JP6909438B2 - Light modulation elements and information recording media - Google Patents

Description

The present invention relates to a light modulation element that modulates the phase of incident reproduced light to reproduce an optical image, and an information recording medium including such a light modulation element.

Various types of light modulation elements have been proposed as light modulation elements such as holograms that can reproduce the original image.

For example, Patent Document 1 discloses an amplitude modulation type light modulation element in which an original image is binarized after Fourier transform and output on a film. Further, Patent Documents 2 to 4 disclose a phase modulation type light modulation element having a concavo-convex pattern. The light modulation elements of Patent Documents 1 to 4 are transmissive light modulation elements in which the observer and the light source are present on opposite sides via the light modulation element, but the observer and the light source refer to the light modulation element. Reflective light modulation elements existing on the same side are also known (see, for example, Patent Document 5).

In addition, for example, Patent Document 6 and Patent Document 7 disclose a light modulation element that diffracts light over the entire visible light wavelength band and reproduces an optical image. Further, Patent Document 8 describes a region in which a first light diffraction structure in which recorded information can be read mechanically is formed and a region in which a second light diffraction structure in which recorded information can be visually read is formed. Disclose a light modulation element (information recording medium) provided so as not to superimpose. Further, Patent Document 9 discloses a light modulation element that obscures the spot light of the 0th-order diffracted light that interferes with observation by superimposing the bright portion of the reproduced original image pattern on the center of the reproduced image region.

Japanese Unexamined Patent Publication No. 10-228870 Japanese Unexamined Patent Publication No. 2004-126535 Japanese Unexamined Patent Publication No. 2007-183336 Japanese Unexamined Patent Publication No. 07-290264 Japanese Unexamined Patent Publication No. 2017-37772 Japanese Unexamined Patent Publication No. 10-153943 Japanese Unexamined Patent Publication No. 2004-126535 Japanese Unexamined Patent Publication No. 07-320014 Japanese Unexamined Patent Publication No. 2004-126536

However, the conventional light modulation element has not always been able to reproduce a specific desired optical image.

For example, in the amplitude modulation type light modulation element of Patent Document 1, the reproducible light image is limited to the light image produced by the 0th-order diffracted light and the light image reproduced point-symmetrically with the light image of the 0th-order diffracted light as the center. .. Therefore, the amplitude modulation type light modulation element of Patent Document 1 reproduces, for example, light images having different patterns on one side and the other side centering on the light image of the 0th-order diffracted light, or an optical image of the 0th-order diffracted light. It is not possible to reproduce a large image of a single pattern around the. On the other hand, the phase modulation type light modulation element of Patent Document 2 has three or more types of optical path length differences brought about by the uneven pattern, so that the light image of the 0th-order diffracted light is mutually centered on one side and the other side. It is possible to reproduce different patterns, or to reproduce a single pattern large around the optical image of the 0th-order diffracted light. However, in the optical image reproduced by the light modulation element of Patent Document 2, the ratio of the 0th-order diffracted light to the reproduced light incident on the light modulation element is very low, so that the scene is observed when the surroundings are observed through the light modulation element. Is blurred and observed.

Further, since the optical modulation elements of Patent Documents 1 to 7 diffract light almost evenly over the entire visible light wavelength band, when white light, which is general ambient light, is incident, the white light is dispersed. The light image is reproduced at a different position for each wavelength, and the rainbow-colored light image is reproduced as a whole. When the light image is reproduced in rainbow colors in this way, various lines (for example, contour lines) are thickened, so that the visibility of the reproduced image is poor and a desired light image cannot be reproduced with high definition. Further, if the color of the reproduced image is limited to the rainbow color, the optical image cannot be reproduced with a specific color (for example, a single color such as red or blue), and the specific color may give a specific impression to the observer. Can not.

As a method of reproducing an optical image in a specific color, a filter layer such as a color filter that allows only light in a specific wavelength band to enter the optical modulation element or selectively transmits only light in a specific wavelength band is used as the optical modulation element. It is possible to add it. However, when only light in a specific wavelength band is incident on the light modulation element, the light sources that can be used are limited, so that the use of the light modulation element is very limited. Further, when the filter layer is provided, the manufacturing cost increases, and the color of the scene observed through the light modulation element is limited to the color of the specific wavelength band, which causes a sense of discomfort to the observer.

Further, Patent Document 8 is provided with first and second optical diffraction structures that diffract two types of wavelengths, whereas the first optical diffraction structure reproduces mechanically readable recorded information. , The second light diffraction structure reproduces visually readable recorded information. Therefore, similarly to the other documents described above, the light modulation element of Patent Document 8 cannot visually reproduce an optical image having a desired specific color when white light is incident, and the observation image can be visually recognized. The sex is not always good. Further, although the light modulation element of Patent Document 8 is provided with two types of light diffraction structures, a light modulation element capable of appropriately diffracting light in two or more types of wavelength bands by a single type of light diffraction structure is also desired. It is rare.

Further, in the light modulation element of Patent Document 9, in order to make the spot light of the 0th-order diffracted light that interferes with the observation inconspicuous, the spot light of the 0th-order diffracted light and the bright part of the reproduction original image pattern are overlapped with each other. By comparison, the brightness of the 0th-order diffracted light is high. Therefore, even if the light modulation element of Patent Document 9 is used, the spot light of the 0th-order diffracted light is still conspicuous in the reproduced image, and the 0th-order diffracted light can deteriorate the visibility of the reproduced image. Further, when the bright portion of the reproduction original image pattern does not exist at the position where the spot light of the 0th-order diffracted light is reproduced, the spot light of the 0th-order diffracted light cannot be hidden by the reproduced image pattern.

As described above, the conventional light modulation element has not always been able to properly reproduce an optical image having a desired visibility. In particular, there is a demand and need for an optical modulation element that can reproduce a generally used white light as a reproduction light and can reproduce a desired light image with good visibility without devising the original image. Very expensive. Such a reproduced image with excellent visibility is not only suitable for design applications, but also suitable for security applications such as authenticity determination. In particular, when the reproduced image is authenticated by a device for security purposes, the authentication accuracy is improved and the reliability is excellent by suppressing the influence of the 0th-order diffracted light and clearly reproducing the desired optical image by other diffracted light. It becomes possible to provide security performance.

The present invention has been made in view of the above circumstances, and a specific color other than rainbow color (that is, a specific wavelength band) when white light is incident without providing a layer that selectively transmits or reflects a specific wavelength band. It is an object of the present invention to provide an optical modulation element capable of reproducing an optical image with (light), and an information recording medium including such an optical modulation element. Another object of the present invention is to provide a light modulation element capable of clearly reproducing a desired light image by reducing the influence of the 0th-order diffracted light, and an information recording medium including such a light modulation element.

One aspect of the present invention includes an element element that reproduces an optical image by modulating the phase of the incident reproduced light, and the element element has an uneven surface, and the diffraction efficiency of the primary diffracted light with respect to the element element is high. The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution and the diffraction efficiency of the -1st order diffracted light is the maximum having a half-value full width of 200 nm or less in the wavelength distribution of the diffraction efficiency including the maximum diffraction efficiency. It relates to an optical modulation element that forms a value.

The uneven surface of the element element includes three or more different heights, and is maximally diffracted in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light. There may be no other maximum value that results in a diffraction efficiency that is more than half the efficiency.

At least two or more types of element elements are provided, and at least two or more types of element elements may have different wavelengths that exhibit maximum diffraction efficiency.

The optical modulation element includes a first region and a second region, an element element including the first type element element is arranged in the first region, and a second type element element is arranged in the second region. The element element including the above is arranged, and the wavelength showing the maximum diffraction efficiency for the first type element element is arranged in the first region unlike the wavelength showing the maximum diffraction efficiency for the second type element element. The optical image reproduced by the element element may have a shape relationship with the optical image reproduced by the element element arranged in the second region.

The maximum diffraction efficiency is included in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light. The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distributions of the above may form a maximum value having a half-value full width of 200 nm or less in the wavelength distribution of the other diffraction efficiency.

The maximum diffraction efficiency may be included in both the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light.

The wavelength showing the maximum diffraction efficiency in one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light, the wavelength distribution of the diffraction efficiency of the first-order diffracted light, and the diffraction efficiency of the -1st-order diffracted light. The difference from the wavelength showing the maximum diffraction efficiency in the other of the wavelength distributions of the above may be 100 nm or less.

In the wavelength band of 380 nm or more and 780 nm or less in one of the diffraction efficiency wavelength distribution of the primary diffracted light and the diffraction efficiency wavelength distribution of the first-order diffracted light, half of the maximum diffraction efficiency in the diffraction efficiency of the other one. There is no other maximum value for the above diffraction efficiency, and in the wavelength band of 380 nm or more and 780 nm or less in the other of the diffraction efficiency wavelength distribution of the primary diffracted light and the diffraction efficiency wavelength distribution of the -1st order diffracted light. It is not necessary that there is another maximum value having a diffraction efficiency of half or more of the maximum diffraction efficiency in the wavelength distribution of the other diffraction efficiency.

The optical modulation element includes a first region and a second region, in which the first type element element is arranged in the first region, and the second type element element is arranged in the second region. In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element is the same as the wavelength distribution of the diffractive efficiency of the primary diffracted light for the second type element element. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first type element element is the same as the wavelength distribution of the diffractivity of the -1st order diffracted light for the second type element element. The reproduced optical image of the primary diffracted light has the same shape as the optical image of the -1st diffracted light reproduced by the second type element element, and the -1st diffracted light reproduced by the first type element element. The optical image of the above has the same shape as the optical image of the primary diffracted light reproduced by the second type element element, and the optical image reproduced by the primary diffracted light of the first type element element and the -1st diffracted light. Even if the relative position with respect to the optical image reproduced by is opposite to the relative position between the optical image reproduced by the primary diffracted light of the second type element element and the optical image reproduced by the -1st diffracted light. good.

A plurality of element elements are provided, including the first type element element and the second type element element, and the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element in the wavelength band of 380 nm or more and 780 nm or less. Is the same as the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second type element element, and the wavelength distribution of the diffractive efficiency of the -1st diffracted light for the first type element element is the second type element element. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light is the same as that of the -1st order diffracted light reproduced by the 1st type element element. The optical image of the first-order diffracted light having the same shape as the optical image and reproduced by the first type element element has the same shape as the optical image of the first diffracted light reproduced by the second type element element. The optical image of the primary diffracted light having and reproduced by the first type element element overlaps with the optical image of the -1st order diffracted light reproduced by the second type element element, and is reproduced by the first type element element. The optical image of the first-order diffracted light may overlap with the light image of the first-order diffracted light reproduced by the element element of the second type.

A plurality of element elements are provided, including the first type element element and the second type element element, and the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element in the wavelength band of 380 nm or more and 780 nm or less. Is different from the wavelength distribution of the diffraction efficiency of the first-order diffracted light for the second type element element, and the wavelength distribution of the diffractivity of the first-order diffracted light for the first type element element is different from that of the second type element element. The optical image of the primary diffracted light reproduced by the first type element element is different from the wavelength distribution of the diffractive efficiency of the -1st diffracted light of the -1st diffracted light reproduced by the second type element element. The optical image of the first-order diffracted light having the same shape as the optical image and reproduced by the first type element element has the same shape as the optical image of the first diffracted light reproduced by the second type element element. The optical image of the primary diffracted light having and reproduced by the first type element element overlaps with the optical image of the -1st order diffracted light reproduced by the second type element element, and is reproduced by the first type element element. The optical image of the first-order diffracted light may overlap with the light image of the first-order diffracted light reproduced by the element element of the second type.

A plurality of element elements are provided, including the first type element element and the second type element element, and the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element in the wavelength band of 380 nm or more and 780 nm or less. Is different from the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second type element element, and the wavelength distribution of the diffractivity of the -1st order diffracted light for the first type element element is the second type element. The wavelength distribution of the diffraction efficiency of the primary diffracted light for the element is different, and the optical image of the primary diffracted light reproduced by the first type element element is the light of the primary diffracted light reproduced by the second type element element. The optical image of the -1st-order diffracted light having the same shape as the image and reproduced by the first type element element has the same shape as the optical image of the -1st-order diffracted light reproduced by the second type element element. The optical image of the primary diffracted light having and reproduced by the first type element element overlaps with the optical image of the primary diffracted light reproduced by the second type element element and is reproduced by the first type element element. The optical image of the -1st order diffracted light may overlap with the optical image of the -1st order diffracted light reproduced by the element element of the second type.

The maximum diffraction efficiency of the 0th-order diffracted light for the element element may be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more.

The maximum diffraction efficiency of the 0th-order diffracted light for the element element may form a maximum value having a full width at half maximum of 200 nm or less.

Even if at least one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light of the element element has the maximum value of the diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less. good.

The maximum diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for the element element is the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the diffraction efficiency of the -1st-order diffracted light for the element element. It may be less than 25% of the maximum value included in the wavelength band of at least one of the wavelength distributions of 456 nm or more and 663 nm or less.

The optical modulation element includes a first region and a second region, in which the first type element element is arranged in the first region and the second type element element is arranged in the second region. The optical image of the primary diffracted light and the optical image of the -1st diffracted light reproduced by the element element of the first type are the optical image of the primary diffracted light and the optical image of the -1st diffracted light reproduced by the element element of the second type. The maximum diffraction efficiency of the 0th-order diffracted light for the 1st type element element is obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more, and the 0th order for the 2nd type element element is obtained. The maximum diffraction efficiency of the folding light may be obtained at a wavelength larger than 421 nm and smaller than 697 nm.

Another aspect of the present invention includes an element element that reproduces an optical image by modulating the phase of incident reproduced light, and the element element has an uneven surface including three or more different heights and is an element. The element reproduces the first light image by the light containing the light of the first wavelength, and reproduces the second light image point-symmetrical to the first light image by the light containing the light of the second wavelength different from the first wavelength. , With respect to an optical modulator.

One of the first light image and the second light image may be reproduced in red.

The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light for the element element is in the wavelength distribution of the one diffraction efficiency. A maximum value may be formed in a wavelength band of 680 nm or more and 780 nm or less.

By changing the angle of incidence of the regenerated light on the element element, the maximum diffraction efficiency of the first-order diffraction light diffraction efficiency wavelength distribution and the -1st-order diffraction light diffraction efficiency wavelength distribution of the element element can be determined by the other. A maximum value may be formed in a wavelength band smaller than 680 nm in the wavelength distribution of diffraction efficiency.

In the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of one diffraction efficiency, there may not be a maximum value having a diffraction efficiency of half or more of the maximum diffraction efficiency.

Another aspect of the present invention comprises an element element that reproduces an optical image by modulating the phase of the incident reproduced light, the element element having a concavo-convex surface containing three or more different heights and an element. The present invention relates to an optical modulation element in which the maximum diffraction efficiency of the 0th-order diffracted light for the element is obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more.

Element The element may be a Fourier transform hologram.

Another aspect of the present invention relates to an information recording medium including any of the above light modulation elements.

The light image may represent information based on at least one of letters, symbols and patterns.

