JP2000214747A - Hologram sensitive film and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hologram sensitive film having a high refractive index modulation degree and high diffraction efficiency and suitable for multi- wavelength simultaneous exposure or for multi-wavelength sequential exposure including no fixing process on the midway by disposing plural sensitive layers having separate sensitivities to the wavelengths of light rays for exposure in one film. SOLUTION: A green-sensitive layer 3, a barrier layer 4, a blue-sensitive layer 5, a barrier layer 6, a red-sensitive layer 7 and a cover film 8 are successively laminated on a base film 2 to obtain the objective hologram sensitive film 1. The green-sensitive layer 3 contains a sensitizing dye and a reaction initiator in such a way that it has sufficient sensitivity only in the wavelength band of about 500-550 nm. The blue-sensitive layer 5 contains a sensitizing dye and a reaction initiator in such a way that it has sufficient sensitivity only in the wavelength band of about 400-480 nm. The red-sensitive layer 7 contains a sensitizing dye and a reaction initiator in such a way that it has sufficient sensitivity only in the wavelength band of about 600-700 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram photosensitive film having a plurality of photosensitive layers in one film and an exposure method for the hologram photosensitive film.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional hologram photosensitive film 100 is a base film 10 made of, for example, a polyethylene terephthalate film having a thickness of about 50 μm.
1, a photosensitive layer 102 containing a photosensitive material is formed to a thickness of, for example, about 20 μm, and the photosensitive layer 102 is covered with a cover film 103 made of, for example, a polyethylene terephthalate film having a thickness of about 25 μm. I have.

Here, the photosensitive material contained in the photosensitive layer 102 has sensitivity only in a certain limited wavelength region. Therefore, for example, when exposing the hologram photosensitive film 100 using red, green, and blue laser light to produce a color image such as a color hologram or a holographic optical element for multiple wavelengths, the sensitivity for each wavelength is reduced. A plurality of hologram photosensitive films 100
Must be configured by sticking together.

[0004]

However, in this case, since each hologram photosensitive film is usually sensitive to adjacent exposure laser wavelengths, it does not go through multiple wavelength simultaneous exposure or a fixing process in the middle. If a color hologram is to be produced by multi-wavelength sequential exposure, interference fringes of a plurality of wavelengths will be recorded on one photosensitive layer, and the diffraction efficiency of each color hologram will be degraded. In order to prevent this, it is necessary to perform exposure and fixing for each color hologram photosensitive film and then to bond the respective hologram photosensitive films, which not only complicates the manufacturing process,
High-precision position reproducibility at the time of exposure of the hologram photosensitive film is required, which leads to an increase in the cost of the manufacturing apparatus.

On the other hand, in recent years, photosensitive materials having sensitivity to the entire visible light range have been developed. In this case, multi-wavelength simultaneous exposure or multi-wavelength sequential exposure without a fixing process in the middle is possible. There is a problem that the refractive index modulation degree is reduced to about one part of the number of exposure wavelengths compared to the refractive index modulation degree of a hologram manufactured by single wavelength exposure. For example, in a typical hologram photosensitive film using a photopolymer as a photosensitive material, a hologram produced by monochromatic exposure has a refractive index modulation degree of 0.0.
On the other hand, in the case of a color hologram produced by three-color exposure of red, blue and green, the refractive index modulation degree for each color is reduced to about 0.01. here,
The diffraction efficiency, that is, the brightness, of the hologram greatly depends on the degree of refractive index modulation, and the diffraction efficiency increases as this value increases.

The present invention has been proposed in view of such a conventional situation. A high refractive index modulation degree and a high diffraction efficiency are obtained, and simultaneous multi-wavelength exposure or other wavelength sequential irradiation is performed without a fixing process. An object of the present invention is to provide a hologram photosensitive film suitable for exposure and an exposure method.

[0007]

The hologram photosensitive film of the present invention has at least two or more photosensitive layers, and each of the at least two or more photosensitive layers has a photosensitive action for a different laser wavelength band. It is characterized by.

Since the hologram photosensitive film according to the present invention as described above has at least two photosensitive layers each having a photosensitive action for a different laser wavelength band, interference fringes corresponding to the laser wavelength band are generated. Is formed on each photosensitive layer.

