JPH0197982A - Production of hologram - Google Patents

Abstract

PURPOSE:To prevent the generation of a deviation between a reproducing wavelength and recording wavelength even if a hologram is exposed to a high temp. and high humidity by equalizing the film thickness of gelatin at the time of recording and the film thickness after development and forming the hologram in such a manner that moisture is not incorporated therein at all. CONSTITUTION:A liquid mixture composed of prescribed ratios of water, gelatin and dichromate is uniformly dropped onto base glass 1 to form the gelatin layer 2 contg. the dichromate which is a sensitizing agent. After the gelatin layer 2 is exposed and rinsed, an additive which can be replaced with the moisture of the gelatin is added into the gelatin and the gelatin recording medium is dried in a vacuum. Cover glass 3 is sealed on the hologram in the vacuum. The moisture in the gelatin lost by drying of the gelatin recording medium in the vacuum and sealing the same in the dry gas is compensated by the additive. The gelatin recording medium which does not contain the moisture at all and is equal in the film thickness of the gelatin at the time of the recording and the film thickness after the development is thus obtd. The generation of the deviation between the reproducing wavelength and the recording wavelength is obviated even if the recording medium is exposed to the high temp. and the high humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a hologram with excellent environmental resistance.

[Conventional technology]

The conventional hologram phenomenon involves exposing dichromate gelatin to light and then hardening the gelatin with a hardening agent. Next, excess hardening agent and dichromic acid were washed away with water, excess water contained in the gelatin was removed by hot water bathing, dehydration treatment, etc., and finally, the hologram was completed by high temperature drying.

[Problems to be Solved by the Invention] However, since the above hologram is in direct contact with the outside air, it is strongly affected by moisture.

Specifically, when exposed to an environment with a temperature of 30° C. and a humidity of 60% R1 for a long time, the hologram recorded by exposure to light gradually disappeared.

Conventionally, in order to solve the above-mentioned problems, the hologram was covered in air with a glass plate, and the surrounding area was shielded with epoxy resin or the like. Also, special public service 1973-173
As shown in Japanese Patent No. 873, it is known to vacuum-deposit polymonochrome para-xylene on the surface of a hologram to provide a moisture-proofing effect. However, these methods
No decrease in diffraction efficiency is observed even when exposed to an environment of 40°C and 190% RH, but in an environment of 90°C or higher, the hologram disappears or the reproduction wavelength and recording wavelength become misaligned. A problem has arisen in that the properties of gelatin change.

The present invention has been made in view of the above-mentioned problems, and provides a method for manufacturing a hologram that maintains diffraction efficiency and does not cause a deviation between the reproduction wavelength and the recording wavelength even when exposed to high temperature and high humidity. The purpose is to

[Means for solving problems]

The present inventors were able to derive the hologram manufacturing method of the present invention through the following process.

In other words, as a result of our research, the present inventors found that conventional holograms made of dichromate gelatin exposed to light and subjected to phenomenon processing and then sealed with a cover glass as they were were sealed with a cover glass because the gelatin contained water. It was found that the reproduced image disappeared simply by heating to 40°C.

Therefore, after the phenomenon treatment, the present inventors dried it by vacuum heating and then sealed it with a cover glass in a dry gas. As a result, we were able to obtain excellent heat resistance with no change in conversion efficiency even in an atmosphere of 90"C for 1000 hours, but the reproduction wavelength shifted to the shorter wavelength side than the recording wavelength. For this, the room temperature at the time of exposure is 20℃, the humidity is 50%R1
1, the recording wavelength is 514 nm and the reproducing wavelength is 4.
The wavelength becomes 90 nm, which results in a shift of approximately 24 nm to the shorter wavelength side. As a result of our investigation into the cause of this, we found the following.