The information recording medium may further include a base material having an opening of a predetermined size, and at least a part of the light modulation element may be arranged at a position corresponding to the opening.

According to the present invention, a light modulation element capable of reproducing an optical image in a specific color other than rainbow color when white light is incident without providing a layer that selectively transmits or reflects a specific wavelength band, and an optical modulation element. An information recording medium including such a light modulation element can be provided. Further, it is possible to provide an optical modulation element capable of clearly reproducing a desired light image by reducing the influence of the 0th-order diffracted light, and an information recording medium including such a light modulation element.

FIG. 1 is a schematic plan view showing a typical example of a hologram holder. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. FIG. 3 is a conceptual diagram of a reflective hologram structure. FIG. 4 is a conceptual diagram of a transmissive hologram structure. FIG. 5 is a conceptual diagram showing the planar structure of the hologram structure. FIG. 6 is a cross-sectional view of an element element showing an outline of an example of a stepped structure of an uneven surface. FIG. 7 is a cross-sectional view of an element element showing an outline of another example of a stepped structure of an uneven surface. FIG. 8 is a graph showing an example of the relationship between the wavelength distribution of the primary diffracted light of each element element and the diffraction efficiency. FIG. 9 is a schematic diagram for explaining an optical image reproduced by a general hologram structure. FIG. 10 is a schematic diagram for explaining an optical image reproduced by the hologram structure of the first embodiment. FIG. 11 is a schematic diagram for explaining an optical image reproduced by the hologram structure of the first embodiment. FIG. 12 is a schematic diagram for explaining an optical image reproduced by the hologram structure of the first embodiment. FIG. 13 is a conceptual diagram showing an example of the planar structure of the transmissive hologram structure according to the modified example 1-1. FIG. 14 is a schematic diagram for explaining an optical image reproduced by the transmissive hologram structure of FIG. FIG. 15 is a conceptual diagram showing another example of the planar structure of the transmissive hologram structure according to the modified example 1-1. FIG. 16 is a schematic diagram for explaining an optical image reproduced by the transmissive hologram structure of FIG. FIG. 17 is a schematic diagram for explaining an optical image reproduced by another example of the transmissive hologram structure according to the modified example 1-1. FIG. 18A is a schematic view for explaining an optical image reproduced by an example of the hologram structure according to the modified example 1-2, and shows an optical image reproduced through the first region. .. FIG. 18B shows an optical image reproduced through the second region of the hologram structure of FIG. 18A. FIG. 19A is a schematic diagram for explaining an optical image reproduced by another example of the hologram structure according to the modified example 1-2, and shows an optical image reproduced through the first region. FIG. 19B shows an optical image reproduced through the second region of the hologram structure of FIG. 19A. FIG. 20 shows the wavelength distributions of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to an example of the reflective hologram structure according to the second embodiment. It is a graph which shows. FIG. 21 shows an example of an optical image reproduced by a hologram structure having the characteristics shown in FIG. FIG. 22 shows the wavelengths of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to another example of the reflective hologram structure according to the second embodiment. It is a graph which shows the distribution. FIG. 23 shows an example of an optical image reproduced by the hologram structure having the characteristics shown in FIG. FIG. 24 shows the wavelengths of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to another example of the reflective hologram structure according to the second embodiment. It is a graph which shows the distribution. FIG. 25 shows an example of an optical image reproduced by a hologram structure having the characteristics shown in FIG. 24. FIG. 26 shows the wavelengths of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to another example of the reflective hologram structure according to the second embodiment. It is a graph which shows the distribution. FIG. 27 shows an example of an optical image reproduced by a hologram structure having the characteristics shown in FIG. FIG. 28A is a diagram showing an example of an optical image b due to the primary diffracted light reproduced by the hologram structure according to the modified example 2-1. FIG. 28B is a diagram showing an example of an optical image b due to the primary diffracted light reproduced by the hologram structure according to the modified example 2-1. FIG. 29 is a diagram schematically showing a planar structure of the hologram structure according to the modified example 2-1 and an optical image reproduced by the hologram structure. FIG. 30 is a conceptual diagram showing an example of the planar structure of the transmissive hologram structure according to the modified example 2-2. FIG. 31A is a schematic view for explaining an example of an optical image reproduced by the transmissive hologram structure of FIG. 30, and shows an optical image reproduced by the first element element. FIG. 31B shows an optical image reproduced by the second element element of the hologram structure of FIG. FIG. 31C shows an optical image reproduced by overlapping the optical image shown in FIG. 31A and the optical image shown in FIG. 31B. FIG. 32A is a schematic view for explaining another example of the light image reproduced by the transmissive hologram structure according to the modified example 2-2, and shows the light image reproduced by the first element element. FIG. 32B shows an optical image reproduced by the second element element of the hologram structure of FIG. 32A. FIG. 32C shows an optical image reproduced by overlapping the optical image shown in FIG. 32A and the optical image shown in FIG. 32B. FIG. 33 shows the wavelength distributions of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to an example of the reflective hologram structure according to the modified example 2-3. It is a graph which shows, in particular, the case where the incident angle of the regenerated light is 0 °. FIG. 34 shows an example of an optical image reproduced by a hologram structure having the characteristics shown in FIG. 33 when the incident angle of the reproduced light is 0 °. FIG. 35 is a graph showing the wavelength distributions of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to the hologram structure of FIG. The case where the incident angle of is 30 ° is shown. FIG. 36 shows an example of an optical image reproduced by a hologram structure having the characteristics shown in FIG. 35 when the incident angle of the reproduced light is 30 °. FIG. 37 is a graph showing the relationship between the wavelength of light (horizontal axis) and the luminous efficiency (vertical axis). FIG. 38 is a diagram showing an example of the relationship between the wavelength (horizontal axis) and the diffraction efficiency (vertical axis) of a general hologram structure. FIG. 39 is a diagram showing an example of an optical image reproduced by the hologram structure having the diffraction characteristics of FIG. 38. FIG. 40 is a diagram showing an example of the relationship between the wavelength (horizontal axis) and the diffraction efficiency (vertical axis) of the hologram structure according to the third embodiment. FIG. 41 is a diagram showing an example of an optical image reproduced by the hologram structure having the diffraction characteristics of FIG. 40. FIG. 42A is a schematic view for explaining an optical image reproduced by an example of the reflective hologram structure according to the modified example 3-1 and shows an optical image reproduced through the first region. FIG. 42B shows an optical image reproduced through the second region of the hologram structure of FIG. 42A.

Hereinafter, the light modulation element according to the embodiment of the present invention will be described.

The light modulation element of each of the following embodiments is composed of a phase modulation type hologram structure that modulates the phase of the incident reproduced light and reproduces an optical image, and in particular, an element element composed of a Fourier transform hologram. including. The Fourier transform hologram is a hologram produced by recording the wavefront information of the Fourier transform image of the original image, and functions as a so-called Fourier transform lens. In particular, the phase-modulated Fourier transform hologram is a hologram having an uneven surface produced by multi-valued the phase information of the Fourier transform image and recording it on a medium as a depth, and is a diffraction phenomenon based on the optical path length difference of the medium. Is used to reproduce the optical image of the original image from the reproduced light. This Fourier transform hologram is advantageous in that, for example, a desired optical image (that is, an original image) can be reproduced with high accuracy, but it can be produced relatively easily. Such a phase modulation type light modulation element is also called quinoform. However, the element elements of the light modulation element to which the present invention can be applied are not limited to the Fourier transform hologram, and the present invention is also applied to a hologram that reproduces an optical image by another method or a light modulation element having another structure. Can be applied.

In the following description, white light containing various wavelengths is given as an example of the reproduced light incident on the hologram structure, but the reproduced light does not necessarily have to be white light. That is, the wavelength included in the reproduced light is not particularly limited as long as the light having a wavelength corresponding to the color of the light image reproduced by the hologram structure is included. Further, in the following description, unless otherwise specified, it is assumed that the incident angle of the reproduced light with respect to the hologram structure is 0 ° (that is, the angle along the normal direction of the incident surface of the hologram structure). Further, unless otherwise specified, the specific value of the refractive index shown in the present specification is based on light having a wavelength of 589.3 nm. Further, in the following description, the refractive index and the characteristic value of the uneven surface shown with respect to the hologram structure 11 are the cases where the hologram structure 11 is used in an air environment having a refractive index of 1.0 unless otherwise specified. It is a value derived by assuming it.

Further, in the present specification, the concept of "two or more optical images having the same shape" includes not only two or more optical images having the same size and the same shape (overall shape), but also the size. Two or more optical images that are different from each other and have the same shape are also included. That is, two or more optical images having the same shape may or may not have the same size as long as they have the same shape, and two or more optical images having a similar relationship with each other have the same shape. It corresponds to "two or more light images having". Therefore, two or more optical images having different sizes to be reproduced due to different constituent wavelengths of the optical images correspond to "two or more optical images having the same shape with each other" if the overall shape is the same. do.

Further, in the present specification, the concept of two optical images having a "point symmetry" relationship includes not only two optical images having the same size and the same shape (overall shape), but also mutual sizes. Also included are two light images that are different and have the same shape. That is, as long as the two optical images having the same shape have the same shape and the reproduction position and the reproduction direction have point symmetry, it does not matter whether the sizes are the same or not. Therefore, for example, two optical images having a similar relationship with each other and having a point symmetry in the reproduction position and the reproduction direction correspond to "two optical images having a point symmetry relationship with each other". .. Therefore, if two or more optical images having different reproduction sizes due to different constituent wavelengths of the optical images have the same shape, and the reproduction position and the orientation of the optical image have point symmetry. , "Two or more optical images having a point-symmetrical relationship with each other".

[First Embodiment]
FIG. 1 is a schematic plan view showing a typical example of the hologram holder 10. FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

The hologram holder 10 shown in FIGS. 1 and 2 includes a hologram layer 1, a reflection layer 2 laminated on one surface of the hologram layer 1, and a base material 4 laminated on the other surface of the hologram layer 1. And. A reflective hologram structure 11 is provided in a part of the hologram holder 10. In the hologram structure 11, one surface of the hologram layer 1 forms an uneven surface 1a, and the reflection layer 2 covering the uneven surface 1a also has an uneven shape. The uneven surface 1a of the hologram structure 11 has an uneven pattern corresponding to the Fourier transformed image of the original image, and has a corresponding uneven depth for each pixel of the Fourier transformed image. For example, a resin (for example, UV curable resin or thermoplastic resin) constituting the hologram layer 1 is formed on a base material 4 (for example, PET: polyethylene terephthalate) by coating or the like, and the hologram layer 1 is subjected to UV curing treatment. Along with the heat and pressure treatment, the uneven surface shaping process of pressing the uneven surface of the original plate is performed, and then the reflective layer 2 (for example, Al, ZnS, TiO _2, etc.) is formed on the uneven surface 1a of the hologram layer 1. Therefore, the hologram holder 10 shown in FIGS. 1 and 2 can be manufactured. Although not shown, other members such as an adhesive, an adhesive, and / or a heat seal layer may be further formed on the reflective layer 2.

When light is incident on such a hologram structure 11 from a point light source or a parallel light source, an optical image (that is, an original image) corresponding to the uneven pattern of the uneven surface 1a is reproduced. This type of light modulation element does not require a screen or the like for projecting an optical image, and reproduces an optical image particularly well when light from a specific light source such as a point light source or a parallel light source is incident. , Convenient and widely available for design, security, or other uses. The optical image reproducible by such a light modulation element is not particularly limited, and for example, characters, symbols, line drawings, patterns, patterns, combinations thereof, and the like can be used as an original image and a reproducible optical image.

As an example, the hologram holder 10 shown in FIGS. 1 and 2 including the hologram structure 11 that functions as a light modulation element as described above and the base material 4 that supports the hologram structure 11 records information such as a passport. The medium can be suitably configured. For example, the hologram structure 11 is determined to be authentic by designing the hologram structure 11 so that the light image reproduced by the hologram structure 11 represents information based on at least one of characters, symbols, and patterns. It can be suitably used for security applications such as. Although the transparent base material 4 is used in the hologram holder 10 shown in FIGS. 1 and 2, an opaque base material may be used instead. In that case, for example, an opening 4a (see FIG. 2) having a predetermined size is formed on the base material, and at least a part of the hologram structure 11 provided as the light modulation element is arranged at a position corresponding to the opening 4a. Therefore, the hologram holder 10 can preferably form an information recording medium such as a passport. The opening 4a may be provided with a hole (space), or instead of providing the hole (space) or the hole (space), only the opening 4a is composed of a transparent body (that is, a transparent base material). You may. Even when the transparent base material 4 is used, for example, by providing a printed body that regulates the transmission of light in a portion of the base material 4 other than the opening 4a, the opening portion of the base material 4 is basically used. The hologram holder 10 may be configured so that light is transmitted only through 4a. Further, an opening may be formed in an information recording medium such as a passport, and the hologram holder 10 may be arranged in the opening. In this case, a hole (space) and / or a transparent body may be provided in the opening portion of the information recording medium, and a printing body that regulates the transmission of light is provided in a portion of the information recording medium other than the opening portion. The information recording medium may be configured so that light transmits only through the openings of the information recording medium.

The hologram structure 11 includes a reflective hologram structure in which the observer 50 and the light source 51a are arranged on the same side with respect to the hologram structure 11 as shown in FIG. 3, and the observer 50 and the light source as shown in FIG. 51b can be classified into a transmission type hologram structure in which 51b is arranged on different sides from each other via the hologram structure 11. As the reflective hologram structure, in addition to the structure provided with an additional layer for reflecting the reproduced light such as the reflection layer 2 shown in FIG. 2, the hologram layer 1 is provided without an additional reflection layer. There is a structure in which the uneven surface 1a is exposed to air and the regenerated light is reflected by utilizing the difference in the refractive index between the hologram layer 1 such as a UV curable resin and the air. On the other hand, the transmissive hologram structure is not provided with such a reflective layer. However, the reflective hologram structure and the transmissive hologram structure are common in that the concave-convex surface 1a is formed on the hologram layer 1 and a desired light image is reproduced by a diffraction phenomenon caused by the difference in optical path length of the uneven surface 1a. do. Regarding the specific unevenness depth of the uneven surface 1a, there are optimum values for each of the transmissive hologram structure and the reflective hologram structure. In the following, the contents described only for either the reflective hologram structure or the transmissive hologram structure are basically described for both the reflective hologram structure and the transmissive hologram structure unless otherwise specified. On the other hand, it can be applied.

FIG. 5 is a conceptual diagram showing the planar structure of the hologram structure 11. The hologram structure 11 of the present embodiment includes a plurality of element elements (also referred to as “hologram cells”) 21 arranged two-dimensionally and regularly. Each element element 21 has the above-mentioned uneven surface 1a and has a plane size of several nm to several mm square (for example, 2 mm square), and modulates the phase of the reproduced light to reproduce an optical image.

