JP2009145772A - Optical element and display device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which is thin in thickness, has a high refractive index and is useful for a camera lens, a shutter or the like. <P>SOLUTION: In the optical element having a transparent magnetic body whose surface has at least a concave or convex shape, a mechanism magnetizing the transparent magnetic body and a polarizer which are provided in this order along an optical path, the transparent magnetic body preferably includes a titania nano-sheet represented by chemical formula:Ti<SB>2-X</SB>M<SB>X</SB>O<SB>4</SB>(wherein M denotes at least one transition metal selected from V, Cr, Mn, Fe, Co, Ni and Cu and x satisfies 0<x<2). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element using the Faraday effect of a transparent magnetic body and a display device using the optical element, and more specifically, a transparent magnetic body having a lens function depending on its shape, and magnetizing the transparent magnetic body An optical element useful as an electric lens shutter that is provided with a mechanism and a polarizer in combination, particularly for electrically switching light at a high speed, and a display device provided with a combination of a light source and a drive circuit on the optical element About.

The present invention provides a transparent magnetic body having a lens function for refracting light and a magneto-optical effect (Faraday effect) function, so that the camera can be opened and closed electrically without a conventional mechanical shutter. The present invention relates to an optical element such as an industrial lens. Conventional techniques in this case include 1) a camera lens and 2) a shutter.
Conventionally, materials such as glass and quartz have been generally used for lenses for optical devices, and a mechanical shutter that opens and closes an optical path has been used.
However, these conventional lenses for optical devices have the following problems and demands. That is, in order to further reduce the size of the optical device, it is a problem that a thinner shape is desired using a material having a large refractive index.
The conventional mechanical shutter has the following problems and requests.
(1) There is variation in opening and closing time due to contact of the shutter blades that open and close. In addition, vibrations were likely to cause image blur.
(2) A mobile phone camera having 3 million pixels or more has been developed. In this case, it is essential to attach a shutter that can withstand an impact when dropped, but this problem has not been sufficiently solved.
(3) At present, the shutter speed is about 1/2000 seconds at the maximum, but there is a demand for further speeding up and high-speed shooting at low cost.
(4) There are applications in which lenses are two-dimensionally arrayed and used for image formation or for optical communication, but it has been difficult to arrange shutters coaxially on individual lenses.
(5) There has been a demand to reduce the size by eliminating the volume portion of the mechanical shutter to be closed.

By the way, the magneto-optical element using the Faraday effect of the transparent magnetic material has high durability of the magnetic film, that is, high durability against temperature, humidity, chemicals, light and the like, and has high flexibility as the film. If a plastic film is used as the support, it can be used as a flexible magneto-optical element, and has many features that can be rewritten at nanoseconds and can be additionally written with a magnetic pen or the like. For this reason, there are several proposals for magneto-optical elements.
Conventional magneto-optical elements using the Faraday effect include those using “rare earth garnet thin film” as a transparent magnetic material (Patent Document 1) and those using “rare earth iron garnet powder as a coating film” (Patent Document 1). 2) and a magneto-optical element (non-patent document 1) using “rare earth iron garnet single crystal” have been proposed. However, since the heating temperature for forming the “rare earth garnet thin film” is as high as 500 ° C. to 700 ° C., the support to be used is greatly limited, and for example, a plastic film cannot be used. In addition, when “rare earth iron garnet powder” is used, high temperature for crystallization is not required, but due to large light scattering by the grain boundary, transparency of visible light cannot be obtained at a practical film thickness. Therefore, the displayed contrast ratio is small depending on the amount of light at the time of light blocking / light transmission, and a practical contrast ratio cannot be obtained. In addition, “rare earth iron garnet single crystal” is difficult to obtain in a large area, is not flexible, and is expensive.

  As a representative element using Faraday rotation, there is a spatial light modulator jointly developed by Carnegie Mellon University in the 1990s and Lytton (Non-Patent Document 1). In this element, a 3 μm thick single crystal rare earth iron garnet film manufactured by the LPE method is used, and each pixel is separated. This is a method in which X and Y drive lines are used, and magnetization is reversed using the local magnetic field strength at the intersection. However, it is inefficient and therefore uses a large current (250 mA). Further, the X wiring has a complicated structure in which it is embedded in a rare earth iron garnet film in order to increase the magnetic field utilization efficiency.

  However, adapting the magnetic material in the optical element to a camera lens, a two-dimensional lens and a shutter does not reach a desired light transmittance, and it is difficult to obtain a practical Faraday rotation angle. It was considered difficult for a reason. Further, a magnetic garnet well known as a transparent magnetic material (for example, YIG) was not colorless and yellowish due to light absorption by iron ions. Moreover, it was often used by being formed as a single crystal on an epitaxial substrate material such as GGG (gadlium gallium garnet). This single crystal production requires a lot of time and cost and is inconvenient in use.

On the other hand, as a transparent magnetic material, a titania nanosheet has already been proposed (Patent Document 3). Here, a film-forming method (alternative self-organization technique) (FIG. 1) is used in which a titania magnetic semiconductor nano-thin film and an organic film are stacked one by one using electrical energy. It is also possible to add various organic compounds such as a water-soluble organic compound to the titania nanosheet dispersion and use a coating method such as a spin coating method.
This titania nanosheet has a feature that it is very small in the visible light region with respect to light absorption as shown in FIG. Moreover, it has the characteristic that absorption performance is large with respect to ultraviolet light. It has already been reported in Non-Patent Document 2 that a rotation angle of 30 ° / μm can be obtained by laminating two types of titania nanosheets of Co substitution and Fe substitution.

Japanese Examined Patent Publication No. 56-15125 JP-A-62-1119758 JP 2006-199556 A J. Appl. Phys., 76, p1910 (1994) J-k.Cho et al. Adv.Mater., 18,295-299 (2006)

  The present invention has been made in view of the above problems in the prior art, and is to provide an optical element that is thinner and has a large refractive index, and further described above by using this optical element. Eliminates mechanical shutter problems, that is, (i) eliminates opening / closing time fluctuations and vibrations due to contact of shutter blades that open and close, (ii) improves shutter speed, and (iii) reduces shutter function , (Iv) All two-dimensional arrayed lenses can individually control the opening and closing of the optical path at high speeds, especially optical elements useful for camera lenses and shutters, and color images, etc. It is an object of the present invention to provide a display device that can be displayed in the same manner.

