JPH10187013A - Production and duplicating method for hologram, and hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hologram that does not generate scattering noise even to illuminating light from an edge, and is high in transparency and quality, by heating a photopolymer material and photoirradiating it after laser exposure. SOLUTION: A hologram dry plate 1 obtained after the laser exposure is placed on a temperature control plate 4 so that a hologram base board 3 faces down. The plate 1 is left a while after the plate 1 is placed, and is awaited till the temperature is stabilized at a set temperature. Then, the irradiation of a halide lamp 5 is performed for an adequate time. In this case, the plate 4 is previously set to an adequate process temperature and stabilized, and the light output of the lamp 5 is also stabilized. Heat processing is performed on the plate 1 obtained after passing through the process so as to be hardened and sentitized. This heating temperature range is from 40 deg.C to 90 deg.C, and photoirradiation quantity is at least >=10J/cm<2> with light having the wavelength of from 330nm to 390nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing, duplicating or mass-producing holograms, particularly high-quality edge-lit holograms, and to holograms produced by these methods.

[0002]

2. Description of the Related Art In recent years, the development of a hologram recording film using a photopolymer and the development of a hologram element using the same have been activated. The hologram formed on this recording film is called a volume phase hologram and has a periodic structure with a minute refractive index in the medium. Therefore, unlike an embossed hologram due to unevenness on the surface, the surface is smooth and looks like a transparent film in appearance. In addition, the hologram has a high resolution and can realize an arbitrary hologram function irrespective of a reflection type or a transmission type.

[0003] Such a photopolymer is disclosed in
-889, JP-A-2-3081, JP-A-5
It is considered that the materials described in JP-A-107999, JP-A-5-197324, and US Pat. No. 4,942,102 are effective.

[0004] Photopolymers having these hologram recording properties basically make a mixture of a polymerization initiator, a chain transfer agent, a binder, a monomer, and possibly a plasticizer sensitive to a laser wavelength in the visible region. Has a material composition to which a dye serving as a sensitizer is added.

[0005] The following are published (for example, "Photopolymers for holography", "Photopolymers for holography SPIC 1212",
SPIE1212, 1990)) The conventional technology will be described using a typical hologram fabrication process using a dry film type photopolymer as a material.

Conventional process conditions (1) Hologram production by laser exposure ~ several tens mJ / cm ² (2) Fixation by UV light irradiation ~ 100 mJ / cm ² (3) Heat treatment 120 ° C, 2 hours First, item (1) Laser exposure is performed using an optical system as shown in FIG. A laser beam 102 emitted from a laser 101 is split by a beam splitter 103 into a laser beam 104 and a laser beam 105 traveling on two optical paths, and using mirrors 106 and 107 at positions where the lengths of both optical paths are equal to each other. They are arranged so as to intersect at a predetermined angle. At this position, the laser beams 104 and 105 interfere with each other and form a standing wave having a period uniquely determined by the intersection angle and the wavelength. Hologram dry plate 1 obtained by bringing photopolymer 108 into close contact with substrate 109
10 is fixed at an exposure arrangement 111 drawn by a solid line or an exposure arrangement 112 drawn by a broken line. Exposure arrangement 1
When fixed at 11, the shape of the standing wave is recorded in a direction substantially parallel to the photopolymer 108, resulting in a reflection hologram. When fixed in the exposure arrangement 112, the shape of the standing wave is recorded in a direction substantially perpendicular to the photopolymer 108, and becomes a transmission hologram.

The mechanism by which the shape of the standing wave is recorded on the photopolymer 108 to form a hologram will be described in more detail.

The case where the laser beams 104 and 105 are plane waves will be described for the sake of simplicity. The standing wave formed by their interference with each other has a sinusoidal intensity distribution as shown in FIG. Having. If the high light intensity portion is called a bright portion and the low light intensity portion is called a dark portion, as shown by the hatched portion in FIG. 16B, first, photopolymerization of the photopolymer 108 is started in the bright portion. . Further, the monomer is consumed in the light part due to the polymerization, and the density of the monomer decreases, so that the diffusion of the unreacted monomer from the dark part to the light part occurs. As a result, the polymerization reaction in the bright portion further proceeds as shown by the hatched portion in FIG.
As a result of such a process, a shape having a density distribution in which a region where polymerization has progressed and a region which has not yet reacted is periodically arranged is formed inside the photopolymer 108, and this shape is as shown in FIG. As shown in (2), the distribution shape is the same as the standing wave formed by the laser light. Since this density distribution appears as a modulation of the refractive index, the interaction with light occurs, and the subsequent conventional process (2)
Is a fixing step using uniform UV light, which promotes polymerization of the entire photopolymer 108 including unreacted regions, and fixes the density distribution shape formed by laser exposure. This has been carried out for the purpose of preventing the already recorded distribution shape from being destroyed by light irradiation after this step and preventing a new distribution structure from being formed. Therefore, UV light irradiation of about 100 mJ / cm ^{2 under} the above conditions was sufficient for this purpose.

The last heat treatment in the conventional process (3) has been performed for the following two purposes.

[0010] 1. 1. Thermal curing of hologram: curing of polymer by thermal polymerization, removal of residual volatiles Thermal sensitization of holograms: further increase in refractive index modulation due to thermal diffusion of radicals Depending on the type of photopolymer, it has been reported that this heat treatment significantly increases the degree of refractive index modulation, thereby doubling the diffraction efficiency of holograms. is there.

