Optical element, device including optical element, and manufacturing method of optical element

Abstract

To provide an optical element capable of increasing diffraction angle and inhibiting light leakage from an oblique direction.SOLUTION: The optical element includes: a first surface and a second surface opposite the first surface; and a first liquid crystal layer and a second liquid crystal layer from the first surface to the second surface in this order. The first liquid crystal layer includes a plurality of alignment regions in which the arrangement direction of liquid crystal molecules changes by 180 degrees in a stepwise manner, along a prescribed in-plane direction. The second liquid crystal layer includes a plurality of alignment regions in which arrangement direction of liquid crystal molecules gradually changes 180 degrees, along a prescribed in-plane direction. A positive C layer is provided between the first liquid crystal layer and the second liquid crystal layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to optical elements, devices including the optical elements, and methods for manufacturing the optical elements. [Background technology]

[0002] 2. Description of the Related Art There are technical fields in which optical elements are used to change the polarization state of light or the traveling direction of light.

[0003] The optical element described above is used in, for example, a light control device. In recent years, development of devices equipped with optical sensors has progressed in the fields of personal authentication and autonomous driving of vehicles. Examples of devices equipped with optical sensors include face authentication devices and LiDAR (light detection and ranging). Optical elements may also be used in such devices equipped with optical sensors. In recent years, display devices for displaying virtual reality (VR), augmented reality (AR), and mixed reality (MR) have been released. In this specification, technologies for displaying non-existent reality, such as VR, AR, and MR, are referred to as "cross reality (XR)." Display elements may also be used in display devices for cross reality.

[0004] Among the optical elements described above, there are optical elements that utilize the diffraction of light. As an optical element that utilizes the diffraction of light, an optical element in which a plurality of liquid crystal layers having a diffractive effect are stacked has been proposed (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 066429 [Patent Document 2] Special Publication No. 2019-536101 Summary of the Invention [Problem to be solved by the invention]

[0006] The optical element in which multiple liquid crystal layers having a diffractive effect are stacked as in Patent Documents 1 and 2 can increase the diffraction angle. However, devices equipped with an optical element in which multiple liquid crystal layers having a diffractive effect are stacked frequently suffer from problems such as reduced contrast and the occurrence of double images. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems. They have identified that the above-mentioned problems arise from increased light leakage when light is incident on an optical element from an oblique direction. After further research, they have discovered that the above-mentioned problems can be solved by disposing a positive C layer between diffractive liquid crystal layers.

[0008] This disclosure provides the following: <1> ~ <3> The present invention provides an optical element of the present invention, a device including the optical element, and a method for manufacturing the optical element. <1> An optical element, the optical element has a first surface and a second surface opposite to the first surface, and has a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface; the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; An optical element having a positive C layer between the first liquid crystal layer and the second liquid crystal layer. <2> <1> An apparatus comprising the optical element according to claim 1. <3> The method comprises the following first to third steps: <1> 10. A method for manufacturing the optical element according to claim 9. First step: preparing a first laminate having a first liquid crystal layer on a first substrate, and a second laminate having a second liquid crystal layer on a second substrate. The first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the predetermined in-plane direction. Second step: A step of obtaining a first' laminate by laminating a first adhesive layer, a positive C layer, and a second adhesive layer on the first liquid crystal layer of the first laminate. Third step: A step of integrating the first' laminate and the second laminate by bonding the surface of the first' laminate facing the second adhesive layer to the surface of the second laminate facing the second liquid crystal layer. [Effects of the Invention]

[0009] The optical element and the device including the optical element according to the present disclosure can increase the diffraction angle and suppress light leakage from oblique directions. The method for manufacturing the optical element according to the present disclosure can efficiently manufacture the optical element having the above-mentioned properties. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view illustrating an embodiment of an optical element according to the present disclosure. [Figure 2] FIG. 2 is a schematic plan view for explaining the states of a first liquid crystal layer, a positive C layer, and a second liquid crystal layer. [Figure 3] FIG. 2 is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the first liquid crystal layer and the second liquid crystal layer. [Figure 4] 1 is a schematic plan view showing a state in which liquid crystal molecules are aligned radially in multiple directions within the plane of a liquid crystal layer. FIG. [Figure 5] FIG. 2 is a plan view showing an embodiment of an arrangement pattern of recesses in a pattern layer, which is an embodiment of an alignment layer. [Figure 6] 1A and 1B are schematic diagrams for explaining a method for measuring light leakage and diffraction efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the optical element of the present disclosure, an apparatus including the optical element, and a method for manufacturing the optical element will be described.

[0012] [Optical elements] The optical element of the present disclosure comprises: a first surface and a second surface opposite to the first surface, and a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface; the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; A positive C layer is provided between the first liquid crystal layer and the second liquid crystal layer.

[0013] FIG. 1 is a cross-sectional view showing one embodiment of an optical element according to the present disclosure. 1 has a first surface 10a and a second surface 10b opposite to the first surface, and has a first liquid crystal layer 31 and a second liquid crystal layer 32 in this order from the first surface 10a to the second surface 10b. The optical element 100 in FIG. 1 has a positive C layer 51 between the first liquid crystal layer 31 and the second liquid crystal layer 32. The optical element 100 in Figure 1 has a first alignment layer 21 and a first substrate 11 on the first surface 10a side of the first liquid crystal layer 31, and a second alignment layer 22 and a second substrate 12 on the second surface 10b side of the second liquid crystal layer 32. The optical element 100 of FIG. 1 has adhesive layers 41 and 42 between the first liquid crystal layer 31 and the positive C layer 51, and between the positive C layer 51 and the second liquid crystal layer 32, respectively. In the optical element 100 of FIG. 1, the layers between the first surface 10a and the second surface 10b are tightly adhered and integrated. Fig. 1 is a schematic cross-sectional view. That is, the scale of each layer constituting optical element 100 is schematic for ease of illustration and differs from the actual scale. The same applies to other figures.

[0014] 2 is a schematic plan view for explaining the states of the first liquid crystal layer 31 and the second liquid crystal layer 32. In FIG. 2, the first liquid crystal layer 31, the positive C layer 51, and the second liquid crystal layer 32 are separated and shifted in the XY plane to make it easier to explain the states of the first liquid crystal layer 31 and the second liquid crystal layer 32. In FIG. 2, reference numeral 31a denotes the alignment direction of liquid crystal molecules in the plane of the first liquid crystal layer 31, and reference numeral 32a denotes the alignment direction of liquid crystal molecules in the plane of the second liquid crystal layer 32. In Fig. 2, the first liquid crystal layer 31 has an alignment region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In Fig. 2, the second liquid crystal layer 32 has an alignment region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In Fig. 2, the symbols P1 and P2 respectively indicate the lengths over which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees. For simplicity, Fig. 2 shows only one alignment region in the X-axis direction in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, but the optical element of the present disclosure has multiple such alignment regions in a predetermined direction.

[0015] Fig. 3(a) is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the first liquid crystal layer. Fig. 3(b) is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the second liquid crystal layer. In Fig. 3(a), reference numeral 31a indicates the alignment direction of liquid crystal molecules in the plane of the first liquid crystal layer 31. In Fig. 3(b), reference numeral 32a indicates the alignment direction of liquid crystal molecules in the plane of the second liquid crystal layer 32. 3(a), the first liquid crystal layer 31 has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In FIG. 3(a), the reference symbols P1-1 to P1-5 each indicate the length over which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees. 3(b), the second liquid crystal layer 32 has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In FIG. 3(b), the reference characters P2-1 to P2-5 respectively indicate the lengths over which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees.

[0016] <Layer structure> The optical element of the present disclosure has a first surface and a second surface opposite to the first surface. The first surface refers to one surface in the thickness direction of the optical element, and the second surface refers to the other surface in the thickness direction of the optical element. The optical element of the present disclosure must have a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface, and must have a positive C layer between the first liquid crystal layer and the second liquid crystal layer.

[0017] The optical element of the present disclosure may have layers other than the first liquid crystal layer, the positive C layer, and the second liquid crystal layer. Examples of the other layers include a first substrate, a first alignment layer, an adhesive layer, a second substrate, and a second alignment layer. Examples of the other layers include retardation layers other than the positive C layer, such as a positive A layer, a negative A layer, a positive B layer, and a negative B layer. Examples of the other layers include liquid crystal layers other than the first and second liquid crystal layers, such as a third liquid crystal layer.

[0018] In the optical element of the present disclosure, it is preferable that the layers from the first surface to the second surface are tightly adhered and integrated. In the above-described integrated configuration, it is preferable to have an adhesive layer between at least one of the first liquid crystal layer and the positive C layer and the positive C layer and the second liquid crystal layer.

[0019] The laminated structure of the optical element of the present disclosure may be any of the following (1) to (11). The order of the layers in the following (1) to (11) refers to the order of the layers from the first surface to the second surface. In the optical element of the present disclosure, the layers from the first surface to the second surface do not need to be in close contact with each other, but it is preferable that the layers from the first surface to the second surface are in close contact with each other and integrated. The laminated structure of the optical element of the present disclosure is not limited to the following (1) to (11). For example, in the following (1) to (11), an adhesive layer may be provided between one or more of the layers from the first surface to the second surface. Furthermore, a primer layer may be provided between the substrate such as the first substrate and the alignment layer such as the first alignment layer. (1) First liquid crystal layer, positive C layer, second liquid crystal layer (2) First substrate, first liquid crystal layer, positive C layer, second liquid crystal layer, second substrate (3) First substrate, first alignment layer, first liquid crystal layer, positive C layer, second liquid crystal layer, second alignment layer, second substrate (4) First substrate, first liquid crystal layer, positive C layer, second substrate, second liquid crystal layer (5) First substrate, first alignment layer, first liquid crystal layer, positive C layer, second substrate, second alignment layer, second liquid crystal layer (6) First liquid crystal layer, first substrate, positive C layer, second substrate, second liquid crystal layer (7) First liquid crystal layer, first alignment layer, first substrate, positive C layer, second substrate, second alignment layer, second liquid crystal layer (8) First liquid crystal layer, positive C layer, retardation layer other than the positive C layer, second liquid crystal layer (9) First substrate, first alignment layer, first liquid crystal layer, positive C layer, retardation layer other than the positive C layer, second liquid crystal layer, second alignment layer, second substrate (10) First liquid crystal layer, positive C layer, second liquid crystal layer, positive C layer, third liquid crystal layer (11) First substrate, first alignment layer, first liquid crystal layer, positive C layer, second substrate, second alignment layer, second liquid crystal layer, positive C layer, third liquid crystal layer, third alignment layer, third substrate

[0020] In the optical element of the present disclosure, the first liquid crystal layer and the second liquid crystal layer each have a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The first liquid crystal layer and the second liquid crystal layer having the above-described configuration each have the effect of diffracting light. Therefore, the optical element of the present disclosure can have a large diffraction angle. However, devices equipped with optical elements each including multiple stacked diffractive liquid crystal layers may suffer from problems such as reduced contrast and double images. The present inventors conducted extensive research to solve these problems. They identified that these problems arise from increased light leakage when light is incident on the optical element from an oblique direction. After further research, they discovered that the above-described problems can be solved by disposing a positive C layer between the first and second diffractive liquid crystal layers. The reason that light leakage can be suppressed by disposing a positive C layer between the first and second diffractive liquid crystal layers is believed to be that the liquid crystal layer located farther from the light incident surface functions more easily as a λ / 2 retardation layer for oblique light. The optical element of the present disclosure can solve these problems regardless of whether the first or second surface is the light incident surface.