The reason for this is that gelatin already contains water at the time of exposure, and when processing the phenomenon during exposure, the water is removed by vacuum heating. When comparing the film thickness with the film thickness after the phenomenon, it was found that the film thickness after the phenomenon was reduced by the amount of moisture in the gelatin.In other words, the pitch of the interference fringes recorded during exposure was In comparison, since the pitch decreases after vacuum heating, the reproduction wavelength shifts to the shorter wavelength side than the recording wavelength.

The present invention was achieved by investigating the above-mentioned causes. In the hologram manufacturing process, after exposing gelatin to water and washing it with water, there is a step of adding an additive that can replace water in gelatin to gelatin. A method for manufacturing a hologram is adopted, which includes the steps of drying a gelatin recording medium in a vacuum, and sealing the hologram in a dry gas.

[Effect]

As mentioned above, in the hologram manufacturing process, the gelatin recording medium is dried in vacuum and sealed in a dry gas, and the moisture in the gelatin that is lost is supplemented with an additive. It was possible to obtain a gelatin recording medium in which the film thickness during gelatin recording was equal to the film thickness after the phenomenon.

〔Effect of the invention〕

By adopting the present invention, it is possible to equalize the film thickness of gelatin during recording and the film thickness after the phenomenon, and to prevent gelatin from containing any moisture.
It was possible to obtain a hologram in which the reproduction wavelength and recording wavelength do not deviate even when exposed to high humidity.

〔Example〕

The hologram manufacturing method of the present invention will be explained using FIGS. 1 and 2.

First, a mixture of water, gelatin, and dichromic acid in predetermined amounts was uniformly dropped onto the base glass 1 to form a gelatin layer 2 containing dichromic acid, which is a photosensitizer, with a thickness of about 15 μm. In this example, the amount of gelatin and dichromic acid added was 3 gelatin per 100 g of water.
The amount was 1 to 7 g, and the dichromic acid was 1 to 3 g. A first step of exposing the gelatin layer 2 by irradiating green light with a wavelength of 514 nm and blue light with a wavelength of 488 nm is a photosensitive step S1.
I did it. The phenomenon of the photosensitive gelatin recording medium is as follows: First, in the hardening process S2, the exposed gelatin layer 2 was immersed in a 50% aqueous solution of a hardening agent (Kodak Rabbit Fixer) for 5 to 10 minutes to harden the gelatin layer 2. .

Then, as a water washing step S3, the gelatin layer 2 is hardened.
All excess hardening agent and dichromic acid contained in gelatin N2 were washed away by washing with water for about 15 minutes.

Thereafter, in the second addition step S4, the gelatin recording medium is immersed for a predetermined time in an aqueous solution of a predetermined concentration of ethylenediaminetetraacetate diammonium as an additive to replace water in the gelatin layer 2. impregnated with. Note that the concentration of the additive and the immersion time vary depending on the thickness of the gelatin layer 2, the humidity during exposure, etc. In this example, the concentration of ethylenediaminetetraacetate diammonium was set to 0.1 to 0.
A 5% aqueous solution was used, and the immersion time was about 3 minutes.

Thereafter, as a third step, dehydration step S5, the gelatin recording medium is immersed for 3 minutes in a 70% solution of isopropyl alcohol, which is a hydrophilic and volatile organic solvent, and for 3 minutes in a 100% solution. The moisture adhering to layer 2 was removed.

Then, in the fourth drying step S6, the gelatin recording medium is heated to 70 to 80° C. in order to remove part of the isopropyl alcohol and water contained in the gelatin layer 2.
was exposed to hot air for 10 to 15 minutes. In addition to the above drying step S6, in order to completely remove the moisture in the gelatin layer 2, the above gelatin recording medium was vacuum dried at a predetermined degree of vacuum and drying temperature as a vacuum drying step S7. . Note that the conditions for the degree of vacuum and drying temperature in the drying step S7 are II! of the gelatin recording medium. This varies depending on the J thickness, humidity during exposure, etc. In this example, the gelatin recording medium was heated to approximately 0.05 T.
The mixture was heated at about 80° C. for 1 hour in a vacuum of

