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

Abstract

Provided is a hologram manufacturing device for efficiently manufacturing a plurality of holograms in a photosensitive layer. A device A includes: an exposure unit C having a master layer 3 having a master hologram 31; a conveyance unit B that conveys an unexposed photosensitive layer 11 and arranges the photosensitive layer 11 on a first surface side of the master layer 3 of the exposure unit C; and a light source D that irradiates the master hologram 31 with coherent light from a first surface side of the photosensitive layer 11. The device A copies interference fringes of the master hologram 31 onto the photosensitive layer 11 by exposing the photosensitive layer by passing the coherent light and diffracted light, generated from the master hologram 31 by the irradiation of the coherent light, through the photosensitive layer 11. The master layer 3 has a plurality of the master holograms 31, and the light source D irradiates all the master holograms 31 of the master layer 3 with coherent light L11 simultaneously.

Description

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

[0001] The present invention relates to a hologram manufacturing apparatus and method for manufacturing a hologram by replicating a master hologram.

[0002] A known method for manufacturing holograms involves optically replicating the interference fringes of a master hologram onto a photosensitive layer using a master hologram. 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 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 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 produced in the photosensitive layer.

[0003] For example, Patent Document 1 discloses a duplication method in which an original hologram is attached to a flat portion of a rotating body, a photosensitive film for duplication is wrapped around and tightly attached to the original hologram, the rotating body is intermittently rotated together with the photosensitive film for duplication, and when the rotating body comes to a standstill, reproduction light is irradiated at an angle to reproduce the original hologram, and the hologram information is intermittently reproduced on the photosensitive film for duplication.

[0004] Japanese Patent Application Publication No. 5-249876

[0005] Patent Document 1 does not disclose or suggest at all about duplicating the interference fringes (information) of a plurality of master holograms onto a photosensitive layer or about a method of irradiating the reproduction light.

[0006] An object of the present invention is to provide a hologram manufacturing apparatus and method that efficiently produces a plurality of holograms in a photosensitive layer by irradiating a master layer having a plurality of master holograms with coherent light.

[0007] In one aspect, there is provided a hologram manufacturing apparatus, comprising: an exposure unit having a master layer having a master hologram; a transport unit that transports an unexposed photosensitive layer and positions the photosensitive layer on a first surface side of the master layer in the exposure unit; and a light source that irradiates the master hologram with coherent light from the first surface side of the photosensitive layer, and exposes 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, where the master layer has a plurality of master holograms, and the light source irradiates all of the master holograms in the master layer with the coherent light simultaneously.

[0008] A second embodiment of the hologram manufacturing apparatus is the same as the first embodiment, except that the photosensitive layer is long and strip-shaped, the plurality of master holograms are arranged in multiple columns in the width direction of the photosensitive layer and multiple rows in a transport direction perpendicular to the width direction, and the transport unit transports the long and strip-shaped photosensitive layer a predetermined length in the longitudinal direction and then stops transporting the photosensitive layer.A third embodiment of the hologram manufacturing apparatus is the same as the first or second embodiment, except that the light source has a mask member that trims the expanded and flattened coherent light, and the trimming light that has passed through the mask member is irradiated simultaneously onto all of the master holograms in the master layer, and the ratio of the intensity of the edge of the trimming light to the intensity of the center of the trimming light is 20% to 80%. A fourth aspect of the hologram manufacturing apparatus is the manufacturing apparatus of any one of the first to third aspects, wherein the light source has a mask member that trims the expanded and flattened coherent light, the trimming light that has passed through the mask member is irradiated simultaneously onto all of the master holograms in the master layer, and the ratio of the effective area of ​​the trimming light to the area of ​​the coherent light immediately before passing through the mask member is 5% to 60%. A fifth aspect of the hologram manufacturing apparatus is the manufacturing apparatus of the third or fourth aspect, wherein the light source further has an oscillator of the coherent light and a reflector that changes the traveling direction of the light toward the master hologram, and the mask member is disposed between the oscillator and the reflector or between the reflector and the photosensitive layer.

[0009] In another aspect, there is provided a hologram manufacturing method of a sixth aspect, comprising: a transport step of transporting an unexposed photosensitive layer to a first surface side of a master layer having a master hologram; and an exposure step of irradiating the photosensitive layer with coherent light from the first surface side after placing the photosensitive layer on the first surface side of the master layer, wherein the coherent light and diffracted light generated from the master hologram by irradiating the coherent light through the photosensitive layer to replicate interference fringes of the master hologram in the photosensitive layer, the master layer having a plurality of master holograms, and the coherent light is irradiated simultaneously to all of the master holograms in the master layer in the exposure step.

