Manufacturing method of hologram substrate, hologram substrate, manufacturing method of replica hologram substrate and manufacturing method of laminated hologram element

Abstract

To provide a manufacturing method of a hologram substrate and the like capable of easily and accurately reading an alignment mark provided at a hologram substrate.SOLUTION: A manufacturing method of hologram substrate 100 includes a hologram layer 20, and a plurality of alignment marks 31, 32 provided at the outside of the hologram layer. The manufacturing method includes: a hologram layer forming step ST2 of forming a hologram layer by radiating light L1, L2 with respect to a photo sensitive material 10 from two directions different from each other where at least one direction is not a normal direction of the photo sensitive material and allowing them to interfere; and an alignment mark forming step ST3 of forming an alignment mark comprising a hologram, by radiating light L1, L3 from one side and the other side of the normal direction of the photo sensitive material, with respect to the outside of a region where the hologram layer is formed in the photo sensitive material, and allowing them to interfere.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a hologram substrate, a method for manufacturing a hologram substrate, a replica hologram substrate, and a method for manufacturing a laminated hologram element. In particular, the present invention relates to a method for manufacturing a hologram substrate, a method for manufacturing a hologram substrate, a replica hologram substrate, and a method for manufacturing a laminated hologram element, which enable alignment marks provided on each hologram substrate to be easily and accurately read and each hologram substrate to be easily and accurately aligned when manufacturing a laminated hologram element by stacking multiple hologram substrates (including replica hologram substrates). [Background technology]

[0002] Conventionally, a method has been proposed for manufacturing a laminated hologram element by laminating a red hologram layer, a green hologram layer, and a blue hologram layer (see, for example, Patent Document 1). For example, when this laminated hologram element is used as a light guide plate, if the positions of each hologram layer are misaligned, a misalignment will occur in the light guide directions of red wavelength light, green wavelength light, and blue wavelength light, resulting in problems such as reduced color reproducibility.

[0003] For this reason, the manufacturing method described in Patent Document 1 proposes providing alignment marks for positioning outside each hologram layer (in Patent Document 1, these are called interference fringe formation regions). The alignment marks described in Patent Document 1 have the same interference fringes as the hologram layers (for example, paragraph 0097 of Patent Document 1). For this reason, when reading the alignment marks, it is necessary to apply illumination light to the end faces of the substrates (in Patent Document 1, light guide plate 121 and support 124) that support each hologram layer, and to detect and image the diffracted light (reflected diffracted light) generated by the alignment marks using an imaging means (for example, paragraph 0097 of Patent Document 1). In order to accurately read an alignment mark (to suppress distortion in the captured image of the alignment mark), and to image the alignment mark from its normal direction (the normal direction of the hologram layer) (so that the direction of the diffracted light generated by the alignment mark is normal to the alignment mark), the angle of incidence of the illumination light on the substrate must satisfy a specific condition (Bragg condition) that corresponds to the interference fringes of the alignment mark (in other words, the interference fringes of the hologram layer) (see, for example, paragraph 0093 of Patent Document 1). Therefore, if the angle of incidence of the illumination light on the substrate deviates from this condition, the direction of the diffracted light generated by the alignment mark will deviate from the normal direction of the alignment mark, resulting in a problem of reduced accuracy in reading the alignment mark. However, satisfying this condition imposes many constraints on the position and angle of incidence of the illumination light, the shape of the substrate onto which the illumination light is incident, and so on. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-175967 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the problems of the conventional technology as described above, and has an object to provide a method for manufacturing a hologram substrate, a method for manufacturing a hologram substrate, a method for manufacturing a replica hologram substrate, and a method for manufacturing a laminated hologram element, which enable alignment marks provided on each hologram substrate to be easily and accurately read when manufacturing a laminated hologram element by stacking multiple hologram substrates, and which enable each hologram substrate to be easily and accurately aligned. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a hologram substrate comprising a hologram layer and a plurality of alignment marks provided outside the hologram layer, the method comprising: a hologram layer forming step of forming the hologram layer by irradiating a photosensitive material with light from two different directions, at least one of which is not the normal direction of the photosensitive material, and causing interference, and an alignment mark forming step of forming the alignment mark consisting of a hologram by irradiating a region of the photosensitive material outside the region where the hologram layer is formed with light from one side and the other side of the normal direction of the photosensitive material, and causing interference.

[0007] According to the method for manufacturing a hologram substrate of the present invention, in the hologram layer formation step, a hologram layer is formed by irradiating a photosensitive material with light from two different directions (at least one of which is not the normal direction of the photosensitive material) and causing interference. Meanwhile, in the alignment mark formation step, an alignment mark made of a hologram is formed by irradiating an area outside the photosensitive material where the hologram layer is to be formed with light from one side and the other side of the normal direction of the photosensitive material (i.e., irradiating with light in the same normal direction but in opposite directions) and causing interference. That is, because the direction of light used when forming the hologram layer is different from that used when forming the alignment mark, the interference fringes that form the hologram layer and the interference fringes that form the alignment mark are not the same, but different, as in Patent Document 1. Since alignment marks are formed by irradiating light from one side and the other side of the normal direction of a photosensitive material and causing interference, for example, if illumination light is irradiated onto an alignment mark provided on a hologram substrate from one side in the normal direction of the hologram substrate, diffracted light (reflected diffracted light) generated by the alignment mark will travel in one side in the normal direction of the hologram substrate. Therefore, by placing an imaging means on one side in the normal direction of the hologram substrate and using this imaging means to detect and image the diffracted light generated by the alignment mark from one side in the normal direction of the hologram substrate, it is possible to easily and accurately read the alignment marks provided on the hologram substrate. Therefore, multiple hologram substrates can be aligned easily and accurately. Furthermore, even if, when reading an alignment mark, illumination light is simultaneously irradiated onto both the alignment mark and the hologram layer from one side in the normal direction of the hologram substrate, the diffracted light (reflected diffracted light) generated by the hologram layer, unlike the diffracted light generated by the alignment mark, travels away from one side in the normal direction of the hologram substrate, making it difficult to detect by the imaging means, and it is possible to image only the alignment mark with relatively high contrast.

[0008] In the hologram layer formation process of the present invention, as described above, an alignment mark is formed by interfering light from two different directions. However, as in the alignment mark formation process, if one of the two directions is set to the normal direction of the photosensitive material, it is efficient in that a common light source can be used in both processes. That is, the method for manufacturing a hologram substrate according to the present invention preferably includes a mask arrangement step, prior to the hologram layer formation step and the alignment mark formation step, of arranging a mask on the photosensitive material, the mask having a first opening provided in a position corresponding to the hologram layer and a second opening provided in a position corresponding to the alignment mark, so as to face one side in the normal direction of the photosensitive material, and blocking light at other positions, in which, in the hologram layer formation step, light is irradiated onto the photosensitive material from one side in the normal direction of the photosensitive material through the first opening of the mask, and in the alignment mark formation step, light is irradiated onto the photosensitive material from one side in the normal direction of the photosensitive material through the second opening of the mask.

