JPH10239518A - Phase difference plate, and polarizing element using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a uniform phase difference regardless of wavelength in optical phase difference of all wavelength of visual light, by specifying the wavelength dispersion value of a phase difference plate of such structure that a plural kinds of double reflective media different in the wavelength dispersion value of a double refractive index are laminated in the orthogonally crossing state of respective lag axes. SOLUTION: In the phase difference plate formed by laminating double refractive media 10, 20 different in the wavelength dispersion value α [α=▵n (450nm)/▵n (650nm)] of a double refractive index ▵n, in the orthogonal state of lag axes 11, 21, the wavelength dispersion value α of this phase difference plate is made smaller than 1. When white linear polarized light enters this phase difference plate, optical phase difference generated from material with a characteristic of small wavelength dispersibility is cancelled by phase difference generated by material with a characteristic of large wavelength dispensability, and the cancelled phase difference quantity is larger in the phase difference generated in shorter wavelength. Longer the wavelength, phase difference amount shows the tendency of more monotoneous increase, and the polarized light incoming as white light also generates uniform phase difference in a visible light area so as to be obtained as white polarized light.

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 having a structure in which the slow axes of two or more types of birefringent media different in direction are perpendicular to each other, wherein the wavelength dispersion value α of the retardation plate is smaller than 1. I do.

Further, a chromatic dispersion value α (α = Δn (450n
m) / Δn (650 nm)) are characterized by being laminated via one or more adhesive layers having a phase difference of 5 nm or less within the adhesive layer surface.

Further, a chromatic dispersion value α (α = Δn (450n
m) / Δn (650 nm)) are laminated via an adhesive layer having at least one liquid crystal composition.

[0008] Also, 1 / when the phase difference R is adjusted to λ / 4.
It is a 4λ plate.

[0009] Further, 1 / in which the phase difference R is adjusted to λ / 2,
It is a 2λ plate.

[0010] Further, a portion that divides a part of the unpolarized light into two polarized lights whose polarization planes are orthogonal to each other and coincides with the polarization plane of the polarized light whose polarization plane does not change by changing one of the two polarization planes. 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.

[0012] Further, a cube-type polarizing beam splitter and a light exit surface on the reflected light side of the polarizing beam splitter are arranged on the same.
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.

[0013]

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 =
Since the birefringent media having different Δn (450 nm) / Δn (650 nm) are laminated so that the slow axes are perpendicular to each other, an optical phase difference generated from a material having a small characteristic of wavelength dispersion is: It is canceled out by the phase difference caused by the material having the characteristic of large wavelength dispersion. At this time, since the phase difference is canceled by the material having the property of large wavelength dispersion, the phase difference generated at a shorter wavelength has a larger amount of the canceled phase difference.

That is, with the retardation plate of the present invention, the shorter the wavelength of the incident light beam, the smaller the phase difference, and the longer the wavelength of the incident light beam, the larger the phase difference. 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.

[0015]

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 retardation plate of the present invention has a structure in which two or more layers of materials having different wavelength dispersion values α are stacked in a state where the slow axes of the respective phase differences are perpendicular to each other. The laminated structure is preferably a two or more layered structure if the adhesion or adhesion between the materials to be laminated is practically no problem, but a structure via an adhesive layer if the materials have poor adhesion or adhesion. There is no problem even if the layer configuration has three or more layers.

The characteristic state of the materials to be laminated will be described in more detail. A material having a small chromatic dispersion value and a material having a large chromatic dispersion value are laminated with their slow axes perpendicular to each other. Further, it is preferable that the phase difference of a material having a small wavelength dispersion is larger than the phase difference of a material having a large wavelength dispersion.

When the phase difference of a material having a small wavelength dispersion is smaller than the phase difference of a material having a large wavelength dispersion, the phase difference due to the birefringent medium having a large wavelength dispersion is reduced by the birefringent medium having a small wavelength dispersion. When the phase difference is canceled by the phase difference, the wavelength dispersion value of the phase difference plate having the laminated structure may not be smaller than 1 because the amount of the canceled phase difference is small.

Next, the operation of the phase difference plate of this embodiment will be described.

When linearly polarized white light is incident on the retardation plate of the present invention, the wavelength dispersion value α (α = Δn (4
Since the A and B birefringent media having a relationship of [alpha] _A <[alpha] _B with respect to [50 nm) / [Delta] n (650 nm)] are laminated so that the slow axes are perpendicular to each other, the characteristic of [alpha] _{A having} a small wavelength dispersion is obtained. Is canceled out 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.

