JPS60198576A - Production for hologram - Google Patents

Abstract

PURPOSE:To enhance the diffraction effect and reduce aberrations of a diffracted light by immersing a hologram, which is already subjected to development, in a solvent which is a bad solvent to a polyvinyl carbazole polymer and in which a resin is dissolved and removing the solvent thereafter. CONSTITUTION:A hologram recording photosensitive film containing a polymer consisting of a polyvinyl carbazole or its alkyl or halogen substitution derivative and a radical generator is exposed to radiation to crosslink this polymer selectively. The photosensitive film is developed in the second solvent after it is swollen by the first solvent, and the hologram where an interference pattern of luster is recorded as variation of the refractive index is obtained. Thereafter, this hologram is immersed in the third solvent which is a bad solvent to said polymer and in which a resin is dissolved, and the hologram is impregnated with the resin, and the solvent is eliminated by evaporation, thus obtaining the focal hologram.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a hologram, particularly a method for manufacturing a phase hologram using a polyvinylcarbazole photosensitizer.

Technical Background A hologram records the interference fringes of two coherent light waves, an object wave and a reference wave, from which the original wavefront can be reconstructed so that the object appears three-dimensional. Known materials for recording holograms include silver halide photography, dichromate gelatin, thermoplastics, and photopolymers, but various requirements such as high diffraction efficiency, high resolution, manufacturability, and heat-and-moisture resistance have been used. There is nothing that satisfies all of the above. Silver halide photography, which is most commonly used, is sensitive to humidity and has low diffraction efficiency because it is of an amplitude type. Dichromate gelatin, which has high diffraction efficiency and high resolution, also has problems in that it is sensitive to humidity and has poor productivity.

As a result of studying new materials to replace these conventional recording materials, we found that polyvinylcarbazole polymers have excellent heat and humidity resistance, and because they are phase-shaped, they provide high diffraction efficiency and are easy to develop. Something was discovered.

Prior Art and Problems Hologram recording photosensitive films mainly made of polyvinylcarbazole polymers contain iodine compounds such as carbon tetraiodide.
(see JP-A-54-101343, Mei. 111l1), or a cyclic cis-'αα fuzyl such as camphorquinone contains a radical generator such as a nyl compound (see Japanese Patent Application No. 57-5695), and Exposure to the interference wave of the reference light causes a radical reaction to crosslink the polyvinylcarbazole polymer with an intensity corresponding to the interference pattern.

It is treated with a first solvent such as toluene or xylene to swell the photosensitive film (at this time, a solvent that does not dissolve the polyvinylcarbazole polymer (including its crosslinked product) in a short period of time is used); Then a second solution such as n-hexane
The majority of the first solvent and the radical generator and )? A portion of the uncrosslinked portion of the IJ vinyl carbazole polymer is eluted into the second solvent. In this way, a pattern consisting of crosslinked and uncrosslinked parts of the polyvinylcarbazole polymer is formed in response to the interference waves, and since the R-turn is accompanied by a change in the refractive index of light, it functions as a hologram.

However, the present inventors have discovered that this polyvinylcarbazole-based hologram has a serious problem due to the developing method. In other words, the hologram obtained as described above has low diffraction efficiency when the reproduction light is incident at the same incident angle (θ0) as the t irradiation during exposure, and when the incident angle is slightly shifted (incident angle θB). The diffraction efficiency is maximized (shift of Bragg angle). If the incident angle of the reproduction light deviates from 00, the greater the deviation, the more aberrations will occur in the diffracted light and the image will become blurred. Therefore, when a Bragg angle shift occurs, a problem arises in that high diffraction efficiency cannot be obtained at θ0, while aberrations occur in the diffracted light at θB, where high diffraction efficiency can be obtained. This Bragg angle shift essentially occurs in vinyl carbazole-based Borodalum recording materials, but the degree of Bragg angle shift varies depending on the type of radical generator.

In the case of cyclic cis-α-dicarbonyl compounds, the shift is large, and the problem is that much more serious.

Purpose of the Invention In view of the problems of the prior art as described above, the purpose of the present invention is to
The object of the present invention is to obtain a hologram with high diffraction efficiency and small aberration of diffracted light by reducing the shift of the Bragg angle due to development processing in a polyvinylcarbazole-based hologram.

