Photopolymer recording media for three-dimensional optical memory for very-large-scale information capacity

FIELD: physics.

SUBSTANCE: invention pertains to organic light sensitive recording media and can be used for making archival three-dimensional holographic optical memory with large scale information capacity. The photopolymer recording medium is described. It consists of solid triplexed polymer films or glass plates and light-sensitive layer between them, including unsaturated compounds, which are capable of ion-radical photopolymerisation; a system providing for photoactivation through radiation in the 400-600nm range and consisting of photochromic compounds and co-initiator. The light sensitive layer contains photochromic compounds with a long mean life of the photo-induced state or thermal irreversible photochromic bonds, and not necessarily, polymer binder, plasticizer and non-polymerisation organic liquid with a large refractive index. There is also proposed usage of such a recording medium in devices for three-dimensional holographic memory of large scale capacity.

EFFECT: design of three dimensional holographic optical memory of large scale information capacity and simplification of the optical device for recoding holograms.

9 cl, 12 tbl, 57 ex, 1 dwg

The technical FIELD

The present invention relates to the field of organic photosensitive recording media and can be used to create an archive of three-dimensional holographic optical memory with ultra-high information capacity, which is currently very topical, especially in connection with the development of modern high-capacity database for telecommunication systems, communication and space technology. The possibility of establishing such an optical memory based on detection of the so-called deep holograms, in particular, in the large photopolymerizable recording medium, due to the photoinduced changes in the refractive index resulting from changes in the density of the substance. Holograms are created by irradiating the photosensitive layer of the recording medium suitable laser radiation. The degree of polymerization of the layer depends on the density of the intensity of the activating radiation in the recording environment. The resulting image represents the set of lines of different intensity can be written in the form of changes in the density of the polymer. The resulting polymer having a refractive index different from the refractive index of the original monomer, will be dependent on the intensity of the activating radiation CoE is eficienta of refraction in different parts of the photosensitive layer. These differences in the recovery phase of the light wave to form the reconstructed image. Check deep holograms is achieved by photobleaching light-sensitive components of the environment in the process of registration of the hologram and, therefore, penetration of laser radiation into the recording environment. Record deep holograms in a thick layer causes a high angular selectivity of registration of holograms and restore the image and, as a consequence, it verbalise information capacity.

The LEVEL of TECHNOLOGY

Known photopolymerized environment, consisting of a monomer-oligomer compositions and photoinitiator systems, which used photoassociation dyes and coinitiator (L. Carretero, S. Blaya, R. Mallavia, et al. // Appl. Opt., 1998, V.37, P.4496).

The drawback of such environments is the fact that to obtain phase holograms in them requires additional post-exposure light and heat treatment, which complicates their use in devices archival optical memory.

Closest to the claimed photopolymerizable recording environments are environments containing photochromic spiropyran, which are intended for use in devices stereophotography to obtain three-dimensional polymer of interest (U.S. patent No. 5230986, IPC G03A 007/028. They contain olefin-unsaturated compounds polymerizable with free radicals generated fotoinitsiatora system, consisting of a donor coinitiator and photochromic compounds from the class of iodine-containing indolinone of benzoporphyrin of the following type:

Painted merolanna form of these compounds is a sensitizer of radical generation. It can be obtained in two ways. One of them is the exposure photopolymerizable environment UV light absorbed by the source spiranovic form. Photopolymerization is carried out visible radiation absorbed merocyanine form of the photochromic compounds. The second way of obtaining merocyanine form is heated photopolymerizable environment, which occurs painted photoinduced form of spiropyran. Obtained by thermal merolanna form, absorbing visible radiation, also provides photogeneration free radicals, leading radical polymerization of olefinic unsaturated monomers. Such photopolymerizing recording medium spontaneously desensitized after turning off the UV light or a cooling layer.

The lack of such photopolymerizable recording media is that they use isawanya leads to the necessity of application in the process of recording holograms visible laser radiation an additional source of light or heat energy, what complicates the design of the device, providing three-dimensional images. Another disadvantage is the fact that constant UV illumination or heating environment maintains a constant concentration merocyanine form and, thereby, prevents the penetration of light into the depth of the recording medium. This eliminates the possibility of registering deep holograms and, therefore, reduces the angular sensitivity of the environment and its information capacity. In addition, heating of the recording medium leads to increased thermal distortion of the interference pattern and, therefore, reduces the resolution. In addition, these environments are liquid, which necessitates the use of long exposure light processing photosensitive layer after the registration of holograms. This leads to unnecessary increase in energy costs and the time of formation of the optical memory in such environments.

