Hologram manufacturing device, hologram manufacturing method, light guide plate, and translucent plate

Abstract

To replicate a hologram having the same interference fringe as that of a master hologram in a photosensitive layer.SOLUTION: A device comprises: an exposure portion C that includes a master layer 3 having master holograms 31 and a translucent plate 41 that is disposed on a first surface side of the master layer 3; and a light source D that irradiates the master hologram 31 with coherent light from a first surface side of the translucent plate. The device interposes an unexposed photosensitive layer 11 between a first surface of the master layer 3 and a second surface of the translucent plate, and exposes the photosensitive layer 11 by transmitting the coherent light and diffracted light generated from the master hologram 31 by the irradiation with the coherent light, to replicate the master hologram 31 at the photosensitive layer 11. A light-absorbing layer 53 that absorbs the diffracted light is provided at a region of a first surface of the translucent plate 41, the region being other than a region to which the coherent light is made incident.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a hologram manufacturing apparatus and a manufacturing method thereof. [Background technology]

[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 master hologram and optically replicate the interference fringes of the master hologram onto a photosensitive layer (Patent Document 1). Briefly, as shown in FIG. 20, a laminate including a master layer containing a master hologram, an unexposed photosensitive layer adhered to the master layer, and a glass plate adhered to the photosensitive layer is irradiated with laser light from the glass plate side. The laser light passes through the glass plate and the photosensitive layer and is incident on the master hologram, generating diffracted light in the master hologram, which then passes through the photosensitive layer. The laser light and the diffracted light interfere with each other to expose the photosensitive layer, thereby recording interference fringes of the master hologram in the photosensitive layer. In this way, the master hologram can be replicated on the photosensitive layer. In other words, a hologram similar to the master hologram can be created in the photosensitive layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-538580 Summary of the Invention

[0004] However, in the case of duplication using a conventional master hologram, there is a risk that interference fringes similar to those of the master hologram may not be recorded in the photosensitive layer, which means that it may not be possible to duplicate a hologram having interference fringes similar to those of the master hologram. [Problem to be solved by the invention]

[0005] The primary objective of the present invention is to replicate a hologram having interference fringes similar to those of the master hologram. [Means for solving the problem]

[0006] The inventors of the present invention have conducted extensive research into the above-mentioned problems. Specifically, as shown in FIG. 20, laser light incident from the glass plate side passes through the photosensitive layer and enters the master hologram. Diffracted light is then generated in the master hologram, and the diffracted light passes through the photosensitive layer. The laser light and diffracted light pass through the photosensitive layer from two directions, exposing the photosensitive layer to light, forming a replicated hologram in that area. However, the diffracted light that passes through the photosensitive layer may be internally reflected at the air interface of the glass plate (the bottom surface in the illustrated example), and the reflected light (reflected diffracted light) may pass through the replicated hologram again. If the reflected light passes through again, the interference fringes of the replicated hologram are disrupted, making it impossible to produce a replicated hologram with interference fringes similar to those of the master hologram. Furthermore, when multiple master holograms are lined up, the diffracted light that passes through the photosensitive layer to form one duplicate hologram may be reflected at the air interface, and this reflected light may pass through the adjacent duplicate hologram, disrupting the interference fringes of the adjacent duplicate hologram. By providing a light-absorbing layer that absorbs the diffracted light so that the reflected light of this diffracted light does not re-enter the duplicate hologram, it is possible to duplicate a hologram having interference fringes similar to those of the master hologram. Furthermore, the phenomenon of internal reflection at the air interface of the glass plate is not limited to when a master hologram is used to replicate a hologram, but is also thought to occur when a hologram is produced without using a master hologram. Based on this knowledge, the present inventors provide the following several means.

[0007] In one aspect, an apparatus for producing a hologram is provided. A first form of hologram manufacturing apparatus includes an exposure unit having a master layer containing a master hologram and a light-transmitting plate arranged on the first surface side of the master layer, and a light source that irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate.The apparatus interposes an unexposed photosensitive layer between the first surface of the master layer and the second surface of the light-transmitting plate, and exposes the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiating it with the coherent light.In this apparatus, a light-absorbing layer that absorbs the diffracted light is provided on the first surface of the light-transmitting plate in an area other than the area where the coherent light is incident.

[0008] A second embodiment of the hologram manufacturing apparatus is the same as the first embodiment, except that at least two master holograms are arranged side by side on the master layer. A third embodiment of the hologram manufacturing apparatus is the manufacturing apparatus of the first or second embodiment, wherein the light absorption layer is provided on at least a first surface of the light-transmitting plate on the side where the diffracted light travels.

[0009] A fourth embodiment of the hologram manufacturing apparatus includes an exposure unit having a master layer containing a master hologram and a light-transmitting plate arranged on the first surface side of the master layer, and a light source that irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate. The apparatus interposes an unexposed photosensitive layer between the first surface of the master layer and the second surface of the light-transmitting plate, and exposes the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiating the coherent light through the photosensitive layer, thereby replicating the master hologram on the photosensitive layer. In this apparatus, a light-absorbing layer that absorbs the diffracted light is provided on at least one of the end surfaces of the light-transmitting plate on the side where the diffracted light travels.

[0010] A fifth embodiment of the hologram manufacturing apparatus is the manufacturing apparatus of the fourth embodiment, except that at least two master holograms are arranged side by side on the master layer, the light-transmitting plate has a first light-transmitting plate corresponding to at least one master hologram and a second light-transmitting plate corresponding to another at least one master hologram, and the light-absorbing layer is provided on at least the end face of the first light-transmitting plate and the second light-transmitting plate on the traveling side of the diffracted light. A hologram manufacturing apparatus of a sixth aspect is the manufacturing apparatus of the fifth aspect, wherein the light absorbing layer is provided on all end faces of the first light-transmitting plate and the second light-transmitting plate. The seventh form of the hologram manufacturing apparatus is any one of the first to sixth manufacturing apparatuses, in which the relationship h>d / tanθ is satisfied, where h is the thickness of the light-transmitting plate, d is the dimension at the incident position of the coherent light, and θ is the diffraction angle of the diffracted light.

[0011] In another aspect, a method for producing a hologram is provided. An eighth embodiment of the method for manufacturing a hologram includes a laminate having a master layer containing a master hologram, an unexposed photosensitive layer arranged on a first surface side of the master layer, and a light-transmitting plate arranged on the first surface side of the photosensitive layer, and the laminate irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate, and exposes the master hologram by transmitting the coherent light and diffracted light generated from the master hologram by the irradiation of the coherent light through the photosensitive layer, thereby replicating the master hologram in the photosensitive layer. In this method, a light-absorbing layer that absorbs the diffracted light is provided on the first surface of the light-transmitting plate in an area other than the area where the coherent light is incident.

[0012] A ninth embodiment of the method for manufacturing a hologram includes a laminate having a master layer containing a master hologram, an unexposed photosensitive layer arranged on a first surface side of the master layer, and a light-transmitting plate arranged on the first surface side of the photosensitive layer, and the laminate irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate, and exposes the master hologram by transmitting the coherent light and diffracted light generated from the master hologram by the irradiation of the coherent light through the photosensitive layer, thereby replicating the master hologram in the photosensitive layer. In this method, a light-absorbing layer that absorbs the diffracted light is provided on at least one of the end surfaces of the light-transmitting plate, the end surface on which the diffracted light travels.