Structure of the Invention In order to achieve the above object, the present invention immerses a hologram that has been subjected to the normal development process as described above in a third solvent. As the third solvent, a poor solvent for the polyvinyl carbazole polymer in which the resin is dissolved is used, and after the resin is impregnated into the hologram, the solvent is removed by evaporation.

In the case of a specific clear phase hologram having the structure of the invention, the Bragg angle θB is determined by the spatial frequency f of the interference fringes, the vertical inclination angle α of the interference fringes, and the refractive index n of the recording medium. The reasons why the Bragg angle shifts due to development are: (1) the film thickness increases due to swelling, and the inclination angle α of the interference fringes changes; It is thought that the density of the recording medium decreases due to the elution of the system polymer, and the refractive index decreases (the refractive index of the crosslinked portion and the uncrosslinked portion, and the difference in the refractive index changes).Interference fringes Since the decrease in the inclination angle and the decrease in the refractive index shift the Bragg angle in the same direction, they do not cancel each other out but act synergistically, resulting in a significant shift in the Bragg angle.

The present inventors conducted studies to return the Bragg angle, which has deviated from the design angle, to the design angle side, and as a result, discovered the following fact.

(1) If the hologram obtained by the above phenomenon is immersed in a poor solvent for the vinylcarpazole polymer and then the solvent is evaporated, the Bragg angle may return to a slight value. Such an effect will not be observed if the solvent's ability to dissolve the polyvinylcarbazole polymer is too small; if the solvent's ability to dissolve the polyvinylcarbazole polymer is too large, the refractive index difference in the interference pattern disappears and the hologram recording disappears. Therefore, the amount of solvent within the range that has the ability to dissolve polyvinylcarbazole polymers has the effect of restoring the Bragg angle. Preferred solvents include methyl isopropyl ketone,
Examples include acetonitrile and a mixed solution of methyl acetate and ethanol.

(2) When the hologram is immersed in an organic solvent in which resin has been dissolved and then pulled up and the solvent is evaporated, the resin is impregnated into the bulky (low density) hologram (polyvinyl carbazole polymer film). , resulting in a slightly higher refractive index.

Therefore, by combining (1) and (2), a third solvent was created by dissolving the resin in a solvent that has the effect of restoring the Bragg angle, and the hologram obtained by the conventional method was immersed in this solvent. When evaporated, a clear effect of restoring the Bragg angle was observed. The resin used for the third solvent may be any resin as long as it is soluble in the solvent used, such as cellulose,
Vinyl-based, urea-based, phenol-based, styrene-based, epoxy-based, acrylic-based, carbonate-based resins, etc. can be used, and it is generally preferable that the number of molecular fragments is on the order of tens of thousands to hundreds of thousands. Not limited.

It has also been found that by repeating the above-described dipping (impregnation) treatment, the return of the Bragg angle can be increased cumulatively.

Examples of polyvinylcarbazole or its alkyl-substituted or halogen-substituted conductor which form the main body of the hologram recording material in the present invention include polyvinylcarbazole, 3-chlorovinylcarbazole polymer, 3-f
romvinylcarbazole polymer, 3-iodovinylcarbazole polymer, 3-methylvinylcarbazole polymer, 3-ethylvinylcarbazole polymer, chlorinated polyvinylcarbazole, frominated i? Examples include ribinylcarbazole.

Examples of iodine compounds that can be used as radical generators include carbon tetraiodide, iodoform, ethylene tetraiodide, triiodoethane, tetraiodoethane, pentayodoethane, and hexaiodoethane, and cyclic cis-α-radicals? For example, 2°3-? Lunandione, 2.2, 5.5
-tetramethyltetrahydro-3,4-furandione,
Paravic acid (imidazoletrione), indole-2
,3-dione (isatin, 1,1,4t4-tetramethyltetralin-2,3-dione, 3-methyl-1,2
-cyclopentanedione, 2,3-dioxo-5,6-
Jetoxy-5,6-dicyatsupyrazine, 1,4,5.
6-ketonehydro5゜6-thioxo2.3-pyrazinecal? Ximide and others can be mentioned.

