JP2004535036A - Multilayer composite liquid crystal optical memory system with information recording and reading means - Google Patents

Abstract

Several embodiments of a new structure of a ROM-, WORM-, or RW-type multi-layer data carrier and general modes of writing, reading, deleting and rewriting data to and from the carrier are disclosed. . As a multi-component structure constituting an electrically controlled thin liquid crystal layer cell having at least one alignment layer made of a photo-anisotropic material functioning as a photosensitive recording layer capable of writing data, Each data holding layer is manufactured. The anisotropic absorbing material may be fluorescent or non-fluorescent. This type of structure electrically controls the ability to absorb and irradiate fluorescent molecules dispersed in the liquid crystal matrix. As a result, in both the pit-by-pit and page-by-page readout modes, the fluorescent crosstalk from the adjacent data holding layer can be partially or completely eliminated, the number of carrier information layers can be increased, and the readout mode can be reduced. To minimize the parasitic aberration distortion.
[Selection diagram] FIG.

Description

【Technical field】
[0001]
Background art
The present invention relates to an optical memory system for recording and reading information on a pit-by-pit or page-by-page basis, and more particularly, to a ROM, WORM, RW-multilayer optical memory system having fluorescent readout information, or a combination thereof.
[0002]
Existing optical memory systems utilize a two-dimensional data carrier having one or two information layers. Most of the conventional technical solutions for recording optical data propose to record the change of the reflected laser irradiation intensity in a local area (pit) of the information layer. These changes include interference effects on CD or DVD read only memory (ROM type) relief optical discs, burning of holes in metal films, decolorization of dyes, widely used CD-write single read multiple (WORM). -Local melting of polycarbonate in the system, phase change rewriting (RW)-Can be the result of changes in reflectivity in the system [Bouhuis G. et al. Et al., "Principles of Optical Disc Systems", Philips Research Laboratories, Eindhoven, Adam Hiller Ltd. , Bristol and Boston].
[0003]
In order to increase the recording density, these carriers have been transferred to shorter wave illumination sources combined with large aperture lenses (high NA objectives) [I. Ichimura et al., SPIE, 3864, 2280], reduced track pitch, and increasing the groove depth of land-groove recording type optical discs [S. Morita et al., SPIE, 3109, 167]. New media and methods for reading information have been developed for high density storage of information [T. Vo-Diny et al., SPIE, 3401, 284] for adjusting the pit depth [S. Spielman et al., SPIE, 3109, 98] and for optical discs having square information pits arranged in a symmetric pattern [Satoh et al., US Pat. No. 5,572,508].
[0004]
U.S. Pat. Nos. 4,634,850 and 4,786,792 (Drexler Technology Corp.) describe a "quadruple storage" of digital optical data to increase data density while minimizing errors. The "density" or "micro chess board" format is used, and the data is read by a CCD photodetector array to four times the amount of digital data that can be optically stored on a motion picture film (or optical memory card). Can be
[0005]
With a three-dimensional (homogeneous) photosensitive medium, such information recording densities exceeding several terabits per cubic centimeter can be achieved. These media exhibit various photophysical and photochemical nonlinear effects in two-photon absorption. Optimal recording and reading performance in these three-dimensional WORM- and RW-information carriers depends on the photosensitive element and, for example, the light-emitting material [D. Parthenopoulos et al., Science, 1989, 245, 843] or when photobleaching materials are utilized, the process of two-photon absorption, both with the product of a photoreaction via an intermediate virtual level, or a photorefractive crystal or polymer and light. If a polymer is used, the process of recording changes in refractive parameters [Y. Kawata et al., Opt. Lett. , 1998, 23, 756] and [R. See Borisov et al., Appl. Phys. , 1998, B67, 1].
[0006]
In principle, this write and read mode allows the local recording of information in pits (similar to the information pits used in conventional reflective CD- or DVD-ROMs) in the information medium with altered information characteristics. Will be able to
[0007]
However, there are difficulties in actually implementing this principle due to the high cost and large size of the femtosecond laser irradiation source required for this type of recording, and the extremely low photosensitivity of the medium. Generally, the reason why the photosensitivity of the medium is extremely low is that the two-photon absorption cross-sectional area parameter of the photosensitive material known by the present inventors at the present time is extremely low.
[0008]
Technically, using a multilayer optical information carrier would be more efficient. However, they are subject to certain limitations, in particular deep within the medium, further problems with the design and properties of the data carrier medium and the data read mode and the device (WORM- and RW-write mode of optical memory data). Occurs.
[0009]
In the reflective mode, each information layer of the multilayer optical information carrier is covered with a partially reflective coating. This reduces the intensity of the read and reflected information beams by passing through the medium to a given information layer and returning to the receiving side.
[0010]
Furthermore, due to their coherent characteristics, both beams passing through suffer from unpredictable refraction and interference distortions in the information layer fragments (pits and grooves).
[0011]
For this reason, multilayer fluorescent light information with fluorescent readout is preferred because there is no partially reflective coating. In this case, refraction and interference distortions are due to the non-coherent features of the fluorescent illumination, longer wavelengths compared to the read laser wavelength, and the transparency and homogeneity of the optical medium to the incident laser and the fluorescent illumination (similar reflection of different layers). Rate), it is much less. Thus, multilayer fluorescent carriers provide several advantages over reflected light memories.
[0012]
U.S. Pat. No. 4,202,491 uses a fluorescent link layer whose data spot emits infrared radiation. JP-A-63-195938 proposes a WORM disk having a fluorescence reading mode in which a data carrier layer is applied to a matte surface of a base layer. Due to the strong light diffusion of the writing and reading radiation, it is absolutely impossible to create a multilayer information structure based on WORM disks. However, it is possible to make a multilayer optical disc using a fluorescent composition. This technique is described in U.S. Patent Nos. 6,027,855 and 5,945,252, and EP-A-0 963 571.
[0013]
U.S. Pat. Nos. 6,009,065 and 6,071,671 (V. Glushko and B. Levich) describe devices for reading information bit by bit from a multilayer fluorescent optical disc.
[0014]
At present, the general requirement for all types of multi-layer fluorescent data carriers (optical disks and cards) is that the data carriers require the maximum possible amount and density of recorded information, the maximum possible reading speed, and the high ratio between "signal and noise". That is what we need to prepare. This requirement can be satisfied when the size of the information pit is minimized and the recording density in each information layer is increased, and when the number of information layers is increased and a readout irradiation source having a shorter wavelength is used. In order to be able to achieve high-speed reading, it is necessary to create the maximum possible capacity of the information fluorescent signal.
[0015]
The actual recording density and the rest of the above parameters of optical data writing are determined not only by the wavelength of the recording illumination source, but also by the actual recording medium used for recording, the input / output mode, and the characteristics of the optical memory device. You.
[0016]
With regard to fluorescent multilayer memories, some additional requirements must be met. That is, the recording radiation must be absorbed only within the boundaries of the microscopic location of the three-dimensional medium, and the writing and / or reading radiation is strong enough to achieve a certain threshold effect. Must. Otherwise, the recording of information bits deep within the recording medium will be achieved by a change in optical properties along the entire route of the recording beam as it passes through the medium.
[0017]
Furthermore, when the fluorescent molecules absorb the one-photon readout radiation, certain differences are observed in the design of the data readout mode in the form of optical disks and cards. Two layers in the multilayer information medium 10 (20) in which the information holding layer 11 (21) is separated by a polymer layer 12 (22) which is transparent to the readout radiation 17 (23) and the fluorescent radiations 24 and 25. Please refer to FIGS. 1 and 2 showing possible read options. Generally, disk systems utilize the bit-by-bit data readout achieved by a sharply focused laser beam 23 (FIG. 2).
[0018]
Spatial filtering in the process of receiving and collecting the fluorescent radiation (24) from the information pits (26) can minimize crosstalk between layers. This crosstalk is caused by the fluorescence excitation (25) of the adjacent information layer that occurs when the readout radiation (23) penetrates. Therefore, when utilizing these data carriers, a sufficiently acceptable low contrast is obtained (background fluorescence intensity I_Fl(Back) difference and their sum K = (I_fl(Pit) -I_fl(Back)) / (I_fl(Pit) + I_fl(Back)) ratio). K = １ ／ to ／ of the recorded signal from each separate information layer.
[0019]
When this occurs, the separate information layers (21) may be completely solidified. The fluorescent material may fill both the small pits (information pits) (26) and the space (27) between them.
[0020]
Due to this phenomenon, a relief master disk whose information-bearing layer (21) has been subsequently coated using known heat-forming techniques (injection-compression-molding techniques) or by means of either spin-coating or roller or dip-coating For example, a 2P process based on a composition capable of photopolymerization from (original disc) can be used.
[0021]
With a multi-layer fluorescent data carrier, such as an optical card, a multi-channel (per page) readout of all pages of information (14) can be used, consisting of thousands of pits (16), This is what a CCD camera does. At this time, the three-dimensional image filtering of the page (14) can be significantly hindered by crosstalk between the layers, which is caused by the fluorescent light (25) emitted by the adjacent layers, so that: It is observed that the contrast actually decreases, so that the image received by the receiver has a lower contrast. For this reason, when using an optical card, it is important to achieve high contrast (K-1.0) in each layer. In order to achieve a high level of contrast, only the information pits (16) have to be filled with fluorescent material, while the information layers (11) are grouped as island-like structures. To manufacture this structure consisting of a data retention layer, very sophisticated techniques have to be used.