The uneven surface 1a has a multi-step shape (that is, a step shape of two or more steps), and the number of steps of the uneven surface 1a is not particularly limited. When reproducing an optical image with a plurality of colors, the uneven surface 1a preferably has three or more steps, and in particular, the uneven surface 1a having four or more steps makes an original image having a complicated composition high-definition. It is possible to reproduce. 6 and 7 are cross-sectional views of the element element 21 showing an outline of the step structure of the uneven surface 1a, FIG. 6 shows an 8-step type uneven surface 1a, and FIG. 7 shows a 4-step type uneven surface 1a. show. Note that FIGS. 6 and 7 show element elements 21 having uneven surfaces 1a having the same step shape, but the actual uneven surface 1a is a step corresponding to the reproduced light image (that is, the original image). Has a shape. The pitch of the uneven pattern on the uneven surface 1a (that is, the pixel pitch (see the sign “P” shown in FIGS. 6 and 7)) is in the range of 0.1 μm to 80.0 μm from the viewpoint of accurately reproducing the optical image. It is preferably present, and usually 1 μm or more is preferable.

FIG. 8 is a graph showing an example of the relationship between the wavelength distribution of the primary diffracted light of each element element 21 and the diffraction efficiency. In FIG. 8, the horizontal axis represents the wavelength and the vertical axis represents the diffraction efficiency. Diffraction efficiency is represented by the amount obtained by dividing the radiant flux of light diffracted in a certain direction by the radiant flux of light incident on each element element 21, the diffracted radiant flux in a certain direction is represented by P, and the incident radiant flux is P0. When represented by, the diffraction efficiency η is a non-dimensional number represented by “η = P / P0”. Each element element 21 exhibits a unique diffraction efficiency depending on the wavelength, and in the example shown in FIG. 8, light having a wavelength near 580 nm (see the sign “H1” in FIG. 8) has a maximum diffraction efficiency Dmax with respect to the primary diffraction light. Is shown. Although FIG. 8 shows an example of the wavelength distribution of the primary diffracted light, the wavelength distribution of the -1st diffracted light also shows a peculiar diffraction efficiency according to the wavelength and also shows the maximum diffraction efficiency at a specific wavelength.

In the present embodiment, the maximum diffraction efficiency Dmax in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for each element element 21 is the maximum. In the wavelength distribution of the diffraction efficiency including the diffraction efficiency Dmax, a maximum value having a half-value full width FWHM of 200 nm or less is formed. The full width at half maximum FWHM referred to here indicates the wavelength band (wavelength width) at a position having half the value (Dmax / 2) of the maximum diffraction efficiency Dmax in the wavelength distribution of the diffraction efficiency (see FIG. 8).

When each element element 21 has such a diffraction characteristic, light having a wavelength corresponding to the maximum diffraction efficiency Dmax and a wavelength in the vicinity thereof is diffracted more efficiently than light in another wavelength band, which contributes to a reproduced image. .. Therefore, even when white light including light of various wavelengths is incident on each element element 21, each element element 21 is not white due to light having a wavelength corresponding to the maximum diffraction efficiency Dmax and a wavelength in the vicinity thereof. Reproduce the light image with the color of. Therefore, by adjusting the diffraction characteristics of each element element 21 (particularly the wavelength distribution of the first-order diffracted light and the wavelength distribution of the -1st-order diffracted light) and making the wavelength corresponding to the maximum diffraction efficiency Dmax correspond to the color of the reproduced image, it is white. Even if light is incident on each element element 21, it is possible to reproduce an optical image with a specific color.

The uneven surface 1a of each element element 21 includes three or more different heights, and has a wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light. It is preferable that there is no other maximum value having a diffraction efficiency of half or more of the maximum diffraction efficiency. That is, the second highest diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light of each element element 21 and the wavelength distribution of the diffractive efficiency of the -1st diffracted light (symbol of FIG. The maximum value of H2 ”) is preferably less than half of the maximum diffraction efficiency Dmax. In this case, color bleeding and line thickening in the reproduced image can be effectively prevented, and the optical image can be reproduced in high definition.

FIG. 9 is a schematic diagram for explaining an optical image 100 reproduced by a general hologram structure 11. 10 to 12 are schematic views for explaining the optical image 100 reproduced by the hologram structure 11 of the first embodiment. In each of FIGS. 9 to 12, the light source used in the reflective hologram structure 11 is indicated by the code “51a”, and the light source used in the transmissive hologram structure 11 is indicated by the code “51b”. .. Further, in the following description, these light sources 51a and 51b are collectively represented by using the sign "51".

Generally, in the diffraction phenomenon, the larger the wavelength of the incident light, the larger the diffraction angle of the diffracted light other than the 0th-order diffracted light. Therefore, when white light is incident on a general hologram structure 11 having the same degree of diffraction efficiency over the entire visible light wavelength band from the light source 51, the hologram structure 11 has an iridescent color as shown in FIG. The optical image 100 is reproduced. On the other hand, when white light is incident on the hologram structure 11 of the present embodiment having the above-mentioned maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less, the hologram structure 11 is shown in FIGS. 10 to 12. Such a monochromatic light image 100 is reproduced. That is, the hologram structure 11 (particularly the uneven surface 1a) of the present embodiment has a diffraction structure optimized for light in a specific wavelength and a wavelength band in the vicinity thereof, and has a specific wavelength among light having various wavelengths. The light image 100 of a specific color is reproduced by selectively using the light of the wavelength band in and around the same. For example, the hologram structure 11 of FIG. 10 shows the maximum diffraction efficiency in the blue wavelength band and reproduces the blue light image 100. The hologram structure 11 of FIG. 11 shows the maximum diffraction efficiency in the green wavelength band and reproduces the green light image 100. The hologram structure 11 of FIG. 12 shows the maximum diffraction efficiency in the red wavelength band and reproduces the red light image 100. The light images 100 of FIGS. 10 to 12 are different in size from each other, which is caused by the difference in wavelength of the light (that is, the first-order diffracted light and / or the first-order diffracted light) constituting the light image 100. It is based on the difference in refraction angle.

As described above, the hologram structure 11 of the present embodiment can reproduce the monochromatic light image 100 even when white light is incident. The light image 100 reproduced in this way is a clear image with almost no blurring due to color dispersion. Further, since the light image 100 can be reproduced in a specific color, it is possible to give the observer 50 a specific impression based on the color. It is also possible to reproduce the light image 100 in color and clearly convey the concept of the light image 100 to the observer 50. Further, since the hologram structure 11 is configured to reproduce a specific monochromatic light image 100, for example, in the authenticity determination, not only the "picture" of the reproduced light image 100 but also the light concerned is used as the basis of the determination. The "color" of the image 100 can be used, enabling highly reliable authenticity determination. Further, the hologram structure 11 of the present embodiment does not need to add a layer that selectively transmits or reflects light in a specific wavelength band, so that the manufacturing cost can be reduced and the observer 50 surrounds the hologram structure 11 through the hologram structure 11. There is no sense of discomfort in the observed image even when observing.

[Manufacturing method of hologram structure 11]
Next, an example of a method for manufacturing the hologram structure 11 (particularly the uneven surface 1a) will be described. The method described below is only an example, and another method capable of appropriately producing the hologram structure 11 including the desired uneven surface 1a can be adopted. Further, the manufacturing method described below can be applied to both the reflective hologram structure 11 (see FIG. 3) and the transmissive hologram structure 11 (see FIG. 4).

First, a two-dimensional image of the original image is read by a computer (Step 1). Then, the computer obtains a two-dimensional complex amplitude image by using each pixel value of the read two-dimensional image as an amplitude value and assigning a random value between 0 and 2π as a phase value for each pixel (). Step2). Then, the computer obtains a two-dimensional Fourier transform image by performing a two-dimensional Fourier transform of the two-dimensional complex amplitude image (Step 3). If necessary, the computer may perform arbitrary optimization processing such as an iterative Fourier transform method or a genetic algorithm (Step 4). Then, the computer sets the phase value of each pixel of the two-dimensional Fourier transform image in four stages (for example, "0", "π / 2", "π" and "3π / 2", or "0", " It is discreteized into 8 stages of "π / 4", "π / 2", "3π / 4", "π", "5π / 4", "3π / 2" and "7π / 4" (Step 5).

Then, the hologram structure 11 (particularly the uneven surface 1a) corresponding to the two-dimensional Fourier transformed image is produced so that each pixel has a depth corresponding to the discretized corresponding phase value (Step 6). For example, when the pixel values of the two-dimensional Fourier transformed image are discretized in four steps in Step 5, a concave-convex surface 1a (see FIG. 7) having a depth of four steps is formed in the hologram layer 1 in Step 6. NS. The depth of the uneven surface 1a is determined by considering not only the diffraction efficiency characteristics to be realized but also various other related parameters (for example, the refractive index of the material constituting the hologram structure 11 (particularly the hologram layer 1)). Is determined by. For example, as a reflective hologram structure 11 for reproducing a blue light image, a hologram structure 11 in which the number of steps of the uneven surface 1a is four and the uneven surface 1a has an optical path length of 330 nm per step is produced. be able to. The reflective hologram structure 11 and the transmissive hologram structure 11 each have a unique concave-convex surface 1a depth structure, and even when trying to realize the same diffraction characteristics, for example, the hologram structure The specific value of the depth of the uneven surface 1a of the body 11 differs between the reflective type and the transmissive type.

The manufacturing apparatus of the hologram structure 11 is not particularly limited, and may be, for example, an apparatus controlled by a computer that executes Steps 1 to 5 described above, or an apparatus provided separately from the computer. .. Further, if necessary, a master mold (that is, a master master plate) corresponding to the structure of the hologram structure 11 (particularly the uneven surface 1a) described above may be made by an exposure apparatus based on a photolithography technique, an electron beam drawing apparatus, or the like. (Step 7). For example, a liquid ultraviolet curable resin is dropped on a mother mold, and the ultraviolet curable resin sandwiched between a base film (for example, PET film (polyethylene terephthalate film)) and the mother mold is irradiated with ultraviolet rays. The hologram structure 11 having a desired uneven surface 1a can be produced by peeling the ultraviolet curable resin together with the base film from the base film. As another method, for example, a method using a thermoplastic ultraviolet curable resin, a method using a thermoplastic resin, a method using a thermosetting resin, and a method using an ionizing radiation curable resin may be adopted. By using the master mold in this way, it is possible to easily and in large quantities to duplicate the hologram structure 11 having the desired uneven surface 1a.

In the case of the reflective hologram structure 11, a reflective layer 2 (for example, a reflective layer composed of Al or a reflective layer composed of ZnS or TiO ₂ (high refractive index layer)) is further formed on the uneven surface 1a by the manufacturing apparatus. It may be formed. However, in the case of the hologram structure 11 that reflects the reproduced light by utilizing the difference in the refractive index between the hologram layer 1 and the air, the uneven surface of the hologram layer 1 is not provided additionally. You may leave 1a exposed to the air. Further, if necessary, another functional layer such as an adhesive layer (for example, a heat seal layer or a primer layer for enhancing the adhesion between adjacent layers) may be formed on the hologram layer 1. Further, for example, when the reflective layer 2 is formed on the uneven surface 1a of the hologram layer 1, an adhesive layer is formed on the surface of the reflective layer 2 having an uneven shape (the surface opposite to the hologram layer 1), and the adhesive layer is formed. The layer may fill the recesses on the surface of the reflective layer 2.

[Depth of uneven surface]
As an example, in the reflective hologram structure 11, the refractive index of the hologram layer 1 is 1.5, and the depth per step of the uneven surface 1a (see the sign “d” in FIGS. 6 and 7) is 110 nm. In this case, the optical path length per step of the uneven surface 1a is 330 nm. In this case, since the uneven surface 1a has a four-step depth structure, the hologram structure 11 exhibits the above-mentioned maximum diffraction efficiency in the blue wavelength band and reproduces a blue light image.

As another example, in the reflective hologram structure 11, the hologram layer 1 has a refractive index of 1.5, the uneven surface 1a has an eight-step depth structure, and the depth per step is 130 nm. In this case, the hologram structure 11 reproduces a blue light image. Further, in the transmissive hologram structure 11, when the refractive index of the hologram layer 1 is 1.5, the uneven surface 1a has a four-step depth structure, and the depth per step is 660 nm, the hologram structure Body 11 reproduces a blue light image. Further, in the reflective hologram structure 11, when the refractive index of the hologram layer 1 is 1.5, the uneven surface 1a has a depth structure of 8 steps, and the depth per step is 230 nm, the hologram structure is formed. Body 11 reproduces a red light image. Further, in the reflective hologram structure 11, when the refractive index of the hologram layer 1 is 1.5, the uneven surface 1a has a depth structure of 6 steps, and the depth per step is 220 nm, the hologram structure is formed. Body 11 reproduces a green light image.

The color (wavelength band) of the light image reproduced by the above-mentioned transmissive hologram structure 11 is assumed to be used in an air environment having a refractive index of 1.0. Further, when the observer observes the light image 100 reproduced by the above-mentioned reflective hologram structure 11, the uneven surface 1a of the hologram layer 1 is arranged on the opposite side to the observer, and the observer passes the uneven surface 1 through the hologram layer 1. The structure (that is, the uneven surface 1a) will be observed. When the uneven surface 1a of the hologram layer 1 is arranged on the same side as the observer, the reflected image from the hologram structure 11 observed by the observer is due to the light reflected on the surface without passing through the hologram layer 1. It is composed. For example, when the uneven surface 1a is formed on the surface of the card-shaped hologram holder 10, the observer observes the light reflected by the uneven surface 1a without passing through the hologram layer 1. In such a case, the optical path length based on the refractive index of the medium on the observer side of the hologram layer 1, for example, the refractive index of air 1.0, rather than the refractive index of the hologram layer 1, is one step of the uneven surface 1a. It is necessary to set the hit depth. Therefore, the observer can observe the desired image by designing the structure of the uneven surface 1a while assuming that the refractive index of the hologram layer 1 (hologram structure 11) is 1.0 of the refractive index of air. be. Specifically, when the refractive index of air is 1.0 and the depth of the uneven surface 1a per step is 165 nm, the optical path length of the uneven surface 1a per step is 330 nm. In this case, since the uneven surface 1a has a four-step depth structure, the hologram structure 11 exhibits the maximum diffraction efficiency in the blue wavelength band and reproduces a blue light image.

[Relationship between the depth of the uneven surface and the peak wavelength of the diffracted light]
When the number of steps of the concave-convex surface 1a of the hologram structure 11 is represented by N, the optical path length modulated per step of the concave-convex surface 1a is represented by l, and the natural number is represented by m, the peak wavelength λ of the diffracted light is as follows. It is expressed by the formula of.

λ = N · l / (mN ± 1)

As described above, the hologram structure 11 of the present embodiment can reproduce an optical image in a single color even when white light is incident. This is realized, for example, when either the first-order diffracted light or the first-order diffracted light of the hologram structure 11 has only one peak wavelength λ in the visible light wavelength band for an arbitrary natural number m. It is possible. For example, when the optical path length l is 330 nm and the number of steps N of the uneven surface 1a is 4, λ = 1320 / (4 m ± 1) holds. Therefore, for m = 1, λ = 440 nm and 264 nm, for m = 2, λ = 188 nm and 146 nm, and for m = 3, λ = 120 nm and 101 nm. When m is 4 or more, the peak wavelength λ becomes a smaller value. Of these, the peak wavelength λ included in the visible light wavelength band is only λ = 440 nm when m = 1. Therefore, when the hologram structure 11 in which the number of stages N = 4 of the uneven surface 1a and the optical path length per stage is l = 330 nm is used, the observer 50 can visually recognize the light having a wavelength of 440 nm and a wavelength in the vicinity thereof. It is possible to reproduce a possible monochromatic optical image.

