Device for producing hologram, method for producing hologram, and light guide plate

Abstract

In the present invention, a master hologram is used to efficiently manufacture, in a photosensitive layer, a hologram having a plurality of interference fringes. This device comprises: an exposure unit C that includes a master layer 3 having a master hologram 31; a transport unit B for transmitting an unexposed photosensitive layer 11 and causing the photosensitive layer 11 to be arranged on a first surface side of the master layer 3 of the exposure unit C; and a light source D for irradiating the master hologram 31 with coherent light from the first surface side of the photosensitive layer 11. The device replicates interference fringes of the master hologram 31 in the photosensitive layer 11 by exposure in which the coherent light and also diffracted light produced from the master hologram due to the irradiation with the coherent light are transmitted through the photosensitive layer 11. The light source D is able to irradiate the master hologram with at least two beams of coherent light that advance in different directions.

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] Light guide plates having holograms are used in, for example, AR (Augmented Reality) devices. For example, the light guide plate has a hologram on the input side, called the incoupling, and a hologram on the output side, called the outcoupling. When reconstruction light is incident on the incoupling, diffracted light is generated, and the diffracted light is reflected and propagated inside the light guide plate and output from the outcoupling. When the output diffracted light enters the eye of an observer looking at the outcoupling, the observer recognizes an image represented by the diffracted light.

[0003] Another known method for manufacturing holograms is to use a master hologram to optically replicate the interference fringes of the master hologram onto a photosensitive layer. Briefly, as shown in FIG. 22 , 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.

[0004] 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.

[0005] Japanese Patent Application Publication No. 5-249876

[0006] As described above, the reconstructed light incident from the incoupling is diffracted and exits from the outcoupling, allowing an observer viewing the outcoupling to recognize the light. However, if the observer's line of sight is misaligned with the direction of travel of the emitted diffracted light (for example, if the observer views the outcoupling at an angle), the observer will see a blurred or no image. In this regard, the range in which the image can be viewed can be expanded by using a hologram having multiple interference fringes that generate multiple diffracted light beams with different diffraction angles. In other words, by using a hologram having multiple interference fringes, diffracted light beams traveling in multiple directions (multiple light beams with different exit angles) can be emitted from the outcoupling, increasing the opportunities for the diffracted light beams to travel along the observer's line of sight, thereby expanding the range in which the image represented by the diffracted light can be viewed (i.e., widening the viewing angle). A method for industrially mass-producing such holograms having multiple different interference fringes is desired. However, Patent Document 1 does not disclose or suggest any method for producing a hologram having multiple different interference fringes.

[0007] An object of the present invention is to provide a hologram manufacturing apparatus and method that can efficiently produce a hologram having a plurality of interference fringes in a photosensitive layer using a master hologram.

[0008] 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, thereby replicating interference fringes of the master hologram onto the photosensitive layer, wherein the light source is capable of irradiating the master hologram with at least two coherent light beams traveling in different directions.

[0009] A second aspect of the hologram manufacturing apparatus is the same as the first aspect, except that the at least two coherent light beams have the same wavelength.A third aspect of the hologram manufacturing apparatus is the first or second aspect, except that the light source has a coherent light oscillator and a reflector that reflects the coherent light from the oscillator, and the reflector is adjustable so that the first coherent light beam travels toward the master hologram and the second coherent light beam travels toward the master hologram in a direction different from that of the first coherent light.A fourth aspect of the hologram manufacturing apparatus is the third aspect, except that the angle between the traveling direction of the first coherent light beam and the traveling direction of the second coherent light beam is 5 to 40 degrees. A fifth embodiment of the hologram manufacturing apparatus is the manufacturing apparatus of any one of the first to fourth embodiments, wherein the photosensitive layer is in the form of a long strip, and the conveying unit conveys the long strip-shaped photosensitive layer in the longitudinal direction by a predetermined length and then stops conveying the photosensitive layer. A sixth aspect of the hologram manufacturing apparatus is the manufacturing apparatus of any of the first to fifth aspects, wherein the master layer has a plurality of master holograms arranged in a plurality of columns in the width direction and a plurality of rows in a transport direction that is perpendicular to the width direction; the photosensitive layer is in the form of a long strip; the transport unit transports the long strip of photosensitive layer a predetermined length in the longitudinal direction and then stops transporting the photosensitive layer; the light source has a position change mechanism that is capable of changing the irradiation position between a first position at which at least two coherent light beams traveling in different directions are irradiated onto a plurality of master holograms extending in one row or one column, and a second position at which at least two coherent light beams traveling in different directions are irradiated onto a plurality of master holograms extending in another row or another column.

[0010] In another aspect, there is provided a seventh aspect of a method for manufacturing a hologram, the method 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 arranging 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 onto the photosensitive layer, in which the master hologram is irradiated with at least two coherent light beams traveling in different directions.

[0011] A hologram manufacturing method of an eighth aspect is the manufacturing method of the seventh aspect, wherein the master hologram is irradiated with three or more coherent light beams traveling in different directions.A hologram manufacturing method of a ninth aspect is the manufacturing method of the seventh or eighth aspect, wherein the coherent light beams are red laser light, green laser light, blue laser light, or composite laser light containing at least two kinds of laser light selected from red laser light, green laser light, and blue laser light.

[0012] According to the manufacturing apparatus and manufacturing method of the present invention, a hologram having a plurality of interference fringes can be efficiently produced in a photosensitive layer using a master hologram.

[0013] 1 is a side view of a hologram manufacturing apparatus according to a first embodiment; a plan view of an exposure unit of the manufacturing apparatus; a perspective view of the exposure unit and light source of the manufacturing apparatus; an enlarged cross-sectional view taken along line IV-IV in FIG. 2; a bottom view of the master layer, as viewed from the first surface side; a bottom view of a light-transmitting plate, as viewed from the bottom side; a perspective view of a first light-transmitting plate of the light-transmitting plate, as viewed from the bottom side; a reference side view of a reflector of the exposure unit and light source; a reference view illustrating a method of manufacturing a master hologram; a reference view illustrating a state when a master hologram is irradiated with reproduction light; a side view of a manufacturing apparatus for explaining steps in a method of manufacturing a hologram; a reference side view illustrating a state when a first coherent light is irradiated; a reference side view illustrating a state when a second coherent light is irradiated; a reference side view illustrating a state when a third coherent light is irradiated; a perspective view of a manufacturing apparatus for explaining steps in the manufacturing method; a plan view of a replica hologram continuum in which holograms are continuously manufactured. 10A and 10B are a reference side view of a light guide plate; a perspective view of an exposure unit and a light source according to a second embodiment; a perspective view of a light source according to a third embodiment; a perspective view of a light source according to a fourth embodiment; (a) is a reference side view of an exposure unit according to a first example of a fifth embodiment, and (b) is a reference side view of an exposure unit according to a second example of the same; and (b) is a reference side view of an exposure unit according to a second example of the same. Reference diagrams for explaining a conventional method of replicating a hologram.