According to the exposure method of the present invention, the holographic photosensitive film having at least two or more photosensitive layers, each having a sensitizing action to a different laser wavelength band, has the sensitizing action of the two or more photosensitive layers. The above-mentioned two or more photosensitive layers are successively exposed by sequentially irradiating a laser having a wavelength band having the wavelength.

In the above-described exposure method according to the present invention, the hologram photosensitive film having at least two or more photosensitive layers each having a photosensitive action for a different laser wavelength band has the two or more photosensitive layers. Since the laser in the wavelength band having a photosensitive action is sequentially irradiated,
Positioning for each wavelength is not required, and a color image with excellent diffraction efficiency can be easily produced.

[0011] The exposure method of the present invention is characterized in that the two or more photosensitive layers each have a photosensitive action on a hologram photosensitive film having at least two or more photosensitive layers, each of which has a photosensitive action on a different laser wavelength band. The above-mentioned two or more photosensitive layers are exposed by irradiating a laser including a wavelength band having the above-mentioned wavelength band.

In the above-described exposure method according to the present invention, the hologram photosensitive film having at least two or more photosensitive layers each having a photosensitive action for a different laser wavelength band has the two or more photosensitive layers. Because it irradiates a laser that includes a wavelength band that has a photosensitive action,
Positioning for each wavelength is not required, and a color image with excellent diffraction efficiency can be easily produced.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 shows a configuration example of the hologram photosensitive film according to the present embodiment. The hologram photosensitive film 1 is a photosensitive film suitable for producing, for example, a color hologram. On the base film 2, a green photosensitive layer 3, a barrier layer 4, a blue photosensitive layer 5, and a barrier layer 6 are formed. , A red photosensitive layer 7 and a cover film 8 are laminated in this order.

Base film 2 and cover film 8
Is made of polyethylene terephthalate or the like. The thickness of the base film 2 and the cover film 8 is about several tens of μm.
μm, and the cover film 8 has a thickness of 25 μm.

Photosensitive layers for green, blue and red 3, 5, 7
Are, respectively, a sensitizing dye (photoseisitizing dye), a reaction initiator (initiator), and a chain transfer agent (chain trans).
fer agent), a monomer, a photopolymer containing a polymer binder and the like. And these greens,
The thicknesses of the blue and red photosensitive layers 3, 5, and 7 are about several μm to several tens μm, and specifically, for example, each 15 μm.
It has been.

The green photosensitive layer 3 has a thickness of about 500 to 5 mm.
A sensitizing dye or a reaction initiator is contained so as to have a sufficient sensitivity only in a wavelength band of 50 nm, and the blue photosensitive layer 5 has a sufficient sensitivity only in a wavelength band of about 400 to 480 nm. , A sensitizing dye and a reaction initiator. The red photosensitive layer 7 has a thickness of about 600-7.
A sensitizing dye and a reaction initiator are contained so as to have sufficient sensitivity only in the wavelength band of 00 nm.

Therefore, when the hologram photosensitive film 1 is exposed to an Ar gas laser having a wavelength of 477 nm,
Only the blue photosensitive layer 5 is exposed, and the other red photosensitive layer 7 and green photosensitive layer 3 are not exposed. When the hologram photosensitive film 1 is exposed by a laser using a second harmonic of a YAG laser having a wavelength of 532 nm, the green photosensitive layer 3 is exposed.
Only the photosensitive layer 7 for red and the photosensitive layer 5 for blue
Is not exposed. When exposure is performed with a Kr gas laser having a wavelength of 647 nm, only the red photosensitive layer 7 is exposed, and the other green photosensitive layers 3 and blue photosensitive layers 5 are not exposed.

As described above, the hologram photosensitive film 1
By using the method of red, green and blue multi-wavelength simultaneous exposure or the method of multi-wavelength sequential exposure, respectively, independent green, blue and red photosensitive layer 3,
Since green, blue, and red interference fringes are recorded on 5, 7, respectively, a color hologram having a high diffraction efficiency can be manufactured even though it is a single film.

