JPH08101628A - Recording method for volumetric hologram - Google Patents

Abstract

PURPOSE: To provide a recording method for volumetric hologram capable of producing a hologram expanded in half-width by using a photopolymer material for volumetric hologram recording for which photopolymn. is utilized. CONSTITUTION: This volumetric hologram recording method includes a stage for exposing interference fringes by light to a recording medium 3 having a recording layer consisting of a compsn. contg. a radical polymerizable compd. and a photo radical polymn. initiator which senses a laser beam or light having excellent coherence, then subjecting this recording medium to full-surface exposing to the light or other light. The recording method described above is provided with a heating stage between the interference fringes exposure and the full- surface exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume hologram recording method, and more particularly, to a volume hologram manufacturing method in which the half width of a diffraction wavelength is expanded.

[0002]

2. Description of the Related Art A hologram is one in which two light beams having the same wavelength (object light and reference light) are made to interfere with each other and the wavefront of the object light is recorded as an interference fringe on a photosensitive material. When this light is applied, a diffraction phenomenon due to interference fringes occurs, and the same wavefront as the original object light can be reproduced.

Holograms are classified into several types according to the recording pattern of interference fringes. In recent years, so-called volume holograms, which record interference fringes by the difference in refractive index inside the recording layer, have high diffraction efficiency and excellent wavelength selection. Due to its properties, it is being applied to applications such as three-dimensional displays and optical elements.

In recent years, as a photopolymer material capable of recording a volume hologram by utilizing photopolymerization, JP-A-2-30
No. 81, a material utilizing the difference in refractive index between the thermoplastic resin and the radical polymerizable compound, or
In JP-A-107999, a material in which a radically polymerizable compound having a different refractive index and a cationically polymerizable compound are used in combination is proposed.

By using these materials, a bright volume hologram having a large refractive index modulation can be obtained by a dry process. However, the latter material is suitable for applications requiring excellent wavelength selectivity such as optical elements, since volume holograms with a relatively narrow half-width of diffraction wavelength are recorded. For applications such as original image recording, the amount of diffracted light is insufficient due to the narrow half-width, which causes a problem that the apparent brightness of the hologram is insufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a volume hologram recording method capable of producing a hologram having an expanded half width by using a photopolymer material for volume hologram recording utilizing photopolymerization. To do.

[0007]

That is, the present invention comprises a composition containing a radically polymerizable compound (a) and a photoradical polymerization initiator system (b) which is sensitive to laser light or light having excellent coherence. In a volume hologram recording method including a step of exposing a recording medium having a recording layer to interference fringes caused by the light, and then exposing the entire surface to the light or other light, a heating step is performed between the interference fringe exposure and the entire surface exposure. A method of recording a volume hologram, characterized by being provided.

The present invention also provides a volume hologram obtained by the above recording method.

Interference by the above light with a recording medium having a recording layer comprising a composition containing a radically polymerizable compound (a) and a photoradical polymerization initiator system (b) which is sensitive to laser light or light having excellent coherence. In the volume hologram recording method including the step of exposing the fringes to light and then the whole surface of the light or other light, a half value width of the diffraction wavelength of the hologram can be reduced by providing a heating step between the interference fringe exposure and the whole surface exposure. Can be expanded.

Although the reason why the half-width is increased by providing the heating step is not clear, the fringes formed by the interference fringe exposure, which are composed of the polymer of the radical-polymerizable compound, are not present in the presence of unreacted radical-polymerizable compound. , Swells by heating,
As a result, it is considered that the distribution of the stripe interval spreads.

The temperature of the heating step is preferably 40 ° C to 80 ° C. The full width at half maximum can be expanded at 80 ° C or higher, but the peak wavelength of the diffracted light may shift to a shorter wavelength.
When it is necessary to suppress this shift, heating at 80 ° C. or lower is recommended.

Suitable compositions used in the present recording method include, in addition to (a) and (b) above, a cationically polymerizable compound (c) which is liquid at room temperature and excellent laser light or coherence. A photo-cationic polymerization initiator system that has low photosensitivity to light and polymerizes component (c) when exposed to light of another wavelength.
A composition containing (d) may be mentioned. If necessary, a polymeric binder, a thermal polymerization inhibitor, etc. may be used in combination.

In this composition, the radically polymerizable compound is polymerized by exposure to interference fringes, but since the cationically polymerizable compound which is liquid at room temperature remains unreacted in the recording layer, the radically polymerizable compound is polymerized. It is easy to cause swelling.

The components (a) to (d) are described in JP-A-5-107.
For example, those described in Japanese Patent Application Publication No. 999 or Japanese Patent Application No. 5-84521 may be used.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Using the photosensitive compositions shown in each of Examples and Comparative Examples described below, a test plate was prepared by the following method, exposed to obtain each hologram, and the physical properties were evaluated by the following methods.