[0013] A tenth embodiment of the method for manufacturing a hologram comprises placing a light-transmitting plate on a first surface side of an unexposed photosensitive layer, irradiating the photosensitive layer with first coherent light from the first surface side of the light-transmitting plate and irradiating the photosensitive layer with second coherent light from a direction different from the first coherent light from a second surface side of the photosensitive layer, and exposing the photosensitive layer to the coherent light irradiation from the two directions, thereby producing a hologram in the photosensitive layer, and a light-absorbing layer that absorbs the second coherent light is provided on the first surface of the light-transmitting plate in an area other than the area where the first coherent light is incident. A hologram manufacturing method of an eleventh aspect is a manufacturing method in which a light-transmitting plate is placed on a first surface side of an unexposed photosensitive layer, a first coherent light is irradiated from the first surface side of the light-transmitting plate, and a second coherent light is irradiated from a second surface side of the photosensitive layer in a direction different from that of the first coherent light, thereby exposing the photosensitive layer by irradiating it with coherent light from the two directions, thereby producing a hologram in the photosensitive layer, and in which a light-absorbing layer that absorbs the second coherent light is provided on at least one of the end surfaces of the light-transmitting plate, the end surface on the side where the second coherent light travels. [Effects of the Invention]

[0014] According to one embodiment of the manufacturing apparatus and manufacturing method of the present invention, it is possible to replicate a hologram having interference fringes similar to those of a master hologram. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a side view of the hologram manufacturing apparatus according to the first embodiment. [Figure 2] FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. 2. [Figure 4] A bottom view of the master layer, seen from the first side. [Figure 5] FIG. 2 is a bottom view of the light-transmitting plate, seen from below. [Figure 6] FIG. 4 is a perspective view of a first light-transmitting plate of the light-transmitting plate, viewed from below. [Figure 7] FIG. 10 is a reference side view of the exposure unit, showing one mode in which reflected light of diffracted light is unlikely to be incident on a replica hologram. [Figure 8] FIG. 10 is a reference side view of the exposure section, showing another aspect in which reflected light of diffracted light is less likely to enter the duplicate hologram. [Figure 9] A reference diagram showing how to create a master hologram. [Figure 10] FIG. 2 is a side view of a manufacturing apparatus for explaining steps in a method for manufacturing a hologram. [Figure 11] A plan view of a replica hologram continuum in which holograms are produced successively. [Figure 12] FIG. 10 is a reference side view of a light guide plate on which a red duplicate hologram, a green duplicate hologram, and a blue duplicate hologram are stacked. [Figure 13] FIG. 10 is a reference side view of an exposure unit according to a first example of the second embodiment. [Figure 14] FIG. 10 is a reference side view of an exposure unit according to a second example of the second embodiment. [Figure 15] FIG. 10 is a cross-sectional view of an exposure unit according to a third embodiment. [Figure 16] 10A is a reference side view of an exposure unit according to a first example of the fourth embodiment, and FIG. 10B is a reference side view of an exposure unit according to a second example of the fourth embodiment. [Figure 17] FIG. 13 is a plan view of an exposure unit of a manufacturing apparatus according to a fifth embodiment. [Figure 18]FIG. 18 is an enlarged cross-sectional view taken along line XVIII-XVIII in FIG. 17. [Figure 19] FIG. 13 is a reference side view for explaining a method for manufacturing a hologram according to the fifth embodiment. [Figure 20] A reference diagram showing a conventional method for creating holograms. DETAILED DESCRIPTION OF THE INVENTION

[0016] [First embodiment] One embodiment will be described below with reference to the drawings. In this specification, the "first surface" of a certain member (e.g., a master layer 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 member refers to the surface opposite to the first surface. It should be noted that the thickness, size, scale, and shape of elements such as layers shown in each drawing may differ from the actual ones.

[0017] {Hologram manufacturing equipment} FIG. 1 is a side view of a hologram manufacturing apparatus according to a first embodiment, FIG. 2 is a plan view of an exposure section in the manufacturing apparatus as seen from above, and FIG. 3 is an enlarged cross-sectional view of the exposure section cut along the conveying direction. In this specification, the "conveying direction" corresponds to the longitudinal direction of the material to be treated, and the "width direction" refers to the direction perpendicular to the longitudinal direction within the surface of the material to be treated.

[0018] The hologram manufacturing apparatus exposes a photosensitive layer to coherent light and diffracted light generated from a master hologram by irradiation with the coherent light, thereby recording interference fringes of the master hologram in the photosensitive layer and replicating the hologram in the photosensitive layer. In this specification, the hologram replicated in the photosensitive layer may be referred to as a "replica hologram." The photosensitive layer applied to the manufacturing apparatus may be in the form of a sheet, but is preferably in the form of a long strip. By loading a long strip of 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 is a strip whose longitudinal length is sufficiently longer than its lateral length. The long strip of photosensitive layer is usually stored wound up 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.

[0019] 1 to 3, the manufacturing apparatus A has a transport section B that transports the 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 a laminate including the photosensitive layer 11 with coherent light L1 in the exposure section C. Various operations of the manufacturing apparatus A, which will be described later, are controlled by a control section (not shown) that includes a computer or the like. The general flow for producing a duplicate hologram is to transport the photosensitive layer 11 to the exposure section C, expose the photosensitive layer 11 to light in the exposure section C to form a duplicate hologram, and then transport the photosensitive layer 11 again, repeating this process to continuously produce multiple duplicate holograms.

[0020] <Material to be processed including a photosensitive layer> 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 photosensitive layer 11 typically has a thickness of several μm to 20 μm, and therefore is often not strong enough 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. 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, and examples of suitable materials include glass, TAC (triacetyl cellulose), and resins such as polycarbonate. The thickness of the support substrate 12 is not particularly limited and is approximately 10 μm to 100 μm. Hereinafter, a material consisting of the support substrate 12 and the photosensitive layer 11 formed solidly on one surface of the support substrate 12 will be referred to as the "processed material 1."

[0021] The long strip-shaped material to be treated 1 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 to be treated 1 to prevent scratches on the support substrate 12 and photosensitive layer 11. For example, a protective film 15 with an adhesive is attached to the support substrate 12 side of the material to be treated 1. In addition, a release liner 16 is attached to the photosensitive layer 11 side of the material to be treated 1. The release liner 16 is attached for two purposes. One is to protect the photosensitive layer 11. The other is to conceal the slight adhesiveness of the photosensitive layer 11, which has slight adhesiveness, and prevent blocking when the material is wound into a roll. In this way, the laminated film consisting of adhesive-attached protective film 15 / processing target 1 (support substrate 12+photosensitive layer 11) / release liner 16 is wound onto a roll and loaded into the unwinding section of manufacturing device A.

[0022] <Transportation section> The conveying section B unwinds the laminated film including the material 1 to be treated that is wound around a roll, and conveys the unwound laminated film including the material 1 to be treated in its longitudinal direction. Specifically, conveying section B has an unwinding section 21 that loads the laminated film wound around a roll, a film peeling section 22 that peels the protective film 15 together with the adhesive from the laminated film and takes it up, a liner peeling section 23 that peels the release liner 16 from the laminated film and takes it up, accumulation mechanisms 241, 242 that allow the intermittently conveyed material 1 to accumulate and thereby enable continuous unwinding and take-up of the material 1, a film laminating section 25 that bonds the adhesive-attached protective film 15 to the exposed material 1, a liner laminating section 26 that bonds the release liner 16 to the exposed material 1, and a take-up section 27 that winds up the material 1 to which the protective film 15 and release liner 16 have been bonded. 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 the unwinding section 21 and the exposure section C, and a second accumulation mechanism 242 is provided between the exposure section C and the winding section 27.

[0023] Conveying section B unwinds the laminated film containing the material 1 from unwinding section 21 at a predetermined speed and conveys it longitudinally. Upstream of first accumulation mechanism 241, film peeling section 22 and liner peeling section 23 peel the adhesive-backed protective film 15 and release liner 16 from the laminated film. Conveying section B conveys the material 1 revealed by peeling off the protective film 15 and release liner 16 to exposure section C, where it temporarily stops conveying. As described below, after the exposure process for material 1 is completed in exposure section C, conveying section B conveys material 1 a predetermined length downstream in the conveying direction and then stops again. By repeating this intermittent conveying process—conveying material 1, stopping conveying, exposing, and then conveying material 1 again—multiple replica holograms can be continuously produced in the long strip-shaped photosensitive layer 11.

[0024] After the exposure process is completed, the film laminating section 25 and the liner laminating section 26 laminate another adhesive-backed protective film 15 and release liner 16 onto the treated material 1, and the winding section 27 winds up the treated material 1 to which the protective film 15 and release liner 16 have been attached at a predetermined speed. The first accumulation mechanism 241 temporarily stores the material 1 to be treated that is being unwound from the unwinding section 21 while the transport of the material 1 to be treated is stopped at the exposure section C, and on the other hand, when the material 1 to be treated that was stopped at the exposure section C starts to be transported again, it releases the stored material 1 to be treated. The second accumulation mechanism 242 releases the material 1 to be treated that is being wound up on the winding section 27 while the transport of the material to be treated 1 to be treated is stopped at the exposure section C, and on the other hand, it temporarily stores the material 1 to be treated that was stopped at the exposure section C when it starts to be transported again. In the example of FIG. 1, the first accumulation mechanism 241 and the second accumulation mechanism 242 are accumulation rolls that move up and down. It is also possible to configure a production line in which either the first accumulation mechanism 241 or the second accumulation mechanism 242 is not provided.