[0014] [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.

[0015] {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.

[0016] The hologram manufacturing apparatus has a light source that irradiates a master hologram with multiple coherent light beams traveling in different directions. The coherent light beams and diffracted light beams generated from the master hologram by the irradiation of the coherent light beams are transmitted through a photosensitive layer to expose the master hologram, thereby recording interference fringes of the master hologram in the photosensitive layer and replicating the hologram in the photosensitive layer. In this specification, the hologram replicated in the photosensitive layer may be referred to as a "replica hologram." The light source irradiates the master hologram with at least two or more coherent light beams that have different angles of incidence with respect to the master hologram. Here, the angle of incidence refers to the angle of the light beam's propagation direction relative to the normal to the first surface of the master hologram.

[0017] The photosensitive layer used in the manufacturing apparatus may be in the form of a sheet, but is preferably in the form of a long strip. By loading a long strip of photosensitive layer into the manufacturing apparatus and exposing the photosensitive layer using the manufacturing apparatus, multiple replica 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 sufficiently longer than its lateral length. A long strip of photosensitive layer is usually wound up on a roll for storage and unwound from the roll when used. A manufacturing apparatus for producing replica holograms in a long strip of photosensitive layer will be specifically described below.

[0018] 1 to 4, manufacturing apparatus A has a transport section B that transports photosensitive layer 11 in the longitudinal direction, an exposure section C that exposes photosensitive layer 11 transported by transport section B, and a light source D that irradiates a laminate including photosensitive layer 11 with coherent light 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 transport photosensitive layer 11 to exposure section C, expose photosensitive layer 11 to light in exposure section C to form a duplicate hologram, and then transport photosensitive layer 11 again, repeating this process to continuously produce a plurality of duplicate holograms.

[0019] <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."

[0020] The long strip-shaped material 1 to be treated may be wound into a roll for storage, transportation, etc. However, it is preferable to attach a protective film 15 or the like to the material 1 to prevent scratches on the support substrate 12 and the photosensitive layer 11. For example, an adhesive-backed protective film 15 is attached to the support substrate 12 side of the material 1 to be treated. A release liner 16 is attached to the photosensitive layer 11 side of the material 1 to be treated. The release liner 16 is then attached for two purposes. One is to protect the photosensitive layer 11. The other is to conceal the slight adhesiveness of the photosensitive layer 11, which has slight adhesiveness, and prevent blocking when the material 1 is wound into a roll. In this way, the 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 21 of the manufacturing apparatus A.

[0021] <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.

[0022] 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.

[0023] 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.

[0024] <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.

[0025] (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.

[0026] 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 in the width direction and n rows 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 on the master layer 3, arranged 3 x 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.

[0027] Here, we will briefly explain how to fabricate a master layer containing a master hologram. A master hologram can be fabricated using a conventionally known method. FIG. 9 is a reference diagram schematically illustrating the process of fabricating a master hologram. As shown in FIG. 9( a), a photosensitive layer 1100 made of a photosensitive material is prepared. Examples of the photosensitive material that can be used include photopolymer, photoresist, silver halide emulsion, and dichromated gelatin. In the illustrated example, the photosensitive layer 1100 is interposed between the first and second substrates 3200 and 3300. However, the master hologram may be fabricated using only the photosensitive layer 1100, or using a substrate in which the photosensitive layer 1100 is provided on the first substrate 3200. Next, laser light IL1 (hereinafter referred to as first light IL1) of a predetermined wavelength is irradiated onto the photosensitive layer 1100 from two different directions (a direction forming an angle α1 with respect to the XZ plane and a direction forming an angle β1 with respect to the XZ plane). The XZ plane includes a normal direction NR, which is a line perpendicular to the surface of the photosensitive layer 1100. The angle α1 corresponds to the angle of incidence of the first light IL1 incident from the first surface side of the photosensitive layer 1100, and the angle β1 corresponds to the angle of incidence of the first light IL1 incident from the second surface side of the photosensitive layer 1100. Specifically, by irradiating the photosensitive layer 1100 with interference light of the first light IL1 of a predetermined wavelength from two directions, the monomer component in the irradiated portion of the photosensitive layer 1100 is diffused, resulting in a refractive index distribution. As a result, interference fringes that depend on the angle of the first light IL1 are recorded in the irradiated portion. In order to maintain coherence, it is preferable that the first light IL1 of the predetermined wavelength is obtained by splitting light emitted from the same laser oscillator using a polarizing beam splitter, rotating the polarization axis of one of the split light beams using a half-wave plate to match the polarization axis of the other light beam, and then magnifying and flattening the light using a magnifying lens and a collimating lens, respectively, before irradiating it from two directions.

[0028] Furthermore, as shown in FIG. 1B, laser light IL2 of a predetermined wavelength (hereinafter, referred to as second light IL2) is irradiated onto the photosensitive layer 1100 from two different directions (a direction forming an angle α2 with respect to the XZ plane and a direction forming an angle β2 with respect to the XZ plane). The angle α2 corresponds to the angle of incidence of the second light IL2 incident from the first surface side of the photosensitive layer 1100, and the angle β2 corresponds to the angle of incidence of the second light IL2 incident from the second surface side of the photosensitive layer 1100. However, since FIG. 1B illustrates a case where the angle of incidence α2 is parallel to the normal direction (angle of incidence α2 = 0 degrees), the symbol α2 is not shown. The angles of incidence α2 and β2 are different from the angles of incidence α1 and β1. Furthermore, it is preferable that the second light IL2 be light of the same wavelength as the first light IL1. By irradiating the photosensitive layer 1100 with the second light IL2, interference fringes that depend on the angle of the second light IL2 are recorded in the irradiated portion. As with the first light IL1, it is preferable that the second light IL2 is also irradiated from two directions after being branched from light emitted from the same laser oscillator and expanded and flattened.

[0029] Furthermore, as shown in FIG. 1C , laser light IL3 of a predetermined wavelength (hereinafter, third light IL3) is irradiated onto the photosensitive layer 1100 from two different directions (a direction forming an angle α3 with respect to the XZ plane and a direction forming an angle β3 with respect to the XZ plane). The angle α3 corresponds to the angle of incidence of the third light IL3 incident from the first surface side of the photosensitive layer 1100, and the angle β3 corresponds to the angle of incidence of the third light IL3 incident from the second surface side of the photosensitive layer 1100. The angles of incidence α3 and β3 are different from the angles of incidence α1, α2, and β1, β2. It is preferable that the third light IL3 be light of the same wavelength as the first light IL1. By irradiating the photosensitive layer 1100 with the third light IL3, interference fringes dependent on the angle of the third light IL3 are recorded in the irradiated portion. As with the first light IL1, it is preferable that the third light IL3 be irradiated from two directions after branching light emitted from the same laser oscillator, expanding and flattening the light, etc. In this way, a master hologram 3100 in which three angles are recorded can be produced in the photosensitive layer 11.

