JPS62165751A - Optical multiplex recording method - Google Patents

Abstract

PURPOSE:To attain high density of optical recording by constituting two optional accumulated films of a laminated recording medium so that at least one of the light absorbing wavelength and the light polarization differs from each other and a light at least one of the light wavelength and the light polarization is variable is irradiated. CONSTITUTION:Each layer is an accumulated firm accumulating plural signal molecule films and a laser light 14 whose polarization and wavelength are varied independently is irradiated to a recording medium forming and laminating the accumulated films L1-Ln by the Langmuir project method. That is, in irradiating the laser light 14 where the polarization thetai and wavelength lambdaj are given to a vibration vector P to the accumulated film 13 whose single molecular film is in the state J, only a specific accumulated film is changed to a new state J*15. In varying the polarization thetai or the wavelength lambdaj variously, the information multiplexed in terms of the dimension of the polarization thetai or the wavelength lambdaj is written into a recording point.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an optical multiplex recording method.

[Conventional technology]

The optical recording method has the characteristic that the recording medium does not deteriorate due to wear because the recording medium and the writing or reading head are not in contact with each other, and is now put into practical use, for example, as an image information recording source.

Furthermore, development research is being carried out to use this technology in large-capacity computer memories.

Among these optical recording methods, the heat mode method is particularly being actively researched because it does not require image processing in a dark room.

As an example of the heat mode method, a small hole called a bit is created by melting and removing a part of the recording medium using a laser beam and writing is performed, while reading is performed by detecting bits and bits with light. There is now a bit detection type. However, bit detection type devices such as r. Most of the materials used are as recording media. Therefore, research is being carried out on optical recording methods to increase the sensitivity of recording media, reduce manufacturing costs, and use organic dyes as recording media in place of harmful materials such as Te.

For example, JP-A-60-1242
In Publication No. 91, a recording medium made of a phthalocyanine polymer composition is irradiated with writing light in a Halus shape to change the orientation or association state of phthalocyanine molecules, thereby changing the reflectance or transmittance from the surroundings. Forming record points with different rates.

[Problem that the invention seeks to solve]

However, with this method, it is impossible to record a plurality of pieces of information on one recording point, and the limit of recording density is determined by the phenomenon of light diffraction, and is approximately 1011 bits/1.

This invention attempts to improve these drawbacks.

[Means for solving problems]

In the optical multiplex recording method of the present invention, each layer is a cumulative film in which a plurality of monomolecular films are accumulated, the recording medium is a stack of a plurality of the above-mentioned cumulative films, and there is no difference between any two of the above-mentioned cumulative films. , the absorption wavelength of the light and the degree of polarization of the light are configured to be different from each other, and the recording medium is irradiated with light in which at least one of the wavelength of the light and the degree of polarization of the light is variable to write information. At least one of reading is performed.

Furthermore, for example, at least one of the absorption wavelength of light and the degree of polarization of light may be different between any two of the monomolecular films constituting the cumulative film. At least one of information writing and reading is performed by irradiating light whose polarization degree is independently variable.

[Effect]

Information is written on each cumulative layer of the recording medium using light that has a different wavelength or degree of polarization.
By changing either the wavelength or the degree of polarization of the laser beam used for recording, information can be multiplexed in one recording spot of the laser beam in the wavelength dimension and the degree of polarization dimension, so the information recording density is 106 bits/i. can be exceeded.

〔Example〕

Next, the method of the present invention will be explained in more detail based on the drawings.

As the molecules of the monomolecular film constituting the cumulative film used in this invention, molecules shown in FIG. 3 that have both a hydrophobic group and a hydrophilic group and also contain an organic dye can be used. In Figure 3, (1) is a hydrophobic group, (2) is an organic dye, and (3)
is a hydrophilic group. The shape of the molecule is such that the position of the organic dye (2) within the molecule is (a) adjacent to a hydrophilic group, [F]) within a hydrophobic group, or (C) sandwiching a hydrophobic group. (2) The one on the side opposite to the hydrophilic group is used, and (2) the one present on the side chain of the molecule is used. Furthermore, if the organic dye itself is hydrophilic, it will have the shape (E), On the other hand, if the organic dye itself is extremely hydrophobic, (F')
The shape will be . In creating a monolayer, at least one of fatty acids such as stearic acid, divalent metal salts of fatty acids, and lipids such as lectins are used in combination with the molecules shown in Figure 2 to stabilize the membrane. I can do it.

Here, the Langmuir-Prodgett method is to develop molecules that share a hydrophilic group and a hydrophobic group on the air-water interface of an aqueous solution, and apply pressure from the horizontal direction to form a single molecule at the interface. This is a method of creating a film and then transferring it onto a substrate, and is a method commonly used as a means of stacking monomolecular films.

For example, by using a substrate on which this monomolecular film is formed and rotating the substrate to accumulate monomolecular films having an absorption wavelength different from that of the previously formed monomolecular film, a cumulative film is formed. Using this accumulated film as a substrate, it is rotated and monomolecular films having absorption wavelengths different from those of the previously formed monomolecular films are laminated to form a recording medium.

