JP2006349874A - Master hologram and manufacturing method thereof, and manufacturing method of phase type volume hologram optical element using master hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a pattern, such as RGB, to be recorded on a phase type volume hologram optical element by one exposure using a single laser light source, and to enable hologram to be reproduced with a small number of components easily. <P>SOLUTION: A master hologram 1 comprises a first transmission type hologram 2 having first element holograms 2R, 2G, 2B; and a second transmission hologram 3 having second element holograms 2R, 2G, 2B. The first transmission type hologram 2 and the second one 3 are overlaid with each other into a double-layer structure. The first element holograms 2R, 2G, 2B and the second ones 2R, 2G, 2B enter a photosensitive material 4 for reproducing holograms. Formation is made so that the incident angles of first luminous flux 9 and second luminous flux 10 can be controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a master hologram, a method for manufacturing the master hologram, and a method for manufacturing a phase-type volume hologram optical element using the master hologram. In particular, the present invention relates to a method for manufacturing a phase-type volume hologram optical element that uses a master hologram to replicate a transmission hologram that is pixelated into a plurality of pixel regions by an interference exposure optical system.

  Conventionally, a phase volume hologram optical element in which a refractive index modulation layer having a different refractive index is laminated in a polymer compound is known as a hologram optical element. The phase-type volume hologram optical element can transmit or diffract light having a specific wavelength according to the principle of an interference filter. Therefore, it is applied to a color filter of a projection liquid crystal display device, a hologram optical element that can reproduce a parallax image in a plurality of directions different from each other, and obtain a stereoscopic image.

  In general, the color of the diffracted light diffracted by the phase type volume hologram optical element is determined by the lattice spacing of interference fringes formed inside the phase type volume hologram optical element. The lattice spacing can be controlled by designing a two-beam interference exposure optical system.

  Specifically, as shown in FIG. 11A, the phase type volume hologram optical element causes the object light and the reference light to enter the hologram dry plate that becomes the phase type volume hologram optical element, that is, the photosensitive material 101, As shown in FIG. 11B, it is manufactured by forming interference fringes 101a on the photosensitive material 101 by exposure with these two light beams. At this time, it is formed in the photosensitive material 101 by changing the wavelength of the object light incident on the photosensitive material 101 and the wavelength of the reference light, or by changing the angle at which the object light and the reference light intersect. The lattice spacing d of the interference fringes 101a can be changed.

  In this way, a phase volume hologram optical element that diffracts or transmits an arbitrary wavelength can be manufactured. In the phase-type volume hologram optical element formed in this way, as shown in FIG. 11C, when the reproduction illumination light that is another light is illuminated, the reproduction light corresponding to the object light is generated by the diffraction. The image of the object can be reproduced.

  Here, for example, Patent Document 1 discloses an example in which a hologram element is pixelated in each pixel region such as R (red), G (green), and B (blue) and applied as a transmission color filter of a projection liquid crystal display device. Has been.

  A method of manufacturing the hologram element will be described with reference to FIG. FIG. 12 is a block diagram for explaining a manufacturing process of a hologram element applied as a transmission color filter. As shown in FIG. 12, when recording a hologram corresponding to a blue pixel of a color filter, for example, blue light is transmitted through an exposure mask 202, and this is used as object light 204 via a resolution optical system 203. The substrate 201 is irradiated. At this time, the reference beam 205 is made incident on the hologram substrate 201 together with the object beam 204, and interference fringes are formed on the hologram substrate 201 by irradiation of these two light beams. Subsequently, the interference fringes corresponding to the colors of the other colors (red and green) are similarly formed sequentially. As described above, a hologram element having interference fringes for each of the three primary colors can be formed.

  Further, Patent Document 2 discloses a manufacturing method for manufacturing a hologram that can obtain a stereoscopic image by reproducing parallax images in a plurality of different directions using a master hologram.

  With reference to FIG. 13, a method for manufacturing a transmission hologram described in Patent Document 2 will be described. FIG. 13 is a cross-sectional view for explaining a method of manufacturing a transmission hologram using a master hologram. As shown in FIG. 13, a plurality of element holograms corresponding to each pattern are formed in advance on the master hologram 302. When the laser beam 304 is incident from the spatial modulation element 303 side, the 0th-order diffracted light 305 transmitted through the light transmitting portion 308 and the master hologram 302 of the spatial modulation element 303 becomes reference light to the photosensitive material 309 of the dry plate 301, The first-order diffracted light 306 becomes object light. The reference light and the object light interfere with each other, and interference fringes are recorded on the photosensitive material 309 of the dry plate 301.

  As described above, patterns corresponding to a plurality of element holograms of the master hologram 302 can be recorded on the photosensitive material 309, and as a result, a transmission hologram can be manufactured. That is, a transmission hologram can be manufactured by replicating the pattern recorded on the master hologram 302 onto the photosensitive material 309.

  When replicating a transmission hologram using the master hologram 302, the transmission hologram can be manufactured by a single exposure. Further, since the master hologram 302 on which each pattern is formed in advance and the photosensitive material 309 are aligned and stacked, it is not necessary to align the mask or the like every time the element hologram is manufactured, thereby improving productivity. It becomes possible.

Patent Document 3 discloses a method for manufacturing a Lippmann full-color hologram. A method for manufacturing a Lippmann full-color hologram described in Patent Document 3 will be described with reference to FIG. FIG. 14 is a cross-sectional view for explaining a method for replicating a Lippmann full-color hologram. As shown in FIG. 14, for example, three copy masters 401R, 401B, and 401G for each color component of red (R), green (G), and blue (B) are viewed from three directions via a mirror 403. When the red laser reproduction illumination light is incident, the red laser reproduction illumination light is reflected from the copy masters 401R, 401B, and 401G, respectively, and is incident on the hologram photosensitive material 402 as object light. Newly incident laser reproduction illumination light interferes, and each object light having a different reproduction angle is recorded on one hologram photosensitive material 402. That is, the Lippmann full-color hologram is duplicated by performing triple exposure.
Japanese Patent Laid-Open No. 10-62784 (Publication date: March 6, 1998) Japanese Patent No. 2822798 (publication date: November 11, 1998) JP 7-104650 A (publication date: April 21, 1995)

  However, the conventional configuration has a problem that a plurality of laser light sources must be used to produce a desired hologram. Alternatively, there is a problem that the incident angle of laser light must be controlled in a large-scale optical system.

  Specifically, in the manufacturing method described in Patent Document 1, in order to form a desired pattern on the hologram substrate 201, exposure is performed using three types of exposure masks 202 corresponding to each color and three types of light sources. There is a need. Therefore, two-beam interference exposure must be performed three times, which requires time and effort, and causes a problem that the optical system becomes large-scale.

  Further, every time the hologram element is manufactured, it is necessary to accurately align the hologram substrate 201 which is a photosensitive material for the hologram element and the exposure mask 202. Therefore, there arises a problem that an operation for manufacturing the hologram element becomes complicated.

  Further, in the manufacturing method described in Patent Document 2, the reproduction of the hologram for reproducing the parallax image, that is, the reproduction of the hologram for guiding the reproduction light to the left and right eyes like the reproduction of the parallax image, in other words, For replicating a hologram that is guided to a single point, a desired pattern can be produced on a transmission type hologram by a single interference exposure using a single laser light source. However, when replicating a hologram that guides the light diffracted by the hologram in an arbitrary direction, for example, a hologram that guides light of R, G, and B wavelengths in completely different directions, that is, transmission In order to colorize a hologram of a type, light of a predetermined wavelength, that is, three types of laser light sources are required. Further, in order to replicate with one type of light source, it is necessary to control the incident angle of the laser light source, so three master holograms 302 for RGB are required. Therefore, there arises a problem that the optical system becomes large-scale.

