of the diffracted light of + -1 order.
Therefore, it is known that the intensity of diffracted light of the anisotropic grating formed by PL recording highly depends on the amplitude ratio angle Ψ of incident light. Hereinafter, this grating will be referred to as PL grating unless otherwise specified in this application.
Figure BDA0002461194880000122
Figure BDA0002461194880000123
Figure BDA0002461194880000124
Next, it is considered that circularly polarized light of opposite rotation having equal amplitudes is irradiated to a polarization recording material by interference (in the present application, unless otherwise specified, this case is referred to as OC interference (Orthogonal circular polarization C interference)). In the case of OC interference, the Jones matrix of the anisotropy distribution formed by recording can be represented by the following formula (6).
Further, the following formula (7) can be obtained by developing the formula (6), and when the intensity of diffracted light with respect to incident polarized light given by the formula (4) is obtained from the formula (7) in the same manner as in the case of PL recording, T shown by the following formula (8) is obtainedOC ±。
Therefore, it is known that the diffraction light intensity of an anisotropic grating formed by OC recording by OC interference depends on the phase difference of incident light. Hereinafter, for simplicity, this grating will be referred to as an OC grating.
Figure BDA0002461194880000131
Figure BDA0002461194880000132
Figure BDA0002461194880000133
As described above, the anisotropic diffraction grating formed in the polarization recording material by polarization hologram recording exhibits diffraction characteristics depending on the incident polarization state. Therefore, polarization information of incident light can be spatially separated in the form of intensity information. Therefore, the value of the stokes parameter can be derived from the intensity information of each diffracted order light. As an example, a stokes parameter detecting element in which 4 anisotropic diffraction gratings having different lattice vectors are overlapped (overlapped) will be schematically described.
Fig. 1 shows a schematic diagram of a diffraction grating.
The anisotropic diffraction grating has 4 gratings A, B, C, D multiply recorded in the polarization recording material. Wherein A, B, C is PL grating, D is OC grating, and their respective lattice vectors are mutually differentArranged at an angle of 45 degrees. Here, assuming that each grating is independently formed in the recording material, the intensity of diffracted light of ± 1 order observed on the screen in the case of vertically incident polarized light to the film is defined as Im+And Im-. In addition, m ═ a, B, C, D, IA+Indicating the intensity of the +1 order light with respect to grating a.
Here, as is clear from the above formula (5), I corresponding to PL gratingA±、IB±、IC±Sinusoidally varying depending on the amplitude ratio angle Ψ of the incident light. In addition, according to the m-equation (5), in the case of the PL grating, the ± 1 st order diffracted lights are equal in intensity and do not depend on the polarization state of the incident light, and therefore IA+＝IA-＝IA、IB+＝IB-＝IB、IC+＝IC-＝ICThis is true.
On the other hand, according to equation (8), I corresponds to OC gratingD±Depending on the phase difference Δ of the incident light.
As above, with respect to S among Stokes parameters0、S1、S3The following formula (9) is obtained from the formula (1). Here, aPLAnd aOCIs a proportionality constant.
On the other hand, the following expressions (10) and (11) are obtained from the expression (1).
Figure BDA0002461194880000141
Figure BDA0002461194880000142
Figure BDA0002461194880000143
I.e. can be represented by S1The absolute value of the amplitude ratio angle Ψ can be obtained from S3The phase difference Δ is obtained.
Here, based on the diffraction characteristics of the PL grating, IA±、IB±、IC±The dependence of the amplitude ratio angle Ψ for the incident polarized light is shown in fig. 2.
As can be seen from FIG. 2, in IB＞(IA+IC) At/2, the amplitude ratio angle is psi < 0, at IB＜(IA+IC) At/2, the amplitude ratio angle is psi > 0.