According to this invention, the said subject is solved by following (1)-(8).
(1) An optical element comprising a transparent magnetic material having a concave or convex surface at least, a mechanism for magnetizing the transparent magnetic material, and a polarizer in this order along the optical path.
(2) The transparent magnetic material has a chemical formula: Ti _2-X M _X O ₄ (where M = V, Cr, Mn, Fe, Co, Ni, Cu, at least one transition metal, 0 <x <2) The titania nanosheet represented by (2) is contained, The optical element as described in said (1) characterized by the above-mentioned.
(3) In the above (1) or (2), the thickness of the transparent magnetic material is continuously changed, and the mechanism of magnetization according to the continuous thickness change has a magnetic field gradient. The optical element described.
(4) The transparent magnetic body according to any one of (2) and (3), wherein the transition metal substitution amount of the titania nanosheet is reduced corresponding to the continuous increase in thickness. Optical element.
(5) The optical element according to any one of (1) to (4), wherein the transparent magnetic body is provided as a regular two-dimensional array on a transparent support.
(6) An optical element characterized in that a polarization conversion element is disposed and used on the incident light side of the optical element according to any one of (1) to (5).
(7) The optical element according to any one of (1) to (6), wherein the transparent magnetic body is provided in a depressed portion of a transparent support.
(8) A display device comprising a light source and a drive circuit for a mechanism for magnetizing a transparent magnetic material in addition to the optical element according to any one of (1) to (7).

(1) According to the first aspect of the present invention, the transparent magnetic material surface is formed in a concave shape or a convex shape, and the optical element having a mechanism for magnetizing the transparent magnetic material and a polarizer is provided. By using it together with a light source that generates light, it is possible to have both the lens effect of greatly changing (refracting) the traveling direction of light and the two functions of greatly rotating the polarization plane of the light passing through the optical element.
(2) According to the invention described in claim 2, the chemical formula: Ti _2-X MxO ₄ (wherein M = V, Cr, Mn, Fe, Co, Ni, Cu, at least one kind of transition metal, Since a transparent magnetic material having a concave or convex shape represented by 0 <x <2) and having a large refractive index is used, a thinner and smaller optical element can be provided. In addition, the light transmission and blocking speed of the optical element can be as high as nanoseconds.
(3) According to the invention described in claim 3, since the applied magnetic field strength can be changed in inverse proportion to the continuous thickness change of the transparent magnetic material having a concave or convex shape, it does not depend on the surface shape. The Faraday rotation angle is obtained, and the same effect as that of the first aspect of the invention can be obtained more effectively.
(4) According to the invention described in claim 4, since the substitution amount of the transition metal of the titania nanosheet is changed in inverse proportion to the continuous thickness of the transparent magnetic material having a concave or convex shape, the surface shape is changed. An independent Faraday rotation angle is obtained, and the same effect as that of the first aspect of the invention can be obtained more effectively.
(5) According to the invention described in claim 5, since the transparent magnetic body having a concave or convex shape on the transparent support has a regular two-dimensional array, all the lenses can control the opening and closing of the optical path at high speed. Usefulness as an image display element is improved.
(6) According to the invention described in claim 6, by using a polarization conversion element in which the exit positions of the separated polarized lights coincide with each other in the front of the optical path, the light utilization efficiency which has been 50% at the maximum in the past is used. Can be greatly improved to about 70 to 80%.
(7) According to the invention described in claim 7, since the transparent magnetic body having a concave or convex shape is provided in the depressed portion of the transparent support and used integrally with the support, the image display element The production method becomes simple and can be used as it is.
(8) According to the invention described in claim 8, after arranging a plurality of optical elements, a drive circuit of a mechanism for magnetizing the transparent magnetic bodies of the elements is provided, and light from the light source to each element is provided. Since the light from the light source is enlarged or reduced on the projection screen and used as a display device, it can be used as a display device. There is no need to provide a separate structure, and a compact configuration is possible, and the usefulness is greatly enhanced. If RGB (R: red, G: green, B: blue) elements are combined and provided for one pixel, a color image can be easily obtained, and in particular, the shutter speed (opening / closing speed) uses inversion of electron spin. So fast.

The optical element and display device according to the present invention will be described in detail below.
Since the optical element according to the present invention (the invention described in claims 1 and 2) is useful for a camera lens, a two-dimensional lens and a shutter, a transparent magnetic material is used. The transparent magnetic material used in the present invention can be used not only for visible light but also for ultraviolet light and infrared light, but is applied to a magnetic material having at least a light transmittance of 80% or more, preferably 95% or more. it can. For the transparent magnetic material used in the present invention, a material having a high refractive index εμ1 / 2 (ε is a dielectric constant and μ is a magnetic permeability), that is, a material having a high dielectric constant and magnetic permeability is preferably selected.

  The transparent magnetic material used in the present invention may be a polycrystalline film or a single crystal. The transparent magnetic material may be a ferromagnetic material, or a paramagnetic material or an antiferromagnetic material. In the case of a paramagnetic material, it is an essential condition that an external magnetic field can be applied. The reason why the magnetic material used in the present invention is transparent is dependent on the wavelength of light, and when visible light is used, it is necessary to be transparent at 400 to 800 nm, and ultraviolet light and infrared light. This is because if it is transparent with light or the like, it can be used for different applications such as optical communication.

As a general transparent ferromagnetic material having a Faraday effect in the present invention, oxides such as Co ferrite and Ba ferrite, materials having large birefringence such as FeBO ₃ , FeF ₃ , YFeO ₃ , and NdFeO ₃ , MnBi, MnCuBi, PtCo or the like can be used, and it can be used as thin as possible to obtain transparency (may be combined with a dielectric film). Inorganic magnetic materials with particularly high transparency include n-type Zn _1-X V _X O and Co-doped TiO ₂ .

In addition, rare earth iron garnet represented by the following general formula can be used as a transparent magnetic material that is uniform over the entire visible light and has a large figure of merit.
_{R 3-X A X Fe 5} -y B y O 12
(Where 0.2 <x <3, 0 ≦ y <5,
R is a rare earth metal and is at least one of Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu;
A is at least one of Bi, Ce, Pb, Ca and Pt,
B is Al, Ga, Cr, Mn, Sc, In, Ru, Rh, Co, Fe (II),
It is at least one of Cu, Ni, Zn, Li, Si, Ge, Zr, and Ti. )

The following magnetic materials are used as the paramagnetic materials described above.
The Tb ₃ Al ₅ O ₁₂ single crystal having a cubic garnet structure is transparent in the visible light region and near-ultraviolet light region and has a large Faraday rotation angle. Therefore, the Tb ₃ Al ₅ O ₁₂ single crystal has a large Faraday rotation angle. Can be used. The Tb ₃ Al ₅ O ₁₂ single crystal is manufactured using a flux method or a floating zone method using a laser.

The transparent magnetic material particularly preferably used in the present invention is a titania nanosheet represented by the following chemical formula.
Chemical formula: Ti _2-X M _X O ₄ (where M = V, Cr, Mn, Fe, Co, Ni, Cu, at least one transition metal, 0 <x <2)
This is a flake particle obtained by exfoliating a layered titanium oxide microcrystal having a magnetic element substituted with at least one metal at a Ti lattice position into one layer which is a basic minimum unit of crystal structure by chemical treatment. It is a magnetic semiconductor nano thin film made of (hereinafter referred to as titania nano sheet). This titania nanosheet has a dielectric constant approximately twice that of titanium oxide (rutile) and a large permeability. In other words, since it is thinner and has a higher refractive index, for example, a camera lens, an optical pickup lens, and a two-dimensional array lens can be greatly reduced in size. The nanosheet production method will be described below.

