JP4531472B2 - Hologram creation apparatus and method - Google Patents

Description

  The present invention relates to an apparatus and method for creating a hologram by recording a number of element holograms on a photosensitive material.

  Holograms (holographic stereograms) created by recording a large number of element holograms on a photosensitive material can be used to scan laser light spatially with ordinary photographs or spatial light modulators that present images of subjects taken from various directions. Modulation is performed, an element hologram is recorded in a local area of one hologram photosensitive material using the modulated laser beam as object light, and such an element hologram is recorded for each local area. There are one-dimensional and two-dimensional holograms. In addition, a Lippmann holographic stereogram created by recording an element hologram by entering the photosensitive material from different sides of the object light and the reference light has a side where the illumination light is incident on the photosensitive material during reproduction. Since the reproduced image can be observed on the same side, it is used, for example, for wall hanging.

  Such a hologram production technique is disclosed in, for example, Patent Document 1. FIG. 5 is an explanatory diagram of a conventional hologram creation technique disclosed in Patent Document 1. In FIG. In the apparatus shown in this figure, the laser light output from the laser light source 111 is branched into two by the half mirror 112. One of the two branched laser beams sequentially enters the spatial light modulation element 115 through the mirror 113 and the lens system 114, undergoes spatial modulation by the spatial light modulation element 115, and passes through the lens 116 as object light. Then, the light enters the photosensitive material 117. The other of the laser beams branched into two by the half mirror 112 enters the photosensitive material 117 from the back as a reference light through the mirror 118.

  The object light and the reference light incident on the photosensitive material 117 interfere with each other, and an element hologram is recorded in a local area on the photosensitive material 117. Then, the image presented on the spatial light modulator 115 is changed and the photosensitive material 117 is moved, and element holograms are sequentially recorded in each of a plurality of local areas on the photosensitive material 117, thereby A Lippmann hologram is created. In this way, element holograms are recorded in an array on the photosensitive material 117 at intervals of 0.3 mm to 0.5 mm, and a Lippmann holographic stereogram is created. Further, at the time of reproduction, the illumination light is incident in the same direction as the incident direction of the reference light, whereby the reproduction light is generated from each element hologram on the photosensitive material 117, and the reproduction image can be observed on the illumination light incident side. it can.

  It is desirable that this Lippmann hologram can faithfully reproduce the intended tone of the target reproduction image. However, the gradation fidelity of the actually obtained reproduced image may be low due to the characteristics of the optical systems of the object light and the reference light and the nonlinearity of the photosensitive material.

  When the object light that has passed through the spatial light modulation element is collected by the lens and enters the photosensitive material, it becomes a light beam group having an angle corresponding to the position of the pixel of the spatial light modulation element. When the same transmittance is given to each pixel of the spatial light modulator, it is desirable that the light rays incident on the photosensitive material from each pixel have an equally spaced angle and have a constant intensity. Usually, the greater the divergence angle, the lower the intensity of the light beam. Also, it is not guaranteed that the laser beam incident on the spatial light modulator is spatially uniform, and in many cases, the laser beam has a Gaussian intensity distribution, that is, at the center of the spatial light modulator. Since the light intensity is stronger and the light intensity is weaker at the periphery, the light intensity is usually lower as the divergence angle is larger.

  Further, in many cases, the light amount of the object and the reproduction light amount are not proportional to each other due to the non-linearity of the photosensitive material, and the reproduction light amount tends to increase further in a region where the object light amount is large. On the contrary, in a region where the amount of object light is small, the amount of reproduction light decreases further, and in extreme cases, the amount of reproduction light may tend to become zero.

  As described above, in the actually obtained reproduced image, when the gradation of the target reproduced image is not reproduced faithfully, the contrast of the reproduced image of the entire hologram is emphasized, or the reproduced image has low contrast and low contrast. As a result, the intended reproduced image cannot be obtained. In particular, when aiming at a full-color hologram obtained by additionally recording an element hologram with a laser beam having a wavelength, there is a problem that it is difficult to obtain an intended color balance.

Non-Patent Document 1 and Patent Document 2 have proposed technologies intended to solve such problems. In the technique proposed in Non-Patent Document 1 (hereinafter referred to as “conventional technique 1”), an image in which the gradation of each pixel is uniform is presented to the spatial light modulation element to create an element hologram. Also, such an element hologram is created for each tone. Then, the diffraction efficiency (reproduction light amount) of the element hologram created for each gradation is measured, and from the relationship between these gradations and the reproduction light amount, the gradation of the object light necessary to obtain the intended reproduced image is obtained. Suppose that a desired reproduced image is obtained. On the other hand, in the technique proposed in Patent Document 2 (hereinafter referred to as “conventional technique 2”), light that is not monochromatic light is emitted to the recorded interference fringes during interference exposure processing, development processing, or during these processing. Irradiated, the transmitted light or diffracted light is detected and dispersed, and the hologram is evaluated.
JP-A-3-249686 Japanese Patent Laid-Open No. 5-100611 Hiroaki Shigeta, et al., “Fundamental study of color control by full parallax holographic stereogram”, 3D image conference 2003, pp.61-64, July 1, 2

  However, the above prior arts 1 and 2 have the following problems.

  First, the first problem of prior art 1 is that it is insufficient as a correction for the nonlinearity of the photosensitive material. The reason for this is that, under the assumption that the light incident on the spatial light modulator is uniform, the amount of light incident on the local area of the photosensitive material on which the element hologram is to be recorded is displayed on the spatial light modulator. This is because it is not only proportional to the luminance of the image but also proportional to the area. In the prior art 1, since the reproduction position of the color patch is the surface of the photosensitive material, the luminance of the image displayed on the spatial light modulator is uniform. However, as shown in FIG. 1, in the example, the image luminance displayed on the spatial light modulator is not uniform.

  FIG. 1 is an explanatory diagram of a photosensitive material and a reproduced image. Here, two element holograms 25 and 41 among a plurality of element holograms recorded on the photosensitive material 34 to reproduce the reproduction image 40 of the quadrangular prism object will be described. In FIG. 1 and FIGS. 2 and 3 described later, the same reference numerals are assigned to the same elements.

