Optical element

Abstract

Provided is an optical element in which the orientation of liquid crystal molecules is favorable and with which sufficient optical element performance can be obtained. This optical element includes a pattern layer and a liquid crystal layer. The pattern layer has a first surface and a second surface opposite to the first surface. The liquid crystal layer is formed on the first surface of the pattern layer. The pattern layer has a plurality of recesses of a first shape in the first surface. The recesses of the first shape have an arc shape in a plan view. The recesses of the first shape are arranged continuously at a prescribed pitch in a first direction in the first surface, and the recesses of the first shape adjacent in the first direction have ends joined to each other. The joining points of the recesses of the first shape satisfy a prescribed condition.

Description

Optical elements

[0001] The present disclosure relates to optical elements.

[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. Furthermore, in recent years, development of devices equipped with optical sensors has progressed in the fields of personal authentication and automated vehicle driving. 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.

[0004] Known optical element configurations include a configuration in which a liquid crystal layer is provided on a pattern layer having a predetermined pattern (Patent Documents 1 and 2).

[0005] International Publication No. 2018 / 038260 Japanese Patent Application Laid-Open No. 2022-147451

[0006] The pattern layer of the optical element of Patent Document 1 has a configuration in which the pattern angle of the pattern layer changes stepwise. That is, the optical element of Patent Document 1 has many contact areas where the pattern angle changes suddenly. At these contact areas, alignment defects of liquid crystal molecules are likely to occur, making it difficult for the optical element to exhibit sufficient performance. Thus, the optical element of Patent Document 1 has the problem of having many contact areas where alignment defects of liquid crystal molecules are likely to occur.

[0007] The pattern layer of the optical element of Patent Document 2 has a plurality of arc-shaped patterns, with a gap between adjacent patterns. The optical element of Patent Document 2 can have a longer length for each pattern than the pattern layer of Patent Document 1. However, the optical element of Patent Document 2 has a problem in that adjacent patterns are separated by a gap, making it difficult for liquid crystal molecules to align in the gap.

[0008] The inventors of the present invention investigated a configuration in which the pattern of the pattern layer is arc-shaped and adjacent patterns are joined together to facilitate alignment of the liquid crystal molecules. However, when adjacent patterns are simply joined together, the performance of the optical element does not reach the theoretical value, and there are many cases in which sufficient performance cannot be obtained. As a result of further research, the inventors of the present invention have completed an optical element that has good alignment of the liquid crystal molecules and can achieve sufficient performance as an optical element.

[0009] The present disclosure provides the following [1] to [9]. [1] An optical element comprising: a patterned layer and a liquid crystal layer; the patterned layer has a first surface and a second surface opposite to the first surface; the liquid crystal layer is formed on the first surface of the patterned layer; the patterned layer has a plurality of recesses of a first shape in the first surface; the recesses of the first shape have an arc shape in a plan view; the recesses of the first shape are arranged continuously at a predetermined pitch in a first direction in the first surface, and adjacent recesses of the first shape in the first direction have ends joined to each other; and the recesses of the first shape satisfy the following conditions 1 and 2: <Condition 1> The angle formed by a tangent to the arc shape of the recesses of the first shape and a line parallel to the first direction is defined as the local angle of the recesses of the first shape. The first-shape recess has a minimum local angle greater than -90.0 degrees and equal to or less than -80.0 degrees, a maximum local angle greater than or equal to +80.0 degrees and less than +90.0 degrees, and the local angle changes continuously from the minimum to the maximum. <Condition 2> A direction perpendicular to the first direction is defined as a second direction, a direction in the second direction in which the arc of the arc shape is convex is defined as a second' direction, a point where ends of adjacent first-shape recesses are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the second' direction is defined as a point M. The intersections of a straight line drawn from point M in the first direction with one first-shape recess and the other first-shape recess that form the junction point X are defined as intersection points Y and Z, respectively. The average angle formed by the first line connecting the junction point X and the intersection point Y and the second line connecting the junction point X and the intersection point Z is greater than 0 degrees and equal to or less than 20.0 degrees. [2] The optical element according to [1], in which the recesses of the first shape are further arranged at a predetermined pitch in the second direction. [3] The optical element according to [2], in which recesses of a second shape that satisfy the following conditions (1) to (4) are arranged between the recesses of the first shape that are arranged at a predetermined pitch in the second direction. <Conditions for the recesses of the second shape> (1) The recesses of the second shape have an arc-shaped shape in a plan view. (2) The recesses of the second shape are arranged at a predetermined pitch in the first direction.(3) The length of the recess of the second shape in the first direction is shorter than the length of the recess of the first shape in the first direction. (4) Ends of recesses of the second shape adjacent to each other in the first direction are not joined. [4] The optical element according to [3], wherein the arc shape of the recess of the second shape coincides with a part of the arc shape of the recess of the first shape. [5] The optical element according to any one of [1] to [4], further satisfying the following condition 3. <Condition 3> The angle formed by a tangent to the arc shape of the recess of the first shape and a parallel line in the first direction is defined as the local angle of the recess of the first shape. The first surface is divided parallel to the second direction into three regions: a first region in which the local angle is -5.0 degrees or more and +5.0 degrees or less, a second region in which the local angle is -50.0 degrees or more and -40.0 degrees or less and +40.0 degrees or more and +50.0 degrees or less, and a third region in which the local angle is -80.0 degrees or more and -70.0 degrees or less and +70.0 degrees or more and +80.0 degrees or less. When the sum of the areas of the recesses in the first regions with respect to the total area of ​​the first regions is defined as a "first area ratio," the sum of the areas of the recesses in the second regions with respect to the total area of ​​the second regions is defined as a "second area ratio," and the sum of the areas of the recesses in the third regions with respect to the total area of ​​the third regions is defined as a "third area ratio," the differences between the maximum and minimum values ​​of the first area ratio, the second area ratio, and the third area ratio are 10% or less. [6] The optical element according to any one of [1] to [5], wherein the liquid crystal layer has a single layer structure. [7] The optical element according to any one of [1] to [5], wherein the liquid crystal layer has a multi-layer structure. [8] The optical element according to [6], wherein the liquid crystal layer has negative wavelength dispersion. [9] The optical element according to [7], wherein the liquid crystal layer has positive wavelength dispersion.

[0010] The optical element of the present disclosure has good alignment of liquid crystal molecules and can fully exhibit its performance as an optical element.

[0011] 4( a ) is a cross-sectional view showing an embodiment of an optical element according to the present disclosure; FIG. 4( a ) is a plan view illustrating an embodiment in which a plurality of recesses of a first shape are arranged in a first plane; FIG. 4( b ) is a schematic plan view illustrating a method for calculating a local angle under condition 1; FIG. 4( a ) is a schematic plan view illustrating a location where a tangent line is drawn under condition 1; FIG. 4( b ) is a schematic plan view illustrating a continuous change in the local angle under condition 1; FIG. 4( b ) is a schematic plan view illustrating a method for calculating a local angle under condition 2; FIG. 5 is a diagram illustrating the symbols X, Y, and Z extracted from FIG. 5; FIG. 5 is a partial plan view illustrating an embodiment in which recesses of a second shape are arranged between recesses of a first shape arranged at a predetermined pitch in a second direction.

