Optical element

Abstract

To provide an optical element that has the favorable orientation of liquid crystal molecules and can achieve sufficient optical element performance.SOLUTION: An optical element comprises 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 predetermined 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. Joining points of the recesses of the first shape satisfy a predetermined condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to 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 been progressing for personal authentication and automatic 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.

[0004] As a configuration of an optical element, a configuration in which a liquid crystal layer is provided on a pattern layer having a predetermined pattern is known (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2018 / 038260 [Patent Document 2] JP 2022-147451 A Summary of the Invention [Problem to be solved by the invention]

[0006] The pattern layer of the optical element of Patent Document 1 has a configuration in which the angle of the pattern of the pattern layer changes stepwise. That is, the optical element of Patent Document 1 has many contact parts where the angle of the pattern changes suddenly. At the contact parts, alignment defects of the 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 a problem in that it has many contact parts where alignment defects of the 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 be oriented in the gap. [Means for solving the problem]

[0008] The inventors have investigated a configuration in which the pattern of the pattern layer is made into an arc shape and adjacent patterns are joined together to make it easier to align 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 present inventors have completed an optical element which has good alignment of liquid crystal molecules and which can provide sufficient performance as an optical element.

[0009] This disclosure provides the following [1] to [9]. [1] A liquid crystal display device comprising: a pattern layer and a liquid crystal layer; the pattern layer has a first surface and a second surface opposite the first surface; the liquid crystal layer is formed on the first surface of the patterned layer; the pattern layer has a plurality of recesses of a first shape in the first surface; The first shape recess has an arc shape in a plan view, the recesses of the first shape are disposed continuously at a predetermined pitch in a first direction in the first plane, and ends of the recesses of the first shape adjacent to each other in the first direction are joined to each other; An optical element, wherein the concave portion of the first shape satisfies the following conditions 1 and 2: <Condition 1> 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 recess of the first shape 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 equal to or greater than +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 is defined as a second' direction, a point where the ends of adjacent recesses of the first shape are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the 2' 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 junction point X and the recess of the other first shape are defined as intersection Y and intersection Z, respectively. The average angle between 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 less than or equal to 20.0 degrees. [2] The optical element according to [1], wherein the recesses of the first shape are further arranged at a predetermined pitch in the second direction. [3] The optical element described in [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 concave portion of the second shape> (1) The recess of the second shape has 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 recess having the second shape in the first direction is shorter than the length of the recess having the first shape in the first direction. (4) The 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 [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 any one of [1] to [4], 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 line parallel to the first direction is defined as a 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 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 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. Effect of the Invention

[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. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view illustrating an embodiment of an optical element according to the present disclosure. [Diagram 2] FIG. 2 is a plan view for explaining an embodiment in which a plurality of recesses having a first shape are arranged in a first surface. [Diagram 3] FIG. 13 is a schematic plan view for explaining a method of calculating a local angle under condition 1. [Figure 4] Fig. 4(a) is a schematic plan view for explaining the locations where tangent lines are drawn under condition 1. Fig. 4(b) is a schematic plan view for explaining the continuous change in local angle under condition 1. [Diagram 5] 13 is a schematic plan view for explaining a method of calculating a local angle under condition 2. FIG. [Figure 6] 6 is a diagram showing symbols X, Y, and Z in FIG. 5. [Figure 7] FIG. 13 is a partial plan view showing 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the optical element according to the present disclosure will be described. [Optical elements] The optical element of the present disclosure comprises: A pattern layer and a liquid crystal layer, the pattern layer has a first surface and a second surface opposite the first surface; the liquid crystal layer is formed on the first surface of the patterned layer; the pattern layer has a plurality of recesses of a first shape in the first surface; The first shape recess has an arc shape in a plan view, the recesses of the first shape are disposed continuously at a predetermined pitch in a first direction in the first plane, and ends of the recesses of the first shape adjacent to each other in the first direction are joined to each other; The recess of the first shape satisfies the following conditions 1 and 2. <Condition 1> 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 recess of the first shape 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 equal to or greater than +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 is defined as a second' direction, a point where the ends of adjacent recesses of the first shape are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the 2' 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 junction point X and the recess of the other first shape are defined as intersection Y and intersection Z, respectively. The average angle between 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 less than or equal to 20.0 degrees.