[0010] A seventh aspect of the hologram manufacturing method is the same as the sixth aspect, except that the trimming is performed by passing the expanded and flattened coherent light through a mask member, and all of the master holograms in the master layer are simultaneously irradiated with the trimming light that has passed through the mask member, and the ratio of the intensity of the edge of the trimming light to the intensity of the center of the trimming light is 20% to 80%.A eighth aspect of the hologram manufacturing method is the same as the sixth or seventh aspect, except that the trimming is performed by passing the expanded and flattened coherent light through a mask member, and all of the master holograms in the master layer are simultaneously irradiated with the trimming light that has passed through the mask member, and the ratio of the effective area of ​​the trimming light to the area of ​​the coherent light immediately before passing through the mask member is 5% to 60%.

[0011] According to the manufacturing apparatus and manufacturing method of the present invention, it is possible to efficiently replicate a plurality of holograms in a photosensitive layer.

[0012] 1 is a side view of a hologram manufacturing apparatus according to a first embodiment; a plan view of an exposure unit of the same manufacturing apparatus; a perspective view of the exposure unit and light source of the same manufacturing apparatus; an enlarged cross-sectional view taken along line IV-IV in FIG. 2; a bottom view of a master layer, as viewed from the first surface side of the master layer; a bottom view of a light-transmitting plate, as viewed from the bottom side of the light-transmitting plate; 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 illustrating a method of manufacturing a master hologram; a side view of a manufacturing apparatus for explaining the steps of a hologram manufacturing method; 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 perspective view of an exposure unit and light source according to a second embodiment. 1. A reference side view of an exposure unit according to a first example of the third embodiment. 2. A reference side view of an exposure unit according to a second example of the third embodiment. 3. A cross-sectional view of an exposure unit according to a fourth embodiment. 4. A reference plan view showing an example of the arrangement of master holograms used in the examples. 5. A reference plan view showing laser light and trimming light used in the examples. 6. A reference diagram for explaining a conventional method of replicating a hologram.

[0013] [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.

[0014] {Hologram manufacturing apparatus} 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 unit in the manufacturing apparatus as seen from above, Fig. 3 is a perspective view showing the exposure unit and light source in the manufacturing apparatus, and Fig. 4 is an enlarged cross-sectional view of the exposure unit cut along the transport direction. In Figs. 2 and 3, both sides of a long, strip-shaped material to be processed are omitted. Also, in Fig. 3, the master mounting member for mounting a master layer and the plate mounting member for mounting a light-transmitting plate are omitted. In this specification, the "transport direction" corresponds to the longitudinal direction of the material to be processed, and the "width direction" refers to the direction perpendicular to the longitudinal direction within the plane of the material to be processed.

[0015] 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.

[0016] 1 to 4, 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 onto a laminate 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.

[0017] <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."

[0018] The long strip-shaped material 1 to be treated may be wound into a roll for storage, transportation, etc. However, it is preferable to attach a protective film 15 or the like to the material 1 to prevent scratches on the support substrate 12 and the photosensitive layer 11. For example, an adhesive-backed protective film 15 is attached to the support substrate 12 side of the material 1 to be treated. A release liner 16 is attached to the photosensitive layer 11 side of the material 1 to be treated. The release liner 16 is attached for the following two purposes: one is to protect the photosensitive layer 11; and the other is to conceal the slight adhesiveness of the photosensitive layer 11, which has slight adhesiveness, and prevent blocking when the material 1 to be treated is wound into a roll. In this way, a laminate film consisting of the adhesive-backed protective film 15 / material 1 to be treated (support substrate 12 + photosensitive layer 11) / release liner 16 is wound into a roll and loaded into the unwinding section of the manufacturing apparatus A.

[0019] <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.

[0020] 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.

[0021] 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.

[0022] <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.

[0023] (Master Layer and Master Mounting Member) Figure 5 is a bottom view of the master layer 3 as viewed from the first surface side. In other words, Figure 5 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 4. 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 5.

[0024] 1 to 5, the master layer 3 has a plurality of master holograms 31. For example, the master layer 3 has a first substrate 32, a second substrate 33, and a plurality of master holograms 31 interposed between the first substrate 32 and the second substrate 33. The master holograms 31 are arranged at predetermined intervals along the surface of the master layer 3. That is, the master holograms 31 are arranged in m columns (m is an integer of 2 or greater) in the width direction and n rows (n is an integer of 2 or greater) in the transport direction, which is a direction perpendicular to the width direction. Here, m is an integer of 2 or greater, and n is an integer of 2 or greater. The upper limits of m and n are not particularly limited, but are each independently, for example, 20 or less, preferably 15 or less. 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 workpiece 1). In the illustrated example, a total of nine master holograms 31 are provided in a 3 x 3 matrix 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 in three columns in the width direction of the material 1 to be processed, with a gap between each row and each column. Thus, 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 the master holograms 31 provided on the master layer 3 are not limited to the three rows and three columns and can be changed as appropriate. The first and second substrates 32 and 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 may be made of, for example, glass, TAC (triacetyl cellulose), polycarbonate, or other resins.

[0025] 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. 10 is a reference diagram schematically illustrating the process of manufacturing a master hologram. As shown in FIG. 10( 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 the same laser oscillator 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.

