JPH06195016A - Holography device - Google Patents

Abstract

PURPOSE:To provide the good-quality holography device which facilitates matching of refractive indices and does not deteriorate the properties of the photosensitive material of a hologram element. CONSTITUTION:This holography device has a hologram substrate 20 formed with the hologram element 11 on a substrate 14 and cover plates 123, 124 disposed with the hologram substrate 20. The respective boundary faces of the hologram substrate 20 and both cover plates 123, 124 are sealed by liquid materials 211, 212. The liquid materials are formed by mixing >=2 kinds of raw materials varying in either or both of the refractive indices and viscosity rates. The raw materials include silicone oil, butyl phthalate, xylene, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic device used for automobile head-up displays, various sensors, stereo holograms and the like.

[0002]

2. Description of the Related Art In recent years, a head-up display for displaying speed and the like in front of a windshield of an automobile has attracted attention. As a device for this head-up display, there has been proposed a holographic device that utilizes the wavelength-selective diffraction / reflection characteristics of a hologram element.
The head-up display 1 is, as shown in FIG.
Incident light 30 emitted from the display 90 and related to the displayed image
Is reflected and diffracted by the holographic device 10, and the reproduction light 31 is evaporated on the windshield 91.
Reflect at 1. The driver 92 uses the reflected reproduction light 311
And a displayed image 93 as a virtual image displayed in front of the windshield 91 can be visually recognized.

The structure of the head-up display 1 will be described. As shown in FIG. 9, a display 90 has a liquid crystal panel 902, a reflecting mirror 903, and a holographic device arranged in front of the incandescent lamp 901 and the incandescent lamp 901. 10 is attached. The liquid crystal panel 902 has a displayed image 93 such as speed, master warning, direction support, and map.
(Fig. 8) is displayed. Further, the display 90 is generally installed near the instrument panel 904.

The above holographic device 10 is shown in FIG.
As shown in FIG. 5, incident light 30 relating to the displayed image is made incident from the upper cover plate 123 and diffracted / reflected by the hologram element 11 formed on the lower surface of the substrate 14. Then, the reproduction light 31 that is the reflected light is again used for the upper cover plate 1
It is emitted from 23. In addition, in the hologram element 11,
Interference fringes having predetermined diffraction / reflection characteristics are formed in advance.

In the holographic device 10 for a head-up display, for example, a hologram element 11 having wavelength selectivity as shown in FIG. 3 to be described later and having a reflection characteristic of a concave mirror is often used. In addition to the regular reproduction light 31, there are surface reflection light 321 reflected from the surface and transmission scattered light 322 due to light transmitted through the hologram element 11.

The above-mentioned surface reflected light 321 and transmitted scattered light 3
Reference numeral 22 denotes a regular displayed image 93 (FIG. 8) by the reproduction light 31.
To form a noise image that disturbs. As shown in FIG. 10, an antireflection film 151 is provided on the surface of the holographic device 10, and the surface reflected light 32 reflected from the surface is reflected.
There is a method of attenuating 1. Further, a method has also been proposed in which a scattering prevention film 152 is provided on the bottom surface of the lower cover plate 124 to suppress the transmitted scattered light 322.

In FIG. 10, reference numeral 131 is a sealing material that optically seals the upper cover plate 123 and the substrate 14, and reference numeral 132 is a sealing material that optically seals the lower cover plate 124 and the hologram element 11. is there.
The upper and lower cover plates 123, 124, the substrate 14, the hologram element 11, and the encapsulants 131, 132, which form each layer of the holographic device 10, are formed of substantially the same refractive index in order to suppress noise light due to reflection. ing.

As the hologram element 11, there are a Lippmann type reflection type hologram element and a Fresnel type transmission type hologram element. Finally, these holograms are enclosed between the upper cover plate 123 with the antireflection film 151 and the lower cover plate 124 with the anti-scattering film 152, as shown in FIG. In this case, the hologram element has a refractive index of about 1.5, and the upper and lower cover plates 151 and 152 and the substrate 14 have a refractive index of about 1.5.
Is.

The cover plates 123 and 124 and the substrate 1
Glass is often used for 4, and the sealing material 131,
For 132, an adhesive such as an epoxy resin, an acrylic resin, or an ultraviolet curable resin is used. The reason why the above-mentioned resin (adhesive) is often used as the sealing materials 131 and 132 is that the sealing material 13 is formed by performing heat treatment or ultraviolet treatment during sealing.
This is because 1,132 itself has the advantage of fixing and adhering the hologram element and the glass to each other, and refraction similar to that of the hologram element 11, the substrate 12, and the upper and lower cover plates 151 and 152. It is because it has a rate.

