ბარბარა კილოსანიძე

The polarization-holographic method gives the possibility to create polarization[1]holographic diffraction elements (PHE) which enables carrying out a complete analysis of the polarization state in real-time and working in a wide spectral range including near infra-red. We suggest an innovative sensor of the polarization state based on such an integral polarization-holographic element. Let us note that currently used sensors and polarimeters are complex and expensive devices and most of them contain mechanically rotating or electronically tunable optical elements, such as kompensators, polarizers, waveplates. In this review the theoretical model, description and characteristics of the suggested polarization state sensor and the examples of its applecation in the tasks of remote sensing, astropolarimetry, spectral ellipsometry and in studying a stressed state in different materials are presented.

Polarization holographic recording and the reconstruction of the field of a nonstationary object wave are considered theoretically. Expressions for the nondiffracted beam, as well as the virtual and real images, formed by a space–time polarization hologram are analyzed. It is shown that, under certain conditions imposed on the isotropic, anisotropic, and gyrotropic responses of a polarization-sensitive medium, one can adequately reconstruct the space structure, time waveform, and polarization characteristics of the field of a nonstationary object in the virtual image.

The model of polarization holography memory in the cylindrical block of polarization sensitive media with use of 90⁰  scheme of adding of operating beams has been described. It is shown experimentally the possibility of obtaining the big volume of recorded and readied information with ultimately low noises and high selectivity of reading. The preliminary estimations show the possibility of receiving the superhigh (up to 1 Terabit) volume of data storage by means of the described system.

The model consideration of photoanisotropy in relaxing polarization-sensitive media on the basis of azo dyes is presented. The dependence of the value of photoanisotropy and time of dark relaxation on the intensity of acting radiation and on the relaxation coefficient is shown.

The results of experimental investigations of photoanisotropy in polarization-sensitive media with dark relaxation on the basis of azodye Dimethyl Yellow is presented. The dependence of the value of photoanisotropy and time of dark relaxation on the intensity of acting radiation and on the relaxation coefficient is shown.

This paper discusses polarization-holographic gratings that make it possible to decompose the light incident on them into an orthogonal basis of plane polarization. It is shown that the functioning of various types of gratings substantially depends on the characteristics of the polarization-sensitive recording medium; in particular, for media with a small gyrotropic reaction, it is impossible to obtain a grating that forms diffracted beams of mutually orthogonal plane polarization. It is proposed to use two gratings recorded with parallel plane-polarized beams so that the beams diffracted by the first grating are plane polarized and their polarization is orthogonal to the polarization of the beams diffracted by the second grating. It is shown that such gratings can be obtained on actual polarization-sensitive materials. The results of experimental stuies are presented.

The results of investigations of kinetics of photoanisotropy induction and relaxation in polarization-sensitive media with dark relaxation are presented. The model consideration of photoanisotropy in polarization-sensitive media with dark relaxation is presented. The conformation-orientation mechanism of the anisotropy induction in these media is considered. The value of “effective anisotropy” is used for the anisotropy description that allows measurements of photoanisotropy to be made in real-time. The time dependence of the value of photoanisotropy and dark relaxation on the acting radiation intensity and relaxation coefficient is shown. The experimental investigations are carried out on materials on the basis of azodye Dimethyl Yellow introduced into different polymer matrices.

The method of object recognition is described by the example of objects of amplitude transparent type. The method is to obtain a photoanisotropic copy of object images on polarization-sensitive material. At consequent illumination of the photoanisotropic copy with a parallel circularly polarized beam of nonactinic light, the transmitted light becomes elliptically polarized. It is shown that the characteristics of the summary polarization ellipse in the Fraunhofer diffraction region uniquely identify the given object. The real-time determination of the characteristics of the summary polarization ellipse is made by means of diffraction gratings of anisotropic profile and by comparison of these characteristics with etalon from the database

We consider the possibility of a complete real-time analysis of the polarization state of light using two types of polarization-holographic grating that decompose the light analyzed into orthogonal circular and orthogonal linear bases. It is shown that it is possible to determine the ellipticity, the direction of rotation, and the azimuth of the polarization ellipse of light by the measurement of the intensity of the diffraction orders by the obtained formulas. The possibility of creating gratings that give an orthogonal linear basis on actual polarization-sensitive materials is shown. A comparison of the experimental results with the theory is given.

The theoretical and experimental investigation of the kinetics of photoanisotropy induction in polarization-sensitive media with significant dark relaxation on the basis of azo dyes in polymer matrices is considered. For improving dynamic characteristics of polarization-sensitive materials, new azo dye N, N-dimethyl-4((4-nitrophenyl)diazenyl)aniline has been specially synthesized, and the kinetics of photoanisotropy induction and relaxation in materials on the basis of this dye has been compared with materials on the basis of Dimethyl Yellow. It is shown that spectral sensitivity of the material with new azo dye is in the range of 470–520 nm, the working range is both in the visible and in the infrared range (from 520 nm at least up to 3400 nm), the maximum meaning of effective anisotropy is 38% (Δn ≈ 0:022), and the time of photoanisotropy inducing and erasing is approximately 18 ms. It is shown that, if we confine ourselves to meanings of effective anisotropy of approximately 1–2% (Δn ≈ 0:007), the time of inducing/ erasing will be of the order of microseconds. The use of such dynamic polarization-sensitive materials gives the possibility of a new direction—dynamic polarization holography to be developed that combines the possibilities of both dynamic and polarization holography and that opens new prospects for applications

The results of investigations of kinetics of photoanisotropy induction and relaxation in polarizationsensitive media with conformation-orientation mechanism of the anisotropy induction having significant dark relaxation are presented. It is shown that such materials can be applied for tasks of dynamic polarization holography. With the purpose of improvement dynamic characteristics of polarization-sensitive materials azodye Nitrodimethyl red (NDMR) is specially synthesized. Materials on the basis of NDMR are used for recording dynamic polarization-holographic gratings with different profile of anisotropy. The results of the investigation of kinetics of diffraction efficiency (DE) of these gratings and the analysis of polarization state of diffracted orders are given. It is shown that time of a cycle of recording/erasing for gratings of some types is of the order of 100 ms at DE = 21%. The theoretical model of dynamic polarization-holographic recording on such materials is presented. Possible applications of the methods of dynamic polarization holography are discussed.