  An image obtained by perspective-transforming the object with the local region on the photosensitive material 34 on which the element hologram 41 is to be recorded as an origin is displayed on the spatial light modulation element, and the incident angle related to the luminance value and coordinate position of each pixel in the image is displayed. The element hologram 41 is obtained by recording a light beam having the same in the local area. The surface of the reproduction image 40 to be reproduced by the element hologram 41 substantially coincides with the position of the element hologram 41, and all the light beams generated from the element hologram 41 constitute a part of the surface of the reproduction image 40. Therefore, if the luminance value of the surface of the reproduced image 40 is uniform, the intensity of these light beam groups is also uniform. Therefore, the image 42 to be displayed on the spatial light modulator that generates these light beams is also uniform. In the image 42, the uniform range is indicated by hatching in FIG.

  On the other hand, the surface of the reproduced image 40 to be reproduced by the element hologram 25 is separated from the position of the element hologram 25. The group of rays generated by the element hologram 25 displays only the range 43 in the surface of the reproduced image 40. Only a part of the image 44 to be displayed on the spatial light modulation element that generates these light beams has a luminance value.

  Comparing the image 44 and the image 42, they are different in the area of the image displayed on the spatial light modulation element, which means that the amount of light incident on the element hologram is different. Therefore, depending on the position of the three-dimensional object to be reproduced, it means that it is not possible to accurately control the amount of incident light only by correcting the gradation information of the image presented to the new gradation information as in prior art 1. To do. In particular, if the luminance value of the object surface is not uniform and there is a pattern, it cannot be corrected.

  That is, when an object is present only in a part of the light beam generated from the element hologram, or when a pattern is present on the object, the image to be displayed on the spatial light modulator is uniform over the entire surface of the spatial light modulator. It is impossible to have a localized image having an area and a position in relation to the position of the element hologram and the position of the object. Therefore, the amount of the object light incident on the element hologram is proportional not only to the gradation of the localized image having the area and position corresponding to the position of the element hologram, but also to the area.

  Next, the second problem of prior art 1 is that it does not correct even non-uniformity due to the characteristics of the optical system. In other words, divergence occurs due to the characteristics of the optical system such as the lens and the fact that the laser beam has a Gaussian intensity distribution (that is, the light intensity increases at the center of the spatial light modulator and decreases toward the periphery). The larger the angle is, the lower the intensity of the light beam is. However, this non-uniformity is not corrected. In particular, when laser beams of a plurality of wavelengths are used on the optical axis in the same optical system, not only the beam diameters of the laser beams of the respective wavelengths are different, but also the Gaussian intensity distribution is different, and accordingly, depending on the divergence angle, The ratio of the light intensity of the object light of each wavelength is different, and the color balance changes depending on the angle. Such non-uniformity due to the characteristics of the optical system cannot be corrected.

  Furthermore, the third problem of the prior art 1 is that correction data for all cases must be prepared for correction between a plurality of wavelengths. Although the mechanism has not yet been clearly described, it is known as a well-known phenomenon that the silver salt film or the like increases the sensitivity when exposed to uniform light in advance. This indicates that the diffraction efficiency is not simply proportional to the exposure dose.

  Moreover, according to FIG. 7 in Non-Patent Document 1, it is shown that correction for a specific wavelength is not independent of correction for other wavelengths. That is, it is shown that correction cannot be performed for all wavelengths by using only correction data relating to a specific wavelength. According to FIG. 7, when the blue component is decreased and the object light intensity is weakened, the diffraction efficiency of green and blue, that is, the reproduction light amount is increased.

Therefore, in order to perform complete correction, it is necessary to measure all combinations of wavelengths and gradations and use data of necessary wavelengths obtained from the measurement results. For example, when the number of gradations of red (r), green (g), and blue (b) is 256, the number of combinations to be displayed is 16,777,216 (= 256 ³ ). Measured when (r, g, b) is combined, and the gradation of each color obtained from the result of this measurement is expressed as (r ′, g ′, b ′).
Each of r ′, g ′ and b ′ is expressed as a function of (r, g, b). Given (r ′, g ′, b ′) in the reconstructed image to be reproduced by the hologram, r ′ (r, g, b), g ′ (r, g, b) and b ′ (r, g) , b), a combination of (r, g, b) is retrieved, and if it does not exist, (r, g, b) obtained by approximation is obtained, and this (r, g, b) Is corrected by displaying on the spatial light modulation element. As described above, there is no guarantee that correction data is uniquely required, and there is a disadvantage that complicated search and conversion must be performed.

  The first problem of prior art 2 is that although a diffraction grating in a narrow range as irradiated with beam light can be evaluated from the measurement principle of the diffraction grating formed in the hologram, evaluation of the hologram in a wide area is possible. Is impossible. Evaluation of a hologram in a large area can be estimated from the evaluation result of a narrow measurement range, but such estimation is inaccurate. That is, there is a drawback that the non-uniformity due to the characteristics of the optical system cannot be corrected because the hologram creation range does not match the measurement range.

  In addition, as a second problem of the prior art 2, a diffraction grating having a plurality of wavelengths is recorded in order to perform spectral measurement by irradiating non-monochromatic light with a simple monochromatic diffraction grating hologram. When applied to a hologram, since components of a plurality of wavelengths may be reproduced at the same spectroscopic measurement position, it is inappropriate for verifying whether a faithful image pattern to be recorded has been reproduced.

  The present invention has been made to solve the above-described problems, and provides an apparatus and a method capable of easily creating a hologram capable of reproducing a reproduced image with high fidelity to a target reproduced image. With the goal.

The hologram production apparatus according to the present invention uses, as a photosensitive material, a volume phase hologram recording material that generates spatial phase modulation in accordance with interference fringes formed by the incidence of object light and reference light. an apparatus for creating a hologram element holograms by interference between reference light and object light to record the photosensitive material at each of a plurality of local regions on the photosensitive material, the target reproduction picture to be reproduced (1) A corresponding image is presented on the spatial light modulator, and the light output from the spatial light modulator on which the image is presented is incident on the local area as object light, and the reference light is also incident on the local area. Recording means for recording the element hologram in the local area by causing the light and the reference light to interfere, and (2) only the reference light is incident on the local area among the object light and the reference light over a certain period of time, (3) Comparison means for comparing the reproduction image captured by the imaging means with the target reproduction image, and (4) Comparison by the comparison means A corrected image corresponding to the result of the correction is presented to the spatial light modulation element, the light output from the spatial light modulation element on which the corrected image is presented is incident on the local region as object light, and the reference light is also incident on the local region. And an additional recording unit that causes the object beam and the reference beam to interfere with each other to additionally record the element hologram in the local region.

