JPH10239519A - Phase difference plate, and polarizing element using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate almost uniform phase difference corresponding to all wavelength in visual light area, by laminating films or sheets specified in the relation of the wavelength dispersion value of a double refractive index and in the relation of phase difference, in the mutually orthogonal direction of lag axes, and specifying the wavelength dispersion value. SOLUTION: In the phase difference plate formed by laminating films or sheets formed of A- and B-polymers which are Α<Β in the relation of the wavelength dispersion value α[α=Δn(450nm)/Δn(650nm)] of a double refractive index Δn, the relation of phase difference R of the respective polymers is RA>RB, the films or sheets are laminated in the orthogonal directions of lag axes of the respective polymers, and the wavelength dispersion value α is made smaller than 1. The A-polymer is selected from a group formed of polypropylene, polymethyl methacrylate, an ethylene-vinyl alcohol copolymer, amorphous polyolefine, and the like, and the B-polymer is selected from the group formed of polystyrene, polyarylate, polycarbonate, polysulfone, polyethersulfone, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element, a polarizing element, an optical analyzer, an optical measuring apparatus, an optical experiment, and the like, for producing linearly polarized light, circularly polarized light, and elliptically polarized light in a uniform wavelength range in the visible light wavelength region. The present invention relates to a retardation plate that is advantageous as a broadband wave plate that generates a phase difference.

[0002]

2. Description of the Related Art A retardation plate is obtained by stretching a thin plate made of an inorganic material such as calcite, mica, and quartz or a polymer film having a high intrinsic birefringence. Converting linearly polarized light to circularly polarized light 1
There are a 波長 wavelength plate (hereinafter abbreviated as a λλ plate) and a 波長 wavelength plate (hereinafter abbreviated as a 板 λ plate) that converts a polarization oscillation plane of linearly polarized light by 90 °.

[0003] In the case of monochromatic light, these retardation plates are adjusted to a phase difference of 1 / 4λ or 1 / 2λ of the light wavelength.
In the case of white light, which is a composite wave in which light rays in the visible light region are mixed, the distribution of the polarization state at each wavelength occurs due to the wavelength dispersion of the phase difference of the material constituting the phase difference plate, and the light is converted into colored polarized light. Is done. Further, in the case of a wavelength plate, it is necessary to prepare a retardation plate adjusted according to the wavelength to be applied from the wavelength dispersibility of the material, so that a wavelength plate for each wavelength is required. That is, in the conventional retardation plate, there are problems that the cost is increased because a wavelength plate is prepared for each light beam wavelength to be used, and that application to white light is unsuitable.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a retardation plate having a wavelength dispersibility such that an optical retardation at all wavelengths of visible light generates a uniform retardation regardless of the wavelength. It is to provide.

[0005]

In order to achieve the above object, the retardation plate of the present invention has a wavelength dispersion value α (α = Δn (450 nm) / Δn) of the birefringence index Δn.
(650 nm)), in a retardation plate in which films or sheets made of A and B polymers having a relationship of α _A <α _B are laminated, the relationship of the retardation R of each polymer is R _A > R _B , and each polymer is Are stacked in a direction in which the slow axis is perpendicular to the axis, and the chromatic dispersion value α is smaller than 1.

Further, a film or a sheet made of each polymer is laminated via an adhesive layer having an in-plane retardation of 5 nm or less.

[0007] A film or sheet made of each polymer is laminated via an adhesive layer having at least one kind of liquid crystal composition.

Further, the wavelength dispersion value α (α = α) of the birefringence index Δn
Δn (450 nm) / Δn (650 nm)) is α
In _A <alpha consisting in which A and B polymer _B film or the retardation plate obtained by laminating a sheet, A polymer polypropylene, polymethyl methacrylate, ethylene - vinyl alcohol copolymer, amorphous polyolefin,
It is characterized by being at least one selected from the group consisting of triacetate, diacetate and polyvinyl alcohol.