Generalization of the Jones vector for partially polarized radiation carried out by Kakichashvili is given. Partially polarized light is presented as two noncoherent components of mutually orthogonal polarization. The formal operation of amplitude summation of mutually noncoherent components and the symbol of this operation are introduced. The rules of operating with this symbol are determined. The regularity of the Weigert effect is modified for partial polarization of the inducing light. On this basis the modification of the Jones matrix for partially polarized light is made. The rules for the formation of the resulting matrix from the Jones matrices corresponding to the noncoherent components of partially polarized light are determined

Dynamic polarization-holographic gratings with a different profile of anisotropy in the band are presented. Polarization-sensitive recording materials of two types are used: material possessing high dark relaxation and highly reversible material without dark relaxation in which the recorded grating is erased by a circularly polarized beam. For a grating recorded by two orthogonally circularly polarized beams a diffraction efficiency of 20% has been obtained at 3.5 W∕cm2 power density during 1 ms recording/erasing time. An all-optical cross commutator based on the matrix of dynamic reprogrammable polarization-holographic microholograms is considered. The amplification of the weak beam at two-wave mixing in polarization-sensitive materials has been shown, with an obtained amplification coefficient of 4.95

Phenomenon of vector polyphotochromism was observed in some high-efficient polarization-sensitive materials dependent on the radiant exposure when material was illuminated with linearly polarized actinic light. The phenomenon has purely vector nature, since under probing by unpolarized light, the transmission spectra of the irradiated and unirradiated area of the material are practically identical. However, an essential change in the transmission spectrum of the material was observed by placing the irradiated area between crossed polarizers when the orientation of the axis of induced anisotropy was of 45 degrees relative to the axes of the polarizers. The dispersion of photoanisotropy was studied at different exposure values. Kinetic curves of the photoanisotropy were obtained for wavelength of 532 nm and 635 nm of probing beam for different values of exposure (30, 60 and 250 J/cm2 ) with linearly polarized actinic light (457 nm). The dispersion curves of the photoanisotropy were obtained for these values of exposure showing an anomalous behavior for exposures above of 30 J/cm2 . This phenomenon was observed in specially synthesized organic materials based on azo dyes introduced in a polymer matrix. The difference between optical densities was obtained for polarized light with a wavelength of 532 nm and 635 nm at different exposures, which makes the prospect the dynamic polarization spectral filters controlled by light and the spectrally selective dynamic polarization holographic gratings to be created.

The phenomenon of vector photochromism was observed in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. The phenomenon has the purely vector nature because the absorption of the irradiated and unirradiated areas of the material is practically identical when we use unpolarized probing light. However, an essential change in the absorption spectrum was observed under probing the sample by linearly polarized nonactinic light when it passes through an analyzer, and this change depends on the value of radiant exposure. The kinetics of the photoanisotropy induced by linearly polarized actinic light at 457 nm was studied in case of wavelengths of 532 and 635 nm of the probing beam. The noticeable difference in absorbance was observed with increase in radiant exposure from 60 J∕cm2 up to 250 J∕cm2 for the used wavelengths of the probing beam. The experimental results obtained in polarization-sensitive material based on the ammonium salt of the azodye Mordant pure yellow in a gelatin matrix are presented. The dependence of the effective anisotropy on the material thickness has been investigated. The mechanism of the phenomenon is discussed. The observed effect can be used for creating dynamic polarization spectral filters controlled by light and the spectrally selective dynamic polarization holographic gratings

A new method for determining the distribution of birefringence and linear dichroism in optical polymer materials is presented. The method is based on the use of polarizationholographic diffraction grating that forms an orthogonal circular basis in the process of diffraction of probing laser beam on the grating. The intensities ratio of the orders of diffraction on this grating enables the value of birefringence and linear dichroism in the sample to be determined. The distribution of birefringence in the sample is determined by scanning with a circularly polarized beam with a wavelength far from the absorption band of the material. If the scanning is carried out by probing beam with the wavelength near to a maximum of the absorption band of the chromophore then the distribution of linear dichroism can be determined. An appropriate theoretical model of this method is presented. A laboratory setup was created for the proposed method. An optical scheme of the laboratory setup is presented. The results of measurement in polymer films with two-dimensional gradient distribution of birefringence and linear dichroism are discussed.

—Some regularities of formation of a new structural state of the thermoplastic polymers - gradually oriented (stretched) state (GOS) are discussed. Transition into GOS is realized by the graded oriented stretching - by action of inhomogeneous mechanical field on the isotropic linear polymers or by zone stretching that is implemented on a standard tensile-testing machine with using a specially designed zone stretching device (ZSD). Both technical approaches (especially zone stretching method) allows to manage the such quantitative parameters of gradually oriented polymers as a range of change in relative elongation/orientation degree, length of this change and profile (linear, hyperbolic, parabolic, logarithmic, etc.). The possibility of obtaining functionally graded materials (FGMs) by graded orientation method is briefly discussed. Uniaxial graded stretching method should be considered as an effective technological solution to create polymer materials with a predetermined gradient of physical properties.

