JPS63305381A - Color hologram and its production - Google Patents

Abstract

PURPOSE:To obtain a natural color reproduced image by forming three primary color reproduced images corresponding to the density of three primary color components of an object and superposing the three reproduced images. CONSTITUTION:A color hologram is constituted of three color-separated holograms 1R, 1G, 1B for forming respective reproduced images 13 of the same object on the same position, respective reproduced images 18 are constituted of three primary color-reproduced images corresponding to the density of respective three primary color components of the object and the three reproduced images 18 are superposed on each other. Consequently, the three primary colors are observed so as to be added and mixed and a natural color reproduced image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color hologram and a method for manufacturing the same.

[Conventional technology]

With the development of technology to obtain coherent light such as lasers,
Holographic technology is also becoming increasingly popular. In this field of holography, coherent light is used,
A hologram is created in which object image information is recorded as interference fringes. When this hologram is irradiated with reproduction light, the object image can be faithfully reproduced in three dimensions due to the diffraction effect of the interference fringes.

As a method for colorizing hologram reconstructed images,
A rainbow hologram is used.

This rainbow hologram has a very beautiful appearance because the reproduced image shines red depending on the viewing angle. However, from a certain viewpoint position, you can only see a certain color at all times.

A color hologram that allows various colors to be observed even when the viewpoint position is fixed is proposed in Japanese Patent Publication No. 57-501697. In this color hologram, a hologram surface is formed by consecutively forming a plurality of regions each having a predetermined area, and the pitch of the interference fringes is made different for each region. Even if the viewpoint is fixed, the wavelength of the diffracted light directed toward the viewpoint is different for each region, so various colors can be observed simultaneously for each region.

[Problem that the invention seeks to solve]

In the conventional color hologram described above, various colors can be observed, but the colors are not the colors of the solid object. In other words, a reproduced image with the natural colors of the object is not obtained, but only colors are artificially and intentionally added.

Therefore, even if you look at the reproduced image, you cannot get the same sense of reality as if you were looking at a real object.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a color hologram and a method for manufacturing the same that can obtain a natural color reproduced image of an object.

[Means for solving problems]

The present invention is a color hologram, in which three color separation holograms, first, second, and third, each having a hologram pattern formed thereon that produces a reconstructed image of the same subject, are placed at the same viewpoint position to reproduce the respective reconstructed images. Each reconstructed image by the first, second, and third color separation holograms is
They each consist of a first primary color, a second primary color, and a third primary color, and these three primary colors can be additively mixed with each other, and each reproduction by the first, second, and third color separation holograms The image includes a first primary color component, a second primary color component, and a second primary color component of the subject, respectively.
A hologram pattern is formed so that the shading information of the third primary color component is reproduced.

In order to manufacture the above-mentioned color hologram, in the present invention, an object is color-separated into three primary colors, first, second, and third, which can be additively mixed with each other, and the first, second, and third primary colors are separated. obtaining a color separation image and obtaining first, second, and third color separation primary holograms in which hologram images for each color separation image are formed; and a reconstructed image of the first color separation primary hologram. , exposing interference fringes with reference light irradiated from a first direction onto a first photosensitive original plate, and producing a first color separated image consisting of a first primary color at a predetermined viewpoint position by reproduction. forming a second color-separated secondary hologram image; and exposing interference fringes between the reproduced image of the second color-separated primary hologram and the reference light irradiated from the second direction onto a second photosensitive original plate. and forming a second color-separated secondary hologram image such that a second color-separated image consisting of a second primary color is generated at a viewpoint position, and a reproduced image of a third color-separated primary hologram. , a third photosensitive original plate is exposed to interference fringes with a reference beam irradiated from a third direction, and a third color separated image consisting of a third primary color is generated at the viewpoint position by reproduction. Color separation 2
forming a secondary hologram image; and obtaining a color hologram by arranging and fixing the first, second, and third secondary holograms at positions where the reproduced images are superimposed. It is.

