JP5565658B2 - Hologram and method for manufacturing hologram - Google Patents

Description

  The present invention relates to a hologram capable of reproducing an image so that different images are observed from at least two directions by light incident from one direction, and a method for manufacturing the hologram.

  2. Description of the Related Art Conventionally, a hologram capable of reproducing an image so that different images are observed from at least two directions by light incident from one direction is known, for example, as a screen switching hologram. A plurality of interference fringes are recorded in the screen switching type hologram disclosed in Patent Literature 1, and Bragg diffraction conditions for the plurality of interference fringes when light having a specific wavelength is incident on the hologram from a specific direction. Are to be satisfied at the same time. For this reason, a different image comes to be observed from a hologram by changing an observation direction.

  Such a screen-switching hologram is going to be used in various fields for the purpose of improving the design and indicating the authenticity due to the special feature of reproducing the image. In order to effectively exhibit the functions expected of the screen-switching hologram, for example, the function of improving the design and the function of indicating authenticity, the transition of each image reproduced by the screen-switching hologram is changed. It is important that it can be clearly seen. For this purpose, it is important that each image is reproduced brightly.

JP 2008-122670 A

  By the way, in Patent Document 1, a plurality of object lights having different image information and reference light are simultaneously incident on the photosensitive material from different directions, so that each object light and reference light can be incident on each other. Interference fringes due to this interference are recorded on the photosensitive material, and a screen switching hologram is produced. However, according to this method, it is expected that a plurality of object lights interfere with each other and many unnecessary interference fringes are recorded on the photosensitive material. When the hologram includes unnecessary interference fringes, the reproduction illumination light is also diffracted in an unnecessary direction, and as a result, the diffraction efficiency in the intended direction is lowered. Accordingly, the image cannot be reproduced brightly in each planned direction, and as a result, a change in the image reproduced in each direction cannot be sufficiently recognized. In this case, there is a possibility that functions expected for the hologram, that is, functions such as improvement in designability and provision of an authenticity determination index cannot be sufficiently exhibited.

  Japanese Patent Laid-Open No. 6-309691 discloses a method in which exposure of a photosensitive material using object light and reference light is sequentially performed in units of interference fringes. However, in the case where a plurality of interference fringes are sequentially formed on the same photosensitive material by sequential exposure, the number of manufacturing steps increases, which causes a problem that the manufacturing cost of the hologram increases. In addition to such problems, it is extremely difficult to adjust the photosensitive material and adjust the exposure conditions for adjusting the diffraction efficiency.

  The present invention has been made in consideration of such points, and is a hologram that reproduces an image so that different images can be observed from at least two directions by light incident from one direction. An object of the present invention is to provide a hologram capable of reproducing an image observed from each direction with diffraction efficiency. The present invention is also a method of manufacturing a hologram capable of reproducing an image so that different images can be observed from at least two directions by light incident from one direction, and can be viewed from each direction with high diffraction efficiency. An object of the present invention is to provide a method for producing a hologram capable of reproducing an image to be reproduced.

A method for manufacturing a hologram according to an aspect of the present invention includes:
A method for producing a hologram capable of reproducing an image so that different images are observed from at least two directions by light incident from one direction,
The laser light generated by each of the two or more laser light sources is separated into the reproduction illumination light and the reference light, respectively, and then the two or more reproduction illuminations composed of each of the laser lights generated from the two or more laser light sources Light is incident on one of a plurality of element holograms to reproduce an image from each of the plurality of element holograms, and the reproduced light from the plurality of element holograms for reproducing the image; Two or more reference lights each consisting of laser light generated from the above laser light source, and simultaneously entering the photosensitive material to record interference fringes on the photosensitive material,
In the step of recording the interference fringes, reproduced light from the plurality of element holograms travels in different directions and enters the photosensitive material from the same side, and the two or more reference lights are on the same side Incident on the photosensitive material from
It is characterized by that.

  In the hologram manufacturing method according to one aspect of the present invention, the reproduction illumination light incident on one element hologram of the plurality of element holograms is different from the one element hologram of the plurality of element holograms. The reproduction illumination light incident on the element hologram may travel in different directions and enter the corresponding element hologram.

  In the hologram manufacturing method according to an aspect of the present invention, the number of the two or more laser light sources is the same as the number of the element holograms, and each of the laser beams generated from the two or more laser light sources is included. Two or more reproduction illumination lights may be incident on any one of the plurality of element holograms which are different from each other.

  Furthermore, in the method for manufacturing a hologram according to an aspect of the present invention, the reproduction light from the plurality of element holograms may travel in one of the at least two directions and enter the photosensitive material.

  Furthermore, in the method for manufacturing a hologram according to one aspect of the present invention, the two or more reference lights composed of the laser beams generated from the two or more laser light sources travel in the same direction and enter the photosensitive material. You may make it do.

  Furthermore, in the hologram manufacturing method according to an aspect of the present invention, the wavelengths of the laser beams generated from each of the two or more laser light sources may be the same.

  Furthermore, in the step of recording the interference fringes of the hologram manufacturing method according to one aspect of the present invention, the reproduction light and the reference light, which are laser beams generated from the same laser light source of the two or more laser light sources. Only interference fringes formed by interference may be recorded.

  Furthermore, in the method for manufacturing a hologram according to one aspect of the present invention, each of the plurality of element holograms may be composed of a part of a single photosensitive material.

  Furthermore, in the hologram manufacturing method according to an aspect of the present invention, each of the plurality of element holograms may be configured as a volume hologram or a computer-generated hologram.

The hologram according to one aspect of the present invention is:
A hologram that reproduces an image so that different images from at least two directions are observed on the same side of the hologram by light incident from one direction,
Laser light generated from each of the two or more laser light sources is separated into reproduction illumination light and reference light, respectively, and then two or more reproduction illuminations composed of each of the laser lights generated from the two or more laser light sources Light is incident on one of a plurality of element holograms to reproduce an image from each of the plurality of element holograms, and the reproduced light from the plurality of element holograms for reproducing the image; Comprising a plurality of interference fringes recorded by simultaneously entering two or more reference beams each consisting of laser beams generated from the above laser light source and the photosensitive material,
The plurality of interference fringes include only interference fringes formed by interference between the reproduction light and the reference light, which are laser beams generated from the same laser light source among the two or more laser light sources.
It is characterized by that.

  In the hologram according to one aspect of the present invention, the interference fringes may include only the same number of interference fringes as the number of the two or more laser light sources.