[0025] <Light source> In the exposure section C, the light source D irradiates the laminate including the photosensitive layer 11 with coherent light L1. Laser light is typically used as the coherent light. There are no particular limitations on the wavelength of the laser light, 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.

[0026] 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 causes the laser light to travel 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 optical devices include a shutter, a beam expander, a half-wave plate, a dielectric multilayer mirror, and a beam splitter, and these 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 laser light of a red wavelength (referred to as red laser light), a green laser oscillator that emits laser light of a green wavelength (referred to as green laser light), and a blue laser oscillator that emits laser light of a blue wavelength (referred to as blue laser light). For example, a 640 nm laser oscillator manufactured by Cobolt (product name "Cobolt 05-01 Series Bolero") can be used as the red laser oscillator. A 532 nm laser oscillator manufactured by Cobolt (product name "Cobolt 05-01 Series Samba") can be used as the green laser oscillator. A 460 nm laser oscillator manufactured by Coherent (product name "Genesis MX460") can be used as the blue laser oscillator.

[0027] As will be described later, the master layer is provided with 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 simultaneously or sequentially irradiate the remaining several master holograms with laser light by moving the multiple mirrors. In the example shown in FIG. 1, a plurality of mirrors 64 are arranged side by side in the width direction, and the plurality of mirrors 64 can move in the longitudinal direction of the material 1 to be processed either independently or simultaneously.

[0028] <Exposure section> The exposure section C is one part of the manufacturing apparatus A where the photosensitive layer 11 is exposed to light. The exposure unit C has a master layer 3 including a master hologram 31, a master mounting member 38 for mounting the master layer 3, light-transmitting plates 41, 42, and 43 arranged on the first surface side of the master layer 3, and a plate mounting member 48 for mounting the light-transmitting plates 41, 42, and 43. A material to be processed 1 including a photosensitive layer 11 is interposed between the first surface of the master layer 3 and the second surfaces of the light-transmitting plates 41, 42, and 43.

[0029] (Master layer and master mounting member) Fig. 4 is a bottom view of the master layer 3 as viewed from the first surface side. In other words, Fig. 4 is a view of the master layer 3 (excluding the light-transmitting plate and the material to be processed 1) as viewed from the direction of the white arrow in Fig. 3. Note that since the master hologram 31 is sandwiched between the first substrate 32 and the second substrate 33, it does not appear on the surface when viewed from the first surface side, but for convenience, the master hologram 31 is also represented by a solid line in Fig. 4.

[0030] 1 to 4, the master layer 3 has at least one master hologram 31, and preferably has multiple master holograms 31. For example, the master layer 3 has a first substrate 32, a second substrate 33, and multiple master holograms 31 interposed between the first substrate 32 and the second substrate 33. The multiple master holograms 31 are arranged at predetermined intervals along the surface of the master layer 3. In the illustrated example, a total of nine master holograms 31 (3 × 3) are provided on the master layer 3. Specifically, the master holograms 31 are arranged in three rows in the transport direction of the material 1 to be processed and three columns in the width direction of the material 1 to be processed, with intervals 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). Therefore, in the illustrated example, three master holograms are arranged in each of the first row S-1, second row S-2, and third row S-3, and three master holograms are arranged in each of the first column R-1, second column R-2, and third column R-3. However, the number and arrangement of master holograms 31 provided on the master layer 3 are not limited to the 3 rows x 3 columns and can be changed as appropriate. The first and second substrates 32, 33 are not particularly limited as long as they are base materials having a refractive index substantially equal to that of the light-transmitting plate, and for example, glass, TAC (triacetyl cellulose), polycarbonate or other resins may be used.

[0031] Here, a method for producing a master layer containing a master hologram will be briefly described. The master hologram can be produced by a conventionally known method. FIG. 9 is a reference diagram that schematically shows how a master hologram is produced. As shown in FIG. 1(a), a photosensitive layer 1100 made of a photosensitive material is prepared. Examples of the photosensitive material that can be used include photopolymer, photoresist, silver halide emulsion, and dichromated gelatin. In the illustrated example, the photosensitive layer 1100 is interposed between the first and second substrates 3200 and 3300. However, in manufacturing the master hologram, only the photosensitive layer 1100 may be used, or the photosensitive layer 1100 may be provided on the first substrate 3200. Next, a master hologram is produced by irradiating photosensitive layer 1100 with light IL of a predetermined wavelength from two different directions: a direction that forms an angle α with respect to the XY plane (hereinafter referred to as the "α direction") and a direction that forms an angle β with respect to the XY plane (hereinafter referred to as the "β direction"). Specifically, by irradiating photosensitive layer 1100 with interference light of laser light of a predetermined wavelength from two directions, the monomer component in the irradiated portion of photosensitive layer 1100 is diffused, resulting in a refractive index distribution. As a result, interference fringes are recorded in the irradiated portion, resulting in master hologram 3100. To maintain coherence, the light IL of the predetermined wavelength is preferably produced by splitting light emitted from a laser oscillator of the predetermined wavelength using a polarizing beam splitter, rotating the polarization axis of one of the split light beams using a half-wave plate to match the polarization axis of the other light, and then magnifying and flattening the light using a magnifying lens and a collimating lens, respectively, before being irradiated from two directions.

[0032] As shown in Figure 1(b), master hologram 3100 manufactured as described above is irradiated with laser light M1 of a predetermined wavelength from one direction (β direction) of the two directions (α direction, β direction) in which laser light of the predetermined wavelength was irradiated when master hologram 3100 was manufactured. In other words, laser light M1, which is reproduction light, is irradiated at an angle at which master hologram 3100 is reproduced. The light is then diffracted in the other direction (α direction) (diffracted light M2). When red laser light is irradiated, a red master hologram is generated, when green laser light is irradiated, a green master hologram is generated, and when blue laser light is irradiated, a blue master hologram is generated.

[0033] Returning to FIG. 3 , a light-absorbing layer 35 is provided on the second surface of the master layer 3. Hereinafter, to distinguish it from a light-absorbing layer provided on a light-transmitting plate, the light-absorbing layer 35 provided on the master layer 3 will be referred to as the "master light-absorbing layer 35." The master light-absorbing layer 35 is laminated at least in an area of ​​the second surface of the master layer 3 that corresponds to the master hologram 31. In the illustrated example, the master light-absorbing layer 35 is laminated over substantially the entire second surface of the master layer 3. Note that when the master layer 3 is composed of only the master hologram 31, or when the master layer 3 is composed of the master hologram 31 and the first substrate 32, the master light-absorbing layer 35 may be laminated at least on the second surface of the master hologram 31. The master light absorbing layer 35 is provided to absorb the light that has passed through the master hologram 31 when part of the coherent light has passed through the master hologram 31 .

[0034] The material for forming the master light-absorbing layer 35 is not particularly limited, provided that it contains an absorbent capable of absorbing the coherent light. Examples of the absorbent include black colorants such as carbon black, organic dyes, pigments primarily composed of metal oxides, inorganic substances such as metal particles, and other organic substances. Since the light that the absorbent can absorb usually depends on the wavelength of the light, the absorbent is selected taking into consideration the wavelength of the coherent light. For example, as described below, when red laser light, green laser light, and blue laser light are selectively used as coherent light during exposure, the light-absorbing layer is formed from a material containing an absorber that can absorb all of these laser lights in the visible light region. A typical example of such an absorber is a black colorant. Alternatively, a mixed absorber may be used, which is a mixture of a first absorber that absorbs light with a wavelength of 600 nm to 900 nm, a second absorber that absorbs light with a wavelength of 450 nm to 750 nm, and a third absorber that absorbs light with a wavelength of 300 nm to 550 nm. The master light-absorbing layer 35 can be formed by applying a forming material containing an absorbent such as the black colorant, a suitable binder resin, and any additives to the second surface of the master layer 3. The thickness of the master light-absorbing layer 35 is not particularly limited, and is, for example, several μm to 100 μm.

