JPH01159682A - Production of hologram - Google Patents

Abstract

PURPOSE:To maintain the moisture in a photosensitive film a specified rate or below so that a sharp image is easily obtd. at the time of reproduction by adjusting the moisture content as well prior to exposing and executing sealing in a vacuum atmosphere. CONSTITUTION:A dry plate is placed in the atmosphere of the prescribed humidity prior to exposing and is subjected to a 1st moisture content adjusting treatment to adjust the moisture in the photosensitive film to the prescribed rate. The dry plate is placed in the vacuum atmosphere after the development process and is subjected to the 2nd moisture content adjusting treatment to adjust the moisture in the photosensitive film to the prescribed rate or below. The dry plate is thereafter sealed in the atmosphere of a dry gas. Dichromate or silver salt is applicable as a photosensitive material, of which the dichromate is exemplified by preferably ammonium dichromate and is also exemplified by potassium dichromate, sodium dichromate, etc., in addition thereto. The silver salt is exemplified by silver chloride, silver iodide, etc., used as the ordinary photosensitive material for photography. A hologram which has high heat resistance even in high humidity and can be reproduced at a desired wavelength is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a hologram using a photosensitive film containing gelatin as a weight [t-mutate, etc.].

[Prior Art and its Problems] Conventionally, one of the light-sensitive materials for holograms is one in which gelatin contains dichromate. That is,
For example, a photosensitive film made of gelatin containing ammonium dichromate is coated on a glass plate to create a dry plate of dichromate-based polymer. After exposing this dry plate to light, it is subjected to development processing.

However, when gelatin is used as a photosensitive material, the thickness of the gelatin layer changes due to changes in its water content, and as a result, the recorded interference pitch differs greatly from the interference pitch after sealing, causing the image to disappear. There is a problem with putting it away.

For example, as a technology to solve such problems,
The one disclosed in Japanese Unexamined Patent Publication No. 57-173873 is known. In other words, by covering the surface of a photosensitive film made of gelatin with a glass plate and further molding the peripheral part with epoxy resin, fluctuations in the water content in gelatin can be prevented, or by using poly◆monochrome instead of a glass plate.・Vacuum deposition of para-xylene further prevents fluctuations in the water content of gelatin.

However, if a cover made of a simple glass plate is left in an environment of 30°C or higher and humidity of 60% RH or higher for a long time, the recorded hologram will disappear, and poly, monochrome,
Even when sealed with rose xylene, the reproduced image may disappear if left in an environment of 90° C. and humidity of 90% RH or higher for a long time. In addition, even if the image does not disappear, the bologram reproduction wavelength shifts to the shorter wavelength side with respect to the recording wavelength used during exposure, making it difficult to appropriately set the reproduction wavelength. be.

In addition, as another technique, as described in Japanese Patent Application Laid-Open No. 61-261766, there is a method in which a hologram is created, then vacuum-dried and covered with a protective cover, but this also applies during exposure. There has been a problem in that a discrepancy occurs between the recording wavelength and the reproduction wavelength due to the influence of moisture contained in the dry plate, resulting in an image becoming unclear during reproduction.

As described above, conventional holograms are sensitive to humidity and heat, but in order to be used in meters such as automobiles, they must be heat resistant to 90° C., so there has been a desire for technology that can be applied to these.

The present invention was made in order to solve the problems of the above-mentioned conventional technology, and it is possible to manufacture a hologram that is highly heat resistant even in high humidity, and further develops the hologram so that it can be reproduced at a desired wavelength. To provide a method for manufacturing a hologram.

[Means for Solving the Problems] A method for manufacturing a hologram according to the present invention, which has been made to solve the above problems, uses a dry plate having a photosensitive film on a support, in which gelatin contains a photosensitive substance, In this hologram manufacturing method in which a hologram is manufactured by exposing, developing, and sealing a photoresist film on a dry plate, the first step is to place the dry plate in a predetermined humidity atmosphere and adjust the water content in the photoresist film to a predetermined amount before exposure. After the development process, the dry plate is placed in a vacuum atmosphere to adjust the moisture content in the photosensitive film to a predetermined amount or less. It is characterized by being sealed.

Here, a dichromate or a silver salt can be applied to the above-mentioned photosensitive material.Ammonium dichromate is preferably used as the dichromate, but potassium dichromate, dichromate Examples of the silver salt include silver chloride and silver iodide, which are used as light-sensitive materials for ordinary photography.

As the support, a glass plate, a plastic plate, a metal plate, etc. are used depending on the purpose.

A preferred embodiment of the first water content adjustment process before exposure is 0, 1 to 5 in order to reduce the water content in the photoresist film to a predetermined amount or less.
There is a process in which a dry plate is exposed to a Torr atmosphere for a period of time (for example, 5 minutes) to reach equilibrium in moisture content.

