WO2001029837A1 - Medium for fluorescent read-only multilayer optical information carrier and its manufacturing method - Google Patents

Abstract

Fluorescent read-only media multilayered information carrier with separated fluorescent information carrier regions (511) against non-fluorescent background (512) in each layer (509) and the methods for making this. A photolithography process where the data carriers are formed from an originally non-fluorescent photosensitive layer (509) applied directly onto the photomask (501), followed by exposing the layer (509) through the photomask to produce fluorescent information pits (511) immediately in front of the transparent regions (504) of the photomask. Special photochemically stable transparent luminophors which control the spectral and luminescent properties of the data carrier layers (509) are generated in the photosensitive compositions.

Description

MEDIUM FOR FLUORESCENT READ-ONLY MULTILAYER OPTICAL INFORMATION CARRIER AND ITS MANUFACTURING METHOD

BACKGROUND OF THE INVENTION

1. Field of invention

The present invention relates to optical memory systems and in particular to fluorescent multilayer Read-only Memory (ROM) optical disks and optical cards.

2. Description of the prior art

Existing optical memory systems utilize two-dimensional data carriers with one or two information layers. Most of the previous technical solutions in optical data recording propose recording of changes in reflected laser illumination intensity in local regions (pits) of the information layer. These changes could be a consequence of interference effects on relief optical disks of CD or DVD ROM-type, burning of holes in the metal film, dye bleaching, local melting of polycarbonate in widely used CD-R systems, change of the reflection coefficient in phase-change systems, etc.

Three-dimensional, i.e. multilayer, optical storage systems provide a comparatively higher storage and recording capacity. However, this imposes specific limitations and requirements on the design and features of the optical information carrier, ways of data recording and reading, especially in the depth of the carrier.

In the reflection mode, each information layer of the multilayer optical information carrier possesses a partly reflective coating which reduces the intensity of both reading and reflected information beams passing through the media to the given information layer and back to the receiver. Due to their coherent nature, both beams are subject to lower refaction and interference distortions on fragments (pits and grooves) of the information layers on their way.

Multilayer fluorescent optical information carriers with fluorescent reading are preferable, as they are free of partly reflective coatings. Diffraction and interference distortions in this case are much less due to the incoherent nature of fluorescent radiation, its longer wavelength in comparison with the reading laser wavelength, and the transparency and homogeneity (similar refractive indices of different layers) of the optical media towards the incident laser and the fluorescent radiation. Thus, multilayer fluorescent carriers have some advantages over the reflective optical memory.

The system is based on an incoherent signal, such as fluorescence and/or luminescence and has twice as high spatial resolution as compared to coherent methods, such as reflection, absorption or refraction (see Wilson T., Shepard C. "Theory and Practice of Scanning Optical Microscopy", Academic Press, London, 1984). Using an incoherent signal the multilayer optical memory could lead to as high increase of information capacity as eight times. Today the general requirement to all types of fluorescent multilayer ROM- type data carriers (optical disks and cards) is creating carriers possessing maximum possible capacity and density of recorded information and maximum possible reading speed. These demands are met through minimizing the size of information pits, increasing their recording density in each information layer, increasing the number of information layers and transfer to shorter-wave sources of reading radiation (information density that can be stored in N-dimensional storage systems, where N = 1 , 2, 3, is inversely proportional to the wavelength to the power N). Increasing the power of information luminescent signal allows one to achieve a high reading speed. Two variants are possible for a fluorescent 3D data carrier medium for Read-only Memory. Variant 1. The paper "Novel Organic ROM Material for 3D Memory

Devices" by A.S. Dvornikov and P.M. Rentzepis (Opt. Commun., 136 (1997), 1-6) reports a medium as a single polymer block comprising uniformly distributed at the molecular level photosensitive and other components (non- fluorescing dye precursors). In such a system data were recorded and read via two- or one-photon absorption by photosensitive molecules at the stage of data recording and by photochemically generated molecules of colored fluorescing dyes at the stage of data reading, respectively.

Fig. 1 shows the reaction mechanism for information recording and reading in said ROM material (see Dvornikov and Rentzepis). It follows from Fig. 1 that some organic dyes, such as Rhodamine B, can exist in two forms depending on the matrix acidity and polarity. One of these forms, for instance base of Rhodamine B, is colorless and shows no fluorescence. In the presence of an acid, however, this colorless form turns into a colored, strongly fluorescing dye. Theoretically, the proposed fluorescent three-dimensional optical storage system has a high information capacity (~10¹⁴ bits/cm³).

However, the drawbacks of the above ROM material are the need of using a bit-by-bit two-photon photochemical recording mode for each information carrier layer and low photosensitivity of said material. This virtually precludes mass production of the read-only memory using this material. Variant 2. Theoretically the ROM type fluorescent multilayer optical storage system has a lesser information capacity as compared to the above- mentioned true three-dimensional system but it has a simpler technology for manufacturing the ROM data carrier. To form individual information carrier layers one can utilize both photosensitive non-fluorescing dye precursors transformed to colored, strongly fluorescing dyes as a result of one-photon photochemical processes, and nonphotosensitive strongly fluorescing dyes.

The basic requirement to the non-fluorescing precursor as the main component of the ROM material is thermal and photochemical stability of the resulting photoinduced fluorescing product.

Figs. 2 and 3 demonstrate two possible types of conventional multilayer information carrier ROM-medium (20 and 30) in which information carrier layers 21 and 31 are separated by polymer layers 22 and 32 transparent for reading and fluorescing radiation.

They are distinguished by the form of the fluorescent information carrier layers wherein spatially separated information layers 21 can be absolutely continuous (first type). The fluorescing substance fills both microholes (information pits) 26 and space 27 between them. The design of a fluorescent read-only multilayer information carrier shown in Fig. 2 admits utilization of well known injection-compression molding technologies or the 2P technology using relief master disks followed by applying information layers 21 using spin coating, roller coating or dip coating techniques.

In the bit-by-bit data reading mode, due to the large density of the reading radiation power (KW/cm²), molecules of the fluorescing dye must have high photo and thermal stability, while the high rotation velocity of the optical disk (10-40 m/s) imposes restrictions on the dye's fluorescence life time (less than 10 ns).

Such a structure of multilayer information medium is most acceptable for ROM-type optical disks. For bit-by-bit data reading, in disk systems predominantly a tightly focused laser beam 23 is used. Spatial filtration in collecting radiation from information pits 24 by the receiver enables low magnitudes of interlayer crosstalk resulting from the excitation of fluorescence 25 of adjacent information layers passed by reading radiation 23. Therefore, the use of such data carriers permits low (K = F(max)/F(o) = 2-4) contrast of the reading signal from each individual information layer (see Fig. 4).