FIG. 17 is a graph showing the absorption characteristics of a certain hologram recording photopolymer, in which the absorption of the dye changes with each process. Each curve shows the absorption characteristics after (a) unexposed photopolymer, (b) after laser exposure, and after fixing with UV light, and (c) after heat treatment.

When the curves (a) and (b) are compared, slight fading is observed due to laser exposure and UV light irradiation, but the absorption characteristic inherent to the dye still remains as shown in, for example, an absorption peak near 650 nm. It turns out that it is remarkably detected. That is, it is considered that most of the dye remains.

The curve (c) shows that the absorption peak inherent in the dye remaining in the previous step is weakened, and that most of the dye is decomposed in this heat treatment step.

In general, the photopolymer after the heat treatment is slightly colored but considerably transparent in appearance, and can be used with almost no problem in a hologram having a usual geometric arrangement.

[0015]

However, the hologram obtained by the above-described process has a problem in that the hologram looks cloudy because the material itself scatters the incident light for reproduction, albeit slightly. Was. Although depending on the type of the hologram, generally, such haze or haze lowers the quality of the hologram.

FIG. 18 shows a so-called edge-lit type hologram in which a hologram image 116 is reproduced from the photopolymer 115 toward the observer 117 with light from the light source 114 incident from the end face of the substrate 113. In particular, the quality was significantly reduced due to cloudiness and haze.
In particular, Japanese Patent Application Nos. 6-166706 and 8-59.
No. 012, etc., has become a serious problem in realizing the edge-lit hologram.

The scatterings to be considered here can be roughly classified into two types: (1) light scattering by a substance constituting the hologram material; and (2) color formation by residual dye.

Light scattering inside the hologram material as described in (1) above is called "haze" (haze), and its reduction has been reduced so far in hologram materials such as silver salts and dichromated gelatin. It has been an issue. Improvements have also been made in photopolymers to reduce the same, and holograms that have been reproduced in a normal geometric arrangement have now been improved to a level at which haze hardly matters.

However, the haze has not actually disappeared, and the present situation is that it is driven to a direction that is difficult to see in a normal arrangement. When light is actually incident on the photopolymer surface and observed from a direction along the photopolymer surface, scattered light can be observed in a region irradiated with the light.
In particular, as shown in FIG.
19 is polished and the photopolymer 1 on the glass side from this end face is polished.
The effect is remarkable when the surface 20 is viewed almost right beside, and the irradiation area 122 irradiated with the illumination light 121 can be clearly distinguished. This is because scattered light 123 is generated in the irradiation area 122 and is visible to the observer 124.

As described above, the scattered light 123 has a normal geometrical arrangement, such that light is incident on the photopolymer surface and the reproduced light is observed from the photopolymer surface. Because it does not enter, it does not look cloudy at all.

Incidentally, the coloring by the residual dye of the above item (2) also causes a reduction in the transparency, and hence the above-mentioned scattered light (haze) and this coloring will be referred to as "scattering noise".

Now, in an edge-lit hologram having a configuration in which light is incident from the end face of the substrate as shown in FIG. 18 and reproduction light is emitted from the substrate surface, scattered light due to illumination light is opposite to the above description. The light is emitted from the surface of the substrate.

As shown in FIG. 20, the scattered light 125 is observed so as to be superimposed on the reproduced image 126, and thus becomes noise that degrades the quality of the reproduced image. Further, even in a background area where no hologram is formed, the scattered light 125
Is emitted from the surface of the substrate, so that the portion that is originally transparent and the background of the substrate should be seen through becomes turbid, and the quality of the entire hologram element is significantly reduced.

Generally, the scattered noise in the laser exposure area is larger than the scattered noise in the background. (Several methods for reducing the scattering noise in the laser exposure area are described in Japanese Patent Application No. 8-59012.) It has also been found that the scattering noise varies in the laser exposure area.

FIG. 21 shows the characteristics of a certain type of photopolymer. The scattering noise (mainly due to the factor 1) in the laser exposure area once increases with an increase in the exposure amount, and then tends to decrease. Is showing. FIG. 2 shows that the scattering noise becomes largest when such a material is used.
This is the boundary portion of the laser exposure area as shown in FIG. That is, this is an area where only one of the reference beam 127 and the object beam 128 is irradiated at the time of laser exposure, and only one of the beams is irradiated, resulting in an insufficient laser exposure. .

Generally, it is difficult to completely match the irradiation areas of the reference light and the object light. Only in an exposure process in a limited geometrical arrangement, a mask can be inserted just before the hologram to make the regions coincide with each other. However, as shown in FIG. 23, any one of the reference light and the object light can be used. It becomes increasingly difficult as the angle of incidence increases. That is, since the reference beam 130 and the object beam 131 transmitted through the mask 129 travel at different angles, a boundary 133 on which only one of the beams is always irradiated on the photopolymer 132 is formed. This is always a problem in hologram production.

In particular, when producing an edge-lit hologram, it is necessary to optically contact a glass block 135 such as a prism with a hologram dry plate 134 as shown in FIG. 24, and to enter a reference beam 136 through this glass block. . Here, in addition to the geometrical constraint that the irradiation areas of the reference light 136 and the object light 137 are matched on the photopolymer 138, the distance between the mask 139 and the photopolymer 138 placed in the respective optical paths is increased. As a result, a diffraction pattern at the edge portion of the mask 139 is generated, so that the laser exposure boundary portion 140 cannot be made clear, and the scattering noise level has increased for the above-described reason.

