JP3426921B2 - Hologram fabrication method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram manufacturing method capable of manufacturing a large hologram.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Unexamined Patent Publication No. 5-103351, there is a device that uses a concave mirror as a screen for image projection and projects an image there. The principle is that, as shown in FIG. 7, an LCD 102 tilted above the inside of the frame 101 is driven by an LCD circuit 104, and an image displayed by the LCD 102 is projected and displayed on a concave mirror 103. The three-dimensional image 105 is observed with the observation eye 106 through the opening 101a. However, this device has a problem that unnecessary external light is reflected by the concave mirror 103 and appears as noise.

Further, when such a device is applied to a head-up display of a passenger car or the like, it is impossible to use the concave mirror itself as a screen because the outside must be seen through the screen.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 62-221928, by forming a concave mirror into a hologram, only the necessary image light is reflected due to the wavelength dependence and the angle dependence of the hologram, and it is unnecessary. Attempts have been made not to reflect such light. This will be described with reference to FIG. 8. The image displayed on the CRT 107 is projected through a hologram diffraction plate 108 onto a hologram lens 109 (arranged on the front windshield 110) which is a hologram of a concave mirror.

This screen is a hologram lens 1
The manufacturing method of 09 is shown in FIG. This hologram lens 1
09, the light from the laser light source 111 is set to 2 as shown in FIG.
The light beam is separated into a light beam, one of which is converted into a parallel light beam 113 by a lens 112, and the light beam from the laser light source 111 is separated into two light beams to generate a divergent spherical wave 114. Photosensitive material 1
It is made by incident on 15. This hologram lens is equivalent to a hologram obtained by using a concave mirror. According to this technique, although the concave mirror itself is expensive by forming the concave mirror into a hologram in this manner, the hologram can be mass-produced, so that there is an advantage that the production cost of the screen can be reduced.

As another three-dimensional display device, VGKomar of Russia has attempted to magnify and project a three-dimensional image using a hologram of a large-diameter concave mirror as a screen (SPIE Vol.120, Three-Dimensional Imaging).
(1977)).

However, in this three-dimensional display device,
In the production of holograms, there is a problem in that the larger the screen, the higher the output laser required. Also, if a silver salt material or dichromated gelatin, which is said to have relatively high exposure sensitivity, is used, a large screen can be produced even by using a conventional laser light source, but the development / fixing process is not wet. There is also a problem that productivity is not good because it is a process.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and includes development / development
An object of the present invention is to provide a hologram production method capable of producing a large hologram which can be used as a large screen because a fixing process is a dry process and a highly productive photopolymer can be used.

[0009]

In order to solve the above-mentioned problems, in the invention described in claim 1, a copy master producing step of producing a copy master by hologram-recording an object on a first recording material, Holographic duplication in which a second recording material having a lower exposure sensitivity than the first recording material is superposed on the copy master produced by the copy master producing process, and the recording area is divided into a plurality of portions to perform hologram duplication by contact copying. And a method of manufacturing a hologram including steps.

That is, according to the first aspect of the present invention, for example, in the step of producing a copy master, a hologram material having a high exposure sensitivity such as a silver salt material and a large-diameter concave mirror are made to face each other at an appropriate angle, and the photosensitive material side. The entire surface is irradiated with a laser beam, and a concave mirror Lippmann hologram is produced by the method of Deniseuk. After that, development / fixing processing is performed to obtain a reproducible copy master. In the hologram duplication process, the hologram produced in the copy master production process (copy master) and the photopolymer are brought into close contact with each other and the laser beam with a reduced divergence angle is partially irradiated from the photopolymer side instead of batch exposure, and the irradiation areas are successively irradiated. Is moved to expose the entire surface. A large holographic screen can be manufactured through the above steps.

Therefore, according to the first aspect of the present invention, the copy master is produced by hologram recording on the high-sensitivity recording material, and the region of the low-sensitivity recording material is divided by using the copy master to perform contact copy. Since a hologram is produced by performing hologram duplication, it becomes possible to produce a large hologram that can be used for a large screen or the like, by using a low-sensitivity hologram recording material.

Further, in the invention described in claim 2, in the method for producing a hologram described in claim 1, the first recording material is a silver salt material.

According to the second aspect of the present invention, since a highly sensitive silver salt material is used for producing the copy master, a good copy master can be produced.

Further, in the invention described in claim 3, in the hologram manufacturing method described in claim 1 or 2, the second recording material is a photopolymer.