In Fig. 3 there is another variant of multilayer information medium, in which information layers 31 are arranged as islands (an island-like structure) and information pits 36 alone are filled with the fluorescing composition. This ensures a significantly better contrast (K = 10-20) of each individual layer. However, in case of data reading via unfocused radiation 37 the interlayer crosstalk is much higher due to poorer spatial filtration of the image.

The above structure of information carrier layers is most preferable for fluorescent multilayer information carriers 30 made as optical cards allowing multichannel (page-by-page) reading by a CCD-camera of whole data pages 34 consisting of several thousands of pits 35.

Page-by-page reading requires relatively low exciting radiation intensity (1- 10 W/cm²) and admits a longer (0.1-0.001 s) process of luminescent image reading. This leaves room for using not only the fluorescence phenomenon inherent in organic molecules with π conjugated electronic system, but also

compositions fluorescing for up to 0.001-0.1 s. Specifically, in the card it is possible to utilize luminescence of lanthanides. Therefore, we predominantly use luminescence as a broader term.

There are a number of practicable technological techniques available for manufacturing island-like information layers. PCT Appl. No. 99/24527 covers a method for manufacturing CD-ROM- type fluorescent optical memory disks. The method comprises: generating a substrate formed as a disk which has a surface and is covered with pits in the surface, and applying a nonphotosensitive fluorescent composition by spin coating, roller coating or dip coating onto the surface of the substrate in such a way that the pits are filled with the fluorescent composition while the surface outside the pits remains free of the fluorescent composition and does not fluoresce.

The drawback of this procedure is the difficulty of complete and uniform removal of the dry film of the fluorescent composition from the surface of the information layer outside pits. This can result in a lower yield of satisfactory products at the stage of manufacturing optical disks and a lower signal to noise ratio for reading.

In U.S. Pat. No 5,211 ,986 a spin coating procedure using vertical substrates is proposed for filling pits alone on flat surfaces with a viscous substance. This method can be also applied for mass production and copying of individual information layers and fluorescent multilayer ROM-type information carriers themselves in combination with the injection-compression molding technology or the 2P process using relief carrier master disks. In this case only information pits can be filled with the fluorescing composition with minimum width of the "background" fluorescing layer in between. However, this method is rather complicated when it is requisite to achieve a high- accuracy reproduction.

In U.S. Pat. No 5,645,964, a contact photolithography procedure is used for mass-scale copying of single-layer ROM optical disks of absorption type. In doing so, polymer photosensitive compositions based on dyes and free radical photo generators, in particular, Ciba Geigy initiators, photochemically stable in the visual spectral range are used to generate information layers. Exposing said information photosensitive layer by UV radiation (250-350 nm) via a positive photomask (transparent pits against a nontransparent background) leads to forming free radicals in illuminated regions of the information layer ensuring effective bleaching of the dye. When the information layer with recorded information pits is irradiated in the 500 to 800 nm range, the photo generators do not absorb this radiation and dyes remain resistant to the action of reading radiation. Applying conventional contact photolithography procedure for generating information elements with the resolution required by standards for CD- and DVD-ROM and higher (the size of information pits is less than 0.4 μm) is

however troublesome, as in such case it is requisite to provide gaps of less than 0.4 μm between the surface of the photomask and the one of the

information carrier layer. The latter generally has surface irregularities on the order of a few microns while the thickness of the information carrier layer varies within tens of microns. As a result, it is very difficult to press it against the photomask uniformly throughout the surface.

A similar contact photolithography procedure is used in PCT Application No. WO 99/23652 for generating a three-dimensional read-only memory (ROM-type) having at least two information fluorescent dyes. In this case, in place of the relief master disk with information carrier microholes (pits) described in U.S. Pat. No 5,645,964, a widely used in the microelectronic technology metal-coated photomask with transparent pits against a nontransparent background.

The basis for forming the information carrier layer is a layer of photosensitive polymer (a negative organic photoresist) with a uniformly dispersed fluorescing dye photochemically stable at the molecular level. In these layers, information pits are formed by the photolithography procedure as fluorescing microislands against a non-fluorescing background (following the exposure and development of the photoresist). The method proposed in this patent application has the same disadvantages as the one described in U.S. Pat. No 5,645,964.

In U.S. Pat. No 4,980,262, a technique is proposed for copying videodisks by the contact photographic printing using an immersion layer, bleaching in the process of exposure, between the photomask and the information layer. This method noticeably improves the quality of copied videoinformation but fails to provide good reproducibility of the size of information pits throughout the surface. In PCT Application No WO 99/47327A1 , another method of contact photolithography for mass-scale copying of optical fluorescent read-only information carriers is proposed. The essence of the method is that it utilizes a special metal-coated photomask as a master disk with deep (0.35-0.5 μm)

and transparent information pits on a glass substrate. The liquid photosensitive composition with a photostable fluorescing dye is applied directly onto the photomask using the spin-coating procedure.

The exposure of the photopolymerized layer by the UV radiation from the side of the transparent substrate is carried out in such a way that solidification of the photosensitive composition occurs only in the information carrier pits

(0.35-0.5 μm). Thereupon the nonpolymerized regions (between the pits) are

removed.

The above method prevents diffraction diffusion of the information pits formed but it is too difficult to be practical due to the complexity of manufacturing photomasks as deep as these with the resolution of -0.2-0.4 μm and the difficulty of defect-free transferring the multiplicity of small in size

and large in height trapezoidal pits from the photomask onto the substrate.

SUMMARY AND ADVANTAGES OF THE INVENTION It is therefore a primary object of the present invention to provide a new photolithographic method for manufacturing and copying fluorescent ROM- type multilayer optical information carrier (FMC), an information carrier composition for the implementation of this method and the resulting improved luminescent information carrier. In this method, just as in PCT Appl. No. WO 99/23652, standard positive photomasks are used, the surface of said photomasks being modified to diminish adhesion to the information carrier layer made of the same information carrier composition. Each information carrier layer represents a continuous thin polymer film containing discretely formed fluorescing microregions (information pits). This approach significantly improves the quality of the information pits and simplifies the process of transferring the formed information carrier layers from the photomask onto the multilayer data carrier. In addition, the precursor of information carrier layer is a solid polymer solution of photosensitive compounds capable of photochemical generating fluorescing molecules resistant to light and heat. The present invention also relates to the method for manufacturing luminescent multilayer read-only-type of information carrier having multiple information layers positioned between spacing layers, each of said information layers containing multiple separated microvolumes (analogs and information pits) capable of generating a fluorescent information signal against a non-fluorescing background when affected by exciting (reading) radiation.