  Moreover, in the manufacturing method described in Patent Document 3, it is necessary to accurately control the incident angle of the light source instead of being able to replicate with one light source. That is, it is necessary to accurately control the incident angle of the laser reproduction illumination light 404 incident on the mirror 403 and the angle of the mirror 403 with respect to the copy masters 401R, 401B, and 401G.

  The present invention has been made in view of the above problems, and its purpose is to record a pattern such as RGB on a phase-type volume hologram optical element by a single exposure using a single laser light source. It is possible to provide a master hologram that can be replicated with a simple and small number of components, a method for manufacturing the master hologram, and a method for manufacturing a phase-type volume hologram optical element using the master hologram.

  In order to solve the above-mentioned problem, the master hologram of the present invention is a master hologram used for replicating a hologram. For example, an element hologram corresponding to light of red (R) wavelength and light of green (G) wavelength are used. Corresponding element holograms: a first transmission hologram having a plurality of first element holograms composed of element holograms corresponding to blue (B) wavelength light, and the first element hologram includes, for example, a grating vector and a grating And a second transmission hologram having a plurality of second element holograms having different pitches, wherein the first transmission hologram and the second transmission hologram are stacked on each other. .

  In general, as an example of a method of manufacturing a hologram, for example, an element hologram corresponding to red (R) wavelength light, an element hologram corresponding to green (G) wavelength light, and blue (B) wavelength light And a method of replicating a master hologram having a plurality of element holograms composed of element holograms onto a photosensitive material. In this method, two-beam interference between zero-order diffracted light that is transmitted through the master hologram by irradiating the master hologram with laser light and first-order diffracted light diffracted by the master hologram Thus, the master hologram is replicated on the photosensitive material by forming interference fringes on the photosensitive material provided on the lower side of the master hologram.

  However, in the above method, when the master hologram has a single layer, when single-wavelength light is incident on the master hologram, for the first-order diffracted light, for example, an element hologram / green corresponding to red (R) wavelength light It is possible to control each element hologram such as an element hologram corresponding to light having a wavelength of (G) and an element hologram corresponding to light having a wavelength of blue (B) to be diffracted at an arbitrary angle. However, the 0th-order diffracted light transmitted through each element hologram cannot be controlled by any of the element holograms, so that the transmitted 0th-order diffracted light is incident on the photosensitive material at the same angle. Therefore, it is impossible to arbitrarily control both the incident angle of the 0th-order diffracted light and the diffraction angle of the 1st-order diffracted light incident on the photosensitive material with each element hologram using a single light source.

  Therefore, in the present invention, the master hologram includes a first transmission hologram having a plurality of first element holograms and a second transmission hologram having a second element hologram different from the first element hologram. And has a two-layer structure in which the first transmission hologram and the second transmission hologram are stacked on each other.

  Thereby, for example, when light having a single wavelength is incident from the first transmission hologram side, the light can be diffracted and transmitted through the plurality of first element holograms. That is, it is possible to emit light at an angle different from the incident angle as the first-order diffracted light and to emit light at the same angle as the incident light as the 0th-order diffracted light that is transmitted light. Therefore, the incident angles of the light incident on the plurality of second element holograms in the second transmission hologram are set different from or the same as the incident angles of the light incident on the first transmission hologram. Can do.

  In the plurality of second element holograms, the light emitted from the first element hologram can be diffracted as first-order diffracted light and transmitted as zero-order diffracted light. In other words, it is possible to emit light at an angle different from the incident angle and to emit light at the same emission angle as the incident angle.

  Therefore, the first transmission hologram and the second transmission hologram are stacked, so that the incident angle of the light incident on the first transmission hologram and the emission angle of the light emitted from the first transmission hologram And the emission angle of the light emitted from the second transmission hologram can be made different. That is, two light beams can be emitted from the master hologram at an angle different from the incident angle of the light incident on the master hologram. In other words, it is possible to change both the incident angle of the 0th-order diffracted light and the diffraction angle of the 1st-order diffracted light incident on the photosensitive material in each element hologram of the master hologram using a single light source.

  Therefore, a master hologram that can record a pattern such as RGB on the phase-type volume hologram optical element with a single exposure using a single laser light source, and thus can replicate a hologram simply and with a small number of parts. Can be provided.

  In the master hologram of the present invention, each first element hologram in the first transmission hologram is incident on a photosensitive material for hologram replication when light is incident from the first transmission hologram side. Each of the second element holograms in the second transmission hologram is different from the first light flux that is incident on the photosensitive material. It is preferable that the angle of incidence of the luminous flux is controlled.

  According to said structure, a 1st element hologram and a 2nd element hologram are formed so that the incident angle of the 1st light beam and the 2nd light beam which inject into the photosensitive material for hologram reproduction may be controlled, respectively. Has been. Thus, in order to duplicate the hologram, when the light is incident on the master hologram, the incident angles of the two beams incident on the photosensitive material, that is, the object beam and the reference beam of the two beam interference exposure system are set to a desired incident angle. It becomes possible to control. Therefore, element holograms that emit light of different wavelengths can be formed on each photosensitive material.

  In the master hologram of the present invention, each of the first element holograms in the first transmission hologram has a first angle by diffracting the incident light when light is incident from the first transmission hologram side. The second element hologram in the second transmission hologram is a second angle different from the first angle by diffracting the light emitted from the first element hologram. It is preferable that the grating emit light with

  According to the above configuration, light diffracted by the first transmission hologram and having a predetermined emission angle is further diffracted by the 0th-order diffracted light passing through the second transmission hologram and the second transmission hologram. Then, the light is separated into first-order diffracted light having an emission angle different from that of the zero-order diffracted light, and is emitted from the second transmission hologram. As a result, it is possible to cause interference between two light beams whose emission angles are arbitrarily controlled. Therefore, it is possible to manufacture a phase type volume hologram optical element that emits light having different wavelengths with one light source. As a result, unlike the prior art, a plurality of light sources are not required when replicating a hologram, and the apparatus can be downsized.

  In the master hologram of the present invention, the diffraction efficiency of each first element hologram in the first transmission hologram is 100%, that is, the 0th order diffracted light is 0% and the first order diffracted light is 100%. The diffraction efficiency of each of the second element holograms is preferably 50%, that is, the 0th-order diffracted light is 50% and the first-order diffracted light is 50%.

  For example, when zero-order diffracted light that is transmitted without being diffracted in the first transmission hologram is generated when light is incident on the first transmission hologram, noise may be generated when the hologram is duplicated. Specifically, extra interference fringes may be recorded on the photosensitive material due to interference between the 0th-order diffracted light and the 1st-order diffracted light in the first transmission hologram.

  However, in the above configuration, since all the light incident on the first transmission hologram is diffracted, only light having a predetermined incident angle can be incident on the second transmission hologram. That is, since the light incident on the second transmission hologram is a single light beam, there is no interference between the 0th-order diffracted light transmitted through the first transmission hologram and the diffracted 1st-order diffracted light. That is, it is possible to prevent unnecessary interference fringes from being formed when replicating the hologram. Therefore, the hologram can be duplicated with high accuracy.

