JP2022075485A - Liquid crystal optical element - Google Patents

Abstract

To provide a liquid crystal optical element capable of mass production.SOLUTION: A liquid crystal optical element according to an embodiment includes a substrate including a first main surface. a plurality of structures disposed on the first main surface and arranged at predetermined pitches, and a liquid crystal layer surrounding each of the structures and disposed in contact with the first main surface between the adjacent structures. The thickness of the liquid crystal layer is larger than that of the structure. The liquid crystal layer includes liquid crystal molecules arranged along the structure and is cured with the liquid crystal molecules oriented in a fixed direction.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to liquid crystal optical elements.

For example, a liquid crystal polarizing lattice using a liquid crystal material has been proposed. Such a liquid crystal polarizing grid divides the incident light into 0th-order diffracted light and 1st-order diffracted light when light having a wavelength λ is incident. When realizing such a liquid crystal polarizing grid, it is required to increase the productivity.

Special Table 2017-522601 Gazette

An object of the present embodiment is to provide a liquid crystal optical element capable of mass production.

The liquid crystal optical element of this embodiment is
A substrate having a first main surface, a plurality of structures arranged on the first main surface and arranged at a predetermined pitch, and the first main surface surrounding each of the structures and adjacent to each other. A liquid crystal layer in contact with a surface is provided, the thickness of the liquid crystal layer is larger than the thickness of the structure, the liquid crystal layer has liquid crystal molecules arranged along the structure, and the orientation of the liquid crystal molecules is provided. It is cured in a fixed direction.

FIG. 1 is a cross-sectional view schematically showing a liquid crystal optical element 1 according to the present embodiment. FIG. 2 is a plan view for explaining the orientation direction of the first liquid crystal molecule LM1 in the vicinity of the first main surface F1 of the liquid crystal optical element 1 shown in FIG. FIG. 3 is a diagram for explaining an example of a method for manufacturing the liquid crystal optical element 1 shown in FIG. FIG. 4 is a cross-sectional view schematically showing a first configuration example of the liquid crystal optical element 1. FIG. 5 is a cross-sectional view schematically showing a second configuration example of the liquid crystal optical element 1. FIG. 6 is a plan view schematically showing an example of the orientation pattern in the liquid crystal layer LC. FIG. 7 is a plan view showing the first layout of the structure 20. FIG. 8 is a plan view showing the second layout of the structure 20. FIG. 9 is a plan view showing a third layout of the structure 20. FIG. 10 is a plan view showing a fourth layout of the structure 20. FIG. 11 is a plan view showing a fifth layout of the structure 20. FIG. 12 is a plan view showing a modification 1. FIG. 13 is a plan view showing a modification 2. FIG. 14 is a plan view showing a modification 3. FIG. 15 is a plan view showing a modified example 4. FIG. 16 is a plan view showing a sixth layout of the structure 20. FIG. 17 is a plan view showing a modification 5. FIG. 18 is a plan view showing a modification 6. FIG. 19 is a plan view showing a modification 7. FIG. 20 is a plan view showing a modification 8.

Hereinafter, this embodiment will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention, which are naturally included in the scope of the present invention. Further, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment, but the drawings are merely examples and are merely examples of the present invention. It does not limit the interpretation. Further, in the present specification and each figure, the same reference reference numerals may be given to the components exhibiting the same or similar functions as those described above with respect to the above-mentioned figures, and the overlapping detailed description may be omitted as appropriate. ..

In the drawings, the X-axis, the Y-axis, and the Z-axis, which are orthogonal to each other, are described as necessary for facilitating understanding. The direction along the X axis is referred to as the X direction or the first direction, the direction along the Y axis is referred to as the Y direction or the second direction, and the direction along the Z axis is referred to as the Z direction or the third direction. The plane defined by the X-axis and the Y-axis is referred to as an XY plane, and the plane defined by the X-axis and the Z-axis is referred to as an XY plane. Looking at the XY plane is called plan view.

FIG. 1 is a cross-sectional view schematically showing a liquid crystal optical element 1 according to the present embodiment. The liquid crystal optical element 1 includes a substrate 10, a plurality of structures 20, and a liquid crystal layer LC.

The substrate 10 is a transparent substrate that transmits light, and is composed of, for example, a transparent glass plate or a transparent synthetic resin plate. The substrate 10 may be made of, for example, a flexible transparent synthetic resin plate. The substrate 10 can take any shape. For example, the substrate 10 may be curved. The refractive index of the substrate 10 is, for example, larger than the refractive index of air.

As used herein, "light" includes visible and invisible light. For example, the lower limit wavelength of the visible light region is 360 nm or more and 400 nm or less, and the upper limit wavelength of the visible light region is 760 nm or more and 830 nm or less. Visible light has a first component (blue component) in the first wavelength band (for example, 400 nm to 500 nm), a second component (green component) in the second wavelength band (for example, 500 nm to 600 nm), and a third wavelength band (for example). It contains a third component (red component) of 600 nm to 700 nm). The invisible light includes ultraviolet rays in a wavelength band shorter than the first wavelength band and infrared rays in a wavelength band longer than the third wavelength band.
In the present specification, "transparent" is preferably colorless and transparent. However, "transparent" may be translucent or colored transparent.

The substrate 10 is formed in a flat plate shape along an XY plane, and has a first main surface F1 and a second main surface F2. The first main surface F1 and the second main surface F2 are planes substantially parallel to the XY plane and face each other in the Z direction. The second main surface F2 is in contact with air, for example, but may be covered with another thin film.