[0013] FIG. 1 is a cross-sectional view showing one embodiment of an optical element according to the present disclosure. The optical element 100 in Fig. 1 has a pattern layer 20 and a liquid crystal layer 30. In Fig. 1, the pattern layer 20 has a first surface 20a and a second surface 20b opposite to the first surface. In Fig. 1, the liquid crystal layer 30 is formed on the first surface 20a of the pattern layer 20. In Fig. 1, the pattern layer 20 has a plurality of recesses 21 on the first surface 20a. The optical element 100 in Fig. 1 has a substrate 10 on the side of the pattern layer 20 opposite to the liquid crystal layer 30. In Fig. 1, the symbol D indicates the depth of the recess. In Fig. 1, the symbol t1 indicates the thickness of the pattern layer in a portion that does not have a recess. In Fig. 1, the symbol t2 indicates the thickness of the pattern layer below the recess. In Fig. 1, the symbol t3 indicates the thickness of the liquid crystal layer formed in a portion 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 the other figures.

[0014] <Pattern layer> The pattern 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 pattern layer. By having the pattern layer, it is possible to easily align the liquid crystal molecules of the liquid crystal layer in a predetermined direction.

[0015] A liquid crystal layer 30 is disposed within the recesses 21 of the patterned 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, the second surface of the pattern layer is preferably flat.

[0016] FIG. 2 is a plan view for illustrating an embodiment in which a plurality of recesses 22 having a first shape are arranged in a first surface. 2, A1 indicates a first direction, A2 indicates a second direction perpendicular to the first direction, P1 indicates the pitch of the recesses of the first shape in the first direction, W1 indicates the length of the recesses of the first shape in the first direction, P2 indicates the pitch of the recesses of the first shape in the second direction, and H1 indicates the length of the recesses of the first shape in the second direction. Since the ends of the recesses of the first shape are joined in the first direction, W1 is equal to P1. In Fig. 2, the recesses 22 of the first shape are continuously arranged at a pitch P1 in the first direction A1. Also, in Fig. 2, the recesses 22 of the first shape adjacent to each other in the first direction A1 have a junction point X where their ends are joined (the reference symbol "X" is omitted in Fig. 2). Also, in Fig. 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 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 shape in a plan view. The liquid crystal in the liquid crystal layer is aligned along the shape of the pattern layer, so by forming the recesses of the first shape in an arc shape, the liquid crystal in the liquid crystal layer can be easily aligned in an arc shape in the first direction.

[0018] In the optical element of the present disclosure, the pattern layer requires that the recesses of the first shape are arranged continuously at a predetermined pitch in a first direction within the first surface, and that adjacent recesses of the first shape in the first direction have ends joined to each other. The liquid crystal molecules in the liquid crystal layer are more easily aligned when there are no gaps in the pattern of the pattern layer. Therefore, by joining adjacent recesses of the first shape, 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 recesses of the first shape; condition 1 must also be satisfied.