[For production]

In the color hologram according to the present invention, the three constituent elements are
Each of the two color separation holograms generates a reconstructed image of the same subject at the same position. In addition, each reconstructed image is a reconstructed image composed of three primary colors, depending on the shading of each component of the three primary colors of the subject, and by superimposing these three reconstructed images, the three primary colors are additively mixed and observed. is,
A natural color reproduction image can be obtained.

Furthermore, in the method for manufacturing a color hologram according to the present invention,
The subject is divided into color separation images of three primary colors to form a color separation primary hologram, and based on this color separation primary hologram, color separation 2
Since a second hologram is formed, a color separation hologram having a hologram pattern that generates a reproduced image as described above can be formed.

〔Example〕

The present invention will be described below based on illustrated embodiments. FIG. 1 is a diagram showing the principle of a color hologram according to the present invention.

This color hologram consists of three color separation holograms IR,
It consists of IC and IB. Each color hologram IR
, IC, and IB contain the red (R), green (G), and blue (
The color components of three primary colors called B) that can be additively mixed are recorded. When this color-separated hologram is irradiated with white reproduction light 2, a reconstructed image can be observed from a viewpoint 3 using the light having the wavelength of each color-separated component. For example, when the color separation hologram IR is irradiated with the reproduction light 2, the reproduced image can be observed from the viewpoint 3 by the diffracted light 4R. At this time, the diffracted light 4R consists of red wavelength component light. Since the reproduction light 2 is white light, diffracted light of other wavelengths will actually be emitted from the color separation hologram IR, but since diffracted light has wavelength dependence, diffracted light of wavelengths other than red is This means that you will not be heading to the position of viewpoint 3. In other words, interference fringes are recorded in the color separation hologram IR such that a red reconstructed image can be observed at the position of the viewpoint 3. Similarly, interference fringes are recorded on the color separation holograms IG and IB so that green and blue reproduced images can be observed at the position of the viewpoint 3, respectively.

Therefore, at viewpoint 3, the reconstructed images of the three primary colors can be observed as hologram reconstructed images from each color separation hologram, overlapping each other. In a hologram, even the shading information of an object image is reproduced. This is because the gradation information is recorded as the magnitude of the diffraction efficiency of the diffraction grating formed on the hologram surface. For example, a clear diffraction grating with high diffraction efficiency is formed in a bright gradation area, and an unclear diffraction grating with low diffraction efficiency is formed in a dark gradation area. Moreover, since each color separation hologram records shading information for each color component of the three primary colors, by overlapping these reconstructed images, it becomes possible to observe a reconstructed image of natural colors.

Next, an embodiment of the method for manufacturing a color hologram according to the present invention will be described. FIG. 2 is a flowchart showing the basic procedure of this manufacturing method. This method consists of three steps: creation of a color-separated primary hologram (step S1), creation of a color-separated secondary hologram (step S2), and creation of a color hologram (step S3). below,
Each stage will be explained in turn.

1. Creation of color-separated primary holograms Here, color-separated primary holograms are created for each of the three primary colors RGB. Two methods will be described below.

(1) First method This method is a method in which a color-separated photograph is created by color-separating an object using a general photographic method, and a hologram is formed based on this color-separated photograph. That is, first the subject is R
Three color-separated photos 5R, separated by each of the three primary colors of GB.
Create 5G and 5B.

In this color separated photograph 5, each primary color component of the subject is recorded as a two-dimensional image. A hologram is formed using this color separated photograph 5 as an object image.

For example, for the primary color R, as shown in FIG. 3, a color separation photograph 5R and a photosensitive original plate 6R are arranged.

Then, one laser beam is divided into illumination light 7 and reference light 8,
The illumination light 7 is transmitted through the color separation photograph 5R to obtain an object light 9, and interference fringes between the object light 9 and the reference light 8 are recorded on the photosensitive original 6R. As the photosensitive original plate, a silver salt photographic material or the like can be used. The photosensitive original plate on which the interference fringes are recorded in this manner becomes a color-separated primary hologram 6R for the primary color R. Similarly, color-separated primary holograms 6G and 6B are created.