The above-mentioned disadvantages due to the fact that in the photopolymerizable recording media as photosensitizers were used photochromic compounds with insufficient lifetime of the photoinduced form. In addition, in such an environment there is no polymer binder or components that contribute to the photopolymerization of the environment in the process Zap the si holograms.

DISCLOSURE of INVENTIONS

The purpose of this invention is to increase the angular sensitivity photopolymerizable recording medium for recording holograms and restore images by recording deep holograms in the thick photosensitive layer, which enables the creation of three-dimensional holographic optical memory ultra-high information capacity, as well as the simplification of the optical recording holograms.

This goal is achieved by the fact that these photopolymerizing recording medium (photopolymerizing composition) contains:

as photosensitizers:

any photochromic compounds with a large lifetime of the photoinduced form, in particular:

- benzothiazolinone spiropyran (I):

derivatives phenoxyacetophenone (II):

Table II
The structure and spectral properties of photochromic derivatives of phenoxyacetophenone (KHF is no) in the photopolymerizable composition
Connection	Structure	The spectral characteristics of the photoinduced form, λmaxnm	The reaction rate constant for thermal discoloration of the photoinduced form, k×108with-1
KHF is no 1		453 480	1,0
KHF is no 2		447 478	1,1

any thermally irreversible photochromic compounds, in particular:

- dietrelated (III)

Table III
The structure and spectral properties of photochromic digitalisation (DGA) in the photopolymerizable composition
Connection	Structure	The spectral characteristics of the photoinduced form, λmaxnm
DGA 1		510
DGA 2		520
DGE 4		420 560 600

- fulginiti (IV):

Table IV
The structure and spectral properties of photochromic polymide (fwz) in photopolymerizable songs
Connection	Structure	The spectral characteristics of the photoinduced form, λmaxnm
Fwz 1		520

as polyarizatsionnogo(s) connection(s):

- α,ωbis(methacryloyloxy-ethylenebisacrylamide) ethylenoxide (ACM-);

- triacrylate of trimethylolpropane (TATE);

- bisphenol-A-bis(glycidylmethacrylate) (BigMa);

- N-vinyl pyrrolidone (VP);

- trimethacrylate glycerol (TMG);

as the polymer binder:

- polymeric compound, in particular:

- poly (methyl methacrylate) (PMMA);

- polystyrene (PS);

as coinitiators, i.e. radiculopathy compounds, in particular:

- dimethylethanolamine (DMEA);

- triethanolamine (tea);

2,2-dimethoxy-2-phenylacetophenone dimethylbenzylamine (DMBC) (Irgacure 651);

as depolymerization organic liquid with a high refractive index, in particular:

- Brabanthal (BB, n=1,588);

- chlorobenzene (CB, n=1,522);

as the plasticizer, in particular:

- dibutyl phthalate (DBP), in the following ratio of components (wt.%):

The novelty of the claimed photopolymerizable recording media is the use as photosensitizers, providing for the registration of holograms to laser radiation of the visible spectral range, photochromic compounds with a long lifetime of the photoinduced coloured shapes or thermally irreversible photochromic compounds at a certain ratio of components, namely: photochromic compounds, coinitiators, polimerizatsionnyh compounds, and optional polymeric binder, plasticizer and depolymerization liquid with a high refractive index. In contrast to the above-mentioned prototype, the use of such photosensitizers leads to eliminating the need for constant use of the source of UV radiation or heating device in addition to the laser that emits in the visible range. At the same time sufficiently prior to recording of holograms to irradiate photopolymerizable recording medium short-term non-coherent UV radiation. Desensitization environment after the registration of holograms by brief exposure to incoherent visible radiation absorbed by photoinduced form of the photochromic compounds. As a result of this reduced cost recording device and increases the resolution of the recording medium. Another hallmark is the ability to fototerapia metaconstitutional layer to the desired value in the process of photoinduced get sensitizer due to the introduction, as coinitiator, the composition of the recording environment photoinitiator providing photopolymerization polyarizatsionnogo(s) connection(s) under the action of UV radiation, in particular 2-dimethoxy-2-phenylacetophenone of dimethylbenzylamine (Irgacure 651).