  An article according to one embodiment of the present invention is characterized in that any one of the holograms according to one embodiment of the present invention described above is attached.

  According to the present invention, different images observed from at least two directions can be reproduced with high diffraction efficiency by light incident from one direction.

FIG. 1 is a diagram showing a hologram in an embodiment of the present invention. FIG. 2 is a diagram for explaining the optical action of the hologram of FIG. FIG. 3 is a diagram for explaining a method of producing a first element hologram used for producing the hologram of FIG. FIG. 4 is a diagram corresponding to FIG. 3 and is a diagram for explaining a method of manufacturing a second element hologram used for manufacturing the hologram of FIG. FIG. 5 is a diagram for explaining a method of manufacturing the hologram of FIG. FIG. 6 is a diagram for explaining a method of manufacturing the hologram of FIG. 1 and an optical system used for manufacturing. FIG. 7 is a diagram showing an optical system in which the presence or absence of interference between laser beams generated from two laser light sources is investigated. FIG. 8 is a diagram showing an optical system in which the presence or absence of interference is investigated by Mach-Zehnder interferometry. FIG. 9 is a diagram showing an image of light projected on the screen by the optical system of FIG. FIG. 10 is a diagram showing an image of light projected on the screen by the optical system of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  FIGS. 1-6 is a figure for demonstrating the hologram and the manufacturing method of a hologram in one embodiment of this invention. Of these, FIGS. 1 and 2 are diagrams mainly for explaining the hologram and its optical action, and FIGS. 3 to 6 are diagrams for mainly explaining a method for manufacturing the hologram. is there.

  As shown in FIGS. 1 and 2, the hologram 10 described below is such that different images 5 and 6 are observed from at least two observation directions d2 and d3 by light L11 incident from one direction d1. It is a screen switching hologram for reproducing images 5 and 6. The hologram 10 is configured as a volume hologram capable of reproducing the images 5 and 6 in a three-dimensional manner, more specifically, as a reflective volume hologram. Such a screen-switching hologram 10 is used for the purpose of improving the design of the article, marking the authenticity of the article, and the like, in particular, packaging materials, cards, certificates, securities, gift certificates, etc. Affixed to etc. and used.

  As shown in FIG. 1, a plurality of interference fringes 11 a and 11 b including information related to different images 5 and 6 are recorded on the screen switching hologram 10. The plurality of interference fringes 11a and 11b are recorded corresponding to the light L11 that travels along the same direction d1 and enters the hologram 10 from the same surface 10a side. Specifically, the plurality of interference fringes 11a and 11b are recorded such that the Bragg diffraction condition is satisfied by the light L11 incident on the hologram 10 from one direction d1. Therefore, the plurality of interference fringes 11a and 11b diffract the incident light L11 from the one direction d1 that functions as reproduction illumination light into the plurality of directions d2 and d3. Then, the lights L12 and L13 diffracted in the directions d2 and d3 reproduce the different images 5 and 6 as reproduction light. As a result, different images 5 and 6 are observed from the one surface 10a side of the hologram 10 along the diffraction directions d2 and d3 by the interference fringes 11a and 11b.

  In the present specification, the number of interference fringes means the number of muscle groups composed of a plurality of stripes extending substantially in parallel, and does not indicate the number of stripes included in the interference fringes.

  In the following example, as shown in FIG. 2, the reproduction illumination light L11 is diffracted within a certain angular range centering on different diffraction directions d2 and d3. As a result, the images 5 and 6 are observed in the viewing zones z1 and z2 corresponding to a certain angle range centered on the diffraction directions d2 and d3.

  More specifically, in the present embodiment, as shown in FIG. 1, the hologram 10 has two interference fringes, a first interference fringe 11a and a second interference fringe 11b. Light (reproduced illumination light) L11 having a certain wavelength travels along the first direction d1 and is diffracted from the first interference fringes 11a with high diffraction efficiency when entering the hologram 10 from the first surface 10a side. Has an effect. As a result, the light L11 is reflected by the hologram 10 in a range centered on the second direction d2. The light (reproduced light) L12 reflected by the hologram 10 forms an image 5.

  Similarly, light (reproduced illumination light) L11 having a specific wavelength travels along the first direction d1 and is highly diffracted from the second interference fringe 11b when entering the hologram 10 from the first surface 10a side. As a result, the light L11 is reflected by the hologram 10 in a range centered on the third direction d3. The reflected light (reproduced light) L13 forms an image 6 different from the image 5 reproduced by the diffracted light (reproduced light) L12 from the first interference fringes 11a.

  In the present embodiment, as indicated by a solid line in FIG. 1, the diffracted light (reproduced light) L12 diffracted by the first interference fringes 11a forms a sphere in the vicinity of the hologram 10. The observer observes the hologram 10 from the viewing zone z1 centered in the second direction d2 in a state where the reproduction illumination light L11 is incident on the hologram 10 from the first surface 10a side along the first direction d1. Thus, the image 5 as a sphere can be observed. On the other hand, the diffracted light (reproduced light) L13 diffracted by the second interference fringes 11b forms a cube in the vicinity of the hologram 10. The observer observes the hologram 10 from the viewing zone z2 centering on the third direction d3 in a state where the reproduction illumination light L11 is incident on the hologram 10 from the first surface 10a side along the first direction d1. Thus, the image 6 as a cube can be observed. The image 5 observed from the first viewing zone z1 and the image 6 observed from the second viewing zone z2 are reproduced at positions that at least partially overlap each other on the basis of the position where the hologram 10 is arranged. Is done.

  In the present embodiment, the wavelength of the reproduction illumination light L11 from the first direction d1 that satisfies the Bragg diffraction condition of the first interference fringe 11a is the reproduction illumination from the first direction d1 that satisfies the Bragg diffraction condition of the second interference fringe 11b. It is the same as the wavelength of the light L11. Therefore, the image 5 observed from the first viewing zone z1 and the image 6 observed from the second viewing zone z2 are reproduced with the same color.

  In this embodiment, when light of a specific wavelength is incident on the hologram 10 from a predetermined direction, the Bragg interference conditions for both the first interference fringe 11a and the second interference fringe 11b are simultaneously satisfied. Become. As a result, the sphere image 5 that can be observed from the first viewing zone z1 is reproduced by the first interference fringes 11a, and at the same time, the cubic image 6 that can be observed from the second viewing zone z2 becomes the second interference. Reproduced by the stripe 11b. Therefore, when the observer gradually changes the observation direction with respect to the hologram 10, the spherical image 5 and the cubic image 6 are sequentially observed. In other words, the observed images 5 and 6 change as the observation direction changes. By such a reproduction mode of the special images 5 and 6, the function expected for the hologram 10, for example, the function of improving the design property and the function of indicating the authenticity of the article on which the hologram 10 is pasted are made effective. It can be demonstrated.