An innovative real-time imaging Stokes spectropolarimeter is presented. The main unit of the polarimeter is an integral polarization-holographic diffraction element, which enables one to carry out a complete analysis of the eight polarization state in real time. An element is recorded by a special polarization-holographic schema using circularly and linearly polarized beams. It decomposes the incoming light into orthogonal circular and linear basis. The simultaneous CCD intensity measurements of the corresponding points or areas in the diffraction orders and further data reduction through the calibration parameters we get real-time Stokes images of a light source that allows to determine detailed polarization state of a light coming from a point or extended space object in a narrow or a wide spectral range. The operating spectral range of the polarimeter is 500-1600 nm with diffraction efficiency equal to 20% at 532 nm, 16% at 635 nm and 2% at 1550 nm. The theoretical model of relations between measured intensities in different diffraction orders and Stokes parameters, earlier developed by the authors, were used to calibrate the polarimeter. The laboratory tests show that the resulting errors are near of 10-2 . The polarimeter is very compact, light weight and could be installed both on ground-based large or small and airborne telescopes

We present an innovative polarization-holographic imaging Stokes polarimeter based on an integral polarization-holographic diffraction element, which allows accomplishing real time analysis of the polarization state of incoming light. An element decomposes the incoming light into diffraction orders, the intensities of which vary depending on the polarization state of the light source. After the CCD intensity measurements of the corresponding points or areas in the diffraction orders and further data reduction through the calibration parameters, we get the real-time Stokes images of the light source, which allows determining full polarization state of a point or extended space object for different spectral regions. The operating spectral range of the polarimeter is 500-1600 nm with diffraction efficiency equal to 20% at 532 nm, 16% at 635 nm and 2% at 1550 nm. The theoretical model of relations between measured intensities in different diffraction orders and Stokes parameters were used to calibrate the polarimeter. Experimental results show that the resulting errors are better than 10-2 and prove the great potential of such polarimeter for observations of various space objects including spectropolarimetric observations of the solar active formations like the solar spicules and prominences. The polarization-holographic imaging Stokes polarimeter is very compact, light-weight and suitable to be installed both on large or small ground-based and airborne telescopes.

The phenomenon of vector photochromism was observed in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. When radiant exposure exceed certain value specific to each material, a sharp change in the transmission spectrum of the probing linearly polarized nonactinic beam is observed after analyzer. While probing with unpolarized light the transmission spectrum is practically unchanged and does not depend on the magnitude of the radiant exposure. The mechanism of this phenomenon is discussed. The effect is an interference nature and depends on the path difference between the ordinary and extraordinary rays in material with photo-induced anisotropy. It is shown that the kinetics of this effect depends on the photosensitive layer thickness and the concentration of the chromophore.The beams with a wavelength away from the absorption band of the material were used as a probing. It is shown that in this case birefringence has made the main contribution in photoanisotropy. The experiments were carried out for polarization-sensitive materials with varying degrees of components integration, in particular, two synthesized side-chain azopolymers obtained by immobilization of polar azo dyes on polymethylmethacrylate backbone. It is shown that the maximum value of the birefringence Dn = 0.162 achieved in azopolymers with covalently bonded components. In this case a third order of interference of the probing beam is observed.

In this paper we present the test spectropolarimetric observations of the spicules in the Hα and He I D3 multiplet for different high chromospheric altitudes from 5000 km to 7000 km using the innovative Polarization-Holographic Imaging Stokes Polarimeter (PHISP) mounted on the 53-cm coronagraph of the Abastumani Astrophysical Observatory (Georgia). The laboratory tests and first spectropolarimetric observations show that the resulting uncertainties are estimated to be of the order of 10−3 .

In this paper, we present a method of pattern recognition based on obtaining the photoanisotropic copies of object images. Such copies are induced on the dynamic polarization-sensitive material when the amplitude image of the object formed by a spatial light modulator is transilluminated by linearly polarized light with a wavelength actinic for the used material. In this case, the distribution of the intensities over the amplitude image is converted into the distribution of photoanisotropy over the sample of a polarization-sensitive material. In the recognition process, this copy is illuminated by parallel circularly polarized nonactinic light. The distribution of elliptical polarization occurs directly behind the photoanisotropic copy, and it is reduced to a summary ellipse in the Fraunhofer diffraction region. It has been shown that the parameters of this ellipse are related to the characteristics of the object and uniquely identify the initial object. The polarization-holographic diffraction element that we developed enables determining the polarization state of a summary ellipse to obtain all the Stokes parameters in real time. The obtained results were compared with the Stokes parameters of the recognizable object in the database. The method invariance with regard to the position, scale, and rotation of the pattern were investigated. In addition, the resolution and sensitivity of this method were determined. The polarization-sensitive materials used to obtain copies are reversible, with practically an unlimited number of recording–deleting cycles. To obtain a photoanisotropic copy of another object on the same material, the previous copy should be deleted with a pulse of circularly polarized actinic light, and then the next copy can be recorded. A laboratory model of the recognition device and the appropriate software were created, and a theoretical model was developed. Databases were obtained for the images of various objects.

We present an innovative imaging Stokes polarimeter. The main unit of the polarimeter is an integral polarization-holographic diffraction element, which enables the instant complete analysis of the polarization state of light in real time. An element is recorded by a special holographic schema using circularly and linearly polarized beams. As a result, it decomposes an incoming light into orthogonal circular and linear diffraction orders. We then capture diffraction orders using a CCD and transform the measured intensities into the Stokes images through the calibration parameters. The Stokes images are used to determine polarization state of a point or an extended space object in different spectral ranges. The operating spectral range of the polarimeter is 500 to 1600 nm with diffraction efficiency equal to 50% at 532 nm, 30% at 635 nm, and 5% at 1550 nm. The theoretical model of relations between measured intensities in different diffraction orders and Stokes parameters was used to calibrate the polarimeter. The calibration observations of day time sky show that the resulting errors are near of 10−3 order.

An innovative polarization state sensor is presented for the determination of the distribution of polarization state of light reflected from the different objects. Such a sensor based on only one integral polarization-holographic diffraction element developed by us is used for real-time analysis of the polarization state of light. The simultaneous measurement of the intensities of four beams diffracted on the element and the appropriate software enable the complete polarization state of an analyzable light (the four Stokes parameters) to be obtained in real-time. The polarization state of light reflected from the object enables to obtain the physicalchemical characteristics of the object’s surface. An application of the sensor in the tasks of remote sensing and in studying a stressed state in different constructions are presented. Such sensor has many advantages compared to conventional devices of polarization optics: operation in real time; a wide spectral range; they differ by compactness, universality, simplicity, light weight and comparative cheapness.