In view of the above problems, the present invention provides a high-quality transparent hologram that does not generate scattering noise even with illumination light from an edge over the entire area of the laser exposure area, the background, and these boundaries. It aims to provide a fabrication process.

[0029]

In the above-described conventional process, the color of the dye is insufficiently discolored and the polymerization is insufficient when the fixing is performed by irradiation with UV light. Therefore, in the heat treatment process to be performed subsequently, these reactions proceed under heat energy.

The change of the photopolymer material in this heat treatment process is very complicated and cannot be strictly described here. However, the dye itself, which is caused by the fading of the dye during the heat treatment process, or the composition resulting from its decomposition. It is considered that the scattering / white turbidity is caused by the diffusion or aggregation of substances, the diffusion or aggregation of unreacted factors such as unreacted monomers, and the change of the photopolymer itself accompanying the progress of the thermal polymerization process.

Therefore, to avoid this, it is necessary to control factors such as the degree of fading of the dye, the process of fading (decomposing) the dye, the degree of polymerization, and the process of progressing the polymerization. Is considered to be the point of solving the problem, and as a result of intensive studies, the inventors have invented a hologram manufacturing method according to the present invention.

That is, in order to solve the above problems, the hologram manufacturing method of the present invention is characterized by performing the following process.

After the laser exposure, the photopolymer material is heated and irradiated with light, or heating and light irradiation are performed simultaneously. The heating temperature range is from 40 ° C to 9
0 ° C. and the light irradiation amount is from 330 nm to 390
The wavelength is at least 10 J / cm ² or more. Alternatively, at least 50 J / cm ² or more with light having a wavelength of 390 nm to 490 nm. Alternatively, the light irradiation amount is at least 10 J / cm ² or more and 390 n with light having a wavelength of 330 nm to 390 nm.
at least 50 J / cm for light of wavelength from m to 490 nm
² or more.

The above heating temperature is lower than the heat treatment temperature of 120 ° C. generally used in the conventional process. Further, the light irradiation amount is an irradiation amount that is higher by two digits or more than the light irradiation amount of 100 mJ / cm ² which has been generally used conventionally. Further, a process of irradiating light in a heated state is unprecedented.

The hologram manufacturing method of the present invention is characterized in that the following process is performed in order to eliminate scattering noise at the laser exposure boundary.

By projecting a mask pattern and irradiating light only to a region where a hologram is not formed, the hologram recording film in the region is inactivated before laser exposure. Alternatively, after the hologram recording film is inactivated in a region where the hologram is not copied, the hologram is copied by contact exposure from the hologram master on which the hologram is uniformly formed. Alternatively, the mask pattern is formed by a spatial light modulator.

An edge-lit hologram produced by any one of the above-described hologram manufacturing or duplication methods, that is, a hologram disposed on a transparent substrate and a light source, An edge-lit hologram configured to emit light from the light source incident from an end face of the transparent substrate to a surface of the transparent substrate by the hologram.

In the present invention, by the above-described process, the fading of the dye is completed before the heat treatment in the ordinary process, so that there is no factor causing unnecessary scattering noise.

Further, the sensitivity of the photopolymer is maintained in the shaded portion of the mask, and the sensitivity is lost in the region corresponding to the transmission portion of the mask, so that a clear boundary line is formed therebetween. Therefore, in the subsequent laser exposure, as long as the irradiation area of the reference light and the object light is set to a large area covering the area where the sensitivity is maintained, the reference light and the object light incident on the photopolymer are set. Are completely coincident with each other.

The use of the spatial modulator makes it possible to form an arbitrary pattern very easily.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hologram manufacturing process of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an experimental apparatus for performing heating and light irradiation according to the present invention. This process is performed after laser exposure in a conventional process and before heat treatment.

In FIG. 1, reference numeral 1 denotes a hologram dry plate, in which a photopolymer 2 is adhered to a hologram substrate 3. Also,
4 is a temperature control plate and 5 is a metal halide lamp. In advance, the temperature control plate 4 is set at an appropriate process temperature and stabilized, and the metal halide lamp 5 also stabilizes the light output. The hologram dry plate 1 after the laser exposure is placed on the temperature control plate 4 with the hologram substrate 3 facing down. After the hologram dry plate 1 is placed, the hologram dry plate 1 is left to stand for a while, and is waited until it is stabilized at the set temperature. Thereafter, the metal halide lamp 5 is irradiated for an appropriate time to complete this step. The hologram dry plate 1 having undergone this step is later subjected to the same heat treatment (120) as in the conventional process for curing and sensitization.
C., 2 hours), and all the processes are completed.

The above is the outline of all the steps including the process according to the present invention. The following experiments were conducted to clarify the optimum range of the heating temperature and the optimum range of the light irradiation amount.
This is an evaluation based on the scattered noise of the hologram of the present invention in the background. That is,
9 shows the results of an experiment in which laser exposure was omitted and light irradiation was performed in a heated state.

First, the conventional process conditions and the characteristics of the hologram obtained thereby will be described.