[0012] Hereinafter, embodiments of the optical element of the present disclosure will be described. [Optical Element] The optical element of the present disclosure comprises a pattern layer and a liquid crystal layer, the pattern layer having a first surface and a second surface opposite to the first surface, the liquid crystal layer being formed on the first surface of the pattern layer, the pattern layer having a plurality of recesses of a first shape within the first surface, the recesses of the first shape having an arc shape in a plan view, the recesses of the first shape being continuously arranged at a predetermined pitch in a first direction within the first surface, and the recesses of the first shape having adjacent first shape recesses in the first direction having mutually joined ends, and the recesses of the first shape satisfy the following conditions 1 and 2. <Condition 1> The angle formed by a tangent to the arc shape of the recesses of the first shape and a line parallel to the first direction is defined as the local angle of the recesses of the first shape. The first-shape recess has a minimum local angle greater than -90.0 degrees and equal to or less than -80.0 degrees, a maximum local angle greater than or equal to +80.0 degrees and less than +90.0 degrees, and the local angle changes continuously from the minimum to the maximum. <Condition 2> A direction perpendicular to the first direction is defined as a second direction, a direction in the second direction in which the arc of the arc shape is convex is defined as a second' direction, a point where ends of adjacent first-shape recesses are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the second' direction is defined as a point M. The intersections of a straight line drawn from point M in the first direction with one first-shape recess and the other first-shape recess that form the junction point X are defined as intersection points Y and Z, respectively. The average angle formed by a first line connecting the junction point X and the intersection point Y and a second line connecting the junction point X and the intersection point Z is greater than 0 degrees and equal to or less than 20.0 degrees.

[0013] FIG. 1 is a cross-sectional view showing one embodiment of an optical element of the present disclosure. The optical element 100 of FIG. 1 has a patterned layer 20 and a liquid crystal layer 30. In FIG. 1, the patterned layer 20 has a first surface 20a and a second surface 20b opposite the first surface. In FIG. 1, the liquid crystal layer 30 is formed on the first surface 20a of the patterned layer 20. In FIG. 1, the patterned layer 20 has a plurality of recesses 21 on the first surface 20a. The optical element 100 of FIG. 1 has a substrate 10 on the side of the patterned layer 20 opposite the liquid crystal layer 30. In FIG. 1, the symbol D indicates the depth of the recesses. In FIG. 1, the symbol t1 indicates the thickness of the patterned layer at a location that does not have a recess. In FIG. 1, the symbol t2 indicates the thickness of the patterned layer below the recess. In FIG. 1, the symbol t3 indicates the thickness of the liquid crystal layer formed at a location that does not have a recess. FIG. 1 is a schematic cross-sectional view. That is, the scale of each layer constituting the optical element 100 and the scale of the recessed portion on the first surface are schematic for ease of illustration and differ from the actual scale. The same applies to figures other than FIG.

[0014] <Patterned Layer> The patterned layer has a first surface and a second surface opposite to the first surface. A liquid crystal layer is formed on the first surface of the patterned layer. The presence of the patterned layer makes it easier to align the liquid crystal molecules in the liquid crystal layer in a predetermined direction.

[0015] The liquid crystal layer 30 is disposed in the recesses 21 of the pattern layer. The shape of the second surface 20b of the pattern layer is not particularly limited. In order to improve the adhesion between the second surface side of the pattern layer and other members such as a substrate, it is preferable that the second surface of the pattern layer is flat.

[0016] FIG. 2 is a plan view illustrating an embodiment in which a plurality of first-shaped recesses 22 are arranged within a first surface. In FIG. 2 , A1 denotes a first direction, A2 denotes a second direction perpendicular to the first direction, P1 denotes the pitch of the first-shaped recesses in the first direction, W1 denotes the length of the first-shaped recesses in the first direction, P2 denotes the pitch of the first-shaped recesses in the second direction, and H1 denotes the length of the first-shaped recesses in the second direction. Because the first-shaped recesses are joined at their ends in the first direction, W1 and P1 are equal. In FIG. 2 , the first-shaped recesses 22 are arranged consecutively in the first direction A1 at a pitch P1. Also, in FIG. 2 , adjacent first-shaped recesses 22 in the first direction A1 have a junction X where their ends join (the junction symbol "X" is omitted in FIG. 2 ). 2, the recesses 22 of the first shape are arranged at a pitch P2 in the second direction A2. In FIG. 2, the recesses 22 of the first shape are not joined together in the second direction.

[0017] In the optical element of the present disclosure, the pattern layer must have a plurality of recesses of a first shape in the first surface, and the recesses of the first shape must have an arc-shaped shape in a plan view. Liquid crystals in the liquid crystal layer are aligned along the shape of the pattern layer. Therefore, by forming the recesses of the first shape in an arc-shaped shape, it is possible to easily align the liquid crystals in the liquid crystal layer in an arc-shaped shape in the first direction.

[0018] In the optical element of the present disclosure, the pattern layer requires that the first-shaped recesses are continuously arranged at a predetermined pitch in the first direction within the first plane, and that adjacent first-shaped recesses in the first direction are joined at their ends. Liquid crystal molecules in the liquid crystal layer are more likely to be aligned when there are no gaps in the pattern of the pattern layer. Therefore, by joining adjacent first-shaped recesses, the liquid crystal molecules in the liquid crystal layer can be more easily aligned. However, in order to improve the alignment of the liquid crystal layer, it is not enough to simply join adjacent first-shaped recesses; Condition 1 must also be satisfied.

[0019] In the optical element disclosed herein, the concave portion of the first shape is required to satisfy the following Condition 1. <Condition 1> The angle formed by the tangent to the arc shape of the concave portion of the first shape and a parallel line in the first direction is defined as the local angle of the concave portion of the first shape. In the concave portion of the first shape, the minimum value of the local angle is greater than −90.0 degrees and less than −80.0 degrees, the maximum value of the local angle is greater than or equal to +80.0 degrees and less than +90.0 degrees, and the local angle changes continuously from the minimum value to the maximum value.