[Modification 1-1]
The hologram structure 11 of this modification is a combination of a plurality of types of element elements 21 having different wavelengths showing maximum diffraction efficiency in a wavelength band of 380 nm or more and 780 nm or less, and when white light is incident, the hologram structure 11 emits light in a plurality of colors. The image can be reproduced. That is, the hologram structure 11 includes at least two or more types of element elements 21, and a wavelength indicating the maximum diffraction efficiency of these at least two or more types of element elements 21 (particularly, a visible light wavelength band (particularly, a wavelength band of 380 nm or more and 780 nm or less). ) Are different from each other, the optical image can be reproduced with a color corresponding to the wavelength indicating the maximum diffraction efficiency of each type of element element 21.

FIG. 13 is a conceptual diagram showing an example of the planar structure of the transmissive hologram structure 11 according to the modified example 1-1. FIG. 14 is a schematic diagram for explaining the light image 100 reproduced by the transmissive hologram structure 11 of FIG. The hologram structure 11 shown in FIGS. 13 and 14 includes a plurality of first element elements 21a and a plurality of second element elements 21b arranged in a checkered pattern. For example, the plurality of first element elements 21a have a concavo-convex surface 1a (that is, the above-mentioned maximum diffraction efficiency) that enables reproduction of the light image 100 of the blue letter "O", and the plurality of second element elements 21a. The element element 21b has an uneven surface 1a that enables reproduction of the light image 100 of the red letter "K". In this case, when white light is incident on the hologram structure 11, the hologram structure 11 reproduces a blue “O” and a red “K” as shown in FIG. As described above, the hologram structure 11 of the present modification can visually reproduce the two types of monochromatic light images 100. In the example shown in FIG. 14, the first element element 21a and the second element element 21b reproduce the independent optical image 100, but the optical image reproduced by the first element element 21a and the second element The light image reproduced by the element 21b may overlap at least in part. In this case, the light image of the overlapping portion has a color in which the color of the light image reproduced by the first element element 21a and the color of the light image reproduced by the second element element 21b are mixed.

FIG. 15 is a conceptual diagram showing another example of the planar structure of the transmissive hologram structure 11 according to the modified example 1-1. FIG. 16 is a schematic diagram for explaining an optical image 100 reproduced by the transmissive hologram structure 11 of FIG. The hologram structure 11 shown in FIGS. 15 and 16 includes a plurality of first element elements 21a, a plurality of second element elements 21b, and a plurality of third element elements 21c arranged in a checkered pattern. For example, the plurality of first element elements 21a have an uneven surface 1a (that is, the above-mentioned maximum diffraction efficiency) that enables reproduction of a blue light image 100, and the plurality of second element elements 21b are red. The plurality of third element elements 21c have an uneven surface 1a that enables the reproduction of the light image 100, and the plurality of third element elements 21c have an uneven surface 1a that enables the reproduction of the green light image 100. In this case, the hologram structure 11 can reproduce not only the red, blue, and green light images 100, but also the light images 100 of other colors by superimposing two or more of these light images 100. .. For example, as shown in FIG. 16, by superimposing and reproducing the light image 100 of the red circle, the light image 100 of the green circle, and the light image 100 of the blue circle, the portion where the red circle and the green circle overlap is a yellow light image. It becomes 100, the part where the green circle and the blue circle overlap becomes the light blue light image 100, the part where the blue circle and the red circle overlap becomes the purple light image 100, and the part where the red circle, the green circle and the blue circle overlap becomes 100. It becomes a white light image 100.

FIG. 17 is a schematic diagram for explaining an optical image 100 reproduced by another example of the transmissive hologram structure 11 according to the modified example 1-1. Each element element 21 can reproduce an optical image with a color having an arbitrary gradation, and the first element element 21a for reproducing a red optical image and the second element for reproducing a blue optical image. Each of the element 21b and the third element element 21c that reproduces a green light image can include a plurality of types of element elements having different gradations. Further, even when each element element 21 is designed based on an original image having an arbitrary gradation, it is possible to reproduce an optical image with a color having an arbitrary gradation. In these cases, the hologram structure 11 can also reproduce the full-color optical image 100 as shown in FIG. 17 when white light is incident.

In the hologram structure 11 shown in FIGS. 13 and 15 described above, the types of element elements 21 arranged adjacent to each other in both the vertical direction and the horizontal direction are different from each other, but the arrangement mode of the plurality of types of element elements 21 is different. There is no particular limitation. For example, the hologram structure 11 may include a plurality of types of element elements 21 arranged in a stripe shape, and the types of element elements 21 arranged adjacent to each other in one of the vertical direction and the horizontal direction may be included. Although different, the types of element elements 21 arranged adjacent to each other may be the same for the other. Further, a plurality of types of element elements 21 may be arranged depending on the arrangement mode in which the above-mentioned checkered pattern arrangement and the striped arrangement are combined.

[Modification 1-2]
In the hologram structure 11, different types of element elements 21 may be arranged in different regions, and the different types of element elements 21 have primary diffracted light and / or -1 next time in a wavelength band of 380 nm or more and 780 nm or less. The wavelengths indicating the maximum diffraction efficiency of the folding light may be different from each other. On the other hand, the optical images reproduced by different types of element elements 21 arranged in different regions may have shape relationships with each other. The light images having a shape relationship as used herein include, for example, a pair of light images having the same or substantially the same shape visually, and the sizes of these light images may be the same as each other. It may be different. Further, the optical images having a shape relationship include, for example, a pair of optical images that form a pattern, a character, or the like having a specific intention by combining the optical images with each other. For example, the hologram structure 11 shown in FIGS. 13 to 17 can reproduce one picture, characters, or the like as an optical image without moving the hologram structure 11 relative to the observer. On the other hand, in the hologram structure 11 shown in FIGS. 18A to 18B and the hologram structure 11 shown in FIGS. 19A to 19B described below, the hologram structure 11 is relatively continuously reciprocated with respect to the observer. Therefore, the combination of the afterimage of the optical image reproduced by the element element 21 of the first region 25 and the afterimage of the optical image reproduced by the element element 21 of the second region 26 causes the above-mentioned "shape relevance". It is possible to construct a "light image to have".

FIG. 18A is a schematic view for explaining the light image 100 reproduced by an example of the hologram structure 11 according to the modification 1-2, and shows the light image 100 reproduced through the first region 25. .. FIG. 18B shows the light image 100 reproduced through the second region 26 of the hologram structure 11 of FIG. 18A. The hologram structure 11 of FIGS. 18A and 18B includes a first region 25 and a second region 26. A plurality of element elements 21 including at least the first type element element are arranged in the first region 25, and a plurality of element elements 21 including at least the second type element element are arranged in the second region 26. Will be done. In the wavelength band of 380 nm or more and 780 nm or less, the wavelength showing the maximum diffraction efficiency for the first type element element is different from the wavelength showing the maximum diffraction efficiency for the second type element element. In the hologram structure 11 shown in FIGS. 18A and 18B, the first type element element 21 whose wavelength showing the maximum diffraction efficiency is included in the blue wavelength band is arranged in the first region 25, and the wavelength showing the maximum diffraction efficiency. The second type element element 21 included in the red wavelength band is arranged in the second region 26. The optical image 100 reproduced by the plurality of element elements 21 arranged in the first region 25 has a shape relationship with the optical image 100 reproduced by the plurality of element elements 21 arranged in the second region 26. Has. Specifically, the element element 21 in the first region 25 and the element element 21 in the second region 26 reproduce an optical image 100 having the same star shape but different colors.

FIG. 19A is a schematic view for explaining the light image 100 reproduced by another example of the hologram structure 11 according to the modified example 1-2, and the light image 100 reproduced through the first region 25. Is shown. FIG. 19B shows the light image 100 reproduced through the second region 26 of the hologram structure 11 of FIG. 19A. The hologram structure 11 of FIGS. 19A and 19B has substantially the same structure as the hologram structure 11 of FIGS. 18A and 18B. However, in the hologram structure 11 of FIGS. 18A and 18B, the light image 100 reproduced by the element element 21 in the first region 25 and the light image 100 reproduced by the element element 21 in the second region 26 are mutually large. In contrast to the light image 100 reproduced by the element element 21 in the first region 25 and the light reproduced by the element element 21 in the second region 26 in the hologram structure 11 of FIGS. 19A and 19B. The image 100 and the image 100 have substantially the same size as each other.

When the uneven surface 1a of the element element 21 in the first region 25 and the uneven surface 1a of the element element 21 in the second region 26 are produced based on the original images of the same size, the wavelength (color) of the diffracted light is different. The size of the reproduced light image 100 differs between the first region 25 and the second region 26 (see FIGS. 18A and 18B). On the other hand, by manufacturing the element element 21 of the first region 25 and the element element 21 of the second region 26 in consideration of the difference in the size of the optical image 100 based on the difference in the wavelength of the diffracted light, FIG. 19A and FIG. As shown in FIG. 19B, it is possible to make the light image 100 reproduced by the element element 21 in the first region 25 and the light image 100 reproduced by the element element 21 in the second region 26 substantially the same size. be. Specifically, by changing the size of the original image used when designing the element element 21 of the first region 25 to the size of the original image used when designing the element element 21 of the second region 26. , The size of the light image 100 can be made substantially the same between the first region 25 and the second region 26. Further, since the diffraction angle can be changed according to the pixel size of each element element 21, the size of each pixel constituting the element element 21 can be changed between the first region 25 and the second region 26. Therefore, the size of the light image 100 can be made substantially the same between the first region 25 and the second region 26.

As described above, in the hologram structure 11 of the present modification, as shown in FIGS. 18A, 18B, 19A and 19B, a first light image 100 having shapes related to each other and having different colors is reproduced. The region 25 and the second region 26 are provided side by side. The observer 50 continuously and repeatedly observes the light image 100 through the first region 25 and the light image 100 through the second region 26 while moving the hologram structure 11. , It is possible to recognize the change in color of the light image 100 while recognizing the same shape of the light image 100. Such a hologram structure 11 can be used for design purposes, but is particularly suitable for security applications such as authenticity determination. The observer 50 can easily verify the authenticity of the hologram holder 10 (see FIG. 1) by confirming whether or not the shape of the optical image 100 is the same and whether or not the color of the optical image 100 is changed by using white light. It is possible to make a reliable judgment. In particular, according to the hologram structure 11 shown in FIGS. 19A and 19B, not only the color change and the same shape of the light image 100 but also the same size of the light image 100 can be confirmed. It is possible to perform highly accurate authenticity judgment.

[Second Embodiment]
In the present embodiment, the same or similar elements as those of the above-described first embodiment and its modifications are designated by the same reference numerals, and detailed description thereof will be omitted. Further, among the above-mentioned explanatory items regarding the first embodiment and its modifications, detailed description of the matters that can be similarly applied to the hologram structure 11 of the present embodiment will be omitted.

The hologram holder 10 and the hologram structure 11 according to the present embodiment have the same configuration as that of the first embodiment described above, and the hologram structure 11 is shown in FIGS. 1, 2, and 5 to 7. It has such an element element 21 and an uneven surface 1a, and may be either a reflective type (see FIG. 3) or a transmissive type (see FIG. 4). Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for each element element 21 of the hologram structure 11 is the maximum. In the wavelength distribution of diffraction efficiency including the diffraction efficiency, a maximum value having a half-value full width of 200 nm or less is formed.

In the hologram structure 11 according to one mode of the present embodiment, the above-mentioned maximum diffraction efficiency is included in one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light. Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light is the wavelength distribution of the other diffraction efficiency. In, a maximum value having a half-value full width of 200 nm or less is formed. Further, in the hologram structure 11 according to the other mode of the present embodiment, the above-mentioned maximum diffraction efficiency is included in both the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light. That is, in the hologram structure 11 according to the other mode, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light. The maximum diffraction efficiencies in the wavelength band of 380 nm or more and 780 nm or less are equal to each other. When white light is incident on the hologram structure 11 according to these modes, the first light image and the second light image can be reproduced in a color other than white by the first-order diffracted light and the first-order diffracted light.

The hologram structure 11 of the above-described embodiment has a wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light. The wavelength showing the maximum diffraction efficiency and the wavelength showing the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light. The difference from the above is preferably 100 nm or less. In this case, in the wavelength band of 380 nm or more and 780 nm or less, the wavelength showing the maximum diffraction efficiency of the primary diffracted light and the wavelength showing the maximum diffraction efficiency of the -1st diffracted light are very close to each other, and the optical image reproduced by the primary diffracted light. And the color of the light image reproduced by the -1st order diffracted light are included in the same or very similar color system.

In the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light, the maximum diffraction efficiency in the wavelength distribution of the other diffraction efficiency. It is preferable that there is no other maximum value having a diffraction efficiency of half or more of. That is, the maximum value of the second largest diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the -1st-order diffracted light is the first time. It is preferable that it is less than half of the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the folding light and the wavelength distribution of the diffraction efficiency of the -1st order diffracted light. Further, in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light, the maximum diffraction efficiency in the wavelength distribution of the other diffraction efficiency. It is preferable that there is no other maximum value having a diffraction efficiency of half or more of. That is, the maximum value of the second highest diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light is the first order. It is preferable that it is less than half of the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the folding light and the wavelength distribution of the diffraction efficiency of the -1st order diffracted light.

The hologram structure 11 that satisfies these conditions effectively prevents color bleeding (color change) and line thickening, and reproduces a high-definition first light image and a second light image in different colors from each other. It is possible.

Hereinafter, a specific example of the optical image 100 reproduced by the hologram structure 11 of the present embodiment will be described. In the following description, the "maximum diffraction efficiency" refers to the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less included in the visible light wavelength band.

FIG. 20 is a graph showing the wavelength distributions of the 0th-order diffracted light, the 1st-order diffracted light, and the -1st-order diffracted light according to an example of the reflective hologram structure 11 according to the second embodiment, and the horizontal axis represents the wavelength. The vertical axis shows the diffraction efficiency. In each drawing (particularly a graph) such as FIG. 20, the wavelength distribution of the 0th-order diffracted light is indicated by "W0", the wavelength distribution of the 1st-order diffracted light is indicated by "W1", and the wavelength distribution of the -1st-order diffracted light is "W". -1 "is shown. FIG. 21 shows an example of an optical image 100 reproduced by the hologram structure 11 having the characteristics shown in FIG. In the following description and drawings, the reproduced image by the 0th-order refracted light is also referred to as "0th-order diffracted light image 100a", the reproduced image by the 1st-order diffracted light is also referred to as "1st-order diffracted light image 100b", and the reproduced image by the -1st-order diffracted light is referred to. It is also referred to as "-1st-order refracted light image 100c", and the code "100" is used when these light images 100a, 100b, and 100c are collectively represented.