[0010]

However, the resin sealing material 13 used in the conventional holographic device 10 is used.
1, 132 has the following drawbacks and causes problems. (A) High viscosity (for example, about 500c with epoxy resin type)
P), it is easy to enclose air bubbles during encapsulation. Therefore, the refractive index is disturbed to generate noise light.

(B) The refractive index n is almost constant for each material and cannot be arbitrarily selected. For example, in the case of epoxy resin, the refractive index n is 1.55, which is almost fixed, and it is difficult to perfectly match the substrate and the cover plate. Therefore, noise due to reflection is likely to occur.

(C) When the resin is cured, heat treatment or ultraviolet treatment is required, and reaction heat may be generated. For example, an epoxy resin requires a heat treatment at about 100 ° C., and an acrylic resin requires a UV treatment. Further, in the case of epoxy resin, the temperature rises to about 150 ° C. due to the heat of reaction.

As a result, the sealing material and the photosensitive material of the hologram element may react with each other to form another reaction layer having a different refractive index. For example, when the photosensitizer is a photopolymer such as polyvinylpyrrolidone or poly (N-vinylcarbazole) as a matrix polymer, another layer having a different refractive index is formed as a reaction layer, which causes cloudiness and noise light. Problems such as occurrence occur. To avoid this, it is necessary to take measures such as providing a barrier layer on the surface of the photosensitizer.

(D) When the resin cures, peeling may occur at the interface with the cover plate or the hologram element. As a result, the refractive index becomes discontinuous, and noise and image distortion occur. In view of the above-mentioned conventional problems, the present invention is to provide an excellent holographic device in which the matching of the refractive index is easy and the photosensitive material of the hologram element is not deteriorated.

[0015]

The present invention is a holographic device having a hologram substrate having a hologram element formed on a transparent substrate, and a transparent cover plate having the hologram substrate disposed thereon. The plate, the substrate, and the hologram element have almost the same refractive index, and
Each boundary surface between the hologram substrate and the cover plate is sealed with a liquid substance, and the liquid substance is formed by mixing two or more kinds of raw materials having different refractive index and / or viscosity. The holographic device is characterized in that

In the present invention, the most remarkable thing is that
That is, the boundary surfaces of the hologram substrate and the cover plate that form the holographic device are sealed with a liquid substance. The liquid substance is formed of two or more kinds of raw materials having different refractive indexes and viscosity. The raw material may be two or more kinds of materials having different refractive index and / or viscosity, and may have the same chemical composition. Examples of the raw material include silicon oil, butyl phthalate, xylene and the like. Alternatively, a solute and a solvent as raw materials may be used and mixed to form a liquid substance.

Further, since silicone oil has a low viscosity, good fluidity, no curing reaction, and no reactivity, there is no influence of encapsulation of a photopolymer or the like in a hologram. In addition, the refractive index can be adjusted easily by simply mixing the high-refractive-index silicone oil and the low-refractive-index silicone oil, and can be arbitrarily selected. Further, when dichromated gelatin is used as the hologram element, moisture resistance is required, but since the silicone oil itself does not easily absorb water, it is possible to impart sufficient moisture resistance to the hologram element. it can.

The cover plate holds the hologram substrate from above and below both sides of the hologram substrate, for example.
Further, the cover plate may be arranged only on one surface on the hologram element side. Furthermore, it is preferable that an antireflection film of MgF ₂ , TiO ₂ or the like is formed on the light incident surface side of the holographic device. The light incident surface side is
A surface on which light on which a display image is projected is incident.

Further, it is preferable that an anti-scattering film such as a black coating film is formed on the surface of the holographic device opposite to the light incident surface side. In addition, the holographic device is used to prevent misalignment and reflection of the glass edge.
It is recommended to fix the periphery with a case made of resin or the like. Alternatively, the periphery of the hologram element may be removed and the seal width S may be provided at that portion.

[0020]

In the holographic device of the present invention, the boundary surface between the hologram substrate and the cover plate is sealed with a liquid substance. The liquid substance is formed by mixing two or more raw material substances having different refractive indexes. Therefore, the refractive index of the liquid substance can be easily adjusted by changing the mixing ratio. Therefore, it is easy to match the refractive index with the cover plate and the hologram substrate.