Further, the wavelength dispersion value α of the birefringence index Δn (α =
Δn (450 nm) / Δn (650 nm)) is α
_In a retardation plate obtained by laminating films or sheets comprising A and B polymers in which _A <α _B , the B polymer is composed of polystyrene, polyarylate, polycarbonate, polysulfone, polyethersulfone, polyetherimide,
It is characterized in that it is at least one selected from the group consisting of polyimide and polyvinylidene fluoride.

Further, characterized in that the phase difference R is _{(R A -R B) = 1} / 4λ plate which is adjusted to lambda / 4.

Further, the present invention is characterized in that the phase difference R is a half λ plate adjusted to (R _A -R _B ) = λ / 2.

Also, a part that divides a part of the unpolarized light into two polarized lights whose polarization planes are orthogonal to each other, and that one of the two polarized lights is changed to match the polarization plane of the polarized light whose polarization plane is not changed. In a polarizing element having a modulating section to be used, it is preferable to use the retardation plate of the present invention as the modulating section.

A unit for converting non-polarized light into polarized light is
A sheet-shaped polarizing element that is continuously processed, wherein the unit changes a part of the unpolarized light into reflected light and transmitted light whose polarization planes are orthogonal to each other, and changes a polarization plane of the reflected light. In a sheet-like polarizing element having a modulation section that is made to coincide with the polarization plane of transmitted light, the retardation plate of the present invention may be used as the modulation section.

[0014] Further, a cube-type polarizing beam splitter and a light exiting surface on the reflected light side of the polarizing beam splitter are provided on the surface.
A 偏光 wavelength plate is used as a 反射 wavelength plate in a light reflecting plate bonded and bonded so as to sandwich a 波長 wavelength plate and at least two or more right angle prisms bonded together with the reflecting plate and the polarizing beam splitter therebetween. It is preferable to use the phase difference plate of the present invention.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When linearly polarized white light is incident on the retardation plate of the present invention, a wavelength dispersion value α (α =
Δn (450 nm) / Δn (650 nm)) is α
_A <α _{B The} film or sheet composed of the polymers A and B is laminated so that the slow axes are perpendicular to each other, so that the optical retardation caused by the material having the characteristic of α _A having small wavelength dispersion is obtained. Is canceled by the phase difference caused by the material having the property of α _B having large wavelength dispersion. At this time, since the phase difference is canceled by the material having the characteristic of α _B having large wavelength dispersion, the phase difference generated at a shorter wavelength has a larger amount of canceled phase difference.

Further, since the relation of the retardation of the film or sheet made of each polymer is RA> RB, the outputted retardation is outputted as polarized light having a smaller phase difference as the wavelength becomes shorter. In other words, the retardation plate of the present invention produces a smaller phase difference as the wavelength of the incident light is shorter, and produces a larger phase difference as the wavelength of the incident light is longer. Therefore, the wavelength dispersion characteristic of the retardation plate according to the present invention tends to monotonously increase as the wavelength becomes longer, and the wavelength dispersion characteristic is such that the optical phase difference at all wavelengths of visible light becomes uniform regardless of the wavelength. Since the retardation plate of the present invention has the same, the polarized light incident as white light also has a uniform phase difference in the visible light region and can be obtained as white polarized light.

[0017]

Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples. The optical properties of the retardation plate of the present invention were measured by the following methods. (1) Phase difference and slow axis The optical phase difference and the slow axis at a wavelength of 550 nm were measured using a polarizing microscope BH2 manufactured by Olympus Optical Co., Ltd. and a Berek compensator. (2) Wavelength dispersion value 400 nm using RETS-6000 manufactured by Otsuka Electronics Co., Ltd.
The optical phase difference in the wavelength range from to 780 nm was measured.