  Furthermore, according to the above configuration, since the diffraction efficiency of the second transmission hologram is 50%, the light intensities of the 0th-order diffracted light and the 1st-order diffracted light in the second transmission hologram are equal. Therefore, when the 0th-order diffracted light and the 1st-order diffracted light are considered as the reference light and the object light, respectively, the contrast between the bright part and the dark part of the interference fringes due to the interference between the reference light and the object light becomes maximum. That is, the refractive index difference is maximized, the diffraction efficiency of the duplicated hologram can be increased, and the duplicated hologram can be reproduced clearly.

  In the master hologram of the present invention, the diffraction efficiency of each first element hologram in the first transmission hologram and each second element hologram in the second transmission hologram are set to a desired diffraction efficiency. Furthermore, it is preferable that the refractive index modulation of each of the refractive index changes, for example, is adjusted.

  For example, when element holograms corresponding to three colors of red (R), green (G), and blue (B) are formed on a photosensitive material, if all the element holograms have the same thickness, light of each color wavelength is used. The diffraction efficiency differs depending on the condition, and the desired diffraction efficiency cannot be obtained. Thereby, when the hologram is duplicated, the accuracy of the reproduced hologram may be lowered.

  Therefore, it is conceivable to adjust the diffraction efficiency by controlling the thickness of each element hologram of the master hologram. In this case, it is necessary to make the thickness of each element hologram different so as to correspond to the light of each wavelength. However, for example, when there are a plurality of pixels corresponding to each color of RGB like a color filter of a liquid crystal display device, it is difficult to change the thickness of the element hologram for each pixel in manufacturing the master hologram. .

  On the other hand, according to the configuration of the present invention, the diffraction efficiencies of the first element hologram and the second element hologram are adjusted by adjusting the refractive index modulation such as the refractive index variation. That is, the diffraction efficiency can be adjusted while keeping the thickness of each element hologram constant. In this case, it is only necessary to change the refractive index modulation for each element hologram, so that the manufacturing process can be prevented from becoming complicated.

  In the master hologram of the present invention, each first element hologram in the first transmission hologram and each second element hologram in the second transmission hologram are red (R), green (G), blue (B In order to replicate the hologram that diffracts light of the wavelengths of the three primary colors, it is preferably an element hologram for the three primary colors.

  According to the above configuration, the first element hologram and the second element hologram of the master hologram are element holograms for red (R), green (G), and blue (B). Colorization is possible. That is, a phase-type volume hologram optical element that emits light of different wavelengths can be manufactured.

  In order to solve the above problems, the method for producing a master hologram of the present invention is sensitive to a first photosensitive material that is sensitive to the first photosensitive wavelength and a second photosensitive wavelength that is different from the first photosensitive wavelength. A lamination step of laminating the second photosensitive material, and a grating that sensitizes the first photosensitive material with light of the first photosensitive wavelength, diffracts incident light, and emits the light at a first angle. A first exposure step for forming a first element hologram having the second photosensitive material, and a second photosensitive material is exposed to light with a second photosensitive wavelength to diffract the light emitted from the first element hologram; And a second exposure step of forming a second element hologram having a grating that is emitted at a second angle different from the one angle.

  According to the above configuration, after laminating the first photosensitive material sensitive to the first photosensitive wavelength and the second photosensitive material sensitive to the second photosensitive wavelength different from the first photosensitive wavelength, One exposure step and a second exposure step are performed.

  Thereby, the first photosensitive material and the second photosensitive material are individually subjected to the exposure process, and then compared with the case where the first element hologram and the second element hologram are aligned. Therefore, it is not necessary to align each other with high accuracy, and the master hologram can be easily manufactured.

  Furthermore, since two types of photosensitive materials having different photosensitive wavelengths are used, the first photosensitive material and the second photosensitive material are extraneous by the mutual light of the first exposure step and the second exposure step. Interference fringes are not formed, and the interference fringes can be formed with high accuracy.

  Further, the first exposure step and the second exposure step form a first element hologram having a grating that diffracts incident light and emits it at a first angle, and emits the first element hologram from the first element hologram. A second element hologram having a grating that diffracts light and emits the light at a second angle different from the first angle is formed.

  Therefore, it is possible to record a pattern such as RGB on the phase-type volume hologram optical element with a single exposure using a single laser light source, that is, a master hologram that can be replicated easily and with a small number of parts. The manufacturing method of can be provided.

  In the master hologram manufacturing method of the present invention, the first exposure step and the second exposure step are exposure steps using a mask having an opening at a predetermined position. Changing the positions of the photosensitive material and the second photosensitive material and repeating the exposure a plurality of times to form desired patterns at different positions of the first photosensitive material and the second photosensitive material. It is preferable that

  According to said structure, since it exposes using the mask which has an opening part in a predetermined position, only a desired position can be exposed.

  Further, since the exposure is repeated while changing the position of the mask, a plurality of patterns can be formed on the first photosensitive material and the second photosensitive material.

  In order to solve the above-described problem, the method for manufacturing a phase-type volume hologram optical element of the present invention is arranged such that the master hologram is disposed on the light incident surface side of a photosensitive material, and the first transmission type of the master hologram is provided. It is characterized in that light is incident from the hologram side and the hologram of the master hologram is duplicated.

  According to the above configuration, a pattern such as RGB can be recorded on the phase-type volume hologram optical element by a single exposure using a single laser light source, that is, the hologram is replicated simply and with a small number of parts. The manufacturing method of the phase type volume hologram optical element using the master hologram which can be provided can be provided. Therefore, it is advantageous in terms of throughput and cost.

  As described above, the master hologram of the present invention has a first transmission hologram having a plurality of first element holograms and a second element hologram having a plurality of second element holograms different from the first element hologram. The first transmission hologram and the second transmission hologram are laminated together.

  Therefore, it is possible to change both the incident angle of the 0th-order diffracted light incident on the photosensitive material and the diffraction angle of the 1st-order diffracted light in each element hologram of the master hologram using a single light source. Therefore, a master hologram that can record a pattern such as RGB on the phase-type volume hologram optical element with a single exposure using a single laser light source, and thus can replicate a hologram simply and with a small number of parts. There is an effect that can be provided.

  As described above, the method for producing a master hologram of the present invention includes a first photosensitive material that is sensitive to the first photosensitive wavelength, and a second photosensitive material that is sensitive to the second photosensitive wavelength different from the first photosensitive wavelength. A laminating step of laminating a photosensitive material, and a first having a grating that sensitizes the first photosensitive material with light having a first photosensitive wavelength and diffracts incident light to emit at a first angle. The first exposure step for forming the element hologram of the first and the second photosensitive material is exposed to light of the second photosensitive wavelength, and the light emitted from the first element hologram is diffracted to the first angle. And a second exposure step of forming a second element hologram having a grating that emits at a second angle different from the first exposure step.

  Therefore, it is possible to record a pattern such as RGB on a phase-type volume hologram optical element with a single exposure using a single laser light source, and thus, a master that can replicate a hologram simply and with a small number of parts. There exists an effect that the manufacturing method of a hologram can be provided.

  As described above, the manufacturing method of the phase type volume hologram optical element of the present invention is arranged such that the master hologram is disposed on the light incident surface side of the photosensitive material, and from the first transmission hologram side of the master hologram. This is a method in which light is incident and the hologram of the master hologram is duplicated.

