JP2000276036A - Color hologram photographing method, color hologram and its evaluating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographing method for preventing the reproducibility of white from getting deteriorated because the peak wavelength of the diffraction efficiency of color hologram R, G or B is deviated from the center wavelength of each hologram. SOLUTION: The photographing of the hologram having the peak of the diffraction efficiency in respective red, green and blue areas to express colors is performed by this photographing method. In such a case, in order to prevent the reproducibility of the white from getting deteriorated because the peak wavelength of the diffraction efficiency is deviated from the center wavelength (650 nm, 550 nm or 450 nm) of each of the red, green and blue areas according to photographing wavelength and a photosensitive material processing condition, any one or more of the wavelength, the height or the half value width of the peak of the diffraction efficiency of each of the red, green and blue areas of the hologram is controlled, whereby chromaticity coordinate values (x, y) expressed by a CIE display system showing a white image are made within the range of ±0.05 from (x, y)=1/3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color hologram photographing method, a color hologram and a method for evaluating the same.
In particular, the present invention relates to a method for photographing or copying a color hologram with high white reproducibility, the obtained color hologram, and a method for evaluating the color hologram.

[0002]

2. Description of the Related Art Conventionally, a full-color hologram composed of R (red), G (green), and B (blue) is photographed by an optical system as shown in FIG. In this example, a full-color Lippmann hologram (reflection hologram) is photographed, and a photosensitive material 20 such as a photopolymer is used.
As a light source, an R laser 1 (for example, a Kr laser (64
7 nm)), a G laser 2 (for example, an Ar laser excited dye laser (553 nm)), and a B laser 3 (for example, an Ar laser (458 nm)), and in order to synthesize laser light from these into one optical path, A total reflection mirror 4 and dichroic mirrors 5 and 6 are used. In the case of the arrangement shown, the dichroic mirror 5 is a red narrow-band mirror having a non-reflection coating on the back surface, and the dichroic mirror 6 is a wavelength 500 nm having a non-reflection coating on the back surface.
Although the mirror selectively reflects only the above light, the arrangement of the lasers 1 to 3 is not limited to the illustrated one and can be changed. In this case, the arrangement of the total reflection mirror 4, the dichroic mirrors 5 and 6, and The reflection band needs to be changed.

[0003] A laser 1 of three colors RGB combined via a total reflection mirror 4 and dichroic mirrors 5 and 6
3 are split into two light beams by a half mirror 7, and one light passes through a mirror 8 and a lens 9 to form a pinhole 1.
The divergent light emitted from the pinhole 10 after being converged to 0 is obliquely incident from one side of the photosensitive material 20. The other split light is condensed on the pinhole 14 via the mirrors 11 and 12 and the lens 13, and the divergent light emitted from the pinhole 14 is incident on the other side of the photosensitive material 20,
Both divergent light beams interfere in the photosensitive material 20, in which a hologram of an object illuminated with, for example, divergent light emitted from the pinhole 14 is recorded.

In order to duplicate a similar hologram from a full-color hologram master consisting of three primary colors of RGB, an optical system as shown in FIG. 2 is used, for example. This example is an example in which a full-color Lippmann hologram (reflection type hologram) is duplicated.
R laser 1, G laser 2, B laser 3
The laser light from these is used as a total reflection mirror 4
The light is combined into one optical path by the dichroic mirrors 5 and 6. Synthesized RGB three color lasers 1-3
The divergent light emitted from the pinhole 10 passes through the lens 9 and the divergent light emitted from the pinhole 10 is brought into close contact with the hologram master 21 via the refractive index matching liquid.
0, and the incident light and the diffracted light from the hologram master 21 interfere with each other in the closely adhered photosensitive material 20, whereby a color hologram having the same characteristics as the hologram master 21 is copied.