(Example) A polyethylene-vinyl alcohol copolymer (EF-F manufactured by Kuraray Co., Ltd .; hereinafter abbreviated as EVOH) was uniaxially stretched at 180 ° C. at an atmosphere temperature not lower than the thermal deformation temperature, and 550 nm for a light beam of 550 nm. The phase difference was adjusted to In the stretched EVOH film, the slow axis coincided with the stretching direction, and the wavelength dispersion value α was 1.004.

Polyether sulfone (manufactured by Sumitomo Heclite Co.)
FS-1300 (hereinafter abbreviated as PES) was uniaxially stretched at 240 ° C. at an atmosphere temperature equal to or higher than the glass transition point, and adjusted to a 275 nm phase difference with respect to a 550 nm light beam. In the stretched PES film, the slow axis coincides with the stretching direction, and the wavelength dispersion value α is 1.
230.

A retardation plate was prepared by laminating the stretched EVOH film and the PES film with their slow axes perpendicular to each other. The retardation of the laminated retardation plate is 550n
m is 275 nm, and the chromatic dispersion value is 0.8.
09.

As a result of measuring the optical phase difference in the wavelength range of 400 nm to 780 nm, the EVOH / P according to the present invention was measured.
The optical function of the λλ plate manufactured from the ES laminated type retardation plate had a phase difference shift of 10% or less in a wavelength range of 450 nm to 650 nm, and showed a good λλ function.

The phase difference plate of the present invention is inserted between the polarizer and the analyzer, and the transmitted light intensity when the polarizer and the analyzer are arranged in parallel Nicols and the polarizer and the analyzer are arranged in crossed Nicols. By measuring the transmission high intensity in the case of the above, the polarization conversion function of the retardation plate manufactured so as to be adjusted to 波長 wavelength according to the present invention was measured in a wavelength range of 400 nm to 780 nm. The efficiency with which the plane of polarization of linearly polarized light is converted into linearly polarized light that has been converted by 90 ° by the λλ plate is 9 in the wavelength range of 450 nm to 650 nm by the retardation plate according to the present invention.
8% or more, indicating a good 1 / 2λ function.

(Comparative Example) Polycarbonate (Pokalon manufactured by Lonza, hereinafter abbreviated as PC) was uniaxially stretched at 175 ° C., which is an atmosphere temperature higher than the thermal deformation temperature, and adjusted to a 275 nm phase difference with respect to a 550 nm light beam. In the stretched PC film, the slow axis coincides with the stretching direction, and the wavelength dispersion value α is 1.09.
It was 8.

As a result of measuring the optical retardation in the wavelength range from 400 nm to 780 nm, the optical function of the 1 / 2λ plate produced from the retardation plate of the stretched PC film was 450 nm.
In the wavelength range from 650 nm to 650 nm, the phase difference was 28%, and the 1 / 2λ function was greatly reduced.

When a PC retardation plate is inserted between the polarizer and the analyzer, the transmitted light intensity when the polarizer and the analyzer are arranged in parallel Nicols, and the polarizer and the analyzer are arranged in crossed Nicols. By measuring the transmission high intensity in the case, the polarization conversion function of the retardation plate manufactured so as to be adjusted to a half wavelength can be improved.
The measurement was performed in a wavelength range from 0 nm to 780 nm. As for the efficiency with which the plane of polarization of linearly polarized light is converted into linearly polarized light that has been converted by 90 ° by the λλ plate, a distribution of 84% to 99.9% is confirmed by a PC retardation plate in a wavelength range of 450 nm to 650 nm, A decrease in 1 / 2λ function was indicated.

[0026]

As described above, by using the retardation plate of the present invention, the optical phase difference at all wavelengths in the visible light range becomes almost uniform irrespective of the light wavelength. In addition to being easily obtained, a wave plate for each applied light wavelength is not required when a wave plate is obtained, and a retardation plate having an advantage that one wave plate can be applied to the entire wavelength range can be provided. . The retardation plate of the present invention takes advantage of the above-mentioned characteristics, and can be applied to a wide range of applications such as various display elements requiring polarization, particularly liquid crystal display elements, optical switches, optical filters, and various optical measuring instruments including the same. Is possible.

