Hologram device and method of manufacturing hologram device

Abstract

To provide a hologram device capable of accurately reproducing a reproduced image.SOLUTION: A hologram device (15) includes a holographic color filter (10) composed of a reflection type volume hologram, and a transmission type computer-generated hologram (11) disposed in front of the holographic color filter so as to overlap the holographic color filter.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a hologram device and a method for manufacturing a hologram device. [Background technology]

[0002] Computer-generated holograms (CGHs) can reconstruct non-existent objects or scenes represented by numerical data.

[0003] Patent Document 1 describes a hologram display device that displays a full-color three-dimensional stereoscopic image using a reflective computer-generated hologram and an RGB color filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-219824 Summary of the Invention [Problem to be solved by the invention]

[0005] A typical RGB color filter selectively transmits light with a broad spectrum for each color. When the hologram display device shown in FIG. 2 of Patent Document 1 is reconstructed using natural light (continuous spectrum white light), for example, blurring occurs due to chromatic aberration. Therefore, the hologram display device described in Patent Document 1 uses a multi-chip full-color LED with narrow-band spectral characteristics as its light source, rather than a typical phosphor-type white LED. Even so, the spectrum of an LED is broader than that of a laser, and blurring still occurs in the reconstructed image. Using an RGB laser light source can further reduce blurring in the reconstructed image. However, RGB laser light sources are expensive, and the environments in which holograms can be viewed are limited.

[0006] An object of one aspect of the present invention is to provide a hologram device that can accurately reconstruct an image using light other than a laser. [Means for solving the problem]

[0007] The hologram device according to aspect 1 of the present invention comprises a holographic color filter formed by a reflective volume hologram, and a transmissive computer-generated hologram placed in front of and superimposed on the holographic color filter.

[0008] A hologram device according to a second aspect of the present invention may be configured in the first aspect above, wherein the computer-generated hologram is a transmission-type phase-modulation hologram.

[0009] A hologram device according to aspect 3 of the present invention may be configured in the above-mentioned aspect 2 such that the computer-generated hologram has a phase modulation amount set so that a reconstructed image is reconstructed by the reconstructed illumination light passing back and forth.

[0010] A hologram device according to a fourth aspect of the present invention may be configured in the second or third aspect above, wherein the computer-generated hologram has a relief on which concavities and convexities that modulate the phase of light are formed.

[0011] A hologram device according to a fifth aspect of the present invention may be configured in the first aspect above, wherein the computer-generated hologram is a transmission-type, light-absorption-type amplitude-modulation hologram.

[0012] A hologram device according to aspect 6 of the present invention may be configured such that, in any of aspects 1 to 5 above, the holographic color filter includes a first color region that reflects light of a first color and a second color region that reflects light of a second color different from the first color.

[0013] A hologram device according to aspect 7 of the present invention may be configured in any of aspects 1 to 6 above, with a plate-shaped or sheet-shaped support, and with the holographic color filter and the computer-generated hologram arranged so that the holographic color filter is sandwiched between the computer-generated hologram and the support.

[0014] A hologram device according to an eighth aspect of the present invention may be configured in any one of the first to seventh aspects above, such that a reconstructed image is reconstructed when white light is irradiated onto the hologram device from the side of the computer-generated hologram.

[0015] A method for manufacturing a hologram device according to aspect 9 of the present invention includes the steps of providing a holographic color filter composed of a reflective volume hologram, and placing a transmissive computer-generated hologram in front of the holographic color filter so as to overlap the holographic color filter.

[0016] A method for manufacturing a hologram device according to aspect 10 of the present invention may be a method in accordance with aspect 9 above, which includes a step of placing a recording material between an original color filter and a reflective member, and recording the volume hologram on the recording material by irradiating a reference beam from the side of the original color filter.

