Hologram production device, hologram production method, light-guiding plate, and light-transmitting plate

Abstract

The present invention reproduces a hologram that has the same interference fringe as a master hologram at a light-sensitive layer. A device according to the present invention includes: an exposure part C that includes a master layer 3 that includes a master hologram 31 and a light-transmitting plate 41 that is provided on a first surface side of the master layer 3; and a light source D that irradiates coherent light at the master hologram 31 from a first surface side of the light-transmitting plate. An unexposed light-sensitive layer 11 is interposed between a first surface of the master layer 3 and a second surface of the light-transmitting plate, and the master hologram 31 is reproduced at the light-sensitive layer 11 by exposure of the light-sensitive layer 11 to the coherent light and diffracted light produced from the master hologram 31 by irradiation with the coherent light. A light-absorbing layer 53 that absorbs the diffracted light is provided at a region of a first surface of the light-transmitting plate 41 that is outside a region that is to be struck by the coherent light.

Description

Hologram manufacturing apparatus, hologram manufacturing method, light guide plate, and light-transmitting plate

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

[0002] A hologram can be created 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 the photosensitive layer (see Patent Document 1). Briefly, as shown in FIG. 20 , a laminate including a master layer containing a master hologram, an unexposed photosensitive layer in close contact with the master layer, and a glass plate in close contact with 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 enters 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, recording the interference fringes of the master hologram in the photosensitive layer. In this way, the master hologram can be replicated onto the photosensitive layer. In other words, a hologram similar to the master hologram can be created in the photosensitive layer.

[0003] JP 2018-538580 A

[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.

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

[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. The master hologram then generates diffracted light, which then 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 duplicate hologram in that area. However, the diffracted light that passes through the photosensitive layer may be internally reflected at the air-to-air interface of the glass plate (the bottom surface in the illustrated example), and the reflected light (reflected diffracted light) may then pass through the duplicate hologram again. If the reflected light passes through again, the interference fringes of the duplicate hologram are disrupted, making it impossible to create a duplicate hologram with interference fringes similar to those of the master hologram. Furthermore, when multiple master holograms are arranged side by side, the diffracted light that passes through the photosensitive layer to form one duplicate hologram may reflect at the air-to-air interface, and the reflected light may then pass through the adjacent duplicate hologram, disrupting the interference fringes of that adjacent duplicate hologram. By providing a light-absorbing layer that absorbs the diffracted light so that the reflected light does not re-enter the replicated hologram, it is possible to replicate 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 cases where 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 have proposed the following several means.

[0007] In one aspect, there is provided a hologram manufacturing apparatus, the hologram manufacturing apparatus of a first embodiment comprising: 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, wherein an unexposed photosensitive layer is interposed between the first surface of the master layer and the second surface of the light-transmitting plate, and the apparatus replicates the master hologram on the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiation with the coherent light through the photosensitive layer for exposure, and 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 onto which 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 same as the first or second embodiment, except that the light-absorbing layer is provided on at least the first surface of the light-transmitting plate on the side along which the diffracted light travels.

[0009] A fourth 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, and an unexposed photosensitive layer is interposed between the first surface of the master layer and the second surface of the light-transmitting plate, and the apparatus replicates the master hologram on the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiating it with the coherent light through the photosensitive layer, and 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 aspect of the hologram manufacturing apparatus is the fourth aspect of the hologram manufacturing apparatus, wherein at least two master holograms are arranged side by side on the master layer, the light-transmitting plate includes 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 one end face of the first and second light-transmitting plates facing the diffracted light. A sixth aspect of the hologram manufacturing apparatus is the fifth aspect of the hologram manufacturing apparatus, wherein the light-absorbing layer is provided on all end faces of the first and second light-transmitting plates. A seventh aspect of the hologram manufacturing apparatus is any of the first to sixth aspects of the hologram manufacturing apparatus, 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.