[0020] FIG. 3 is a schematic plan view illustrating a method for calculating the local angle under condition 1. In FIG. 3, reference numeral 21 denotes a recess having a first shape, dashed line D1 denotes a parallel line in a first direction, and dashed lines E1 and E2 denote tangents to the arc shape of the recess having the first shape. FIG. 4(a) is a schematic plan view illustrating the location where the tangents are drawn under condition 1. FIG. 4(a) is also a partial enlarged view of the planar shape of the arc shape of the recess having the first shape (a partial enlarged view of the portion indicated by reference numeral F1 in FIG. 3). The arc shape includes a first arc 21-1 on the inner periphery, a second arc 21-2 on the outer periphery, and a line connecting the ends of the first arc and the second arc on the same side. Under condition 1, the tangent to the arc shape is drawn so as to be tangent to the arc 21-2 on the outer periphery. In Condition 1 and Condition 3 described below, the "-" and "+" signs of the local angles are used such that, with the perpendicular direction to the parallel lines in the first direction as a reference, a "-" sign is assigned to the angle formed between a tangent line inclined to one side with respect to the reference and a parallel line in the first direction, and a "+" sign is assigned to the angle formed between a tangent line inclined to the other side with respect to the reference and a parallel line in the first direction. In FIG. 3, the tangent line forming θ1-1 and the tangent line forming θ1-2 are inclined to different sides with respect to the reference. Therefore, if the sign of θ1-1 is "-", the sign of θ1-2 is "+". Satisfying Condition 1 means that the arc-shaped recesses are continuous in a semicircular shape without being interrupted midway. Because the optical element of the present disclosure satisfies Condition 1, it is easy to increase the pitch of the recesses of the first shape in the first direction. Furthermore, in the optical element of the present disclosure, the ends of adjacent recesses of the first shape are joined in the first direction, so that there is no gap between adjacent recesses of the first shape. Therefore, the optical element of the present disclosure can easily align liquid crystal molecules along the recesses of the first shape in the first direction. When an acute angle and an obtuse angle exist between a tangent to the arc shape of the recesses of the first shape and a parallel line in the first direction, the acute angle is considered to be the local angle of the recesses of the first shape.

[0021] In condition 1, the minimum value of the local angle is preferably −89.7 degrees or more and −81.0 degrees or less, more preferably −89.5 degrees or more and −82.0 degrees or less, and even more preferably −89.0 degrees or more and −83.0 degrees or less. In condition 1, the maximum value of the local angle is preferably +81.0 degrees or more and +89.7 degrees or less, more preferably +82.0 degrees or more and +89.5 degrees or less, and even more preferably +83.0 degrees or more and +89.0 degrees or less.

[0022] In this specification, the planar shape of the recesses on the first surface of the pattern layer is confirmed by imaging the first surface of the pattern layer with a scanning electron microscope. The local angle in condition 1 is calculated from the captured photograph. It is preferable to perform imaging with a scanning electron microscope under the following conditions. An example of a scanning electron microscope is the "SU8000" product name from Hitachi High-Technologies Corporation. <Imaging conditions> Acceleration voltage: 5.0 kV Emission current: 5.0 μA Probe current: High Detector: SE(U) WD: 8 mm Condenser lens 1: 5.0 Condenser lens 2: 1.0 Tilt function of sample stand: tilt angle "0.0" is entered

[0023] In Condition 1, whether the local angle changes continuously can be determined by the following (1) to (3). (1) At any two points on the outer circumferential side of the second arc 21-2, tangent lines are drawn to each of the two points, and the local angles are calculated. For example, at the points marked with a black circle and a black triangle in FIG. 4B, tangent lines are drawn to each of the two points, and the local angles are calculated. If the local angles are identical to the first decimal place, the relationship between the two points is defined as "satisfying a continuous tangent relationship." (2) With respect to any two points that satisfy a continuous tangent relationship, if the distance between the two points is less than 10 nm, the local angle between these two points is considered to "change continuously." (For example, if the local angles of the "●" and "▲" in Figure 4(b) are identical down to the first decimal place and the distance between the "●" and "▲" is less than 10 nm, the local angle is considered to change continuously between the "●" and "▲". (3) If the local angle changes continuously over the entire arc shape according to the criteria in (1) and (2) above, the local angle is considered to change continuously under condition 1.

[0024] The optical element disclosed herein requires that the first-shaped recesses satisfy the following condition 2. <Condition 2> A direction orthogonal to the first direction is defined as a second direction, a direction in which the arc of the arc shape is convex in the second direction is defined as a second' direction, a point where the ends of adjacent first-shaped recesses are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the second' direction is defined as a point M. Intersections of a line drawn from point M in the first direction with one first-shaped recess that forms the junction point X and the other first-shaped recess that forms the junction point X are defined as an intersection point Y and an intersection point Z, respectively. The average angle formed by the first line connecting the junction point X and the intersection point Y and the second line connecting the junction point X and the intersection point Z is greater than 0 degrees and not more than 20.0 degrees.

[0025] FIG. 5 is a schematic plan view illustrating a method for calculating the angle under condition 2. FIG. 5 is also a partially enlarged view of the area indicated by symbol C1 in FIG. 2. FIG. 6 is a view showing symbols X, Y, and Z in FIG. 5. The angle formed by the first line connecting the junction point X and the intersection point Y and the second line connecting the junction point X and the intersection point Z corresponds to θ in FIG. 6. In FIG. 5, symbol A2 indicates the second direction, symbol A2' indicates the second direction and the direction in which the arc of the arc shape is convex, and symbol A1 indicates the first direction. In FIG. 5, symbol X indicates the junction point under condition 2. As shown in FIG. 5, the junction point under condition 2 refers to the point where the outer circumferential arcs 21-2 join together. Although not shown, in FIG. 5, the distance between symbol X and symbol M is 100 nm. Under condition 2, the angle formed by the first line connecting the junction point X and the intersection point Y and the second line connecting the junction point X and the intersection point Z is calculated at any 20 points. The average value of the angles at the 20 points is then set as the average angle under condition 2.

[0026] When the average angle of Condition 2 is 0 degrees, the ends of the recesses of the first shape can be brought as close as possible in the first direction. However, when the average angle of Condition 2 is 0 degrees, the accuracy of the pattern near the joining point is likely to decrease when preparing a plate for forming the pattern layer, making it impossible to stably form the pattern layer. Therefore, when the average angle of Condition 2 is 0 degrees, it is difficult to fully demonstrate the performance of the optical element. Furthermore, when the average angle of Condition 2 is 0 degrees, adjacent recesses are integrated near the joining point, thereby widening the width of the recess. Therefore, when the average angle of Condition 2 is 0 degrees, it is difficult for liquid crystal molecules to align along the recesses near the joining point. When the average angle of Condition 2 exceeds 20.0 degrees, the load near the joining point increases when the pattern layer is peeled off from the shaping plate, making the pattern layer more likely to deform. Therefore, when the average angle of Condition 2 exceeds 20.0 degrees, it is difficult to fully demonstrate the performance of the optical element. On the other hand, by setting the average angle of Condition 2 to be more than 0 degrees and not more than 20.0 degrees, the pattern layer can be formed stably, and the performance of the optical element can be fully exhibited.

[0027] Regarding the average angle of condition 2, the lower limit is preferably 0.5 degrees or more, more preferably 1.0 degrees or more, and even more preferably 2.0 degrees or more, and the upper limit is preferably 15.0 degrees or less, more preferably 12.0 degrees or less, and even more preferably 6.0 degrees or less.