(Conventional process) (1) Laser exposure step: omitted (2) Fixing step Temperature: room temperature Light irradiation amount: 0.1 J / cm ² (receiver 1) (3) Heat treatment step: 120 ° C., 2 hours ( Experimental results) Scattering noise: 18 to 30 cd / m ² The experimental conditions in the examples shown here were fixed under the following conditions unless otherwise specified. Photopolymer: HRF750X245-9 (manufactured by DuPont) Substrate form: 4-side polished plate (50 × 50 × thickness 4)
mm) Substrate material: Optical glass BK7 Light irradiation lamp: Metal halide lamp Irradiation direction: From base film side Illuminometer: Ushio UV illuminometer UIT-1
01 Receiver 1 UVD-365PD (wavelength band 330-39
0 nm) Receiver 2 UVD-405PD (wavelength band 330-49)
0 nm) Illumination light source: Cold cathode fluorescent tube φ3 mm Measuring instrument: Minolta luminance meter LS-100 The photopolymer used here is a photopolymer for full-color hologram having hologram recording sensitivity over the entire visible range, and at the same time, a master hologram. 2 has a structure as shown in FIG. That is, the photopolymer 6 has a structure in which the photopolymer 6 is in close contact with the cover film 7 and the barrier film 8, and the hologram dry plate 1 is usually formed by being attached to the hologram substrate 9. This is configured to peel off the cover film 7 and make optical contact through the isotropic barrier film 8 to mainly facilitate the transfer duplication. However, in a normal process, this cover is used. It may be used without removing the film 7. In this experiment, the process was performed with the cover film 7 left, and the heat treatment was completed.
This was peeled off immediately before the measurement shown below.

The value shown as the light irradiation amount was calculated by taking the product of the light intensity measured by each light receiver and the light irradiation time. For example, the value of 0.1 J / cm ² in the conventional example was measured by the photodetector 1, that is, at least 33 J / cm ^2.
2 mW / cm light intensity including wavelengths from 0 nm to 390 nm
² shows that this is achieved by irradiating 50 seconds of light.

The scattering noise was evaluated by constructing a measuring system as shown in FIG. Reference numeral 10 denotes a hologram element for evaluation after the process, 11 denotes a cold cathode fluorescent tube, 12 denotes a reflection mirror, 13
Is a shielding plate, and 14 is a luminance meter. The level of the scattering noise 15 generated by the light from the cold cathode fluorescent tube 11 was measured by a luminance meter 14 installed at a distance of about 1 m. After the cold cathode fluorescent tube 11 was turned on by a power supply device having a fixed voltage and current level, the measurement was carried out after a sufficient time until the output was stabilized.

A method for quantitatively evaluating the value of the scattering noise of such an edge-lit hologram has not been established. This time, the values measured by the luminance meter as described above are shown as data. This is because the effect of the present invention is quantitatively expressed by displaying the luminance as a standard parameter in optical measurement. In addition to the above, a measurement system combining a power meter 16 and a black pipe 17 (this may be a configuration in which irises are arranged in series) as shown in FIG. Was compared, it was confirmed that the qualitative tendency was consistent with the measurement result by the luminance meter. That is, the magnitude of the measured value of each evaluation sample did not reverse in each measurement result. If anything, the sensitivity at the level where the scattering noise is reduced is higher in the measurement system using the luminance meter,
This is also one of the reasons for showing the effect of the present invention by the data of the luminance meter.

As described above, the reading of the luminance meter obtained as a result of the conventional process is mostly 18 cd.
It was a value of / m ^2, but was also show a large value of 30 cd / m ² is in. This value of 30 cd / m ² indicates a luminance that can be sufficiently observed even in a bright room. The hologram substrate is originally transparent, and its background should be seen as if viewed through a window glass. However, the background is blurred when such scattered noise is emitted from the hologram. Also, the best value of 18 cd / m ² was very bright to the eyes when observed in a darkened room, and was at a level where it was almost difficult to see the object behind the hologram.

Next, the usefulness of the present invention will be shown by showing the fabrication process based on the present invention and the results obtained thereby together with supplementary experimental results in a range beyond the limited area according to the present invention. I will do it.

(Experiment 1) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: 40 ° C. Light irradiation: 10 J / cm ² (Receiver 1) Filter used: Visible light cut filter U330 (thickness 3 mm) (3) Heat treatment step: Same as before (120 ° C, 2
(Experimental results) Luminance meter indicated value: 9 to 10 cd / m ² (Experiment 2) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating temperature: 90 ° C. Light irradiation: 10 J / cm ² ( Receiver 1) Filter used: Visible light cut filter U330 (thickness: 3 mm) (3) Heat treatment step: Same as before (120 ° C, 2
(Experimental results) Luminance meter indication value: 9 to 10 cd / m ² (Experiment 3) (1) Laser exposure step: Omitted (2) Fixing and fading step Temperature: 25 ° C. Light irradiation: 10 J / cm ² (Light receiving) 1) Filter used: Visible light cut filter U330 (thickness 3 mm) (3) Heat treatment step: Same as before (120 ° C, 2
(Experiment result) Luminance meter indicated value: 12-13 cd / m ² (Experiment 4) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating temperature: 105 ° C. Light irradiation: 10 J / cm ² ( Receiver 1) Filter used: Visible light cut filter U330 (thickness: 3 mm) (3) Heat treatment step: Same as before (120 ° C, 2
Time) (Experimental Result) Luminance Meter Indication Value: 11-13 cd / m ^{2 Based} on the four experimental results described above, heating temperature range 4
At least 330 nm to 390 at 0 ° C. to 90 ° C.
It can be seen that the transparency of the background of the hologram is improved by irradiating 10 J / cm ^{2 with} light having a wavelength of nm.