[0011] In another aspect, there is provided a method for manufacturing a hologram. The method for manufacturing a hologram of an eighth aspect includes a laminate including a master layer containing 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, and includes irradiating the master hologram with coherent light from the first surface side of the light-transmitting plate, and allowing the coherent light and diffracted light generated from the master hologram by the irradiation of the coherent light to pass through the photosensitive layer to expose the master hologram to the photosensitive layer, wherein 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 an area onto which 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 on the side where 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 in 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 end surface of the light-transmitting plate on the side where the second coherent light travels.

[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.

[0015] 1 is a side view of a hologram manufacturing apparatus according to a first embodiment; a plan view of an exposure unit of the manufacturing apparatus; an enlarged cross-sectional view taken along line III-III in FIG. 2; a bottom view of a master layer, as viewed from the first surface side; a bottom view of a light-transmitting plate, as viewed from the bottom side; a perspective view of a first light-transmitting plate, as viewed from the bottom side; a reference side view of an exposure unit, illustrating one aspect in which reflected light of diffracted light is unlikely to enter a duplicate hologram; a reference side view of an exposure unit, illustrating another aspect in which reflected light of diffracted light is unlikely to enter a duplicate hologram; a reference view showing a method of manufacturing a master hologram; a side view of a manufacturing apparatus for explaining steps in a method of manufacturing a hologram; a plan view of a duplicate hologram continuum in which holograms are continuously manufactured; 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; a reference side view of an exposure unit according to a first example of a second embodiment; a reference side view of an exposure unit according to a second example of a second embodiment. 17A and 17B are cross-sectional views of an exposure unit according to a third embodiment. (a) is a reference side view of an exposure unit according to a first example of a fourth embodiment, and (b) is a reference side view of an exposure unit according to a second example of the fourth embodiment. ...c) is a plan view of an exposure unit of a manufacturing apparatus according to a fifth embodiment. (d) is an enlarged cross-sectional view taken along line XVIII-XVIII in FIG. 17A. (e) is a reference side view for explaining a method for manufacturing a hologram according to the fifth embodiment. (f) is a reference diagram showing a conventional method for producing a hologram.

[0016] [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 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 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 drawing may differ from the actual ones.

[0017] {Hologram manufacturing apparatus} Fig. 1 is a side view of a hologram manufacturing apparatus of a first embodiment, Fig. 2 is a plan view of an exposure unit in the manufacturing apparatus as seen from above, and Fig. 3 is an enlarged cross-sectional view of the exposure unit cut along the transport direction. 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 within the plane of the material to be processed that is perpendicular to the longitudinal direction.

[0018] The hologram manufacturing apparatus 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 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 used in the manufacturing apparatus may be in the form of a sheet, but 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 refers to a strip whose longitudinal length is significantly longer than its lateral length. The long strip of 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.

[0019] 1 to 3, manufacturing apparatus A has a conveying section B that conveys photosensitive layer 11 in the longitudinal direction, an exposure section C that exposes photosensitive layer 11 conveyed by conveying section B, and a light source D that irradiates coherent light L1 onto a stack including photosensitive layer 11 in exposure section C. Various operations of 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 of manufacturing a duplicate hologram is to convey photosensitive layer 11 to exposure section C, expose photosensitive layer 11 to light in exposure section C to form a duplicate hologram, and then convey photosensitive layer 11 again, repeating this process to continuously produce a plurality of duplicate holograms.

[0020] <Processed Material Including 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. Examples include glass, TAC (triacetylcellulose), 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 side of the support substrate 12 will be referred to as the "processed material 1."

[0021] 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 then 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 1 to be treated is wound into a roll. In this way, the laminated 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.

[0022] <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 accumulate, thereby enabling the material to be treated 1 to be continuously unwound and taken up, a film laminating section 25 that bonds the 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 the release liner 16 to the material to be treated 1 that has been exposed to light, and a take-up section 27 that winds 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.

[0023] 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.

