Method for manufacturing hologram, light guide plate, and hologram original plate

Abstract

The present invention facilitates the filling of a refractive-index alignment liquid and improves the production efficiency of a hologram. Provided is a method for manufacturing a hologram that includes: a step of disposing, with a gap S therebetween, an overlap member 3 above one surface of a processing material 1 having an unexposed photosensitive layer 11; a step of filling the gap S between the processing material 1 and the overlap member 3 with a refractive-index alignment liquid; and a step of, after filling with the refractive-index alignment liquid, recording interference fringe on the photosensitive layer 11 by projecting coherent light onto the photosensitive layer 11. Supply holes 5 that communicate with the gap S are formed in the overlap member 3. The refractive-index alignment liquid is filled from the supply holes 5 into the gap S.

Description

Hologram manufacturing method, light guide plate, and hologram master plate

[0001] The present invention relates to a method for producing a hologram.

[0002] A hologram can be produced by irradiating a photosensitive layer with laser light of a predetermined wavelength from two different directions. Another known method for producing a hologram is to use a hologram master plate having a master hologram and optically replicate the interference fringes of the master hologram onto the photosensitive layer (Patent Document 1). Patent Document 1 discloses a method for replicating a hologram by laminating a photosensitive material film 1 for duplication onto a hologram master plate 35, dripping a refractive index matching liquid onto the film 1, and then covering the film 1 with anti-reflection coated glass 34. The reference numerals in the Background Art section are those used in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2000-162951

[0004] In Patent Document 1, it takes time for the dropped refractive index matching liquid to spread into a thin film on the photosensitive film 1 for duplication due to capillary force. Even if a large amount of refractive index matching liquid is dropped, the capillary force does not improve, and the time required for the liquid to spread into a thin film is hardly shortened. Furthermore, if the refractive index matching liquid is dropped onto the photosensitive film 1 for production and then covered with anti-reflection coated glass 34, there is a risk of air bubbles being trapped if the refractive index matching liquid does not spread into a thin film on the film 1. Therefore, it is desirable to fill the gap between the film 1 (corresponding to the processed material) and the anti-reflection coated glass 34 (corresponding to the overlapping member) with refractive index matching liquid after overlapping the film 1 (corresponding to the processed material). However, Patent Document 1 does not disclose or suggest such a method. If the gap could be easily filled with refractive index matching liquid, the work time could be shortened and hologram production efficiency could be improved.

[0005] A first object of the present invention is to provide a method for manufacturing a hologram that allows for easy filling of a refractive index matching liquid and improves hologram production efficiency. A second object of the present invention is to provide a hologram master for hologram duplication that allows for easy filling of a refractive index matching liquid.

[0006] In one aspect, a method for manufacturing a hologram is provided, comprising: a placement step of placing an overlapping member on one side of a workpiece having an unexposed photosensitive layer with a gap therebetween; a filling step of filling the gap between the workpiece and the overlapping member with a refractive index matching liquid; and an exposure step of irradiating the photosensitive layer with coherent light after filling with the refractive index matching liquid, thereby recording interference fringes in the photosensitive layer, wherein the overlapping member has a supply hole that communicates with the gap, and the refractive index matching liquid is filled into the gap through the supply hole.

[0007] A second aspect of the hologram manufacturing method is the same as the first aspect, except that the supply hole is formed in a region of the overlapping member through which coherent light for recording interference fringes in the photosensitive layer does not propagate. A third aspect of the hologram manufacturing method is the same as the first or second aspect, except that the diameter of the supply hole is 0.5 mm to 10 mm. A fourth aspect of the hologram manufacturing method is the same as any of the first to third aspects, except that a plurality of supply holes are formed at intervals. A fifth aspect of the hologram manufacturing method is the same as the fourth aspect, except that the interval between adjacent supply holes is 20 mm to 150 mm. A sixth aspect of the hologram manufacturing method is the same as any of the first to fifth aspects, except that the workpiece has a support substrate and the photosensitive layer provided on the support substrate, and in the arranging step, the overlapping member is arranged on one side of the support substrate of the workpiece with the gap therebetween. A seventh aspect of the hologram manufacturing method is the same as any one of the first to sixth aspects, except that the overlapping member is a hologram master plate having a master hologram. An eighth aspect of the hologram manufacturing method is the same as any one of the first to sixth aspects, except that the overlapping member is a light-transmitting plate. A ninth aspect of the hologram manufacturing method is the same as any one of the first to sixth aspects, except that the overlapping member is a prism.

[0008] In another aspect, there is provided a hologram master plate. The hologram master plate of a tenth aspect is used for replicating a hologram. The hologram master plate has an area where a master hologram is formed and an area where the master hologram is not formed, and a supply hole for supplying a refractive index matching liquid is formed in the area where the master hologram is not formed, penetrating the area in the thickness direction.

[0009] The hologram manufacturing method of the present invention utilizes a supply hole to easily fill the gap between the overlapping member and the processed material with refractive index matching liquid. By simplifying the refractive index matching liquid filling process, the work time can be shortened and hologram production efficiency can be improved.

[0010] 15 is a schematic side view of a hologram manufacturing apparatus according to a first embodiment; a plan view of an exposure unit of the same manufacturing apparatus; an enlarged cross-sectional view taken along line III-III in FIG. 2; a plan view of a hologram master; a cross-sectional view taken along line V-V in FIG. 4; a cross-sectional view taken along line VI-VI in FIG. 4; a perspective view of a hologram master; a schematic side view showing a step of bringing a photosensitive layer of a material to be processed and a light-transmitting plate into close contact in the hologram manufacturing method according to the first embodiment; a cross-sectional view showing a filling step of filling a gap with a refractive index matching liquid in the first embodiment; a reference explanatory diagram showing an exposure step in which interference fringes are formed in a photosensitive layer by coherent light; a schematic side view showing a step of wiping off the refractive index matching liquid; a plan view of a hologram continuum; a reference side view of a light guide plate on which a red hologram, a green hologram, and a blue hologram are stacked; a schematic side view of a hologram manufacturing apparatus according to a second embodiment; a plan view of an exposure unit of the same manufacturing apparatus; an enlarged cross-sectional view taken along line XVI-XVI in FIG. 15; a schematic side view of a hologram manufacturing apparatus according to a third embodiment. 19 is a plan view of an exposure unit of the same manufacturing apparatus. It is an enlarged cross-sectional view taken along line XIX-XI of FIG. 18. It is a cross-sectional view showing a filling step of filling a gap with a refractive index matching liquid in a third embodiment. It is a reference explanatory diagram showing an exposure step in which interference fringes are formed on a photosensitive layer by coherent light.

[0011] [First Embodiment] One embodiment will be described below with reference to the drawings. In this specification, the "first surface" of a certain component (e.g., a hologram master or a light-transmitting plate) refers to the surface on which coherent light is incident to expose a photosensitive layer, and the "second surface" of a certain component refers to the surface opposite to the first surface. Please note that the thickness, size, scale, and shape of components such as layers shown in each figure may differ from the actual ones.