[0035] The master layer 3 is attached to a master mounting member 38. The master mounting member 38 includes a holder 381 that holds the master layer 3 and a movement mechanism 382 that moves the holder 381. The movement mechanism 382 moves the holder 381 holding the master layer 3 to move the master layer 3 closer to or farther from the workpiece 1. In the example shown in FIG. 1, the workpiece 1 is transported substantially horizontally in the exposure section C, so the movement mechanism 382 moves the master layer 3 up and down. As shown by the two-dot chain line in FIG. 3, the movement mechanism 382 moves the holder 381 holding the master layer 3 upward, thereby moving the master layer 3 away from the workpiece 1. Furthermore, the movement mechanism 382 moves the holder 381 downward, thereby bringing the master layer 3 into substantial contact with the workpiece 1. The movement mechanism 382 can be a conventional actuator, such as a pneumatic cylinder or a rack-and-pinion. The movement mechanism 382 may be configured to be able to move the master layer 3 a predetermined amount in the width direction and / or the transport direction.

[0036] (transparent plate) Fig. 5 is a bottom view of the light-transmitting plates 41, 42, and 43 as viewed from the first surface side. In other words, Fig. 5 is a view of the light-transmitting plates 41, 42, and 43 (excluding the material to be processed 1 and the master layer 3) as viewed from the direction of the white arrow in Fig. 3. 1 to 3 and 5, the light-transmitting plates 41, 42, and 43 are members that support the material to be treated 1, and the material to be treated 1 is interposed between the light-transmitting plates 41, 42, and 43 and the master layer 3. The light-transmitting plates are arranged on the first surface side of the master layer 3. In order to interpose the material to be treated 1 between the light-transmitting plates 41, 42, and 43 and the master layer 3, the light-transmitting plates 41, 42, and 43 are not in close contact with the first surface of the master layer 3, but are arranged on the first surface side of the master layer 3 with a gap therebetween.

[0037] 3, light-transmitting plates 41, 42, and 43 are provided corresponding to at least the master hologram 31. For example, if the master layer 3 includes a plurality of master holograms 31, one light-transmitting plate may be disposed on the first surface side of the master layer 3 corresponding to all of the master holograms 31, or one light-transmitting plate 41 may be disposed corresponding to at least one master hologram 31, and another light-transmitting plate 42 may be disposed corresponding to at least another master hologram 31. In the latter case, a plurality of separate light-transmitting plates are used. In the illustrated example, light-transmitting plates 41, 42, and 43 are arranged corresponding to each row of the master hologram 31. Specifically, as described above, the master layer 3 has 3 rows and 3 columns of master holograms 31 arranged thereon, and thus three light-transmitting plates 41, 42, and 43 are arranged corresponding to the three rows. Hereinafter, the three light-transmitting plates 41, 42, and 43 will be referred to as the "first light-transmitting plate 41," the "second light-transmitting plate 42," and the "third light-transmitting plate 43," respectively. Referring to FIG. 1 , the first light-transmitting plate 41 is located downstream in the transport direction, the second light-transmitting plate 42 is located closer to the unwinding section 21, and the third light-transmitting plate 43 is located closer to the unwinding section 21. Therefore, the first light-transmitting plate 41 and the second light-transmitting plate 42, and the second light-transmitting plate 42 and the third light-transmitting plate 43 are adjacent to each other in the transport direction.

[0038] The first light-transmitting plate 41 is disposed on the first surface side of the master layer 3 in correspondence with the three master holograms 31 arranged in the first row S-1. The second light-transmitting plate 42 is disposed on the first surface side of the master layer 3 in correspondence with the three master holograms 31 arranged in the second row S-2. The third light-transmitting plate 43 is disposed on the first surface side of the master layer 3 in correspondence with the three master holograms 31 arranged in the third row S-3. The first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43 are all made of strip-shaped light-transmitting plates extending in the width direction.

[0039] The first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43 may be the same shape and size, or may be the same shape but different sizes, or may be different shapes but different sizes. In the illustrated example, the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43 are the same shape and size to simplify the equipment. Hereinafter, since the second light-transmitting plate 42 and the third light-transmitting plate 43 have the same configuration as the first light-transmitting plate 41, the configuration of the first light-transmitting plate 41 will be described in detail, and a detailed description of the second light-transmitting plate 42 and the third light-transmitting plate 43 will be omitted. Regarding the second light-transmitting plate 42 and the third light-transmitting plate 43, the terms "first light-transmitting plate 41" and "first row S-1" in the following section on specific examples of the first light-transmitting plate 41 should be read as "second light-transmitting plate 42" and "second row S-2" or "third light-transmitting plate 43" and "third row S-3."

[0040] Specific examples of the first light-transmitting plate 41 Fig. 6 is a perspective view of the first light-transmitting plate 41. Note that in Fig. 6, the first surface of the first light-transmitting plate 41 faces upward on the paper. 3, 5, and 6, the first light-transmitting plate 41 is formed in the shape of a rectangular parallelepiped with its longitudinal axis in the width direction. The first light-transmitting plate 41 extends in the width direction so as to overlap the three master holograms 31 arranged in the first row S-1 and their surrounding areas in a planar perspective view. The dimensions of the first light-transmitting plate 41 are equal to or larger than the dimensions of the master holograms 31, and preferably larger than the dimensions of the master holograms 31. In this specification, the "dimension" of an object such as a light-transmitting plate refers to the length of the object in a side view (the length in the conveying direction). "Side view" refers to viewing the object from one side to the opposite side in the width direction. The thickness of the first light-transmitting plate 41 is set appropriately, but in order to minimize reflection of diffracted light, it is preferable that the thickness of the first light-transmitting plate 41 is relatively large. For example, the thickness of the first light-transmitting plate 41 is 10 mm to 50 mm, and preferably 25 mm to 45 mm. The first light-transmitting plate 41 is made of a material that transmits coherent light. For example, the first light-transmitting plate 41 (light-transmitting plate) is made of a material with a refractive index of about 1.5. Examples of materials with a refractive index of about 1.5 include glass, TAC (triacetyl cellulose), polycarbonate, and other resins. Examples of the glass include alkali-free glass, low-alkali glass, borosilicate glass, and soda-lime glass.

[0041] The first light-transmitting plate 41 is provided with light-absorbing layers 51 and 53. The light-absorbing layers 51 and 53 are provided to absorb diffracted light. The diffracted light is light that is diffracted when coherent light enters the master hologram 31. In this embodiment, the light-absorbing layers 51 and 53 are provided on the end faces and the first surface of the first light-transmitting plate 41. The end faces are also called thickness surfaces or side surfaces and refer to surfaces of the first light-transmitting plate 41 other than the first and second surfaces. The rectangular parallelepiped first light-transmitting plate 41 has four end faces. The light-absorbing layer 51 may be provided in a solid state on all end faces, or may be provided in a solid state on at least the end face on the side where the diffracted light travels. In the illustrated example, the light-absorbing layer 51 is provided on all end faces of the first light-transmitting plate 41.

[0042] Furthermore, a light-absorbing layer 53 is also provided on the first surface of the first light-transmitting plate 41. However, in order to allow coherent light to be incident on the master hologram 31 from the first surface side of the first light-transmitting plate 41, the light-absorbing layer 53 is provided on the first surface of the first light-transmitting plate 41 in an area other than the area where coherent light is incident on the master hologram 31. Hereinafter, the "area where coherent light is incident on the master hologram 31" will be referred to as the "incident area," and the "area other than the area where coherent light is incident on the master hologram 31" will be referred to as the "non-incident area." The incident area is the area surrounded by fine dashed lines in Figures 5 and 6. Note that such dashed lines are not actually drawn on the first light-transmitting plate 41. The incident area has approximately the same shape and size as the master hologram 31 in a planar view. By irradiating the incident area with coherent light, the coherent light is incident on the master hologram 31. The light-absorbing layer 53 may be provided in a solid state over the entire non-incident region of the first surface (not shown), or may be provided at least in the non-incident region (first surface) on the side where the diffracted light travels. In the example shown, the light-absorbing layer 53 is provided not over the entire non-incident region, but in the non-incident region on the side where the diffracted light travels. In other words, the light-absorbing layer 53 is provided in a part of the non-incident region. Furthermore, the edge 53a of the light-absorbing layer 53 provided on the first surface is located along or near the edge of the incident region.