In addition, the hologram production method according to the present invention is a method for producing a volume phase hologram recording material that generates spatial phase modulation in accordance with interference fringes by forming interference fringes due to incidence of object light and reference light. Used to create a hologram on a photosensitive material by recording an element hologram by causing object light and reference light to interfere with each other in a plurality of local areas on the photosensitive material, and (1) target reproduction to be reproduced An image corresponding to the image is presented to the spatial light modulation element, and the light output from the spatial light modulation element on which the image is presented is incident on the local area as object light, and the reference light is also incident on the local area. A recording step of recording the element hologram in the local region by causing the object light and the reference light to interfere, and (2) the reference light of the object light and the reference light for a certain period after the recording step. An imaging step for capturing a reproduction image by reproduction light generated from the local region at this time, and (3) a comparison step for comparing the reproduction image captured in the imaging step with the target reproduction image (4) A corrected image corresponding to the comparison result in the comparison step is presented to the spatial light modulator, and the light output from the spatial light modulator on which the modified image is presented is incident on the local region as object light. And an additional recording step of additionally recording the element hologram in the local region by causing the reference beam to also enter the local region and causing the object beam and the reference beam to interfere with each other.

  A hologram creating apparatus and a hologram creating method according to the present invention create an hologram on a photosensitive material by recording an element hologram by causing object light and reference light to interfere with each other in each of a plurality of local regions on the photosensitive material. , Based on the same technical idea. In the hologram creating apparatus (method) according to the present invention, an image corresponding to a target reproduction image to be reproduced is presented to the spatial light modulation element by the recording means (in the recording step), and the spatial light modulation element on which this image is presented The light output from the light enters the local area as object light, and the reference light also enters the local area. The object light and the reference light interfere with each other, and an element hologram is recorded in the local area. Thereafter, only the reference light of the object light and the reference light is incident on the local area for a certain period by the imaging means (in the imaging step), and at this time, a reproduction image by the reproduction light generated from the local area is captured. . The reproduced image captured by the imaging unit (in the imaging step) and the target reproduced image are compared by the comparing unit (in the comparison step). Then, by the additional recording means (in the additional recording step), a corrected image corresponding to the comparison result (in the comparing step) by the comparing means is presented to the spatial light modulation element, and from the spatial light modulation element in which this corrected image is presented The output light enters the local area as object light, and the reference light also enters the local area. The object light and the reference light interfere with each other, and an element hologram is additionally recorded in the local area.

  In the hologram creating apparatus (method) according to the present invention, the target reproduction image is based on light having a plurality of wavelengths, and for each of the plurality of wavelengths, the recording means records (in the recording step) an element hologram in a local region, and the imaging means (In the imaging step) captures the reconstructed image, the comparison means (in the comparison step) compares the reconstructed image with the target reconstructed image, and the additional recording means (in the additional recording step) additionally records the element hologram in the local area It is preferable to do this.

  The hologram creating apparatus according to the present invention sequentially repeats imaging of a reproduced image by an imaging unit, comparison of a reproduced image and a target reproduced image by a comparing unit, and additional recording of an element hologram by an additional recording unit for each of a plurality of wavelengths. It is preferred to do so. In the hologram creating method according to the present invention, it is preferable that the imaging step, the comparing step, and the additional recording step are sequentially repeated for each of a plurality of wavelengths.

The hologram forming apparatus according to the present invention (method), a body volume phase hologram recording material is a soluble thermoplastic resin (A) in an organic solvent, 9,9'-and radical polymerization has a diaryl fluorene skeleton A radically polymerizable compound (B) that is solid at normal temperature and pressure and containing at least one possible unsaturated bond, a plasticizer (C), and a photopolymerization initiator (D), and comprising a thermoplastic resin (A ), Radically polymerizable compound (B) and plasticizer (C) each having a weight percentage of “(A) :( B) :( C) = 10-80: 10-80: 10-80” (however, each of these Is preferably less than 100). Furthermore, the refractive index of the radical polymerizable compound (B) is preferably larger than the weighted average of the refractive index of the thermoplastic resin (A) and the refractive index of the plasticizer (C).

  According to the present invention, a hologram capable of reproducing a reproduction image with high fidelity to the target reproduction image can be easily created.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 2 is an overall perspective view of the hologram creating apparatus according to the present embodiment. FIG. 3 is an explanatory diagram of an optical system in the hologram creating apparatus according to the present embodiment. In FIG. 2, components hidden under the photosensitive material 34 are not shown. The hologram creating apparatus according to this embodiment is an apparatus that creates a hologram on the photosensitive material 34 by recording an element hologram by causing object light and reference light to interfere with each other in a plurality of local regions on the photosensitive material 34.

The hologram creating apparatus according to the present embodiment is provided with three laser light sources 1 to 3 as a light source unit that outputs coherent light. The laser light source 1 is for outputting a laser beam of a red wavelength lambda _r, for example, a He-Ne laser light source for outputting laser light having a wavelength of 633 nm. The laser light source 2 is for outputting a laser beam in the green wavelength lambda _g, for example, Nd outputs laser light having a wavelength of 532 nm: a YAG laser light source. The laser light source 3 is for outputting a laser beam of a blue wavelength lambda _b, for example, a He-Cd laser light source for outputting laser light having a wavelength of 443 nm.

  The optical path blocker 4 is provided on the optical path immediately after the laser beam emitting end of the laser light source 1 and controls the passage and blocking of the laser beam. The optical path blocker 5 is provided on the optical path immediately after the laser beam emission end of the laser light source 2 and controls the passage and blocking of the laser beam. The optical path blocker 6 is provided on the optical path immediately after the laser beam emission end of the laser light source 3, and controls the passage and blocking of the laser beam. The passage and blocking of the laser beam in each of the optical path blockers 4 to 6 is performed based on a control signal sent from the computer 39. Each of the optical path interrupters 4 to 6 is, for example, an electromagnetic shutter or an ultrasonic deflector.