Another aspect of the present invention is use of a photosensitive composition for manufacturing luminescent information carrier layers wherein the composition comprises photosensitive non-fluorescing compounds capable of generating fluorescent products as a result of mono- or bimolecular photochemical reactions in the solid photosensitive film made of this composition. The exposure was performed through an information carrier photomask with CD- or DVD-like data patterns encoded as transparent information pits on the nontransparent background. Another feature of the present invention includes the application of the photosensitive composition either immediately onto the photomask or onto one side of the polymer film subsequently used as a spacing layer. Additionally, the subject invention includes the use of thermo- or photopolymerizable glues for forming the luminescent multilayer read-only- type information carrier; and for providing spacing layers when solidified. According to the present invention, photochemical reactions generate luminescent photoproducts forming information carrier pits. These reactions take place between non-fluorescing compounds having proton-dependent auxochromes, such as Rhodamine B lactam (see U.S. Patent No. 6,027,855) and photosensitive compounds that are acid photogenerators, for instance onium, ferrocene or diazonium salts.

The present invention also includes the possibility of generating the multilayer information carrier with maximum in intensity and identical in size luminescent signals from the pits through proper selection of the composition of the photosensitive layer, its thickness or the exposure energy at the stage of forming each information layer of the multilayer carrier.

Another feature of the present invention is the dssensitization of the photosensitive layers following the formation of the fluorescent information carrier layer by means of additional wet treatment. Further, the present invention relates to the use of special photochemically stable luminescent additives within the photosensitive composition which ensures controllable variation of spectral and fluorescing properties of the photosensitive layers; in particular, the high intensity of the fluorescent information signal in a given spectral range relative to the wavelength of the reading radiation. In this case, different information carrier layers can fluoresce in different spectral ranges but be read by either the same or different radiation source.

Brief Description of the Drawings

Fig. 1 illustrates the reaction mechanism for the fluorescent ROM material. Fig. 2 schematically presents the bit-by-bit reading from the fluorescent multilayer carrier with the fluorescing background in information layers.

Fig. 3 schematically presents page-by-page reading from the fluorescent multilayer carrier without any fluorescent background in information layers. Fig. 4 is a diagram explaining how to derive the magnitude of contrast from the fluorescent pit cross-section in the i^th information layer.

Figs. 5a-c are flowcharts for the FMC manufacturing process.

Fig. 6 is a qualitative graph of the kinetics of storing the fluorescent photoproduct during the exposure of the photosensitive film for different embodiments.

Fig. 7 is a graph which shows fluorescence spectra of photosensitive films comprising various fluorescent additives F.

Fig. 8 is a graph which shows fluorescent intensity and image contrast as a function of time. Fig. 9 is a graph showing absorption and fluorescence spectra of the

Rhodamine B lactam polymer film and the died form thereof before and after UV radiation.

Figs. 10(a) and 10(b) are the fluorescent microimage and graph of one fluorescent layer manufactured by spin-coating of the photomask, the latter being in the CD-ROM format.

Figs. 11(a) and 11(b) are graphs which show the absorption and fluorescence spectra, respectively, of the photosensitive composition with F component (oxazine 1 ) on the glass substrate before and after UV radiation. Figs. 12(a), 12(b) and 12(c) are graphs which show the fluorescent image for different information layers in a 20-layer information carrier where 12(a) is the 1^st layer, 12(b) is the 10^th layer; and 12(c) is the 20^th layer.

Fig. 13 is the fluorescent microimage of a fragment of the information layer obtained using the vacuum-press photographic printing technique, according to the present invention.

Detailed Description of the Preferred Embodiments. In the present invention, several preferred embodiments are described for manufacturing the read-only multilayer optical information carrier with fluorescent reading.

Referring first to Fig. 5(a) which is a flowchart 500 for a process for fabricating the read-only fluorescent multilayer optical information carrier (FMC) of the present invention. In Fig. 5(b), the initial stage, information carrier photomask 501 with CD- or DVD-like data patterns is made by standard photolithographic methods applied in the manufacturing process for microelectronic devices (Moreau W.M., "Semiconductor Lithography". Plenum Press, New York and London, 1988). To do this, a thin (100-200 nm) layer of chromium 503 is applied onto polished (transparent in the UV and visible spectral range) glass or quartz substrate 502. Then, a thin layer of photoresist or electronoresist is applied onto the metal-coated surface of substrate 502. Thereafter, a CD-like data pattern is formed in the metallic layer as transparent pits 504 on nontransparent background 505 using a high- resolution photo- or electron-beam lithographic procedure. To improve the safety of photomask 501 and isolate the chromium surface possessing high adhesion to most of polymer coats, the photomask is coated with about 50- 100-nm thick silicon dioxide 506 by ionic bombardment. The coating is sufficiently strong to reliably protect the photomask. If necessary, the photomask surface may be cleaned with organic solvents. To reduce adhesion, the surface of the photomask is treated by antiadhesive agent 507. In the second stage, photosensitive solution 508 is prepared. The solution comprises a polymer binder, photosensitive agent and other components, e.g., non-fluorescing dye precursors, photochemically forming colored fluorescent dyes.

In the third stage, photomask 501 with CD- or DVDV-like data pattern pits is spin-coated by photosensitive solution 508. A suitable spinner is used that can vary in speed from several hundred revolutions per minute (RPM) to several thousand RPM. Such a spinner preferably has vents to provide film drying while spinning. A thin film 509 0.2-1.0 micron thickness (preferably 0.4- 0.8 μm) is formed. The thickness enables subsequent generation of 0.4-1.0

μm (preferably 0.3-0.5 μm) information pits.

Thereafter, photosensitive film 509 is exposed by activating UV radiation 510 via photomask 501. As a result of the photochemical reaction in layer 509, in the regions located immediately behind information pits 504, fluorescing pits 511 are formed. Thus, in continuous photosensitive film 509, information carrier layer 512 is formed; in the volume of said layer fluorescing microregions (information "pits") are discretely positioned. The refraction indices of information carrier layer 512 in the places where photocemically generated information pits 511 are positioned and outside them (the background) differ not more than by the value of 0.01 to 0.02. This is the reason for almost complete absence on them of light scattering of the reading and fluorescing (information) radiation and hence for better contrast of the recorded signal.

In the fifth stage, film fluorescent information layer 510 is separated, e.g., by peeling off, from the photomask and then laminated onto another, hard substrate or nonfluorescent layer (see Fig. 5(b)).

Stages 1 to 5 are repeated using different substrates as many times as required for generating corresponding information layers. In so doing, each time as a substrate for transferring the next, say N ^h information layer, a substrate with N-1 earlier formed information and spacing layers are used. In the present invention, two embodiments are proposed describing consecutive stages of separation and transfer of fluorescent information layers that have been formed in stages 1 to 4 and assembling said layers to form a multilayer optical information carrier.