[0043] The material for forming the light-absorbing layers 51 and 53 is not particularly limited, provided that it contains an absorbent capable of absorbing the diffracted light. The light-absorbing layers 51 and 53 can be formed, for example, from the materials exemplified for the master light-absorbing layer 35. To avoid redundancy, further description will be omitted; for the materials and methods for forming the light-absorbing layers 51 and 53, please refer to the master light-absorbing layer 35.

[0044] 1 to 3 and 5, the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43 are attached to a plate mounting member 48 with their longitudinal end faces in close contact with each other. Both widthwise ends of the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43 are attached to the plate mounting member 48. The plate mounting member 48 is fixed to a frame (not shown) of the manufacturing apparatus A. Note that the plate mounting member 48 may be provided with a movement mechanism (not shown) so that the first light-transmitting plate 41 and the like can be moved.

[0045] The light-absorbing layers 51 and 53 are provided to absorb the diffracted light before it is reflected. For this purpose, the light-absorbing layers 51 and 53 may be provided in an appropriate range on the first surface and / or end surface of the light-transmitting plate, taking into consideration the dimensions of the coherent light, the diffraction angle of the diffracted light, the thickness of the light-transmitting plate (such as the first light-transmitting plate 41), etc. For example, as described above, when the light absorption layer 53 is provided on the first surface of the light-transmitting plate (such as the first light-transmitting plate 41) so that the edge 53a of the light absorption layer 53 is located along or near the edge of the incident area, by satisfying the relationship of the following formula (1), almost all of the diffracted light can be absorbed by the light absorption layers 51, 53 without being internally reflected. Equation (1): h>d / tanθ where h represents the thickness of the light-transmitting plate, d represents the dimension at the incident position of the coherent light, and θ represents the diffraction angle of the diffracted light. In formula (1), d refers to the dimension of the coherent light itself when the dimension of the coherent light at the incident position of the coherent light is equal to or smaller than the dimension of a master hologram, and refers to the dimension of the master hologram when the dimension of the coherent light is larger than the dimension of one master hologram. The diffraction angle of the diffracted light refers to the angle between the normal to the first surface of the master hologram and the propagation direction of the diffracted light.

[0046] Figure 7 is a reference side view showing the state of diffracted light when the relationship of formula (1) is satisfied. In this specification, a "reference side view" refers to a view seen from the side, with the internal components also shown in perspective. In Figure 7, coherent light L1 is shown by a solid line, and diffracted light L2 is shown by a dashed line.

[0047] 7, diffracted light L2 generated from master hologram 31 by irradiation with coherent light L1 is almost entirely absorbed by light absorption layers 51 and 53. This makes it possible to create a replica hologram in photosensitive layer 11 that has interference fringes similar to those of master hologram 31. Specifically, light-absorbing layers 51, 53 are provided on the end faces and first face of the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43. Therefore, as shown in FIG. 7, coherent light L1 incident from the incident region on the first face of the first light-transmitting plate 41 is diffracted at a predetermined diffraction angle (e.g., an acute diffraction angle) recorded in the master hologram 31 of the first row S-1, generating diffracted light L2. When the diffracted light L2 first strikes the first face and end face of the first light-transmitting plate 41, the diffracted light is absorbed by the light-absorbing layers 51, 53 without being internally reflected. Therefore, it is possible to prevent reflected light (diffracted light reflected on the first face and end face of the first light-transmitting plate 41) from re-entering the duplicate hologram 310 formed by exposing the photosensitive layer 11 as the coherent light L1 and diffracted light L2 pass through the photosensitive layer 11. Therefore, the interference fringes of the replica hologram 310 are not disturbed, and it is possible to produce a replica hologram 310 having interference fringes similar to those of the master hologram 31. As with the first light-transmitting plate 41, the diffracted light of the second light-transmitting plate 42 and the third light-transmitting plate 43 is also absorbed by the light-absorbing layers 51, 53 without being internally reflected.

[0048] Furthermore, the light-transmitting plates are divided into a plurality of pieces corresponding to the rows, such as a first light-transmitting plate 41, a second light-transmitting plate 42, and a third light-transmitting plate 43, and a light-absorbing layer 51 is provided on at least the end face of each plate on the side on which the diffracted light travels. Therefore, the diffracted light traveling through one light-transmitting plate does not enter the light-transmitting plate adjacent to the light-transmitting plate in the transport direction. In other words, because the light-transmitting plates are divided into a plurality of pieces and the light-absorbing layer 51 is provided on the end face on the side on which the diffracted light travels, for example, the diffracted light L2 traveling through the second light-transmitting plate 42 does not enter the first light-transmitting plate 41 adjacent to the second light-transmitting plate 42, and the diffracted light L2 traveling through the third light-transmitting plate 43 does not enter the second light-transmitting plate 42 adjacent to the third light-transmitting plate 43. This prevents, for example, diffracted light L2 generated in the master hologram 31 in the second row S-2 from entering the first light-transmitting plate 41, causing the diffracted light L2 to be internally reflected and enter the duplicate hologram 310 in the first row S-1, thereby disrupting the interference fringes of the duplicate hologram 310. The first row S-1 and the second row S-2, and the second row S-2 and the third row S-3, are adjacent rows in the transport direction.

[0049] Furthermore, even when the relationship of the following formula (2) is satisfied, it is possible to prevent reflected light from being incident on the duplicate hologram again. Equation (2): h>d / 2tanθ Here, h, d, and θ are the same as in equation (1).

[0050] Figure 8 is a reference side view showing the state of diffracted light when the relationship of formula (2) is satisfied. Coherent light is shown by a solid line, diffracted light by a dashed line, and reflected light by a dot-dash line. 8, diffracted light L2 generated from the master hologram 31 by irradiation with coherent light L1 is partially absorbed by the light-absorbing layers 51 and 53, but part of the diffracted light L2 is internally reflected at the air interface of the incident region of the first light-transmitting plate 41 (generating reflected light L3). If the relationship of formula (2) is satisfied, the reflected light L3 will not be incident on the replica hologram. Specifically, as shown in FIG. 8 , a portion of the diffracted light L2 is absorbed by the light-absorbing layers 51, 53 provided on the first surface and end surface of the first light-transmitting plate 41 and is not reflected. A portion of the diffracted light L2 travels to the incident region of the first surface of the first light-transmitting plate 41 and is internally reflected there, and reflected light L3 travels back into the first light-transmitting plate 41. When the relationship of formula (2) is satisfied, the reflected light L3 does not enter the duplicate hologram 310 formed in the photosensitive layer 11 but instead travels to the master layer 3. Note that, because the master light-absorbing layer 35 is provided on the second surface of the master layer 3, the reflected light L3 that has passed through the master layer 3 is absorbed by the master light-absorbing layer 35. This prevents the reflected light L3 from repeatedly reflecting and entering the duplicate hologram 310. Even when the relationship of formula (2) is satisfied, the interference fringes of the replica hologram 310 are not disturbed by the reflected light, and it is possible to produce a replica hologram 310 having interference fringes similar to those of the master hologram 31. The second light-transmitting plate 42 and the third light-transmitting plate 43 are similar to the first light-transmitting plate 41.

[0051] Note that neither Equation (1) nor Equation (2) takes into account the thickness of the material to be treated 1. In other words, in Equation (1) and Equation (2), it would be more accurate to define h as "the thickness of the light-transmitting plate + the thickness of the material to be treated 1." However, the thickness of the material to be treated 1 (the thickness of the photosensitive layer 11 and the thickness of the supporting substrate 12) is much smaller than the thickness of the light-transmitting plate. Therefore, even without taking the thickness of the material to be treated 1 into consideration, it is believed that the above-mentioned effects can be achieved by satisfying the relationship between Equation (1) and Equation (2). Note that in each figure, the thickness of the material to be treated 1 (the photosensitive layer 11 and the supporting substrate 12) is exaggerated to make the material to be treated 1 easier to understand. For this reason, h is defined as "the thickness of the light-transmitting plate," but if necessary, h in formulas (1) and (2) may be defined as "the thickness of the light-transmitting plate + the thickness of the material to be treated."

