JPS60122983A - Copying method of hologram - Google Patents

Abstract

PURPOSE:To prevent generation of an interference caused by a gap between a master hologram and a photosensitive base plate, and to obtain a copy hologram having a high accuracy by interposing a gel-like gelatin colloid between the master hologram and the photosensitive base plate, and executing an exposure. CONSTITUTION:Between a master hologram 9 having a hologram recorded on a silver salt sensitized material 9b desirably, on a transparent base plate 9a of transparent plastic, glass, etc., and a photosensitive base plate 10 provided with a photoresist layer 10a on a base plate 10b made of plastic, glass, a metallic plate, etc., a gelatin colloid 11 is interposed as a thin layer by using rolls 12, 12 or using a plain press 13, or the like. A copying light 3 is exposed from the base plate 9a side of an obtained laminated body. After the exposure, the photosensitive base plate 10 is peeled off and a development is executed. In this way, owing to existence of the colloid layer 11, generation of an interference fringe caused by a gap between the base plates 9, 10 is eliminated, and a copy hologram 10 having a high accuracy is obtained.

Description

[Detailed description of the invention] The present invention relates to a method for optically copying holograms.

Holograms generally record light interference patterns on a substrate, and can record three-dimensional images and other high-density information.Holograms can be used for many purposes such as optical memory, anti-counterfeiting, and decoration. It is expected that it will be applied in various fields.

Basically, a hologram is produced by shining light onto a line or information source to obtain information light, causing light interference between the line and the reference light, and recording the information on a photosensitive material.

However, in order to put holograms into practical use in various fields, it is necessary to quickly and efficiently mass-produce a large number of lines and holograms.

Therefore, instead of manufacturing a large number of holograms one by one using the above-described method, a method is used to copy a hologram obtained using the above-described method.

One of the nine conventional copying methods is to place a hologram to be copied (hereinafter referred to as a master hologram) and an unexposed photosensitive substrate in close contact with each other, and then apply copy light from the master hologram side. The master hop is applied onto the photosensitive material of the unexposed photosensitive substrate.
This method records the same interference fringes as the gram.

This will be explained with reference to the drawings in Fig. 1.

Photosensitive material 1 with a substrate of 1 m and a hologram of interference fringes recorded
When the copy light 3 is irradiated from the master hologram 1 side with the master hologram blind made of b and the photosensitive substrate 2 made of the substrate 2b and the photosensitive material 2a facing each other, a hologram identical to the master hologram, that is, a copy hologram is produced. It is recorded on the photosensitive material 2a.

A laser or mercury lamp is used as the light source for copying light.

Copy light is generally irradiated onto the master hologram substrate 1a.
The beam is incident from a direction perpendicular to , or from a direction that satisfies the Bragg condition.

However, if you do the shikoby by such method.

Due to the non-uniformity of the gap 4 between the master hologram 1 and the photosensitive substrate 2 and the non-uniformity of the incident angle of the light incident on the photosensitive substrate 2, interference of equal thickness and angle of inclination occur on the Sicoby hologram, respectively. Interference fringes called interference overlap the hologram image, impairing the color and accuracy of the hologram, and in the case of image-type images, the appearance is impaired.

This will be explained with reference to the drawings in FIG.

The incident light of the copy light 8 is divided into a 90th order light and a first order light (reproduction signal light) by a master hologram l.

On the surface of the photosensitive material 2a of the zero-order ray photosensitive substrate, the light is further divided into transmitted light 5 and reflected light 6, and one reflected light 6 is reflected on the lower surface of the master hologram 1 and then passes through the photosensitive substrate 2. The primary light is similarly divided into transmitted light 7 and reflected light 8.

As a result, interference between transmitted light 5 and reflected light 6 of the 0th order light,
Interference between the transmitted light 7 and the reflected light 8 of the primary light occurs, and interference fringes expressed by the formula 2π ■=”” (Ryon D Co' 1 ) are recorded on the photosensitive material 2a of the photosensitive substrate. It will end up being put away. In addition, ■ is the intensity of the interference light, and λ is the wavelength of the light.

i is the refractive index of the gap 4, and is the angle of one beam of light with respect to a plane perpendicular to the photosensitive substrate, that is, the incident angle of light.