[0017] A hologram device manufacturing method according to an eleventh aspect of the present invention may be a method according to the tenth aspect, in which the spectral band reflected by the holographic color filter is narrower than the spectral band transmitted by the original color filter. [Effects of the Invention]

[0018] According to one aspect of the present invention, a hologram device can be realized that can accurately reconstruct a reconstructed image using light other than a laser. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing the configuration of a holographic color filter manufacturing apparatus according to one embodiment of the present invention. [Figure 2] FIG. 1 illustrates the spectral characteristics of a holographic color filter. [Figure 3] FIG. 1 is a diagram showing a schematic configuration of a hologram device according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a partial configuration of a hologram device according to an embodiment of the present invention. [Figure 5] 1 is a diagram showing a flow of manufacturing and reproducing a hologram device according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing a configuration of a hologram device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Embodiment 1] (Configuration of holographic color filter manufacturing apparatus 1) 1 is a diagram showing the configuration of a holographic color filter manufacturing apparatus 1. The holographic color filter manufacturing apparatus 1 includes a light source 2, dichroic mirrors 3a and 3b, mirrors 4a and 4b, a spatial filter 5, a lens 6, a master color filter 7, a recording material 8, and a reflecting member 9.

[0021] The light source 2 is a light source that emits coherent light as reference light. Here, the light source 2 emits laser light of multiple wavelengths. The light source 2 includes a first laser light source 2r, a second laser light source 2g, and a third laser light source 2b. The first laser light source 2r emits laser light of a first wavelength. The second laser light source 2g emits laser light of a second wavelength. The third laser light source 2b emits laser light of a third wavelength. The first wavelength, second wavelength, and third wavelength are different from each other. Here, the first wavelength corresponds to red, the second wavelength corresponds to green, and the third wavelength corresponds to blue. The light source 2 is a white light source that emits RGB laser light.

[0022] Dichroic mirror 3a transmits light of the first wavelength and reflects light of the second wavelength. The green laser light is reflected by mirror 4a, then by dichroic mirror 3a, and merges with the red laser light. Dichroic mirror 3b transmits light of the first and second wavelengths and reflects light of the third wavelength. The blue laser light is reflected by mirror 4b, then by dichroic mirror 3b, and merges with the red and green laser lights. The combined light of the red, green, and blue laser lights becomes reference light for creating a holographic color filter. The reference light enters spatial filter 5.

[0023] The spatial filter 5 is a filter that removes unnecessary components of the incident light, thereby making the intensity distribution of the transmitted light a predetermined distribution (for example, a Gaussian distribution). The spatial filter 5 adjusts the intensity distribution of the reference light. The reference light that has passed through the spatial filter 5 is incident on the lens 6.

[0024] The lens 6 collimates the reference light into parallel light (plane waves). The reference light that has passed through the lens 6 is incident on an original color filter 7.

[0025] The original color filter 7 is a color filter that transmits light in a specific wavelength range. For example, the original color filter 7 is a color filter used in a liquid crystal panel or the like. The original color filter 7 includes a plurality of first filter regions 7r, a plurality of second filter regions 7g, and a plurality of third filter regions 7b. For example, the linear first filter regions 7r, the linear second filter regions 7g, and the linear third filter regions 7b are each periodically arranged.

[0026] The first filter region 7r transmits light in a first spectral band (red) that includes a first wavelength and blocks light in other wavelength ranges. The first spectral band that the first filter region 7r transmits is wider than the spectral band of the laser light emitted by the first laser light source 2r. The second filter region 7g transmits light in a second spectral band (green) that includes a second wavelength and blocks light in other wavelength ranges. The second spectral band that the second filter region 7g transmits is wider than the spectral band of the laser light emitted by the second laser light source 2g. The third filter region 7b transmits light in a third spectral band (blue) that includes a third wavelength and blocks light in other wavelength ranges. The third spectral band that the third filter region 7b transmits is wider than the spectral band of the laser light emitted by the third laser light source 2b.