  First, an aqueous solution of acid such as hydrochloric acid is brought into contact with the titanium oxide powder having a layered structure, and the product is filtered, washed, and dried to replace all alkali metal ions present between the layers before treatment with hydrogen ions. A substance is obtained. Next, when the obtained hydrogen-type substance is put into an aqueous solution of amine or the like and stirred, it is colloidalized. At this time, the layers constituting the layered structure are peeled up one by one. The acid treatment in the former stage is disclosed in Japanese Patent Publication No. 6-88786, Japanese Patent No. 1966650 and Japanese Patent Publication No. 6-78166, Japanese Patent No. 1936988, Japanese Patent Laid-Open No. 9-25123, Japanese Patent No. 2671949, and the like. .

As the layered titanium oxide as a starting compound, layered titanium in which at least one transition metal element (V, Cr, Mn, Fe, Co, Ni, Cu) is substituted at the Ti lattice position of the lipidocrocite-type titanate. Oxides Ti _2-X M _X O ₄ (where M = V, Cr, Mn, Fe, Co, Ni, Cu, etc., 0 <x <2) can be used. More preferably, the Fe or Co element is substituted in the range of 0 <x <0.8. As a transition metal element that induces ferromagnetic properties at room temperature or higher, it is desirable to replace Fe or Co element in the range of 0 <x <0.8, but from V, Cr, Mn, Fe, Co, Ni It is possible to adjust ferromagnetic properties such as magnetic susceptibility, magneto-optical properties, magnetic transition temperature, etc. by adjusting the concentration of at least one selected transition metal, combining two or more metals, and adding a dopant. . Replacing two kinds of elements in one nanosheet at the same time, such as Co and Fe, is also an effective method for obtaining a large Faraday rotation angle.

Next, the above layered titanium oxide Ti _2-X M _X O ₄ is acid-treated and converted into a hydrogen type (H _0.8 Ti _2-X M _X O ₄ .nH ₂ O), and then an appropriate amine or the like is used. Solize by shaking in aqueous solution. In this solification step, the chemical formula: Ti _{2 -X} M _X O ₄ (wherein M = V, Cr, Mn, Fe, Co, Ni, Cu, at least one transition metal, 0 <x < The titania nanosheet having 2) is produced, and the layers constituting the mother crystal, that is, the nanosheets are dispersed in water one by one in the sol solution. The thickness of the nanosheet depends on the crystal structure of the starting mother crystal, but is extremely thin, around 1 nm. On the other hand, the lateral size is on the order of μm and has a very high two-dimensional anisotropy in shape.

  In addition, in the titania nanosheet demonstrated above, it can form as a transparent magnetic body with very little wavelength dependence of the Faraday rotation angle in a visible light region. Therefore, it can be used as a lens that must have a small wavelength dependency. For example, a CoFe simultaneous substitution nanosheet shown in Example 1 described later can be mentioned, and the wavelength dependency in the visible light region is extremely small.

  By the way, as described in the problem of the prior art, when the titania nanosheet dispersion is directly applied to a thickness of about 1 μm by a spin coater or other application method, transparency cannot be obtained by light scattering from the randomly stacked nanosheets. There is a problem that. Here, TBA (tetrabutylammonium) is preferably used as a dispersant for the titania nanosheet dispersion. Of course, other dispersants may be used. However, since the titania nanosheet has a negative charge, a material that does not cause aggregation due to electrical coupling is required. TBA is used as a dispersant in an aqueous solvent and has a structure that covers almost the entire surface of the nanosheet with a single layer during film formation, and surrounds the nanosheet.

  In the present invention, by using a water-soluble (aqueous) polymer as a water-soluble organic compound in addition to the dispersant, light scattering can be reduced and the transparency of the film can be ensured. The light scattered by the nanosheet seems to pass through the magnetic material like an optical waveguide by the added transparent polymer.

  If the amount of the water-soluble (aqueous) polymer used is too small, it cannot function as a light passage. On the other hand, if the amount is too large, the function as a magnetic material will be too low. Examination of the optimum mixing amount between 0 to 40% by weight reveals that the transparency improves in proportion to the mixing amount, but 5 to 30% by weight gives a high transmittance and is particularly preferable. It was. If the content is 31% by weight or more, the magnetic characteristics, particularly the Faraday rotation angle, is remarkably lowered. Therefore, a mixing amount of 30% by weight or less is preferable.

  In addition, the use of a water-soluble (aqueous) polymer has an effect of greatly reducing bubbles encapsulated by a dispersant such as TBA. When a water-soluble (aqueous) polymer is not used, the film after the film formation and drying contains many pores (length of several hundred nm to several μm), and light scattering causes film formation. Although the transparency is lowered, when a water-soluble (aqueous) polymer is used, these pores are not seen even when observed by cross-sectional TEM. As a result, the transparency of the film is greatly improved. The transparency of the film is very important when the product of the present invention is used.

  The water-soluble (aqueous) polymer mentioned here is a polymer that dissolves in water. For example, natural polymers such as starch, casein, glue, gelatin, gum arabic, sodium alginate, pectin, carboxymethylcellulose, methylcellulose, Examples include semisynthetic polymers such as viscose, and synthetic polymers such as polyvinyl alcohol, polyacrylamide, polyethyleneimine, sodium polyacrylate, polyethylene oxide, and polyvinylpyrrolidone.

  In addition, it is preferable that the magnetic body (transparent magnetic body) produced in this way removes moisture absorbed by TBA after film formation by overheating or UV irradiation, and it is understood that the Faraday effect of the nanosheet layer is more exhibited. It was. The heating may be about 100 ° C. to 150 ° C., about 10 minutes to several hours. Moreover, it is preferable that UV irradiation is sufficiently performed for several hours to several tens of hours. For example, the Faraday rotation angle when applied to a thickness of 1 μm depends on the magnetic atom substitution conditions of the titania nanosheet, but a practically applicable value of 5 to 20 ° was obtained.

In the transparent magnetic material of the present invention, the water-soluble (aqueous) polymer is preferably gelatin.
In the present invention, the nanosheets are preferably used by being laminated, but among the water-soluble (aqueous) polymers, gelatin is particularly preferable in this respect (lamination of nanosheets). When gelatin and other water-soluble polymers such as carboxymethyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol are used at 10% by weight of the nanosheet, when the film thickness is 1 μm, the diffraction peak (2θ≈4 in the X-ray diffraction diagram) is applied. .8 °) intensities were as follows.
・ Carboxymethylcellulose 33 kcounts / s
・ Hydroxyethylcellulose 11 kcounts / s
・ Polyvinyl alcohol 18 kcounts / s
・ Gelatin 75 kcounts / s

  The intensity of the diffraction peak (2θ≈4.8 °) is generated by the lamination period of the nanosheets and is called a first-order diffraction line, and other second-order and third-order diffraction lines appear. Since the diffraction peak intensity increases in proportion to the state of the high regularity of nanosheets on the support, it can be said that it is very preferable in the case of gelatin. When the cross section of the film using gelatin is observed by the TEM method, the number of pores in the film and the surface unevenness are the smallest compared to the three types of water-soluble polymers other than gelatin (smoothness is low). It was found that the film is most preferable because high transparency of the film can be obtained. In addition, it is preferable to use gelatin with a high protein degradation rate because it causes less aggregation with the nanosheet.