[0026] As shown in FIG. 1B, master hologram 3100 manufactured as described above is irradiated with laser light IL100 of the 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 produced. In other words, laser light IL100, 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 IL200). When laser light of a red wavelength is irradiated, a red master hologram is generated; when laser light of a green wavelength is irradiated, a green master hologram is generated; and when light of a blue wavelength is irradiated, a blue master hologram is generated.

[0027] Returning to FIG. 4 , a light-absorbing layer 35 is provided on the second surface of the master layer 3. Hereinafter, the light-absorbing layer 35 provided on the master layer 3 will be referred to as the "master light-absorbing layer 35" to distinguish it from a light-absorbing layer provided on a light-transmitting plate. The master light-absorbing layer 35 is laminated at least in the area of ​​the second surface of the master layer 3 corresponding 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 passes through the master hologram 31 when a portion of the coherent light passes through the master hologram 31. The master light-absorbing layer 35 also absorbs light that passes through portions of the master layer 3 where the master hologram 31 is not provided.

[0028] 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, green, and blue laser beams are selectively used as coherent light during exposure, the light-absorbing layer is formed from a material containing an absorbent capable of absorbing all of these laser beams 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.

[0029] 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. 4 , 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.

[0030] (Light-Transmitting Plates) Figure 6 is a bottom view of the light-transmitting plates 41, 42, and 43 as viewed from the first surface side. In other words, Figure 6 is a view of the light-transmitting plates 41, 42, and 43 as viewed from the direction of the white arrow in Figure 4 (excluding the material to be treated 1 and the master layer 3). With reference to Figures 1 to 4 and 6, 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.

[0031] As shown in FIG. 4 , 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, n rows of master holograms 31 are provided on the master layer 3, and therefore n light-transmitting plates are arranged corresponding to each row. In the illustrated example, three rows and three columns of master holograms 31 are arranged, 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.

[0032] 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.

[0033] 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."

[0034] Specific Examples of the First Light-Transmitting Plate 41 FIG. 7 is a perspective view of the first light-transmitting plate 41. Note that FIG. 7 depicts the first surface of the first light-transmitting plate 41 facing upward. With reference to FIGS. 4, 6, and 7, 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 in a side view). "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.

[0035] 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.

[0036] Furthermore, a light-absorbing layer 53 is also provided on the first surface of the first light-transmitting plate 41. A region of the first surface of the first light-transmitting plate 41 that is irradiated with coherent light to record a replica hologram in the photosensitive layer 11 and has approximately the same shape and size as the master hologram 31 in a planar view is called a "corresponding region," while a region of the first surface of the first light-transmitting plate 41 other than the corresponding region is called a "non-corresponding region." When exposing the photosensitive layer 11 to form interference fringes of the master hologram 31 in the photosensitive layer 11, the corresponding region can be irradiated with coherent light that is the same shape and size as the master hologram 31 or smaller in size than the master hologram 31. Therefore, when coherent light is incident at least from within the corresponding region, the coherent light enters the master hologram 31 from the corresponding region, thereby forming a replica hologram in the photosensitive layer 11. In FIGS. 6 and 7 , the corresponding region is indicated by a fine dashed line (the corresponding region is the area surrounded by the fine dashed line). It should be noted that such broken lines are not actually drawn on the first light-transmitting plate 41 .

[0037] The light-absorbing layer 53 is provided in the non-corresponding region of the first surface of the first light-transmitting plate 41. The light-absorbing layer 53 may be provided in a solid form over the entire non-corresponding region of the first surface (not shown), or may be provided at least in the non-corresponding region (first surface) on the side where the diffracted light travels. In the illustrated example, the light-absorbing layer 53 is provided not over the entire non-corresponding region, but only in the non-corresponding region on the side where the diffracted light travels. In other words, the light-absorbing layer 53 is provided in a portion of the non-corresponding region. Furthermore, an edge 53 a of the light-absorbing layer 53 provided on the first surface is located along or near the edge of the corresponding region.

[0038] 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.

[0039] 1 to 4 and 6, 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.

[0040] The light-absorbing layers 51 and 53 are provided to absorb the diffracted light before it is reflected. The purpose of providing the light-absorbing layers 51 and 53 will now be explained. 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 interface of the glass plate (the bottom surface in the illustrated example), and the reflected light (reflected diffracted light) may pass through the duplicate hologram again. If the reflected light passes through again, the interference fringes of the duplicate hologram will be disrupted, making it impossible to produce a duplicate hologram with interference fringes similar to those of the master hologram. Therefore, in this embodiment, light-absorbing layers are provided to absorb the diffracted light before it is reflected.

[0041] For this purpose, the light-absorbing layers 51, 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-absorbing 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-absorbing layer 53 is located along or near the edge of the corresponding area, by satisfying the relationship of the following formula (1), almost all of the diffracted light can be absorbed by the light-absorbing layers 51, 53 without internal reflection. 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.

[0042] Figure 8 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 8, coherent light L1 is shown by a solid line, and diffracted light L2 is shown by a dashed line.

[0043] As shown in FIG. 8 , 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. 8 , coherent light L1 incident from the corresponding region 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.