[0005] In the case of FIGS. 1 and 2, the diffraction efficiency of a photographed or copied hologram is such that when reproducing white,
Each of the diffraction efficiencies of R, G and B is 50%,
The half width of each diffraction peak is about 15 nm. In addition,
The center wavelength of the diffraction is about 2 due to shrinkage of the photosensitive material 20 or the like.
The wavelength shifts by a short wavelength of about 0 nm, and R, G, and B are each 62
7 nm, 533 nm, and 438 nm. Then, the position of the image reproduced from the white reproduction hologram on the xy chromaticity diagram is as shown in FIG. As shown in this figure, the values of the x coordinate and the y coordinate representing the white image are around 0.3, and the white appears to be clear white.

[0006]

The G laser 2 used for photographing or copying in FIGS. 1 and 2 is an Ar laser-excited dye laser (553 nm), but this dye laser is inferior in output stability. Therefore, G laser 2 is LD
The laser was changed to 532 nm, and at the same time, the B laser 3 was changed to Ar laser (477 nm).
A white reproduction hologram was photographed and duplicated in the above arrangement. The diffraction efficiency of the hologram is R,
The diffraction efficiency of each of G and B was set to 50%. The half width of each diffraction peak is about 15 nm.
The center wavelength of diffraction is shifted by about 20 nm due to shrinkage of the photosensitive material 20 and the like, and R, G, and B are each 6 nm.
27 nm, 512 nm, and 457 nm. The position on the xy chromaticity diagram of the image reproduced from the white reproduction hologram is as shown in FIG. In this case, the x-coordinate value representing the white image is about 0.25, and the y-coordinate value is about 0.2, and what should originally appear white appears only bluish white.

That is, R for expressing color,
In hologram imaging and duplication having diffraction efficiency peaks in G and B, respectively, the imaging wavelength used for imaging and duplication, the shrinkage of the photosensitive material, and the diffraction wavelength due to other processing conditions (such as contact with a color tuning film, adhesive, etc.) The peak wavelength of the diffraction efficiency of the produced hologram is changed to the center wavelength of each of R, G, and B (650 nm, 55
0 nm, 450 nm), the reproducibility of white color deteriorates.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to shift the peak wavelengths of the R, G, and B diffraction efficiencies of a color hologram from their respective center wavelengths. An object of the present invention is to provide a photographing method for preventing white color reproducibility from being deteriorated.

[0009]

According to the present invention, there is provided a color hologram photographing method for achieving the above object, which comprises a hologram having a diffraction efficiency peak in each of a red region, a green region, and a blue region for expressing a color. Depending on the photographing wavelength used for photographing and the processing conditions of the photosensitive material, the peak wavelength of the diffraction efficiency of the produced hologram has the center wavelength (650 nm, 550 nm, 4 nm) of each of the red, green, and blue regions.
50 nm) to prevent the white reproducibility from deteriorating.
By controlling any one or more of the wavelength, height, or half width of the peak of the diffraction efficiency of each blue region, the chromaticity coordinate values x and y represented by the CIE display system showing a white image can be converted to color. This method is characterized in that x, y = 1/3 to ± 0.05, which corresponds to equal energy white light that looks clear and white without taste, is kept within a range.

In this case, when a hologram is photographed by exposing three wavelengths at the same time, the peak value of the diffraction efficiency of the manufactured hologram becomes 3: 1 from the exposure intensity balance.
It is possible to shift the light amount balance between the light sources of the two wavelengths.

Further, with respect to a duplicate product in which a hologram is photographed by simultaneously exposing three wavelengths, taking into account the phenomenon that each color of RGB is shifted to a short wavelength by a photosensitive material, an adhesive layer, etc. No. 97345, “Volume Hologram Laminate and Label for Producing Volume Hologram Laminate” are laminated on the hologram photosensitive material layer, and the center wavelength is shifted in the longer wavelength direction to produce a more colored hologram. it can. At this time, the heave value of the diffraction efficiency is 1:
The light amount balance of the three wavelengths can be shifted from the exposure intensity balance of 1: 1.