[0024] After the exposure process is completed, the film laminating unit 25 and the liner laminating unit 26 laminate another adhesive-backed protective film 15 and release liner 16 to the treated material 1, and the winding unit 27 winds up the treated material 1 with the bonded protective film 15 and release liner 16 at a predetermined speed. The first accumulation mechanism 241 temporarily retains the treated material 1 being unwound from the unwinding unit 21 while the transport of the treated material 1 is stopped at the exposure unit C, and releases the retained treated material 1 when the treated material 1 that was stopped at the exposure unit C begins to be transported again. The second accumulation mechanism 242 releases the treated material 1 being wound up by the winding unit 27 while the transport of the treated material 1 is stopped at the exposure unit C, and temporarily retains the treated material 1 when the treated material 1 that was stopped at the exposure unit 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.

[0025] <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.

[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 propagates 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 optical devices include a shutter, a beam expander, a half-wave plate, a dielectric multilayer mirror, and a beam splitter, which 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.

[0027] As will be described later, the master layer 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 simultaneously irradiate the remaining several master holograms with laser light by moving the multiple mirrors. 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.

[0028] <Exposure Section> The exposure section C is a part of the manufacturing apparatus A that exposes the photosensitive layer 11. The exposure section 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. The workpiece 1 including the 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) Figure 4 is a bottom view of the master layer 3 as viewed from the first surface side. In other words, Figure 4 is a view of the master layer 3 (excluding the light-transmitting plate and the material to be treated 1) as viewed from the direction of the outline arrow in Figure 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 Figure 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 x 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, the second row S-2, and the third row S-3, and three master holograms are arranged in each of the first column R-1, the second column R-2, and the third column R-3. However, the number and arrangement of master holograms 31 provided in master layer 3 are not limited to the above 3 rows x 3 columns and can be changed as appropriate. There are no particular restrictions on the first and second substrates 32, 33 as long as they are base materials having a refractive index approximately equal to that of the light-transmitting plate, and for example, glass, TAC (triacetyl cellulose), polycarbonate, or other resins can be used.

[0031] Here, a method for manufacturing a master layer containing a master hologram will be briefly described. A master hologram can be manufactured by a conventionally known method. FIG. 9 is a reference diagram schematically illustrating the process of manufacturing a master hologram. As shown in FIG. 9(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, the master hologram may be manufactured using only the photosensitive layer 1100, or may be manufactured using a substrate in which the photosensitive layer 1100 is 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 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 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. In order to maintain coherence, it is preferable that the light IL of the predetermined wavelength is irradiated from two directions after light emitted from a laser oscillator of the 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 coincide with the polarization axis of the other light beam, and the light is magnified and flattened by a magnifying lens and a collimating lens, respectively.

[0032] As shown in FIG. 1B, 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 the laser light of the predetermined wavelength was irradiated when master hologram 3100 was produced. In other words, laser light M1, which is the 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 the light-absorbing layer 35 provided on the master layer 3 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 consists of only the master hologram 31 or 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 passes 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 such absorbents 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. The light that an absorbent can absorb typically depends on the wavelength of the light, so the absorbent is selected taking into account the wavelength of the coherent light. For example, as described below, if red laser light, green laser light, and blue laser light are selectively used as the coherent light during exposure, the light-absorbing layer is formed from a material containing an absorbent capable of absorbing all of these laser lights in the visible light range. A typical example of such an absorbent is a black colorant. Alternatively, a mixed absorbent may be used, for example, comprising a first absorbent that absorbs light with a wavelength of 600 nm to 900 nm, a second absorbent that absorbs light with a wavelength of 450 nm to 750 nm, and a third absorbent 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, an appropriate 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 has a holder 381 that holds the master layer 3 and a moving mechanism 382 that moves the holder 381. The moving 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 of FIG. 1 , the workpiece 1 is transported substantially horizontally in the exposure section C, so the moving mechanism 382 moves the master layer 3 up and down. As shown by the two-dot chain line in FIG. 3 , the moving 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 moving mechanism 382 moves the holder 381 downward, thereby bringing the master layer 3 into substantial contact with the workpiece 1. The moving 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] (Light-Transmitting Plates) Figure 5 is a bottom view of the light-transmitting plates 41, 42, and 43 as viewed from the first surface side. In other words, Figure 5 is a view of the light-transmitting plates 41, 42, and 43 as viewed from the direction of the white arrow in Figure 3 (excluding the material to be treated 1 and the master layer 3). With reference to Figures 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 disposed on the first surface side of the master layer 3. Note that, 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 disposed on the first surface side of the master layer 3 with a gap therebetween.