The plurality of structures 20 are arranged on the first main surface F1 and are arranged along the X direction at a predetermined first pitch P1. The structure 20 here is a convex body extending in the Z direction from the first main surface F1. As will be described in detail later, such a plurality of structures 20 have a function of defining the orientation direction of the liquid crystal molecules contained in the liquid crystal layer LC. Each of the structures 20 is in contact with the first main surface F1, but another thin film may be interposed between the structure 20 and the first main surface F1. The structure 20 is formed of, for example, an organic material, but may be formed of an inorganic material.

The structure 20 has a cross-sectional shape that tapers along the Z direction in the XZ plane. That is, the structure 20 has a bottom portion 20B in contact with the first main surface F1 and a top portion 20T on the opposite side of the bottom portion 20B, and the width WB of the bottom portion 20B along the X direction is larger than the width WT of the top portion 20T. big. In the example shown in FIG. 1, the first main surface F1 is exposed between the adjacent bottom portions 20B. However, the first main surface F1 between the adjacent bottom portions 20B may be covered with a thin film.
Further, the structure 20 has a side surface 20S between the bottom portion 20B and the top portion 20T. The side surfaces 20S face each other in the X direction. Each of the side surfaces 20S is an inclined surface inclined with respect to the Z direction.

In the configuration example in which the structure 20 is in contact with the substrate 10, the refractive index of the structure 20 is equivalent to the refractive index of the substrate 10. Therefore, the light that reaches the interface between the substrate 10 and the structure 20 is hardly refracted.

Each of the structures 20 has a substantially constant thickness D20 along the Z direction from the first main surface F1. The thickness D20 of the structure 20 is larger than the width WB of the bottom 20B. In one example, the thickness D20 is 100 nm to 2000 nm, preferably 300 nm to 1000 nm. The width WB is, for example, 50 nm to 1500 nm, preferably 100 nm to 1000 nm. The ratio of width WB to thickness D20 (WB / D20) is less than 1 and greater than 0.1.

It is desirable that the angle θ formed by the side surface 20S of the structure 20 and the bottom portion 20B is smaller than 90 degrees. In one example, the angle θ is 65 ° to 88 °, preferably 75 ° to 85 °.

The liquid crystal layer LC surrounds each of the structures 20 and is in contact with the top portion 20T and the side surface 20S. Moreover, in the example shown in FIG. 1, the liquid crystal layer LC is in contact with the first main surface F1 between the adjacent structures 20. The liquid crystal layer LC has a thickness DLC along the Z direction from the first main surface F1. The thickness DLC of the liquid crystal layer LC is larger than the thickness D20 of the structure 20. In one example, the thickness DLC is 1000 nm to 14000 nm, preferably 5000 nm to 12000 nm. The thickness D20 is as described above. The ratio of thickness D20 to thickness DLC (D20 / DLC) is less than 1 and greater than 0.01. Desirably, the ratio (D20 / DLC) is less than 1 and greater than 0.04.
The thickness DLC of the liquid crystal layer LC described here corresponds to the thickness when the liquid crystal layer LC is a single layer. The liquid crystal layer LC may be a multilayer body in which a plurality of layers are laminated.

The distance L between the bottoms 20B of the adjacent structures 20 along the X direction is smaller than the thickness DLC of the liquid crystal layer LC. In one example, the distance L is 50 nm to 1500 nm, preferably 100 nm to 1000 nm. The thickness DLC is as described above. The ratio of distance L to thickness DLC (L / DLC) is less than 1 and greater than 0.007. Desirably, the ratio (L / DLC) is less than 0.2 and greater than 0.014.

Further, the distance L is equal to or smaller than the thickness D20. In one example, the ratio of distance L to thickness D20 (L / D20) is 1 or less, greater than 0.3. From the viewpoint of defining the orientation direction of the liquid crystal molecules, it is desirable that the distance L is small and that the thickness D20 is large. However, considering the productivity when the structure 20 is formed by the manufacturing method using a mold described later, it is desirable that the distance L is large and the thickness D20 is small.

In the example shown in FIG. 1, no other thin film or substrate is overlapped on the liquid crystal layer LC in the Z direction. That is, the liquid crystal layer LC has a main surface F3 in contact with air. The main surface F3 may be covered with another thin film such as a protective film.

The liquid crystal layer LC has a plurality of liquid crystal structures LMS. The liquid crystal structure LMS has a first liquid crystal molecule LM1 located on one end side thereof and a second liquid crystal molecule LM2 located on the other end side. The first liquid crystal molecule LM1 is close to the first main surface F1, and the second liquid crystal molecule LM2 is close to the main surface F3.
Each first liquid crystal molecule LM1 of the liquid crystal structure LMS is located between the structures 20 adjacent to each other in the X direction. Each second liquid crystal molecule LM2 of the liquid crystal structure LMS is located above the structure 20 along the Z direction. The liquid crystal structure LMS is also located above the structure 20.

The orientation direction of the first liquid crystal molecule LM1 is defined by the adjacent structure 20. The relationship between the orientation direction and the structure 20 will be described later with reference to FIG. Each liquid crystal structure LMS can be regarded as a continuum in which a plurality of liquid crystal molecules including the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 are arranged in the Z direction. Therefore, since the orientation direction of the first liquid crystal molecule LM1 is defined by the structure 20, the orientation direction of the plurality of liquid crystal molecules arranged in the Z direction including the second liquid crystal molecule LM2 is the orientation of the first liquid crystal molecule LM1. It is specified according to the direction. As a result, the plurality of liquid crystal molecules including the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 in each liquid crystal structure LMS are respectively oriented in a predetermined direction in the XY plane.