(Experiment 5) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: 40 ° C. Light irradiation: 50 J / cm ² (receiver 2) Filter used: colored glass L-40 (3) Heat treatment process: Same as before (120 ° C, 2
(Experiment result) Luminance meter indicated value: 8-9 cd / m ² (Experiment 6) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating temperature: 90 ° C. Light irradiation: 50 J / cm ² ( Receiver 2) Filter used: Color glass L-40 (3) Heat treatment step: Same as before (120 ° C, 2
(Experiment result) Luminance meter indicated value: 9 to 10 cd / m ² (Experiment 7) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating temperature: Room temperature Light irradiation: 50 J / cm ² (Light receiving) 2) Filter used: colored glass L-40 (3) Heat treatment step: same as before (120 ° C, 2
Time) (Experimental result) Intensity meter indicated value: 11-12 cd / m ² (Experiment 8) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating temperature: 105 ° C. Light irradiation: 50 J / cm ² ( Receiver 2) Filter used: Color glass L-40 (3) Heat treatment step: Same as before (120 ° C, 2
Time) (Experimental result) Luminance meter indicated value: 11-13 cd / m ^{2 As} shown in FIG. 5, the color glass L-40 used here has a property of cutting light having a wavelength of 390 nm or less. And the reading of the receiver 2 is 3 compared to the case without the filter.
It was as low as 0%.

From the four experimental results described above, at least 390 n in a heating temperature range of 40 ° C. to 90 ° C.
It can be seen that irradiating light having a wavelength of m to 490 nm with 50 J / cm ² improves the transparency of the background of the hologram.

(Experiment 9) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: 40 ° C. Light irradiation: 10 J / cm ² (receiver 1) 70 J / cm ² (receiver 2) (3) ) Heat treatment step: Same as before (120 ° C, 2 hours) (Experimental result) Intensity meter indicated value: 8-9 cd / m ² (Experiment 10) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating Temperature: 90 ° C. Light irradiation: 10 J / cm ² (Receiver 1) 70 J / cm ² (Receiver 2) (3) Heat treatment process: Same as before (120 ° C., 2 hours) (Experimental results) Luminance meter indicated value: 8 to 9 cd / m ² (Experiment 11) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: room temperature Light irradiation: 10 J / cm ² (receiver 1) 70 J / cm ² (receiver 2) (3) Heat treatment step: Same as before (12 ° C., 2 hours) (Test Results) luminance meter readings: 11-12 cd / m ² (Experiment 12) (1) laser exposure step: omitted (2) fixing and bleaching process heating temperature: 105 ° C. irradiation: 10J / cm ² (Receiver 1) 70 J / cm ² (Receiver 2) (3) Heat treatment step: Same as before (120 ° C., 2 hours) (Experimental result) Luminance meter indicated value: 10-11 cd / m ² or more From the four experimental results described, the heating temperature range 4
At least 330 nm to 390 at 0 ° C. to 90 ° C.
10 J / cm ² , and at least 3
Light having a wavelength of 30 nm to 490 nm at 70 J / cm
^It can be seen that the ^two irradiations particularly effectively improve the background transparency of the hologram.

(Experiment 13) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: 40 ° C. Light irradiation: 5 J / cm ² (receiver 1) 35 J / cm ² (receiver 2) (3) ) Heat treatment step: Same as before (120 ° C, 2 hours) (Experimental results) Intensity meter indicated value: 10-12 cd / m ² (Experiment 14) (1) Laser exposure step: Omitted (2) Fixing and fading step Heating Temperature: 90 ° C. Light irradiation: 5 J / cm ² (Receiver 1) 35 J / cm ² (Receiver 2) (3) Heat treatment process: Same as before (120 ° C., 2 hours) (Experimental results) Luminance meter indication value: 10-11 cd / m ² (Experiment 15) (1) Laser exposure step: omitted (2) Fixing and fading step Heating temperature: 90 ° C. Light irradiation: 1 J / cm ² (receiver 1) 7 J / cm ² (receiver) 2) (3) Heat treatment process: Same as before ( 20 ° C., 2 hours) (Test Results) luminance meter readings: 13-14 cd / m ² (Experiment 16) (1) laser exposure step: omitted (2) fixing and bleaching process heating temperature: 40 ° C. irradiation: 1 J / Cm ² (Receiver 1) 7 J / cm ² (Receiver 2) (3) Heat treatment step: Same as before (120 ° C, 2 hours) (Experimental result) Brightness meter indicated value: 13-15 cd / m ² or more According to the four experimental results described in the above, the heating temperature range 4
When the light having a wavelength of 330 nm to 390 nm at 0 ° C. and 90 ° C. is less than 10 J / cm ² , and
It can be seen from the graph that when the light having a wavelength of 490 nm is less than 50 J / cm ² , the transparency of the background of the hologram cannot be improved.

To summarize the above, in the process of the present invention, the level of the scattered noise is 10 cd /
m ² or less, and 10 cd /
m ² was found to be not below.

As described above, the effects of the present invention have been shown by 16 dispersed experimental results. In order to clarify the claims of the present invention, FIG. 6 shows an example of the experimental results as a graph.

From this, it can be seen that almost the same effect is obtained in the range of 40 ° C. to 90 ° C. Also, the light irradiation amount is 10 cd / cm ² within the irradiation amount range of 10 J / cm ² or more.
m ² or less, especially 120 J / cm ²
4 to 3 times higher than the conventional dose
A good result of 5 cd / m ² has been obtained. In observation in a dark room, it was confirmed that this level was a level at which the background of the hologram could be clearly recognized.