[0028] In the configuration requirements shown in this specification, when multiple upper limit options and multiple lower limit options are shown, a numerical range can be a combination of one selected from the upper limit options and one selected from the lower limit options. For example, in the case of condition 2, examples of the numerical range include more than 0 degrees and 20.0 degrees or less, more than 0 degrees and 15.0 degrees or less, more than 0 degrees and 12.0 degrees or less, more than 0 degrees and 6.0 degrees or less, 0.5 degrees or more and 20.0 degrees or less, 0.5 degrees or more and 15.0 degrees or less, 0.5 degrees or more and 12.0 degrees or less, 0.5 degrees or more and 6.0 degrees or less, 1.0 degrees or more and 20.0 degrees or less, 1.0 degrees or more and 15.0 degrees or less, 1.0 degrees or more and 12.0 degrees or less, 1.0 degrees or more and 6.0 degrees or less, 2.0 degrees or more and 20.0 degrees or less, 2.0 degrees or more and 15.0 degrees or less, 2.0 degrees or more and 12.0 degrees or less, and 2.0 degrees or more and 6.0 degrees or less.

[0029] The pitch P1 of the first-shaped recesses in the first direction varies depending on the desired optical properties and cannot be generalized; however, it is preferably 0.4 μm or more and 10,000 μm or less, more preferably 0.7 μm or more and 8,000 μm or less, and even more preferably 1.0 μm or more and 6,000 μm or less. The pitch P1 of the first-shaped recesses in the first direction is the same as the length W1 of the first-shaped recesses in the first direction. Therefore, W1 is also preferably within the aforementioned range. Setting P1 to 0.4 μm or more is preferable in that it facilitates alignment of liquid crystal molecules and achieves optical properties for blue (wavelength 450 nm), which is on the short-wavelength side of the visible light range. In this specification, the pitch and length of the recesses are measured from photographs of the first surface of the pattern layer taken with a scanning electron microscope.

[0030] The length H1 of the first-shaped recesses in the second direction varies depending on the desired optical properties and cannot be generally determined, but is preferably 0.1 μm or more and 20,000 μm or less, more preferably 0.2 μm or more and 18,000 μm or less, and even more preferably 0.3 μm or more and 17,000 μm or less. Setting H1 to 0.1 μm or more is preferable in that it makes it easier to align liquid crystal molecules.

[0031] The ratio (H1 / W1) of the length H1 of the first-shaped recess in the second direction to the length W1 of the first-shaped recess in the first direction is preferably 0.3 or more and 2.0 or less, more preferably 0.4 or more and 1.9 or less, and even more preferably 0.5 or more and 1.8 or less.

[0032] With respect to the planar shape of the recess of the first shape, the distance between the first arc 21-1 (the arc on the inner periphery) and the second arc 21-2 (the arc on the outer periphery) is preferably 1 nm or more and 100 nm or less, more preferably 5 nm or more and 50 nm or less, and even more preferably 15 nm or more and 30 nm or less. By making the distance 1 nm or more, the pattern layer can be more easily peeled from the shaping plate, making it easier to form the pattern layer more stably. By making the distance 100 nm or less, it is easier to align the liquid crystal molecules. The distance between the first arc and the second arc is the average value of the distances at any 20 points in a photograph of the first surface of the pattern layer taken with a scanning electron microscope.

[0033] The depth of the recesses of the first shape is preferably 2 nm or more and 200 nm or less, more preferably 10 nm or more and 100 nm or less, and even more preferably 20 nm or more and 50 nm or less. By making the depth of the recesses of the first shape 2 nm or more, liquid crystal molecules can be more easily aligned along the recesses. By making the depth of the recesses of the first shape 200 nm or less, the pattern layer can be more easily peeled from the shaping plate, making it easier to form the pattern layer more stably. The depths of other recesses, such as the recesses of the second shape, are also preferably within the above range. In this specification, the depth of the recesses of the first shape is defined as the average of 18 depth values, excluding the maximum and minimum values, from 20 arbitrarily selected recess depth values. The depths of other recesses, such as the recesses of the second shape, are also defined as the average value obtained by the above-mentioned method.

[0034] In this specification, the depth of recesses such as recesses of the first shape is measured by imaging a vertical cross section of the optical element with a scanning electron microscope. The depth of each recess means the maximum depth of each recess. It is preferable to perform imaging with a scanning electron microscope under the following conditions. An example of a scanning electron microscope is the "SU8000" product name of Hitachi High-Technologies Corporation. <Imaging conditions> Acceleration voltage: 5.0 kV Emission current: 5.0 μA Probe current: High Detector: SE(U) WD: 8 mm Condenser lens 1: 5.0 Condenser lens 2: 1.0 Tilt function of sample stand: tilt angle "0.0" is entered

[0035] In the optical element of the present disclosure, the recesses of the first shape are preferably further arranged at a predetermined pitch in the second direction. In Fig. 2, the recesses 22 of the first shape are arranged at a pitch P2 in the second direction A2. By arranging the recesses of the first shape also in the second direction, it is possible to increase the area within the surface of the optical element that exhibits a predetermined function. In order to stably form a pattern layer, it is preferable that the recesses of the first shape are not bonded in the second direction.

[0036] The pitch P2 is preferably 0.1 μm or more and 100.0 μm or less, more preferably 0.15 μm or more and 60.0 μm or less, and even more preferably 0.3 μm or more and 20.0 μm or less. By setting P2 to 0.1 μm or more, it is possible to easily and stably form the pattern layer when preparing a plate for forming the pattern layer. By setting P2 to 100.0 μm or less, it is possible to easily increase the arrangement density of the first recesses in the pattern layer.

[0037] In the optical element of the present disclosure, it is preferable that recesses of a second shape that satisfy the following conditions (1) to (4) are arranged between recesses of a first shape that are arranged at a predetermined pitch in the second direction. <Conditions for recesses of second shape> (1) The recesses of the second shape have an arc shape in a plan view. (2) The recesses of the second shape are arranged at a predetermined pitch in the first direction. (3) The length of the recesses of the second shape in the first direction is shorter than the length of the recesses of the first shape in the first direction. (4) Ends of recesses of the second shape that are adjacent in the first direction are not joined to each other.

[0038] 7 is a partial plan view showing an embodiment in which recesses 23 of a second shape are arranged between recesses 22 of a first shape arranged at a predetermined pitch in the second direction A2. The inclusion of the second recesses increases the density of the recesses within the first surface of the pattern layer. This increases the area within the surface of the optical element that performs a predetermined function.

[0039] It is preferable that the arc shape of the recesses of the second shape coincide with a portion of the arc shape of the recesses of the first shape. The coincidence of the arc shape of the recesses of the second shape with a portion of the arc shape of the recesses of the first shape is determined from a photograph of the first surface of the pattern layer taken with a scanning electron microscope. For example, this can be determined by the following steps A1 to A3. A1: Cut out a portion corresponding to the arc shape of the recesses of the second shape from the image data of the photograph. A2: When the cut-out arc shape of the recesses of the second shape is moved in a second direction, calculate the area ratio where the arc shape of the recesses of the second shape overlaps with the arc shape of the recesses of the first shape. The area ratio is expressed by the following formula: Area ratio (%) = (area of ​​the portion of the arc shape of the recess of the second shape that overlaps with the arc shape of the recess of the first shape / area of ​​the arc shape of the recess of the second shape) x 100 A3: If the area ratio is 90% or more, it is considered that the arc shape of the recess of the second shape and a portion of the arc shape of the recess of the first shape coincide with each other.