[0044] 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.

[0045] Furthermore, reflected light can be prevented from re-entering the duplicate hologram even when the relationship of the following formula (2) is satisfied: formula (2): h>d / 2 tan θ, where h, d, and θ are the same as in formula (1).

[0046] FIG. 9 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 dot-dash line. As shown in FIG. 9 , 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 diffracted light L2 is internally reflected at the air-interface of the corresponding region of the first light-transmitting plate 41 (generating reflected light L3). When the relationship of Equation (2) is satisfied, the reflected light L3 is less likely to be incident on the replica hologram. Specifically, as shown in FIG. 9 , a portion of 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 diffracted light L2 travels to the corresponding region on the first surface of the first light-transmitting plate 41, 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 is unlikely to be incident on the duplicate hologram 310 formed in the photosensitive layer 11, and instead 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.

[0047] 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."

[0048] (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).

[0049] 1 and 3, the light source D irradiates the laminate including the photosensitive layer 11 with coherent light L11 in the exposure section C. The light source D irradiates all of the master holograms 31 of the master layer 3 with the coherent light L11 simultaneously.

[0050] 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. There are also no particular limitations on the type of laser light, and examples include solid-state lasers, liquid lasers, gas lasers, and semiconductor lasers.

[0051] The light source D includes a laser oscillator 61, a reflector 62 that changes the direction of laser light from the laser oscillator 61 and causes the laser light to travel toward a laminate including a photosensitive layer 11, and various optical devices arranged between the laser oscillator 61 and the reflector 62.

[0052] 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.

[0053] In the illustrated example, the light source D has three laser oscillators 61 (a first oscillator 611, a second oscillator 612, and a third oscillator 613) that each emit coherent light of a different wavelength. For example, the first oscillator 611 is a red laser oscillator, the second oscillator 612 is a green laser oscillator, and the third oscillator 613 is a blue laser oscillator. The number of laser oscillators 61 provided in the light source D is not limited to three, and may be one, two, or four or more.

[0054] The reflector 62 is not particularly limited as long as it can reflect the laser light, which is coherent light, and for example, a mirror can be used. Examples of optical devices include a shutter, a magnifying lens, a collimating lens, a half-wave plate, a dielectric multilayer mirror, an achromatic lens, a mask member, and a beam splitter, and these can be appropriately selected and placed on the optical path. In order to simultaneously irradiate multiple master holograms 31 with coherent light, the laser light emitted from the laser oscillator 61 is magnified and flattened.

[0055] 3 shows one example of the configuration of the light source D. Arranged on the optical path of the first oscillator 611 are, in this order, a shutter 6111, a dielectric multilayer mirror 6112, a magnifying lens 6113, a collimating lens 6114, a half-wave plate 6115, and a dielectric multilayer mirror 6116. The red laser light emitted from the first oscillator 611 is magnified and flattened by the magnifying lens 6113 and the collimating lens 6114, has its polarization direction adjusted by the half-wave plate 6115, and is then reflected by the dielectric multilayer mirror 6116. The shutter is a device that controls the blocking and transmission of light, and the dielectric multilayer mirror is a device that reflects light of a specific wavelength with a high reflectance. On the optical path of the second oscillator 612, a shutter 6121, a dielectric multilayer mirror 6122, a magnifying lens 6123, a collimating lens 6124, a half-wave plate 6125, and a Dylomic mirror 6126 are arranged in this order. The green laser light emitted from the second oscillator 612 is similarly magnified and flattened and reflected by the Dylomic mirror 6126. The Dylomic mirror 6126 is a mirror that selectively reflects light of a specific wavelength, transmitting the red laser light and reflecting the green laser light. On the optical path of the third oscillator 613, a shutter 6131, a dielectric multilayer mirror 6132, a magnifying lens 6133, a collimating lens 6134, a half-wave plate 6135, and a Dylomic mirror 6136 are arranged in this order. The blue laser light emitted from the third oscillator 613 is similarly magnified and flattened and reflected by the Dylomic mirror 6136. The dylomic mirror 6136 is a mirror that selectively reflects light of a specific wavelength, and transmits red and green laser light and reflects blue laser light.

[0056] The red, green, and blue laser beams travel the same optical path after the Dylomic mirror 6136. A shutter 71, a magnifying lens 72, a collimating lens 73, and a broadband dielectric multilayer mirror 74 are provided after the Dylomic mirror 6136. The laser beams transmitted through or reflected by the Dylomic mirror 6136 are further expanded and collimated by the magnifying lens 72 and the collimating lens 73, and then reflected by the broadband dielectric multilayer mirror 74. A magnifying lens 75, a collimating lens 76, and a mask member 77 are provided after the broadband dielectric multilayer mirror 74. The laser beams reflected by the broadband dielectric multilayer mirror 74 are further expanded and collimated by the magnifying lens 75 and the collimating lens 76, and then pass through the mask member 77, where they are shaped into the shape of an opening 771 in the mask member 77. The mask member 77 blocks a portion of the laser beam, which is coherent light, and shapes the coherent light into a desired shape (the shape of the opening 771). In other words, the mask member 77 is a member that trims the expanded coherent light L12 emitted from the laser oscillator 61 and passes coherent light L11 of a desired shape. In this specification, the coherent light L11 after being trimmed to a desired shape by the mask member 77 is referred to as "trimmed light L11." In the illustrated example, the mask member 77 trims the expanded coherent light L12 into a rectangular shape in plan view that encompasses all of the master holograms 31, so that coherent light is irradiated simultaneously onto all of the master holograms 31 in the master layer 3.