[0009] According to the above-described preferred method, a common light source that irradiates light from one side in the normal direction of the photosensitive material can be used in both the hologram layer formation process and the alignment mark formation process, thereby enabling both processes to be performed efficiently. Furthermore, by blocking the second opening of the mask in the hologram layer formation process (allowing light to pass only through the first opening), and by blocking the first opening of the mask in the alignment mark formation process (allowing light to pass only through the second opening), a light source that irradiates a large amount of light that spreads over an area including both the first and second openings can be used. Furthermore, since the positional relationship between the hologram layer and the alignment mark formed on the photosensitive material is determined by the positional relationship between the first and second openings in the mask, forming the hologram layer and the alignment mark using the same mask allows for the manufacture of a hologram substrate with little variation in the positional relationship between the two.

[0010] Preferably, in the alignment mark forming process, a reflecting mirror is positioned facing the other side of the photosensitive material in the normal direction of the photosensitive material, and the alignment mark is formed by causing interference between light irradiated onto the photosensitive material from one side of the normal direction of the photosensitive material through the second opening of the mask and light that is reflected by the reflecting mirror and irradiated onto the photosensitive material from the other side of the normal direction of the photosensitive material.

[0011] According to the above-described preferred method, the alignment mark formation process can be carried out efficiently because light irradiated onto the photosensitive material from one side in the normal direction of the photosensitive material can be simply reflected by a reflecting mirror, and the reflected light can be used as light irradiated onto the photosensitive material from the other side in the normal direction of the photosensitive material.

[0012] In a hologram substrate manufactured by carrying out the method for manufacturing a hologram substrate according to the present invention, the direction of diffracted light generated when light is irradiated onto the hologram layer from one side in the normal direction of the hologram layer is not the normal direction of the hologram layer. This is because at least one of the two directions of light used to form the hologram layer is not the normal direction of the photosensitive material. On the other hand, the direction of diffracted light generated when light is irradiated onto an alignment mark from one side in the normal direction of the alignment mark is the normal direction of the alignment mark. This is because the light used to form the alignment mark is light irradiated from one side and the other side in the normal direction of the photosensitive material. Therefore, in order to solve the above problem, the present invention also provides a hologram substrate comprising a hologram layer and a plurality of alignment marks, wherein the alignment marks are formed from holograms, and the direction of diffracted light generated when light is irradiated onto the hologram layer from one side in the normal direction of the hologram layer is not the normal direction of the hologram layer, but the direction of diffracted light generated when light is irradiated onto the alignment marks from one side in the normal direction of the alignment marks is the normal direction of the alignment marks.

[0013] In order to solve the above-mentioned problems, the present invention also provides a method for producing a replica hologram substrate by preparing the hologram substrate as a master hologram substrate and replicating it, the method comprising: a photosensitive material arranging step of arranging a photosensitive material with respect to the master hologram substrate so that the photosensitive material faces one side in a normal direction of the master hologram substrate; and a duplication step of duplicating the hologram layer and the alignment marks of the master hologram substrate in the photosensitive material by causing interference between light irradiated onto the photosensitive material from one side in the normal direction of the photosensitive material and diffracted light generated when the light is irradiated onto the master hologram substrate.

[0014] According to the method for manufacturing a replica hologram substrate of the present invention, a replica hologram substrate can be easily manufactured (a master hologram substrate can be replicated) simply by placing a photosensitive material so that it faces one side of the master hologram substrate in the normal direction and irradiating light onto the photosensitive material from one side of the normal direction of the photosensitive material.

[0015] Furthermore, in order to solve the above-mentioned problems, the present invention provides a method for manufacturing a laminated hologram element by preparing, as the hologram substrate, a red hologram substrate having a red hologram layer that is the hologram layer and red alignment marks that are the alignment marks, which are formed by irradiating with light of a red wavelength, a green hologram substrate having a green hologram layer that is the hologram layer and green alignment marks that are the alignment marks, which are formed by irradiating with light of a green wavelength, and a blue hologram substrate having a blue hologram layer that is the hologram layer and blue alignment marks that are the alignment marks, which are formed by irradiating with light of a blue wavelength, and laminating the red hologram substrate, the green hologram substrate, and the blue hologram substrate, the method comprising: irradiating the red alignment marks of the red hologram substrate with first illumination light having a wavelength that includes a red wavelength from one side in a normal direction of the red hologram substrate; capturing an image of the red alignment marks from one side in the normal direction of the red hologram substrate to obtain a first captured image; an image acquisition step of irradiating the green alignment mark with second illumination light having a wavelength including a green wavelength from one side in the normal direction of the green hologram substrate, and capturing an image of the green alignment mark from one side in the normal direction of the green hologram substrate to acquire a second captured image, and irradiating the blue alignment mark of the blue hologram substrate with third illumination light having a wavelength including a blue wavelength from one side in the normal direction of the blue hologram substrate, and capturing an image of the blue alignment mark from one side in the normal direction of the blue hologram substrate to acquire a third captured image; a coordinate detection step of detecting coordinates of the red alignment marks, the green alignment marks, and the blue alignment marks by image processing the first captured image and the third captured image, respectively; a position adjustment step of adjusting positions of the red hologram substrate, the green hologram substrate, and the blue hologram substrate so that the coordinates of the red alignment marks, the green alignment marks, and the blue alignment marks match; and a bonding step of bonding the red hologram substrate, the green hologram substrate, and the blue hologram substrate after the position adjustment.The present invention also provides a method for manufacturing a laminated hologram element having the above structure.