Number of applications require technology that allows strong, retrieving, and processing a large volume of information. Holographic memory offers high-density data storage with parallel access and high throughput. Several methods exist for data multiplexing based on the fundamental principles of volume hologram selectivity. We recently demonstrated that a polarization encoding of the reference wave looks promising as a wave to increase the storage density. Polarization holography offers a method other than traditional methods of selectivity, such as spatial de-correlation between recorded and reconstruction fields. In this report we present the model of polarization holographic memory in a cylindrical block of polarization sensitive materials with use of 900 scheme of adding operating beams. It is experimentally shown the possibility of obtaining big capacity of recorded and readied information with ultimately low noise and high selectivity of reading. The preliminary estimations show the possibility of receiving the superhigh (up to 1 Terabytes) volume of data storage by means of the described element.

The results of experimental investigations of photoanisotropy in polarization-sensitive media with dark relaxation on the basis of azodye Dimethyl Yellow is presented. The model consideration of photoanisotropy in polarization-sensitive media with dark relaxation is presented. The media with conformation-orientation mechanism of the anisotropy induction is considered. The value of “effective anisotropy” is used for the anisotropy description that allows measurements of photoanisotropy to be made in real-time. The value of photoanisotropy and dark relaxation time dependence on the acting radiation intensity and relaxation coefficient is shown. The time of the order of tens of milliseconds for the achievement of the maximum meaning of anisotropy and the dark relaxation time are obtained.

The results of the investigation of recording of dynamic polarization-holographic gratings are presented. Dynamic polarization-sensitive materials with conformation-orientation mechanism of the induction of anisotropy were used as a recording media. Such media were created on the basis of specially synthesized azodyes introduced into different polymer matrices. Small enough times of induction and relaxation of photoanisotropy (of about hundreds of microseconds) were achieved due to the optimization of the parameters of these media. Gratings with a different profile of anisotropy in a band were obtained when beams of different polarization were used in recording. Diffraction efficiencies of the received gratings were measured and polarization analysis of diffracted orders was made. On some samples the diffraction efficiency up to 20% was achieved at the characteristic time of dynamic work operating of the grating (of less than 1 millisecond) with the use of orthogonal circular polarized beams in the recording of gratings. The possibility of the use of these gratings as optical switches was investigated when actinic radiation of Ar laser (λ = 488 nm) was used for the formation of a grating and as a switched beam the radiation of He-Ne laser (λ = 632.8 nm) was used. It is shown that the characteristic switching time can be much less than 1 microsecond if we limit ourselves to the meanings of diffraction efficiency of the order of 1% that is sufficient for the whole class of tasks and if we use the additional incoherent illumination. The theoretical model of the operation of dynamic polarization-holographic gratings is presented.

In order to increase the level of protection of important documents, securities, industrial products, etc. against counterfates, a new type of protection system has been developed - a polarization-holographic protection system. A laboratory technology has been developed for obtaining protective elements, as well as devices for determining the authenticity of these elements. The proposed protection system uses specially synthesized polarization-sensitive materials and polarization-holographic elements with special properties.

We investigated the polarization-holographic gratings recorded by orthogonal and parallel linearly polarized beams, and analyzed [polarization of beams in various combinations of the gratings. For the recording, we used polarization-sensitive materials based on azodyes introduced in polymer matrices, developed by us. A complete analysis of the light, including the degree of polarization became also feasible with the help of polarization-holographic element based on the different type of polarization-holographic grating.              

The results of theoretical and experimental investigations of the kinetics of photoanisotropy in relaxing polarization sensitive media are presented. The media with the conformation-orientation mechanism of the basis of azodyes introduced into different polymer matrices were investigated. Unlike the media with photophysical mechanism of the induction of anisotropy requiring high intensities of inducing radiation the considered media with photochemical mechanism favorably differ by high sensitivity to polarized light that allows continuous lasers of low power to be used. 

Polarization-Holographic Element on the basis of diffraction gratings with different profile of anisotropy for complete analysis of light, namely definition of all parameters of polarization ellipse is described.

For the creation of permanent memory element, we suggested using stable polarization-sensitive media in which anisotropy grows under the action of actinic polarized light when energetic exposure increases and it retains a long time after the illumination stops. These are media on the basis of azodyes introduced in different polymer matrices, with high sensitivity to polarized light, large values of photoanisotropy and high resolution

With the purpose to increase a level of protection of the important documents, securities, industrial goods, etc. from counterfeiting the polarization-holographic system of protection is developed. The suggested approach is based on new physical principles and allows a level of protection against counterfeiting to be increased. The technology of obtaining protective elements and also a device for the definition of authenticity of these elements has been developed. The suggested system of protection uses specially synthesized polarization-sensitive materials and polarization-holographic elements with special properties. The definition of authenticity is made by means of the analysis of the polarization state of light diffracted on the protective element. The essential advantage of this system is that the copying of polarizationholographic protective element by optical methods is impossible in principle which complicates their counterfeiting.

The polarization-holographic system of protection has been developed. The suggested approach is based on new physical principles, namely on the using of polarization state of light that allows the level of protection of important documents, securities, industrial goods, etc. against counterfeiting to be increased. The system includes polarization-holographic protection elements and a device for the definition of authenticity of these elements. The elements are made on specially synthesized polarization-sensitive materials with certain properties which additionally raise the level of protection. The definition of authenticity is made by means of the analysis of the polarization state of light diffracted on the protective element. The essential advantage of this system is that the copying of the polarization-holographic protective element by optical methods is impossible in principle which complicates their counterfeiting.