For example, when the number of steps on the uneven surface 1a of the hologram structure 11 is 8 and the depth per step is 200 nm (maximum depth 1400 nm (see the sign “D” in FIG. 6)), FIG. 20 shows. As described above, the wavelength indicating the maximum diffraction efficiency of the 0th-order diffracted light is set to 600 nm, the wavelength indicating the maximum diffraction efficiency of the 1st-order diffracted light is set to 533 nm, and the wavelength indicating the maximum diffraction efficiency of the -1st-order diffracted light is set to 685 nm. can do. As shown in FIG. 21, the light image 100 reproduced from the reproduced light of white light by the hologram structure 11 is a green 1 arranged point-symmetrically with respect to a yellow-orange 0th-order diffracted light image 100a. The next diffracted light image 100b and the red -1st order diffracted light image 100c are included. Further, the first-order diffracted light image 100b and the first-order diffracted light image 100c have the same shape (“F” shape in the illustrated example). The 0th-order diffracted light image 100a has a color depending on the non-diffraction wavelength and the diffraction efficiency.

Further, when the number of steps on the uneven surface 1a of the hologram structure 11 is set to 4 and the depth per step is 190 nm (maximum depth 570 nm (see the sign “D” in FIG. 7)), as shown in FIG. In addition, the wavelength indicating the maximum diffraction efficiency of the 0th-order diffracted light is set to 570 nm, the wavelength indicating the maximum diffraction efficiency of the 1st-order diffracted light is set to 456 nm, and the wavelength indicating the maximum diffraction efficiency of the 1st-order diffracted light is set to 760 nm. be able to. As shown in FIG. 23, the light image 100 reproduced from the reproduced light of white light by the hologram structure 11 is a blue first-order diffracted light image having the same shape arranged point-symmetrically with respect to the 0th-order diffracted light image 100a. Includes 100b and a red -1st order diffracted light image 100c.

Further, when the number of steps on the uneven surface 1a of the hologram structure 11 is set to 4 and the depth per step is 280 nm (maximum depth 840 nm), as shown in FIG. 24, the maximum diffraction efficiency of the 0th-order diffracted light is increased. The indicated wavelength can be set to 420 nm, the wavelength indicating the maximum diffraction efficiency of the primary diffracted light can be set to 672 nm, and the wavelength indicating the maximum diffraction efficiency of the -1st order diffracted light can be set to 480 nm. As shown in FIG. 25, the light image 100 reproduced from the reproduced light of white light by the hologram structure 11 is a red first-order diffracted light having the same shape arranged at point-symmetrical positions about the 0th-order diffracted light image 100a. Includes image 100b and blue -1st order diffracted light image 100c. By setting the wavelength indicating the maximum diffraction efficiency of the 0th-order diffracted light to a wavelength outside the visible light wavelength band, it is possible to prevent the 0th-order diffracted light image 100a from being visually recognized.

Further, when the number of steps on the uneven surface 1a of the hologram structure 11 is set to 4 and the depth per step is 400 nm (maximum depth 1200 nm), as shown in FIG. 26, the maximum diffraction efficiency of the 0th-order diffracted light is increased. The indicated wavelength can be set to 600 nm, the wavelength indicating the maximum diffraction efficiency of the primary diffracted light can be set to 533 nm, and the wavelength indicating the maximum diffraction efficiency of the first-order diffracted light can be set to 436 nm. In this example, the wavelength showing the second highest diffraction efficiency of the -1st order diffracted light is set within the visible light wavelength band (specifically, 685 nm), and the diffraction efficiency also shows a high value of 0.6 or more. Therefore, the color of the -1st order diffracted light image 100c is a mixture of a color corresponding to a wavelength of 436 nm and its vicinity (that is, blue) and a color corresponding to a wavelength of 685 nm and its vicinity (that is, red) (that is, purple). It becomes. Therefore, as shown in FIG. 27, the light image 100 reproduced from the reproduced light of the white light by the hologram structure 11 is a green 1 having the same shape arranged at point-symmetrical positions with respect to the 0th-order diffracted light image 100a. The next diffracted light image 100b and the purple -1st order diffracted light image 100c are included.

The optical image 100 shown in FIGS. 20 to 27 described above is merely an example of the optical image 100 reproducible by the hologram structure 11 of the present embodiment, and by adjusting the diffraction characteristics of the hologram structure 11. It is also possible to reproduce the optical image 100 in another color. The diffraction characteristics of the hologram structure 11 can be adjusted by any method. For example, the number of steps of the uneven surface 1a, the depth of the unevenness, and the refractive index of the hologram structure 11 (particularly the hologram layer 1) can be appropriately selected to be 0. The wavelength distribution of the second-order diffracted light, the first-order diffracted light and the first-order diffracted light can be adjusted.

As described above, according to the hologram structure 11 of the present embodiment, even when white light is used as the reproduction light, the optical image 100 having a specific wavelength (that is, a specific color) is reproduced by the first-order diffracted light and the first-order diffracted light. can do. In particular, by making the wavelength showing the maximum diffraction efficiency of the first-order diffracted light and the wavelength showing the maximum diffraction efficiency of the -1st-order diffracted light included in the wavelength bands of different color systems, the 0th-order diffracted light image 100a is centered. The first-order diffracted light image 100b and the first-order diffracted light image 100c of different colors can be reproduced at the point-symmetrical positions. Similarly to the hologram structure 11 of the first embodiment described above, the hologram structure 11 of the present embodiment also reproduces the light image 100 in a specific color other than the rainbow color, so that the high-definition light image 100 is displayed. It can be reproduced and a specific impression based on a specific color can be given to the observer 50. Further, the wavelength showing the maximum diffraction efficiency of the first-order diffracted light and the wavelength showing the maximum diffraction efficiency of the first-order diffracted light may be set to wavelengths included in the same color system. In this case, the first-order diffracted light image 100b and the first-order diffracted light image 100c of the same color system can be reproduced at point-symmetrical positions centered on the 0th-order diffracted light image 100a.

[Modification 2-1]
28A and 28B are diagrams showing an example of an optical image 100b generated by the primary diffracted light reproduced by the hologram structure 11 according to the modified example 2-1. Note that FIG. 28A shows an optical image 100a due to the 0th-order refracted light and an optical image 100b due to the first-order diffracted light reproduced by the first element element 21a described later, and FIG. 28B is reproduced by the second element element 21b described later. The light image 100a by the 0th-order refracted light and the light image 100b by the 1st-order diffracted light are shown. FIG. 29 is a diagram schematically showing a planar structure of the hologram structure 11 according to the modified example 2-1 and an optical image 100 reproduced by the hologram structure 11.

The hologram structure 11 according to this modification includes a first region 28 and a second region 29, and the first region 28 includes a plurality of first-type element elements 21 (hereinafter, “first element element 21a””. (Also referred to as) is arranged, and a plurality of second type element elements 21 (hereinafter, also referred to as “second element element 21b”) are arranged in the second region 29. In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first element element 21a is the same as the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second element element 21b. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first element element 21a is the same as the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second element element 21b. Further, the primary diffracted light image 100b reproduced by the first element element 21a has the same shape as the -1st refracted light image 100c reproduced by the second element element 21b, and is reproduced by the first element element 21a. The -1st-order diffracted light image 100c to be formed has the same shape as the first-order diffracted light image 100b reproduced by the second element element 21b. The relative position of the light image reproduced by the first-order diffracted light of the first element element 21a and the light image reproduced by the -1st-order diffracted light is the light reproduced by the first-order diffracted light of the second element element 21b. It is opposite to the relative position of the image and the light image reproduced by the -1st order diffracted light.

In the case of the hologram structure 11 shown in FIGS. 28A, 28B and 29, the first element element 21a reproduces the first-order diffracted light image 100b on one side (right side of the drawing) of the 0th-order diffracted light image 100a and the other side (the other side (right side of the drawing)). The -1st order diffracted light image 100c is reproduced on the left side of the drawing). On the other hand, the second element element 21b reproduces the -1st-order diffracted light image 100c on one side (right side of the drawing) of the 0th-order diffracted light image 100a and reproduces the 1st-order diffracted light image 100b on the other side (left side of the drawing). As described above, the relationship of the relative positions of the first-order diffracted light image 100b and the -1st-order diffracted light image 100c with respect to the 0th-order diffracted light image 100a is reversed between the first element element 21a and the second element element 21b. There is. The diffraction angle of the first element element 21a is set to be the same as the diffraction angle of the second element element 21b. On the other hand, the wavelength distribution of the first-order diffracted light and the -1st-order diffracted light of the first element element 21a is the same as the wavelength distribution of the first-order diffracted light and the -1st-order diffracted light of the second element element 21b. Therefore, as shown in FIG. 29, the primary diffracted light image 100b reproduced by the first element element 21a has the same color as the primary diffracted light image 100b reproduced by the second element element 21b (green in FIG. 29). The -1st-order diffracted light image 100c reproduced by the first element element 21a has the same color (red in FIG. 29) as the -1st-order diffracted light image 100c reproduced by the second element element 21b.

By arranging the first region 28 and the second region 29 having the above-described configuration side by side, a diffraction element (that is, a diffraction element that reproduces the inverted color optical image 100 at a point-symmetrical position centered on the 0th-order diffracted optical image 100a (that is,). The first element element 21a and the second element element 21b) are adjacent to each other. Therefore, by switching the region illuminated by the white light between the first region 28 and the second region 29, the light images reproduced on both sides of the 0th-order diffracted light image 100a have the same shape. You can switch colors while keeping it almost.

The hologram structure 11 described above uses two original images having the same shape and color as each other and arranged point-symmetrically, and the first element element 21a and the second element element 21a in the first region 28. It can be realized by making the second element element 21b of the region 29 of. Further, the number of steps of the uneven surface 1a of the first element element 21a and the depth per step can be the same as the number of steps of the uneven surface 1a of the second element element 21b and the depth per step. Further, the position where the light image 100 is reproduced by the first element element 21a in the first region 28 and the position where the light image 100 is reproduced by the second element element 21b in the second region 29 are at least partially. They may overlap or be different from each other.

[Modification 2-2]
FIG. 30 is a conceptual diagram showing an example of the planar structure of the transmissive hologram structure 11 according to the modified example 2-2. FIG. 31A is a schematic view for explaining an example of the light image 100 reproduced by the transmissive hologram structure 11 of FIG. 30, and shows the light image 100 reproduced by the first element element 21a. FIG. 31B shows an optical image 100 reproduced by the second element element 21b of the hologram structure 11 of FIG. FIG. 31C shows an optical image 100 reproduced by overlapping the optical image shown in FIG. 31A and the optical image shown in FIG. 31B.

The element elements 21 constituting the hologram structure 11 of this modification include a plurality of first type element elements (that is, the first element element 21a) and a plurality of second type element elements (that is, the second element element 21b). ) And. The first element element 21a and the second element element 21b are mixed in the same region, and in the illustrated example, the first element element 21a and the second element element 21b are arranged in a checkered pattern. In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first element element 21a is the same as the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second element element 21b. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first element element 21a is the same as the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second element element 21b. Further, the light image 100b-1 of the first-order diffracted light and the light image 100c-1 of the -1st-order diffracted light reproduced by the first element element 21a have the same shape, and the light image 100a-1 of the 0th-order diffracted light. Has a point-symmetrical relationship centered on. Similarly, the light image 100b-2 of the first-order diffracted light and the light image 100c-2 of the -1st-order diffracted light reproduced by the second element element 21b have the same shape, and the light image 100a- of the 0th-order diffracted light. It has a point-symmetrical relationship centered on 2.

Further, the optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a has the same shape as the optical image 100c-2 of the primary diffracted light reproduced by the second element element 21b. The optical image 100c-1 of the primary diffracted light reproduced by the first element element 21a has the same shape as the optical image 100b-2 of the primary diffracted light reproduced by the second element element 21b. The optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a overlaps with the optical image 100c-2 of the primary diffracted light reproduced by the second element element 21b, and the first element element 21a The optical image 100c-1 of the first-order diffracted light reproduced by the above overlaps with the light image 100b-2 of the first-order diffracted light reproduced by the second element element 21b. The optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a has substantially the same size as the optical image 100c-2 of the primary diffracted light reproduced by the second element element 21b. Moreover, it is preferable that most of them overlap (for example, in 50% or more of each of the light image 100b-1 of the first-order diffracted light and the light image 100c-2 of the first-order diffracted light). Similarly, the optical image 100c-1 of the primary diffracted light reproduced by the first element element 21a has approximately the same size as the optical image 100b-2 of the primary diffracted light reproduced by the second element element 21b. However, it is preferable that most of them overlap (for example, in 50% or more of each of the optical image 100c-1 of the -1st-order diffracted light and the light image 100b-2 of the 1st-order diffracted light).

As shown in FIG. 31C, the optical image 100 finally reproduced by the hologram structure 11 of the present modification having the above configuration is the optical image reproduced by the first element element 21a (see FIG. 31A). It becomes a composite image in which the optical image (FIG. 31B) reproduced by the second element element 21b overlaps. That is, an optical image having the same shape and the same color is reproduced at a point-symmetrical position centered on the 0th-order diffracted optical image 100a. According to the hologram structure 11 of this modification, it is possible to easily reproduce an optical image of the same color at a point-symmetrical position centered on the 0th-order diffracted optical image 100a.

The hologram holder 10 may include a plurality of hologram structures 11 of the present modification, and the wavelengths of the primary diffracted light of the first element element 21a and the second element element 21b included in each hologram structure 11. The distribution and the wavelength distribution of the -1st order diffracted light may be changed between the hologram structures 11. In this case, each hologram structure 11 can reproduce a plurality of types of light images 100 (for example, light images 100 having different colors from each other).

In the above example, the wavelength distribution of the diffraction efficiency of the primary diffracted light and the -1st diffracted light is the same between the first element element 21a and the second element element 21b, but these wavelength distributions are the first element. It may be different between the element 21a and the second element element 21b. That is, in the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first element element 21a is different from the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second element element 21b. Also, the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first element element 21a may be different from the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second element element 21b. In this case, as in the above example, the optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a is the optical image 100c− of the -1st diffracted light reproduced by the second element element 21b. The optical image 100c-1 of the -1st-order diffracted light reproduced by the first element element 21a may have the same shape as that of 2, and may be overlapped with the first-order diffracted light reproduced by the second element element 21b. It may have the same shape as the optical image 100b-2 and may overlap. In particular, the optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a has substantially the same size as the optical image 100c-2 of the primary diffracted light reproduced by the second element element 21b. Moreover, it is preferable that most of them overlap (for example, in 50% or more of each of the light image 100b-1 of the first-order diffracted light and the light image 100c-2 of the first-order diffracted light). Similarly, the optical image 100c-1 of the primary diffracted light reproduced by the first element element 21a has approximately the same size as the optical image 100b-2 of the primary diffracted light reproduced by the second element element 21b. However, it is preferable that the light overlaps with most of the light (for example, 50% or more of each of the light image 100c-1 of the first-order diffracted light and the light image 100b-2 of the first-order diffracted light).