The mirror 7 and the dichroic mirrors 8 and 9 receive the laser beams that are output from the laser light sources 1 to 3 and reach them, and output them on the same optical path. That is, the dichroic mirror 8, and to reflect the output from the laser light source 3 passes through the optical path breaker 6 laser beam reflected wavelength lambda _b by the mirror 7, the optical path breaker 5 is output from the laser light source 2 by reflecting a laser beam having a wavelength lambda _g which has passed, and outputs the laser light of the laser beam and the wavelength lambda _b of the wavelength lambda _g to the dichroic mirror 9. The dichroic mirror 9, and to reflect the laser beam of the laser beam and the wavelength lambda _g of the wavelength lambda _b that reaches from the dichroic mirror 8, a laser beam having a wavelength lambda _r which is output from the laser light source 1 passes through the optical path breaker 4 The laser beams having the wavelengths λ _r , λ _g and λ _b are output to the half mirror 10 by being reflected. The half mirror 10 divides the laser beam that has arrived from the dichroic mirror 9 into two branches, outputs one of the two branched laser beams to the mirror 26, and outputs the other laser beam to the optical path blocker 11.

  The optical system that reaches the photosensitive material 34 after the mirror 26 is an optical system for reference light. The lens 27 and the lens 28 constitute an afocal optical system, which inputs laser light that has reached from the half mirror 10 via the mirror 26, expands the beam diameter, and outputs the laser light to the mask plate 29. The mask plate 29 has a rectangular opening 30 in accordance with the shape of the local region where the element hologram is recorded. The laser beam whose beam diameter has been enlarged by the lenses 27 and 28 is inputted, and the inputted laser The cross section part which injected into the opening 30 among light is output. The lens 31 and the lens 32 constitute an afocal optical system, and a mirror 33 is provided between them. The lenses 31 and 32 receive the laser light that has passed through the opening 30 of the mask plate 29 and make the laser light enter the local region 25 on the photosensitive material 34 as reference light. That is, the lenses 31 and 32 image the opening 30 of the mask plate 29 on the local region 25 on the photosensitive material 34. The mirror 33 gives an incident angle of the reference light to the local region 25.

  The optical system that reaches the photosensitive material 34 after the optical path blocker 11 is an optical system for object light. The optical path blocker 11 is provided on the optical path of the laser beam output from the half mirror 10, and controls the passage and blocking of the laser beam. The passage and blocking of the laser beam in the optical path blocker 11 is performed based on a control signal sent from the computer 39. The optical path blocker 11 is, for example, an electromagnetic shutter or an ultrasonic deflector. The lens 12 and the lens 13 constitute an afocal optical system. The laser light reaching from the optical path blocker 11 is input, the beam diameter is enlarged, and the laser light is output to the diffusion plate 14.

  The diffuser plate 14 receives the laser beam whose beam diameter is enlarged by the lenses 12 and 13 and forms the secondary light source surface 15. The lens 16 is disposed so that the diffuser plate 14 is positioned on the front focal plane, and the light emitted from the secondary light source surface 15 on the diffuser plate 14 is incident on the spatial light modulator 17. The spatial light modulation element 17 presents an image based on the image data sent from the computer 39, applies spatial intensity modulation according to the image to the light input from the lens 16, and converts the light to the light. Output as object light.

  The secondary light source surface 15 formed on the diffusion plate 14 becomes a surface light source that is farther than the spatial light modulator 17 and enlarged by the action of the lens 16. The expansion ratio of the beam diameter by the lenses 12 and 13 is set so that the average diameter of speckles generated on the spatial light modulator 17 from the surface light source 15 is equal to or smaller than the pixel pitch of the spatial light modulator 17. The diameter of the light source surface 15 is determined. This is to prevent the pixel information from being recorded in the element hologram when the dark part of the speckle speckled pattern is larger than the pixel pitch. Desirably, the diameter of the secondary light source surface 15 is preferably increased so that the average diameter of speckles is sufficiently smaller than the pixel pitch.

  The lens 18 condenses the object light output from the spatial light modulator 17 and outputs it to the mask plate 19. The mask plate 19 has a rectangular opening 20 in accordance with the shape of the local region where the element hologram is recorded. The mask plate 19 inputs the object light condensed by the lens 16 and the opening of the input object light. The cross-sectional portion incident on 20 is output. The lens 21 and the lens 24 constitute an afocal optical system, and a mirror 22 is provided on the optical path between them. The lenses 21 and 24 receive the object light that has passed through the opening 20 of the mask plate 19 and make the object light enter the local region 25 on the photosensitive material 34. That is, the lenses 21 and 24 image the opening 20 of the mask plate 19 on the local region 25 on the photosensitive material 34.

  The mask plate 19 is positioned closer to the light source than the front focal plane of the lens 21. As a result, the local region 25 on the photosensitive material 34 is positioned closer to the light source than the rear focal plane of the lens 24. This relates to the expansion of the viewing zone during hologram reproduction. That is, the maximum incident angle of the object light to the local region 25 is such that when the object light incident on the local region 25 is parallel light, the viewing area is determined only by the focal length and the aperture (that is, the numerical aperture NA) of the lens 24. Although determined, when the local region 25 is positioned on the light source side from the rear focal plane of the lens 24, the object light is incident on the local region 25 at a large incident angle, and the viewing zone is expanded.

In this case, it is important that the spatial light modulator 17 is irradiated with the surface light source 15.
The spatial light modulator 17 is disposed closer to the lens 18 than the front focal plane of the lens 18, and the image 23 of the spatial light modulator 17 by the lenses 18 and 21 is closer to the lens 24 than the front focal plane of the lens 24. Imaged. Referring also to FIG. 1, when the image 23 of the spatial light modulation element 17 is observed with the position of the element hologram 25 as a viewpoint, the image 23 is closer to the lens 24 than the front focal plane of the lens 24. The magnified virtual image 38 is observed far away by the action of the magnifying glass of the lens 24. Since the position of the element hologram 25 is closer to the lens 24 than the rear focal plane of the lens 24, an incident angle larger than the maximum incident angle determined by the numerical aperture NA of the lens 24 is obtained. In order to establish this situation, the transmitted light from each pixel of the spatial light modulator 17 has a certain emission angle, that is, the incident light to the spatial light modulator 17 has a certain incident angle. It is necessary to have. A secondary light source surface 15 having a size as a light source is formed including this purpose.