Examples of the first solvent used in the present invention include benzene, toluene, xylene, ethylbenzene, n-pyropylbenzene, cumene, phenol, cresol, chlorobenzene, dichlorobenzene, nitrobenzene, benzyl alcohol, benzyl chloride, Benzene and naphthalene derivatives such as benzyl bromide, α-methylnaphthalene and α-chlornaphthalene; alkylhalodef substitutes such as dichloromethane, chloroform, trichlene, dichloroethane and chloroform; ketones such as acetone and cyclohexanone; other amines and amides There is. This includes those for which the processing temperature must be set appropriately.

Examples of the second solvent used in the present invention include alkanes such as n-pentane, n-hexane, n-hexane, n-octane, isooctane, and cyclohexane, cycloalkanes, methyl alcohol, ethyl alcohol, n-7'
Examples include alcohols such as lobil alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, and isoamyl alcohol, and ethers such as diethyl ether, methyl ethyl ether, noisoglobil ether, and the like.

In the present invention, exposure and development using the first and second solvents are the same as conventionally known techniques.

Fruit of invention/lf! Creation of i-row hologram After mixing and dissolving the materials shown in Table 1, a filtered coating liquid (photosensitive agent) was applied onto a glass substrate to a thickness of 1 μm using a spin coater.

China Anan Kogyo Co., Ltd. Novicol 2108P Umbrella* C1b
Next, as shown in Fig. 1, the glass substrate coated with photosensitive agent 1 as described above was exposed to an Ice (Je) laser beam with a spherical wave incident angle of 50° and a reference wave incident angle of 0°. Master hologram 2ff of the created silver halide photograph: Faced to each other, Ar laser beam was used to perform Bragg angle reproduction copying.The incident (output) angle α0 of the 0th order light 1. of the Bragg angle reproduction copy was 11°.
, the output angle αFi of the primary optical beam is 51°. In the figure, 3 is a collimator.

Table 2 shows the master and exposure conditions.

Margin Table-2 Master and Exposure Conditions Next, toluene vapor is condensed on the surface of the exposed polyvinyl carbazole film. About 200 to 400 inches of ribinylcarpasol membrane per membrane (100% before swelling)
The sample was expanded in a medium (described as ) and then developed by immersing it in n-pentane. The polyvinyl carbazole film thickness after development was about 150 to 250% of the initial thickness (before swelling).

The hologram thus obtained is illuminated with Ar Radhe light (wavelength 48
8 nm) was irradiated with an energy of 500 tnJz&2 while changing the incident angle, and the diffraction efficiency was measured. The diffraction efficiency is the 2-cent ratio of the intensity of the outgoing (diffracted) light at the outgoing angle O0 to the intensity of the incident light. The incident angle at which the diffraction efficiency was maximized was defined as the Bragg angle.

Zorag angle restoration process Referring to Figure 2, hologram 1 created as above
1 was held in a jig 12 and immersed in the treatment liquid 13 (FIG. 2 (a)) to impregnate the resin, then slowly pulled up (FIG. 2←)) and dried in the atmosphere at room temperature. The treatment solution was made from methyl acetate, ethanol, and acrylic resin, and experiments were conducted with different composition ratios. Table 3 shows the composition of the treatment liquid and the state of the hologram after treatment. Regarding the composition of the processing solution, the concentration of ethanol was changed in A-E, and the concentration of ethanol was changed in A-E.
, F and G have different resin content ratios.

When the processing liquid wets the membrane surface, it permeates into the developed and bulky membrane. As the processing solution permeates into the membrane, the cloudiness in the developed area disappears. When ethanol was added, the developed area became cloudy again as the solvent evaporated, but when only methyl acetate was used as the solvent, the hologram almost disappeared at the same time as the cloudiness disappeared. On the other hand, when ethanol becomes excessive, resin powder is deposited on the hologram film surface (D, E). This resin powder is undesirable because it scatters Rayleigh's light and causes significant noise. Therefore, it is considered that the appropriate composition ratio of ethanol is 10 to 20 g per 100 g of methyl acetate.

Also, from the comparison of C, F, and G, even if the solvent composition is the same, the hologram tends to disappear when there is less resin.
g, for a solvent consisting of 10-20 g of ethanol, 2
It was found that the use of an acrylic resin with a weight of at least 100 g can prevent the hologram from disappearing. However, if the resin concentration is too high, the viscosity of the impregnating solution increases, making it difficult to process uniformly.

From the above results, the composition of the impregnation treatment solution was 100% methyl acetate.
It is appropriate for ethanol to be 10 to 209 g and for resin to be about 2 g.

