Optical sheet and exposure method

Abstract

To provide an optical sheet having alignment marks that can easily detect an optical reference point of a functional region exhibiting an optical function such as a lens function, and an exposure method. An optical sheet having a functional region exhibiting an optical function and two alignment marks, wherein the functional region has a reference point of a physical property, and when viewed from a direction perpendicular to a main surface s of the optical sheet, one of the two alignment marks is present between the other of the two alignment marks and the reference point, and the reference point is present on a straight line passing through the two alignment marks.

Description

Technical Field

[0001] This invention relates to an optical film and an exposure method for manufacturing the optical film. Background Technology

[0002] Optical elements that control the direction of light are used in various optical devices. For example, they are used in backlighting of liquid crystal displays, AR (Augmented Reality) glasses, VR (Virtual Reality) glasses, MR (Mixed Reality) glasses, head-mounted displays (HMDs), head-up displays (HUDs), projectors, beam deflectors, and sensors for object detection and distance measurement.

[0003] As an optical element for controlling the direction of light, an optical sheet (optical element) having a liquid crystal layer has been proposed, which is formed by using a liquid crystal composition containing a liquid crystal compound and aligning the liquid crystal compound to a predetermined orientation state.

[0004] For example, Patent Document 1 describes a liquid crystal diffraction element that has at least an optical anisotropy layer (liquid crystal layer) formed using a liquid crystal composition containing a liquid crystal compound. The optical anisotropy layer has a liquid crystal alignment pattern that changes as the orientation of the optical axis derived from the liquid crystal compound rotates continuously in at least one direction within the plane. When the length of 180 degrees rotation of the optical axis in one direction is defined as one period, and one period gradually changes in one direction, starting from the longest period, when the average period of 50 periods in one direction is defined as Λa, in a region having a period with an average period of Λa or less, when observing the main surface of the optical anisotropy layer with an optical microscope, the ratio of the maximum to minimum width of 30 consecutive bright lines and the ratio of the maximum to minimum width of 30 consecutive dark lines in the region are both 1.2 or less.

[0005] Furthermore, Patent Document 1 describes the following: The optical anisotropic layer (liquid crystal layer) functions as a lens by having a radial pattern that aligns the liquid crystal pattern from the inside to the outside.

[0006] Previous technical documents Patent documents Patent Document 1: International Publication No. 2023 / 101002 Summary of the Invention

[0007] The technical problem to be solved by the invention This type of optical sheet can be cut to a size that includes areas (functional areas) that incorporate various optical functions, such as the function of a display lens. Furthermore, this type of optical sheet can be stacked on top of other optical components.

[0008] When cutting optical sheets to sizes that include functional areas, or when stacking them with other optical elements, high-precision alignment is required. For example, when an optical sheet functions as a lens, it is desirable to cut the optical sheet to the desired size using the center point of the lens as a reference point, or to align and stack it with other optical elements. However, liquid crystal layers formed using liquid crystal compositions containing liquid crystal compounds appear as flat films, exhibiting a lens effect through the liquid crystal alignment pattern. Therefore, the center cannot be visually observed like a typical lens (e.g., the convex vertex if it is a convex lens). Thus, to detect the optical reference point, it is necessary to assemble an optical system specifically for the optical sheet by combining polarizing filters, etc. However, for example, in optical systems that require the use of multiple polarizing filters, the light intensity is reduced due to the multiple polarizing filters, making it difficult to obtain an image with sufficient brightness. Consequently, the boundary lines of the image representing the reference point become blurred, and position detection based on image processing may not achieve sufficient accuracy.

[0009] The purpose of this invention is to solve the problems of the prior art and to provide an optical sheet and an exposure method that have alignment marks for easily detecting optical reference points of functional areas in an optical sheet with optical functions such as a display lens.

[0010] means for solving technical problems To address this issue, the present invention has the following structure.

[0011] [1] An optical sheet having a functional area for displaying optical functions and two alignment marks, wherein, Functional areas have physical reference points. When viewed from a direction perpendicular to the main surface of the optical plate, there is another alignment mark between one of the two alignment marks and the reference point. A reference point exists on the straight line passing through the two alignment marks.

[0012] [2] According to the optical sheet described in [1], wherein, Two alignment marks exist outside the functional area.

[0013] [3] According to the optical sheet described in [1], wherein, Two alignment marks exist within the functional area.

[0014] [4] The optical sheet according to any one of [1] to [3] has two sets of two alignment marks. A straight line passing through one set of two alignment marks intersects with a straight line passing through another set of two alignment marks. A reference point exists at the intersection of the two straight lines.

[0015] [5] The optical sheet according to any one of [1] to [3], wherein, The geometric center of the functional area is offset from the reference point.

[0016] [6] The optical sheet according to any one of [1] to [3] has the following characteristics: The liquid crystal layer is formed using a liquid crystal composition containing a liquid crystal compound. Functional regions and two alignment marks are formed in the liquid crystal layer. In the functional regions, the liquid crystal compound is oriented.

[0017] [7] According to the optical sheet described in [6], wherein, The liquid crystal compounds within the two alignment marks have different orientations.

[0018] [8] An exposure method, which is a method for interferometric exposure of a photosensitive layer, wherein, The photosensitive layer is exposed through a mask to form a pattern on the photosensitive layer that creates functional areas for displaying optical functions. Two light beams are respectively passed through a through hole in the shielding part of the mask to form alignment marks in the area of ​​the photosensitive layer exposed by only one light beam and the area exposed by only the other light beam.

[0019] [9] According to the exposure method described in [8], wherein, It has two through holes, forming two sets of two alignment marks.

[0020]

[10] An exposure method, which is a method for interferometric exposure of a photosensitive layer, wherein, The photosensitive layer is exposed to form a pattern on the photosensitive layer for creating functional areas that display optical functions. By setting a shielding part in the optical path of two beams to block a portion, alignment marks are formed in the area of ​​the photosensitive layer where the pattern is formed, in the area exposed by only one beam and in the area exposed by only the other beam.

[0021]

[11] According to the exposure method described in

[10] , wherein, It has two shielding parts, forming two sets of two alignment marks.

[0022] Invention Effects According to the present invention, an optical sheet and an exposure method are provided that have alignment marks for easily detecting optical reference points in an optical sheet having functional areas such as display lenses. Attached Figure Description

[0023] Figure 1 This is a conceptual diagram illustrating an example of the optical sheet used in this invention.

[0024] Figure 2 This is a conceptual diagram illustrating another example of the optical sheet used to explain the present invention.

[0025] Figure 3 This is a conceptual diagram illustrating another example of the optical sheet used to explain the present invention.

[0026] Figure 4 This is a conceptual diagram illustrating another example of the optical sheet used to explain the present invention.

[0027] Figure 5 This is a partial conceptual diagram illustrating another example of the optical sheet of the present invention.

[0028] Figure 6 This is a cross-sectional view conceptually illustrating a portion of the functional areas of the optical sheet of the present invention.

[0029] Figure 7 This is a top view conceptually illustrating a portion of the functional areas of the optical sheet of the present invention.

[0030] Figure 8 This is a conceptual illustration of an example of an exposure apparatus for exposing an alignment film used to manufacture the optical sheet of the present invention.

[0031] Figure 9 This is a conceptual diagram illustrating an example of the exposure method of the present invention.

[0032] Figure 10 It is a conceptual illustration for implementation. Figure 9 A top view of an example of a mask used in the exposure method shown.

[0033] Figure 11 This is a top view that conceptually illustrates another example of a mask.

[0034] Figure 12 This is a conceptual diagram illustrating another example of the exposure method of the present invention.

[0035] Figure 13 It is a conceptual illustration for implementation. Figure 12 A top view of an example of a mask used in the exposure method shown. Detailed Implementation

[0036] Hereinafter, the optical sheet of the present invention will be described in detail based on the preferred embodiment shown in the accompanying drawings.

[0037] In addition, the figures shown below are conceptual diagrams for illustrating the present invention, and the shapes, sizes, and positional relationships of the constituent elements differ from those in reality.

[0038] Furthermore, in this invention, the numerical range represented by “~” refers to the range encompassed by the numerical values ​​recorded before and after “~” as the lower and upper limits.

[0039] In this specification, unless otherwise specified, angles such as "45°", "parallel", "perpendicular" or "orthogonal" refer to angles that differ from the strict angle by less than 5 degrees. The difference from the strict angle is preferably less than 3 degrees, and more preferably less than 1 degree.

[0040] In this specification, terms such as “same” and “equal” include the range of error that is generally permissible in the relevant technical field.

[0041] In this specification, Re(λ) represents the in-plane delay at wavelength λ. Unless otherwise specified, wavelength λ is 550 nm.

[0042] In this specification, Re(λ) is a value measured at wavelength λ using an AxoScan (manufactured by Axometrics). The following is calculated by inputting the average refractive index ((nx+ny+nz) / 3) and film thickness (d(μm)) into the AxoScan.

[0043] Slow axis direction (°) Re(λ) = R0(λ) Additionally, R0(λ) represents the value calculated by AxoScan, but refers to Re(λ).

[0044] Figure 1 The image below conceptually illustrates an example of the optical sheet of the present invention. Figure 1 This is a top view of the optical sheet 10 viewed from a direction perpendicular to the main surface. Furthermore, in this application, the main surface refers to the largest surface of the sheet-like object (film-like object, plate-like object).

[0045] exist Figure 1 In the example shown, the optical sheet 10 has a region (functional region) that displays the function of a liquid crystal lens (liquid crystal diffraction lens). As will be described later, Figure 1 The optical sheet 10 shown can be a single layer of liquid crystal with functional regions, or it can be a stack of liquid crystal layers, alignment films and supports.