I.e. can be formed fromBThe sign of the amplitude ratio angle Ψ is determined. Further, the obtained amplitude ratio angle Ψ and phase difference Δ are substituted into the above equation (1), thereby obtaining S2. Therefore, the diffracted light I from the anisotropic diffraction grating of FIG. 1 can be usedA、IB、IC、ID±All elements of the stokes parameters of the incident light are determined. It should be noted that, if intensity information necessary for deriving the stokes parameter is obtained, the stokes parameter can be measured even in an anisotropic pattern different from the anisotropic diffraction grating of fig. 1.
Preferably, the anisotropic diffraction grating element has an anisotropic diffraction grating having a plurality of lattice vectors with different directions from each other, and at least the anisotropic orientation or birefringence of the lattice vectors is periodically modulated.
Further, it is preferable that the anisotropic diffraction grating element has: an anisotropic diffraction grating that spatially separates and converts information of Stokes parameters of incident light into intensity information according to the distribution of anisotropic orientation and birefringence. Further, it is preferable that the anisotropic diffraction grating element has an anisotropic diffraction grating having a good diffraction efficiency of light of ± 1 st order. The ideal phase difference with the best diffraction efficiency for the PL grating and the OC grating is obtained from the above equations (5) and (8).
Specifically, in the case of the OC grating, it is preferable that the diffraction efficiency be 5% or more, that is, the phase difference (δ ═ 2 π Δ nd/λ) be in the range of 0.448+2 π m to 5.82+2 π m (m: natural number), preferably 50% or more, that is, the phase difference (δ ═ 2 π Δ nd/λ) be in the range of 1.57+2 π m to 4.71+2 π m (m: natural number), and that the diffraction efficiency be 100%, that is, the phase difference (δ ═ 2 π Δ nd/λ) be 3.14+2 π m (m: natural number).
In the case of a PL grating, the diffraction efficiency, i.e., the phase difference (δ ═ 2 π Δ nd/λ), is preferably in the range of 0.916 to 6.58, 9.70 to 12.4, 15.8 to 18.3, and 22.8 to 24.0, the diffraction efficiency, i.e., the phase difference (δ ═ 2 π Δ nd/λ), of 15% or more, preferably in the range of 1.69 to 5.72, and the diffraction efficiency, i.e., the phase difference (δ ═ 2 π Δ nd/λ), of 33.8%, is preferably 3.68.
The anisotropic diffraction grating element can be prepared as follows.
That is, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating having a photoreactive polymer film having photoreactive side chains that undergo at least 1 reaction selected from the group consisting of (a-1) photocrosslinking and (a-2) photoisomerization.
Further, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating formed of a photoreactive polymer film. In this case, it is necessary to improve the diffraction efficiency of the ± 1 st order light obtained from the diffraction pattern formed in the photoreactive polymer film, and therefore, the photoreactive polymer used in the photoreactive polymer film is preferably a polymer capable of inducing a large phase difference, specifically, a phase difference in the above range by interference exposure with a desired polarized light.
It is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating having:
I) a first transparent substrate layer; and
II) a first photoreactive polymer membrane having a first photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
Further, it is preferable that the anisotropic diffraction grating element includes an anisotropic diffraction grating having:
III) a second transparent substrate layer; and
IV) a second photoreactive polymer membrane having a second photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization,
the II) first photoreactive polymer film and the IV) second photoreactive polymer film are disposed to face each other, and (B) a low molecular liquid crystal layer is disposed between the II) first film and the IV) second film.
First and second transparent substrate layers
The first transparent base layer and the second transparent base layer are formed of transparent bases.
As the transparent substrate, depending on the characteristics used as a polarization imaging device, for example, glass; acrylic, polycarbonate, and other plastics. For example, it is preferable that the transparent substrate has a property of transmitting polarized ultraviolet rays.
< (B) Low molecular liquid Crystal layer
Here, as the low molecular liquid crystal contained in the low molecular liquid crystal layer B), nematic liquid crystal, ferroelectric liquid crystal, or the like which has been conventionally used for liquid crystal display elements and the like can be used.