From the above results, it can be seen that if the interval or the amount of incident angle of light is not uniform depending on the position of the hologram, interference fringes will appear. Therefore, theoretically, interference fringes will disappear if the master hologram 1 and the photosensitive substrate 2 are brought into perfect contact with each other and the gap is set to 0.

However, in reality, even if a vacuum adhesion device or the like is used, it is inevitable that a gap of 3 μm or less will occur.

Equal thickness interference and equal oblique angle interference that occur on the copy hologram cannot be eliminated.

The present invention has been made in view of the above, and it is an object of the present invention to provide a hologram copying method that overcomes the drawbacks of conventional copying methods and can obtain excellent copy holograms with high precision.

This article summarizes a method for copying holograms that is characterized by:

The present invention will be explained below with reference to the drawings.

The present inventor found that the interference of uniform thickness and interference of equal oblique angle increases as the reflected light increases, and therefore as the transmitted light decreases, in the optical system shown in Fig. 2, the three layers are transmitted without reflection. Focusing on the formula expressing the amount of transmitted light, that is, the transmittance, we investigated a method for preventing interference fringes by increasing tp and ts.

From the above formula, it can be seen that the more the town and n differ, and the more n and nl differ, the more tP + tIB decreases;
The more tp, tI! It can be seen that I increases.

Therefore, in order to eliminate the aforementioned undesirable interference fringes, it is better to bring the refractive index n of the gap 4 closer to the refractive index of the master hologram photosensitive material 1b and the refractive index of the photosensitive material 2a of the photosensitive substrate. I understand.

As a means for achieving this, the present inventor considered intervening in the gap 4 a substance having a refractive index close to the refractive index n2 of the refractive heavy electric material of the photosensitive material tb of the master hologram and the refractive index n2 of the photosensitive material 2a of the photosensitive substrate.

The photosensitive materials used for the master hologram and the photosensitive substrate are generally silver salts, photoresists, photochromic materials, thermoplastics, magneto-optical materials, etc.9 The present inventor has discovered that there is an intervening material between these photosensitive materials. They discovered gelatin colloid as a substance that has the effect of erasing interference fringes. In particular, the present invention exhibits excellent effects in copying combinations in which silver salt is used as the photosensitive material for the master hologram and photoresist is used as the photosensitive material for the photosensitive substrate. The materials for the substrates that hold these photosensitive materials include plastic films such as polyester, PVC, polycarbonate, and acrylic, as well as materials that have properties sufficient to hold the photosensitive materials, such as plastic plates, glass plates, and metal plates. If so, nine can be used in the present invention. However, the substrate for the master hologram must have light transparency.

The method according to the present invention will be specifically explained below.

Melt the gelatin by heating it (generally above 40°C).

Make gelatin colloid of about 0.5 to 50%.

In particular, 10 to 40 yen is optimal.

Next, the gelatin colloid is applied in the form of a sol to at least one of the master porogram or the photosensitive substrate.

Application methods include dip method, extrusion method,
Known methods such as roll coating, knife coating, Myaba coating, spinner coating, and wheel coating can be used, and the thickness of the 111 cloth is usually 1 μm to 1000 μm.
It is sufficient if the coating thickness is m.

Next, the master hologram and photosensitive substrate are placed in a J with the gelatin colloid layer in between while the gelatin colloid is in a sol state.
ll! Match i.

The laminating method uses nip rolls.

A thousand press method etc. are used.

When using the nip roll method, see Figure 3.

It is also possible to coat the gelatin colloid I11 while pasting the master hologram 9 and the photosensitive substrate 1o together with the nip rolls 12.

When using the flat press method, gelatin colloid 11 is poured onto a photosensitive substrate 10 in FIG. 4.

It is also possible to press the master hologram 9 from above with a flat press 13 and apply the paste.

In addition, it is also possible to heat the gelatin colloid layer, which has been gelled once after application, to solify it again for pasting.

After pasting the master hologram and the photosensitive substrate with the gelatin colloid layer as described above, the gelatin colloid layer is cooled, for example,
After gelatinizing the gelatin colloid layer, it is exposed to copying light 3 in the usual manner as shown in FIG. 5, and the master hologram 9 is copied onto the photosensitive material 10a of the photosensitive substrate 0.