[0019] In the optical element of the present disclosure, the concave portion of the first shape must satisfy the following condition 1. 《Condition 1》 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 recess of the first shape 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 equal to or greater than +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 for explaining a method of calculating a local angle under condition 1. In FIG. In FIG. 3, reference numeral 21 denotes a recess of a first shape, dashed lines denote parallel lines in a first direction, and dashed lines denote tangents to the arc shape of the recess of the first shape. FIG. 4(a) is a schematic plan view for explaining the location where the tangent line is drawn in condition 1. FIG. 4(a) is also a partial enlarged view of the planar shape of the arc shape of the first shape recess (partially enlarged view of the area circled by the dashed line in FIG. 3). The arc shape includes a first arc 21-1 on the inner periphery side, a second arc 21-2 on the outer periphery side, and a line connecting the ends of the first arc and the second arc on the same side. In condition 1, the tangent line to the arc shape is drawn so as to be tangent to the arc on the outer periphery side. In condition 1 and condition 3 described later, the signs of "-" and "+" of local angles are given by using a perpendicular direction to a parallel line in a first direction as a reference, and a "-" sign is given to an angle between a tangent inclined to one side of the reference and a parallel line in the first direction, and a "+" sign is given to an angle between a tangent inclined to the other side of the reference and a parallel line in the first direction. In FIG. 3, the tangent forming θ1-1 and the tangent 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 along the way. Since the optical element of the present disclosure satisfies condition 1, the pitch of the recesses of the first shape can be easily increased in the first direction. Furthermore, since the optical element of the present disclosure has the ends of adjacent recesses of the first shape joined in the first direction, 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 recess of the first shape and a parallel line in the first direction, the acute angle is regarded as a local angle of the recess 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 photographing the first surface of the pattern layer with a scanning electron microscope. The local angle in Condition 1 is calculated from the photograph. The scanning electron microscope is preferably used for imaging under the following conditions: The scanning electron microscope may be SU8000, a product name of Hitachi High-Technologies Corporation. <Imaging conditions> Acceleration voltage: 5.0Kv Emission current: 5.0uA Probe current: High Detector: SE(U) Working distance: 8mm Condenser lens 1:5.0 Condenser lens 2:1.0 Tilt function of the document table: Enter the tilt angle "0.0"

[0023] In condition 1, whether or not the local angle changes continuously can be determined by the following (1) to (3). (1) At any two points on the second arc 21-2 on the outer periphery, draw a tangent line to each of them and calculate the local angle. For example, at the points marked with "●" and "▲" in FIG. 4(b), draw a tangent line to each of them and calculate the local angle. Then, if the respective local angles are identical down to the first decimal place, the relationship between any two points is defined as "satisfying the relationship of continuous tangents." (2) For any two points that satisfy the relationship of continuous junction, if the distance between the two points is less than 10 nm, it is considered that the "local angle changes continuously" between these two points. (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 between the "●" and "▲" is considered to change continuously.) (3) If the local angle changes continuously over the entire arc shape according to the criteria of (1) and (2) above, then the local angle is deemed to change continuously under condition 1.

[0024] In the optical element of the present disclosure, the concave portion of the first shape must satisfy the following condition 2. 《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 is defined as a second' direction, a point where the ends of adjacent recesses of the first shape are joined is defined as a junction point X, and a point 100 nm away from the junction point X in the 2' 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 junction point X and the recess of the other first shape are defined as intersection Y and intersection Z, respectively. The average angle between 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 less than or equal to 20.0 degrees.

[0025] Fig. 5 is a schematic plan view for explaining a method of calculating the angle of condition 2. Fig. 5 is also a partially enlarged view of the portion circled by the dashed line in Fig. 2. Fig. 6 is a view in which the symbols X, Y, and Z are extracted from Fig. 5. The angle formed by the first straight line connecting the junction point X and the intersection point Y and the second straight line connecting the junction point X and the intersection point Z corresponds to θ in Fig. 6. In FIG. 5, reference symbol A2 indicates the second direction, reference symbol A2' indicates the second direction in which the arc of the arc shape is convex, and reference symbol A1 indicates the first direction. 5, the symbol X indicates a joining point under condition 2. The joining point under condition 2 means a location where the arc 21-2 on the outer periphery joins, as shown in FIG. Although not shown, in FIG. 5, the distance between the symbol X and the symbol M is 100 nm. In condition 2, the angle between a first line connecting junction point X and intersection point Y and a second line connecting junction point X and intersection point Z is calculated at any 20 points. The average of the angles at the 20 points is set as the average angle for 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 close to the limit 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, so the pattern layer cannot be stably formed. 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, so the width of the recesses becomes wider. Therefore, when the average angle of condition 2 is 0 degrees, it is difficult for liquid crystal molecules to be oriented along the recesses near the joining point. If 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. For this reason, if 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 greater than 0 degrees and equal to or less 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 options for the upper limit and the lower limit of the numerical value are shown, one selected from the upper limit options and one selected from the lower limit options can be combined to form a numerical range. For example, in the case of condition 2, the numerical range can be 0 degrees or more and 20.0 degrees or less, 0 degrees or more and 15.0 degrees or less, 0 degrees or more and 12.0 degrees or less, 0 degrees or more 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 recesses of the first shape in the first direction varies depending on the optical properties to be desired, but is preferably 0.4 μm to 10,000 μm, more preferably 0.7 μm to 8,000 μm, and even more preferably 1.0 μm to 6,000 μm. The pitch P1 of the recesses of the first shape in the first direction is the same as the length W1 of the recesses of the first shape in the first direction. For this reason, it is preferable that W1 is also in the above-mentioned range. Setting P1 to 0.4 μm or more is preferable in that it makes it easier to align the liquid crystal molecules and obtains optical characteristics of blue (wavelength 450 nm) which is on the short wavelength side of the visible light region. In this specification, the pitch of the recesses and the length of the recesses are measured from a photograph of the first surface of the pattern layer taken with a scanning electron microscope.

