JPH06138804A - Production of hologram - Google Patents

Abstract

PURPOSE:To provide the process for production of holograms capable of producing plural uniform hologram elements by one time of photographing process. CONSTITUTION:This process for production of the holograms consist in producing the holograms by interfering object light 30 and reference light 31 in photosensitive agent layers 401 to 403. These photosensitive agent layers 401 to 403 have light transparency. Plural pieces of these photosensitive agent layers 401 to 403 are disposed in the progressing direction of the object light 30 and the reference light 31 and are subjected to photographing of the holograms. The holograms may be of a Lippmann type or Fresnel type.

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 for manufacturing a plurality of hologram elements by photographing once.

[0002]

2. Description of the Related Art Holograms are manufactured by irradiating a photosensitive material with object light and reference light to form interference fringes of the two lights. In order to efficiently manufacture a large number of holograms, as shown in FIG. 9, the photosensitizer film 49 having a large area So is subjected to a photographing process in a lump and then divided into hologram elements 191 to 196 having a small area S. The method of doing is used.

That is, the object light 30 and the reference light 31 are irradiated from both sides of the large-area photosensitizer film 49, and interference fringes 291,296 (other than 291,296 are not shown) are formed on the large-area photosensitizer film 49. The hologram 19 is manufactured. Then, the large area hologram 19 is divided to obtain hologram elements 191 to 196 having a small area S.

[0004]

However, the method of dividing the large area hologram 19 and manufacturing a plurality of hologram elements 191-196 as described above has the following problems. First, since the area is large, the in-plane distribution of the photographing lights 30, 31 becomes non-uniform, and the diffraction efficiency of the hologram becomes non-uniform due to the in-plane position of the large-area hologram 19. Second,
Although the power of the photographing laser beam per unit area is reduced due to the large area, the exposure amount (J) required for photographing the hologram
Is constant, the exposure time becomes long. Therefore, the fluctuation of the optical path length of the photographing laser light becomes large, and it becomes difficult to form clear interference fringes.

Thirdly, as shown in FIG. 9, when the object light 30 is divergent light, the hologram element 19 to be divided is divided.
The directions of the interference fringes 291, 296 are all different for each of 1 to 196. As a result, the hologram element 19
When 1 to 196 are used, for example, in a display device such as a head-up display for automobiles described below, the position of the reproduced display image looks different depending on the hologram elements 191 to 196.

The head-up display 100 is shown in FIG.
0, the displayed image 9 emitted from the display 90 is displayed.
The incident light 33 regarding 3 is diffracted by the holographic device 1
The reflected light 34 is reflected and reflected by the vapor deposition film 911 vapor-deposited on the windshield 91 to visually recognize the displayed image 93 as a virtual image.

Further, there is a problem that a prism and a lens (see FIG. 1 which will be described later) used in the photographing process become large, resulting in an increase in cost. In view of the above-mentioned conventional problems, the present invention aims to provide a hologram manufacturing method capable of manufacturing a plurality of uniform hologram elements by a single photographing step.

[0008]

SUMMARY OF THE INVENTION The present invention is a method for producing a hologram, wherein a hologram is produced by interfering object light and reference light in a photosensitizer layer, wherein the photosensitizer layer has a light-transmitting property. In addition, a method of manufacturing a hologram is characterized in that a plurality of the above-mentioned photosensitizer layers are arranged in the traveling direction of the object light and the reference light so that a plurality of holograms are simultaneously prepared.

What should be noted in the hologram manufacturing method according to the present invention is that a plurality of light-transmitting photosensitizer layers are arranged in the traveling direction of the photographing light, that is, the object light and the reference light, and the hologram is simultaneously photographed. Is to do. As described above, in the conventional method, the photosensitizer layer is
Exposure was performed by arranging on the same plane perpendicular to the photographing light.

On the other hand, in the hologram photographing step of the present invention, a plurality of photosensitizer layers of the material are arranged in the traveling direction of the photographing light. A light-transmissive photosensitizer is used for the photosensitizer layer as a material. The photosensitizer layer to be the above-mentioned material may be a photosensitizer itself formed into a film (see FIGS. 6 and 7), or a photosensitizer fixed on a supporting member having a high light-transmitting property (see FIG. 1, FIG. (See FIG. 8).

[0011]

In the method for producing a hologram according to the present invention, a hologram is photographed by arranging a plurality of n photosensitizer layers to be materials in the traveling direction of the photographing light. Therefore, the area S for irradiating the photographing light is 1 / n as compared with the area So of the conventional photosensitizer film in which the n photosensitizer layers are flatly developed on the same plane. Therefore, the power of the photographing light in the exposed surface of the photosensitizer layer is made uniform as compared with the conventional method. Therefore, the diffraction efficiency of each completed hologram element is also uniform in the plane (solution of the first problem).