In the optical element of the present invention, a transparent support is not always essential, but a lens made of the transparent magnetic material of the present invention may be formed on the transparent support.
In addition, the magnetic body of the present invention is provided on a transparent support as necessary. In this case, it is preferable to provide an underlayer (surface treatment layer) that reduces the surface contact angle with water on the surface of the support. .
As described above, the periodic arrangement of nanosheets is very important. As a factor for improving the alignment, the surface contact angle of the support with water was found to be as low as 10 ° or less. Surface contact angle with a film thickness of 1 μm using a nanosheet dispersion (gelatin mixture) in which the elements to be substituted at the Ti lattice positions are Co and Fe (Fe _0.2 Co _0.3 Ti _1.5 O ₄ ) Is applied on a glass support of 5 °, there is a large difference in the intensity of diffraction peaks (2θ≈4.8 °) in the X-ray diffraction pattern as compared to the case of glass with an untreated surface contact angle of 21 °. Appearance was about 10 times larger in the case of glass with a surface contact angle of 5 °, and the transparency of the film was higher.

  It was found that the Faraday rotation angle of the film decreases when the nanosheets are low in alignment. When the surface contact angle is high, it is considered that the nanosheets in the dispersion are not well adapted to the support surface, and therefore the arrangement of the nanosheets thereon is different.

  There are various conventional methods for reducing the surface contact angle. For example, a method is often used in which the surface of the support is cleaned using various plasmas such as oxygen, ozone, nitrogen, and argon. In addition, the nanosheet has a special shape (for example, 1 nm in thickness × 1 μm in length × 1 μm in width) and has an electrically strong negative charge, so the concentration of the nanosheet dispersion cannot be increased. For this reason, the size of the surface contact angle is particularly important, and it is required to be stable and low for a long time. There is also a method in which a low surface contact angle can be obtained for a long time by processing such as providing a base layer on the surface of the support. For example, a surface modification method for injecting reactive groups onto the resin surface using an ion beam in a vacuum atmosphere in air, a method for applying various organic materials such as surfactants, a method for providing fine irregularities on the surface, oxidation It is preferable to provide a surface treatment layer such as a method of providing a transparent inorganic material having a catalytic function such as titanium by a PVD method, a CVD method, a coating method, or the like.

  Since the optical element of the present invention is useful for a camera lens, a two-dimensional lens, and a shutter, the shape of the transparent magnetic material is important, and the surface is not a flat plate shape, and the surface is concave or convex. It needs to be formed into a shape. That is, the transparent magnetic body has a concave or convex surface shape in order to provide a lens function. This is because the light is refracted greatly, and in particular, as described above, it is used taking advantage of a large refractive index. In this transparent magnetic body having a concave or convex surface, a part of the flat plate is not formed in a concave or convex shape, but the light transmitting surface has at least a concave or convex shape, preferably The concave or convex shape changes continuously (including constant). Even when used in a rectangular groove shape or the like, the lens effect such as condensing and divergence is larger than the conventional one due to the large refractive index of the transparent magnetic material. The shape of the surface that does not transmit light is not particularly limited.

  Since the shape of the surface of the transparent magnetic material preferably changes continuously, the surface (outer shape) that does not transmit light is appropriately used, such as a circle or a corner, but the refractive index of light changes due to the continuous change, The lens effect appears. The simplest example is a concave lens or a convex lens. The transparent magnetic material may be magnetized in advance or may not be magnetized.

The refractive indexes of lenses currently on the market are 1.50 to 1.74 for plastic lenses and 1.50 to 1.90 for glass lenses. In this way, the glass lens can be made thinner in terms of refractive index, but it is thin and light because the specific gravity is as large as 2.41 to 3.99 for glass compared to 1.17 to 1.35 for plastic. I can't.
In the present invention, the specific gravity of the titania nanosheet that is particularly preferably used in the transparent magnetic material is about 2.0 to 2.5 because the half is composed of a polymer material, as will be described in detail later. Further, the refractive index is as extremely large as 2.0 to 3.0. For this reason, a thin and light lens can be produced.
However, since conventional titania nanosheets were used in the form of a flat film, they could not be used as lenses even if they were highly transparent. The inventors of the present invention can obtain a transmittance of 80 to 95% by mixing about 5 to 20% by weight of gelatin with the dispersion of titania nanosheets or by reducing the surface contact angle on the support. As a result, the present invention has been achieved. Since gelatin has an adhesive function in addition to the effect of improving the alignment of titania nanosheets and improving the surface smoothness, the shape can be maintained as an optical element.

  In the present invention, the transparent magnetic body does not necessarily have to have a concave or convex shape on the entire surface through which light passes, and may have a shape combined with a flat surface. For example, a composite optical element in which a convex lens (a ridge-like protrusion) is provided on a flat sheet substrate may be used.

  In the present invention, the surface shape of the transparent magnetic material is formed in a concave or convex shape in order to provide a lens function, but in order to further provide a high-speed shutter function, a polarizer on the transparent magnetic material, A mechanism for magnetizing the transparent magnetic material in the vicinity of the transparent magnetic material, such as a magnetic coil or a permanent magnet, is provided and used as an optical element. In this optical element, light is transmitted or blocked by energizing the magnetic coil and power failure. Since the magnetization of the magnetic material is caused by the change in the direction of electron spin, the magnetization direction of the transparent magnetic material can be reversibly changed at a high speed of about nanoseconds in the traveling direction of light or in the direction opposite to the traveling direction. Has characteristics.

  Therefore, if the magnetization direction of the transparent magnetic material is changed by a magnetic coil or the like, the shutter speed of about 1/2000 seconds can be increased to about 1/1000000000 seconds and about 500,000 times with the conventional mechanical shutter. Have Furthermore, the variation in opening / closing time and the vibration due to the contact of the shutter blade that opens and closes, which is a problem of the conventional mechanical shutter, are eliminated. It is possible to provide a mechanical shutter function with a reduced size. In addition, it is possible to individually control the opening and closing of the optical path of all the two-dimensional arrayed lenses at high speed.

When polarized light from a polarized light source, for example, a polarized light emitting LD, enters the optical element, the polarization plane rotates to the right or left with respect to the traveling direction (optical axis) depending on the magnetization direction. This is a phenomenon called the Faraday effect.
In the present invention, since a mechanism for magnetizing the transparent magnetic material is provided, the polarization plane of light passing through the transparent magnetic material having a lens function can be rotated in this way. When the light transmitted through the transparent magnetic material is received by a light receiving device having a polarizer, light reception can be switched (with or without light reception) depending on whether it is right-handed polarized light or left-handed polarized light.