Further, in the hologram photosensitive film 1, the photosensitive layers are laminated in the order of the green photosensitive layer 3, the blue photosensitive layer 5, and the red photosensitive layer 7, which have high visibility and large luminosity. The green photosensitive layer 3 from which the diffraction efficiency can be obtained is disposed inside the film, that is, at the position farthest from the reproduction light irradiation direction, and the red photosensitive layer 7 having a small luminous efficiency and the diffraction efficiency is difficult to be increased. This is because it is arranged at the outer side, that is, at the position closest to the irradiation direction of the reproduction light. By disposing the green, blue, and red photosensitive layers 3, 5, and 7 in this manner, a color hologram in which the luminosity and the diffraction efficiency of each color are balanced can be obtained.

The barrier layers 4 and 6 are for suppressing the movement of photopolymer molecules between the green, blue and red photosensitive layers 3, 5 and 7, and have a thickness of green, The thickness is smaller than the thickness of the blue and red photosensitive layers 3, 5, and 7, for example, about 5 μm. If the photopolymer molecules move between the photosensitive layers 3, 5 and 7 for each color, the degree of refractive index modulation decreases, and high diffraction efficiency cannot be obtained. By providing the barrier layers 4, 6 between the green, blue, and red photosensitive layers 3, 5, 7, the movement of photopolymer molecules can be suppressed, and high diffraction efficiency can be obtained.

Next, the mechanism of forming interference fringes by phase modulation when exposing such a hologram photosensitive film 1 will be described with reference to the drawings. Here, FIG. 2 is a diagram schematically showing an optical system of the color exposure system.

As shown in FIG. 2, the color exposure system includes a laser light source for emitting laser light of a predetermined wavelength,
A variable beam splitter disposed on the optical axis of the laser light from the laser light source. The variable beam splitter is for separating laser light emitted from a laser light source into reference light and object light. Here, a YAG laser 10 having a wavelength of 532 nm is used as a laser light source for green light. An Ar laser 11 having a wavelength of 477 nm is used as a blue laser light source, and a Kr laser 12 having a wavelength of 647 nm is used as a red laser light source.

The green laser G emitted from the YAG laser 10 is totally reflected by the total reflection mirror 13,
The light enters the variable beam splitter 14. Here, the light reflected by the variable beam splitter 14 is the reference light G1.
And the light transmitted through the variable beam splitter is the object light G
It becomes 2.

The blue laser B emitted from the Ar laser 11 is totally reflected by the total reflection mirror 15 and enters the variable beam splitter 16. Here, the light reflected by the variable beam splitter 16 becomes the reference light B1, and the light transmitted through the variable beam splitter becomes the object light B2.

The red laser R emitted from the Kr laser 12 is totally reflected by the total reflection mirror 17 and enters the variable beam splitter 18. Here, the light transmitted through the variable beam splitter 18 becomes the reference light R1, and the light reflected by the variable beam splitter 18 becomes the object light R1.
It becomes 2.

The reference beams G1, B1, and R1 for the respective colors separated by the variable beam splitters 14, 16, and 18 are:
The colors are synthesized by the dichroic mirrors 19 and 20. The color-combined reference light L1 is incident on the hologram photosensitive film 1 disposed on the hologram substrate 30 via the reference light beam shaping optical system 21. In the optical path of the reference light, total reflection mirrors 22, 23, and 24 for changing the traveling direction of the reference light are arranged.

On the other hand, the variable beam splitters 14, 16,
18, object light G2, B2, and R for each color
2 is color-combined by dichroic mirrors 25 and 26. The color-combined object light L2 is incident on the hologram photosensitive film 1 via the beam shaping optical system 27 for the object light. In the optical path of these object lights, a total reflection mirror 28 for changing the traveling direction of the object lights,
29 are arranged.

Here, the reference light L1 and the object light L2 are such that the reference light L1 is incident on one principal surface of the hologram photosensitive film 1 and the object light L2 is incident on the other principal surface of the hologram photosensitive film 1. I do. That is, the reference light L1 is made incident on one main surface of the hologram photosensitive film 1 at a predetermined incident angle, and
The object light L2 is incident on the other main surface of the hologram photosensitive film 1 so that the optical axis is substantially perpendicular to the hologram photosensitive film 1. As a result, the reference light L1 and the object light L2 interfere with each other on the photosensitive layers 3, 5, and 7 of the hologram photosensitive film 1, and interference fringes generated by the interference between the reference light L1 and the object light L2 are generated.
The change is recorded in the photosensitive layer of the hologram photosensitive film 1 as a change in the refractive index.