The liquid crystal layer LC of the present embodiment is cured in a state where the orientation direction of the liquid crystal molecules including the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 is fixed. That is, the orientation direction of the liquid crystal molecules is not controlled according to the electric field. Therefore, the liquid crystal optical element 1 does not have an electrode for orientation control. Such a liquid crystal layer LC is formed, for example, by applying energy such as light to a monomer to polymerize it.

FIG. 2 is a plan view for explaining the orientation direction of the first liquid crystal molecule LM1 in the vicinity of the first main surface F1 of the liquid crystal optical element 1 shown in FIG. FIG. 1 corresponds to a cross-sectional view of the liquid crystal optical element 1 along the line AB shown in FIG.

The plurality of structures 20 are formed so as to have substantially the same shape in a plan view, and each is curved. The plurality of structures 20 are arranged at intervals along the X direction. The first liquid crystal molecule LM1 between the structures 20 adjacent to each other in the X direction is cured with its major axis LX oriented along the tangent TL of the structure 20. The tangent line TL here is, for example, a tangent line tangent to the outer edge of the bottom portion 20B of the structure 20.

FIG. 3 is a diagram for explaining an example of a method for manufacturing the liquid crystal optical element 1 shown in FIG.

First, in step ST1, the transparent structure material 20M is applied to the first main surface F1 of the substrate 10 and the solvent is removed to form a state in which the structure material 20M is temporarily cured. Here, an ultraviolet curable resin can be applied as the structure material 20M.

Subsequently, in step ST2, a mold MD in which recesses corresponding to the shape of the structure 20 are formed in advance is prepared, the mold MD is superposed on the structure material 20M, and ultraviolet rays are irradiated while pressurizing. As a result, the structure material 20M is cured into a shape corresponding to the concave portion of the mold MD, and the structure 20 is formed. After that, the mold MD is removed.
In the example shown in FIG. 3, the convex portion CV of the mold MD is in contact with the first main surface F1 and is irradiated with ultraviolet rays. Therefore, the formed structures 20 are separated from each other, and the first main surface F1 between the structures 20 is exposed.
When the mold MD is pressurized, ultraviolet rays may be irradiated with the structure material 20M interposed between the convex portion CV and the first main surface F1. In this case, the first main surface F1 between the structures 20 is covered with a thin film made of the same material as the structure 20.

Subsequently, in step ST3, the liquid crystal layer LC is formed on the substrate 10. The liquid crystal layer LC is formed, for example, as follows. First, the liquid crystal material is applied so as to be in contact with the first main surface F1 and the structure 20. Then, the liquid crystal material is cured by irradiating it with light such as ultraviolet rays to form a liquid crystal layer LC.

However, before the liquid crystal material is cured, the orientation direction of the liquid crystal molecules contained in the liquid crystal material is fixed as follows. That is, the first liquid crystal molecule LM1 close to the first main surface F1 is horizontally oriented along the XY plane between the adjacent structures 20, and the long axis is along the tangent line of the structure 20. Oriented to. The orientation direction of the liquid crystal molecule (including the second liquid crystal molecule LM2) LM overlapping in the Z direction with respect to the first liquid crystal molecule LM1 is determined according to the orientation direction of the first liquid crystal molecule LM1. The liquid crystal molecule LM located above the structure 20 is oriented following the liquid crystal molecule LM around the liquid crystal molecule LM.

In the example shown in FIG. 3, the orientation direction of the liquid crystal molecule LM overlapping the first liquid crystal molecule LM1 is almost the same as the orientation direction of the first liquid crystal molecule LM1, but when the chiral agent is added to the liquid crystal material. In, a plurality of liquid crystal molecules LM are swirled and overlapped in the Z direction starting from the first liquid crystal molecule LM1.
In this way, the liquid crystal material is cured after the orientation direction of each liquid crystal molecule LM is fixed according to the orientation direction of the first liquid crystal molecule LM1.

According to this embodiment, the minute structure 20 can be easily formed by using the mold MD having minute irregularities on the order of wavelength. Such a structure 20 has a function of defining the orientation direction of the liquid crystal molecules contained in the liquid crystal material when the liquid crystal material is applied. The pattern of the structure 20 is formed so that the liquid crystal molecule LM forms a desired orientation pattern. Therefore, the liquid crystal material is cured in a state where the orientation direction of each liquid crystal molecule is fixed in a predetermined direction, and a liquid crystal layer LC having a predetermined retardation is formed. Therefore, the liquid crystal optical element 1 having desired optical characteristics can be mass-produced.

As an example, when a liquid crystal optical element 1 was prototyped with a width WB of the structure 20 of 150 nm, a distance L of 300 nm, and a thickness D20 of 300 nm, a liquid crystal layer LC having liquid crystal molecules oriented in a predetermined direction was produced. Was formed, and it was confirmed that the desired retardation could be obtained.

Next, a specific configuration example of the liquid crystal optical element 1 according to the present embodiment will be described.