[0046] Figure 1The optical sheet 10 shown has a liquid crystal layer formed using a liquid crystal composition containing a liquid crystal compound 40. The liquid crystal layer has a functional region 12 where the liquid crystal compound 40 is oriented in a predetermined orientation state to exhibit optical functions, and an unoriented region 14 where the liquid crystal compound 40 is not oriented. Figure 1 In the example shown, the main surface of the optical sheet 10 is roughly rectangular in shape, with a roughly circular functional area 12 and an unoriented area 14 around it.

[0047] exist Figure 1 In the example shown, the functional region 12 has a liquid crystal alignment pattern that changes while continuously rotating in at least one direction along the optical axis of the liquid crystal compound 40. Specifically, it has a radial liquid crystal alignment pattern that changes while continuously rotating in one direction, with the optical axis of the liquid crystal compound 40 radiating outwards from the inside. In a liquid crystal layer having this liquid crystal alignment pattern, it can also be said that the lines connecting the liquid crystal compounds 40 with the same optical axis orientation are circular, and the circular line segments are arranged in a concentric circle pattern.

[0048] The functional region 12 with its radial liquid crystal alignment pattern allows incident light to be transmitted as either diverging or focused light, depending on the rotation direction of the optical axis of the liquid crystal compound 40 and the direction of the transmitted circularly polarized light. That is, by setting the liquid crystal alignment pattern of the functional region 12 to a radial shape, the functional region 12 functions, for example, as a concave or convex lens. The liquid crystal alignment pattern of the functional region 12 will be described in detail later.

[0049] This functional area 12, which acts as a lens, has the center of the lens. Figure 1 In the example shown, the center of the lensing effect of functional region 12 is the reference point P0 for the physical characteristics in this invention. More precisely, the intersection of the optical axis of the lens and functional region 12 is exemplified as the reference point for the physical characteristics. Figure 1 In the example shown, the center of the radial liquid crystal alignment pattern, originating from multiple points where the orientation of the optical axis of the liquid crystal compound 40 changes simultaneously with continuous rotation, intersects in one direction and becomes the center of the lens; therefore, this point becomes the reference point P0 for physical properties. Furthermore, in Figure 1 In the example shown, the geometric center of functional region 12 coincides with the location of reference point P0.

[0050] Here, the optical sheet of the present invention has two alignment marks. When viewed from a direction perpendicular to the main surface of the optical sheet, there is another alignment mark between one of the two alignment marks and a reference point. The reference point is located on a straight line passing through the two alignment marks.

[0051] exist Figure 1 In the example shown, the optical plate 10 has two alignment marks P1 and P2 on the outer side of the functional region 12, i.e., the unoriented region 14. Furthermore, a reference point P0 exists on an imaginary straight line L1 passing through the two alignment marks P1 and P2. That is, the reference point P0 and the two alignment marks P1 and P2 are aligned on a straight line.

[0052] Furthermore, there is another alignment mark P1 between one of the two alignment marks, alignment mark P2, and the reference point P0. That is, the reference point P0 does not exist between the two alignment marks P1 and P2, but exists outside the two alignment marks P1 and P2. In other words, the two alignment marks P1 and P2 exist on a straight line in one direction of either of the radial liquid crystal alignment patterns.

[0053] In the regions marked with alignment marks, the liquid crystal compound 40 is oriented in an orientation different from either the functional region 12 or the unoriented region 14. For example, in the regions marked with alignment marks P1 and P2, the liquid crystal compound 40 is uniaxially oriented. Furthermore, it is preferable that the orientation direction of the uniaxial orientation of the liquid crystal compound 40 in alignment mark P1 is different from, for example, substantially orthogonal to, the orientation direction of the uniaxial orientation of the liquid crystal compound 40 in alignment mark P2.

[0054] As described above, optical sheets are used by cutting functional areas to include various optical functions, such as lens effects. These optical sheets are then stacked with other optical elements. High-precision alignment is required when cutting the optical sheet to the size that includes the functional areas or when stacking it with other optical elements. For example, when the optical sheet has a lens effect, it is desirable to cut the optical sheet to the desired size using the center point of the lens as a reference point, or to align and stack it with other optical elements. However, optical sheets are flat films in appearance, and their center cannot be observed with the naked eye as in a typical lens (e.g., the convex vertex if it is a convex lens). Therefore, to detect the optical reference point, it is necessary to assemble an optical system specifically for the optical sheet by combining polarizing filters, etc. However, for example, in the case of an optical system that requires the use of multiple polarizing filters, the light intensity is reduced due to the multiple polarizing filters, making it difficult to obtain an image with sufficient brightness. This results in blurred boundary lines representing the reference point, and insufficient accuracy cannot be obtained through image processing-based position detection.

[0055] For example, such as Figure 1 In the example shown, when the functional region 12 has a structure with a radial liquid crystal alignment pattern, the alignment direction of the liquid crystal compound 40 gradually changes towards the center side, making it difficult to accurately detect the alignment direction of the liquid crystal compound 40 near the center to detect the center position.

[0056] In contrast, the optical sheet 10 of the present invention has two alignment marks P1 and P2, and a reference point P0 with the physical characteristics of a functional region 12 on a straight line L1 passing through the two alignment marks P1 and P2. The reference point P0 is not located between the two alignment marks P1 and P2, but rather on the outer side between them. Within the regions of the two alignment marks P1 and P2, the liquid crystal compound is uniaxially oriented, thus making it easy and accurate to detect the alignment marks P1 and P2. For example, if light is irradiated through a linear polarizer, the alignment marks P1 and P2 can be easily detected because the amount of transmitted light in the surrounding unoriented region 14 differs from that of the alignment marks P1 and P2. Therefore, by detecting the two alignment marks P1 and P2, the reference point P0 with physical characteristics existing on the straight line L1 passing through the two alignment marks P1 and P2 can be easily and accurately detected.

[0057] Furthermore, the two alignment marks P1 and P2 do not sandwich the reference point P0 between them. The two alignment marks P1 and P2 can be positioned close to each other. Therefore, compared to the case where the reference point P0 is between the two alignment marks P1 and P2, it is easier to detect the two alignment marks P1 and P2 by measuring within a narrow area.

[0058] Here, in Figure 1 In the example shown, the two alignment marks P1 and P2 are configured as an unoriented region 14 located outside the functional region 12, but are not limited to this. Figure 2 This is a diagram that conceptually illustrates another example of the optical sheet of the present invention.

[0059] Figure 2 The optical element 10b shown has two alignment marks P5 and P6 within the functional region 12. Additionally, Figure 2 The example shown has the same characteristics as the example shown, except that the positions of the two alignment marks P5 and P6 are different. Figure 1 The optical plate 10a shown has the same structure, therefore the following mainly describes the differences. Furthermore, in Figure 2 In the example shown, to clearly indicate the positions of alignment marks P5 and P6, the illustration of the alignment state (liquid crystal alignment pattern) of the liquid crystal compound 40 in functional region 12 is omitted. However, the alignment state (liquid crystal alignment pattern) of the liquid crystal compound 40 in functional region 12 is consistent with... Figure 1 The example shown is the same.

[0060] Figure 2The optical sheet 10b shown has a liquid crystal layer formed using a liquid crystal composition containing a liquid crystal compound 40. The liquid crystal layer has functional regions 12 where the liquid crystal compound 40 is oriented according to the liquid crystal alignment pattern described above, and unoriented regions 14 where the liquid crystal compound 40 is not oriented. As described above, the functional regions 12 function as lenses, and the reference point P0 has the center of the lens.

[0061] Figure 2 The optical element 10b shown has two alignment marks P5 and P6 within the functional region 12. Furthermore, a reference point P0 exists on an imaginary straight line L3 passing through the two alignment marks P5 and P6. That is, the reference point P0 and the two alignment marks P5 and P6 are aligned on a straight line.

[0062] Furthermore, among the two alignment marks, one alignment mark P6 exists between itself and the reference point P0, while the other alignment mark P5 exists between them. That is, the reference point P0 does not exist between the two alignment marks P5 and P6, but rather exists outside the area between them. In other words, the two alignment marks P5 and P6 exist on a straight line in a single direction of either of the radial liquid crystal alignment patterns.

[0063] Furthermore, in the regions marked with alignment marks P5 and P6, the liquid crystal compound 40 is oriented in a different orientation state than the functional region 12.

[0064] Thus, even when alignment marks P5 and P6 are positioned within functional area 12, alignment marks P5 and P6 can be easily and accurately detected. Therefore, by detecting the two alignment marks P5 and P6, the reference point P0 of the physical characteristics existing on the straight line L3 passing through the two alignment marks P5 and P6 can be easily and accurately detected.

[0065] Furthermore, if the alignment mark is disposed in the functional region 12, it may obstruct the optical properties of the functional region 12. Therefore, the alignment mark is preferably disposed in the region outside the functional region 12 (unoriented region 14).

[0066] Furthermore, in Figure 1 In the example shown, it is assumed to have a set of two alignment marks P1 and P2, but it is not limited to this. Figure 3 This is a diagram that conceptually illustrates another example of the optical sheet of the present invention.

[0067] Figure 3 The optical plate 10c shown has two alignment marks P1 and P2 and two alignment marks P3 and P4 in the unaligned region 14. That is, the optical plate 10c has two sets of two alignment marks. Furthermore, Figure 3 The example shown, in addition to having two sets of two alignment marks, has the same... Figure 1The optical sheet 10a shown has the same structure, so the differences will be explained below.

[0068] Figure 3 The optical sheet 10c shown has a liquid crystal layer formed using a liquid crystal composition containing a liquid crystal compound 40. The liquid crystal layer has functional regions 12 where the liquid crystal compound 40 is oriented according to the liquid crystal alignment pattern described above, and unoriented regions 14 where the liquid crystal compound 40 is not oriented. As described above, the functional regions 12 function as lenses, and the reference point P0 has the center of the lens.

[0069] Figure 3 The optical plate 10c shown has two alignment marks P1 and P2 and two alignment marks P3 and P4 within the functional region 12. Furthermore, there is a reference point P0 on an imaginary straight line L1 passing through one set of alignment marks P1 and P2, and another reference point P0 on an imaginary straight line L2 passing through another set of alignment marks P3 and P4.