Further, when a hologram is photographed using laser beams of three wavelengths, a green region is adjusted so that the peak value of the diffraction efficiency of the produced hologram has an exposure intensity balance of 1: 1: 1. A dye laser can be used as the laser having the wavelength.

The color hologram of the present invention has a diffraction efficiency peak in each of a red region, a green region, and a blue region for expressing a color, and has a diffraction efficiency peak wavelength in each of a red region, a green region, and a blue region. Deviated from the center wavelength (650 nm, 550 nm, 450 nm) of each of the red, green, and blue regions, and the height or half-value width of the diffraction efficiency deviated from 1: 1: 1 and a white image The chromaticity coordinate values x and y expressed in the CIE display system indicating x are within the range of x, y = 1/3 to ± 0.05 corresponding to equi-energy white light that looks clear and has no color. It is characterized by having.

The method for evaluating a color hologram according to the present invention comprises:
In a method for evaluating a color hologram having peaks of diffraction efficiency in each of a red region, a green region, and a blue region for expressing a color, the sample hologram was designed by irradiating highly directional illumination light near the designed incident angle. In the vicinity of the diffraction angle, the chromaticity of the light diffracted from the sample hologram is obtained by calculating the chromaticity of the light diffracted from the sample hologram by a chromaticity measuring device or a spectroscope or by obtaining the spectral distribution and then obtaining the chromaticity. Coordinate values x and y are x and y
= 1/3 to ± 0.05.

In the present invention, the red region of the hologram is
By controlling at least one of the wavelength, height, or half width of the peak of the diffraction efficiency of each of the green region and the blue region, the chromaticity coordinate values x, y represented by the CIE display system showing a white image are controlled. Is set within the range of x, y = 1/3 to ± 0.05, which is equivalent to an equal-energy white light that looks clear and has no color, so that the photographing wavelength and the photosensitive material used for photographing can be adjusted. The peak wavelength of the diffraction efficiency of the produced hologram has a central wavelength (650 nm, 550 nm, 450 n) in each of the red, green, and blue regions.
m), the reproduced image looks clear and white with no color, and good color reproducibility of white is obtained.
The reproducibility of other colors is also good.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention will be described below based on embodiments.

When the diffraction efficiency profiles (diffraction efficiency distributions) of the volume type color hologram in the R, G, and B regions are η _r , η _g , and η _b , respectively, the wavelength is λ.
The diffraction efficiency distribution η _all (λ) of the entire hologram
Η _all (λ) = η _r + η _g + η _b − (η _r η _g + η _g η _b + η _b η _r ) (1) Assuming that the spectral distribution of the illumination light is P _s (λ), the spectral distribution P (λ) of the light diffracted from the hologram is P (λ) = P _s (λ) η _all (λ) (2) Becomes The tristimulus values X, Y, and Z in the CIE display system are as follows.

X = 100 × ∫P (λ) x ′ (λ) dλ / ∫P _s (λ) y ′ (λ) dλ Y = 100 × ∫P (λ) y ′ (λ) dλ / ∫P _s (Λ) y ′ (λ) dλ Z = 100 × ΔP (λ) z ′ (λ) dλ / ΔP _s (λ) y ′ (λ) dλ (3) where x ′ (λ ), Y ′ (λ) and z ′ (λ) are spectral tristimulus values.

The chromaticity coordinates (x, y) represented in the CIE display system are obtained by the following equation: x = X / (X + Y + Z), y = Y / (X + Y + Z) (4)

Here, as described in the section of the prior art,
In the arrangements of FIG. 1 and FIG.
Laser (wavelength 647nm), LD as G laser 2
Laser (wavelength 532 nm), B laser 3 as Ar
When a white reconstructed hologram is photographed and copied using a laser (477 nm), the diffraction efficiency of each of the R, G, and B regions is set to 50%.
The half width of each diffraction peak is about 15 nm, and
The center wavelength of the diffraction is DuPo which is the photosensitive material 20 used.
For contraction of HRF800X001 manufactured by nt, R,
G and B peak wavelengths are 627 nm and 512 n, respectively.
m, 457 nm. This white reproduction hologram is called C
When the chromaticity coordinates (x, y) when reproducing by illuminating with light are obtained according to the above equation (4), the positions on the xy chromaticity diagram are as shown in FIG. This reconstructed image should look white, but only looks bluish white.