Specific examples of the low molecular liquid crystal include cyanobiphenyls such as 4-cyano-4 '-n-pentylbiphenyl and 4-cyano-4' -n-heptyloxybiphenyl; cholesterol esters such as cholesterol acetate and cholesterol benzoate; carbonates such as 4-carboxyphenylethyl carbonate and 4-carboxyphenyl n-butyl carbonate; phenyl esters such as phenyl benzoate and biphenyl phthalate; schiff bases such as benzylidene-2-naphthylamine and 4' -n-butoxybenzylidene-4-acetanilide; benzidines such as N, N' -dibenzylidenedianiline and p-dianisilbenzidine; azoxybenzenes such as 4,4 '-azoxyanisole and 4, 4' -di-n-butoxyazoxybenzene; liquid crystals of phenylcyclohexyl, terphenyl, phenyldicyclohexyl and the like, which are specifically shown below; and the like, but are not limited thereto.
Figure BDA0002461194880000161
Figure BDA0002461194880000171
It is preferable to use an anisotropic diffraction grating in which information on the stokes parameter of light incident on the polymer thin film is spatially separated from the distribution of the anisotropic azimuth and birefringence formed in the polymer thin film by subjecting the photoreactive polymer film to interference exposure with light of a desired polarization to form an arbitrary diffraction pattern, and converted into intensity information.
[ photoreactive Polymer film ]
Preferably, the photoreactive polymer film is formed by having a photoreactive polymer having a photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
In the present specification, photoreactivity means that either reaction of (A-1) photocrosslinking or (A-2) photoisomerization or a property of both reactions occurs.
It is preferable that the photoreactive polymer has a side chain that undergoes the photocrosslinking reaction (A-1).
As for the photoreactive polymer, i) is a polymer exhibiting liquid crystallinity in a predetermined temperature range and having a photoreactive side chain.
The photoreactive polymer is preferably ii) reacted with light having a wavelength of 250 to 450nm and exhibits liquid crystallinity at a temperature of 50 to 300 ℃.
Regarding the photoreactive polymer, iii) preferably has a photoreactive side chain that reacts to light in a wavelength range of 250nm to 450nm, particularly polarized ultraviolet light.
As for the photoreactive polymer, it is preferable that iv) has a mesogen group in order to exhibit liquid crystallinity at a temperature range of 50 to 300 ℃.
The photoreactive polymer has a photoreactive side chain having photoreactivity as described above. The structure of the side chain is not particularly limited, and the side chain preferably has a structure in which the reaction represented by the above (A-1) and/or (A-2) occurs, and preferably has a structure in which the photocrosslinking reaction of (A-1) occurs. The structure in which the (A-1) photocrosslinking reaction occurs is preferable in the following respects: even if the structure after the reaction is exposed to external stress such as heat, the orientation of the photoreactive polymer can be stably maintained for a long period of time.
When the side chain structure of the photoreactive polymer has a rigid mesogen component, the orientation of the liquid crystal is stable, which is preferable.
Examples of the mesogen component include biphenyl, terphenyl, phenylcyclohexyl, phenylbenzoate, and azophenyl, but are not limited thereto.
Examples of the structure of the main chain of the photoreactive polymer include at least 1 selected from the group consisting of a radical polymerizable group such as hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate, α -methylene- γ -butyrolactone, styrene, vinyl, maleimide, norbornene, and siloxane, but are not limited thereto.
The side chain of the photoreactive polymer is preferably a side chain containing at least 1 of the following formulas (1) to (6).
Figure BDA0002461194880000191
Wherein A, B, D each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
s is C1-C12 alkylene, and hydrogen atoms bonded on the S are optionally substituted by halogen groups;
t is a single bond or C1-12 alkylene, and hydrogen atoms bonded on the T are optionally substituted by halogen groups;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0(in the formula, R0Represents a hydrogen atomAlkyl group having 1 to 5 carbon atoms), -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
Y2is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y1The same definition;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
cou represents coumarin-6-yl or coumarin-7-yl, the hydrogen atoms bonded to which are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
one of q1 and q2 is 1 and the other is 0;
q3 is 0 or 1;
p and Q are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-8 alicyclic hydrocarbon, and combinations thereof; wherein, in the case where X is-CH-CO-O-, -O-CO-CH-and P or Q on the side to which-CH-is bonded is an aromatic ring, when the number of P is 2 or more, P is optionally the same as or different from each other, and when the number of Q is 2 or more, Q is optionally the same as or different from each other;
l1 is 0 or 1;
l2 is an integer of 0 to 2;
when l1 and l2 are both 0, A represents a single bond when T is a single bond;
when l1 is 1, B represents a single bond when T is a single bond;
h and I are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, and combinations thereof.