Further, by selecting a raw material having a low viscosity, a liquid material having a low viscosity can be obtained. Therefore, bubbles are unlikely to be generated inside, and even if bubbles are generated, they can be easily removed.

Further, since the liquid material is sealed in the liquid state, it is not necessary to carry out a curing treatment unlike the conventional resin sealing. Therefore, problems such as alteration of the photosensitive material of the hologram element due to the curing process do not occur. As described above, according to the present invention, the matching of the refractive index is easy, and the photosensitive agent of the hologram element is not deteriorated.
It is possible to provide an excellent holographic device.

[0023]

【Example】

Example 1 FIG. 1 shows a holographic device according to an example of the present invention.
~ It demonstrates using FIG. The holographic device of this example is used for the above-mentioned automobile head-up display.

As shown in FIG. 1, the holographic device 10 includes a hologram substrate 20 having a hologram element 11 formed on a transparent substrate 14 and a transparent cover for sandwiching the hologram substrate 20 from the upper and lower sides. Plate 123,
And 124. In addition, the cover plate 12
3, 124, the substrate 14 and the hologram element 11 have substantially the same refractive index n.

The boundary surfaces between the hologram substrate 20 and the cover plates 123 and 124 are formed by the liquid substances 211 and 211.
It is sealed with 12. The liquid substances 211 and 212 are
It is formed by mixing two or more kinds of raw materials having different refractive indexes and / or viscosity.

Each of these will be described in detail below. The hologram substrate 20 is formed by forming the hologram element 11 on the lower surface of a substrate 14 made of transparent glass. The hologram element 11 is manufactured by exposing a photosensitive material to light, and a recording medium having interference fringes is recorded. The recording medium is a concave lens as a magnifying glass, as described later. Further, on the hologram element 11, two interference fringes having different pitches of 290 nm and 320 nm are recorded. The wavelength selected for the hologram element 11 changes depending on the distance between the interference fringes.

That is, the hologram element 11 has the characteristics of a concave lens, and two types of interference fringes having a curvature are recorded in order to obtain wavelength selectivity. The two types of interference fringes having different pitches can be formed by changing the wavelength and the incident angle of the laser light incident on the photosensitive agent.

The upper cover plate 123 is made of transparent glass, and has a surface 1231 on which the incident light 30 is incident.
An antireflection film 151 made of MgF ₂ and TiO ₂ is coated. Lower surface 1 of upper cover plate 123
232 is the upper surface 142 of the substrate 14 (the hologram element 1
No. 1 is not formed) and the above-mentioned both sides 1
A space between 232 and 142 is sealed by a liquid substance 211 made of silicone oil.

The lower cover plate 124 is made of transparent glass, and the lower surface 1241 of the lower cover plate 124 has a black anti-scattering film 1.
52 is coated. Lower cover plate 1
An upper surface 1242 of 24 is opposed to the hologram element 11 of the hologram substrate 20, and a space between the both 1242 and 11 is sealed with a liquid substance 212 made of silicon oil.

The hologram element 11 of this example is manufactured as follows. First, as shown in FIG. 2, dichromated gelatin (D.
C. G) on the bottom surface 141 of the glass substrate 14 to a film thickness of 1
20 μm to 40 μm after gelling or drying
Stabilize in an atmosphere of ℃ and 50% RH.

Next, a concave lens as a magnifying glass is recorded on the photosensitizer 112, developed and dried. Thereafter, as shown in FIG. 1, the hologram substrate 20 having the hologram element 11 formed thereon is sandwiched and fixed between the upper and lower cover plates 123 and 124 by the liquid substances 211 and 212 made of silicon oil.

Here, in order to record an object on the photosensitive agent 112, generally, as shown in FIG. 2, a glass substrate 14 to which the photosensitive agent 112 is applied, a lens 16 having a certain focal length and a prism 17 are used. Liquid substances 211 and 212 made of silicon oil as a refractive index adjusting liquid are sandwiched between the two.

Argon laser light having a wavelength of 514.5 nm is incident as incident light 33 from the prism 17 side. Since the refractive index is uniform after the incidence, the laser light is reflected by the lens 16
Interference light fringes are formed in the photosensitive agent 112 by the reflected light 332 reflected by the reflection film 161 formed on the surface of the copying lens 16 on the atmosphere side and the incident light 33. A part of the reflected light 332 passes through the substrate 14 and is incident on the prism 17, and a part of the reflected light 332 is reflected by the incident surface 171 of the prism 17.