[0070] Furthermore, in one set of two alignment marks, there is another alignment mark P1 between one alignment mark P2 and the reference point P0. And in another set of two alignment marks, there is another alignment mark P3 between one alignment mark P4 and the reference point P0.

[0071] Furthermore, in the regions of alignment marks P1, P2, P3, and P4, the liquid crystal compound 40 is oriented in a different orientation state than the functional region 12.

[0072] Furthermore, the straight line L1 passing through alignment marks P1 and P2 is not parallel to and intersects the straight line L2 passing through alignment marks P3 and P4. In this case, as... Figure 3 As shown, the reference point P0 exists at the intersection of line L1 and line L2.

[0073] exist Figure 3 In the example shown, there are two sets of two alignment marks in pairs, so the reference point P0 can be determined at the intersection of the straight lines defined by the two sets of two alignment marks, thus making detection easier and more accurate.

[0074] Furthermore, from the viewpoint that the reference point P0 can be detected more easily and accurately, the angle between the two sets of lines (L1 and L2) marked by the alignment marks is preferably 30° to 90°, more preferably 60° to 90°, and even more preferably 89° to 90°.

[0075] Furthermore, in Figure 1 In the example shown, the structure is designed such that the geometric center of the functional region 12 coincides with the reference point P0 of the optical function (physical properties) manifested by the functional region 12, but it is not limited to this. Figure 4This is a diagram that conceptually illustrates another example of the optical sheet of the present invention.

[0076] Figure 4 The optical plate 10d shown has two alignment marks P1 and P2 in the unaligned region 14. Additionally, Figure 4 In the example shown, the structure of functional region 12b is different; otherwise, it has the same characteristics as... Figure 1 The optical plate 10a shown has the same structure, therefore the following mainly describes the differences. Furthermore, in Figure 4 In the example shown, in order to clarify with Figure 1 The difference in functional region 12 shown in the example, the illustration of liquid crystal compound 40 within functional region 12b is omitted, and the line connecting the liquid crystal compounds oriented in a certain direction is shown.

[0077] Figure 4 The optical sheet 10d shown has a liquid crystal layer formed using a liquid crystal composition containing a liquid crystal compound 40. The liquid crystal layer has functional regions 12b in which the liquid crystal compound 40 is oriented in a predetermined pattern and unoriented regions 14 in which the liquid crystal compound 40 is not oriented.

[0078] exist Figure 4 In the example shown, functional region 12b has the following off-center liquid crystal alignment pattern: in the left-right direction (X-axis direction) of the figure, the length of one cycle in the direction from reference point P0 to the right is different from the length of one cycle in the direction from reference point P0 to the left. The length of one cycle will be described in detail later.

[0079] The reference point P0 and the geometric center P of the functional region 12b with this liquid crystal alignment pattern are used to determine the physical properties of the functional region 12b. x Offset. In the example diagram, functional area 12b is approximately circular, therefore the geometric center P... x It is the center of the circle.

[0080] Thus, even at the geometric center P of functional region 12b x Even if the reference point P0 of the physical property is not the same as the reference point P0, the reference point P0 also exists on the imaginary straight line L1 passing through the two alignment marks P1 and P2. Therefore, by detecting the two alignment marks P1 and P2, the reference point P0 of the physical property existing on the straight line L1 passing through the two alignment marks P1 and P2 can be easily and accurately detected.

[0081] In addition, Figure 4The example shown illustrates an example where the liquid crystal alignment pattern of functional region 12b is an off-center liquid crystal alignment pattern, but it is not limited to this. It could also have the following structure: the liquid crystal alignment pattern of functional region 12b is the aforementioned concentric (radial) liquid crystal alignment pattern, with its physical reference point P0 and the geometric center P of functional region 12b. x Offset.

[0082] In the examples described above, the shape of the main surface of the optical sheet is set to a rectangle, but it is not limited to this. Depending on the shape of other optical elements in the stacked optical sheet, it can be set to various shapes such as circles, ellipses, polygons, and irregular shapes.

[0083] Furthermore, in the examples above, the shape of the functional area is set to be circular, but it is not limited to this. Depending on the shape of other optical elements in the stacked optical sheet, it can be set to various shapes such as rectangle, ellipse, polygon, irregular shape, etc.

[0084] Furthermore, there are no particular restrictions on the shape and size of the alignment mark. For example, the alignment mark can be any shape, such as a circle, cross, quadrilateral, triangle, or other polygons, C-shapes, etc. From the viewpoint of ease of detection of the alignment mark and detection accuracy of the reference point P0, the size of the alignment mark is preferably 0.1 mm to 3 mm in diameter of the circle tangent to the alignment mark, more preferably 0.5 mm to 2 mm, and even more preferably 1 mm to 1.5 mm.

[0085] Furthermore, in Figure 1 and Figure 4 In the example shown, the two alignment marks, which are set as a group, are both positioned in the unoriented region 14. Figure 3 In the example shown, both alignment marks are configured in functional region 12, but this is not a limitation. Alternatively, one of the two alignment marks, which are a group, can be configured in unaligned region 14, and the other can be configured in functional region 12.

[0086] Furthermore, in Figure 3 In the example shown, two sets of two alignment marks are configured in the unoriented region 14, but this is not a limitation. Alternatively, two sets of two alignment marks can be configured in the functional region 12, or one set of two alignment marks can be configured in the functional region 12, while the other set of two alignment marks can be configured in the unoriented region 14.

[0087] and, Figure 1 The two alignment marks shown as a group are configured separately, but are not limited to this. Figure 5 This is a partially enlarged view conceptually illustrating another example of the optical sheet of the present invention.

[0088] exist Figure 5 In the example shown, the two alignment marks P7 and P8, which form a group, are in contact with each other in a partially overlapping manner. In this way, the two alignment marks that form a group can make contact.

[0089] The distance between two alignment marks that form a set is not particularly limited. From the viewpoints of miniaturization of the optical sheet and miniaturization of the inspection area during alignment mark detection, it is preferable that the two alignment marks are close together. On the other hand, from the viewpoints of the detection accuracy of the reference point P0, it is preferable that the two alignment marks are separated to a certain extent. From the above viewpoints, the distance between the two alignment marks is preferably 1mm to 5mm, more preferably 1mm to 3mm, and even more preferably 1mm to 2mm.

[0090] Furthermore, in the examples described above, the unoriented region 14 is defined as an unoriented region of the liquid crystal compound 40, but it is not limited to this. The unoriented region 14 (the region other than the functional region) can be oriented in a different orientation state than the functional region 12. For example, the unoriented region 14 can be a region of uniaxial orientation of the liquid crystal compound 40, or it can be an orientation pattern with an opposite phase to the functional region 12, an orientation pattern with a different pitch and / or orientation from the orientation pattern of the functional region 12, a random orientation, etc.

[0091] Furthermore, in the examples described above, the region of the alignment mark is defined as a region where the liquid crystal compound 40 is uniaxially oriented, but this is not a limitation. It is permissible as long as the alignment mark and the surrounding region (unoriented region 14 or functional region 12) have different orientation states of the liquid crystal compound. For example, when the alignment mark is disposed in the unoriented region 14 and the liquid crystal compound 40 is uniaxially oriented in the unoriented region 14, the region of the alignment mark can be a region where the liquid crystal compound 40 is uniaxially oriented in a direction different from that of the unoriented region 14, or it can be a region where the liquid crystal compound 40 is unoriented and un-oriented. Similarly, when the alignment mark is disposed in the functional region 12, the region of the alignment mark can be a region where the liquid crystal compound 40 is uniaxially oriented, or it can be a region where the liquid crystal compound 40 is unoriented and un-oriented.

[0092] Furthermore, in the regions of the two alignment marks that form a pair, in the case of uniaxial orientation of the liquid crystal compound 40, the directions of the uniaxial orientation in the regions of the two alignment marks can be the same or different.

[0093] Next, use Figure 6 and Figure 7 right Figure 1 The functional area 12 of the optical sheet shown will be explained. Figure 6 This is a cross-sectional view conceptually illustrating a portion of the functional areas of the optical sheet of the present invention. Figure 7 Viewed from above (Z direction). Figure 6 A top view of the functional areas shown.

[0094] As mentioned above, Figure 1 The optical sheet shown includes a liquid crystal layer with functional regions that display the function of a liquid crystal lens (liquid crystal diffraction lens). Figure 6 In the middle, the optical sheet 10 is a stack of a support 30, an alignment film 32 and a liquid crystal layer 36 stacked in sequence.

[0095] The functional regions 12 of the liquid crystal layer 36 have a liquid crystal alignment pattern that changes as the orientation of the optical axis 40A of the liquid crystal compound 40 continuously rotates in at least one in-plane direction. Additionally, in Figure 1 , Figure 3 and Figure 7 In order to simplify the accompanying drawings and clearly show the structure of the functional region 12, only the liquid crystal compound 40 in the interface on the alignment film side of the liquid crystal layer 36 is shown. However, as Figure 6 As shown, the liquid crystal layer 36, like a liquid crystal layer formed using a composition containing a conventional liquid crystal compound, has a structure in which the liquid crystal compound 40 is stacked along the thickness direction. Furthermore, in Figure 6 and Figure 7 In this example, a rod-shaped liquid crystal compound is shown as liquid crystal compound 40, so the direction of the optical axis is consistent with the length direction of liquid crystal compound 40.

[0096] Specifically, in Figure 6 and Figure 7 In the functional region 12 shown, the orientation of the optical axis 40A of the liquid crystal compound 40 changes while continuously rotating in the direction indicated by arrow D. Specifically, the angle between the optical axis 40A of the liquid crystal compound 40 arranged along the direction of arrow D and the direction of arrow D varies depending on the position of the arrow direction. Along the direction of arrow D, the angle between the optical axis 40A and the direction of arrow D changes sequentially from θ to θ+180° or θ-180°.