By performing this first water content adjustment process, the thickness of the photoresist film after development can be adjusted to the same thickness as during exposure, and as will be described later, the recording wavelength and reproduction wavelength can be matched. can be done. Note that in the first moisture content adjustment process, heat treatment at around 90° C. may be added in order to quickly reduce the moisture content. Further, as another preferred embodiment of the first water content adjustment process, a process of placing the dry plate in an atmosphere with higher humidity than vacuum is performed. By adjusting the humidity of this atmosphere, a desired reproduction wavelength different from the recording wavelength can be selected.

The exposure conditions are a photosensitive range suitable for exposing a photosensitive material, and for example, when a photosensitive film of a dichromic acid polymer is used, a wavelength range shorter than 550 nm.

One of the preferred aspects of the second moisture content adjustment treatment after development is as follows:
0.005~0. In an ITorr atmosphere for a period of time long enough for the moisture content in the photoresist film to reach equilibrium (for example, about 5 minutes)
Place a drying plate to remove most of the moisture in the photoresist film.

The purpose of the seal is to prevent the amount of water in the photosensitive film from changing after development due to the influence of external humidity, and the sealing method is to use a cover glass and seal with an optical adhesive. As the adhesive at this time, it is necessary to use a colorless and transparent adhesive having a refractive index approximately equal to that of the cover glass. It should be noted that the atmosphere when performing the above sealing must be set in such a way that the moisture content in the photoresist film does not fluctuate; in other words, the second moisture content adjustment process is performed in a vacuum atmosphere. Moisture conditioning and sealing may be performed in dry gas, or at high temperatures (eg, 105° C.) where moisture evaporates.

[Function] According to the hologram manufacturing method of the present invention, not only is the second moisture content adjustment process performed in a vacuum atmosphere after development, but also the first moisture content adjustment process such as vacuum treatment is performed before exposure. The moisture content adjustment process was added after the inventor discovered that differences in the humidity atmosphere during exposure caused large fluctuations in the reproduced wavelength, as explained below. It is.

That is, for example, when exposing a photosensitive film made of gelatin containing dichromate, exposure is performed at a recording wavelength of 514.5 nm in various humidity atmospheres, and the second moisture content after development is The conditions for the adjustment treatment were 90°C, O, l.
A hologram was created by carrying out 1 hour of 'rorr' vacuum heating treatment. Then, we search for the optimal wavelength for reproduction, and as shown in Figures 2 and 3, we plot the difference between the reproduction wavelength and recording wavelength on the vertical axis and the humidity (degree of vacuum) at the time of exposure on the horizontal axis. expressed.

As a result, as shown in FIG. 2, the lower the humidity at the time of exposure, the sharper the difference between the reproduction wavelength and the recording wavelength becomes.As shown in FIG. When the value is less than ITorr, the reproduction wavelength matches the recording wavelength. That is, in addition to the vacuum drying process (second moisture content adjustment process) after development, the vacuum drying process (second moisture content adjustment process) is also performed before exposure.
By performing the first water content adjustment process), the water content in gelatin at the time of exposure can be reduced to a certain amount or less,
The idea was to draw attention to the fact that vacuuming before exposure is a good way to match the reproduction wavelength with the recording wavelength.

Further, as is clear from FIG. 2, by adjusting the amount of water in the photoresist film before exposure to a larger amount, it is also possible to set the reproduction wavelength to a desired wavelength different from the recording wavelength. Moreover, since the photoresist film is placed in a vacuum atmosphere after development through a second moisture content adjustment process, there is almost no moisture in the photoresist film, and the moisture content does not change due to sealing.

[Effect] As explained above, according to the present invention, the moisture content is adjusted before exposure, and if the film is placed in a vacuum atmosphere and then sealed in a dry atmosphere, the amount of moisture in the photoresist film is reduced. Since the moisture content can be kept below a certain level, the image will not disappear or the reproduced wavelength will not deviate from the recorded wavelength even if left in high temperature conditions for a long time, making it easy to obtain clear images during reproduction. Obtainable.

Further, by setting the humidity in the photoresist film to a high level before exposure, an image can be obtained at a desired reproduction wavelength different from the recording wavelength.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows a cross section of a hologram manufactured by the manufacturing method of this example. This hologram is constructed by forming a photosensitive film 3 containing ammonium dichromate in gelatin on a glass substrate 1, and sealing the film with a glass cover 7 using an adhesive 5.

To manufacture such a hologram, first, as shown in Figure 1, a photosensitive material is prepared by mixing 100 parts by weight of water with 5 parts by weight of gelatin and 1 ffi amount of ammonium dichromate, and this is placed on a glass substrate. A photoresist film is formed by coating the film to a thickness of 25 nm. Next, the photosensitive film on the dry plate thus produced is dried at room temperature.

Next, the dry plate before exposure is subjected to a vacuum drying process (first moisture content adjustment process) to remove moisture in the photosensitive film. The degree of vacuum at this time is 0. Process at ITorr for 15 minutes. The vacuum drying process may be carried out for a time sufficient to bring the moisture in the photoresist film into an equilibrium state at the degree of vacuum, but the processing time can be shortened by increasing the degree of vacuum. Therefore, it is preferable to change the degree of vacuum and time as appropriate depending on the thickness of gelatin applied to the gelatin dry plate.