[0021] <Liquid crystal layer> The optical element of the present disclosure has a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface. The first liquid crystal layer is required to have multiple alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction, and the second liquid crystal layer is required to have multiple alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The first liquid crystal layer and the second liquid crystal layer have alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction, and are thereby able to exhibit the following functions (X1) to (X2), respectively. (X1) A function of diffracting and inverting the phase of incident light when circularly polarized light is incident as the incident light. (X2) When natural light or linearly polarized light is incident as incident light, the function of diffracting the incident light and separating the incident light into right-handed circularly polarized light and left-handed circularly polarized light.

[0022] The direction of the slow axis and / or the direction of the fast axis of the liquid crystal layer varies along the alignment direction of the liquid crystal molecules. Therefore, a liquid crystal layer having an alignment region in which the direction of the slow axis and / or the direction of the fast axis change stepwise by 180 degrees along a predetermined in-plane direction can be said to have an alignment region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the predetermined in-plane direction. Therefore, whether or not a liquid crystal layer has an alignment region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the predetermined in-plane direction can be determined by measuring the direction of the slow axis and / or the direction of the fast axis. An example of a device capable of measuring the direction of the slow axis and / or the direction of the fast axis of a liquid crystal layer is a two-dimensional birefringence evaluation system (product name: WPA-Micro) manufactured by Photonic Lattice. In this specification, the slow axis means the in-plane direction in which the refractive index is greatest, and the fast axis means the in-plane direction perpendicular to the slow axis.

[0023] The diffraction angle θ can be expressed by the following formula, where x [nm] is the length required for the alignment direction of the liquid crystal molecules in the liquid crystal layer to change 180 degrees, λ [nm] is the wavelength of light, and θ0 is the angle of incidence of light. θ and θ0 are angles when the perpendicular direction to the plane of the liquid crystal layer is set to 0 degrees. In the formula below, θ0 is the positive direction from the perpendicular direction. The sign ± is added because, depending on the direction of rotation of the circularly polarized light that is the incident light, the light may be diffracted in the positive direction or the negative direction relative to the perpendicular direction. sinθ=±(λ / x)+sinθ0

[0024] For example, when the incident angle θ0 is fixed at 0 degrees and the wavelength of light is fixed at 1550 nm, the relationship between the pitch, which is the length until the alignment direction of the liquid crystal molecules changes by 180 degrees, and the diffraction angle is as shown in Table 1 below. [Table 1]

[0025] The diffraction angles in Table 1 are angles when the liquid crystal layer is a single layer. If the polarization state is the same, increasing the number of liquid crystal layers increases the diffraction angle as a multiplier of the number of diffractive optical elements. If the diffraction angle at an arbitrary pitch is θ (degrees) and the number of diffractive optical elements is n, the diffraction angle is 2 n-1 ×θ (degrees).

[0026] The first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The predetermined direction of the first liquid crystal layer may be a specific direction of the first liquid crystal layer. That is, the first liquid crystal layer may have a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a specific in-plane direction. In FIG. 3(a), the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. The second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The predetermined direction of the second liquid crystal layer may be a specific direction of the second liquid crystal layer. That is, the second liquid crystal layer may have a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a specific in-plane direction. In FIG. 3(b), the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane.

[0027] As shown in Figure 3(a), the first liquid crystal layer may have a gap between the symbols 31a indicating the alignment direction of the liquid crystal molecules in the plane of the first liquid crystal layer 31, but it is not necessary for there to be such a gap. As shown in Figure 3(b), the second liquid crystal layer may have a gap between the symbols 32a indicating the alignment direction of the liquid crystal molecules in the plane of the first liquid crystal layer 31, but it is not necessary for there to be such a gap.

[0028] The optical element of the present disclosure may have the following configuration 1. <<Configuration 1>> The predetermined direction of the first liquid crystal layer is a specific direction of the first liquid crystal layer, the predetermined direction of the second liquid crystal layer is a specific direction of the second liquid crystal layer, and the specific direction of the first liquid crystal layer and the specific direction of the second liquid crystal layer are approximately the same direction.

[0029] By providing the above-described configuration 1, it becomes easier to increase the diffraction angle of the optical element. In the above configuration 1, "substantially the same direction" means that the angle between the specific direction of the first liquid crystal layer and the specific direction of the second liquid crystal layer is 1.0 degrees or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less.

[0030] The optical element of the present disclosure may have the following configuration 2. When the optical element has the configuration 2, it is preferable that it has the above configuration 1. Configuration 2 When P1 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes gradually by 180 degrees, P1 becomes gradually shorter from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction, and when P2 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer changes gradually by 180 degrees, P2 becomes gradually shorter from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction.

[0031] In Fig. 3(a), the symbols P1-1 to P1-5 each indicate the length over which the alignment direction of the liquid crystal molecules in the first liquid crystal layer changes stepwise by 180 degrees. In Fig. 3(a), the symbols P1-1 to P1-3 have the same length, and the symbols P1-4 to P1-5 have the same length, and the length of symbols P1-1 to P1-3 is greater than the length of symbols P1-4 to P1-5. Therefore, in Fig. 3(a), P1 becomes shorter stepwise from the alignment region at the left end in the X-axis direction to the alignment region at the right end. The symbols P2-1 to P2-5 in Fig. 3(b) each indicate the length over which the alignment direction of the liquid crystal molecules in the second liquid crystal layer changes stepwise by 180 degrees. In Fig. 3(b), the lengths of the symbols P2-1 to P2-3 are the same, and the lengths of the symbols P2-4 to P2-5 are the same, and the length of the symbols P2-1 to P2-3 is greater than the length of the symbols P2-4 to P2-5. Therefore, in Fig. 3(b), P2 becomes shorter stepwise from the alignment region at the left end in the X-axis direction to the alignment region at the right end.

[0032] By providing the above-described configuration 2, it is possible to impart different diffraction angles to different locations within the surface of the optical element. In the case of the configuration 2, P1 of the first liquid crystal layer and P2 of the second liquid crystal layer do not have to be substantially aligned, but it is preferable that they are substantially aligned. By substantially aligning P1 and P2, it becomes easier for the liquid crystal layers to interact with each other. P1 and P2 being substantially equal means that P1 / P2 is 0.97 or more and 1.03 or less, preferably 0.98 or more and 1.02 or less, and more preferably 0.99 or more and 1.01 or less.

[0033] The optical element of the present disclosure may have the following configuration 3. Structure 3 The predetermined directions of the first liquid crystal layer are radial directions based on the center of the arrangement pattern of the liquid crystal molecules, and the predetermined directions of the second liquid crystal layer are radial directions based on the center of the arrangement pattern of the liquid crystal molecules.

[0034] FIG. 4 is a schematic plan view showing a state in which liquid crystal molecules are aligned radially in multiple directions within the plane of the liquid crystal layer. In FIG. 4, each line corresponding to reference symbol 31c indicates the alignment direction of the liquid crystal molecules at each location. In FIG. 4, alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees are provided in multiple directions radially from the center of the liquid crystal molecule alignment pattern. For example, in the direction along the X axis, the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees between reference symbols A1 and A2, between reference symbols A2 and A3, between reference symbols B1 and B2, and between reference symbols B2 and B3. FIG. 4 corresponds to a schematic plan view of the first and second liquid crystal layers that satisfy the third configuration.

[0035] In the third configuration, as shown in FIG. 4, it is preferable that regions in which the liquid crystal molecules are aligned in the same direction are concentrically arranged within the plane of the first and second liquid crystal layers. In the case of Configuration 3, it is preferable that the multi-direction of the first liquid crystal layer and the multi-direction of the second liquid crystal layer are substantially the same direction. "Substantially the same direction" means that the angle between the direction of the first liquid crystal layer and the direction of the second liquid crystal layer is 1.0 degree or less, preferably 0.7 degree or less, and more preferably 0.5 degree or less.

[0036] The optical element of the present disclosure may have the following configuration 4. When the optical element has the configuration 4, it preferably has the above configuration 3. Structure 4 When the length until the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes stepwise by 180 degrees is defined as P1, P1 becomes shorter stepwise from the central alignment region toward the outer alignment region, When P2 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer gradually changes by 180 degrees, P2 gradually shortens from the central alignment region toward the outer alignment regions.

[0037] By providing the above-described configuration 4, it is possible to converge or diverge light, and it is possible to easily impart lens functions to the optical element. In configuration 4, P1 of the first liquid crystal layer and P2 of the second liquid crystal layer do not have to be approximately the same, but it is preferable that they are. When P1 and P2 are approximately the same, it becomes easier to adjust the lens function. P1 and P2 being substantially equal means that P1 / P2 is 0.97 or more and 1.03 or less, preferably 0.98 or more and 1.02 or less, and more preferably 0.99 or more and 1.01 or less.

[0038] In FIG. 4, the distances between A1 and A2, A2 and A3, B1 and B2, and B2 and B3 indicate the lengths over which the alignment direction of the liquid crystal molecules changes by 180 degrees. Also, in FIG. 4, the distance between A1 and A2 is greater than the distance between A2 and A3, and the distance between B1 and B2 is greater than the distance between B2 and B3. In other words, in the liquid crystal layer of FIG. 4, the distance over which the alignment direction of the liquid crystal molecules changes by 180 degrees gradually decreases from the central alignment region toward the outer alignment regions. Therefore, FIG. 4 corresponds to a schematic plan view of the first and second liquid crystal layers satisfying Configuration 4.

[0039] The optical element of the present disclosure preferably further comprises the third liquid crystal layer, and has the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer in this order from the first surface to the second surface, and the third liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction, and has a positive C layer between the second liquid crystal layer and the third liquid crystal layer. By providing the above configuration, it is possible to easily increase the diffraction angle and also to suppress light leakage from oblique directions.

[0040] The optical element of the present disclosure may further include a fourth liquid crystal layer or the like as a layer having a plurality of alignment regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The fourth liquid crystal layer or the like may be embodied in the same manner as the first to third liquid crystal layers.