Note that the recording density is maximized when any two monomolecular films in the recording medium are formed so that at least one of the absorption wavelength of light and the degree of polarization of light is different.

By the way, in this invention, writing is performed on an optical recording medium consisting of a cumulative film in which each layer has a different anisotropy of molecular orientation and/or a different absorption wavelength using light whose degree of polarization can be controlled and/or whose wavelength can be varied. Or read. First, writing information based on the degree of polarization of light can be explained as follows.

In other words, light viewed as a wave has the properties of a transverse wave, vibrating in a plane perpendicular to the direction of travel.

The direction of this vibration is a vector called P. On the other hand, for organic dyes, in the simplest case, the transition moment from $→S is expressed as a vector. That is, the transition moment points in a certain direction determined by the structure of the molecule.

This direction is a vector called A. The probability that this organic dye is excited by the incident light P is given by equation (1).

p (cy) = po C0g2α (1) Formula (
In 1), as shown in FIG. 4, α is the angle formed by the vector P(4) of the vibration direction of the incident light and the vector A(5) of the transition moment of absorption of the organic dye. Formula (1
), when α=01, that is, P and A are parallel, the probability of excitation is the maximum value po, and when α=90, that is, orthogonal, it is 0.

By the way, in the multilayer recording medium of this invention, Langmuir
The Blodgett method creates a monomolecular film of molecules that have both hydrophobic groups and hydrophilic groups in their molecules and also contains an organic dye. It also has anisotropy in the degree of polarization of light absorption, and the vector direction AI of the transition moment of light absorption of the film coincides with the vector direction A of the transition moment of the organic dye in the film. Therefore, as shown in FIG. 1, the cumulative monomolecular films L1 to Ln (n is a natural number, n indicates the degree of orientation (degree of polarization)) on the substrate (6) all have different anisotropy of molecular orientation. When creating a recording medium (7) consisting of a cumulative film of , each cumulative film has a different absorption transition moment vector direction A1 to An
It has (8). In this way, by varying the degree of polarization of light absorbed by each cumulative film, it is possible to write information on the multiplex recording medium of the present invention in the dimension of the degree of polarization of light.

Next, regarding the writing of the wavelength dimension of light, when the cumulative film is created by the Langmuir-Prodgett method,
Since the organic dye is oriented with high density in a monomolecular film, each layer has an absorption wavelength, and the absorption wavelength λh (h is a natural number) of the film coincides with the absorption wavelength λh of the organic dye in the film. Therefore, if a recording medium (9) consisting of cumulative films L1 to Lh of monomolecular films all having different absorption wavelengths is created on a substrate (6) as shown in FIG. 2, each cumulative film will have different absorption wavelengths. It has an absorption wavelength of 1 to λ) IQQ, and as a result, it is possible to write information in the wavelength dimension of light. In this invention, the vector direction A1 of the transition moments of different absorptions is
~An and different absorption wavelengths 1~λh can be used as a multiple recording layer. Here, the cumulative film Li-j (1'
≦i≦n, 1≦j≦h) can be used by accumulating any number of recording layers in any order as a multiple recording layer. FIG. 5 shows an example of multiple recording layers in the present invention.

Substrates for accumulating monomolecular films used in this invention include glass plates, metal-deposited glass plates, metal-deposited plastic plates,
Commonly used materials such as metal plates and semiconductor plates can be used. 1 Here, the cumulative film Li-j is composed of m layers (m
is a natural number), and each cumulative film (here, the cumulative number m of monolayers is arbitrary, but cumulative films L1-1 to
It is preferable that all Ln-h have the same cumulative number m, and +c preferably 3≦m≦30. Also the fifth
In Ln-h shown in the figure, n is the vector direction A1 to An(8) of different transition moments of each cumulative film [corresponding to this, and k is 1≦≦ The angle β formed by the transition moment Ak (b) of n-1 natural number) and the transition moment Ak+1@ of the +1st layer is 0° and βk<
In the range of 180°, preferably 80°: β-≦6
0° or 120°≦β and ≦150°. Similarly, in Ln-h, h corresponds to the wavelengths λ1 to λh of light.

In producing the cumulative film used in the present invention, all methods such as the vertical deposition method and the horizontal deposition method in the monomolecular film deposition method of the Langmuir-Prodgett method can be used. In addition, the cumulative film created by the Langmuir-Prodgett method includes a Y-shaped film in which the monomolecular film is deposited with different polar groups facing the substrate in each layer, and a Y-shaped film in which the monomolecular film is deposited with all the hydrophobic groups facing the substrate. There is a kingdom of X-type films and Z-type films that accumulate with all hydrophilic groups directed toward the substrate.
Either membrane can be used. Preferably, however, it is an X-shaped membrane or a Y-shaped membrane made by a horizontal deposition method.