Since the photopolymer has a poorer exposure sensitivity by 1 to 2 digits than the silver salt material, when attempting to expose a large area at once, the light intensity per unit area becomes small and a hologram cannot be taken. Therefore, according to the third aspect of the invention, the photopolymer is adopted as the second recording material used in the hologram duplication step, and the hologram is duplicated by contact copying from the copy master to produce a hologram. A large hologram can be produced even if a photopolymer having excellent but low sensitivity is used.

Further, in the invention described in claim 4, in the hologram manufacturing method described in claim 1, 2 or 3, the subject is a concave mirror.

That is, in the invention described in claim 4, first, a copy master is prepared from a large concave mirror hologram using a photosensitive material having a high exposure sensitivity, and using this, for example,
A large concave mirror hologram is duplicated by overlaying a photopolymer with good productivity but poor exposure sensitivity with a copy master, dividing the recording area, irradiating laser light one after another to make contact copies, and expose the entire surface. . A large holographic screen can be manufactured by the above two steps.

Therefore, according to the fourth aspect of the invention, since the subject is a concave mirror, a large holographic screen can be produced even if a photopolymer having excellent productivity but low sensitivity is used.

Further, in the invention described in claim 5, in the hologram manufacturing method described in claim 1, 2, 3 or 4, a mask having a square window is used in the hologram duplication step. .

According to the fifth aspect of the present invention, since a mask having a square window is used in the hologram duplication process, the recording area is divided by using a circular beam of irradiation light for hologram duplication. Even if it is exposed by light, the entire surface of the second recording material can be uniformly irradiated with light.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. As an embodiment, a method for producing a large holographic screen according to the present invention will be described.

FIG. 1 is a principle diagram for explaining the production of the copy master of the embodiment. First, as shown in Figure 1,
The laser light 1 is made into a divergent spherical wave 3 by the lens 2 and arranged so as to irradiate the large-diameter concave mirror 6 as a whole. in this case,
Since the light intensity per unit area is small, the hologram photosensitive material (recording material) 4 is made of a highly sensitive material having good exposure sensitivity such as silver salt material (exposure sensitivity 0.0003 to 1 mJ / cm ² ). . At this time, the hologram photosensitive material 4
Arranges the emulsion surface 5 toward the lens 2 side. The reason for this is the thickness of the substrate of the hologram photosensitive material 4.

In this way, the divergent spherical wave 3 coming from the lens 2 and the parallel light 7 which is the reflected light from the large-diameter concave mirror 6 are made incident on the hologram photosensitive material 4, which results. The interference pattern is recorded on the hologram photosensitive material 4. Then, after exposure, appropriate development / fixing processing is performed, and a hologram of a large-diameter concave mirror serving as a copy master is completed.

Next, the hologram duplication using the copy master of the hologram of the large-diameter concave mirror produced as described above will be described with reference to the principle diagram of FIG.

When the hologram 10 of the large-aperture concave mirror of the copy master manufactured as described above is irradiated with the parallel light 8 which is the reproduction light of the parallel light as shown in FIG. The focused spherical wave 11 focused on the point 12 is reproduced. Here, as shown in FIG. 2, a new hologram photosensitive material (recording material) 9 is brought into close contact with the hologram 10 of the large-diameter concave mirror of the copy master, and when the parallel light 8 is irradiated, the large-diameter concave mirror hologram 10 of the copy master is irradiated. An interference pattern formed by the focused spherical wave 11 which is the reproduction light by the and the parallel light 8 is recorded on the hologram photosensitive material 9.

In this case, the material surface of the hologram photosensitive material material 9 is the hologram 1 of the large-diameter concave mirror of the copy master.
It is indispensable to face the material surface (emulsion surface) of 0.
This is because the hologram having the same size as the cross-sectional area of the parallel light 8 illuminating the hologram photosensitive material 9 is used as the hologram photosensitive material 9.

If such exposure is carried out without making the material surfaces (emulsion surfaces) of each other face each other, the parallel light 8 is converted into the hologram photosensitive material 9 due to the thickness of the glass substrate or the like.
And the focused sphere wavefront 11 which is the light diffracted and reflected by the large-diameter concave mirror hologram 10 of the copy master.
However, there is a positional deviation from the portion where the hologram photosensitive material 9 is irradiated. Then, a hologram having the same size as the cross-sectional area of the parallel light 8 illuminating the hologram photosensitive material 9 cannot be formed.