[0041] When the first and second liquid crystal layers have the above-described configuration 1, the optical element having the third liquid crystal layer preferably has the following configuration 1'. In configuration 1', "substantially the same direction" means that the angle formed between the specific direction of the first liquid crystal layer and the specific direction of the second liquid crystal layer, and the angle formed between the specific direction of the second liquid crystal layer and the specific direction of the third liquid crystal layer, are 1.0 degrees or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less. "Configuration 1'" The predetermined direction of the third liquid crystal layer is a specific direction of the third liquid crystal layer, and the specific direction of the first liquid crystal layer, the specific direction of the second liquid crystal layer, and the specific direction of the third liquid crystal layer are approximately the same direction.

[0042] When the first and second liquid crystal layers have the above-described configuration 2, the optical element having the third liquid crystal layer preferably has the following configuration 2'. When the optical element has the configuration 2', P1, P2, and P3 do not have to be approximately the same, but it is preferable that they are approximately the same. "Configuration 2'" When P3 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the third liquid crystal layer changes gradually by 180 degrees, P3 gradually shortens from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction.

[0043] When the first and second liquid crystal layers have the above-described configuration 3, the optical element having the third liquid crystal layer preferably has the following configuration 3'. In configuration 3', it is preferable that regions in which the liquid crystal molecules are aligned in the same direction are concentrically arranged within the plane of the third liquid crystal layer. When configuration 3' is included, it is preferable that the multi-directions of the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer are aligned in approximately the same direction. "Almost the same direction" means that the angle between the direction of the first liquid crystal layer and the direction of the second liquid crystal layer, and the angle between the direction of the second liquid crystal layer and the direction of the third liquid crystal layer are each 1.0 degree or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less. "Configuration 3'" The predetermined directions of the third liquid crystal layer are radial directions with respect to the center of the arrangement pattern of the liquid crystal molecules.

[0044] When the first and second liquid crystal layers have the above-described configuration 4, the optical element having the third liquid crystal layer preferably has the following configuration 4'. When the optical element has the configuration 4', P1, P2, and P3 do not have to be approximately the same, but it is preferable that they are approximately the same. "Configuration 4'" When P3 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the third liquid crystal layer gradually changes by 180 degrees, P3 gradually shortens from the central alignment region toward the outer alignment regions.

[0045] The alignment regions of the first and second liquid crystal layers, or the first, second, and third liquid crystal layers, in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, do not need to coincide in the planar direction. Even if the alignment regions of each liquid crystal layer do not coincide in the planar direction, interaction between the liquid crystal layers can be obtained as long as the alignment directions of the liquid crystal molecules in each liquid crystal layer are approximately the same. Furthermore, by not coincidentally aligning the alignment regions of each liquid crystal layer in the planar direction, moiré can be suppressed. To facilitate enhancing the interaction between the liquid crystal layers, it is preferable that the alignment regions in the first and second liquid crystal layers, or the first, second and third liquid crystal layers, in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, are not shifted too much in the planar direction. When the length over which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees is defined as the pitch and the maximum value of the pitch of the multiple liquid crystal layers included in the optical element is defined as Pmax, the misalignment of the alignment regions in the planar direction of each liquid crystal layer is preferably less than Pmax, and more preferably Pmax / 2 or less.

[0046] The position of the alignment region of each liquid crystal layer in the planar direction is determined from the cross-sectional photographs obtained in the following (B1) to (B4). Since the degree of dyeing of the liquid crystal layer varies depending on the direction of alignment of the liquid crystal molecules, the alignment regions of each liquid crystal layer such as the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer can be discriminated from the cross-sectional photographs obtained in the following (B1) to (B4). Further, from the cross-sectional photographs obtained in the following (B1) to (B4), the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees can also be discriminated.

[0047] (B1) Prepare a cut sample by cutting the optical element into strip shape. Embed the cut sample with a thermosetting resin to prepare an embedded sample. (B2) Use a microtome to cut the embedded sample to prepare an ultra-thin section sample. The above-mentioned cutting is performed so that a vertical cross-section in the thickness direction of the optical element is exposed. The conditions of the microtome are such that the knife is a diamond knife and the set section thickness is 80 nm. (B3) Stain the ultra-thin section sample by immersing it in an osmium tetroxide solution for 30 minutes and in a ruthenium tetroxide solution for 5 minutes. (B4) Observe the stained sample by STEM under the following conditions. <STEM conditions> · Apparatus (manufactured by Hitachi High-Tech Corporation, product number: S-4800 TYPE1) · Acceleration voltage; 30.0 kV · Emission current; 10 μA · W.D; 8 mm · Detector; TE

[0048] The first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer have a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. The positive C layer, positive A layer, negative A layer, positive B layer, and negative B layer described later are different from the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer in that they do not have a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane.

[0049] In the first, second, and third liquid crystal layers, the length over which the alignment direction of the liquid crystal molecules changes by 180 degrees is not particularly limited. The lower limit of the length is preferably 0.2 μm or more, more preferably 0.8 μm or more, and even more preferably 2.0 μm or more. By setting the length to 0.2 μm or more, poor alignment can be easily suppressed when the alignment layer described below is a patterned layer. The upper limit of the length is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. To make it easier to achieve a visible diffraction angle, the angle is preferably 500 μm or less.

[0050] <Liquid crystal layer materials> The liquid crystal compound constituting the first liquid crystal layer, the second liquid crystal layer and the third liquid crystal layer may be one or more selected from rod-shaped liquid crystal compounds such as nematic liquid crystal compounds and smectic liquid crystal compounds, cholesteric liquid crystal compounds, discotic liquid crystal compounds (disk-shaped liquid crystal compounds), etc. The liquid crystal layer may further contain a chiral agent in addition to the liquid crystal compound. For example, a liquid crystal layer containing a nematic liquid crystal compound and a chiral agent has an alignment in which the direction of the liquid crystal compound molecules is rotated when the liquid crystal layer is viewed in a plane. However, the direction of the liquid crystal compound molecules does not need to be rotated 360 degrees and may be rotated by less than 360 degrees.

[0051] The first, second and third liquid crystal layers are preferably homogeneously aligned liquid crystal layers so as to easily impart a predetermined in-plane retardation to the liquid crystal layers, and therefore the liquid crystal compound in the liquid crystal layers is preferably a rod-shaped liquid crystal compound.

[0052] The liquid crystal compound is preferably a rod-shaped liquid crystal compound, and is not particularly limited, but examples thereof include the compounds shown in (1) to (28) below.

[0053] [ka]

[0054] [Chemistry]

[0055] [Chemistry]

[0056] [Chemistry]

[0057] The liquid crystal compound preferably is a polymerizable rod-like liquid crystal material. Examples of the polymerizable functional group of the polymerizable rod-like liquid crystal material include those that polymerize by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat. Specific examples include radical polymerizable functional groups. Examples of the radical polymerizable functional group include a functional group having at least one addition-polymerizable ethylenically unsaturated double bond, and more specifically, a vinyl group, an acrylate group (a general term including an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group), with or without a substituent, etc.

[0058] The first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer may have positive wavelength dispersion or negative wavelength dispersion. Negative wavelength dispersion is a characteristic in which the phase difference imparted to the transmitted light increases as the wavelength of the transmitted light becomes longer. Positive wavelength dispersion is a characteristic in which the phase difference imparted to the transmitted light decreases as the wavelength of the transmitted light becomes longer. In this specification, when the in-plane phase difference at a wavelength of 450 nm is defined as Re450 and the in-plane phase difference at a wavelength of 550 nm is defined as Re550, the characteristic in which Re450 < Re550 is referred to as negative wavelength dispersion. In this specification, the characteristic in which Re450 > Re550 is referred to as positive wavelength dispersion. In this specification, the in-plane retardation is expressed by the following formula, where Nx is the refractive index in the slow axis direction with the highest in-plane refractive index, Ny is the refractive index in the direction perpendicular to the slow axis in-plane, Nz is the refractive index in the thickness direction, and d (nm) is the layer thickness. Also, in this specification, the retardation in the thickness direction is expressed by the following formula. In-plane phase difference=(Nx-Ny)×d) Phase difference in the thickness direction = ((Nx + Ny) / 2 - Nz) × d

[0059] The birefringence of a liquid crystal compound is preferably 0.10 to 0.30, and more preferably 0.15 to 0.26. A higher birefringence is preferable because it allows the liquid crystal layer to be made thinner while still maintaining the same optical performance. However, the higher the birefringence of a liquid crystal compound, the more necessary it is to add units, such as aromatic rings like benzene rings, that are sensitive to ultraviolet light to the liquid crystal molecular structure. For this reason, a birefringence of a liquid crystal compound of 0.30 or less is preferable. The birefringence of a liquid crystal compound can be calculated by dividing the in-plane retardation measured in an area without pattern pitch by the thickness. The in-plane retardation can be measured using, for example, an Oji Scientific Instruments "Model: KOBRA-WR" instrument, and the thickness can be measured using a cross-sectional SEM.

[0060] The first, second, and third liquid crystal layers can be formed, for example, by applying a liquid crystal layer-forming coating liquid containing a liquid crystal compound onto a substrate, followed by drying and curing as necessary. To facilitate the formation of alignment regions in the liquid crystal layers, it is preferable to form an alignment layer on the substrate in advance.

[0061] The first, second, and third liquid crystal layers each preferably have an average in-plane retardation within a predetermined range. When the controlled wavelength is λ [nm], the in-plane retardation of each liquid crystal layer is preferably from (λ / 2) × 0.95 to (λ / 2) × 1.05, more preferably from (λ / 2) × 0.97 to (λ / 2) × 1.03, and even more preferably from (λ / 2) × 0.99 to (λ / 2) × 1.01. By setting the average value of the in-plane retardation of each liquid crystal layer within the above range, it becomes easier to exhibit the functions of the above (X1) to (X2). In any of the cases where λ is 450 nm, 550 nm, and 650 nm, it is preferable that each liquid crystal layer has an in-plane retardation within the above range. By providing the above-described configuration, it is possible to easily suppress light leakage even when the incident light has a wide range of wavelengths in the visible light region. In order to easily provide the above-described configuration, it is preferable that the overall configuration of the liquid crystal layer exhibits negative wavelength dispersion in the entire region of visible light.

[0062] <Positive C layer> The optical element of the present disclosure needs to have a positive C layer between the first liquid crystal layer and the second liquid crystal layer. By disposing a positive C layer between the first liquid crystal layer and the second liquid crystal layer having a diffraction effect, the liquid crystal layer located on the side farther from the light incident surface is likely to function as a λ / 2 retardation layer for obliquely incident light, and thus it is considered that light leakage can be suppressed. When the optical element of the present disclosure further includes a third liquid crystal layer, it is preferable that a positive C layer is also provided between the second liquid crystal layer and the third liquid crystal layer.