  In particular, in the hologram 10 according to the present embodiment, unnecessary interference fringes are not recorded due to the manufacturing method described below. For this reason, according to the hologram 10 according to the present embodiment, it is possible to effectively prevent light from being diffracted in an unnecessary direction. In other words, the incident light can be effectively utilized and diffracted in the direction in which the incident light is expected with a very high diffraction efficiency. As a result, the images 5 and 6 are reproduced brightly, the change in the visually recognized images 5 and 6 accompanying the change in the observation direction can be clearly grasped, and the function expected of the hologram 10 is more effectively exhibited. Become so.

  Next, an example of a method for manufacturing the hologram 10 as described above will be described mainly with reference to FIGS. In the following example, first, a plurality of element holograms 16a and 16b (H1 hologram 15) capable of reproducing different images 5 and 6 are prepared, and then reproduction light from each of the element holograms 16a and 16b is used as object light. The hologram 10 is produced by simultaneously recording on the photosensitive material 13 a plurality of interference fringes 11 a and 11 b that can be used to reproduce different images 5 and 6. That is, in the following description, the hologram 10 is produced by the so-called H1H2 method.

  In FIG. 2, one of two types of marks PM1 and PM2 is provided on the upper and lower edges of the second surface 10b of the hologram 10. 5 and 6, one of two types of marks PM1 and PM2 is provided on the upper and lower edges of the photosensitive material 13 that forms the hologram 10. The marks PM1 and PM2 in FIGS. 5 and 6 are given in consideration of convenience in understanding the front and back and upper and lower sides of the photosensitive material 13 in correspondence with the hologram 10 described above. The surface (second surface) 13b on which the marks PM1 and PM2 are provided is a surface that forms the second surface 10b on which the hologram marks PM1 and PM2 are provided. Similarly, in FIG. 3 to FIG. 6, the H1 hologram 15 and the photosensitive material 18 that forms the H1 hologram 15 are also convenient for understanding the H1 hologram 15 and the photosensitive material 18 with their front and back sides and upper and lower sides corresponding to each other. In consideration of the above, the marks PM3 and PM4 are provided. Therefore, the surface (second surface) 18b on which the marks PM3 and PM4 of the photosensitive material 18 are provided is a surface that forms the surface (second surface) 15b on which the marks PM3 and PM4 of the H1 hologram 10 are provided. . These marks PM1, PM2, PM3, and PM4 are not necessary for the hologram 10 to achieve the functions and effects described in this specification.

  The photosensitive materials 13 and 18 are usually handled by being laminated on a transparent substrate. However, in this specification and the drawings, for the convenience of understanding the invention, the photosensitive materials (dry plates) 13 and 18 are used. The transparent base material which supports 18 is omitted.

  First, a method for producing the element holograms 16a and 16b will be described. In the following example, a plurality of element holograms 16a and 16b are prepared as transmission type volume holograms. In the following example, interference fringes of the first element hologram 16a capable of reproducing the spherical image 5 are recorded in one area of one photosensitive material 18, and a cube is recorded in the other area of one photosensitive material 18. The interference fringes of the second hologram 16b capable of reproducing the image 6 are recorded.

  As an example, the interference fringes of the first element hologram 16a are first produced. First, as shown in FIG. 3, areas of the photosensitive material 18 other than the area where the first element hologram 16 a is to be produced are shielded against light used for exposure of the photosensitive material 18. Cover with one mask 19a. The photosensitive material 18 partially covered with the first mask 19a is disposed at a predetermined position. As the photosensitive material 18, various known photosensitive materials (dry plates) can be used. For example, as the photosensitive material 18, a photopolymer, a silver salt emulsion, dichromated gelatin, a photoresist, or the like can be used.

  Next, the model 5a produced based on the shape (sphere) of the image 5 to be reproduced by the first element hologram 16a is arranged at a predetermined position with the photosensitive material 18 as a reference. As shown in FIG. 3, in this state, laser light is generated from a single laser light source and separated into object illumination light and reference light L31. Of these, the reference light L31 is incident on the photosensitive material 18 from the side of the one surface 18b along a specific direction (fourth direction) d4 as parallel light. On the other hand, the object illumination light is applied to the model 5a, and the object light L32 scattered and reflected by the model 5a enters the photosensitive material 18. As a result, a region of the photosensitive material 18 that is not covered with the first mask 19a is exposed by the reference light L31 and the object light L32, and interference fringes due to interference with the reference light L31 and the object light L32 are recorded in this region. The In this way, interference fringes of the first element hologram 16a capable of reproducing the spherical image 5 are produced in one region of the photosensitive material 18.

  Next, the interference fringes of the second element hologram 16b are produced. First, as shown in FIG. 4, the first mask 19 a is peeled off from the photosensitive material 18, and then the region other than the region where the second element hologram 16 b of the photosensitive material 18 is to be produced is exposed to the photosensitive material 18. It is covered with a second mask 19b having a light shielding property against the light used in the above. Thereafter, the model 6a produced based on the shape (cube) of the image 6 to be reproduced by the second element hologram 16b is positioned with respect to the photosensitive material 18 partially covered with the second mask 19b. To do. At this time, a part of the image 6a is arranged in a region (region indicated by a two-dot chain line in FIG. 4) based on the photosensitive material 18 on which the model 5a is arranged at the time of manufacturing the first element hologram 16a. The image 6 a is positioned with respect to the photosensitive material 18.

  In this state, as shown in FIG. 4, laser light is generated from a single laser light source and separated into object illumination light and reference light L41. Of these, the reference light L41 enters the photosensitive material 18 as parallel light from the one surface 18b side along a specific direction (fifth direction) d5. In the present embodiment, the incident direction d5 of the reference light L41 to the photosensitive material 18 is different from the incident direction d4 of the reference light L31 to the photosensitive material 18 when the first element hologram 16a is manufactured. As can be understood from FIGS. 3 and 4, the incident direction d4 of the reference light L31 to the photosensitive material 18 at the time of manufacturing the first element hologram 16a and the photosensitive material 18 of the reference light L41 at the time of manufacturing the second element hologram 16b. The incident direction d5 is inclined to the opposite side with the normal direction to the one surface 18b of the photosensitive material 18 as the center.