[0057] The trimming light L11 is irradiated onto the master hologram 31. The trimming light L11 when irradiated onto the master hologram 31 is represented by a fine dashed line on the master layer 3 in FIG. 3 . A reflector 62 is provided to direct the trimming light L11 toward the master hologram 31. In this embodiment, for example, one reflector 62 is provided. The reflector 62 changes the traveling direction of the trimming light L11 obtained from the oscillator through the optical equipment toward the master hologram 31. Although not specifically shown, the laser oscillator 61, the magnifying lens, and other optical equipment that constitute the light source D, and the reflector 62 are fixed to a stage table (not shown) or the like that is provided on the frame of the manufacturing apparatus A.

[0058] {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. 11 , 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.

[0059] 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 4 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.

[0060] As shown in FIGS. 1 and 3 , trimming light L11 (coherent light) is irradiated onto all master holograms 31 from the first surface side of the light-transmitting plate 41 of this laminate, exposing the photosensitive layer 11 to duplicate holograms having interference fringes similar to those of the master holograms 31. The irradiation time of the trimming light L11 is until the exposure of the photosensitive layer 11 is complete for all master holograms 31. The irradiation time is appropriately set taking into consideration the output of the laser light from the oscillator, the magnification of the laser light, the size of the trimming light, and the like. Specifically, the energy intensity of the laser light is high at the center and decreases with increasing distance from the center. Therefore, the intensity of the trimming light at the edges is lower than that at the center. The irradiation time is set taking into consideration the cumulative exposure amount so that the photosensitive layer 11 can be sufficiently exposed near the edges of the trimming light L11 without being overexposed near the center of the trimming light L11. As will be described later, a duplicate hologram can be efficiently produced when the ratio of the intensity of the trimming light at the edge to the intensity of the trimming light at the center is 20% to 80%, or when the ratio of the effective area of ​​the trimming light to the area of ​​the expanded laser light immediately before passing through the mask member is 5% to 60%. The effective area of ​​the trimming light refers to the area of ​​the trimming light that can simultaneously make coherent light incident on multiple master holograms 31.

[0061] The coherent light 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 that is a mixture of at least two types of laser light selected from red, green, and blue laser light. For example, when the shutter 6111 of the first oscillator 611 is opened and the shutters 6121 and 6131 of the second oscillator 612 and the third oscillator 613 are closed, the red laser light from the first oscillator 611 is reflected by the reflectors 62 and irradiates all of the master holograms 31. In this case, a red replica hologram is created in the photosensitive layer 11. When the shutter 6121 of the second oscillator 612 is opened and the shutters 6111 and 6131 of the first oscillator 611 and the third oscillator 613 are closed, the green laser light from the second oscillator 612 is reflected by the reflectors 62 and irradiates all of the master holograms 31. In this case, a green duplicate hologram is created in the photosensitive layer 11. When the shutter 6131 of the third oscillator 613 is opened and the shutters 6111, 6121 of the first oscillator 611 and the second oscillator 612 are closed, the blue laser light from the third oscillator 613 is reflected by each reflector 62 and irradiated onto all of the master holograms 31. In this case, a blue duplicate hologram is created in the photosensitive layer 11. 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 created using laser light of the same wavelength as the laser light of the predetermined wavelength.

[0062] The trimming light L11 (coherent light) irradiated from the first surface side of the light-transmitting plate enters the light-transmitting plate (such as the first light-transmitting plate 41) through a corresponding region of the light-transmitting plate, passes through the photosensitive layer 11, and then enters the master hologram 31, generating diffracted light. The diffracted light then passes through the photosensitive layer 11, exposing the photosensitive layer 11. In other words, the interference fringes of the master hologram 31 are recorded in the photosensitive layer 11. The portion of the photosensitive layer 11 where the interference fringes are recorded becomes a duplicate hologram. Note that the trimming light L11 has a rectangular shape in a plan view that encompasses all of the master holograms 31, and therefore includes portions that extend beyond the corresponding regions corresponding to each master hologram 31. The light of the trimming light L11 that extends beyond the corresponding regions does not enter the master hologram 31 and does not generate diffracted light. Therefore, interference fringes are not recorded in the photosensitive layer 11 through which the extended light passes. Alternatively, the excess light is absorbed by the light absorption layer 53 and the master light absorption layer 35, and therefore no interference fringes are recorded in the photosensitive layer 11. Therefore, by simultaneously irradiating all of the master holograms 31 with the trimming light L11, duplicate holograms of approximately the same shape, size, and number as each master hologram 31 are produced in the photosensitive layer 11.