[0063] The positive C layer is a layer that satisfies the relationship of Nx ≒ Ny < Nz when the refractive index in the direction of the slow axis having the highest refractive index in the plane is defined as Nx, the refractive index in the direction orthogonal to the slow axis in the plane is defined as Ny, and the refractive index in the thickness direction of the layer is defined as Nz. Nx ≒ Ny means that the difference between Nx and Ny is 0.02 or less. The difference is preferably 0.01 or less. The positive A layer described later is a layer that satisfies the relationship of Nx > Ny ≒ Nz. Ny ≒ Nz means that the absolute value of the difference between Ny and Nz is 0.02 or less. The absolute value of the difference is preferably 0.01 or less. The negative A layer described later is a layer that satisfies the relationship of Nx ≒ Nz > Ny. Nx ≒ Nz means that the absolute value of the difference between Nx and Nz is 0.02 or less. The absolute value of the difference is preferably 0.01 or less. The positive B layer described later is a layer that satisfies the relationship of Nz > Nx > Ny. The negative B layer, which will be described later, is a layer that satisfies the relationship Nx>Ny>Nz.

[0064] The refractive index of each layer, such as the positive C layer, can be measured using the Fresnel normal incidence reflectance formula, for example, by the following methods C1 to C3. However, the refractive index cannot be measured in areas with orientation pitch in the planar direction because diffraction occurs. For this reason, a measurement sample without orientation pitch in the planar direction is prepared, and the refractive index of each layer is measured using this sample. C1: For each layer, light is incident at an angle of 5 degrees from the normal, and the reflectance is measured at the angle of the specular reflection direction. The incident light is linearly polarized light parallel to the slow axis of each layer. Then, from the reflectance in the slow axis direction obtained, the refractive index (Nx * ) is calculated. Reflectance in the slow axis direction = ((1-Nx * ) / (1+Nx * )) 2 C2: For each layer, light is incident at an angle of 5 degrees from the normal, and the reflectance is measured at the angle of the specular reflection direction. The incident light is linearly polarized light parallel to the fast axis of each layer. Then, from the reflectance in the fast axis direction obtained, the refractive index (Ny * ) is calculated. Reflectivity in the fast axis direction = ((1-Ny * ) / (1+Ny * )) 2 C3: The three-dimensional refractive index values ​​(Nx, Ny, Nz) calculated from a phase difference measuring instrument (Oji Measuring Instruments, product name: KOBRA) are the in-plane refractive index Nx of C1 and C2. * and Ny * The three-dimensional refractive index values ​​are adjusted so as to match the above. Then, the adjusted three-dimensional refractive index values ​​(Nx, Ny, Nz) are set as Nx, Ny, and Nz of each layer.

[0065] The positive C layer can be a general-purpose positive C layer. The positive C layer is preferably formed from, for example, a liquid crystal compound that exhibits homeotropic alignment. The liquid crystal compound that exhibits homeotropic alignment preferably exhibits a smectic phase or a nematic phase, and more preferably exhibits a smectic phase. The smectic phase results in a highly ordered layer structure in which the centers of gravity of the liquid crystal molecules are aligned, making it easier for the positive C layer to exhibit homeotropic alignment.

[0066] The positive C layer may contain a vertical alignment promoter to facilitate homeotropic alignment of the liquid crystal compound. Examples of vertical alignment promoters include boronic acid compounds, onium salts, and side-chain liquid crystal polymers. The amount of the vertical alignment agent is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, based on the total solid content of the positive C layer. From the viewpoint of suppressing crystallization of the liquid crystal, it is preferable to use a polymerized side-chain liquid crystal polymer.

[0067] The thickness of the retardation layer in the thickness direction of the positive C layer is preferably −250 nm or more, more preferably −200 nm or more, and is preferably −20 nm or less, more preferably −40 nm or less. The in-plane retardation of the positive C layer is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 2 nm or less.

[0068] The positive C layer can be formed, for example, by applying a coating liquid containing materials for forming the positive C layer to a substrate or other object to be coated, and then drying and curing the coating liquid as necessary. A vertical alignment film may be formed on the object to be coated before forming the positive C layer.

[0069] As the vertical alignment film, a general-purpose vertical alignment film such as a polyimide alignment film or an LB film can be used. More specifically, materials for forming vertical alignment films include silane coupling-based compositions for vertical alignment films such as silane surfactants, titanate surfactants, pyridinium salt polymer surfactants, and n-octadecyltriethoxysilane; polyimide-based compositions for vertical alignment films such as soluble polyimides having a long-chain alkyl group or an alicyclic structure in the side chain, and polyamic acids having a long-chain alkyl group or an alicyclic structure in the side chain; and the like.

[0070] The optical element of the present disclosure may have a vertical alignment film for facilitating homeotropic alignment of the liquid crystal compound in the positive C layer. When a positive C layer is formed on a vertical alignment film, both the vertical alignment film and the positive C layer may be disposed between the first and second liquid crystal layers, or only the positive C layer may be disposed between the first and second liquid crystal layers. For example, in a transfer film having a substrate, a vertical alignment film, and a positive C layer in this order, if the substrate and the vertical alignment film are designed to form a peel interface, both the vertical alignment film and the positive C layer can be transferred between the first and second liquid crystal layers. Furthermore, if the transfer film is designed to form a peel interface between the vertical alignment film and the positive C layer, only the positive C layer can be transferred between the first and second liquid crystal layers. By adjusting the peel strength of each interface using a release agent or the like, it is possible to design the interface of the transfer film that peels preferentially.

[0071] The positive C layer can be formed between the first and second liquid crystal layers, for example, by the following process: It is preferable to place the positive C layer in the optical element by a transfer method, as shown in the following process. (1) A transfer film having a positive C layer and an adhesive layer on a peelable substrate is prepared. (2) The adhesive layer side of the transfer film is bonded to the first liquid crystal layer, and then the peelable substrate is peeled off to obtain a laminate having the first liquid crystal layer, the adhesive layer, and the positive C layer in this order. (3) A second liquid crystal layer is laminated on the positive C layer of the laminate via an adhesive layer.

[0072] <Other layers> The optical element of the present disclosure may have layers other than the first liquid crystal layer, the positive C layer, and the second liquid crystal layer. Examples of the other layers include a first substrate, a first alignment layer, an adhesive layer, a second substrate, and a second alignment layer. Examples of the other layers include retardation layers other than the positive C layer, such as a positive A layer, a negative A layer, a positive B layer, and a negative B layer.

[0073] <Retardation layers other than the positive C layer> The optical element of the present disclosure may further have one or more layers selected from a positive A layer, a negative A layer, a positive B layer, and a negative B layer between the first liquid crystal layer and the second liquid crystal layer. When the optical element of the present disclosure includes a third liquid crystal layer, it may further include one or more layers selected from a positive A layer, a negative A layer, a positive B layer, and a negative B layer between the first liquid crystal layer and the second liquid crystal layer and / or between the second liquid crystal layer and the third liquid crystal layer. The above configuration makes it possible to adjust the wavelength dispersion, and it is possible to easily increase the diffraction angle over a wide wavelength range, and it is also possible to easily suppress light leakage from oblique directions. The positive A layer, negative A layer, positive B layer and negative B layer may have positive wavelength dispersion or negative wavelength dispersion.

[0074] The positive A layer, negative A layer, positive B layer, and negative B layer can be made of general-purpose materials.

[0075] 《Base material》 The optical element of the present disclosure may have a substrate. For example, the optical element of the present disclosure preferably includes the following configuration 5. By including configuration 5, the first liquid crystal layer can be protected by a first substrate, and the second liquid crystal layer can be protected by a second substrate. Furthermore, by arranging the substrates as in configuration 5, there is no substrate between the first liquid crystal layer and the second liquid crystal layer that can change the phase, which makes it easier for light to interact with the first liquid crystal layer and the second liquid crystal layer. Furthermore, by arranging the substrates as in configuration 5, curling of the optical element can be more easily suppressed. -Configuration 5- A first substrate is provided on the first surface side of the first liquid crystal layer, and a second substrate is provided on the second surface side of the second liquid crystal layer.

[0076] When the optical element of the present disclosure includes the third liquid crystal layer described above, it preferably includes the following configuration 5'. When the optical element includes the following configuration 5', a substrate may or may not be present between the second and third liquid crystal layers. -Configuration 5'- A first substrate is provided on the first surface side of the first liquid crystal layer, and a third substrate is provided on the second surface side of the third liquid crystal layer.

[0077] Various materials can be used as the material constituting the substrate of each substrate, but materials with good mechanical properties, optical properties, stability, and processability are preferred. Such materials include polymer resins having an alicyclic structure, methacrylic resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, polyethersulfone, triacetyl cellulose, polyethylene terephthalate, epoxy acrylate, urethane acrylate, and other resins; glass; and the like, with resins being preferred. That is, each substrate is preferably a resin substrate. The in-plane retardation of each substrate is preferably 20 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, even more preferably 1 nm or less, and most preferably 0 nm. In this specification, the wavelength of light serving as the reference for the refractive index and retardation is 550 nm unless otherwise specified.

[0078] The thickness of each substrate can be adjusted appropriately within the range of 5 μm to 1000 μm. The thickness of the substrate can be measured using a film thickness measuring device. Examples of film thickness measuring devices include Mitutoyo's Digimatic Standard Outside Micrometer (product number: MDC-25SX). The thickness of the substrate can be measured at any 10 points, and the average value should be the above-mentioned value.

[0079] Each substrate preferably has a total light transmittance according to JIS K7361-1:1997 of 70% or more, more preferably 80% or more, and even more preferably 85% or more. Each substrate preferably has a haze according to JIS K7136:2000 of 5% or less, more preferably 3% or less, and even more preferably 1% or less.

[0080] When an alignment layer is provided between the substrate and the liquid crystal layer, it is preferable that the refractive index of the alignment layer and the refractive index of the substrate are close to each other in order to suppress light refraction. Specifically, the refractive index of the alignment layer / the refractive index of the substrate is preferably 0.97 or more and 1.03 or less, and more preferably 0.99 or more and 1.01 or less. When an alignment layer is provided between the substrate and the liquid crystal layer, a primer layer may be provided between the substrate and the alignment layer.

[0081] <<Alignment layer>> The optical element of the present disclosure may have an alignment layer. For example, when the optical element of the present disclosure has the above-described configuration 5, it preferably has the following configuration 6. By having the configuration 6, it becomes easier for the first liquid crystal layer and the second liquid crystal layer to have the above-described alignment region.

[0082] -Configuration 6- A first alignment layer is provided between the first substrate and the first liquid crystal layer, and a second alignment layer is provided between the second substrate and the second liquid crystal layer.