[0016] In the manufacturing method of the laminated hologram element according to the present invention, "red wavelength" means, for example, a wavelength of 600 to 700 nm, "green wavelength" means, for example, a wavelength of 500 to 560 nm, and "blue wavelength" means, for example, a wavelength of 430 to 500 nm. Furthermore, in the manufacturing method of a laminated hologram element according to the present invention, the "hologram substrate" may be a master hologram substrate manufactured by the manufacturing method of a hologram substrate according to the present invention, or a replica hologram substrate manufactured by the manufacturing method of a replica hologram substrate according to the present invention. According to the manufacturing method of the laminated hologram element of the present invention, in the captured image acquisition step, the red alignment mark is irradiated with first illumination light having a wavelength including a red wavelength from one side in the normal direction of the red hologram substrate, so that diffracted light (reflected diffracted light) generated by the red alignment mark travels toward one side in the normal direction of the red hologram substrate. Therefore, in the first captured image acquired by capturing the red alignment mark from one side in the normal direction of the red hologram substrate, the red alignment mark is captured with relatively high contrast. Similarly, in the second captured image, the green alignment mark is captured with relatively high contrast, and in the third captured image, the blue alignment mark is captured with relatively high contrast. Therefore, in the coordinate detection step, the first captured image, the second captured image, and the third captured image are subjected to image processing, so that the coordinates of the red alignment mark, green alignment mark, and blue alignment mark can be detected with high accuracy. According to the present invention, in the position adjustment process, the positions of the red hologram substrate, green hologram substrate, and blue hologram substrate are adjusted so that the coordinates of the red alignment mark, green alignment mark, and blue alignment mark match, and in the bonding process, the hologram substrates are bonded together after their positions have been adjusted.This makes it possible to manufacture a laminated hologram element in which the red hologram layer, green hologram layer, and blue hologram layer of each hologram substrate are aligned with high precision. [Effects of the Invention]

[0017] According to the present invention, by stacking multiple hologram substrates, when manufacturing a laminated hologram element, it is possible to easily and accurately read the alignment marks provided on each hologram substrate, and to manufacture hologram substrates that can easily and accurately align each hologram substrate. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a flowchart showing the outline of steps in a method for manufacturing a hologram substrate according to an embodiment of the present invention. [Figure 2] 1A to 1C are schematic diagrams illustrating the outline of steps in a method for manufacturing a hologram substrate according to an embodiment of the present invention. [Figure 3] 3 is a schematic diagram illustrating a method for closing a first opening 41 and second openings 42 and 43 of the mask 40 shown in FIG. 2 using an auxiliary mask. [Figure 4] FIG. 1 is a flowchart showing the outline of steps in a method for manufacturing a replica hologram substrate according to an embodiment of the present invention. [Figure 5] 1A to 1C are schematic diagrams illustrating the outline of steps in a method for manufacturing a replica hologram substrate according to an embodiment of the present invention. [Figure 6] 1 is a flow chart showing the outline of steps in a method for manufacturing a laminated hologram element according to an embodiment of the present invention. [Figure 7] FIG. 7 is a schematic diagram illustrating a captured image obtaining step ST32 shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the drawings are for reference purposes only, and the dimensions, scale, and shapes of the components shown in the drawings may differ from the actual ones.

[0020] [Hologram substrate manufacturing method] Fig. 1 is a flow chart showing the outline of the steps of the method for producing a hologram substrate according to this embodiment. Fig. 2 is a schematic diagram illustrating the outline of the steps of the method for producing a hologram substrate according to this embodiment. As shown in FIG. 1, the manufacturing method according to this embodiment includes a mask placement step ST11, a hologram layer formation step ST12, and an alignment mark formation step ST13.

[0021] <Mask placement process ST11> Fig. 2(a) is a plan view showing a schematic configuration of a mask prepared in a mask placement step ST11. In Fig. 2(a), the Z direction indicates the thickness direction (corresponding to the thickness direction of a holographic substrate, which will be described later) that is the normal direction of the mask, the X direction indicates a direction perpendicular to the Z direction and parallel to one side of the holographic substrate, which will be described later, and the Y direction indicates a direction perpendicular to the Z direction and the X direction. This is also true for the other figures. 2(a), the mask 40 prepared in the mask placement step ST11 has a first opening 41 provided at a location corresponding to a hologram layer (described later) and second openings 42 and 43 provided at locations corresponding to a plurality of alignment marks (two in this embodiment) (described later), and blocks light in other locations. The mask 40 is made of, for example, glass or a transparent resin such as polycarbonate, polyamide, or acrylic, and the first opening 41 and the second openings 42 and 43 are formed by, for example, laser processing. The areas of the mask 40 other than the first opening 41 and the second openings 42 and 43 are printed with a color such as black, thereby blocking light. In this embodiment, since the alignment marks described below are rectangular in plan view, the corresponding second openings 42, 43 are also rectangular in plan view. However, the present invention is not limited to this, and if the alignment marks described below are circular in plan view, the corresponding second openings 42, 43 may also be circular in plan view. The second openings 42, 43 may have any shape corresponding to the shape of the alignment marks. The same applies to the first opening 41.

[0022] 2(b) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing the mask placement step ST11. In FIG. 2(b), the mask 40 is shown as a cross-section seen from the arrow AA in FIG. 2(a). In other figures, the cross-section of the mask 40 is also shown as a cross-section seen from the arrow AA. 2(b), in the mask placement step ST11, a mask 40 is placed relative to the photosensitive material 10 so as to face one side (the lower side in the example shown in FIG. 2(b)) in the normal direction (Z direction) of the photosensitive material 10. In this embodiment, the photosensitive material 10 is supported by a light-transmitting plate 50, and the mask 40 is placed below this light-transmitting plate 50. The photosensitive material 10 may be, for example, a photosensitive resin such as a photopolymer or photoresist, or a laminate of a photosensitive resin and a substrate. The photosensitive resin may be, for example, Bayfol (registered trademark) HX200, a photopolymer manufactured by Covestro. The substrate may be, for example, glass or triacetylcellulose (TAC). The light-transmitting plate 50 is not particularly limited as long as it has a refractive index equivalent to that of the photosensitive material 10, and examples thereof include glass, TAC (triacetyl cellulose), and resins such as polycarbonate.

[0023] <Hologram layer forming step ST12> FIG. 2(c) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing the hologram layer forming step ST12. As shown in FIG. 2(c), in the hologram layer forming step ST12, light beams L1 and L2 are irradiated onto the photosensitive material 10 from two different directions (a direction forming an angle α with respect to the XY plane (hereinafter referred to as the “α direction”) and a direction forming an angle β with respect to the XY plane (hereinafter referred to as the “β direction”)) to cause interference, thereby forming the hologram layer 20. As the light beams L1 and L2, coherent light beams such as laser beams are used. In this embodiment, the α direction in which light L1 is irradiated is the normal direction (Z direction) of the photosensitive material 10 (i.e., α = 90°), and the β direction in which light L2 is irradiated is not the normal direction (Z direction) of the photosensitive material 10 (i.e., β ≠ 90°). Then, with the second openings 42 and 43 of the mask 40 closed (a state in which light can pass only through the first opening 41), light L1 is irradiated onto the photosensitive material 10 from one side in the normal direction (Z direction) of the photosensitive material 10 (the bottom side in the example shown in FIG. 2(c)) through the first opening 41 of the mask 40 and the light-transmitting plate 50. As a result, the photosensitive material 10 is irradiated with interference light of light L1 and light L2, and the monomer component in the irradiated portion of the photosensitive material 10 diffuses, generating interference fringes with a refractive index distribution, thereby forming a hologram (volume hologram) layer 20. In order to maintain the coherence of the light L1 and the light L2, it is preferable to split the light emitted from the same laser light source into light L1 and light L2 using a polarizing beam splitter, rotate the polarization axis of the split light L2 using a half-wave plate to match the polarization axis of the light L1, and then magnify and flatten the light using a magnifying lens and a collimating lens, respectively, before irradiating the light from two directions (direction α and direction β). An example of a method for closing the second openings 42 and 43 of the mask 40 will be described later.

