JP3672116B2 - Hologram array replication method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for replicating a hologram array, and more particularly to a method for replicating a hologram array that can replicate the same hologram array from a hologram array such as a hologram color filter.
[0002]
[Prior art]
The hologram array can be used instead of a microlens array, for example. As one of such hologram arrays, the present applicant has proposed a hologram color filter for a liquid crystal display device in Japanese Patent Application No. 5-12170. The configuration is composed of an eccentric Fresnel zone plate-shaped micro hologram array. The hologram color filter will be briefly described below.
[0003]
A liquid crystal display device using this hologram color filter will be described with reference to the sectional view of FIG. In the figure, the hologram array 5 constituting this hologram color filter is arranged at a distance from the backlight 3 incident side of the liquid crystal display element 6 regularly divided into liquid crystal cells 6 '(pixels). On the back surface of the liquid crystal display element 6, a black matrix 4 provided between the liquid crystal cells 6 'is disposed. In addition to the above, polarizing plates (not shown) are disposed on both sides of the liquid crystal display element 6. Between the black matrix 4, as in the conventional color liquid crystal display device, an absorptive color filter that passes light of colors corresponding to R, G, and B color separation pixels is arranged. Also good.
[0004]
The hologram array 5 corresponds to the repetition period of the color separation pixels of R, G, and B, that is, the repetition pitch corresponding to each set of three liquid crystal cells 6 'adjacent in the direction in the plane of the liquid crystal display element 6. The micro holograms 5 'are arranged in an array at the same pitch. The micro holograms 5' are arranged in groups of three liquid crystal cells 6 'adjacent to each other in the direction of the surface of the liquid crystal display element 6 and arranged one by one. Each of the micro-holograms 5 ′ has three components corresponding to the micro-hologram 5 ′ with the green component light in the backlight 3 incident at an angle θ with respect to the normal line of the hologram array 5. It is formed in a Fresnel zone plate shape so as to condense on the liquid crystal cell G at the center of the color separation pixels R, G, B. The micro-hologram 5 'is formed of a transmission type hologram such as a relief type, a phase type, and an amplitude type, which has little or no wavelength dependency of diffraction efficiency. Here, the fact that the diffraction efficiency has no or little wavelength dependency means that the diffraction efficiency is not a type that diffracts only a specific wavelength and the other wavelengths do not diffract, such as a Lippmann hologram. The wavelength also means what is diffracted, and the diffraction grating having less wavelength dependency of the diffraction efficiency diffracts at different diffraction angles depending on the wavelength.
[0005]
Because of such a configuration, when the white backlight 3 incident at an angle θ with respect to the normal line is incident from the surface of the hologram array 5 opposite to the liquid crystal display element 6, it depends on the wavelength. The diffraction angles by the micro-hologram 5 ′ are different, and the condensing position for each wavelength is dispersed in a direction parallel to the surface of the hologram array 5. Among them, the red wavelength component is at the position of the liquid crystal cell R that displays red, the green component is at the position of the liquid crystal cell G that displays green, and the blue component is at the position of the liquid crystal cell B that displays blue. By arranging the hologram array 5 so as to be diffracted and condensed, each color component passes through each liquid crystal cell 6 'with almost no attenuation in the black matrix 4, and the liquid crystal cell 6' at the corresponding position is passed through. Color display according to the state can be performed.
[0006]
As described above, by using the hologram array 5 as a color filter, each wavelength component of the conventional color filter backlight can be incident on each liquid crystal cell 6 'without absorption without any waste. Can be improved.