(2) Second method This method is a method in which a hologram is formed by directly color-separating an object. That is, the object is separately irradiated with illumination light of the three primary colors of RGB, and a hologram is created based on the object light from there. for example,
Regarding the primary color R, as shown in FIG. 4, a laser beam having the wavelength of the primary color R is divided into illumination light 7R and reference light 8R, and the illumination light 7R is irradiated onto the subject 10 to obtain object light 9R. Interference fringes between the object beam 9R and the reference beam 8R are recorded on the photosensitive original plate 6R. The photosensitive original plate on which the interference fringes are recorded in this manner becomes a color-separated primary hologram 6R for the primary color R. Similarly, color-separated primary holograms 6G and 6B are created. Both stereoscopic information and contrast information of the subject 10 are recorded in this color-separated primary hologram, making it possible to reproduce a three-dimensional reconstructed image. As the light used to form the color-separated primary hologram, for example, red wavelength light from a helium neon laser can be used as the primary color R, and green and blue wavelength light from an argon ion laser can be used as the primary colors G and B, respectively. In addition, as a photosensitive original plate, R
A material having GB color photosensitivity is used.

(2) Creation of color-separated secondary holograms Three color-separated secondary holograms are created based on the three color-separated primary holograms created in step S1. This color-separated secondary hologram is created using the same principle as the creation of a conventional rainbow hologram.

First, we will briefly explain the principle of rainbow holograms. The primary hologram obtained in step S1 is a hologram that should originally be reproduced with monochromatic reproduction light such as a laser, and strictly speaking, it cannot be reproduced with white light. this is,
This is because the imaging position of the reconstructed image differs depending on the wavelength, and if white light is used for reproduction, reconstructed images shifted for each of the various wavelength components included in the white light will overlap. In order to reproduce such a laser-reproduced hologram using white light,
There is a method of using a thin slit and looking through the slit. By viewing through a slit that satisfies predetermined conditions, it is possible to cut out components other than monochromatic light, making it possible to reproduce white light.

However, it is not practical to always use a slit during playback. Therefore, it was developed with the idea of recording the slit for viewing into the hologram image as well.
It's a rainbow hologram. This rainbow hologram fully enables reproduction using white light. Figure 5 (
a) is a diagram showing the principle of creating this rainbow hologram. First, as shown in the figure, a mask 11 is placed on the hologram surface of the primary hologram 6. This mask 11 has
A narrow slit 12 (for example, about 5 mm wide) is provided, and a reproduction light 13 such as a laser beam is provided to the primary hologram 6.
When the beam is irradiated, a reconstructed image is formed by the diffracted light 14 passing through the slit 12. Interference fringes between this reproduced image and the reference beam 15 (which can be obtained by dividing the reproduced beam 13) are recorded on the photosensitive original plate 16.

The secondary hologram recorded on this photosensitive original plate 16 becomes a rainbow hologram. That is, as shown in FIG. 5(b), when the photosensitive original plate 16 is irradiated with white reproduction light 17, a reproduced image 18 of the subject and a reproduced image 19 of the mask 11 are formed. Therefore, from the viewpoint 3, it is as if the reconstructed image 18 is seen through the slit image 20 of the mask image 19.
It becomes like watching. Therefore, unnecessary wavelength components are equivalent to being cut by a mask, and even if white light is used as reproduction light, almost the same result as a reproduced image using laser light can be obtained. Note that when the viewpoint 3 is moved, the imaging position of the mask image 19 shifts to a different wavelength, so the reconstructed image 18 can be observed from any position.

The above is a conventionally known method for creating a rainbow hologram, but in the present invention, by utilizing this principle, a color-separated secondary hologram 1 is created from the color-separated primary holograms 6R, 6G, and 6B.
Create 6R, 16G, and 16B. In other words, Fig. 5 (
If the color-separated primary holograms 6R, 6G, and 6B created in step S1 are used as the primary holograms 6 shown in a), the photosensitive original plate 16 becomes the color-separated secondary holograms 16R, respectively.
916G and 16B are formed. Therefore, by irradiating these secondary holograms 16R, 16G, and 16B with the reproduction light 17, reproduced images 18R, 218G, and 18B are obtained, respectively. Each reproduced image has shading corresponding to each primary color component of the subject. However, this reproduced image 18R,1
8G and 18B are not necessarily formed in red, green, and blue colors, respectively. Let us now consider the factors that determine the color of each reproduced image.