[0024] <Alignment mark forming process ST13> FIG. 2(d) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing the alignment mark forming step ST13. As shown in Figure 2(d), in the alignment mark forming process ST13, light L1 is irradiated from one side of the normal direction (Z direction) of the photosensitive material 10 (the bottom side in the example shown in Figure 2(d)) to the outside of the area where the hologram layer 20 is formed in the photosensitive material 10, as in the hologram layer forming process ST12, and light L3 is irradiated from the other side of the normal direction (Z direction) (the top side in the example shown in Figure 2(d)) to cause interference, thereby forming alignment marks 31 and 32 consisting of holograms. In this embodiment, with the first openings 41 of the mask 40 closed (with light only passing through the second openings 42 and 43), light L1 is irradiated onto the photosensitive material 10 from one side (bottom) in the normal direction (Z direction) of the photosensitive material 10 via the second openings 42 and 43 of the mask 40 and the light-transmitting plate 50. Also, in this embodiment, a reflecting mirror 60 is disposed to face the other side (top) in the normal direction (Z direction) of the photosensitive material 10. As a result, light L1 that passes through the second openings 42 and 43 of the mask 40 and is transmitted through the light-transmitting plate 50 and the photosensitive material 10 is reflected by the reflecting mirror 60 to become light L3 that is irradiated onto the photosensitive material 10 from the other side (top) in the normal direction (Z direction) of the photosensitive material 10. As a result, the photosensitive material 10 is irradiated with interference light of the light L1 and the light L3, the monomer component in the irradiated portion of the photosensitive material 10 is diffused, and interference fringes having a refractive index distribution are generated, thereby forming alignment marks 31 and 32 made of holograms (volume holograms). An example of a method for closing the first openings 41 of the mask 40 will be described later.

[0025] A hologram substrate can be manufactured by performing the above-described mask placement step ST11, hologram layer formation step ST12, and alignment mark formation step ST13. Note that, in the present embodiment, an example has been described in which the hologram layer formation step ST12 and then the alignment mark formation step ST13 are performed in that order, but the present invention is not limited to this, and it is also possible to employ a mode in which the alignment mark formation step ST13 is performed first, and then the hologram layer formation step ST12 is performed. FIG. 2(e) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing an example of a hologram substrate manufactured by the manufacturing method according to this embodiment. FIG. 2(f) is a plan view showing an example of a hologram substrate manufactured by the manufacturing method according to this embodiment. The hologram substrate 100 shown in FIGS. 2(e) and 2(f) has a preferred configuration in which substrates 70 are laminated on both sides of a photosensitive material 10 on which a hologram layer 20 and alignment marks 31 and 32 are formed, via an appropriate adhesive or using a self-adhesive photosensitive material 10. Examples of the substrate 70 include glass and resins such as polycarbonate, polyamide, and acrylic. However, the present invention is not limited thereto. The hologram substrate 100 may also have a configuration in which no substrate 70 is laminated (a configuration in which only the photosensitive material 10 on which the hologram layer 20 and alignment marks 31 and 32 are formed) or a configuration in which a substrate 70 is laminated on only one side. 2(e) and 2(f) includes a hologram layer 20 and a plurality of (two in this embodiment) alignment marks 31 and 32, and the alignment marks 31 and 32 are formed from holograms. The direction of diffracted light generated when light is irradiated onto the hologram layer 20 from one side in the normal direction (Z direction) of the hologram layer 20 is not the normal direction (Z direction) of the hologram layer 20. On the other hand, the direction of diffracted light generated when light is irradiated onto the alignment marks 31 and 32 from one side in the normal direction (Z direction) of the alignment marks 31 and 32 is the normal direction (Z direction) of the alignment marks 31 and 32.

[0026] An example of a method for closing second openings 42 and 43 in mask 40 in hologram layer forming step ST12 and an example of a method for closing first openings 41 in mask 40 in alignment mark forming step ST13 will be described below. As a method for closing the first opening 41 and the second openings 42 and 43 of the mask 40, for example, a method using an auxiliary mask is considered. 3A and 3B are schematic diagrams illustrating a method for blocking the first opening 41 and the second openings 42 and 43 of the mask 40 using an auxiliary mask. FIG. 3A is a plan view (similar to FIG. 2A) showing the general configuration of the mask 40. FIG. 3B is a plan view showing the general configuration of the auxiliary mask. FIG. 3C is a plan view showing the second openings 42 and 43 of the mask 40 being blocked using the auxiliary mask in the hologram layer forming step ST12. FIG. 3D is a plan view showing the first opening 41 of the mask 40 being blocked using the auxiliary mask in the alignment mark forming step ST13. 3(b), the auxiliary mask 40A has a first opening 41A and second openings 42A and 43A, and blocks light in other areas, similar to the mask 40. The auxiliary mask 40A is made of a transparent resin, such as glass, polycarbonate, polyamide, or acrylic, similar to the mask 40, and the first opening 41A and second openings 42A and 43A are formed by, for example, laser processing. The areas of the auxiliary mask 40A other than the first opening 41A and second openings 42A and 43A are printed with a color, such as black, to block light.

[0027] 3(a) and 3(b), the first opening 41A and the second openings 42A, 43A of the auxiliary mask 40A have dimensions equal to or larger than the first opening 41 and the second openings 42, 43 of the mask 40, respectively. Preferably, the first opening 41A and the second openings 42A, 43A of the auxiliary mask 40A have dimensions slightly larger than the first opening 41 and the second openings 42, 43 of the mask 40, respectively. The Y-direction separation distance between the first opening 41A and the second openings 42A, 43A of the auxiliary mask 40A is equal to the Y-direction separation distance between the first opening 41 and the second openings 42, 43 of the mask 40. The X-direction separation distance between the second openings 42A and 43A of the auxiliary mask 40A is equal to the X-direction separation distance between the second openings 42 and 43 of the mask 40. However, the positional relationship in the X direction between first opening 41A and second openings 42A and 43A of auxiliary mask 40A is different from the positional relationship in the X direction between first opening 41 and second openings 42 and 43 of mask 40.