It is preferable that the side chain is any 1 kind of photoreactive side chain selected from the group consisting of the following formulas (7) to (10).
In the formula, A, B, D, Y1、X、Y2And R has the same definition as above;
l represents an integer of 1 to 12;
m represents an integer of 0 to 2, m1 and m2 represent an integer of 1 to 3;
n represents an integer of 0 to 12 (wherein, when n is 0, B is a single bond).
Figure BDA0002461194880000211
It is preferable that the side chain is any 1 kind of photoreactive side chain selected from the group consisting of the following formulas (11) to (13).
Wherein A, X, l, m1 and R have the same meanings as defined above.
Figure BDA0002461194880000212
The side chain is preferably a photoreactive side chain represented by the following formula (14) or (15).
In the formula, A, Y1L, m1 and m2 have the same meanings as defined above.
Figure BDA0002461194880000213
The side chain is preferably a photoreactive side chain represented by the following formula (16) or (17).
Wherein A, X, l and m have the same meanings as defined above.
Figure BDA0002461194880000221
The side chain is preferably a photoreactive side chain represented by the following formula (18) or (19).
(in the formula, A, B, Y1、R1Have the same definitions as above.
One of q1 and q2 is 1 and the other is 0;
l represents an integer of 1 to 12, m1 and m2 represent an integer of 1 to 3;
Figure BDA0002461194880000222
the side chain is preferably a photoreactive side chain represented by the following formula (20).
In the formula, A, Y1X, l and m have the same definitions as above.
Figure BDA0002461194880000223
The photoreactive polymer film may be formed of a polymer having any 1 liquid crystalline side chain selected from the group consisting of the following formulas (21) to (31). For example, in the case where the photoreactive side chain of the polymer forming the photoreactive polymer film does not have liquid crystallinity, or in the case where the main chain of the polymer forming the photoreactive polymer film does not have liquid crystallinity, it is preferable that the component forming the photoreactive polymer film has any 1 liquid crystalline side chain selected from the group consisting of the following formulas (21) to (31).
Wherein A, B, q1 and q2 have the same meanings as defined above;
Y3is a group selected from the group consisting of 1-valent benzene ring, naphthalene ring, biphenyl ring, furan ring, nitrogen-containing heterocycle, C5-C8 alicyclic hydrocarbon, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2CN, -a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
R3represents a hydrogen atom, -NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a nitrogen-containing heterocycle, a C5-8 alicyclic hydrocarbon, and a CAn alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms;
l represents an integer of 1 to 12, m represents an integer of 0 to 2, wherein in formulas (23) to (24), the total of all m is 2 or more, in formulas (25) to (26), the total of all m is 1 or more, and m1, m2, and m3 each independently represents an integer of 1 to 3;
R2represents a hydrogen atom, -NO2CN, -a halogen group, a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a nitrogen-containing heterocycle, an alicyclic hydrocarbon with 5-8 carbon atoms, an alkyl group or an alkoxy group;
Z1、Z2represents a single bond, -CO-, -CH2O-、-CH＝N-、-CF2-。
Figure BDA0002461194880000241
Method for preparing photoreactive polymer film
The photoreactive polymer film described above can be obtained as follows: the liquid crystal polymer is obtained by polymerizing a photoreactive side chain monomer having the photoreactive side chain and, if necessary, copolymerizing the photoreactive side chain monomer with a monomer having the liquid crystal side chain. For example, the optical fiber can be manufactured by referring to [0062] to [0090] of WO2017/061536 (the entire contents of the publication are incorporated by reference into the present application).
