JPH0453905A - Polarizing element and its manufacture - Google Patents

Abstract

PURPOSE:To stably form the twist nematic (TN) structure to a desired function by making thickness of a liquid crystal layer different in two areas divided by a straight line which passes through the center of a concentric circle and is roughly in parallel to the linear orientation direction. CONSTITUTION:Liquid crystal layers 24, are inserted and held by a transparent substrate 20A and 20B, and in the liquid crystal layer 24 belonging to an area A, and the liquid crystal layer 25 belonging to an area B in two areas A,B divided by a straight line L1 passing through the center 0 of a concentric circle, thickness of the liquid crystal layers is different by a step difference part 21. Accordingly, a TN liquid crystal layer structure in which a liquid crystal twist angle THETA on the periphery of the concentric circle is distributed continuously from THETA=-pi/2 to THETA=pi/2 in the areas A,B is obtained, and also, the liquid crystal layer 24 and the liquid crystal layer 25 have clear discontinuity by a variation ot thickness in an end face part(corresponding to the straight line L1) of the step difference part 21. In such a way, a discrimination comes to appear easily on the end face part (straight line L1) of the step difference part 21, therefore, a TN liquid crystal structure can be formed stably to a desired state.

Description

[Detailed Description of the Invention] Industrial Application Fields of the Invention Polarizing elements used in the field of optical equipment, particularly converting concentrically polarized light (or radial polarized light) into linearly polarized light, or converting linearly polarized light into concentrically polarized light (or radially polarized light). This invention relates to a converting polarizing element.

Conventional technology Conventional linear retarders such as quarter-wave plates and half-wave plates have been used in optical head devices as polarizing elements to convert the polarization state of light. 1-X, which converted uniformly over the entire surface, was mainly used for twisted nematic liquid crystals (hereinafter referred to as TN
1' with display devices using liquid crystal)! In optical integrated devices that combine optical waveguides, gratings, etc., there is a limit to miniaturization of pixels (currently about 100 to 200 μm square). , transform polarization states with spatially different distributions into homogeneous polarization states such as linear polarization within a small area.
Furthermore, there is an increasing demand for converting a homogeneous polarization state into a spatially distributed polarization state.

Special grade In the case of an optical integrated device that uses a concentric grating coupler to radiate guided light to the outside of the waveguide, it is necessary to convert the polarization state with a vibration plane in the tangential direction or radial direction of the concentric circles to a homogeneous polarization state. There has never been an element capable of achieving such polarization conversion in the past.Therefore, the present applicant proposed a polarizing element having the above function and an optical head device using the same in Japanese Patent Application No. 1-246808. This will hereinafter be referred to as a prior example, and an optical head device using a polarizing element in the prior example will be explained using FIG. 5@FIG.

In the configuration diagram of the optical head device in the prior example shown in FIG. 5, even though the transparent layer 2 with a low refractive index is formed on the Si substrate 1 and the transparent layers 3A and 3B with high refractive index are formed on it, it is still transparent. The layer 3A is circular tlL, and the layer 3B is annular surrounding 3A.On the surfaces of the transparent layers 3A and 3B, grating covers 4A and 4B are formed concentrically with respect to the center axis.
A transparent layer 3c with a high refractive index is formed on the surface of the transparent layer 3A with a transparent layer 5A with a low refractive index sandwiched therebetween.
Although a concentric grating cover 4C about the center axis is formed on the surface of the transparent layer 3C that contacts B and its grating cover 4B in the area facing the inner circumferential side, the surface of the transparent layer 3B has a low refractive index. A transparent layer 5B is formed, and the refractive index of the transparent layer 5B is equal to that of the transparent layer 5A, and L% Si
Photodetectors 6A and 6B are formed on the substrate 1 at positions corresponding to the discontinuities between the transparent layers 3 and 3B.
Even if the reflective film 7 is formed in the transparent layer 5A to cover the transparent layer 6B, even if the Si substrate 1 near the center axis is hollow, the linearly polarized light emitted from the semiconductor laser 8 is still reflected by the condenser lens 9. The light is focused and converted into light 11 having an electric field vector in the concentric tangential direction (or radial direction) by the retardation plate 19A and the polarizing element 10A.Then, the light 11 is input into the waveguide layer 3C by the concentric grating 4C. The guided light 12C of the TE mode (or 1M mode) propagates toward the outer circumferential direction inside the waveguide layer 3c. Tonamu waveguide light 12B is emitted by grating coupler 4B, and synchrotron radiation 13
If the guided light 12B is in the TE mode, the synchrotron radiation 13 becomes light in a polarization state in which the electric field vector points in the concentric tangential direction (hereinafter referred to as concentric circularly polarized light), and in the TM mode, the electric field vector points in the radial direction. The light is in a polarized state (hereinafter referred to as radiation polarization).