  Object illumination light composed of laser light oscillated by the same laser light source as the reference light L41 is applied to the model 6a, and object light L42 scattered and reflected by the model 6a is incident on the photosensitive material 18. As a result, the area of the photosensitive material 18 that is not covered with the second mask 19b is exposed by the reference light L41 and the object light L42, and interference fringes due to interference with the reference light L41 and the object light L42 are recorded in this area. The In this way, the interference fringes of the second element hologram 16b capable of reproducing the spherical image 6 are produced.

  Thereafter, by performing an appropriate post-treatment according to the type of material constituting the photosensitive material 18, the photosensitivity of the photosensitive material 18 is lost, and the first element hologram 16a and the second element hologram 16b are obtained. As shown in FIGS. 3 and 4, in the exposure for producing the first element hologram 16a and the second element hologram 16b, the object light L32, L42 and the reference light L31, L41 are the same surface 18b of the photosensitive material 18. Is incident on the photosensitive material 18. Therefore, the produced first element hologram 16a and second element hologram 16b are transmissive volume holograms.

  In the present embodiment, the first element hologram 16 a and the second element hologram 16 b are formed from different regions of the single photosensitive material 18. Therefore, the first element hologram 16a and the second element hologram 16b constitute one first-stage H1 hologram 15 that is excellent in terms of handling.

  It should be noted that the wavelength of the laser light used when the first element hologram 16a is manufactured (that is, the wavelength of the object light L32 and the wavelength of the reference light L31) and the wavelength of the laser light used when the second element hologram 16b is manufactured (that is, , The wavelength of the object light L42 and the wavelength of the reference light L41) are incident on the first surface 10a of the hologram 10 to be manufactured shown in FIGS. 1 and 2 from the first direction d1, and the interference fringes 11a and 11b. The wavelength of the above-described light (reproduced illumination light) L11 (see FIGS. 1 and 2) that is diffracted with high efficiency is set to be the same. Further, the laser light source used when the first element hologram 16a is manufactured may be the same as or different from the laser light source used when the second element hologram 16b is manufactured.

  Next, a method for producing the screen switching hologram 10 using the first element hologram 16a and the second element hologram 16b forming the H1 hologram 15 thus obtained will be described. In the following description, an optical system (exposure apparatus) 20 including two or more laser light sources 21a and 21b is used to produce a screen switching hologram 10 made of a reflective volume hologram.

  First, the optical system (exposure apparatus) 20 used for producing the hologram 10 will be described. The optical system 20 includes a plurality of laser light sources, more specifically, the number of viewing zones z1 and z2 at which different images 5 and 6 are observed by being diffracted by the hologram 10 with high diffraction efficiency, in other words. The number of the interference fringes 11a and 11b to be recorded on the hologram 10 is the same as the number of laser light sources. Therefore, the optical system 20 for producing the hologram 10 shown in FIGS. 1 and 2 includes two laser light sources (first laser light source 21a and second laser light source 21b) as shown in FIG.

  The plurality of laser light sources 21a and 21b included in the optical system 20 oscillate laser beams having the same wavelength. Specifically, the light enters the first surface 10a of the hologram 10 to be manufactured shown in FIGS. 1 and 2 from the first direction d1 and is diffracted by the interference fringes 11a and 11b with high efficiency. It has the same wavelength as the light (reproduced illumination light) L11 (see FIGS. 1 and 2). Therefore, as at least one of the plurality of laser light sources 21a and 21b included in the optical system 20, the laser light source used at the time of manufacturing the first element hologram 16a or the laser light source used at the time of manufacturing the second element hologram 16b is used. Also good.

  As the laser light sources 21a and 21b as described above, various known laser light sources can be used. For example, as the laser light sources 21a and 21b, a helium-neon laser, an argon ion laser, a krypton ion laser, a neodymium yag laser, a semiconductor laser, or the like that can oscillate laser light with high output can be used. It should be noted that the laser light source used at the time of manufacturing the first element hologram 16a or the laser light source used at the time of manufacturing the second element hologram 16b can also be constituted by these various known laser light sources.

  As shown in FIG. 6, the optical system (exposure device) 20 reflects a laser beam from each of the laser light sources 21a and 21b and adjusts the optical path of the laser beam, and each of the laser light sources 21a and 21b. A spatial filter SF for spreading the laser light, a lens C for collimating the laser light spread by the spatial filter SF, and the like are included. With these optical devices, the laser beams from the laser light sources 21a and 21b can be incident on the photosensitive material 13, the first element hologram 16a, or the second element hologram 16b from a predetermined direction. .

  Next, a method for producing the hologram 10 using such an optical system (exposure apparatus) 20 will be described.

  First, the first-stage H1 hologram 15 constituted by the first element hologram 16a and the second element hologram 16b and the photosensitive material 13 are positioned with respect to each other. Specifically, as shown in FIGS. 5 and 6, the H1 hologram 15 and the photosensitive material 13 that forms the hologram 10 are arranged apart from each other in parallel. At this time, the H1 hologram 15 is a surface 15b (the surface of the photosensitive material 18) on which the object light L32 and L42 and the reference light L31 and L41 are incident when the first element hologram 16a and the second element hologram 16b are produced. 18b) is arranged so as to face the photosensitive material 13. In addition, the separation distance of the photosensitive material 13 from the H1 hologram 15 is based on the position of the photosensitive material 18 (H1 hologram 15), and the photosensitive material 13 is arranged with the models 5a and 6a when the element holograms 16a and 16b are manufactured. It is determined in the vicinity of the region.

  As the photosensitive material 13, various known photosensitive materials (dry plates) can be used in the same manner as the photosensitive material 18 constituting the first element hologram 16a and the second element hologram 16b. For example, the photosensitive material 18 can be composed of a photopolymer, a silver salt emulsion, dichromated gelatin, a photoresist, or the like.

  In this state, as shown in FIG. 6, the laser beams L61 and L62 generated from the plurality of laser light sources 21a and 21b are applied to the first element hologram 16a and the second element hologram 16b forming the H1 hologram 15 and the photosensitive material 13. Irradiate.

  The first laser light L61 generated from the first laser light source 21a of the optical system (exposure apparatus) 20 is reflected by the mirror M and proceeds while changing the traveling direction. The first laser light L61 is separated into two lights, a reference light L51 and a reproduction illumination light L52, at a desired light quantity ratio by the beam splitter BS.