  Therefore, it is possible to record a pattern such as RGB on a phase-type volume hologram optical element with a single exposure using a single laser light source, and thus, a master that can replicate a hologram simply and with a small number of parts. There is an effect that it is possible to provide a method of manufacturing a phase-type volume hologram optical element using a hologram. Therefore, there are excellent effects such as being advantageous in terms of throughput and cost.

  An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, for example, a phase type volume hologram optical element for use as a color filter of a liquid crystal display element will be described. However, the present invention is not limited to this.

(1) Basic principle of hologram replication technology Generally, as a method for recording a hologram on a photosensitive resin for holograms, for example, the light and darkness of interference fringes generated by causing object light and reference light to interfere with each other is used for the above photosensitive resin. There is a method of recording as a difference in refractive index.

  Here, the basic principle of a hologram duplication technique using a transmission type master hologram will be described with reference to FIG.

  As shown in FIG. 10, the master hologram 91 is composed of element holograms on which a pattern corresponding to a desired hologram is formed. Therefore, the master hologram 91 is used as an angle conversion layer for incident exposure light. The “element hologram” means a grating designed with a grating pitch and a grating vector for forming a desired pattern on the photosensitive material 92. That is, it means a hologram on which a specific pattern is formed.

The master hologram 91 of the transmission type is brought into close contact with the photosensitive material 92, the Ikko bundle of a particular wavelength lambda _a is incident by the incident angle theta _a from the master hologram 91 side to the photosensitive material 92 side. One light beam incident on the master hologram 91 is separated into zero-order diffracted light passing through the master hologram 91 and first-order diffracted light diffracted by the master hologram 91. The zero-order diffracted light and the first-order diffracted light are caused to interfere with each other, that is, two light beams are caused to interfere with each other to form interference fringes on the photosensitive material 92. At this time, an interference fringe composed of a high refractive index portion and a low refractive portion is formed in the photosensitive material 92. That is, a difference in refractive index is caused by the brightness and darkness of the light interference fringes.

Here, by controlling the incident angle θ _Oa (= θ _a ) of the zero-order diffracted light incident on the photosensitive material 92 and the incident angle θ _Ra of the first-order diffracted light, a desired grating pitch and grating can be applied to the photosensitive material 92. A grating composed of vectors can be formed. That is, a hologram that diffracts light of a specific wavelength in a specific direction can be recorded on the photosensitive material 92.

(2) Master Hologram Next, the master hologram of the present embodiment will be described with reference to FIGS. FIG. 1 is a sectional view showing a schematic configuration of a transmission master hologram. FIG. 2 is a plan view showing an arrangement state of element holograms formed on the master hologram. FIG. 3 is a plan view showing another arrangement state of the element holograms formed on the master hologram.

  As shown in FIG. 1, the master hologram 1 is composed of a first transmission hologram 2 and a second transmission hologram 3. The first transmission hologram 2 is laminated on the second transmission hologram 3. That is, the master hologram 1 has a configuration in which a first transmission hologram 2 and a second transmission hologram 3 are laminated in two layers. For the sake of explanation, the first transmission hologram 2 side will be described as the upper side, and the second transmission hologram 3 will be described as the lower side.

  Further, in FIG. 1, for the convenience of explanation, the first transmission hologram 2 and the second transmission hologram 3 are drawn in a separated state. However, in practice, the first transmission hologram 2 and the second transmission hologram 3 are in close contact with each other via PVA (polyvinyl alcohol) (not shown).

  The PVA functions as an adhesive that fixes the first transmission hologram 2 and the second transmission hologram 3. However, the adhesive is not limited to PVA, and any material can be used as long as the material has adhesiveness enough to withstand use and transmits laser light.

  Next, the first transmission hologram 2 includes a plurality of first element holograms 2R, 2G, and 2B. The first element holograms 2R, 2G, and 2B are element holograms having different grating vectors and grating pitches corresponding to three colors of red (R), green (G), and blue (B), respectively. That is, the first element holograms 2R, 2G, and 2B are patterned so as to correspond to the red (R), green (G), and blue (B) pixel regions of the liquid crystal display element. In other words, a grating in which a grating pitch and a grating vector are designed so as to correspond to the red (R), green (G), and blue (B) pixel regions of the liquid crystal display element is formed.

Specifically, in the first element holograms 2R, 2G, and 2B, laser light having a single wavelength λ ₀ incident at a predetermined incident angle θ ₀ is diffracted to different angles θ _r1 , θ _g1, and θ _b1. As shown, the grating vectors are inclined at different angles. Moreover, it is designed with a predetermined grating pitch so that the diffracted lights do not interfere with each other.

  The second transmission hologram 3 includes a plurality of second element holograms 3R, 3G, and 3B. The first element holograms 3R, 3G, and 3B are element holograms having different hologram structures corresponding to three colors of red (R), green (G), and blue (B), respectively. That is, the second transmission hologram 3 is formed with a grating in which the grating pitch and the grating vector are designed so as to correspond to the red (R), green (G), and blue (B) pixel regions of the liquid crystal display element. It has been done.

More specifically, the laser light having a single wavelength λ ₀ diffracted by the first element holograms 2R, 2G, and 2B of the first transmission hologram 2 to different angles θ _r1 , θ _g1, and θ _b1 is obtained. The grating vectors are inclined at different angles so that they are diffracted at different angles θ _r2 , θ _g2, and θ _b2 when incident on the second element holograms 3R, 3G, and 3B, respectively. Further, like the first transmission hologram 2, it is designed with a predetermined grating pitch so that the diffracted lights do not interfere with each other, and has a multilayered structure.

  The first element holograms 2R, 2G, and 2B and the second element holograms 3R, 3G, and 3B are formed so as to have different grating vectors and grating pitches.

  Next, FIG. 2 and FIG. 3 show the arrangement state of element holograms formed on the master hologram of the present embodiment. In the figure, among the reference numbers attached to the respective members, 5R and 6R are positions corresponding to R (red) element holograms, 5G and 6G are positions corresponding to G (green) element holograms, and 5B and 6B. Indicates a position corresponding to the element hologram of B (blue). For example, as shown in FIG. 2, the first element holograms 2R, 2G, and 2B and the second element holograms 3R, 3G, and 3B are divided into stripes and regularly arranged, and the first transmission holograms 2 are respectively arranged. And the second transmission hologram 3 is formed. However, it is not limited to a stripe shape, and may be formed in the first transmission hologram 2 in a matrix shape as shown in FIG.

  However, since the first element holograms 2R, 2G, and 2B correspond to the second element holograms 3R, 3G, and 3B, respectively, when one is formed in a stripe shape, the other is also in a stripe shape. Similarly, when one is formed in a matrix, the other is also in a matrix. That is, when viewed from the normal direction (ie, from the upper side to the lower side in FIG. 1), the positions of the first element holograms 2R, 2G, 2B and the second element holograms 3R, 3G, 3B coincide with each other. It has a structure.

(3) Manufacturing Method of Phase Type Volume Hologram Next, a manufacturing method for manufacturing a phase type volume hologram optical element using the master hologram of the present embodiment will be described with reference to FIG.

  First, as shown in FIG. 1, the master hologram 1 is placed in close contact with a photosensitive material 4 that will be a phase volume hologram optical element.

  At this time, in order to prevent irregular reflection of light at the interface between the master hologram 1 and the photosensitive material 4, a refractive index adjusting liquid (index) having an appropriate refractive index between the master hologram 1 and the photosensitive material 4. It is desirable to arrange a matching liquid).