[0012] {Hologram Manufacturing Apparatus of First Embodiment} The first embodiment relates to a manufacturing apparatus that uses a hologram master to record interference fringes of a master hologram in a photosensitive layer, i.e., replicates a hologram in a photosensitive layer. Fig. 1 is a side view of the hologram manufacturing apparatus of the first embodiment, Fig. 2 is a plan view of an exposure unit in the manufacturing apparatus seen from above, and Fig. 3 is an enlarged cross-sectional view of the exposure unit cut along the transport direction. Note that Fig. 2 does not include a refractive index matching liquid supply device. Note that in this specification, the "transport direction" corresponds to the longitudinal direction of the material to be processed, and the "width direction" refers to the direction perpendicular to the longitudinal direction within the surface of the material to be processed.

[0013] The hologram manufacturing apparatus of this embodiment records interference fringes of the master hologram in a photosensitive layer by transmitting coherent light and diffracted light generated from a master hologram by irradiating the coherent light through the photosensitive layer, thereby replicating a hologram in the photosensitive layer. In this specification, a hologram replicated using a hologram master plate may be referred to as a "replica hologram." The material to be processed having the photosensitive layer may be in the form of a sheet, but preferably in the form of a long strip. By loading the material to be processed having the photosensitive layer into the manufacturing apparatus and exposing the photosensitive layer using the manufacturing apparatus, multiple replicate holograms can be continuously obtained. The sheet shape refers to a predetermined size, such as a substantially rectangular, square, or circular shape in plan view. The long strip shape refers to a strip whose longitudinal length is significantly longer than its lateral length. The long strip photosensitive layer is typically stored in a roll and unwound from the roll when in use. A manufacturing apparatus for producing a replica hologram on a long strip-shaped photosensitive layer will now be described in detail.

[0014] 1 to 3 , the manufacturing apparatus A includes a transport section B that transports the workpiece 1 having a photosensitive layer 11 in the longitudinal direction, an exposure section C that exposes the photosensitive layer 11 transported by the transport section B, and a light source D that irradiates the laminate including the photosensitive layer 11 with coherent light L1 in the exposure section C. The various operations of the manufacturing apparatus A, which will be described later, are controlled by a control section (not shown) equipped with a computer or the like. The general flow of replica hologram production is as follows: the workpiece 1 having the photosensitive layer 11 is transported to the exposure section C, a refractive index matching liquid is filled into the gap between the workpiece 1 and the hologram master 3, which is the overlapping member, and the workpiece 1, the photosensitive layer 11 is exposed to light to form a replica hologram, and the workpiece 1 is transported again. This process is repeated to continuously produce multiple replica holograms. In this embodiment, the hologram master 3 corresponds to the overlapping member.

[0015] <Processable Material Having a Photosensitive Layer> The processable material 1 has a photosensitive layer 11. The photosensitive layer 11 is made of an unexposed photosensitive material. Examples of photosensitive materials that can be used include photopolymers, photoresists, silver halide emulsions, and dichromated gelatin. The thickness of the photosensitive layer 11 is typically several μm to 20 μm. The processable material 1 may be composed of only the photosensitive layer 11, but the photosensitive layer 11 itself often does not have enough strength to withstand transport through the manufacturing equipment A. For this reason, the photosensitive layer 11 is typically formed on a long, strip-shaped support substrate 12. Therefore, a preferred processable material 1 has a support substrate 12 and a photosensitive layer 11 formed thereon in a solid state. The support substrate 12 is not particularly limited as long as it has a refractive index approximately equal to that of the light-transmitting plate. Examples of the support substrate 12 include glass, TAC (triacetylcellulose), polycarbonate, and other resins. The thickness of the support substrate 12 is not particularly limited, but is about 10 μm to 100 μm.

[0016] The long strip-shaped material 1 to be treated may be wound into a roll for storage, transportation, etc. However, it is preferable to attach a protective film 15 or the like to the material 1 to prevent scratches on the support substrate 12 and the photosensitive layer 11. For example, an adhesive-backed protective film 15 is attached to the support substrate 12 side of the material 1 to be treated. A release liner 16 is attached to the photosensitive layer 11 side of the material 1 to be treated. The release liner 16 is attached for the following two purposes: one is to protect the photosensitive layer 11; and the other is to conceal the slight adhesiveness of the photosensitive layer 11, which has slight adhesiveness, and prevent blocking when the material 1 to be treated is wound into a roll. In this way, a laminate film consisting of the adhesive-backed protective film 15 / material 1 to be treated (support substrate 12 + photosensitive layer 11) / release liner 16 is wound into a roll and loaded into the unwinding section of the manufacturing apparatus A.

[0017] <Conveying section> Conveying section B unwinds the laminate film including the material to be treated 1 wound around a roll and conveys the unwound laminate film including the material to be treated 1 in its longitudinal direction. Specifically, conveying section B has an unwinding section 21 that loads the laminate film wound around a roll, a film peeling section 22 that peels the protective film 15 together with the adhesive from the laminate film and takes it up, a liner peeling section 23 that peels the release liner 16 from the laminate film and takes it up, accumulation mechanisms 241, 242 that allow the material to be treated 1 that is intermittently conveyed to remain, thereby enabling the material to be treated 1 to be continuously unwound and taken up, a film laminating section 25 that bonds another protective film 15 with adhesive to the material to be treated 1 that has been exposed to light, a liner laminating section 26 that bonds another release liner 16 to the material to be treated 1 that has been exposed to light, and a take-up section 27 that takes up the material to be treated 1 with the protective film 15 and release liner 16 bonded to it. Note that guide rolls and the like are arranged at appropriate positions on the conveying path of conveying section B. In the illustrated example, a first accumulation mechanism 241 is provided between unwinding section 21 and exposure section C, and a second accumulation mechanism 242 is provided between exposure section C and winding section 27.

[0018] Conveying unit B unwinds the laminate film containing the material 1 to be treated from unwinding unit 21 at a predetermined speed and conveys it in the longitudinal direction. Upstream of first accumulation mechanism 241, film peeling unit 22 and liner peeling unit 23 peel the adhesive-backed protective film 15 and release liner 16 from the laminate film. Conveying unit B conveys the material 1 to exposure unit C, where it temporarily stops conveying. As described below, after the exposure process for material 1 is completed in exposure unit C, conveying unit B conveys material 1 downstream in the conveying direction by a predetermined length and then stops again. By repeating this intermittent conveying process of conveying material 1, stopping conveying, exposing material 1, and conveying material 1 again, multiple duplicate holograms can be continuously produced in the long strip-shaped photosensitive layer 11.

[0019] After the exposure process is completed, another adhesive-backed protective film 15 and release liner 16 are bonded to the treated material 1 in the film bonding section 25 and liner bonding section 26. The winding section 27 winds up the treated material 1 to which the protective film 15 and release liner 16 are bonded at a predetermined speed. The first accumulation mechanism 241 temporarily retains the treated material 1 being unwound from the unwinding section 21 while the transport of the treated material 1 is stopped at the exposure section C, and releases the retained treated material 1 when the treated material 1 that was stopped at the exposure section C begins to be transported again. The second accumulation mechanism 242 releases the treated material 1 being wound up by the winding section 27 while the transport of the treated material 1 is stopped at the exposure section C, and temporarily retains the treated material 1 when the treated material 1 that was stopped at the exposure section C begins to be transported again. 1, accumulation rolls that move up and down are used as the first accumulation mechanism 241 and the second accumulation mechanism 242. Note that a production line may be configured in which either the first accumulation mechanism 241 or the second accumulation mechanism 242 is not provided.