Further, the directions of the interference fringes formed on the respective photosensitizer layers are different as in the conventional method (see FIG.
96), but all in the same direction (solution of the third problem). However, the interference fringes formed on each hologram element are displaced in the vertical direction (shooting light direction) due to the inter-surface gap of each photosensitive agent layer.

However, the thickness of each photosensitizer layer is extremely thin. Therefore, since the gap between the photosensitizer layers can be reduced, the influence thereof is extremely small as compared with the conventional problem caused by the deviation of the direction of the interference fringes. Further, as shown in Example 1 described later, the influence of the vertical shift of the interference fringes on the display image on the head-up display can be almost ignored.

The exposure time can be suppressed within an appropriate time by changing the number of the photosensitizer layers to be arranged according to the strength of light transmission of the photosensitizer layer. Therefore, it is possible to avoid obscuring the interference fringes due to the lengthening of the exposure time (solving the second problem). As described above, according to the hologram manufacturing method of the present invention, it is possible to manufacture a plurality of uniform hologram elements by one imaging step.

[0015]

【Example】

Example 1 A method for manufacturing a hologram according to an example of the present invention will be described with reference to FIGS. The hologram element in this example is a hologram element used in a head-up display of an automobile.

In this example, as shown in FIG.
1 to 403, it is a hologram manufacturing method in which the object light 30 and the reference light 31 are caused to interfere with each other to manufacture a hologram. The photosensitizer layers 401 to 403 have translucency. Then, a plurality of the photosensitizer layers 401 to 403 are arranged in the traveling direction of the object light 30 and the reference light 31, and the hologram is photographed at the same time.

The steps will be described in detail below. As shown in FIG. 1, the photosensitizer layers 401 to 403 of this example are formed on the bottom surfaces of the light-transmitting substrates 421 to 423, and the two are integrated to form photosensitizer substrates 461 to 463. . The photosensitizer substrates 461 to 463 are made of heavy chromium distribution gelatin (D.C.G) as a photosensitizer, and are 112 mm × 46 mm ×
Soda glass with a size of 1.8 mm (refractive index n = 1.5
2) The substrates 421 to 423 manufactured in 2) are formed on the bottom surface so as to have a film thickness of 25 μm, and after gelling or drying, they are stably manufactured at 20 ° C. in an atmosphere of about 50% RH.

Next, as shown in FIG.
1 to 463 is set to a predetermined focal length (in this example, 1000 m
m) is sandwiched between the spherical lens 51 and the prism 52. At this time, the boundary surface of each of the photosensitizer substrates 461 to 463 has a refractive index adjusting liquid 441 to 44 made of silicon oil.
Seal with 4.

A refractive index adjusting liquid in which a lens, a prism, a substrate, and a photosensitizer are matched in refractive index is a kind of optical glass B.
If the lens made of K7, the substrate made of base glass, and the photosensitizer are made of dichromated gelatin, it is desirable that the refractive index can be adjusted between 1.48 and 15.6,
In addition to silicone oil, xylene, benzyl acrylate, etc. may be used. Lens 15, prism 52, substrate 4
21-423, photosensitizer layers 401-403, and adjusting liquid 4
61 to 463 need to have almost the same refractive index,
If even one has a significantly different refractive index, internal reflection occurs at the interface and a noise hologram occurs.

Next, from the prism 52 side, the wavelength 514.
Argon laser light of 5 nm is made incident as the reference light 31. After the incidence, the reference light 31 travels straight through each medium having a substantially uniform refractive index toward the lens 51, and reaches the reflection film 511 formed on the bottom surface (atmosphere side) of the lens 51. Then, the reflected light 301 as the object light 30 reflected by the reflective film 511 and the incident light 311 as the reference light 31 form interference fringes in the photosensitizer layers 401 to 403.

As a result, a hologram element in which a concave lens as a magnifying glass is recorded is formed in each of the photosensitizer layers 401 to 403. The reproduction light of the hologram element (incidence angle 33.5) is changed by changing the incident angle of the argon laser light.
2) is 540 nm, 600 as shown in FIG.
The exposure is performed so that the two colors are nm.

That is, the hologram element 11 manufactured as described above is incorporated into the holographic device 1 as shown in FIG. 3, and the incident light 33 enters the holographic device 1.
When the laser beam is incident, the reproduction light 34 has wavelength characteristics as shown in FIG. FIG. 2 is a diffraction wavelength characteristic diagram showing that the hologram element exhibits high efficiency in two colors of wavelengths of 540 nm and 600 nm. The energy of the incident light used for the exposure is 500 mJ in total.