  When the reproduction light is generated by irradiating the element hologram with illumination light, the image 38 of the spatial light modulator 17 is applied to the photosensitive material 34 when the illumination light is incident in the same direction as the incident direction of the reference light. Is reproduced on the side opposite to the illumination light incident side (that is, the back side of the photosensitive material 34 for the observer). Accordingly, considering the thickness of the light beam to be reproduced, the element hologram 25 is usually larger than the pixel size of the spatial light modulation element 17 and the element hologram 25, so that the pixel of the spatial light modulation element 17 is larger. From the element hologram 25 to the observer, and the spread is expanded. Since the resolution of the reproduced three-dimensional image is determined by the thickness of the light beam, a situation in which the light beam thickness increases is not preferable.

  Therefore, the illumination light is used as conjugate light of reference light. Under the illumination light, the reproduction light from the element hologram 25 forms a real image of the spatial light modulator 17. The observer is located on the side of the illumination light, and when comparing the size of the pixel of the spatial light modulation element 17 and the size of the element hologram 25, the element hologram 25 is usually larger. The image is reproduced while being narrowed to the pixel of the light modulation element 17. Furthermore, when the condition that the observer's pupil is positioned on the real image of the spatial light modulator 17 is added and a plurality of pixels are reproduced on the observer's pupil, the focus adjustment function of the observer's eyes becomes effective. It is expected to work, and a more natural three-dimensional reproduction image can be observed.

  As described above, the mask plate 19 is disposed on the light source side from the front focal plane of the lens 21, the spatial light modulation element 17 is disposed on the lens 18 side from the front focal plane of the lens 18, and the conjugate light of the reference light Is used as illumination light to obtain a viewing angle that is equal to or larger than the viewing angle limited by the numerical aperture NA of the lens 24, and the observer's pupil becomes the position of the real image of the spatial light modulator 17. As described above, by arranging the position of the spatial light modulator 17 closer to the lens 18 than the front focal plane of the lens 18, a more natural three-dimensional reproduced image can be observed.

  The photosensitive material 34 is a volume phase hologram recording material that generates spatial phase modulation in accordance with interference fringes formed by the incidence of object light and reference light. More specifically, it is a refractive index modulation type photopolymer, and the difference between the refractive index of the exposed part and the refractive index of the unexposed part only by the recording process of irradiating the interference fringes generated by the interference of coherent light. (Preferably a difference of 0.001 or more) is generated, and a wet development process for amplifying a difference in refractive index other than a recording process or a dry development process by light or heat is not necessary. A typical example of the refractive index modulation type photopolymer used as the photosensitive material 34 is a composition containing a radical polymerizable compound that initiates polymerization by light, a photoinitiator system thereof, and a binder polymer.

  A specific example of a more suitable photopolymer is a composition for volume phase type hologram recording material used to record the intensity distribution of interference fringes as a change in refractive index, and is soluble in an organic solvent. A thermoplastic resin (A) having a 9,9′-diarylfluorene skeleton and containing at least one unsaturated bond capable of radical polymerization, and a radical polymerizable compound (B) which is solid at normal temperature and pressure, and A plasticizer (C) and a photopolymerization initiator (D) are included. The weight percentage of the thermoplastic resin (A), the radical polymerizable compound (B) and the plasticizer (C) is “(A) :( B) :( C) = 10-80: 10-80: 10-80” (However, the sum of the weight percentages of each of these is less than 100), and the refractive index of the radical polymerizable compound (B) is the refractive index of the thermoplastic resin (A) and that of the plasticizer (C). It is preferably larger than the weighted average with the refractive index.

  Specific examples of the thermoplastic resin (A) used include polyvinyl acetate, polyvinyl butyrate, polyvinyl formal, polyvinyl carbazole, polyacrylic acid, polymethacrylonitrile, polyacrylonitrile, poly-1,2-dichloroethylene, ethylene-acetic acid. Vinyl copolymer, polymethyl methacrylate, syndiotactic polymethyl methacrylate, poly-α-vinyl naphthalate, polycarbonate, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polystyrene, poly-α-methylstyrene, poly-O -Methylstyrene, poly-p-methylstyrene, poly-p-phenylstyrene, poly-p-chlorostyrene, poly-2,5-dichlorostyrene, polyarylate, polysulfone, polyethersulfone , One or a combination of two or more selected from these examples is suitable. The preferred molecular weight of these resins is 10,000 to 1,000,000.

  Specific examples of the compound suitable as the radically polymerizable compound (B) having a 9,9′-diarylfluorene skeleton and containing at least one unsaturated bond capable of radical polymerization and being solid at room temperature and normal pressure include 9 , 9-bis [4- (3-acryloyloxy-2-hydroxy) propoxyphenyl] fluorene, 9,9-bis (4-methacryloyloxyphenyl) fluorene, 9,9-bis (4-acryloyloxyphenyl) fluorene, 9,9-bis [4- (2-methacryloyloxyethoxy) phenyl] fluorene, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene, 9,9-bis {4- [2- ( 3-acryloyloxy-2-hydroxy-propoxy) -ethoxy] phenyl} fluorene, 9,9-bis [4- (3-acryloyloxy-2-hydroxy) propoxy-3-methylphenyl] fluorene, etc. And the like.

  As the plasticizer (C), phthalates represented by dimethyl phthalate, diethyl phthalate, dioctyl phthalate; dimethyl adipate, dibutyl adipate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, diethyl succinate Aliphatic dibasic acid esters; orthophosphates represented by trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresyl phosphate; acetic acid esters represented by glyceryl triacetate, 2-ethylhexyl acetate; Inactive compounds such as phosphites represented by phyte and dibutyl hydrogen phosphite are exemplified.

  As the photopolymerization initiator (D), radicals can be absorbed by absorbing laser light such as He—Ne (wavelength 633 nm), Nd: YAG (wavelength 532 nm), Ar (wavelength 515 nm, 488 nm), He—Cd (wavelength 442 nm). Those that generate are preferably used. Examples of such photopolymerization initiators include carbonyl compounds, amine compounds, arylaminoacetic acid compounds, organic tin compounds, alkylaryl boron salts, onium salts, iron arene complexes, trihalogenomethyl-substituted triazine compounds, organic peroxides. Bisimidazole derivatives, titanocene compounds, and combinations of these initiators and photosensitizing dyes are preferably used. Examples of the carbonyl compound include benzyl, benzoin ethyl ether, benzophenone, diethoxyacetophenone, and the like.