  In this case, since the S / N is better when the Faraday rotation angle of the transparent magnetic material is larger, it is important to improve the arrangement of the nanosheets when the titania nanosheet is used as the transparent magnetic material, for example, At the time of lens formation, it is necessary to take measures such as applying a magnetic field of about 3 to 15 Tesla in parallel or perpendicular to the substrate surface, or reducing the contact angle of the substrate surface with water to about 5 °. Moreover, when a titania nanosheet is used, it can be formed in an uneven shape without a support.

  The transparent magnetic material in the present invention preferably has a concavo-convex shape that changes continuously, but in addition to this, it can be changed into a stepped shape, that is, a lattice shape, to have a lens function. The unevenness can be used by forming it into a wave shape or a hook shape. Further, the magnetic field application direction may not necessarily be parallel to the light traveling direction (optical axis), or a mode not applied as the third mode may be added. In this case, the rotation is in the right or left direction. In addition, it is possible to use modes such as transmission, blocking, and intermediate transmission with a mode in which the rotation is substantially zero.

As described above, in the optical element of the present invention, a transparent support is not always essential, but a lens made of the transparent magnetic material of the present invention may be formed on the transparent support. As a material of the transparent support, generally, quartz glass, GGG, sapphire, lithium tantalate, crystallized transparent glass, Pyrex (registered trademark) glass, single crystal silicon, Al ₂ O ₃ , Al ₂ O ₃ .MgO, MgO _{· LiF, Y 2 O 3 ·} LiF, BeO, transparent ceramic material such as _{ZrO 2, Y 2 O 3,} ThO 2 · CaO, inorganic materials such as inorganic silicon may be used.

Various commercially available polarizing films can be used as the polarizer layer. The polarizing film is roughly classified into a multi-halogen polarizing film, a dye polarizing film, a metal polarizing film, and the like, but is not limited thereto. The following polarizers can also be used.
(1) Polarizer described in Japanese Patent Application Laid-Open No. 01-93702 It is easy to manufacture by arranging and fixing in a fixed direction on the surface of a polarizing layer support including a large number of rod-shaped elements made of ferromagnetic fine particles. It is a polarizing plate with excellent optical characteristics.
(2) Wire grid polarizer (written by Tokyo University of Agriculture and Technology, Katsuaki Sato “Physics of Modern People: Light and Magnetism” (Asakura Shoten) published in 1988, page 103)
There is a transparent support with gold or aluminum lines drawn at minute intervals. In this case, if the distance d between the lines and the wavelength are λ, it is utilized that the transmitted light is almost completely linearly polarized light having a vibration plane perpendicular to the line for light having a wavelength of λ >> d. The degree of polarization is said to be about 97%.
(3) “Polacore” manufactured by Corning
Unlike conventional organic polarizing elements, heat-resistant, moisture-resistant, chemical-resistant, and laser-resistant glass that has polarization characteristics by aligning long stretched metallic silver in the glass itself in one direction Very good. Infrared is mainly used, but there is a special specification for visible light.
(4) Multilayer polarizer Produced by Prof. Shojiro Kawakami of Tohoku University Research Institute of Electrical Communication around 1991. For visible light, RF sputtering is used to form Ge (germanium) with a thickness of 6-8 nm and 1 μm. The layers are made by alternately laminating SiO 2 having a thickness of 60 μm. The figure of merit αTE / αTM (ratio of extinction constant to TE wave and TM wave) measured at a wavelength of 0.6 μm is close to 400, the extinction ratio measured at a wavelength of 0.8 μm is 35 dB, and the insertion loss is 0.18 dB. Yes, enough for visible light.
(5) Reflective polarizer This is sold by Sumitomo 3M Co., Ltd. Hundreds of thin films with different refractive indexes are stacked and stacked, and the polarized light is extracted by repeating reflection and transmission between the layers. It is called a reflection type in order to reflect one of S and P polarized light and allow one to pass. The total thickness is about 100 μm. Compared to the absorption type, the image is felt bright because it is reflected. There is also a wire-grid reflective polarizer with periodic arrangement of aluminum thin wires from Moxtek.
(6) Polarizing beam splitter An optical element that splits or combines a light beam into two or more beams is called a beam splitter. Among them, the one that splits the branched two light beams so that the polarization directions are different is called a polarization beam splitter. In general, a surface in which two right-angle prisms are bonded is coated with a dielectric multilayer film. The P-polarized component is transmitted and the S-polarized component is reflected by 90 degrees. A transmittance and a reflectance of 98% or more can be obtained. Others use special gratings.
(7) Polarizing prism A uniaxial crystal has a different refractive index between an ordinary ray that vibrates perpendicularly to the optical axis direction and an extraordinary ray that has a vibration direction within the main cross section including the optical axis. When two cut out prisms are combined, light having different vibration surfaces can be separated. There are Nicol prism, Gran Thompson prism, Gran Foucault prism, Grand Taylor prism, Lotion prism, Wollaston prism and so on.
(8) Diffraction grating If the pitch of the diffraction grating is reduced, the transmittance of TE wave and TM wave will be different and function as a polarizer. Although not called a polarizer, it has a polarizer function and can be used as a polarizer in the present invention.

  FIG. 3 shows a configuration example of the optical element of the present invention in which a polarizer and a magnetic coil are further provided on or in the vicinity of a transparent magnetic material, and light is transmitted or blocked by energization and power failure of the magnetic coil.

  For the magnetic coil, it is preferable to wire the coil around the light passage path from the viewpoint of uniformity of magnetic field, control of magnetic field distribution, and the like. The outer shape of the coil is selected as appropriate, such as a circle or a rectangle. The polarizer can be used as a curved surface or as a flat surface. The number of the polarizers used may be two before and after the transparent magnetic material, or one may be used when the linearly polarized light is used for the incident light. It is necessary to dispose after passing through the transparent magnetic material.

  As a method for producing a magnetic coil, a method of directly patterning and bonding a conductive thin wire, a method of forming a conductive thin wire so as to be printed using an ink jet method, and a plating method (JP 2003-1224047 A, etc.) Or the like. Although the width | variety of a conducting wire is based on the objective, it is used at 5-50 micrometers.

In the present invention, the direction of the generated magnetic field is controlled by changing whether the magnetic coil is energized or not, and the energizing direction is positive or negative, thereby controlling the magnetization direction of the transparent magnetic material (including the magnetization intensity). By changing the rotation direction and angle of the polarization plane. In this case, unlike the conventional case, the polarized light is refracted by the shape of the transparent magnetic material and the direction is bent. Moreover, although the polarization switching speed depends on the electric circuit and the like, it is as high as several microseconds to several nanoseconds, and the shutter speed can be improved.
In addition, as described above, it is possible to eliminate variations in opening / closing time and vibration due to contact of the shutter blades that are opened and closed, which has been a problem with conventional mechanical shutters. Further, the mechanical shutter function can be provided with a reduced size.