(Preparation of Test Plate) A predetermined amount of the photoradical polymerization initiator (system) component (b) and the photocationic polymerization initiator (system) component (d) are dissolved or dispersed in a solvent, and then the component (a) ), Component (c) and other components such as polymer binder were added and stirred, and filtered to obtain a photosensitive solution. This sensitizing solution is applied on a 16 cm x 16 cm glass plate using an applicator, and it is applied at 90 degrees for 5
Allow to dry for minutes. Furthermore, a polyethylene film having a thickness of 80 μm (LUPIC LI, Tonen Kagaku KK) was laminated on it, and this plate was divided into 3 to 4 cm squares to obtain test plates.

(Exposure) The first exposure was carried out using 514.5 nm light of an argon ion laser. FIG. 1 shows a schematic diagram of a recording method of a reflection hologram. The light intensity of one light flux on the surface of the test plate was 1.0 mW / cm ² , and the exposure was performed for 30 seconds. After the completion of the first exposure, as a heating process, the test plate was allowed to stand still in a flan machine having a given constant temperature. Then, as post-exposure, light from a high-pressure mercury lamp (manufactured by Nippon Battery Co., Ltd., experimental ultraviolet irradiation device, FL-1001-2) was irradiated from the polyethylene film side for 1 minute.

(Evaluation) The diffraction efficiency of the reflection hologram is
It was determined from the reflectance of the hologram by Shimadzu's own recording spectrophotometer UV-2100 and the attached integrating sphere device ISR-260.

The photosensitive compositions of the following Examples and Comparative Examples were prepared, and each hologram was prepared by the above method, and this evaluation was performed as described above.

(Examples 1 to 4) Table 1 shows the composition of the photosensitive composition for hologram recording used in Examples 1 to 4. Table 2 shows changes in the half-value width of the diffraction wavelength peak and changes in the diffraction peak wavelength under various heating conditions.

[0021]

[Table 1]

[0022]

[Table 2]

After the completion of the first exposure, the half width can be increased by providing the heating process. (Comparative Examples 1 and 2) These are comparative examples with respect to Examples 1 to 4, and the same photosensitive composition as that used in Examples 1 to 4 was used, and a heating process was provided after completion of the first exposure. This is an example showing that the half width does not change by the conventional technique when the post exposure is performed and when the hologram is left for 1 hour at room temperature after the first exposure and then the post exposure is performed.
Table 3 shows the treatment conditions and the change in the half-value width of the diffraction peak.

[0024]

[Table 3]

The above-mentioned Examples 1 to 4, Comparative Example 1,
The abbreviations of the compounds shown in Comparative Example 2 and Table 1 are as follows.

Cationic polymerizable compound (c) CAT-1 ... Glycidyl ether obtained by adding 4 moles of propylene oxide to pentaerythritol, and the number of glycidyl groups per molecule is 3

Radical polymerizable compound (a) A-BPHE ... 9,9-bis (3-ethyl-4-acryloxydiethoxyphenyl) fluorene

Photoradical polymerization initiator system (b) DYE-1 ... 3,9-diethyl-3'-carboxymethyl-2,2'-thiacarbocyanine, iodine salt-DPI.TF ... diphenyl Iodonium trifluoromethanesulfonate

The cationic photopolymerization initiator system _{(d) · TPS · SbF 6} ··· manufactured by Ciba-Geigy, triarylsulfonium, hexafluoroantimonate compound, trade name UVI-6974

Other Components and Solvents P-1 ... Copolymer of methyl methacrylate / ethyl acrylate / acrylic acid (copolymerization ratio = 45/49 /
6) ・ BuOH ・ ・ ・ n-butyl alcohol ・ MIBK ・ ・ ・ Methyl isobutyl ketone

[0031]

According to the method of the present invention, a photopolymer material for volume hologram recording utilizing photopolymerization can be used to produce a bright-looking volume hologram with an expanded half-width.

[Brief description of drawings]

FIG. 1 shows a schematic view of a reflection hologram recording method in the first exposure.

[Explanation of symbols]

 1: Glass plate 2: Recording layer 3: Polyethylene film 4: Laser 5: Laser beam 6: Mirror 7: Beam splitter 8: Objective lens 9: Lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Iwao Sumiyoshi 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (4)

[Claims] 1. A recording medium having a recording layer comprising a composition containing a radically polymerizable compound (a) and a photoradical polymerization initiator system (b) which is sensitive to laser light or light having excellent coherence. In the method of recording a volume hologram, which comprises the step of exposing the interference fringes due to the above, and then exposing the whole surface with the above-mentioned light or other light, a heating step is provided between the interference fringe exposure and the whole surface exposure. Recording method. 2. The recording method according to claim 1, wherein the heating step is performed in a temperature range of 40 ° C. to 80 ° C. 3. The composition according to claim 1, further comprising a cationically polymerizable compound (c) which is liquid at room temperature, low photosensitivity to laser light or light having excellent coherence and a different wavelength. The recording method according to claim 1, further comprising a photocationic polymerization initiator system (d) which polymerizes the component (c) upon exposure to light. 4. A volume hologram recorded by the method of claim 1.