The method of object recognition is described by the example of objects of amplitude transparent type. The method is to obtain a photoanisotropic copy of object images on the polarization-sensitive material. At consequent illumination of the photoanisotropic copy with a parallel circularly polarized beam of nonactinic light, the transmitted light becomes elliptically polarized. It is shown that the characteristics of the summary polarization ellipse in the Fraunhofer diffraction region uniquely identify the given object. The real time determination of the characteristics of the summary polarization ellipse is made by means of diffraction gratings of anisotropic profile and by comparison of these characteristics with etalon from database.

We have developed a technology for obtaining polarization-holographic gratings (the gratings have anisotropic profile continuously changing within each spatial period) with different distribution of anisotropy in the grating period, as well as the technology for obtaining polarization-holographic elements based on such gratings. To obtain gratings and elements, special high-performance polarization-sensitive materials developed by us are used. We can present samples of gratings and elements and demonstrate how they work. We have developed the technology of obtaining of polarization-holographic gratings that have anisotropic profile continuously changing within each spatial period and also the technology of reception of polarization-holographic elements on the basis of such gratings. Special highly effective polarization-sensitive materials developed by us are used for obtaining such gratings and elements. We can present samples of gratings and elements and give a demonstration of their work.

შემოთავაზებულია სპექტროპოლარიმეტრიის მეთოდი პოლარიზაციულ-ჰოლოგრაფიული ელემენტის ბაზაზე სინათლის სრული ანალიზისათვის, კერძოდ სტოქსის ოთხივე პარამეტრის განსაზღვრისათვის. ამგვარ ელემენტს უნარი შესწევს იმუშაოს ფართო სპექტრულ დიაპაზონში. ასტროპოლარიმეტრიაში პოლარიზაციულ-ჰოლოგრაფიული ელემენტის გამოყენების შესაძლებლობის დემონსტრირებისათვის ჩვენ ჩავატარეთ მზის გვირგვინში პოლარიზაციის მდგომარეობის სივრცული განაწილების კვლევა მზის სრული დაბნელების დროს 2006 წლის 29 მარტს, პოლარიზაციულ-ჰოლოგრაფიული ელემენტისა და რეგისტრაციის სისტემის გამარტივებული ვარიანტის მეშვეობით საველე პირობებში. შემუშავებული იქნა პორტატიული რეფრაქტორი 10/120 სმ, რომელშიც პირველად იყო გამოყენებული პოლარიზაციულ-ჰოლოგრაფიული ელემენტი. ეს კი საშუალებას იძლეოდა ცირკულარული ან ელიფსური პოლარიზაციის ბრუნვის მიმართულების პრეციზიული განსაზღვრის +1 და -1 დიფრაქციის რიგებში ფორმირებული გამოსახულებების შესაბამის წერტილებში ინტენსიობების შედარებით. გამოკვლეული იქნა არეები ჩრდილოეთ და სამხრეთ პოლუსების მიდამოში.

წარმოდგენილია დინამიური პოლარიზაციულ-ჰოლოგრაფიული მესერების ჩაწერის კვლევის

შედეგები. ჩამწერ არედ გამოყენებული იყო დინამიური პოლარიზაციულად მგრძნობიარე მასალები ანიზოტროპიის ინდუცირების კონფორმაციულ-ორიენტაციული მექანიზმით. ამგვარი არეები შეიქმნა სპეციალური ფიზიკურ-ქიმიური თვისებების მქონე პოლიმერულ მატრიცებში შეყვანილი სპეციალურად სინთეზირებული აზოსაღებარის ბაზაზე. ფოტოანიზოტროპიის ინდუცირების საკმარისად მცირე დრო (დაახლოებით ათეული მიკროწამებისა) მიღწეული იყო ამ არეების პარამეტრების ოპტიმიზაციის საშუალებით. მიღებულია მესერები ანიზოტროპიის სხვადასხვა პროფილით ჩაწერისათვის სხვადასხვა პოლარიზაციის მქონე კონების გამოყენებით. გაზომილი იქნა მესერების დიფრაქციული ეფექტურობა და ჩატარდა დიფრაქციული რიგების პოლარიზაციული ანალიზი. 

ჩვენ მიერ შემოთავაზებულია პოლარიზაციის სიბრტყის ბრუნვის კუთხის პრეციზიული გაზომვის მეთოდი. არსებული მეთოდებისაგან განსხვავებით ამ მეთოდში ბრუნვის კუთხის პრეციზიული გაზომვა ხორციელდება პოლარიზაციულ-ჰოლოგრაფიული მესერის მეშვეობით. ეს კი ოპტიკურად აქტიური ნივთიერების კონცენტრაციის განსაზღვრის საშუალებას იძლევა დროის რეალურ მასშტაბში მაღალი სიზუსტით. თუ წფივად პოლარიზებული მონოქრომატული სინათლის კონა გარკვეული აზიმუტით გადის ოპტიკურად აქტიურ ნივთიერებაში შედეგად მივიღებთ პოლარიზაციის სიბრტყის მობრუნებას (აზიმუტის ცვლილებას) ოპტიკური აქტივობის ხარჯზე. ამის შემდეგ სინათლის კონა ეცემა აღალხარისხიან მეოთხედ ტალღოვან ფირფიტას, რომელიც ორიენირებულია ისე, რომ ოპტიკურად აქტიური მასალის არარსებობის დროს გასული სინათლის კონა წრფივად პოლარიზებულია.

Polarization-holographic element on the basis of diffraction gratings with different profile of anisotropy for complete analysis of light, namely definition of all Stokes parameters of polarization ellipse is described. The polarizationholographic elements have many advantages compared to conventional devices of polarization optics: they make it possible to carry out the polarization analysis and transformation of light in real time; they operate in a wide spectral range without any need of modulation. A single element of the kind is as effective as the whole set of conventional analogues in polarization optics. We investigated the polarization-holographic gratings recorded by linearly polarized beams, and analyzed polarization of diffracted beams. For the recording, we used polarization-sensitive materials based on azodyes introduced in polymer matrices, developed by us. A complete analysis of the light, including the degree of polarization became also feasible with the help of polarization-holographic element based on the different type of polarization-holographic gratings.