[0007]
Such a color filter comprising a hologram array can be produced, for example, by a duplication method based on two-beam interference between multi-point convergent light and zero-order transmitted light emitted from a micro-hologram lens array comprising computer generated holograms (Japanese Patent Application No. 5-14572). No.). The duplication method will be briefly described with reference to the cross-sectional view of FIG. 4. The hologram interference fringes of the minute hologram 5 ′ are calculated by a computer. For example, the interference fringes are applied by an electron beam onto a glass substrate coated with an electron beam resist. Drawing, developing, and relief-type computer generated hologram (CGH: Computer Generated)
(Hologram) 5 ″ array 7 is manufactured. Next, as shown in FIG. 4, the hologram photosensitive material 8 is brought into intimate contact with the relief surface of the CGH array 7 thus manufactured, or is overlapped with a slight gap. Laser light 9 is incident from the CGH array 7 side at an angle θ corresponding to the backlight 3 in FIG. 3, and the convergent diffracted light 10 and the linearly transmitted light 11 generated by each CGH 5 ″ of the CGH array 7 are generated in the hologram photosensitive material 8. The CGH array 7 is duplicated with interference. This duplicated hologram is used as the hologram array 5 in FIG. The hologram array 5 can also be produced by further duplicating the duplicate hologram as an original plate.
[0008]
[Problems to be solved by the invention]
However, the hologram array 5 obtained by duplicating the CGH array 7 as an original plate by the method as shown in FIG. 4 has a very small size even if each CGH 5 ″ constituting the CGH array 7 has interference fringes drawn on the entire surface thereof. No interference fringes are recorded on the entire surface of the hologram 5 'because the hologram sensitive material 8 is usually coated with a photosensitive layer 13 on a glass substrate 12 as shown in FIG. Therefore, even if the CGH array 7 and the hologram photosensitive material 8 are brought into close contact with each other, a gap (about 50 μm) is generated between the relief surface of the CGH array 7 and the photosensitive layer 13, so that the photosensitive layer 13. This is because a region N in which the convergent diffracted light 10 is not incident is generated.
[0009]
As described above, in the duplication method as shown in FIG. 4, the area in which interference fringes are recorded becomes smaller as duplication is repeated. In addition, the focal length of the minute hologram 5 'is shortened. Furthermore, the degree of modulation of the recorded interference fringes is also reduced. Note that the distance (pitch) between the centers of the minute holograms 5 'is not changed by the duplication method as shown in FIG.
[0010]
As described above, if the interference fringe recording area of each micro-hologram 5 ′ becomes smaller than the entire area by duplication, when the backlight 3 is irradiated, a region N in which the incident light is diffracted and cannot be wavelength-dispersed is generated, and the spectral efficiency is lowered. At the same time, unnecessary 0th order light increases.
[0011]
The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a hologram array replication method capable of completely replicating the same hologram array from a hologram array master such as a hologram color filter. Is to provide.
[0012]
[Means for Solving the Problems]
The method for replicating a hologram array of the present invention that achieves the above object is a method for replicating a hologram array by optical replication from a hologram array master plate in which the element hologram is convergent. A hologram sensitive material is arranged in parallel with the hologram array master in the area to be converted into divergent light, and the reproduction illumination light is irradiated from the hologram array master, so that the diffracted light and the linearly transmitted light from each element hologram are sensed by the hologram. The method is characterized in that a duplicate hologram array of the hologram array original plate is obtained by causing interference in the material.
[0013]
In this case, the distance between the hologram array original plate and the photosensitive layer of the hologram sensitive material can be set to approximately twice the focal length of the element hologram.
[0014]
For example, a computer generated hologram array can be used as the hologram array original plate.
[0015]
Further, the obtained duplicate hologram array may be used again as a hologram array master, and may be duplicated again in the same arrangement.
[0016]
Further, as a duplicate hologram array, for example, a hologram color filter having a function of dispersing each element hologram by dispersing the wavelength of white light incident at an angle with respect to the normal of the recording surface in the direction along the recording surface. Applicable to.