According to the first embodiment, as seen in Fig. 5(b), a suitable liquid photopolymerizable glue 513 is used. Glue 513 is applied onto the information layer 512. A polycarbonate or polymethylmetacrylate substrate 514 (or a substrate with pre-attached information and spacing layers) then applied and is compressed 515 to obtain a layer 516 uniform across its thickness. The thickness of said layer is controlled within 10 to 100 μm using

spacers 517. A vacuum is applied to reduce the number of air bubbles trapped inside layer 516. Thereupon, layer 519 is solidified by means of activating radiation 518 and separated together with information carrier layer 512 and substrate 514 from photomask 501. The photopolymerizable glues used herein and those which do not dissolve the information layer and in solid state 519 have a refraction index close to that of said information layer, Radiation 518 should be photochemically inactive with respect to information carrier layer 512. This can be attained, for instance, through using photopolymerization initiators sensitive to visible light (400-500 nm) in combination with UV-light-sensitive (250-360 nm) photodying initiators for the information layer. In gluing, the spectral composition of radiation 518 is formed by means of light filters.

Instead of liquid photopolymerizable glues, any suitable dry photopolymerizable glues may be used, as for example, "SURPHEY" produced by E. I. Du Pont de Nemours and Co. (USA) (see F. Shvartsman, U.S. Pat. No 5,279,689) incorporated herein by reference),

The structure of the dry photopolymerizable glue is given in Fig. 5c. The structure includes flexible dry photopolymerazable glue film 520 and two protection layers 521 and 522. At the first step, protection layer 521 is taken away and dry glue film 520 is laminated onto the surface of photomask 501 with information layer 512. Then protection layer 522 is removed and the back side of dry film 520 is laminated onto the surface of the substrate with N pre- attached information and spacing layers. Thereafter, film 520 is solidified with the help of radiation 518 and separated together with the information fluorescent layer and the substrate. Afterwards, the above-mentioned operations (1-4) are repeated as shown in Fig. 5b.

Whereas in the proposed method the information carrier layers retain their photosensitivity, they should be protected from daylight. Such protecticn is provided through adding special light-absorbing dopants to the spacing layers covering the multilayer information carrier from outside. For instance, we use Tinuvin, e.g., Tinuvins 144, 292 and 622) to protect the information carrier from UV radiation in concentration 0.1 M, the thickness of the protective layer being 40 μm, absorbs 99.9% incident light in the spectral range below 340 nm

thus greatly slowing down the photodying of the photosensitive layer.

Another possible way to protect information layers from exposure is desensitization following exposure via the photomask by means of wet treatment. In this case, unreacted photosensitive components, such as molecules of the acid photogenerator and/or molecules of the non-fluorescing dye precursor, are washed out of the photosensitive layer. This treatment of the exposed information carrier layer can be performed either directly on the photomask or after the transfer of the information layer onto the substrate.

In another method used in the present invention with the aim to attain maximum full contact between the photomask and the photosensitive layer the latter is initially applied not onto the photomask but onto a transparent polymer film of a preset thickness. In this case, a thin (0.5-1.5 μm) glue layer

with protective polymer cover is deposited over the back side of said film subsequently used as a spacer. The structure is of the form of a two-sided sticky tape or dry photopolymerizable glue.

The photosensitive film is then tightly vacuum-pressed against the photomask. Thereafter, it is exposed via the photomask (see Fig. 5) followed by assembling the polymer information carrier layers into a single FMC.

Fig. 13 presents a fluorescent microimage of one of said information carrier layers. The quality of said layers differs little from the quality of layers obtained from the same photomasks using the technique of pouring the photosensitive composition on the photomask. The advantage of this method lies in the absence of necessity to use secondary exposure while forming the spacing layer in assembling the FMC my means of photopolymerizable glues.

As mentioned earlier in the Background of the Invention section, in attaining a high-speed data reading and a high signal to noise ratio (SNR) in

3D fluorescent memory devices of vital importance is the generation of a sufficiently strong fluorescent signal from each information layer. The quantum power d _h /dt of the fluorescent signal is defined by the expression:

dN hv = K,N₂V dt dN h v ■ k_βN₂V (1 ) dt where k_fi is a luminophore's fluorescence constant, N₂ is concentration of the luminophore in excited state, and V is the pit volume.

At steady-state excitation, the pit fluorescent radiation power is

dN ^hv = K_XN₂V = φ_eΦ^lS l - e -σ(N₀-N₂ )d⁴ dt proportional to the quantum power of exciting laser radiation absorption:

^^ = k_βN₂'V = <p_βΦⁱS[\ - e-^σ(N°-^{Nι )d}] (2) where φn is the fluorescence quantum yield, and Φ¹ is intensity of the exciting

laser radiation incident on the pit in the i^th layer, S is the pit area, σ is the

cross-section of the luminophore absorption at the laser radiation wavelength,

No is concentration of the luminophore, (N₀-N'₂) is concentration of the luminophore in the ground (nonexcited) state in the i^th layer, and d is the information layer thickness. It follows from the above relationships that to achieve a high-power fluorescence it is requisite to maintain a high concentration of the luminophore both in the ground and excited states. This implies a considerable absorption of laser radiation in each information layer. Additional losses in the excitation intensity occur due to light scattering, while in the case of a disk the factor of deterioration of the laser radiation focusing in the depth of the multilayer system is added as well.

As laser exciting laser radiation penetrates into the multilayer structure, its intensity (Φ) decreases leading to reduced power of the information signal. As

can be seen from equations (1 ) and (2) supra, identical and at the same time powerful signals can be attained in a number of different ways.

First, it can be achieved by varying the intensity of the reading radiation (Φ) as a function of the layer number. This approach is more suitable for card

reading since laser radiation intensity is significantly lower in comparison to bit-by-bit disk reading (Figs. 2 and 3) and the luminophore operates in the linear mode.

Second, it can be achieved by fabricating FMC systems with different values of absorption in different layers. Optimal distribution of the absorption value for reading radiation (in the region 1 to 50%) in fluorescent pits of information layers can be computed and depends on the number of layers, filling factor for each layer and numerical aperture (NA) used for collection of lens fluorescent radiation, etc. As is seen in equation Fabes supra, (2), compensation for attenuation of the exciting light intensity at a constant value of the area of information pits can be attained either through increasing the layer thickness (d) and accordingly the volume of pits or through higher concentration of the luminophore. Thus, would be preferable to use a combination of both methods, because optical resolution deteriorates with information layer thickness while higher concentration for most luminophores leads to degradation of the quantum yield. In the present invention for manufacturing FMC systems, the thickness of the information layer is easily adjusted by the spinner rotation speed, viscosity of the photosensitive composition. The volumetric concentration of the luminophore formed in the photosensitive layer depends on the original concentration of the photosensitive non-fluorescing dye precursors, initiator concentration and its exposure time while forming the i^th information layer.