[0083] When the optical element of the present disclosure has the above-described configuration 5', it preferably has the following configuration 6'. By having the configuration 6', it becomes easier for the first liquid crystal layer and the third liquid crystal layer to have the above-described alignment region. -Configuration 6'- A first alignment layer is provided between the first substrate and the first liquid crystal layer, and a third alignment layer is provided between the third substrate and the third liquid crystal layer.

[0084] Examples of the alignment layer include a rubbed layer, a patterned layer, and a photo-aligned layer, of which the patterned layer and the photo-aligned layer are preferred.

[0085] (Pattern layer) The pattern layer has recesses on the side that contacts the liquid crystal layer, and the pattern layer can easily align the liquid crystal molecules of the liquid crystal layer along the extending direction of the recesses.

[0086] The recesses in the pattern layer are preferably arranged so that the extending direction of the recesses changes stepwise by 180 degrees, which is the direction of a tangent drawn to the shape of the recesses in a plan view. Reference numeral 211 in Figures 5(a) and 5(b) corresponds to the recessed portion. In Figures 5(a) and 5(b), the extending direction of the recessed portion changes stepwise by 180 degrees in the region of reference numeral W1. The recesses in the pattern layer may be continuous over a predetermined length as shown in Figure 5(a), or may be divided into small sections as shown in Figure 5(b), where adjacent recesses are spaced apart by a small distance.

[0087] The arrangement pattern of the recesses in the pattern layer may be designed to match the desired arrangement pattern of the liquid crystal molecules in the liquid crystal layer. The length of the recesses in the pattern layer in the uniaxial direction and the depth of the recesses may be adjusted appropriately within a range that allows the liquid crystal molecules to be easily aligned along the extending direction of the recesses.

[0088] The pattern layer can be formed, for example, by shaping the unshaped pattern layer using a plate having a shape complementary to the surface shape of the pattern layer. More specifically, the pattern layer can be formed, for example, by the following steps 1 and 2.

[0089] Step 1: A step of applying a coating liquid for forming a pattern layer containing a resin onto a substrate to form a layer containing a resin. Step 2: A step of shaping a layer containing a resin using a plate having a shape complementary to the surface shape of the pattern layer.

[0090] When the coating liquid for forming a patterned layer contains a solvent, it is preferable to dry the solvent in step 1.

[0091] The resin for the pattern layer is preferably a curable resin, and general-purpose curable resins such as thermosetting resins and ionizing radiation curable resins can be used as the curable resin. When a curable resin is used as the resin, it is preferable to use a pattern layer-forming coating liquid containing a curable resin composition as the pattern layer-forming coating liquid in step 1. That is, when a curable resin is used as the resin, it is preferable that the curable resin in the coating liquid in step 1 is in an uncured state. When a coating liquid for forming a pattern layer containing an ionizing radiation curable resin composition is used as the coating liquid for forming a pattern layer in step 1, it is preferable to irradiate the layer with ionizing radiation simultaneously with the shaping in step 2 to cure the ionizing radiation curable resin composition contained in the shaped layer.

[0092] The plate used in step 2 can be produced by general-purpose means such as laser lithography, electron beam lithography, or focused ion beam. The uneven shape to be formed on the surface of the plate can be designed using general-purpose simulation software. It is also preferable to produce many plates by duplicating the plate produced by the above-mentioned means and arranging the many duplicated plates to form a multi-faceted plate. Plate duplication can be carried out by general-purpose means such as electroforming. The shape of the plate may be flat, cylindrical, etc. A cylindrical plate is preferred in that it can be processed by roll-to-roll and has excellent productivity.

[0093] (photo alignment layer) The photo-alignment layer can be formed, for example, by irradiating a photo-alignment material with polarized or unpolarized light. The polarized light can be irradiated perpendicularly or obliquely to the photo-alignment layer, and the unpolarized light can be irradiated obliquely to the photo-alignment layer.

[0094] The photo-alignment layer can be patterned, for example, by the following methods (1) and (2). (1) A method of exposing an alignment layer using a polarizing mask patterned into a predetermined pattern. Examples of the polarizing mask include a wire-grid polarizing mask. During exposure, the alignment layer and the polarizing mask are preferably in close contact with each other. The ultraviolet light used for exposure is preferably parallel light. (2) A method in which the alignment layer is exposed to polarized laser light. By changing the polarization direction of the laser at each location on the alignment layer, the alignment direction can be patterned into a specific pattern.

[0095] Examples of photo-alignment materials include photoisomerization-type and photodimerization-type resins. Examples of photodimerization-type resins include resins having structures such as cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleimide, and cinnamylideneacetic acid derivatives. Examples of photoisomerization-type resins include resins containing azo compounds.

[0096] The thickness of the pattern layer and the alignment layer such as the photoalignment layer may be adjusted appropriately depending on the purpose.

[0097] 《Adhesive layer》 The optical element of the present disclosure may have an adhesive layer. The adhesive layer is disposed, for example, between the first liquid crystal layer and the positive C layer, and between the positive C layer and the second liquid crystal layer.

[0098] The adhesive layer may be a general-purpose adhesive layer such as a pressure-sensitive adhesive layer, a heat-sensitive adhesive layer, or a curable adhesive layer. The thickness of the adhesive layer may be adjusted appropriately depending on the purpose.

[0099] <Application> The optical element of the present disclosure can be used, for example, as a diffractive optical element, and can also be used as a component of a light control device. The diffraction angle of light transmitted through a diffractive optical element can be adjusted to a predetermined range. Therefore, for example, by using a diffractive optical element, it is possible to widen or narrow the irradiation range of light. In addition, by using a diffractive optical element, it is possible to impart directionality to light. Furthermore, by causing the light beams transmitted through the diffractive optical element to interfere with each other, it is possible to produce the effects of a lens, a prism, or the like. Due to the above-mentioned effects, the diffractive optical element can be used as a component of devices such as cross reality devices, optical sensors, and laser projectors.

[0100] [Device] The device of the present disclosure includes the optical element of the present disclosure described above.

[0101] Examples of the device include a display device such as a cross reality device, an optical sensor, and a laser projector.

[0102] [Method of manufacturing optical elements] The optical element of the present disclosure described above can be manufactured, for example, by the following first to third steps. First step: preparing a first laminate having a first liquid crystal layer on a first substrate, and a second laminate having a second liquid crystal layer on a second substrate, wherein the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction, and the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the predetermined in-plane direction. Second step: A step of obtaining a first' laminate by laminating a first adhesive layer, a positive C layer, and a second adhesive layer on the first liquid crystal layer of the first laminate. Third step: A step of integrating the first' laminate and the second laminate by bonding the surface of the first' laminate facing the second adhesive layer to the surface of the second laminate facing the second liquid crystal layer.

[0103] In the first step, the first laminate preferably has a first alignment layer between the first substrate and the first liquid crystal layer, and the second laminate preferably has a second alignment layer between the second substrate and the second liquid crystal layer.

[0104] The second step is preferably carried out using a transfer film containing a positive C layer. For example, the second step can be carried out according to the following steps (2-1) to (2-4). (2-1) A transfer film having, in this order, a peelable first substrate, a first adhesive layer, a positive C layer, a second adhesive layer, and a peelable second substrate is prepared. (2-2) The releasable first substrate is peeled off from the transfer film. (2-3) The first adhesive layer exposed by peeling off the releasable first substrate is bonded onto the first liquid crystal layer of the first laminate. (2-4) The releasable second substrate is peeled off.

[0105] The transfer film used in (2-1) above can be produced, for example, by the following means d1 to d4. In d3, a positive C layer may be formed by applying a coating liquid for forming a positive C layer onto the first adhesive layer of the first member and drying it. Alternatively, in d3, a positive C layer may be formed by transferring a positive C layer formed on another member onto the first adhesive layer of the first member. d1: A first member is prepared by forming a first adhesive layer on a releasable first substrate. d2: A second member is prepared by forming a second adhesive layer on a second peelable substrate. d3: A positive C layer is formed on the first adhesive layer of the first member. d4: The second adhesive layer of the second member is attached onto the positive C layer.

[0106] The disclosure is as follows: <1> ~ <13> Includes. <1> An optical element, the optical element has a first surface and a second surface opposite to the first surface, and has a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface; the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; An optical element having a positive C layer between the first liquid crystal layer and the second liquid crystal layer. <2> the predetermined direction of the first liquid crystal layer is one specific direction of the first liquid crystal layer, the predetermined direction of the second liquid crystal layer is one specific direction of the second liquid crystal layer, and the one specific direction of the first liquid crystal layer and the one specific direction of the second liquid crystal layer are substantially the same direction; <1> The optical element according to claim 1. <3> When the length until the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes stepwise by 180 degrees is defined as P1, P1 becomes shorter stepwise from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction, When the length until the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer changes stepwise by 180 degrees is defined as P2, P2 becomes shorter stepwise from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction. <2> The optical element according to claim 1. <4> the predetermined direction of the first liquid crystal layer is a multi-direction that is radially aligned with the center of the arrangement pattern of the liquid crystal molecules, and the predetermined direction of the second liquid crystal layer is a multi-direction that is radially aligned with the center of the arrangement pattern of the liquid crystal molecules. <1> The optical element according to claim 1. <5> When the length until the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes stepwise by 180 degrees is defined as P1, P1 becomes shorter stepwise from the central alignment region toward the outer alignment region, When the length over which the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer changes stepwise by 180 degrees is defined as P2, P2 becomes shorter stepwise from the central alignment region toward the outer alignment regions. <4> The optical element according to claim 1. <6> The liquid crystal display further comprises one or more layers selected from a positive A layer, a negative A layer, a positive B layer, and a negative B layer between the first liquid crystal layer and the second liquid crystal layer. <1> ~ <5> 10. The optical element according to claim 9, wherein the optical element is a reflective optical element. <7> a first substrate on the first surface side of the first liquid crystal layer, and a second substrate on the second surface side of the second liquid crystal layer; <1> ~ <6> 10. The optical element according to claim 9, wherein the optical element is a reflective optical element. <8> a first alignment layer between the first substrate and the first liquid crystal layer, and a second alignment layer between the second substrate and the second liquid crystal layer; <7> The optical element according to claim 1. <9> a third liquid crystal layer, the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer being arranged in this order from the first surface to the second surface; the third liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; a positive C layer between the second liquid crystal layer and the third liquid crystal layer; <1> ~ <8> 10. The optical element according to claim 9, wherein the optical element is a reflective optical element. <10> The optical element has layers from the first surface to the second surface that are tightly adhered to each other and integrated together. <1> ~ <9> 10. The optical element according to claim 9, wherein the optical element is a reflective optical element. <11> an adhesive layer is provided between the first liquid crystal layer and the positive C layer and / or between the positive C layer and the second liquid crystal layer; <10> The optical element according to claim 1. <12> <1> ~ <11> An apparatus comprising the optical element according to any one of the above. <13> The method comprises the following first to third steps: <1> ~ <11> 10. A method for manufacturing the optical element according to any one of the above. First step: preparing a first laminate having a first liquid crystal layer on a first substrate, and a second laminate having a second liquid crystal layer on a second substrate. The first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along the predetermined in-plane direction. Second step: A step of obtaining a first' laminate by laminating a first adhesive layer, a positive C layer, and a second adhesive layer on the first liquid crystal layer of the first laminate. Third step: A step of integrating the first' laminate and the second laminate by bonding the surface of the first' laminate facing the second adhesive layer to the surface of the second laminate facing the second liquid crystal layer. [Example]

[0107] Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples. Note that "parts" and "%" are based on mass unless otherwise specified.