As described above, the hologram 1 of the large-diameter concave mirror of the copy master is formed by the contact copy method.
Zero duplicate holograms can be made.

However, a low-sensitivity hologram recording material (exposure sensitivity 5 to 5) having poor exposure sensitivity such as photopolymer is used.
0 mJ / cm ²⁾ at, even using a laser of high output, in this way to try entire batch exposure, the production of the hologram intensity is too small per unit area is very difficult.

Therefore, as shown in the principle diagram of FIG. 3, the exposure optical system is basically the same as that shown in FIG. 2, but the recording area is divided into a plurality of portions to perform hologram duplication by contact copying. That is, when the hologram 15 of the large-diameter concave mirror of the copy master manufactured as described above is irradiated with the parallel light 13 that divides the recording area, the condensing point which is the reproduction light by the large-diameter concave mirror hologram 15 of the copy master. The focused spherical wave 11 focused on 12 is reproduced.
Therefore, at this time, if a new hologram photosensitive material (recording material) 14 is brought into close contact with the hologram 15 of the large-diameter concave mirror of the copy master, the focused spherical wave 16 and the parallel light 1
The interference pattern due to 3 and 3 is recorded on the hologram photosensitive material 14.

By doing so, it is possible to use a low-sensitivity hologram recording material having a poor exposure sensitivity such as a photopolymer. For example, when a photopolymer is used as the recording material to be a duplicate hologram, as shown in FIG. 3, the beam diameter cross-sectional area is set so that the light intensity satisfies the photopolymer exposure condition, and the beam diameter of the laser beam is set. Should be expanded to form parallel light 13.

Then, as shown in FIG. 3, the entire surface is not collectively exposed and the recording area is divided, and the parallel light 13 is shifted so as to be parallel to the optical axis of the parallel light 13, and the exposure is successively performed. Then, by finally exposing the entire surface of the hologram photosensitive material 14, a duplicate hologram of the hologram of the large-diameter concave mirror can be produced even if the hologram photosensitive material 14 having low exposure sensitivity and low sensitivity is used.

Therefore, according to the present invention, even if a recording material, such as a photopolymer, which is excellent in mass productivity but has a low exposure sensitivity and a low sensitivity is used, it is very difficult to collectively expose the entire surface of a large-diameter concave mirror. It is possible to mass-produce holograms that are duplicates of holograms.

Further, the maximum diffraction efficiency of the hologram using the silver salt material is about 70%, but the copy master produced using the hologram produces a duplicate hologram produced using a photopolymer as in the present embodiment. Since the maximum diffraction efficiency is higher than that, and a maximum diffraction efficiency close to 100% can be expected, a very high diffraction efficiency can be produced by producing a screen for image projection.

When the parallel light 13 as shown in FIG. 3 is produced by using an ordinary lens, the beam cross section has a circular shape. Therefore, unlike the case of FIG. 3, the parallel light 13 of the hologram photosensitive material 14 is used as shown in FIG. 5 by using a mask 18 having an open rectangular window (opening) as shown in the sectional view of FIG. The mask 18 is arranged on the irradiation side. Then, the hologram photosensitive material 14 is sequentially exposed while the mask 18 is displaced to expose the entire surface thereof, so that the divided areas can be accurately exposed, and a uniform hologram without exposure unevenness can be manufactured.

In the copy master manufacturing process described with reference to FIG. 1, in the above-described method, the light reflected by the large-diameter concave mirror 6 becomes parallel light 7 when the hologram of the large-diameter concave mirror is collectively exposed. However, they may not be parallel, and may be divergent light, for example. Here, when the divergent light is used, in the hologram duplication step described with reference to FIG. 3 or FIG. 5, the exposure is performed while shifting the optical axis unlike the one using the parallel light 13 described above. The entire surface of the hologram photosensitive material can be exposed by changing (shifting) the spreading direction of the spherical wave from the diverging point of the diverging light.

Further, in the hologram duplication step described with reference to FIG. 3 or FIG. 5, the exposure is performed using the parallel light which is the reflected light of the large diameter concave mirror at the time of producing the large diameter concave mirror in the copy master making step. A diverging spherical wave similar to the incident light on the large-diameter concave mirror in the copy master manufacturing process may be used. No matter which light beam is used, the large-diameter concave mirror hologram produced by the copy master production process is superposed on the unexposed hologram photosensitive material, and the hologram reproduced by irradiating laser light is also physically equivalent. is there.