[0063] As described above, the provision of light-absorbing layers 51, 53 on the light-transmitting plate prevents reflected diffracted light from entering the duplicate hologram, thereby ensuring the production of duplicate holograms having interference fringes similar to those of master hologram 31. In particular, the provision of light-absorbing layers 51, 53 on at least one of the end faces of each light-transmitting plate on the side along which the diffracted light travels also prevents the diffracted light from entering duplicate holograms adjacent to each other in the transport direction.

[0064] After the trimming light L11 is irradiated in this manner to create duplicate holograms corresponding to all of the master holograms 31 in the photosensitive layer 11, the irradiation of the trimming light L11 from the light source D is stopped. For example, the shutter 71 is closed or the laser oscillator 61 is stopped from emitting light to prevent the coherent light from traveling toward the reflector 62. Next, the moving mechanism 382 is used to separate the master layer 3 from the support substrate 12 of the workpiece 1. After the master layer 3 is 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).

[0065] 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).

[0066] The exposed workpiece 1 is transported and stopped, returning to the state shown in FIG. 11 . 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 workpiece 1, exposed to trimming light L11, and duplicate holograms corresponding to all the master holograms 31 are created in the photosensitive layer 11. The master layer 3 is then released, the workpiece 1 is transported a predetermined length, and the process is then stopped. This process is repeated. In this manner, duplicate holograms can be efficiently and continuously created. According to the present invention, coherent light is simultaneously irradiated onto all master holograms 31 in the master layer 3, thereby enabling the creation of multiple duplicate holograms in the photosensitive layer 11, the same number as the master holograms 31. When creating a duplicate hologram by irradiating a single master hologram with laser light, as in the conventional method, a repeating process of laser light irradiation, master hologram movement, photosensitive layer transport, and master hologram contact is required. Conventionally, only one duplicate hologram could be produced per repeat operation, and producing multiple duplicate holograms required a relatively long time. In contrast, the present invention makes it possible to simultaneously produce multiple duplicate holograms by irradiating multiple master holograms 31 with coherent light. This allows multiple duplicate holograms to be produced per repeat operation, which involves irradiating coherent light, moving the master layer, transporting the photosensitive layer, and then adhering the master layer, thereby enabling efficient production of duplicate holograms.

[0067] Figure 12(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 replicate hologram continuum 100 in Figure 12 has a plurality of replicated holograms 310 arranged in three rows.

[0068] 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.

[0069] 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 12(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.

[0070] <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.

[0071] For example, the above-mentioned 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. 13, a red duplicate hologram 310R consisting of incoupling 311R and outcoupling 312R, a green duplicate hologram 310G consisting of incoupling 311G and outcoupling 312G, and a blue duplicate hologram 310B consisting of incoupling 311B and outcoupling 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.

[0072] 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).

[0073] Second Embodiment In the first embodiment, the trimming light L11 is shaped into a substantially rectangular shape that encompasses all of the master holograms 31. However, as shown in Fig. 14, for example, coherent light L12 emitted from a laser oscillator 61 and expanded and flattened may be trimmed into the same number of trimming light beams L111 as the number of master holograms 31. In Fig. 14, a mask member 77 is provided with the same number of openings 772 as the number of master holograms 31, and the expanded and flattened coherent light L12 that passes through the mask member 77 is split into the same number of trimming light beams L111 as the number of master holograms 31 and each having substantially the same shape as the master hologram 31 in a planar view. The trimming light L111 when irradiated onto the master hologram 31 is represented by a fine dashed line on the master layer 3 in Fig. 12. In the above description, the coherent light L12 emitted from the laser oscillator 61 and expanded and flattened is trimmed by the mask member 77, but it is also possible (without providing the mask member 77) to irradiate all of the master holograms 31 with substantially circular coherent light L12 (not shown). Furthermore, in the above description, the mask member 77 is disposed between the laser oscillator 61 and the reflector 62, but it is also possible (not shown) to dispose the mask member 77 between the reflector 62 and the photosensitive layer 11.

[0074] [Third 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. 15 , 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).

[0075] Furthermore, while the first embodiment uses multiple separate light-transmitting plates, a single light-transmitting plate 44 may be used, as shown in FIG. 16 . 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-corresponding area 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. 15 , 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 on its first surface with a dimension equal to or greater than the dimension d of the coherent light, 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.

[0076] [Fourth 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. 17, 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.

[0077] Fifth Embodiment 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 below the exposure unit C. Furthermore, the first embodiment illustrates a case in which coherent light 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 limited to this. The coherent light 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.