Therefore, according to the present invention, the R laser 1, the G laser 2, and the B laser 2 are set so that the diffraction efficiency of the R region is 60%, the diffraction efficiency of the G region is 60%, and the diffraction efficiency of the B region is 30%. When the amount of light from the laser 3 was adjusted and photographed and duplicated in the same manner, the chromaticity coordinates (x, y) of the image reproduced from the white hologram were obtained according to the above equation (4). 3 was as shown in FIG. 3, and the reconstructed image appeared clear white with no color. At that time, the x coordinate value and the y coordinate value were both approximately 0.3.

As in this embodiment, the peak wavelengths of the diffraction efficiencies in the R region, G region, and B region of the hologram to be manufactured have respective center wavelengths (650 nm, 550 nm, 450 nm).
nm), the white light reproducibility deteriorates, and the diffraction efficiency of the hologram produced by adjusting the light amounts of the R, G, and B recording light used for photographing and duplication is reduced to 1:
The chromaticity coordinate values x and y are deviated from 1: 1 so that the hologram is close to x, y = 1/3 corresponding to equal-energy white light that looks clear and white without color. be able to.

In this case, x and y calculated from equation (4)
If the range of the value of each is within the range of 1/3 ± 0.05, the reproduced image looks clear and white without coloring, so that the values of x and y are each 1/3 ± 0. .05
The diffraction efficiency may be adjusted by adjusting the amount of recording light so as to fall within the range.

The center wavelength of the hologram produced by the laser is shifted from the recording wavelength to a shorter wavelength by 20 nm. In the above embodiment, the adjustment at the shifted wavelength is considered, but the color reproducibility is further improved. For this purpose, a layer configuration for returning the shifted wavelength to the recording wavelength can be provided. At this time, a photopolymerizable compound in a pressure-sensitive adhesive layer laminated on one or both sides of the hologram, at least one of a plasticizer and a surfactant, or a tackifier is contained, the photopolymerizable compound, The center wavelength can be controlled by moving at least one of a plasticizer and a surfactant, or a tackifier between layers. With this layer configuration, 20 nm
Just by returning to the long wavelength and shifting to the same center wavelength as the photographing wavelength, the reproducibility of white is not sufficiently improved, so that the amount of R, G, and B recording light used for photographing and copying is reduced as described above. The impeachment rate of the hologram produced by adjusting is 1:
The chromaticity coordinate values x and y are deviated from 1: 1 so that the hologram has near x, y = 1/3, which is equivalent to white light with equal energy and looks clear and white. be able to.

In the above description, the chromaticity coordinate values x and y are set to fall within the range of 1/3 ± 0.05.
The peak values of the diffraction efficiencies in the region, the G region, and the B region are set to 1: 1:
It was an example to shift from 1, but instead,
Even if the half widths of the diffraction efficiency profiles of the R region, the G region, and the B region are different from each other, the chromaticity coordinate values x and y are similarly set to be within the range of 1/3 ± 0.05. It is possible.

As described above, a Kr laser (647 nm) is used as the R laser 1 and an A laser is used as the G laser 2.
When an r laser excited dye laser (553 nm) and an Ar laser (458 nm) as the B laser 3 are used, the peak values of the diffraction efficiencies in the R, G, and B regions are set to 1: 1: 1, and half of the diffraction peak is obtained. Assuming that the value widths are the same, the values of the x coordinate and the y coordinate representing the white image are close to 0.3 as shown in FIG. 4, and the color is clear white with no tint. It is not necessary to shift the peak values of the diffraction efficiency in the region and the region B from 1: 1: 1.

