JPH01112277A - Production of hologram - Google Patents

Abstract

PURPOSE:To obtain a volume phase type hologram which has excellent transparency and has no cracks by previously subjecting a specific photosensitive layer to a swelling treatment by a solvent and crosslinking treatment, then subjecting said layer to exposing and development processing. CONSTITUTION:The photosensitive material layer is subjected to a crosslinking treatment operation by incoherent light which is called preexposing in order to develop the resistance to the ensuing development processing prior to hologram exposing by coherent light. The degree of the preexposing largely affects the transparency and resolution of the hologram. The photosensitive material layer composed essentially of a vinyl carbazole polymer is previously put into the wetting state by the solvent and is then crosslinked by photoirradiation in such a manner, by which the cracks to be generated in the ensuing development processing stage are eliminated. The volume phase type hologram having the excellent transparency is thereby body.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a hologram, and more specifically,
The present invention relates to an improved method for manufacturing a volume phase hologram using a vinyl carbazole polymer as a recording layer.

(Prior art) Holography is a method in which a light wave with good coherence, such as a laser, is irradiated onto an object, the amplitude and phase of which are modulated according to the shape of the object, and the reflected or transmitted light waves are applied to a sensitive material layer. It is a technology that receives and records light and reproduces the optical image of the object recorded by the irradiated light on the resulting hologram. For example,
A stereoscopic optical image can be observed on a flat film.

With the progress of research on holography, the requirements for the sensitive material have now become quite clear. Many materials are known as sensitive materials that can be used in holography, including bleached silver salts, photoresists, thermoplastics, dichromate gelatin, inorganic glass materials, and ferroelectric materials. It is being further researched.

In addition, with the advancement of holography technology, it is becoming possible to form holograms that can withstand practical use, and holograms are being used in a variety of ways, such as enjoying the image itself and using it to decorate various items. holograms are expanding, and correspondingly various forms are being required for holograms.

Vinyl carbazole polymers are known as practical holographic photosensitive materials that meet the above requirements.

(Problems to be Solved by the Invention) When a hologram is formed using a vinylcarbazole-based polymer as a sensitive material, a volume-phase hologram with excellent moisture resistance, light resistance, transparency, and diffraction efficiency can be obtained. For example, the sensitive material layer is 6
If the thickness is .mu.m or more, there is a problem that many cracks will occur on the surface during a later phenomenon, making it impossible to obtain a highly transparent hologram.

For example, when a dichromate gelatin-based photosensitive material is used, a hologram with excellent transparency and no cracks can be obtained by applying a known hardening process even if the photosensitive material layer is thick. Even if a film formation treatment was used, the above problem could not be solved when a vinyl carbazole polymer was used.

Therefore, an object of the present invention is to provide a volume phase type hologram that does not generate cracks and has high transparency even when a relatively thick photosensitive material layer made of a vinyl carbazole polymer is used.

(Means for solving problems) The above object is achieved by the present invention as described below.

That is, in the present invention, a sensitive material layer mainly composed of a vinyl carbazole polymer is subjected to swelling treatment with a solvent,
This hologram manufacturing method is characterized by crosslinking in a swollen state, followed by exposure and development.

(Function) Before hologram exposure with coherent light, the sensitive material layer is swollen with a solvent in advance, and the sensitive material layer is preferably crosslinked by light irradiation, thereby eliminating cracks that may occur during the subsequent processing steps. A volume phase type hologram with excellent transparency is provided.

That is, before the hologram is exposed to coherent light, a crosslinking process is performed using incoherent light, which is called pre-exposure, in order to develop resistance to subsequent development processing. It is known that the degree of pre-exposure is one of the important factors that greatly influences the transparency and resolution of the hologram.

How crosslinking caused by incoherent light is affected by subsequent development processing will be explained.

Generally, crosslinking a polymer increases its rigidity (so-called hardening), but at the same time it loses its flexibility.

As a result, it is unable to respond to external stress, elongation, and other deformations, causing it to break, that is, to become brittle.

This is because crosslinking suppresses the free movement of polymer chains,
This means that it is no longer able to absorb the strain energy associated with deformation.