[0078] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0079] Example 1 Preparation of Material to be Processed A material to be processed was prepared by coating a triacetyl cellulose film with a photopolymer to form a 16 μm-thick photosensitive layer on a support substrate. Preparation of Master Layer As shown in FIG. 18(a), a single master hologram 31-E was formed within a square frame 81-E measuring 50 mm x 50 mm. As shown in the figure, the master hologram 31-E was a square slightly smaller than the frame 81-E indicated by the dashed line. Note that the frame 81-E indicated by the dashed line in FIG. 18 is shown for convenience of explanation only, and the frame 81-E does not actually exist. The master layer used in Example 1 was one in which the master hologram units were arranged in 6 rows and 6 columns, as shown in FIG. 18(b).

[0080] <Exposure> A master layer having the 6 rows x 6 columns of master holograms, the substrate, and a 30 mm-thick glass plate were bonded together via index oil to form a laminate consisting of master layer / index oil / support substrate / photosensitive layer / glass plate. The photosensitive layer was exposed by simultaneously irradiating all master holograms with trimming light from the glass plate side of this laminate for a predetermined period of time. This exposure produced the same number of duplicate holograms (36) in the photosensitive layer as the master holograms. The trimming light was obtained by stepwise expanding and collimating laser light emitted from a 532 nm laser oscillator (manufactured by Cobolt under the trade name "Cobolt 05-01 Series Samba") multiple times, and then passing the expanded and collimated laser light through a mask member. Figure 19 shows the shapes of the expanded and collimated laser light L12-E and trimming light L11-E immediately before passing through the mask member. Hereinafter, the expanded and collimated laser light immediately before passing through the mask member will be referred to as "expanded laser light." The expanded laser light L12-E was circular with a diameter D1-E, and the trimming light L11-E was square with a side 82-E. The center O of the expanded laser light L12-E and the center O of the trimming light L11-E coincided. The circle L13-E represented by the fine dashed line is a circle passing through the four corners 83-E of the trimming light L11-E. <Exposure conditions> Oscillator output: 500 mW. Diameter of the laser light before expansion: 3 mm. Laser light expansion magnification: 327 times. Diameter D1-E of the expanded laser light L12-E: 980 mm. One side 82-E of the trimming light L11-E: 300 mm. Irradiation time (exposure time): 115 seconds. The irradiation time is set so that the cumulative exposure of the trimming light L11-E at the corner 83-E is 20 mJ / cm ２ The cumulative exposure dose is 20 mJ / cm. ２ It has been empirically found that if the above conditions are met, the photosensitive layer can be exposed sufficiently and a good hologram replica can be produced.

[0081]

[0082] [Examples 2 to 6] The photosensitive layers were exposed by simultaneously irradiating all master holograms with trimming light for a predetermined period of time in the same manner as in Example 1, except that the arrangement of the master holograms and the exposure conditions were changed as shown in Table 1. In each of Examples 2 to 6, nine duplicate holograms were produced.

[0083] In Table 1, "effective area of ​​trimming light / area of ​​magnified laser light (%)" refers to the ratio of the effective area of ​​the trimming light to the area of ​​the laser light (coherent light) immediately before passing through the mask member. The effective area of ​​the trimming light is the area of ​​the trimming light that allows coherent light to be incident simultaneously on multiple master holograms 31. When multiple master hologram units are arranged vertically and horizontally, as in this embodiment, the effective area of ​​the trimming light is the area enclosed by lines connecting the outer edges of the outermost master holograms. In this embodiment, the area of ​​the trimming light and the area enclosed by lines connecting the outer edges of the outermost master holograms are substantially the same. For example, trimming light having the shape of a circle L13-E, represented by the fine dashed line in FIG. 19, can also be used as the trimming light. Whether the circular trimming light L13-E or the rectangular trimming light L11-E is used, all master holograms can be irradiated simultaneously, and the cumulative exposure dose remains unchanged. In other words, the effective area of ​​the circular trimming light L13-E is the same as the effective area of ​​the rectangular trimming light L11-E (the area of ​​the range surrounded by the lines connecting the outer edges of the outermost master holograms).

[0084] In Table 1, "corner energy intensity / center energy intensity (%)" refers to the ratio of the intensity of the trimming light at the edge (corner) to the intensity of the trimming light at the center. The intensity ratio and the energy intensity at the center and corner of the trimming light were calculated by measuring the energy intensity at the center and assuming that the energy intensity of the laser light follows a Gaussian distribution. The energy intensity and intensity ratio at the corner were calculated from the energy intensity at the center. The values ​​for the center and corner energy intensities in Table 1 are measured and calculated values ​​rounded to the nearest tenth. On the other hand, the values ​​for the corner energy intensity / center energy intensity in Table 1 are measured and calculated values ​​that are not rounded. Therefore, please note that the values ​​obtained by simply dividing the center and corner intensity values ​​in Table 1 do not match the energy intensity / center energy intensity values ​​in Table 1.

[0085] [Evaluation] The "irradiation time per replicate hologram" in Table 1 was calculated by dividing the irradiation time of the trimming light by the number of replicate holograms obtained. All of the replicate holograms obtained in Examples 1 to 6 had good interference fringes. Specifically, of the 36 replicate holograms obtained in Example 1, both the central replicate hologram (the replicate hologram produced by irradiating the trimming light near the center) and the corner replicate holograms (the replicate holograms produced by irradiating the trimming light near the corners) had good interference fringes. The same was true for Examples 2 to 6.