< lens element >
The polarization imaging device of the present invention has a lens element. The lens element is not particularly limited as long as it has an imaging function of a light receiving element described later.
< light receiving element >
The polarization imaging device of the present invention has a light receiving element. The light receiving element is only required to obtain the S from the data obtained by imaging0～S3There is no particular limitation.
The polarization imaging apparatus of the present invention will be described with reference to the drawings.
Fig. 3 is a diagram illustrating an outline of the polarization imaging apparatus of the present invention.
The polarization imaging device of the present invention includes an imaging lens, a color filter, an anisotropic diffraction grating, and a light receiving element array.
The arrangement distance between the imaging lens and the light receiving element array is made variable so as to enable focus adjustment.
Since the diffraction angle of the anisotropic diffraction grating is accompanied by wavelength dependence, there is a problem that an image is blurred due to angular dispersion with respect to white light. Therefore, the influence of dispersion is reduced by inserting a color filter. An anisotropic diffraction grating having an optimized retardation according to an observation wavelength is used in combination with an interference filter of a corresponding frequency band.
By introducing an imaging unit (imaging lens, light receiving element array), imaging measurement can be performed without being limited to spot measurement.
In general, for the determination of the stokes parameter, fourier analysis methods such as a method of measuring the light intensities of 0deg linearly polarized light component, 90deg linearly polarized light component, 45deg linearly polarized light component, -45deg linearly polarized light component, right circularly polarized light component, and left circularly polarized light component in the formula (1) and a rotary phase shifter method are used. However, these methods require measurement many times in principle, and are therefore not suitable for measurement of an object whose state changes with time.
In contrast, the polarization imaging apparatus according to the present invention can perform polarization imaging measurement using a snapshot by spatially separating information necessary for measurement of the stokes parameters and acquiring the information at once in the form of intensity information. That is, the present invention is characterized in that even a dynamic object to be measured can be measured. In addition, there is also a feature that an expensive optical element is not required including a diffraction grating, and thus it is inexpensive.
The polarization imaging apparatus of the present invention can be applied to various fields because it can perform two-dimensional measurement of a dynamic measurement object or a static measurement object. Examples of the vehicle include, but are not limited to, the medical field, the automotive autonomous driving technology field, and the safety field.
The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
Examples
< production of Anisotropic diffraction Grating >
As a recording material, photo-crosslinkable polymer liquid crystals (4- (4-methoxycinnamoyloxy) biphenyl side groups; 4- (4-methoxycinnamoyloxy) biphenyl side groups (P6CB)) represented by the following formula were used.
P6CB was dissolved in methylene chloride and spin-coated on a glass substrate to a film thickness of 300 nm.
2 glass substrates coated with P6CB film were prepared, and the P6CB film sides were relatively stuck together, thereby producing an empty cell. For the fabricated void cell, UV laser having a wavelength of 325nm emitted from a He-Cd laser was allowed to perform OC interference while being irradiated at a wavelength of 600mJ/cm2Exposure energy of (1). After the irradiation, the cell was heat-treated in an oven at 150 ℃ for 15 minutes, and then a low molecular liquid crystal 5CB (4-cyano-4 '-pentylbiphenyl; 4-cyano-4' -pentyllbiphenyl) was injected into the cell to prepare a cell-type OC grating. The diameter of the produced anisotropic diffraction grating was 8 mm.
Figure BDA0002461194880000261
< manufacture of polarization imaging device >
A polarization imaging apparatus was produced from the schematic diagram of the polarization imaging apparatus shown in fig. 3.
Specifically, as shown in fig. 4, the polarization imaging device is arranged so that an imaging lens, an interference filter (FL 532-3 (center wavelength 532nm) manufactured by throllabs, the obtained anisotropic diffraction grating, and a light receiving element are arranged in this order from the object to be imaged, and a commercially available camera (ILCE 6000S manufactured by SONY) is used as the light receiving element, and the imaging lens, the interference filter, and the anisotropic diffraction grating are packaged in a measurement system and can be mounted on the commercially available camera.