This concentric circularly polarized (or radiation polarized) light 131 becomes linearly polarized light after passing through the polarizing element 10B and the retardation plate 19B, and is focused on a point F on the reflective surface 16 of the optical disc 15. Light ζ, retardation plate 19 again
B and polarizing element 10B, the light becomes concentrically polarized light (or radiation polarized light), enters into waveguide layers 3A and 3B by grating couplers 4A and 4B, and propagates in the respective layers from the outer periphery toward the inner periphery. The guided lights 18A and 18B of the waveguide layers 3A and 3B are emitted from the outermost and innermost ends of the waveguide layers 3A and 3B, and are received by the photodetectors 6A and 6B, respectively. Next Place the polarizing element 10B and retardation plate 19B at the focal point F.
The effect produced by providing it between the grating coupler 4B and the grating coupler 4B will be explained using FIG. An example of a cross-sectional diagram of the light intensity distribution is shown, where (a) is concentrically polarized (or radial polarized) light, (b) is linearly polarized light, and as is clear from the comparison of (a) and (b). Concentric circularly polarized light (or radial polarized light) cannot achieve better light focusing than linearly polarized light. This is because the electric field vectors are opposite to each other at diagonal positions about the center of the concentric circle and cancel each other out at the focal point. Therefore, the polarizing element 10B and the retardation plate 19
If B is placed between the grating coupler 4B and the condensing point and the concentrically polarized light (or radial polarized light) is converted into completely linearly polarized light, high light convergence can be obtained.Reflected light 17 in Figure 5 is the grating coupler. 4A, 4B into the waveguides 3A, 3B. In order to obtain high input coupling efficiency (it is desirable that the polarization state of the reflected light and the emitted light be the same), the polarizing element 10B and the retardation plate 19B Converts reversibly between linearly polarized light and concentric circularly polarized light (or radial polarized light).The effect of increasing the input coupling efficiency of reflected light into the waveguide is also shown in Figure 7. The changes in the polarization state of light due to the element 10B and the retardation plate 19B are explained in the same figure (a)!, t,
The principle of polarization conversion by the polarizing element 10B is shown. The polarizing element 10B is composed of one TN liquid crystal layer, and one side (focusing point F side) of this TN liquid crystal layer has a unidirectional linear liquid crystal arrangement as shown by the solid line 40, and the other side (grating coupler 4B side)
is formed by aligning the liquid crystal in the tangential direction of the circle shown by the broken line 41. However, by performing such a simple liquid crystal alignment process, the distribution of the liquid crystal twist angle θ is continuously different at each position on the concentric circumference. It is possible to obtain a liquid crystal layer with a TN structure with
The twist angle θ is from θ=-π/2 to θ=0 and then θ=π/
2 (however, the counterclockwise twist on the paper is assumed to be a right-handed twist, and the twist angle is negative), (d)
Regarding each position from (ne) to (h), when linearly polarized light is incident on the liquid crystal layer of a similar TN structure,
The electric field vector of the light rotates along the twist of the TN structure. Therefore, the concentric circularly polarized light emitted from the grating coupler 4B (the electric field vector 42 indicated by the dashed arrow)
ζ The light rotates by almost the same angle as the twist angle of the liquid crystal at each position of the element and has an electric field vector in the direction of linear alignment of the liquid crystal layer (electric field vector 43 indicated by a solid line arrow). Two areas A divided by a straight line 44 passing through the center of the concentric circles and parallel to the straight line alignment direction,
Since the electric field vectors 43 are opposite to each other in regions A and B, the directions of the electric field vectors 43 are opposite to each other in regions A and B (that is, the phases are shifted by π).