(First configuration example)
FIG. 4 is a cross-sectional view schematically showing a first configuration example of the liquid crystal optical element 1. FIG. 4 corresponds to a cross-sectional view of the liquid crystal optical element 1 along the CD line shown in FIG. The first configuration example corresponds to an example in which the liquid crystal optical element 1 functions as a transmission type diffraction grating. The liquid crystal layer LC has a nematic liquid crystal in which the orientation directions are aligned. The orientation direction of the plurality of first liquid crystal molecules LM1 arranged along the first main surface F1 continuously changes along the Y direction.
When the liquid crystal layer LC is a multilayer body as described above, it may be a nematic liquid crystal in which a part of the liquid crystal layer LC is twist-oriented.

The refractive index anisotropy or birefringence of the liquid crystal layer LC is Δn (difference between the refractive index ne for abnormal light of the liquid crystal molecule and the refractive index no for normal light), the thickness of the liquid crystal layer LC is DLC, and the diffracted light. When the wavelength is λ, it is desirable that the refractive index Δn · DLC of the liquid crystal layer LC is λ / 2.

Focusing on one liquid crystal structure LMS, the orientation direction of the first liquid crystal molecule LM1 and the orientation direction of the second liquid crystal molecule LM2 are almost the same. Further, the orientation direction of the other liquid crystal molecules LM between the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 is also substantially the same as the orientation direction of the first liquid crystal molecule LM1.

Light may be incident on the liquid crystal optical element 1 from the side of the liquid crystal layer LC, or light may be incident on the liquid crystal optical element 1 from the side of the substrate 10. Here, a case where light is incident from the side of the liquid crystal layer LC will be described. The incident light LTI is divided into the 0th-order diffracted light LT0 and the 1st-order diffracted light LT1 after passing through the liquid crystal optical element 1. The diffraction angle θd0 of the 0th-order diffracted light LT0 is equivalent to the incident angle θi of the incident light LTi. The diffraction angle θd1 of the primary diffracted light LT1 is different from the incident angle θi.

(Second configuration example)
FIG. 5 is a cross-sectional view schematically showing a second configuration example of the liquid crystal optical element 1. FIG. 5 corresponds to a cross-sectional view of the liquid crystal optical element 1 along the CD line shown in FIG. The second configuration example corresponds to an example in which the liquid crystal optical element 1 functions as a reflection type diffraction grating. The liquid crystal layer LC has a cholesteric liquid crystal. In addition, in FIG. 5, for simplification of the drawing, one liquid crystal molecule LM is shown as a representative of the liquid crystal molecules oriented in the average orientation direction among the plurality of liquid crystal molecules located in the XY plane. ing. The orientation direction of the plurality of first liquid crystal molecules LM1 arranged along the first main surface F1 continuously changes along the Y direction.

Focusing on one liquid crystal structure LMS, a plurality of liquid crystal molecules LM are spirally stacked along the Z direction while swirling. The orientation direction of the first liquid crystal molecule LM1 and the orientation direction of the second liquid crystal molecule LM2 are almost the same. The liquid crystal structure LMS has a spiral pitch P. The spiral pitch P indicates one cycle (360 degrees) of the spiral.

The liquid crystal layer LC has a plurality of reflecting surfaces 13 as shown by the alternate long and short dash line. In one example, the plurality of reflective surfaces 13 are substantially parallel to each other. The reflective surface 13 is inclined with respect to the first main surface F1 and has a substantially planar shape extending in a certain direction. According to Bragg's law, the reflecting surface 13 selectively reflects a part of the incident light LTi of the incident light LTt and transmits the other light LTt. The reflecting surface 13 reflects the light LTr according to the inclination angle φ of the reflecting surface 13 with respect to the first main surface F1.
In the example shown in FIG. 5, the spiral pitch P is shown as the distance along the Z direction between the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2, but improves the reflectance at the reflecting surface 13. From the viewpoint, the thickness DLC of the liquid crystal layer LC is preferably 5 times or more the spiral pitch P, and more preferably 10 times or more.

The reflective surface 13 here corresponds to a surface in which the orientation directions of the liquid crystal molecules LM are aligned or a surface in which the spatial phases are aligned (equal phase surface). The shape of the reflecting surface 13 is not limited to a planar shape, and may be a concave or convex curved surface shape, and is not particularly limited. Further, the reflecting surface 13 may have irregularities, the inclination angle φ of the reflecting surface 13 may not be uniform, or the plurality of reflecting surfaces 13 may not be regularly aligned. The reflective surface 13 having an arbitrary shape can be configured according to the spatial phase distribution of the liquid crystal structure LMS.

The cholesteric liquid crystal, which is a liquid crystal structure LMS, reflects circularly polarized light having a predetermined wavelength λ included in the selective reflection band Δλ in the same swirling direction as the swirling direction of the cholesteric liquid crystal. For example, when the turning direction of the cholesteric liquid crystal is clockwise, the clockwise circular polarization of the light having a predetermined wavelength λ is reflected and the counterclockwise circular polarization is transmitted. Similarly, when the swirling direction of the cholesteric liquid crystal is counterclockwise, the counterclockwise circular polarization of the light having a predetermined wavelength λ is reflected and the clockwise circular polarization is transmitted.