[0037] As shown in FIG. 3 , light-transmitting plates 41, 42, and 43 are provided corresponding to at least one master hologram 31. For example, if the master layer 3 includes multiple master holograms 31, one light-transmitting plate may be arranged on the first surface of the master layer 3 corresponding to all of the master holograms 31. Alternatively, one light-transmitting plate 41 may be arranged corresponding to at least one master hologram 31, and another light-transmitting plate 42 may be arranged corresponding to at least another master hologram 31. In the latter case, multiple 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 holograms 31. Specifically, as described above, the master layer 3 has three rows and three columns of master holograms 31 arranged thereon, and therefore 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. With reference to Fig. 1 , the first light-transmitting plate 41 is located downstream in the conveying 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 conveying 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 will 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 FIG. 6 depicts the first surface of the first light-transmitting plate 41 facing upward. With reference to FIGS. 3, 5, and 6, the first light-transmitting plate 41 is formed in a rectangular parallelepiped shape with its longitudinal axis extending 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 transport direction). "Side view" refers to viewing the object from one side in the width direction to the opposite side. The thickness of the first light-transmitting plate 41 is set as appropriate, but it is preferable that the thickness of the first light-transmitting plate 41 be relatively large in order to minimize reflection of diffracted light. 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 formed from a material that transmits coherent light. For example, the first light-transmitting plate 41 (light-transmitting plate) is formed from a material with a refractive index of approximately 1.5. Examples of materials with a refractive index of approximately 1.5 include glass and resins such as TAC (triacetyl cellulose) and polycarbonate. 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 is incident on the master hologram 31. In this embodiment, the light-absorbing layers 51 and 53 are provided on the end faces and 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 FIGS. 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 diffracted light travels. In the illustrated example, the light-absorbing layer 53 is provided not over the entire non-incident region, but in the non-incident region on the side where 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, and the material and method for forming the light-absorbing layers 51 and 53 should be referred 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, 53 are provided to absorb the diffracted light before it is reflected. For this purpose, the light-absorbing layers 51, 53 may be provided in an appropriate area 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 (e.g., the first light-transmitting plate 41), and the like. For example, as described above, when the light-absorbing layer 53 is provided on the first surface of the light-transmitting plate (e.g., the first light-transmitting plate 41) so that the edge 53a of the light-absorbing layer 53 is located along or near the edge of the incident area, the relationship of the following formula (1) can be satisfied to absorb almost all of the diffracted light without causing internal reflection by the light-absorbing layers 51, 53. Formula (1): h > d / tan θ, 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 is equal to or smaller than the dimension of the master hologram at the incident position of the coherent light, 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 direction of 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, the term "reference side view" refers to a side view that shows the internal components in a perspective view. In Figure 7, coherent light L1 is shown by a solid line, and diffracted light L2 is shown by a dashed line.