  Thereafter, as shown in FIG. 6, the reference light L51 composed of the first laser light L61 is formed as a parallel light beam that has been expanded by the spatial filter SF and the lens C to such an extent that it can enter the entire desired region of the photosensitive material 13. Then, the light enters the photosensitive material 13. At this time, as shown in FIGS. 5 and 6, the reference light L <b> 51 forms the second surface 10 b of the photosensitive material 13 that forms the second surface 10 b opposite to the first surface 10 a of the hologram 10 described above. Is incident on the photosensitive material 13 along the first direction d1 described above. The reference light L51 is conjugate with respect to the reproduction illumination light L11 (see FIGS. 1 and 2) having a specific wavelength that is diffracted with high efficiency by the interference fringes 11a and 11b and the photosensitive material 13 (hologram 10). It becomes a relationship.

  On the other hand, the reproduction illumination light L52 is, as shown in FIG. 5, the first element as a parallel light beam spread to the extent that it can enter the entire desired area of the first element hologram 16a by the spatial filter SF and the lens C. It enters the hologram 16a. At this time, as shown in FIGS. 5 and 6, the reproduction illumination light L52 is opposite to the surface 15b (the surface 18b of the photosensitive material 18) on which the reference light L31 is incident when the first element hologram 16a is produced. Is incident on the first element hologram 16a along the above-described fourth direction d4. That is, the reproduction illumination light L52 has a conjugate relationship with respect to the reference light L31 at the time of manufacturing the first element hologram 16a and the first element hologram 16a (photosensitive material 18).

  Therefore, the reproduction illumination light L52 is diffracted with high diffraction efficiency in the first element hologram 16a, and reproduces the image 5 corresponding to the model 5a. Since the positional relationship between the H1 hologram 15 including the first element hologram 16a and the photosensitive material 13 is adjusted as described above, the first element hologram 16a is located near the photosensitive material 13 as shown in FIG. The spherical image 5 is reproduced three-dimensionally. Then, the light (reproduction light) having the information of the image 5 as the object light L53 from the side of the first surface 13a of the photosensitive material 13 that forms the first surface 10a of the hologram 10 described above. , Enters the photosensitive material 13.

  Since the object light L32 at the time of manufacturing the first element hologram 16a was scattered reflected light (see FIG. 3), the reproduction illumination light L52 was constituted by reproduction light diffracted by the first element hologram 16a. The object light L53 enters the photosensitive material 13 as convergent light. The object light L53 has a conjugate relationship with the reproduction light L12 (see FIGS. 1 and 2) having a specific wavelength diffracted with high efficiency by the first interference fringes 11a and the photosensitive material 13 (hologram 10). It becomes.

  As described above, as shown in FIG. 5, the reference light L51 and the object light L53 made of the first laser light L61 generated from the first laser light source 21a are incident on the photosensitive material 13 from different directions. become. As a result, the first interference fringes 11a are recorded in a desired region of the photosensitive material 13 due to interference between the reference light L51 made of the first laser light L61 and the object light L53 made of the first laser light L61. Become so. The first interference fringes 11a recorded here are, as can be understood from FIG. 1, the second direction d2 which is the center of the incident direction of the object light L53 on the photosensitive material 13, and the photosensitive material of the reference light L51. 13 extends in the direction parallel to the bisector of the angle formed by the first direction d1 that is the direction of incidence on 13.

  On the other hand, as shown in FIG. 6, the second laser light L62 generated from the second laser light source 21b of the optical system (exposure apparatus) 20 is the same as the first laser light L61 generated from the first laser light source 21a. Thus, the reference light L54 and the reproduction illumination light L55 are separated into two lights at a desired light quantity ratio.

  Thereafter, as shown in FIG. 6, the reference light L <b> 54 composed of the second laser light L <b> 62 is reflected by the mirror M and proceeds while changing the traveling direction. In particular, as shown in FIGS. 5 and 6, the reference light L54 passes through the first half-mirror HM so as to enter the photosensitive material 13 in the same direction as the reference light L51 composed of the first laser light L61. It is combined with the reference light L51 consisting of the laser light L61. After that, the reference light L54 composed of the second laser light L62 is combined with the reference light L51 composed of the first laser light L61 as shown in FIG. 5 and FIG. The beam is spread to the extent that it can enter the entire region, and enters the photosensitive material 13 as a parallel light beam from the second surface 13b side along the first direction d1 in the same manner as the reference light L51 composed of the first laser light L61. . Similar to the reference light L51 made of the first laser light L61, the reference light L54 is a reproduction illumination light L11 having a specific wavelength that is diffracted with high efficiency by the interference fringes 11a and 11b (FIGS. 1 and 5). 2) and the photosensitive material 13 (hologram 10).

  On the other hand, as shown in FIG. 5, the reproduction illumination light L55 is converted into the second element as a parallel light beam spread to the extent that it can be incident on the entire area of the desired region of the second element hologram 16b by the spatial filter SF and the lens C. The light enters the hologram 16b. At this time, as shown in FIGS. 5 and 6, the reproduction illumination light L55 is opposite to the surface 15b (the surface 18b of the photosensitive material 18) on which the reference light L41 is incident when the second element hologram 16b is produced. Is incident on the second element hologram 16b along the above-described fifth direction d5. That is, the reproduction illumination light L55 has a conjugate relationship with respect to the reference light L41 at the time of manufacturing the second element hologram 16b and the second element hologram 16b (photosensitive material 18).

  Therefore, the reproduction illumination light L55 is diffracted with high diffraction efficiency in the second element hologram 16b, and reproduces the image 6 corresponding to the model 6a. As shown in FIG. 5, the second element hologram 16 b reproduces a cubic image 6 in the vicinity of the photosensitive material 13 in a three-dimensional manner. Then, light (reproduction light) having such information of the image 6 enters the photosensitive material 13 from the first surface 13a side as the object light L56.

  Since the object light L42 at the time of manufacturing the second element hologram 16b was scattered reflected light (see FIG. 4), the reproduction illumination light L55 was constituted by reproduction light diffracted by the second element hologram 16b. The object light L56 enters the photosensitive material 13 as convergent light. The object light L56 has a conjugate relationship with the reproduction light L13 (see FIGS. 1 and 2) having a specific wavelength diffracted with high efficiency by the second interference fringes 11b and the photosensitive material 13 (hologram 10). It becomes.

