Hologram recording material, hologram recording method, and optical recording medium

1 . A hologram recording material comprising:

a sensitizing dye absorbing light upon hologram exposure to generate an excited state thereof; and

an interference fringes-recording component capable of causing color development reaction or discoloration reaction by an electron or energy transfer from the excited state to record interference fringes providing a refractive index modulation,

wherein at least one of the sensitizing dye one the interference fringes-recording component is one of a polymer and an oligomer.

2 . The hologram recording material according to claim 1 , wherein the interference fringes-recording component comprises: an acid generator; and one of an acid-colorable dye precursor and an acid-discolorable dye, at least one of the acid generator, the acid-colorable dye precursor and the acid-discolorable dye being one of a polymer and an oligomer.

3 . The hologram recording material according to claim 2 , wherein the one of the acid-colorable dye precursor and the acid-discolorable dye is one of a polymer and an oligomer.

4 . The hologram recording material according to claim 1 , wherein the interference fringes-recording component comprises: a base generator; and one of a base-colorable dye precursor and a base-discolorable dye, at least one of the base generator, the base-colorable dye precursor and the base-discolorable dye being one of a polymer is an oligomer.

5 . The hologram recording material according to claim 4 , wherein the one of the base-colorable dye precursor and the base-discolorable dye is one of a polymer and an oligomer.

6 . The hologram recording material as defined according to claim 1 , wherein the interference fringes-recording component comprises a colorable dye precursor being one of a polymer and an oligomer, the colorable dye be represented by formula (1):

( A 1 −PD ) m 1  (1)

wherein A1 and PD are covalently bonded to each other; A1 represents a site capable of disconnecting the covalent bond to PD by an electron or energy transfer with the excited state of the sensitizing dye; PD represents a site capable of causing color development reaction when PD is released upon the disconnection of the covalent bond to A1, with the proviso that the molecules of the formula (1) are connected to each other with covalent bond of at least one of A1 and PD to form a polymer or an oligomer, and m1 represents an integer of 3 to 1,000,000.

7 . The hologram recording material according to claim 1 , wherein the interference fringes-recording component comprises a discolorable dye being one of a polymer and an oligomer, the discolorable dye being represented by formula (2):

( A 2 −DD ) m 2  (2)

wherein A2 and DD are covalently bonded to each other; A2 represents a site capable of disconnecting the covalent bond to DD by an electron or transfer with he excited state of the sensitizing dye; DD represents a site which stays in the form of dye when DD is covalently bonded to A2; DD is discolored when DD is released upon the disconnection of the covalent bond to A2, with the proviso that the molecules of the formula (2) are connected to each other with covalent bond of any of A2 and DD to form a polymer or an oligomer, and m2 represents an integer of 3 to 1,000,000.

8 . The hologram recording material according to claim 1 , further comprising an electron-donating compound capable of donating an electron to a radical cation of the sensitizing dye, from which electron has been transferred to the interference fringes-recording component.

9 . The hologram recording material according to claim 8 , wherein the electron-donating compound is one of a polymer and an oligomer.

10 . The hologram recording material as defined according to claim 8 , comprising one of a polymer and an oligomer, the one of the polymer and the oligomer being are copolymer of at least two of the sensitizing dye the interference fringes-recording component and the electron-donating compound.

11 . A hologram recording method, which comprises recording interference fringes providing a refractive index modulation in a hologram recording material according to claim 1 by at least one of 1) a color development reaction, 2) a color development reaction amplified by a self-sensitization with a coloring material of a latent image, 3) a polymerization reaction sensitized with a coloring material of a latent image, 4) a dye discoloration reaction, and 5) a latent image-sensitized polymerization reaction sensitized by a latent image of a residual of a discolorable dye.

12 . The hologram recording method according to claim 11 , wherein

the recording of the interference fringes is performed by 2) the color development reaction amplified by a self-sensitization with a coloring material of a latent image, and

the recording of the interference fringes comprises:

a first step of generating a coloring material as a latent image by holographic exposure, the coloring material having no absorption in a wavelength of a hologram reproducing light; and

a second step of irradiating the latent image of the coloring material with a light having a wavelength, which is different from that of the holographic exposure and in which the sensitizing dye has a molar absorption coefficient of 5,000 or less, to self-sensitize and self-amplify the coloring material,

wherein each of the first and second stops is dry process.

13 . The hologram recording method according to claim 11 , wherein

the interference fringe-recording component is a component capable of recording the interference fringes by at least one of 1) the color development reaction and 2) the color development reaction amplified by a self-sensitization with a coloring material of a latent image,

the component comprises a dye precursor capable of forming a coloring material, wherein the coloring material has an absorption shifted to a longer wavelength than that of the dye precursor and has no absorption in a wavelength of a hologram reproducing light, and

the interference fringes are recorded by forming the refractive index modulation through a color development of the coloring material as a result of an electron or energy transfer from the excited state of the sensitizing dye or an excited state of the coloring material.