[0047] As shown in FIG. 7 , diffracted light L2 generated from the master hologram 31 by irradiation with coherent light L1 is almost entirely absorbed by the light-absorbing layers 51 and 53. This allows a replica hologram having interference fringes similar to those of the master hologram 31 to be formed in the photosensitive layer 11. Specifically, light-absorbing layers 51 and 53 are provided on the end faces and first surface 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 area on the first surface 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 in the first row S−1, generating diffracted light L2. When the diffracted light L2 first strikes the first surface and end surface of the first light-transmitting plate 41, the diffracted light is absorbed by the light-absorbing layers 51 and 53 without internal reflection. This prevents reflected light (diffracted light reflected by the first surface or end surface of the first light-transmitting plate 41) from being re-entered into the duplicate hologram 310 formed by exposing the photosensitive layer 11 to coherent light L1 and diffracted light L2 as they pass through the photosensitive layer 11. This prevents the interference fringes of the duplicate hologram 310 from being disturbed, making it possible to produce a duplicate 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 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 the first light-transmitting plate 41, the second light-transmitting plate 42, and the third light-transmitting plate 43, and a light-absorbing layer 51 is provided on at least one end face of each plate on the side along which the diffracted light travels. Therefore, the diffracted light traveling through one light-transmitting plate does not enter the light-transmitting plate adjacent to that light-transmitting plate in the transport direction. In other words, because the light-transmitting plate is divided into a plurality of pieces and the light-absorbing layer 51 is provided on the end face along 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. Therefore, for example, it is possible to prevent diffracted light L2 generated in the master hologram 31 in the second row S-2 from entering the first light-transmitting plate 41, and then the diffracted light L2 from being internally reflected and entering the duplicate hologram 310 in the first row S-1, thereby disturbing 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, reflected light can be prevented from re-entering the duplicate hologram even when the following relationship (2) is satisfied: h>d / 2 tan θ (2), where h, d, and θ are the same as in equation (1).

[0050] FIG. 8 is a reference side view showing the state of diffracted light when the relationship of Equation (2) is satisfied. Coherent light is represented by a solid line, diffracted light by a dashed line, and reflected light by a dashed-dotted line. As shown in FIG. 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 a portion 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). When the relationship of Equation (2) is satisfied, the reflected light L3 does not enter the replica hologram. Specifically, as shown in FIG. 8 , a portion of the diffracted light L2 is absorbed by the light-absorbing layers 51 and 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, is internally reflected at the incident region, 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 proceeds to the master layer 3. Note that, because a 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 duplicate hologram 310 are not disturbed by the reflected light, and a duplicate hologram 310 having interference fringes similar to those of the master hologram 31 can be produced. 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, it is believed that the above-mentioned effects can be achieved by satisfying the relationship between Equation (1) and Equation (2) even without considering the thickness of the material to be treated 1. 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, particularly 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." However, if necessary, h in Equation (1) and Equation (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 adhering the material 1 to the light-transmitting plate. The exposure section C also includes an index oil injector and an index oil remover (both not shown) that are interposed between the master layer 3 and the material 1 to prevent an air interface from forming between the master layer 3 and the material 1. A bleaching section 29 is provided downstream of the exposure section C. The bleaching section 29 irradiates the material 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).

[0053] {Hologram Manufacturing Method} Next, a hologram manufacturing method will be described. The above-described manufacturing apparatus A is used to manufacture a replica hologram using the master hologram 31. As shown in FIG. 10 , the moving mechanism 382 separates the master layer 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 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 brings the first surface of the photosensitive layer 11 of the workpiece 1 into close contact with the second surface of the light-transmitting plate. Since the photosensitive layer 11 has slight adhesiveness, the photosensitive layer 11 of the material to be processed 1 can be brought into close contact with the second surface of the light-transmitting plate without creating an air interface between the photosensitive layer 11 and the light-transmitting plate by lightly pressing the material to be processed 1 with the pressure roll 28. Thereafter, as shown in Figure 1, the moving mechanism 382 moves the master layer 3 closer to the support substrate 12 of the material to be processed 1.

[0054] A gap exists 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. Therefore, 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 the index oil 39 has been injected. The 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 the master layer 3 / index oil 39 / workpiece 1 (support substrate 12 + photosensitive layer 11) / light-transmitting plates 41, 42, 43, with no air interface between the layers, is temporarily formed in the exposure section C.

[0055] As shown in FIG. 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 create a replica hologram in the photosensitive layer 11 having interference fringes similar to those of the master hologram 31. The coherent light L1 is shaped to have substantially the same shape and size as the master hologram 31 in a planar view. However, as described below, 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. Laser light of different wavelengths may also be irradiated for each row. For example, red laser light is irradiated onto the master holograms 31 in the first row R-1, green laser light is irradiated onto the master holograms 31 in the second row R-2, and blue laser light is irradiated onto the master holograms 31 in the third row R-3. In this manner, the red duplicate holograms are arranged in the first row R-1, the green duplicate holograms are arranged in the second row R-2, and the blue duplicate holograms are arranged in the third row R-3. It should be noted that when irradiating the master holograms 31 with laser light of a predetermined wavelength (e.g., red laser light) to expose the photosensitive layer 11, the master holograms 31 are naturally produced using laser light of the same wavelength as the laser light of the predetermined wavelength.