In the optical element of the present invention, it is preferable that the mechanism for magnetizing the transparent magnetic body has a magnetic field gradient according to the continuous thickness change of the concave or convex transparent magnetic body (claim 3). Invention).
A mechanism for magnetizing the transparent magnetic material, such as a magnetic coil, is not necessarily required for one optical axis, and a plurality of mechanisms may be used for controlling the magnetic field distribution. In particular, in the general lens shape, the thickness of the transparent magnetic material is different between the center and the periphery, and the optical path length passing through the lens is different, so the Faraday rotation angle of the transmitted light is also different. By changing the number of turns on the outside and increasing the number of turns closer to the center or on the contrary, the generated magnetic field distribution can be changed between the center side and the outside. There is also a magnetic field strength distribution change addition method that changes the amount of energization by providing a separate outer coil), or by adding a high permeability material of various shapes to generate a magnetic field so that the rotation angle is constant Need to be corrected. A plurality of transparent magnetic bodies having a concavo-convex shape may be formed.
Needless to say, the Faraday rotation angle is made uniform in the utilization plane by weakening the applied magnetic field strength for the thick transparent magnetic material and strengthening the thin magnetic material.

The optical element of the present invention corresponds to a continuous increase in thickness of a transparent magnetic material having a concave or convex shape, that is, a titania nanosheet, that is, a chemical formula: Ti _2-X M _X O ₄ (where M = V, Cr, It is preferable to reduce the substitution amount of the transition metal in at least one transition metal selected from Mn, Fe, Co, Ni, and Cu, 0 <x <2) (the invention according to claim 4).
As a correction method, there are a method using the magnetic field distribution applied in this way and a method of reducing the amount of the transition metal to be replaced, contrary to the increase in the thickness of the transparent magnetic material.
As for the element substitution method, as described in the method for producing titania nanosheets, the layered titanium oxide Ti _{2-X in} which the desired transition metal element is substituted at the Ti lattice position of the lepitocrosite type titanate as the starting compound. M _X O ₄ may be used. As a specific substitution example, an example of Ti _1.5 Fe _0.2 Co _0.3 O ₄ in which Fe and Co are simultaneously substituted in the same material will be described in Example 1.

The optical element of the present invention may be one in which a transparent magnetic body having a concave or convex shape is provided as a regular two-dimensional array on a transparent support (the invention according to claim 5). An example of this configuration is shown in FIGS.
As shown in FIG. 6, after processing the surface of the transparent support, a transparent magnetic material is provided at the processing site (for example, a dispersion of transparent magnetic material is poured and then dried), and the support and the magnetic material are integrated. May be used. The surface of the transparent support can be processed by a so-called molding method using a transparent plastic, and the dispersion of the transparent magnetic material can be put into the processing site and dried. As indicated by the arrow of “light passing direction” shown in FIG. 6, whether light is incident from above or below is appropriately selected according to the purpose. With such a configuration, in the optical communication field or the image forming field that can be placed on a projector, it is not necessary to enlarge or reduce the image, to project or block the image, or to use a new lens mechanism. Can be made compact.

The optical element of the present invention may be one in which a polarization conversion element is disposed on the incident light side of the optical element (the invention according to claim 6).
An optical element (Claim 1) in which a transparent magnetic body having at least a concave or convex surface, a mechanism for magnetizing the transparent magnetic body, and a polarizer are provided along the optical path in this order is a linearly polarized light. However, it does not have a polarizer function for converting circularly polarized light into linearly polarized light. The optical element of the present invention having a polarization conversion element arranged on the incident light side is useful as an electric lens shutter that electrically switches light at a high speed.

  If a conventional polarizer is used as it is, the problems of light utilization efficiency and polarization separation remain, and the lens cannot be used. The present invention (Claim 6) is characterized in that a polarization conversion element is provided in front of the optical element as having a polarizer function. A polarizer can only achieve 50% light utilization efficiency at most, but if this polarization conversion element is used, the light utilization efficiency is 70% or more, and the adaptability is also improved for lenses such as cameras where the amount of light is important. It was decided to do.

  Here, polarization separation will be described using a conventional polarization conversion element (FIG. 5). As shown in FIG. 5, in the conventional polarization conversion, two orthogonal linearly polarized lights S and P are separated by a birefringent material, and then one linearly polarized light is rotated by 90 ° by a phase difference plate to have the same polarization plane. Although it is emitted as polarized light, there is a problem that information on incident light, for example, light intensity, is separated because the emission position is different.

In the present invention, this inconvenience is solved by using a laminated polarization conversion element produced by laminating two transparent magnetic layers, and the usefulness of the optical element of the present invention as an optical lens is greatly improved. ing.
FIG. 7 shows a configuration of a laminated polarization conversion element useful in the present invention.
In the laminated polarization conversion element 30, the polarization conversion elements 12 are stacked in pairs on the top and bottom, and the oblique repeating layer structure of the periodic density of each element is equiangular with respect to the main surface of the substrate 11 and reverse. The two linearly polarized lights (Ee and Eo) separated in the direction of the element incident surface have a polarization plane angle difference of 90 ° when emitted from the element surface.

  Unlike the case where only one polarization conversion element 12 is used, when the polarization conversion elements 12 are overlapped in a pair in the upper and lower directions, the characteristic that the separated polarized light always overlaps with the linearly polarized light at the exit opening appears. As a result, information that incident light has, such as color information, density information, and gradation information of a color image, can be used without being separated. Care must be taken to avoid light scattering on each surface that joins the two layers. For example, lamination in a mirror state or continuous film formation is preferable. Further, the number of pairs of the polarization conversion elements 10 may be plural, and if the number is plural, the thickness of the polarization conversion elements 12 of each stacked layer can be reduced.

  Further, in the stacked polarization conversion element 30, planar smoothness is important for the interface where the polarization conversion elements 12 are superposed in pairs in order to reduce light scattering. As a means for eliminating this light scattering as much as possible, by providing a non-magnetic and transparent film 21 at the interface between the two polarization conversion elements 12, light scattering can be largely eliminated and light utilization efficiency can be improved. For the transparent nonmagnetic film 21, for example, the following inorganic materials and organic materials are appropriately used.

That is, as the inorganic substance, a transparent and thermally stable substance is suitable, for example, a metal or semi-metal oxide, nitride, chalcogenide, fluoride, carbide, and a mixture thereof, specifically SiO. ₂ , SiO, Al ₂ O ₃ , GeO ₂ , In ₂ O ₃ , Ta ₂ O ₅ , TeO ₂ , TiO ₂ , MoO ₃ , WO ₃ , ZrO ₂ , Si ₃ N ₄ , Si ₃ N ₄ , AlN, BN , TiN, ZnS, CdS, CdSe, ZnSe, ZnTe, AgF, PbF ₂ , MnF ₂ , NiF ₂ , SiC, and the like, or a mixture thereof.