[0030] 10, when a first reconstructed beam IL1-1 having the same wavelength and the same incident angle α1 as the first light IL1 is incident on the master hologram 3100, the master hologram 3100 produces a first diffracted beam IL1-2 having the same diffraction angle β1 as the angle β1. When a second reconstructed beam IL2-1 having the same wavelength and the same incident angle α2 as the second light IL2 is incident on the master hologram 3100, the master hologram 3100 produces a second diffracted beam IL2-2 having the same diffraction angle β2 as the angle β2. When a third reconstructed beam IL3-1 having the same wavelength and the same incident angle α3 as the third light IL3 is incident on the master hologram 3100, the master hologram 3100 produces a third diffracted beam IL3-2 having the same diffraction angle β3 as the angle β3. When red-wavelength laser light is used as the first to third light IL1, IL2, and IL3, a red master hologram that generates three diffracted beams is generated; when green-wavelength laser light is used, a green master hologram that generates three diffracted beams is generated; and when blue-wavelength light is used, a blue master hologram that generates three diffracted beams is generated. When three laser beams including red-wavelength laser light, green-wavelength laser light, and blue laser light are used as the first to third light IL1, IL2, and IL3, a red master hologram, a green master hologram, and a blue master hologram that generate three diffracted beams are generated in multiplex. Note that, although the above example illustrates a case in which a photosensitive layer is exposed using three beams of light traveling in different directions, a master hologram may also be produced by irradiating the photosensitive layer with two beams of light traveling in different directions or four or more beams of light traveling in different directions.

[0031] 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 coherent light when a portion of the light passes through the master hologram 31. The master light-absorbing layer 35 is also provided to absorb the coherent light when the coherent light passes through an area not including the master hologram 31.

[0032] 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.

[0033] 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.

[0034] (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.

[0035] 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.

[0036] 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.

[0037] 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."

[0038] 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.

[0039] 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.

[0040] Furthermore, a light-absorbing layer 53 is also provided on the first surface of the first light-transmitting plate 41. However, in order to allow coherent light to be incident on the master hologram 31 from the first surface side of the first light-transmitting plate 41, the light-absorbing layer 53 is provided in an area of ​​the first surface of the first light-transmitting plate 41 other than an area where at least two coherent light beams with different propagation directions are incident on the master hologram 31. Hereinafter, the "area where coherent light is incident on the master hologram 31" will be referred to as the "incident area," and the "area other than the area where at least two coherent light beams with different propagation directions are incident on the master hologram 31" will be referred to as the "non-incident area." The light-absorbing layer 53 may be provided in a solid form over the entire non-incident area of ​​the first surface (not shown), or may be provided at least in the non-incident area (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-incident area, but only in the non-incident area on the side where the diffracted light travels. That is, the light absorption layer 53 is provided in a part of the non-incident region. In addition, the edge 53 a of the light absorption layer 53 provided on the first surface is located along the edge of the incident region or in the vicinity of the edge of the incident region.

[0041] 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.

[0042] 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.

[0043] The light-absorbing layers 51 and 53 are provided to absorb the diffracted light generated by the master hologram 31 after it passes through the photosensitive layer 11. Here, the purpose of providing the light-absorbing layers 51 and 53 will be explained. As shown in FIG. 22 , 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, the light-absorbing layers 51 and 53 are provided to absorb the diffracted light. 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.

[0044] (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).

[0045] <Light Source> Figure 8 is a reference side view showing the exposure unit and the reflector of the light source. Hereinafter, the term "reference side view" refers to a perspective view showing the internal state of the components of the exposure unit C (e.g., light-transmitting plates 41, 42, and 43, master layer 3, etc.) as viewed from the side. With reference to Figures 1, 3, and 8, in the exposure unit C, light source D irradiates master hologram 31 from the first surface side of light-transmitting plates 41, 42, and 43 with at least two coherent light beams traveling in different directions. Light source D also includes a position change mechanism 63 that changes the irradiation position of the coherent light on master hologram 31. The position change mechanism 63 changes the irradiation position between a first position where the coherent light is irradiated onto a plurality of master holograms 31 extending in one row and a second position where the coherent light is irradiated onto a plurality of master holograms 31 extending in another row.

[0046] 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 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.

[0047] The light source D includes a laser oscillator 61, a reflector 62 that changes the direction of laser light emitted from the laser oscillator 61 and directs the laser light toward a laminate including the photosensitive layer 11, and various optical devices disposed between the laser oscillator 61 and the reflector 62. The reflector 62 has a reflecting surface 62a that reflects coherent light. The reflector 62 is configured so that at least the angle of the reflecting surface 62a can be adjusted. Furthermore, the reflector 62 is equipped with a position changing mechanism 63.

[0048] 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.

[0049] 3, the light source D has three laser oscillators 61 (a first oscillator 611, a second oscillator 612, and a third laser oscillator 613) that emit coherent light beams of different wavelengths. 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.

[0050] The reflector 62 is not particularly limited as long as it can reflect the laser beam, which is coherent light, and may be, for example, a mirror. Examples of optical devices include a shutter, a magnifying lens, a collimating lens, a half-wave plate, a dielectric multilayer mirror, and a beam splitter, and any of these may be appropriately selected and placed on the optical path.

[0051] 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. Red laser light of a predetermined wavelength 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. Green laser light of a predetermined wavelength 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 red laser light and reflecting 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 of a predetermined wavelength emitted from the third oscillator 613 is similarly expanded 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 lights and reflects blue laser light.

[0052] Furthermore, the red, green, and blue laser beams travel the same optical path after the Dylomic mirror 6136. A shutter 71 and a broadband dielectric multilayer mirror 72 are provided after the Dylomic mirror 6136. The laser beam reflected by the mirror 72 is split into multiple beams. The laser beam is split into the same number of beams as the number of master holograms 31 in one row. In other words, the laser beam is split into the same number of beams as the number of columns of master holograms 31 in the master layer 3. As described above, the master layer 3 has three columns of master holograms 31 (three per row), so the laser beam reflected by the broadband dielectric multilayer mirror 72 is split into three beams. For example, a first polarizing beam splitter 731, a second polarizing beam splitter 732, and a broadband dielectric multilayer mirror 74 are provided to split the laser beam. A half-wave plate 75, a magnifying lens 76, and a collimating lens 77 are provided after the first polarizing beam splitter 731, the second polarizing beam splitter 732, and the wideband dielectric multilayer mirror 74, respectively. The laser light reflected by the wideband dielectric multilayer mirror 72 is split by the first polarizing beam splitter 731 into P waves and S waves at a ratio depending on the orientation at the half-wave plates 6115, 6125, and 6135. The split S waves proceed to the half-wave plate 75, where their polarization orientation is adjusted, and then expanded and collimated by the magnifying lens 76 and the collimating lens 77. The split P waves proceed to the half-wave plate 78, where their polarization orientation is adjusted, and then expanded by the second polarizing beam splitter 732 into P waves and S waves at a ratio depending on the orientation at the half-wave plate. The split S waves proceed to the half-wave plate 75, where they are expanded and collimated. The branched P wave is reflected by a wideband dielectric multilayer mirror 74, and then travels to a half-wave plate 75 where it is expanded and collimated.