When the spiral pitch of the cholesteric liquid crystal is P, the refractive index of the liquid crystal molecule to abnormal light is ne, and the refractive index of the liquid crystal molecule to normal light is no, generally, the selective reflection band Δλ of the cholesteric liquid crystal for vertically incident light is It is indicated by "no * P to ne * P". Specifically, the selective reflection band Δλ of the cholesteric liquid crystal changes with respect to the range of “no * P to ne * P” according to the inclination angle φ of the reflection surface 13, the incident angle θi, and the like.
The liquid crystal layer LC may be a single layer or a multilayer. When the liquid crystal layer LC is a multilayer body, liquid crystal layers having different spiral pitches may be laminated, or liquid crystal layers having spirals whose spiral directions are opposite to each other may be laminated. Further, when the liquid crystal layer LC is a single layer, it may be a liquid crystal layer in which the spiral pitch changes continuously.

(Example of orientation pattern)
FIG. 6 is a plan view schematically showing an example of the orientation pattern in the liquid crystal layer LC. FIG. 6 shows the orientation direction of the first liquid crystal molecule LM1 among the liquid crystal molecules contained in each liquid crystal structure, and the structure 20 is not shown.

The orientation directions of the first liquid crystal molecules LM1 arranged along the Y direction are different from each other. That is, the spatial topologies in the XY planes differ along the Y direction. For example, the orientation direction of each of the first liquid crystal molecules LM1 changes by a constant angle along the Y direction (from the left to the right in the figure). Here, the amount of change in the orientation direction of the first liquid crystal molecule LM1 is constant along the Y direction, but may be gradually increased or gradually decreased. Here, as shown in FIG. 6, the distance between the two first liquid crystal molecules LM1 when the orientation direction of the first liquid crystal molecule LM1 changes by 180 degrees along the Y direction is defined as the orientation pitch α.

On the other hand, the orientation directions of the first liquid crystal molecules LM1 arranged along the X direction are substantially the same. That is, the spatial topologies in the XY planes substantially match in the X direction.

For example, when the liquid crystal optical element 1 functions as a transmission type diffraction grating described with reference to FIG. 4, the alignment pitch α has a wavelength of the diffracted light of λ, an incident angle of θi, and a diffraction angle of the primary diffracted light. Is set to θd1, and the following relationship is satisfied.

α = λ / (sinθd1-sinθi)
The orientation pitch α is, for example, 3 μm or less.

Next, a layout example of the structure 20 for realizing the orientation pattern shown in FIG. 6 will be described.

(1st layout)
FIG. 7 is a plan view showing the first layout of the structure 20. The first layout corresponds to an example in which a plurality of structures 20 have one type of structure (first structure) 21. Each of the structures 21 is formed in a similarly curved arch shape in a plan view.

The plurality of structures 21 are arranged in the X direction and the Y direction, respectively. The plurality of structures 21 are arranged at the first pitch P1 along the X direction. Further, the plurality of structures 21 are arranged along the Y direction at a second pitch P2 different from the first pitch P1. In one example, the second pitch P2 is larger than the first pitch P1. The second pitch P2 is equivalent to the orientation pitch α shown in FIG.

According to such a first layout, the liquid crystal molecules between the structures 21 adjacent to each other in the X direction are oriented along the tangent line of the structure 21, and the orientation directions of the liquid crystal molecules arranged in the Y direction are continuous. Change. The liquid crystal molecules between the structures 21 adjacent to each other in the Y direction are oriented along the X direction.

(2nd layout)
FIG. 8 is a plan view showing the second layout of the structure 20. The second layout corresponds to an example in which a plurality of structures 20 have a plurality of types of structures (first structure) 21 and structures (second structure) 22. The second layout differs from the first layout in that the structure 22 is added. Each of the structures 22 has a shape different from that of the structure 21 in a plan view, and is formed in a curved arch shape.

The different shape here includes a case where the total length of the structure 22 is different from the total length of the structure 21 and a case where the curvature of the structure 22 is different from the curvature of the structure 21. In the example shown in FIG. 8, the total length of the structure 22 is shorter than the total length of the structure 21, but the curvature of the structure 22 is equivalent to the curvature of the structure 21.

The plurality of structures 22 are arranged in the X direction and the Y direction, respectively. In the X direction, the structure 21 and the structure 22 are arranged alternately. Further, one structure 22 is arranged at substantially an intermediate point between two structures 21 adjacent to each other in the X direction. In addition, a plurality of structures 22 may be arranged between two structures 21 adjacent to each other in the X direction.

The plurality of structures 22 are arranged at a pitch P11 along the X direction. Further, the plurality of structures 22 are arranged along the Y direction at a pitch P12 different from the pitch P11. In one example, the pitch P11 is equivalent to the first pitch P1, the pitch P12 is equivalent to the second pitch P2, and the pitch P12 is equivalent to the orientation pitch α.

According to such a second layout, the liquid crystal molecules between the structure 21 and the structure 22 adjacent to each other in the X direction are oriented along the tangents of the structure 21 and the structure 22 and are oriented in the Y direction. The orientation direction of the liquid crystal molecules arranged in the line changes continuously. The liquid crystal molecules between the structures 21 adjacent to each other in the Y direction are oriented along the X direction.

(3rd layout)
FIG. 9 is a plan view showing a third layout of the structure 20. The third layout corresponds to an example in which the plurality of structures 20 have a plurality of types of structures (first structure) 21 and structures (third structure) 23. The third layout differs from the first layout in that the structure 23 is added. In the third layout, the structure 22 may be further added as in the second layout shown in FIG.

Each of the structures 23 has a shape different from that of the structure 21 in a plan view, and extends linearly along the X direction. The structure 23 is arranged between adjacent structures 21 in the Y direction. The plurality of structures 23 are arranged at a pitch P22 along the Y direction. In one example, the pitch P22 is equivalent to the second pitch P2 and the pitch P22 is equivalent to the orientation pitch α.

