JPS60117279A - Formation of hologram - Google Patents

Abstract

PURPOSE:To obtain a Bragg angle shift hologram with good hologram by applying resist which is sensitive to resist exposure, using wavelength suitable for the sensitivity a photosensitive material, and adjusting the light quantity ratio of the 0-order and 1-order light beams from a master hologram by a lambda/2 plate. CONSTITUTION:Silver salt, gelatin dichromate, etc., which are not sensitive to light for resist exposure are used as the photosensitive material 11 on a substrate 10 of glass, etc. The photosensitive material is coated with resist 12 by a spin coating method, and exposed to light 13 with wavelength sensitive to the resist 12 for hologram formation to take a copy of a Bragg angle shift hologram from the master hologram 14. In this case, copy light 15 has such as wavelength that the photosensitive material 11 is sensitive. The lambda/2 plate 16 is interposed in the copy light 15 to adjust the light quantity ratio of the 0-order light and 1-order light to 1 in S polarization reproduction, and then a copy is taken. Consequently, the Bragg angle shift hologram with high contrast is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for creating a hologram used in a hologram scanner or the like.

Background of the Technology To save labor, barcode reading devices have come into use that read the barcode printed on the exterior of a product and input it into a computer. Since a hologram scanner that uses a hologram as both a light converging element and a light deflection element to converge and scan the Raded light is suitable for this device, this barcode reading device uses a hologram scanner as its light scanning section. . This optical scanning section forms a hologram on a hologram recording medium 3 by interfering plane wave light 1 and spherical wave light 2 as shown in FIG.
A method is used in which the completed hologram is used to irradiate plane wave light 4 from a direction opposite to that when the hologram was created to obtain scanning light.

However, since the hologram manufacturing process involves chemical processing such as development of the recording medium, the recording medium 3 may swell or contract.
There are times when the angle of inclination of the recorded interference fringes changes and a desired reproduction method cannot achieve high first use efficiency. Therefore, it is possible to freely control the incident angle (Bragg angle) of the reproduction light to maximize efficiency by changing only the inclination angle of the interference fringes while the desired aberration is produced (in some cases, no aberration is produced). It has become necessary.

Prior Art and Problems As a conventional technology for controlling the Bragg angle, there is a Bragg angle shift hologram copying method. As shown in Fig. 2, coherent plane wave light 6 is irradiated at an incident angle θ to a master hologram 5 on which a desired interference fringe pattern has been created by direct exposure, and the transmitted light and diffracted light are applied to a recording medium 7 at an inclination angle. This method copies exactly the same interference fringe pattern by changing only the angle θ, and by changing θ, the angle of inclination can be freely controlled. However, this method has disadvantages in that the amount of zero-order light (transmitted light) is larger than the amount of first-order light (diffracted light), resulting in poor contrast and low first-use efficiency during reproduction.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks of the conventional art, it is an object of the present invention to provide a hologram production method capable of obtaining a Bragg angle shift hologram with good contrast.

According to the present invention, a resist that is sensitive to the light for resist exposure is applied on a photosensitive material that is not sensitive to the light for resist exposure, and a master hologram is created on the resist. , provides a hologram production method characterized in that copying is performed using light of a wavelength suitable for the sensitivity of the photosensitive material and adjusting the ratio of the amount of 0th order light and the amount of first order light from the master hologram with a λ/2 plate. This is achieved by

Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a diagram for explaining the hologram production method according to the present invention, and a-g are cross-sectional views for explaining the process. In the figure, 1o is a substrate, 11 is a photosensitive material, 12
13 is a resist, 13 is a resist exposure light, 14 is a master hologram, 15 is a copy light, 16 is a λ/2 plate, 17
show Bragg angle shift holograms, respectively.

To explain the method of the present invention with reference to FIG. 3, first, as shown in FIG. 3A, a film of photosensitive material 11 is formed on a substrate 10 such as glass. As this photosensitive material, one that is not sensitive to light for resist fogging is used.

Generally, a laser in the ultraviolet region is used for resist exposure, and therefore, silver salt monodichromate gelatin, which is insensitive to the ultraviolet region, is suitable as the photosensitive material. Next, as shown in figure b, the photosensitive material 11
A resist 12 is spin-coded on top of the resist 12. Next, as shown in Figure 0, light 13 of a wavelength (mainly in the ultraviolet region) that is sensitive to the resist 12
Exposure for creating holograms is performed. Next, by developing the resist as shown in Figure d, a master hologram 14 is obtained.