Now, when considering the diffraction angle due to the diffraction pattern on the hologram, this diffraction angle differs depending on the wavelength of the diffracted light. This diffraction pattern is formed during hologram formation.
Since the interference fringes are formed between the object light and the reference light, the diffraction angle of the diffracted light having each wavelength is determined by the pitch of the interference fringes. FIG. 6 shows a principle diagram for forming a general hologram. That is, the photosensitive original plate 21 is irradiated with the object light 22 and the reference light 23 to form this interference fringe pattern on the photosensitive original plate 21 . Now, the incident angle of the object beam 22 is θ, and the reference beam 23 is
The incident angle is θ, and the wavelengths of the object beam 22 and reference beam 23 are λ
, the interference fringe pitch P formed on the photosensitive original plate 6 is expressed by the following equation.

P-λ/(sin θ+sln θ) If the object light 22 is made perpendicular to the photosensitive original plate 21 as shown in FIG. 6, then θ −0, so P-λ/sin θ. Usually, a laser is used as a light source for the object light and the reference light, so the wavelength λ is usually constant. Therefore, the interference fringe pitch P is determined by the incident angle θ of the reference beam 23, and the diffraction angle during reproduction is determined by the incident angle θ of the reference beam during recording. After all, in FIG. 5(a), the color-separated secondary holograms 16R, 16G,
16B, if the incident angle of the reference beam 15 is set to a predetermined value, the colors of the reproduced images 18R, 18G, and 18B formed as shown in FIG. 16B can be changed to red, green, and blue, respectively. It can be done.

■ Creation of color holograms In step S2, three color-separated secondary holograms 16R, 16 are created.
Once G and 16B are created, a color hologram is created based on these. In the general production process,
Since the same color holograms will be mass-produced, the color-separated secondary hologram created in step S2 will first be used as an original for duplication. By performing duplication at this stage, it is only necessary to perform step S3 for mass-produced products, and manufacturing costs can be significantly reduced. Since various methods of replicating holograms are known, examples thereof will be briefly explained here. If, for example, a photoresist is used as the photosensitive original plate 16 in step S2, the obtained color-separated secondary hologram will be of a relief type, that is, the surface will have irregularities of interference fringes formed thereon.

Therefore, the surface of this relief-type hologram is plated with nickel, and this is peeled off to form a relief-type hologram on a metal plate. If necessary, it is provided with an appropriate backing and used as a press plate. Alternatively, a larger number of press plates can be reproduced from this nickel press plate. Next, this press plate will be used to mass produce color-separated secondary holograms. For example, when a thermoplastic film such as vinyl chloride is hot-pressed with a press plate, a relief pattern is copied in the same way as on a record, and a color-separated secondary hologram made of vinyl chloride can be obtained.

The three color-separated secondary holograms obtained by the above method are transparent holograms, and if these three pieces are superimposed as the color-separated holograms IR, IG, and IB shown in Fig. 1 and reproduced by transmitted light, , a color hologram reconstructed image is obtained.

Therefore, in order to make a practical color hologram, it is necessary to adhere three color separation holograms to each other.

However, if a general adhesive is used for bonding, the relief pattern formed on each color-separated hologram will optically disappear. Therefore, first, a thin film layer made of a material with a refractive index significantly different from that of the material constituting the color separation hologram (in this example, vinyl chloride) and the adhesive was formed on each relief pattern. do.

This thin film layer can be obtained, for example, by vacuum deposition of a transparent metal oxide or sulfide. In this way, by adhering thin film layers having different refractive indexes, the relief pattern is optically maintained. The technology for sandwiching this thin film layer is described in Japanese Patent Application Laid-Open No. 61-2727.
It is detailed in the publication No. 73, so please refer to that publication for details.