  Here, as the refractive index adjusting liquid, for example, when the refractive index of the master hologram 1 is 1.50, for example, aromatic hydrocarbon benzene, toluene, xylene, and ethylbenzene having a very low refractive index are used. Can do. Here, xylene is particularly effective because of its fast drying rate.

Next, laser light having a single wavelength λ ₀ is incident on the first transmission hologram 2 at an incident angle θ ₀ . The “incident angle” means an incident angle at which the laser light is incident on a line (normal line) perpendicular to a surface (incident surface) on which the laser light is incident in the first transmission hologram 2. The “emission angle” means an emission angle at which the laser beam is emitted from the first transmission hologram 2 with respect to the normal line. Hereinafter, the same applies to the second transmission hologram 3 and the photosensitive material 4.

The laser light incident on the first transmission hologram 2 is diffracted at a predetermined angle in each of the first element holograms 2R, 2G, and 2B. That is, the laser light is diffracted at an angle of θ _r1 in the first element hologram 2R based on the inclination angle of the grating vector, θ _g1 in the first element hologram 2G, and θ _{b1 in} the first element hologram 2B.

  At this time, if the 0th-order diffracted light that is transmitted without being diffracted in the first element holograms 2R, 2G, and 2B is generated, it causes noise during the manufacture of the hologram, so the first transmission hologram 2, that is, the first element hologram It is desirable that the diffraction efficiency in 2R · 2G · 2B is approximately 100%. As a result, the incident laser light is diffracted by about 100% in the first transmission hologram 2, that is, the first element holograms 2R, 2G, and 2B.

Next, the laser light diffracted at the predetermined angles θ _r1 , θ _g1, and θ _b1 in the first element holograms 2R, 2G, and 2B of the first transmission hologram 2 is incident on the second transmission hologram 3 To do. Specifically, the laser light diffracted by the first element hologram 2R enters the element hologram 3R. Similarly, the laser beams diffracted by the first element holograms 2G and 2B are incident on the first element holograms 3G and 3B, respectively. That is, the laser light travels to the element hologram corresponding to the same color of the first transmission hologram 2 and the second transmission hologram 3.

The laser light incident on the second transmissive hologram 3 includes a first light beam 9 that is 0th-order diffracted light that passes through the second transmissive hologram 3 at the diffracted angles θ _r1 , θ _g1, and θ _b1 , respectively. The second transmission hologram 3 is separated into a second light beam 10 which is a first-order diffracted light diffracted at a predetermined angle θ _r2 · θ _g2 · θ _b2 in the plurality of element holograms 3R, 3G and 3B.

Specifically, the laser light emitted from the first element hologram 2R at the emission angle θ _r1 is separated into the first-order diffracted light at the emission angle θ _r2 and the zero-order diffracted light at the emission angle θ _{r1 at} the element hologram 3R. . Similarly, the laser light of the first element holograms 2G emitted at emission angle [theta] g _1, it emits angle element holograms 3G is separated 0-order diffracted light emission angle theta _g1 and first-order diffracted light of theta _g2. The laser beam emitted from the first element hologram 2B at the emission angle θ _b1 is separated into the first-order diffracted light at the emission angle θ _b2 and the zero-order diffracted light at the emission angle θ _{b1 at} the element hologram 3B.

  In other words, the diffraction angle of the first light beam 9 is controlled by the first transmission hologram 2. Further, the second light beam 10 is diffracted again to a desired angle by the second light transmission hologram 3 and the first light beam 9 whose diffraction angle is controlled by the first transmission hologram 2. Be controlled. As a result, a first light beam 9 and a second light beam 10 diffracted to a desired angle are generated.

  That is, it can be said that the first transmission hologram 2 is an angle conversion layer that converts incident laser light into a predetermined emission angle. That is, the laser light incident on the second transmission hologram 3 is converted into different incident angles. Similarly, it can be said that the second transmission hologram 3 is an angle conversion layer that converts light from the first transmission hologram 2 into a predetermined emission angle.

  Therefore, the first transmission hologram 2 and the second transmission hologram 3 perform interference exposure of the first light beam 9 and the second light beam 10 controlled to a desired angle as object light and reference light, respectively. Thus, a patterned transmission hologram made of a desired element hologram can be manufactured.

  In other words, the two light fluxes of the laser light intersect at different angles in each RGB area, which is each pixel area in the photosensitive material 4, so that interference fringes having different intervals are formed. In other words, the duplicated hologram has a function of reproducing laser light having a single wavelength for each primary color by using the formed grating to reproduce different reproduction wavelengths. As a result, a transmissive phase volume hologram optical element that emits light of different wavelengths can be formed.

  As described above, according to the above configuration, it is possible to form a phase type volume hologram optical element that converts each color such as RGB into a pixel by one exposure using a single laser light source.

  Moreover, according to the said structure, the master hologram 1 and the photosensitive material 4 are contact | adhered via the refractive index adjustment liquid etc. as mentioned above, and the space | interval of the master hologram 1 and the photosensitive material 4 is narrow. For this reason, a transmission type hologram composed almost of the element hologram having the pattern shape of the master hologram 1 is duplicated on the photosensitive material 4.

  In the present embodiment, the first-order diffracted light in the second transmission hologram 3 is the reference light, and the 0th-order diffracted light is the object light. Conversely, the first-order diffracted light is the object light, and the 0th-order diffracted light is the reference light. Is possible.

  Further, the diffraction efficiency of the second transmission hologram 3 needs not to include 0% and 100%. That is, it must be designed so that two light beams are generated. For example, when the diffraction efficiency is 0%, all the incident laser light is transmitted, and only one light beam is emitted from the second transmission hologram 3. On the other hand, when the diffraction efficiency is 100%, all the incident laser light is diffracted and only one light beam is emitted from the second transmission hologram 3. Therefore, in order to form interference fringes, it is necessary to newly irradiate laser light as object light or reference light. Therefore, since another laser light source is newly required, there is a possibility that the apparatus becomes large-scale.

  Furthermore, it is particularly desirable that the diffraction efficiency of the second transmission hologram 3 is approximately 50% so that the intensity of the 0th-order diffracted light and the intensity of the 1st-order diffracted light are equal. In this case, since the intensity of the 0th-order diffracted light and the intensity of the 1st-order diffracted light are equal, it becomes easier to adjust the laser light when forming interference fringes. Furthermore, the contrast between the bright part and the dark part due to the interference between the 0th-order diffracted light and the 1st-order diffracted light can be maximized. Accordingly, the refractive index difference between the high refractive index portion and the low refractive index portion formed in the photosensitive material 4 can be increased. That is, the diffraction efficiency of the hologram to be duplicated can be increased.

  On the other hand, when the diffraction efficiency of the second transmission hologram 3 is different from about 50%, when the intensity ratio between the first-order diffracted light and the zero-order diffracted light is different, the contrast between the bright part and the dark part is formed when the interference fringes are formed. Will drop. Therefore, the reproduction light of the duplicated hologram becomes dark, that is, the diffraction efficiency of the duplicated hologram may be reduced.

  However, the second transmission hologram 3 diffraction efficiency may be appropriately determined according to the intended use of the phase volume hologram optical element.

(4) Master Hologram Manufacturing Method FIGS. 5 (a) to 5 (e), FIGS. 6 (a) to 6 (c), and FIG. 7 (a) to FIG. This will be described with reference to 7 (c).