[0022]
Furthermore, when the fluorescent information pits in a layer occupy about 50 percent of the total layer area, the information signal emitted by this layer and traveling to the light receiving device, even if the write percentage is as large as that referred to above, The intensity is about 1 / N of the intensity of the total fluorescence flow reaching the receiver from the multilayer carrier in readout mode, where N represents the number of information layers on the carrier.
[0023]
The present invention provides a new structure for fluorescent multi-layer data carriers of the ROM-, WORM or RW type, and several options of types and modes for writing and reading data to / from the carrier. With these options, the ability to absorb and irradiate fluorescent molecules diluted in the liquid crystal matrix can be controlled electrically. This can also completely or partially eliminate fluorescent crosstalk between adjacent data retention layers during reading in both "per pit" or "per page" modes. In doing so, the fluorescence intensity of the information signal can be controlled and the distance between the layers can be reduced, thereby increasing the number of information layers of the carrier and reducing aberrations and distortion in the reading process. In addition, the proposed solution expands the application area of various non-linear and linear photochemical and photophysical mechanisms of single writing or rewriting. Also, the same irradiation source for recording, reading and deleting data on the data carrier can be used.
[0024]
In addition, the present invention includes other designs of multi-layer information carriers that use a photochemically stable anisotropically absorbing non-fluorescent material as the host fluorescent material, while maintaining the absence of host molecules in the liquid crystal matrix. Good.
[0025]
The details and advantages of the invention will emerge more clearly from a reading of the following description, which describes in more detail the principles of writing, reading and rewriting data on information carriers developed by the inventors. Also provided are a number of drawings and descriptions of the present invention.
[0026]
Note that the drawings do not show the actual sizes and proportions of the components to facilitate understanding of the structure and operating principles of the fluorescent multilayer optical data carrier.
[0027]
Hereinafter, the present invention will be described with reference to the drawings supporting the present invention.
[0028]
FIG. 3 is a generalization of the proposed structure consisting of a composite multi-layer (two layers selected for easy understanding of the operating principle) optical data carrier (300) manufactured based on a motorized guest-host liquid crystal system. FIG. 4 is a schematic cross-sectional view of an option.
[0029]
As a key component, the data carrier (300) is equipped with "pads" (substrate) (301) and includes a plurality of data retaining layers (data layers) (302), which are described in [US Pat. , 009,065, 6,071,671, International Publication WO99 / 24527, etc.], a multilayer structure is formed instead of a single layer structure. In general, this multilayer structure is electrically operable and consists of two similar optically transparent electrodes (3030) coated with alignment layers (304 and 305) separated by spacers (306). It is designed as a thin liquid crystal cell (LC), and the space between the alignment layers divided by the spacer (306) contains a photochemically stable and anisotropically absorbing fluorescent material used as a host material (308). And a guest-host liquid crystal (LC) composition (307).
[0030]
Since a photochemically stable substance that is fluorescent in a given spectrum and capable of anisotropic absorption is required, it can be sufficiently dissolved in a liquid crystal composition and has high fluorescence when irradiated with a large number of photons (quantum). Toxic substances were selected. In these materials, the molecules are arranged in tough rod-like or disk-like clusters, whose long-wave absorbing oscillators are either along the long axis (eg, stilbene, etc.) or cross the long axis (eg, Tetracene, pentacene, and other polyacene).
[0031]
In the present invention, aromatic hydrocarbons such as multi-core concentrated aromatic hydrocarbons and derivatives thereof, aromatic hydrocarbon groups containing arylethylene groups and arylacetylene groups and derivatives thereof (1.2-diarylethylene, diarylpolyene, Stilbene functional group substitution, and 1.4-distyrylbenzene substitution, etc.) and polyphenyl hydrocarbons, compositions containing 5- (furan, thiophene, pyrrole, and derivatives thereof), heterocyclic compositions, carbonyl groups ( A composition containing coumarin and carbostenated substances, anthrone and aromatic acid derivatives, oxazole-5-substitution, indigoid and thioindigoid, quinone, etc.), naphthalic acid compounds, and xanthene groups, acridine groups, oxazine groups, azine groups, Perylene group, Rylene group, Biarontoron (vialonthrone) group, cyanine group, phthalocyanine group, a photochemically stable composition comprising a complex compound of a metal having an organic ligand and an organic dye such as a porphyrin group, and select these fluorescent materials.
[0032]
The liquid crystal and the dye were mixed at a molar ratio of 1: 0.01 to 1: 0.8. For liquid crystals, thermotropic or lyotropic smectic or cholesteric liquid crystals or mixtures thereof can be used, but mixtures with nematic liquid crystals or other crystals are more preferred.
[0033]
The photochemically stable anisotropic absorbing material may have a covalent bond with a molecule of a material having liquid crystal properties. It is a liquid crystal substance that can play a role as a fluorescent agent because it is affected by irradiation and can emit fluorescence when absorbed.
[0034]
The data layer (302) is separated by an "intermediate layer" (309), which is optically of high quality and provides write and read illumination that can also retain and delete data (fluorescence). On the other hand, it is permeable. The intermediate layer is several microns to several hundred microns thick. The protective layer (310) protects the optical data storage medium from mechanical damage and the adverse effects of the aggressive medium. To eliminate the parasitic effects of light reflection, scattering and diffraction caused by out-of-focus layers, the refractive parameters for all data, intermediate and protective layers very close to each other for a given wavelength It is important to choose. Also, the same parameters must be selected for the guest-host LC composition (307), which may be homeotropic (or planar depending on its nature and read and / or write mode). . If desired, the data layer of a given wavelength (302) may be assembled as a multilayer with an anti-reflective and interference coating. To assemble this type of layer, several additional layers (not shown in FIG. 3) must be added to the structure.
[0035]
The data layer and the intermediate layer are adhered to one multilayer carrier (300) using an adhesive (311) that solidifies when exposed to light or heat.
[0036]
The controller 312 performs individual electric control. This has the role of using the power supply from the power supply 313 to orient the LC molecules of composition 308, and thus the host fluorescent molecules (308) that are part of this composition. The controller 312 and the power supply (313) are located outside the multilayer carrier (300) because they are located on independently operating data writing and / or reading devices (not shown in FIG. 3).
[0037]
For the optically transparent electrode (303), a transparent electrode layer commonly used for PC liquid crystal (LC) screens was used. These layers are made from metal oxides such as indium tin oxide (ITO), tin oxide. The thickness of these layers is about 0.001-1 mmc. These layers are manufactured as a homogeneous film (303) or as two mutually orthogonal strips (FIG. 4) 41, 42 to write, read or delete data on (or from) the multilayer carrier. In the general mode, power may be saved. In the latter case, each of the liquid crystal cells passes through the spectral region when writing, reading, or deleting data in a given region (page) 43 of one layer of the data layer (302) of the multilayer carrier (300). It functions as a shutter array for controlling the coefficient of the host fluorescence excitation (308). It also controls the fluorescence intensity. Both sides of the intermediate glass or polymer layer (309) are coated with electrodes (303). (For glass or polymer, select Mylar (Dupont), polycarbonate, epoxy resin, photosensitive resin, photopolymer composition, etc.) it can). The intermediate layers are preferably isotropic as long as their optical properties do not change.
[0038]
In order to make the surface of the alignment layer (304) homogeneous, an alignment layer conventionally used in liquid crystal (LC) screen technology may be used. This technique is described in [P. Chatelain, Bull. Soc. Franc. Miner. 66, 105 (1943)]. This method uses a polyimide type polymer film with a thickness of less than 1 micron. The membrane is mechanically rubbed in one direction to coat one of the transparent electrodes (303) (FIG. 3) or one of the electrodes 41 or.
[0039]
However, this technique has little or no applicability when the thickness of the intermediate layer is very thin (less than about 10 mmc) or when the layer uses a fine relief surface (309). In this case, a non-contact method of planar alignment of the liquid crystal layer, for example, a method of obliquely spraying a transparent material [J. L. Janning, Appl. Phys. Lett. 21, 173 (1972)] or the use of Langmuir-Blodgett multilayer molecular membranes [E. Guyon, Vac. Sci. Technol. 10, 681 (1973)].
[0040]
In the present invention, a so-called optically anisotropic material, that is, a technique of aligning liquid crystals using an originally isotropic photosensitive material is used, and these materials are irradiated with polarized light, and polarized light. It exhibits optical anisotropy when absorbing induced light irradiation even if it is not. This technique was discovered in 1990 by one of the inventors of the present invention [V. Kozenkov et al., 11 USSR Optical Liquid Crystal Conference, Kransnoyarsk, 1990, p. 130 (Russian)].
[0041]
Optical anisotropy results from the anisotropy of the oriented molecular distribution both within the depth of the material and on its surface. These may be the remaining initial molecules with anisotropic properties or may be new anisotropic products formed as a result of photochemical reactions. When this occurs, once the activating radiation has successfully reached the optically anisotropic material, the main orientation of the permanent dipoles of the remaining initial molecules will be oriented according to the material plane and orthogonal to the electric field vector of the activating radiation. Will be. As a result of this orientation, a combination of anisotropic molecules located on the surface of the anisotropic material and anisotropic products formed as a result of the photochemical reaction is achieved. This combination can orient the liquid crystal molecules along the material plane and in a certain direction according to the direction of the main orientation of the surface molecules of the photo-anisotropic material.
[0042]
In the present invention, layers made from these materials may be manufactured using centrifugal techniques, solution immersion, or according to the Langmuir-Blodgett method, or by vacuum hot spraying. Non-contact and non-mechanical optical methods for adding alignment properties can produce ultra-thin interlayers (309), or if only one of the layer surfaces is coated with fine relief , A fine relief surface layer can be made.