[0030] The length H1 of the first shaped recess in the second direction cannot be generally determined as it varies depending on the desired optical properties, 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. It is preferable to set H1 to 0.1 μm or more in that this makes it easier to align the liquid crystal molecules.

[0031] The ratio (H1 / W1) of the length H1 in the second direction of the first shaped recess to the length W1 in the first direction of the first shaped recess 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] Regarding the planar shape of the recess of the first shape, the distance between the first arc 21-1 (arc on the inner circumference side) and the second arc 21-2 (arc on the outer circumference side) 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 setting the distance to 1 nm or more, the pattern layer can be more easily peeled off from the shaping plate, and the pattern layer can be more stably formed. By setting the distance to 100 nm or less, the liquid crystal molecules can be more easily aligned. The distance between the first arc and the second arc is determined as the average value of 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 in 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, the 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 off from the shaping plate, and the pattern layer can be more stably formed. The depth of other recesses, such as the recesses of the second shape, is also preferably within the above range. In this specification, the depth of the recess of the first shape is the average value of 18 depth values, excluding the maximum and minimum values, from 20 depth values ​​of the recess randomly selected. The depths of the other recesses, such as the recess of the second shape, are also average values ​​obtained by the above-mentioned method.

[0034] In this specification, the depth of the recesses such as the recesses of the first shape is measured by imaging the vertical cross section of the optical element with a scanning electron microscope. The depth of each recess means the maximum depth of each recess. The scanning electron microscope is preferably used for imaging under the following conditions. An example of the scanning electron microscope is the product name "SU8000" of Hitachi High-Technologies Corporation. <Imaging conditions> Acceleration voltage: 5.0Kv Emission current: 5.0uA Probe current: High Detector: SE(U) Working distance: 8mm Condenser lens 1:5.0 Condenser lens 2:1.0 Tilt function of the document table: Enter the tilt angle "0.0"

[0035] In the optical element of the present disclosure, it is preferable that the recesses of the first shape are further arranged at a predetermined pitch in the second direction. 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 that exerts a predetermined function within the surface of the optical element. In order to stably form the pattern layer, it is preferable that the recesses of the first shape do not join 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 stably form a pattern layer when preparing a plate for forming the pattern layer, and 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 the recesses of the first shape that are arranged at a predetermined pitch in the second direction. <Conditions for the concave portion of the second shape> (1) The recess of the second shape has 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 recess having the second shape in the first direction is shorter than the length of the recess having the first shape in the first direction. (4) The ends of the recesses of the second shape adjacent to each other in the first direction are not joined to each other.

[0038] FIG. 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. By providing the second recesses, the density of recesses in the first surface of the pattern layer can be increased, thereby increasing the area that exerts a predetermined function in the surface of the optical element.

[0039] The arc shape of the recess of the second shape preferably matches a portion of the arc shape of the recess of the first shape. The coincidence of the arc shape of the recesses of the second shape with a part 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, by the following steps A1 to A3. A1: A portion corresponding to the arc shape of the recess of the second shape is cut out from the image data of the photograph. A2: When the arc shape of the cut recess of the second shape is moved in the second direction, the area ratio of the overlapping area of ​​the arc shape of the recess of the second shape and the arc shape of the recess of the first shape is calculated. 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: When the area ratio is 90% or more, it is deemed that 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.