According to such a third layout, the liquid crystal molecules between the structures 21 adjacent to each other in the X direction are oriented along the tangent line of the structure 21, and the orientation directions of the liquid crystal molecules arranged in the Y direction are continuous. Change. The liquid crystal molecules between the structures 21 adjacent in the Y direction are oriented along the structure 23.
In the third layout, the number of structures 23 located between the structures 21 adjacent to each other in the Y direction may be two or more.

(4th layout)
FIG. 10 is a plan view showing a fourth layout of the structure 20. The fourth layout corresponds to an example in which the plurality of structures 20 have a plurality of types of structures (first structure) 21 and structures (second structure) 22. Both the structures 21 and 22 are formed in an arch shape as described in the second layout of FIG. However, in the fourth layout, the structures 21 are arranged with a half cycle shift and the structure 22 is also arranged with a half cycle shift in the structure rows adjacent to each other in the Y direction as compared with the second layout. It differs in that.

Here, attention is paid to the structure rows R1 and R2 adjacent to each other in the Y direction. In each of the structure rows R1 and R2, the structure 21 and the structure 22 are arranged alternately along the X direction, and the structure 22 is located approximately in the middle of the two structures 21 adjacent to each other in the X direction. There is. Further, in each of the structure rows R1 and R2, the plurality of structures 21 are arranged at the first pitch P1 along the X direction, and the plurality of structures 22 are arranged at the pitch P11 along the X direction.

The arrangement period of the structure 21 and the structure 22 in the structure row R1 is deviated by half a cycle from the arrangement period of the structure 21 and the structure 22 in the structure row R2. Therefore, the position of the peak P211 of the structure 21 in the structure row R1 is aligned with the position of the peak P222 of the structure 22 in the structure row R2 in the Y direction. Further, the position of the peak 221 of the structure 22 in the structure row R1 is aligned with the position of the peak P212 of the structure 21 in the structure row R2 in the Y direction.

According to such a fourth layout, the liquid crystal molecules between the structure 21 and the structure 22 adjacent to each other in the X direction are oriented along the tangents of the structure 21 and the structure 22 and are oriented in the Y direction. The orientation direction of the liquid crystal molecules arranged in the line changes continuously. The liquid crystal molecules between the structure rows R1 and R2 adjacent to each other in the Y direction are oriented along the X direction.

(Fifth layout)
FIG. 11 is a plan view showing a fifth layout of the structure 20. The fifth layout corresponds to an example in which the plurality of structures 20 have a plurality of types of structures (first structure) 24 and structures (second structure) 25. Each of the structures 24 and 25 is formed in an arch shape, but has an asymmetrical shape in the figure. However, the shape of the structure 24 is axisymmetric with the shape of the structure 25 with respect to the axis parallel to the X direction. The structures 24 and 25 are arranged alternately along the X direction. The plurality of structures 24 are arranged at a pitch P4 along the X direction, and the plurality of structures 25 are arranged at a pitch P5 along the X direction.

In the structure 24, the length on the right side of the figure is shorter than the length on the left side of the figure with the position of the peak P24 as the center. In the structure 25, the length on the right side of the figure is longer than the length on the left side of the figure with the position of the peak P25 as the center.

According to such a fifth layout, the liquid crystal molecules between the structure 24 and the structure 25 adjacent to each other in the X direction are oriented along the tangents of the structure 24 and the structure 25, respectively, and are oriented in the Y direction. The orientation direction of the liquid crystal molecules arranged in the line changes continuously. The liquid crystal molecules between the structure rows R1 and R2 adjacent to each other in the Y direction are oriented along the X direction.

(Modification 1)
FIG. 12 is a plan view showing a modification 1.
In the modified example 1 shown here, the pitch P4 along the X direction of the structure 24 and the pitch P5 along the X direction of the structure 25 are enlarged as compared with the fifth layout shown in FIG. It's different.

(Modification 2)
FIG. 13 is a plan view showing a modification 2.
The layout shown in the upper part of FIG. 13 corresponds to an example in which one structure 23 is added between adjacent structure rows R in the fifth layout shown in FIG. As described above, the structure 23 extends linearly along the X direction.
The layout shown in the lower part of FIG. 13 corresponds to an example in which one structure 23 is added between adjacent structure rows R in the layout of the modified example 1 shown in FIG.

(Modification 3)
FIG. 14 is a plan view showing a modification 3.
The layout shown in the upper part of FIG. 14 corresponds to an example in which two structures 23 are added between adjacent structure rows R in the fifth layout shown in FIG. As described above, each of the structures 23 extends linearly along the X direction.
The layout shown in the lower part of FIG. 14 corresponds to an example in which two structures 23 are added between adjacent structure rows R in the layout of the modified example 1 shown in FIG.

(Modification example 4)
FIG. 15 is a plan view showing a modified example 4.
The layout shown in the upper part of FIG. 15 corresponds to an example in which three structures 23 are added between adjacent structure rows R in the fifth layout shown in FIG.
The layout shown in the lower part of FIG. 15 corresponds to an example in which three structures 23 are added between adjacent structure rows R in the layout of the modified example 1 shown in FIG.
The number of structures 23 located between adjacent structure rows R may be four or more.