[0027] The recording material 8 is a photosensitive material capable of recording a volume hologram (so-called thick hologram). Examples of materials that can be used for the recording material 8 include photopolymers and silver halide films. Because photopolymers are soft, they may be attached to a substrate (such as a glass substrate) and fixed thereto. The recording material 8 here is a material before the volume hologram is recorded on it. The recording material 8 is placed over the master color filter 7. The recording material 8 is placed between the master color filter 7 and a reflective member 9. Here, the recording material 8 is directly attached to the master color filter 7, but it may also be indirectly attached via a transparent member. By fixing the recording material 8 to the master color filter 7, the effects of minute vibrations during transfer can be reduced.

[0028] The reflective member 9 reflects light of the first wavelength, the second wavelength, and the third wavelength. The reflective member 9 is attached directly to the recording material 8, but may also be attached indirectly via a transparent member.

[0029] The first filter region 7r transmits the red laser light of the incident reference light. The red laser light that passes through the first filter region 7r enters the region of the recording material 8 corresponding to the first filter region 7r, passes through the recording material 8, and is reflected by the reflecting member 9. The red laser light reflected by the reflecting member 9 passes through the recording material 8 again and passes through the first filter region 7r again. Therefore, the region of the recording material 8 corresponding to the first filter region 7r is irradiated with the red laser light incident from the first filter region 7r side and the reflected red laser light. Here, the reflected red laser light acts as the object light. The red laser light (reference light) incident from the first filter region 7r side and the reflected red laser light (object light) interfere with each other and form interference fringes on the recording material 8. The reference light and object light travel in opposite directions. Therefore, a reflection-type volume hologram that reflects (diffracts) red (first wavelength) light is formed in the region of the recording material 8 corresponding to the first filter region 7r.

[0030] The same effect occurs for laser light of other wavelengths. A reflective volume hologram that reflects green light (second wavelength) is formed in the area of ​​recording material 8 corresponding to second filter region 7g. A reflective volume hologram that reflects blue light (third wavelength) is formed in the area of ​​recording material 8 corresponding to third filter region 7b. The holographic color filter 10 is obtained by bleaching (developing) the exposed recording material 8.

[0031] The holographic color filter 10 includes a plurality of first color regions, a plurality of second color regions, and a plurality of third color regions. The plurality of first color regions are formed at positions corresponding to the plurality of first filter regions 7r of the original color filter 7. The first color regions are regions in which volume holograms that selectively reflect light of a first wavelength are formed. The plurality of second color regions are formed at positions corresponding to the plurality of second filter regions 7g of the original color filter 7. The second color regions are regions in which volume holograms that selectively reflect light of a second wavelength are formed. The plurality of third color regions are formed at positions corresponding to the plurality of third filter regions 7b of the original color filter 7. The third color regions are regions in which volume holograms that selectively reflect light of a third wavelength are formed.

[0032] FIG. 2 shows the spectral characteristics of the holographic color filter 10. The vertical axis represents reflectance or transmittance (%). The horizontal axis represents wavelength (nm). FIG. 2 plots the reflectance of the holographic color filter 10 and the transmittance of the first filter region 7r, the second filter region 7g, and the third filter region 7b of the master color filter 7. Volume holograms have high wavelength selectivity. Therefore, the spectral band reflected by each color region of the holographic color filter 10 is narrower than the spectral band transmitted by the corresponding filter region of the master color filter 7. For example, the full width at half maximum of the transmittance of the second filter region 7g is approximately 115 nm, while the full width at half maximum of the reflectance of the second color region of the holographic color filter 10 is approximately 11 nm. In this way, a holographic color filter 10 with a narrow spectral band reflected can be obtained using a master color filter 7 with a wide spectral band transmitted.

[0033] (Configuration of hologram device 15) 3 is a diagram showing a schematic configuration of hologram device 15. Hologram device 15 includes holographic color filter 10 and computer-generated hologram 11.

[0034] The holographic color filter 10 is a color filter formed by a reflective volume hologram. The holographic color filter 10 includes a plurality of first color regions 10r, a plurality of second color regions 10g, and a plurality of third color regions 10b. For example, the linear first color regions 10r, the linear second color regions 10g, and the linear third color regions 10b are each periodically arranged. The holographic color filter 10 may also include a substrate as a support for the recording material 8.