Study and analysis of known scientific-technical and patent literature showed that the full set of features that characterize these technical solutions that were not previously known, i.e. the proposed solutions meet the criterion of "novelty".

The invention is illustrated further by means of examples and with reference to the drawing, which shows the angular dependence of the diffraction efficiency (DE) of the diffraction gratings at the intensity of radiation of an argon laser 5.5 mW/cm².

INFORMATION CONFIRMING the POSSIBILITY of carrying out the INVENTION

Example 1

Sample photopolymerizable recording medium was prepared in the following way: 1) separately preparing a solution of a solid photochromic compounds KHF is no 1 in N-vinyl pyrrolidone (VP); 2) in the resulting solution was added a mixture of polimerizatsionnyh compounds (ACM-2 and TTMT), as well as coinitiator DMAA; 3) the resulting solution was thoroughly stirred; 4) mixed solution was evacuated for 20 min to remove air bubbles from the solution; 5) vakuumirovaniya solution was applied is as Mylar film with a dividing strip of a specified thickness and covered the second Mylar film. The result has been triplex material.

The weight percent of components of the recording environment is presented in the attached table 1 (sample 1).

For evaluation of the photoinduced change of the refractive index fotopolimerizado layer that defines the registration phase holograms, used the Refractometer CRF-22 (Russia). On the surface of the measuring prism of the Refractometer glass rod put a few drops of the sample and gently closed the head of the instrument. Measured the refractive index of the initial solution. Then located between the prism and the photosensitive layer was irradiated with UV light lamp DRSH-250 through the filter UFS-6, emitting radiation with λ=366 nm for 1 min to transfer the photochromic compound from the original colorless in photoinduced painted form. Measured the refractive index of the layer a second time. After this colored solution was irradiated with visible light with λ>400 nm from the illuminator OI-18 for 5 minutes and Then measured the refractive index for the third time. The efficiency of the photopolymerization layer under the action of visible radiation was estimated from the difference in refractive index after exposure of the layer to UV light and visible radiation (Δn=n^view-n^UV).

For this sample, the magnitude of the photoinduced treason the Oia refractive index was Δ n=0,0020 (table 1, sample 1), which proves the possibility of registration of phase holograms in this sample photopolymerizable recording environment.

Example 2

In the manner specified in example 1, was prepared a sample with the same composition, except for coinitiator and mass content of the component (table 1, sample 2).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 1 (sample 1), the data indicate the possibility of recording phase holograms on the prepared sample.

Example 3

In the manner specified in example 1, was prepared a sample with the same composition, in which instead of N-vinylpyrrolidone (VP) was used brobinson (BB). The composition and the weight percent of components are presented in table 1 (sample 3).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 1 (sample 3), the data indicate the possibility of recording phase holograms on the prepared sample.

Example 4

In the manner specified in example 1, was prepared a sample with the same composition, in which instead of N-vinylpyrrolidone (VP) was used chlorobenzene (CB). The composition and the weight percent of the components are presented in ablaze 1 (sample 4).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 1 (sample 4), the data indicate the possibility of recording phase holograms on the prepared sample.

Examples 5-7

In the manner specified in example 1 was prepared photopolymerized layers with the same photochromic compound, in which, as an additional coinitiator was introduced UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced into the solution of the EAP in the first stage of sample preparation. The specific composition and the weight percent of components in the samples are presented in table 2 (samples 5-7).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 2, data which indicate the possibility of fototerapia layer under the action of UV radiation used to obtain photoinduced photosensitizer, sensitive to visible radiation, as well as recording phase holograms in the prepared samples under the action of La the cluster radiation of the visible range. The degree of fototerapia was estimated by the difference between the refractive indices of the layer after UV irradiation, and the original sample (Δn=n^UV-n^ex).