[0020] <Light Source> The light source D irradiates the laminate including the photosensitive layer 11 with coherent light L1 in the exposure section C. Laser light is typically used as the coherent light. The wavelength of the laser light is not particularly limited, but when the replicated hologram is incorporated into, for example, an AR (Augmented Reality) device, it is preferable to use laser light in the visible light region. For example, it is preferable to use laser light with a red wavelength, green wavelength, or blue wavelength. In the present invention, "red wavelength" refers to, for example, a wavelength of 600 to 700 nm, "green wavelength" refers to, for example, a wavelength of 500 to 560 nm, and "blue wavelength" refers to, for example, a wavelength of 430 to 500 nm. The type of laser light is not particularly limited, and examples include solid-state lasers, liquid lasers, gas lasers, and semiconductor lasers.

[0021] The light source D includes, for example, a laser oscillator 61, a mirror 64 that changes the direction of laser light emitted from the laser oscillator 61 and directs the laser light toward a laminate including the photosensitive layer 11, and various optical devices (such as a magnifying lens 62 and a collimating lens 63) disposed between the laser oscillator 61 and the mirror 64. The optical devices may be conventionally known and disposed as appropriate. Examples of the optical devices include a shutter, a beam expander, a half-wave plate, a dielectric multilayer mirror, and a beam splitter. These optical devices may be appropriately selected and disposed on the optical path. The laser oscillator 61 emits laser light of a predetermined wavelength. In one embodiment, a laser oscillator 61 that emits laser light of a visible light wavelength is used. Examples of such laser oscillators 61 include a red laser oscillator that emits a laser beam with a red wavelength (referred to as red laser beam), a green laser oscillator that emits a laser beam with a green wavelength (referred to as green laser beam), and a blue laser oscillator that emits a laser beam with a blue wavelength (referred to as blue laser beam). For example, the red laser oscillator may be a 640 nm laser oscillator manufactured by Cobolt (product name "Cobolt 05-01 Series Bolero"), etc. The green laser oscillator may be a 532 nm laser oscillator manufactured by Cobolt (product name "Cobolt 05-01 Series Samba"), etc. The blue laser oscillator may be a 460 nm laser oscillator manufactured by Coherent (product name "Genesis MX460"), etc.

[0022] As will be described later, the hologram master plate 3 has multiple rows and multiple columns of master holograms. The light source D may be configured to irradiate all of the master holograms with laser light (coherent light) using a single mirror. Alternatively, the light source D may be configured to irradiate one master hologram with laser light using a single mirror, and then sequentially irradiate the remaining master holograms with laser light by moving the single mirror. Alternatively, the light source D may have multiple mirrors, and may be configured to irradiate several master holograms simultaneously or sequentially with laser light using the multiple mirrors, and then move the multiple mirrors to irradiate the remaining several master holograms simultaneously or sequentially with laser light. In the example shown in FIG. 1 , multiple mirrors 64 are arranged side by side in the width direction, and the multiple mirrors 64 can be moved independently or simultaneously in the longitudinal direction of the workpiece 1.

[0023] <Exposure Section> The exposure section C is a part of the manufacturing apparatus A that exposes the photosensitive layer 11. The exposure section C includes a hologram master 3 including a master hologram 31, a master mounting member 38 for mounting the hologram master 3, a light-transmitting plate 41 arranged on the first surface side of the hologram master 3, and a plate mounting member 48 for mounting the light-transmitting plate 41. The material to be processed 1 including the photosensitive layer 11 is interposed between the first surface of the hologram master 3 and the second surface of the light-transmitting plate 41. Therefore, in the exposure section C, the light-transmitting plate 41, the material to be processed 1, and the hologram master 3 are arranged in this order from bottom to top.

[0024] (Hologram master and master mounting member) Fig. 4 is a plan view of the hologram master 3 as viewed from the second surface side. Fig. 5 is a cross-sectional view of the hologram master 3 including the area where the supply holes are provided, and Fig. 6 is a cross-sectional view of the hologram master 3 including the master hologram 31. Fig. 7 is a perspective view of the hologram master 3.

[0025] 1 to 7 , the hologram master 3 has at least one master hologram 31, and preferably a plurality of master holograms 31. In terms of layer configuration, the hologram master 3 has, for example, a first substrate 32, a second substrate 33, and a plurality of master holograms 31 interposed between the first substrate 32 and the second substrate 33. The plurality of master holograms 31 are arranged at predetermined intervals, preferably at equal intervals, along the surface of the hologram master 3. In the illustrated example, a total of nine master holograms 31 (3×3) are provided on the hologram master 3. Specifically, the master holograms 31 are arranged in three rows in the transport direction of the material 1 to be processed and in three columns in the width direction of the material 1 to be processed, with a gap between each row and each column. Note that a "row" refers to a group arranged in the width direction, and a "column" refers to a group arranged in the transport direction (corresponding to the longitudinal direction of the material 1 to be processed). However, the number and arrangement of the master holograms 31 provided on the hologram master plate 3 are not limited to the above-mentioned 3 rows x 3 columns, and can be changed as appropriate.

[0026] The master hologram 31 is a portion of a layer 34 (photosensitive material layer) made of a photosensitive material where interference fringes are recorded. The thickness of the photosensitive material layer 34 including the master hologram 31 is approximately several μm to 20 μm. The first and second substrates 32, 33 are not particularly limited as long as they are base materials having a refractive index approximately equal to that of the light-transmitting plate, and examples thereof include glass and resins such as TAC (triacetyl cellulose) and polycarbonate. The thickness of the first and second substrates 32, 33 is not particularly limited and is approximately 10 μm to 100 μm.

[0027] The hologram master 3 is fabricated, for example, by the following method. First and second substrates 32, 33 are provided on both sides of a photosensitive material layer 34, such as a photopolymer. Next, a master hologram is fabricated by irradiating the photosensitive material layer 34 with light of a predetermined wavelength 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"). Specifically, by irradiating the photosensitive material layer 34 with interference light of laser beams of a predetermined wavelength from two directions, the monomer components in the irradiated portions of the photosensitive material layer 34 are diffused, resulting in a refractive index distribution. This records interference fringes in the irradiated portions, forming the master hologram 31. A bleaching process is then performed to complete the photoreaction in the unexposed portions of the photosensitive material layer 34 (areas where no master hologram is formed). Irradiation with red laser light generates a red master hologram, irradiation with green laser light generates a green master hologram, and irradiation with blue laser light generates a blue master hologram.