[0056] Laser light irradiated from the first surface of the light-transmitting plate enters the light-transmitting plate through 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, generating diffracted light. The diffracted light then 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 light-absorbing layers 51 and 53 on the light-transmitting plate prevents reflected light from diffracting the light from entering the duplicate hologram. This ensures the production of duplicate holograms with interference fringes similar to those of master hologram 31. In particular, providing multiple light-transmitting plates and light-absorbing layers 51 and 53 on at least one end face of each light-transmitting plate on the side where the diffracted light travels also prevents the diffracted light from entering duplicate holograms adjacent 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 FIG. 1 , the 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 the photosensitive layer 11. The mirror 64 is then moved to the third row S-3, and a duplicate hologram is created in the same manner. After duplicate holograms corresponding to all of the master holograms 31 in the master layer 3 are created in the photosensitive layer 11 in this manner, the moving mechanism 382 separates the master layer 3 from the support substrate 12 of the workpiece 1. After the master layer 3 is separated, index oil typically adheres to the second surface of the support substrate 12 of the workpiece 1. Therefore, the index oil adhering 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 transport is then 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 FIG. 10 . This sends the exposed photosensitive layer 11 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 master holograms 31. The master layer 3 is then released, the material 1 is transported a predetermined length, and the process is repeated. In this manner, duplicate holograms can be continuously created. FIG. 11( a ) is a plan view of the exposed material 100. The exposed material 1 has multiple duplicate holograms arranged consecutively in its photosensitive layer 11. Hereinafter, the "exposed material 100" will be referred to as the "duplicate hologram continuum 100." In the above example, three rows of master holograms 31 are used, so the duplicate hologram continuum 100 in FIG. 11(a) has a plurality of duplicate holograms 310 arranged in three rows.

[0059] 1, a bleaching process 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 these may be individually wound up on the winding section 27. For example, as shown in Figure 11(b), a double-row replicate hologram continuum 100 may be divided into single-row replicate hologram continuums 100 using a slitter 290, and these may then be individually wound up. 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 bonded to each other.

[0061] <Uses of Replica Holograms> Individual replica holograms can be obtained by cutting the replica hologram continuum 100 at appropriate locations. The uses of the replica hologram are not particularly limited. The replica hologram of the present invention can be applied to various applications that have been publicly known or will become publicly known in the future. Replica 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 manufactured using 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 also be manufactured using the replica 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.

[0062] For example, the above-described manufacturing apparatus A (or manufacturing method) can also produce a duplicate hologram set consisting of one rectangular hologram called an incoupling and one large rectangular hologram called an outcoupling. As shown in Fig. 12, 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 are laminated in this order, and glass plates or transparent resin plates are laminated on the front and back surfaces of the laminate, thereby forming a light guide plate G for an AR device.

[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, the longitudinal end faces of the plurality of 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 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, a single light-transmitting plate 44 may be used, as shown in FIG. 14 . That is, a single light-transmitting plate 44 corresponding to all 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 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 , the light-absorbing layer 53 provided on the first surface of the light-transmitting plate 44 preferably 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. By disposing a single light-transmitting plate 44 corresponding to all holograms and providing a light-absorbing layer 53 with a dimension equal to or greater than the dimension d of the coherent light on its first surface, as in this embodiment, the diffracted light L2 can be prevented from being internally reflected at the first surface. However, in the present embodiment, the interval between adjacent master holograms 31 in the transport direction (for example, between the master hologram 31 in the first row S-1 and the master hologram 31 in the second row S-2, or between 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 that are separated into rows and have light-absorbing layers 51 on their end faces, as in the first embodiment, the diffracted light L2 can be absorbed by the light-absorbing layers 51 and 53 even if the interval between adjacent master holograms 31 in the transport direction is relatively small. Therefore, by using light-transmitting plates 41, 42, and 43 that are separated into multiple plates and have light-absorbing layers 51, as in the first embodiment, the interval between adjacent master holograms 31 can be made small, which has the advantage of allowing more duplicate 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. However, 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 the two.