[0052] (others) The exposure section C is provided with a pressure roll 28 for bringing the material 1 into close contact with the light-transmitting plate. The exposure section C also has an index oil injector and an index oil remover (neither of which are shown) that are interposed between the master layer 3 and the material 1 to prevent an air interface from occurring between the master layer 3 and the material 1. A bleaching unit 29 is 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-processed photosensitive layer 11 is bleached by the irradiation, and the photoreaction of the photosensitive layer 11 (the area irradiated with coherent light and the area not irradiated with coherent light) is completed.

[0053] {Hologram manufacturing method} Next, a method for manufacturing a hologram will be described. When a replica hologram is produced using the master hologram 31, the production apparatus A is used. As shown in FIG. 10, the master layer 3 is separated from the support substrate 12 of the processed material 1 by the moving mechanism 382, ​​the transport unit B transports the processed material 1 downstream in the transport direction by a predetermined length, and the transport of the processed material 1 in the exposure unit C is stopped. This predetermined length corresponds to the portion of the photosensitive layer 11 that has been exposed. Next, the pressure roll 28 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 28 is indicated by a two-dot chain line). This causes the first surface of the photosensitive layer 11 of the processed material 1 to adhere to the second surface of the light-transmitting plate. Because the photosensitive layer 11 has slight adhesiveness, lightly pressing the processed material 1 with the pressure roll 28 allows the photosensitive layer 11 of the processed material 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. Thereafter, as shown in FIG. 1, the master layer 3 is moved closer to the support substrate 12 of the processing target 1 by the movement mechanism 382.

[0054] There is a gap between the first surface of the master layer 3 and the support substrate 12 of the workpiece 1, and the presence of this gap creates an air interface. For this reason, an index oil is injected and filled between the first surface of the master layer 3 and the support substrate 12 of the workpiece 1 using an index oil injector (not shown). Figure 3 shows the state after index oil 39 has been injected. Index oil 39 is an oil with a refractive index approximately equal to that of the light-transmitting plate. In this way, a laminate consisting of master layer 3 / index oil 39 / processed material 1 (support substrate 12 + photosensitive layer 11) / transparent plates 41, 42, 43, with no air interface between each layer, is temporarily formed in the exposure section C.

[0055] 1, coherent light L1 is irradiated onto master hologram 31 from the first surface side of light-transmitting plate 41 of this laminate, exposing photosensitive layer 11 to form a replica hologram in photosensitive layer 11, which has interference fringes similar to those of master hologram 31. Coherent light L1 is shaped to have approximately the same shape and size as the master hologram 31 in a planar view. However, as will be described later, coherent light L1 may be larger or smaller than the shape of master hologram 31. The coherent light L1 for exposing the photosensitive layer 11 may be, for example, red laser light, green laser light, blue laser light, or a composite laser light that is a mixture of at least two types of laser light selected from red laser light, green laser light, and blue laser light. Alternatively, laser light of a different wavelength may be applied to each row. For example, red laser light is applied to the master holograms 31 in the first row R-1, green laser light is applied to the master holograms 31 in the second row R-2, and blue laser light is applied to the master holograms 31 in the third row R-3. In this way, the red duplicate holograms are aligned in the first row R-1, the green duplicate holograms are aligned in the second row R-2, and the blue duplicate holograms are aligned in the third row R-3. 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.

[0056] The laser light irradiated from the first surface side of the light-transmitting plate enters the light-transmitting plate from an incident region of the light-transmitting plate (such as first light-transmitting plate 41), passes through photosensitive layer 11, and then enters master hologram 31 to generate diffracted light, which passes through photosensitive layer 11, thereby recording the interference fringes of master hologram 31 in photosensitive layer 11. The portion of photosensitive layer 11 where the interference fringes are recorded becomes a duplicate hologram. As described above, providing the light-absorbing layers 51, 53 on the light-transmitting plate prevents reflected diffracted light from entering the duplicate hologram, thereby ensuring the production of a duplicate hologram having interference fringes similar to those of the master hologram 31. In particular, by dividing the light-transmitting plate into multiple pieces and providing the light-absorbing layers 51, 53 on at least the end face of each light-transmitting plate on the side along which the diffracted light travels, the diffracted light can also be prevented from entering duplicate holograms adjacent to each other in the transport direction.

[0057] Coherent light L1 is irradiated onto the master holograms 31 arranged in the first row S-1, creating a duplicate hologram corresponding to each master hologram 31 in the first row S-1. Then, as shown by the two-dot chain line in Figure 1, mirror 64 is moved to the second row S-2, and coherent light L1 is irradiated onto the master holograms 31 arranged in that row, creating a duplicate hologram in photosensitive layer 11. Then, mirror 64 is moved to the third row S-3, and a duplicate hologram is created in the same manner. After replica holograms corresponding to all of the master holograms 31 in the master layer 3 have been produced in the photosensitive layer 11 in this manner, the master layer 3 is separated from the support substrate 12 of the workpiece 1 by the movement mechanism 382. After the master layer 3 has been separated, index oil is usually attached to the second surface of the support substrate 12 of the workpiece 1. Therefore, the index oil attached to the support substrate 12 is removed by wiping it off using an index oil remover (not shown). The material 1 is then transported downstream in the transport direction by a predetermined length (the length that has been exposed), and the transport is stopped. The material 1 is adhered to the second surfaces of the light-transmitting plates 41, 42, and 43 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 plates 41, 42, and 43 when the transport unit B pulls the material 1. However, if the photosensitive layer 11 is difficult to separate from the light-transmitting plates 41, 42, and 43, an appropriate peeling means may be provided in the transport unit B, or the light-transmitting plates 41, 42, and 43 may be moved away from the material 1 (not shown).

[0058] The exposed material 1 is transported and stopped, returning to the state shown in Figure 10. 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. After this, the master layer 3 is similarly brought into close contact with the material 1 and exposed to coherent light to create duplicate holograms in the photosensitive layer 11 corresponding to all of the master holograms 31. The master layer 3 is then released, the material 1 is transported a predetermined length, and the process is then stopped. This process is repeated. In this manner, duplicate holograms can be continuously created. Figure 11(a) is a plan view of an exposed material 100. The exposed material 1 has a plurality of replicated holograms arranged continuously in its photosensitive layer 11. Hereinafter, the "exposed material 100" will be referred to as the "replica hologram continuum 100." The above example illustrates the use of three rows of master holograms 31, so the replicated hologram continuum 100 in Figure 11(a) has a plurality of replicated holograms 310 arranged in three rows.

[0059] As shown in Figure 1, a bleaching treatment is performed on a replica hologram continuum 100 in a bleaching unit 29. A protective film 15 and a release liner 16 are laminated to the bleached replica hologram continuum 100 in a film laminating unit 25 and a liner laminating unit 26, respectively, and the resulting product is then wound up in a winding unit 27.

[0060] If necessary, the replicate hologram continuum 100 may be divided into individual rows of replicate holograms, and then the individual rows may be wound up on the winding section 27. For example, as shown in Figure 11(b), a multi-row replicate hologram continuum 100 may be divided into single-row replicate hologram continuums 100 using a slitter 290, and these may then be wound up individually. It is generally preferable that the division by the slitter 290 be carried out after the protective films 15 and release liners 16 have been attached to each other.

[0061] <Uses of replicated holograms> By cutting the replicated hologram continuum 100 at appropriate points, individual replicated holograms can be obtained. The use of the replica hologram is not particularly limited. The replica hologram of the present invention can be applied to various applications that have been known in the past or will become known in the future. For example, the replica hologram can be used in optical-related products such as light guide plates; security-related products such as anti-counterfeiting seals and authentication seals; and design-related products such as decorative items. A light guide plate according to one embodiment has a hologram manufactured by the above-described manufacturing apparatus and manufacturing method. For example, a light guide plate can be manufactured by sandwiching a replica hologram between two glass plates or transparent resin plates. Furthermore, a light guide plate for an AR device can be manufactured using the replica hologram. An AR (Augmented Reality) device is a device, such as smart glasses, that can simultaneously project text information and virtual content in addition to the real world. In such a device, light corresponding to the 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.