[0043]
If a thin LC cell is used for the data layer (302), the alignment layer (304) may not be used. In the present invention, the alignment layer (305) provided on the reverse transparent electrode 303 (FIG. 3) or the electrode 42 (or 41) (FIG. 4) plays a role of a recording layer in addition to the role of the alignment. . These layers can be manufactured by mechanical rubbing, oblique spraying of polymer layers, or can be made from Langmuir-Blodgett membranes (for ROM-type data carriers). It is also possible to use the photo-alignment methods referred to above that work well with photo-anisotropic materials (for ROM-, WORM- or RW type data carriers).
[0044]
In the latter case, after the writing is completed, the layer will contain a number of small areas holding data (information marks or pits) 314 similar to the reflective pits of a conventional CD or CD-ROM system. These are located in the background area (315) and have different molecular clusters both in the outer surface (316 and 317) and in the LC layer (307) when compared to the electrically controlled LC composite guest-host layer 307. As a result, they will have different alignment performances.
[0045]
At the same time that the LC molecules are electrically controlled and aligned, the host fluorescent anisotropic molecules (308) diluted in the LC also become more aligned and oriented and begin to absorb readout radiation. When this occurs, the absorption coefficient and the fluorescence intensity of the data holding layer also change depending on the presence or absence of the voltage applied to the electrode 303 or 41 and 42.
[0046]
Such technical solutions in applying photo-isotropic materials as photo-alignment layers involve several approaches compared to the contact and non-contact non-optical methods of LC molecular orientation previously used. There are advantages. Here, the advantages are as follows.
[0047]
-Simplicity in forming a photopatterned alignment surface having a predetermined spatial configuration of surface alignment performance.
[0048]
Good orientation of LC molecules on the surface in terms of light quality.
[0049]
.Adhesion W with molecules on the surface of the alignment layer₃Can be controlled.
[0050]
The last-mentioned advantage is particularly important, in writing high-density surface data in the data layer (302), the thickness of the LC layer must be correlated to the size of the information pits recorded in the recording layer (305). In other words, if the pits are about 0.4 mmc, the LC layer must be about 0.1-0.4 mmc thick.
[0051]
Furthermore, high adhesiveness (W₃It is not possible to electrically reorient the molecules in a nematic LC, for example in the region of about 0.01 mmc thickness, in the actual electric field controlling the orientation surface and the process of a). In other words, it is not possible to do it with a layer consisting of several molecular layers in direct contact with the mesophase. Controlling the exposure energy of the optically anisotropic material not only forms an axis of LC planar orientation, but also provides an adhesive energy value (W) that is the adhesiveness between LC molecules and surface molecules of the photoaligner.₃) Can be controlled, and consequently their electro-optical behavior can be influenced.
[0052]
Thus, in the present invention, the proposed electrically controlled multi-component electrical structure of the data layer (302), layer (304) (if available) plays the role of a conventional alignment layer. In contrast, the alignment layer (305) also operates directly as a ROM-, WORM- or RW type recording layer. In this case, hidden patterns of information pits are formed to take shape in the process of changing the alignment properties, and those changes are coordinated along the surface in relation to the LC molecules. If necessary, this pattern may be automatically read (visualized) at a high fluorescence intensity, which is performed by the guest-host liquid crystal cell of the data retention layer 302. This layer also includes an orientation recording layer (305) using anisotropically absorbing fluorescent molecules as host (308).
[0053]
The proposed composite fluorescent multilayer optical data carrier includes a CD- or DVD-read only memory (ROM), a write once read many (WORM), a rewritable (RW), Or it may be manufactured as a mixed type of them in various optical disks, cards or tapes. The shape of the two-dimensional distribution of information pits along the space of such a carrier may be drawn as a straight line or may be a spiral or circular track, in which case EFM (8-14 modulation) The data flow is written using the 14 digital channel modulation codes. Also, the data may be written in the form of four adjacent bytes recorded using the ETT (8-10) method of two-dimensional data encoding on the surface of the orientation recording layer (305).
[0054]
By changing the orientation of the axis of the dichroic molecule (308) that emits light directed to the readout radiation that excites the fluorescence, it is possible to control the fluorescence intensity. As a result of the dichroic properties of the absorbing fluorescent material (308), the light emitted thereby is of maximum intensity. However, to achieve maximum intensity, the molecules must be oriented such that the absorption of the readout radiation is maximized. The electric field generated by the controller 312 is used to change the direction of the liquid crystal matrix (307), thereby controlling the intensity of the read-out irradiation by the fluorescent molecules (308), and thus the intensity of the fluorescent light holding light emitted by them. can do. If necessary, the electric field parameters can be gradually changed without changing the intensity of the readout irradiation, and the light intensity of the fluorescent light will also change gradually.
[0055]
For example, the electrostatic deformation of a homeotropic texture of a nematic LC (501) having a negative dielectric anisotropy or a homogeneous (planar) texture of a nematic LC (502) oriented in one direction and having a positive dielectric anisotropy. Based on this, the proposed optical memory system may be structured. These deformations are achieved by correlatedly changing the orientation of the molecules of the dichroic phosphor (503) diluted in the nematic matrix (504) (FIG. 5a).
[0056]
A nematic liquid crystal, for example a nematic liquid crystal having a positive dielectric anisotropy, orients elongated molecules of a dichroic substance (503), places them parallel to each other, and further comprises molecules (502 ) Also functions as a matrix arranged in parallel. When the orientation of the liquid crystal matrix changes in the electric field, the orientation of the dichroic material (503) changes, so that the thin guest-host LC layer (504) is exposed to read (or write) and delete irradiation (505). ) Changes (absolutely zero maximum) and emission performance (also maximum zero).
[0057]
For example, when no voltage is supplied (V = 0), if the dichroic molecule (503) is to be oriented in parallel to the electrode surface (303), a nematic having a positive dielectric anisotropy (502) It is necessary to form an oriented planar structure on the sample. Furthermore, at a given wavelength, the dichroism should be such that the readout radiation is maximally absorbed (FIG. 5b, curve 1) and thus the maximum fluorescence emission in the readout mode (FIG. 5b, curve 1 '). It is necessary to select a molecule (503) having Electric field V = V₁, The positive anisotropic nematic LC (502) selected as the matrix changes its texture to become homeotropic, whereas the molecules of the dichroic material (503) are polarized. It will be oriented perpendicular to the direction of oscillation of the electrical vector of the lightwave, which may be polarized or unpolarized. Since the molecule is substantially transparent, there will be no absorption and no fluorescence emission at the wavelength of the readout illumination (FIG. 5b, curves 2 and 2 ', respectively).
[0058]
In this case, since the fluorescent background (506) does not exist in all the out-of-focus layers except for the layer being read, the fluorescent crosstalk caused by them is eliminated, and the “signal and read” in the read mode is eliminated. The "noise" ratio can be increased. The absorption performance of layer 504 can be minimized to substantially zero, which allows the use of optically anisotropic and fluorescent materials whose absorption ranges overlap completely or partially.
[0059]
To save power used by the readout device, it is preferable to use a nematic crystal with negative dielectric anisotropy. When no voltage is applied to the electrodes (303), all data retaining layers (302) do not absorb the read radiation and consequently do not emit any fluorescence. Control of the power supply to the electrode (303) (or a particular strip of electrodes 41 and 42) is only necessary to read from a given data layer (302) or a given data page (44) of this layer. is there.
[0060]
Another advantage of the proposed multi-component structure of the fluorescent data storage layer 302 when compared to existing single-layer fluorescent data storage systems is that it also acts as a photo-patterning alignment layer for the guest-host composition 307. The recording layer (305) may be as thin as desired, up to a single layer with a thickness of only 10 Angstroms. At the same time, its absorption performance is also very low, but the intensity of the read, write and delete radiation remains substantially the same (not reduced) in the process of passing through such multilayer media.
[0061]
Further, when the absorption range of the photosensitive alignment recording layer (305) and the absorption range of the anisotropic absorption fluorescent material (308) are completely or partially overlapped, the absorption performance of the anisotropic fluorescent molecules is controlled by using electricity. Is possible. Thus, data can be written, read, or deleted on a WORM or RW type carrier with an irradiation source using the same wavelength. In addition, there is an additional opportunity to use various linear and non-linear photochemical and photophysical devices for single written or rewritten data.
[0062]
Even if the thickness of the photosensitive recording layer (305) is reduced to the size of a single molecular layer at the maximum, not only does not affect the photosensitivity in the data writing process, but also in the conventional single-layer fluorescent recording layer, Note that, as is often the case, the readout process does not affect the parameters of the data (fluorescence) signal. This is achieved because the data being written is stored as a change in the orientation properties of the surface (316) of the recording layer (305), while the data retention signal in read mode causes the fluorescent molecules (308) to be stored. This is because it is strengthened by the electrically controlled guest / host LC layer (307). Signal enhancement is not dependent on the thickness of the recording layer (305), but is affected only by the thickness of the LC layer (307) and the concentration of the fluorescent material (308) there. The proposed readout technique does not assume a change in the size of the information pit (314). In addition, it is preferable to be as thin as possible to eliminate the parasitic refraction effects of writing and / or reading radiation from the out-of-focus layer to the data pits.