[0017]
In the present invention, a hologram sensitive material is disposed in parallel with the hologram array original plate in a region where diffracted light from each element hologram is converted from convergent light to divergent light, and the reproduction illumination light is irradiated from the hologram array original plate side. In order to obtain a duplicate hologram array of the hologram array original plate by causing the diffracted light and the linearly transmitted light from each element hologram to interfere in the hologram sensitive material, the distance between the hologram array original plate and the photosensitive layer of the hologram sensitive material is Accordingly, the same hologram as the original can be duplicated to prevent the generation of a region where there is no hologram interference fringe recording and is not diffracted, and the hologram interference fringe recording region of the original can be enlarged or reduced. Furthermore, since the hologram array original plate and the hologram sensitive material can be duplicated while being separated from each other, the hologram array original plate is hardly damaged and the abrasion resistance is improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The basic principle of the present invention is that when the hologram array original plate 7 is duplicated in the arrangement as shown in FIG. 4, the recording area of each element hologram becomes inevitably small, and an area N where hologram interference fringes cannot be recorded is generated. In order to prevent this, the photosensitive layer 13 is arranged at a position twice the focal length of the element hologram, and the convergent light diffracted from each element hologram becomes divergent light, and the diameter of the cross section becomes the same as the diameter of the element hologram. By duplicating at the position, the same hologram interference fringes are recorded with the same size as the hologram array original plate 7. Note that the hologram array obtained by duplication may be duplicated again in the same manner, and as the reproduction illumination light at that time, laser light traveling in the direction opposite to the reference light 11 at the time of the first duplication is used.
[0019]
This principle will be described with reference to FIG. FIG. 1 is a diagram for explaining an embodiment in which a hologram array 5 constituting a hologram color filter is produced from a CGH array original plate 7 by one copy. As in the case of FIG. 4, the original hologram array 5 constituting the hologram color filter is configured as a CGH array 7, and the distance from the relief surface of the CGH array original plate 7 to the photosensitive layer 13 is the focal length f of each CGH 5 ″. Is set to 2f 2 times, and the hologram photosensitive material 8 is arranged apart from the CGH array original plate 7. Laser light 9 is incident from the CGH array original plate 7 side at an angle θ corresponding to the backlight 3 of FIG. The diffracted light 10 diffracted by the CGH 5 ″ of the array original plate 7 and converted from the convergent light into the divergent light and the linearly transmitted light 11 are duplicated by causing interference in the photosensitive layer 13 of the hologram photosensitive material 8.
[0020]
In this case, when the diameter of the recording area of each element hologram 5 ″ of the CGH array original plate 7 is D, the diffracted light 10 once converges from the relief surface of each CGH 5 ″ to the position P of f and the same diameter D at the position 2f. Becomes the divergent luminous flux. Therefore, when the photosensitive layer 13 is arranged at this position and interferes with the linearly transmitted light 11, the diameter of the recording area of the hologram interference fringe becomes the same D, and the pitch between the copied element holograms is also the same as that of the CGH array original plate 7. The pitch between the element holograms 5 ″ is the same. Moreover, light traveling in the direction opposite to the transmitted light 11 in the case of replicating the hologram array is incident on the hologram array thus replicated from the glass substrate 12 side. As a result, the diffracted light is collected at a position P at a distance f from the photosensitive layer 13 on which the hologram interference fringes are recorded, and becomes the same as the focal length of the element hologram 5 ″ of the CGH array original plate 7. That is, the same hologram array as the CGH array original plate 7 is duplicated.
[0021]
In the arrangement of FIG. 1, since a cover film 14 having a certain thickness is arranged on the incident side of the photosensitive layer 13, the diameter of the recording area of the hologram interference fringes in the photosensitive layer 13 is strictly slightly smaller than D. Become. Therefore, a region N (FIG. 4) in which no hologram interference fringes corresponding to the difference is recorded is generated. In order to prevent this, the distance from the relief surface of the CGH array original plate 7 to the photosensitive layer 13 may be slightly larger than 2f. In addition, the duplicated hologram array may be used with the cover film 14 attached, or may be used with the cover film 14 peeled off. Therefore, it is necessary to set the focal length of CGH5 ″.