FIG. 7(b) shows the phase compensation principle of the retardation plate 19B in the previous example. Even if the retardation plate 19B is configured on one side B of the area B, if the refractive index of the retardation plate 19B is n1, the thickness is d1, and the wavelength of the laser beam is λ, then the light on the side that passes through the retardation plate 19B is and the phase difference force (2π(rz−1)d) of the light on the non-transmitted side
So that it becomes +, that is, board d+ = (2k l)λ/2
If it is created to satisfy the relationship (n+-1) (k: natural number), it is possible to shift the phase of the light passing through regions A and B by π. Different electric field vector a
The phases of the lights (S, a) are aligned by passing through the retardation plate 19B\ Light with electric field vectors am and a having the same direction, that is, completely linearly polarized light.In this way, the polarizing element 10B By combining the and retardation plate 19B, the phase difference of the light passing through region 9B can be compensated and concentrically polarized light can be converted to linearly polarized light. Furthermore, these conversions are reversible, and linearly polarized light can be converted to concentrically polarized light. Conversion to polarized light can be performed in the same way, but the retardation plate 19A and polarizing element 1 in FIG.
0A has the same configuration as the above-mentioned retardation plate 19B and polarizing element 10B, and the linearly polarized light emitted from the semiconductor laser 8 can be converted into completely concentric circularly polarized light using the same principle. Problems As explained above, in order to achieve high light collection and high input coupling efficiency using a concentric grating coupler, a polarizing element that reversibly converts linearly polarized light to concentrically polarized light is required, and a patent application is filed. It is possible to realize this polarization conversion using the polarizing element proposed in 1991-246808.In order to further improve the polarization conversion performance of the polarizing element of the preceding example, there are the following issues. This is a diagram showing the twist angle distribution of the TN liquid crystal layer in the example polarizing element. In Figure 8, point 0 indicates the center of the circle of the above-mentioned concentric alignment, and arrow S indicates the alignment direction on the linear alignment side of the liquid crystal alignment surface. . If the liquid crystal alignment of the TN liquid crystal layer is ideally formed, the liquid crystal twist angle θ will be 0 on a straight line passing through the center of the concentric circles and orthogonal to the direction S, and the liquid crystal will be on a straight line at the azimuth angle α relative to point 0 in area A. Twist angle θ is θ
= α1, on the straight line of azimuth α- of region B, θ = α8 (however, both α4 and α8 assume that the clockwise direction is positive) In other words, in the straight line region BO in the direction of straight line S passing through point O Reciprocal twists (twist angles θ−π/2 and θ−−π/2)
A so-called disclination line occurs at the boundary line where the TN structures of
As shown in the figure, the disclination line should completely coincide with the straight line in the linear orientation direction passing through the center of the concentric circles (2). As shown in the figure, the disclination line 411 is generally attached to the straight line L4 in the linear orientation direction passing through the concentric center 0.
This is a disordered state. This is due to the fluidity of the liquid crystal when it is inhabited, the surface condition of the liquid crystal alignment surface, and the influence of the rotating substance contained in the twisted nematic liquid crystal material, causing the balance of elastic energy within the liquid crystal layer to collapse. When the disclination line 41 is disturbed in this way, an area (shaded area F) that is deviated from the end face of the retardation plate (corresponding to the straight line L4) is created. In this area, the polarizing element is converted. When the polarizing element is small, the influence of disturbance of this disclination line becomes large.4Means for Solving the ProblemsThe present invention provides a polarizing element and a polarizing element that solves the above-mentioned problems. The present invention provides a method for manufacturing the same, and uses the following means to create a twisted plate between the liquid crystal alignment surfaces in which one of the liquid crystal alignment surfaces is aligned in a straight direction and the other is aligned in a tangential direction of a concentric circle.
In a polarizing element having a nematic liquid crystal layer, the thickness of the liquid crystal layer is made to differ between two regions divided by a straight line passing through the center of concentric circles and approximately parallel to the linear alignment direction (on the liquid crystal alignment surface in the linear direction). A concave portion or a convex portion is provided in a linear region passing through the center of the concentric circles and substantially parallel to the linear direction, and the thickness of the liquid crystal layer is configured to change on a straight line passing through the center of the concentric circles and substantially parallel to the linear alignment direction. 4 Alternatively, the angles of the linear alignment direction may be made different in two areas of the liquid crystal layer separated by a straight line passing through the center of the concentric circle and approximately parallel to the linear alignment direction.Alternatively, one of the liquid crystal alignment planes may be aligned in the linear direction and the other in the concentric circle tangential direction. In manufacturing a polarizing element in which a twisted nematic liquid crystal layer is provided between two treated transparent substrates, a resistor in which a liquid crystal is sealed between the two transparent substrates is used.
By applying a heat treatment to heat the liquid crystal to near the N-I point and then cooling it, one of the two transparent substrates having a transparent conductive film on the surface is applied in a straight direction and the other in the tangential direction of a concentric circle. After alignment treatment, a twisted nematic liquid crystal layer is provided between the two transparent substrates, and then a voltage is applied to the liquid crystal layer.