[0028] The hologram master 3, which is a stacking member, may be used as is. To prevent deformation such as curvature when the hologram master 3 is moved, the hologram master 3 is attached to a master mounting member 38. The master mounting member 38 has a portion 381 that holds the hologram master 3 and a movement mechanism 382 that moves the holding portion 381. The holding portion 381 is attached in close contact with the periphery and second surface of the hologram master 3. The movement mechanism 382 moves the holding portion 381 that holds the hologram master 3 to move the hologram master 3 closer to and farther away from the workpiece 1. In the example of FIG. 1 , the workpiece 1 is transported substantially horizontally in the exposure unit C, so the movement mechanism 382 moves the hologram master 3 up and down. As shown by the two-dot chain line in Figure 3, the moving mechanism 382 moves the holding unit 381 holding the hologram master 3 upward, thereby separating the hologram master 3 from the material to be processed 1. Furthermore, the moving mechanism 382 moves the holding unit 381 downward, thereby positioning the hologram master 3 with a gap from the material to be processed 1. A conventionally known actuator such as a pneumatic cylinder or a rack and pinion can be used as the moving mechanism 382. The moving mechanism 382 may be configured to move the hologram master 3 a predetermined amount in the width direction and / or the transport direction.

[0029] (Supply Hole) The hologram master 3 has a supply hole 5 formed therein for supplying a refractive index matching liquid. The supply hole 5 penetrates the hologram master 3 in the thickness direction. In the illustrated example, the thickness direction is approximately parallel to the normal direction. The supply hole 5 penetrates the thickness direction and communicates with a gap S defined by the hologram master 3 and the material to be processed 1. The gap between the hologram master 3 and the material to be processed 1 can be filled with a refractive index matching liquid through the supply hole 5. The supply hole 5 is formed in an area that does not have a master hologram 31. If the supply hole 5 were formed to penetrate the master hologram 31, coherent light incident on the master hologram 31 would be scattered by the supply hole, which could prevent the interference fringes of the master hologram 31 from being accurately recorded in the photosensitive layer 11.

[0030] The diameter of the supply hole 5 is not particularly limited, but if it is too small, it may be difficult to introduce the refractive index matching liquid, and if it is too large, the strength of the hologram master 3 may be reduced. From this perspective, the diameter 5Y of the supply hole 5 is, for example, 0.5 mm to 10 mm, preferably 2 mm to 8 mm (see FIG. 4 ). It is sufficient that at least one supply hole 5 is provided within the surface of the hologram master 3. It is preferable to provide multiple supply holes 5, as this allows the refractive index matching liquid to be filled in a shorter time. In the illustrated example, when viewed in the width direction of the workpiece 1, multiple supply holes 5 are provided along the width direction, and when viewed in the longitudinal direction of the workpiece 1, multiple supply holes 5 are provided along the longitudinal direction. Therefore, the supply holes 5 are arranged in a grid pattern in the area not including the master hologram 31. When a plurality of supply holes 5 are provided, the interval between adjacent supply holes 5 is not particularly limited, but is, for example, 20 mm to 150 mm, preferably 30 mm to 100 mm, and more preferably 40 mm to 60 mm, because this allows filling with the refractive index matching liquid in a relatively short time. The interval refers to the interval 5W1 between adjacent supply holes 5 in the width direction or the interval 5W2 between adjacent supply holes 5 in the longitudinal direction (see FIG. 4).

[0031] When a plurality of supply holes 5 are provided, the area of ​​the hologram master 3 (overlapping member) per one supply hole 5 is, for example, 1000 mm ２ ~30,000mm ２ and preferably 2000 mm ２ ~25,000mm ２ The area of ​​the hologram master 3 (overlapping member) per supply hole 5 can be calculated by the following formula: Area of ​​the hologram master 3 (overlapping member) per supply hole 5 = Area of ​​the hologram master 3 / Number of supply holes 5.

[0032] Furthermore, the supply holes 5 are formed in a region where coherent light for recording interference fringes in the photosensitive layer 11 does not propagate. As will be described later, during exposure, diffracted light and its reflected light generated by the master hologram 31 propagate in one direction (e.g., the longitudinal direction) of the workpiece 1. If supply holes 5 are formed in the direction in which the diffracted light or reflected light (both of which are coherent light) propagate, the light will be scattered by the supply holes. To prevent this, the supply holes 5 are formed in a region where coherent light does not propagate. In the illustrated example, a plurality of supply holes 5 are formed at predetermined intervals in regions not having a master hologram 31 in the width direction and in regions not having a master hologram 31 in the longitudinal direction.

[0033] Furthermore, a supply device is provided to supply the refractive index matching liquid to the supply hole 5. As shown in FIGS. 1 and 3 , the supply device includes a tank 511 that stores the refractive index matching liquid, a tube 512 connected to the tank 511, an insertion portion 513 provided at the tip of the tube 512, and an opening / closing portion 514 such as a valve. The tube 512 is flexible so that it can follow the movement of the hologram master 3. When the holding portion 381 of the master mounting member 38 holds the second surface of the hologram master 3 as in this embodiment, the holding portion 381 has a communication hole 383 that communicates with the supply hole 5. As shown in FIG. 3 , the insertion portion 513 is inserted into the communication hole 383. When the opening / closing portion 514 is opened, the refractive index matching liquid in the tank 511 flows into the supply hole 5 through the tube 512, and the refractive index matching liquid is filled into the gap S from the supply hole 5. Note that the tank, the opening / closing portion, and the upper portion of the tube 512 are not shown in FIG. 3 . In addition, in FIG. 3, the tube 512 and the insertion portion 513 are not shown in cross section (the same applies to the other figures).

[0034] (Light-Transmitting Plate) The light-transmitting plate 41 is disposed on the opposite side of the master hologram 31. The material to be processed 1 is interposed between the light-transmitting plate 41 and the hologram master 3. For example, the light-transmitting plate 41 may be a plate having the same area as the hologram master 3 or a larger or smaller area than the hologram master 3. The thickness of the light-transmitting plate 41 is appropriately set; however, if it is too small, it may be prone to breakage, and if it is too large, it is undesirable from a cost-effectiveness perspective. From this perspective, the thickness of the light-transmitting plate 41 is 10 mm to 50 mm, preferably 25 mm to 45 mm. The light-transmitting plate 41 is formed from a material that transmits coherent light. For example, the light-transmitting plate 41 is formed from a material having a refractive index of approximately 1.5. Examples of materials having a refractive index of approximately 1.5 include glass and resins such as triacetylcellulose (TAC) and polycarbonate. Examples of the glass include alkali-free glass, low-alkali glass, borosilicate glass, and soda-lime glass.

[0035] (Other) The exposure unit C is provided with a wiping unit 281 that wipes away the refractive index matching liquid. The wiping unit 281 can be, for example, a wiping roll with a liquid-absorbing material on its circumferential surface. Furthermore, the exposure unit C is provided with a pressure roll 282 that presses the workpiece 1 against the light-transmitting plate. A bleaching unit 29 is also provided downstream of the exposure unit C. The bleaching unit 29 irradiates the workpiece 1 with UV / VIS light of a relatively high intensity, but not enough to damage the material forming the photosensitive layer 11. The exposure bleaches the exposed photosensitive layer 11, completing the photoreaction of the photosensitive layer 11 (both the areas irradiated with coherent light and the areas not irradiated with coherent light).