When a polymer that has lost its degree of freedom is swollen with a solvent, the polymer attempts to balance its energy balance by breaking due to solvation by solvent molecules.

It is obvious that if a solid is crosslinked and then subjected to a development process of swelling and shrinking after exposure, destruction will occur, as can be easily inferred from the general phenomenon described above.

To explain in more detail, after the pre-exposure, in consideration of later swelling and shrinkage, pre-exposure crosslinking is performed in a swollen state to the extent that swelling is desired, and this is then dried. Then, in the solid state at this time, the polymer chains can preserve the arrangement of the polymer chains, which has a comparative degree of freedom in the dissolved state. Even if a development treatment is applied, the result is only a transition between two states: swelling (swelling), which is the configuration of polymer chains crosslinked during pre-exposure, and contraction (contraction), which is a solid configuration.

Naturally, the main exposure using coherent light must be performed on a solid state. This is a completely opposite idea to pre-exposure. This is because destruction is caused by crosslinking in a solid and causing it to swell.

(Preferred Embodiments) The present invention will be described in more detail below by citing preferred embodiments.

In the present invention, the main polymer of the hologram sensitive material is any polymer selected from polyvinylcarbazole, its alkyl-substituted derivatives, or its halogen-substituted derivatives, and specifically, for example, polyvinylcarbazole, 3-chloro vinyl carbazole polymer,
Examples include 3-bromvinylcarbazole polymer, 3-iodovinylcarbazole polymer, 3-methylvinylcarbazole polymer, 3-ethylvinylcarbazole polymer, chlorinated polyvinylcarbazole, brominated polyvinylcarbazole, and the like.

Among them, unsubstituted polyvinylcarbazole is practically the most suitable because it is easy to use and the performance of the resulting hologram is particularly excellent.

The above-mentioned vinyl carbazole polymer may be copolymerized with other monomers as necessary, for example, in order to control properties such as strength and flexibility when formed into a film. Examples of other monomers that can be used for such purposes include, in addition to divinyl carbazoles, vinyl esters such as vinyl acetate, esters of acrylic acid and methacrylic acid, styrene and styrene derivatives, and N-vinylpyrrolidone. , N-vinyl phthalimide, etc., which can be copolymerized by a radical polymerization copolymerization method. Further, other polymers such as polystyrene, styrene-butadiene copolymer, styrene-hydrogenated butadiene copolymer, etc. can also be blended to the extent that a hologram image can be recorded. Incidentally, the addition ratio of these materials is selected so as to obtain desired characteristics.

In the present invention, the polymer component forming the main body of the above-mentioned sensitive material must be activated in advance to radiation by an iodine compound.

Such iodine compounds coexist in polymer components and constitute a sensitive material that has sufficient sensitivity even in the visible wavelength range. Examples include iodine compounds whose main components are iodoethane, tetraiodoethane, pentaiodoethane, hexaiodoethane, and the like.

The hologram sensitive material used in the present invention is obtained by dissolving the above-mentioned polymer and iodine compound in a suitable solvent in a predetermined ratio or making a dispersion liquid, and then forming a coating film on a support such as glass or a transparent resin film. Or it can be made into a film by itself.

When using a support, it is desirable that the support has enough strength to support the hologram film. Furthermore, any material can be used as long as it satisfies these characteristics, and examples include materials such as resin, metal, glass, and ceramic.

In the present invention, before exposing the holographic sensitive material as described above to coherent light, the sensitive material layer is swollen with a solvent and then crosslinked. The solvent used is a solvent that dissolves or swells the vinyl carbazole polymer, such as benzene, toluene, xylene, ethylbenzene, n-pyropylbenzene, cumene, phenol, cresol, chlorobenzene, dichlorobenzene, nitrobenzene, Benzyl alcohol, pencil chloride, benzyl bromide, methylnaphthalene, α-chlornaphthalene, and other benzene and naphthalene derivatives; dichloromethane, chloroform, trichlene, dichloroethane, proform, and other alkyl halogen substitutes; acetone, cyclohexanone, and other ketones; and other amines. and amides.