The results of investigations of kinetics of photoanisotropy induction and relaxation in polarization-sensitive media with conformation-orientation mechanism of the anisotropy induction having significant dark relaxation are presented. It is shown that such materials can be applied for tasks of dynamic polarization holography. With the purpose of improvement dynamic characteristics of polarization-sensitive materials azodye Nitrodimethyl red (NDMR) is specially synthesized. Materials on the basis of NDMR are used for recording dynamic polarization-holographic gratings with different profile of anisotropy. The results of the investigation of kinetics of diffraction efficiency (DE) of these gratings and the analysis of polarization state of diffracted orders are given. It is shown that time of a cycle of recording/erasing for gratings of some types is of the order of 100 ms at DE = 21 %. The theoretical model of dynamic polarizationholographic recording on such materials is presented. Possible applications of the methods of dynamic polarization holography are discussed.

Integral polarization-holographic element on the basis of the different type of diffraction gratings with different profile of anisotropy for complete analysis of polarization state of light, namely definition of all Stokes parameters is presented. The possibility of obtaining polarization-holographic elements working in wide spectral range 500 – 4200 nm is investigated. The possibility of the creation of a cheap and simple real-time imaging Stokes spectropolarimeter on the basis of such an element is shown

The new method of imaging Stokes spectropolarimetry in real time on the basis of polarization-holographic element is offered. Polarization-holographic element with complicated profile of anisotropy for the real-time complete analysis of polarization state of light (all Stokes parameters) is developed. During diffraction the element decomposes light incoming on them onto orthogonal circular and linear basis. The simultaneous measurement of the intensities in all points of images in diffracted orders by means of CCD matrices and appropriate software allows to determine the spatial distribution of a polarization state in the images of extended objects, and also the dispertion if this distribution.

The phenomenon of energy transfer is considered by means of dynamic polarization holograms. The use of higheffective reversible polarization-sensitive media makes it possible to use beams with low intensities from CW lasers. For amplification of energy transfer, the additional mechanical shift of the medium was used such that the phase shift would be of optimal value π/2. The increase of the intensity of a weak beam up to 300% within the time of tens of milliseconds was obtained. This approach gives the possible to amplify coherent light beams by relatively simple way including the amplification of beams in communication systems

In order to obtain a polarization sensitive materials with improved characteristics, there was conducted intensify interaction between the components of recording media through the interaction between the molecular electrostatic forces. For creating materials there were used various organic dyes capable of photochemical geometric isomerization under the influence of actinic polarized light with a wavelength closed to the maximum of the absorption spectrum of each dye. Various polarization sensitive materials have been synthesized based on the polar water-soluble components. Substantial improvement photoanisotropic characteristics of these materials are revealed due to previously added ionizing functional groups in the chromophoric components. It is shown particular exemplary embodiment of synthesis the materials composed of dyes which communicate with certain polymers via dipole-ionic bonds. The research data of medium properties on their base have been brought up for the consideration. In the same way photoanisotropic materials are created on basis of various polar polymer matrixes which separate macromolecules are capable of establishing dipole-dipole bonds with each other. Thanks to this circumstance a supplementary number of polymer fragments which cannot afford direct connection with dye molecules are also able to get drawing into the photoanisotropy inducting processes. It is displayed the influence of such interactions on material kinetics and value of attainable photoanisotropy. A capability of achievement extremely high values of photoanisotropy is produced on the material samples based on the dyes with expanded number of ionized substituent.

The possibility real time complete analysis of polarization state of light by polarization-holographic elements is considered. The requirements to characteristics of the elements are discussed for different applications. The application of the methods of dynamic polarization holography is discussed.

The Polarization-Holographic Imaging Stokes Spectro-Polarimeter developed by us is proposed to use for the determination of the characteristics of the surface of objects at optical remote sensing. Only one integral polarizationholographic element is used in such a spectropolarimeter as an analyzing detail, which makes real time complete analysis of the polarization state of light (determination of all the four Stokes parameters) possible, as well as the determination of the distribution of the polarization state of light in the image of recognizable object and the dispersion of this distribution, which provides additional information while identifying an object. A theoretical model showing the connection of the Stokes parameters of light reflected from a recognizable object with the characteristics of the material of the reflecting surface of the object has been developed that allows the appropriate correlation connections to be set. Experimentally the possibility of obtaining the distribution of the values of the Stokes parameters is shown for the samples from different materials and of a different geometric form.

Polarization holographic element with complex distribution of anisotropy and gyrotropy is suggested for astropolarimetry by means of real time analysis of the state and degree of polarization (also the dispersion of this state) of light that went into the entrance pupil of the telescope. The element decomposes the light incident on it into the orthogonal circular and linear bases. Simultaneous measurement of the intensities of diffracted beams allows all four Stokes parameters to be determined and the dispersion of this state. The possibility of the creation of suitable higheffective and extremely compact element and its application for detection and characterization of exsoplanets is discussed.

New stable polarization-sensitive materials are developed on the hydrophobic components basis which doesn’t require an additional moisture protection. Bisazodye ortho-tolidinebisazophenol chromophoric component was synthesized which is liposoluble analogue of water-soluble azodye Mordant Pure Yellow M. This bisazodye were used to develop the hydrophobic materials films which can be applied as a protective layer themselves. To increase the thermal stability we have synthesized material by introducing bisazodye into the main-chain of macromolecule of thermally stable polymer. The different types of polarization-holographic gratings with high diffraction efficiency of 30-50% were recorded on the obtained materials by laser beams (441 - 488 nm).

A new polarimetric method of real-time complete analysis of the polarization state of light based on the integral polarization-holographic element is considered. The advantages and applications of this method in optical information processing are discussed.