< measurement of imaging >
In this example, imaging measurement was performed using a blackish-greenish chafer, which exhibits selective reflection characteristics with respect to circularly polarized light, as a subject. The image is shown in fig. 5.
As can be seen from fig. 5, 3 image points are obtained. The optical components of-1 order, 0 order and +1 order correspond to the OC grating in order from the left. Wherein the-1 st order light and the +1 st order light components represent two-dimensional distributions of left-handed circularly polarized light components and right-handed circularly polarized light components.
Extraction of-1 order light component (I) by image processing-1) And +1 order light component (I)+1) Based on the following expression, the difference calculation is carried out, and the obtained S3The imaged image of (a) is shown in fig. 6.
S3＝(I+1-I-1)/(I+1+I-1)
As can be seen from FIG. 6, S along the appearance of the Mouremys mutica was obtained3The spatial distribution of (a). From the image, it is understood that the light reflected and scattered by the blackish green scarab mainly includes left-handed circularly polarized light. This is consistent with the selective reflection characteristics of the circularly polarized light of the well-known blackish green scarab.
Therefore, it is actually verified that the polarization camera device of the present invention can perform imaging measurement on the spatial distribution of stokes parameters by using snapshots.

Claims (15)

1. A polarization imaging apparatus includes: an anisotropic diffraction grating element, a lens element, and a light receiving element, in which optical anisotropy is periodically modulated.
2. The apparatus according to claim 1, wherein the anisotropic diffraction grating element has an anisotropic diffraction grating provided with a plurality of lattice vectors different in direction from each other, at least anisotropic orientation or birefringence of the lattice vectors being periodically modulated.
3. The apparatus of claim 1 or claim 2, wherein the anisotropic diffraction grating element has: an anisotropic diffraction grating that spatially separates and converts information of Stokes parameters of incident light into intensity information according to the distribution of anisotropic azimuth and birefringence.
4. The apparatus of any of claims 1-3, wherein the anisotropic diffraction grating element comprises an anisotropic diffraction grating having a photoreactive polymer film with photoreactive side chains that undergo at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
5. The apparatus of any one of claims 1-4, wherein the anisotropic diffraction grating element comprises an anisotropic diffraction grating formed from the photoreactive polymer film.
6. The apparatus of any of claims 1-5, wherein the anisotropic diffraction grating element comprises an anisotropic diffraction grating having:
I) a first transparent substrate layer; and
II) a first photoreactive polymer membrane having a first photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization.
7. The apparatus of any of claims 1-4 and 6, wherein the anisotropic diffraction grating element comprises an anisotropic diffraction grating having:
III) a second transparent substrate layer; and
IV) a second photoreactive polymer membrane having a second photoreactive side chain that undergoes at least 1 reaction selected from the group consisting of (A-1) photocrosslinking and (A-2) photoisomerization,
the II) first photoreactive polymer film and the IV) second photoreactive polymer film are disposed to face each other, and (B) a low molecular liquid crystal layer is disposed between the II) first film and the IV) second film.
8. The apparatus according to any one of claims 4 to 7, wherein an anisotropic diffraction grating is used which forms an arbitrary diffraction pattern on the polymer thin film by subjecting the photoreactive polymer film to interference exposure with light of a desired polarization, thereby spatially separating information of Stokes parameters of light incident on the polymer thin film according to the distribution of anisotropy orientation and birefringence formed in the polymer thin film and converting the information into intensity information.