In the experiment, if the sample and the lamp for light irradiation are brought close to each other, the temperature of the sample naturally rises because the lamp is affected by the heat radiation of the lamp in addition to the energy of light irradiation. In particular, since the light irradiation amount for fixing and dye fading according to the present invention is about two orders of magnitude higher than usual, according to experiments, a temperature rise of 30 ° C. to 50 ° C. was observed during light irradiation. Room temperature 2
Even when the experiment was started at 5 ° C., the temperature of the sample naturally increased from 55 ° C. to 75 ° C. during the light irradiation, so the value obtained as a result of the experiment in which the sample temperature was intentionally increased It was similar to Therefore, although it is possible to construct a simpler process with this method,
However, the sample temperature may be 100 ° C. or higher depending on the light irradiation conditions and the cooling state of the irradiation device, and as a result, there was an example in which the cloudiness was increased due to overheating. In an extreme case, the base film, the photopolymer, and the glass substrate may be burned.

In order to eliminate the above-mentioned adverse effects, in the above experiment, an experiment was carried out by placing a sample on a temperature control plate provided with a cooling mechanism using a Peltier element, and an optimum heating temperature range was determined. . Here, when the distance from the lamp was shortened, a temperature rise due to light irradiation was observed, but the rise was suppressed to 20 ° C. or less at the maximum. It was also found that by setting the distance from the lamp appropriately, the set temperature could be almost maintained.

Of course, the temperature control plate as described above is not always necessary in an actual manufacturing process.
It is only necessary to set conditions that satisfy the temperature condition and the light irradiation condition according to the present invention. Even when the temperature is naturally increased as described above without performing the temperature control, good results are obtained only in a range that satisfies the temperature condition and the light irradiation condition according to the present invention.

FIG. 7 is a graph showing the absorption characteristics of the photopolymer in each step of the process of the present invention, showing how the absorption of the dye changes with each process. Each curve shows the absorption characteristics after (a) unexposed photopolymer, (b) after heating, and after light irradiation (c) after heat treatment.

From the curve (b), it can be seen that the absorption peak peculiar to the dye disappeared by the light irradiation of this process, that is, before the heat treatment. Even after the heat treatment, there is no significant change in the absorption characteristics as shown by the curve (c). The photopolymer that has undergone this process has a light orange color, but has a low level of scattering noise.

The above is the evaluation in the background where no hologram is formed. However, in order to evaluate the improvement in the transparency of the hologram, laser exposure is actually performed and scattering noise in the area where the hologram is formed is reduced. Must be evaluated.

FIG. 8 shows an optical system for forming a regular reflection hologram. 18 is a photopolymer, 19 is a substrate, 20 is a surface reflection mirror, 21 and 22 are refractive index matching liquids, and 23 is an antireflection substrate. A regular reflection hologram is formed in the photopolymer 18 by causing the laser beam 24 to enter from the antireflection substrate 23 side and interfere with the reflected light from the surface reflection mirror.

Argon laser wavelength 48 as laser light
8 nm, HRF similar to the above experiment as photopolymer
After performing laser exposure using 750 X 245-9 and xylene as a refractive index matching liquid, heating and light irradiation by the process of the present invention and heat treatment in a normal process were performed. The hologram after the process was illuminated with a cold cathode fluorescent tube from the end face of the substrate in the same manner as in the above experiment, and the scattering noise from the surface was observed.

In the conventional process, the area where the regular reflection hologram was formed was clearly different from the background and could be easily recognized. The formed regular reflection hologram does not generate diffracted light on the substrate surface with respect to such incident light from the end face. That is, the fact that the hologram area can be recognized here indicates that the level of the scattering noise which has been a problem so far is high. According to the evaluation by the luminance meter, the scattering noise level in the area where the regular reflection hologram was formed was 5-
The value was higher by 10 cd / m2.

On the other hand, according to the process of the present invention, the difference between the regular reflection hologram area and the background is only 1-2.
At cd / m 2, the level was almost unnoticeable.
That is, it was found that the effects of the present invention were remarkably exhibited also in the laser exposure region. When the spectral characteristics of the reflection hologram were evaluated after heating and light irradiation, it was confirmed that the reflectance was higher than that immediately after the laser exposure, and that the half width was broadened. However, this sensitization is not as large as the sensitization observed in the heat treatment at 120 ° C. for 2 hours, which is the same as the conventional process after light irradiation. confirmed.

FIG. 9 shows an optical system for forming an edge-lit reflection hologram. 25 is a photopolymer, 26 is a substrate, 27 and 28 are glass blocks, 29,
Reference numerals 30 and 31 denote light absorbing plates, and reference numerals 32 and 33 denote refractive index matching liquids. The reference light 34 is incident from the glass block 27 side,
A reflection hologram is formed in the photopolymer 25 by interference with the object light 35 incident from the glass block 28.

In the case of an edge-lit type reflection hologram formed by such a configuration, since diffracted light is actually emitted from the substrate surface, it is difficult to separate and quantify background scattering noise. Therefore, when visual observation was performed from a position deviated from the emission direction, a remarkable improvement was confirmed as compared with the conventional process.

The effect has also been confirmed when applied to the following devices.