Referring now to Fig. 6 a qualitative graph of the kinetics of storing the fluorescent photoproduct during the exposure of the photosensitive film for different embodiments, Curve 1 corresponds to a variant where photosensitive components are distributed within a hard polymer matrix with low (0.5-1.0 wt.%) content of the residual solvent. In this case, the fluorescing photoproduct accumulation is smooth and attains saturation with maximum photochemical yield of 80-100%, depending on the type of photochemical reaction. Incomplete photochemical reaction in the solid film can be explained by difficult spatial diffusion of molecules (see, for instance, Fig. 1), participating in the bimolecular reaction (the effect of kinetic halt of the photochemical process).

For higher concentrations of the residual solvent in the same film or for a monomoiecular nature of the photochemical reaction the yield may be as high as 100%. In Fig. 6, Curve 2 is similar to Curve 3 except that the concentration of photosensitive components in the film is three times less for the same layer thickness. Curve 3 is similar to Curve 1 except that the photosensitive layer thickness is three times less than the thickness of the film used in the first case.

Consequently, by proper varying the composition of the photosensitive layer, its thickness or the energy of exposing (recording) radiation at the stage of forming the information layer one can fabricate an FMC with information layers having fluorescing pits with minimum in intensity and equal in size fluorescent signals.

In accordance with the present invention for manufacturing the Read Only Fluorescent Multilayer Optical Information Carrier ROM (FMC), it is possible to use virtually any mono- or bimolecular irreversible photochemical reactions in a solid body leading to generation of photo- and thermostable fluorescing photoproducts from non-fluorescing precursors. The latter requirement stems from the fact that the generated fluorescing photoproduct should not be subject to thermo- or photodestruction during multiple data reading from ROM FMC.

Currently there exist a large number of organic nonfluorescent photosensitive precursors capable of generating a fluorescent substance - organic luminophore - as the main photoproduct of monomoiecular or bimolecular reactions (see A. Zweig. Third SPSE Meeting on Non- Conventional Imaging Systems, Washington, D.C., 1971 , p. 79; G.R. Bird. SPSE Meeting. Washington, D.C., 1971. Preprint Paper Summaries, p. 4; A. Zweig "Photochemical Generation of Stable Fluorescent Compounds", Pure and Applied Chemistry, vol. 33, pp. 389-410 (1973); G.R. Bird, Photogr. Sci. Eng., vol. 17, 261 (1973); G.A. Delzenne. In: Advances in Photochemistry, vol. 11 , N4, Wiley, 1979, p. 1 ; and U.S. Patents NN: 3,869,363; 3,892,642; 3,767,408; 3,475,172; 3,676,139; 3,666,470 et al.). The following compounds are proposed as a photosensitive component: Coumarin derivatives, Rhodamine B lactons, Thioindigoid dyes, Stiibene derivatives, Anthraquinone and Anthracene substituents, photosensitive Phenylanthracene anhydrides, Phenyinaphthalenes, Oxadiazole and Furylchrome derivatives, and other organic compounds.

A monomoiecular photochemical reaction can be exemplified by the photofluorescent system based on a vinyl chloride and vinylidene chloride copolymer with Oxadiazole derivatives of diphenylchloromethyl-1 ,3,4- ozadiazole-type described in U.S. Pat. No. 3,869,363. Under UV illumination this compound is converted to red-fluorescing bis-diphenyi-methylene-2,5- dihydro-1 ,3,4-oxadiazole.

The patent literature is replete with suggestions for absorption photosensitive materials based on bimolecular photochemical reactions, such as free-radical type ones which by the nature of generated photoproduct - absorber - can have a fluorescent response to exposure, i.e. are ready photofluorescent materials. For instance, layers containing xanthene dyes (see U.S. Pat. No 3,767,408) with CBr₄ (Application PCT No WO 98/28740; U.S. Pat. No 6,027,855).

In U.S. Pat. No 5,945,252 a method for photochemical generation of stable fluorescent amines from peri-phenoxy derivatives of polycyclic P-quinones is described.

Non-fluorescing dye precursors can be exemplified by Rhodamine B lactams, coumarins, bases of some oxazine dyes (Nile Blue and others), as well as dyes of various classes having proton-dependent auxochromic groups, among them 9,10-dianilinoanthracene, naphthacenepyridones, pyrazolanthranones, fluorenone and anthrapyhdones.

We used, for example, the following photosensitive compositions for generating a photosensitive layer by bimolecular photochemical reactions between acid photogenerators and nonfluorescent dye precursors. A suitable concentration of a leuco form of a fluorescent dye (component A) is 1-10%, while the concentration of the acid generator (component B) is about 0.5-5% of the polymer weight. The concentration of the polymer (component C) in the solvent (component D) is defined by the need to obtain a high-quality film of certain thickness. Concentrations of components A and B in the polymer matrix are essentially determined by the necessity of obtaining a definite concentration of the died fluorescent form. For varying the spectral and fluorescent properties of the photosensitive composition, special dopants F in concentration of 1-5% of the polymer matrix weight were added to said photosensitive composition. In such a system, the degree of advancement of the photoreaction generating a strongly fluorescing photoproduct can be 80 to 100%.

Examples of component A which may be used include: substituted lactams of Rhodamine B derivatives, 9-o-methylaniiino-3,6-bis-diethylamino- 9-xanthenyl-o-benzoacid lactam or 9-anilino-3,6-bisdiethylamino-9-xanthenyl- o-benzoacid lactam, described in U.S. Pat. No 6,027,855, incorporated herein by reference.

Examples of component B (acid photogenerator) which may be used for photochemical transformation of the non-fluorescing rhodamine B lactams into a strongly fluorescing dye, include commercially available acid photogenerators, such as, onium, ferrocene or diazonium salts. For use in combination with lactams, triarylsuifonic salts, e.g., triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium tetraborate, triphenylsulfonium tetraphenyl borate, triphenylsulfonium tosylate, tetraph nyl, produced by Union Carbide, UCB Chemicals, as preferred. When irradiated by UV light, the above-mentioned acid photogenerators produce strong Brenstead's acids dying ail forms of lactams and lactons of xanthene dyes. In addition, they possess high thermal stability (they are not destroyed at heating to 350°C) and low diffusion path (less than 100 A). The latter is extremely

important in terms of generation of information carrier layers with a long time of "dark" information storing. In view of the extremely low size of fluorescent information pits, long-term storing of information in the described above multilayer fluorescent systems is defined by migration stability of fluorescent dyes in information layers.