[0067] [Fourth Embodiment] In the first embodiment, coherent light having substantially the same dimensions as the 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 the dimension 31W of the master hologram 31 may be irradiated. In this case, a duplicate hologram 310 having a smaller area than the master hologram 31 is formed in the photosensitive layer 11. Furthermore, as shown in FIG. 16( b), coherent light L1 having a dimension d larger than the dimension 31W of the master hologram 31 may be irradiated. In this case, a duplicate hologram 310 having substantially the same area as the master hologram 31 is formed in the photosensitive layer 11, similar to the case where coherent light L1 having substantially the same dimension d as the master hologram 31 is irradiated. Note that when coherent light L1 having a dimension d larger than the dimension 31W of the master hologram 31 is irradiated, a portion of the light extends beyond the 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 exposure unit C, but coherent light may be irradiated from above the exposure unit C (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 exposure unit C. Furthermore, 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. However, this is not limited to this example. The coherent light L1 is irradiated at an angle that reproduces the master hologram 31. Furthermore, in the first embodiment, coherent light is irradiated onto the workpiece 1 in a substantially horizontal position in the exposure unit C. However, coherent light may be irradiated onto the workpiece 1 in an oblique or vertical position (not shown). The present invention is not limited to the above-described various embodiments 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 Apparatus} Figure 17 is a plan view from above of an exposure unit C in a manufacturing apparatus A of this embodiment that produces holograms without using a master hologram, and Figure 18 is an enlarged cross-sectional view of the exposure unit C cut along the transport direction. The manufacturing apparatus of this embodiment differs from the first embodiment in terms of configuration in 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 light-transmitting plates 41, 42, and 43 (in place of a master layer).

[0071] As shown in FIG. 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 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. At least one prism 9 is required. In the illustrated example, three prisms 9 (a first prism 91, a second prism 92, and a 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 1 to be treated is interposed in the gaps. Furthermore, the prism 9 is configured to be movable so that it can be moved closer to and farther away from the material 1 to be treated, as shown by the two-dot chain line in FIG. 18 . For example, the prism 9 is attached to a mounting member (not shown) equipped with a moving mechanism, and can be moved closer to or farther away from the material 1 to be treated by driving the moving mechanism. When multiple (three) prisms 9 are provided as shown in the figure, all of the prisms may be configured to be movable synchronously, or may be configured to be movable independently. The light source (not shown) is configured to irradiate coherent light from the first surface side of the light-transmitting plates 41, 42, 43 and the prism 9 side, respectively. The remaining configuration of the manufacturing apparatus A of this embodiment is the same as that of the manufacturing apparatus of the first embodiment described above.