  As the photosensitizing dye, mihiraketone, acridine yellow, merocyanine, methylene blue, camphorquinone, eosin, decarboxylated rose bengal and the like are preferably used. The photosensitizing dye is not particularly limited as long as it absorbs light in the visible region. For example, cyanine derivatives, merocyanine derivatives, phthalocyanine derivatives, xanthene derivatives, thioxanthene derivatives, acridine derivatives, porphyrin derivatives, coumarin derivatives. Base styryl derivatives, ketocoumarin derivatives, quinolone derivatives, stilbene derivatives, oxazine derivatives, thiazine dyes, etc. can also be used. Furthermore, “Dye Handbook” (Shin Okawara et al., Kodansha, 1986) Photosensitizing dyes described in “Chemicals” (Shin Okawara et al., CMC, 1983) and “Special functional materials” (Tadasaburo Ikemori et al., CMC, 1986) can also be used. These may be used alone or in combination of two or more.

  The refractive index modulation type photopolymer as the photosensitive material 34 is preferably in the form of a film and has a thickness of 5 μm to 500 μm. Since the photopolymer is relatively thin and easily damaged, it is preferably coated on a substrate made of glass, quartz or resin. It is preferable that a photopolymer coated on the substrate is further provided with a cover layer made of glass, quartz or resin. The base material and the cover layer are transparent or colored so as not to reflect light. As the transparent material, transparent resins such as glass, quartz, polyethylene terephthalate (PET), acrylic resin, polycarbonate, polyolefin, and alicyclic polyolefin can be used.

  A specific example of the photosensitive material 34 is as follows. As the thermoplastic resin (A), vinyl acetate (manufactured by Wako Pure Chemical Industries, “vinyl acetate polymer methanol solution”, degree of polymerization 1400 to 1600, polymer refractive index: 1.46) is heated to remove methanol and remain. 4.2 g of polymer component is used. An acrylic acid adduct of 9,9-bis (4-hydroxyphenyl) fluorene glycidyl ether as a radical polymerizable compound (B) having a 9,9-diarylfluorene skeleton and solid at normal temperature and pressure “ASF400” manufactured by Sakai Chemical Industry Co., Ltd., 1.6 g of a single refractive index is used. As the plasticizer (C), 4.2 g of diethyl sebacate (manufactured by Wako Pure Chemical Industries, “SDE”, refractive index: 1.43) is used. As an initiator (D), 1.5 g of 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) benzophenone (manufactured by NOF Corporation, “BTTB-25”) is used. As the sensitizing dye, 0.01 g of a cyanine dye (manufactured by Nippon Photosensitive Dye, NK1538) is used. Further, 11 g of acetone is used as a solvent. And these are mixed at normal temperature and the composition for recording materials is adjusted. This composition is applied to one side of a PET substrate having a thickness of 50 μm and dried, and the thickness of the dried composition is set to 30 μm. By performing heat treatment, the solvent is removed from the composition to form a recording layer, and a recording medium having a two-layer structure composed of a PET substrate and a recording layer is produced. The recording layer of this recording medium is covered with a PET film having a thickness of 50 μm to produce a photosensitive film for hologram recording having a three-layer structure.

By using such a photosensitive material 34, the element hologram is recorded in the local region 25 only by the incidence of the object light and the reference light and the formation of interference fringes even if the development process is not performed. Therefore, after element holograms are recorded in the local region 25 for the wavelengths λ _r , λ _g, and λ _b , the incidence of object light on the local region 25 is blocked by the optical path blocker 11 and by the optical path blockers 4 to 6. By making light of any one of the wavelengths λ _r , λ _g, and λ _b enter the local region 25, a reproduced image 38 for the wavelength of the incident light can be obtained. The camera 37 captures the reproduced image 38. The computer 39 inputs the reproduced image captured by the camera 37, compares the reproduced image with the target reproduced image, and causes the spatial light modulation element 17 to present a corrected image corresponding to the comparison result. Then, the light output from the spatial light modulation element 17 on which the corrected image is presented is newly incident on the local region 25 as object light, and the reference light is also incident on the local region 25, and these object light and reference are input. Element holograms can be additionally recorded in the local region 25 by causing interference with light.

  That is, the hologram creating apparatus according to the present embodiment causes the spatial light modulation element 17 to present an image corresponding to the target reproduction image to be reproduced, and the light output from the spatial light modulation element 17 on which the image is presented to the object. The light is incident on the local region 25 and the reference light is also incident on the local region 25, and the object hologram and the reference light are caused to interfere with each other to record the element hologram in the local region 25. As a means, it includes components on the optical paths of the object light and the reference light from the light sources 1 to 3 to the photosensitive material 34.

  In addition, the hologram production apparatus according to the present embodiment causes only the reference light of the object light and the reference light to enter the local region 25 over a certain period, and the reproduced image by the reproduced light generated from the local region 25 at this time. As image pickup means for this purpose, the optical path blockers 4 to 6 and 11, a camera 37, a computer 39, and the like are provided. The hologram creating apparatus compares the picked-up reproduced image with the target reproduced image, and includes a computer 39 as a comparison means for that purpose. Further, the hologram creating apparatus presents a corrected image corresponding to the comparison result to the spatial light modulation element 17, and uses the light output from the spatial light modulation element 17 on which the corrected image is presented as object light to the local region 25. In addition, the reference light is also incident on the local area 25, the object light and the reference light are caused to interfere with each other, and an element hologram is additionally recorded in the local area 25. To the photosensitive material 34, and the like and the like on the optical path of the object light and the reference light.

  In addition, the hologram creating apparatus according to the present embodiment moves the photosensitive material 34 in the first direction parallel to the surface of the photosensitive material 34 in order to record the element hologram in each of a plurality of local regions on the photosensitive material 34. And a second moving mechanism for moving the first moving mechanism together with the photosensitive material 34 in a second direction parallel to the surface of the photosensitive material 34 and perpendicular to the first direction. For example, a linear stage is provided as a moving mechanism (not shown). These first moving mechanism and second moving mechanism move by a distance corresponding to the size of the local region 25 based on a control signal sent from the computer 39.

  The computer 39 calculates the relative positional relationship between the three-dimensional target reproduction image to be reproduced by the photosensitive material 34 and the local region 25 on which the element hologram is to be recorded, and based on the calculation result, spatial light modulation is performed. An image to be presented on the element 17 is obtained as follows. That is, when the target reproduction image to be reproduced exists on the reference light incident side of the photosensitive material 34, the center position of the element hologram 25 is symmetric with respect to the enlarged virtual image 38 of the spatial light modulation element 17 by the lens 24. Assuming a new projection screen, a three-dimensional reconstructed object perspective transformation image for this projection screen is calculated while performing hidden surface removal with the observer placed at the origin. When the target reproduction image to be reproduced exists also on the side opposite to the reference light incident side of the photosensitive material 34, the enlarged virtual image 38 by the lens 24 of the spatial light modulator 17 is used as the projection screen and the position of the element hologram 25 Is calculated while executing hidden surface removal with the observer placed at the position of the magnified virtual image 38.