This becomes possible only when the time of longitudinal diffusion for the photodied form of the dye and the photoactivated acid generator in the polymer layer and their transverse diffusion in the spacing layer are negligibly low as compared to the required time of information storing. For this reason we prefer lactam compounds (e.g. methylanilino-3,6-bis-diethylamino-9- xanthenyl-o-benzoacid lactam) and acid generator (Union Carbide's Cyracure 6990) with maximum bulky lateral substituents. The polymer was chosen quite hard (polymethylmetacrylate) with a high glass transition temperature (T_g > 100°C). Our testing a 10-layer specimen at higher temperature has demonstrated that a 6-hour exposure in the air at 100°C does not lead to any noticeable

changes in fluorescence intensity and degree of contrast in the reading information pits. In combination with lactons there can be also used nitrobenzoic esters, such as 2-nitrobenzyl tosylate, 2,6-dinitrobenzyl tosylate, 2,4-dinitrobenzyl tosylate, etc, as well as sulfobenzenes: (2-methyibenzyl)phenyl sulfone, (2,4- dimethylbenzyl)phenyl sulfone, bis-(2-methylbenzyl) sulfone, etc. Weak acids (like nitrobenzoic one) dye lactonic forms of xanthene dyes but they do not dye lactams.

As a polymer base (component C) of the photosensitive composition there can be used, for example, polymethylmetacrylate, polybutylmetacrilate, polystyrene, polycarbonates, polyformals, polyacrylates, copolimers thereof, etc. The choice of the polymer matrix is predominantly determined by the solubility and stability in said polymer matrix of the non-fluorescing dye precursors and acid generators, as well as their high transparence in the range of spectral sensitivity of the photosensitive components.

Table 1. Light absorption for typical wavelengths in a 0.5 μm polymer film

containing Rhodamine B lactam with the concentration of 0.15M and a died form of Rhodamine B lactam with the concentration of 0.03M.

Despite the great variety of organic luminophores, the number of dyes possessing high photostability, high quantum radiation yield at high concentrations in the polymer matrix and at the same time characterized by sufficiently high absorption in the radiation range of modern laser (semiconductor) sources, is very limited. The number of compounds capable of generating fluorescent dyes with requisite characteristics under UV illumination is even more restricted. Thus, the rather narrow absorption bands of rhodamine dyes in the range of 530 to 560 nm make them convenient objects for excitation (data reading) by green (532 nm) solid-state lasers. However, they are little suitable for blue (400-420 nm) semiconductor lasers and absolutely unsuitable for red (630-670 nm) semiconductor lasers (Table

1 ).

To resolve the problem of matching the generation wavelengths of laser excitation sources and spectral properties of the luminophore as well as controllable variation of spectral fluorescent properties of the photosensitive layers, in this invention it is proposed to introduce one more component F into the photosensitive composition. This should be a photostable luminophore and, depending on the type of combining said component F with photosensitive component A, it should possess either high (80-100%) or low (5-10%) fluorescence quantum yield.

For instance, the weak absorption of the died form of Rhodamine B lactam in the radiation range of blue semiconductor lasers (Table 1 ) can be adjusted through adding component F characterized by a sufficiently high absorption in this range and simultaneously by a high fluorescence quantum yield. In this case, when the died form of lactam is accumulated in the exposed regions of the photosensitive layer up to 0.02-0.1 M concentration, there occurs almost full switch-off of the component F fluorescence and radiation-free energy transfer of the absorbed quanta onto the died form of Rhodamine B lactam. The latter reradiates it with the quantum yield of 80-90%, while the exposure- free regions fluoresce of the order of magnitude less. The specific feature of said system is the same absorption value for reading laser radiation across the entire information layer.

Among other examples of said controlling spectral fluorescent properties of photosensitive information layers by means of component F are increasing the intensity of the fluorescent signal from fluorescent pits in a preset wavelength range and shifting fluorescent (information carrier) radiation towards a longer wavelength region as compared to the wavelength of the reading radiation. This facilitates the process of their spectral separation on the photoreceiver during reading and allows spectrally selective fluorescent reading from different FMC information layers through using various fluorescent substances as special F additives.

In so doing, it becomes possible to decrease the thickness of spacing layers which in turn permits increasing the total number of FMC information layers, i.e. improving its information capacity. In addition, the reduction of inter-layer gaps facilitates operation of the reading head while the spectral selection of noise exposure from adjacent layers allows improving the contrast of reading information signals.

Whenever the died fluorescent product of photosensitive component A possesses a low fluorescence yield, component F is used such that it has a bathochromic shift of the fluorescence band, high fluorescence quantum yield and low absorption in the range of exciting (reading) laser radiation. In this case, the died product of photosensitive component A absorbs a greater portion of exciting light energy and transmits it in a radiation-free way (via Foerster's mechanism) to radiating component F. To this end, the radiation level of component F should be lower than that of the photoproduct of component A. Fluorescence of died photoproduct A can be virtually completely switched off by luminophore F. The whole system will possess a quantum yield and radiation spectrum typical of luminophore F.

In this invention, it is proposed to use similar reactions for preparing photosensitive compositions comprising identical photosensitive components A and B as well as various dopants F fluorescing in different spectral ranges. In manufacturing FMC using such photosensitive compositions, reading of information carrier compositions is performed via the same radiation source while recording of fluorescent information carrier signals therefrom is carried out in different spectral regions. As an example: 1^st layer with pure Rhodamine B radiates at 580 nm; 2^nd layer with Oxazine 1 as an additive radiates at 670 nm; 3^rd layer with Rhodamine 800 as an additive radiates at 710 nm (see Fig. 7). The use of light filters in front of the photodetector would allow reduction of interlayer crosstalk, decrease in the interlayer distance, increase in the total number of information layers and improved FMC information capacity.

This invention is illustrated by the following examples of actual implementation thereof.

Example 1. The photosensitive composition described in Table 2 was spin-coated onto a photomask with a 100-nm SiO₂ coat. The thickness of the resulting layer was 0.4 μm. The photosensitive layer was exposed via the

photomask with the entire radiation spectrum from a 250-W mercury bulb for 15 seconds. The power density (without filtration of visible and UV radiation) in the specimen plane was of the order of 0.2 W/cm². Fig. 9 shows absorption spectra (1 , 2) and fluorescence spectra (3) for given photosensitive layer prior (1 ) and following (2, 3) UV illumination.