[0040] The length of the recesses of the second shape in the first direction may be adjusted to match the desired density of the recesses, as long as it is shorter than the length of the recesses of the first shape in the first direction.

[0041] The optical element of the present disclosure may further include n-th shaped recesses, such as third-shaped recesses and fourth-shaped recesses, arranged between first-shaped recesses arranged at a predetermined pitch in the second direction, in addition to the second-shaped recesses. The n-th shaped recesses preferably satisfy the following condition (where "n" is an integer of 3 or greater). The "match" in (5) below means that the area ratio in the following formula is 90% or greater: Area ratio (%) = (area of ​​the portion of the arc shape of the n-th shaped recess that overlaps with the arc shape of the n-1th shaped recess / area of ​​the arc shape of the n-th shaped recess) × 100 <Conditions for n-th shaped recesses> (1) The n-th shaped recesses have an arc shape in a plan view. (2) The n-th shaped recesses are arranged at a predetermined pitch in the first direction. (3) The length of the n-th shaped recess in the first direction is shorter than the length of the n-1th shaped recess in the first direction. (4) The ends of the nth recesses adjacent to each other in the first direction are not joined to each other. (5) The arc shape of the nth recess coincides with a part of the arc shape of the (n-1)th recess.

[0042] The optical element according to the present disclosure preferably further satisfies the following condition 3. <Condition 3> The angle formed by the tangent to the arc shape of the recess of the first shape and a line parallel to the first direction is defined as the local angle of the recess of the first shape. The first surface is divided parallel to the second direction into three regions: a first region in which the local angle is −5.0 degrees or more and +5.0 degrees or less, a second region in which the local angle is −50.0 degrees or more and −40.0 degrees or less and +40.0 degrees or more and +50.0 degrees or less, and a third region in which the local angle is −80.0 degrees or more and −70.0 degrees or less and +70.0 degrees or more and +80.0 degrees or less. When the sum of the areas of the recesses in the first region relative to the total area of ​​the first region is defined as the "first area ratio," the sum of the areas of the recesses in the second region relative to the total area of ​​the second region is defined as the "second area ratio," and the sum of the areas of the recesses in the third region relative to the total area of ​​the third region is defined as the "third area ratio," the difference between the maximum and minimum values ​​of the first area ratio, second area ratio, and third area ratio is 10% or less.

[0043] The symbols R1, R2, and R3 in Fig. 7 correspond to the first region, second region, and third region of Condition 3, respectively. Note that Fig. 7 is a schematic diagram for easily explaining Condition 3, and therefore the local angles of the first to third regions in Fig. 7 do not completely match the local angles of Condition 3. In Condition 3, the total area of ​​the recesses means the total area of ​​all the recesses. The total area of ​​all the recesses means the sum of the area of ​​the recesses of the first shape and the area of ​​the recesses other than the recesses of the first shape.

[0044] Satisfying condition 3 means that there is little difference in the area ratio of the recesses between regions. Satisfying condition 3 makes it easier for the optical element to stably exhibit predetermined performance within its surface. In condition 3, the difference between the maximum and minimum values ​​is more preferably 7% or less, and even more preferably 5% or less.

[0045] In Condition 3, the area ratios of the first to third regions are measured from a photograph of the first surface of the pattern layer taken with a scanning electron microscope. More specifically, the area ratios of the first to third regions are calculated at any 20 locations on the photograph, and the average values ​​of the 20 locations are defined as the area ratios of the first to third regions.

[0046] The pattern layer may have a thickness below the recesses. In FIG. 1, the symbol t2 indicates the thickness of the pattern layer below the recesses. The average thickness below the recesses is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less, and even more preferably 2 μm or more and 7 μm or less. By setting t2 to 0.5 μm or more, it is possible to easily control the curing when forming the pattern layer and to easily coat the liquid crystal layer on the pattern layer. By setting t2 to 20 μm or less, it is possible to easily suppress the occurrence of curl. The average thickness below the recesses means the average thickness of 8 thicknesses, excluding the maximum and minimum values, from any 10 thicknesses measured at 10 locations on a cross-sectional photograph of the optical element.

[0047] <<Material of Pattern Layer>> The pattern layer preferably contains a resin. The proportion of the resin in the pattern layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total solid content of the pattern layer.

[0048] Resin: Examples of resins for the pattern layer include thermoplastic resins and cured products of curable resin compositions. Among these, cured products of curable resin compositions are preferred in order to improve strength. The proportion of the cured product of the curable resin composition relative to the total solid content of the pattern layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0049] Examples of the cured product of the curable resin composition include a cured product of a heat-curable resin composition and a cured product of an ionizing radiation-curable resin composition, and among these, a cured product of an ionizing radiation-curable resin composition is preferred.

[0050] The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound"). Examples of the ionizing radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups. The ionizing radiation curable resin is preferably a compound having an ethylenically unsaturated bond group. Furthermore, from the viewpoint of preventing damage to the pattern layer during the manufacturing process of the optical element, the ionizing radiation curable resin is more preferably a compound having two or more ethylenically unsaturated bond groups, and among these, a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups is even more preferred. The polyfunctional (meth)acrylate compound can be either a monomer or an oligomer. Ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Usually, ultraviolet (UV) rays or electron beams (EB) are used, but other types of electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams can also be used.

[0051] Among the polyfunctional (meth)acrylate compounds, examples of bifunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate. Examples of trifunctional or higher functional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate. The above (meth)acrylate monomers may have a portion of their molecular skeleton modified, and those modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like can also be used.

[0052] Examples of polyfunctional (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylates can be obtained, for example, by reacting a polyhydric alcohol and an organic diisocyanate with a hydroxy (meth)acrylate. Preferred epoxy (meth)acrylates include (meth)acrylates obtained by reacting a trifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with (meth)acrylic acid; (meth)acrylates obtained by reacting a bifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a polybasic acid and (meth)acrylic acid; and (meth)acrylates obtained by reacting a bifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a phenol and (meth)acrylic acid. The above-mentioned ionizing radiation curable resins can be used alone or in combination of two or more.

[0053] When the ionizing radiation curable resin is an ultraviolet curable resin, the pattern layer forming coating liquid preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, etc. The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing rate, and examples thereof include one or more selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc.

[0054] The pattern layer may contain additives such as a refractive index adjuster, an antioxidant, an ultraviolet absorber, a light stabilizer, and an antistatic agent, as long as the effects of the present disclosure are not impaired.