Effect: According to the above configuration, the position of the disclination line can be stably created on a straight line passing through the center of the concentric circles and approximately parallel to the straight line alignment direction, so that the liquid crystal alignment of the TN liquid crystal layer is good and polarization conversion is possible. Embodiments in which a polarizing element with high performance can be obtained An embodiment of a polarizing element according to the present invention will be explained with reference to FIGS. % Although detailed explanation will be omitted, FIG. 1 shows a polarizing element according to an embodiment of the present invention in a plan view and a cross-sectional configuration diagram. In the figure, even if a transparent stepped portion 21 is provided on the inner surface of the transparent substrate 20A by etching or the like, the transparent substrate 20A and the stepped portion 21, and the surface of the transparent substrate 20B are provided with a liquid crystal for aligning the liquid crystal. Alignment films 22 and 23 are formed respectively, and the surface of 22 has a linear orientation in the direction of arrow 26 parallel to the step boundary line L+, and the surface of 23 has a concentric circle tangential direction centered on point 0 on Li (broken line). As described above, the liquid crystal layers 24 and 25 are sandwiched between the two transparent substrates 20A and 20B, and are divided into two areas A that pass through the concentric center 0 and are separated by the straight line L1. , B. Even if the liquid crystal layer 24 belonging to area A and the liquid crystal layer 25 belonging to area B of Gi Liquid crystal twist angle θ PA Area 9 B, respectively θ
A TN liquid crystal layer structure continuously distributed from = -π/2 to θ = π/2 is obtained. Therefore, disclination tends to appear on the end face (straight line L+) of the stepped portion 21, which makes it difficult for the TN liquid crystal structure to be stably formed in the desired state. In addition, the light transmitted through the liquid crystal layer 24 and 25 in the polarizing element of this example is the same as in the previous example.The optical path of the light transmitted through the liquid crystal layer 24 and 25 is the same as in the previous example. The lengths are different 6 A, 8
However, as in the optical head device in the previous example, the linear alignment direction is made to match both the input grating cover 4C and the laser light source 8 and the output grating cover 4B and the condensing point F. If the phase difference plates 19A and 1 are arranged as shown in FIG.
9B can be omitted.Next, we will consider the case where the polarizing element shown in FIG. 1 is used to convert completely concentric circularly polarized light to linearly polarized light, similar to the combination of polarizing element 10B and retardation plate 19B in the previous example. −, when linearly polarized light with an electric field vector parallel or orthogonal to the input side liquid crystal molecular axis is incident on the TN liquid crystal layer, and linearly polarized light with an electric field vector parallel or orthogonal to the output side molecular axis is output. Twist angle θ and wavelength of light Relationship with λ1i
Gooch-Tarry formula (C9H, Go.

ch and HoA, Tarry, 'The o
physical property of twist
d nematic 1quid crystal
5 structures with twist a
ngles<90°', App1, Phys,,V
o1, 8, 1975. reference. ) yo ri, θ(1+(πdΔnbaθλ))” ]' “2kyr
(k; integer) (1) In the formula L (1), 80 represents the refractive index difference of the liquid crystal, and d represents the thickness of the liquid crystal layer.

By transforming equation (1), it can be expressed as equation (2), where λ−
Δnd(4k"-θ"/rr")-""
...(2) From equation (2), λ is θ=0 for θ
Draw a downward convex curve with the minimum value.