[0040] The length in the first direction of the recesses of the second shape may be adjusted in accordance with a desired density of the recesses, within a range shorter than the length in the first direction of the recesses of the first shape.

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

[0042] It is preferable that the optical element of the present disclosure further satisfies the following condition 3. <Condition 3> The angle between a tangent to the arc shape of the recess of the first shape and a line parallel to the first direction is defined as a 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 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.

[0043] 7 correspond to the first region, the second region, and the third region, respectively, of condition 3. Note that since FIG. 7 is a schematic diagram for easily explaining condition 3, 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 the different regions. By satisfying condition 3, it becomes easier to stably exhibit predetermined performance within the plane of the optical element. In condition 3, the difference between the maximum value and the minimum value is more preferably 7% or less, and even more preferably 5% or less.

[0045] In condition 3, the area ratios of 1 to 3 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 1 to 3 are calculated at any 20 points on the photograph, and the average value of the 20 points is set as the area ratios of 1 to 3.

[0046] The pattern layer may have a thickness below the recess. In Fig. 1, the reference character t2 indicates the thickness of the pattern layer below the recess. The average thickness below the recess is preferably 0.5 μm to 20 μm, more preferably 1 μm to 15 μm, and even more preferably 2 μm to 7 μm. 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 apply the liquid crystal layer onto the pattern layer. By setting t2 to 20 μm or less, it is possible to easily suppress the occurrence of curling. The average thickness below the recess means the average thickness of 8 locations excluding the maximum and minimum values ​​from among 10 locations arbitrarily taken in the cross-sectional photograph of the optical element.

[0047] <Pattern layer material> The pattern layer preferably contains a resin, and 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 the resin for the pattern layer include a thermoplastic resin and a cured product of a curable resin composition. Among these, a cured product of a curable resin composition is preferred in order to improve strength. The proportion of the cured product of the curable resin composition 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.

[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.In addition, from the viewpoint of suppressing damage to the pattern layer during the process of manufacturing the optical element, the ionizing radiation curable resin is more preferably a compound having two or more ethylenically unsaturated bond groups, and among them, a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups is even more preferable.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, as well as 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 (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 (meth)acrylate monomer may have a part of its molecular skeleton modified, and those modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like may also be used.

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

[0053] When the ionizing radiation curable resin is an ultraviolet ray curable resin, the coating liquid for forming the pattern layer preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. The photopolymerization initiator may be one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, and the like. The photopolymerization accelerator can reduce polymerization inhibition caused by air during curing and increase the curing speed, and examples of the accelerator include one or more types 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 a 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 coating liquid for forming a pattern layer containing a curable resin composition as the coating liquid for forming a pattern layer 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 ionizing radiation simultaneously with the shaping in step 2 to 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 a 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 the plate produced by the above-mentioned means, and arrange the many copies to produce a multi-faceted plate. The plate can be reproduced by a 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.

[0061] <Liquid crystal layer> In the optical element of the present disclosure, a liquid crystal layer is formed on the first surface of the pattern 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 pattern layer, and then drying and curing the liquid crystal layer as necessary.

[0062] The liquid crystal compound may be at least one 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 arrangement in which the direction of the molecules of the liquid crystal compound rotates when the liquid crystal layer is viewed in a plane. However, the direction of the molecules of the liquid crystal compound does not need to rotate 360 ​​degrees, and may rotate less than 360 degrees.

[0063] The liquid crystal compound is preferably a rod-shaped liquid crystal compound, and is not particularly limited, but examples of the rod-shaped liquid crystal compound include the compounds shown in (1) to (17) below.