As described above, the master hologram 1 has a structure in which the first transmission hologram 2 and the second transmission hologram 3 are sequentially laminated. A first transmission hologram 2 and the second transmission hologram 3, respectively, and the first photosensitive material 12 that is sensitive by a first photosensitive wavelength lambda _1, the first photosensitive wavelength lambda ₁ is different from the second and a second photosensitive material 13 that is sensitive by the photosensitive wavelength lambda _2. A method for manufacturing the master hologram 1 will be described.

  First, as shown in FIG. 5A, a second photosensitive material 13, a transparent adhesive layer 7, and a first photosensitive material 12 are sequentially laminated on a transparent glass support substrate (not shown). That is, the first photosensitive material 12 is fixed to the second photosensitive material 13 through the transparent adhesive layer 7 while being supported by a glass support substrate (not shown).

First photosensitive material 12 is a photosensitive resin sensitive to a first photosensitive wavelength lambda _1. As the first photosensitive material 12, for example, a silver salt emulsion, dichromated gelatin, a photopolymer or the like can be used. However, the first photosensitive material 12 is not particularly limited, and a material generally used as a hologram material can be used. In addition, when a photopolymer is used, it is more effective because it is not necessary to perform a developing process and a very bright reproduced image can be displayed.

Second photosensitive material 13 is a photosensitive resin sensitive to a second photosensitive wavelength lambda _2. As the 2nd photosensitive material 13, the material similar to the 1st photosensitive material 12 can be used, for example.

  The first photosensitive material 12 and the second photosensitive material 13 are preferably substantially the same in other physical properties except that the photosensitive wavelength is different.

  The adhesive layer 7 is a transparent PVA film made of, for example, polyvinyl alcohol (PVA).

  Next, as shown in FIG. 5B, a mask 8 having an opening 14 provided at a desired position is placed on the first photosensitive material 12.

  Here, as the mask 8, for example, the masks shown in FIGS. 6A to 6C or FIGS. 7A to 7C may be used.

  Here, FIG. 6A to FIG. 6C are plan views showing the shapes of the masks used in the master hologram manufacturing method of the present embodiment. An opening is formed in each pixel region, which is a striped mask. FIGS. 7A to 7C are plan views showing the shape of a mask used in the method for manufacturing a master hologram of the present embodiment. An opening is formed in each pixel region, which is a mask in the form of a matrix.

  Of the reference numerals attached to the members in the figure, 15R, 15G, 15B, 16R, 16G, and 16B are formed on the first photosensitive material 12 and the second photosensitive material 13, respectively. The positions corresponding to the pixel regions of the respective colors of red (R), green (G), and blue (B) are shown. For example, 15R and 16R correspond to a red (R) region, 15G and 16G to a green (G) region, and 15B and 16B to a blue (B) region. Further, the hatched portion indicates the mask portion, and the white portion indicates the opening portion.

  Here, for example, when the masks shown in FIGS. 6A to 6C are used, patterns such as RGB are divided into stripes to be formed on the photosensitive material 4. On the other hand, when the masks shown in FIGS. 7A to 7C are used, patterns such as RGB are divided into a matrix and formed on the photosensitive material 4.

Next, as shown in FIG. 5 (c), the upper mask 8, than the wavelength lambda ₁ of the light source (not shown), illuminates a two-beam of wavelength lambda ₁ of the object beam and the reference beam. In the figure, arrows indicate the direction of light irradiation. The two arrows do not distinguish between reference light and object light. The two light fluxes enter the first photosensitive material 12 and the second photosensitive material 13 from the opening 14 of the mask 8. At this time, when the object light and the reference light are incident at a desired angle, the object light and the reference light intersect each other in the first photosensitive material 12. As a result, the first photosensitive material 12 is exposed to the two light beams having the wavelength λ ₁ to form interference fringes. In this way, the first element hologram 2R is formed. On the other hand, the second photosensitive material 13 is not exposed to the two light beams having the wavelength λ ₁ and maintains the state before exposure.

Subsequently, as shown in FIG. 5 (d), in a state of mounting the mask 8, through a mask 8, than the wavelength lambda ₂ of the light source (not shown), at a predetermined incident angle, wavelength lambda ₂ The two light beams of the object light and the reference light are irradiated. As a result, the first photosensitive material 12 is not exposed, and only the second photosensitive material 13 is exposed to form interference fringes. As a result, the second element hologram 3R is formed.

  Next, as shown in FIG. 5E, a plurality of masks 8 having different opening positions as shown in FIGS. 6A to 6C or FIGS. 7A to 7C are replaced. Then, the master hologram in which the first photosensitive material 12 and the second photosensitive material 13 are patterned in a stripe shape or a matrix shape by repeating the operations shown in FIGS. 1 is obtained.

  Alternatively, the same mask 8 may be used, and the mounting position of the mask 8 itself may be changed, and the operations shown in FIGS. 5B to 5D may be repeated.

  In addition, after the first transmission hologram 2 and the second transmission hologram 3 are individually manufactured, the first transmission hologram 2 and the second transmission hologram 3 are aligned and laminated, The laminated body may be used as the master hologram 1. In this case, since the same material can be used as the first photosensitive material 12 and the second photosensitive material 13, when the laser beam is incident on the master hologram 1 thus manufactured, the first transmission hologram Reflection at the interface between the second transmission hologram 3 and the second transmission hologram 3 can be prevented. Accordingly, since no reflected light is generated as noise at the time of hologram duplication at the interface, the hologram can be duplicated with high accuracy.

  In the present embodiment, the first transmission hologram 2 is formed so that the diffraction efficiency is about 100%, and the second transmission hologram 3 is formed so that the diffraction efficiency is about 50%. .

  In general, when a light source having a single wavelength is incident on a transmission hologram composed of a plurality of element holograms having different grating vectors at a certain angle, the diffraction efficiency varies depending on each element hologram.

  For example, in general, the diffraction efficiency of a transmission-type volume hologram, which is a thick transmission phase hologram, can be expressed by the relationship shown below.

η = sin ² ((πn ₁ T) / (λB cos θ _Bragg )) (1)
(N ₁ : refractive index modulation, η: diffraction efficiency, T: volume hologram thickness, θ _Bragg : Bragg angle incident angle, λ _B : Bragg wavelength)
Here, the Bragg wavelength indicates the corresponding wavelength in each of the formed first element holograms 2R, 2G, and 2B. That is, the wavelength of the R (red) region in the first element hologram 2R, the wavelength of the G (green) region in the first element hologram 2G, and the wavelength of the B (blue) region in the first element hologram 2B are black wavelengths. Equivalent to. Accordingly, the diffraction efficiency changes depending on the corresponding wavelength (wavelength of diffraction / transmission) of each element hologram.

That is, the hologram thickness T, the refractive index modulation n ₁ , the Bragg incident angle θ _Bragg , and the first element hologram 2G • 2B in the first element hologram 2R have the same conditions as the diffraction efficiency η _R = 100%. In some cases, the first element holograms 2G and 2B having different wavelengths have a diffraction efficiency of 100% or less. As a result, zero-order diffracted light is generated in the first element holograms 2G and 2B.

  Here, as described in the above section [(3) Method for producing phase-type volume hologram], when the hologram is duplicated, if light other than the necessary exposure light is generated, unnecessary interference fringes are formed on the photosensitive material 4. Therefore, the hologram cannot be duplicated with high accuracy. Therefore, in the first transmission hologram 2, it is desirable that the diffraction efficiencies of the first element holograms 2R, 2G, and 2B are approximately equal to 100%.