[0036] {Method of Manufacturing a Hologram of the First Embodiment} Next, a method of manufacturing a hologram will be described. The manufacturing method of the present invention includes a placement step of placing an overlapping member on one side of a workpiece having an unexposed photosensitive layer, with a gap therebetween; a filling step of filling the gap between the workpiece and the overlapping member with a refractive index matching liquid; and an exposure step of irradiating the photosensitive layer with coherent light after filling the refractive index matching liquid, thereby recording interference fringes in the photosensitive layer. In this embodiment, the overlapping member is a hologram master. In the filling step, the refractive index matching liquid is filled into the gap through supply holes 5 formed in the hologram master 3.

[0037] To produce a duplicate hologram, for example, the above-described manufacturing apparatus A is used. As shown in FIG. 8 , the moving mechanism 382 separates the hologram master 3 from the support substrate 12 of the workpiece 1, the transport unit B transports the workpiece 1 downstream in the transport direction by a predetermined length, and the transport of the workpiece 1 in the exposure unit C is stopped. The predetermined length corresponds to the portion of the photosensitive layer 11 for which exposure processing has been completed. Next, the pressure roll 282 is moved downstream in the transport direction while in contact with the second surface of the support substrate 12 (the movement of the pressure roll 282 is indicated by a two-dot chain line). This causes the first surface of the photosensitive layer 11 of the workpiece 1 to adhere to the second surface of the light-transmitting plate. Because the photosensitive layer 11 has slight adhesiveness, lightly pressing the workpiece 1 with the pressure roll 282 allows the photosensitive layer 11 of the workpiece 1 to adhere to the second surface of the light-transmitting plate without creating an air interface between the photosensitive layer 11 and the light-transmitting plate.

[0038] 1 and 3, the hologram master 3 is lowered by the movement mechanism 382 and brought close to one surface (second surface) of the support substrate 12 of the workpiece 1. That is, the hologram master 3, which is an overlapping member, is placed on one surface of the support substrate 12 of the workpiece 1 with a gap therebetween. More specifically, when the hologram master 3 is lowered, the first surface of the hologram master 3 faces the second surface of the support substrate 12 of the workpiece 1 with a gap S therebetween (see FIG. 3). Because the support substrate 12 is not adhesive, the gap S exists between the first surface of the hologram master 3 and the support substrate 12 of the workpiece 1. The gap S is, for example, about 1 μm to 30 μm.

[0039] <Filling Process> The presence of the gap S creates an air interface. Therefore, the gap S between the first surface of the hologram master 3 and the support substrate 12 of the workpiece 1 is filled with a refractive index matching liquid. The refractive index matching liquid may be any liquid that has been publicly known or will become publicly known after the filing of this application. The refractive index matching liquid is a liquid having a refractive index approximately equal to that of the light-transmitting plate 41. For example, a silicone oil, whose refractive index is similar to that of glass, may be used as the refractive index matching liquid. Oil components such as silicone oil are also called index oil or matching oil. The opening / closing portion 514 is opened, and the refractive index matching liquid in the tank 511 is supplied to the supply hole 5. As shown in FIG. 9( a), the refractive index matching liquid 7 supplied from the tube 512 flows into the gap S through the supply hole 5. The refractive index matching liquid 7 may be supplied under pressure. When the refractive index matching liquid 7 is supplied from above as in this embodiment, the refractive index matching liquid 7 flows into the gap S under its own weight without pressure. In particular, because the gap S is very small, the refractive index matching liquid 7 that has entered the supply hole 5 quickly spreads throughout the gap S due to capillary action. As shown in FIG. 9B , when the entire gap S is filled with the refractive index matching liquid 7, the opening / closing section 514 is closed, and the supply of the refractive index matching liquid 7 is stopped. The amount of refractive index matching liquid 7 to be filled into the entire gap S can be preset based on the size of the gap S and the area of ​​the hologram master 3, and the supply of the refractive index matching liquid 7 is stopped according to the preset amount. Alternatively, a sensor (not shown) may detect when the entire gap S is filled with the refractive index matching liquid 7, and the supply of the refractive index matching liquid may be stopped at that timing. In this way, a laminate consisting of the hologram master 3 / refractive index matching liquid 7 / processed material 1 (support substrate 12 + photosensitive layer 11) / transparent plate 41, with no air interface between the layers, is temporarily formed in the exposure section C.

[0040] By utilizing the supply holes 5, the operation of filling the gap S with the refractive index matching liquid 7 can be easily performed. Furthermore, since a plurality of supply holes 5 are formed, the refractive index matching liquid 7 can be filled into the gap S in a short time. In particular, since the supply holes 5 are arranged at intervals of 20 mm to 150 mm, the refractive index matching liquid 7 can be filled into the gap S in an extremely short time. The ability to fill the refractive index matching liquid 7 in a short time improves the production efficiency of holograms.

[0041] 1 , coherent light L1 is irradiated onto the master hologram 31 from the first surface side of the light-transmitting plate 41 of this laminate, exposing the photosensitive layer 11 to a duplicate hologram having interference fringes similar to those of the master hologram 31, in the photosensitive layer 11. For example, the coherent light L1 is irradiated onto the master holograms 31 arranged in the first row, and a duplicate hologram corresponding to each master hologram 31 is produced in the photosensitive layer 11. The coherent light L1 is shaped to have substantially the same shape and size as the master hologram 31 in a planar view. However, the coherent light L1 may be larger or smaller than the shape of the master hologram 31. The coherent light L1 for exposing the photosensitive layer 11 may be, for example, red laser light, green laser light, or blue laser light, or a composite laser light obtained by mixing at least two types of laser light selected from red laser light, green laser light, and blue laser light. It should be noted that when laser light of a predetermined wavelength (e.g., red laser light) is irradiated onto the master hologram 31 to expose the photosensitive layer 11, the master hologram 31 is naturally produced using laser light of the same wavelength as the laser light of the predetermined wavelength.

[0042] FIG. 10 is an explanatory diagram of the state during exposure, showing a longitudinal cut of the exposed portion C including the master hologram 31. Hatching representing the cut surface is omitted. As shown in FIG. 10 , coherent light L1 (laser light) irradiated from the first surface of the light-transmitting plate 41 passes through the photosensitive layer 11 and then enters the master hologram 31, generating diffracted light L2. As the diffracted light L2 passes through the photosensitive layer 11, the interference fringes of the master hologram 31 are recorded in the photosensitive layer 11. The portion of the photosensitive layer 11 where the interference fringes are recorded becomes the duplicate hologram 310. While FIG. 10 illustrates an example in which the coherent light L1 is irradiated parallel to the normal direction of the master hologram 31 and the diffracted light propagates at an acute diffraction angle, this is not limiting. The coherent light L1 is irradiated at an angle that reproduces the master hologram 31.

[0043] Incidentally, the diffracted light L2 may be internally reflected at the air interface of the light-transmitting plate 41. Reflected light L3 of this diffracted light L2 propagates in one direction (in the illustrated example, the longitudinal direction of the material 1) through the stack including the light-transmitting plate 41. As described above, the supply holes 5 are formed in an area where coherent light (such as diffracted light or reflected light) does not propagate. Therefore, even if the reflected light L3 occurs, the reflected light L3 can be prevented from scattering within the stack and propagating in random directions.