(6th layout)
FIG. 16 is a plan view showing a sixth layout of the structure 20.
In the sixth layout, the plurality of structures 20 are N types of structures (first structure) 201, structure (second structure) 202, structure (third structure) 203, and structure (third structure). 4 Structure) Corresponds to the example having 204. Here, N is 4. Each of the structures 201 to 204 is formed in a straight line. However, the extending directions of the structures 201 to 204 are different from each other. The structures 201 to 204 are arranged at intervals along the Y direction.

When the structures 201 to 204 are regarded as a group of structures, the repeating pitch (period) β of the structures is equivalent to the orientation pitch α described with reference to FIG.
For example, when a group of structures is divided into N gradations and each gradation is expressed by a linear structure, the extension direction of the structure of each gradation is an angle represented by (180 ° / N). It changes little by little. That is, the angle formed by the extending direction of the structures adjacent to the Y direction is (180 ° / N).
The example shown here corresponds to the case where N is 4, and the extending directions of the structures 201 to 204 arranged in the Y direction change by 45 ° in the clockwise direction. Hereinafter, each of the structures 201 to 204 will be specifically described.

The plurality of structures 201 extend in the Y direction, are parallel to each other, and are arranged at equal intervals D201 along the X direction. The interval D201 is, for example, 100 nm. When the pitch β is 3 μm, the length L201 of the structure 201 along the Y direction is, for example, 600 nm.
The plurality of structures 202 are parallel to each other and are arranged at equal intervals along the X direction. The extending direction of the structure 202 is a direction of 45 ° clockwise with respect to the structure 201 with respect to the extending direction of the structure 201. The spacing D202 between adjacent structures 202 is, for example, 100 nm.
The plurality of structures 203 extend in the X direction, are parallel to each other, and are arranged at equal intervals D203 along the Y direction. In other words, the extending direction of the structure 203 is 90 ° clockwise with respect to the extending direction of the structure 201 with respect to the extending direction of the structure 201. The spacing D203 between adjacent structures 203 is, for example, 100 nm.
The plurality of structures 204 are parallel to each other and are arranged at equal intervals along the X direction. The extending direction of the structure 204 is a direction of 135 ° clockwise with respect to the structure 201 with respect to the extending direction of the structure 201. The spacing D204 between adjacent structures 204 is, for example, 100 nm.

According to such a sixth layout, the liquid crystal molecules between the structures 201 adjacent to each other in the X direction are oriented along the extending direction of the structure 201, and the liquid crystal molecules between the structures 202 adjacent to each other in the X direction are oriented. Is oriented along the extension direction of the structure 202, and the liquid crystal molecules between the structures 203 adjacent to the X direction are oriented along the extension direction of the structure 203, and the liquid crystal molecules of the structure 204 adjacent to the X direction are oriented. The liquid crystal molecules in between are oriented along the extending direction of the structure 204.
Although the case where N is 4 has been described here, N is an integer of 2 or more and may be an integer other than 4.

Some modifications will be described below. Each modification corresponds to the case where N is 4. In each modification, the extension direction of each of the structures 201 to 204 is different. In the following description, the extension direction of the structure with respect to the Y direction is shown as the direction of the clockwise angle θ with reference to the direction of the tip of the arrow indicating the Y direction.

(Modification 5)
FIG. 17 is a plan view showing a modification 5.
The extending direction of the structure 201 with respect to the Y direction is a direction in which the angle θ201 is 15 °. Similarly, the extending direction of the structure 202 is the direction in which the angle θ202 is 60 °. The extending direction of the structure 203 is the direction in which the angle θ203 is 105 °. The extending direction of the structure 204 is the direction in which the angle θ204 is 150 °.
That is, in the modified example 5, none of the structures 201 to 204 extend in the Y direction, nor does it extend in the X direction.
Also, the set of structures 201 and 202 is asymmetric with the set of structures 203 and 204 with respect to an axis that passes between structures 202 and 203 and is parallel to the X direction.
The angles formed by the extending directions of the structures adjacent to each other in the Y direction are the same, and are 45 °.

(Modification 6)
FIG. 18 is a plan view showing a modification 6.
The extending direction of the structure 201 with respect to the Y direction is a direction in which the angle θ201 is 22.5 °. Similarly, the extending direction of the structure 202 is the direction in which the angle θ202 is 67.5 °. The extending direction of the structure 203 is the direction in which the angle θ203 is 112.5 °. The extending direction of the structure 204 is the direction in which the angle θ204 is 157.5 °.
Further, the set of the structures 201 and 202 is axisymmetric with the set of the structures 203 and 204 with respect to the axis passing between the structure 202 and the structure 203 and parallel to the X direction.
The angle formed by the extending direction of the structures adjacent to each other in the Y direction is 45 °.

(Modification 7)
FIG. 19 is a plan view showing a modification 7.
The angle formed by the extending direction of the structures adjacent to the Y direction is not always constant.
That is, the extending direction of the structure 201 with respect to the Y direction is the direction in which the angle θ201 is 25 °. Similarly, the extending direction of the structure 202 is the direction in which the angle θ202 is 75 °. The extending direction of the structure 203 is the direction in which the angle θ203 is 105 °. The extending direction of the structure 204 is the direction in which the angle θ204 is 155 °.
The extending directions of the structures 201 and 202 intersect each other at 50 °. The extending directions of the structures 202 and 203 intersect each other at 30 °. The extending directions of the structures 203 and 204 intersect each other at 50 °. The extending directions of the structures 204 and 201 intersect each other at 50 °.