-X The polarizing element of the present invention has a twist angle θ balance of the liquid crystal layer.
It is continuously distributed in the range of −π/2≦θ≦π/2.When 〇=0, λ is the minimum value (=λ weight), θ=Sat π/2
When λ has a maximum value (=λa), therefore, if the wavelength of the light source used is λ, the Δnd value of the liquid crystal layer should be set so as to satisfy the relationship λ1≦λ≦λimaginary. When plate θ = 0, (1) 2C Δnd (2k) -'-λ (-λ+) (k: natural number) --- (3) When θ = π/2, equation (1) becomes △nd ( 4k"-174)-""-λ (-λ2)
--- (4) (k: natural number), so good polarization conversion can be achieved by satisfying the condition of equation (5) below (4k"-1/4)"'≦Δnd/λ≦ 2k
-.(5) (k: natural number) The above is the conclusion of the liquid crystal layer 24 of the polarizing element shown in FIG.
25 strength lengths (6) each! It is desirable that the formula (7) is satisfied, but (16+”-1)””≦2△nch/λ≦4+
---(a) (kB natural number) (18 to 2"-1)""≦2△nds/λ≦4 to 2" (
7) (k2; natural number) Furthermore, in order to give the transparent stepped portion 21 the function of the retardation plate 19B of the previous example, if the refractive index of the retardation plate 19B is λ and the wavelength of the laser beam is λ, then the laser beam passes through the stepped portion 21. Phase difference force between the light on the side and the light on the non-transparent side (2yr(n+-n
o) Is ld+-dal or is (n+-no)ld
+ -d21 = (2kg -1)λ/2 ・-(
8) If it is created to satisfy the relationship (k3: natural number), it is possible to convert the light passing through areas A and B into completely concentric circularly polarized light and linearly polarized light with the same phase. It is a cross-sectional configuration diagram of a polarizing element that is another example, and as shown in the figure, a substrate 20A on the linear alignment side of the liquid crystal alignment surface of two transparent substrates 20A (linear alignment side) and 20B (concentric alignment side). Even if a linear concave portion 50 or a linear convex portion 51 is provided on the top in the linear alignment direction passing through the center of the concentric circle, the thickness of the liquid crystal layer 52 is changed by the concave portion 50 or the convex portion 51 due to such a configuration. Although the disclination scene line is stabilized along the concave portion 50 or the convex portion 51, FIG. Even if an organic alignment film such as the above is applied using a spin cord or the like, the substrate 31 is rubbed with a nylon cloth or the like to align it in the linear direction. 30, rub in the Pb direction that is inclined by about 2 to 3 degrees (clockwise in the figure is positive) with respect to the linear end surface L2 of the thin plate 30. Next, apply the rubbed area to the thin plate 30. Cover (X area B with straight line L
Rubbing is performed in a direction P- which is approximately -2 to -3 (deg) similar to that of 2.

When bonding this Hiro substrate 31 to another substrate oriented in the tangential direction of the concentric circles, alignment is made so that the boundary between area A and area B intersects with the center axis of the concentric circle, and the liquid crystal material is bonded via a sealing material. By performing such an alignment treatment on the linearly aligned surface, a disclination line can be stably formed on the straight line Le since the orientation of liquid crystal molecules near the linearly aligned surface is discontinuous in the region on the straight line L2. For the polarizing element of the previous example, by devising the manufacturing method, it was possible to create a stable position of the disclination line. Figure 4 shows the N-I of the liquid crystal material This figure shows the change in the disclination line when the liquid crystal is heated to a point (the temperature at which the optical anisotropy of the liquid crystal disappears) and then slowly cooled. Figure (a) shows the state before heating. Figure (b) shows the state after heating. By heating and slowly cooling the device as shown in the figure, the imbalance in the elastic energy of the liquid crystal layer caused by the fluidity during liquid crystal injection and the surface of the liquid crystal alignment surface is released, and the liquid crystal is rearranged to the desired state. It is also possible to create a polarizing element by providing a transparent conductive film such as ITO on transparent substrates that sandwich a liquid crystal layer.A voltage is applied to the liquid crystal layer once or several times using this transparent conductive film. In particular, due to the rearrangement of the liquid crystal, the straight line L as shown in Figure 4
Effects of the Invention According to the present invention, it is possible to eliminate the instability of the position of the disclination line and create a polarizing element with the liquid crystal twist angle more stable at a predetermined position. Because you can
A polarizing element with high polarization conversion performance between concentric circularly polarized light and linearly polarized light has been realized, and its effect is extremely large (t

[Brief explanation of drawings]