[0044] 1 , mirror 64 is then moved to the second row, and coherent light L1 is applied to the master holograms 31 arranged in that row, creating a duplicate hologram in photosensitive layer 11. Mirror 64 is then moved to the third row, and a duplicate hologram is created in the same manner. In this way, duplicate holograms corresponding to all of the master holograms 31 on hologram master 3 are created in photosensitive layer 11.

[0045] <Post-process> Thereafter, the moving mechanism 382 separates the hologram master 3 from the support substrate 12 of the workpiece 1. After the hologram master 3 is separated, a refractive index matching liquid is usually attached to the second surface of the support substrate 12 of the workpiece 1. Therefore, as shown in Fig. 11 , the wiping unit 281 is moved while being in contact with the second surface of the support substrate 12 of the workpiece 1, thereby removing the refractive index matching liquid.

[0046] <Repeated Process> The material 1 is then transported downstream in the transport direction by a predetermined length (the portion that has been exposed), and the transport is stopped. The material 1 is adhered to the second surface of the light-transmitting plate 41 due to the slight adhesiveness of the photosensitive layer 11. Because the slight adhesiveness of the photosensitive layer 11 is very weak, the material 1 separates from the light-transmitting plate when the transport unit B pulls the material 1. However, if the photosensitive layer 11 is difficult to separate from the light-transmitting plate 41, an appropriate peeling means may be provided in the transport unit B, or the light-transmitting plate 41 may be moved away from the material 1 (not shown).

[0047] The exposed material 1 is transported and stopped, returning to the state shown in Figure 8. As a result, the exposed photosensitive layer 11 is sent downstream, and the unexposed photosensitive layer 11 is subsequently placed in the exposure section C. Thereafter, similar steps are taken to bring the photosensitive layer 11 of the material 1 into close contact with the light-transmitting plate 41, place the hologram master 3 on the support substrate 12 of the material 1 with a gap S therebetween, fill the gap S with a refractive index matching liquid through the supply hole 5, expose the material 1 to produce duplicate holograms in the photosensitive layer 11 corresponding to all the master holograms 31, release the hologram master 3, transport the material 1 a predetermined length, and then stop the material. These steps are then repeated. In this manner, duplicate holograms can be produced continuously.

[0048] Figure 12(a) is a plan view of an exposed material 100. The exposed material 1 has a plurality of holograms arranged continuously in its photosensitive layer 11. Hereinafter, the "exposed material 100" will be referred to as the "hologram continuum 100." The above example illustrates the use of three rows of master holograms 31, so the hologram continuum 100 in Figure 12(a) has a plurality of duplicate holograms 310 arranged in three rows.

[0049] 1, a bleaching treatment is performed on a hologram continuum 100 in a bleaching unit 29. A protective film 15 and a release liner 16 are laminated to the bleached hologram continuum 100 in a film laminating unit 25 and a liner laminating unit 26, respectively, and the resulting hologram continuum is then wound up in a winding unit 27.

[0050] If necessary, hologram continuum 100 may be divided into individual hologram rows, and then the rows may be individually wound up on winding section 27. For example, as shown in Figure 12(b), multi-row hologram continuum 100 may be divided into single-row hologram continuums 100 using slitter 290, and these may then be individually wound up. It is generally preferable that division by slitter 290 be performed after protective film 15 and release liner 16 have been bonded to each other.

[0051] {Uses of Holograms} Individual holograms can be obtained by cutting the hologram continuum 100 at appropriate locations. The uses of the produced holograms are not particularly limited. The produced holograms can be applied to various uses that are conventionally known or will become known in the future. Holograms can be used, for example, in optical-related products such as light guide plates; security-related products such as anti-counterfeit seals and authentication seals; and design-related products such as decorative items. A light guide plate according to one embodiment has a hologram produced using the above-described manufacturing apparatus and manufacturing method. For example, a light guide plate can be formed by sandwiching the produced hologram between two glass plates or transparent resin plates. Furthermore, a light guide plate for an AR device can also be produced using the hologram. An AR (Augmented Reality) device is a device, such as smart glasses, that can display text information and virtual content simultaneously with the real world. In such a device, light corresponding to text information or virtual content (light of red wavelength, light of green wavelength, and light of blue wavelength) is guided by a light guide plate to a position where light from the real world is received.

[0052] For example, the above-described manufacturing apparatus A (or manufacturing method) can also produce a duplicate hologram that includes a set of one rectangular hologram called an incoupling and one large rectangular hologram called an outcoupling. As shown in Fig. 13, a light guide plate G for an AR device can be constructed by stacking, in order, red hologram 310R consisting of incoupling 311R and outcoupling 312R, green hologram 310G consisting of incoupling 311G and outcoupling 312G, and blue hologram 310B consisting of incoupling 311B and outcoupling 312B, and then laminating glass plates or transparent resin plates on the front and back surfaces of the stack.

[0053] Second Embodiment In the first embodiment, the supply holes 5 are provided in the hologram master 3, but the supply holes 5 may be provided in the light-transmitting plate 41. In other words, the overlapping member in which the supply holes 5 are formed may be the light-transmitting plate 41.

[0054] {Hologram Manufacturing Apparatus of Second Embodiment} Fig. 14 is a side view of manufacturing apparatus A of this embodiment, Fig. 15 is a plan view of the exposure unit in the manufacturing apparatus as seen from above, and Fig. 16 is an enlarged cross-sectional view of the exposure unit cut along the transport direction. Note that the refractive index matching liquid supply device is omitted in Fig. 15. The manufacturing apparatus A of this embodiment differs in configuration from the first embodiment in that a light-transmitting plate 41 is arranged above the material to be processed 1 and a hologram master 3 is arranged below the material to be processed 1, and that supply holes 5 are provided in the light-transmitting plate 41.

[0055] Regarding the manufacturing apparatus A of this embodiment, we will explain the configuration and effects that differ from the manufacturing apparatus A of the first embodiment above, and for similar configurations, the terms or symbols may be used as is and the description of the configuration may be omitted (the same applies to the third embodiment and beyond).

[0056] The hologram master 3 is disposed below the material 1 to be processed. Therefore, the photosensitive layer 11 of the material 1 faces the hologram master 3. The hologram master 3 is held by a master mounting member. The hologram master 3 may be configured to be movable in the vertical direction, or may be fixed so that it cannot move. The light-transmitting plate 41 is disposed above the material 1 to be processed. The light-transmitting plate 41 can be moved up and down as shown by the two-dot chain line in FIG. 16 . Note that the plate mounting member for the light-transmitting plate 41 and the mechanism for moving the light-transmitting plate 41 up and down are not shown. When the light-transmitting plate 41 is lowered, the first surface of the light-transmitting plate 41 faces one surface (second surface) of the support substrate 12 of the material 1 to be processed, with a gap S between them. Furthermore, the coherent light L1 is irradiated from the light-transmitting plate 41 side (upper side). In FIG. 14, the light source that irradiates the coherent light L1 is not shown, and only the coherent light L1 is shown.