In this case, the optical images 100a-1, 100b-1, 100c-1 reproduced by the first element element 21a as shown in FIG. 32A and the second element element 21b reproduced by the second element element 21b as shown in FIG. 32B. The optical images 100a-2, 100b-2, and 100c-2 overlap each other, and the optical image 100 as shown in FIG. 32C is reproduced. That is, light images having the same shape and different colors can be reproduced at point-symmetrical positions centered on the 0th-order diffracted light image 100a.

For example, in the reflective hologram structure 11 according to the present modification described above, the number of steps on the uneven surface 1a of the first element element 21a is set to 8 and the depth per step is set to 200 nm (maximum depth 1400 nm). On the other hand, the number of steps on the uneven surface 1a of the second element element 21b can be increased to four, and the depth per step can be set to 190 nm (maximum depth of 570 nm). In this case, while reproducing the primary diffracted light image 100b-1 of the first element element 21a in green and the -1st diffracted light image 100c-1 in red, the primary diffracted light image 100b of the second element element 21b is reproduced. -2 is reproduced in blue and the -1st-order diffracted light image 100c-2 is reproduced in red. Then, these light images are combined, and finally, a magenta light image and a yellow light image are reproduced at point-symmetrical positions centered on the 0th-order diffracted light image 100a. In the examples shown in FIGS. 32A to 32C, the -1st-order diffracted light image 100c-1 reproduced by the first element element 21a and the -1st-order diffracted light image 100c-2 reproduced by the second element element 21b are It has similar colors (ie, red), but may have different colors.

As another form, in the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first element element 21a is the diffraction efficiency of the -1st diffracted light for the second element element 21b. It may be different from the wavelength distribution, and the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first element element 21a is different from the wavelength distribution of the diffraction efficiency of the first diffracted light for the second element element 21b. You may. In this case, the optical image of the primary diffracted light reproduced by the first element element 21a has the same shape as the optical image of the primary diffracted light reproduced by the second element element 21b, and is the first element element. The optical image of the -1st-order diffracted light reproduced by the 21a has the same shape as the optical image of the -1st-order diffracted light reproduced by the second element element 21b, and is reproduced by the first element element 21a1 The optical image of the secondary diffracted light overlaps with the optical image of the primary diffracted light reproduced by the second element element 21b, and the optical image of the -1st diffracted light reproduced by the first element element 21a is the second element element. It may overlap with the optical image of the -1st order diffracted light reproduced by 21b. In particular, the optical image 100b-1 of the primary diffracted light reproduced by the first element element 21a has substantially the same size as the optical image 100b-2 of the primary diffracted light reproduced by the second element element 21b. It is preferable that most of them overlap (for example, in 50% or more of each of the light image 100b-1 of the first-order diffracted light and the light image 100b-2 of the first-order diffracted light). Similarly, the optical image 100c-1 of the -1st-order diffracted light reproduced by the first element element 21a has approximately the same size as the optical image 100c-2 of the -1st-order diffracted light reproduced by the second element element 21b. It is preferable to have and to overlap with most of them (for example, in 50% or more of each of the -1st-order diffracted light image 100c-1 and the -1st-order diffracted light image 100c-2).

In this case, the optical images 100a-1, 100b-1, 100c-1 reproduced by the first element element 21a as shown in FIG. 32A and the second code shown in parentheses in FIG. 32B. The optical images 100a-2, 100b-2, and 100c-2 reproduced by the element element 21b overlap each other, and the optical image 100 as shown in FIG. 32C is reproduced. That is, light images having the same shape and different colors can be reproduced at point-symmetrical positions centered on the 0th-order diffracted light image 100a.

In the hologram structure 11 of this modification, the arrangement mode of the first element element 21a and the second element element 21b is not limited to the checkered pattern described above. For example, the first element element 21a and the second element element 21b may be arranged depending on the arrangement mode in which the striped arrangement, the checkered pattern arrangement, and the striped arrangement are combined.

[Modification 2-3]
Similar to the hologram structure 11 described above, the hologram structure 11 of this modification includes a plurality of element elements 21 configured as Fourier transform holograms that reproduce an optical image by modulating the phase of the incident reproduced light. Be prepared. Each element element 21 has a concavo-convex surface 1a containing three or more different heights, and is a first-order diffracted light containing light in the first wavelength band (that is, a wavelength showing the above-mentioned maximum wavelength). ) Reproduces the first optical image, and includes light in a second wavelength band different from the first wavelength band (that is, light in a second wavelength different from the first wavelength (wavelength showing the above-mentioned maximum wavelength efficiency) -1. The second light image, which is point-symmetrical to the first light image, is reproduced by the next diffracted light). In particular, one of the first light image and the second light image is reproduced in red.

That is, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for each element element 21 is the diffraction efficiency of the other. A maximum value is formed in the wavelength band of 680 nm or more and 780 nm or less in the wavelength distribution of. Further, by changing the incident angle of the reproduced light on each element element 21, the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for each element element 21 are 380 nm or more and 780 nm. The maximum diffraction efficiency in the following wavelength bands can be maximized in a wavelength band smaller than 680 nm in the wavelength distribution of the other diffraction efficiency.

FIG. 33 shows the wavelength distributions of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to an example of the reflective hologram structure 11 according to the modified example 2-3. It is a graph which shows, in particular, the case where the incident angle of the regenerated light is 0 °. FIG. 34 shows an example of an optical image 100 reproduced by the hologram structure 11 having the characteristics shown in FIG. 33 when the incident angle of the reproduced light is 0 °. FIG. 35 is a graph showing the wavelength distributions of the 0th-order diffracted light (W0), the 1st-order diffracted light (W1), and the -1st-order diffracted light (W-1) according to the hologram structure 11 of FIG. The case where the incident angle of light is 30 ° is shown. FIG. 36 shows an example of an optical image 100 reproduced by the hologram structure 11 having the characteristics shown in FIG. 35 when the incident angle of the reproduced light is 30 °. In FIGS. 33 and 35, the horizontal axis indicates the wavelength and the vertical axis indicates the diffraction efficiency.

For example, when the number of steps on the uneven surface 1a of each element element 21 of the reflective hologram structure 11 is 8 and the depth per step is 207 nm (maximum depth 1449 nm), the hologram structure 11 is shown in FIG. The hologram structure 11 having the diffraction characteristics shown in 33 and 35 can be realized. That is, when the incident angle of the reproduced light with respect to the hologram structure 11 is 0 °, the 0th-order diffracted light has a peak wavelength at 621 nm, the 1st-order diffracted light has a peak wavelength at 552 nm, and the -1st-order diffracted light peaks at 709 nm. Can have wavelength. On the other hand, when the incident angle of the reproduced light with respect to the hologram structure 11 is 30 °, the 0th-order diffracted light has a peak wavelength near 540 nm, the 1st-order diffracted light has a peak wavelength at 473 nm, and the -1st-order diffracted light has a peak wavelength of 624 nm. It can have a peak wavelength.

As is clear from FIGS. 33 and 35, in general, the peak wavelength of each diffracted light shifts to the short wavelength side as the incident angle of the reproduced light with respect to the hologram structure 11 increases from 0 °. On the other hand, the width of the wavelength band of each color system in the visible light wavelength band is not uniform among the color systems, and in particular, the wavelength band corresponding to the red system is wider than the wavelength band corresponding to the other color systems. Therefore, an optical image produced by diffracted light having a peak wavelength in a red wavelength band tends to remain red in color and hardly change even if the incident angle of the reproduced light changes. On the other hand, in the optical image by diffracted light having a peak wavelength in the wavelength band of other color systems other than red, the color of the reproduced image tends to change to the color on the short wavelength side when the incident angle of the reproduced light changes. be.

Therefore, the diffraction characteristics of the hologram structure 11 (particularly the maximum diffraction efficiency described above) are adjusted so that the light image of the primary diffracted light (that is, the first light image) and the light image of the -1st diffracted light (that is, the second light image) can be adjusted. By reproducing at least one of them mainly by red light (particularly light corresponding to a wavelength of 680 nm or more and 780 nm or less), the at least one optical image can be reproduced in red even if the incident angle of the reproduced light changes. ..

In particular, one of the reproduced image by the primary diffracted light and the regenerated image by the -1st diffracted light is set to red (particularly the color corresponding to the wavelength of 680 nm or more and 780 nm or less), and the other is set to a color other than red. May be good. For example, in the hologram structure 11 having the diffraction characteristics shown in FIGS. 33 and 35, when the incident angle of the reproduced light is 0 °, the -1st order diffracted light image 100c has a red color as shown in FIGS. 33 and 34. Moreover, the primary diffracted light image 100b has a green color, but when the incident angle of the reproduced light is 30 °, the -1st diffracted light image 100c maintains a red color as shown in FIGS. 35 and 36, but the primary diffracted light image 100b. Becomes blue.

As described above, according to the hologram structure 11 of the present modification, at least one of the light image by the first-order diffracted light and the light image by the -1st-order diffracted light is reproduced in red even if the incident angle of the reproduced light is changed. Is possible. Such a hologram structure 11 can be used for design purposes, but is particularly suitable for security applications such as authenticity determination. The observer 50 observes the first-order diffracted light image 100b and the first-order diffracted light image 100c while changing the incident angle of the white light with respect to the hologram structure 11, and one or both of the first-order diffracted light image 100b and the first-order diffracted light image 100c. It is possible to easily and surely determine the authenticity of the hologram holder 10 depending on whether or not the hologram holder 10 maintains the red state.

In the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of one of the above-mentioned diffraction efficiencies, it is preferable that there is no maximum value having a diffraction efficiency of 380 nm or more and 780 nm or less. That is, the maximum value of the second largest diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of one of the above-mentioned diffraction efficiencies is preferably less than half of the maximum diffraction efficiency. In this case, it is possible to effectively prevent color bleeding and thickening at the periphery of the line and reproduce a high-definition optical image.

[Third Embodiment]
In the present embodiment, the same or similar elements as those of the first embodiment, the second embodiment and the modifications thereof described above are designated by the same reference numerals, and detailed description thereof will be omitted. Further, among the above-mentioned explanatory items relating to the first embodiment, the second embodiment and their modified examples, detailed description of the matters similarly applicable to the hologram structure 11 of the present embodiment is omitted. do.

The hologram holder 10 and the hologram structure 11 according to the present embodiment have the same configuration as that of the first embodiment described above, and the hologram structure 11 is shown in FIGS. 1, 2, and 5 to 7. It has such an element element 21 and an uneven surface 1a, and may be either a reflective type (see FIG. 3) or a transmissive type (see FIG. 4).

The hologram structure 11 of the present embodiment can provide a highly visible reproduced image by substantially reducing the influence of the 0th-order diffracted light on the reproduced optical image as compared with the conventional light modulation element.

FIG. 37 is a graph showing the relationship between the wavelength of light (horizontal axis) and the luminous efficiency (vertical axis). Luminous efficiency represents the intensity of brightness that the human eye perceives, and the intensity of brightness that the human eye perceives at the wavelength that maximizes sensitivity is set to "1", and the degree to which the brightness of other wavelengths is perceived is defined as "1". It is a dimensionless number expressed by a relative ratio of 1 or less.

The brightness of the reproduced image actually observed by the human eye is equivalent to the product of the wavelength intensity distribution of the reproduced light incident on the hologram structure 11 and the diffraction efficiency, which is further multiplied by the luminous efficiency. do. Therefore, by setting the peak wavelength of the 0th-order diffracted light to a wavelength band (specifically, 421 nm or less or 697 nm or more) showing a relative luminous efficiency of 0.005 or less, the 0th-order diffracted light can be compared with the conventional light modulation element. It can be made significantly less noticeable visually.

Therefore, in the hologram structure 11 of the present embodiment, the maximum diffraction efficiency of the 0th-order diffracted light for each element element 21 can be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. In this case, since the light image reproduced by the 0th-order diffracted light can be made inconspicuous, the visibility of the light image reproduced by other diffracted light can be improved. Further, in the hologram structure 11, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th order diffracted light for each element element 21 can be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. You may. In the hologram structure 11 of the present embodiment, each element element 21 has an uneven surface 1a, and each element element 21 is similar to the hologram structure 11 of the first embodiment and the second embodiment described above. The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light is the wavelength distribution of the diffraction efficiency including the maximum diffraction efficiency. , A maximum value having a half-value full width of 200 nm or less is formed.

The maximum diffraction efficiency of the 0th-order diffracted light for each element element 21 is preferably a maximum value having a full width at half maximum of 200 nm or less. In this case, most of the 0th-order diffracted light (that is, the 0th-order diffracted light in the wavelength band in which the diffraction efficiency of half or more of the peak diffraction efficiency is secured) is included in the wavelength of 421 nm or less or 697 nm or more, which is difficult to see. Therefore, the light image reproduced by the 0th-order diffracted light can be made noticeably inconspicuous. Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for each element element 21 may form a maximum value having a full width at half maximum of 200 nm or less.

Further, at least one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for each element element 21 has a maximum value of the diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less. Is preferable. In this case, the optical image is reproduced by at least one of the first-order diffracted light and the first-order diffracted light in the wavelength band having high luminous efficiency, and the sharpness of the light image can be improved.

In particular, the maximum diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for each element element 21 is the wavelength distribution of the diffraction efficiency of the first-order diffracted light for each element element 21. It is preferably less than 25% of the maximum value contained in at least one of the wavelength distributions of the diffraction efficiency of the first-order diffracted light, which is 456 nm or more and 663 nm or less. In this case, in the wavelength band having high luminous efficiency, the diffraction efficiency of at least one of the first-order diffracted light and the first-order diffracted light can be sufficiently increased as compared with the diffraction efficiency of the 0th-order diffracted light. Thereby, the visibility of the light image reproduced by at least one of the first-order diffracted light and the first-order diffracted light can be improved more effectively.

The hologram structure 11 of the present embodiment described below includes a plurality of element elements 21 configured as Fourier transform holograms that reproduce an optical image by modulating the phase of the reproduced light, and each element element 21 has 3 elements. It has an uneven surface 1a containing different heights of more than one step. Then, as described above, the maximum diffraction efficiency of the 0th-order diffracted light for each element element 21 can be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for each element element 21 may be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more.

FIG. 38 is a diagram showing an example of the relationship between the wavelength (horizontal axis) and the diffraction efficiency (vertical axis) of the general hologram structure 11. FIG. 39 is a diagram showing an example of an optical image 100 reproduced by the hologram structure 11 having the diffraction characteristics of FIG. 38. FIG. 40 is a diagram showing an example of the relationship between the wavelength (horizontal axis) and the diffraction efficiency (vertical axis) of the hologram structure 11 according to the third embodiment. FIG. 41 is a diagram showing an example of an optical image 100 reproduced by the hologram structure 11 having the diffraction characteristics of FIG. 40. In FIGS. 38 and 40, the wavelength distribution of the 0th-order diffracted light is indicated by "W0", the wavelength distribution of the 1st-order diffracted light is indicated by "W1", and the wavelength distribution of the -1st-order diffracted light is indicated by "W-1". It is shown.