Next, the Bragg angle shift hologram is copied from the master hologram 14 as shown in Figure e. At this time, copy light 1
5 uses a wavelength to which the photosensitive material 11 is sensitive.

Further, once the copy incident angle to which the Bragg angle is to be shifted is determined, the copy conditions are determined.

Generally, when copying, the best ratio between the 0th order light amount and the 1st order light amount is 1, and a copy hologram with good contrast can be obtained, but in reality it is smaller or larger than 1.

Therefore, the present invention utilizes the characteristics unique to the resist of the master hologram. Figure 4 shows the relationship between the polarization component of the copy light and the 0th-order light amount/1st-order light amount at a certain incident angle.The figure shows that the diffraction efficiency of the resist largely depends on the polarization direction of the incident light. , the efficiency is highest for S-polarized light and the lowest for P-polarized light. Taking advantage of this property, the λ/2 plate 16 is inserted into the copy light 15 in FIG. As shown at point A in Figure 4, the 0th order light intensity/
Copying is performed after adjusting the primary light amount to 1.

Next, as shown in figure f, the master hologram 14 is removed with a solvent such as acetone, and then the photosensitive material 11 is developed and fixed, thereby completing the Bragg angle shift hologram 17 as shown in figure g.

According to this embodiment, when copying from a master hologram, if the ratio of 0th order light amount/1st order light amount is smaller than 1, a copy hologram with high contrast can always be obtained by rotating the λ/2 plate. Therefore, it is possible to shift the Bragg angle within this range, and since the master hologram is created by applying a resist to the copying dry plate, it is also excellent in terms of close copying.

FIG. 5 is a diagram for explaining another embodiment. In the figure, 10 indicates a substrate, 11 indicates a photosensitive material, 12 indicates a resist, and 20 indicates a filter.

This embodiment differs from the previous embodiment in that, in the step shown in FIG. 3, a filter 20 (which may be a single layer) is deposited between the photosensitive material 11 and the resist 12, as shown in FIG. be. The role of this filter 20 is to loosen the restrictions of the photosensitive material 11. This filter is shown in Figure 3e.
In the Fl exposure, no light is allowed to pass through the photosensitive material 11, and in the exposure shown in FIG. 3e during copying, the light is allowed to pass through the photosensitive material 11. For example, if the photosensitive material 11 is made of silver salt or other material sensitive to red, a red filter (a filter that only passes red) may be used as the filter 20. Note that since this filter may be a single layer, it does not generate high heat during vapor deposition and does not damage the photosensitive material 11.

According to this embodiment, by including the filter 20, it is possible to use a photosensitive material having sensitivity not only in the infrared region but also in the ultraviolet region. Hiko: Also, in order to match the polarization planes of the 0th-order light and the 1st-order light from the master hologram during copying, a λ/2 plate with a rotation direction opposite to the direction of rotation of the λ/2 plate when the copying light is incident is used as a photosensitive material. It is also effective to deposit it between the resist and the resist.

Effects of the Invention As explained in detail above, the method for producing a hologram according to the present invention involves stacking two layers of photosensitive materials and resists that are sensitive to different types of light, creating a master hologram on the resist, and then exposing the master hologram to another layer. By copying it onto a material, a Bragg angle shift hologram with high contrast can be obtained, which is a great effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a hologram, FIG. 2 is a diagram for explaining the conventional Bragg angle shift hologram copying method, FIG. 3 is a diagram for explaining the hologram creation method according to the present invention, and FIG. This figure shows the dependence of the diffraction efficiency of the master hologram on the polarization direction, and FIG. 5 is a diagram for explaining another embodiment. In the drawings, 10 is a substrate, 11 is a photosensitive material, 12 is a resist, 14 is a master hologram, 15 is a copy light,
16 is a λ/2 plate, 17 is a Bragg angle shift hologram,
20 each indicates a filter. Patent Applicant Fujitsu Limited Patent Application Agent Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate 1) Yukio Patent Attorney Akira Yamaguchi 1st Endurance 20th 4th 4th 30th (f) 40th

Claims (1)

[Claims] 1. A resist that is sensitive to the light for resist exposure is applied on a photosensitive material that is not sensitive to the light for resist exposure, and a master hologram is created on the resist, and then the photosensitive material is A hologram creation method characterized by using light of a wavelength suitable for sensitivity and copying by adjusting the ratio of the amount of zero-order light and the amount of first-order light from a master hologram with a λ/2 plate. 2. The method for producing a hologram according to claim 1, characterized in that a filter is deposited between the photosensitive material and the resist to loosen restrictions on the sensitivity of the photosensitive material.