Next, an argon ion laser (51
4.5 nm). During exposure, no moisture enters the gelatin photosensitive film, such as in a vacuum container or in a liquid that does not contain water (in an index matching liquid).
Expose to light.

Next, it is immersed in a 0.5% by weight aqueous solution of ammonium dichromate, and then immersed in a 20° C. hardening fixer (Rapidfixer, manufactured by Kodak) for 10 minutes to perform a hardening treatment.

After that, development processing is performed. As a condition for this process, 25
After immersion in 70% inpropyl alcohol at ℃ for 2 minutes,
It is immersed in 100% inpropyl alcohol at 0°C for 4 minutes, then washed with water, bathed in hot water, and dehydrated.

Thereafter, after performing high-temperature drying by drying under hot air at 90°C for 10 minutes or more, vacuum treatment (vacuum heating drying process: second moisture content adjustment process) in a 90°C atmosphere is performed in a vacuum, and the gelatin is Remove the moisture inside completely. The processing conditions at this time were 0.005 to 0. The process is carried out at a vacuum level of 1 Torr for a period of time (for example, about 5 minutes) until the amount of water in the photoresist film reaches equilibrium.

Next, using a cover glass 7 in a dry gas, the dry plate is sealed with an optical adhesive. The purpose of sealing with dry gas is to prevent the moisture content in the photoresist film from changing if air is introduced.

According to the hologram produced as described above, the gelatin drying plate is vacuum-dried before exposure to remove moisture in the gelatin, and then exposed, developed, and then vacuum-dried again, so that the exposure to light during exposure and after sealing is completed. Most of the water in the film is removed, and the water content conditions can be kept the same. This can prevent the playback wavelength from shifting due to expansion of gelatin due to differences in water content in the gelatin photosensitive film. Therefore, if an argon ion laser is used for the recording wavelength, the reproduction wavelength can also be reproduced by a laser of the same wavelength, and its durability can be maintained for more than 1000 hours in an environment of 90°C and 90% RH. However, there is no change in diffraction efficiency or reproduction wavelength.

As another example, instead of performing vacuum drying in the first moisture content adjustment process, the reproduction wavelength can be set to a wavelength different from the recording wavelength. By changing the reproduction wavelength in this way, the following usage becomes possible. In other words, laser light can only obtain a specific wavelength and is limited to the playback wavelength range, but if you want to play back green on a TV screen, for example, you can record at a wavelength longer than 555 nm and use the first By appropriately selecting the humidity atmosphere for the moisture adjustment process, it is possible to set the green reproduction wavelength to 555 nm.

In addition, as a method of adjusting the humidity atmosphere in this case, the moisture content in the photoresist film obtained in a certain humidity atmosphere is determined in advance by measuring the absorption spectrum in the infrared region, and the moisture content is determined in advance. This can be achieved by performing moisture content adjustment treatment in a humid atmosphere.

Such a reproduced image using a bologram can be displayed in a superimposed manner with other images, allowing various displays to be performed.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing the manufacturing process of a hologram according to an embodiment of the present invention, and Figs. 2 and 3 show the relationship between the difference between the reproduction wavelength and the recording wavelength and the humidity (degree of vacuum) during exposure. The graph and FIG. 4 are cross-sectional views schematically showing a hologram manufactured by the manufacturing method of the present invention. 1...Glass substrate 3...Photoresist film 5...Adhesive 7...Cover glass agent Patent attorney Establishment
Tsutomu (and 1 other person) Figure 1 Figure 2 Exposure of 51 degrees t% RH Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Production of a hologram, in which a hologram is produced by exposing, developing, and sealing the photosensitive film of the dry plate using a dry plate having a photosensitive film on a support in which gelatin contains a photosensitive substance. In this method, before exposure, a dry plate is placed in a predetermined humidity atmosphere to perform a first moisture content adjustment process to adjust the moisture in the photoresist film to a predetermined amount, and after development, the dry plate is placed in a vacuum atmosphere to adjust the moisture content in the photoresist film. The second step is to adjust the moisture content to a predetermined amount or less.
A method for producing a hologram, which comprises subjecting the hologram to water content adjustment treatment, followed by sealing in a dry gas atmosphere. 2. The method for producing a hologram according to claim 1, wherein the photosensitive material is dichromate. 3. The method for producing a hologram according to claim 1, wherein the photosensitive material is a silver salt. 4. Any one of claims 1 to 3, wherein the first water content adjustment process is characterized in that the dry plate is processed in a vacuum atmosphere to reduce the water content in the photosensitive film to a predetermined amount or less. A method for manufacturing a hologram as described in . 5. According to any one of claims 1 to 3, the first water content adjustment process is performed in a humid atmosphere such that the reproduction wavelength has a predetermined wavelength difference with respect to the recording wavelength. hologram manufacturing method.