[0097] On the other hand, in the liquid crystal compound 40 forming the functional region 12, liquid crystal compounds 40 with the same orientation of the optical axis 40A are arranged at equal intervals in the Y direction, which is orthogonal to the direction of arrow D, i.e., in the Y direction of continuous rotation of the optical axis 40A. In other words, in the liquid crystal compound 40 forming the functional region 12, the angle between the orientation of the optical axis 40A and the direction of arrow D is equal for the liquid crystal compounds 40 arranged in the Y direction. Figure 1In the functional region 12 shown, regions with the same orientation of the optical axis 40A are formed in a circular shape with the center aligned, forming a concentric liquid crystal alignment pattern.

[0098] In a liquid crystal alignment pattern where the optical axis 40A rotates continuously in one direction, the length (distance) of the optical axis 40A of the liquid crystal compound 40 rotating 180° becomes the length Λ of one cycle in the liquid crystal alignment pattern. That is, if it is Figure 7 The functional region 12 shown is defined as the length (distance) by which the optical axis 40A of the liquid crystal compound 40 is rotated 180° in the direction of arrow D, where the orientation of the in-plane optical axis 40A changes continuously. In other words, one period Λ in the liquid crystal alignment pattern is defined by the distance from θ to θ+180° between the angle between the optical axis 40A of the liquid crystal compound 40 and the direction of arrow D.

[0099] In other words, the distance between the centers of two liquid crystal compounds 40 with equal angles relative to the direction of arrow D in the direction of arrow D is one period Λ. Specifically, as... Figure 7 As shown, the distance between the centers of the two liquid crystal compounds 40 whose arrow D direction is consistent with the direction of the optical axis 40A is one period Λ.

[0100] In functional region 12, the liquid crystal alignment pattern repeats one cycle Λ in a direction that changes as it rotates continuously in the direction of arrow D, i.e., the direction of optical axis 40A.

[0101] In functional region 12, among the liquid crystal compounds arranged in the Y direction, the angle formed by the optical axis 40A and the direction of arrow D is equal. The region in the Y direction where the liquid crystal compound 40 with the angle formed by the optical axis 40A and the direction of arrow D is arranged is designated as region R.

[0102] In this case, the value of the in-plane retardation (Re) in each region R is preferably half a wavelength, i.e., λ / 2. This in-plane retardation is calculated by multiplying the refractive index difference Δn associated with the refractive index anisotropy of region R by the thickness of the functional region 12. The refractive index difference associated with the refractive index anisotropy of region R is defined as the difference between the refractive index in the direction of the slow axis within the plane of region R and the refractive index in the direction orthogonal to the slow axis. That is, the refractive index difference Δn associated with the refractive index anisotropy of region R is equal to the difference between the refractive index of the liquid crystal compound 40 in the direction of the optical axis 40A and the refractive index of the liquid crystal compound 40 in the direction perpendicular to the optical axis 40A within the plane of region R. In other words, the aforementioned refractive index difference Δn is equal to the refractive index difference of the liquid crystal compound.

[0103] Furthermore, in a liquid crystal lens (functional region 12) having a concentric circular liquid crystal alignment pattern with a radially rotating liquid crystal alignment pattern having an optical axis 40A continuously rotating in one direction, the regions with the same orientation of the optical axis 40A, which are formed in a ring shape with the same center, are equivalent to... Figure 7 Region R in the middle.

[0104] If circularly polarized light is incident on this functional region 12, the light is diffracted, and the direction of the circularly polarized light is reversed. This effect will be explained below. In functional region 12, the product of the refractive index difference of the liquid crystal compound and the thickness of the liquid crystal layer is set to λ / 2.

[0105] Furthermore, this effect is exactly the same in a liquid crystal lens having a concentric liquid crystal alignment pattern with a liquid crystal alignment pattern that rotates continuously in one direction with an optical axis 40A.

[0106] When the product of the refractive index difference of the liquid crystal compound in functional region 12 and the thickness of the liquid crystal layer is λ / 2, if incident light as left-handed circularly polarized light is incident on functional region 12, the incident light is given a phase difference of 180° through functional region 12, and the transmitted light is converted into right-handed circularly polarized light. Furthermore, the liquid crystal alignment pattern formed in functional region 12 is a periodic pattern in the direction of arrow D, so the transmitted light travels in a direction different from the direction of travel of the incident light. Thus, the incident light of left-handed circularly polarized light is converted into transmitted light of right-handed circularly polarized light that is tilted at a predetermined angle relative to the incident direction in the direction of arrow D.

[0107] On the other hand, when the product of the refractive index difference of the liquid crystal compound in functional region 12 and the thickness of the liquid crystal layer is λ / 2, if right-handed circularly polarized incident light is incident on functional region 12, the incident light is given a 180° phase difference through functional region 12 and is converted into left-handed circularly polarized transmitted light. Furthermore, the liquid crystal alignment pattern formed in functional region 12 is a periodic pattern in the direction of arrow D, therefore the transmitted light travels in a direction different from the direction of travel of the incident light. At this time, the transmitted light travels in a direction different from the incident direction, that is, in a direction opposite to the direction of arrow D relative to the incident direction. Thus, the incident light is converted into left-handed circularly polarized transmitted light that is tilted at only a predetermined angle relative to the incident direction towards arrow D.

[0108] In functional region 12, a liquid crystal alignment pattern is continuously rotated in one direction along an optical axis 40A having liquid crystal compound 40 radially. Furthermore, the direction of rotation is the same in all directions (one direction) from the center outwards.

[0109] The functional region 12, which has a liquid crystal alignment pattern that changes radially with continuous rotation originating from the optical axis of the liquid crystal compound, can cause incident light to diverge or converge and be transmitted depending on the rotation direction of the optical axis of the liquid crystal compound 40 and the rotation direction of the incident circularly polarized light. In other words, this functional region 12 functions as a concave lens depending on the rotation direction of the incident circularly polarized light, for example, in the case of right-handed circularly polarized light and in the case of left-handed circularly polarized light. Alternatively, the functional region 12 functions as a convex lens in the case of right-handed circularly polarized light and as a concave lens in the case of left-handed circularly polarized light.

[0110] In the functional region 12, which functions as a liquid crystal lens, the liquid crystal alignment pattern preferably changes in one direction (arrow D direction) while the orientation of the optical axis of the liquid crystal compound 40 rotates continuously, with the length of one cycle gradually decreasing from the inside to the outside. This allows for more appropriate focusing or divergence of the incident circularly polarized light.

[0111] Thus, the liquid crystal layer having the functional region 12 that functions as a liquid crystal lens is preferably formed by coating a liquid crystal composition containing a liquid crystal compound onto an alignment film described later, aligning the liquid crystal compound into a predetermined liquid crystal alignment pattern, and then curing the liquid crystal compound to form the liquid crystal layer containing the functional region 12.

[0112] The coating of liquid crystal compositions can be achieved using printing methods such as inkjet and roll printing, as well as all known methods that can uniformly coat liquids onto sheets, such as spin coating, bar coating, and spray coating.

[0113] The coated liquid crystal composition is dried and / or heated as needed, and then cured to form a liquid crystal layer containing the functional regions 12. During this drying and / or heating process, the liquid crystal compounds in the liquid crystal composition are oriented according to a predetermined liquid crystal orientation pattern. When heating is performed, the heating temperature is preferably 200°C or lower, more preferably 130°C or lower.

[0114] The oriented liquid crystal compound is then polymerized as needed. Polymerization can be either thermal polymerization or photopolymerization based on light irradiation, but photopolymerization is preferred. Ultraviolet light is preferably used for light irradiation. The irradiation energy is preferably 20 mJ / cm². 2 ~50J / cm 2 More preferably 50–1500 mJ / cm 2 To promote the photopolymerization reaction, light irradiation can also be carried out under heating conditions or in a nitrogen atmosphere. The wavelength of the irradiated ultraviolet light is preferably 250–430 nm.

[0115] There is no limitation on the thickness of the liquid crystal layer including the functional region 12, as long as it is appropriately set according to the purpose of the optical sheet, the performance required in the functional region 12, and the forming material of the liquid crystal layer.

[0116] The manner in which the functional region 12 (liquid crystal layer) functions as a liquid crystal lens and the materials of the liquid crystal layer (liquid crystal composition) are described in International Publication Nos. 2019 / 189675, 2019 / 189818, 2020 / 066429, 2021 / 040012, and 2022 / 050319.

[0117] Furthermore, in the examples described above, the optical sheet 10 includes a liquid crystal layer, and the functional region 12 of the liquid crystal layer is designed to function as a liquid crystal lens, but is not limited to this. As long as the reference point exhibits optical function and has physical characteristics, various known optical sheets can be used.

[0118] Here, the reference point of the functional region 12 refers to a point that can be defined as a reference point of a certain physical property existing in the plane of the functional region 12. For example, the reference point of the functional region 12 may include the center point of physical properties such as the optical axis of a lens, the transition point or branch point of physical properties in the plane such as retardation, refractive index, diffraction characteristics and polarization selectivity, the intersection point of optical axes such as optical axis, slow axis and transmission axis, and the rotation center axis of a spiral phase plate used for the generation of topological light waves, etc.

[0119] Specifically, a preferred example of a functional region having a reference point within the plane of the region, which displays optical functions, is a lens element. A lens element having an optical axis can use the optical axis of the lens element as a reference point. More precisely, the intersection of the functional region of the lens element and the optical axis of the lens element can be used as a reference point.

[0120] Such lens elements are preferably formed by having one or more of the following on a resin substrate: a structure that exhibits optical effects through geometric phase distribution, such as a liquid crystal lens; a microstructure such as a metasurface or Fresnel lens structure; a holographic layer that has at least a refractive index distribution or light absorption distribution within the layer; a liquid crystal layer that has at least a birefringence in plane distribution or light absorption anisotropy in plane distribution within the layer; and a nanocomposite layer that has at least a birefringence in plane distribution or light absorption anisotropy in plane distribution within the layer. These lens elements are thin film or sheet-like in shape and can simultaneously perform the function of a lens.