The computer 39 separates the three-dimensional reconstructed object perspective transformation image into three colors of red (λ _r ), green (λ _g ), and blue (λ _b ). Presented to the light modulation element 17, the optical path blocker 4 and the optical path blocker 11 are opened for a preset exposure time, and an element hologram is recorded on the local region 25. Next, an image of the green component is presented to the spatial light modulator 17, and the optical path blocker 5 and the optical path blocker 11 are opened for a preset exposure time, and an element hologram is additionally recorded on the local region 25. Further, an image of the blue component is presented to the spatial light modulation element 17, and the optical path blocker 6 and the optical path blocker 11 are opened for a preset exposure time, and an element hologram is additionally recorded on the local area 25.

  Then, the first moving mechanism (rollers 35, 36) or the second moving mechanism is moved by the size of the local region 25, and the above exposure operation is repeated. When the element hologram has been recorded within the preset range, the recording of the hologram on the photosensitive material 34 is completed. The operation described above is merely the operation of the recording means for recording the element holograms for each of the three wavelengths. In the hologram creating apparatus according to the present embodiment, in addition to the recording means, the imaging means, the comparison means, The additional recording means operates as follows.

  Next, the operation of the hologram creating apparatus according to the present embodiment will be described, and the hologram creating method according to the present embodiment will be described. FIG. 4 is an explanatory diagram of the operation of the hologram creating apparatus according to the present embodiment. In this figure, in order from the top, the target reproduction image for each of red, green and blue, the reproduction image captured by the camera 37 for each of red, green and blue, and the spatial light modulation element 17 for each of red, green and blue. The presented images, the open / close state of the optical path interrupter 4, the open / close state of the optical path interrupter 5, the open / close state of the optical path interrupter 6, and the open / close state of the optical path interrupter 11 are shown.

  (Step S1) The computer 39 creates perspective transformation images RR, RG, RB for each wavelength to be recorded in the local region 25 at the current position.

  (Step S2) The computer 39 displays the perspective transformation image RR on the spatial light modulation element 17, opens the optical path blocker 4 and the optical path blocker 11 for TWR0 time, and locally displays the element hologram of the red component during this open period. Record in area 25.

  (Step S3) The computer 39 displays the perspective transformation image RG on the spatial light modulation element 17, opens the optical path blocker 5 and the optical path blocker 11 for TWG0 time, and locally displays the element hologram of the green component during this open period. Record in area 25.

  (Step S4) The computer 39 displays the perspective transformation image RB on the spatial light modulation element 17, opens the optical path blocker 6 and the optical path blocker 11 for TWB 0 time, and locally displays the element hologram of the blue component during this open period. Record in area 25.

  (Step S5) The computer 39 opens the optical path blocker 4 only for TR time, and acquires the reproduction image CR1 of the red component imaged by the camera 37 during this open period. When the reproduced image CR1 is equal to or smaller than a predetermined value, the following procedure is skipped.

  (Step S6) The computer 39 opens the optical path interrupter 5 for TR time, and acquires the reproduction image CG1 of the green component imaged by the camera 37 during this open period. When the reproduced image CG1 is equal to or smaller than a predetermined value, the following procedure is skipped.

  (Step S7) The computer 39 opens the optical path blocker 6 for TR time, and obtains a reproduction image CB1 of the blue component imaged by the camera 37 during this open period. When the reproduced image CB1 is equal to or smaller than a predetermined value, the following procedure is skipped.

(Step S8) The computer 39 subtracts the image obtained by multiplying the reproduction image CR1 of the red component perspective transformation image by the constant α _r determined in advance from the perspective transformation image RR to be recorded and obtains it. The corrected image (RR-α _r CR1) is displayed on the spatial light modulation element 17, the optical path blocker 4 and the optical path blocker 11 are opened for TWR1 hour, and the element hologram of the red component is displayed in the local region 25 during this open period. To make additional recordings.

(Step S9) The computer 39 subtracts an image obtained by multiplying the reproduction image CG1 of the green component perspective transformation image by the constant α _g determined in advance from the perspective transformation image RG to be recorded, and obtains it. The corrected image (RG-α _g CG1) is displayed on the spatial light modulator 17, the optical path blocker 5 and the optical path blocker 11 are opened for TWG1 time, and the element hologram of the green component is displayed in the local region 25 during this open period. To make additional recordings.

(Step S10) The computer 39 subtracts from the perspective transformation image RB to be recorded an image obtained by multiplying the reproduction image CB1 of the blue component perspective transformation image by a constant α _b determined in advance by an experiment, thereby obtaining the difference. The corrected image (RB-α _b CB1) is displayed on the spatial light modulator 17, the optical path blocker 6 and the optical path blocker 11 are opened for TWB1 time, and the element hologram of the blue component is displayed in the local region 25 during this open period. To make additional recordings.

  Thereafter, steps S5 to S10 are repeated until the difference between the captured reproduced image and the target reproduced image is equal to or smaller than a predetermined threshold value. In addition, said step S2-S4 is corresponded to the recording step in the hologram production method which concerns on this embodiment. Steps S5 to S7 correspond to an imaging step in the hologram creating method according to the present embodiment. The steps S8 to S10 correspond to a comparison step and an additional recording step in the hologram creating method according to the present embodiment.

In addition, it is preferable to use the following method in combination in the above operation. That is, since the speckle noise peculiar to laser beam reproduction exists in the reproduced images CR1, CG1, and CB1 captured by the camera 37, it is preferable to use an appropriate low-pass filter in combination. In order to effectively improve the diffraction efficiency by additional recording and to prevent generation of scattering components due to unnecessary exposure, it is desirable that the intensity ratio of the reference light and the object light is equal. Therefore, the reproduction images CR1, CG1, and CB1 picked up by the camera 37 are multiplied by α _r , α _g , and α _b so as not to saturate on the spatial light modulator 17, and the exposure times TWR, TWG, and TWB are respectively 1 / α. It is preferable to multiply by _r 1, 1 / α _g and 1 / α _b . Further, it is necessary to repeat each wavelength component sequentially without performing additional recording for each wavelength. This is to minimize the change that occurs in the current additional recording status due to additional recording of other wavelength components.