[0035] Computer-generated hologram 11 is a transmission-type hologram (a so-called thin hologram) formed by a computer-calculated hologram. Here, computer-generated hologram 11 is a transmission-type phase-modulation hologram. Computer-generated hologram 11 is disposed on the front surface (observer side) of holographic color filter 10, overlapping holographic color filter 10. Computer-generated hologram 11 includes a plurality of first diffraction regions 11r, a plurality of second diffraction regions 11g, and a plurality of third diffraction regions 11b. The plurality of first diffraction regions 11r are positioned to overlap the plurality of first color regions 10r of holographic color filter 10. The plurality of second diffraction regions 11g are positioned to overlap the plurality of second color regions 10g of holographic color filter 10. The plurality of third diffraction regions 11b are positioned to overlap the plurality of third color regions 10b of holographic color filter 10.

[0036] Computer-generated hologram 11 is created as follows. Data for first hologram 11r', second hologram 11g', and third hologram 11b' is generated by a computer. First hologram 11r' is a hologram that uses a reconstruction illumination light of a first wavelength to reconstruct a reconstructed image of a color (red) component of a first wavelength that constitutes reconstructed color image 14. Second hologram 11g' is a hologram that uses a reconstruction illumination light of a second wavelength to reconstruct a reconstructed image of a color (green) component of a second wavelength that constitutes reconstructed color image 14. Third hologram 11b' is a hologram that uses a reconstruction illumination light of a third wavelength to reconstruct a reconstructed image of a color (blue) component of a third wavelength that constitutes reconstructed color image 14. Portions of first hologram 11r' corresponding to the plurality of first color regions 10r are extracted to form the plurality of first diffraction regions 11r. Portions of second hologram 11g' corresponding to the plurality of second color regions 10g are extracted to form the plurality of second diffraction regions 11g. The portions of third hologram 11b' corresponding to the plurality of third color regions 10b are extracted to form the plurality of third diffraction regions 11b. Computer-generated hologram 11 is a hologram created using the extracted data of the plurality of first diffraction regions 11r, the data of the plurality of second diffraction regions 11g, and the data of the plurality of third diffraction regions 11b.

[0037] During reconstruction, white light W is irradiated onto hologram device 15 from the front side (the side of computer-generated hologram 11) as reconstruction illumination light. White light W has a continuous spectrum including light of a first wavelength, a second wavelength, and a third wavelength. White light W may be light from an LED light source that emits white light, or natural light. White light W passes through first diffraction region 11r and enters first color region 10r. First color region 10r selectively reflects the light of the first wavelength from white light W. The reflected light of the first wavelength passes through first diffraction region 11r again and is diffracted to become object light R of the first wavelength. The object light R of the first wavelength emitted from multiple first diffraction regions 11r forms a reconstructed image of the color (red) component of the first wavelength. Similarly, object light G of the second wavelength and object light B of the third wavelength are emitted from second diffraction region 11g and third diffraction region 11b, respectively. The object light G of the second wavelength emitted from the plurality of second diffraction regions 11g constitutes a reconstructed image of the color component of the second wavelength (green). The object light B of the third wavelength emitted from the plurality of third diffraction regions 11b constitutes a reconstructed image of the color component of the third wavelength (blue). In this way, the object light R of the first wavelength, the object light G of the second wavelength, and the object light B of the third wavelength are combined to reconstruct a color reconstructed image 14.

[0038] FIG. 4 is a cross-sectional view showing a partial configuration of hologram device 15. The observer 21 side is the front side. Hologram device 15 is illuminated from the front side with white light W, which serves as reconstruction illumination light. Here, computer-generated hologram 11 is a phase-modulation hologram. Phase-modulation holograms are advantageous in that they have high diffraction efficiency and do not reconstruct conjugate images. Computer-generated hologram 11 has substrate 12 and relief 13. Substrate 12 is a light-transmitting carrier that supports relief 13. For example, substrate 12 is a glass substrate.