[0053] Each of the multiple laser beams thus branched is irradiated onto the master hologram 31. Reflectors 62 are provided to direct each laser beam toward the master hologram 31. In this embodiment, the number of reflectors 62 provided is the same as the number of laser beams (the number of columns of the master hologram 31). In the illustrated example, three reflectors 62 are provided. Each reflector 62 changes the direction of laser beams traveling from the oscillator through the optical device to the collimator lens 77 toward the master hologram 31. A shaping mask member 79 is disposed between the collimator lens 77 and the reflector 62. The expanded and parallel laser beam (coherent light) has a circular shape, but by passing through the mask member 79, it is shaped to the shape of the opening 791 of the mask member 79. For example, the laser beam is shaped through the mask member 79 into a shape substantially identical to that of the master hologram 31. In the illustrated example, since the master hologram 31 has a rectangular shape in a plan view, the laser light is shaped into a substantially rectangular shape, for example, substantially the same shape and size as the master hologram 31 .

[0054] In order to change the irradiation position of the laser light, the light source D is provided with a position change mechanism 63. For example, the position change mechanism 63 is provided on the reflector 62. In this embodiment, a plurality of reflectors 62 are provided, and each of the reflectors 62 is provided with a position change mechanism 63. The position change mechanism 63 includes a fixed unit 631, a moving unit 632, and a drive unit (not shown) that moves the moving unit 632 relative to the fixed unit 631. The fixed unit 631 is, for example, a uniaxial stage, and is fixed to the frame (not shown) of the manufacturing apparatus A. Note that, although not specifically shown, the components of the light source D other than the moving unit 632 (such as the oscillator 61) are fixed to a stage base (not shown) or the like provided on the frame of the manufacturing apparatus A. A support unit 65 is provided on the moving unit 632. The reflector 62 is provided at the end of the support unit 65. The moving part 632 (and the reflectors 62 provided on the moving part 632) can be moved on the fixed part 631 along the conveying direction of the material to be treated 1 by a driving part (not shown). The driving method of the driving part is not particularly limited as long as it can slide the moving part 632, and examples thereof include a gear drive method such as a rack and pinion, a feed screw method such as a ball screw drive, and a micrometer method. For example, the moving part 632 (and the reflectors 62) can slide upstream and downstream in the conveying direction along rails 6311 formed on the fixed part 631. Each moving part 632 (and each reflector 62) can move independently or simultaneously along the conveying direction of the material to be treated 1. In the illustrated example, each moving part 632 (and each reflector 62) is configured to be able to move simultaneously in the conveying direction of the material to be treated 1.

[0055] The position changing mechanism 63 moves the reflector 62 to a first position where laser light (coherent light) is irradiated onto a plurality of master holograms 31 extending in one row, the Nth row (N is an integer greater than or equal to 1 and less than or equal to n-1), and to a second position where the laser light (coherent light) is irradiated onto a plurality of master holograms 31 extending in another row, the N+1th row. For example, as shown in FIGS. 1 and 3 , each reflector 62 is disposed by the position changing mechanism 63 at the first position so that coherent light can be irradiated onto each master hologram 31 in the first row. Furthermore, each reflector 62 can be moved by the position changing mechanism 63 to a second position, as shown by the two-dot chain line in FIG. 1 , so that coherent light can be irradiated onto each master hologram 31 in the second row. Furthermore, each reflector 62 can be moved by the position changing mechanism 63 to a third position so that coherent light can be irradiated onto each master hologram 31 in the third row.

[0056] Furthermore, the reflector 62 is provided with an optical path adjustment mechanism for changing the traveling direction of the coherent light toward the master hologram 31. The optical path adjustment mechanism allows the reflector 62 to cause the first coherent light to travel toward the master hologram 31 and the second coherent light to travel toward the master hologram 31 in a direction different from that of the first coherent light. The optical path adjustment mechanism includes an angle adjustment unit for adjusting the angle of the reflector 62, a position adjustment unit for adjusting the position of the reflector 62, and a height adjustment unit for changing the height of the reflector 62. Specifically, with reference to FIG. 8 , the reflector 62 is attached to the moving unit 632 via a support unit 65. The support unit 65 includes a cylindrical portion 651, a shaft portion 652 provided so as to be movable relative to the cylindrical portion 651, and a hinge portion 653 rotatably attached to the end of the shaft portion 652. The cylindrical portion 651 is fixed to the moving unit 632. The shaft 652 can be advanced or retreated relative to the tube 651 by a conventionally known extension / retraction drive mechanism (not shown) (extension / retraction is indicated by an arrow). The hinge 653 is fixed to the side of the reflector 62 opposite the reflective surface 62a. The hinge 653 can rotate around a rotation center shaft 654 provided at the end of the shaft 652 (rotation of the hinge is indicated by an arrow). The hinge 653 is rotated by a conventionally known rotation drive mechanism (not shown). The axis of the rotation center shaft 654 extends parallel to the width direction. Therefore, the angle of the reflector 62 can be appropriately changed so that it is inclined at a desired angle with respect to a plane including the conveyance direction and the width direction. The tube 651, shaft 652, and extension / retraction drive mechanism (not shown) correspond to a height adjustment unit that changes the height of the reflector 62. The shaft 652, hinge 653, and rotation drive mechanism correspond to an angle adjustment unit that adjusts the angle of the reflector 62. Furthermore, the above-mentioned position changing mechanism 63 (a uniaxial stage having a fixed part 631, a moving part 632, and a driving part) also serves as the position adjusting part of the optical path adjusting mechanism.

[0057] {Method of Manufacturing Hologram} Next, a method of manufacturing a hologram will be described. When a duplicate hologram is manufactured using the master hologram 31, the manufacturing apparatus A is used.