[0062] For example, the above-mentioned manufacturing apparatus A (or manufacturing method) can also produce a duplicate hologram that is a set of one rectangular hologram called an incoupling and one large rectangular hologram called an outcoupling. As shown in Figure 12, a light guide plate G for an AR device can be constructed by stacking a red duplicate hologram 310R consisting of incouplings 311R and outcouplings 312R, a green duplicate hologram 310G consisting of incouplings 311G and outcouplings 312G, and a blue duplicate hologram 310B consisting of incouplings 311B and outcouplings 312B in that order, and then laminating glass plates or transparent resin plates on the front and back of the stack.

[0063] The second embodiment will be described below. In this description, the configuration and effects that differ from those of the above-described embodiment will be mainly described. For similar configurations, the terms or symbols will be used as they are, and the description of the configuration may be omitted (the same applies to the third embodiment and beyond).

[0064] [Second embodiment] In the first embodiment described above, the longitudinal end faces of multiple light-transmitting plates (e.g., the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43) are in close contact with each other. However, as shown in FIG. 13, there may be gaps between adjacent multiple light-transmitting plates (e.g., the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43).

[0065] Furthermore, while the first embodiment uses multiple separate light-transmitting plates, it is also possible to use a single light-transmitting plate 44, as shown in FIG. 14 . That is, a single light-transmitting plate 44 corresponding to all of the master holograms 31 may be disposed on the first surface side of the master layer 3. When a single light-transmitting plate 44 corresponding to all of the master holograms 31 is used, a light-absorbing layer 53 is provided in at least the non-incident region of the first surface of the light-transmitting plate 44, and preferably, a light-absorbing layer 51 is also provided on the end surface of the light-transmitting plate 44. As shown in FIG. 14 , it is preferable that the light-absorbing layer 53 provided on the first surface of the light-transmitting plate 44 has a dimension equal to or greater than the dimension d of the coherent light. This allows the diffracted light L2 to be absorbed by the light-absorbing layer 53. In this embodiment, one light-transmitting plate 44 is provided for each hologram, and a light-absorbing layer 53 having a dimension equal to or greater than the dimension d of the coherent light is provided on the first surface of the light-transmitting plate 44. This prevents the diffracted light L2 from being internally reflected by the first surface. However, in this embodiment, the distance between adjacent master holograms 31 in the transport direction (for example, the master hologram 31 in the first row S-1 and the master hologram 31 in the second row S-2, or the master hologram 31 in the second row S-2 and the master hologram 31 in the third row S-3) must be relatively large. In this regard, by using light-transmitting plates 41, 42, and 43 separated by rows and provided with light-absorbing layers 51 on their end surfaces, as in the first embodiment, the diffracted light L2 can be absorbed by the light-absorbing layers 51 and 53 even if the distance between adjacent master holograms 31 in the transport direction is relatively small. Therefore, by using light-transmitting plates 41, 42, and 43 that are divided into multiple pieces and provided with a light-absorbing layer 51 as in the first embodiment, the distance between adjacent master holograms 31 can be reduced, which has the advantage of allowing more replica holograms to be produced per unit length of the processed material 1.

[0066] [Third embodiment] In the first embodiment, the photosensitive layer 11 of the material to be processed 1 is brought into close contact with the light-transmitting plates 41, 42, and 43 in the exposure section C, but as shown in Fig. 15, the material to be processed 1 may be turned over so that the photosensitive layer 11 of the material to be processed 1 is brought into close contact with the master layer 3. In this case, an air interface is created between the support substrate 12 of the material to be processed 1 and the second surface of the light-transmitting plate, and index oil 39 may be filled between them.

[0067] [Fourth embodiment] In the first embodiment, coherent light having dimensions substantially the same as those of master hologram 31 is irradiated from the first surface side of the light-transmitting plate. However, this is not limited to this. For example, as shown in FIG. 16( a), coherent light L1 having a dimension d smaller than dimension 31W of master hologram 31 may be irradiated. In this case, a replica hologram 310 having an area smaller than that of master hologram 31 is formed in photosensitive layer 11. Furthermore, as shown in FIG. 16( b), coherent light L1 having a dimension d larger than dimension 31W of master hologram 31 may be irradiated. In this case, a replica hologram 310 having an area substantially the same as that of master hologram 31 is formed in photosensitive layer 11, similar to the case where coherent light L1 having dimension d substantially the same as that of master hologram 31 is irradiated. Note that when coherent light L1 having dimension d larger than dimension 31W of master hologram 31 is irradiated, a portion of the light extends beyond master hologram 31. However, the stray light does not enter the master hologram 31 and does not produce diffracted light. Therefore, interference fringes are not recorded in the photosensitive layer 11 through which the stray light passes. Alternatively, the stray light is absorbed by the light absorption layer 53 and the master light absorption layer 35.

[0068] In the first embodiment, coherent light is irradiated from below the paper surface in the exposure unit C, but coherent light may be irradiated from above the paper surface (not shown). In this case, the configuration of the exposure unit C in the first embodiment is inverted upside down so that coherent light can be irradiated from above the paper surface. In the first embodiment, the coherent light L1 is irradiated parallel to the normal direction of the master hologram 31, and the diffracted light travels at an acute diffraction angle, but this is not limiting. The coherent light L1 is irradiated at an angle that reproduces the master hologram 31. Furthermore, in the first embodiment described above, coherent light is irradiated onto the workpiece 1 in an approximately horizontal position at the exposure section C, but coherent light may also be irradiated onto the workpiece 1 in an oblique or vertical position (not shown), for example. Furthermore, the present invention is not limited to the various embodiments described above, and can be modified as appropriate within the intended scope of the present invention.

[0069] [Fifth embodiment] In the first embodiment, the master hologram 31 is used to create a replica hologram in the photosensitive layer 11, but it is also possible to create a hologram without using a master hologram.

[0070] {Hologram manufacturing equipment} FIG. 17 is a plan view from above of an exposure section C in a manufacturing apparatus A of this embodiment that produces holograms without using a master hologram, and FIG. 18 is an enlarged cross-sectional view of the exposure section C cut along the transport direction. The difference in the configuration of the manufacturing apparatus of this embodiment from the first embodiment is that the manufacturing apparatus A of this embodiment does not include a master layer having a master hologram. However, the manufacturing apparatus A of this embodiment is provided with a prism 9 on the second surface side of the light-transmitting plates 41, 42, and 43 (instead of a master layer).

[0071] 17, 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 in the illustrated example, or may be the same length as or longer than the material 1 to be treated in the width direction. The prism 9 used has a refractive index approximately equal to that of the light-transmitting plate. At least one prism 9 is required. In the illustrated example, three prisms 9 (first prism 91, second prism 92, and third prism 93) are provided corresponding to the light-transmitting plates 41, 42, and 43. There are gaps between the prisms 9 and the light-transmitting plates 41, 42, and 43, and the material to be treated 1 is interposed in the gaps. As indicated by the two-dot chain line in FIG. 18 , the prism 9 is configured to be movable so that it can be moved toward or away from the material to be treated 1. For example, the prism 9 is attached to a mounting member (not shown) equipped with a movement mechanism, and can be moved toward or away from the material to be treated 1 by driving the movement mechanism. When multiple (three) prisms 9 are provided as illustrated, all of the prisms may be configured to be movable synchronously, or each may be configured to be movable independently. Furthermore, the light source (not shown) is configured so as to be able to irradiate coherent light from the first surface side of the light-transmitting plates 41, 42, and 43 and from the prism 9 side. The remaining configuration of the manufacturing apparatus A of this embodiment is the same as that of the manufacturing apparatus of the first embodiment.

[0072] {Hologram manufacturing method} The moving mechanism separates the prism 9 from the support substrate 12 of the material to be processed 1, and the transport unit B transports the material to be processed 1 downstream in the transport direction by a predetermined length, after which the transport of the material to be processed 1 in the exposure unit C is stopped. Next, the pressure roll 28 presses the photosensitive layer 11 of the material to be processed 1 against the second surface of the light-transmitting plates 41, 42, and 43, and then the prism 9 is brought closer to the support substrate 12. Index oil 39 is injected between the prism 9 and the support substrate 12. As a result, a laminate consisting of the prism 9 / index oil 39 / material to be processed 1 (support substrate 12 + unexposed photosensitive layer 11) / light-transmitting plates 41, 42, and 43, with no air interface between the layers, is temporarily formed in the exposure unit C, as shown in FIG. 18 .