  Therefore, there is a method of making the diffraction efficiency of each element hologram uniform by adjusting the thickness of each element hologram. That is, from the above formula (1), it is clear that the diffraction efficiency η increases or decreases by changing the thickness T of the volume hologram.

  However, since the master hologram 1 of the present embodiment has a structure in which the first transmission hologram 2 and the second transmission hologram 3 are laminated, the first element holograms 2R, 2G, and 2B, It is difficult in manufacturing to make the thicknesses of the second element holograms 3R, 3G, and 3B different, that is, to change the thickness for each pixel.

Therefore, it is desirable to control the refractive index modulation that is the refractive index change amount of the first photosensitive material 12 and the second photosensitive material 13 in each element hologram region. In other words, it is desirable to obtain a desired diffraction efficiency by adjusting the refractive index modulation n ₁ of each of the first element holograms 2R, 2G, and 2B and the second element holograms 3R, 3G, and 3B. This makes it possible to obtain a desired diffraction efficiency without changing the thicknesses of the plurality of element holograms.

Here, the refractive index modulation n ₁ are, for example, when using a photopolymer as the photosensitive material 4, it can be controlled by the integrated exposure amount. Further, the integrated exposure amount can be adjusted by the irradiation intensity of the object light and the reference light, the irradiation time, and the like.

(5) Manufacturing Example of Master Hologram and Phase Type Volume Hologram Next, referring to FIGS. 4, 8 (a), 8 (b), and 9 based on the manufacturing method of the phase type volume hologram described above. However, an example of manufacturing a phase-type volume hologram optical element will be described.

  FIG. 4 shows a transmissive color in which element holograms that selectively diffract and transmit red (R), green (G), and blue (B) light are arranged in a matrix as the phase-type volume hologram optical element. A filter element, that is, a hologram color filter 11 is shown.

  The hologram color filter 11 includes element holograms 11R, 11G, and 11B corresponding to red (R), green (G), and blue (B) colors.

Further, the hologram color filter 11, for example, separates white light (R + G + B) incident at an incident angle θ _R = 60 ° into each RGB light, and emits each RGB light perpendicularly to the hologram color filter surface. . That is, the angle between the normal to the RGB light and the hologram color filter surface is 0 °.

Here, the wavelengths of the color lights emitted from the element holograms 11R, 11G, and 11B of the hologram color filter 11 are λ _R = 630 nm, λ _G = 550 nm, and λ _B = 460 nm, respectively. The grating pitches of the element holograms 11R, 11G, and 11B are formed to be Λ _R = 420 nm, Λ _G = 367 nm, and Λ _B = 307 nm. Further, the inclination angle of the grating vector is formed to be 30 °.

  Next, a method for calculating the gratings of the element holograms 11R, 11G, and 11B of the hologram color filter 11 will be described with reference to FIGS. 8 (a), 8 (b), and 9. FIG.

  As shown in FIG. 8A, generally, when the object light and the reference light are incident at a symmetric angle with respect to the normal line (z axis), the object light and the reference light and the formed grating vector are formed. Indicates an isosceles triangle, and the grating is formed at an angle that bisects the angle formed by the object beam and the reference beam. That is, a grating is formed on the normal line (z axis). The grating vector is orthogonal to the grating. Here, the pitch of the formed grating can be changed by changing the crossing angle between the object light and the reference light. For example, when the crossing angle is increased, the grating pitch is decreased.

  Further, as shown in FIG. 8B, when the object light and the reference light are incident at an asymmetric angle with respect to the normal line (z axis), a grating inclined with respect to the normal line (z axis) is formed. Can be formed.

  Here, the relational expression with the grating pitch, the diffraction wavelength, and the incident angle (diffraction angle) is as follows. In addition, incident light shall be fundamentally specularly reflected.

Λ = λ / (2n · sin θ) (2)
Furthermore, if the angle between the grating and the normal (z axis) is θ _off ,
θ _off = (θ ₁ + θ ₂ ) / 2 (3)
(See FIG. 9).

  Λ: grating pitch, λ: wavelength of light, θ: light incident angle (angle formed with normal (z axis)), n: refractive index of hologram. Regarding the subscripts of variables, R corresponds to the red element hologram 11R, G corresponds to the green element hologram 11G, and B corresponds to the blue element hologram 11B.

Here, for the element hologram 11R in the R region, the reproduction wavelength is λ _R = 630 nm, the reproduction light incident angle θ ₂ = 60 °, and the emission angle θ ₁ = 0 °, so that the incident light is transmitted in this way. The diffraction grating of the hologram to be diffracted is inclined by θ _{off (R) with} respect to the normal line from the equation (3). That means
θ _{off (R)} = (60 ° + 0 °) / 2 = 30 °
Will just be inclined.

Here, considering the incident angle and diffraction angle with this grating as the axis,
Incident angle: θ ₂ − (θ ₁ + θ ₂ ) / 2 = (θ ₂ −θ ₁ ) / 2
The light incident at an angle of (here, 630 nm wavelength light)
Diffraction angle: (θ ₁ + θ ₂ ) / 2−θ ₁ = (θ ₂ −θ ₁ ) / 2
Will be diffracted at an angle of. That is, the incident angle = the diffraction angle. Therefore, the grating pitch of the element hologram 11R in the R region is as follows.

Λ _R = λ / (2n · sin θ) = 630 / (2 × 1.5 × sin ((60 ° −0 °) / 2)) = 420 nm
It becomes. Similarly, the grating pitch of the element hologram 11G in the hologram color filter 11 is Λ _G = 367 nm, the element hologram 11B is Λ _B = 307 nm, and the inclination angle of the grating vector is 60 ° in each G · B region (note that the grating Can be obtained as 30 °).

  Next, a method for calculating the gratings of the first transmission hologram 2 and the second transmission hologram 3 of the master hologram 1 for duplicating the hologram color filter 11 will be described.

  For example, when the hologram color filter 11 is manufactured by irradiating the master hologram 1 with Kr light by a 407 nm wavelength krypton (Kr) laser, the grating to be formed on the master hologram 1 is shown as follows. The refractive index of the master hologram 1 is 1.5. The variable subscripts R1, G1, and B1 correspond to the first element holograms 2R, 2G, and 2B, respectively, and R2, G2, and B2 correspond to the second element holograms 3R, 3G, and 3B, respectively. And

First, in the element hologram 11R, as described above, the tilt angle θ _{off (R) of the} grating is 30 °. In order to form this grating, the incident angles of the object beam and the reference beam are set as follows using equation (2).

Here, if the angle to the required grating is θ _i ,
420 = λ _Kr / (2n · sin θ _i ) = 407 / (2 × 1.5 × sin θ _i )
Therefore, θ _i = 18.845≈18.8 °
It becomes.

In other words, the object light and the reference light are incident on the grating to be formed at an angle of θ _i ≈18.8 °. Here, since the grating is inclined by θ _{off (R)} = 30 ° with respect to the normal line of the hologram color filter surface, the angle between the object light and the reference light and the normal line of the hologram color filter surface is 30 ° + 18.8 ° = 48.8 ° and 30 ° -18.8 ° = 11.2 °.

  The first transmission hologram 2 and the second transmission hologram 3 of the master hologram 1 on which the Kr light is incident at the above angle are as follows.