[0058] 11, in order to irradiate the multiple master holograms 31 extending in the first row S-1 with coherent light, the reflector 62 is positioned at a first position corresponding to the first row S-1. Meanwhile, the moving mechanism 382 separates the master layer 3 from the support substrate 12 of the processed material 1, and the transport unit B transports the processed material 1 downstream in the transport direction by a predetermined length, and then transport of the processed material 1 in the exposure unit C is stopped. The predetermined length corresponds to the portion of the photosensitive layer 11 for which exposure processing has been completed. Next, the pressure roll 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 processed material 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] <Exposure Process Using Multiple Coherent Light Beams Propagating in Different Directions> At least two coherent light beams traveling in different directions are irradiated onto the master hologram 31 in the first row S-1. It is preferable that the at least two coherent light beams traveling in different directions are irradiated onto the same area of ​​the master hologram 31. As shown in FIGS. 1 and 3 , a first coherent light beam L1 is irradiated onto the master hologram 31 from the first surface side of the light-transmitting plate 41. Specifically, as shown in FIG. 12 , a light source D irradiates the master hologram 31 with a first laser beam L11, which is a first coherent light beam traveling in a predetermined direction. The incident angle α1 of the first laser beam L11 is set to the same as the incident angle of the first light IL1 when the master hologram 31 was fabricated. The angle, position, and / or height of the reflector 62 are adjusted by the optical path adjustment mechanism so that the traveling direction of the first laser beam L11 is the incident angle α1. The adjustment is appropriately set taking into consideration the angle of incidence, the distance from the reflector 62 to the master hologram 31, and the like. The irradiated first laser beam L11 passes through the photosensitive layer 11 and enters the master hologram 31, where it generates a first diffracted beam L12 due to the interference fringes (interference fringes generated by the first beam IL1) recorded in the master hologram 31. The diffraction angle β1 of the first diffracted beam L12 is the same as that recorded in the master hologram 31. As the first diffracted beam L12 from the master hologram 31 passes through the photosensitive layer 11, the photosensitive layer 11 is exposed to the first laser beam L11 and the first diffracted beam L12. As a result, a duplicate hologram in which the wavelength and angle of the first laser beam L11 are recorded is formed in the photosensitive layer 11. The first laser beam L11 is irradiated until the exposure of the photosensitive layer 11 is completed. For example, if the integrated exposure amount of the photosensitive layer 11 is 20 mJ / cm ２ The first laser beam L11 is irradiated until the above-mentioned irradiation time is reached. The irradiation time of the first laser beam L11 is set appropriately taking into consideration the intensity of the laser beam, the cumulative exposure amount, etc. The same applies to the subsequent irradiation of the second laser beam L21 and the third laser beam L32.

[0061] Note that a portion of the first diffracted light L12 is absorbed by the light absorption layers 51 and 53 and is not reflected. Also, a portion of the first diffracted light L12 may be internally reflected to generate reflected light L13, but this reflected light L13 does not pass through the duplicated hologram in the photosensitive layer 11 again and is absorbed by the light absorption layer 51. This makes it possible to prevent the interference fringes of the duplicated hologram in which the wavelength and angle of the first laser light L11 are recorded from being disturbed.

[0062] After the exposure with the first laser beam L11 is completed, the master hologram 31 in the first row S-1 is irradiated with second coherent light L21 from the first surface side of the light-transmitting plate 41. Specifically, as shown in FIG. 13 , the master hologram 31 is irradiated with second laser beam L21, which is second coherent light traveling in a predetermined direction, by a light source D. The second laser beam L21 is preferably irradiated over the same range of the master hologram 31 as the range irradiated with the first laser beam L11. The traveling direction of the second laser beam L21 (second coherent light) is different from the traveling direction of the first laser beam L11. That is, the incident angle α2 of the second laser beam L21 is set to the same as the incident angle of the second light IL2 when the master hologram 31 was fabricated. However, since FIG. 13 illustrates a case where the incident angle α2 is parallel to the normal direction, the symbol α2 is not shown. Furthermore, it is preferable that the second laser beam L21 be a laser beam having the same wavelength as the first laser beam L11. The angle, position, and / or height of the reflector 62 are adjusted by the optical path adjustment mechanism so that the traveling direction of the second laser beam L21 is the incident angle α2. In the illustrated example, after the first laser beam L11 is irradiated, the angle and position of the reflector 62 along the transport direction are adjusted. When adjusting the angle of the reflector 62 by the optical path adjustment mechanism, the shutter 71 or the like is closed to prevent the laser beam from hitting the reflector 62. The incident angle of the second laser beam L21 is, for example, -20 to 20 degrees, preferably -10 to 10 degrees. The angle between the traveling direction of the second laser beam L21 and the traveling direction of the first laser beam L11 is, for example, 5 to 40 degrees, preferably 10 to 30 degrees, and more preferably 15 to 25 degrees. By making the second laser beam L21 and the first laser beam L11 incident at the angle described above, a replica hologram with a wide viewing angle can be produced.

[0063] The irradiated second laser light L21 passes through the photosensitive layer 11 and enters the master hologram 31, where it generates second diffracted light L22 due to the interference fringes (interference fringes generated by the second light IL2) recorded in the master hologram 31. The diffraction angle β2 of the second diffracted light L22 is the same as that recorded in the master hologram 31. As the second diffracted light L22 from the master hologram 31 passes through the photosensitive layer 11, the photosensitive layer 11 is exposed to the second laser light L21 and the second diffracted light L22. As a result, a duplicate hologram in which the wavelength and angle of the second laser light L21 are recorded is formed in the photosensitive layer 11. Note that a portion of the second diffracted light L22 is absorbed by the light absorption layers 51 and 53 and is not reflected. Furthermore, a portion of the second diffracted light L22 may be internally reflected to generate reflected light L23, but this reflected light L23 does not pass through the duplicated hologram in the photosensitive layer 11 again, but is absorbed by the light absorption layer 51. This prevents the interference fringes of the duplicated hologram in which the wavelength and angle of the second laser light L21 are recorded from being disturbed.

[0064] After the exposure with the second laser beam L21 is completed, the master hologram 31 in the first row S-1 is irradiated with third coherent light L31 from the first surface side of the light-transmitting plate 41. Specifically, as shown in FIG. 14 , the master hologram 31 is irradiated with third laser beam L31, which is third coherent light traveling in a predetermined direction, by a light source D. The third laser beam L31 is preferably irradiated over the same range of the master hologram 31 as the range irradiated with the first laser beam L11 and the second laser beam L21. The traveling direction of the third laser beam L31 (third coherent light) is different from the traveling directions of the first laser beam L11 and the second laser beam L21. That is, the incident angle α3 of the third laser beam L31 is set to be the same as the incident angle of the third light IL3 when the master hologram 31 was fabricated. Furthermore, it is preferable to use laser light having the same wavelength as the first laser beam L11 for the third laser beam L31. The optical path adjustment mechanism adjusts the angle, position, and / or height of the reflector 62 so that the traveling direction of the third laser beam L31 is the incident angle α3. In the illustrated example, after the second laser beam L21 is irradiated, the angle, position along the transport direction, and height of the reflector 62 are adjusted. When adjusting the angle of the reflector 62 using the optical path adjustment mechanism, a shutter 71 or the like is closed to prevent the laser beam from hitting the reflector 62. The angle between the traveling direction of the second laser beam L21 and the traveling direction of the third laser beam L31 is, for example, 5 to 40 degrees, preferably 10 to 30 degrees, and more preferably 15 to 25 degrees. By making the second laser beam L21 and the third laser beam L31 incident at the above angle, a replica hologram with a so-called wide viewing angle can be produced.