  As described above, in the hologram creating apparatus and method according to the present embodiment, after the element hologram is once recorded in the local region 25, only the reference light out of the object light and the reference light is incident on the local region 25 for a certain period. At this time, a reproduction image by the reproduction light generated from the local region 25 is captured. Then, the captured reproduced image and the target reproduced image are compared, a corrected image corresponding to the result of the comparison is presented to the spatial light modulation element 17, and the spatial light modulation element 17 on which the modified image is presented is displayed. The output light is incident on the local region 25 as object light, and the reference light is also incident on the local region 25. These object light and reference light interfere with each other, and an element hologram is additionally recorded in the local region 25. Therefore, the hologram creating apparatus and method according to the present embodiment can easily create a hologram that can reproduce a reproduced image with high fidelity to the target reproduced image.

It is explanatory drawing of a photosensitive material and a reproduced image. It is a perspective view of the whole hologram production apparatus concerning this embodiment. It is explanatory drawing of the optical system in the hologram production apparatus which concerns on this embodiment. It is explanatory drawing of operation | movement of the hologram production apparatus which concerns on this embodiment. It is explanatory drawing of the conventional hologram production technique.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-3 ... Laser light source, 4-6 ... Optical path blocker, 7 ... Mirror, 8, 9 ... Dichroic mirror, 10 ... Half mirror, 11 ... Optical path blocker, 12, 13 ... Lens, 14 ... Diffusing plate, 16 ... Lens, 17 ... Spatial light modulator, 18 ... Lens, 19 ... Mask plate, 20 ... Aperture, 21 ... Lens, 22 ... Mirror, 23 ... Image of spatial light modulator, 24 ... Lens, 25 ... Local area, 26 ... Mirror, 27, 28 ... lens, 29 ... mask plate, 30 ... aperture, 31, 32 ... lens, 33 ... mirror, 34 ... photosensitive material, 35, 36 ... roller, 37 ... camera, 38 ... enlarged virtual image, 39 ... computer , 40 ... Reconstructed image.

Claims (8)

A volume phase hologram recording material that generates spatial phase modulation according to interference fringes due to the incidence of object light and reference light is used as a photosensitive material. An apparatus for creating a hologram on the photosensitive material by recording an element hologram by causing object light and reference light to interfere with each other in each region,
An image corresponding to the target reproduction image to be reproduced is presented on the spatial light modulator, and the light output from the spatial light modulator on which the image is presented is incident on the local region as object light, and the reference light is Recording means for recording the element hologram in the local area by causing the object light and the reference light to interfere with each other.
Imaging means for causing only the reference light of the object light and the reference light to enter the local region over a certain period, and capturing a reproduction image by the reproduction light generated from the local region at this time;
Comparison means for comparing the reproduced image captured by the imaging means with the target reproduced image;
A corrected image corresponding to a result of comparison by the comparison unit is presented to the spatial light modulation element, and light output from the spatial light modulation element on which the corrected image is presented is incident on the local region as object light. The additional recording means for additionally recording the element hologram in the local area by causing the reference light to also enter the local area, causing the object light and the reference light to interfere with each other, and
A hologram creating apparatus comprising: The target reproduction image is based on light having a plurality of wavelengths,
For each of the plurality of wavelengths, the recording unit records an element hologram in the local region, the imaging unit images the reproduced image, the comparing unit compares the reproduced image with the target reproduced image, and An additional recording means additionally records an element hologram in the local region;
The hologram creating apparatus according to claim 1.   Imaging of the reproduced image by the imaging unit, comparison of the reproduced image and the target reproduced image by the comparing unit, and additional recording of element holograms by the additional recording unit are sequentially repeated for each of the plurality of wavelengths. The hologram creating apparatus according to claim 2. A volume phase hologram recording material that generates spatial phase modulation according to interference fringes due to the incidence of object light and reference light is used as a photosensitive material. A method of creating a hologram on the photosensitive material by recording an element hologram by causing object light and reference light to interfere with each other in each region,
An image corresponding to the target reproduction image to be reproduced is presented on the spatial light modulator, and the light output from the spatial light modulator on which the image is presented is incident on the local region as object light, and the reference light is A step of recording the element hologram in the local area by causing the object light and the reference light to interfere with each other,
An imaging step of causing only the reference light of the object light and the reference light to enter the local area for a certain period after the recording step, and capturing a reproduction image by the reproduction light generated from the local area at this time;
A comparison step of comparing the reproduced image captured in the imaging step with the target reproduced image;
A corrected image corresponding to the result of the comparison in the comparison step is presented to the spatial light modulator, and the light output from the spatial light modulator on which the modified image is presented is incident on the local region as object light. An additional recording step for additionally recording the element hologram in the local area by causing the reference light to also enter the local area, causing the object light and the reference light to interfere with each other, and
A hologram production method comprising: The target reproduction image is based on light having a plurality of wavelengths,
For each of the plurality of wavelengths, an element hologram is recorded in the local area in the recording step, the reproduced image is imaged in the imaging step, the reproduced image is compared with the target reproduced image in the comparing step, In the additional recording step, an element hologram is additionally recorded in the local area.
The method for producing a hologram according to claim 4 . The hologram creating method according to claim 5 , wherein the imaging step, the comparing step, and the additional recording step are sequentially repeated for each of the plurality of wavelengths. The volume phase hologram recording material is
A radically polymerizable compound which is solid at normal temperature and pressure and contains a thermoplastic resin (A) soluble in an organic solvent and at least one unsaturated bond capable of radical polymerization having a 9,9'-diarylfluorene skeleton (B), a plasticizer (C), and a photopolymerization initiator (D),
The weight percentage of each of the thermoplastic resin (A), the radical polymerizable compound (B) and the plasticizer (C) is “(A) :( B) :( C) = 10-80: 10-80: 10-80”. (But the sum of each of these weight percentages is less than 100),
The method for producing a hologram according to claim 4 . 8. The hologram producing method according to claim 7 , wherein the refractive index of the radical polymerizable compound (B) is larger than a weighted average of the refractive index of the thermoplastic resin (A) and the refractive index of the plasticizer (C). .

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