In addition, when recording delicate images in which the thickness of the support (generally film) for each color separation hologram considerably affects the quality of the reproduced image, each color separation hologram is formed into a transfer foil structure and a common support is used. By transferring each color separation hologram onto the body, a hologram composite of the three primary colors of RGB can be created in an extremely thin state on a common support, as if three color separation holograms were overlapped on one plane. This results in a state like this, allowing faithful image reproduction.

Although the above description has been made regarding a transmission reproduction type color hologram, the present invention is similarly applicable to a reflection reproduction type color hologram. For example, in the case of the above-mentioned method of bonding by sandwiching thin films, a reflective reproduction type color hologram can be obtained by using a reflective film as the thin film.

In the reflective reproduction type color hologram, in FIG. 1, reproduction light 2 is irradiated onto the Yira hologram from the same side as the viewpoint 3. Reflected and diffracted light from each color separation hologram is incident on the viewpoint 3. In order to create a reflective reproduction type color hologram, it is preferable to form a reflective layer on the back surface of the color separation hologram (color separation hologram IB in the configuration shown in FIG. 1) located on the rearmost side. Figure 7 shows the color separation hologram IB,
This is an example in which a reflective layer 25 made of an aluminum vapor tube layer is formed. A support 24 is formed on the back surface of the color separation hologram IB. FIG. 7(a) shows an example in which a reflective layer 25 is deposited on the back surface of the support 24, and FIG. An example in which the film is deposited between the color-separating hologram IB, and FIG. In the example shown in FIG. 2(a), the manufacturing process is simple because aluminum can be vapor-deposited after manufacturing a composite body in which three color separation holograms are integrated, but the thickness of the support 24 is large. This has the disadvantage that the reproduced image appears double. In the example shown in FIG. 6(b), the thickness of the color separation hologram IB can be set to about 1 μm, which does not cause the above-mentioned disadvantages, and it is also possible to pre-deposit aluminum on the support 24. However, since the above-mentioned thin film reflective layer to obtain the primary color B image is also required on the relief forming surface of the color separation hologram IB, an extra vapor deposition step is required. The example in figure (c) is
This is the most suitable example for creating a reflection reproduction type hologram. Since the reflective layer 25 is formed on the relief forming surface of the color separation hologram IB, the number of vapor deposition steps can be minimized. After performing this vapor deposition, a color separation hologram IC is placed on top of it.
, IR, a color hologram (reflective reproduction type here) as shown in FIG. 1 can be obtained.

Although the present invention has been described above based on several embodiments, the present invention is not limited to these embodiments, and various modifications are possible. For example, the order in which the color separation holograms are stacked is not limited to the RGB order, but may be in any order. Furthermore, a white reflective metal other than aluminum (for example, nickel, chromium, silver, etc.) may be used as a reflective layer for obtaining a reflective reproduction type color hologram. Furthermore, in the creation of the color-separated primary hologram in step S1, although a color-separated photograph is used in the first method described above, a halftone color-separated photograph can also be used as in the case of printing. Moreover, in order to create a three-dimensional effect of the subject, stereographic holograms whose colors have been separated in advance may be used. In such a stereographic hologram, a hologram is created based on a series of photographs, so it is possible to express a moving subject, a very large subject, etc.