For example, when transmitting and diffracting at 48.8 ° in the first element hologram 2R of the first transmission hologram 2, from equation (2), the grating pitch of the first element hologram 2R and the inclination angle of the grating vector are ,
Λ _R1 = λ _Kr / (2 · n · sin ((θ ₂ −θ ₁ ) / 2))
= 407 / (2.1.5.sin (48.8 ° -0 °) / 2)
= 328.407 nm
≒ 328nm
The grating vector is 65.6 °, that is, the angle between the inclination angle of the grating and the normal is 24.4 °.

Next, the Kr light emitted at this angle (48.8 °) is guided and incident on the second element hologram 3R of the second transmission hologram 3. Here, the second element hologram 3R is diffracted to an angle of 11.2 ° with the normal. Therefore, the grating pitch in the second element hologram 3R is similarly,
Λ _R2 = λ _Kr / (2 · n · sin ((θ ₂ −θ ₁ ) / 2))
= 407 / (2.1.5.sin ((48.8 ° -11.2 °) / 2))
= 42.9777 nm
≒ 420nm
It becomes.

  Further, the grating vector is 60 ° (the inclination angle of the grating is 30 °).

  Similarly calculated, the first transmission hologram 2 and the second transmission hologram 3 for forming the element hologram 11G in the G region and the element hologram 11B in the B region have the following gratings. Become.

That is, the first transmission hologram 2 has a grating pitch of 311 nm in the first element hologram 2G, 288 nm in the first element hologram 2B, and a tilt angle of the grating vector of 64.1 in the first element hologram 2G. ° (θ _{off (G1)} = 25.9 °), and the first element hologram 2G is composed of each element hologram of 61.8 ° (θ _{off (B1)} = 28.2 °). In the second transmission hologram 3, the grating pitch in the G region is 367 nm, the B region is 307 nm, and the inclination angle of the grating vector is 68.3 ° (θ _{off (G2)} = 21.7 ° in the G region ₎ . ), The region B is composed of element holograms of 63.7 ° (θ _{off (B2)} = 26.3 °).

  As described above, by designing the first transmission hologram 2 and the second transmission hologram 3 constituting the master hologram 1, a Kr laser 407 nm single wavelength light source as shown in FIG. The hologram color filter 11 can be manufactured by the exposure of the degree.

  Note that a grating similar to the grating formed by the Kr light can be formed on the hologram color filter 11 using only light having a wavelength different from that of the Kr light. In this case, as compared with the case where Kr light is used, the incident angles of the object light and the reference light may be appropriately changed based on the above formula (2).

  In this embodiment, the hologram color filter 11 that separates the white light incident from a certain angle into each RGB light and emits the light perpendicularly to the hologram color filter surface has been described. However, the present invention is not limited to this. . Depending on the design of the master hologram 1, for example, it is possible to manufacture a phase type volume hologram optical element that diffracts and emits RGB light incident at different angles at different desired angles.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be suitably used when manufacturing a phase-type volume hologram optical element.

It is sectional drawing which shows schematic structure of the master hologram which is one Embodiment of this invention. It is a top view which shows the arrangement | positioning state of the element hologram formed in the said master hologram. It is a top view which shows the other arrangement | positioning state of the element hologram formed in the said master hologram. It is a perspective view of the phase type volume hologram optical element which is one Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the said master hologram. It is a top view which shows the shape of the mask used when manufacturing the said master hologram. It is a top view which shows the other shape of the mask used when manufacturing the said master hologram. It is explanatory drawing for demonstrating the relationship between object light and reference light, and a grating. It is explanatory drawing for demonstrating the relationship between object light and reference light, and a grating. It is sectional drawing for demonstrating the basic principle of the replication technique of the volume hologram using a transmission type master hologram. It is explanatory drawing for demonstrating the basic principle of a hologram. It is sectional drawing for demonstrating the manufacturing method of the conventional hologram element applied as a transmission type color filter. It is sectional drawing for demonstrating the conventional method of manufacturing a transmission type hologram using a master hologram. It is sectional drawing for demonstrating the replication method of the conventional Lippmann full-color hologram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master hologram 2 1st transmission hologram 2R * 2G * 2B 1st element hologram 3 2nd transmission hologram 3R * 3G * 3B 2nd element hologram 4 Photosensitive material 7 Adhesive layer 8 Mask 9 1st Light beam 10 Second light beam 11 Hologram color filter (phase volume hologram optical element)
11R / 11G / 11B Element hologram 12 First photosensitive material 13 Second photosensitive material n ₁ Refractive index modulation (change in refractive index)
η Diffraction efficiency

Claims (9)

In the master hologram used to duplicate the hologram,
A first transmission hologram having a plurality of first element holograms, and a second transmission hologram having a plurality of second element holograms different from the first element hologram,
A master hologram, wherein the first transmission hologram and the second transmission hologram are laminated together. Each first element hologram in the first transmission hologram has an incident angle of the first light beam incident on the photosensitive material for hologram replication when light is incident from the first transmission hologram side. Formed to control,
Each second element hologram in the second transmission hologram is formed so as to control an incident angle of a second light beam that is incident on the photosensitive material and is different from the first light beam. The master hologram according to claim 1, characterized in that: Each first element hologram in the first transmission hologram is a grating that diffracts incident light and emits it at a first angle when light enters from the first transmission hologram side,
Each second element hologram in the second transmission hologram is a grating that diffracts the light emitted from each first element hologram and emits the light at a second angle different from the first angle. The master hologram according to claim 2.   The diffraction efficiency of each first element hologram in the first transmission hologram is 100%, and the diffraction efficiency of each second element hologram in the second transmission hologram is 50%. The master hologram according to claim 2 or 3.   Each of the first element holograms in the first transmission hologram and each of the second element holograms in the second transmission hologram have their respective refractive index modulations so that the respective diffraction efficiencies become a desired diffraction efficiency. The master hologram according to claim 4, wherein the master hologram is adjusted.   Each first element hologram in the first transmission hologram and each second element hologram in the second transmission hologram have wavelengths of three primary colors of red (R), green (G), and blue (B). 5. The master hologram according to claim 4, wherein the master hologram is an element hologram for three primary colors so as to duplicate a hologram that diffracts light. A laminating step of laminating a first photosensitive material sensitized by a first photosensitive wavelength and a second photosensitive material sensitized by a second photosensitive wavelength different from the first photosensitive wavelength;
A first exposure step of forming a first element hologram having a grating that sensitizes a first photosensitive material with light of a first photosensitive wavelength and diffracts incident light to emit it at a first angle. When,
The second photosensitive material is exposed to light having the second photosensitive wavelength, and the second photosensitive material is diffracted to diffract the light emitted from the first element hologram and to emit the light at a second angle different from the first angle. A method for producing a master hologram, comprising at least a second exposure step for forming a second element hologram. The first exposure step and the second exposure step are steps of exposing using a mask having an opening at a predetermined position, and
The positions of the mask and the first photosensitive material and the second photosensitive material are changed, and the exposure is repeated a plurality of times, so that a desired pattern is different between the first photosensitive material and the second photosensitive material. 8. The method of manufacturing a master hologram according to claim 7, wherein the master hologram is a step of forming at a position.   The master hologram according to any one of claims 1 to 6 is arranged on a light incident surface side of a photosensitive material, and light is incident from a first transmission hologram side of the master hologram, A method of manufacturing a phase-type volume hologram optical element, wherein a hologram of a master hologram is duplicated.

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