FIG. 7 shows a method of writing on the cumulative film using laser light, which is light whose polarization degree can be controlled and whose wavelength can be independently varied. A laser beam α→ having a degree of polarization (θi) and a wavelength (λj) of a vibration vector P is applied to the cumulative film of a monomolecular film in a state of −1 to Ln−h−J. When irradiated, only the cumulative film of the monomolecular film in which the value of the angle α between the vibration vector P and the vector direction An of the transition moment of the film is 0° and the absorption wavelength is λj changes to a new J prison state αG. , the absorption spectrum of that layer also changes. Therefore, the presence or absence of a change in the absorption spectrum, that is, the presence or absence of a change in the absorption spectrum, can be determined by varying the degree of polarization by varying θi or ^j using this method, which can be used as a binary code signal of O-1. Information multiplexed in the θi or λj dimensions can be written at a single recording point.In addition, the molecules of each cumulative film are polarized because the orientation of the molecules is efficiently controlled by the Langmuir-Prodgett method. Recording based on the difference in degree θi and wavelength λj can be performed accurately and efficiently.

FIG. 3 shows a method of reading out the cumulative film using laser light as light whose degree of polarization can be controlled. Weak laser beam αe with the same light intensity as when writing
While irradiating, the degree of polarization θi of the laser beam and the vector direction A of the transition moment of each film. The degree of polarization θi of the vibration vector P of the laser beam is changed so that the value of the angle α between the By changing the value of I can put it out.

As the recording medium, compounds containing porphyrin, phthalocyanine, and other organic dyes that cause a hole-burning reaction, and compounds containing spiropyran and other organic dyes that cause a photochromic reaction can be used.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to multiplex record information in at least one dimension of the polarization degree θi of light and the wavelength λj of light, and it is possible to multiplex record information in at least one dimension of the polarization degree θi of light and the wavelength λj of light, and it is possible to multiplex record information in at least one dimension of the polarization degree θi of light and the wavelength λj of light. Recording becomes possible.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a recording medium in which cumulative films L1 to Lo of monomolecular films formed on a substrate each have different anisotropy of molecular orientation, according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a recording medium in which cumulative films L1 to Lh of monomolecular films formed on a substrate have different absorption wavelengths, respectively, and FIG. Figure 4 is a structural diagram of a molecule that has both a hydrophobic group and a hydrophilic group and an organic dye that can be used in the invention.
Explanation of the angle α formed by the vector P of the vibration direction of the incident light and the vector A of the transition moment of absorption of the organic dye, Part 5
FIG. 6 is a diagram illustrating the configuration of an example of a multiple recording layer according to the present invention. FIG. 6 is an explanatory diagram of the angle β formed by the transition moment Ak of the first layer and the transition moment Ak+1 of the +1st layer. FIG. , a block diagram showing a method of writing on the cumulative film using laser light as light whose polarization degree and wavelength can be controlled. FIG. FIG. 9 is a block diagram showing a method of reading out the cumulative film using the polarization degree θi of light.
is 30° and 120°, the wavelength of light is λ1, and the degree of polarization θi of light is 30° and 90', and the wavelength of light is λ2. . (1): Hydrophobic group, (2): Organic dye, (3) Dihydrophilic group, (4): Vector of vibration direction of incident light P 1 (5)
: Vector A of transition moment of absorption of organic dye, (
6): Substrate, (7): Recording medium, (8): Vector direction AH to AH. (9): recording medium, ao: absorption wavelength person 1~λh, (b)
: Transition moment Ak1 (2): Transition moment Ak+
1, (to): the cumulative film in J state, α4: laser light,
(To) = Accumulated film layer in J* state, Ct*: Weak laser light Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (6)

[Claims] (1) Each layer is a cumulative film of multiple monolayers,
The recording medium is formed by laminating a plurality of the above-mentioned cumulative films, and is configured such that at least one of the light absorption wavelength and the light polarization degree is different between any two of the above-mentioned cumulative films, and the above-mentioned recording An optical multiplex recording method in which at least one of information writing and reading is performed by irradiating a medium with light whose wavelength and polarization degree are variable. (2) At least one of the light absorption wavelength and the light polarization degree is different between any two of the monomolecular films constituting the cumulative film, and the light wavelength and light polarization degree are different from each other on the recording medium. 2. The optical multiplex recording method according to claim 1, wherein at least one of information writing and reading is performed by irradiating light whose polarization degree is independently variable. (3) The optical multiplex recording method according to claim 1, wherein the monomolecular film is created by Langmuir-Blodgett method. (4) The molecule constituting the monomolecular film has both a hydrophobic group and a hydrophilic group in the molecule, and a molecule containing an organic dye is used. The optical multiplex recording method described. (5) The optical multiplex recording method according to any one of claims 1 to 3, wherein the irradiated light is a laser beam. (6) The optical multiplex recording method according to claim 3, wherein the organic dye causes a change in light absorption spectrum characteristics before and after absorbing light.