  As described above, as shown in FIG. 5, the reference light L54 and the object light L56 composed of the second laser light L62 generated from the second laser light source 21b are incident on the photosensitive material 13 from different directions. become. As a result, the second interference fringes 11b are recorded in a desired region of the photosensitive material 13 due to interference between the reference light L54 made of the second laser light L62 and the object light L56 made of the second laser light L62. Become so. The second interference fringes 11b recorded here are, as can be understood from FIG. 1, the third direction d3 that is the center of the incident direction of the object light L56 on the photosensitive material 13, and the photosensitive material of the reference light L54. 13 extends in the direction parallel to the bisector of the angle formed by the first direction d1 that is the direction of incidence on 13.

  As described above, a plurality of interference fringes 11 a and 11 b can be recorded on the photosensitive material 13. When the interference fringe recording process is completed, a post-processing process is then performed on the photosensitive material 13 to obtain the hologram 10 made of a reflective volume hologram. The content of the post-processing varies depending on the material forming the photosensitive material 13, but as an example, ultraviolet irradiation and heat treatment can be performed on the photosensitive material 13 as a series of post-processing.

  By the way, in the present embodiment, the reference light L51 and the object light L53 composed of the first laser light L61 from the first laser light source 21a, and the reference light L54 composed of the second laser light L62 from the second laser light source 21b and The object light L56 is incident on the photosensitive material 13 at the same time. Thus, the hologram 10 can be formed in a short time by forming a plurality of interference fringes 11a and 11b on the photosensitive material 13 by simultaneous exposure. In addition, it is not necessary to prepare the optical system 20 with complicated operations multiple times. Furthermore, the diffraction efficiency in each interference fringe 11a, 11b can be adjusted by a simple operation such as adjusting the light amounts of the first laser light L61 and the second laser light L62. That is, the hologram 10 in which the interference fringes 11a and 11b having desired optical characteristics are accurately formed can be manufactured at low cost.

  Furthermore, the hologram 10 manufactured by the above-described method exhibits very excellent diffraction efficiency. This is because unnecessary interference fringes are not recorded on the hologram 10.

  As shown in FIG. 6, when the photosensitive material 13 is simultaneously exposed from three directions, incident light (reference light) from the first direction d1 and incident light (object light) from a direction centering on the second direction d2 are used. In addition to the second interference fringe 11b caused by the incident light (reference light) from the first interference fringe 11a and the first direction d1 and the incident light (object light) from the direction centering on the third direction d3, the second direction Further interference fringes due to the object light L53 from d2 and the object light L56 from the third direction d3 can also be recorded on the photosensitive material 13. In particular, the object light L53 from the second direction d2 and the object light L56 from the third direction d3 are convergent lights, and do not travel in only one strict direction. Therefore, due to the object lights L53 and L56, very complicated interference fringes that may significantly reduce the diffraction efficiency of the first interference fringes 11a and the second interference fringes 11b can be formed.

  However, in the present embodiment, as described above, the laser beams L61 and L62 generated from the plurality of laser light sources 21a and 21b are the two beams of the reference beams L51 and L54 and the object beams L53 and L56, respectively. Simultaneously incident on the photosensitive material 13. The coherence of the laser beams oscillated from different laser light sources is extremely low even if the laser beams have the same wavelength. The above-described method for manufacturing the hologram 10 has been invented based on such characteristics relating to laser beam interference.

  7 to 10, the inventor of the present invention generates interference from separated light obtained by separating the laser light L81 generated from the same laser light source 23c and two different laser light sources 23a and 23b. The result of investigating the interference between the laser beams L71 and L72 thus obtained is shown. As shown in FIG. 7, two laser beams L71 and L72 oscillated from two different laser light sources 23a and 23b are synthesized by a half mirror HM, then spread by a spatial filter SF and projected onto a screen 25. . In this case, as shown in FIG. 9, the light 27 is projected on a substantially circular area corresponding to the diffusion direction by the spatial filter SF on the screen 25, and no interference pattern consisting of bright and dark stripes was observed. On the other hand, as shown in FIG. 8, the laser beam L81 generated from the single laser light source 23c is once separated by the beam splitter BS, and then the separated beams L81a and L81b are synthesized again by the half mirror HM, and then the spatial filter. It was spread by SF and projected onto the screen 25. In this case, as shown in FIG. 10, the light 28 is projected in a stripe shape on the screen 25 in the circular area corresponding to the diffusion direction by the spatial filter SF, and the interference pattern consisting of bright and dark stripes is clearly observed. It was. That is, the experiments shown in FIGS. 7 to 10 also confirmed that the coherence of the laser beams L71 and L72 having the same wavelength emitted from the different laser light sources 23a and 23b is remarkably reduced. In the experiments shown in FIGS. 7 to 10, commercially available semiconductor pumped solid state (DPSS) lasers that oscillate laser light having a wavelength of 532 nm were used as the laser light sources 23a, 23b, and 23c.

  Based on such interference characteristics of laser light, simultaneous exposure using a plurality of laser light sources 21a and 21b consists of laser light generated from the same laser light source among the plurality of laser light sources 21a and 21b. Only the interference fringes 11 a and 11 b between the reference light and the object light are recorded on the photosensitive material 13. That is, when the laser beams generated from each of the plurality of laser light sources enter the photosensitive material 13 from two different directions as reference light and object light, respectively, the photosensitive material 13 has the same number of laser light sources as the number of laser light sources. Only interference fringes are formed. Therefore, in the example of FIG. 5, no interference fringes are formed between the first laser beam L61 and the second laser beam L62. As a result, the object beam L53 of the first laser beam L61 and the second laser beam L62 Interference fringes formed by interference with the reference light L56 are not recorded on the photosensitive material 13.