Next, the gelatin colloid 11 and the photosensitive substrate 1o are separated, and the photosensitive substrate 1o is developed to obtain a copy hologram.

Suitable light sources for copying include a He-Na laser, an Ar laser, a Jle-Cd laser, a Kr laser, or a mercury lamp.

Development of the photosensitive substrate is carried out by a normal development method for the photosensitive substrate used.

Applications of the present invention extend to those based on various principles such as 7-Renel holograms, Fourier transform holograms, Fraunho 7-ar holograms, and image holograms, rainbow holograms, porographic stereograms, Lippmann holograms, and holograms using these principles. This includes graphic diffraction gratings, etc.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

EXAMPLE An example is shown in which a hologram photographed on a silver salt film was copied onto a photoresist plate using the method of the present invention.

First, according to a known method, a +25 mw He-Ne laser was used to remove Agfagewald 10'E75 silver salt film A (4
Shoot a rainbow hologram on the AGE 7
It was developed for 10 minutes using Atmar, a developer manufactured by Agepart.

Next, by the method shown in FIG. 3, the silver salt film on which the hologram was photographed was attached to a photoresist dry plate at the same time as the gelatin colloid was applied.

The photoresist drying plate was 4 x 5 inches and was placed on a 211-thick glass plate using Photoresist P, AZ1350J from Gigray.
Spinner coat the stock solution at 2000jF, 7'll
, which was bre-baked at 90°C for 30 minutes. Gelatin colloid is from Nitta Seratin.

A 20% solution of Collotype 41 in 60°C water was used. The coating thickness was approximately 6.1 +u.

Next, in the method shown in FIG. 5, an Ar+ laser beam was irradiated from the silver halide film side at an incident angle of the Bragg angle (40° in this case). After exposure, the silver salt film and gelatin layer were peeled off from the photoresist dry plate, and a
The photo was developed for 5 minutes.

Obtained a hologram similar to the master hologram.

As explained above, according to the hologram copying method according to the present invention, by interposing gelatin colloid between the master hologram and the photosensitive substrate, the gap between the master hologram and the photosensitive substrate is created. Equal thickness interference and equal inclination angle interference do not occur during copying, making it possible to provide a copy hologram with unprecedentedly high precision.

Furthermore, since the gelatin colloid is in the form of a gel, there is no need to take any special means for retaining the liquid, and the operation is easier, compared to when a liquid is used as the substance interposed in the gelatin.

In addition, according to the method of the present invention, when recording a hologram on a photoresist with low sensitivity, the hologram is once recorded on a sensitive silver halide film, and the p=raw image is faithfully reproduced by 7.
Since the method of copying to the photoresist can be performed, the retention time and quality are improved by 9 minutes. The present invention is significant because it is a hologram relief type formed on photoresist and can be used as an original plate for mass duplication using a heat press method or the like.

[Brief explanation of drawings]

The drawings show a method according to the present invention and a conventional method, and FIG. 1 is a longitudinal cross-sectional view of a conventional copying method. FIG. 2 is a vertical sectional view showing the mechanism by which interference occurs in the conventional copying method, FIGS. 3 and 4 are longitudinal sectional views of the bonding method of the present invention, and FIG. FIG. 3 is a longitudinal cross-sectional view of the method. 1・---1--- Master Hologram 1 @ ---
- Substrate t b of # - Photosensitive material '2 of g - Photosensitive substrate 2a - Photosensitive material 2b of # - Substrate of # 3. --- 1 --- Copy light 4 --- Gap 5 --- 0th order light (non-reflected light) 6. --- 0th order light (repeatedly reflected light twice)? ------
--- 1st-order light (non-reflected light) 8-・----i-order light (repeatedly reflected light - times)! -------- Master hologram 9 m--------- Master hologram substrate 9
b ------I photosensitive material 10-----1 photosensitive substrate 10m-----1 photosensitive material 10b-----# substrate Seitomi--gelatin colloid 12------・-Two rolls 18------・-Flat press

Claims (1)

[Claims] (1) A method for copying a hologram, which comprises exposing a hologram to light by interposing a gelatin colloid between the hologram and a photosensitive substrate.- (2) A hologram is recorded on a silver salt photosensitive material. A method for copying a hologram according to claim 1, wherein the photosensitive material of the photosensitive substrate is a 7-photoresist.