Table 2

The photosensitive layer exposed by UV illumination was applied onto the polycarbonate substrate 0.6 mm thick using liquid photopolymer glue from oligourethanacryl oligomer, a photoinitiator of radical polymerization of the

Irgacure 1700 trade mark (produced by Ciba-Geigy) and a triplet sensitizer fluorenone (see Table 3). This composition has a longer wavelength photosensitivity range (over 410 nm) in comparison with the fluorescent information layer. The photopolymerizable glue was solidified by the same radiation source via a light filter cutting off wavelength radiation below 410 nm. The radiation density in the specimen's plane was 0.14 W/cm². The information layer fixed to the polycarbonate substrate was removed from the photomask and used for measurements. Table 3. Content of the photopolymerizable composition used for transferring information layers onto the substrate and for generating spacing layers in FMC.

¹⁾ used for external protective layers.

The fluorescent image was measured using a lens with NA=0.65 and a CCD camera made by Princeton Instruments Inc. Fluorescence was excited by means of an argon laser (λ=514 nm) focused to a 0.005-cm³ spot. The

light intensity in the specimen's plane was 2 W cm^"2. The CCD camera reading time was 0.08 s. Fig. 10 demonstrates a typical fluorescent image and cross-section profile of one information layer. The photomask was written in the CD standard. The contrast of the image of a single layer varied in the range from 10 to 15. The destructive effect of 514-nm reading radiation on the information system is built up of both direct photodestruction of the died form of Rhodamine B lactam and potential process of photodying under the action of the reading beam. The latter probably is due both to the absorption of the long-wave side of the S₀→S-ι transition and direct T₀→Tι absorption of the

acid generator. Fig. 8 shows fluorescence intensity and image contrast of information pits versus radiation time using a 514-nm argon laser. The measurements were performed on a single-layer information specimen where the information pits are on the order of 1 μm. The light intensity was 2 W/cm². It was shown that the photodestruction quantum yield of the died form of Rhodamine B lactam is less than 10^"7. The invariant nature of the degree of contrast is demonstrative of the fact that essentially photodying does not occur under 514-nm radiation. Possibly, it advances significantly more slowly than the photodestruction of the died form. Example 2. To the photosensitive medium described in Example 1 , 0.3% of Oxazine 1 is added. The submicron film on the glass substrate is produced by spin-coating. Fluorescence excitation of said film in the region of 532 nm results in extremely low radiation in the region of 670 nm (Fig. 11 b, Curve 0) which can be explained by poor absorption of Oxazine 1 in this spectral region (Fig. 11 a, Curve 0). Following UV exposure and accumulation of molecules of the died form of Rhodamine B leucobase (Fig. 11a, Curve 1 ) the intensity of sensitized fluorescence increases 30 times (Fig. 11 b, Curve 1 ).

Example 3. The same as in Example 2 except that Rhodamine 800 was used instead of Oxazine 1. Maximum fluorescence for said composition following illumination was observed at 710 nm.

Example 4. The same as in Example 2 except that the BASF ROT-300 perylene dye was used instead of Oxazine 1. Maximum fluorescence for said composition after illumination was observed at 608 nm.

Example 5. The same as in Example 1 except that 1 ,8-Naphthyiene-1 ,2- benzimidazole in 0.1 M concentration was used instead of Oxazine 1. Absorption of the film at 400 nm was 11 %. When excited in the region of 400 nm, the original film fluoresced at 480 nm. Following exposure by UV radiation and accumulation of molecules of the died form of Rhodamine B leucobase maximum fluorescence for said film shifted to 590 nm. Example 6. The photosensitive coat was made on the photomask as described in Example 1. Only one half of the film was photodied through UV exposure via the photomask. The other half of the film was covered by a dark screen. Thereupon said film was transferred onto the polycarbonate substrate (as in Example 1 ) and dried. Then the substrate with the photosensitive layer was placed in the mixture of hexane-toluene solvents (3:1) for 2 minutes at 20°C. Following this procedure the die in the exposed part was fully kept.

Subsequent exposure of the film by UV radiation (the intensity density was 0.2 W/cm², time of exposure was 15-20 minutes) did not lead to dying in the previously nonilluminated part of the photosensitive layer. The dye earlier induced in the other part remained invariant.

Example 7. Single-layer information films were prepared as described in Example 1 , except that a 0.1 -mm thick polycarbonate film was used instead of the 0.6 mm substrate. Then following the process given in Fig. 5b they were glued together to obtain a 10-layer specimen. Thereafter two independently fabricated 10-layer structures were glued together to build up a 20-layer one. The same photopolymerizable composition as described in Example 1 was used for gluing and forming the spacing layer. To obtain optimal regime of layer-by-layer absorption during reading and the same fluorescent signal intensity throughout all layers, the information carrier layers were made different in thickness. Fig. 12 shows a fluorescent image profile for the 1^st (A), 10^th (B) and 20^th (C) layers. It can be seen that the intensity and degree of contrast of information pits are quite close for all information layers.

Example 8. In this case the photosensitive film was exposed; in said film easily-volatile chlorine-containing solvents like chloroform, dichloroethane and others were used component B. Exposing such a freshly prepared film with a sufficiently high content (3-5wt.%) of residual solvent leads to generation of a photofluorecent product. Identical results can be also obtained by exposing said film in saturated with solvent vapor. The exposed film was desensitized by means of heating at 80-100°C.

Chlorine-containing polymers can combine two functions, namely: they can act as a film-forming component and as an acid generator. Desensitization of such a film however is impracticable. Besides, an additional protection of the exposed layer is required as described earlier. In the above examples we have shown preferred embodiments of the present invention. However, other embodiments differing, for instance, in the choice of material for the substrate, content of the photopolymerizable glue and photosensitive composition, spacing layer thickness, etc, are possible as well. They can complement the above-mentioned list of embodiments rather than restrict the scope of claim to priority of the proposed application for the discovery in compliance with the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method for generation of a fluorescent multilayer read-only information carrier having a multitude of information layers placed between spacing layers. Each of said information layers contains in its volume a host of separated from each other microregions (pits) capable of generating a fluorescent information signal against a non-fluorescing background when affected by exciting (reading) radiation and incorporating the following stages: a) providing a number of information carrier photomasks with CD- or DVD-like data patterns encoded as transparent information pits against the nontransparent background; b) applying one or more photosensitive liquids onto the photomask to form a hard photosensitive film on the surface of said photomask; c) exposing said photosensitive film by activating radiation via the photomask to generate fluorescent microregions (pits) against the non- fluorescing background, said microregions being localized behind the transparent microregions on the photomask; d) transferring the exposed information carrier layer with the fluorescent microregions from the photomask onto the data carrier; and e) forming a fluorescent multilayer information carrier by the consecutive layer-by-layer formation of said information carrier layers with fluorescent pits from different photomasks to build up a single unitary structure.