[0055] <<Method for forming pattern layer>> 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 first surface. More specifically, the pattern layer can be formed, for example, by the following steps 1 and 2.

[0056] 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 the layer containing a resin using a plate having a shape complementary to the surface shape of the first surface of the pattern layer.

[0057] When the coating liquid for forming a pattern layer contains a solvent, it is preferable to dry the solvent in step 1.

[0058] 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 pattern layer-forming coating liquid containing an ionizing radiation-curable resin composition is used as the pattern layer-forming coating liquid in step 1, it is preferable to irradiate with ionizing radiation simultaneously with the shaping in step 2, and cure the ionizing radiation-curable resin composition contained in the shaped layer.

[0059] When another layer such as a primer layer is present between the substrate and the pattern layer, it is preferable to carry out a step of forming the other layer on the substrate before step 1.

[0060] The plate used in step 2 can be produced by general-purpose means such as laser lithography, electron beam lithography, or FIB (Focused Ion Beam). It is also preferable to produce a large number of plates by duplicating a plate produced by the above-mentioned means and then arranging the many replicated plates to form a multi-faceted plate. The plate can be reproduced by general-purpose means such as electroforming. Examples of the shape of the plate include flat and cylindrical shapes. Cylindrical plates are preferred because they can be processed by roll-to-roll processing and have excellent productivity.

[0061] <Liquid Crystal Layer> In the optical element of the present disclosure, the liquid crystal layer is formed on the first surface of the patterned layer. The liquid crystal layer can be formed, for example, by applying a liquid crystal layer-forming coating liquid containing a liquid crystal compound onto the patterned layer, and then drying and curing the liquid crystal layer as necessary.

[0062] Examples of the liquid crystal compound include 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, and discotic liquid crystal compounds (disk-shaped liquid crystal compounds). 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.

[0063] The liquid crystal compound is preferably a rod-shaped liquid crystal compound, and although there is no particular limitation on the rod-shaped liquid crystal compound, examples thereof include the compounds shown in (1) to (17) below.

[0064]

[0065]

[0066] Among liquid crystal compounds, polymerizable rod-shaped liquid crystal materials are preferred. Polymerizable functional groups of polymerizable rod-shaped liquid crystal materials include those that polymerize under the action of ionizing radiation such as ultraviolet light or electron beams, or heat. Specific examples include radically polymerizable functional groups. Examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and more specific examples include vinyl groups and acrylate groups (a general term including acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups), with or without substituents.

[0067] The liquid crystal layer is preferably formed over the entire surface of the first surface of the pattern layer. That is, it is preferable to form the liquid crystal layer also in areas on the first surface of the pattern layer that do not have recesses (FIG. 1). The thickness of the liquid crystal compound may be adjusted according to the desired retardation value.

[0068] The liquid crystal layer may have a single layer structure or a multi-layer structure. In order to reduce the thickness, the liquid crystal layer preferably has a single layer structure. In order to improve the display quality by widening the bandwidth of the optical element, the liquid crystal layer preferably satisfies the following condition (i) or (ii): (i) The liquid crystal layer has a multi-layer structure and has positive wavelength dispersion; (ii) The liquid crystal layer has a single layer structure and has negative wavelength dispersion.

[0069] The liquid crystal layer may have positive wavelength dispersion or negative wavelength dispersion. Negative wavelength dispersion is a characteristic in which the retardation imparted to transmitted light increases as the wavelength of transmitted light increases. Positive wavelength dispersion is a characteristic in which the retardation imparted to transmitted light decreases as the wavelength of transmitted light increases. In this specification, when the in-plane retardation at a wavelength of 450 nm is defined as Re450 and the in-plane retardation at a wavelength of 550 nm is defined as Re550, a characteristic in which Re450<Re550 is referred to as negative wavelength dispersion. In this specification, a characteristic in which Re450>Re550 is referred to as positive wavelength dispersion.

[0070] In an optical element having a liquid crystal layer laminated on a patterned layer, the shape of the patterned layer can be confirmed, for example, by the following method (1) or (2). Note that the shape of the patterned layer may be confirmed by a method other than the following methods (1) and (2), as long as the method allows for easy removal of the liquid crystal layer on the patterned layer. (1) According to JIS K5600-5-6:1999, 100 grid-like cuts are made on the surface of the liquid crystal layer at 1 mm intervals. Then, 18 mm Nichiban Cellotape (registered trademark) is applied to the cut areas and rubbed with an eraser to firmly adhere the tape to the coating film. The tape is then quickly peeled off at least 10 times to remove the coating film. If some of the coating film from the grid-like cuts begins to peel off during the above-described process, it is preferable to repeat the above-described process, focusing on the peeled area. In this way, the shape of the patterned layer can be confirmed by peeling off the liquid crystal layer on the patterned layer. (2) Using a cross-section cutting technique used in cross-sectional observations such as STEM, the optical element is cut as thin as possible and cross-sectional STEM images are taken repeatedly. The cross-sectional STEM images obtained are then stitched together to create a three-dimensional image, allowing the shape of the pattern layer to be confirmed.

[0071] <Substrate> The optical element of the present disclosure may have a substrate.

[0072] Various materials can be used as the material constituting the substrate, but materials with good mechanical properties, optical properties, stability, and processability are preferred. Examples of 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, the substrate is preferably a resin substrate. The in-plane retardation of the 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. The wavelength λ of light serving as the reference for the retardation is 550 nm.

[0073] The thickness of the substrate can be adjusted appropriately within the range of 5 μm or more and 1000 μm or less. 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 thereof may be the above-mentioned value.

[0074] The substrate preferably has a total light transmittance of 70% or more, more preferably 80% or more, and even more preferably 85% or more according to JIS K7361-1:1997.The substrate preferably has a haze of 10% or less, more preferably 5% or less, and even more preferably 3% or less according to JIS K7136:2000.

[0075] In order to suppress refraction of light at the interface between the substrate and the pattern layer, it is preferable that the refractive index of the pattern layer and the refractive index of the substrate are close to each other. Specifically, the refractive index of the pattern 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. The wavelength λ of light that serves as the reference for the refractive index is 550 nm.

[0076] <Other Layers> The optical element of the present disclosure may further include other layers. Examples of other layers include a primer layer for improving adhesion between the substrate and the pattern layer, an antistatic layer, etc. The primer layer is preferably formed between the substrate and the pattern layer. The antistatic layer is preferably formed on the opposite side of the substrate from the pattern layer.