[0121] As a functional region with a reference point within the plane that displays other optical functions, and which is also the area displaying the optical functions, a forked polarizing diffraction element as described in Japanese Patent Application Publication No. 2021-043295 is a preferred example. In this case, for example, the branch point of the fork can be used as the reference point.

[0122] Furthermore, the spiral-type phase difference plate described in Japanese Patent Application Publication No. 2015-163912 and other publications can preferably be exemplified as a functional region having a reference point in the plane. In this case, for example, the center point of the spiral can be used as the reference point.

[0123] Furthermore, the stacked optical element described in Japanese Patent Application Publication No. 2009-151287, etc., can preferably be exemplified as a functional region having a reference point in the plane. In this case, for example, the intersection of the symmetry axes generated by stacking a phase difference layer having a symmetry axis in the X direction and having a slow axis direction distribution that varies with reference to that symmetry axis, and a phase difference layer having a symmetry axis in the Y direction and having a slow axis direction distribution that varies with reference to that symmetry axis, can be used as the reference point. Specifically, in Figures 4-6 In the diagram, point 13 in each figure becomes the reference point.

[0124] Furthermore, the spatially deformable wavelength plate described in Japanese Patent Application Publication No. 2008-233903, etc., can preferably be exemplified as a functional region having a reference point in the plane. In this case, for example, the center point on the arrangement layer can be used as the reference point. Specifically, Figure 2 Point 18 of B becomes the reference point.

[0125] Furthermore, optical elements with non-uniform retardation as described in Japanese Patent Publication Nos. 2021-500629 and 2020-515903 can preferably be exemplified as functional regions having reference points in the plane. In this case, for example, when performing quadrant division as described in Japanese Patent Publication No. 2021-500629, the center point of the quadrant can be used as the reference point. Furthermore, if the optical element has a distribution of phase difference or fast axis direction, and this distribution has a symmetrical point, that symmetrical point can be used as the reference point. Moreover, if the distribution has multiple axes of symmetry, the intersection of these axes of symmetry can be used as the reference point.

[0126] In this invention, the reference point of the functional region 12 is not necessarily the center of the surface direction of the area that displays the optical function of the functional region 12.

[0127] Furthermore, in this invention, the functional region 12 may have multiple points that can serve as reference points. In this case, any one point can be appropriately selected as the reference point in the functional region 12.

[0128] In this invention, the reference point of the functional region 12 can be a point that can be observed with the naked eye or a point that cannot be observed with the naked eye. From the viewpoint of being able to properly obtain the effect of the invention that allows the position of the reference point of the functional region 12 to be determined, it is preferable to use an optical sheet 10 having a functional region 12 having a reference point that cannot be observed with the naked eye.

[0129] In addition, in this invention, "cannot be observed with the naked eye" means that if operations different from the usual observation state are not performed, such as the use of optical elements such as polarizers and filters, and the irradiation with special light such as ultraviolet light and specific polarized light, then a person cannot visually identify it. That is, in the usual living environment, a person cannot visually identify it using the visual recognition ability that a person has.

[0130] The support 30 supports the orientation film 32 and the layer having the functional regions 12 (e.g., in...). Figure 6 The example shown is a support for the liquid crystal layer 36. As long as the support 30 can support the alignment film 32 and the layer with the functional region 12, various sheet-like materials (thin films, plates) can be used.

[0131] The transmittance of the support 30 relative to the wavelength of light acting on the functional region 12 is preferably 50% or more, more preferably 70% or more, and even more preferably 85% or more.

[0132] The thickness of the support 30 is not limited, as long as it is appropriately set according to the application of the optical sheet 10 and the forming material of the support 30 to maintain the thickness of the alignment film 32 and the layer having the functional region 12. The thickness of the support 30 is preferably 1 to 1000 μm, more preferably 3 to 250 μm, and even more preferably 5 to 150 μm.

[0133] The support 30 can be a single layer or multiple layers. Examples of a single-layer support 30 include supports made of glass, silicon, triacetyl cellulose (TAC), polyethylene terephthalate (PET), polycarbonate, polyvinyl chloride, acrylic acid, and polyolefins. Examples of a multi-layer support 30 include supports comprising any one of the aforementioned single-layer supports as a substrate, with other support layers disposed on the surface of this substrate.

[0134] The alignment film 32 is an alignment film used to align the liquid crystal compound into a predetermined liquid crystal alignment pattern when forming the functional region 12.

[0135] In the aforementioned example, the functional region 12 has a liquid crystal alignment pattern that changes as the orientation of the optical axis of the liquid crystal compound rotates continuously in one in-plane direction. Therefore, the alignment film 32 is formed such that the liquid crystal compounds 40 in the functional region 12 are arranged in this liquid crystal alignment pattern.

[0136] The alignment film 32 can utilize various known alignment films. Examples include a triboelectric film composed of organic compounds such as polymers, an inclined vapor-deposited film of inorganic compounds, a film with microgrooves, and a film formed by stacking LB (Langmuir-Blodgett) films based on the Langmuir-Blodgett process of organic compounds such as ω-trisanoic acid, dioctadecylmethylammonium chloride, and methyl stearate.

[0137] The alignment film 32 based on friction treatment can be formed by repeatedly rubbing the surface of the polymer layer with paper or cloth in a predetermined direction. Preferably, the materials used in the alignment film 32 are polyimide, polyvinyl alcohol, polymers with polymerizable groups as described in Japanese Patent Application Publication No. 9-152509, and materials used in the formation of alignment films as described in Japanese Patent Application Publication Nos. 2005-097377, 2005-099228, and 2005-128503.

[0138] The alignment film 32 is preferably a so-called photoalignment film formed by irradiating polarized or unpolarized light onto a material with photoalignability. That is, as the alignment film 32, a photoalignment film formed by coating a photoalignment material onto a substrate is preferred. Polarized light can irradiate the photoalignment film from a vertical or oblique direction, while unpolarized light can irradiate the photoalignment film from an oblique direction.

[0139] Examples of photoalignment materials that can be used in the alignment film 32 of the present invention include, for example, Japanese Patent Application Publication Nos. 2006-285197, 2007-076839, 2007-138138, 2007-094071, 2007-121721, 2007-140465, and 2007-1 Azo compounds described in Japanese Patent Publication No. 56439, Japanese Patent Application Publication No. 2007-133184, Japanese Patent Application Publication No. 2009-109831, Japanese Patent Publication No. 3883848 and Japanese Patent Publication No. 4151746, aromatic ester compounds described in Japanese Patent Application Publication No. 2002-229039, and Japanese Patent Application Publication No. 2002-265541 and Japanese Patent Application Publication No. 2002-317013. The described maleimide and / or alkenyl-substituted nadicimide compounds having photooriented units, the photocrosslinkable silane derivatives described in Japanese Patent Nos. 4205195 and 4205198, the photocrosslinkable polyimides, photocrosslinkable polyamides and photocrosslinkable polyimides described in Japanese Patent Nos. 2003-520878, 2004-529220 and 4162850, are all examples of such compounds. Esters and photodimerizable compounds, particularly cinnamic acid ester compounds, chalcone compounds, and coumarin compounds, as described in Japanese Patent Application Publication Nos. 9-118717, 10-506420, 2003-505561, International Publication No. 2010 / 150748, 2013-177561, and 2014-012823, are preferred examples. Among these, azo compounds, photocrosslinkable polyimides, photocrosslinkable polyamides, photocrosslinkable polyesters, cinnamic acid ester compounds, and chalcone compounds are preferred.

[0140] The thickness of the alignment film 32 is not limited, as long as the thickness is appropriately set according to the forming material of the alignment film 32 to obtain the required alignment function. The thickness of the alignment film 32 is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm.

[0141] There are no limitations on the method for forming the alignment film, and various known methods corresponding to the materials used to form the alignment film can be employed. As an example, a method can be illustrated by coating the alignment film onto the surface of a support, allowing it to dry, and then exposing the alignment film with a laser beam to form an alignment pattern. The method for forming the alignment film will be described in detail later.

[0142] Furthermore, in this invention, the formation location of the alignment mark is not limited to the layer having the functional region 12. For example, the alignment mark can be formed on the support 30 or the alignment film 32.

[0143] There are no limitations on the method for forming the alignment mark, and various known methods can be exemplified as long as they can be detected later. Examples include drawing using inks, processing using laser beams, and engraving using a pressing and shaping mold. Preferably, the alignment mark is formed by performing the exposure method described later.

[0144] Alignment marks may be visible to the naked eye or not.

[0145] Next, the exposure method for manufacturing the optical film of the present invention will be described.

[0146] The first aspect of the exposure method of the present invention is a method for interferometric exposure of a photosensitive layer, wherein, The photosensitive layer is exposed through a mask to form a pattern on the photosensitive layer that creates functional areas for displaying optical functions. Two light beams are respectively passed through a through hole in the shielding part of the mask to form alignment marks in the area of ​​the photosensitive layer exposed by only one light beam and the area exposed by only the other light beam.

[0147] As the first exposure method, Figure 1 , Figures 3-7 The following description uses an example of exposing an alignment film 32 for forming a liquid crystal layer having functional regions 12 that function as liquid crystal lenses. That is, in the examples described below, the alignment film 32 is the photosensitive layer of the present invention.

[0148] Figure 8 The image shows, conceptually, an example of an exposure apparatus for implementing an exposure method for forming a radial liquid crystal alignment pattern.

[0149] Figure 8 The exposure apparatus 80 shown includes: a light source 84 on which a laser 82 is provided; a polarization beam splitter 86 that splits the laser beam M from the laser 82 into an S-polarized beam MS and a P-polarized beam MP; a reflector 90A disposed in the optical path of the P-polarized beam MP and a reflector 90B disposed in the optical path of the S-polarized beam MS; a lens 92 disposed in the optical path of the S-polarized beam MS; the polarization beam splitter 94; and a λ / 4 plate 96.