[Brief description of the drawings]

FIG. 1 Wavelength dispersion characteristics of a retardation plate in the visible light region

FIG. 2 shows a retardation characteristic in a visible light region of a half-wave plate produced by the retardation plate of the present invention.

FIG. 3 shows a polarization conversion characteristic in a visible light region of a half-wave plate manufactured using the retardation plate of the present invention.

Claims (10)

[Claims] 1. A wavelength dispersion value α (α = Δn) of a birefringence index n.
(450 nm) / Δn (650 nm)) is α _A <
In the retardation plate obtained by laminating a film or sheet consisting of A and B polymer is alpha _B, the relationship of the phase difference R of the polymer is R _A> R _B, laminated to the orientation slow axis of each polymer is perpendicular And a chromatic dispersion value α is smaller than 1. 2. The retardation plate according to claim 1, wherein a film or a sheet made of each polymer is laminated via an adhesive layer having an in-plane retardation of 5 nm or less. 3. The retardation plate according to claim 1, wherein a film or a sheet made of each polymer is laminated via an adhesive layer having at least one kind of liquid crystal composition. 4. A wavelength dispersion value α (α = Δn) of a birefringence index Δn.
(450 nm) / Δn (650 nm)) is α _A <
In alpha _B retardation plate obtained by laminating a film or sheet consisting of A and B polymers is, polypropylene A polymer, polymethyl methacrylate, ethylene - vinyl alcohol copolymer, amorphous polyolefins, triacetate, diacetate, polyvinyl alcohol 4. The retardation plate according to claim 1, wherein the retardation plate is at least one selected from the group consisting of: 5. A wavelength dispersion value α (α = Δn) of a birefringence index Δn.
(450 nm) / Δn (650 nm)) is α _A <
In the retardation plate obtained by laminating a film or sheet consisting of A and B polymer is alpha _B, the group B polymer is polystyrene, polyarylate, polycarbonate, polysulfone, polyether sulfone, polyetherimide, polyimide, polyvinylidene fluoride Claim 1 characterized by being at least one kind selected from
4. The retardation plate according to 2 or 3. 6. The method of claim 1, wherein the phase difference R is _{(R A -R B) = λ} / 4 1 / 4λ plate, adjusted to
The retardation plate according to 2, 3, 4 or 5. 7. The method of claim 1, wherein the phase difference R is _{(R A -R B) = λ} / 2 1 / 2λ plate, adjusted to
The retardation plate according to 2, 3, 4 or 5. 8. A part that divides a part of the unpolarized light into two polarized lights whose polarization planes are orthogonal to each other, and matches the polarization plane of the polarized light whose polarization plane does not change by changing one of the two polarization planes. A polarizing element comprising a modulating section for causing the phase difference plate according to claim 7 as a modulating section. 9. A unit for converting non-polarized light into polarized light, wherein the unit is a sheet-like polarizing element that is continuously processed, and the unit is configured to reflect a part of the non-polarized light and reflected light whose polarization planes are orthogonal to each other. The retardation plate according to claim 7, wherein the sheet-like polarizing element has a portion that divides the transmitted light and a modulator that changes the polarization plane of the reflected light to match the polarization plane of the transmitted light. A sheet-like polarizing element comprising: 10. A cube-type polarization beam splitter, and one light exit surface on the reflected light side of the polarization beam splitter is provided.
A 偏光 wavelength plate is used as a 反射 wavelength plate in a light reflecting plate bonded and bonded so as to sandwich a 波長 wavelength plate and at least two or more right angle prisms bonded together with the reflecting plate and the polarizing beam splitter therebetween. A polarizing element comprising the retardation plate according to claim 6.