[0039] Relief 13 has projections and depressions corresponding to the interference fringes of the computer-generated hologram and is provided on substrate 12. The projections and depressions formed on the surface of relief 13 modulate the phase of each component of white light W passing through in accordance with the depth of the projections and depressions. Relief 13 constitutes a phase-modulation hologram. Relief 13 is made of, for example, photoresist.

[0040] Each first diffraction region 11r may have multiple irregularities (multiple cells) in the short dimension direction of the first diffraction region 11r. Similarly, each second diffraction region 11g may have multiple irregularities in the short dimension direction of the second diffraction region 11g. Each third diffraction region 11b may have multiple irregularities in the short dimension direction of the third diffraction region 11b. The short dimension direction is the direction in which the first diffraction region 11r, the second diffraction region 11g, and the third diffraction region 11b are aligned.

[0041] Holographic color filter 10 is attached directly to the back surface of computer-generated hologram 11. Holographic color filter 10 may also be attached indirectly to computer-generated hologram 11 via a transparent member.

[0042] Of the white light W incident from the front surface of hologram device 15, the reconstruction illumination light of the first wavelength passes through first diffraction region 11r of computer-generated hologram 11, is reflected by first color region 10r, and passes through first diffraction region 11r again. The same applies to the reconstruction illumination light of the second and third wavelengths. That is, the reconstruction illumination light passes through computer-generated hologram 11 twice and is phase-modulated twice. In computer-generated hologram 11, the phase modulation amount of relief 13 is set so that the reconstruction illumination light of each wavelength passes back and forth to reconstruct a reconstructed image of each color. That is, the phase modulation amount at each position on computer-generated hologram 11 is set to half the phase modulation amount at each position on a normal hologram that reconstructs a reconstructed image with a single pass. For example, the depth of the recesses in relief 13 may be half the depth of the recesses of a normal hologram that reconstructs a reconstructed image with a single pass. Conversely, reconstruction illumination light that passes through computer-generated hologram 11 only once will not properly reconstruct a reconstruction image.

[0043] Hologram device 15 of this embodiment combines reflective holographic color filter 10 and transmissive computer-generated hologram 11. As a result, only specific light with a narrow spectral band is selectively reflected by holographic color filter 10 from the white light incident as the reconstruction illumination light. The reflected light becomes object light that forms a reconstructed image by computer-generated hologram 11. For example, only object light R of a first wavelength is emitted from first diffraction region 11r. Therefore, even when reconstruction illumination light with a broad, continuous spectrum is used, blurring of the reconstructed image can be suppressed. Therefore, hologram device 15 can accurately reconstruct a reconstructed image even with a non-laser reconstruction illumination light.

[0044] Hologram device 15 also has multiple regions (first color region 10r and first diffraction region 11r, second color region 10g and second diffraction region 11g, and third color region 10b and third diffraction region 11b) corresponding to multiple wavelengths of light, allowing hologram device 15 to reconstruct color reconstruction image 14 having multiple colors.

[0045] (Manufacturing and Reproducing Hologram Device 15) 5 is a diagram showing the flow of manufacturing and reproducing a hologram device 15. A recording material 8 is placed between an original color filter 7 and a reflective member 9. A volume hologram is recorded on the recording material 8 by irradiating it with reference light (RGB laser light) from the side of the original color filter 7 (S1). This results in a holographic color filter 10 composed of a reflective volume hologram.

[0046] Separately, a transmission-type computer-generated hologram 11 is fabricated. For example, a photoresist is provided on a substrate 12. By using laser lithography, the photoresist is irradiated with laser light at an intensity corresponding to the unevenness of the interference fringes, and the depth to which the resist is removed by development can be adjusted. This allows the formation of a relief 13 having unevenness corresponding to the interference fringes of the computer-generated hologram.

[0047] Holographic color filter 10 is provided (placed) at an arbitrary position (S2). Computer-generated hologram 11 is placed in front of holographic color filter 10 so as to overlap holographic color filter 10 (S3). This results in hologram device 15.