The solvent mentioned above is a good solvent for vinyl carbazole polymers, but its solubility and swelling properties can be adjusted by mixing a poor solvent with it. Examples of the poor solvent include alkanes such as n-pentane, n-hexane, n-hebutane, low octane, isooctane, and cyclohexane;
Cycloalkanes, alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, diethyl ether, methyl ethyl ether, diisopropyl ether, etc. Examples include ethers.

The swelling treatment of the sensitive material layer can be carried out by any method such as dipping in a solvent, spraying the solvent, or absorbing the solvent in a solvent gas atmosphere.The degree of swelling can be adjusted by adjusting the amount of solvent used,
temperature, time, combinations of good and poor solvents and their ratios,
This can be easily carried out by utilizing differences in factors such as solubility, boiling point, vapor pressure, and freezing point of solvents.

In the present invention, the degree of swelling is preferably determined based on the degree of swelling performed in the subsequent development step. For example, the degree of swelling in the development step is determined by
Since it is 120% or more in Publication No. 43, 120% or more is also common in the present invention.

The crosslinking in the swollen state can be carried out by irradiation with general light such as a fluorescent lamp, incandescent lamp, xenon lamp, halogen lamp, or mercury lamp.

After crosslinking, the absorbed solvent is removed by evaporation, etc., and an interference pattern is exposed to a coherent laser beam of two beams: an object beam and a reference beam at an appropriate wavelength within the sensitive wavelength range of the sensitive material. Furthermore, a volume phase type hologram with high transparency, high resolution, and high diffraction efficiency can be formed by a method that includes a development process that utilizes swelling and shrinkage phenomena caused by a solvent.

(Effects) By pre-swelling and crosslinking the photosensitive material layer mainly composed of vinylcarbazole polymer with a solvent, and then exposing and developing it, even relatively thick photosensitive material layers can be made transparent. A volume phase type hologram with excellent properties and no cracks is provided.

(Example) The present invention will be explained in more detail with reference to Examples below.

Example 1 On a 1.1 mm thick blue plate glass-42 as a base material,
In a dark place, apply a solution of 2.5 g of poly(N-vinylcarbazole) and 0.2 g of carbon tetrachloride dissolved in 30 g of monochlorobenzene using a spinner (Mikasas Viner, II (-2), and then dry. A photosensitive material layer for forming a hologram with a thickness of about 11 μm was obtained.

Next, this base material was mixed with methanol/toluene = 10 at 25°C.
The sample was immersed in a mixed solvent of 1/90% and swollen to 150%, taken out, and irradiated with light using a 40% fluorescent lamp as a pre-exposure for crosslinking. After drying this to its original volume, use a static laser (514,5 nm) on this sensitive material layer, set an offset angle of 70°, and a light intensity ratio of 1:1 (the sum of the light intensities of both beams is the incident An image corresponding to the desired object was recorded according to Denishuk's method under conditions of 3 mW/crr.

After exposure, the photosensitive material layer was sequentially processed in the following steps (+) to (3) to obtain a hologram of the present invention.

(1) After immersion in acetone at 20℃ for 2 minutes, (2) at 35℃
After immersion in xylene for 3 minutes, (3) immersion in n-heptane at 25°C for 3 minutes, and then drying.

The obtained hologram had a diffraction efficiency of 75% for light with a wavelength of 490 nm, no cracks were observed on the surface, and a light transmittance of 92% (600 nm) in the area not exposed to the laser.
Met.

Comparative Example 1 The same sensitive material layer used in Example 1 was directly pre-exposed in a dry state, and then subjected to the same development process to obtain a hologram of Comparative Example.

This hologram has a reflection diffraction efficiency of 75 at 490 nm.
%, but countless cracks occurred on the surface.
The light transmittance of the laser-unexposed area also decreased to 57%.

Patent applicant Canon Co., Ltd.] 1 Agent Patent attorney Yoshi 1) Katsuhiro, --! 7<・self T
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Claims (1)

[Claims] (1) A method for producing a hologram, which comprises swelling a sensitive material layer mainly composed of a vinylcarbazole polymer with a solvent, crosslinking it in the swollen state, and then exposing and developing it.