  According to the present embodiment as described above, a plurality of laser beams L61 and L62 are generated from two or more laser light sources 21a and 21b, and the laser beams L61 and L62 are the reference beams L51 and L54 and the reference beams, respectively. The object lights L53 and L56 traveling in directions different from L51 and L54 are simultaneously incident on the photosensitive material 13 from a plurality of directions, whereby a plurality of interference fringes 11a and 11b are produced. As a result, the interference fringes 11a and 11b are only interference fringes formed by interference between the object light and the reference light generated from the same laser light source of the two or more laser light sources 21a and 21b. Only the same number of interference fringes 11a and 11b as the number of the two or more laser light sources 21a and 21b are included. That is, for example, interference fringes or the like between the two object lights L53 and L56 incident from different directions are not recorded on the hologram 10, and unnecessary interference fringes are prevented from being recorded on the hologram 10. Therefore, it is possible to prevent incident light from being diffracted in an unintended direction by unnecessary interference fringes. Thereby, the hologram 10 can diffract incident light with high diffraction efficiency, and the images 5 and 6 can be reproduced brightly in a plurality of different directions. From this point, the function expected of the hologram 10, for example, the function of improving the designability and the function of indicating the authenticity of the article to which the hologram 10 is attached can be effectively exhibited. In particular, the reproduction mode of the images 5 and 6 by the hologram 10 is complicated, and in this respect, it is difficult to forge the hologram 10, so that the hologram 10 functions extremely effectively as a sign for indicating authenticity. Further, since the hologram 10 has the interference fringes 11a and 11b recorded by simultaneous exposure, it can be manufactured at low cost and with high accuracy, and the optical characteristics can be easily adjusted.

  Further, according to the present embodiment, unnecessary interference fringes are not formed on the hologram 10 as described above. Therefore, the images 5 and 6 having a desired shape in each observation direction can be reproduced so as to be clearly observed as images having a predetermined shape. Further, even when one image observed from one direction is reproduced so as to overlap with another image observed from the other direction in the vicinity of the hologram 10, each image is clear at the overlapping portion. Can be observed. As a result, a plurality of images observed from each direction can have different shapes in the overlapping portion in the vicinity of the hologram 10. According to such a hologram 10, the function expected for the hologram 10, for example, the function of improving the designability and the function of indicating the authenticity of the article to which the hologram 10 is attached can be more effectively exhibited. it can.

  Furthermore, according to the present embodiment, as well shown in FIG. 5, the incident directions d4 of the reproduction illumination light L52 incident on one element hologram 16a among the plurality of element holograms 16a and 16b are plural. Of the element holograms 16a, 16b, the incident direction d5 of the reproduction illumination light L55 incident on another element hologram 16b different from the one element hologram 16a is different. According to such an aspect, the freedom degree of arrangement | positioning of optical apparatuses, such as the mirror M which defines the optical path of each laser beam L61, 62, increases, and it is prevented that the said optical apparatus interferes with each other. Thereby, the structure of the optical system 20 can be simplified greatly. Therefore, even if the plurality of element holograms 16a and 16b are arranged adjacent to each other, the laser beams L61 and L62 generated from the laser light sources 21a and 21b different from each other are applied only to the target element holograms 16a and 16b. More accurate incidence can be achieved. Thereby, generation | occurrence | production of a stray light etc. can be suppressed and it can prevent more stably that the unintended interference fringe will be recorded.

  As mentioned above, although this invention was demonstrated based on one embodiment illustrated, this invention is not limited to these embodiment, In addition, it can implement in a various aspect. Below, an example of a deformation | transformation is demonstrated.

(Modification 1)
In the above-described embodiment, the example in which the hologram 10 is configured as a reflective volume hologram has been described, but the present invention is not limited thereto. For example, the hologram 10 is configured as a transmission-type volume hologram including a plurality of interference fringes recorded corresponding to each of light that travels in different directions and enters the hologram from the same plane side. May be. Also by such a modification, the same effect as embodiment mentioned above can be acquired.

(Modification 2)
In the above-described embodiment, when producing a hologram 10 capable of reproducing an image so that different images are observed from at least two directions by light having a specific wavelength incident from one direction, the same wavelength as the specific wavelength is produced. Although the example in which the interference fringes 11a and 11b are recorded on the photosensitive material 13 using the laser beam having the wavelength of is shown, it is not limited thereto.

  Even if light having a wavelength different from the specific wavelength is incident on the hologram at an incident angle satisfying the Bragg interference condition of the interference fringes 11a and 11b, it is diffracted by the interference fringes 11a and 11b with high diffraction efficiency. Become. In this phenomenon, reference light comprising laser light having the wavelength different from the specific wavelength along the incident direction (illumination direction) of light having a wavelength different from the specific wavelength and the diffraction direction (reproduction direction) thereof, and By making the object light incident on the photosensitive material 13, the same interference fringes 11 a and 11 b as in the above-described embodiment can be recorded on the photosensitive material 13. Therefore, also by this modification, the same operation effect as embodiment mentioned above can be acquired.

  For the same reason, in the above-described embodiment, when producing the element holograms 16a and 16b, an example in which interference fringes are recorded on the photosensitive material 18 using a laser beam having the same wavelength as the specific wavelength. Although shown, it is not limited to this.

(Modification 3)
In the above-described embodiment, the hologram 10 reproduces the images 5 and 6 so that the different images 5 and 6 are observed from the two directions by the light having a specific wavelength incident from one direction. However, the present invention is not limited to this. The images 5 and 6 may be reproduced so that the holograms 10 and 6 are different from each other from three or more directions. According to such a modification, it can be expected that the same operational effects as those of the above-described embodiment can be obtained more remarkably.

  The hologram according to this modification can be manufactured in the same manner as the manufacturing method in the above-described embodiment using H1 holograms having three or more element holograms and the same number of laser light sources as the number of element holograms.

(Modification 4)
Furthermore, although the example in which the element holograms 16a and 16b are configured as transmission-type volume holograms has been described in the above-described embodiment, the present invention is not limited thereto. For example, at least one of the element holograms 16a and 16b may be configured as a reflective volume hologram. Furthermore, at least one of the element holograms 16a and 16b may be configured as a hologram other than the volume hologram, for example, a computer-generated hologram (CHG).

(Modification 5)
Furthermore, in the above-described embodiment, an example in which a plurality of element holograms constituting the H1 hologram are arranged adjacent to each other in one direction has been described, but the present invention is not limited to this. For example, a large number of element holograms may be arranged side by side in two or more directions, or a large number of element holograms may be randomly arranged on the surface defined by the H1 hologram. . A plurality of element holograms may be arranged with a gap.

(Modification 6)
Furthermore, in the above-described embodiment, an example in which the plurality of element holograms 16a and 16b are formed in each region of one photosensitive material 18 using the light-shielding masks 19a and 19b is shown. Not limited. A plurality of element holograms may be formed on different photosensitive materials. In this modification, a plurality of element holograms produced separately are arranged in a position facing the photosensitive material 13 that forms the hologram 10 and held by a holder or the like. In the same manner as the embodiment, exposure of the photosensitive material 13 that forms the hologram 10 can be performed.