[0063]
In order to explain the operation principle of the data carrier in more detail, a case where the control voltage V is not applied to the electrode (303) (V = 0) and a case where the voltage is applied (V = V₁4) Schematic plan view (FIG. 6a) and cross-sectional view (FIG. 6b) of one such multi-component data layer (302) of WORM- or RW type, proposed data carrier (300). Please refer to FIG. 6A and FIG. 6B.
[0064]
The arrows (601 and 602) in FIG. 6a indicate the alignment directions on the surfaces 316 and 317 of the information pits (314) and the background area (315), respectively, and thus the optically shaped optical patterning recording alignment layer ( 305). For example, these directions may be located at an angle of 90 °, whereas the orientation direction (603) on the surface of the homogeneous layer (304) is the orientation direction (603) of the region where the pit 314 is located in the layer 305. 601) may be parallel.
[0065]
In this case, the three-dimensional image (pattern) of the guest-host LC layer (307) takes the form of optical patterning, and the liquid crystal (604) is located in the region 608 beyond the surface 316 of the information pit (606). The molecules and fluorescent molecules (605) are oriented parallel to the orientation direction (601) in the figure. The region 607 located in front of the background region 317 exhibits a twisted nematic-like appearance, and the liquid crystal molecules (604) and the fluorescent molecules (605) located on the layer surface (304) are parallel to the drawing. Oriented. On the opposite surface they are oriented at right angles to the surface, in other words, in the case of the twisting effect, the direction of the LC planar orientation on the opposite electrode will be at right angles.
[0066]
In the read phase, such a multilayer structure of the data holding layer (302) at zero voltage (V = 0) is emitted by the recording layer (305) with a polarizer having the polarization (611) shown in the figure. Receive linearly polarized light irradiation. In this process, the read-out radiation is absorbed by the molecules of the fluorescent material (605) and thus is re-emitted (612) (I_n(Pit)). However, this phenomenon is only observed in the region of the LC composition 608 in front of the surface (316) of the information pit (314), and in the region of the LC composition (607) beyond the background surface (317). Become transparent when exposed to this type of readout illumination in the context of polarized light. Visually, a non-fluorescent background (I_n(Back)) and observe the fluorescent pattern of the information pit. Also, the fluorescent radiation is polarized. Activating an additional polarizer located in front of the light receiving device allows certain background overexposure to external illumination to be avoided (not shown in FIG. 6).
[0067]
A right angle change in the direction of the write illumination polarization plane can result in a negative read mode, ie, observing a light emitting background with non-fluorescent information pits. In order to eliminate fluorescent crosstalk from other layers in read mode, they must be energized as shown in FIG. 6b. As a result, while all LC molecules (614) in the matrix and LC fluorescent molecules (613) in the matrix are oriented perpendicular to the electrodes, the out-of-focus layer is completely invisible to readout illumination. Become transparent.
[0068]
If no voltage is applied and the LC material has a negative dielectric anisotropy, the phosphor is oriented perpendicular to the electrodes, does not absorb the readout radiation, and is oriented perpendicular to the layer . In the readout phase, a voltage is applied to the selected data layer, so that the LC layer (307) with the molecules of the phosphor (308) has been correlated with the data recorded in the recording alignment layer (305). A planar orientation patterning feature will be obtained.
[0069]
For example, FIG. 7 shows that the information is recorded in the form of a patterned alignment surface, and in a corresponding type of a conventional high-fluorescence readout signal in different polarization states of the readout illumination, made of a light-anisotropic material. Some options for forming the recording alignment layer (305) are shown. At this time, whether information pits are available or unavailable in a given minute area of the carrier is quantitatively detected by the difference in fluorescence intensity between the information pit position and the background. Is done. The same applies to general fluorescent methods for reading information, for example, the methods described in [US Pat. Nos. 6,009,065 and 6,071,671 (Grushko and Levich)]. Is true.
[0070]
FIG. 7a shows that the information pits (701) and the background area (702) have surfaces that are orthogonal to each other, and the same applies to their alignment capabilities (703 and 704). Such an arrangement of the patterned recording layer (305) provides a maximum contrast equal to K = + 1 or -1 (positive or negative) when reading with linearly polarized (705 or 706) illumination. Can be However, the unpolarized illumination (707) cannot be used for this purpose, in which case the contrast will be reduced or even zero using conventional readout methods based on intensity. That's why.
[0071]
This disadvantage can be corrected by the data reading method proposed in the present invention. This method is based on the presence or absence of anisotropy rather than the difference in the intensity of the fluorescence signal (eg, varying degrees of polarization) in the fluorescence signal when polarized or unpolarized readout radiation is being absorbed. The detected signal can be detected. The technique of the present invention can also detect a difference in the direction of the polarization optical axis.
[0072]
In fact, the fluorescence emission of individual anisotropic absorbing molecules is also anisotropic. Thus, for the configuration shown at 7a that is not oriented in space, it is performed not only when reading is performed with linearly polarized (705 or 706) radiation, but also with non-polarized (707) radiation. Even so, the fluorescence data retaining illumination will be polarized. Furthermore, in the case of unpolarized irradiation, the polarization vectors of the fluorescence emission in the information pit position area (701) and the background area (702) are orthogonal to each other, and are located in front of the light receiving cells of the reading device. It can be easily identified by the polarizer located.
[0073]
FIG. 7b shows another possible configuration where there is no orientation feature (709) in the background area (708) and there is a planar orientation (711) oriented to the information pit surface (710). In this case, polarized reading (714) and unpolarized irradiation (712) can also be used with the general readout technique based on intensity, in which case the contrast is increased after module K = 1/3. The intensity I of the fluorescence signal can be obtained from the polarized irradiation (713)._nWhen (back) is twice its maximum value, a contrast equal to K = -1 is obtained. In the context of the polarized read-out illumination (713 or 714) mode, for example, an optical system including a switching modulator for rotating the read-out illumination polarization plane, and electricity transmitted by fluorescence at the dual rotation frequency of the read-out illumination polarization vector The polarization of the emission signal can be detected using a light receiving device for photoelectrically detecting the variable component of the signal. In this case, the intensity of the fluorescence emitted by the background region (709) containing the randomly oriented fluorescent molecules does not change, and the contrast component of the electric signal transmitted by this irradiation is cut off.
[0074]
When unpolarized readout illumination (712) is applied, the polarized fluorescence is only illuminated by the information pits (711), the presence of which adds another polarizer located in front of the light receiving device. Can also be detected. A single photon readout by both intensity and polarization allows both bitwise and page by page readout to be performed.
[0075]
According to the present invention, there is provided a structure including a plurality of components of a fluorescent data holding layer using an optically anisotropic material to form an alignment recording layer and a guest-host type liquid crystal composition. For the “guest”, a photochemically stable fluorescent substance capable of anisotropic absorption is used, whereby a ROM-, WORM-, or RW-type optical carrier can be manufactured. Further, the data layer composed of a plurality of components of the ROM type can be manufactured using an alignment layer conventionally used for a liquid crystal screen.
[0076]
FIG. 8a shows proposed data of the ROM type using spacers (811) located between split layers (812) of the same thickness using a transparent electrode (813) and an alignment layer (813) ensuring the same orientation. One of the options for layer (810) is shown.
[0077]
In this particular case, the spacer 811 not only ensures the necessary thickness of the LC guest / host layer with the fluorescent molecules (815) in the information pits (816), but also plays the role of a ROM type data layer. It has a three-dimensional patterned appearance and can be made from photosensitive acrylic or positive or negative photoresistors. The data recorded therein can be formed by conventional methods of contact or projection lithography or electrophotography, or by performing a scan modulated laser irradiation along the photosensitive surface followed by development. As the aligner (813), either a photo aligner made of a photo-anisotropic material or a conventional LC aligner can be used. In the present invention, one or both of the aligners (813) may be omitted in the view shown in FIG. 8a.
[0078]
FIG. 8b shows another option for the multi-component structure of the ROM-type fluorescent data layer (802). In this case, the dividing layer (821) having a data-retaining fine relief surface (822) and a flat surface (823) is formed using a reflective CD- or DVD using an injection compression molding technique or a 2P process based on a photopolymerization composition. -Made like an optical disc. Transparent electrodes (824) are sprayed on both sides of the split layer (821) to coat the alignment coats 825 and 826. In order to avoid possible damage to the data layer (826), optical methods and optically anisotropic materials were used to develop the alignment properties. The information pit (827) was filled with a guest-host LC composition 828 containing a fluorescent substance. Again, as in the case referenced above, at least one of the alignment layers (825 or 826) may not be present.
[0079]
FIG. 8c shows one of the proposed surfaces of a WORM- or RW-type data layer (830). In this case, the split layer having a flat surface (823) and a surface (833) with straight, concentric or spiral tracks or channels (834) was based on injection compression molding technology, or photopolymerization compression. It is made using a 2P process. The size and shape of the track are selected based on the orientation characteristics of the guest host LC 835 having the fluorescent molecules 836 and the desired tracking mode. The transparent electrodes 837 are sprayed on both sides of the division layer (833). If the LC layer 835 is very thin (less than 1 micron), the alignment layer (838) may be omitted and the alignment layer (840) is made from a photo-anisotropic material.
[0080]
If the same illumination source is used for the write or delete data, these processes are performed in a homeotropic orientation of the guest-host LC composition (839) of all data layers before and even in a given layer. Occurs in the read mode, and in the read mode, these processes are repeated in all layers except the layer under reading where the LC composition (839) is oriented along a plane.