[0064] [ka]

[0065] [ka]

[0066] Among the liquid crystal compounds, polymerizable rod-shaped liquid crystal materials are preferred. Examples of the polymerizable functional group of the polymerizable rod-shaped liquid crystal material include those that are polymerized by the action of ionizing radiation such as ultraviolet light or electron beams, or heat. Specific examples include radically polymerizable functional groups. Examples of the radically polymerizable functional group include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and more specifically, examples of the radically polymerizable functional group 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 on the entire surface of the first surface of the pattern layer, that is, the liquid crystal layer is preferably formed also on the portions of 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 be of a single layer structure or a multi-layer structure, but in order to reduce the thickness, the liquid crystal layer is preferably of a single layer structure. In order to improve the display quality by broadening the bandwidth of the optical element, it is preferable that the liquid crystal layer 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 dispersibility or negative wavelength dispersion. Negative wavelength dispersibility 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 dispersibility 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 where Re450 < Re550 is referred to as negative wavelength dispersibility. In this specification, the characteristic where Re450 > Re550 is referred to as positive wavelength dispersibility.

[0070] In an optical element in which a liquid crystal layer is laminated on a pattern layer, the shape of the pattern layer can be confirmed by, for example, the following method (1) or (2). Note that as long as the liquid crystal layer on the pattern layer can be easily removed, the shape of the pattern layer may be confirmed by a method other than the following methods (1) and (2). (1) In accordance with JIS K5600-5-6:1999, make a 100-square grid cut at 1 mm intervals on the surface of the liquid crystal layer. Then, attach a 18 mm cellophane tape (registered trademark) manufactured by Nichiban Co., Ltd. to the cut portion, and rub the tape with an eraser on top to firmly attach the tape to the coating film. Then, repeat the operation of instantaneously peeling off the tape 10 times or more to peel off the coating film. If a part of the coating film of the grid cut has peeled off during the above-described operation, it is preferable to repeat the above-described operation centering on the peeled portion. In this way, the shape of the pattern layer can be confirmed by peeling off the liquid crystal layer on the pattern layer. (2) Repeatedly perform the operation of cutting the optical element as thinly as possible in cross-section by a cross-section cutting method used during cross-section observation such as STEM and taking a cross-section STEM image. By connecting the obtained cross-section STEMs and visualizing them in a three-dimensional manner, the shape of the pattern layer can 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. 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 appropriately adjusted within the range of 5 μm or more and 1000 μm or less. The thickness of the substrate can be measured with 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 determined by measuring any ten points and averaging the measured value as described above.

[0074] The 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. The substrate preferably has a haze according to JIS K7136:2000 of 10% or less, more preferably 5% or less, and even more preferably 3% or less.

[0075] In order to suppress the 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 that 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 is 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, and the antistatic layer is preferably formed on the substrate opposite to the pattern layer.

[0077] <Phase difference> The optical element may have an average in-plane retardation within a predetermined range. When the controlled wavelength 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, when the optical element is used as a diffractive optical element, for example, the following effects can be achieved. (1) When circularly polarized light is incident on a 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 a diffractive optical element, the light can be diffracted and separated into right-handed circularly polarized light and left-handed circularly polarized light. The in-plane retardation of an optical element means 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 devices for measuring the in-plane retardation include "AxoStep" manufactured by AXOMETRICS and a two-dimensional birefringence evaluation system (product name: WPA-Micro) manufactured by Photonic Lattice. The former product is suitable for measuring a wide area, while the latter product is suitable for measuring a narrow area.

[0078] <Application> 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. The diffraction angle of light transmitted through a diffractive optical element can be adjusted to a predetermined range, so that, for example, the irradiation range of light can be widened or narrowed by using a diffractive optical element. Furthermore, by causing the light beams transmitted through the diffractive optical element to interfere with each other, it is possible to produce the effect of a lens, a prism, or the like. Due to the above-mentioned action, 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 the diffractive optical element can be expressed by the following formula, where the pitch is x [nm], the wavelength of light is λ [nm], and the angle of incidence of light is θ0. θ and θ0 are angles when the perpendicular direction to the plane of the diffractive optical element is 0 degrees. In the formula below, θ0 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 light that is the incident light, there are cases where the light is diffracted in the positive direction or the negative direction with respect to the perpendicular direction. In this specification, the pitch refers to the pitch P1 of the recesses of the first shape. sinθ=±(λ / x)+sinθ0

[0080] 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 and the diffraction angle is as shown in Table 1 below. [Table 1]

[0081] The diffraction angles in Table 1 are for a single 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 ×θ (degrees). EXAMPLES

[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. In addition, "parts" and "%" are based on mass unless otherwise specified.