[0150] If a support 30 is provided with an alignment film (photoalignment film) 32 coated before exposure, and a laser beam M is irradiated from a laser 82, the laser beam M is split into a P-polarized light MP and an S-polarized light MS by a polarization beam splitter 86, and the P-polarized light MP and the S-polarized light MS travel in different directions.

[0151] The P-polarized light MP, split by polarization beam splitter 86, is reflected by mirror 90A and incident on polarization beam splitter 94. On the other hand, the S-polarized light MS, split by polarization beam splitter 86, is reflected by mirror 90B, focused by lens 92, and incident on polarization beam splitter 94.

[0152] P-polarized light MP and S-polarized light MS are combined by polarization beam splitter 94, and then pass through λ / 4 plate 96 to become right-handed and left-handed circularly polarized light corresponding to their polarization directions, which are then incident on alignment film 32 on support 30. At this time, P-polarized light MP is reflected by mirror 90A and directly incident on polarization beam splitter 94, so the circularly polarized light converted from P-polarized light MP illuminates alignment film 32 as a plane wave. On the other hand, S-polarized light MS is reflected by mirror 90A, focused by lens 92, and then incident on polarization beam splitter 94, so the circularly polarized light converted from S-polarized light MS illuminates alignment film 32 as a spherical wave.

[0153] When plane waves and spherical waves illuminate the alignment film 32, the polarization state of the light illuminating the alignment film 32 changes periodically in the form of interference fringes due to the interference of right-handed and left-handed circularly polarized light. Since the cross angle between the left-handed and right-handed circularly polarized light changes from the inside to the outside of the concentric circles, an alignment pattern in which the alignment state changes from the inside to the outside can be obtained. Thus, a concentric (radial) alignment pattern in which the alignment state changes periodically can be obtained in the alignment film 32. That is, in this example, the two beams are a plane wave and a spherical wave.

[0154] In this exposure apparatus 80, one cycle Λ of the liquid crystal alignment pattern, in which the optical axis of the liquid crystal compound 40 rotates continuously by 180° in one direction, can be controlled by changing the refractive power (F-number of lens 92), the focal length of lens 92, and the distance between lens 92 and alignment film 24. Furthermore, by adjusting the refractive power (F-number of lens 92), the length Λ of one cycle of the liquid crystal alignment pattern can be changed in one direction of continuous rotation of the optical axis.

[0155] Specifically, by adjusting the diffusion angle of the light diffused through lens 92 and interfering with parallel light, the length Λ of one cycle of the liquid crystal alignment pattern can be changed in one direction of continuous rotation of the optical axis. More specifically, if the refractive power of lens 92 is reduced, the light becomes closer to parallel, and therefore the length Λ of one cycle of the liquid crystal alignment pattern gradually shortens from the inside to the outside, and the F-value increases. Conversely, if the refractive power of lens 92 is increased, the length Λ of one cycle of the liquid crystal alignment pattern shortens sharply from the inside to the outside, and the F-value decreases.

[0156] By forming a liquid crystal layer 36 on an alignment film 32 with an alignment pattern that changes periodically in this orientation state, a functional region 12 with a liquid crystal alignment pattern that rotates continuously in one direction along an optical axis 40A derived from the liquid crystal compound 40 can be formed.

[0157] The alignment film 32, having an alignment pattern, has an alignment pattern that aligns the liquid crystal compound, such that the orientation of the optical axis 40A of the liquid crystal compound 40 in the liquid crystal layer 36 formed on the alignment film 32 changes while continuously rotating in at least one in-plane direction. If the axis of the alignment film 32 along the orientation of the liquid crystal compound is defined as the alignment axis, then it can be said that the alignment film 32 has an alignment pattern in which the orientation of the alignment axis changes while continuously rotating in at least one in-plane direction. The alignment axis of the alignment film 32 can be detected by measuring absorption anisotropy. For example, when linearly polarized light is irradiated onto the alignment film 32 while rotating, and the amount of light transmitted through the alignment film 32 is measured, it can be observed that the light amount gradually changes in one in-plane direction, with the orientation being at its maximum or minimum.

[0158] Here, in the exposure method of the present invention, exposure is performed through a mask 98 used to delineate the region for interference exposure of the alignment film 32. Therefore, Figure 8 The exposure apparatus 80 shown has a mask 98 between the λ / 4 plate 96 and the alignment film 32. Furthermore, in addition to the opening defining the area for interference exposure, the mask 98 also has through holes in the shielding portion, forming areas for transmission through holes where only plane waves are exposed and areas where only spherical waves are exposed. Utilizing... Figure 9 and Figure 10 This point needs clarification.

[0159] Figure 9 This is a conceptual diagram illustrating an example of the exposure method of the present invention, and is an enlarged representation. Figure 8 The diagram shows the mask 98, the support 30, and the orientation film 32. Figure 10 It is a conceptual illustration for implementation. Figure 9 A top view of an example mask used in the exposure method shown. That is, Figure 10 Viewed from above Figure 9 The diagram shows mask 98.

[0160] like Figure 9 and Figure 10 As shown, the mask 98 has an opening 98a for defining the area for interference exposure of the alignment film 32 and a through hole 98b formed around the opening 98a. In the example shown, the planar shape of the opening 98a is approximately circular. Furthermore, the planar shape of the through hole 98b is approximately circular. The size of the through hole 98b is sufficiently small compared to the size of the opening 98a.

[0161] Furthermore, in Figure 9 In the diagram, a spherical wave exposed to the alignment film is conceptually represented by a single-dash line, and a plane wave is conceptually represented by a double-dash line. Furthermore, the direction of travel of the spherical wave is indicated by a single-dash arrow, and the direction of travel of the plane wave is indicated by a double-dash arrow. Additionally, in... Figure 9 For simplicity, the diagram shows the shielding portion of the transmission mask 98 as a single-dotted line representing a spherical wave and a double-dotted line representing a plane wave. However, in reality, both plane and spherical waves are only shielded by the opening 98a and the through hole 98b of the transmission mask 98.

[0162] like Figure 9 As shown, when interferometric exposure is performed on the alignment film 32 using plane waves and spherical waves, the interferometric exposure is performed through the opening 98a of the mask 98. Therefore, a portion 32a of the alignment film 32 corresponding to the opening 98a is interferometrically exposed. As described above, an alignment pattern is formed in the interferometrically exposed region 32a to align the liquid crystal compounds in the liquid crystal layer 36 into a radial alignment pattern. Therefore, the size and shape of the opening 98a are approximately the same as the size and shape of the functional region to be fabricated.

[0163] And, as Figure 9 As shown, a through-hole 98b, different from the opening 98a, is provided on the shielding portion of the mask 98. Therefore, plane waves and spherical waves transmitted through the through-hole 98b expose the alignment film 32. At this time, as indicated by the double-dotted arrow, the plane wave transmits approximately perpendicularly through the through-hole 98b; therefore, when viewed from a direction perpendicular to the main surface of the alignment film 32, the region 32b of the alignment film 32 corresponding to the through-hole 98b is exposed. Furthermore, the spherical wave directed towards this region 32b is shielded by the shielding portion of the mask 98, so this region 32b is not exposed by the spherical wave. That is, region 32b becomes the region exposed only by a plane wave (one beam).

[0164] On the other hand, as indicated by the dashed arrow, the spherical wave is transmitted through the through-hole 98b in an inclined direction. Therefore, when viewed from a direction perpendicular to the main surface of the alignment film 32, region 32c of the alignment film 32, which is further outward (farther than region 32a) than region 32b corresponding to the through-hole 98b, is exposed. Furthermore, the plane wave directed towards region 32c is blocked by the shielding portion of the mask 98, so region 32c is not exposed by the plane wave. That is, region 32c becomes the region exposed only by the spherical wave (another beam).

[0165] Furthermore, in this invention, the area exposed only by a plane wave (one beam) refers to the area exposed by light in which the ratio of the light intensity of the plane wave (one beam) to the total light intensity of the plane wave (one beam) and the spherical wave (another beam) is 90% or more. Similarly, the area exposed only by a spherical wave (another beam) refers to the area exposed by light in which the ratio of the light intensity of the spherical wave (another beam) to the total light intensity of the plane wave (one beam) and the spherical wave (another beam) is 90% or more.

[0166] Furthermore, if the ratio of spherical waves to plane waves changes, the interfering light becomes elliptically polarized on the exposure surface. Exposure with elliptically polarized light generates an orientation-limiting force along the major axis. Moreover, the closer the ratio of the major and minor axes of elliptically polarized light is to 1 (closer to circularly polarized light), the more difficult it is to align. Since alignment is difficult with elliptically polarized light exposure, an increased exposure time or amount of light, i.e., exposure energy, is required to increase the orientation-limiting force. Therefore, an energy difference for orientation is generated between the area exposed with elliptically polarized light and the functional area. Thus, the area serving as an alignment mark and the functional area can be formed using this energy difference for orientation. That is, by adjusting the exposure time and energy, the functional area is oriented, while the area serving as the alignment mark is in an under-oriented state, thereby forming the area serving as the alignment mark.

[0167] exist Figure 8 In the exposure apparatus 80 shown, if the λ / 4 plate 96 is arranged only in relation to the opening 98a, the plane wave and spherical wave transmitted through the through-hole 98b remain orthogonally linearly polarized light. Therefore, regions 32b and 32c are exposed with linearly polarized light and thus have an orientation-limiting force in one direction. Since the linearly polarized light exposing region 32b is orthogonal to the linearly polarized light exposing region 32c, the direction of the orientation-limiting force in region 32b is orthogonal to the direction of the orientation-limiting force in region 32c.

[0168] Furthermore, the regions of the alignment film 32 other than the region 32a exposed by interference, the region 32b exposed only by plane wave, and the region 32c exposed only by spherical wave are shielded by the shielding portion of the mask 98 and are not exposed.