Next, the diffraction efficiency and Bragg angle of the holograms immersed in treatment solutions B and C were measured in the same manner as described above. Figure 3 shows changes in Bragg angle before and after rC1 processing. The horizontal axis is the Bragg angle θ0 before processing. The vertical axis is the Bragg angle θ1 after processing. The following can be seen from this graph.

(1) θ0 and 0 times have a positive correlation.

(3) Since the return of the Bragg angle is small, θ! is 0 weight 5
degree (target value) or less.

(1) According to K, in order to reduce θl, it is sufficient to reduce θO, but it is assumed that there is no significant difference in the film itself between a film whose Bragg angle has been reduced by processing and a film whose Bragg angle is originally small. For example, I don't think it would be possible to restore the lag angle to history by repeating the process again.

Therefore, when the dipping method was repeatedly applied, it was found that the Bragg angle gradually returned to its original value. Of the 10 samples prepared, 7 obtained a diffraction efficiency of 6 or more.
FIG. 4 shows the change in Bragg angle when the sample was subjected to the immersion process eight times, and FIG. 5 shows the change in diffraction efficiency at the Bragg angle when the sample was undone. Immersion treatment ff: By repeating 8 times, the Bragg angle could be kept within the range of 2 to 5 degrees (Fig. 4). Table 4 and FIG. 6 show the diffraction efficiency before the treatment and after repeating the immersion treatment eight times.

Although the diffraction efficiency decreases by about 10% through this 8-time immersion treatment (Figure 5), the incident angle-diffraction efficiency O characteristic curve becomes gentler, and the incident angle margin (diffraction efficiency decreases within 10%) increases. It expanded from about ±3 degrees to ±5 degrees (Figure 6). As a result, for all seven samples, we were able to obtain a high diffraction efficiency of 50 to 60 degrees at 0 degree incidence (design angle) (Table 3. Table 4: Changes in properties due to immersion treatment Effects of the invention As is clear from the above explanation, depending on the present invention, the Bragg angle shifted by the development of the polyvinyl carbazole hologram can be returned to the designed angle side.
Conventionally, polyvinylcarbazole-based holograms have been provided that have high diffraction efficiency at a designed incident angle and small aberrations of diffracted light.

[Brief explanation of the drawing]

Figure 1 is a diagram illustrating the transfer of a hologram from a master hologram to a tivinylcarbazole-based photoresist film, Figure 2 is a diagram illustrating the Zorag angle return dipping process of the hologram, and Figure 3
The figure is a graph showing the Bragg angle shift due to immersion treatment, Figure 4 is a graph showing the Bragg angle shift due to repeated immersion treatment, Figure 5 is a graph showing the change in diffraction efficiency due to repeated immersion treatment, and Figure 6 is a graph showing the change in diffraction efficiency due to repeated immersion treatment. Incident angle due to processing −
It is a graph showing changes in diffraction efficiency characteristics. 1.../UIJ, 2...Master hologram, 3.
...Collimator, 11...Hologram, 12...
Jig, 13...Treatment liquid, θ0...Bragg angle during immersion treatment -on...Plug angle after 3-time immersion treatment, η・
...Diffraction efficiency, η1... Diffraction efficiency after 3-time immersion treatment. 10 752nd Figure 3 0 5 10 75 20 25 Bragg angle θO before treatment (de9) Number of 4th bond processing n (times) Figure 5 0 2 4 6 8 10 Number of immersion treatments n (times)

Claims (1)

[Claims] 1. A photosensitive film for hologram recording containing a polymer made of polyvinylcarbazole or its alkyl-substituted or halogen-substituted derivative and a radical generator is exposed to radiation to selectively crosslink the polymer. After that, the photoresist film is swollen with a 11t1 solvent, and then developed in a second solvent to obtain a hologram recording the gloss interference A' turn as a refractive index change, and then the porodurum is swollen with the polymer. A method for manufacturing a hologram, comprising immersing the hologram in a third solvent which is a poor solvent and has a resin dissolved therein, impregnating the hologram with the resin, and removing the solvent by evaporation. 2. The developing step is characterized in that the first solvent, the radical generator, and the uncrosslinked portion of the polymer are eluted from the photosensitive film into the second solvent. The method described in section. 3. Claim 1, wherein the radiation is a laser beam.
The method described in section.