Examples 8-21

In the manner specified in example 1 was prepared photopolymerized layers with photochromic compound KHF is no 2, which as one of coinitiators included UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced in the EAP in the first stage of sample preparation. The specific composition and the weight percent of components in the samples are presented in table 3 (examples 8-21).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 6, also shown in table 3, the data which indicate the possibility of fototerapia layer under the action of UV radiation used to obtain photoinduced photosensitizer, sensitive to visible radiation, as well as recording phase holograms in the prepared samples.

Examples 22-24

In the manner specified in example 1 was prepared photopolymerized layers with photochromic compound KHF is no 2, which as the od of the CSOs from coinitiators included UV photoinitiator DMBC, providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced in the EAP in the first stage of sample preparation. In addition, the photopolymerizable composition of the media was part of a polymeric binder, which was used PMMA. This introduced an additional step of sample preparation, namely the dissolution of PMMA in chloroform. This solution was added to a solution of photochromic compounds and DMBC in the EAP. The chloroform was removed from the photosensitive composition in the process of degassing the samples. The specific composition and the weight percent of components in the samples are presented in table 4 (examples 22-24).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 4, the data which indicate the possibility of fototerapia layer under the action of UV radiation used to obtain photoinduced photosensitizer, sensitive to visible radiation, as well as recording phase holograms in the prepared samples.

Examples 25 and 26

In the manner specified in example 1 was prepared samples photopolymerizable based environments photochromic is soedineniya BTSP 1, which have introduced or N-vinyl pyrrolidone (VP), or brobinson (BB). The composition and the weight percent of components are presented in table 5 (examples 25 and 26).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also presented in the same table, the data indicate the possibility of recording phase holograms in the prepared samples.

Examples 27-45

In the manner specified in example 1 was prepared photopolymerized layers of photochromic compounds BTSP, which as one of coinitiators introduced UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced in the EAP in the first stage of sample preparation. The specific composition and the weight percent of components in the samples are presented in table 6 (examples 27-45).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 6, also shown in table 6, the data which indicate the possibility of fototerapia layer under the action of UV radiation used to obtain photoinduced photo is of sensibilizatora, sensitive to visible radiation, as well as recording phase holograms in the prepared samples.

Examples 46-48

In the manner specified in example 1 was prepared photopolymerized layers with photochromic compound BTSP 3, which as one of coinitiators included UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced in the EAP in the first stage of sample preparation. In addition, the photopolymerizable composition of the media used polymer binder, namely PMMA. This introduced an additional step of sample preparation, namely the dissolution of PMMA in chloroform. This solution was added to a solution of photochromic compounds BTSP 3 and coinitiator DMBC in the EAP. The chloroform was removed from the photosensitive composition in the process of degassing the samples. Along with the PMMA was used plasticizer DBP entered in the same solvent. The specific composition and the weight percent of components in the samples are presented in table 7 (examples 46-48).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 1 are also shown in table 7, data is e which indicate the possibility of fototerapia layer under the action of UV radiation, used to obtain photoinduced photosensitizer, sensitive to visible radiation, as well as recording phase holograms in the prepared samples.

Examples 49 and 50

In the manner specified in example 1 was prepared photopolymerized layers with photochromic compound BTSP 1, which as one of coinitiators included UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced in the EAP in the first stage of sample preparation. In addition, the photopolymerizable composition of the media used polymer binder, namely PS. This introduced an additional step of sample preparation, namely the dissolution of PS in chloroform. This solution was added to a solution of photochromic compounds BTSP 1 and coinitiator DMBC in the EAP. The chloroform was removed from the photosensitive composition in the process of degassing the samples. Along with the PS, was used plasticizer DBP entered in the same solvent. The specific composition and the weight percent of components in the samples are presented in table 7 (examples 49 and 50).

The results of measurements of the photoinduced change of the refractive index, measured p is the method described in example 1 are also shown in table 7, the data which indicate the possibility of fototerapia layer under the action of UV radiation used to obtain photoinduced photosensitizer, sensitive to visible radiation, as well as recording phase holograms in the prepared samples.

Examples 51-57

In the manner specified in example 1 was prepared photopolymerized layers with the photochromic compounds of the and fwz, compounds in which one of coinitiators contained and did not contain UV photoinitiator DMBC providing vodootvedenie layer under the action of non-coherent UV radiation used to obtain photoinduced forms of photochromic compounds. Because DMBC is a solid, it was introduced into the solution of the EAP in the first stage of sample preparation. The specific composition and the weight percent of components in the samples are presented in table 8 (samples 51-57).