Since the relationship of the phase difference (R) of each birefringent medium is R _A > R _B , the emitted phase difference is emitted as polarized light having a smaller phase difference as the wavelength becomes shorter. That is,
According to the retardation plate of the present invention, the shorter the wavelength of the incident light beam, the smaller the phase difference, and the longer the wavelength of the incident light beam, the larger the phase difference. Therefore, the wavelength dispersion characteristic of the retardation plate according to the present invention tends to monotonically increase as the wavelength increases, and the optical phase difference at all wavelengths of visible light has a uniform phase difference regardless of the wavelength. The polarized light incident as white light can also be obtained as white polarized light because a uniform phase difference occurs in the visible light region.

Next, the material of each component of the phase difference plate of this embodiment will be described.

The birefringent medium constituting the retardation plate is a stretched polymer film, a low-molecular liquid crystal having a long molecular axis oriented in one direction, a polymer of a photocurable liquid crystal, a low-molecular liquid crystal and a photocurable liquid crystal. Liquid crystal composite polymer, thermosetting liquid crystal polymer, low molecular liquid crystal / thermosetting liquid crystal composite polymer, side-chain polymer liquid crystal, main-chain polymer liquid crystal with controlled orientation and thickness, liquid crystal It is selected from the group consisting of liquid crystal cells in which the composition is sandwiched between solid substrates, inorganic oxides, dichroic organic molecules formed by a dry process such as oblique evaporation, and crystalline materials such as mica and quartz. It is a laminated phase difference plate made of two or more kinds of materials having different wavelength dispersion values α, and is preferably configured to give a uniform phase difference to an incident light flux. Those having a large difference are more preferable.

[0024]

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 is a configuration diagram of a phase difference plate of the present invention.

FIG. 2 is a configuration diagram of a retardation plate of the present invention.

FIG. 3 is a configuration diagram of a phase difference plate of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Birefringent medium with small wavelength dispersion value and large phase difference 11 Slow axis of birefringent medium 10 20 Birefringent medium with large wavelength dispersion value and small phase difference than birefringent medium 10 21 Birefringence Slow axis of medium 20 30 Adhesive layer 40 Birefringent medium with small wavelength dispersion value and large phase difference 41 Slow axis 50 of birefringent medium 40 Large wavelength dispersion value and twice as large as birefringent medium 40 Birefringent medium having smaller phase difference than phase difference 51 Slow axis of birefringent medium 50

Claims (8)

[Claims] 1. A wavelength dispersion value α (α = Δn) of a birefringence index Δn.
(450 nm) / Δn (650 nm)) in a retardation plate having a structure in which two or more types of birefringent media having different retardation axes are perpendicular to each other, have a wavelength dispersion value α of 1 or more. A phase difference plate characterized by being small. 2. A chromatic dispersion value α (α = Δn (450 nm)
2. The retardation plate according to claim 1, wherein birefringent media having different / Δn (650 nm) are laminated via one or more adhesive layers having a retardation in the plane of the adhesive layer of 5 nm or less. 3. A chromatic dispersion value α (α = Δn (450 nm)
2. The retardation plate according to claim 1, wherein birefringent media having different / Δn (650 nm) are laminated via an adhesive layer having at least one type of liquid crystal composition. 4. A quarter-wave having a phase difference R adjusted to λ / 4.
4. The phase difference plate according to claim 1, wherein the phase difference plate is a plate. 5. A half-wave having a phase difference R adjusted to λ / 2.
4. The phase difference plate according to claim 1, wherein the phase difference plate is a plate. 6. A part that divides a part of the unpolarized light into two polarized lights whose polarization planes are orthogonal to each other, and matches a polarization plane of a polarized light whose polarization plane is not changed by changing one of the two polarization planes. A polarizing element having a modulating section for causing the phase difference plate according to claim 5 as a modulating section. 7. A unit for converting non-polarized light into polarized light, wherein the unit is a continuously processed sheet-like polarizing element, and the unit is configured to reflect a part of the non-polarized light as reflected light whose polarization plane is orthogonal to each other. 6. The retardation plate according to claim 5, wherein the retardation plate is a modulator in a sheet-shaped polarizing element having 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: 8. A cube-type polarizing beam splitter,
The output surface on the reflected light side of the polarizing beam splitter is 1/4
Claims: In a polarizing element comprising a light reflecting plate bonded together so as to sandwich a wavelength plate, and at least two or more right-angle prisms bonded together across a reflecting plate and the polarizing beam splitter, a 1/4 wavelength plate is claimed. A polarizing element comprising the retardation plate according to 4.