The hologram element 1 is formed on the substrates 421 to 423.
The hologram substrate on which No. 1 was formed is washed with water until it loses its color after exposure, and immersed in a commercially available photographic hardener fixing solution (Rapid Fixer manufactured by Kodak Co., Ltd.) for 10 minutes. Then, after washing with water, it is immersed in a 90% isopalopanol solution for 10 minutes and dried with hot air. After that, heat aging is performed at 150 ° C for 4 hours to prevent wavelength change in the actual vehicle environment.

Thereafter, as shown in FIG. 3, the hologram substrate 14 is sandwiched between the cover plates 123 and 124 from above and below, and optically sealed with the sealing materials 131 and 132 to complete the holographic device 1. Sealing material 131, 132
A commercially available epoxy thermosetting resin (manufactured by Cemedine Co., Ltd., trade name CS-2340-5) is used for this, and its refractive index is 1.55. The thickness of the sealing materials 131 and 132 is 50 μm.

When the hologram substrate 14 is sealed,
The circumference of the hologram element 11 is removed by a slight width S as shown in FIG. The holographic device 1 of this example
The cover plates 123 and 124 are made of glass and have a length of 112 m.
The size is m × 46 mm × 1.0 mm, and the seal width S is 5 mm. Also, the lower cover plate 12
The bottom surface of No. 4 is coated with an anti-scattering film 15 having a thickness of 10 μm, which is made by adding 5% of a black pigment (Glasslite 500 made by Cashew) to an epoxy resin and mixing them.

Next, the function and effect of the hologram manufacturing method according to this embodiment will be described. In this example, the photosensitive material substrate 461
A plurality (three) of to 463 are arranged in the traveling direction of the photographing light (object light 30 and reference light 31) to photograph the hologram. Therefore, the plurality of photosensitive material substrates 461 to 46
The area S irradiated with the photographing light is 1/3 as compared with the conventional method in which 3 is flatly developed on the same plane. Therefore, the power of the photographing light in the exposed surface of the photosensitizer layers 401 to 403 is relatively more uniform than that in the conventional method. Therefore, the diffraction efficiency of the manufactured hologram element becomes more uniform.

The directions of the interference fringes of the manufactured hologram elements are almost the same. Although the interference fringes are slightly displaced in the vertical direction, the total thickness of the photosensitive material substrates 461 to 463 is about 1.8 mm. On the other hand, since the focal length of the lens 51 is 1000 mm, when the present hologram element is used in the head-up display, the displacement of the displayed image is a little less than 0.2% in depth and is slight.
When a film-shaped photosensitive material dry plate is used as the photosensitive material, its thickness is 50 μm or less, and the total thickness is extremely small even if a plurality of such photosensitive material plates are arranged. Is negligible.

In this example, the photosensitive material substrates 461 to 46 are used.
Although an example in which 3 sheets of 3 are stacked and exposed is shown, the number can be increased or decreased depending on the strength of the translucency of the photosensitive material substrate. For example, when the number of laminated photosensitizer layers is changed to 5, the transmittance of photographing light is as shown in FIG. At that time, the diffraction efficiency of the hologram element manufactured by the method shown in this example is shown in FIG.

As is known from FIG. 5, even if the number of laminated layers is increased to 5, a hologram element having a good diffraction efficiency of 70% or more can be manufactured. The number of samples N in FIG. 4 is 2, and the number of samples in FIG. 5 is 4. In FIG. 5, the vertical line indicates the change width within the sample, and the circles indicate the average value.

As described above, according to the hologram manufacturing method of this embodiment, it is possible to manufacture a plurality of uniform hologram elements by one photographing step. The photosensitizer used in this example is D.I. C. G. However, as long as it is a photosensitizer that transmits light for photographing, it can be applied to photopolymers, silver salts, reliefs, and the like. The substrate supporting the photosensitizer layer is not limited to soda glass as long as it has a property of transmitting the photographing light.

Example 2 In this example, as shown in FIG. 6, the photosensitive agent layer 4 in Example 1 was used.
01 to 403, a film-shaped photosensitive agent dry plate 404 to
406 is used, and the substrates 421 to 423 as a support of the photosensitive agent in Example 1 are not used. The light-transmitting holders 451 and 452 sandwich the three photosensitizer dry plates 404 to 406 from the left and right, and the boundary surfaces of the photosensitizer dry plates 404 to 406 are used as refractive index adjusting liquids 441 to 4
Seal with silicone oil 44.

The outside air surface 45 of the left holder 451 is
The object light 30 is emitted from 11 and the reference light 31 is made incident from the outside air surface 4521 of the holder 452 on the right side to form holograms on the photosensitive agent dry plates 404 to 406. Others are similar to those of the first embodiment, and similar effects can be obtained.