[0065] The irradiated third laser light L31 passes through the photosensitive layer 11 and enters the master hologram 31, where it generates third diffracted light L32 due to the interference fringes recorded in the master hologram 31 (interference fringes generated by the third light IL3). The diffraction angle β3 of the third diffracted light L32 is the same as that recorded in the master hologram 31. As the third diffracted light L32 from the master hologram 31 passes through the photosensitive layer 11, the photosensitive layer 11 is exposed to the third laser light L31 and the third diffracted light L32. As a result, a duplicate hologram in which the wavelength and angle of the third laser light L31 are recorded is formed in the photosensitive layer 11. Note that a portion of the third diffracted light L32 is absorbed by the light absorption layers 51 and 53 and is not reflected. Furthermore, a portion of the third diffracted light L32 may be internally reflected to generate reflected light L33, but this reflected light L33 does not pass through the duplicate hologram in the photosensitive layer 11 again, but is absorbed by the light absorption layer 51 and / or the master light absorption layer 35. This prevents the interference fringes of the duplicate hologram in which the wavelength and angle of the third laser light L31 are recorded from being disturbed.

[0066] Although the above example illustrates the case where photosensitive layer 11 is exposed to three laser beams traveling in different directions, a duplicate hologram may also be produced by irradiating master hologram 31 with two laser beams traveling in different directions, or four or more laser beams traveling in different directions. In this case, master hologram 31 is naturally produced using two beams of light traveling in different directions, or four or more beams of light traveling in different directions. By using three or more laser beams traveling in different directions, a duplicate hologram with a so-called wide viewing angle can be produced.

[0067] The multiple laser beams (first laser beam L11, second laser beam L21, and third laser beam L31 in the above example) for exposing the photosensitive layer 11 may be, for example, red laser beams (e.g., 640 nm laser beams), green laser beams (e.g., 532 nm laser beams), blue laser beams (e.g., 460 nm laser beams), or composite laser beams including at least two types of laser beams selected from red, green, and blue laser beams. 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 beam from the first oscillator 611 is reflected by each reflector 62 and irradiated onto the master hologram 31. In this case, a red replica hologram having multiple angles recorded in the photosensitive layer 11 is produced. When shutter 6121 of second oscillator 612 is opened and shutters 6111 and 6131 of first oscillator 611 and third oscillator 613 are closed, green laser light from second oscillator 612 is reflected by each reflector 62 and irradiated onto master hologram 31. In this case, a green replica hologram is created in which multiple angles are recorded in photosensitive layer 11. When shutter 6131 of third oscillator 613 is opened and shutters 6111 and 6121 of first oscillator 611 and second oscillator 612 are closed, blue laser light from third oscillator 613 is reflected by each reflector 62 and irradiated onto master hologram 31. In this case, a blue replica hologram is created in which multiple angles are recorded in photosensitive layer 11.

[0068] For example, when all shutters 6111, 6121, and 6131 are opened, red, green, and blue laser beams from the first to third oscillators 611, 612, and 613 are simultaneously reflected by the respective reflectors 62 and irradiated onto the master hologram 31. In this case, red, green, and blue duplicate holograms are multiplexed and recorded at multiple angles in the photosensitive layer 11. Alternatively, two types of laser beams may be selected. For example, when shutters 6111 and 6121 are opened and shutter 6131 is closed, red and green laser beams from the first and second oscillators 611 and 612 are reflected by the respective reflectors 62 and irradiated onto the master hologram 31. In this case, a duplicate hologram is created in the photosensitive layer 11, in which interference fringes diffracting red wavelength light and interference fringes diffracting green wavelength light are multiplexed and recorded at multiple angles. The interference fringes that diffract the red, green, and blue wavelength light are recorded in a master hologram. When at least two types of laser light selected from red, green, and blue laser light are simultaneously irradiated, the laser light of each color can be irradiated with a time difference by adjusting the output intensity of the laser oscillator.

[0069] Furthermore, when irradiating master hologram 31 with a composite laser beam containing at least two types of laser beams selected from red, green, and blue laser beams, the laser beams may be irradiated one by one in sequence. For example, as described in the above <Exposure Step>, red laser beam from first oscillator 611 is propagated in at least two different directions (e.g., propagated so as to have the same angle of incidence as the first, second, and third laser beams) and irradiated onto master hologram 31 in the first row S-1 to expose photosensitive layer 11. Next, green laser beam from second oscillator 612 is similarly propagated in at least two different directions and irradiated onto master hologram 31 in the first row S-1 to expose photosensitive layer 11. Next, blue laser beam from third oscillator 613 is similarly propagated in at least two different directions and irradiated onto master hologram 31 in the first row S-1 to expose photosensitive layer 11. In this way, even when two or more laser beams of predetermined wavelengths are sequentially irradiated while changing the angle, a duplicate hologram in which each interference fringe is multiplexed and recorded is produced in the photosensitive layer 11. It should be noted that when laser beams of predetermined wavelengths (e.g., red laser beams) are irradiated onto the master hologram 31 to expose the photosensitive layer 11, the master hologram 31 is naturally produced using laser beams of the same wavelength as the laser beams of the predetermined wavelength. Here, in this specification, the expression "light of the same wavelength" means that the wavelengths of the two contrasting beams are the same if the two contrasting beams are light of a single wavelength, and that the wavelengths of the two contrasting beams include light of two or more wavelengths. Regarding the latter, for example, if the two contrasting beams are composite laser beams each including red laser beam, green laser beam, and blue laser beam, the wavelengths of the red laser beam, the green laser beam, and the blue laser beam of the two contrasting beams are the same.

[0070] <Irradiation Position Changing Process> As described above, by irradiating the master holograms 31 arranged in the first row S-1 with coherent light from multiple directions, duplicate holograms corresponding to each of the master holograms 31 in the first row S-1 are created in the photosensitive layer 11. After duplicate holograms corresponding to all of the master holograms 31 arranged in the first row S-1 are created, duplicate holograms corresponding to the master holograms 31 arranged in the second row S-2 are created. At this time, the position changing mechanism 63 moves each reflector 62 from the first position to a second position corresponding to the second row S-2 (see the two-dot chain lines in FIGS. 1 and 14 and FIG. 15). The reflectors 62 are moved simultaneously (synchronized). Note that the movement from the first position to the second position is performed after all of the master holograms 31 arranged in the first row S-1 are irradiated with at least two beams of coherent light at the first position, thereby completing the exposure of the photosensitive layer 11. In other words, the position change mechanism 63 does not operate until multiple exposures of the photosensitive layer 11 at different angles at the first position are completed and the recording of each interference fringe of the master hologram 31 in the first row S-1 is completed on the photosensitive layer 11. After the exposure is completed, the position change mechanism 63 moves each reflector 62 from the first position to the second position. Furthermore, it is preferable to prevent coherent light from traveling toward each reflector 62 when each reflector 62 moves. This prevents coherent light from irradiating the photosensitive layer 11 while the reflector 62 is moving, thereby preventing coherent light from accidentally entering an already-produced duplicate hologram (the duplicate hologram produced in the first row S-1 in the above example). Methods for preventing coherent light from traveling toward each reflector 62 when each reflector 62 moves include closing the shutter 71 or stopping the emission of laser light from the oscillator 61. However, closing the shutter 71 is simple and preferred.