That is, as shown in FIG. 3, in the initial state, the light La having a predetermined energy or more (ie, the reference light and the reference light) is applied to the photopolymer in which the monomer 32 is uniformly dispersed in the polymer binder 31. As shown in FIG. 4, the monomer 32 in the exposed portion is polymerized according to the energy of the irradiated light La, as shown in FIG. And
As a result of the polymerization of the monomer 32, the concentration of the monomer 32 varies depending on the location. Since the refractive index of the monomer 32 is different from that of the polymer binder 31, interference fringes are recorded here by refractive index modulation, and the exposure is completed. Thereafter, as shown in FIG. 5, the residual monomer is polymerized by irradiation with the ultraviolet ray Lb, the polymerization of the monomer 32 is completed, the refractive index modulation degree is increased, and the refractive index modulation is fixed. Subsequently, by performing a heat treatment at, for example, 120 ° C. for 2 hours, the refractive index modulation degree is amplified, and the hologram fabrication is completed. In this case, the increase in the refractive index modulation is 0.02
It is about 0.04.

The process in which photopolymerization of a monomer occurs by the energy (hν) of a photon largely depends on a sensitizing dye and a reaction initiator constituting a photopolymer. That is, as shown below, first, the sensitizing dye (Dye) converts the photon energy (h
ν) is absorbed and becomes electrically excited (Equation 1).
Subsequently, the sensitizing dye (Dye ^* ) in the excited state promotes the decomposition of the radical (radical) constituting the reaction initiator (Equation 2),
Finally, this group and the chain transfer agent
nt) acts on the monomer to cause photopolymerization to form a polymer (Equation 3).

Dye → Dye ^* (Equation 1) Dye ^* + initiator → radical (Equation 2) radical + chain transfer agent + monomer → polymer (Equation 3) Thereby, the type of the sensitizing dye or the reaction initiator in the photopolymer By controlling the composition ratio and the composition ratio, the photosensitive wavelength bands of the green, blue and red photosensitive layers 3, 5, and 7 can be controlled.

The hologram photosensitive film 1 as described above
Is particularly suitable for producing a so-called thick hologram. Here, a so-called thick hologram is a hologram in which the interval between interference fringes is smaller than the thickness of the photosensitive layers 3, 5, and 7. When diffracting and reflecting an incident light beam, the wavelength and the incident angle of the incident light beam Has selectivity for

That is, in an infinitely thick hologram, the incident light for reproduction (diffraction) is reproduced (diffraction) only at the same wavelength and the same incident angle as the production light beam, and the other wavelength or In the case of the incident angle, reproduction (diffraction) is not performed, and only the 0th-order light (that is, a light beam that passes through the hologram without being diffracted) is generated.

In other words, in the case of a thick hologram, even if a light source having a broad band spectrum is used as a hologram reproducing light source, reproduction with a single wavelength is possible, and the wavelength dependence of the diffraction angle as seen when reproducing a thin hologram appears. In principle, color (multi-wavelength) reproduction without color shift is possible in principle.

In the above-described embodiment, the hologram photosensitive film 1 in which the thicknesses of the green, blue and red photosensitive layers 3, 5 and 7 are all the same has been described as an example. The thicknesses of 3, 5, and 7 may be different. The thicknesses of the green, blue, and red photosensitive layers 3, 5, and 7 affect the maximum value of the diffraction efficiency and the band of the diffraction spectrum.
As the thickness of 7 increases, the maximum value of the diffraction efficiency increases, and the band of the diffraction spectrum decreases.

Accordingly, the green, blue and red photosensitive layers 3,
The light use efficiency can be increased by controlling the thicknesses of the light source 5 and the light source 7 so as to have a diffraction spectrum band corresponding to the spectrum of the reproduction light source. For example, as shown in the spectrum of FIG. 6, when a reproducing light source having a relatively wide red bandwidth is used, the thickness of the red photosensitive layer 7 is smaller than that of the blue photosensitive layer 5 and the green photosensitive layer 3. I do. Specifically, the thickness of the green photosensitive layer 3 and the blue photosensitive layer 5 is 15 μm.
If m, the thickness of the red photosensitive layer 7 is, for example, 7 μm.