[0028] The auxiliary mask 40A having the above configuration is arranged so as to overlap with the mask 40 in the Z direction (for convenience, it is not shown in the above-mentioned FIGS. 2(b) to 2(d)). In the above-mentioned FIGS. 2(b) to 2(d), the auxiliary mask 40A may be arranged above or below the mask 40. FIGS. 3(c) and 3(d) illustrate the case where the auxiliary mask 40A is arranged above the mask 40. The end of the auxiliary mask 40A in the X direction is attached to, for example, a uniaxial stage (not shown) that is movable in the X direction, so that the auxiliary mask 40A can move in the X direction relative to the stationary mask 40.

[0029] In the hologram layer forming step ST12, auxiliary mask 40A is positioned relative to mask 40 as shown in Fig. 3(c) . In the state shown in Fig. 3(c), second openings 42 and 43 of mask 40 are blocked by auxiliary mask 40A, while first opening 41 of mask 40 overlaps with second opening 41A of the auxiliary mask, so that light can pass through only first opening 41. In the alignment mark forming step ST13, the auxiliary mask 40A is positioned relative to the mask 40 as shown in Fig. 3(d). In the state shown in Fig. 3(d), the first opening 41 of the mask 40 is blocked by the auxiliary mask 40A, while the second openings 42 and 43 of the mask 40 overlap with the second openings 42A and 43A of the auxiliary mask, so that light can pass through only the second openings 42 and 43. As described above, by using auxiliary mask 40A and adjusting the position of auxiliary mask 40A, it is possible to close second openings 42 and 43 of mask 40 in hologram layer forming step ST12, and to close first opening 41 of mask 40 in alignment mark forming step ST13. However, the present invention is not limited to this, and various embodiments can be adopted as long as it is possible to close second openings 42 and 43 of mask 40 in hologram layer forming step ST12, and to close first opening 41 of mask 40 in alignment mark forming step ST13.

[0030] [Manufacturing method for replica hologram substrate] When mass-producing the above-mentioned hologram substrate 100, the mask placement step ST11, the hologram layer formation step ST12, and the alignment mark formation step ST13 described with reference to Figures 1 and 2 may be repeated, or it is also possible to use hologram substrate 100 as a master hologram substrate and manufacture (mass-produce) replica hologram substrates by duplicating this. A method for manufacturing such replica hologram substrates will be described below.

[0031] Fig. 4 is a flow chart showing the outline of the steps of the method for producing a replica hologram substrate according to this embodiment. Fig. 5 is a schematic diagram illustrating the outline of the steps of the method for producing a replica hologram substrate according to this embodiment. As shown in FIG. 4, the manufacturing method according to this embodiment includes a preparation step ST21, a photosensitive material placement step ST22, and a duplication step ST23.

[0032] <Preparation process ST21> In preparation step ST21, the above-mentioned hologram substrate 100 is prepared as a master hologram substrate. Specifically, the above-mentioned mask placement step ST11, hologram layer formation step ST12, and alignment mark formation step ST13 are performed to manufacture the master hologram substrate 100.

[0033] <Photosensitive material placement process ST22> FIG. 5(a) is a cross-sectional view (an XZ cross-sectional view perpendicular to the Y direction) showing the photosensitive material placement step ST22. 5(a), in the photosensitive material placement step ST22, a photosensitive material 10A is placed on one side (the lower side in the example shown in FIG. 5(a)) of the master hologram substrate 100 in the normal direction (Z direction) of the master hologram substrate 100. Unlike the photosensitive material 10 that constitutes the master hologram substrate 100, this photosensitive material 10A does not yet have a hologram layer 20 or alignment marks 31 and 32 formed thereon.

[0034] <Replication process ST23> FIG. 5(b) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing the duplication step ST23. As shown in FIG. 5(b), in the duplication step ST23, the photosensitive material 10A is irradiated with light L1 from one side (the bottom side in the example shown in FIG. 5(b)) in the normal direction (Z direction) of the photosensitive material 10A, the same light L1 as used in manufacturing the master hologram substrate 100 described above. That is, the angle α that the light L1 forms with respect to the XY plane is 90°. However, unlike in manufacturing the master hologram substrate 100 described above, when irradiating the light L1 in the duplication step ST23, no mask 40 is used. Therefore, the entire light L1 is irradiated onto the photosensitive material 10A, and the light L1 that has passed through the photosensitive material 10A is simultaneously irradiated onto both the hologram layer 20 and the alignment marks 31 and 32 of the master hologram substrate 100. When light L1 is irradiated onto master hologram substrate 100, diffracted light (reflected diffracted light) R1 is generated at hologram layer 20, and diffracted light (reflected diffracted light) R2 and R3 are generated at alignment marks 31 and 32, respectively. Diffracted light R2 and R3 travel to one side (downward) in the normal direction (Z direction), and diffracted light R1 travels in a direction corresponding to the direction (β direction, see FIG. 2(c)) of light L2 used to form hologram layer 20 of master hologram substrate 100. These diffracted light R1 to R3 are then irradiated onto photosensitive material 10A.

[0035] Therefore, photosensitive material 10A is irradiated with the interference light of light L1 and diffracted light R1-R3, and the monomer component in the irradiated portion of photosensitive material 10A diffuses, generating interference fringes with a refractive index distribution. As a result, a hologram (volume hologram) layer 20A is formed in the portion irradiated with the interference light of light L1 and diffracted light R1, an alignment mark 31A made of a hologram (volume hologram) is formed in the portion irradiated with the interference light of light L1 and diffracted light R2, and an alignment mark 32A made of a hologram (volume hologram) is formed in the portion irradiated with the interference light of light L1 and diffracted light R3. The interference fringes that form hologram layer 20A and alignment marks 31A and 32A formed in this manner are the same as the interference fringes that form hologram layer 20 and alignment marks 31 and 32, respectively. That is, the hologram layer 20A and the alignment marks 31A and 32A formed on the photosensitive material 10A are copies of the hologram layer 20 and the alignment marks 31 and 32 on the master hologram substrate 100, respectively.

