Information recording medium and method of reading information from information recording medium, and image detection apparatus

A system for authenticating hidden information comprising:

• an information recording medium on which the hidden information is recorded, the information recording medium being formed of a paper base material and including a first layer and a transparent second layer stacked on the first layer and including a light reflection layer, the second layer having an uneven surface, wherein a plurality of minuscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information, and a plurality of miniscule diffraction grating elements each having a diffraction grating holding dummy information irrelevant to the hidden information, are arranged on the surface of the second layer, a grating pitch and a grating angle are set in such a manner that the whole or part of light rays diffracted by the diffraction grating elements based on the illumination light from a light source enter a predetermined spatial area, and in the case where the whole or part of the diffraction light rays from a diffraction grating element group including a combination of at least two diffraction grating elements among the plurality of miniscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information enter the predetermined area, and a sum of reproduction information in the predetermined area is developed as predetermined one or plurality of hidden information, and a predetermined color and a predetermined pattern are arranged on the first layer in accordance with arrangement of the diffraction grating elements holding the hidden information;
• and
• an authentication apparatus, the authentication apparatus including:
• a light source which radiates illumination light rays of a color in the same color group as or complementary to a predetermined color of a pattern arranged on a first layer corresponding to diffraction grating elements holding the hidden information and on the first layer corresponding to diffraction grating elements around the diffraction grating elements holding the hidden information;
• reading means for reading the hidden information developed by a combination of the light rays diffracted, through the diffraction grating elements, from the illumination light rays radiated on the diffraction grating elements from the light source;
• and
• authentication means for authenticating the hidden information based on the information read by the reading means.

A system for authenticating hidden information comprising:

• an information recording medium on which the hidden information is recorded, the information recording medium being formed of a paper base material and including a first layer and a transparent second layer stacked on the first layer and including a light reflection layer, the second layer having an uneven surface, wherein a plurality of minuscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information, and a plurality of miniscule diffraction grating elements each having a diffraction grating holding dummy information irrelevant to the hidden information, are arranged on the surface of the second layer, a grating pitch and a grating angle are set in such a manner that the whole or part of light rays diffracted by the diffraction grating elements based on the illumination light from a light source enter a predetermined spatial area, and in the case where the whole or part of the diffraction light rays from a diffraction grating element group including a combination of at least two diffraction grating elements among the plurality of miniscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information enter the predetermined area, and a sum of reproduction information in the predetermined area is developed as predetermined one or plurality of hidden information, and a predetermined color and a predetermined pattern are arranged on the first layer in accordance with arrangement of the diffraction grating elements holding the hidden information, wherein a pattern having a color corresponding to a wavelength of light radiated at the time of reading the hidden information is arranged on the first layer corresponding to the diffraction grating elements around the diffraction grating elements holding the hidden information;
• and
• an authentication apparatus, the authentication apparatus including:
• a light source which radiates illumination light rays of a color in the same color group as or complementary to a predetermined color of a pattern arranged on a first layer corresponding to diffraction grating elements holding the hidden information and on the first layer corresponding to diffraction grating elements around the diffraction grating elements holding the hidden information;
• reading means for reading the hidden information developed by a combination of the light rays diffracted, through the diffraction grating elements, from the illumination light rays radiated on the diffraction grating elements from the light source;
• and
• authentication means for authenticating the hidden information based on the information read by the reading means.

A system for authenticating hidden information comprising:

• an information recording medium on which the hidden information is recorded, the information recording medium being formed of a paper base material and including a first layer and a transparent second layer stacked on the first layer and including a light reflection layer, the second layer having an uneven surface, wherein a plurality of minuscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information, and a plurality of miniscule diffraction grating elements each having a diffraction grating holding dummy information irrelevant to the hidden information, are arranged on the surface of the second layer, a grating pitch and a grating angle are set in such a manner that the whole or part of light rays diffracted by the diffraction grating elements based on the illumination light from a light source enter a predetermined spatial area, and in the case where the whole or part of the diffraction light rays from a diffraction grating element group including a combination of at least two diffraction grating elements among the plurality of miniscule diffraction grating elements each having a diffraction grating holding the whole or part of hidden information enter the predetermined area, and a sum of reproduction information in the predetermined area is developed as predetermined one or plurality of hidden information, and a predetermined color and a predetermined pattern are arranged on the first layer in accordance with arrangement of the diffraction grating elements holding the hidden information, wherein a pattern having a color complimentary to the color corresponding to a wavelength of light radiated at the time of reading the hidden information is arranged on the first layer corresponding to the diffraction grating elements around the diffraction grating elements holding the hidden information;
• and
• an authentication apparatus, the authentication apparatus including:
• a light source which radiates illumination light rays of a color in the same color group as or complementary to a predetermined color of a pattern arranged on a first layer corresponding to diffraction grating elements holding the hidden information and on the first layer corresponding to diffraction grating elements around the diffraction grating elements holding the hidden information;
• reading means for reading the hidden information developed by a combination of the light rays diffracted, through the diffraction grating elements, from the illumination light rays radiated on the diffraction grating elements from the light source;
• and
• authentication means for authenticating the hidden information based on the information read by the reading means.

An information recording medium, comprising:

• an arrangement of diffraction grating cells constituting cells each formed of a single diffraction grating, wherein
• the information recording medium is formed of a paper base material and has an uneven surface and the diffraction grating cells are arranged on the uneven surface of the information recording medium,
• a plurality of types of the diffraction grating cells make up one information recording area,
• two or more different types of the diffraction grating cells included in the diffraction grating cells making up the information recording area are information recording elements,
• two or more different types of the diffraction grating cells included in the diffraction grating cells making up the information recording area are information hiding elements,
• at least one of the diffraction grating cells included in the diffraction grating cells making up the information recording area is dummy,
• the diffraction grating cells of different types included in the diffraction grating cells making up the information recording area are configured of diffraction gratings having different grating angles from each other and having different grating angles from each of the two or more different types of the diffraction grating cells that are the information hiding elements,
• information is recorded in a two-dimensional arrangement of the diffraction grating cells constituting the information recording elements in the information recording area,
• when the diffraction grating cells are irradiated with an illumination light from a light source, only one diffraction grating light ray is emitted from one diffraction grating cell, and
• the illumination light is a diffused illumination light that irradiates the diffraction grating cell in a plurality of angles and the diffraction light ray diffracts and diverges in a certain degree.