[0083] 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 each measurement and evaluation, the target sample was exposed to the above atmosphere for 30 minutes to 60 minutes, and then the measurement and evaluation were performed.

[0084] 1-1. Planar shape of recesses in pattern layer The first surface of the pattern layer of the intermediate of the optical element of the example and the comparative example was imaged using a scanning electron microscope (Hitachi High-Technologies Corporation, product name "SU8000"). The imaging conditions were as follows. The intermediate refers to a laminate having a primer layer and a pattern layer on a substrate. Then, based on the image, the local angle of condition 1, the pitch P1 in the first direction, the pitch P2 in the second direction, the length H1 of the recess of the first shape in the second direction, the distance between the first arc and the second arc, the average angle of condition 2, and the difference in the area ratio of condition 3 were calculated by the method described in the specification. Furthermore, based on the image, it was determined whether or not the local angle of condition 1 changed continuously by the method described in the specification. The angle that changed continuously was marked "Yes", and the angle that did not change continuously was marked "No". The "distance between the first arc and the second arc" was expressed as "arc distance". In the comparative example in which the pattern layer could not be peeled off from the plate when forming the pattern layer, the result was marked "-". The results are shown in Table 3. <Imaging conditions> Acceleration voltage: 5.0Kv Emission current: 5.0uA Probe current: High Detector: SE(U) Working distance: 8mm Condenser lens 1:5.0 Condenser lens 2:1.0 Tilt function of the document table: Enter the tilt angle "0.0"

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

[0086] 1-3. Peelability The peelability was evaluated according to the following criteria, and 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 peeled off 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 peeled off from the plate. C: When forming the pattern layer, some of the resin remained on the shaping plate, and the pattern layer was not easily peeled off from the plate. D: When forming the pattern layer, the shaping plate could not be peeled off from the shaped layer.

[0087] 1-4. First Orientation The alignment of the liquid crystal layer was evaluated according to the following criteria for the optical elements of the examples and comparative examples. 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. It can be said that the less the Schlieren texture, the better the alignment of the liquid crystal molecules. A: Within an observation area 50 times square the pitch of the pattern layer, the number of Schlieren structures is zero, excluding those caused by dust. B: Within an observation area 50 times square the pitch of the pattern layer, the number of Schlieren structures, excluding those caused by dust, is between 1 and 9. C: Within an observation area 50 times the pitch of the pattern layer, the number of Schlieren structures 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 aligned along the direction of the first-shaped recesses in the vicinity of the junction point X where the ends of adjacent first-shaped recesses are joined was observed. For the observation, a two-dimensional birefringence evaluation system (product name: WPA-Micro) from Photonic Lattice was used. The second orientation was evaluated according to the following criteria. The second orientation was observed in a narrower region than the first orientation. A: In the vicinity of the joining point X, the difference between the orientation of the concave portion of the first shape and the orientation of the liquid crystal molecules is within 3.0 degrees. B: In the vicinity of the joining point X, the difference between the orientation of the concave portion of the first shape and the orientation of the liquid crystal molecules is more than 3.0 degrees and within 6.0 degrees. C: In the vicinity of the joining point X, the difference between the orientation of the concave portion of the first shape and the orientation of the liquid crystal molecules exceeds 6.0 degrees.

[0089] 2. Making the plate A simulation tool was used to design the shape of the first surface of the pattern layer. The first surface was arranged so that the recesses of the first shape were continuously arranged at a predetermined pitch in a first direction, and the ends of the recesses of the first shape adjacent in the first direction were joined to each other. Furthermore, the first surface was arranged so that the recesses of the first shape were arranged at a predetermined pitch in a second direction perpendicular to the first direction. The above simulation was performed so that, with regard to the planar shape of the recesses of the first shape, the local angle of 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 of condition 2, and difference in area ratio of condition 3 would be the values ​​shown in Table 2. Furthermore, the above simulation was performed so that the planar shape of the recesses of the first shape would satisfy condition 1. Using a 6-inch square synthetic quartz plate, a quartz master mold with the surface shape designed by simulation was created 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 mother mold, and then a transparent substrate was placed on 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 mother mold to obtain a resin plate having a shape complementary to that of the mother mold. Next, a replica mold of the mother mold, which is a mold having a shape complementary to that of the resin plate, was obtained by electroforming. A plurality of the replica molds were produced. A plurality of replica molds were wound around a roll to produce a roll-shaped plate to be used in the examples and comparative examples (Table 2).