Further, in the hologram manufacturing method shown in FIG. 6, the holders 451 and 452 may be prisms as shown in FIG. Explaining the object light 30, the unnecessary interference fringes are produced by transmitting through the photosensitizer layer, internally reflecting at the outside air surface 4521 of the holder 452, and returning to the photosensitizer layer again. Since it can be changed so as not to return to the photosensitizer layer, it is possible to remove the reflected light from the outside air surfaces 4511 and 4521 of the holders 451 and 452.

Example 3 This example is an example in which the present invention is applied to the manufacture of a Fresnel type hologram element. As shown in FIG. 7, a Fresnel hologram element is manufactured by using an object light 30 and a reference light 31.
And irradiating the photosensitizer layers 404 to 406 from the same direction.

That is, the photosensitizer layers 404 to 406 are sandwiched between the holders 451 and 452, and the respective boundary surfaces are sealed with the refractive index adjusting liquids 441 to 444 made of silicon oil. Then, the object light 30 and the reference light 31 are irradiated from the same direction to form interference fringes on the photosensitizer layers 404 to 406 to manufacture a Fresnel hologram element. Others are similar to those of the first and second embodiments, and similar effects can be obtained.

Example 4 This example is a specific example of Example 3 in which a Fresnel hologram element is manufactured by a contact exposure method. In this example, as shown in FIG.
This is a method of manufacturing a hologram for a laser scanner by a so-called contact exposure method, in which a hologram is photographed while being in close contact with the substrate.

Substrate 424 of Photosensitizer Substrate 464-466
Photosensitizer layers 407 to 409 are formed at 426.
The photosensitive material substrates 464 to 466 are integrated with each other through the refractive index adjusting liquids 441 and 442 made of silicon oil. On the other hand, the master hologram 18 is arranged close to the photosensitive material substrates 464 to 466. The master hologram 18 is sandwiched by holders 453 and 454. Holder 453 on the left side and photosensitive agent layer 4 on the right side
The gap G with 09 is set to 2 mm.

Then, the laser light 3 is made incident from the right side of the master hologram 18 (the direction opposite to the photosensitive material substrates 464 to 466). Then, master hologram 1
The so-called zero-order light 312 that simply passed without being diffracted at 8
And the so-called first-order light 302 diffracted by the master hologram 18 enters the photosensitive material substrates 464 to 466.

Then, in the photosensitizer layers 407 to 409, the zero-order light 312 as the reference light and the primary light 30 as the object light are used.
2 interfere with each other to form a hologram. Others are similar to those of the first and second embodiments, and similar effects can be obtained.

In the above embodiment, the shape of the lens 51 for recording on the photosensitive material is spherical, but the type of lens to be recorded is not limited to a spherical mirror, but a parabolic mirror, an elliptic mirror,
Any of a toroidal mirror, an off-axis parabolic mirror, and an off-axis elliptical mirror may be used.

[Brief description of drawings]

FIG. 1 is an explanatory view of a hologram manufacturing method according to a first embodiment.

FIG. 2 is a wavelength characteristic diagram of diffraction of the hologram element of Example 1.

FIG. 3 is an explanatory diagram of the holographic device according to the first embodiment.

FIG. 4 is a diagram showing the relationship between the number of laminated photosensitizer layers and the transmittance of photographing light in Example 1.

FIG. 5 is a relationship diagram between the number of laminated photosensitizer layers and the diffraction efficiency of a hologram element in Example 1.

FIG. 6 is an explanatory diagram of a hologram manufacturing method according to a second embodiment.

FIG. 7 is an explanatory diagram of a hologram manufacturing method according to a third embodiment.

FIG. 8 is an explanatory diagram of a hologram manufacturing method according to a fourth embodiment.

FIG. 9 is an explanatory diagram of a hologram manufacturing method according to a conventional technique.

FIG. 10 is an explanatory diagram of a head-up display.

[Explanation of symbols]

 1. ． ． Holographic device 11 ... Hologram element, 141-143 ... Hologram substrate, 18. ． ． Master hologram, 30. ． ． Object light, 31. ． ． Reference light, 33. ． ． Incident light, 34. ． ． Reproduction light, 401-409. ． ． Photosensitizer layer, 421-426. ． ． Substrate, 441-444. ． ． Refractive index adjusting liquid, 451-454. ． ． Holder, 461-466. ． ． Photosensitizer substrate, 51. ． ． Lens, 52. ． ． prism,

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tetsuya Kato 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd. (72) Inventor Hiroyuki Tatebayashi 1-1-chome, Showa-cho, Kariya city, Aichi Nippondenso Within the corporation

Claims (1)

[Claims] 1. A method for producing a hologram, wherein a hologram is produced by causing object light and reference light to interfere with each other in a photosensitizer layer, wherein the photosensitizer layer has a light-transmitting property. A method of manufacturing a hologram, wherein a plurality of photosensitizer layers are arranged in a traveling direction of an object light and a reference light to form a plurality of holograms at the same time.