FIG. 10 shows a configuration example of a display device described in Japanese Patent Application Nos. 6-166706 and 8-59012. 36 is a cold cathode fluorescent tube, 37 is a reflection mirror, 38 is a substrate, 39 is propagation light, 40 is an edge-lit hologram, 41 is illumination light, 42 is a polymer dispersed liquid crystal display device, and 43 is a pixel in a scattering state. , 44 are scattered display light, and 45 is an observer. The light emitted from the cold cathode fluorescent tube 36 enters the substrate 38 directly or after being reflected by the reflection mirror 37 to become the propagation light 39, and is diffracted by the edge-lit hologram 40 to become the illumination light 41. This illumination light 4
Numeral 1 emits light downward from the surface of the substrate 38 in the figure, enters a polymer dispersion type liquid crystal display device 42 disposed in close proximity, illuminates the pixels 43 in a scattered state, and observes them as scattered display light 44. Reaches the eye of the person 45. In other areas of the polymer-dispersed liquid crystal display device 40, since the pixels are in a transparent state, the illumination light 42 is transmitted as it is, and is not visible to the observer 45.

When the above-mentioned edge-lit hologram was produced by the process of the present invention, the background was clearly visible in the region where the polymer dispersed liquid crystal became transparent. As a result, a transparent display, a head-up display, and a transparent direct-view display capable of displaying a color as described in the above literature can be configured.

In this fabrication, the optical system shown in FIG. 9 can be used. Here, as shown in FIG. 11, the peripheral region of the photopolymer 25 is irradiated with light in advance, and the inactive region 46 (FIG. Black portion). As a result, the boundary of the exposure region 49 where the reference beam 47 and the object beam 48 interfere to form a hologram is uniquely determined, and scattering noise is eliminated at the boundary of the exposure region of the completed edge-lit hologram.

Incidentally, in the embodiment described above, HR
Although the description has been made by taking F750X245-9 as an example, another photopolymer manufactured by DuPont, H
RF600X001, HRF700X071, HRF7
50X199, HRF750X181, HRF750X
122, HRF750X083, Omnidex352
And the like, the same effect has been confirmed, and it is considered that the production method of the present invention is also effective for other similar photopolymers.

However, in the case of a type of photopolymer in which the base film cannot be peeled, the transparency is slightly inferior due to the effects of dirt and scratches on the surface or internal scattering of the base film itself. Therefore, in order to produce the most transparent hologram, especially an edge-lit hologram, the base film can be peeled off, and an isotropic barrier film is used as the outermost surface, or a transparent adhesive such as a UV effect resin is attached to this. Most preferred is a form in which a transparent film or glass is adhered through the film.

FIG. 12 is a diagram schematically showing a state of copying from a master hologram. In the figure, 50 is a master hologram, 51 is an inactive area, 52 is a photopolymer, 53
Is a refractive index matching liquid, 54 is a glass block, 55 is a laser beam for duplication, 56 is a diffracted light for duplication, 57 is a hologram, 58
Is a light absorbing plate.

The master hologram 50 is formed by the process as described above, and a hologram is formed uniformly over the entire effective area.
It should be noted that there can be any form of master hologram in the case of a single photopolymer film or in the case where it is attached to a substrate material. The duplication photopolymer 52 in which an inactive region 51 is partially formed is bonded to the master hologram 50 via the refractive index matching liquid 53, and the duplication laser light 55 is irradiated from the glass block 54 which is in close contact with the master hologram 50. You. The duplicated diffraction light 56 diffracted by the master hologram 50 interferes with the duplicated laser light 55 to form a hologram 57. The diffraction light for duplication 56 not diffracted by the master hologram 50 is absorbed by the light absorbing plate 58. By the above process, the hologram 57 is copied to an arbitrarily definable area other than the inactive area 51.
Since the inactive region 51 is provided, the boundary of the region is clear, and no scattering noise occurs.

FIG. 13 is a principle diagram of forming an inactive area by projecting a mask pattern. The light from the light source 60 that has passed through the mask pattern 59 is projected onto the photopolymer material 62 by the projection lens 61 to form a projection pattern 63 in which the mask pattern has been enlarged, reduced, or has the same size. The mask pattern 59 is formed of, for example, a negative film or the like, and is inactivated in a region on the photopolymer material 62 (the white region of the projection pattern 63 in the figure) to which the light that has passed through the transparent region (white region in the figure) reaches. Done.
During this time, the photopolymer material 62 is stationary, is fed at a constant interval after the end, and deactivates the next region.

When changing the shape of the inactive region, the mask pattern 59 may be replaced with another negative film. In addition, as shown in FIG. 14, by configuring this mask pattern with a spatial light modulator 64 such as a liquid crystal panel, there is an advantage that pattern switching becomes extremely easy and the loss required for this can be omitted.

[0081]

As described above, according to the present invention, a hologram having high transparency and free from scattering noise, in particular, an edge-lit hologram can be realized. This is usually transparent,
A compact, high-quality, edge-lit, transparent information display panel that displays information only when necessary can be realized. Furthermore, by combination with a polymer dispersion type liquid crystal display device,
A transparent display or a head-up display that can display necessary information only when necessary without obstructing the field of view is realized. Further, a transparent direct-view type display device capable of color display can be realized. In addition, duplicate holograms having different aperture patterns can be efficiently produced from one master hologram.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for performing a heating and light irradiation process in the present invention.

FIG. 2 is a configuration diagram of a hologram dry plate.

FIG. 3 is a configuration diagram of a scattering noise measurement system using a luminance meter.

FIG. 4 is a configuration diagram of a scattering noise measurement system using a power meter.

FIG. 5 is a transmission characteristic diagram of a colored glass.

FIG. 6 is a graph showing experimental results obtained by the process of the present invention.

FIG. 7 is a graph showing a change in absorption characteristics of a photopolymer by the process of the present invention.

FIG. 8 is a configuration diagram of an optical system for forming a regular reflection hologram.