[0048] White light W, which is a reconstruction illumination light, is irradiated onto hologram device 15 from the side of computer-generated hologram 11, thereby reconstructing color reconstruction image 14 (S4). The reconstruction illumination light may be natural light containing light of the first wavelength, light of the second wavelength, and light of the third wavelength.

[0049] Holographic color filter 10 manufactured by the above method is composed of a reflection-type volume hologram. Therefore, computer-generated hologram 11 cannot be placed behind the color filter as in the configuration of Patent Document 1. Computer-generated hologram 11 must be placed in front of holographic color filter 10 (on the incident side of the reconstruction illumination light and on the observer 21 side). In addition, the reconstruction illumination light is phase-modulated twice by computer-generated hologram 11. Therefore, unlike the configuration of Patent Document 1 that uses a reflection-type computer-generated hologram and a normal RGB color filter, the amount of phase modulation for one modulation must be adjusted to half in hologram device 15.

[0050] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0051] 6 is a cross-sectional view showing the configuration of hologram device 16 of this embodiment. Hologram device 16 includes holographic color filter 10, computer-generated hologram 11, and support 17.

[0052] Support 17 is a plate- or sheet-like object. Support 17 carries holographic color filter 10 and computer-generated hologram 11. Support 17 may be, for example, a card equipped with an IC (integrated circuit) chip, or a sheet-like object such as a voucher or banknote.

[0053] Holographic color filter 10 and computer-generated hologram 11 are arranged on support 17 so that holographic color filter 10 is sandwiched between support 17 and computer-generated hologram 11. Here, holographic color filter 10 is arranged on one side of support 17. Computer-generated hologram 11 is arranged so as to cover holographic color filter 10. The outer surface of computer-generated hologram 11 may be covered with a protective film or the like.

[0054] A viewer positioned in front of hologram device 16 can view a reconstructed image by illuminating it with white light from the front (computer-generated hologram 11 side) of hologram device 16. In this way, hologram device 16 can accurately reconstruct a reconstructed image under white light, making it suitable for use in preventing the counterfeiting of cards, vouchers, and the like.

[0055] (Variation) When fabricating the holographic color filter 10, the optical axis of the reference light incident on the recording material 8 may or may not be perpendicular to the surface of the recording material 8. However, the direction of the reference light reflected by the reflecting member 9 is the direction of the reconstruction illumination light reflected (diffracted) by the holographic color filter 10. The reconstruction illumination light that passes through the first diffraction region 11r is preferably reflected by the holographic color filter 10 and then incident on the same first diffraction region 11r. Therefore, it is preferable that the optical axis of the reference light incident on the recording material 8 is nearly perpendicular to the surface of the recording material 8. However, this does not necessarily apply if the width of the first diffraction region 11r in the short dimension direction is sufficiently large compared to the thickness of the recording material 8. Furthermore, the optical axis of the reference light may be tilted in the long dimension direction in which the first diffraction region 11r or the first filter region 7r extends.

[0056] Computer-generated hologram 11 may be a transmission-type, light-absorbing amplitude-modulation hologram. When computer-generated hologram 11 is an amplitude-modulation hologram, there is no need to adjust the amount of phase modulation due to the reconstruction illumination light passing through it twice. In other words, an amplitude-modulation hologram that reconstructs a reconstruction image by the reconstruction illumination light passing through it once can be used as computer-generated hologram 11. Note that, if light is reflected from areas corresponding to the dark parts (blocked parts) of the interference fringes, this will affect the reconstructed image, so it is preferable that the amplitude-modulation hologram be a light-absorbing type in which the dark parts of the interference fringes absorb light.

[0057] The hologram device may have multiple color regions corresponding to multiple (two or more) wavelengths of light, and may be configured to reconstruct a multicolor reconstructed image. However, the hologram device is not limited to this. It may also be configured to include a holographic color filter that reflects light of a single wavelength and a transmission-type computer-generated hologram that diffracts light of a single wavelength. Even in this case, the wavelength selectivity of the holographic color filter allows for the use of white light to accurately reconstruct a reconstructed image composed of light of a single wavelength while suppressing blurring.