FIG. 3 shows a process explanation showing an orientation method in another embodiment. FIG. 4 shows a change in the disclination line in an embodiment of the method for manufacturing a polarizing element of the present invention. FIG. Figure 6 shows the light intensity distribution at the condensing position of the optical head device shown in Figure 5. Figure 7 shows the polarization conversion performance of the polarizing element in the previous example. Figure 8 shows the liquid crystal twist angle distribution l of the polarizing element of the previous example. Figure 9 shows the variation of the disclination line.■...Si substrate 2...Transparent #3A with low refractive index,
3B, 3C...High refractive index transparent [4A, 4B, 4C...
・Grating coupler, L...center $111
5A, 5B, 5C...low refractive index transparent W/L 6A,
6B...Photodetection bolt 7...Reflected wind 8...Semiconductor laser, 9...Condensing lens, CIOA, 10&
...Polarizing element, 11...Input source 12C, 18A
, 18B... Guided light 13... Synchrotron radiation 16...
Optical disk reflective surface 17A, 17B...reflection 119A
, 19B... Retardation plate 21... Transparent stepped portion 24
, 25...Liquid crystal layer 26.27...Liquid crystal alignment direction
50...Straight concave vein 51...Straight line 5Kon Name of agent Patent attorney Shigetaka Awano 1 person Figure 1 XIA 8 n, 23 N, 25 To, 27 r i! 1111 Close-up part Tilt crystal orientation- Obscure crystal layer diagonal crystal arrangement 11 squares 1911Q sacrifice- Figure Figure 2-* Dencho drawing axis (riichi) (μm) - (ritsu axis) (μm) Fig.

Claims (6)

[Claims] (1) A polarizing element having a twisted nematic liquid crystal layer between a pair of liquid crystal alignment surfaces, one of which is aligned in a linear direction and the other aligned in a tangential direction of a concentric circle, wherein the straight line passes through the center of the concentric circle. A polarizing element characterized in that a liquid crystal layer has a different thickness in two regions separated by a straight line substantially parallel to the direction. (2) By arranging a transparent stepped portion adjacent to the liquid crystal layer in one of the two regions, the thickness of the liquid crystal layer between the two regions is made different, and the refractive index of the transparent stepped portion is set to n, The refractive index anisotropy of the twisted nematic liquid crystal layer is expressed as Δn (=n
___o−n_o), the thickness of the liquid crystal layer in the two regions is d_
1, d_2, and the wavelength of light is λ, these values are (16k_1^2-1)^1^/^≦2Δnd_1/λ
≦4k_1 and (16k_2^2-1)^1^/^2≦2Δnd_2/
λ≦4k_2 and |n−n_o||d_2−d_1|=(2k_3−1)
λ/2 (or |n-n_o||d_2-d_1|=(
2k_3-1)λ/2)(k_1, k_2, k_3; natural numbers) The polarizing element according to claim 1, wherein the polarizing element satisfies the following relationship. (3) A polarizing element having a twisted nematic liquid crystal layer between a pair of liquid crystal alignment surfaces, one of which is oriented in a linear direction and the other in a tangential direction of a concentric circle, with the center of the concentric circle on the linear alignment surface. A polarizing element characterized in that a linear concave portion or convex portion is formed passing through the linear alignment direction and substantially parallel to the linear alignment direction. (4) A polarizing element having a twisted nematic liquid crystal layer between a pair of liquid crystal alignment surfaces in which one of the liquid crystal alignment surfaces is aligned in a linear direction and the other is aligned in a tangential direction of a concentric circle, wherein the straight line passes through the center of the concentric circle. A polarizing element characterized in that two regions of a liquid crystal layer separated by a straight line substantially parallel to the direction have different linear alignment directions. (5) A method for manufacturing a polarizing element, in which a twisted nematic liquid crystal layer is provided between two transparent substrates that have been subjected to alignment treatment in a linear direction on one of a pair of liquid crystal alignment surfaces and in a concentric tangential direction on the other. A method for manufacturing a polarizing element, comprising: sealing a liquid crystal between the two transparent substrates, and then subjecting the liquid crystal to heat treatment in which the liquid crystal is heated to near the N-I point and then cooled. (6) After performing alignment treatment on one of two transparent substrates having a transparent conductive film on the surface in a linear direction and in a concentric tangential direction on the other, a twisted nematic liquid crystal layer is placed between the two transparent substrates. A method for manufacturing a polarizing element, comprising: sealing a liquid crystal between the two transparent substrates, and then applying a voltage to the liquid crystal layer to rearrange the liquid crystal. Method of manufacturing elements.