[0169] By forming a liquid crystal layer on the alignment film 32 exposed in this way, the liquid crystal compound in the liquid crystal layer 36 of the interference-exposed region 32a is aligned according to the alignment pattern formed in region 32a, becoming a functional region 12 with a radial liquid crystal alignment pattern and a lens function. Furthermore, in the liquid crystal layer 36 of region 32b exposed only with a plane wave, the liquid crystal compound is uniaxially aligned according to the direction of the alignment restraint force of region 32b, becoming an alignment mark. Similarly, in the liquid crystal layer 36 of region 32c exposed only with a spherical wave, the liquid crystal compound is uniaxially aligned according to the direction of the alignment restraint force of region 32c, becoming another alignment mark. And, in the unexposed regions, the liquid crystal compound in the liquid crystal layer 36 is unaligned, becoming an unaligned region 14.

[0170] That is, in the exposure method of this embodiment, by providing a through hole 98b on the mask 98 for interference exposure, two alignment marks that are set as a group can be set. At this time, the orientation directions of the liquid crystal compounds in the two alignment marks that are set as a group are approximately orthogonal. Furthermore, the size and shape of the through hole 98b of the mask 98 are approximately the same as the size and shape of the alignment mark to be produced.

[0171] Furthermore, the reference point P0 for the physical characteristics of functional region 12 is formed at the intersection of the central axis of the spherical wave and the alignment film 32. Two alignment marks are formed through a through-hole 98b in region 32b exposed only by plane waves and region 32c exposed only by spherical waves. The position of the alignment mark formed in region 32c exposed by spherical waves is determined based on the diffusion angle of the spherical wave, etc. Therefore, the reference point P0 for the physical characteristics of functional region 12 and the two alignment marks exist on a straight line. Therefore, by detecting the two alignment marks, the reference point P0 for the physical characteristics of functional region 12 can be accurately detected.

[0172] In addition, Figure 9 and Figure 10 In the example shown, mask 98 is configured with a single through hole 98b, but it is not limited to this, such as... Figure 11 As shown, the mask 98 can also be configured with two through holes 98b. If such a mask 98 is used for the above-mentioned interference exposure, two regions 32b exposed only by plane waves and two regions 32c exposed only by spherical waves are formed on the alignment film 32, corresponding to the two through holes 98b, respectively.

[0173] By forming a liquid crystal layer on the alignment film 32 exposed in this way, functional region 12 on region 32a exposed by interference, two alignment marks forming a group on region 32b and region 32c, and another group of two alignment marks forming a group on region 32b and region 32c. That is, two groups of two alignment marks can be formed.

[0174] Furthermore, in Figure 9 and Figure 10 In the example shown, the plane wave and spherical wave passing through the through-hole 98b are linearly polarized light, but this is not a limitation; the plane wave and spherical wave passing through the through-hole 98b can also be circularly polarized light. That is, Figure 8 The λ / 4 plate 96 in the middle can also be configured to correspond to the through hole 98b.

[0175] In this case, for example, the alignment film 32 is exposed to linearly polarized light in any direction beforehand, and then the above-described exposure method is performed. As a result, the region 32a exposed by interference can have the same alignment pattern as described above, and the region 32b exposed only by plane wave and the region 32c exposed only by spherical wave are exposed with circularly polarized light, thus eliminating the previous state of exposure with linearly polarized light.

[0176] Then, if a liquid crystal layer is formed on the alignment film 32, the liquid crystal compound is uniaxially aligned in the liquid crystal layer on the unaligned region 14, a functional region 12 with the same liquid crystal alignment pattern as described above is formed on the liquid crystal layer on region 32a, and alignment marks in an unaligned state are formed on regions 32b and 32c. That is, in this case, the alignment state is different in the two alignment marks and the surrounding unaligned regions 14, so the two alignment marks can be easily detected.

[0177] Furthermore, in Figure 9 In the example shown, plane waves and spherical waves are used for interferometric exposure, but it is not limited to this. Two spherical waves with different diffusion angles can also be used for interferometric exposure.

[0178] The second aspect of the exposure method of the present invention is a method of interferometric exposure of the photosensitive layer, wherein, The photosensitive layer is exposed to form a pattern on the photosensitive layer for creating functional areas that display optical functions. By setting a shielding part in the optical path of two beams to block a portion, alignment marks are formed in the area of ​​the photosensitive layer where the pattern is formed, in the area exposed by only one beam and in the area exposed by only the other beam.

[0179] As a second exposure method, for Figure 2 The following describes the exposure of an alignment film 32, which has a functional region 12 that functions as a liquid crystal lens and is used to form a liquid crystal layer with two alignment marks within the functional region 12.

[0180] Furthermore, the exposure apparatus for implementing the second exposure method is identical to the exposure apparatus for implementing the first exposure method, except for the mask structure. Therefore, the following description mainly focuses on the different parts. And, in the following description... Figure 12 In the example shown, with Figure 9 Similarly, in the example shown, the two beams are a plane wave and a spherical wave, but they could also be two spherical waves with different spread angles.

[0181] Figure 12 This is a conceptual diagram illustrating another example of the exposure method of the present invention, and is an enlarged representation. Figure 8 The diagram shows the mask 98, the support 30, and the orientation film 32. Figure 13 It is a conceptual illustration for implementation. Figure 12 A top view of an example mask used in the exposure method shown. That is, Figure 13 Viewed from above Figure 12 The diagram shows mask 98.

[0182] In addition, Figure 12 In the diagram, the single-dash line representing spherical waves and the double-dash line representing plane waves are omitted. The direction of travel of spherical waves is indicated by arrows with single-dash lines, and the direction of travel of plane waves is indicated by arrows with double-dash lines.

[0183] like Figure 12 and Figure 13 As shown, the mask 98 has an opening 98a for defining the area for interference exposure of the alignment film 32 and a shielding portion 98c disposed within the opening 98a. In the example shown, the planar shape of the opening 98a is approximately circular. Furthermore, the planar shape of the shielding portion 98c is also approximately circular. The size of the shielding portion 98c is sufficiently small compared to the size of the opening 98a. Also, in the example shown, the shielding portion 98c is disposed at a position offset from the center of the opening 98a.

[0184] like Figure 12 As shown, when interferometric exposure is performed on the alignment film 32 using plane waves and spherical waves, the interferometric exposure is performed through the opening 98a of the mask 98. Therefore, a portion 32a of the alignment film 32 corresponding to the opening 98a is interferometrically exposed. As described above, an alignment pattern is formed in the interferometrically exposed region 32a to align the liquid crystal compounds in the liquid crystal layer 36 into a radial alignment pattern. Therefore, the size and shape of the opening 98a are approximately the same as the size and shape of the functional region to be fabricated.

[0185] And, as Figure 12As shown, a shielding portion 98c is provided in the opening 98a of the mask 98 to partially shield a portion of the wave. Therefore, a portion of the plane wave and spherical wave passing through the opening 98a are shielded. At this time, regions 32b and 32c are created where the spherical wave (single-dotted arrow) is shielded by the shielding portion 98c and only the plane wave (double-dotted arrow) reaches the mask, and regions 32c and 32b are shielded by the shielding portion 98c and only the spherical wave (single-dotted arrow) reaches the mask. That is, region 32b becomes the region where only the plane wave is exposed, and region 32c becomes the region where only the spherical wave is exposed.

[0186] Both plane waves and spherical waves are circularly polarized light; therefore, regions 32b and 32c are exposed to circularly polarized light. Consequently, no orientation-confining force is generated in regions 32b and 32c.

[0187] Furthermore, the area surrounding the interference-exposed region 32a of the orientation film 32 is shielded by the mask 98 and is not exposed to plane waves or spherical waves.

[0188] By forming a liquid crystal layer on the alignment film 32 exposed in this way, the liquid crystal compound in the liquid crystal layer 36 of the interference-exposed region 32a is aligned according to the alignment pattern formed in region 32a, thus becoming a functional region 12 with a radial liquid crystal alignment pattern and a lens function. Furthermore, in the liquid crystal layer 36 of region 32b exposed only by plane waves, the liquid crystal compound is not aligned and becomes an alignment mark. Similarly, in the liquid crystal layer 36 of region 32c exposed only by spherical waves, the liquid crystal compound is not aligned and becomes another alignment mark. And, in the unexposed regions, the liquid crystal compound in the liquid crystal layer 36 is not aligned and becomes an unaligned region 14.

[0189] That is, in the exposure method of this embodiment, by providing a shielding portion 98c in the opening 98a of the mask 98 for interference exposure, two alignment marks that are set as a group can be set in the functional region 12. At this time, the liquid crystal compound in the two alignment marks that are set as a group is in an unoriented state. Furthermore, the size and shape of the shielding portion 98c are approximately the same as the size and shape of the alignment marks to be produced.

[0190] In addition, Figure 12 and Figure 13 In the example shown, the mask 98 is configured to have one shielding portion 98c in the opening 98a, but it is not limited to this and can also be configured to have two shielding portions 98c in the opening 98a. If such a mask 98 is used for the above-described interference exposure, then corresponding to the two shielding portions 98c, two regions 32b exposed only by plane waves and two regions 32c exposed only by spherical waves are formed on the alignment film 32.

[0191] By forming a liquid crystal layer on the alignment film 32 exposed in this way, functional region 12 on region 32a exposed by interference, two alignment marks forming a group on region 32b and region 32c, and another group of two alignment marks forming a group on region 32b and region 32c. That is, two groups of two alignment marks can be formed.

[0192] In addition, in the above example, the regions of the liquid crystal layer formed on regions 32b and 32c are used as alignment marks, but it is not limited to this. Regions 32b and 32c of the alignment film 32 can also be used as alignment marks.