In the above-described embodiment, when exposing the hologram photosensitive film 1, multi-wavelength simultaneous exposure is performed in which red, blue and green light are combined and irradiated at one time to expose the hologram photosensitive film 1. Although described as an example, the present invention is not limited to this, in the case of multi-wavelength sequential exposure of exposing the hologram photosensitive film 1 by sequentially irradiating red, blue, and green light independently respectively Is also applicable. In this case, a bright color hologram with high diffraction efficiency can be obtained in the present invention without a fixing step between the exposure steps of the respective colors.

[0039]

According to the present invention, by providing a plurality of hologram photosensitive layers having a photosensitive action independently for each exposure wavelength in a single film, a multi-wavelength simultaneous exposure or fixing process without the step of fixing is performed. It is possible to realize a hologram photosensitive film that can obtain a hologram with high brightness and high diffraction efficiency even by sequential exposure.

Further, in the present invention, by using a hologram photosensitive film having a plurality of hologram photosensitive layers having a photosensitive action independently for each exposure wavelength, positioning of the hologram photosensitive film for each exposure wavelength can be performed. It is not necessary to increase the diffraction efficiency remarkably, and it is possible to realize an exposure method capable of obtaining a hologram with high brightness and high diffraction efficiency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one configuration example of a hologram photosensitive film of the present invention.

FIG. 2 is a schematic diagram illustrating an example of an optical system of a color exposure system that exposes a hologram photosensitive film.

FIG. 3 is a diagram illustrating the principle of recording interference fringes by phase modulation, and is a schematic diagram illustrating a state where monomers are dispersed in a polymer binder.

FIG. 4 is a diagram illustrating the principle of recording interference fringes by phase modulation, and is a schematic diagram illustrating a state in which a monomer has moved according to the brightness of the interference fringes.

FIG. 5 is a diagram for explaining the principle of recording interference fringes by phase modulation, and is a schematic diagram showing a state in which a residual monomer is photopolymerized by irradiating ultraviolet rays.

FIG. 6 is a spectrum diagram showing an example of a wavelength band of a reproduction light source.

FIG. 7 is a cross-sectional view showing one configuration example of a conventional hologram photosensitive film.

[Explanation of symbols]

1 hologram photosensitive film, 2 base film,
3 photosensitive layer for green, 4,6 barrier layer, 5 photosensitive layer for blue, 7 photosensitive layer for red, 8 cover film

Claims (8)

[Claims] 1. A hologram photosensitive film comprising at least two or more photosensitive layers, wherein the at least two or more photosensitive layers have a photosensitive action on different laser wavelength bands. 2. The hologram photosensitive film according to claim 1, wherein a barrier layer for suppressing molecular movement between the two or more photosensitive layers is disposed between the two or more photosensitive layers. 3. The hologram photosensitive film according to claim 1, wherein the two or more photosensitive layers each contain a sensitizing dye having a different laser wavelength band having a photosensitive action. 4. The hologram photosensitive film according to claim 1, wherein the two or more photosensitive layers each contain a reaction initiator having a different laser wavelength band having a photosensitive action. 5. A photosensitive layer having three photosensitive layers, each having a central wavelength of 400 nm in a laser wavelength band having a photosensitive action.
~ 500nm, 500-600nm, 600-700n
2. The hologram photosensitive film according to claim 1, wherein the hologram photosensitive film is present in m. 6. The hologram photosensitive film according to claim 1, wherein the photosensitive layer is made of a photopolymer. 7. A hologram photosensitive film having at least two or more photosensitive layers, each having a photosensitive action to a different laser wavelength band, and a laser having a wavelength band in which the two or more photosensitive layers each have a photosensitive action. By exposing the two or more photosensitive layers sequentially. 8. A hologram photosensitive film having at least two or more photosensitive layers, each having a photosensitive action to a different laser wavelength band, wherein the two or more photosensitive layers each include a wavelength zone having a photosensitive action. An exposure method, comprising exposing the two or more photosensitive layers by irradiating a laser.