[0057] Supply holes 5 are provided within the surface of the light-transmitting plate 41. The supply holes 5 penetrate the light-transmitting plate 41 in the thickness direction. The supply holes 5 penetrate in the thickness direction and communicate with the gap S defined by the light-transmitting plate 41 and the material to be processed 1. The supply holes 5 are parallel to the thickness direction, but may also penetrate at an angle relative to the thickness direction. The gap S between the hologram master 3 and the material to be processed 1 can be filled with a refractive index matching liquid through the supply holes 5. The supply holes 5 are formed in an area excluding the area corresponding to the master hologram 31. In other words, the supply holes 5 are formed in an area of ​​the light-transmitting plate 41 that does not correspond to the master hologram 31. The dashed-dotted line in Figure 15 represents the outline of the master hologram 31 that exists when the light-transmitting plate 41, etc., is viewed from above. The master hologram 31 exists below the area surrounded by the dashed-dotted line. No supply holes 5 are formed in the area corresponding to the master hologram 31 (the area surrounded by the dashed-dotted line). If a supply hole 5 is formed in this region, when coherent light L1 is irradiated from the light-transmitting plate 41, the light L1 may be scattered, and the interference fringes of the master hologram 31 may not be accurately recorded in the photosensitive layer 11.

[0058] Furthermore, supply holes 5 are formed in regions that do not transmit coherent light for recording interference fringes on photosensitive layer 11. In the illustrated example, a plurality of supply holes 5 are formed at predetermined intervals in regions that do not correspond to master hologram 31 in the width direction and in regions that do not correspond to master hologram 31 in the length direction. The diameter of supply hole 5, the interval between adjacent supply holes 5, and the area of ​​light-transmitting plate 41 (overlapping member) per supply hole 5 are as described in the section (supply holes) of the first embodiment above.

[0059] {Method for manufacturing a hologram according to the second embodiment} In this embodiment, the overlapping member is a light-transmitting plate 41. Then, in the filling step, a refractive index matching liquid is filled into the gap through supply holes 5 formed in the light-transmitting plate 41.

[0060] The light-transmitting plate 41 is raised to separate it from the support substrate 12 of the material 1 to be processed, and the material 1 to be processed is transported downstream in the transport direction by a predetermined length by the transport section B, and the transport of the material 1 to be processed is stopped in the exposure section C. Next, the pressure roll 282 is moved to bring the photosensitive layer 11 of the material 1 into close contact with the hologram master 3.

[0061] <Placement step> Next, the light-transmitting plate 41 is lowered to approach one surface (first surface) of the support substrate 12 of the workpiece 1. That is, the light-transmitting plate 41, which is an overlapping member, is placed on one surface of the support substrate 12 of the workpiece 1 with a gap S therebetween (see FIG. 16 ).

[0062] <Filling Process> The opening / closing section 514 is opened, and the refractive index matching liquid in the tank 511 is supplied to the supply hole 5. The refractive index matching liquid supplied from the tube 512 flows into the gap S from the supply hole 5, as in the first embodiment. In this way, a laminate consisting of the light-transmitting plate 41 / refractive index matching liquid 7 / processing target 1 (support substrate 12+photosensitive layer 11) / hologram master 3, with no air interface between the layers, is temporarily formed in the exposure section C.

[0063] 14 , coherent light L1 is irradiated onto the master holograms 31 in the first row from the first surface side of the light-transmitting plate 41 of this laminate, thereby exposing the photosensitive layer 11. As in the first embodiment, this exposure allows duplicate holograms having interference fringes similar to those of the master holograms 31 to be produced in the photosensitive layer 11. Coherent light L1 is irradiated onto the master holograms 31 arranged in the second and third rows, thereby producing duplicate holograms in the photosensitive layer 11.

[0064] <Post-Process> Thereafter, the light-transmitting plate 41 is separated from the support substrate 12 of the object 1 to be treated, and the refractive index matching liquid adhering to the support substrate 12 is removed by the wiping part 281 .

[0065] <Repeated Process> The exposed material 1 is then transported downstream, the photosensitive layer 11 of the unexposed material 1 is brought into close contact with the hologram master 3, a light-transmitting plate 41 is placed on the support substrate 12 of the material 1 with a gap S therebetween, a refractive index matching liquid is filled into the gap S through the supply hole 5, exposure is performed to produce duplicate holograms in the photosensitive layer 11 corresponding to all of the master holograms 31, the light-transmitting plate 41 is released, the material 1 is transported a predetermined length, and the material is stopped. This process is repeated. Duplicate holograms can be produced continuously in this manner.

[0066] In the first and second embodiments, the hologram master 3 is used to replicate the interference fringes of the master hologram 31 onto the photosensitive layer 11. However, a hologram may be produced using a prism (without using the hologram master 3). In this case, the supply holes 5 are formed in the prism. That is, the overlapping member in which the supply holes 5 are formed may be a prism.

[0067] {Hologram Manufacturing Apparatus of Third Embodiment} Fig. 17 is a side view of manufacturing apparatus A of this embodiment, Fig. 18 is a plan view of the exposure unit in the manufacturing apparatus as seen from above, and Fig. 19 is an enlarged cross-sectional view of the exposure unit cut along the transport direction. Note that the refractive index matching liquid supply device is omitted in Fig. 18. The structural differences between the manufacturing apparatus of the first embodiment and this embodiment are that manufacturing apparatus A of this embodiment is provided with a prism 9 instead of a hologram master 3, and that supply holes 5 are provided in the prism 9.

[0068] As shown in FIG. 18 , the prism 9 extends in the width direction. The prism 9 may be slightly shorter than the material 1 to be treated in the width direction, as shown in the illustrated example, or may be equal to or longer than the material 1 to be treated in the width direction. The prism 9 has a refractive index approximately equal to that of the light-transmitting plate 41. At least one prism 9 is required. In the illustrated example, three prisms 9 are arranged in a line along the longitudinal direction of the material 1 to be treated. The material 1 to be treated is interposed between each prism 9 and the light-transmitting plate 41. Furthermore, the prism 9 is configured to be movable so that it can be moved toward or away from the material 1 to be treated, as indicated by the two-dot chain line in FIG. 19 . For example, the prism 9 is attached to a mounting member (not shown) equipped with a moving mechanism, and can be moved toward or away from the material 1 to be treated by driving the moving mechanism. When the prism 9 is lowered, the lower surface of the prism 9 faces one surface of the support substrate 12 of the material to be treated 1 with a gap S. The light source (not shown) is configured to be able to irradiate coherent light L1 from the first surface side of the light-transmitting plate and to irradiate coherent light L11 from the prism 9 side.

[0069] Supply holes 5 are provided within the surface of the prism 9. The supply holes 5 penetrate the prism 9 in the thickness direction. In the illustrated example, the thickness direction is approximately parallel to the normal direction. The supply holes 5, which penetrate in the thickness direction, communicate with the gap S defined by the prism 9 and the material to be treated 1. The supply holes 5 may also be formed at an angle with respect to the thickness direction. The gap S between the prism 9 and the material to be treated 1 can be filled with a refractive index matching liquid through the supply holes 5. The supply holes 5 are formed in a region of the prism 9 excluding the region through which the coherent light L11 irradiated from the prism 9 passes. In other words, the supply holes 5 are formed in a region of the prism 9 through which the coherent light L11 does not pass. The dashed-dotted line in FIG. 18 represents the region through which the coherent light L11 irradiated from the prism 9 passes. No supply holes 5 are formed in the region surrounded by the dashed-dotted line. If supply holes 5 are formed in this region, when coherent light L11 is irradiated through prism 9, the light may be scattered, making it difficult to accurately record interference fringes on photosensitive layer 11. The diameter of supply holes 5, the spacing between adjacent supply holes 5, and the area of ​​light-transmitting plate 41 (overlapping member) per supply hole 5 are as described in the section (supply holes) of the first embodiment above.