[0022]
Further, in the case of duplication with the arrangement as shown in FIG. 1, unnecessary reflection occurs on both surfaces of the CGH array original plate 7 and the surface (back surface) opposite to the photosensitive layer 13 of the glass substrate 12, and this unnecessary reflected light and the straight transmitted light. 11 may interfere with unnecessary interference fringes. In order to prevent this, an antireflection film may be provided on at least one surface of the CGH array original plate 7 and a light absorption layer may be provided on the back surface of the glass substrate 12.
[0023]
By the way, the hologram array obtained by duplicating from the CGH array original plate 7 in the arrangement as shown in FIG. 1 is not used as the hologram color filter 5 as it is, but this duplicate hologram array is obtained by duplicating again as the original plate. A hologram array can be used as the hologram color filter 5. FIG. 2 shows an arrangement for performing such second replication. In the figure, the hologram array obtained by duplication in the arrangement of FIG. 1 is used as the intermediate hologram array H1, and the intermediate hologram array H1 is used as the original plate, and the duplication is performed again. In this case, the hologram sensitive material 8 is arranged on the original plate 7 side when the intermediate hologram array H1 is duplicated, and the reproduction illumination laser beam 9 'is on the opposite side of the hologram sensitive material 8 from the intermediate hologram array H1. Is made to enter in the direction of traveling in the opposite direction to the transmitted light 11 in the case of copying. Then, the distance from the diffraction surface of the intermediate hologram array H1 to the photosensitive layer 13 of the hologram photosensitive material 8 is set to 2f, which is twice the focal length f of the element hologram. With this arrangement, when the reproduction illumination laser light 9 'is incident on the intermediate hologram array H1, the light 10' diffracted from each element hologram of the intermediate hologram array H1 is opposite to the diffracted light 10 in FIG. Then, once converged, it becomes a divergent light beam having the same diameter D at the position 2f. Accordingly, as in the case of FIG. 1, the diffracted light 10 'and the linearly transmitted light 11' interfere with each other in the photosensitive layer 13 disposed at this position, and the same focal length f is applied to the region of the same diameter D at the pitch D. An array of element holograms is duplicated and recorded.
[0024]
In the arrangement of FIGS. 1 and 2, if the distance from the diffraction surface of the original plate 7 or H1 to the photosensitive layer 13 of the hologram sensitive material 8 is greater than 2f, the hologram interference fringe recording area is enlarged more than D, and the element hologram When the distance becomes smaller than 2f, the hologram interference fringe recording area is reduced smaller than D, and the focal distance of the element hologram becomes smaller. In any case, there is no change in the dimension of the element hologram itself (distance between the centers of adjacent element holograms: pitch).
[0025]
Therefore, when the distance from the original plate to the photosensitive layer is approximately twice the focal length of the element hologram forming the hologram array, the duplication method of the present invention generates the region N that is not diffracted by duplicating the same hologram as the original plate. If it is larger than about twice the focal length of the element hologram, to enlarge the hologram interference fringe recording area of the original (for example, draw in a smaller area rather than the entire area of the element hologram, When recording hologram interference fringes over the entire area of the element hologram by duplication), if the focal length of the element hologram is smaller than approximately twice, draw the interference fringe width wider than it actually is and use it to reduce it by duplication it can. In particular, when manufacturing a hologram color filter as described with reference to FIG. 3, the duplication method of the present invention is approximately doubled to prevent the occurrence of a region N (FIG. 4) in which incident light is diffracted and cannot be wavelength-dispersed. Are suitable. The duplication method of the present invention can also be used to increase or decrease the focal length.
[0026]
By the way, the distance between the original plate and the hologram photosensitive material at the time of duplication is controlled by adjusting the thickness of the spacer that puts the gap between the hologram original plate 7, H1 and the hologram photosensitive material 8 between them. Can do. Further, duplication may be performed while a gap between them is measured by a sensor such as a laser focus displacement meter (gap measuring machine), a contact displacement sensor, a non-contact displacement sensor, or an air sensor.