[0072] {Hologram Manufacturing Method} The movement mechanism separates the prism 9 from the support substrate 12 of the material to be processed 1, the transport unit B transports the material to be processed 1 downstream in the transport direction by a predetermined length, and transport of the material to be processed 1 in the exposure unit C is stopped. Next, the pressure roll 28 brings the photosensitive layer 11 of the material to be processed 1 into close contact with the second surfaces 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 Figure 19, coherent light L4-1 is irradiated from the first surface side of the light-transmitting plate 41, and coherent light L4-2, oriented in a direction different from that of the coherent light L4-1, is irradiated from the second surface side of the material to be processed 1, including the photosensitive layer 11. The coherent light L4-2 is irradiated onto 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 Figure 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 light beams is rotated by a half-wave plate to match the polarization axis of the other light beam, and the split light beams are expanded and flattened by a magnifying lens and a collimating lens, respectively, and then appropriately reflected by mirrors. 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. In other words, a hologram 311 is formed in the photosensitive layer 11. The second coherent light beam L4-2 transmitted through the photosensitive layer 11 is absorbed by the light-absorbing layers 51 and 53 provided on the light-transmitting plate 41. This prevents the second coherent light beam L4-2 from being internally reflected, preventing the reflected light from entering the hologram 311. This prevents the interference fringes of the hologram 311 from being disturbed, and allows the hologram 311 to have the designed interference fringes. Subsequently, the first surface side of the light-transmitting plate 42 and the second prism 92 are irradiated with the first coherent light beam L4-1 and the second coherent light beam L4-2, respectively, thereby forming the hologram 311 in the photosensitive layer 11. Similarly, first and second coherent light beams L4-1 and L4-2 are irradiated from the light-transmitting plate 43 and the third prism 93 to produce a hologram 311. The first and second coherent light beams L4-1 and L4-2 may be irradiated simultaneously onto the light-transmitting plates 41, 42, and 43 and the first through third prisms 91, 92, and 93, respectively. 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. Similarly, the photosensitive layer 11 is then irradiated with coherent light beams in two directions to produce a hologram.

[0075] A: Hologram manufacturing apparatus B: Conveying section of manufacturing apparatus C: Exposure section of manufacturing apparatus D: Light source of manufacturing apparatus 11: Photosensitive layer 3: Master layer 31: Master hologram 41, 42, 43: Light-transmitting plates 51, 53: Light-absorbing layers

Claims

1. A hologram manufacturing device comprising: 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; an unexposed photosensitive layer is interposed between the first surface of the master layer and the second surface of the light-transmitting plate; and the coherent light and diffracted light generated from the master hologram by irradiating the coherent light are transmitted through the photosensitive layer to expose the master hologram to the photosensitive layer, wherein 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.

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

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

4. A hologram manufacturing device comprising: 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; an unexposed photosensitive layer interposed between the first surface of the master layer and the second surface of the light-transmitting plate; and an exposure device that copies the master hologram onto the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by irradiating it with the coherent light through the photosensitive layer, wherein a light-absorbing layer that absorbs the diffracted light is provided on at least one end surface of the light-transmitting plate on the side where the diffracted light travels.

5. A hologram manufacturing device as described in claim 4, wherein 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.

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

7. A hologram manufacturing apparatus according to any one of claims 1 to 6, 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 manufacturing method for a laminate having a master layer containing a master hologram, an unexposed photosensitive layer arranged on the first surface side of the master layer, and a light-transmitting plate arranged on the first surface side of the photosensitive layer, comprising irradiating the master hologram with coherent light from the first surface side of the light-transmitting plate, and exposing the master hologram to the photosensitive layer by transmitting the coherent light and diffracted light generated from the master hologram by the irradiation of the coherent light through the photosensitive layer, wherein 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.

9. A manufacturing method for a laminate having a master layer containing a master hologram, an unexposed photosensitive layer arranged on the first surface side of the master layer, and a light-transmitting plate arranged on the first surface side of the photosensitive layer, in which the master hologram is replicated in the photosensitive layer by irradiating the master hologram with coherent light from the first surface side of the light-transmitting plate and allowing the coherent light and diffracted light generated from the master hologram by the irradiation of the coherent light to pass through the photosensitive layer to expose the master hologram, wherein a light-absorbing layer that absorbs the diffracted light is provided on at least one end surface 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 placing a light-transmitting plate on the first surface side of the photosensitive layer, irradiating the first surface side of the light-transmitting plate with first coherent light and irradiating the second surface side of the photosensitive layer with second coherent light in a direction different from the first coherent light, and exposing the photosensitive layer with coherent light irradiation from the two directions, wherein 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.

11. A method for producing a hologram in an unexposed photosensitive layer by placing a light-transmitting plate on the first surface side of the photosensitive layer, irradiating the first surface side of the light-transmitting plate with first coherent light and irradiating the second surface side of the photosensitive layer with second coherent light in a direction different from that of the first coherent light, thereby exposing the photosensitive layer to the coherent light irradiation from the two directions, wherein 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 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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