  Organic substances include, for example, natural products such as oil and fat compounds, sugar compounds and peptide compounds, in-vivo materials such as enzymes and marine natural products, polymer compounds such as synthetic resins and elastomer compounds, colloidal compounds, and inclusion compounds. Examples include functional molecules. In particular, PVA (polyvinyl alcohol) is useful. The method of applying the transparent non-magnetic film 21 made of an organic material with a thickness of several μm is preferable because it can achieve the purpose of joining the pair of laminated films 12 each having a reverse gradient. The transparent magnetic film 21 preferably has a low refractive index. Moreover, although there is no restriction | limiting in particular in thickness, The thinner one is preferable and it is important to give the uniformity of a film thickness.

  An example of the overall configuration of the present invention using this polarization conversion element is shown in FIG.

In the optical element of the present invention, it is preferable that a transparent magnetic body having a concave or convex shape is provided in a depressed portion of the transparent support and used integrally (invention according to claim 7).
As shown in FIG. 6, after processing an uneven | corrugated shape on the transparent support body surface, a transparent magnetic body may be provided in a process site | part and a support body and a magnetic body may be integrated and used. In this case, the light transmission direction can be used in both the upper and lower directions in FIG.

A display device of the present invention is provided with the above-described optical element, a light source, and a drive circuit for a mechanism that magnetizes a transparent magnetic material (the invention according to claim 8).
As a preferred configuration example, after a plurality of optical elements are arranged as shown in FIG. 4A, a drive circuit (FIG. 9) for a mechanism (for example, a magnetic coil) that individually magnetizes the transparent magnetic bodies of the elements. The light from each light source (a white light source is preferable, but a plurality of laser light sources may be used. Reflected light having a different optical axis may be used) is individually transmitted or blocked (half-open). However, if the light from the light source is projected on the projection screen in an enlarged manner (which can be reduced), it can be used as a display device. In such a configuration, it is not necessary to separately provide a large lens system and a shutter as in the prior art, so that a compact configuration is possible and the usefulness is greatly enhanced. A color image can be easily obtained by providing RGB elements as a set for one pixel, and the shutter speed (opening / closing speed) is particularly high because the electron spin inversion is used as described above. It becomes. The screen is not essential, and a white part such as a wall surface can be used as appropriate.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
First, a laminated film composed of a titania nanosheet and a polymer was formed as follows.
Potassium carbonate (K ₂ CO ₃ ), titanium dioxide (TiO ₂ ), cobalt oxide (CoO), and iron oxide (Fe ₂ O ₃ ) are _mixed with K _0.8 Ti _1.5 Fe _0.2 Co _0.3 O ₄ . Weighing and mixing so as to obtain a molar ratio, followed by firing at 800 ° C. for 40 hours to synthesize magnetic element-substituted potassium titanate (K _0.8 Ti _1.5 Fe _0.2 Co _0.3 O ₄ ). The synthesized magnetic element-substituted potassium titanate was brought into contact with 1 g of powder at a rate of 100 cm ³ of 1N hydrochloric acid solution and allowed to react at room temperature with occasional stirring. The operation of replacing with a fresh hydrochloric acid solution every day was repeated three times, and then the solid phase was washed with filtered water and air-dried.
0.5 g of the obtained layered titanic acid powder (Ti _1.5 Fe _0.2 Co _0.3 O ₄ ) was added to 100 cm ³ of tetrabutylammonium hydroxide solution and shaken (150 rpm) at room temperature for 1 week to give a milky white color The titania sol was obtained.
In the _following, it represents the _{H 0.8 Ti 1.5 Fe 0.2 Co 0.3} O 4 · nH 2 O and CoFe simultaneous substitution nanosheet. A gelatin solution having a solid content of 20% by weight was mixed with this dispersion. This liquid is referred to as a CoFe simultaneous substitution nanosheet dispersion.
In the quartz glass hollowed out into a semicircular shape as shown in FIG. 6, first, after coating a silicon mold release agent, the above dispersion is put and dried, and the solid surface becomes the surface A in the figure. Repeat until.
The maximum thickness at the center of the semicircular transparent magnetic body was 5 mm, and the outer shape of the circle was 30 mm. The light passing direction with respect to the semicircular transparent magnetic material is up and down as indicated by arrows in the cross-sectional view in the figure. Quartz glass and transparent magnetic material were used as they were without separation. On the transparent magnetic material side, a protective film made of a transparent silicone resin was formed to a thickness of 5 μm.
Next, a nichrome-coated copper wire having an outer diameter of 30 μm was wound 300 times along the circumference of the semicircular transparent magnetic material from above the protective film to form a coil. The product of the thickness of the semicircular transparent magnetic material and the magnetic flux density by the coil was calculated so that all were the same on the light passage surface. The polarizer was placed in front of the semicircular transparent magnetic material and on the plane behind the semicircular transparent magnetic material. The polarizing axes of the polarizers were arranged in the same direction.
The light traveling from the right side to the left side in FIG. 3 passed through the polarizer and the transparent magnetic material (magnetic coil) and reached the screen.
Next, after magnetizing the transparent magnetic material by applying a direct current of 0.1 millisecond (1/10000 second) to the magnetic coil at 100 mA, no light on the screen was visible. This is because light that has been linearly polarized by the polarizer placed in front is transmitted through the transparent magnetic material and the plane of polarization is rotated by approximately 90 °, so that it cannot pass through the polarizer behind the semicircular transparent magnetic material. It is a result.

[Example 2]
A Tb ₃ Al ₅ O ₁₂ single crystal having a cubic garnet structure was produced by a floating zone method using a carbon dioxide gas laser having a wavelength of 10600 nm. Next, this paramagnetic single crystal was polished into a lens having a concave shape with a diameter of 3 mm.
Next, in the same manner as in Example 1, a coil was formed by winding a nichrome-coated copper wire having an outer diameter of 30 μm 50 times. The product of the thickness of the semicircular transparent magnetic material and the magnetic flux density by the coil was calculated so that all were the same on the light passage surface. The polarizer was placed in front of the semicircular transparent magnetic material and on the plane behind the semicircular transparent magnetic material. The polarizing axes of the polarizers were arranged in the same direction.
The light traveling from the right side to the left side in FIG. 3 passed through the polarizer and the transparent magnetic material (magnetic coil) and reached the screen.
Next, the light on the screen was not visible at all during the time when the transparent magnetic material was magnetized by applying a direct current of 0.1 millisecond (1/10000 second) to the magnetic coil at 100 mA. This is because the light that has been linearly polarized by the front polarizer passes through the polarizer on the back side of the semicircular transparent magnetic material as a result of passing through the magnetized transparent magnetic material and rotating the polarization plane by approximately 90 °. This is the result of being unable to.