[0058] First filter region 7r, second filter region 7g, and third filter region 7b of master color filter 7 are not limited to being linear, but may be arranged in an array. In this case, the regions of holographic color filter 10 and computer-generated hologram 11 are also arranged in an array.

[0059] When producing the holographic color filter 10, the reference light incident on the master color filter 7 is not limited to a plane wave and may be, for example, a spherical wave. Furthermore, the reconstruction illumination light (white light W) that reconstructs the hologram device 15 may be either a spherical wave or a plane wave. Furthermore, the angle of incidence of the reconstruction illumination light may be different from the angle of incidence of the reference light.

[0060] A transmission type spatial light modulator may be used as computer-generated hologram 11. The computer-generated hologram may be directly displayed on the spatial light modulator.

[0061] The recessed portions of the unevenness of the relief 13 may be voids or may be filled with a medium having a refractive index different from that of the raised portions.

[0062] According to one aspect of the present invention, by using a holographic color filter in which a master color filter is recorded as a volume hologram, the spectrum becomes narrow and a clear image can be obtained even with white light. Furthermore, by using a transmission-type phase-modulation hologram or a transmission-type and light-absorbing amplitude-modulation hologram, a color computer-generated hologram can be obtained, which produces a bright reconstructed image.

[0063] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0064] 1. Holographic color filter manufacturing equipment 2 light source 2r First laser light source 2g Second laser light source 2b Third laser light source 7 Original Color Filter 7r First filter area 7g Second filter area 7b Third filter area 8 Recording material 9 Reflective material 10 Holographic Color Filter 10r 1st color area 10g second color area 10b 3rd color area 11 Computer-generated hologram 11r First diffraction region 11g Second diffraction area 11b Third diffraction region 11r' 1st hologram 11g' Second hologram 11b' Third hologram 12 PCB 13 Relief 14 Color Reconstruction 15, 16 Hologram Device 17 Support

Claims

1. a holographic color filter formed by a reflective volume hologram; a transmission-type computer-generated hologram disposed in front of and superimposed on the holographic color filter.

2. 2. The hologram device according to claim 1, wherein the computer-generated hologram is a transmission-type phase-modulation hologram.

3. 3. The hologram device according to claim 2, wherein the computer-generated hologram has a phase modulation amount set so that a reconstructed image is reconstructed by a reciprocating reconstructing illumination light passing through the hologram.

4. 3. The hologram device according to claim 2, wherein the computer-generated hologram has a relief formed with concaves and convexes that modulate the phase of light.

5. 2. The hologram device according to claim 1, wherein the computer-generated hologram is a transmission-type, light-absorption-type amplitude-modulation hologram.

6. The hologram device of claim 1 , wherein the holographic color filter includes a first color region that reflects light of a first color and a second color region that reflects light of a second color different from the first color.

7. A plate-shaped or sheet-shaped carrier is provided, 2. The hologram device according to claim 1, wherein the holographic color filter and the computer-generated hologram are arranged so that the holographic color filter is sandwiched between the computer-generated hologram and the carrier.

8. 8. The hologram device according to claim 1, wherein a reconstructed image is reconstructed when white light is irradiated onto the hologram device from the side of the computer-generated hologram.

9. providing a holographic color filter constituted by a reflective volume hologram; and placing a transmission-type computer-generated hologram in front of the holographic color filter so as to overlap the holographic color filter.

10. 10. A method for manufacturing a hologram device as described in claim 9, comprising a step of placing a recording material between an original color filter and a reflective member, and recording the volume hologram on the recording material by irradiating a reference beam from the side of the original color filter.

11. The method for manufacturing a hologram device according to claim 10 , wherein the spectral band reflected by the holographic color filter is narrower than the spectral band transmitted by the original color filter.

Images