14 . The hologram recording method according to claim 1 , wherein

the recording of the interference fringes is performed by 3) the polymerization reaction sensitized with the coloring material of the latent image, and

the recording of the interference fringes comprises:

a first step of generating a coloring material as a latent image by holographic exposure, the coloring material having no absorption in a wavelength of a hologram reproducing light; and

a second step of irradiating the latent image of the coloring material with a light having a wavelength, which is different from that of the holographic exposure, to cause a polymerization reaction.

wherein each of the first and second steps is dry process.

15 . The hologram recording method according to claim 14 , wherein

the sensitizing dye absorbs light upon the holographic in the first step to generate the excited state thereof, and

the interference fringe-recording component comprises:

a dye precursor capable of forming a coloring material by an electron or energy transfer from the excited state of the sensitizing dye in the first step or from an excited state of the coloring material in the second step, wherein the coloring material has an absorption shifted to a longer wavelength than that in the dye precursor, the coloring material has an absorption in a wavelength in which the sensitizing has a molar absorption coefficient of 5,000 or less, and the coloring material has no absorption in a wavelength of a hologram reproducing light;

a polymerizable compound;

a polymerization initiator capable of initiating a polymerization of the polymerizable compound by an energy or electron transfer from the excited state of the sensitizing dye in the first stop or from an excited state of the coloring material in the second stop; and

a binder.

16 . The hologram recording method according to claim 11 , wherein

the recording of the interference fringes is performed by 4) the dye discoloration reaction,

the interference fringe-recording component comprises at least one of a discolorable dye and a discoloring agent precursor, the discoloring agent precursor comprising at least one of a radical generator, an acid generator, a base generator, a nucleophilic agent generator, an electrophilic agent generator and an triplet oxygen, and

the interference fringes are recorded by forming the refractive index modulation through at least one of: discoloring the discolorable dye as a result of an energy or electron transfer from the excited state of the sensitizing dye directly to the discolorable dye; and discoloring the discolorable dye by a discoloring agent formed by an energy or electron transfer from the excited state of the sensitizing dye to the discoloring agent precursor.

17 . The hologram recording method according to claim 11 wherein

the recording of the interference fringes is performed by 7) the latent image-sensitized polymerization reaction sensitized by a latent image of a residual of a discolorable dye, and

the interference fringe-component records the interference fringes by a method comprising:

a first step in which:

the sensitizing dye represented absorbs light upon holographic exposure to generate the excited state thereof,

a color of a discolorable dye is discolored by at least one of; an energy or electron transfer from the excited state of the sensitizing dye directly to the discolorable dye; and a discoloring agent formed by an energy or electron transfer from the excited state of the sensitizing dye to a discoloring agent precursor, the discoloring agent precursor comprising at least one of a radical generator, an acid generators a base generator, a nucleophilic agent generator, an electrophilic agent generator and an triplet oxygen, and

a residual of the discolorable dye forms a latent image; and

a second step of irradiating the latent image of the residual of the discolorable dye with light having a wavelength, which is different from that the holographic exposure, to cause a polymerization reaction by activating a polymerization initiator as a result of an energy or electron transfer from the residual of the discolorable dye.

18 . The hologram recording method according to claim 17 wherein the interference fringe-recording component comprises:

a discolorable dye capable of discoloring itself in the first step as a result of at least one of: an energy or electron transfer directly from the excited state of the sensitizing dye; and an generation of the discoloring agent by an energy or electron transfer from the excited state of the sensitizing dye to the discoloring agent precursor, the discolorable dye having a molar absorption coefficient of 1,000 or less at a wavelength of a hologram reproducing light;

a polymerizable compound;

a polymerization initiator capable of initiating a polymerization of the polymerizable compound by an electron or energy transfer from the excited state of the residual of the discolorable dye in the second step; and

a binder.

19 . The hologram recording material according to claim 1 , wherein the interference fringes are non-rewritable.

20 . The hologram recording method according to claim 11 , comprising performing a multiplexed recording by subjecting the hologram recording material to holographic exposure ten times or more.

21 . The hologram recording method according to claim 20 , wherein the multiplexed recording is performed under a common exposure amount in each holographic exposure.

22 . An optical recording medium comprising a hologram recording material according to claim 1 .

23 . The optical recording medium according to claim 22 , wherein the hologram recording material is stored in a light-shielding cartridge during a storage period.