[0108] 1. Measurement and Evaluation The optical elements of the examples and comparative examples were subjected to the following measurements and evaluations. The atmosphere during each measurement and evaluation was set to a temperature of 23±5°C and a relative humidity of 40% to 65%. Before starting each measurement and evaluation, the target sample was exposed to the above atmosphere for 30 to 60 minutes, and then the measurement and evaluation were carried out.

[0109] 1-1. Light leakage and diffraction efficiency (1) Light leakage rate at 0 degrees incidence A laser light source 61, a polarizing plate 62, a λ / 4 retardation plate 63, the optical elements 100 of the examples and comparative examples, and a detector 64 were arranged in the order shown in FIG. 6(a). The detector 64 was equipped with an integrating sphere, and the angle of the opening of the integrating sphere relative to the direction of laser light irradiation could be varied. When the angle of the opening relative to the direction of laser light irradiation was perpendicular, the angle between the point of incidence of the laser light on the optical element and the radius of the opening of the integrating sphere was adjusted to 2 to 3 degrees. The light transmitted through the λ / 4 retardation plate 63 was left-handed circularly polarized light. A laser beam with a wavelength of 532 nm was irradiated perpendicularly to the plane of the polarizing plate in FIG. 6(a), and the intensity of the laser beam that traveled straight was detected by the detector. The intensity of the laser beam at this time was designated the "intensity through the optical element at 0 degrees." Furthermore, the intensity of the laser beam that traveled straight was detected by the detector when the optical element was removed from FIG. 6(a). The intensity of the laser beam at this time was designated the "blank intensity." The percentage (%) of light leakage at 0-degree incidence was calculated using the following formula. The results are shown in Table 2. In Fig. 6, the laser light that travels straight without being diffracted by optical element 100 is not diffracted normally, and can therefore be considered to be laser light leakage. Percentage of light leakage at 0 degrees incidence (%) = (intensity through optical element at 0 degrees / intensity of blank) x 100

[0110] (2) Diffraction efficiency at 0 degrees incidence A laser beam having a wavelength of 532 nm was irradiated perpendicularly to the plane of the polarizing plate in Figure 6(a), and the intensity of the laser beam was measured while changing the angle of the detector 64 relative to the irradiation direction of the laser beam. The angle at which the intensity of the laser beam reached its maximum value in the above measurement was regarded as the diffraction angle at 0 degrees incidence for the optical elements 100 of the example and comparative example. The results are shown in Table 2. The maximum value of the intensity of the laser beam measured in this way was taken as the "intensity of the diffracted laser beam." The diffraction efficiency (%) at 0-degree incidence was calculated from the "intensity of the diffracted laser light" and the "blank intensity" in (1) above using the following formula. The results are shown in Table 2. Diffraction efficiency at 0 degrees incidence (%) = (diffracted laser light intensity / blank intensity) x 100

[0111] (3) Light leakage rate at 30 degrees incidence The laser light source 61, polarizing plate 62, λ / 4 retardation plate 63, optical elements 100 of the examples and comparative examples, and detector 64 were arranged in the same manner as in FIG. 6(a), except that the optical element 100 was tilted as shown in FIG. 6(b). "θ" in FIG. 6(b) was set to 30 degrees. A laser beam with a wavelength of 532 nm was irradiated in a direction perpendicular to the plane of the polarizing plate in FIG. 6(b), and the intensity of the laser beam that traveled straight ahead was detected by the detector. The intensity of the laser beam at this time was defined as "intensity through the optical element at 30 degrees." The percentage of light leakage at 30 degrees incidence was calculated using the "intensity through the optical element at 30 degrees" and the "blank intensity" in (1) above, using the following formula. The results are shown in Table 2. Light leakage rate at 30 degrees incidence (%) = (intensity through 30-degree optical element / blank intensity) x 100

[0112] 1-2. Orientation The alignment of the first liquid crystal layer of the optical elements of the examples and comparative examples was evaluated according to the following criteria. A polarizing microscope was used for the evaluation. The area observed was 25 μm × 25 μm. The smaller the Schlieren texture, the better the alignment of the liquid crystal molecules. Note that some of the optical elements of the examples and comparative examples have a second liquid crystal layer and a third liquid crystal layer, but since the first to third liquid crystal layers in each example and comparative example have the same configuration, only the alignment of the first liquid crystal layer was evaluated. A: Excluding dust-related causes, the number of Schlieren structures is six or less. B: Excluding dust-related causes, the number of Schlieren structures is between 7 and 15. C: Excluding dust-related causes, the number of Schlieren structures is 16 or more.

[0113] 2. Making the plate <Shape design through simulation> A simulation tool was used to design the recessed portion patterns of the pattern layer, and the following first to fifth recessed portion patterns were designed. First Pattern The recess pattern was a pattern corresponding to the alignment direction 31a of the liquid crystal molecules in Figure 3(a). Although the number of patterns in the X-axis and Y-axis directions is small in Figure 3(a), the number of patterns in the X-axis and Y-axis directions was increased until a sufficient number was reached. In the pattern, the minimum value of the pitch, which is the length over which the extension direction of the recesses changes stepwise by 180 degrees, was 6 μm. The maximum value of the pitch was 300 μm (the maximum pitch value for the second to sixth patterns is also 300 μm). The width of each recess in the minor axis direction was 25 nm, and the depth of each recess was 30 nm. <<Second Pattern>> The second pattern was designed in the same manner as the first pattern, except that the minimum value of the pitch, which is the length over which the extending direction of the recesses changes stepwise by 180 degrees, was changed to 9 μm. "Third Pattern" A third pattern was designed in the same manner as the first pattern, except that the minimum value of the pitch, which is the length over which the extending direction of the recesses changes stepwise by 180 degrees, was changed to 4 μm. "Fourth Pattern" A fourth pattern was designed in the same manner as the first pattern, except that the minimum value of the pitch, which is the length over which the extending direction of the recesses changes stepwise by 180 degrees, was changed to 8 μm. "The fifth pattern" The recess pattern was a pattern corresponding to the alignment direction 31c of the liquid crystal molecules in Figure 4. In this pattern, the minimum value of the pitch, which is the length over which the extension direction of the recesses changes stepwise by 180 degrees, was 6 μm. The width of each recess in the minor axis direction was 25 nm, and the depth of each recess was 30 nm.

[0114] <Making a plate using the above data> <<Creating the first roll-shaped plate>> Using a 6-inch square synthetic quartz plate, a quartz master mold with recesses of the first pattern designed in simulation was created using an electron beam lithography process that uses an electron beam lithography system and a dry etching system. Next, an ultraviolet-curable resin was poured into the master mold, and then a transparent substrate was placed on top of the ultraviolet-curable resin. The resin was then cured by irradiating it with ultraviolet light. The transparent substrate and resin were then peeled off from the master mold to obtain a resin plate having a shape complementary to that of the master mold. Next, electroforming was used to obtain a replica mold of the master mold, which is a mold having a shape complementary to that of the resin plate. Multiple replica molds were produced. Multiple replica molds were wound around a roll to produce a first roll-shaped plate. <<Making the second to fourth roll plates>> The second to fifth roll-shaped plates were obtained in the same manner as the first roll-shaped plate, except that the first pattern was changed to the second to fifth patterns.

[0115] 3. Fabrication of Optical Elements [Example 1] <Preparation of the first laminate> A primer layer having the following formulation was applied onto a substrate (a 40 μm thick cycloolefin polymer, Zeon Corporation's trade name "ZEONOR") and dried to form a primer layer having a thickness of 0.5 μm. Next, a coating liquid for forming a pattern layer having the following formulation was applied onto the primer layer and dried to form a layer containing an uncured resin. Next, using the first roll-shaped plate prepared in "2" above, a layer containing uncured resin was formed, and at the same time, ultraviolet light was irradiated from the substrate side (integrated light amount: 500 mJ / cm 2 ), and the layer containing the shaped resin was cured. Next, the shaped layer was peeled off from the plate to obtain a laminate having a primer layer and a pattern layer on the substrate. The pattern layer corresponds to the alignment layer. Next, the following liquid crystal layer forming coating solution was applied onto the pattern layer, which is the alignment layer, and after drying, ultraviolet light was irradiated (integrated light amount: 150 mJ / cm 2 ), a liquid crystal layer was formed. The liquid crystal layer was formed by two coating processes, using a liquid crystal with an in-plane birefringence (Δn) of 0.17 and adjusting the thickness so that the in-plane retardation at a wavelength of 532 nm was 266 nm. Through the above steps, a first laminate having a substrate, a primer layer, an alignment layer, and a liquid crystal layer in this order was obtained, which was used in Example 1. The substrate, primer layer, alignment layer, and liquid crystal layer of the first laminate used in Example 1 correspond to the first substrate, first primer layer, first alignment layer, and first liquid crystal layer.

[0116] <Preparation of second laminate> The second laminate used in Example 1 was obtained using the same materials and processes as those for the first laminate. The substrate, primer layer, alignment layer, and liquid crystal layer of the second laminate used in Example 1 correspond to the second substrate, second primer layer, second alignment layer, and second liquid crystal layer.

[0117] <Preparing the first transfer film> A first transfer film for use in Example 1 was prepared, having a peelable first substrate, a first adhesive layer, a first positive C layer, a second adhesive layer, and a peelable second substrate in this order. The positive C layer was a homeotropically aligned liquid crystal layer with an in-plane retardation of 0.5 nm and a thickness retardation of −100 nm. The peel strength between the peelable first substrate and the first adhesive layer was smaller than the peel strength between the peelable second substrate and the second adhesive layer. The first positive C layer of the first transfer film was formed by transferring the first positive C layer, which was prepared as follows, onto the first adhesive layer.