[0081]
9a and 9b show an orientation recording layer (305) (plan view) of a proposed multi-component structure of a WORM or RW type data layer (302), a generalized version of which is shown in FIG. Are shown before data is written (FIG. 9A) and after data is written (9b). Tracks 911 (922) of data carriers made as optical card 910 (or optical disc 920) are located on photosensitive alignment recording layer 912 (922) made of a photo-anisotropic material. This layer 912 (922) may also serve as a photo-patterned photo-alignment layer of a guest-host LC composition layer made of anisotropically absorbing fluorescent molecules that are photochemically stable in the data layer 302 comprising the first plurality of components. Works. For example, this layer has a background region 913 (923) with randomly oriented molecular clusters 914 (924). It also has straight (for optical card 910) or spiral (for optical disc 920) tracks 911 (921), and in most cases the molecular clusters have a major orientation 915 (925). In this case, the direction of the main orientation of these molecular clusters (see FIG. 9 shown using arrows) is relative to the track, as in the case of the linear track (911) of the optical card (910). Constant angle Ψ_iOr may be located along (crossing) tracks, as in the case of concentric tracks (921) on an optical disc.
[0082]
This surface structure of each photosensitive alignment recording layer i912 (922) is oriented along an aligned molecular orientation. This orientation can be achieved by exposing the i-layer (prior to fabrication of the multilayer data carrier 300) to linearly polarized radiation (not shown in FIG. 9) that is focused and scanned along the surface, and the initial molecular structure of this layer This irradiation is absorbed by the layer's optically anisotropic material, since is in the unoriented state 914 (924).
[0083]
In addition, since photolithography technology has become very popular recently, it is also possible to use projection or contact-type optical printing by irradiating polarized light. This irradiation passes through a metal plated positive photo template with transparent tracks. To create a structure with unoriented tracks 911 (921), it is necessary to use a negative photo template against an oriented background 913 (923).
[0084]
Later, a multilayer composite liquid crystal optical carrier can be made. These are given angles Ψ prepared in advance._IUsing an orientation recording layer. One side of the intermediate layer (309) is coated with those layers and further with the electrode 303.
[0085]
As already mentioned, when data is recorded on one of the recording layers of the multilayer carrier, the desired absorption capacity of all multi-component data layers can be obtained by applying a voltage before that. And this power is provided to those layers from an external controller (312).
[0086]
Further, in a bit-by-bit write mode, a write beam (not shown in FIG. 9) is focused onto a spot 916 or 917 (926 or 927) in the track location area 911 (921) and is made of a light anisotropic material. Partially absorbed by the created recording medium 912 (922). As a result of photophysical properties, photochemical or photothermal processes, the initial molecular clusters in the material and, most importantly, on the surface of the exposed areas 916 or 917 (926 or 927) are modified, and these changes allow the guest -The alignment ability with respect to the host LC layer 307 also changes. These changes depend on the type of optically anisotropic material and the parameters of the writing pulse (pulse intensity and energy distribution in space and time, pulse duration, orientation of molecular clusters 915 at spots 916 or 917 (926 or 927)). , The polarization state and direction of the writing irradiation polarization vector). These changes appear as changes in the direction of the spatial orientation of the surface molecules 918 (928) (or formation in the negative case). For example, these alignment directions change in the orthogonal direction in the micro regions 916 (926), or, when positive, as shown in FIG. 9, are completely shifted in the micro regions 917 (927). 919 (929). The orientation of the LC layer 307 in direct contact with the modified surfaces 918, 919, 928, and 929 changes accordingly.
[0087]
The first recording option uses anisotropic material in a photochemical or photophysical recording mechanism, in which case the initial molecular orientation 916 () on track 911 (921), for example, by polarized illumination with polarization vector pointing. 926) is written orthogonally.
[0088]
A second option is to use a photothermal recording mechanism, where the writing is done after the melting of the microregion 917 (927) and the material cools and loses the molecular orientation 919 (929). . The data pits written by this method are illuminated in the mode shown in FIGS. 6 and 7 by both the illumination source with different wavelengths absorbed by the fluorescent molecules of the LC composition and also by the same illumination source used for writing. It can be read. However, in the latter case, a lower irradiation intensity must be used.
[0089]
Note that it is not entirely reliable to provide all oscillators that anisotropically absorb fluorescent molecules as linear oscillators. Thus, even if such molecules are oriented in perfect homeotropic clusters, they will absorb some of the readout radiation. Further, as described above, the fluorescent molecules dissolved in the region near the surface, for example, the region near the surface of the nematic LC and, consequently, the region that is in direct contact with the intermediate phase of the alignment recording layer 912 (922) are affected by the electric field. When affected, they cannot be completely re-oriented.
[0090]
All of this can result in incomplete loss of illumination of the fluorescent background, which consists of out-of-focus layers. In the present invention, an attempt was made to eliminate this phenomenon with higher efficiency, and an additional code of angle / individual value was used. An additional feature is that the direction of the primary orientation of the molecular cluster 915 (925) towards each track 911 (921) of the recording layer 912 (922) of the multi-layer data carrier 300 is encoded with an angle Ψ individual value. Having. This is used in the readout phase to additionally polarization separate (decode) the anisotropic (partially polarized) fluorescent illumination of the layer being read out. This helps to separate this layer from the anisotropic partially polarized fluorescent illumination coming from all other out-of-focus layers.
[0091]
All optically anisotropic materials, whether of photochemical or photophysical mechanisms, are characterized by optical anisotropy and, consequently, reversibility, which gives rise to the ability to reorient the LC. In this case, these alignment abilities may be deleted together with the optical anisotropy. In other words, certain local data recorded in the recording light anisotropic layer can be optically or photothermally deleted. In this recording layer, the write data can be completely deleted using a pure heat treatment method, that is, a method of heating the entire layer.
[0092]
The data may be restored (or rewritten) using the same modified orientation of the optical axis of the induced anisotropy polarized by the initial light irradiation with the same or different polarization vector. However, the number of these reversible cycles depends on the particular mechanism that creates the optical anisotropy of these materials.
[0093]
According to the invention, it is proposed to use a photo-anisotropic material based on a unimolecular irreversible photochemical reaction or a bimolecular photochemical reaction on a WORM type data carrier. In the latter case, materials based on low or high photosensitivity substances may be used, for example Langmuir-Blodgett multimolecular membranes or the nonacozadein of the 10,12-carboxylic acid. A diacetylene derivative group such as a sprayed film [Kozenkov V. et al. Et al., Presentations, the USSR Academy of Science, 1977, 237, 3, p. 633]. However, their reversibility is small and is limited in each cycle by the number of photosensitive molecules used in the photochemical process. However, these materials can be used for the purposes of the present invention as WORM type recording media in situations where molecular rotation is eliminated. In addition, the small reversibility of the light-induced anisotropy can be used to modify the written data during processing or recording, or after writing is completed.
[0094]
Also, most photochromic materials exhibit the effect of photoinduced light anisotropy. However, they exhibit reverse irradiation rate relaxation and have a very high quantum release, which leads to irreversible destruction of photochromic molecules in both the initial and / or photoinduced state, Not very useful for the purpose of the invention.
[0095]
For the purposes of the present invention, photo-anisotropic materials made of non-fluorescent substances that are photochemically stable and have anisotropic absorption can be best utilized. Unlike materials that exhibit light-induced anisotropy effects (Weigert effect) as a result of various reversible and irreversible photochemical reactions, these materials have polarized irradiation and polarized light. When absorbing non-induced radiation, optical anisotropy is created as a result of the photophysical process of molecular orientation. Furthermore, this process does not involve any chemical or morphological changes of the molecular cluster.
[0096]
When this occurs, a large portion of the anisotropic photochemically stable non-fluorescent molecules will be along a plane lying in a direction perpendicular to the electric field vector of the lightwave, or in the case of unpolarized illumination, It is oriented in its propagation direction. These materials are photochemically stable, which allows not only to modify the recorded data, but also to ensure an infinite number of "write / delete" cycles, in other words Writing and rewriting can be performed indefinitely. This data may be stored for many years. Furthermore, these materials enable data to be read without destroying the data.
[0097]
Further, in the proposed invention, all operations involving writing, reading, deleting, and rewriting data on such media can be performed by the same illumination source. It is not even necessary to reset its parameters (time, power, and polarized light pulse). These materials can be used as ROM-, WORM-, and RW type data carriers. These composite multi-layer data carriers are particularly competent because their configuration can include ROM-, WORM, and RW type recording layers. These layers may be made from materials of similar or different compositions. This greatly simplifies the manufacturing techniques for these composite multi-layer data carriers and extends their range of functions.
[0098]
The photochemically stable, anisotropically absorbing non-fluorescent materials used in these optically anisotropic materials may be incorporated into the polymer matrix at the molecular level, or a small number that enhances their film-forming properties. It may be used as a homogeneous single substance with special additives.
[0099]
These potentials show typical motion graphs of induction and photo-anisotropic irradiation rate relaxation (two-beam refraction) in a single material film affected by polarized light irradiation at various stages of induction or deletion. See FIG.
[0100]
As can be seen from FIG. 10, the material is isotropic in its initial thermodynamically stable state. This state is considered a logical zero "0". As data is written in the irradiation process, the material acquires the property of optical anisotropy, and the anisotropy asymptotically reaches the photostable parameter (Graph 1). For very short exposures (or low power), an emissivity relaxation process may be observed (Graph 2), whereby the induced anisotropy is completely reduced to a certain stable value. Or partially reduced, which increases with increasing exposure layer energy. Such a reduction occurs as a result of Brownian molecular rotational diffusion and can lead to random shifts of photochemically stable molecules. However, as the exposure energy increases, the rate of relaxation of the irradiation rate decreases, and the rate of relaxation does not exist (Graph 3).