2. The method according to claim 1 , wherein UV- photopolymerizable glues are used in the transfer step.

3. The method as in claims 2, wherein the radiation solidifying said UV- photopolymerizable glues is photochemically inactive with respect to said information carrier layers.

4. The method as in claims 2 and 3, wherein liquid glues are utilized as UV- photopolymerizable glues.

5. The method as in claims 2 and 3, where dry glues are utilized as UV- photopolymerizable glues.

6. The method as in any of claims 3, 4, and 5, wherein solidified glue layers are used as spacing layers.

7. The method according to claim 6, where said UV- photopolymerizable glues do not dissolve said information carrier layers and in the solid state have their refraction index approximating the refraction index of the latter.

8. The method as in claim 7, wherein said spacing layers are 5 to 100 μm thick.

9. The method according to claim 1 , where said photosensitive layers laminated onto said photomask are 0.1 to 1.0 μm thick, preferably 0.3

to 0.45 μm.

10. The method as in claims 1 and 9, wherein said photosensitive layers absorb from 30 to 70% of said activating radiation.

11. The method as in claims 1 and 9, wherein said photosensitive layers are exposed by said activating radiation in the spectral range below 350 nm.

12. The method as in claims 1 and 9, wherein said fluorescent information microregions (pits) formed in said information carrier layer absorb from 1 to 20% of the exciting (reading) radiation.

13. The method as in claim 12, wherein the amount of absorption by said information carrier pits of said reading (exciting) radiation in each said information carrier layers is adjusted by the thickness of said layer, concentration of the photosensitive components in said photosensitive layer or the energy of exposure thereof while generating said information carrier layer.

14. The method as in claim 1 , wherein said fluorescent information microregions (pits) are generated immediately in the volume of said photosensitive layer.

15. The method as in claims 1 through 14, where said absorbing dopants are added to said spacing layers.

16. The method as in claim 15, where said absorbing dopants are added to additional layers covering said fluorescent multilayer information carrier.

17. The method as in claim 15, wherein Tinuvin is used as said additional dopant.

18. The method as in claim 1 through 17, wherein each said information carrier layer following generation is desensitized by means of wet treatment by a solvent to remove the remaining unreacted photosensitive components from the exposed information carrier layer.

19. The method as in claim 18, wherein said solvent comprises heptane, hexane or a mixture thereof.

20. The photosensitive composition for use in making fluorescent multilayer read only information carrier as recited in claim 1 , comprising: a) at least one or more photosensitive non-fluorescing substance capable of generating a fluorescent photoproduct; b) at least one or more photochemically stable film-forming polymer; c) a solvent consisting of one or more components; d) a dopant capable of changing spectral fluorescent properties of said photosensitive layers.

21. The composition as in claim 20, wherein said non-fluorescent substance is capable of undergoing monomoiecular photochemical reactions to produce a fluorescent photoproduct.

22. The composition as in claim 20, wherein said non-fluorescent substance is capable of undergoing bimolecular photochemical reactions to produce a fluorescent photoproduct.

23. The composition as in claim 22, wherein the reaction between photogenerators of free radicals and non-fluorescing dye precursor is utilized as said bimolecular photochemical reaction.

24. The composition as in claim 23, wherein CBr is used as said photogenerator of free radicals.

25. The composition as in claim 22, wherein the reaction between the acid photogenerator and said non-fluorescing dye precursor is utilized as said bimolecular photochemical reaction.

26. The composition as in any of claims 1 through 25, where said Acid photogenerators are selected from the group of onium, ferrocene or diazonium salts.

27. The composition as in claims 1 through 25, wherein said acid photogenerators are selected from the group of triarylsulfonic salts: triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium tetraborate, triphenylsulfonium tetraphenyl borate, triphenylsulfonium tosylate.

28. The composition as in claims 1 through 25, wherein said acid photogenerators are selected from the group of sulfobenzenes: 2-nitrobenzyl tosylate, 2,6-dinitrobenzyl tosylate, 2,4-dinitrobenzyl tosylate.

29. The composition as in claims 1 through 25, wherein said acid photogenerators are selected from the group of sulfobenzenes: (2- methylbenzyl)phenyl sulfone, (2,4-dimethylbenzyl)phenyl sulfone, bis-(2- methylbenzyl) sulfone.

30. The composition as in claims 1 through 25, wherein said non- fluorescing dye precursors are selected from various classes of compounds having proton-dependent auxochromic substituents: 9,10-dianilinoanthracene, fluorenone, naphthacenepyridones, pyrazolanthranones, anthrapyridones.

31. The composition as in claims 1 through 25, wherein said non- fluorescing dye precursors are selected from the group of substituted lactams of Rhodamine B: 9-o-methylaniiino-3,6-bis-diethylamino-9-xanthenyl-o- benzoacid lactam, 9-anilino-3,6-bisdiethylamino-9-xanthenyl-o-benzoacid lactam.

32. The composition as in claim 20, wherein thermo- and photochemically stable luminophores are utilized as component F.

33. The composition as in claims 20, 32, wherein luminophores ensuring a high-intensity fluorescent signal within the preset spectral range in relation to the reading radiation wavelength are used as said dopant.

34. The fluorescent multilayer information carrier produced according to claims 1 through 20, wherein luminophores radiating in different spectral ranges are utilized as said component F in one or more said information layers.

35. The fluorescent multilayer information carrier claim 34, wherein each said information layers, the same photosensitive components but different components F fluorescing in different spectral ranges are used.

36. The composition as in claim 20, wherein luminophores for said dopant are selected from the group of Oxazine 1 , Rhodamine 800, perylene dye ROT-300.

37. The method for generating the fluorescent multilayer read-only- type information carrier having a multitude of information layers disposed between the spacing layers, each of said information layers carries in its volume a multitude of spaced microregions (pits) capable of generating the fluorescent information signal against the nonfluorescent background when exposed to exciting (reading) radiation, comprising the steps: a) providing a number of information carrier photomasks with CD- or DVD-like data patterns encoded as transparent information pits against the nontransparent background; b) applying one or more liquid photosensitive liquids onto a thin polymer film, said polymer film having a thin layer of thermoglue on its reverse side; c) laminating said polymer film with the photosensitive layer onto the photomask surface; d) exposing said photosensitive film by activating radiation via the photomask to generate fluorescent microregions (pits) against the non- fluorescing background, said microregions being localized behind the transparent microregions on the photomask; e) transferring the exposed information carrier layer with fluorescent microregions using liquid or dry glue from the photomask onto the data carrier; and f) applying dfferenct information carrier layers from different photomasks to form a unitary multilayer structure.

38. The fluorescent multilayer structure formed by the method of any of claims 1 through 36.