In this case, as shown in FIG.
The angle α of the incident surface of No. 7 is adjusted with respect to the incident light so that the reflected light 333 of the incident surface 171 of the prism 17 does not travel toward the photosensitive agent 112. By arranging such a prism 17, reflected light 3 at the interface that causes noise
The display noise due to 33 can be removed.

A black coating that absorbs light is applied to the side surface 172 of the prism 17 to prevent the reflected light 333 from the incident surface 171 of the prism 17 from advancing toward the photosensitive agent 112. In this way, a noise image is prevented from being recorded when the lens 16 is copied or recorded on the photosensitive agent 112.

In this example, 112 mm × 46 mm × 1.8 m
A dichromate gelatin film as a photosensitizer 112 having a thickness of 25 μm was formed on a glass substrate 14 (made of soda glass and having a refractive index of about 1.52). The photosensitizer 112
Is a solution in which 0.6 g of ammonium dichromate is dissolved in 100 ml of 4% gelatin solution and has a refractive index of about 1.55.
Is. The substrate 14 provided with the photosensitizer 112 is
72 in a dryer maintained in an atmosphere of ℃ and 50% RH
Left for hours.

Then, with the configuration of FIG.
m Argon laser light, reproduction light (incident angle 33.5 °
Then, the incident angle was changed so that the two colors of 540 nm and 600 nm were obtained (FIG. 3), and the photosensitive agent 112 was exposed to a laser power of 500 mJ in total. The focal length of the lens 16 in FIG. 2 is 1000 mm.

After the exposure, the substrate 14 was washed with water until the color disappeared, and a commercially available photographic hardener fixing solution (Rapid.
It was immersed in a fixer) for 10 minutes. After washing with water, it was immersed in a 90% isopropanol solution for 10 minutes and dried with hot air.
After that, heat aging was performed at 150 ° C. for 4 hours to prevent wavelength change in the actual vehicle environment.

After that, the periphery of the hologram element 11 is removed so that the seal width S in FIG. 1 is set to 5 mm. Also, Mg
It has a structure in which four layers of F ₂ and TiO ₂ are alternately laminated,
An upper cover plate 123 (112 mm × 46 mm ×) having an antireflection film 151 having a luminous reflectance of 0.3% formed on the surface thereof.
1.0 mm) was prepared. On the other hand, a lower cover plate 124 (112 mm × 112 mm × 100 μm) on the surface of which an anti-scattering film 152 formed by adding 5% of black pigment (Glasslite 500 made by Cashew) to epoxy resin and mixing is formed.
46 mm × 1.0 mm) was prepared.

The liquid substances 211 and 212 are commercially available low-refractive-index silicon oils as raw materials (KF56 manufactured by Shin-Etsu Chemical Co., Ltd., viscosity at 25 ° C., 10 cP, refractive index 1.4
98) and a high-refractive-index silicone oil (HIVACF-4 manufactured by Shin-Etsu Chemical Co., Ltd., viscosity of 37 cP at 25 ° C., refractive index of 1.555) are mixed. The low refractive index silicone oil and the high refractive index silicone oil are mixed at 60:40.
Were mixed in a weight ratio of 1 to adjust the refractive index of the substrate 14 to 1.52. The viscosity of the liquid substances 211 and 212 is 19 cP at 25 ° C.

The sealing with the liquid substance of silicone oil was carried out as follows. As shown in FIG. 5, 20 cc of the liquid substance 211 as a sealing material is placed on the upper surface of the lower cover plate 214. Then, after aligning one end 145 of the hologram substrate 20 with one end 2145 of the lower cover plate 214, the other end 146 of the hologram substrate 20 is gradually lowered to combine the hologram substrate 20 and the lower cover plate 214. This descending speed V
Is 10 mm / min.

The sealing of the upper cover plate 123 and the hologram substrate 20 is also carried out by the same steps as above. Further, as shown in FIG. 4, the holographic device 10 has its periphery fixed by a resin case 8 in order to prevent misalignment and reflection of glass edges.

Further, the holographic device 10 of this example is
As shown in FIG. 1, both sides of the hologram substrate 20 are supported by cover plates 123 and 124.
As shown in FIG. 7, by covering the surface of the hologram element 11 with one cover plate 124,
It is also possible to take a double glass structure.