〔Effect of the invention〕

As described above, in the color hologram according to the present invention, the color hologram is constituted by three color separation holograms that each generate a reconstructed image of the same subject at the same position, and each reconstructed image has three parts of the subject.
Since the reconstructed image is made up of three primary colors that correspond to the shading of each component of the primary colors, by superimposing these three reconstructed images, the three primary colors are observed as an additive mixture, and a natural color reconstructed image is obtained. be able to.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic principle of the color hologram according to the present invention, Fig. 2 is a flowchart showing the basic procedure of the method for producing a color hologram according to the present invention, and Figs. 3 and 4 are as shown in Fig. 2. Of the steps shown, FIGS. 5 and 6 are diagrams showing an example of the method for creating a color-separated primary hologram in step S1, and FIGS. FIG. 7 is a diagram showing an example of the procedure for creating a color hologram in step S3 of the procedure shown in FIG. 2. IR, IC, IB... Color separation hologram, 2... Reproduction light, 3... Viewpoint, 4R, 4G, 4B... Diffracted light, 5
R...red color separation photograph, 6,6R...photosensitive original plate,
7.7R...Illumination light, 8,8R...Reference light, 9,9
R...Object light, 10...Subject, 11...Mask, 12...Slit, 13...Reproduction light, 14...
Diffraction light, 15... Reference, 16... Photosensitive original plate, 17
...Reproduction light, 18...Reproduction image, 19...Mask image, 20...Slit image, 21...Photosensitive original plate, 22.
...Object light, 23...Reference light, 24...Support, 2
5... Reflective layer, 81-S3... Each step of the flowchart. Applicant's agent Sato - Yumani, Figure 2, Exposed Figure 3, Figure 4 (G) (b) Figure 5, Figure 6, Figure 7

Claims (1)

[Claims] 1. Three holograms, called first, second, and third, on which a hologram pattern that produces a reconstructed image of the same subject is formed.
A color hologram in which two color separation holograms are arranged at positions such that respective reproduced images are overlapped and formed at the same viewpoint position, wherein each reproduced image by the first, second, and third color separation holograms is formed. each consists of a first primary color, a second primary color, and a third primary color, and these three primary colors are three primary colors that can be additively mixed with each other, and the first, second, and third color separation holograms In each reproduced image according to Features a color hologram. 2. The color separation holograms are adhered to each other with an adhesive, and the refractive index of the material constituting the color separation hologram and the refractive index of the adhesive are different from each other on the hologram pattern forming surface of the color separation hologram. The color hologram according to claim 1, characterized in that thin film layers are formed of materials having different ratios. 3. The color hologram according to claim 2, characterized in that one color separation hologram is further adhered to a support. 4. The color hologram according to claim 2 or 3, wherein a reflective layer is formed on the surface of the color separation hologram or the support. 5. The first, second, and third images can be mixed with each other.
The colors are separated into three primary colors: first, second, and third.
obtaining first, second, and third color-separated primary holograms in which hologram images for each color-separated image are formed; and reproducing the first color-separated primary hologram. Interference fringes between the image and a reference light irradiated from a first direction are exposed on a first photosensitive original plate, and the first color separated image consisting of the first primary color is reproduced at a predetermined viewpoint position. forming a first color-separated secondary hologram image such that interference fringes between the reconstructed image of the second color-separated primary hologram and a reference beam irradiated from a second direction are formed in a second color-separated a second color separation 2 that is exposed on a photosensitive original plate and that reproduces the second color separation image consisting of the second primary color at the viewpoint position;
forming a secondary hologram image; exposing interference fringes between the reproduced image of the third color-separated primary hologram and a reference beam irradiated from a third direction onto a third photosensitive original; a third color separation 2 such that reproduction produces the third color separation image consisting of the third primary color at a position;
forming a secondary hologram image; and obtaining a color hologram by arranging and fixing the first, second, and third secondary holograms at positions such that their reproduced images overlap. A method for manufacturing a color hologram. 6. The method for producing a color hologram according to claim 5, wherein in the step of obtaining the color-separated primary hologram, a color-separated image is obtained as a color-separated photograph. 7. The method for manufacturing a color hologram according to claim 6, wherein in the step of obtaining a color-separated primary hologram, a color-separated image is obtained by irradiating the object with illumination light of each primary color. 8. In the step of obtaining a color-separated secondary hologram, a reproduced image of the color-separated primary hologram is formed on the photosensitive original plate through a slit provided at a predetermined viewing angle range position, and the hologram image formed on the photosensitive original plate is 8. The method of manufacturing a color hologram according to claim 5, wherein the diffracted light is directed only within the viewing angle range. 9. In the step of obtaining a color hologram, the color-separated secondary hologram obtained in the previous step is duplicated in large numbers, and the color-separated secondary hologram is used to obtain a color hologram. The method for producing a color hologram according to any one of items 5 to 8.