[0036] By carrying out the above-described preparation step ST21, photosensitive material placement step ST22, and replication step ST23, a replica hologram substrate can be manufactured. FIG. 5(c) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing an example of a replica hologram substrate manufactured by the manufacturing method according to this embodiment. The replica hologram substrate 100A shown in FIG. 5(c) has a configuration in which a photosensitive material 10A (see FIG. 5(b)) on which a hologram layer 20A and alignment marks 31A and 32A have been formed is cut to an appropriate size (after cutting the outer edge of the photosensitive material 10A). In a preferred embodiment, similar to the master hologram substrate 100 shown in FIG. 2(e), substrates 70 are laminated on both sides of the photosensitive material 10A on which the hologram layer 20A and alignment marks 31A and 32A have been formed, using an appropriate adhesive or a self-adhesive photosensitive material 10A. As with the master hologram substrate 100, the substrates 70 may be made of glass or a resin such as polycarbonate, polyamide, or acrylic. However, the present invention is not limited to this, and it is also possible to adopt a configuration in which the replica hologram substrate 100A does not have the substrate 70 laminated thereon (a configuration in which only the photosensitive material 10A on which the hologram layer 20A and the alignment marks 31A and 32A are formed) or a configuration in which the substrate 70 is laminated on only one side. 5(c) also includes a hologram layer 20A and multiple (two in this embodiment) alignment marks 31A and 32A, similar to the master hologram substrate 100. The alignment marks 31A and 32A are formed of holograms. When light is irradiated onto the hologram layer 20A from one side in the normal direction (Z direction) of the hologram layer 20A, the direction of the diffracted light produced is not the normal direction (Z direction) of the hologram layer 20A. On the other hand, when light is irradiated onto the alignment marks 31A and 32A from one side in the normal direction (Z direction) of the alignment marks 31A and 32A, the direction of the diffracted light produced is the normal direction (Z direction) of the alignment marks 31A and 32A.

[0037] [Method of manufacturing laminated hologram element] A method for manufacturing a laminated hologram element by laminating multiple master hologram substrates 100 (or replica hologram substrates 100A) will be described below. In the following explanation, the case of laminating master hologram substrates 100 will be described as an example, but the same process is also used when laminating replica hologram substrates 100A. FIG. 6 is a flow chart showing the outline of steps in the method for manufacturing a laminated hologram element according to this embodiment. As shown in FIG. 6, the manufacturing method according to this embodiment includes a preparation step ST31, a captured image obtaining step ST32, a coordinate detection step ST33, a position adjustment step ST34, and a bonding step ST35.

[0038] <Preparation process ST31> In preparation step ST31, red hologram substrate 100R, green hologram substrate 100G, and blue hologram substrate 100B are prepared. Red hologram substrate 100R is a hologram substrate having red hologram layer 20R as hologram layer 20 and red alignment marks 31R and 32R as alignment marks 31 and 32, which are formed by performing mask placement step ST11, hologram layer formation step ST12, and alignment mark formation step ST13 using red wavelength light as light L1 to L3 shown in FIG. 2. Green hologram substrate 100G is a hologram substrate having green hologram layer 20G as hologram layer 20 and green alignment marks 31G and 32G as alignment marks 31 and 32, which are formed by performing mask placement step ST11, hologram layer formation step ST12, and alignment mark formation step ST13 using green wavelength light as light L1 to L3 shown in FIG. The blue hologram substrate 100B is a hologram substrate having a blue hologram layer 20B, which is the hologram layer 20, and blue alignment marks 31B and 32B, which are the alignment marks 31 and 32, formed by performing a mask placement process ST11, a hologram layer formation process ST12, and an alignment mark formation process ST13 using light of blue wavelengths as the light L1 to L3 shown in Figure 2. In this embodiment, for each of the red hologram substrate 100R, green hologram substrate 100G, and blue hologram substrate 100B, a substrate 70 is laminated on only one side of the photosensitive material 10 on which the hologram layers 20R to 20B and alignment marks 31R to 31B, 32R to 32B are formed.

[0039] <Captured image acquisition step ST32> FIG. 7 is a schematic diagram illustrating the captured image obtaining step ST32 in the method for manufacturing a laminated hologram element according to this embodiment. In the captured image obtaining step ST32, first, red hologram substrate 100R and blue hologram substrate 100B are arranged facing each other in the Z direction (thickness direction of each substrate) as shown in Fig. 7(a). Specifically, as shown in Fig. 7(a), red hologram substrate 10R is sucked (vacuum sucked) by suction stage 81, and blue hologram substrate 100B is sucked (vacuum sucked) by suction stage 82, which is arranged opposite suction stage 81 in the Z direction.

[0040] Next, as shown in FIG. 7(b), suction stages 81 and 82 are moved the same distance in a horizontal direction (e.g., the X direction) (accompanying this, red hologram substrate 100R and blue hologram substrate 10B also move horizontally), so that red alignment mark 32R of red hologram substrate 100R faces imaging unit 1a in the Z direction across half mirror 3a, and blue alignment mark 32B of blue hologram substrate 100B faces imaging unit 1b in the Z direction across half mirror 3b. Light source 2a is positioned so that emitted light is reflected by half mirror 3a and irradiated within the field of view of imaging unit 1a. Light source 2b is positioned so that emitted light is reflected by half mirror 3b and irradiated within the field of view of imaging unit 1b. In other words, the combination of imaging unit 1a, light source 2a, and half mirror 3a and the combination of imaging unit 1b, light source 2b, and half mirror 3b each constitute a coaxial epi-illumination optical system. However, the present invention is not limited to this, and it is also possible to use ring illumination concentric with the imaging means 1a and 1b as the light sources 2a and 2b without using the half mirrors 3a and 3b. The imaging means 1a and 1b may be, for example, a CCD area sensor or a CMOS area sensor (for example, "CA-H500MX" manufactured by Keyence Corporation). The light source 2a may be, for example, a red LED light source (for example, "HLV3-22RD-2" manufactured by CCS Corporation). The light source 2b may be, for example, a blue LED light source (for example, "HLV3-22BL-2" manufactured by CCS Corporation). However, as long as the light source 2a emits light with a wavelength including a red wavelength and the light source 2b emits light with a wavelength including a blue wavelength, it is also possible to use, for example, the same white LED light source as the light sources 2a and 2b.

[0041] Next, in the state shown in Figure 7(b), the light source 2a and half mirror 3a irradiate the red alignment mark 32R of the red hologram substrate 100R with first illumination light having a wavelength including red wavelengths from one side (the bottom side in the example shown in Figure 7(b)) in the normal direction (Z direction) of the red hologram substrate 100R (angle α shown in Figure 7(b) = 90°), and the imaging means 1a captures an image of the red alignment mark 32R from one side (the bottom side) in the normal direction (Z direction) of the red hologram substrate 100R to obtain a first captured image. Similarly, in the state shown in Figure 7(b), third illumination light having a wavelength including blue wavelengths is irradiated onto blue alignment mark 32B of blue hologram substrate 100B from one side (the upper side in the example shown in Figure 7(b)) in the normal direction (Z direction) of blue hologram substrate 100B by light source 2b and half mirror 3b, and a third captured image is obtained by imaging blue alignment mark 32B from one side (the upper side) in the normal direction (Z direction) of blue hologram substrate 100B by imaging means 1b.