The hologram structure 11 having the diffraction characteristic of FIG. 38 is a reflection type and has the same configuration as that of FIG. 5 described above, and the concave-convex surface 1a of each element element 21 has a four-stage concave-convex structure and 1 It is formed on the hologram layer 1 having a step contact depth of 180 nm and a refractive index of 1.5. In this case, as shown in FIG. 38, in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light, the diffraction efficiency has a peak in the visible light wavelength band (specifically, around 540 nm). Therefore, as shown in FIG. 39, the light image 100a reproduced by the 0th-order diffracted light appears visibly in green between the 1st-order diffracted light image 100b and the -1st-order diffracted light image 100c.

On the other hand, the hologram structure 11 having the diffraction characteristic of FIG. 40 is a reflection type and has the same configuration as that of FIG. 5 described above, and the concave-convex surface 1a of each element element 21 has a four-stage concave-convex structure. The depth per step is set to 277.5 nm, and the hologram layer 1 has a refractive index of 1.5. In this case, as shown in FIG. 40, the maximum diffraction efficiency of the 0th-order diffracted light for each element element 21 (see the sign “H0” in FIG. 40) is obtained at a wavelength of 421 nm or less. Further, the maximum diffraction efficiency of the 0th-order diffracted light for each element element 21 forms a maximum value having a full width at half maximum of 200 nm or less. Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for each element element 21 may be obtained at a wavelength of 421 nm or less, and 0 for each element element 21. The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the next diffracted light may form a maximum value having a half-value full width of 200 nm or less. Further, the maximum value of the diffraction efficiency is set in the wavelength band in which at least one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffracted efficiency of the -1st diffracted light for each element element 21 is 456 nm or more and 663 nm or less (FIG. 40). (See "H1" and "H-1"). Further, the maximum diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for each element element 21 is the wavelength distribution of the diffraction efficiency of the first-order diffracted light for each element element 21 and -1. It is less than 25% of the maximum value (see the signs “H1” and “H-1” in FIG. 40) included in at least one of the wavelength distributions of the diffraction efficiency of the next diffracted light in the wavelength band of 456 nm or more and 663 nm or less.

According to the hologram structure 11 having the diffraction characteristics shown in FIG. 40 described above, as shown in FIG. 41, the optical image due to the 0th-order diffracted light is visually recognized between the primary diffracted light image 100b and the -1st-order diffracted light image 100c. Does not appear as possible.

As described above, according to the hologram structure 11 of the present embodiment, the optical image reproduced by the 0th-order diffracted light is not visually recognized or appears inconspicuously even if it can be visually recognized, so that the original image is not devised. The optical image 100 generated by the primary diffracted light and the -1st diffracted light can be reproduced with good visibility. Therefore, for example, even when reproducing an optical image having no bright part in the center (that is, the original image), the optical image is clearly visible and clear by other diffracted light so that the optical image reproduced by the 0th-order diffracted light is not bothered. Can be played.

The hologram structure 11 of the present embodiment can reproduce an optical image having better visibility than a conventional light modulation element in which a reproduced image by 0th-order diffracted light is conspicuous. Therefore, the hologram structure 11 is suitable for design applications and for security purposes such as authenticity determination. Also suitable for. In particular, by adjusting the diffraction characteristics of the hologram structure 11 and making the peak wavelength of the 0th-order diffracted light different from the peak wavelength of the ± 1st-order diffracted light in the visible light wavelength band (for example, the wavelength band of 380 nm or more and 780 nm or less), the 0th order A filter that cuts the peak wavelength of the folded light can be used in combination with the hologram structure 11. As an example, in the wavelength band of 380 nm or more and 780 nm or less, the wavelength band showing the diffraction efficiency of more than half of the maximum diffraction efficiency in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light is the largest in the wavelength distribution of the diffraction efficiency of the ± 1st-order diffracted light. It is possible to use a filter that cuts the peak wavelength of such 0th-order diffracted light when it does not overlap with a wavelength band exhibiting a diffraction efficiency of half or more of the diffraction efficiency. When such a filter is used, it is possible to more reliably prevent the optical image from being reproduced by the 0th-order diffracted light. Therefore, for example, when determining the suitability of the reproduced image of the hologram structure 11 using a device in a security application, it is possible to make a highly accurate determination and improve the reliability of authentication.

[Depth of uneven surface]
The hologram structure 11 of the present embodiment can be manufactured by the same method as the manufacturing method of the hologram structure 11 of the first embodiment described above, for making the optical image due to the 0th-order diffracted light inconspicuous. An uneven surface 1a having a unique uneven depth can be formed on the hologram layer 1.

For example, the reflective hologram structure 11 having the diffraction characteristics of the present embodiment has the same configuration as that of FIG. 5 described above, and the concave-convex surface 1a of each element element 21 has a four-stage concave-convex structure. It can be formed when the depth per step is set to 277.5 nm and the refractive index of the hologram layer 1 is 1.5. In this case, the optical path length per stage of the uneven surface 1a is 832.5 nm, the blue light image is reproduced by the -1st-order refracted light, the red light image is reproduced by the 1st-order diffracted light, and the red light image is reproduced by the 0th-order diffracted light. The light image is reproduced very dark and hardly noticeable.

As another example, in the reflective hologram structure 11, the refractive index of the hologram layer 1 is 1.5, and the concave-convex surface 1a of each element element 21 has an 8-step concave-convex structure, and each step has a concave-convex structure. When the depth is set to 277.5 nm, the -1st-order diffracted light reproduces the blue light image, the 1st-order diffracted light reproduces the red light image, and the 0th-order diffracted light reproduces the light image very dark. It is reproduced and hardly noticeable. Further, in the transmissive hologram structure 11, the refractive index of the hologram layer 1 is 1.5, the uneven surface 1a of each element element 21 has a four-step uneven structure, and the depth per step is 1665 nm. When set and used in an air environment with a refractive index of 1.0, the -1st order diffracted light reproduces the blue light image, the 1st order diffracted light reproduces the red light image, and the 0th order diffracted light reproduces it. The light image is reproduced very dark and hardly noticeable.

On the other hand, in the reflective hologram structure 11, the refractive index of the hologram layer 1 is 1.5, the uneven surface 1a of each element element 21 has a four-step uneven structure, and the depth per step is 180 nm. When set to, the red light image is reproduced by the -1st-order diffracted light, the blue light image is reproduced by the 1st-order diffracted light, and the light image reproduced by the 0th-order diffracted light is reproduced in bright green and stands out (Fig. 39).

[Relationship between the depth of the uneven surface and the peak wavelength of the reproduced image]
When the optical path length modulated per stage of the uneven surface 1a is represented by l and the natural number is represented by m, the peak wavelength λ0 of the 0th-order diffracted light reproduced by the hologram structure 11 is represented by the following equation. It does not depend on the number of steps N of the uneven surface 1a.

λ0 = l / m

As described above, one of the features of the hologram structure 11 of the present embodiment is that the optical image reproduced by the 0th-order diffracted light is visually inconspicuous. This can be realized when the peak wavelength λ0 of the 0th-order diffracted light does not exist in the wavelength band (that is, 421 nm to 697 nm) having a relative luminous efficiency of 0.005 or more. For example, in the reflection type hologram structure 11, when the optical path length l is 832.5 nm, the peak wavelength λ0 of the 0th-order diffracted light can be set to 832.5 / m. In this case, λ0 = 832.5 nm for m = 1, λ0 = 416.25 nm for m = 2, and λ0 = 277.5 nm for m = 3. When m = 4 or later, λ0 becomes a smaller value. Since the peak wavelength λ0 of these 0th-order diffracted lights is not included in the wavelength band having a relative luminous efficiency of 0.005 or more (wavelength band larger than 421 nm and smaller than 697 nm), the optical path length l is set to 832.5 nm. Therefore, the optical image 100 in which the 0th-order diffracted light is inconspicuous can be observed.

[Modification 3-1]
The hologram structure 11 may include a plurality of regions, and the region in which the plurality of element elements 21 according to the present embodiment described above are arranged and the region in which the plurality of element elements 21 having other diffraction characteristics are arranged. And may be arranged side by side with each other.

FIG. 42A is a schematic view for explaining the light image 100 reproduced by an example of the reflective hologram structure 11 according to the modified example 3-1. The light image 100 reproduced through the first region 25. Is shown. FIG. 42B shows the light image 100 reproduced through the second region 26 of the hologram structure 11 of FIG. 42A.

The hologram structure 11 of FIGS. 42A and 42B includes a first region 25 and a second region 26. A plurality of first-type element elements 21 are arranged in the first region 25, and a plurality of second-type element elements 21 are arranged in the second region 26. Further, the optical image of the primary diffracted light and the optical image of the -1st diffracted light reproduced by the element element 21 of the first type are the optical image of the primary diffracted light and the -1st diffracted light reproduced by the element element 21 of the second type. It has a shape related to the light image of. The light images having a shape relationship as used herein include, for example, a pair of light images having the same or substantially the same shape visually, and the sizes of these light images may be the same as each other. It may be different. Further, the optical images having a shape relationship include, for example, a pair of optical images that form a pattern, a character, or the like having a specific intention by combining the optical images with each other. Then, the maximum diffraction efficiency of the 0th-order diffracted light for the first type element element 21 can be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. On the other hand, the maximum diffraction efficiency of the 0th-order diffracted light for the second type element element 21 is obtained at a wavelength larger than 421 nm and smaller than 697 nm. Further, the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for the first type element element 21 may be obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. Even if the maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for the second type element element 21 is obtained at a wavelength larger than 421 nm and smaller than 697 nm. good.

Further, when white light is incident on the first type element element 21 and the second type element element 21, the primary diffracted light image 100b of the first type element element 21 and the -1 next time of the second type element element 21. The folded light image 100c has a similar color (for example, red), and the -1st order diffracted light image 100c of the first type element element 21 and the primary diffracted light image 100b of the second type element element 21 have a similar color (for example, blue). Have.

When white light is incident on the first region 25 described above, as shown in FIG. 42A, the first-order diffracted light image 100b and the first-order diffracted light image 100c by the first-type element element 21 are visually reproduced. However, the optical image of the 0th-order diffracted light is reproduced so as not to be visually recognized or conspicuous. On the other hand, when white light is incident on the second region 26 in which the above-mentioned second type element element 21 is arranged, as shown in FIG. 42B, it is 0 together with the primary diffracted light image 100b and the -1st diffracted light image 100c. The next diffracted light image 100a is visually reproduced.

Then, in the hologram structure 11 shown in FIGS. 42A and 42B, the first region 25 and the second region 26 are provided adjacent to each other. The observer 50 continuously observes the optical image 100 reproduced through the first region 25 and the optical image 100 reproduced through the second region 26 while moving the hologram structure 11. By repeating the above, it is possible to recognize the change in the presence / absence of the 0th-order diffracted light image 100a while recognizing the same shape and color of the 1st-order diffracted light image 100b and the -1st-order diffracted light image 100c. Such a hologram structure 11 can be used for design purposes, but is particularly suitable for security applications such as authenticity determination. The observer 50 can easily and surely determine the authenticity of the hologram holder 10 according to the presence or absence of a change in the 0th-order diffracted light image 100a using white light.

[Use]
The usage mode and use of the hologram structure 11 (light modulation element) and the hologram holder 10 described above are not particularly limited, and can be used for entertainment and design purposes such as reproducing a character image. Further, in security applications, for example, the hologram structure 11 (light modulation element) can be applied to the following objects. When the hologram holder 10 is used as an information recording medium, various information such as passports, ID cards, banknotes, credit cards, cash vouchers, gift certificates, other tickets, official documents, personal information and confidential information are recorded. The optical modulation element and the information recording medium according to the present invention can be applied to other media, other media having monetary value, and the like, and their counterfeiting can be prevented. The ID card referred to here includes, for example, a national ID card, a license, a membership card, an employee ID card, a student ID card, and the like. In the hologram holder 10, the base material that holds the hologram structure 11 (see the symbol “4” in FIG. 2) can be composed of, for example, paper, resin, metal, synthetic fiber, or a combination thereof. When an opening (see the symbol “4a” in FIG. 2) is formed in the base material, the entire area of the opening may be covered with the hologram structure 11, or only a part of the opening may be covered with the hologram structure. Body 11 may be placed. The hologram structure 11 may be configured as a transparent member in appearance. For example, a point light source is arranged on the back surface side of the hologram holder 10 that holds the transmissive hologram structure 11, and the observer observes the point light source through the hologram structure 11 from the front surface side of the hologram holder 10. The observer can visually recognize the security information recorded in the hologram structure 11. This security information can be used, for example, for determining the authenticity of the hologram holder 10.

Further, the light modulation element according to the present invention can be applied to the above-mentioned hologram holder 10 by any method. For example, unevenness formation, transfer, sticking, and sandwiching on the surface of the hologram holder 10 can be applied. Alternatively, the light modulation element according to the present invention can be held by an arbitrary object (that is, the hologram holder 10) by using a technique such as embedding. Therefore, the hologram structure 11 may be formed by using a part of the members constituting the hologram holder 10, or the hologram structure 11 may be additionally provided to the hologram holder 10.

Further, the above-mentioned hologram structure 11 may be used alone for various purposes, or may be used together with other functional layers such as a printing layer and used for various purposes.

[Constituent material of hologram layer]
The material constituting the hologram layer 1 is not particularly limited, but as described above, the hologram layer 1 can be composed of various resins. Specific examples of various resins are listed below.

Examples of the thermosetting resin constituting the hologram layer 1 include unsaturated polyester resin, acrylic-modified urethane resin, epoxy-modified acrylic resin, epoxy-modified unsaturated polyester resin, alkyd resin, and phenol resin. Examples of the thermoplastic resin constituting the hologram layer 1 include polycarbonate (PC), polyethylene terephthalate (PET), glycol-modified polyethylene terephthalate (PET-G), polyvinyl chloride (PVC), acrylic acid ester resin, and acrylamide. Examples thereof include resins, nitrocellulose resins, and polystyrene resins. These resins may be homopolymers or copolymers composed of two or more kinds of constituent components. Further, these resins may be used alone or in combination of two or more.

The thermosetting resin or thermoplastic resin described above includes various isocyanate compounds, metal soaps such as cobalt naphthenate and zinc naphthenate, organic peroxides such as benzoyl peroxide and methyl ethyl ketone peroxide, benzophenone, acetophenone, anthraquinone and naphthoquinone. It may contain a thermosetting agent such as azobisisobutyronitrile or diphenylsulfide.

Examples of the ionizing radiation curable resin constituting the hologram layer 1 include epoxy-modified acrylate resin, urethane-modified acrylate resin, and acrylic-modified polyester resin. Among them, urethane-modified acrylate resin is preferable, and Japanese Patent Application Laid-Open No. 2007-017643 is particularly preferable. A urethane-modified acrylic resin represented by the chemical formula shown in the publication is preferable.