Example 3
In the same manner as in Example 1, the following five types of CoFe simultaneous substitution nanosheets having different compositions were synthesized by changing the mixing amount of cobalt oxide and iron oxide.
1. Ti _1.50 Fe _0.2 Co _0.30 O ₄
2. Ti _1.48 Fe _0.2 Co _0.32 O ₄
3. Ti _1.46 Fe _0.2 Co _0.34 O ₄
4). Ti _1.44 Fe _0.2 Co _0.36 O ₄
5). Ti _1.42 Fe _0.2 Co _0.38 O ₄
The Faraday rotation angle measured for each nanosheet independently increased from 1 to 5 sequentially.
Next, after coating the mold release agent in the same quartz glass as in Example 1 hollowed out into a semicircular shape as shown in FIG. It repeated until it became the surface A point of. In this case, the thickness of the circular lens manufactured decreases as the distance from the central axis increases.
Therefore, since the Faraday rotation angle is proportional to the light passing distance, the drying order of the nanosheet dispersion liquid was changed from 1 to 5 in order so that the outer side becomes a material having a larger Faraday rotation angle. The Faraday rotation angle distribution of the manufactured optical element was within 3% at the maximum.
Next, an optical element was formed in the same manner as in Example 1, and after direct current was applied to the magnetic coil for 0.1 millisecond (1/10000 second) and 100 mA to magnetize the transparent magnetic material, the light on the screen was completely I couldn't see it. This is because light that has been linearly polarized by the polarizer placed in front is transmitted through the transparent magnetic material and the plane of polarization is rotated by approximately 90 °, so that it cannot pass through the polarizer behind the semicircular transparent magnetic material. It is a result.

Example 4
The optical element produced in Example 1 was regularly arranged two-dimensionally on a support as shown in FIG. 4 by the same method to form an optical element. The maximum thickness at the center of the semicircular transparent magnetic body was 0.5 mm, and the outer shape of the circle was 3 mm. The arrangement period of the elements was 4 mm in both the vertical and horizontal directions, and 100 elements were arranged in both the vertical and horizontal directions. Each element was provided with a magnetic coil as shown in FIG. 3, and each magnetic coil was individually provided with a capacitor and connected to an electric drive circuit. The drive circuit was selected so that an image could be appropriately formed from vertically and horizontally wired circuits, energized, and each optical element was individually driven to form a character image on the screen.

Example 5
Using the CoFe co-substituted titania nanosheet produced in Example 1, a polarization conversion element was produced in the following order.
After the surface was polished, the ends of the quartz glass plate coated with a release agent were combined to produce a U-shaped container. A small amount of the mixed dispersion was poured into this container. A 6 Tesla magnetic field was applied so as to be parallel to the nanosheet surface, dried slowly, then removed from the magnetic field and heated at 100 ° C. Further, the same method as described above was repeated thereon, and the nanosheets were laminated until the film thickness reached 52 μm. Thereafter, the quartz glass plate other than the quartz glass serving as the support was peeled off, and the laminated nanosheet was taken out of the container. The laminated nanosheet was transparent. When light having a wavelength of 450 nm was incident perpendicularly to the nanosheet surface, the Faraday rotation angle was 17 ° / μm. When a magnetic field is applied, the intensity of the primary peak (corresponding to the stacking cycle of the nanosheets. The diffraction angle is 4.7 °) indicating the maximum intensity in the X-ray diffraction diagram is compared with that when no magnetic field is applied. It was about 10 times, and the arrangement was improved. The Faraday rotation angle was also improved about 3 times.
Light having a wavelength of 450 nm was incident on the laminated nanosheet so as to be perpendicular to the quartz glass support. The separated polarized light was linearly polarized light, and the planes of polarization were perpendicular to each other. The separation angle was 25 °. Next, using an electromagnet capable of applying a magnetic field of 1 k Gauss, magnetization of the laminated nanosheet was performed perpendicular to the film surface. In the same manner as described above, light having a wavelength of 450 nm was incident. Only linear deflection deflected perpendicular to the nanosheet array was emitted.
In the same manner as described above, a laminated nanosheet having a thickness of 26 μm was produced. The laminated nanosheet and the laminated nanosheet prepared above were arranged so that the inclination of the obliquely repeating layer having a periodic density was reversed, and then bonded together using PVA (polyvinyl alcohol) before drying (FIG. 7). .
Light having a wavelength of 450 nm was incident so as to be perpendicular to the quartz glass support. The separated polarized light was linearly polarized light and the plane of polarization was perpendicular.
Magnetization of the laminated nanosheet was performed in the same manner as described above. Similarly to the above, light having a wavelength of 450 nm was incident so as to be perpendicular to the quartz glass support. The separated polarized light was linearly polarized light, the polarization plane was parallel, and the polarization was converted.
Next, in front of the optical element produced in Example 1, the polarization conversion film was arranged with the optical axis aligned. In the same manner as in Example 1, no light on the screen could be seen after the transparent magnetic material was magnetized by applying a direct current of 0.1 millisecond (1/10000) to the magnetic coil at 100 mA. This is because light that has been linearly polarized by the polarizer placed in front is transmitted through the transparent magnetic material and the plane of polarization is rotated by approximately 90 °, so that it cannot pass through the polarizer behind the semicircular transparent magnetic material. It is a result.

It is the schematic which shows the structure of the laminated film of a titania nanosheet and a polymer layer. It is a figure which shows the light absorbency of a titania nanosheet. It is a figure which shows the optical element of this invention. A transparent magnetic body is regularly arranged two-dimensionally on a transparent support, (a) is a plan view thereof, and (b) is a sectional view thereof. It is a figure for demonstrating the conventional polarization conversion element. A transparent magnetic body is provided at a processing site on the surface of the transparent support, wherein (a) is a plan view thereof and (b) is a cross-sectional view thereof. It is a figure for demonstrating the polarization conversion element useful for implementation of this invention. It is a figure of the optical element of this invention using a polarization conversion element. It is a figure which shows the drive circuit which magnetizes the transparent magnetic body of an optical element separately.

Explanation of symbols

11 Substrate 12 Polarization Conversion Element 30 Multilayer Polarization Conversion Element 21 Transparent Nonmagnetic Film

Claims (8)

  An optical element comprising a transparent magnetic body having a concave or convex surface at least, a mechanism for magnetizing the transparent magnetic body, and a polarizer in this order along an optical path. The transparent magnetic material has a chemical formula: Ti _{2 -X} M _X O ₄ (where M = V, Cr, Mn, Fe, Co, Ni, Cu, at least one transition metal, 0 <x <2) The optical element of Claim 1 containing the titania nanosheet represented by these.   3. The optical element according to claim 1, wherein the transparent magnetic body has a thickness that continuously changes, and a mechanism that magnetizes in accordance with the continuous thickness change has a magnetic field gradient. 4.   4. The optical element according to claim 2, wherein the transparent magnetic material has a reduced transition metal substitution amount in the titania nanosheet corresponding to a continuous increase in thickness.   The optical element according to claim 1, wherein the transparent magnetic body is provided as a regular two-dimensional array on a transparent support.   An optical element comprising a polarization conversion element arranged on the incident light side of the optical element according to claim 1.   The optical element according to claim 1, wherein the transparent magnetic body is provided in a depressed portion of the transparent support.   A display device comprising a light source and a drive circuit for a mechanism for magnetizing a transparent magnetic material in addition to the optical element according to claim 1.