By the steps described above, a hologram (holographic screen) having a large-diameter concave mirror can be produced even if a hologram recording material having poor sensitivity such as a photopolymer is used. As shown in the principle diagram of FIG. 6, the holographic screen 21 has a function of reflecting and diffracting the parallel light 22 when the incident light of the diverging light 20 from the diverging point 19 is irradiated.

In the above embodiment, the object is a large-diameter concave mirror, but the object is not limited to this, and any object can be used as long as it is possible to take a hologram. That is, according to the present invention, it is possible to duplicate a hologram of any subject.

[0040]

As described above, according to the first aspect of the invention, the copy master is hologram-recorded on a high-sensitivity recording material to be manufactured, and the copy master is used to form an area of the low-sensitivity recording material. Since holograms are produced by dividing and performing hologram duplication by contact copy, it becomes possible to produce large holograms that can be used for large screens and the like, by using a hologram recording material with low sensitivity.

Further, according to the invention of claim 2,
Since a highly sensitive silver salt material is used for producing the copy master, a good copy master can be produced.

Further, according to the invention described in claim 3,
A photopolymer is adopted as the second recording material used in the hologram duplication process, and a hologram is produced by duplicating the hologram from the copy master by contact copying. Can be manufactured.

Further, according to the invention of claim 4,
Since the subject is a concave mirror, it is possible to fabricate a large holographic screen even if a photopolymer having excellent productivity but low sensitivity is used. Therefore, when the large-diameter concave mirror hologram produced according to the present invention is used as an image projection screen, a large screen display is possible, and since the diffraction efficiency is high, a brighter and more powerful image display than the conventional one is possible.

Further, according to the invention of claim 5,
Since a mask with a square window is used in the hologram duplication process, even if the recording area is divided and exposed by using a hologram duplication light having a circular beam shape,
The entire surface of the recording material can be uniformly irradiated with light. Therefore, since the divided areas can be accurately exposed at the time of exposure, it is possible to mass-produce a uniform large hologram without exposure unevenness.

[Brief description of drawings]

FIG. 1 is a principle diagram of an optical system for explaining the production of a copy master (large-diameter concave mirror hologram) in the method for producing a large holographic screen according to the embodiment of the present invention.

FIG. 2 is a principle diagram of an optical system for explaining hologram duplication by contact copying using a copy master of a large-diameter concave mirror hologram produced by the optical system of FIG.

FIG. 3 is a principle diagram of an optical system for explaining hologram duplication by contact copying in which a recording area is divided into a plurality of areas using a copy master of a large-diameter concave mirror hologram produced by the optical system of FIG.

FIG. 4 is a diagram showing a shape of an opening of a mask used in a hologram duplication step.

5 is a principle of an optical system for explaining hologram duplication by contact copy using a mask of FIG. 4 which divides a recording area into a plurality of areas by using a copy master of a large-diameter concave mirror hologram produced by the optical system of FIG. It is a figure.

FIG. 6 is a principle diagram of an optical system for explaining the function of a large holographic screen (large-diameter concave mirror hologram) manufactured according to the embodiment.

FIG. 7 is a principle diagram of an image display device using a conventional concave mirror.

FIG. 8 is a principle diagram of an image display device using a conventional concave mirror hologram.

9 is a principle diagram showing a manufacturing optical system of a concave mirror hologram used in the display device of FIG.

[Explanation of symbols]

3,26 Divergent spherical wave 4,9,14 Holographic photosensitive material 6 Large-diameter concave mirror 7,8,13,19,22 Parallel light (plane wave) 10,15 Copy master (large-diameter concave mirror hologram) 11,16 Focused spherical wave 18 Mask 21 Large holographic screen (large-diameter concave mirror hologram)

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Claims (5)

(57) [Claims] 1. A copy master producing step of producing a copy master by performing hologram recording of an object on a first recording material, and a copy master produced by the copy master producing step is exposed to light more than the first recording material. And a hologram duplication step of superimposing a second recording material having low sensitivity, dividing a recording region into a plurality of portions, and performing hologram duplication by contact copying. 2. The method for producing a hologram according to claim 1, wherein the first recording material is a silver salt material. 3. The method for producing a hologram according to claim 1, wherein the second recording material is a photopolymer. 4. The method for producing a hologram according to claim 1, wherein the subject is a concave mirror. 5. The mask according to claim 1, wherein a mask having a square window is used in the hologram duplication process.
3. The method for producing a hologram according to 3 or 4.