When the ionizing radiation curable resin is cured, a monofunctional or polyfunctional monomer, oligomer or the like can be used in combination for the purpose of adjusting the crosslinked structure and viscosity. Examples of the monofunctional monomer include mono (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, hydroxyethyl (meth) acrylate, vinylpyrrolidone, (meth) acryloyloxyethyl succinate, and (meth) acryloyloxyethyl phthalate. And so on. The bifunctional or higher functional monomers are classified by skeletal structure and are classified into polyol (meth) acrylate (for example, epoxy-modified polyol (meth) acrylate, lactone-modified polyol (meth) acrylate, etc.), polyester (meth) acrylate, and epoxy (meth). ) Acrylate, urethane (meth) acrylate, other polybutadiene-based, isocyanuric acid-based, hydantin-based, melamine-based, phosphoric acid-based, imide-based, phosphazene-based poly (meth) acrylate and the like. In addition, various monomers, oligomers and polymers that are UV and electron beam curable are available.

More specifically, examples of the bifunctional monomer and oligomer include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 1,6-hexanediol di (meth). Examples include acrylate. Examples of the trifunctional monomer, oligomer, and polymer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and aliphatic tri (meth) acrylate. Examples of the tetrafunctional monomer and oligomer include pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and aliphatic tetra (meth) acrylate. Examples of the pentafunctional or higher functional monomers and oligomers include dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate. Moreover, (meth) acrylate having a polyester skeleton, urethane skeleton, phosphazene skeleton and the like can be mentioned. The number of functional groups is not particularly limited, but if the number of functional groups is smaller than 3, the heat resistance tends to decrease, and if it exceeds 20, the flexibility tends to decrease, so that the number of functional groups is particularly high. Those in the range of 3 to 20 are preferable.

The content of the monofunctional or polyfunctional monomer or oligomer as described above can be adjusted as appropriate, but it is usually preferably 50 parts by weight or less with respect to 100 parts by weight of the ionizing radiation curable resin, and 0.5 weight by weight in particular. It is preferably in the range of parts to 20 parts by weight.

Further, the hologram layer 1 is provided with a photopolymerization initiator, a polymerization inhibitor, a deterioration inhibitor, a plasticizer, a lubricant, a colorant such as a dye or a pigment, a surfactant, a defoaming agent, a leveling agent, and a leveling agent, if necessary. Additives such as a thixotropic property-imparting agent may be added as appropriate.

When the hologram layer 1 has self-supporting property, the film thickness of the hologram layer 1 is preferably in the range of 0.05 mm to 5 mm, and more preferably in the range of 0.1 mm to 3 mm. On the other hand, when the hologram layer 1 is formed on a transparent substrate without having self-supporting property, the film thickness of the hologram layer 1 is preferably in the range of 0.1 μm to 50 μm, particularly in the range of 2 μm to 20 μm. Is preferable. Further, the size of the hologram layer 1 (for example, the size in a plan view) can be appropriately set according to the use of the hologram structure 11.

[Other variants]
The hologram structure 11 used in each of the above-described embodiments and modifications is composed of a plurality of element elements 21 as shown in FIG. 5, but the hologram structure 11 is composed of a single element element 21. You may be.

Further, the plan view size and the plan view shape of each element element 21 are not particularly limited, and each element element 21 may have an arbitrary size and shape. For example, the plan view shape of each element element 21 can be a quadrangle such as a square, a rectangle, a trapezoid, another polygonal shape (for example, a triangle, a pentagon, a hexagon, etc.), a perfect circle, an ellipse, another circular shape, a star shape, or a star shape. It may have a heart shape or the like, and the hologram structure 11 may have two or more types of element elements 21 having a plan view shape.

Further, an arbitrary functional layer may be added to the hologram structure 11, and the hologram structure 11 may be covered with, for example, a transparent thin-film deposition layer. In particular, by providing a transparent vapor-deposited layer having no gloss, it is possible to prevent the hologram structure 11 from having gloss and conceal the hologram structure 11. From the viewpoint of hiding the hologram structure 11, the total light transmittance of such a transparent vapor-deposited layer is preferably 80% or more, and more preferably 90% or more. Further, in the reflective hologram structure 11, the hologram structure 11 can be covered with a reflective vapor-deposited layer (see the reflective layer 2 in FIG. 2). As constituent materials of the reflective vapor deposition layer, for example, Mg, Al, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Se, Rb, Pd, Ag, Cd, In, Sn, Sb, Te, Examples include metals such as Au, Pb, and Bi. Further, examples of the constituent material of the transparent thin-film deposition layer include oxides and sulfides of the above metals such as _{ZnS and TiO 2.} These materials may be used alone to form a thin-film deposition layer, or two or more materials may be combined to form a thin-film deposition layer.

The thickness of the thin-film deposition layer provided on the hologram layer 1 (particularly on the uneven surface 1a) can be appropriately set from the viewpoint of desired reflectivity, color tone, design, application, etc., and may be in the range of, for example, 50 Å to 1 μm. It is preferable, and above all, it is preferably in the range of 100 Å to 1000 Å. In particular, when the transparency of the thin-film deposition layer is prioritized, the thickness of the vapor-deposited layer is preferably 200 Å or less, while when the concealment of the thin-film deposition layer is prioritized, the thickness of the thin-film deposition layer exceeds 200 Å. Is preferable. Further, as a method for forming the thin-film deposition layer, a general method for forming the thin-film deposition layer can be adopted, and examples thereof include a vacuum deposition method, a sputtering method, and an ion plating method.

The present invention is not limited to the above-described embodiments and modifications. For example, various modifications may be added to each element of the above-described embodiment and modification. In addition, embodiments that include components and / or methods other than the components and / or methods described above may also be included in the embodiments of the present invention. In addition, an embodiment of the present invention may include a form in which some of the above-mentioned components and / or methods are not included. In addition, a form including some components and / or methods included in one embodiment of the present invention and some components and / or methods included in other embodiments of the present invention is also included in the present invention. It may be included in the embodiment. Therefore, the components and / or methods included in each of the above-described embodiments and modifications and the embodiments of the present invention other than the above may be combined, and the embodiments related to such combinations are also the embodiments of the present invention. Can be included in the form. Further, the effect produced by the present invention is not limited to the above-mentioned effect, and a peculiar effect according to the specific configuration of each embodiment can be exhibited. In this way, various additions, changes and partial deletions can be made to each element described in the claims, the specification, the abstract and the drawings without departing from the technical idea and purpose of the present invention. Is.

1 Hologram layer 1a Concavo-convex surface 2 Reflective layer 4 Base material 10 Hologram holder 11 Hologram structure 21 Element element 21a First element element 21b Second element element 21c Third element element 25 First region 26 Second Region 28 First region 29 Second region 50 Observers 51, 51a, 51b Light source 100 Optical image 100a 0th-order diffracted light image 100b 1st-order diffracted light image 100c-1st-order diffracted light image

Claims (20)

It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed .
At least two or more types of the element elements are provided,
The at least two or more types of element elements are light modulation elements in which the wavelengths showing the maximum diffraction efficiency are different from each other. The uneven surface of the element element includes three or more different heights.
In the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light, another maximum value having a diffraction efficiency of half or more of the maximum diffraction efficiency is set. The optical modulation element according to claim 1, which does not exist. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
Includes first and second regions
In the first region, the element element including the element element of the first type is arranged.
In the second region, the element element including the second type element element is arranged.
The wavelength showing the maximum diffraction efficiency of the first type element element is different from the wavelength showing the maximum diffraction efficiency of the second type element element.
The light image reproduced by the element element arranged in the first region is a light modulation element having a shape relationship with the optical image reproduced by the element element arranged in the second region. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
The maximum diffraction efficiency is included in one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the other of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light is the wavelength distribution of the other diffraction efficiency. An optical modulation element that forms a maximum value having a half-value full width of 200 nm or less. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
The light modulation element, wherein the maximum diffraction efficiency is included in both the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light. The wavelength showing the maximum diffraction efficiency in one of the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light, the wavelength distribution of the diffraction efficiency of the primary diffracted light, and the-. The optical modulation element according to claim 4 , wherein the difference between the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength showing the maximum diffraction efficiency in the other is 100 nm or less. The maximum diffraction in the wavelength band of 380 nm or more and 780 nm or less in one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light. There is no other maximum value that makes the diffraction efficiency more than half of the efficiency, and the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light are 380 nm or more and 780 nm or less. The optical modulation according to any one of claims 4 to 6 , wherein there is no other maximum value having a diffraction efficiency of half or more of the maximum diffraction efficiency in the wavelength distribution of the other diffraction efficiency. element. Includes first and second regions
In the first region, the element element of the first type is arranged.
In the second region, the element element of the second type is arranged.
In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element is the same as the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second type element element. Yes, the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first type element element is the same as the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second type element element.
The optical image of the primary diffracted light reproduced by the first type element element has the same shape as the optical image of the -1st refracted light reproduced by the second type element element, and is of the first type. The optical image of the first-order diffracted light reproduced by the element element has the same shape as the optical image of the first-order diffracted light reproduced by the second type element element.
The relative position between the light image reproduced by the primary diffracted light of the first type element element and the light image reproduced by the -1st diffracted light is the light reproduced by the primary diffracted light of the second type element element. The light modulation element according to any one of claims 4 to 7 , which is opposite to the relative position of the image and the light image reproduced by the -1st order diffracted light. A plurality of the element elements are provided, and include a first type element element and a second type element element.
In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element is the same as the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second type element element. Yes, the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first type element element is the same as the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second type element element.
The optical image of the primary diffracted light reproduced by the first type element element has the same shape as the optical image of the -1st refracted light reproduced by the second type element element, and is of the first type. The optical image of the first-order diffracted light reproduced by the element element has the same shape as the optical image of the first-order diffracted light reproduced by the second type element element.
The light image of the primary diffracted light reproduced by the first type element element overlaps with the optical image of the -1st refracted light reproduced by the second type element element, and is reproduced by the first type element element. The light modulation element according to any one of claims 4 to 7 , wherein the light image of the first-order diffracted light overlaps with the light image of the first-order diffracted light reproduced by the element element of the second type. A plurality of the element elements are provided, and include a first type element element and a second type element element.
In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element is different from the wavelength distribution of the diffraction efficiency of the primary diffracted light for the second type element element. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first type element element is different from the wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the second type element element.
The optical image of the primary diffracted light reproduced by the first type element element has the same shape as the optical image of the -1st refracted light reproduced by the second type element element, and is of the first type. The optical image of the first-order diffracted light reproduced by the element element has the same shape as the optical image of the first-order diffracted light reproduced by the second type element element.
The light image of the primary diffracted light reproduced by the first type element element overlaps with the optical image of the -1st refracted light reproduced by the second type element element, and is reproduced by the first type element element. The light modulation element according to any one of claims 4 to 7 , wherein the light image of the first-order diffracted light overlaps with the light image of the first-order diffracted light reproduced by the element element of the second type. A plurality of the element elements are provided, and include a first type element element and a second type element element.
In the wavelength band of 380 nm or more and 780 nm or less, the wavelength distribution of the diffraction efficiency of the primary diffracted light for the first type element element is different from the wavelength distribution of the diffraction efficiency of the first-order diffracted light for the second type element element. The wavelength distribution of the diffraction efficiency of the -1st order diffracted light for the first type element element is different from the wavelength distribution of the diffraction efficiency of the first diffracted light for the second type element element.
The optical image of the primary diffracted light reproduced by the first type element element has the same shape as the optical image of the primary diffracted light reproduced by the second type element element, and the element of the first type. The optical image of the -1st-order diffracted light reproduced by the element has the same shape as the optical image of the -1st-order diffracted light reproduced by the second type element element.
The light image of the primary diffracted light reproduced by the first type element element overlaps with the light image of the primary diffracted light reproduced by the second type element element, and is reproduced by the first type element element. The light modulation element according to any one of claims 4 to 7 , wherein the light image of the -1st-order diffracted light overlaps with the light image of the -1st-order diffracted light reproduced by the element element of the second type. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
A light modulation element in which the maximum diffraction efficiency of 0th-order diffracted light for the element element is obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more. The light modulation element according to claim 12 , wherein the maximum diffraction efficiency of the 0th-order diffracted light with respect to the element element forms a maximum value having a full width at half maximum of 200 nm or less. The element element has a maximum value of diffraction efficiency in a wavelength band in which at least one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light is 456 nm or more and 663 nm or less. The optical modulation element according to any one of claims 1 to 13. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
The element element has a maximum value of diffraction efficiency in a wavelength band in which at least one of the wavelength distribution of the diffraction efficiency of the first-order diffracted light and the wavelength distribution of the diffraction efficiency of the first-order diffracted light is 456 nm or more and 663 nm or less. ,
The maximum diffraction efficiency in the wavelength band of 456 nm or more and 663 nm or less in the wavelength distribution of the diffraction efficiency of the 0th-order diffracted light for the element element is the wavelength distribution of the diffraction efficiency of the first-order diffracted light for the element element and the -1 next time. An optical modulation element that is less than 25% of the maximum value included in at least one of the wavelength distributions of the diffraction efficiency of folding light in the wavelength band of 456 nm or more and 663 nm or less. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
Includes first and second regions
In the first region, the element element of the first type is arranged.
In the second region, the element element of the second type is arranged.
The optical image of the primary diffracted light and the -1st diffracted light reproduced by the first type element element are the optical image of the primary diffracted light and the -1st diffracted light reproduced by the second type element element. It has a shape related to the optical image and has a shape related to it.
The maximum diffraction efficiency of the 0th-order diffracted light for the first type element element is obtained at a wavelength of 421 nm or less or a wavelength of 697 nm or more, and the maximum diffraction efficiency of the 0th-order diffracted light for the second type element element is 421 nm. A light modulation element obtained at a wavelength larger than 697 nm and smaller than 697 nm. It is equipped with an element element that reproduces an optical image by modulating the phase of the incident reproduced light.
The element element has an uneven surface and has an uneven surface.
The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the primary diffracted light and the wavelength distribution of the diffraction efficiency of the -1st diffracted light for the element element is the diffraction efficiency including the maximum diffraction efficiency. In the wavelength distribution, a maximum value having a half-value full width of 200 nm or less is formed.
The element element is a light modulation element which is a Fourier transform hologram. It is provided with an element element that reproduces an optical image by modulating the phase of the incident reproduced light, and the element element has an uneven surface, and the wavelength distribution of the diffraction efficiency of the primary diffracted light for the element element and -1. The maximum diffraction efficiency in the wavelength band of 380 nm or more and 780 nm or less in the wavelength distribution of the diffraction efficiency of the next diffracted light forms a maximum value having a half-value full width of 200 nm or less in the wavelength distribution of the diffraction efficiency including the maximum diffraction efficiency. An information recording medium including a modulation element. The information recording medium according to claim 18 , wherein the optical image represents information based on at least one of characters, symbols, and patterns. Further provided with a substrate having a predetermined size opening,
The information recording medium according to claim 18 or 19 , wherein at least a part of the light modulation element is arranged at a position corresponding to the opening.

Images