9. The apparatus according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having any 1 type of photoreactive side chain selected from the group consisting of the following formulas (1) to (6),
wherein A, B, D each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
s is C1-C12 alkylene, and hydrogen atoms bonded on the S are optionally substituted by halogen groups;
t is a single bond or C1-12 alkylene, and hydrogen atoms bonded on the T are optionally substituted by halogen groups;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are independently optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, wherein R is0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
Y2is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y1The same definition;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
cou represents coumarin-6-yl or coumarin-7-yl, the hydrogen atoms bonded to which are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
one of q1 and q2 is 1 and the other is 0;
q3 is 0 or 1;
p and Q are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-8 alicyclic hydrocarbon, and combinations thereof; wherein, in the case where X is-CH-CO-O-, -O-CO-CH-and P or Q on the side to which-CH-is bonded is an aromatic ring, when the number of P is 2 or more, P is optionally the same as or different from each other, and when the number of Q is 2 or more, Q is optionally the same as or different from each other;
l1 is 0 or 1;
l2 is an integer of 0 to 2;
when l1 and l2 are both 0, A represents a single bond when T is a single bond;
when l1 is 1, B represents a single bond when T is a single bond;
h and I are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, and combinations thereof,
Figure FDA0002461194870000041
10. the apparatus according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having any 1 type of photoreactive side chain selected from the group consisting of the following formulas (7) to (10),
wherein A, B, D each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are independently optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, wherein R is0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12;
m represents an integer of 0 to 2, m1 and m2 represent an integer of 1 to 3;
n represents an integer of 0 to 12, wherein, when n is 0, B is a single bond;
Y2is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO2、-CN、-CH＝C(CN)2-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;
r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y1The same definition is given to the same,
Figure FDA0002461194870000051
11. the apparatus according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having any 1 type of photoreactive side chain selected from the group consisting of the following formulas (11) to (13),
wherein A each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 represents an integer of 1 to 3;
r represents a ring selected from among 1-valent benzene rings, naphthalene rings, biphenyl rings, furan rings, pyrrole rings and C5-8 alicyclic hydrocarbons, or a group in which 2 to 6 identical or different rings selected from among these substituents are bonded via a linking group B, and hydrogen atoms bonded to each of these are independently optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2A halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, or R represents a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms, wherein R represents a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
Figure FDA0002461194870000061
12. the device according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having a photoreactive side chain represented by the following formula (14) or (15),
wherein A each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from 1-valent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring and C5-8 alicyclic hydrocarbon, or a phase selected from these substituentsGroups of 2 to 6 rings, which are identical or different, bonded via a linking group B, the hydrogen atoms bonded to them each independently being optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, wherein R is0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
l represents an integer of 1 to 12, m1 and m2 represent an integer of 1 to 3,
Figure FDA0002461194870000062
13. the apparatus according to any one of claims 4 to 8, wherein the photoreactive polymer film comprises a photoreactive polymer having a photoreactive side chain represented by the following formula (16) or (17),
wherein A represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, m represents an integer of 0 to 2,
Figure FDA0002461194870000071
14. the device according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having any 1 kind of photosensitive side chain selected from the group consisting of the following formulas (18) or (19),
wherein A, B each independently represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a benzene ring, a naphthalene ring, a biphenyl ring, furan selected from 1-valent benzene rings, naphthalene rings, biphenyl ringsA ring of a C5-8 alicyclic hydrocarbon, a pyrrole ring or 2-6 rings selected from these substituents, which may be the same or different, bonded via a linking group B, and hydrogen atoms bonded to these groups are each independently optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, wherein R is0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
one of q1 and q2 is 1 and the other is 0;
l represents an integer of 1 to 12, m1 and m2 represent an integer of 1 to 3;
R1represents a hydrogen atom, -NO2、-CN、-CH＝C(CN)2a-CH-CN group, a halogen group, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms,
Figure FDA0002461194870000081
15. the device according to any one of claims 4 to 8, wherein the photoreactive polymer film has a photoreactive polymer having a photoreactive side chain represented by the following formula (20),
wherein A represents a single bond, -O-, -CH2-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;
Y1represents a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR0、-NO2、-CN、-CH＝C(CN)2a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, wherein R is0Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;
l represents an integer of 1 to 12, m represents an integer of 0 to 2,
Figure FDA0002461194870000082
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