[0077] <Retardation> The optical element may have an average in-plane retardation within a predetermined range. When the wavelength to be controlled is λ [nm], the in-plane retardation of the optical element is preferably (λ / 2)×0.95 or more and (λ / 2)×1.05 or less, more preferably (λ / 2)×0.97 or more and (λ / 2)×1.03 or less, and more preferably (λ / 2)×0.99 or more and (λ / 2)×1.01 or less. By setting the average in-plane retardation of the optical element within the above range, the optical element can exhibit, for example, the following effects when used as a diffractive optical element. (1) When circularly polarized light is incident on the diffractive optical element, the light can be diffracted and the phase of the light can be inverted. (2) When natural light or linearly polarized light is incident on the diffractive optical element, the light can be diffracted and the light can be separated into right-handed circularly polarized light and left-handed circularly polarized light. The in-plane retardation of an optical element refers to the average value of five in-plane retardations, excluding the maximum and minimum values, from among the seven in-plane retardations in the plane of the optical element. The wavelength λ of light serving as the reference for the retardation is 550 nm. Examples of in-plane retardation measuring devices include the "AxoStep" manufactured by AXOMETRICS and the two-dimensional birefringence evaluation system (product name: WPA-Micro) from Photonic Lattice. The former product is suitable for measuring a wide area, while the latter product is suitable for measuring a narrow area.

[0078] <Applications> The optical element of the present disclosure can be used, for example, as a diffractive optical element. The optical element of the present disclosure can also be used as a component of a light control device. Light transmitted through a diffractive optical element can be adjusted to a predetermined diffraction angle range. Therefore, for example, by using a diffractive optical element, it is possible to widen or narrow the irradiation range of light. Furthermore, by causing the lights 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, optical sensors, and laser projectors.

[0079] The diffraction angle θ of a diffractive optical element is expressed as follows: pitch is x [nm], wavelength of light is λ [nm], and incident angle of light is θ ０ In this case, θ and θ can be expressed by the following equations.０ is the angle when the perpendicular direction to the plane of the diffractive optical element is set to 0 degrees. ０ is the case of the positive direction from the perpendicular direction. The sign ± is added because, depending on the direction of rotation of the circularly polarized incident light, the light may be diffracted in the positive direction or the negative direction relative to the perpendicular direction. In this specification, the pitch refers to the pitch P1 of the recesses of the first shape. sin θ = ±(λ / x) + sin θ ０

[0080] For example, the incident angle θ ０ When the angle is fixed to 0 degrees and the wavelength of light is fixed to 1550 nm, the relationship between the pitch and the diffraction angle is as shown in Table 1 below.

[0081] The diffraction angles in Table 1 are angles when there is one diffractive optical element. If the polarization state is the same, increasing the number of diffractive optical elements 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 It can be expressed as ×θ (degrees).

[0082] 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.

[0083] 1. Measurement and Evaluation The following measurements and evaluations were carried out on the optical elements of the Examples and Comparative Examples. The atmosphere during each measurement and evaluation was 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 atmosphere for 30 to 60 minutes, and then the measurement and evaluation were carried out.

[0084] 1-1. Planar Shape of the Recesses of the Pattern Layer The first surface of the pattern layer of the intermediate body of the optical element of the Examples and Comparative Examples was imaged using a scanning electron microscope (Hitachi High-Technologies Corporation, product name "SU8000"). The imaging conditions were as follows. The intermediate body refers to a laminate having a primer layer and a pattern layer on a substrate. Based on the image, the local angle under condition 1, pitch P1 in the first direction, pitch P2 in the second direction, length H1 of the recesses of the first shape in the second direction, distance between the first arc and the second arc, average angle under condition 2, and difference in area ratio under condition 3 were calculated using the method described in the specification. Furthermore, based on the image, whether or not the local angle under condition 1 continuously changed was determined using the method described in the specification. A continuous change was evaluated as "yes," and a non-continuous change was evaluated as "no." The "distance between the first arc and the second arc" was referred to as the "arc distance." For comparative examples in which the pattern layer could not be peeled off from the plate when forming the pattern layer, the result was marked with "-". The results are shown in Table 3. <Imaging conditions> - Acceleration voltage: 5.0 kV - Emission current: 5.0 μA - Probe current: High - Detector: SE (U) - WD: 8 mm - Condenser lens 1: 5.0 - Condenser lens 2: 1.0 - Tilt function of sample stand: tilt angle "0.0" entered

[0085] 1-2. Depth of recesses in pattern layer Vertical cross sections of the optical elements of the examples and comparative examples were imaged using a scanning electron microscope (Hitachi High-Technologies Corporation, product name "SU8000"). The imaging conditions were the same as those in 1-1 above. Then, the depth D of the recesses of the first shape of the intermediate was measured based on the method described in the specification. The results are shown in Table 3.

[0086] 1-3. Peelability Peelability was evaluated according to the following criteria. The results are shown in Table 3. A: When the pattern layer was formed, no resin remained on the shaping plate, and the pattern layer was easily peelable from the plate. B: When the pattern layer was formed, a small amount of resin remained on the shaping plate, but the pattern layer was easily peelable from the plate. C: When the pattern layer was formed, some of the resin remained on the shaping plate, and the pattern layer was not easily peelable from the plate. D: When the pattern layer was formed, the shaping plate could not be peeled from the shaped layer.

[0087] 1-4. First Alignment The alignment of the liquid crystal layer was evaluated for the optical elements of the Examples and Comparative Examples according to the following criteria. A polarizing microscope was used for the evaluation. The results are shown in Table 3. When the pitch of the pattern layer is 1 μm, the "observation area 50 times the pitch of the pattern layer" described below is 50 μm x 50 μm. The fewer schlieren textures there are, the better the alignment of the liquid crystal molecules. A: In an observation area 50 times the pitch of the pattern layer, the number of schlieren textures is zero, excluding those caused by dust. B: In an observation area 50 times the pitch of the pattern layer, the number of schlieren textures is between 1 and 9, excluding those caused by dust. C: In an observation area 50 times the pitch of the pattern layer, the number of schlieren textures is 10 or more, excluding those caused by dust.

[0088] 1-5. Second Orientation For the optical elements of the examples and comparative examples, whether or not the liquid crystal molecules are oriented along the direction of the first-shaped recesses was observed near the junction point X where the ends of adjacent first-shaped recesses are joined. A two-dimensional birefringence evaluation system (product name: WPA-Micro) from Photonic Lattice was used for the observation. The second orientation was evaluated according to the following criteria. A narrower region was observed for the second orientation than for the first orientation. A: The difference between the orientation of the first-shaped recesses and the orientation of the liquid crystal molecules near the junction point X was within 3.0 degrees. B: The difference between the orientation of the first-shaped recesses and the orientation of the liquid crystal molecules near the junction point X was greater than 3.0 degrees and less than 6.0 degrees. C: The difference between the orientation of the first-shaped recesses and the orientation of the liquid crystal molecules near the junction point X was greater than 6.0 degrees.