[0071] 15, the master holograms 31 arranged in the second row S-2 are irradiated with at least two coherent beams of light traveling in different directions, in the same manner as in the above-described <<exposure step>>. For example, as described above, first laser beam L11, second laser beam L21, and third laser beam L31, each having a different incident angle, are irradiated sequentially from the first surface side of the light-transmitting plate 42 toward the master holograms in the second row S-2. In this manner, duplicate holograms corresponding to the master holograms 31 in the second row S-2 are produced in the photosensitive layer 11. Next, the reflector 62 is moved to the third row S-3, and duplicate holograms are produced in the same manner.

[0072] <Next Processing Step> After replica holograms corresponding to all of the master holograms 31 in the master layer 3 have been produced in the photosensitive layer 11 in this manner, the moving mechanism 382 separates the master layer 3 from the support substrate 12 of the workpiece 1. After the master layer 3 has been separated, index oil is usually attached to the second surface of the support substrate 12 of the workpiece 1, so the index oil attached to the support substrate 12 is removed by wiping it off with an index oil remover (not shown).

[0073] 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).

[0074] The exposed material 1 is transported and stopped, and the reflector 62 is returned to the first position, returning to the state shown in Figure 11. As a result, the exposed photosensitive layer 11 is sent downstream, and the unexposed photosensitive layer 11 is subsequently placed in the exposure section C.

[0075] <Repeated Process> Subsequently, the master layer 3 is adhered to the workpiece 1 in a similar manner, and exposed to at least two coherent beams of light traveling in different directions to create duplicate holograms corresponding to all of the master holograms 31 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. Figure 16( a) is a plan view of the workpiece 100 after exposure processing. The exposed workpiece 1 has multiple duplicate holograms arranged consecutively on its photosensitive layer 11. Hereinafter, the "exposed workpiece 100" will be referred to as the "replica hologram continuum 100." The above example illustrates the use of three rows of master holograms 31, and the duplicate hologram continuum 100 in Figure 16 has multiple duplicate holograms 310 arranged in three rows.

[0076] 1 , the duplicate hologram continuum 100 is subjected to a bleaching treatment in a bleaching unit 29. A protective film 15 and a release liner 16 are laminated to the bleached duplicate 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.

[0077] 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 16(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.

[0078] {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 holograms 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.

[0079] For example, the above-described manufacturing apparatus A (or manufacturing method) can also produce a replica hologram that includes a set of one rectangular hologram called an incoupling and one large rectangular hologram called an outcoupling. FIG. 17 is a reference side view showing an example of a light guide plate G. In the illustrated light guide plate G, a replica hologram having an incoupling 311 and an outcoupling 312 is disposed between transparent plates 1200, 1200. As shown in the figure, the incoupling 311 is irradiated with light L11-1 having an incident angle α1 and wavelength recorded in the interference fringes, light L21-1 having an incident angle α2 (however, since this is parallel to the normal direction NR, the symbol α2 is not shown) and wavelength, and light L31-1 having an incident angle α3 and wavelength. Each light is diffracted by the incoupling 311, and the diffracted light L12-1, L22-1, and L32-1 are reflected and propagated within the light guide plate G and are respectively emitted from the outcoupling 312. Since at least angle information is recorded in the replicated hologram manufactured by manufacturing apparatus A, each of the emitted beams L14-1, L24-1, and L34-1 travels at an emission angle α1, α2, and α3 (the same angle as the incident angle). For this reason, even when the eye coupling 312 is viewed from an oblique direction relative to the normal direction NR, the image represented by the emitted beam can be clearly seen.

[0080] 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).

[0081] [Second Embodiment] In the second embodiment, a position changing mechanism 63 changes the irradiation position between a first position where coherent light is irradiated onto a plurality of master holograms 31 extending in one row, and a second position where coherent light is irradiated onto a plurality of master holograms 31 extending in another row. Fig. 18 is a perspective view showing an exposure section C and a light source D in a manufacturing apparatus A of the second embodiment. However, in Fig. 18, both sides of the long strip-shaped workpiece are omitted, and further, for the light source D, a reflector 62 and a position changing mechanism 63 are shown.

[0082] Referring to FIG. 18 , as in the first embodiment, the master holograms 31 are arranged in m columns in the width direction and n rows in the transport direction, which is perpendicular to the width direction. In the illustrated example, a total of nine master holograms 31 (3×3) are provided on the master layer 3. The position change mechanism 63 moves the reflector 62 between a first position where laser light (coherent light) is irradiated onto a plurality of master holograms 31 extending in one column, the Mth row (M is an integer between 1 and m−1), and a second position where the laser light (coherent light) is irradiated onto a plurality of master holograms extending in another row, the M+1th row. Specifically, the moving unit 632 of the position change mechanism 63 is movable in the width direction relative to the fixed unit 631. Therefore, each reflector 62 provided on the moving unit 632 is movable along the width direction of the workpiece 1. 18, for example, each reflector 62 is disposed at a first position by a position change mechanism 63 so that coherent light beams traveling in different directions can be irradiated onto each master hologram 31 in the first column R-1. Furthermore, each reflector 62 can be moved by a position change mechanism 63 to a second position, as indicated by the two-dot chain line in the figure, so that coherent light beams traveling in different directions can be irradiated onto each master hologram 31 in the second column R-2. Furthermore, each reflector 62 can be moved by a position change mechanism 63 to a third position so that coherent light beams traveling in different directions can be irradiated onto each master hologram 31 in the third row R-3.