[0070] {Method for manufacturing a hologram according to the third embodiment} In this embodiment, the overlapping member is a prism 9. Then, in the filling step, a refractive index matching liquid is filled into the gap through the supply holes 5 formed in the prism 9.

[0071] The prism 9 is raised and separated from the support substrate 12 of the material 1 to be treated, and the material 1 to be treated is transported downstream in the transport direction by a predetermined length by the transport unit B, where it is stopped. Next, the pressure roll 282 is moved to bring the photosensitive layer 11 of the material 1 into close contact with the light-transmitting plate 41.

[0072] <Placement step> Next, the prism 9 is lowered to approach one surface of the support substrate 12 of the material to be treated 1. That is, the prism 9, which is an overlapping member, is placed on one surface of the support substrate 12 of the material to be treated 1 with a gap S therebetween (see FIG. 19 ).

[0073] <Filling Process> The opening / closing section 514 is opened, and the refractive index matching liquid in the tank 511 is supplied to the supply hole 5. The refractive index matching liquid 7 supplied from the tube 512 flows into the gap S from the supply hole 5, as in the first embodiment (see FIG. 20 ). In this way, a laminate consisting of the prism 9 / refractive index matching liquid 7 / material to be processed 1 (support substrate 12+photosensitive layer 11), with no air interface between the layers, is temporarily formed in the exposure section C.

[0074] 17 and 21, coherent light L1 is irradiated onto the workpiece 1 from the first surface side of the light-transmitting plate 41, and coherent light L11, which is irradiated from the prism 9 side in a direction different from that of the coherent light L1, is irradiated onto the workpiece 1. To suppress reflection and refraction, the coherent light L11 is irradiated onto the workpiece 1 through the prism 9. The coherent light L1 and the coherent light L11 travel in different directions but are light of the same wavelength (e.g., laser light of the same wavelength). For example, light emitted from a laser oscillator of a predetermined wavelength is split by a polarizing beam splitter, the polarization axis of one of the split light beams is rotated by a half-wave plate to match the polarization axis of the other light beam, and the light is magnified and flattened by a magnifying lens and a collimating lens, respectively, and then each of the split light beams is appropriately reflected by a mirror. This allows coherent light beams L1 and L11 of the same wavelength to be irradiated onto the photosensitive layer 11 of the workpiece 1 from different directions. As shown in Figure 21, the photosensitive layer 11 is exposed to the coherent light beams L1 and L11 irradiated from the two directions, and interference fringes are recorded. In other words, a hologram 311 is formed in the photosensitive layer 11. The three prisms 9 are similarly irradiated with the coherent light beam L11, and corresponding holograms 311 are formed in the photosensitive layer 11.

[0075] <Post-Process> Thereafter, the prism 9 is separated from the support substrate 12 of the object 1 to be treated, and the refractive index matching liquid adhering to the support substrate 12 is removed by the wiping unit 281 .

[0076] <Repeated Process> Thereafter, the exposed material 1 is transported, the photosensitive layer 11 of the material 1 is brought into close contact with the light-transmitting plate 41, the prism 9 is placed on the support substrate 12 of the material 1 with a gap S therebetween, the gap S is filled with a refractive index matching liquid through the supply hole 5, coherent light L1 and L11 is irradiated from two directions to create a hologram in the photosensitive layer 11, the prism 9 is released, the material 1 is transported a predetermined length, and the material 1 is stopped. These steps are repeated in this manner. Holograms can be continuously created in the photosensitive layer 11.

[0077] [Fourth Embodiment] In the above embodiments, the case where the refractive index matching liquid is supplied to the supply hole 5 from above has been exemplified, but this is not limiting. For example, the refractive index matching liquid may be supplied to the supply hole 5 from below. In this case, it may be difficult to fill the gaps due to the weight of the refractive index matching liquid, so it is preferable to supply the refractive index matching liquid under pressure. Furthermore, when the refractive index matching liquid is supplied from below, for example, the hologram master 3 having the supply hole 5 of the first embodiment may be disposed below the processed material 1 (in this case, the light-transmitting plate 41 is disposed above the processed material 1). Similarly, when the refractive index matching liquid is supplied from below, for example, the light-transmitting plate 41 having the supply hole 5 of the second embodiment may be disposed below the processed material 1, or the prism 9 having the supply hole 5 of the third embodiment may be disposed below the processed material 1.

[0078] A Hologram manufacturing apparatus B Conveying section of manufacturing apparatus C Exposure section of manufacturing apparatus D Light source of manufacturing apparatus S Gap between overlapping member and processed material 1 Processed material 11 Photosensitive layer 12 Supporting substrate 3 Hologram master (overlapping member) 31 Master hologram 41 Light-transmitting plate (overlapping member) 5 Supply hole 7 Refractive index matching liquid 9 Prism (overlapping member)

Claims

1. A method for manufacturing a hologram, comprising: a placement step of placing an overlapping member with a gap on one side of a processed material having an unexposed photosensitive layer; a filling step of filling the gap between the processed material and the overlapping member with a refractive index matching liquid; and an exposure step of recording interference fringes in the photosensitive layer by irradiating the photosensitive layer with coherent light after filling the refractive index matching liquid, wherein a supply hole leading to the gap is formed in the overlapping member, and the refractive index matching liquid is filled into the gap through the supply hole.

2. The method for producing a hologram according to claim 1, wherein the supply holes are formed in an area of ​​the overlapping member through which coherent light for recording interference fringes on the photosensitive layer does not propagate.

3. The method for producing a hologram according to claim 1, wherein the diameter of the supply hole is 0.5 mm to 10 mm.

4. The method for producing a hologram according to claim 1, wherein a plurality of the supply holes are formed at intervals.

5. The method for producing a hologram according to claim 4, wherein the interval between adjacent supply holes is 20 mm to 150 mm.

6. The method for manufacturing a hologram according to claim 1, wherein the material to be processed has a supporting substrate and the photosensitive layer provided on the supporting substrate, and in the positioning step, the overlapping member is positioned on one side of the supporting substrate of the material to be processed with the gap therebetween.

7. The method for producing a hologram according to claim 1, wherein the overlapping member is a hologram master having a master hologram.

8. The method for producing a hologram according to claim 1, wherein the overlapping member is a light-transmitting plate.

9. The method for producing a hologram according to claim 1, wherein the overlapping member is a prism.

10. A light guide plate having a hologram manufactured by the manufacturing method according to any one of claims 1 to 9.

11. A hologram master plate used when replicating a hologram, comprising an area in which a master hologram is formed and an area in which the master hologram is not formed, and a supply hole for supplying a refractive index matching liquid is formed in the area in which the master hologram is not formed, penetrating the thickness direction.

Images