[0086] As shown in Table 1, Examples 1 and 3 to 5 require less time to produce one duplicate hologram than Examples 2 and 6. Therefore, when producing the same number of duplicate holograms, Examples 1 and 3 to 5 complete the process in less time than Examples 2 and 6. Comparing Examples 1 and 3 to 5 with Examples 2 and 6 reveals that the time required to produce one duplicate hologram can be shortened by setting the ratio of the effective area of ​​the trimming light to the area of ​​the expanded laser light immediately before passing through the mask member to within a range of 5% to 60%, preferably within a range of 7% to 50%, and more preferably within a range of 10% to 40%. Furthermore, the time required to produce one duplicate hologram can be shortened by setting the ratio of the energy intensity of the edge of the trimming light to the energy intensity of the center of the trimming light to within a range of 20% to 80%, preferably within a range of 25% to 75%, and more preferably within a range of 30% to 71%.

[0087] A Hologram manufacturing apparatus B Conveying section of manufacturing apparatus C Exposure section of manufacturing apparatus D Light source of manufacturing apparatus L1 Coherent light L2 Diffracted light L11, L111 Trimming light L12 Coherent light immediately before trimming 11 Photosensitive layer 3 Master layer 31 Master hologram 41, 42, 43 Light-transmitting plates 51, 53 Light-absorbing layers 61 Laser oscillator 613 Third oscillator 62 Reflector 77 Mask member

Claims

1. A hologram manufacturing apparatus comprising: an exposure unit having a master layer having a master hologram; a transport unit that transports an unexposed photosensitive layer and positions the photosensitive layer on the first surface side of the master layer in the exposure unit; and a light source that irradiates the master hologram with coherent light from the first surface side of the photosensitive layer, wherein the coherent light and diffracted light generated from the master hologram by irradiating the coherent light through the photosensitive layer to expose the photosensitive layer, thereby replicating interference fringes of the master hologram on the photosensitive layer, wherein the master layer has a plurality of master holograms, and the light source irradiates all of the master holograms in the master layer with coherent light simultaneously.

2. A hologram manufacturing device as described in claim 1, wherein the photosensitive layer is in the form of a long strip, the plurality of master holograms are arranged in a plurality of columns in the width direction of the photosensitive layer and in a plurality of rows in the transport direction which is a direction perpendicular to the width direction, and the transport unit transports the long strip-shaped photosensitive layer in the longitudinal direction by a predetermined length and then stops transporting the photosensitive layer.

3. A hologram manufacturing device as described in claim 1, wherein the light source has a mask member that trims the expanded and flattened coherent light, the trimming light that has passed through the mask member is irradiated simultaneously onto all master holograms in the master layer, and the ratio of the intensity of the edge of the trimming light to the intensity of the center of the trimming light is 20% to 80%.

4. A hologram manufacturing device as described in claim 1, wherein the light source has a mask member that trims the expanded and flattened coherent light, the trimming light that has passed through the mask member is irradiated simultaneously onto all master holograms in the master layer, and the ratio of the effective area of ​​the trimming light to the area of ​​the coherent light immediately before passing through the mask member is 5% to 60%.

5. A hologram manufacturing apparatus as described in claim 3 or 4, wherein the light source further comprises an oscillator of the coherent light and a reflector that changes the direction of the light toward the master hologram, and the mask member is disposed between the oscillator and the reflector or between the reflector and the photosensitive layer.

6. A method for manufacturing a hologram, comprising: a transport step of transporting an unexposed photosensitive layer to the first surface side of a master layer having a master hologram; and an exposure step of irradiating the first surface side of the photosensitive layer with coherent light after placing the photosensitive layer on the first surface side of the master layer, wherein 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 photosensitive layer, thereby replicating interference fringes of the master hologram in the photosensitive layer, wherein the master layer has a plurality of master holograms, and in the exposure step, the coherent light is irradiated simultaneously onto all of the master holograms in the master layer.

7. A method for producing a hologram as described in claim 6, wherein the trimming is performed by passing expanded and flattened coherent light through a mask member, and the trimming light that has passed through the mask member and been trimmed is simultaneously irradiated onto all master holograms in the master layer, and the ratio of the intensity of the trimming light at the edge to the intensity of the trimming light at the center is 20% to 80%.

8. A method for producing a hologram as described in claim 6, wherein the trimming is performed by passing the expanded and flattened coherent light through a mask member, and the trimming light obtained by passing through the mask member is simultaneously irradiated onto all master holograms in the master layer, and the ratio of the effective area of ​​the trimming light to the area of ​​the coherent light immediately before passing through the mask member is 5% to 60%.

9. A light guide plate having a hologram manufactured by the manufacturing method according to any one of claims 6 to 8.

10. A light guide plate having a hologram manufactured by the manufacturing apparatus according to any one of claims 1 to 5.

Images