Whether or not the chromaticity coordinate values x and y of the color hologram obtained or photographed or duplicated as shown in FIG. 1 or 2 are within the range of 1/3 ± 0.05 as designed. For example, the chromaticity coordinate values x and y are measured directly by the arrangement shown in FIG. 5 or the diffraction efficiency distribution η _all (λ) of the hologram is obtained using a spectroscope, and (2) to The chromaticity coordinate values x and y are obtained according to the equation (4), and the obtained chromaticity coordinate values x and y are each １ ／ ± 0.
05 may be determined. Hereinafter, FIG. 5 will be described.

A sample table 32 is mounted so as to be adjustable in rotation about the Z-axis of the base 31, and a light source table 33 is simultaneously mounted so as to be capable of being separately rotated about the same Z-axis. Then, the hologram H to be evaluated is attached to the sample table 32 with its position adjusted in the XZ direction. In addition, a color luminance meter (for example, TOPCON color luminance meter BM-7) 34 is attached to the base 31 in a direction to take in light incident from the measurement center direction of the hologram H of the sample table 32. On the other hand, the illumination light is incident on the light source table 33 at the measurement center of the hologram H,
A white light source (for example, a xenon lamp or a halogen lamp) 35 is attached, and a collimating lens 3
6 is arranged.

Then, from the light source 35 collimated by the collimating lens 36, white illumination light 37 is incident on the hologram H at the designed incident angle θ (n in the figure is the normal to the hologram H plane). The angle of the sample table 32 and the light source table 33 with respect to the base 31 is adjusted and fixed so that the diffracted light 38 of the hologram H enters the color luminance meter 34 at the designed diffraction angle φ, and the chromaticity of the diffracted light 38 from the hologram H is adjusted. Coordinate value x,
y is measured directly by the color luminance meter 34.

Here, for example, the TOPCON color luminance meter BM-7 uses the spectral three stimulus values x '(λ), y'.
(3) A color glass filter having three types of transmittance spectral characteristics corresponding to (λ) and z ′ (λ) is provided.
The tristimulus values X, Y, and Z in the CIE display system of the equation are directly obtained, and then the chromaticity coordinate values x and x of the CIE display system in the equation (4)
y is directly output.

Therefore, according to the measurement arrangement shown in FIG. 5, the diffracted light 38 emitted when the sample hologram H is illuminated with the white light 37 having a high directivity at the designed incident angle θ.
It can be easily evaluated whether or not the chromaticity coordinate values x and y are within the range of 1/3 ± 0.05 as designed.

In the arrangement of FIG. 5, the color luminance meter 3
A spectroscope may be attached instead of 4, and the spectral distribution P (λ) of the diffracted light 38 may be obtained, and the chromaticity coordinate values x and y may be obtained and evaluated according to the equations (3) and (4). .

It is needless to say that the incident angle θ and the diffraction angle φ
It is desirable to perform the above measurement while adjusting near the design value.

The color hologram photographing method, color hologram, and evaluation method of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.

[0035]

As is apparent from the above description, according to the color hologram photographing method, color hologram and evaluation method of the present invention, the peak wavelength of the diffraction efficiency in each of the red, green, and blue regions of the hologram is obtained. By controlling one or more of the height and the half-value width, the chromaticity coordinate values x and y represented by the CIE display system showing a white image can be converted to a clear white color without any color. Since the x and y values corresponding to white light are set within the range of 1/3 to ± 0.05, the diffraction efficiency peak of the hologram produced depends on the photographing wavelength used for photographing and the processing conditions of the photosensitive material. Even if the wavelengths deviate from the center wavelengths (650 nm, 550 nm, 450 nm) of the red, green, and blue regions, the reproduced image looks clear and white with no tint,
Good color reproducibility of white is obtained, and reproducibility of other colors is also good.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a full-color hologram imaging optical system to which the present invention can be applied.

FIG. 2 is a diagram showing a configuration of a full-color hologram duplication optical system to which the present invention can be applied.