That is, the holographic device 10 shown in FIG.
In No. 0, the antireflection film 151 is formed directly on the atmosphere-side surface of the substrate 14, and the scattering prevention film 152 is formed on the atmosphere-side surface of the cover plate 124. The hologram substrate 20 having the substrate 14 and the hologram element 11 is covered by the liquid substance 212.
It is fixed on the surface of No. 4. In this case, the incident light 30
Enters the holographic device 100 from the substrate 14 side, and the reproduction light 31 thereof is emitted to the substrate side.

In the holographic device 200 shown in FIG. 7, the anti-scattering film 151 is formed directly on the surface of the substrate 14 on the atmosphere side, and the anti-reflection film 151 is formed on the surface of the cover plate 123 on the atmosphere side. There is. This board 1
Hologram substrate 20 having 4 and hologram element 11
Are fixed to the surface of the cover plate 123 by the liquid substance 211. In this case, the incident light 30 is
The holography device 200 from the cover plate 123 side
And the reproduction light 31 is emitted to the cover plate 123 side.

Next, the function and effect of the holographic device 10 of this example will be described. Holographic device 10 of this example
In FIG. 1, the interface between the hologram substrate 20 and the upper and lower cover plates 123 and 124 is sealed with liquid substances 211 and 212 made of silicon oil, as shown in FIG. As can be seen from the above specific example, the refractive index of silicon oil can be easily adjusted by changing the mixing ratio of two different kinds of silicone oil.

Therefore, the refractive index of the hologram substrate 20 and the glass of the cover plates 211 and 212 can be easily matched. Liquid silicone oil is used, and its viscosity is extremely small. Specifically, the silicone oil liquid substances 211 and 212 of this example have a viscosity of 19 cP at 25 ° C., whereas the conventional epoxy resin sealing material has a viscosity of 500 cP.

Therefore, in the liquid substances 211 and 212 of this example, bubbles are not entrained when the hologram substrate 14 is sealed. Further, unlike the conventional sealing using a resin adhesive, curing treatment is not performed, so that the liquid substance 211,
The sealing by 212 does not change the quality of the photosensitive agent of the hologram element 11.

Next, a comparative experiment was conducted on the liquid sealing according to the present invention and the conventional resin sealing. Table 1 below shows a summary of the characteristics of the silicone oil encapsulant of this example and the conventional epoxy resin encapsulant as a comparative example.

As can be seen from Table 1, the silicone oil encapsulant has a low viscosity, good fluidity, no curing reaction, and no reactivity, and therefore is not affected by encapsulation of the photopolymer in the hologram. In addition, the refractive index can be adjusted easily by simply mixing the high-refractive-index silicone oil and the low-refractive-index silicone oil, and can be arbitrarily selected.

When dichromated gelatin is used as the hologram element, moisture resistance is required, but since silicone oil itself does not easily absorb water, the hologram element has sufficient moisture resistance. can do.
On the other hand, the epoxy resin encapsulant has a high viscosity and there is a possibility that air bubbles may be trapped inside during encapsulation. Also, the refractive index is constant at 1.55, and it is not possible to set an arbitrary refractive index. Further, heating may cause a curing reaction, which may affect the characteristics of the hologram element.

Table 2 shows the characteristics of the holographic device 10, such as noise ratio and bubble generation. The top row of the table (N
1) shows the present invention. The second row (N2) in Table 2 is an example in which a conventional epoxy resin sealing material is used as the sealing material. As is known from Table 2, this example (Table 2N1) has extremely good characteristics as compared with the conventional example (Table 2N2). Note that N3 and N4 in Table 2 will be described in the second embodiment.

Further, in the above-mentioned conventional holographic device, a commercially available epoxy thermosetting resin (manufactured by Cemedine, trade name CS-2340-5) is used as a sealing material, and its refractive index is 1. 55, viscosity is 500 cP (25
℃). In this conventional example, the above-mentioned encapsulant is applied to the surfaces of the cover plates 123 and 124 so as to have a thickness of 50 μm, respectively, and the substrate 14 is sandwiched between the cover plates 123 and 124 as shown in FIG. . afterwards,
Heat curing treatment was performed at 120 ° C. for 30 minutes. Other manufacturing methods are the same as those in the above-described embodiment of the present invention.

[0054]

[Table 1]

[0055]

[Table 2]

As described above, according to the present embodiment, it is possible to provide a good quality holographic device which facilitates matching of refractive indexes and uses a sealing material which does not deteriorate the photosensitive material of the hologram element. it can.

As a secondary effect, since silicon oil does not easily absorb water, it has an effect of preventing the hologram element 11 from moisture. Although glass is used for the substrate 14 and the upper and lower cover plates 123 and 124 in this example,
These may be transparent resins or films.