In polarization holography special polarization‐sensitive materials are used for recording the polarization state of light and in the recording process the corresponding anisotropy of optical parameters is induced in such materials under the action of polarized light. Among the materials with such properties the materials based on solid solutions of organic dyes in polymer matrices, as well as media with chemically covalent bonds between them (side‐chain and main‐chain azopolymers) have the best properties. The stable and dynamic azodye‐containing polarization‐sensitive materials has been developed and investigated by us.

An innovative real-time polarimetric method is presented based on the integral polarization-holographic diffraction element developed by us. This element is suggested to be used for real time analysis of the polarization state of light, to help highlight military equipment in a scene. In the process of diffraction, the element decomposes light incoming on them onto orthogonal circular and linear basis. The simultaneous measurement of the intensities of four diffracted beams by means of photodetectors and the appropriate software enable the polarization state of an analyzable light (all the four Stokes parameters) and its change to be obtained in real time. The element with photodetectors and software is a sensor of the polarization state. Such a sensor allows the point-by-point distribution of the polarization state in the images of objects to be determined. The spectral working range of such an element is 530 – 1600 nm. This sensor is compact, lightweight and relatively cheap, and it can be easily installed on any space and airborne platforms. It has no mechanically moving or electronically controlled elements. The speed of its operation is limited only by computer processing. Such a sensor is proposed to be use for the determination of the characteristics of the surface of objects at optical remote sensing by means of the determination of the distribution of the polarization state of light in the image of recognizable object and the dispersion of this distribution, which provides additional information while identifying an object. The possibility of detection of a useful signal of the predetermined polarization on a background of statistically random noise of an underlying surface is also possible. The application of the sensor is also considered for the nondestructive determination of the distribution of stressed state in different constructions based on the determination of the distribution of the polarization state of light reflected from the object under investigation. The prospect of this sensor application in astropolarymetry both for land and space telescopes is also discussed.

The phenomenon of vector polyphotochromism within a wide spectral range is revealed in organic polarization-sensitive materials when material is illuminated with linearly polarized actinic light. The effect has a purely vector nature, while the transmission spectrum of the exposed material essentially changes in case of observing between crossed polarizers and the change in the spectrum unambiguously depends on the energy exposure. A significant dependence of the kinetic of the vector polyphotochromism induction on the power density of linearly polarized actinic light (445 nm) is shown for probing beam of 635 nm. It is also shown that the kinetics of the effect depends on the degree of integration of the component molecules of the material by the cohesion of both ways the electrostatic forces (by use mineral electrolytes and polyelectrolytes) and the covalent bonds (azopolymers based on different chromophores), as well as on the photosensitive layer thickness and the concentration of the chromophore. The mechanism of the phenomenon is discussed. Considering the fact that the change in the spectral characteristics occurs throughout the full visible range, this effect may be used for creating the spectrally selective dynamic polarization holographic gratings, displays based on new physical principles, and also for creating modulators and dynamic polarization spectral filters controlled by light.

A new real-time nondestructive polarimetric method is suggested for the determination of the stressed state distribution in different objects. Light reflected from the object is polarized in a varying degree, and the distribution of the polarization state in the object image is related to the distribution of stresses in it. Method is based on the obtaining the distribution pattern of the polarization state of light in the object image, which is formed by an objective. The integral polarization-holographic diffraction element developed by us is used for real time complete analysis of the polarization state of light at each point of the image, formed by the element in the diffraction orders. The simultaneous measurement of the intensities in four diffracted beams by means of a matrix of photodetectors and the appropriate software enable the polarization state of an analyzable light and its change to be obtained in real time. The laboratory model is presented. The correlation relations between the polarization state of light reflected from the sample with the distribution of the dosated mechanical stresses is considered. The theoretical model is presented. The experimental results are shown for different samples with one- and two-axis stress distribution. The method is nondestructive, i.e. there is no need to drill holes or openings or sticking transparent photoelastic plates on the object to determine the stresses. This method will enable the distance monitoring and diagnosis of already existing constructions to be carried out. This method will differ by universality, simplicity, high speed and comparative cheapness.

A new method of the objects recognition is suggested based on real-time determining the parameters of the integral polarization ellipse in the Fraunhofer diffraction region, which is formed while illuminating the photoanisotropic copy of the object image by nonactinic circularly polarized light beam.

Phenomenon of vector polyphotochromism was observed in some high-efficient polarization-sensitive materials dependent on the radiant exposure when material was illuminated with linearly polarized actinic light. The phenomenon has purely vector nature.

This paper presents the experiments on photoanisotropic organic media films based on the composition of the azodye and polymer containing different polyelectrolytes. As a part of an experiment to strengthen the cohesion of the matrix macromolecules, we individually added to the test compositions polyelectrolytes with variations of quantity and with the different nature. The kinetic curves of the inducing photoanisotropy in the polarization-sensitive films are shown. The addition of the electrolyte to this type of materials contributes to an early manifestation of vector polyphotochromic effect at low exposures, which in turn is a sign of improved photoanisotropic properties as this effect appears exclusively in high-performance polarization-sensitive materials.

The well-known scalar photochromism phenomenon is a reversible phototransformation of chemical species between two forms having different absorption spectra. It is observed under the action of actinic light regardless of its polarization state. Unlike this in some high-efficient polarization-sensitive azopolymeric materials, we have observed a welldeveloped vector polyphotochromism which appears as a light-induced area with spectral selectivity for the linearly polarized probing beams. A sharp change in the transmission spectrum of the material have been observed when we placed an irradiated area of the sample between crossed polarizers, while the transmission spectrum of the sample remained practically unchanged in case of probing by unpolarized light. The effect has a purely vector nature, while the transmission spectrum of the exposed material essentially changes in case of observing between crossed polarizers and the change in the spectrum unambiguously depends on the energy exposure. A significant dependence of the kinetic of the vector polyphotochromism induction on the power density of linearly polarized actinic light (445 nm) is shown for probing beam of 635 nm. It is also shown that the kinetics of the effect depends on the photosensitive layer thickness and the concentration of the chromophore. The experiments were carried out for two synthesized side-chain azopolymers obtained as immobilized polar azo dyes on polymethylmethacrylate backbone. It is clearly shown a light-controlled spectral selectivity of the sample activated by the various doses of the stimulating radiation.