The results of measurements of the photoinduced change of the refractive index, measured according to the method described in example 6, also shown in table 8, the data which indicate the possibility of fototerapia layer in the presence of DBK under the action of UV radiation used to obtain photoinduced photosensitizer, sensitive to visible) is to obtain, as well as recording phase holograms in the prepared samples.

Example 58

Sample photopolymerizable recording medium prepared by the method described in example 23 was used for recording holograms for the purpose of measuring the angular sensitivity of the holographic recording medium, defining its information capacity. For this photopolymerized layer was sandwiched between two Mylar films separated by a polymeric spacer thickness of 0.5 mm, the Central part of which has been cut and filled photopolymerizable composition.

Before recording the hologram pattern of the recording medium was irradiated with incoherent ultraviolet light lamp DRSH-250 through the filter UFS-6 transmissive with λ=366 nm for 1 min While the sample was acquired color. Holographic gratings were recorded in the scheme with symmetric beams separated from the beam of an argon (Ar) laser, emitting at a wavelength of λ=488 nm with an intensity of 5.5 mW/cm². After registration of the hologram, the sample was illuminated by visible light illuminator OI-18 to complete bleaching of the sample. For recovery of the used radiation of helium-neon (HeNe) laser, emitting coherent light with a wavelength of λ=633 nm. Diffraction of radiation were recorded in real time using a sensor, RA is laid at the Brewster angle. The angular dependence was determined when the angle of inclination of the recording and restorative laser beams and consistent with prior irradiation of the sample with UV and visible light for each of the recorded hologram. The obtained dependence shown in the drawing, which shows a high angular sensitivity of the prepared sample, providing the use of this recording medium to create a three-dimensional optical memory with high information capacity.

Example 59

Sample photopolymerizable recording medium manufactured by the method described in example 58, was different in that for the manufacture of laminated material instead of the Mylar film was used glass plates.

Registration of holograms with a positive result were carried out by the method described in example 58.

1. Photopolymerizable recording medium consisting of a solid triplexing polymer films or glass plates and located between the light-sensitive layer comprising at least one replaced Susanne connection, capable of ion-radical photopolymerization, a system for providing photo-activation radiation in the spectral range of 400-600 nm and consisting of at least one photochromic compound and at least one coinitiator, characterized in that the photosensitive layer contains a photochromic compound with a large lifetime of the photoinduced form or thermally irreversible photochromic compound and, optionally, a polymeric binder, a plasticizer and depolymerization organic liquid with a higher refractive index in the following ratio, wt.%:

2. Photopolymerizable medium according to claim 1, characterized in that the photochromic compound with a large lifetime of the photoinduced form, which is a sensitizer selected from the group benzothiazolinone of spiropyranes and phenoxypropionic quinones.

3. Rotopol merseyway medium according to claim 1, characterized in that thermally irreversible photochromic compound, which is a sensitizer selected from the group of classes of digitalisation and polymides.

4. Photopolymerizable medium according to claim 1, characterized in that one of coinitiator is a UV photoinitiator, for example 2,2-dimethoxy-2-phenylacetophenone dimethylbenzylamine (DMBC) (Irgacure 651).

5. Photopolymerizable medium according to claim 1, characterized in that the unsaturated polimerizacionnye compound is an unsaturated acrylic oligomer selected from the group consisting of α,ωbis(methacryloyloxy-ethylenebisacrylamide)ethylenoxide (ACM-2); triacrylate of trimethylolpropane (TATE); bisphenol-A-bis(glycidylmethacrylate) (BigMa); N-vinylpyrrolidone (VP); trimethacrylate glycerol (TMG).

6. Photopolymerizable medium according to claim 1, wherein the polymer binder is a poly (methyl methacrylate).

7. Photopolymerizable medium according to claim 1, characterized in that depolymerization organic liquid with a higher refractive index is brobinson (BB).

8. Photopolymerizable medium according to claim 1, characterized in that the plasticizer is a dibutyl phthalate (DBP).

9. Application photopolymerizable recording medium according to claim 1 in a device of the three-dimensional hologram the practical memory extra large capacity.