Finally, the hologram was sealed with a cover glass in a sealing step S8, which was the fifth step. Specifically, first, in a vacuum heating step S7, the vacuum atmosphere of the gelatin recording medium placed in a vacuum is replaced with a dry nitrogen atmosphere. Then, in this nitrogen atmosphere, the cover glass 3 was sealed to the surface of the base glass 1 on which the gelatin N2 was provided using a transparent adhesive having a refractive index substantially equal to that of the base glass 1 supporting the gelatin layer 2. Here, the cover glass 3 and the base glass 1 are subjected to anti-reflection treatment.

The environmental resistance of the hologram obtained by the above hologram manufacturing method was evaluated. As for environmental resistance, the hologram was kept stationary in an atmosphere of 90° C. for 1000 hours. As a result, the hologram obtained by the above manufacturing method not only had no decrease in diffraction efficiency, but also had an excellent hologram in which there was no discernible deviation between the reproduction wavelength and the recording wavelength.

In the above embodiment, cyanmonium ethylenediaminetetraacetate was used as the additive, but the additive is not limited to this, and any additive may be used as long as it satisfies the following conditions.

(1) It should not have any adverse effects on gelatin such as dissolution or discoloration.

(2) It cannot be dissolved in the dehydration treatment solution during the phenomenon.

(3) It must be stable at at least 100°C without any changes such as dissolution.

It is sufficient that the additive satisfies the above conditions, and for example, ethylenediaminetetraacetic acid salts such as ethylenediaminetetraacetic acid niummonium salt, ethylenediaminetetraacetic acid tetrasodium tetrahydrate, and ethylenediaminetetraacetic acid trihydrate may be used.

In the above embodiment, vacuum drying was performed after the high temperature drying step S6, but vacuum drying may be performed directly after dehydration.

In the above embodiment, the hologram was sealed in a dry nitrogen atmosphere, but the environment for sealing is not limited to this, and any environment may be used as long as it is in a dry gas atmosphere.

In the above example, the gelatin recording medium was heated at 80°C in vacuum.
Although the drying temperature is not limited to this, the drying temperature is 1.
The temperature range may be from 5 to 90°C.

This is because if the temperature is 15° C. or lower, the gelatin recording medium cannot be sufficiently dried, and if the temperature is 90° C. or higher, the gelatin recording medium will deteriorate in quality.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of the manufacturing process showing this embodiment, and FIG. 2 is a cross-sectional view of the hologram. 1... Base glass, 2... Gelatin layer, 3...
cover glass. Representative Patent Attorney Takashi Okabe

Claims (5)

[Claims] (1) A first step of exposing a gelatin recording medium containing a photosensitizer to a light interference pattern and then washing it with water to remove the photosensitizer; and adding an additive that can replace water in the gelatin recording medium. a second step of adding water to the gelatin recording medium; a third step of removing water contained in the gelatin recording medium by immersing the gelatin recording medium in a hydrophilic and volatile organic solvent; and a third step of removing water contained in the gelatin recording medium by drying the recording medium. A method for manufacturing a hologram, comprising: a fourth step of removing moisture in gelatin and replacing the moisture in the gelatin with the additive; and a fifth step of sealing the recording medium in a dry gas. (2) The method for manufacturing a hologram according to claim 1, wherein the second step of adding the additive comprises immersing the recording medium in the additive for a predetermined period of time. (3) The method for producing a hologram according to any one of claims 1 to 2, wherein the additive in the second step comprises at least one of ethylenediaminetetraacetate. (4) Drying the recording medium in the fourth step in a vacuum for 9
The method for manufacturing a hologram according to any one of claims 1 to 3, characterized in that the hologram is dried by heating at a temperature of 0° C. or lower. (5) The drying of the recording medium in the fourth step is performed by drying with hot air and then heating and drying in a vacuum at 90° C. or lower. How to make a hologram.