[0083] A brief description of hologram production using the manufacturing apparatus A of this embodiment will be given. As shown in FIG. 18 , to irradiate the multiple master holograms 31 extending in the first row R-1 with coherent light, a reflector 62 is positioned at a first position corresponding to the first row R-1. The transport unit B transports the material 1 a predetermined length and then stops the transport. The pressure roll 28 brings the photosensitive layer 11 into close contact with the second surface of the light-transmitting plate 41. The master layer 3 is brought close to the material 1 and filled with index oil 39. Next, at least two coherent beams of light traveling in different directions are irradiated onto the multiple master holograms 31 in the first row R-1 from the first surface side of the light-transmitting plates 41, 42, and 43. This creates duplicate holograms in the photosensitive layer 11 corresponding to the master holograms 31 in the first row R-1. The position change mechanism 63 moves the reflector 62 in the width direction, positioning the reflector 62 at a second position corresponding to the second row R-2. Movement from the first position to the second position is performed after all of the master holograms 31 arranged in the first row R-1 at the first position have been irradiated with coherent light and exposure of the photosensitive layer 11 has been completed. At least two beams of coherent light traveling in different directions are irradiated onto the master holograms 31 in the second row R-2, and duplicate holograms corresponding to each of the master holograms 31 in the first row R-2 are created in the photosensitive layer 11. Next, the reflector 62 is moved to the third row R-3, and duplicate holograms are created in the same manner.

[0084] [Third Embodiment] In the first embodiment described above, the light source D has the same number of reflectors 62 as the number of columns of the master hologram 31, but this is not limited to the case where the number of reflectors 62 of the light source D is the same as the number of columns of the master hologram 31. For example, as shown in FIG. 19 , there may be only one reflector 62. This reflector 62 simultaneously changes the traveling direction of all coherent light toward each master hologram 31. Although not specifically shown, there may also be two reflectors 62, and the number of reflectors 62 can be changed as appropriate. In the second embodiment described above, there are the same number of reflectors 62 as the number of rows of the master hologram 31, but similarly, there may also be one or two reflectors 62, and this can be changed as appropriate.

[0085] [Fourth Embodiment] In the first and second embodiments, the laser light emitted from each oscillator 61 travels along the same optical path along the way, but this is not limited to this. For example, as shown in Fig. 20, the laser light emitted from each oscillator 61 may travel along independent optical paths and be incident on the master hologram 31 via a reflector 62. In the illustrated example, a shutter 71, a half-wave plate 75, a magnifying lens 76, and a collimating lens 77 are arranged in this order after each of the first to third oscillators 611, 612, and 613. However, the arrangement of the optical devices is not limited to the example of Fig. 20.

[0086] Fifth Embodiment In the first and second embodiments, coherent light having dimensions substantially the same as those of the master hologram 31 is irradiated from the first surface side of the light-transmitting plate. However, this is not limiting. For example, as shown in FIG. 21A, coherent light having a dimension d smaller than the dimension 31W of the master hologram 31 may be irradiated. In this case, a replica hologram 310 having an area smaller than that of the master hologram 31 is formed in the photosensitive layer 11. Furthermore, as shown in FIG. 21B, coherent light having a dimension d larger than the dimension 31W of the master hologram 31 may be irradiated. When irradiating coherent light having a dimension d larger than the dimension 31W, a mask member 79 having an opening 791 larger than that of the master hologram 31 is used, or the mask member 79 is omitted. In this case, a replica hologram 310 having an area substantially the same as that of the master hologram 31 is formed in the photosensitive layer 11, just as in the case of irradiating coherent light having a dimension d substantially the same as that of the master hologram 31. When coherent light having a dimension d larger than the dimension 31W of the master hologram 31 is irradiated, part of the light strays from the master hologram 31. However, the stray light does not enter the master hologram 31 and does not produce diffracted light. Therefore, interference fringes are not recorded in the photosensitive layer 11 through which the stray light passes. Alternatively, the stray light is absorbed by the light absorption layer 53 and the master light absorption layer 35.

[0087] In the first and second embodiments, 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 and second embodiments is inverted upside down so that coherent light can be irradiated from below the exposure unit C. Furthermore, in the first and second embodiments, the coherent light is irradiated parallel to the normal direction of the master hologram 31, and the diffracted light travels at an acute diffraction angle. However, this is not limited to this example. The coherent light is irradiated at an angle that reproduces the master hologram 31. Furthermore, in the first and second embodiments, the coherent light is irradiated onto the workpiece 1 in a substantially horizontal position in the exposure unit C. However, the 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.

[0088] A Hologram manufacturing device B Conveying section of manufacturing device C Exposure section of manufacturing device D Light source of manufacturing device L11, L21, L31 Coherent light L12, L22, L32 Diffracted light 11 Photosensitive layer S-1 First row S-2 Second row 3 Master layer 31 Master hologram 61 Laser oscillator 62 Reflector 63 Position change mechanism 631 Fixed section 632 Moving section

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 pass through the photosensitive layer to expose the photosensitive layer, thereby replicating interference fringes of the master hologram on the photosensitive layer, wherein the light source is capable of irradiating the master hologram with at least two coherent light beams traveling in different directions.

2. The hologram manufacturing apparatus according to claim 1, wherein the at least two coherent beams of light have the same wavelength.

3. The hologram manufacturing apparatus of claim 1, wherein the light source comprises a coherent light oscillator and a reflector that reflects the coherent light from the oscillator, and the reflector is adjustable to direct a first coherent light toward the master hologram and a second coherent light toward the master hologram in a direction different from that of the first coherent light.

4. The hologram manufacturing apparatus according to claim 3, wherein the angle formed between the traveling direction of the first coherent light and the traveling direction of the second coherent light is 5 to 40 degrees.

5. The hologram manufacturing device according to claim 1, wherein the photosensitive layer is in the form of a long strip, and the transport unit transports the long strip-shaped photosensitive layer a predetermined length in the longitudinal direction and then stops transporting the photosensitive layer.

6. The hologram manufacturing apparatus of claim 1, wherein the master layer has a plurality of master holograms arranged in a plurality of columns in the width direction and a plurality of rows in a transport direction perpendicular to the width direction; the photosensitive layer is in the form of a long strip, and the transport unit transports the long strip of photosensitive layer a predetermined length in the longitudinal direction and then stops transporting the photosensitive layer; the light source has a position change mechanism, and the position change mechanism is capable of changing the irradiation position between a first position where at least two coherent light beams traveling in different directions are irradiated onto a plurality of master holograms extending in one row or one column, and a second position where at least two coherent light beams traveling in different directions are irradiated onto a plurality of master holograms extending in another row or another column.

7. A method for replicating interference fringes of the master hologram onto the photosensitive layer, 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 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 are transmitted through the photosensitive layer to expose the photosensitive layer, and the method comprises irradiating the master hologram with at least two coherent light beams traveling in different directions.

8. The method for producing a hologram according to claim 7, wherein the master hologram is irradiated with three or more coherent beams of light traveling in different directions.

9. The method for producing a hologram according to claim 7, wherein the coherent light is a red laser light, a green laser light, a blue laser light, or a composite laser light containing at least two types of light selected from the group consisting of red laser light, green laser light, and blue laser light.

10. A light guide plate having a hologram manufactured by the manufacturing method according to any one of claims 7 to 9.

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

Images