(Modification 7)
In the above-described embodiment, the example in which the images 5 and 6 observed from the different viewing zones z1 and z2 are recorded in the hologram 10 as a geometric three-dimensional shape is shown, but the present invention is not limited to this. For example, in combination with a special reproduction mode of the hologram 10, an image that can effectively improve designability and an image that can effectively display authenticity are recorded on the hologram 10. It may be.

  For example, the images observed in the adjacent viewing zones or the adjacent directions change little by little, and thereby, by changing the observation direction, a plurality of images may be observed like a moving image. Good.

  Further, authenticity determination information for displaying authenticity may be included only in any of a plurality of images observed from different directions (viewing zones). For example, when one image observed from one direction (viewing zone) is reproduced so as to overlap with another image observed from the other direction in the vicinity of the hologram 10, the overlapping portion is authentic. The determination information may be displayed. In this case, authenticity can be displayed by switching to another image, and forgery of the hologram can be made more difficult.

(Modification 8)
In the embodiment described above, the hologram 10 diffracts the light L11 incident from one direction, thereby reproducing the images so that the different images 5 and 6 are observed in the same color from different viewing zones. Although shown, it is not limited to this. For example, the image may be reproduced so that the hologram 10 diffracts the light L11 incident from one direction so that different images are observed in different colors and different directions (viewing zones).

  In the above-described embodiment, the hologram according to this modification includes the wavelength of the first laser light L61 oscillated from the first laser light source 21a and the wavelength of the second laser light L62 oscillated from the second laser light source 21b. , Can be manufactured. According to the hologram according to this modification obtained in this way, when white light such as illumination is incident on the hologram, the color (for example, red) in which one image is reproduced is the other Is different from the reproduced color (for example, blue). According to such a modification, it can be expected that the same operational effects as those of the above-described embodiment can be obtained more remarkably.

(Modification 9)
Furthermore, in the above-described embodiment, an example in which laser light having a specific wavelength is generated from the laser light sources 21a and 21b used for manufacturing the interference fringes 11a and 11b has been described. Therefore, according to the example shown in the above embodiment, the images 5 and 6 are reproduced with a single color. However, the present invention is not limited to such an example, and one image 5 is reproduced with a plurality of colors. You may be made to do.

  As an example, a hologram capable of reproducing a color image can be produced as follows. First, an element hologram capable of reproducing an image in full color is prepared. Then, when exposing the photosensitive material 13, along the optical path of each laser beam generated from each laser light source in the above-described embodiment, a laser beam in a wavelength band capable of displaying red, a wavelength capable of displaying green. A laser beam in a band and a laser beam in a wavelength band that can display blue are combined and travel. When white light is incident on the hologram thus produced, each reproduced image is observed in full color.

(Modification 10)
In the above-described embodiment, the example in which the reference light is collimated by the lens C when the interference fringes are recorded on the hologram 10 or each of the element holograms 16a and 16b has been described. For example, the reference light may be diffused light.

(Modification 11)
Although several modifications to the above-described embodiment have been described above, a plurality of modifications can be applied in appropriate combination.

5,6 Image 5a, 6a Model 10 Hologram (Screen switching hologram, H2 hologram)
10a, 10b surface 11a, 11b interference fringe 13 photosensitive material 13a, 13b surface 15 H1 hologram 16a, 16b element hologram 18 photosensitive material 18a, 18b surface 21a, 21b laser light source

Claims (9)

A method for producing a hologram capable of reproducing an image so that different images are observed from at least two directions by light incident from one direction,
The laser beams having the same wavelength generated by each of the two or more laser light sources are separated into reproduction illumination light and reference light, respectively, and then two laser beams generated from the two or more laser light sources are formed. Reproduction light from the plurality of element holograms that causes the above reproduction illumination light to enter each of the plurality of element holograms, reproduce an image from each of the plurality of element holograms, and reproduce the image And two or more reference lights each consisting of laser beams generated from the two or more laser light sources, simultaneously incident on the photosensitive material, to record interference fringes on the photosensitive material,
In the step of recording the interference fringes,
Reproduced light from the plurality of element holograms travels in different directions and enters the photosensitive material from the same side,
The two or more reference lights are incident on the photosensitive material from the same side.
A method for producing a hologram, comprising: The reproduction illumination light incident on one element hologram of the plurality of element holograms and the reproduction illumination light incident on another element hologram different from the one element hologram among the plurality of element holograms are mutually Proceed in different directions, each incident on the corresponding element hologram,
The method for manufacturing a hologram according to claim 1. The number of the two or more laser light sources is the same as the number of the element holograms,
Two or more reproduction illumination lights composed of each of the laser beams generated from the two or more laser light sources respectively enter one of the element holograms different from each other among the plurality of element holograms.
The method for producing a hologram according to claim 1, wherein the hologram is produced. Reconstructed light from the plurality of element holograms travels in one of the at least two directions and enters the photosensitive material.
The method for producing a hologram according to any one of claims 1 to 3, wherein: The two or more reference lights composed of each of the laser beams generated from the two or more laser light sources proceed in the same direction as each other and enter the photosensitive material.
The method for manufacturing a hologram according to any one of claims 1 to 4, wherein: In the step of recording the interference fringes, only the interference fringes formed by interference between the reproduction light and the reference light generated from the same laser light source of the two or more laser light sources are recorded.
The method for producing a hologram according to any one of claims 1 to 5 , wherein: A hologram that reproduces an image so that different images from at least two directions are observed on the same side of the hologram by light incident from one direction,
The laser beams having the same wavelength generated from each of the two or more laser light sources are separated into the reproduction illumination light and the reference light, respectively, and then two laser beams generated from the two or more laser light sources are formed. Reproduction light from the plurality of element holograms that causes the above reproduction illumination light to enter each of the plurality of element holograms, reproduce an image from each of the plurality of element holograms, and reproduce the image A plurality of interference fringes recorded by simultaneously making two or more reference lights each consisting of laser light generated from the two or more laser light sources incident on the photosensitive material,
The plurality of interference fringes include only interference fringes formed by interference between the reproduction light and the reference light, which are laser beams generated from the same laser light source among the two or more laser light sources.
A hologram characterized by that. The interference fringes include only the same number of interference fringes as the number of the two or more laser light sources.
The hologram according to claim 7 . An article to which the hologram according to claim 7 or 8 is attached.

Images