[0073] As shown in FIG. 19, coherent light L4-1 is irradiated from the first surface side of a light-transmitting plate 41, and coherent light L4-2, directed in a direction different from that of the coherent light L4-1, is irradiated from the second surface side of a material to be processed 1 including a photosensitive layer 11. The coherent light L4-2 is irradiated to the second surface side of the material to be processed 1 through a first prism 91 to suppress reflection and refraction. In this specification, the coherent light irradiated from the first surface side of the light-transmitting plate is referred to as "first coherent light L4-1," and the coherent light irradiated from the second surface side of the material to be processed 1 is referred to as "second coherent light L4-2." In FIG. 19, the first coherent light L4-1 is represented by a solid line, and the second coherent light L4-2 is represented by a dashed line. The first coherent light L4-1 and the second coherent light L4-2 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 lights is rotated by a half-wave plate to match the polarization axis of the other light, and the split lights are expanded and flattened by a magnifying lens and a collimating lens, respectively, and then each split light is appropriately reflected by a mirror. This allows the first coherent light L4-1 to be irradiated from the first surface side of the light-transmitting plate 41, and the second coherent light L4-2 to be irradiated from the second surface side of the workpiece 1.

[0074] The photosensitive layer 11 is exposed to the coherent light beams (first coherent light beam L4-1 and second coherent light beam L4-2) emitted from the two directions, and interference fringes are recorded on the photosensitive layer 11. In other words, a hologram 311 is formed on the photosensitive layer 11. The second coherent light L4-2 that has passed through the photosensitive layer 11 is absorbed by the light-absorbing layers 51 and 53 provided on the light-transmitting plate 41. As a result, the second coherent light L4-2 is not internally reflected, and the reflected light can be prevented from entering the hologram 311. As a result, the interference fringes of the hologram 311 are not disturbed, and a hologram 311 having the designed interference fringes can be produced. Thereafter, the first surface side of the light-transmitting plate 42 and the second prism 92 are irradiated with first coherent light L4-1 and second coherent light L4-2, respectively, thereby forming a hologram 311 in the photosensitive layer 11. Similarly, the first and second coherent light L4-1 and L4-2 are irradiated from the light-transmitting plate 43 and the third prism 93 to form the hologram 311. Note that the first and second coherent light L4-1 and L4-2 may be simultaneously irradiated onto the light-transmitting plates 41, 42, and 43 and the first to third prisms 91, 92, and 93, respectively. Thereafter, the material 1 is transported downstream in the transport direction by a predetermined length (the length that has been exposed), and the transport is stopped. Thereafter, a hologram is produced by irradiating the photosensitive layer 11 with coherent light in two directions in the same manner. [Explanation of symbols]

[0075] A Hologram manufacturing equipment B. Manufacturing equipment conveying section C. Exposure section of manufacturing equipment D Light source for manufacturing equipment 11 Photosensitive layer 3 Master Tier 31 Master Hologram 41,42,43 Translucent plate 51,53 Light absorbing layer

Claims

1. an exposure unit having a master layer including a master hologram and a light-transmitting plate disposed on a first surface side of the master layer; and a light source that irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate, an apparatus for replicating a master hologram on an unexposed photosensitive layer by interposing the unexposed photosensitive layer between a first surface of the master layer and a second surface of the light-transmitting plate, and exposing the photosensitive layer to coherent light and diffracted light generated from the master hologram by irradiation with the coherent light, the apparatus comprising: a light-absorbing layer that absorbs the diffracted light is provided on an area of ​​the first surface of the light-transmitting plate other than the area onto which the coherent light is incident;

2. 2. The hologram manufacturing apparatus according to claim 1, wherein the master layer has at least two master holograms arranged side by side.

3. 2. The hologram manufacturing apparatus according to claim 1, wherein the light-absorbing layer is provided on at least a first surface of the light-transmitting plate on a side along which the diffracted light travels.

4. an exposure unit having a master layer including a master hologram and a light-transmitting plate disposed on a first surface side of the master layer; and a light source that irradiates the master hologram with coherent light from the first surface side of the light-transmitting plate, an apparatus for replicating a master hologram on an unexposed photosensitive layer by interposing the unexposed photosensitive layer between a first surface of the master layer and a second surface of the light-transmitting plate, and exposing the photosensitive layer to coherent light and diffracted light generated from the master hologram by irradiation with the coherent light, the apparatus comprising: A hologram manufacturing apparatus, wherein a light-absorbing layer that absorbs the diffracted light is provided on at least one of the end faces of the light-transmitting plate on the side where the diffracted light travels.

5. The master layer has at least two master holograms arranged side by side; the transparent plate includes a first transparent plate corresponding to at least one master hologram and a second transparent plate corresponding to at least another master hologram; 5. The hologram manufacturing apparatus according to claim 4, wherein the light absorbing layer is provided on at least one of the end faces of the first and second light-transmitting plates on the traveling side of the diffracted light.

6. 6. The hologram manufacturing apparatus according to claim 5, wherein the light absorbing layer is provided on all end surfaces of the first light-transmitting plate and the second light-transmitting plate.

7. 7. The hologram manufacturing apparatus according to claim 1, wherein the relationship h>d / tan θ is satisfied, where h is the thickness of the light-transmitting plate, d is the dimension at the incident position of the coherent light, and θ is the diffraction angle of the diffracted light.

8. a laminate including a master layer including a master hologram, an unexposed photosensitive layer disposed on a first surface side of the master layer, and a light-transmitting plate disposed on the first surface side of the photosensitive layer, irradiating the master hologram with coherent light from the first surface side of the light-transmitting plate; a manufacturing method for replicating the master hologram in the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiation of the coherent light through the photosensitive layer to expose the master hologram, the method comprising: a light-absorbing layer that absorbs the diffracted light is provided on an area of ​​the first surface of the light-transmitting plate other than an area onto which the coherent light is incident.

9. a laminate including a master layer including a master hologram, an unexposed photosensitive layer disposed on a first surface side of the master layer, and a light-transmitting plate disposed on the first surface side of the photosensitive layer, irradiating the master hologram with coherent light from the first surface side of the light-transmitting plate; a manufacturing method for replicating the master hologram in the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiation of the coherent light through the photosensitive layer to expose the master hologram, the method comprising: A method for manufacturing a hologram, wherein a light-absorbing layer that absorbs the diffracted light is provided on at least one of the end faces of the light-transmitting plate on the side where the diffracted light travels.

10. A manufacturing method for producing a hologram in an unexposed photosensitive layer by arranging a light-transmitting plate on a first surface side of the unexposed photosensitive layer, irradiating the first surface side of the light-transmitting plate with first coherent light and irradiating a second surface side of the photosensitive layer with second coherent light in a direction different from that of the first coherent light, and exposing the photosensitive layer by irradiation with the coherent light from the two directions, comprising: a light-absorbing layer that absorbs the second coherent light is provided on an area of ​​the first surface of the light-transmitting plate other than an area onto which the first coherent light is incident.

11. A manufacturing method for producing a hologram in an unexposed photosensitive layer by arranging a light-transmitting plate on a first surface side of the unexposed photosensitive layer, irradiating the first surface side of the light-transmitting plate with first coherent light and irradiating a second surface side of the photosensitive layer with second coherent light in a direction different from that of the first coherent light, and exposing the photosensitive layer by irradiation with the coherent light from the two directions, comprising: A method for manufacturing a hologram, wherein a light-absorbing layer that absorbs the second coherent light is provided on at least one of the end faces of the light-transmitting plate on the side where the second coherent light travels.

12. A light guide plate having a hologram manufactured by the manufacturing method according to any one of claims 8 to 11.

13. A light guide plate having a hologram manufactured by the manufacturing apparatus according to any one of claims 1 to 6.

14. A light-transmitting plate used in the manufacturing apparatus according to any one of claims 1 to 6.

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