[0090] 3. Fabrication of Optical Elements [Example 1] A primer layer having the following formulation was applied onto a substrate (a cycloolefin polymer having a thickness of 40 μm; Zeon Corporation's trade name "ZEONOR") and dried to form a primer layer having a thickness of 0.5 μm. Next, a coating solution 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, the roll-shaped plate prepared in "2" above is used to form a layer containing uncured resin, and at the same time, ultraviolet light is 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 the primer layer and the pattern layer on the substrate. Next, the following liquid crystal layer forming coating solution was applied onto the pattern layer, dried, and then irradiated with ultraviolet light (integrated light amount: 150 mJ / cm 2 ) to form a liquid crystal layer. The liquid crystal layer was formed by applying two coatings, the thickness of which was adjusted so that the in-plane retardation was 266 nm, using a liquid crystal having an in-plane birefringence (Δn) of 0.17. The above steps yielded the optical element of Example 1. The optical element of Example 1 was produced by roll-to-roll production.

[0091] <Coating solution 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

[0092] <Coating solution for forming pattern layer> Pentaerythritol triacrylate: 96 parts by weight (Manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) Photopolymerization initiator: 4 parts by weight (IGM, product name: Omnirad184)

[0093] <Liquid crystal layer coating solution> ·Rod-shaped liquid crystal molecules: 10 parts by mass (LC242 (product name), manufactured by BASF, in-plane birefringence (Δn)=0.17) Photopolymerization initiator: 0.4 parts by weight (IGM, product name: Omnirad184) Methyl ethyl ketone: 89.6 parts by weight

[0094] [Examples 2 to 10], [Comparative Examples 1 to 4] Except for changing the plate to that shown in Table 2, the same procedure as in Example 1 was carried out to obtain a laminate having a primer layer and a pattern layer on a substrate, and an optical element.

[0095] [Table 2]

[0096] [Table 3]

[0097] It can be seen from the results in Table 3 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. [Explanation of symbols]

[0098] 10: Base material 20: Pattern layer 20a: First side 20b: Second Side 21: Recess 22: First shape recess 23: Second shape recess 30: Liquid crystal layer 100: Optical elements A1: First direction A2: Second direction X: Junction

Claims

1. A pattern layer and a liquid crystal layer, the pattern layer has a first surface and a second surface opposite the first surface; the liquid crystal layer is formed on the first surface of the patterned layer; the pattern layer has a plurality of recesses of a first shape in the first surface; the first shape recess has an arc shape in a plan view, the recesses of the first shape are disposed continuously at a predetermined pitch in a first direction in the first plane, and ends of the recesses of the first shape adjacent to each other in the first direction are joined to each other; An optical element, wherein the concave portion of the first shape satisfies the following conditions 1 and 2: <Condition 1> 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 recess of the first shape has a minimum value of the local angle that is greater than -90.0 degrees and less than -80.0 degrees, a maximum value of the local angle that is greater than +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 is defined as a second' direction, a point where the ends of adjacent recesses of the first shape 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 in the first direction from point M with the recess of one first shape forming junction point X and the recess of the other first shape are defined as intersection Y and intersection Z, respectively. The average angle between 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.

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. 3. The optical element according to claim 2, wherein a recessed portion of a second shape that satisfies the following conditions (1) to (4) is disposed between the recessed portions of the first shape that are disposed at a predetermined pitch in the second direction: <Conditions for the Second Shape of Recess> (1) The recess of the second shape has 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 recess having the second shape in the first direction is shorter than the length of the recess having the first shape in the first direction. (4) The 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 second shaped recess coincides with a portion of the arc shape of the first shaped recess.

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 the liquid crystal layer has positive wavelength dispersion.

Images