[0027]
Further, the gap between them can be duplicated while being controlled by using a focal length measuring device such as a microscope or a CCD camera by previously attaching an alignment mark to the hologram master 7, H1 or hologram sensitive material 8. . Furthermore, a hologram to be focused at an arbitrary distance is recorded on the hologram master 7, H1, or hologram sensitive material 8, and the hologram itself can be copied while controlling the gap between them using a generated image. it can.
[0028]
The hologram master 7 to be replicated has CGH5 ″ multifaceted, but is not limited to this, and may be an optically recorded hologram array. However, the present invention is not limited to this, and it is needless to say that the replication method of the present invention can be applied to replication of hologram arrays, hologram lens arrays, and the like for other purposes.
[0029]
The hologram array duplication method of the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.
[0030]
【The invention's effect】
As is apparent from the above description, according to the hologram array duplication method of the present invention, the hologram sensitive material is arranged in parallel with the hologram array master in the region where the diffracted light from each element hologram is converted from convergent light to divergent light. Then, a reproduction hologram array of the hologram array master is obtained by irradiating the reproduction illumination light from the hologram array master side and causing the diffracted light and the linearly transmitted light from each element hologram to interfere in the hologram sensitive material. Due to the distance between the array original and the photosensitive layer of the hologram photosensitive material, the same hologram as the original is duplicated to prevent the generation of non-diffracting areas where no hologram interference fringes are recorded. The area can be enlarged or reduced. Furthermore, since the hologram array original plate and the hologram sensitive material can be duplicated while being separated from each other, the hologram array original plate is hardly damaged and the abrasion resistance is improved. Note that the hologram array replication method of the present invention is particularly suitable for preventing the occurrence of a region where the incident light is diffracted and cannot be wavelength-dispersed when the hologram color filter is manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of a hologram array replication method of the present invention.
2 is a diagram showing an arrangement for performing replication again using the duplicate hologram array obtained in the arrangement of FIG. 1 as an original plate;
FIG. 3 is a cross-sectional view of a liquid crystal display device using a hologram color filter.
FIG. 4 is a cross-sectional view for explaining a conventional duplication method.
[Explanation of symbols]
5 ″… CGH
7 ... CGH array original plate 8 ... Hologram sensitive material 9 ... Laser beam 9 '... Laser beam 10 ... Convergent diffracted beam 10' ... Divergent diffracted beam 11 ... Linearly transmitted beam 13 ... Photosensitive layer H1 ... Intermediate hologram array

Claims (5)

In a method of replicating a hologram array by optical duplication from a hologram array master in which element holograms are convergent, a hologram parallel to the hologram array master in a region where diffracted light from each element hologram is converted from convergent light to divergent light A duplicate hologram array of the hologram array original plate is arranged by arranging a photosensitive material, irradiating the reproduction illumination light from the hologram array original plate side, and causing the diffracted light and the linearly transmitted light from each element hologram to interfere in the hologram sensitive material. A method for duplicating a hologram array, characterized in that: 2. The method for duplicating a hologram array according to claim 1, wherein the distance between the hologram array original plate and the photosensitive layer of the hologram sensitive material is set to approximately twice the focal length of the element hologram. 3. The hologram array duplication method according to claim 1, wherein the hologram array master comprises a computer generated hologram array. 4. The method for replicating a hologram array according to claim 1, wherein the obtained replica hologram array is used again as a hologram array master and is replicated again in the same arrangement. The duplicate hologram array is a hologram color filter having a function of dispersing each element hologram by dispersing the wavelength of white light incident at an angle with respect to the normal of the recording surface in the direction along the recording surface. 5. The method for duplicating a hologram array according to claim 1, wherein the hologram array is duplicated.

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