[0193] Furthermore, in Figure 12 In the example shown, in the structure where interference exposure is performed via mask 98, a shielding portion 98c is provided at the opening 98a of mask 98 to partially shield the area. However, this is not a limitation. In a structure where interference exposure is performed without using mask 98, a shielding portion 98c may also be provided in the optical paths of the two beams. For example, a λ / 4 plate 96 (see reference) may also be placed directly in front of the alignment film 32 to be exposed. Figure 8 A partially shielding part 98c is provided on the top.

[0194] Furthermore, the shielding portion 98c is not limited to a structure with 0% light transmittance; it can also be a shielding portion that attenuates light. For example, in a structure that uses plane waves and spherical waves for interferometric exposure, the shielding portion 98c reduces the light of a beam, thereby creating regions 32b exposed with light containing a large amount of plane wave components and regions 32c exposed with light containing a large amount of spherical wave components on the alignment film 32. The alignment state in these regions can be set to a different orientation state than that of the interferometrically exposed region (the region that becomes the functional region) 32a. Thus, regions that serve as alignment marks can be formed.

[0195] Furthermore, when using products with such... Figure 8When the exposure apparatus 80 of the λ / 4 plate 96 performs interference exposure on the alignment film 32, a region without phase difference can be locally formed within the surface of the λ / 4 plate 96. That is, it can be set as a region that does not convert the incident linearly polarized light into circularly polarized light and allows it to be transmitted. In this case, it is possible to form a region 32a in which two linearly polarized lights (P-polarized light MP and S-polarized light MS) are converted into circularly polarized light by the λ / 4 plate 96 and subjected to interference exposure, a region in which one linearly polarized light converted into circularly polarized light by the λ / 4 plate 96 and another linearly polarized light transmitted through a region without phase difference of the λ / 4 plate 96 is subjected to interference exposure, and a region in which another linearly polarized light converted into circularly polarized light by the λ / 4 plate 96 and another linearly polarized light transmitted through a region without phase difference of the λ / 4 plate 96 is subjected to interference exposure. Thus, the orientation state of the region subjected to interference exposure with circularly polarized light and linearly polarized light can be set to a different orientation state than the region subjected to interference exposure with two circularly polarized lights (the region that becomes the functional region) 32a, and thus it is possible to form a region that serves as an alignment mark.

[0196] The above describes an example of the exposure method of the present invention for exposing an alignment film used to align a liquid crystal layer, but it is not limited thereto. In the case of a process of interferometric exposure of a photosensitive layer to form a functional region, by appropriately applying the above method, it is possible to form two alignment marks that exist on a straight line with the reference point of the physical characteristics of the functional region.

[0197] For example, in the case of a surface relief diffraction lens in which a diffraction structure with a repeating pattern of alternating concave and convex shapes is formed, if interference fringes are formed on a resist layer (photosensitive layer) formed using photoresist material by exposing spherical waves and plane waves in a concentric or elliptical overlapping shape in the same manner as in the above example, the resist layer in the strong part will solidify, while the resist layer in the weak part will not solidify. Therefore, by cleaning, it is possible to create a pattern of concave and convex interference fringes on the resist layer.

[0198] In this case, the area that is designated as a functional area is also defined by using a mask, and through holes are provided on the mask. The resist in the area where only the spherical wave is exposed and the area where only the plane wave is exposed is more cured than the unexposed area, so two alignment marks can be formed.

[0199] Alternatively, by setting a shielding portion in the optical path of the two beams (the opening of the mask), regions exposed only by plane waves and regions exposed only by spherical waves can be formed in the functional region (the region exposed with a pattern of interference fringes). In this case, by setting the curing intensity of the resist to a level where only the intensity of plane waves or spherical waves will not cure, regions without interference fringes can be formed within the functional region and used as alignment marks.

[0200] When a shielding portion is provided at the opening of the mask, an intensity difference can be created between the plane wave and the spherical wave. As a result, the area exposed with the stronger intensity will cure, while the area exposed with the weaker intensity will not cure easily, thus making it possible to distinguish the positive and negative of the two alignment marks.

[0201] Furthermore, when forming a region without interference fringes within a functional area and using it as an alignment mark, the size of the alignment mark is preferably larger than the spacing of the interference fringes, preferably more than twice.

[0202] Furthermore, in the examples above, it is assumed that one functional region (the area for forming the functional region) and one or two sets of alignment marks (the areas for forming the alignment marks) are formed on one photosensitive layer (alignment film, resist layer), but it is not limited to this. Multiple functional regions (the areas for forming the functional regions) and alignment marks (the areas for forming the alignment marks) corresponding to each functional region can be formed on one grown photosensitive layer.

[0203] For example, when forming a liquid crystal layer on an alignment film, a long alignment film (and support) is prepared. By changing the position on the alignment film while performing the above-described exposure method, it is possible to form a combination of alignment films, including an interference-exposed region 32a (a region for forming functional regions), a region exposed only with plane waves 32b, and a region exposed only with spherical waves 32c (a region for forming alignment marks corresponding to each functional region). By forming a liquid crystal layer on this alignment film, it is possible to form a liquid crystal layer having multiple functional regions and alignment marks corresponding to each functional region.

[0204] Thus, when a liquid crystal layer with multiple functional regions is fabricated, it is cut to a size containing one functional region and a corresponding alignment mark for use. In this case, the optical sheet of the present invention has two alignment marks forming a set. A reference point for the physical characteristics of the functional regions exists on a straight line passing through the two alignment marks. Therefore, by detecting the two alignment marks, the reference point for the physical characteristics existing on the straight line passing through the two alignment marks can be easily detected, and the sheet is cut to a shape having a functional region at the desired position using this reference point as a reference. Furthermore, by cutting based on the reference point for the physical characteristics of each functional region, multiple functional regions can be easily and accurately cut into the same structure.

[0205] Furthermore, as an example, the cut optical sheet 10 is aligned and stacked with an optical element cut in the same assembly shape as when assembled into an optical device. There are no limitations on the optical elements that can be combined with the optical sheet 10 of the present invention, and various known optical elements can be used.

[0206] As an example, other optical elements that can be combined with optical sheets include lenses, polarizers, phase retardation plates, microlens arrays, apertures (apertures), anti-reflective coatings, light diffusion coatings, prisms, isolators, etc.

[0207] Therefore, in order to combine the optical sheet of the present invention with other optical elements to achieve the desired function, alignment is usually required when stacking with other optical elements to make the positional relationship of the optical sheet and the optical elements in the planar direction appropriate. In contrast, the optical sheet of the present invention has two alignment marks that form a set. A reference point for the physical characteristics of the functional area exists on the straight line passing through the two alignment marks. Therefore, by detecting the two alignment marks, the reference point for the physical characteristics existing on the straight line passing through the two alignment marks can be easily detected, and alignment with other optical elements can be easily and accurately performed with reference to this reference point.

[0208] The optical film and exposure method of the present invention have been described above, but the present invention is not limited thereto. Various improvements and modifications can be made without departing from the spirit of the present invention.

[0209] Symbol Explanation 10, 10b, 10c, 10d - Optical sheet; 12 - Functional region; 14 - Unoriented region; 30 - Support; 32 - Orientation film; 32a - Region exposed by interference; 32b - Region exposed only by plane wave; 32c - Region exposed only by spherical wave; 36 - Liquid crystal layer; 40 - Liquid crystal compound; 40A - Optical axis; 80 - Exposure device; 82 - Laser; 84 - Light source; 86, 94 - Polarizing beam splitter; 90A, 90B - Mirror; 92 - Lens; 96 - λ / 4 plate; 98 - Mask; 98a - Opening; 98b - Through hole; 98c - Shielding part; P0 - Reference point; P x - Geometric center, P1~P8 - Alignment marks, L1~L4 - Straight lines, R - Region, Λ - 1 cycle, M - Laser beam, MP - P-polarized light, MS - S-polarized light.

Claims

1. An optical sheet having a functional area for displaying optical functions and two alignment marks, wherein, The functional area has a physical reference point. When viewed from a direction perpendicular to the main surface of the optical sheet, there is another alignment mark between one of the two alignment marks and the reference point. The reference point exists on the straight line passing through the two alignment marks.

2. The optical sheet according to claim 1, wherein, The two alignment marks are located outside the functional area.

3. The optical sheet according to claim 1, wherein, The two alignment marks are present within the functional area.

4. The optical plate according to any one of claims 1 to 3, having two sets of the two alignment marks, A straight line passing through one set of the two alignment marks intersects with a straight line passing through another set of the two alignment marks. The reference point exists at the location where the two lines intersect.

5. The optical sheet according to any one of claims 1 to 3, wherein, The geometric center of the functional area is offset from the reference point.

6. The optical sheet according to any one of claims 1 to 3, comprising: The liquid crystal layer is formed using a liquid crystal composition containing a liquid crystal compound. The functional area and the two alignment marks are formed in the liquid crystal layer. The liquid crystal compound is oriented in the functional region.

7. The optical sheet according to claim 6, wherein, The orientations of the liquid crystal compounds within the two alignment marks are different.

8. An exposure method, which is a method of interferometric exposure of a photosensitive layer, wherein, The photosensitive layer is exposed through a mask to form a pattern on the photosensitive layer for creating functional areas that display optical functions. Two light beams are respectively passed through a through hole provided in the shielding part of the mask to form alignment marks in the area of ​​the photosensitive layer exposed by only one light beam and the area exposed by only the other light beam.

9. The exposure method according to claim 8, wherein, It has two through holes, forming two sets of two alignment marks.

10. An exposure method, which is a method of interferometric exposure of a photosensitive layer, wherein, The photosensitive layer is exposed to form a pattern on the photosensitive layer for creating functional areas that display optical functions. By setting a shielding part in the optical path of two beams to block a portion, alignment marks are formed in the area of ​​the photosensitive layer where the pattern is formed, in the area exposed by only one beam and in the area exposed by only the other beam.

11. The exposure method according to claim 10, wherein, It has two of the aforementioned shielding portions, forming two sets of two of the aforementioned alignment marks.

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