FIG. 9 is a configuration diagram of an optical system for forming an edge-lit reflection hologram;

FIG. 10 is a configuration diagram of a transparent display using an edge-lit reflection hologram and a polymer-dispersed liquid crystal display device.

FIG. 11 is a configuration diagram of an optical system for forming an edge-lit reflection hologram using a photopolymer having a peripheral portion inactivated.

FIG. 12 is a configuration diagram of an optical system for replicating a hologram.

FIG. 13 is a principle diagram of inactivation by a projection method.

FIG. 14 is a principle diagram of inactivation by a projection method using a spatial light modulator.

FIG. 15 is a configuration diagram of a laser exposure optical system.

FIG. 16A is a light intensity distribution diagram of interference fringes. FIG. 16B is a schematic diagram showing movement of an unreacted monomer in a photopolymer. FIG. 16C is a schematic diagram showing a region where polymerization has progressed.

FIG. 17 is a diagram showing absorption characteristics of a photopolymer in a conventional process.

FIG. 18 is a configuration diagram of an edge-lit hologram.

FIG. 19 is a principle diagram showing a state of scattered light observation by a photopolymer.

FIG. 20 is a diagram showing a reproduction state of an edge-lit hologram including scattering noise.

FIG. 21 is a graph showing the relationship between the photopolymer scattering noise and the amount of exposure.

FIG. 22 is a diagram showing a boundary portion of a laser exposure region.

FIG. 23 is a principle view for explaining how a boundary is formed.

FIG. 24 is a principle diagram illustrating a state in which a boundary is formed in an edge-lit hologram.

[Explanation of symbols]

 Reference Signs List 1 hologram dry plate 2 photopolymer 3 hologram substrate 4 temperature control plate 5 metal halide lamp 6 photopolymer 7 cover film 8 barrier film 9 hologram substrate 10 evaluation hologram element 11 cold cathode fluorescent tube 12 reflection mirror 13 shield plate 14 luminance meter 15 scattering noise Reference Signs List 16 power meter 17 black pipe 18 photopolymer 19 substrate 20 surface reflection mirror 21, 22 refractive index matching liquid 23 antireflection substrate 24 laser beam 25 photopolymer 26 substrate 27, 28 glass block 29, 30, 31 light absorption plate 32, 33 Refractive index matching liquid 34 Reference light 35 Object light 36 Cold cathode fluorescent tube 37 Reflector mirror 38 Substrate 39 Propagation light 40 Edge-lit hologram 41 Illumination light 42 Polymer dispersed liquid crystal display device 43 Pixel in scattering state 44 Scattering Illumination 45 Observer 46 Inactive area 47 Reference light 48 Object light 49 Exposure area 50 Master hologram 51 Inactive area 52 Photopolymer 53 Refractive index matching liquid 54 Glass block 55 Duplicating laser beam 56 Duplicating diffracted beam 57 Hologram 58 Light Absorbing plate 59 Mask pattern 60 Light source 61 Projection lens 62 Photopolymer material 63 Projection pattern 64 Spatial light modulator

Claims (15)

[Claims] 1. A method for manufacturing a hologram using a photopolymer material, comprising heating the photopolymer material after laser exposure and irradiating the photopolymer material with light. 2. A method for manufacturing a hologram using a photopolymer material, wherein heating and light irradiation of the photopolymer material are performed simultaneously after laser exposure. 3. The method for producing a hologram according to claim 1, wherein a heating temperature range is 40 ° C. or more and 90 ° C. or less. 4. The method for producing a hologram according to claim 1, wherein the irradiation amount of light having a wavelength of 390 nm or less is 10 joules or more per square centimeter. 5. The method for producing a hologram according to claim 1, wherein the irradiation amount of light having a wavelength of 390 nm or more is 50 joules or more per square centimeter. 6. The light irradiation amount of light having a wavelength of 390 nm or less is 10 joules or more per square centimeter, and the light irradiation amount of 390 nm or more is 50 joules or more per square centimeter. A method for producing the hologram according to the above. 7. A lamp according to claim 1, wherein a lamp for emitting ultraviolet light and visible light is used as a light irradiation light source.
A method for producing the hologram according to the above. 8. The method for manufacturing a hologram according to claim 1, wherein the light is irradiated with sunlight. 9. A method for manufacturing a hologram, comprising projecting a mask pattern and irradiating light only to a region where a hologram is not formed, thereby inactivating a hologram recording film in said region before laser exposure. . 10. A method for duplicating a hologram, comprising: inactivating a hologram recording film in a region where a hologram is not duplicated, and then duplicating the hologram by contact exposure from a hologram master on which a hologram is uniformly formed. 11. The hologram duplication according to claim 10, wherein the mask pattern is projected to irradiate light only to a region where the hologram is not duplicated, thereby inactivating the hologram recording film in said region. Method. 12. The method according to claim 9, wherein the mask pattern is formed by a spatial light modulator. 13. An edge lit comprising a light source and a hologram arranged on a transparent substrate, wherein the hologram emits light from the light source incident from an end face of the transparent substrate to a surface of the transparent substrate. A hologram, wherein the hologram is manufactured by the method for manufacturing a hologram according to any one of claims 1 to 9. 14. The hologram duplication method according to claim 11, wherein the mask pattern is formed by a spatial light modulator. 15. An edge lit comprising a light source and a hologram arranged on a transparent substrate, wherein the hologram emits light from the light source incident from an end face of the transparent substrate to a surface of the transparent substrate. 13. A hologram, which is manufactured by the hologram duplication method according to claim 10.