[0042] In order to accurately detect the coordinates of the red alignment mark 32R and the blue alignment mark 32B in the coordinate detection step ST33 described below, it is preferable to increase the resolution of the first captured image and the third captured image. For this reason, it is preferable to capture the first captured image by limiting the field of view of the imaging means 1a to the red alignment mark 32R and its vicinity, rather than the entire red hologram substrate 100R. Then, after acquiring the first captured image of the red alignment mark 32R and the third captured image of the blue alignment mark 32B, the first captured image of the red alignment mark 31R and the third captured image of the blue alignment mark 31B are acquired in the same manner. Specifically, the suction stage 81 is moved in the horizontal direction (X direction) relative to the imaging means 1a (and the red hologram substrate 100R is moved in the horizontal direction accordingly), so that the field of view of the imaging means 1a is set to the red alignment mark 31R and its vicinity, and the first captured image is acquired. Alternatively, two imaging means 1a may be provided, one for capturing an image of the red alignment marks 31R and one for capturing an image of the red alignment marks 32R. The same applies to the imaging means 1b.

[0043] <Coordinate detection step ST33> In the coordinate detection step ST33, the first captured image and the third captured image are each subjected to image processing to detect the coordinates (XY coordinates) of the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B. The coordinates of the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B can be, for example, the center coordinates of the pixel areas corresponding to the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B, which are extracted by performing binarization processing on the first captured image and the third captured image. The coordinates of the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B detected in the first and third captured images are directly relative coordinates in the respective fields of view of the imaging units 1a and 1b. Since the positions of the imaging units 1a and 1b relative to the same predetermined reference position can be known in advance, the relative coordinates of the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B detected in the first and third captured images can be corrected using the positions of the imaging units 1a and 1b, respectively, to calculate the absolute coordinates of the red alignment marks 31R, 32R and the blue alignment marks 31B, 32B relative to the same reference position. These absolute coordinates are used as the coordinates in the position adjustment step ST34 described below.

[0044] <Position adjustment process ST34> In position adjustment step ST34, the positions of red hologram substrate 100R and blue hologram substrate 100B are adjusted so that the coordinates of red alignment mark 31R and blue alignment mark 31B match, and the coordinates of red alignment mark 32R and blue alignment mark 32B match. Specifically, the positions of the red hologram substrate 100R and the blue hologram substrate 100B are adjusted by moving at least one of the suction stage 81 that suctions the red hologram substrate 100R and the suction stage 82 that suctions the blue hologram substrate 100B in the X direction, the Y direction, or by rotating it around the Z direction.

[0045] <Laminating process ST35> In the bonding step ST35, the red hologram substrate 100R and the blue hologram substrate 100B after the position adjustment are bonded together. Specifically, for example, suction stages 81 and 82 are moved the same distance in the horizontal direction (e.g., the X direction) (since they are moved the same distance, the adjusted positions of red hologram substrate 100R and blue hologram substrate 100B do not change), thereby eliminating the presence of imaging means 1a and 1b, light sources 2a and 2b, and half mirrors 3a and 3b between suction stages 81 and 82. Next, to bond red hologram substrate 100R and blue hologram substrate 100B together, for example, a UV-curable adhesive (not shown) is applied to blue hologram substrate 100B. Thereafter, red hologram substrate 100R and blue hologram substrate 100B are brought into contact with each other. Specifically, at least one of suction stages 81 and 82 is moved in the Z direction to bring red hologram substrate 100R and blue hologram substrate 100B into contact with each other. Finally, ultraviolet light is irradiated onto the adhesive from an ultraviolet light irradiation means (not shown) to harden the adhesive, thereby bonding red hologram substrate 100R and blue hologram substrate 100B together. In order to bond red hologram substrate 100R and blue hologram substrate 100B together while they are aligned with high precision, bonding step ST35 is preferably performed in a vacuum chamber (not shown). That is, after suction stages 81 and 82 are carried into the vacuum chamber, adhesive is applied, at least one of suction stages 81 and 82 is moved in the Z direction, and ultraviolet light is irradiated.

[0046] Through the steps described above, the red hologram substrate 100A and the blue hologram substrate 100B are bonded together, and a laminate of these substrates is obtained. However, because the green hologram substrate 100G remains to be bonded (because the answer to step ST36 in FIG. 6 is "No"), the manufacturing method according to this embodiment again performs the captured image obtaining step ST32 through the bonding step ST35. Although details are omitted, in the second capture image obtaining step ST32 through the bonding step ST35, the green hologram substrate 100G and the laminate of the red hologram substrate 100A and the blue hologram substrate 100B are positioned opposite each other in the Z direction, and the same procedures as described above are performed. In the second captured image acquisition step ST32, green alignment marks 31G, 32G of green hologram substrate 100G are irradiated with second illumination light having a wavelength including a green wavelength from one side in the normal direction (Z direction) of green hologram substrate 100G, and a second captured image is acquired by capturing an image of green alignment marks 31G, 32G from one side in the normal direction (Z direction) of green hologram substrate 100G, and the light source that irradiates the second illumination light can be, for example, a green LED light source (for example, "HLV3-22GR-2" manufactured by CCS). However, as long as the light source emits light with a wavelength including a green wavelength, it is also possible to use, for example, a white LED light source.

[0047] By executing the captured image obtaining step ST32 twice as described above, the first captured image, the second captured image, and the third captured image are obtained as a whole in the captured image obtaining step ST32. Furthermore, by performing the coordinate detection step ST33 twice in total, the coordinates of the red alignment marks 31R, 32R, the green alignment marks 31G, 32G, and the blue alignment marks 31B, 32B are detected in the coordinate detection step ST33 as a whole. Furthermore, by performing the position adjustment process ST34 a total of two times, the positions of the red hologram substrate 100R, the green hologram substrate 100G, and the blue hologram substrate 100B are adjusted so that the coordinates of the red alignment mark 31R, the green alignment mark 31G, and the blue alignment mark 31B match, and the coordinates of the red alignment mark 32R, the green alignment mark 32G, and the blue alignment mark 32B match, as a whole, in the position adjustment process ST34. Furthermore, by performing the bonding step ST35 twice in total, the position-adjusted red hologram substrate 100R, green hologram substrate 100G, and blue hologram substrate 100B are bonded together in the bonding step ST35 as a whole.