[0101]
Further, a sufficiently high exposure of the active irradiation (about 0.1 to 1 nJ / η)²The termination of () results in a more aligned self-orientation of the molecules of the layer (Graph 4), reaching a new thermodynamically stable state. The rate of such "upward radiation rate relaxation" increases with increasing heat of the layer. Such a highly oriented state is considered a logic "1". This state remains stable until the temperature reaches the melting temperature of the optically anisotropic material.
[0102]
The maximum of this photoinduced optical anisotropy in these media approaches the corresponding value in liquid crystals. Therefore, the orientation state parameter S may be expressed as follows.
[0103]
S = (D₁₁-D₁) / (D₁₁+ 2D₁(1)
And the value of the two-beam refractive index Δn is
Δn = n₁-N₁₁      (2)
These values can reach 0.8 and 0.3, respectively.
[0104]
Where n₁₁And D₁₁Are the values of the index of refraction and the value of the optical density of the material for the polarization component vector of the measurement illumination created by the active illumination polarization, which may be parallel or perpendicular to the polarization vector of the activation illumination, respectively.
[0105]
It has been established that the photoinduced state of these materials (including the ordered orientation of the surface molecules) is maintained for at least 10 years or more.
[0106]
The fluorescent reading of the data written in this manner may be executed in the mode shown in FIGS. However, short-term or low-intensity exposure of such aligned and oriented layers to a similar, but unpolarized, or circularly polarized radiation source results in partial displacement (graph 5) Speaking of the liquid crystal, the alignment characteristics are partially deteriorated. The same result can be achieved when the direction of the polarization vector of the readout illumination is changed and made orthogonal. However, when the irradiation source is shut off, a photoinduced and thermodynamically stable state can be restored (graph 4 '), and the same applies to the alignment properties of the liquid crystal. Due to this characteristic of photo-anisotropic material made of non-fluorescent substance with photo-chemically stable anisotropic absorption, data is recorded in the proposed multi-component fluorescent data system and these are recorded in the orientation recording layer. When the material is used, data can be read without substantially damaging the data. In addition, the interaction between the sign of emissivity relaxation and the rate (graphs 2, 4, and 4 ') can cause "self-deletion" if the absorbed energy is very small (graph 2 in FIG. 10). ), There is no optically anisotropic "background" target for out-of-focus layers in the write mode.
[0107]
Deletion of the recorded data may be performed in the same mode as the reading, but requires more irradiation energy. In this process, one of the complete thermal (photothermal) molecular shifts (and loss of ability to align the liquid crystal) may be observed in the microregion being deleted (Graph 6). This is due to the orthogonal reorientation (Graph 6 ') (Graph 6') when the region is affected by local melting and subsequent cooling of the layer, or by orthogonally polarized illumination (in terms of LC, a change in the orientation of the alignment capability). ).
[0108]
Note that in the latter case, another thermodynamically stable situation (temperature below the melting point of the layer) can be reached when the exposure power is the same as the write mode exposure power. Since this situation is high and is oriented orthogonal to the initial alignment state, it is considered a logical negative unit "-1". When this occurs, new data may be deleted and written at the same time.
[0109]
The rewrite mode is similar to the initial write (Graph 7). In the present invention, all write and delete operations in a given photosensitive alignment recording layer are performed by applying a voltage to all out-of-focus layers that precede the given layer, including the layer itself. (In the case of an LC composition having a positive dielectric anisotropy). In another option, the voltage may be applied only to a given layer (for LC compositions with negative dielectric anisotropy). In other words, either when supplying voltage to all data layers except the layer being read (first option) or when supplying voltage only to the layer being read (second option). , Data can be read.
[0110]
In the read mode, the present invention does not utilize mass modification of the anisotropic optical properties of a given orientation recording layer 912 (922) that can perform two functions. However, they may be used for quality control or for modifying recorded data or data being written. With these media, it is possible to do it in real time and even after the recording process is completed. These operations are performed by adjusting the temporal and / or spatial parameters, and the distribution of illumination intensity and write pulse energy. Also, the polarization of the recording device or the optical system of the recording device may be adjusted.
[0111]
In fact, the photo-induced anisotropy of the photo-anisotropic material occurs directly in the exposure process, since the time required for these photo-alignment and photo-chemical processes does not exceed 100 ms. Further, the generated two-beam refraction (TBR) is guided to a transparent region which is a region located outside the spectral region of the photosensitive recording layer.
[0112]
All of these make this non-destructive method when using non-photoactive irradiation, for example, when using He-Ne (λ = 632.8 nm) or semiconductors (λ-700 nm) in real time or after completion of writing. Can be used to control the data being written.
[0113]
In the exposure phase, when using polarized photoactive illumination of the layer 912 (922) in read-out mode, one may observe the appearance of fluorescent data pit precursors, which reduces the shape of the hidden molecular orientation on the surface. In some cases, a three-dimensional anisotropic phase (two-beam refraction) modulation pattern placed against an isotropic background may be provided. Since the layer is very thin, a one-to-one correspondence is observed between the degree of aligned molecular orientation within the layer and on its surface (912) (922).
[0114]
Using a polarization analyzer located between the exposed recording layer and the photodetector, the hidden three-dimensional pit precursor pattern is converted to a three-dimensional modulated pattern, resulting in non-photoactive polarized irradiation. May control the writing quality.
[0115]
The spatial distribution (I (x, y)) of the read illumination intensity is determined using the two-beam refraction (TBR) value guided through the writing process after passing through the hidden pit precursor pattern and the analyzer. Good.
[0116]
I (x, y) = I₀× Sin²(ΠΔn (x, y) d / λ) = Const × (Δn (x, y))²      (3)
Where Tn space directed to the precursor of the pit formed and affected by active irradiation with a spatial distribution of energy H (x, y) = Δn (x, y) = Ψ (H (x, y)) distribution
d-thickness of recording layer
λ-wavelength of readout radiation
I₀The intensity of the readout radiation reaching the data carrier;
Const = I₀× (πd / λ)²
X, Y-three-dimensional (spatial) axis on the plane of the recording layer position
Assuming that the optical axes of both the polarizer and the analyzer are orthogonal, while the optical axis of the corresponding TBR recording I layer oriented at the angle Ψ is at an angle of 45 ° to these axes. May be.
[0117]
For a brief understanding of Equation 3, the absorption at the wavelength of the active radiation is very small, since the recording layer is very thin, and the intensity within the depth Z of the layer, and thus its TBR, is similar. On the other hand, it may be assumed that the value of the phase delay (φ) is also very small (φ = πΔn (x, y) d / λ).
[0118]
11 and 12 show schematics of two possible options for writing data using the proposed technique for controlling and modifying the quality of hidden information pit patterns in a layer.
[0119]
The option of FIG. 11 controls and corrects data writing for each bit by reading the hidden pattern of the recorded information bit by bit using a DRAW technique (immediate writing and immediate reading) in real time. In the writing process, a modulator 1103 modulates a laser beam 1101, which is polarized by a polarizer 1102 and recorded by a recording signal 1104.
[0120]
The modulated recording beam (1105) is focused by a lens (objective lens) (1106) on the recording layer (1107) of the multilayer data carrier (1108). The device uses a special beam scanning method in which each pit is individually exposed. This method does not require a photo template. To obtain a predetermined data pattern, the invention uses a special programming device for scanning the beam.
[0121]
In the exposed area in layer 912 (922), a continuous appearance of the precursor of the fluorescent information pits may be observed, and the pattern may be observed against an isotropic background with two-beam refraction and Obtain the shape of the spatially modulated pattern. The TBR value and its spatial distribution in the hidden pattern (precursor spatial topology) can be determined using the value and spatial distribution of the recording pulse energy. The latter is determined using the corresponding modulation code (1104) and depends on the quality of the lens focus.
[0122]
Hidden images of these phase precursors of the information pits are in bit-by-bit mode by inactive laser irradiation (1110) of focused light (eg, a helium-neon laser (1109) with an irradiation wavelength equal to 632.8 nm). It may be read in real time. To do this, the reproduction beam (1110) is converted by the polarizer (1111) into a linearly polarized beam. When this beam passes through the dichroic mirror (1113), it is focused by the lens (1116) on the focusing area of the writing beam (1105) for writing on the recording layer (1107). Upon passing through a small area of this layer, the linearly polarized reproduction beam (1112) capable of retaining the written hidden anisotropic pattern of the fluorescent pit precursor is converted to an elliptically polarized beam (1114), which is then analyzed. Partially pass through photons (1115). The lens (1116) projects the visualized image of the fluorescent pit precursor onto a photoelectric detector (1117), which emits an electrical signal (1118). After being processed by the computer, this signal reaches an exposure device control unit (not shown in FIG. 11).
[0123]
Therefore, by using the proposed method, which is formed in real time and measures the parameters of the hidden image of the fluorescent information pit precursor with high accuracy, the power and polarization of the writing irradiation, the exposure time and also the lens focus (1106) The feedback can be obtained by adjusting the quality of the intensity distribution of the exposure beam by the correction of ()).