[0089] 2. Plate Fabrication A simulation tool was used to design the shape of the first surface of the pattern layer. The first surface was designed so that the recesses of the first shape were arranged continuously in a first direction at a predetermined pitch, and so that adjacent recesses of the first shape in the first direction were joined at their ends. Furthermore, the first surface was also designed so that the recesses of the first shape were arranged at a predetermined pitch in a second direction perpendicular to the first direction. The simulation was performed so that the planar shape of the recesses of the first shape satisfied the values ​​listed in Table 2 for the local angle (condition 1), pitch P1 in the first direction, pitch P2 in the second direction, length H1 of the recesses of the first shape in the second direction, spacing between the first arc and the second arc, average angle (condition 2), and difference in area ratio (condition 3). Furthermore, the simulation was performed so that the planar shape of the recesses of the first shape satisfied condition 1. A quartz master mold with a surface shape designed by simulation was produced using a 6-inch square synthetic quartz plate through an electron beam lithography process using an electron beam lithography device and a dry etching device. Next, an ultraviolet-curable resin was poured into the master mold, and 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, a replica mold of the master mold, which is a mold having a shape complementary to that of the resin plate, was obtained by electroforming. Multiple replica molds were produced. Multiple replica molds were wound around a roll to produce roll-shaped plates used in the examples and comparative examples (Table 2).

[0090] 3. Fabrication of Optical Element [Example 1] A primer layer having the following formulation was applied to 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 pattern layer-forming coating liquid having the following formulation was applied to the primer layer and dried to form a layer containing uncured resin. Next, the roll-shaped plate prepared in "2" above was used to form the layer containing uncured resin, and at the same time, ultraviolet light was irradiated from the substrate side (cumulative 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. Next, the following liquid crystal layer-forming coating solution was applied to the pattern layer, dried, and then irradiated with ultraviolet light (integrated light amount: 150 mJ / cm ２ ), a liquid crystal layer was formed. The liquid crystal layer used was a liquid crystal with an in-plane birefringence (Δn) of 0.17, and the film thickness was adjusted so that the in-plane retardation was 266 nm. The liquid crystal layer with the above film thickness was formed by two coating steps. The optical element of Example 1 was obtained by the above process. The optical element of Example 1 was produced by roll-to-roll production.

[0091] <Coating liquid for forming primer layer> Polyolefin resin: 70 parts by mass (manufactured by Mitsubishi Chemical Corporation, trade name: Surflen P-1000) Silica-based lubricant: 5 parts by mass (manufactured by CIK Nanotec Co., Ltd., trade name: SIRMIBK15WT%-E65) Methyl ethyl ketone: 25 parts by mass

[0092] <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 (manufactured by IGM, product name: Omnirad 184)

[0093] <Liquid crystal layer forming coating liquid> Rod-shaped liquid crystal molecules: 10 parts by mass (LC242 (trade name), manufactured by BASF, in-plane birefringence (Δn) = 0.17) Photopolymerization initiator: 0.4 parts by mass (manufactured by IGM, trade name: Omnirad 184) Methyl ethyl ketone: 89.6 parts by mass

[0094] [Examples 2 to 10], [Comparative Examples 1 to 4] Except for changing the plate to that shown in Table 2, laminates having a primer layer and a pattern layer on a substrate, and optical elements were obtained in the same manner as in Example 1.

[0095]

[0096]

[0097] From the results in Table 3, it can be seen that the optical elements of the examples have good peelability and orientation, and therefore the optical elements of the examples are likely to exhibit their performance.

[0098] 10: Substrate 20: Pattern layer 20a: First surface 20b: Second surface 21: Recess 22: Recess of first shape 23: Recess of second shape 30: Liquid crystal layer 100: Optical element A1: First direction A2: Second direction X: Junction point

Claims

1. An optical element having a pattern layer and a liquid crystal layer, the pattern layer having a first surface and a second surface opposite to the first surface, the liquid crystal layer being formed on the first surface of the pattern layer, the pattern layer having a plurality of recesses of a first shape within the first surface, the recesses of the first shape having an arc shape in a plan view, the recesses of the first shape being continuously arranged at a predetermined pitch in a first direction within the first surface, and the recesses of the first shape adjacent in the first direction have ends joined to each other, and the recesses of the first shape satisfy the following conditions 1 and 2. <Condition 1> The angle formed by the tangent to the arc shape of the recesses of the first shape and a parallel line in the first direction is defined as the local angle of the recesses of the first shape. The first shape recess has a minimum value of the local angle that is greater than -90.0 degrees and equal to or less than -80.0 degrees, a maximum value of the local angle that is greater than or equal to +80.0 degrees and less than +90.0 degrees, and the local angle changes continuously from the minimum value to the maximum value. <Condition 2> A direction perpendicular to the first direction is defined as a second direction, a direction in which the arc of the arc shape is convex in the second direction is defined as a second' direction, a point where ends of adjacent first shape recesses are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the second' direction is defined as a point M. The intersections of a straight line drawn from point M in the first direction with the recess of one first shape forming the junction point X and the recess of the other first shape forming the junction point X are defined as intersection point Y and intersection point Z. The average angle formed by the first straight line connecting the junction point X and intersection point Y and the second straight line connecting the junction point X and intersection point Z is greater than 0 degrees and equal to or less than 20.0 degrees.

2. The optical element according to claim 1, wherein the recesses of the first shape are further arranged at a predetermined pitch in the second direction.

3. The optical element according to claim 2, wherein recesses of a second shape that satisfy the following conditions (1) to (4) are arranged between the recesses of the first shape that are arranged at a predetermined pitch in the second direction. <Conditions for the recesses of the second shape> (1) The recesses of the second shape have an arc shape in a plan view. (2) The recesses of the second shape are arranged at a predetermined pitch in the first direction. (3) The length of the recesses of the second shape in the first direction is shorter than the length of the recesses of the first shape in the first direction. (4) Ends of the recesses of the second shape adjacent to each other in the first direction are not joined to each other.

4. The optical element according to claim 3, wherein the arc shape of the recess of the second shape coincides with a portion of the arc shape of the recess of the first shape.

5. The optical element according to claim 1, further satisfying the following condition 3: <Condition 3> The angle between a tangent to the arc shape of the recess of the first shape and a parallel line in the first direction is defined as a local angle of the recess of the first shape. The first surface is divided into three regions parallel to the second direction: a first region where the local angle is -5.0 degrees or more and +5.0 degrees or less; a second region where the local angle is -50.0 degrees or more and -40.0 degrees or less and +40.0 degrees or more and +50.0 degrees or less; and a third region where the local angle is -80.0 degrees or more and -70.0 degrees or less and +70.0 degrees or more and +80.0 degrees or less. When the sum of the areas of the recesses in the first region relative to the total area of ​​the first region is defined as the "first area ratio," the sum of the areas of the recesses in the second region relative to the total area of ​​the second region is defined as the "second area ratio," and the sum of the areas of the recesses in the third region relative to the total area of ​​the third region is defined as the "third area ratio," the difference between the maximum and minimum values ​​of the first area ratio, second area ratio, and third area ratio is 10% or less.

6. The optical element according to claim 1, wherein the liquid crystal layer has a single layer structure.

7. The optical element according to claim 1, wherein the liquid crystal layer has a multi-layer structure.

8. The optical element according to claim 6, wherein the liquid crystal layer has negative wavelength dispersion.

9. The optical element according to claim 7, wherein said liquid crystal layer has positive wavelength dispersion.

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