Further, the holographic device 10 using a liquid substance as the sealing material has been shown as an example used in a head-up display of an automobile, but other holographic devices are also applicable. That is, the hologram element 11
Even if the recording medium to be recorded on is another optical element or a stereoscopic image, it can be applied without any inconvenience. Further, it can be similarly applied to a holographic device in which the number of layers of the hologram element or the hologram substrate and the shape thereof are different.

Example 2 In this example, as a photosensitizer for the hologram element in Example 1, a commercially available photopolymer (HR-70 manufactured by DuPont) was used.
0) is used. That is, the commercially available photopolymer is attached to the substrate 14, the photopolymer coating is removed, and only the photopolymer is attached to the substrate 14 (see FIG. 1).

After that, exposure is carried out in the same manner as in Example 1 and 2
An interference fringe pitch of 90 nm was formed. Then, UV irradiation was performed for a total of 6 J to stabilize the photopolymer. The same liquid material of silicone oil as in Example 1 was used as the sealing material. Others are the same as in the first embodiment.

The characteristics of the holographic device 10 of this example are shown as N3 in Table 2. In addition, in this example, a conventional example in which an epoxy resin is used as the sealing material is shown as N4 in Table 2. The epoxy resin encapsulant described above is the conventional example in Table 1 (Table 2N).
It is the same as 2).

As can be seen from the comparison of N3 and N4 in Table 2 above, the present invention provides a significant improvement in characteristics as compared with the conventional example. In the first and second embodiments, D. C. G. Although the example of the photopolymer is shown, other than that, a relief, that is, one having a concavo-convex processed by a photoresist can be applied.

Although silicone oil was used as the raw material of the liquid substance in Examples 1 and 2, butyl phthalate (viscosity 10 cP, refractive index 1.49), xylene, etc., had a low viscosity and were mixed. Therefore, another solution whose refractive index can be easily adjusted can be used.

[Brief description of drawings]

FIG. 1 is a sectional view of a holographic device according to a first embodiment.

FIG. 2 is an explanatory view of the manufacturing process of the hologram element of the first embodiment.

FIG. 3 is a wavelength characteristic diagram of the hologram element of Example 1.

FIG. 4 is a cross-sectional view of the holographic device according to the first embodiment with a case attached.

FIG. 5 is an explanatory view of a sealing process of the holographic device according to the first embodiment.

FIG. 6 is a cross-sectional view of the holographic device having a double glass structure according to the first embodiment.

FIG. 7 is a cross-sectional view of another holographic device having a two-glass structure according to the first embodiment.

FIG. 8 is a schematic explanatory diagram of a conventional head-up display.

FIG. 9 is a configuration diagram of a conventional head-up display.

FIG. 10 is an explanatory diagram of a conventional holographic device.

[Explanation of symbols]

 10, 100, 200. ． ． Holographic device, 11. ． ． Hologram element, 123.124. ． ． Cover plate, 14. ． ． Substrate, 151. ． ． Antireflection film, 152. ． ． Anti-scattering film, 20. ． ． Hologram substrate, 211, 212. ． ． Liquid substance, 30. ． ． Incident light, 31. ． ． Reproduction light,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Tatebayashi, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Yasuhiro Mizutani, 1-1, Showa-cho, Kariya city, Aichi prefecture Within the corporation

Claims (7)

[Claims] 1. A holographic device comprising a hologram substrate having a hologram element formed on a translucent substrate, and a translucent cover plate provided with the hologram substrate, wherein the cover plate, the substrate and the hologram. The element has substantially the same refractive index, and each boundary surface between the hologram substrate and the cover plate is sealed with a liquid substance, and the liquid substance has different refractive index and / or viscosity coefficient. A holographic device, which is formed by mixing two or more kinds of raw materials. 2. The holographic device according to claim 1, wherein the raw material is silicon oil, butyl phthalate, or xylene. 3. The holographic device according to claim 1, wherein the periphery of the holographic device is fixed by a case made of resin or the like. 4. The holographic device according to claim 1, wherein the cover plate sandwiches the hologram substrate from both upper and lower surfaces of the hologram substrate. 5. The holographic device according to claim 1, wherein the cover plate is arranged on one surface of the hologram element side. 6. The holographic device according to claim 1, wherein an antireflection film is formed on the light incident surface side of the holographic device. 7. The holographic device according to claim 1, wherein an anti-scattering film is formed on the surface of the holographic device opposite to the light incident surface side.