[0048] By the process described above, all hologram substrates (red hologram substrate 100R, green hologram substrate 100G, and blue hologram substrate 100B) are bonded together (step ST36 shown in Figure 6 is "Yes"), and a laminated hologram element can be manufactured. 7(c) is a cross-sectional view (XZ cross-sectional view perpendicular to the Y direction) showing an example of a laminated hologram element manufactured by the manufacturing method according to this embodiment. In a preferred embodiment, laminated hologram element 200 shown in FIG. 7(c) has a configuration in which substrate 70 is laminated on green hologram substrate 100G via an appropriate adhesive or using self-adhesive photosensitive material 10 that constitutes green hologram substrate 100G. Substrate 70 may be made of, for example, glass or a resin such as polycarbonate, polyamide, or acrylic.

[0049] According to the manufacturing method of hologram substrate 100 and the manufacturing method of laminated hologram element 200 according to the present embodiment described above, an imaging unit (e.g., imaging unit 1a) is disposed on one side of a hologram substrate (e.g., red hologram substrate 100R) in the normal direction. The imaging unit detects and captures diffracted light from alignment marks (e.g., red alignment mark 32R) from one side of the normal direction of the hologram substrate, thereby enabling easy and accurate reading of alignment marks provided on the hologram substrate. Therefore, multiple hologram substrates (red hologram substrate 100R, green hologram substrate 100G, and blue hologram substrate 100B) can be easily and accurately aligned. Furthermore, by bonding the hologram substrates together after adjusting their positions, laminated hologram element 200 can be manufactured in which red hologram layer 20R, green hologram layer 20G, and blue hologram layer 20B of each hologram substrate are accurately aligned. [Explanation of symbols]

[0050] 10...Photosensitive material 20 Hologram layer 31, 32 Alignment marks 40... Mask 41 First opening 42, 43... Second opening 50...Translucent plate 60...Reflective mirror 70... Substrate 100···Hologram substrate (master hologram substrate) 100A···Replica hologram substrate 200···Laminated hologram element L1, L2, L3...light ST1: Mask placement process ST2: Hologram layer formation process ST3: Alignment mark formation process

Claims

1. A method for manufacturing a hologram substrate including a hologram layer and a plurality of alignment marks provided outside the hologram layer, the method comprising: a hologram layer forming step of irradiating a photosensitive material with light from two different directions, at least one of which is not a normal direction of the photosensitive material, and causing interference to form the hologram layer; an alignment mark forming step of irradiating light from one side and the other side in a normal direction of the photosensitive material onto an area outside the area where the hologram layer is formed in the photosensitive material, causing interference, thereby forming the alignment mark consisting of a hologram; A method for manufacturing a hologram substrate having the above structure.

2. a mask arrangement step, prior to the hologram layer formation step and the alignment mark formation step, of arranging a mask on the photosensitive material, the mask having a first opening provided at a position corresponding to the hologram layer and a second opening provided at a position corresponding to the alignment mark, so as to face one side in a normal direction of the photosensitive material, and the mask blocking light at other positions; In the hologram layer forming step, light is irradiated onto the photosensitive material from one side in a normal direction of the photosensitive material through the first opening of the mask, In the alignment mark forming step, light is irradiated onto the photosensitive material from one side in a normal direction of the photosensitive material through the second opening of the mask. The method for manufacturing the hologram substrate according to claim 1 .

3. In the alignment mark forming step, a reflecting mirror is disposed relative to the photosensitive material so as to face the other side in the normal direction of the photosensitive material, and the alignment mark is formed by causing interference between light irradiated onto the photosensitive material from one side in the normal direction of the photosensitive material through the second opening of the mask and light reflected by the reflecting mirror and irradiated onto the photosensitive material from the other side in the normal direction of the photosensitive material. The method for manufacturing the hologram substrate according to claim 2 .

4. A hologram substrate comprising a hologram layer and a plurality of alignment marks, the alignment mark is formed from a hologram, The direction of diffracted light generated when light is irradiated onto the hologram layer from one side in the normal direction of the hologram layer is not the normal direction of the hologram layer, but is the direction of diffracted light generated when light is irradiated onto the alignment mark from one side in the normal direction of the alignment mark is the normal direction of the alignment mark; Holographic substrate.

5. A method for producing a replica hologram substrate by duplicating a master hologram substrate according to claim 4, comprising the steps of: a photosensitive material arranging step of arranging a photosensitive material with respect to the master hologram substrate so as to face one side in a normal direction of the master hologram substrate; a duplication step of duplicating the hologram layer and the alignment marks of the master hologram substrate onto the photosensitive material by causing interference between light irradiated onto the photosensitive material from one side in a normal direction of the photosensitive material and diffracted light generated when the light is irradiated onto the master hologram substrate; A method for manufacturing a replica hologram substrate having the above structure.

6. As the hologram substrate according to claim 4, a red hologram substrate having a red hologram layer that is the hologram layer and a red alignment mark that is the alignment mark, both formed by irradiating with light having a red wavelength; a green hologram substrate having a green hologram layer that is the hologram layer and a green alignment mark that is the alignment mark, both formed by irradiating with light having a green wavelength; and a blue hologram substrate having a blue hologram layer that is the hologram layer and a blue alignment mark that is the alignment mark, both formed by irradiating with light having a blue wavelength, are prepared; a method for manufacturing a laminated hologram element by laminating the red hologram substrate, the green hologram substrate, and the blue hologram substrate, the method comprising: an image acquisition step of irradiating the red alignment mark of the red hologram substrate with first illumination light having a wavelength including a red wavelength from one side in a normal direction of the red hologram substrate, and capturing an image of the red alignment mark from one side in the normal direction of the red hologram substrate, thereby acquiring a first captured image; irradiating the green alignment mark of the green hologram substrate with second illumination light having a wavelength including a green wavelength from one side in the normal direction of the green hologram substrate, and capturing an image of the green alignment mark from one side in the normal direction of the green hologram substrate, thereby acquiring a second captured image; and irradiating the blue alignment mark of the blue hologram substrate with third illumination light having a wavelength including a blue wavelength from one side in the normal direction of the blue hologram substrate, and capturing an image of the blue alignment mark from one side in the normal direction of the blue hologram substrate, thereby acquiring a third captured image; a coordinate detection step of detecting coordinates of the red alignment mark, the green alignment mark, and the blue alignment mark by processing the first captured image, the second captured image, and the third captured image, respectively; a position adjusting step of adjusting the positions of the red hologram substrate, the green hologram substrate, and the blue hologram substrate so that coordinates of the red alignment mark, the green alignment mark, and the blue alignment mark match; a bonding step of bonding the red hologram substrate, the green hologram substrate, and the blue hologram substrate after position adjustment; A method for manufacturing a laminated hologram element having the above structure.

Images