[0118] <Preparation of the first positive C layer> As the transparent substrate, E5000 (thickness: 38 μm, PET film) manufactured by Toyobo Co., Ltd. was used. A mixed resin consisting of trimethylolpropane triacrylate and dipentaerythritol hexaacrylate mixed in a 7:3 mass ratio was dissolved in a 1:1 mixed solvent of methyl isobutyl ketone and methyl ethyl ketone to prepare a mixed solution with a solid content of 25%. An initiator was added to the mixed solution in an amount of 4 parts by mass per 100 parts by mass of the solid content, and a surfactant was added in an amount of 0.3 parts by mass per 100 parts by mass of the solid content, to prepare a composition for an alignment film. The initiator used was "Omnirad907" manufactured by IGM, and the surfactant was "Megafac F-477" manufactured by DIC. The composition for alignment film was applied to the transparent substrate with a Mayer bar to a film thickness of 2.5 μm, dried in an oven at 70° C. for 1 minute, and then irradiated with a Fusion-UV (Heraeus) at an irradiation dose of 100 mJ / cm 2 . 2 The resulting solution was then UV-cured to form an alignment film. A liquid crystal material, "RMM28B" manufactured by Merck, was dissolved in a 1:1 mixed solvent of methyl isobutyl ketone and methyl ethyl ketone to prepare a mixed solution with a solid content of 25%. A surfactant was added to the mixed solution in an amount of 0.3 parts by mass per 100 parts by mass of the liquid crystal material to prepare a polymerizable liquid crystal composition. The surfactant used was "Megafac F-477" manufactured by DIC Corporation. Next, the polymerizable liquid crystal composition was applied onto the alignment film using a Mayer bar to a predetermined thickness, and then dried in an oven at 50°C for 1 minute. After that, it was irradiated with a Fusion-UV device manufactured by Heraeus GmbH at an irradiation dose of 300 mJ / cm. 2 The positive C layer was formed by UV curing at 1000 kJ / cm2. The thickness of the positive C layer was adjusted as follows: After forming a positive C layer on the transparent substrate with the alignment film, the positive C layer alone was transferred to a 3 cm square piece of glass with an acrylic adhesive layer to prepare a laminate for measurement. The retardation value of the laminate for measurement was measured at a wavelength of 550 nm using a retardation measurement device (Oji Scientific Instruments, KOBRA-WR), and the retardation value in the thickness direction was adjusted to -100 nm.

[0119] <Laminating> The releasable first substrate was peeled from the first transfer film. Next, the releasable first substrate was peeled off, and the surface of the first transfer film exposed on the first adhesive layer side was placed face-to-face with the surface of the first laminate on the first liquid crystal layer side, and these were then bonded together. Next, the releasable second substrate was peeled off from the first transfer film. Next, the releasable second substrate was peeled off, and the surface of the first transfer film exposed on the second adhesive layer side was placed face-to-face with the surface of the second laminate on the second liquid crystal layer side, and these were then bonded together. Through the above process, an optical element of Example 1 was obtained, which had a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a first positive C layer, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers closely attached and integrated. The first and second liquid crystal layers were arranged so that the directions in which the alignment directions of the liquid crystal molecules change stepwise by 180 degrees were approximately aligned in the planar direction. The misalignment of the alignment regions of the first and second liquid crystal layers in the planar direction was less than 300 μm.

[0120] <<Coating liquid for forming primer layer>> Polyolefin resin: 70 parts by weight (Mitsubishi Chemical Corporation, product name: Surflen P-1000) Silica-based lubricant: 5 parts by weight (Manufactured by CIK Nanotech, product name: SIRMIBK15WT%-E65) Methyl ethyl ketone: 25 parts by weight

[0121] <<Coating liquid for forming pattern layer>> Pentaerythritol triacrylate: 96 parts by mass (Manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) Photopolymerization initiator: 4 parts by mass (IGM, product name: Omnirad184)

[0122] <<Liquid crystal layer forming coating liquid>> ·Rod-shaped liquid crystal molecules: 10 parts by mass (7:3 mixture of liquid crystal manufactured by Tokyo Chemical Industry Co., Ltd. (CAS RN: 132900-75-5, product code: D5936) and liquid crystal manufactured by BASF (Paliocolor LC1057 (product name)). In-plane birefringence (Δn) = 0.17) Photopolymerization initiator: 0.4 parts by mass (IGM, product name: Omnirad184) Methyl ethyl ketone: 89.6 parts by mass

[0123] [Example 2] An optical element of Example 2 was obtained in the same manner as in Example 1, except that the in-plane retardation and thickness direction retardation of the positive C layer of the first transfer film were changed to the values ​​shown in Table 2.

[0124] [Example 3] An optical element of Example 3 was obtained in the same manner as in Example 1, except that the in-plane retardation and thickness direction retardation of the positive C layer of the first transfer film were changed to the values ​​shown in Table 2.

[0125] [Example 4] <Preparation of the first laminate> The first laminate used in Example 4 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to the second roll-shaped plate. <Preparation of second laminate> The second laminate used in Example 4 was obtained using the same materials as those used in the first laminate of Example 4 and through the same steps as those used in the first laminate of Example 4. <Preparation of the third laminate> A third laminate used in Example 4 was obtained using the same materials and processes as those for the first laminate in Example 4. The substrate, primer layer, alignment layer, and liquid crystal layer of the third laminate used in Example 4 correspond to a third substrate, a third primer layer, a third alignment layer, and a third liquid crystal layer. <Preparing the first transfer film> As the first transfer film used in Example 4, a film similar to the first transfer film in Example 1 was prepared. <Preparing the second transfer film> A second transfer film similar to the first transfer film of Example 1 was prepared as the second transfer film used in Example 4. The second transfer film had, in this order, a peelable first substrate, a third adhesive layer, a second positive C layer, a fourth adhesive layer, and a peelable second substrate. <Laminating> The releasable first substrate was peeled from the first transfer film. Next, the releasable first substrate was peeled off, and the surface of the first transfer film exposed on the first adhesive layer side was placed face-to-face with the surface of the first laminate on the first liquid crystal layer side, and these were then bonded together. Next, the releasable second substrate was peeled off from the first transfer film. Next, the releasable second substrate was peeled off, and the surface of the first transfer film exposed on the second adhesive layer side was placed face-to-face with the surface of the second laminate on the second liquid crystal layer side, and these were then bonded together. Next, the releasable first substrate was peeled from the second transfer film. Next, the surface of the second transfer film exposed by peeling the releasable first substrate, facing the third adhesive layer side, was bonded to the surface of the second laminate facing the second substrate side. Next, the releasable second substrate of the second transfer film was peeled. Next, the surface of the second transfer film exposed by peeling the releasable second substrate, facing the fourth adhesive layer side, was bonded to the surface of the third laminate facing the third liquid crystal layer side. The above process resulted in the production of an optical element of Example 4, which had the following layers in this order: a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a first positive C layer, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, a second substrate, a third adhesive layer, a second positive C layer, a fourth adhesive layer, a third liquid crystal layer, a third alignment layer, a third primer layer, and a third substrate, with these layers tightly adhered and integrated. The first, second, and third liquid crystal layers were arranged such that the directions in which the liquid crystal molecules were aligned in a stepwise 180-degree increment were approximately aligned in the planar direction. The misalignment of the alignment regions of the first to third liquid crystal layers in the planar direction was less than 300 μm.

[0126] [Example 5] <Preparation of the fourth laminate> A fourth laminate used in Example 5 was obtained using the same materials and processes as those for the first laminate in Example 4. The substrate, primer layer, alignment layer, and liquid crystal layer of the fourth laminate used in Example 5 correspond to a fourth substrate, a fourth primer layer, a fourth alignment layer, and a fourth liquid crystal layer. <Preparing the third transfer film> A third transfer film similar to the first transfer film of Example 1 was prepared as the third transfer film used in Example 5. The third transfer film had, in this order, a peelable first substrate, a fifth adhesive layer, a second positive C layer, a sixth adhesive layer, and a peelable second substrate. <Laminating> The releasable first substrate was peeled from the third transfer film. Next, the surface of the third transfer film exposed by peeling the releasable first substrate, which was on the fifth adhesive layer side, was placed opposite the surface of the optical element of Example 4 on the third substrate side, and these were then bonded together. Next, the releasable second substrate of the third transfer film was peeled off. Next, the surface of the third transfer film exposed by peeling the releasable second substrate, which was on the sixth adhesive layer side, was placed opposite the surface of the fourth laminate on the fourth liquid crystal layer side, and these were then bonded together. The above process resulted in the production of an optical element of Example 5, which had the following layers in this order: a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a first positive C layer, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, a second substrate, a third adhesive layer, a second positive C layer, a fourth adhesive layer, a third liquid crystal layer, a third alignment layer, a third primer layer, a third substrate, a fifth adhesive layer, a third positive C layer, a sixth adhesive layer, a fourth liquid crystal layer, a fourth alignment layer, a fourth primer layer, and a fourth substrate, with these layers tightly adhered and integrated. The first, second, third, and fourth liquid crystal layers were arranged such that the directions in which the liquid crystal molecules were aligned in a stepwise 180-degree increment were approximately aligned in the planar direction. The misalignment of the alignment regions of the first to fourth liquid crystal layers in the planar direction was less than 300 μm.

[0127] [Example 6] Except for using the following first transfer film as the first transfer film, the optical element of Example 6 was obtained in the same manner as in Example 1. The optical element of Example 6 has, in this order, a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a first positive C layer, an adhesive layer, a positive A layer, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, and a second substrate, and these layers are tightly adhered and integrated. <Preparing the first transfer film> A first transfer film for Example 6 was prepared, having, in this order, a peelable first substrate, a first adhesive layer, a first positive C layer, an adhesive layer, a positive A layer with positive wavelength dispersion, a second adhesive layer, and a peelable second substrate. The positive C layer is a homeotropically aligned liquid crystal layer. The combined in-plane retardation of the positive A layer and the first positive C layer was 256 nm, and the thickness direction retardation was −200 nm (thickness direction retardation of the first positive C layer: −330 nm, thickness direction retardation of the positive A layer: 130 nm). The peel strength between the peelable first substrate and the first adhesive layer was less than the peel strength between the peelable second substrate and the second adhesive layer. The first positive C layer of the first transfer film was formed by transferring the first positive C layer prepared in the same manner as in Example 1 onto the first adhesive layer (however, the first positive C layer was prepared so that the retardation in the thickness direction was −330 nm). The positive A layer of the first transfer film was formed by transferring the positive A layer prepared as follows onto the adhesive layer.