FIG. 3 is an xy chromaticity diagram showing chromaticity coordinates of an image reproduced from a white reproduction hologram according to one embodiment of the present invention.

FIG. 4 is an xy chromaticity diagram showing chromaticity coordinates of an image reproduced from a white reproduction hologram according to another embodiment of the present invention.

FIG. 5 is a diagram showing an example of a measurement arrangement for implementing the method for evaluating a color hologram according to the present invention.

FIG. 6 is an xy chromaticity diagram showing chromaticity coordinates of an image reproduced from a white reproduction hologram of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... R laser 2 ... G laser 3 ... B laser 4 ... Total reflection mirror 5, 6 ... Dichroic mirror 7 ... Half mirror 8, 11, 12 ... Mirror 9, 13 ... Lens 10, 14 ... Pinhole 20 ... Photosensitive material 21 ... hologram master 31 ... base 32 ... sample table 33 ... light source table 34 ... color luminance meter 35 ... white light source 36 ... collimating lens 37 ... white illumination light 38 ... diffracted light H ... sample hologram

Claims (6)

[Claims] 1. A method for photographing a hologram having a diffraction efficiency peak in each of a red region, a green region, and a blue region for expressing a color, according to a photographing wavelength used for photographing and processing conditions of a photosensitive material. In order to prevent the peak wavelength of the diffraction efficiency of the hologram from deviating from the center wavelength (650 nm, 550 nm, 450 nm) of each of the red, green, and blue regions, the hologram has a red region, a green region, and a green region. Any one of the wavelength, height, or half width of the peak of the diffraction efficiency in each of the blue region and the blue region
By controlling at least one of the chromaticity coordinate values x and y expressed in the CIE display system indicating a white image, x and y = x, y =
A color hologram photographing method characterized in that it is set within a range of 1/3 to ± 0.05. 2. When a hologram is photographed by simultaneously exposing three wavelengths, the light intensity balance of the light source of the three wavelengths is shifted from the exposure intensity balance at which the peak value of the diffraction efficiency of the produced hologram becomes 1: 1: 1. 2. The color hologram photographing method according to claim 1, wherein: 3. When the hologram is conveyed by simultaneously exposing three wavelengths, the diffraction of the produced hologram is considered in consideration of adding a layer configuration for shifting the diffraction center wavelength of the produced hologram to a longer wavelength. 1: 1: 1 peak efficiency
3. The color hologram photographing method according to claim 1, wherein the light intensity balance of the three wavelength light sources is shifted from the exposure intensity balance. 4. When photographing a hologram using laser beams of three wavelengths, a green region is adjusted so that a peak value of diffraction efficiency of the produced hologram has an exposure intensity balance of 1: 1: 1. 2. The color hologram photographing method according to claim 1, wherein a dye laser is used as the laser having the wavelength. 5. A hologram having a diffraction efficiency peak in each of a red region, a green region, and a blue region for expressing a color, wherein a peak wavelength of the diffraction efficiency is in a red region, a green region,
The center wavelength of each blue region (650 nm, 550 nm,
450 nm), and the height or half width of the peak of the diffraction efficiency in each of the red, green, and blue regions is 1:
The chromaticity coordinate values x and y, which deviate from 1: 1 and are expressed in the CIE display system indicating a white image, are x and y = equivalent white light that looks clear and white without coloring. 1
A color hologram, wherein the color hologram is in the range of ３ to ± 0.05. 6. A method for evaluating a color hologram having a diffraction efficiency peak in each of a red region, a green region, and a blue region for expressing a color, wherein illumination light having high directivity near an incident angle designed for a sample hologram is provided. Irradiate, near the designed diffraction angle, by calculating the chromaticity of the light diffracted from the sample hologram by a chromaticity measuring device or spectroscope or by obtaining the spectral distribution and then obtaining the chromaticity, A method for evaluating a color hologram, comprising determining whether or not chromaticity coordinate values x and y of diffracted light fall within a range of x, y = 1/3 to ± 0.05.