[0124]
FIG. 12 shows another possible variant using the proposed method in which a CCD camera (1119) was used as photodetector (1117). In this case, as soon as the writing is completed, the quality of the spatial topology of the hidden pattern of the fluorescent information pit precursor in the recording layer of the multilayer data carrier (1120) is completely or selectively controlled, if necessary. be able to. The readout diagram of FIG. 12 is similar to the diagram shown in FIG. 11 and includes a polarizer (1111) and an analyzer (1115), but the lens (1116) immediately removes the entire hidden pattern of the recording layer. Readout, which is projected by the lens (1116) to the position plane of the CCD camera (1119). By being able to analyze hidden patterns in this way, it is possible to create, for example, an optimal situation for forming a ROM-type recording layer of a composite multilayer data carrier.
[0125]
Construct an electrically controlled thin liquid crystal cell with at least one initial patterning (for ROM-type systems) or photo-anisotropic photosensitive (for WORM- or RW-type systems) alignment layers The proposed technical solution of designing the fluorescence data storage layer as a multi-component structure allows the functions among the various components to be distributed.
[0126]
When writing in a WORM- or RW-type system, writing is performed on one of the alignment layers that also acts as a recording layer. Here, in the case of the LC layer, data is written by the alignment ability whose surface is spatially modulated. In other words, a photo-patterning optical alignment layer can be formed.
[0127]
In read mode, a guest-host LC matrix with a photochemically stable fluorescent host material with anisotropic absorption is used, regardless of the carrier type (ROM-, WORM-, or RW-type). In a WORM- or RW type composite fluorescent liquid crystal data carrier, this distribution of functions in the write and read modes dramatically simplifies the requirements of the fluorescent composition used in these devices. The use of photochemically stable fluorescent materials in such systems, for example, uses natural fluorescent materials based on bimolecular photochemical reactions or the current state of the art WORM-photosensitive systems in which the photoproducts are fluorescent. The problem of the preservation of the irradiation rate of the existing fluorescent data layer can be completely solved. This is related to their possible emissivity thermochemical or diffusion processes. These processes create traces made from the fluorescent molecules and also create background fluorescent illumination in read-out mode or phenomena in the intensity of the fluorescent signal due to irradiance degradation of the initial fluorescent dye.
[0128]
As mentioned above, RW-photosensitive systems based on photochromic reactions have the following disadvantages. That is, a low "write-delete-write" cycle due to the reverse irradiation rate process and the photodisruption of photochromic molecules.
[0129]
In the present invention, another option of the multilayer composite LC optical system of ROM-, WORM-, or RW memory type is further proposed. Instead of a fluorescent anisotropic absorber, this option uses a non-fluorescent, photochemically stable material that also becomes an anisotropic absorber at a given readout wavelength. These substances are used in the host molecule as additives. For this purpose, it is necessary to select a non-fluorescent substance that can be sufficiently diluted with the liquid crystal composition. These molecules are in the form of rods or disks, and their long wave oscillators are located along or across the long axis. These materials are used for LC screens that operate on the guest-host principle. Further, an anisotropic dye having negative dichroism can be used.
[0130]
In this case, all the optical memory designs (FIGS. 3-6, 7-9, 11 and 12) and the data write, read and delete operations (FIGS. 7 and 10) referred to above remain the same. . However, by detecting a quantitative difference between the read irradiation intensity at the information pit and the background position, or by measuring the presence or absence of the anisotropy characteristic of the read irradiation (degree of polarization) or the difference in the direction of the optical axis. The reading is performed by performing the measurement.
[0131]
Note also that this read mode can be used in the fluorescent system of the optical memory described above.
[0132]
Another option of the proposed solution involves the use of LC compositions containing non-anisotropic fluorescent or non-fluorescent additive molecules. In this case, the composition of the multilayer data layer remains the same.
[0133]
As shown in FIGS. 11 and 12, by arranging a multilayer data holding structure between two polarizers, reading becomes possible. In this process, the optical axis of the polarizer must be orthogonal to the optical axis of the analyzer. The information pits I read from the data layer I_i ^pitLocation area and background I_i ^backThe illumination intensity through the analyzer in the area is expressed as:
[0134]
I_i ^pit= I₀・ Sin (2a_i ^pit) ・ Sin²(Π (Δn_i ^pit・ D_i ^pit+ Δn_i ^lc・ D_i ^lc) / Λ) (4)
I_i ^back= I₀・ Sin (2a_i ^back) ・ Sin²(Π (Δn_i ^back・ D_i ^back+ Δn_i ^lc・ D_i ^lc) / Λ)
Where I₀Is the intensity of the readout radiation reaching layer i of the multilayer data carrier.
[0135]
Δn_i ^{pit, back, lc}, D_i ^{pit, back, lc}Is the DLP value induced by writing irradiation in the information pit position area of the alignment recording layer i and the adjacent LC layer i, and the thickness corresponding thereto.
[0136]
a_i ^{pit, back}Is the angle between the direction of the optical axis of each polarizer (analyzer) in the information pit and the background I data layer position area and the direction of the DLP optical axis.
[0137]
λ is the read irradiation wavelength.
[0138]
To obtain a maximum contrast equal to 1, the angle a towards the polarizer_i ^pitMust be equal to 45 ° and the angle a with respect to the polarizer_i ^backMust be equal to 90 ° (or 0 °). In this case, I_i ^pitValue = 0 and I_i ^pit= I₀・ Sin²(ΠΔn_i ^lc・ D_i ^lc/ Λ) (d_i ^back<< d_i ^lc).
[0139]
Another method of writing data to these composite multilayer optical memory systems of the WORM type, which may or may not include a fluorescent or anisotropic absorbing material in the LC composition, is photothermal writing using misalignment of the aligner surface. . For this purpose, absorption writing radiation and mechanically rubbed or Langmuir-Blodgett layers may be used, these layers being obliquely sprayed and coated with some other layer. To enhance absorption in the write mode, some material that can absorb this radiation can also be added, and they can be added to the LC layer. These can be either thermochromic or photochromic substances. Also, VO₂Electrochromic substances can also be used together with electrochromic organic or inorganic substances of the type.
[0140]
Thus, the proposal of the present invention provides a new structure of a ROM-, WORM-, or RW-type multilayer composite liquid crystal optical memory system and a method for writing and reading data to and from this structure. In the system of the present invention, the ability to absorb and irradiate fluorescent molecules dissolved in the liquid crystal matrix of the data holding layer can be electrically controlled. Also, during reading in both pit-by-pit and page-by-page modes, fluorescent crosstalk from adjacent data layers can be partially or completely eliminated.
[0141]
In addition, there are further options for electrically controlling (and, if necessary, smoothing) the intensity of the fluorescence data signal without changing the intensity of the readout illumination. In particular, the distance between layers can be minimized by reducing or completely eliminating fluorescent crosstalk. This can reduce parasitic aberration distortion and increase the number of data layers of the carrier, so that more light from the read fluorescence illumination can be collected and the design of the read optical head can be simplified. . Furthermore, the proposed solution expands the possible areas of application, which applies not only to various nonlinearities of single or multiple data writing, but also to linear photochemical or photophysical mechanisms. It also allows the same illumination source to be used to write, read, and delete data on such carriers.
[0142]
Rewriting with fluorescence data reading by using a photo-anisotropic material based on a photochemically stable non-fluorescent substance with anisotropic absorption as a recording medium that also plays the role of a photo-aligned photo-alignment layer Possible multilayer memory systems can be applied substantially.
[0143]
The present invention may be illustrated using the following examples of the composition and structure of the proposed guest-host liquid crystal data retention layer.
[0144]
Example 1 ROM-type fluorescent data holding layer in which the spacer also acts as a data carrier layer
Fluorescent substance-1.4-bis (N, N-diphenylaminophenyl-1,3,4-oxadiazyl) benzene or 1,8-naphthalene-1 ', 2'benzimidazole
Liquid crystal-4-octyloxy 4'-cyanobigenyl (8OCB)
Example 2. WORM type fluorescence data retention layer
Optical aligner-paramethoxy polyvinyl cinnamate
Fluorescent substance-dye # 1 (FIG. 13)
Liquid crystal-LCM440 (NIOPiK, Russia)
Example 3 RW type fluorescence data retention layer
Optical Aligner-Dye # 2
Fluorescent substance-dye # 1
Liquid crystal-LCM807 (NIOPIK, Russia)
Example 4. RW type data retention layer containing dichroic dye
Optical Aligner-Dye # 2
Liquid crystal-LCM807
Dichroic dye-Dye # 3
Example 5 RW type data storage layer without dye
Optical Aligner-Dye # 2
Liquid crystal-LCM440
The examples referred to above are merely illustrative of the proposed structure of a multilayer composite fluorescent liquid crystal optical memory system and the method of writing and reading data to / from that structure. These examples do not limit the claims set forth in the claims.
[Brief description of the drawings]
[0145]
FIG. 1 is a schematic diagram of page-by-page data readout from a multilayer fluorescent information carrier having a fluorescent background created by an information layer that is not to be read.
FIG. 2 is a schematic diagram of bit-by-bit data readout from a multilayer fluorescent information carrier having a fluorescent background created by an information layer that is not to be read.
FIG. 3 is a schematic cross-sectional view of a general option of a proposed structure consisting of a composite liquid crystal-fluorescent dye type multi-layer data carrier.
FIG. 4 is a schematic illustration of a data storage layer having transparent electrodes in the form of two mutually orthogonal strips.
FIG. 5 is an alignment and switching configuration of a fluorescence-liquid crystal data layer.
FIG. 6 is a plan view and a cross-sectional view of one data holding layer when a voltage is applied to an electrode and when no voltage is applied.
FIG. 7a. b) Various options for forming a recording layer with patterned and oriented surfaces, and a mode for reading the fluorescence signal from these surfaces.