(Modification 8)
FIG. 20 is a plan view showing a modification 8.
The extending direction of the structure 201 with respect to the Y direction is a direction in which the angle θ201 is 20 °. Similarly, the extending direction of the structure 202 is the direction in which the angle θ202 is 60 °. The extending direction of the structure 203 is the direction in which the angle θ203 is 120 °. The extending direction of the structure 204 is the direction in which the angle θ204 is 160 °.
The extending directions of the structures 201 and 202 intersect each other at 40 °. The extending directions of the structures 202 and 203 intersect each other at 60 °. The extending directions of the structures 203 and 204 intersect each other at 40 °. The extending directions of the structures 204 and 201 intersect each other at 40 °.
As described in the modified example 7 and the modified example 8, the angle formed by the extending direction of the structures adjacent to the Y direction does not necessarily have to be a constant angle (180 ° / N). The angle shown here is an example and is not limited to this angle.

As described above, according to the present embodiment, it is possible to provide a liquid crystal optical element capable of mass production.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Liquid crystal optical element 10 ... Substrate F1 ... First main surface 20 ... Structure 20B ... Bottom 20T ... Top 20S ... Side LC ... Liquid crystal layer LM1 ... First liquid crystal molecule LM2 ... Second liquid crystal molecule LMS ... Liquid crystal structure

Claims (16)

A substrate having a first main surface and
A plurality of structures arranged on the first main surface and arranged at a predetermined pitch,
A liquid crystal layer that surrounds each of the structures and is disposed between the adjacent structures is provided.
The thickness of the liquid crystal layer is larger than the thickness of the structure,
The liquid crystal layer is a liquid crystal optical element having liquid crystal molecules arranged along the structure and cured in a state where the orientation direction of the liquid crystal molecules is fixed. The structure is made of a transparent organic material and has a bottom in contact with the first main surface and a top on the opposite side of the bottom.
The liquid crystal optical element according to claim 1, wherein the width of the bottom is larger than the width of the top. The liquid crystal optical element according to claim 2, wherein the refractive index of the structure is equivalent to the refractive index of the substrate. The liquid crystal optical element according to claim 2, wherein the thickness of the structure is larger than the width of the bottom portion. The liquid crystal optical element according to claim 2, wherein the distance between the bottoms of the adjacent structures is smaller than the thickness of the liquid crystal layer. The liquid crystal optical element according to claim 2, wherein the distance between the bottoms of the adjacent structures is equal to or smaller than the thickness of the structure. In plan view, each of the structures is curved and
The liquid crystal optical element according to claim 2, wherein the liquid crystal molecules located between the adjacent structures are oriented so that their long axes are oriented along the tangent line of the structure. The plurality of structures have a plurality of curved first structures.
The plurality of first structures are arranged at a first pitch along the first direction, and are arranged at a second pitch different from the first pitch along a second direction intersecting with the first direction. Item 2. The liquid crystal optical element according to item 1. The plurality of structures further include a second structure arranged between the first structures adjacent to each other in the first direction.
The liquid crystal optical element according to claim 8, wherein the second structure has a shape different from that of the first structure and is curved. The plurality of structures further include at least one third structure disposed between the first structures adjacent to each other in the second direction.
The liquid crystal optical element according to claim 8, wherein the third structure extends linearly along the first direction. The liquid crystal optical element according to claim 1, wherein the liquid crystal layer has a nematic liquid crystal having aligned orientation directions. The liquid crystal optical element according to claim 1, wherein the liquid crystal layer has a cholesteric liquid crystal. The plurality of structures further include a second structure arranged between the first structures adjacent to each other in the first direction.
The liquid crystal optical element according to claim 8, wherein the shape of the first structure is axisymmetric with the shape of the second structure with respect to an axis parallel to the first direction. The plurality of structures have N types of structures, and the plurality of structures have N types of structures.
The N types of structures are each formed in a straight line and have different extending directions from each other.
The liquid crystal optical element according to claim 1, wherein among the N types of structures, the angle formed by the extending directions of the structures adjacent to each other is (180 ° / N). The plurality of structures include a plurality of first structures arranged at equal intervals along the first direction, a plurality of second structures arranged at equal intervals along the first direction, and the first direction. It has a plurality of third structures, which are arranged at equal intervals along the
The first structure, the second structure, and the third structure are each formed linearly.
The extension direction of the first structure, the extension direction of the second structure, and the extension direction of the third structure are different from each other.
The first structure, the second structure, and the third structure are arranged in order along a second direction intersecting the first direction.
The angle formed by the extending direction of the first structure and the extending direction of the second structure is equivalent to the angle formed by the extending direction of the second structure and the extending direction of the third structure. The liquid crystal optical element according to claim 1. The plurality of structures include a plurality of first structures arranged at equal intervals along the first direction, a plurality of second structures arranged at equal intervals along the first direction, and the first direction. It has a plurality of third structures, which are arranged at equal intervals along the
The first structure, the second structure, and the third structure are each formed linearly.
The extension direction of the first structure, the extension direction of the second structure, and the extension direction of the third structure are different from each other.
The first structure, the second structure, and the third structure are arranged in order along a second direction intersecting the first direction.
The angle formed by the extending direction of the first structure and the extending direction of the second structure is the angle formed by the extending direction of the second structure and the extending direction of the third structure. The liquid crystal optical element according to claim 1, which is different.

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