[0128] <Preparation of the first positive A layer> As a transparent substrate, Cosmoshine Super Birefringent Film (SRF) (thickness: 80 μm, PET film) manufactured by Toyobo Co., Ltd. was used. A propylene glycol monomethyl ether solution (solid content 4.5%) of a composition for a photo-alignment film containing a polycinnamate compound was applied to the non-primer-treated surface of the transparent substrate using a Mayer bar to a film thickness of 300 nm, and then dried in an oven at 100°C for 1 minute. The resulting film was then irradiated with a 310 nm wavelength and 20 mJ / cm dose.2 The film was exposed to polarized light at 1000 W ... A mixture of the following compounds was used as the liquid crystal material. Four parts by mass of initiator and 0.3 parts by mass of surfactant were added to 100 parts by mass of the liquid crystal material, and the mixture was then dissolved in a 1:1 mixed solvent of methyl ethyl ketone and methyl isobutyl ketone to prepare a polymerizable liquid crystal composition with a solids content of 25%. The initiator used was "Omnirad907" manufactured by IGM, and the surfactant was "Megafac F-477" manufactured by DIC. Next, the polymerizable liquid crystal composition was applied to the photo-alignment film using a Mayer bar to a predetermined thickness, and then dried in an oven at 100°C for 1 minute. After that, it was irradiated with a Fusion-UV device manufactured by Heraeus GmbH at an irradiation dose of 300 mJ / cm. 2 The coating was then UV cured to form a positive A layer. (Liquid crystal material used in the positive A layer)

[0129] [ka]

[0130] [Example 7] Except for using the following first transfer film as the first transfer film, the optical element of Example 7 was obtained in the same manner as in Example 1. The optical element of Example 7 has, in this order, a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a first positive C layer, two positive A layers, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, and a second substrate, and these layers are tightly adhered and integrated. <Preparing the first transfer film> A first transfer film for use in Example 7 was prepared, having, in this order, a peelable first substrate, a first adhesive layer, a first positive C layer, an adhesive layer, two positive A layers with negative wavelength dispersion, a second adhesive layer, and a peelable second substrate. The positive C layer is a homeotropically aligned liquid crystal layer. The combined in-plane retardation of the two positive A layers and the first positive C layer is 290 nm, and the thickness retardation is -200 nm. The peel strength between the peelable first substrate and the first adhesive layer is less than the peel strength between the peelable second substrate and the second adhesive layer. The first positive C layer of the first transfer film was formed by transferring the first positive C layer, which was prepared in the same manner as in Example 1, onto the first adhesive layer (however, the first positive C layer was adjusted so that the phase difference in the thickness direction was −400 nm). Two "Pure Ace RM" (trade name) Teijin Co., Ltd. positive A layers with negative wavelength dispersion and an in-plane retardation of 145 nm and a thickness retardation of 100 nm were used. The positive A layers were formed on the first positive C layer via an adhesive layer. There were two positive A layers, and an adhesive layer was also provided between each of the positive A layers.

[0131] [Example 8] An optical element of Example 8 was obtained in the same manner as in Example 1, except that the following first laminate and second laminate were used as the first laminate and second laminate. The first liquid crystal layer and the second liquid crystal layer were aligned in a direction in which the alignment direction of the liquid crystal molecules changed stepwise by 180 degrees, and the misalignment in the planar direction of the alignment regions of the first and second liquid crystal layers was less than 300 μm. <Preparation of the first laminate> The first laminate used in Example 8 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a third roll-shaped plate. <Preparation of second laminate> A second laminate used in Example 8 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fourth roll-shaped plate.

[0132] [Example 9] An optical element of Example 9 was obtained in the same manner as in Example 1, except that the following first laminate and second laminate were used as the first laminate and second laminate. The first liquid crystal layer and the second liquid crystal layer were arranged so that the directions in which the alignment directions of the liquid crystal molecules change stepwise by 180 degrees were approximately aligned in the planar direction. The misalignment in the planar direction of the alignment regions of the first and second liquid crystal layers was set to less than 300 μm. <Preparation of the first laminate> The first laminate used in Example 9 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to the fifth roll-shaped plate. <Preparation of second laminate> The second laminate used in Example 9 was obtained using the same materials and processes as those for the first laminate in Example 9. The substrate, primer layer, alignment layer, and liquid crystal layer of the second laminate used in Example 9 correspond to the second substrate, second primer layer, second alignment layer, and second liquid crystal layer.

[0133] [Comparative Example 1] The surface of the first laminate of Example 1 facing the first liquid crystal layer and the surface of the second laminate of Example 1 facing the second liquid crystal layer were laminated via an adhesive layer to obtain an optical element of Comparative Example 1. The optical element of Comparative Example 1 had a first substrate, a first primer layer, a first alignment layer, a first liquid crystal layer, an adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, and a second substrate, in this order, and these layers were tightly adhered and integrated. The first liquid crystal layer and the second liquid crystal layer had a direction in which the alignment direction of the liquid crystal molecules changed stepwise by 180 degrees that was approximately aligned in the planar direction. The misalignment of the alignment regions of the first and second liquid crystal layers in the planar direction was less than 300 μm.

[0134] Comparative Example 2 The first laminate of Example 1 was used as the optical element of Comparative Example 2.

[0135] Comparative Example 3 An optical element of Comparative Example 3 was obtained in the same manner as in Example 1, except that the first transfer film described below was used as the first transfer film. The optical element of Comparative Example 3 had a first primer layer, a first alignment layer, a first liquid crystal layer, a first adhesive layer, a positive A layer, a second adhesive layer, a second liquid crystal layer, a second alignment layer, a second primer layer, and a second base material, in this order, and these layers were closely attached and integrated. The first liquid crystal layer and the second liquid crystal layer had alignment regions, in which the alignment direction of the liquid crystal molecules changed stepwise by 180 degrees, that were approximately aligned in the planar direction. The misalignment of the alignment regions of the first and second liquid crystal layers in the planar direction was less than 300 μm. <Preparing the first transfer film> A first transfer film for use in Comparative Example 3 was prepared, which had, in this order, a peelable first substrate, a first adhesive layer, a positive A layer having positive wavelength dispersion, a second adhesive layer, and a peelable second substrate. The positive A layer had an in-plane retardation of 256 nm. The peel strength between the peelable first substrate and the first adhesive layer was smaller than the peel strength between the peelable second substrate and the second adhesive layer. The positive A layer of the first transfer film was formed by transferring the positive A layer prepared in the same manner as in Example 6 onto the first adhesive layer.

[0136] [Table 2]

[0137] Note 1: In Table 2, "Re" indicates the in-plane retardation, and "Rth" indicates the retardation in the thickness direction. Note 2: In Table 2, "Retardation value of retardation layer" indicates the retardation of the positive C layer alone in Examples 1 to 5, 8, and 9, the combined retardation of the positive A layer and the positive C layer in Examples 6 and 7, and the retardation of the positive A layer alone in Comparative Example 3.

[0138] As shown in Table 2, it can be confirmed that the optical elements of the examples can increase the diffraction angle at 0-degree incidence. Also, as shown in Table 2, it can be confirmed that the optical elements of the examples can suppress light leakage at an oblique angle of 30 degrees incidence. Thus, from the results of the examples, it can be confirmed that the optical elements of the present disclosure can increase the diffraction angle and suppress light leakage from oblique directions. [Explanation of symbols]

[0139] 10a: First side 10b: Second side 11: First substrate 12: Second substrate 21: First alignment layer 22: Second alignment layer 31: First liquid crystal layer 32: Second liquid crystal layer 41, 42: Adhesive layer 51: Positive C layer 100: Optical elements

Claims

1. An optical element, the optical element has a first surface and a second surface opposite to the first surface, and has a first liquid crystal layer and a second liquid crystal layer in this order from the first surface to the second surface, the first liquid crystal layer has a plurality of alignment regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; the second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; An optical element comprising a positive C layer between the first liquid crystal layer and the second liquid crystal layer.

2. 2. The optical element of claim 1, wherein the predetermined direction of the first liquid crystal layer is a specific direction of the first liquid crystal layer, the predetermined direction of the second liquid crystal layer is a specific direction of the second liquid crystal layer, and the specific direction of the first liquid crystal layer and the specific direction of the second liquid crystal layer are approximately the same direction.

3. When a length P1 is defined as a length until the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes stepwise by 180 degrees, P1 becomes shorter stepwise from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction, The optical element described in claim 2, wherein when P2 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer changes gradually by 180 degrees, P2 gradually shortens from the alignment region at one end in the specific direction to the alignment region at the other end in the specific direction.

4. 2. The optical element according to claim 1, wherein the predetermined direction of the first liquid crystal layer is a radial direction in multiple directions relative to the center of the arrangement pattern of the liquid crystal molecules, and the predetermined direction of the second liquid crystal layer is a radial direction in multiple directions relative to the center of the arrangement pattern of the liquid crystal molecules.

5. When a length P1 is defined as a length until the alignment direction of the liquid crystal molecules in the alignment region of the first liquid crystal layer changes stepwise by 180 degrees, P1 becomes shorter stepwise from the central alignment region toward the outer alignment region, The optical element described in claim 4, wherein when P2 is defined as the length over which the alignment direction of the liquid crystal molecules in the alignment region of the second liquid crystal layer gradually changes by 180 degrees, P2 gradually becomes shorter from the central alignment region to the outer alignment regions.

6. 2. The optical element according to claim 1, further comprising one or more layers selected from a positive A layer, a negative A layer, a positive B layer, and a negative B layer between the first liquid crystal layer and the second liquid crystal layer.

7. The optical element according to claim 1 , further comprising a first substrate on the first surface side of the first liquid crystal layer, and a second substrate on the second surface side of the second liquid crystal layer.

8. 8. The optical element according to claim 7, comprising a first alignment layer between the first substrate and the first liquid crystal layer, and a second alignment layer between the second substrate and the second liquid crystal layer.

9. a third liquid crystal layer, the first liquid crystal layer, the second liquid crystal layer, and the third liquid crystal layer being arranged in this order from the first surface to the second surface; the third liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction; The optical element according to claim 1 , further comprising a positive C layer between the second liquid crystal layer and the third liquid crystal layer.

10. The optical element according to claim 1 , wherein the layers from the first surface to the second surface of the optical element are tightly adhered and integrated.

11. The optical element according to claim 10 , further comprising an adhesive layer between the first liquid crystal layer and the positive C layer and / or between the positive C layer and the second liquid crystal layer.

12. An apparatus comprising an optical element according to any one of claims 1 to 11.

13. 2. A method for producing an optical element according to claim 1, comprising the following first to third steps: First step: preparing a first laminate having a first liquid crystal layer on a first substrate, and a second laminate having a second liquid crystal layer on a second substrate. The first liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. The second liquid crystal layer has a plurality of alignment regions in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined in-plane direction. Second step: A step of obtaining a first' laminate by laminating a first adhesive layer, a positive C layer, and a second adhesive layer on the first liquid crystal layer of the first laminate. Third step: A step of integrating the first' laminate and the second laminate by bonding the surface of the first' laminate facing the second adhesive layer to the surface of the second laminate facing the second liquid crystal layer.

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