FIG. 8a. b. c ROM-, WORM-, or RW-type composite data storage layer structure option.
FIG. 9a. b is a schematic plan view of tracks shown on an optical card and an optical disk before and after writing by beam incidence, respectively.
FIG. 10 is a typical diagram of a kinematic curve of derivation, deletion, and photo-anisotropic dark relaxation of a photo-anisotropic material including a photochemically stable anisotropic absorber. The upward (↑) and downward (↓) arrows indicate when photoactive irradiation is turned on and off. The symbols A → B and B ← A indicate when the polarized photoactive radiation has been switched to orthogonal mode. The symbols "0", "1", and "-1" indicate the starting position and the two light-induced and stable states, respectively, in thermodynamic terms.
FIG. 11 is a schematic diagram of one of the options of a bit-by-bit data writing device when data is written to a multilayer fluorescent liquid crystal optical data carrier ensuring bit-by-bit control and adjustment of the quality of data writing in real time. .
FIG. 12 is one of the designed options for controlling the quality of the written recording layer of the multi-layer composite fluorescent liquid crystal optical carrier on a page-by-page basis.
FIG. 13 is a structural formula of a dye.

Claims (27)

A multi-layer composite fluorescent liquid crystal optical data carrier,
Including a plurality of data retention layers arranged in parallel planes,
The data layer is arranged on the same pad, divided by a transparent intermediate layer,
Each of the data retention layers is fabricated as a multi-component structure comprising an electrically controlled thin liquid crystal cell made from two similar optically transparent electrodes, wherein the transparent electrode is a solid Made as a system of layers or two mutually orthogonal strips, coated with at least one alignment layer, separated by spacers, and in the space between said spacers, the guest-host liquid crystal composition and the photochemically used as host Data carrier filled with fluorescent material with stable anisotropic absorption. Optically transparent electrodes are applied to both sides of the glass or polymer interlayer, preferably optically isotropic and transparent to all write, read, fluorescent and deleterious radiation, 2. The data carrier according to claim 1, wherein at least one has a smooth surface, while the other side includes tracks in the form of small pits. All data retention and refractive index of the intermediate layer and the guest-host LC composition in the homeotropic state (or depending on the planar state, its properties and the write mode and / or the read data), the write fluorescence (data retention) and read ( 3. The data carrier according to claim 1, wherein the wavelengths of the data excitation) and the deletion irradiation are the same or close to each other. 2. The data carrier according to claim 1, wherein the data holding layer is made in the form of a multilayer interference anti-reflection filter for the wavelengths of the writing, fluorescence (information carrier) and its excitation (reading) and erasure illumination. The data carrier according to claim 1, wherein the thickness of the LC layer is a size corresponding to a minimum size of the information holding pit formed in the layer. It contains a substance that can be dissolved in a liquid crystal composition, and because the substance is a photochemically stable substance that becomes fluorescent in a predetermined spectrum, it emits a large number of photons (quantum) and becomes highly fluorescent. Yes, these materials have molecules oriented in tough rod-like or disk-like clusters, and the long-wave absorbing oscillators of said molecules are oriented along or across the long axis Data carrier according to any one of claims 1 to 5. Aromatic hydrocarbons and their derivatives such as multi-core concentrated aromatic hydrocarbons and their derivatives, aromatic hydrocarbon groups including arylethylene groups and arylacetylene groups and their derivatives (1,2-diarylethylene, diarylpolyene, Compositions containing stilbene functional substitutions and 1,4-distyrylbenzene substitutions, etc.) and polyphenyl hydrocarbons, 5- (furans, thiophenes, pyrroles and their derivatives), six-membered molecules (one or two Nitrogen atom composition or one or two oxygen atom composition, etc., heterocyclic composition, carbonyl group (coumarin and carbostenated substances, anthrone and aromatic acid derivatives, oxazole-5-substituted, indigoid and thioindigoid, quinone Etc.), including naphtha Composite of an acid compound, a metal having an organic ligand such as a xanthene group, an acridine group, an oxazine group, an azine group, a perylene group, a terrylene group, a vialonthrone group, a cyanine group, a phthalocyanine group, a porphyrin group, and an organic dye 7. The data carrier according to claim 1, comprising a fluorescent substance selected from a photochemically stable composition containing a compound. 8. A data carrier according to claims 1 and 7, comprising nematic, smectic or cholesteric liquid crystals or mixtures thereof with other substances for obtaining liquid crystals. 9. The data carrier according to claim 8, wherein the liquid crystal and the fluorescent substance are mixed in a molar ratio of 1: 0.01 to 1: 0.8. The data carrier according to claim 1, wherein the photochemically stable fluorescent material having anisotropic absorption has a covalent bond with a molecule of a substance having a liquid crystal property. 2. The data carrier according to claim 1, wherein the data carrier includes a liquid crystal substance as a fluorescent material that is photochemically stable and has anisotropic absorption because the material is affected by irradiation and emits fluorescence when absorbing the irradiation. At least one orientation that can be manufactured by one-way mechanical rubbing of polymer films, Langmuir-Blodgett films, or oblique spraying, or made using a non-contact photo-alignment method that works well with photo-anisotropic materials The data carrier of claim 1, including a layer. A spacer disposed between the smooth (both sides) equal thickness dividing layers, said spacer having a three-dimensional patterned appearance, ensuring the required thickness of the guest-host liquid crystal composition, 2. A data carrier according to claim 1, which simultaneously acts as a type data layer. 14. The data carrier of claims 1 and 13, comprising a three-dimensional patterned spacer that may be made from a photosensitive polymer or a positive or negative photoresistor by applying lithography or laser scanning. A three-dimensional patterned spacer simultaneously acting as a ROM-type data layer, said spacer being molded by injection compression molding technology or a 2P process based on a photopolymerization composition and arranged on one of the surfaces of said split layer 14. The data carrier according to claim 1 or claim 13, wherein A data carrier according to claims 13 and 15, which may not have one or both alignment layers. 2. The method of claim 1, wherein one of the alignment layers also acts as a ROM-, WORM-, and RW type light-emitting layer recording layer, said layer being made of a photo-anisotropic material that is not dissolved in the guest-host liquid crystal composition. Data carrier. 18. The data carrier according to claim 1, wherein the minimum thickness of the photosensitive alignment recording layer may be the same as one monolayer. 2. The data carrier according to claim 1, wherein a track area for guiding a beam of a recording, reproducing or erasing operation is formed in a photosensitive alignment recording layer made of a photo-anisotropic material. 18. The data carrier according to claim 1, wherein an energy value of adhesion between liquid crystal molecules and molecules on the surface of the photosensitive alignment recording layer can be controlled by exposure energy to polarized light irradiation. 2. The data carrier according to claim 1, wherein the WORM type photosensitive alignment recording layer is made from a photo-anisotropic material based on a unimolecular irreversible photochemical reaction or a bimolecular photochemical reaction, such as a diacetylene derivative or polyvinyl cinnamate. . The data layer may be of the following types: CD- or DVD-read only memory (ROM), write-once-read-many (WARM), rewritable (RW), or a mix of them on various optical disks, cards or tapes 2. The data carrier according to claim 1, which may be of the following type. Claims: A photochemically stable anisotropically absorbing non-fluorescent material may be introduced into the polymer matrix or used as a homogeneous single material with a small number of special additives that serve to enhance film-forming properties. Data carrier according to claim 1 and claim 22. 23. Data carrier according to claims 1 and 22, wherein the data layer is designed as a multi-component structure and comprises an electrically controlled thin liquid crystal cell having at least one alignment layer. A device for writing, reading, and deleting data on (from) a fluorescent multilayer data carrier,
Manufactured as a solid layer or as a system of two mutually orthogonal strips, coated with at least one alignment layer and electrically controlled consisting of two similar optically transparent electrodes separated by spacers A multi-layer composite fluorescent liquid crystal optical information carrier including a plurality of data storage layers having a structure composed of a plurality of components constituting a thin liquid crystal cell, wherein a space between the spacers includes a guest-host liquid crystal composition and a photochemical used as a host. An optical information carrier, which is filled with a fluorescent material having a stable anisotropic absorption,
An electromagnetic irradiation source having a wavelength for performing optical or thermo-optical writing, optical reading, and optical or thermo-optical deletion of information stored in the data carrier;
Polarization optical means for setting the polarization characterized by writing, reading, and erasing illumination;
Optical means for forming a predetermined spatial configuration of an electromagnetic beam for writing, reading and deleting information in a pit or page mode;
After photoelectrically detecting the intensity and / or polarization characteristics (reading degree and aroma of the main orientation of the partially polarized radiation) of the data-retaining fluorescent radiation to be read out, pit-by-pit or page-by-page, it is then subjected to a data-retaining electrical signal. Light receiving means for converting the
Optoelectronic means for performing quality control and correction of write data, capable of transmitting a feedback signal of write mode correction immediately after real time or completion of writing,
Means for applying a voltage to any given solid or strip electrode pair to control the absorption and fluorescence capabilities of the guest-host liquid crystal composition disposed between the electrodes;
Including devices. 6. The device according to claim 5, wherein the absorption spectrum of the photosensitive alignment recording layer made of a photo-anisotropic material and the spectrum of the multilayer data carrier phosphor partially or completely overlap. Have the same wavelength of light irradiation, but different time, energy, and polarization parameters, to write, read, delete, and modify data written on WORM- or RW-type multilayer optical carriers 27. The device according to claims 25 and 26, comprising an illumination source.

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