An innovative real-time imaging Stokes spectropolarimeter is presented. The main unit of the polarimeter is an integral polarization-holographic diffraction element, which enables the complete analysis of the polarization state of light to be carried out in real time. An element is recorded by a special holographic schema using circularly and linearly polarized beams. As a result it decomposes an incoming light into orthogonal circular and linear diffraction orders. Upon simultaneous CCD intensity measurements of the corresponding points or areas in the diffraction orders and further data reduction through the calibration parameters we get real-time Stokes images of a light source. The further reduction of Stokes images allows to determine detailed polarization state of a light coming from a point or extended space object in a narrow or a wide spectral range. The operating spectral range of the polarimeter is 500-1600 nm with diffraction efficiency equal to 20% at 532 nm, 16% at 635 nm and 2% at 1550 nm. The laboratory calibration tests were obtained with a quasi-monochromatic point size depolarized light source which further were circularly or linearly polarized with known polarization parameters and a degree of polarization near to 100%. The theoretical model of relations between measured intensities in different diffraction orders and Stokes parameters, earlier developed by the authors (Kilosanidze B., Kakauridze G. SPIE Proceedings, vol. 8082-126, 2011), were used to calibrate the polarimeter. The laboratory tests show that the resulting errors for single mesure are near of 10-2 or less.

We present an innovative polarization-holographic imaging Stokes polarimeter based on a polarization-holographic diffraction element, which enables the complete real time analysis of the polarization state of the incoming light. An element decomposes the incoming light into diffraction orders, the intensities of which vary depending on the polarization state of the light source. After the CCD intensity measurements of the corresponding points or areas in the diffraction orders, and further data reduction through the calibration parameters, we get the real-time Stokes images of the light source, which allows determining the full polarization state of a point or extended space object in either a narrow or wide spectral range. The operating spectral range of the polarimeter is 500-1600 nm with diffraction efficiency equal to 20% at 532 nm, 16% at 635 nm and 2% at 1550 nm. The theoretical model of the relation between measured intensities in different diffraction orders and Stokes parameters, developed by Kilosanidze & Kakauridze (2007), was used to calibrate the polarimeter. The tests show that the resulting errors are better than 1%. First polarimetric test images were obtained for stars and solar spicules. The polarimeter is compact, lightweight, and could be installed on ground-based, airborne, or space telescopes.

A new method of objects recognition is suggested based on real-time determining parameters of the integral polarization ellipse which is formed in the Fraunhofer diffraction region by the photoanisotropic copy of the object image while such a copy is illuminated with nonactinic circularly polarized light beam.

A new method is presented for determining the distribution of birefringence and linear dichroism in different materials based on the polarization-holographic element when circularly polarized light beam transmitted through the sample diffracts on the element.

A new method of pattern recognition is presented which is based on obtaining photoanisotropic copies on the dynamic polarization sensitive material. The amplitude image of the object is illuminated by a linearly polarized light with a wavelength actinic for this material. In result a photoanisotropic copy of this image is induced on the polarizationsensitive material. In recognition process, a photoanisotropic copy is illuminated by circularly polarized light of a nonactinic wavelength. The distribution of elliptical polarization occurs behind a photoanisotropic copy and reduces to a summary ellipse in the Fraunhofer diffraction region. The parameters of this ellipse are related to the characteristics of the original object and uniquely identify the initial object. The polarization-holographic diffraction element developed by us enables to determine summary ellipse parameters - to obtain all the Stokes parameters in real time and to compare obtained results with recognizable object etalon in database. The method invariance to position, scale and rotation of pattern are investigated. The resolution and sensitivity of this method were also determined. The dynamic polarizationsensitive materials are reversible, with practically unlimited number of recording-deleting cycles. To obtain a photoanisotropic copy of another object on the same material, the previous copy should be deleted with a pulse of circularly polarized actinic light, then a next copy can be recorded. A laboratory model of the recognition device, appropriate software and a theoretical model were created. Database have been obtained by using images of various objects.

The study of the mechanism of the phenomenon of vector polyphotochromism led to the opinion that it has an interference nature. This paper presents the first experimental data on the correspondence of this effect with the manifestation of the photoelasticity of the polymer component of the material. We verified the accordance of the transmission spectra of polarized light on the one hand of a photoactivated polarization-sensitive material and on the other hand under the influence of a mechanical stress. The profiles of the obtained polarization spectra match each other.

An all-optical light beam switching based on the controlled dynamic polarizationholographic gratings is suggested. A switchable beam deflects in the necessary direction at the expense of diffraction on the grating when grating vector is changed

A method for determining the scalar and vector reactions of polarization-sensitive materials is presented based on the polarization hologram recording on these materials and on the analysis of the probing beam polarization by the polarization-holographic element.

The phenomenon of vector polyphotochromism was found earlier in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. This effect was observed at high radiant exposures. In this paper the vector polyphotochromic effect is considered when azimuthally dependent exposure is used. The principal difference in these two approaches is that, in exposure-dependent technique, the transmission spectrum of the material depends on the magnitude of the inducing light exposure and this dependence is non-linear. Therefore, certain tunable spectral profiles of the material are very difficult to be fixed, in particular, in the blue spectral region. In the use of the azimuthally dependent technique, the changes in the transmission spectrum are occurred depending on the polarization azimuth of the inducing light. It is shown that the advantage of this approach is the possibility of inducing this effect at much lower exposures of the exciting radiation and obtaining approximately linear dependence of the spectral characteristics of the material on illumination conditions. It should be noted the material used exhibits photochromic behavior of an unusual nature, which is based not on a slight change in the spectral characteristics of the pigment under the light action, but there are changes in the so-called interference color of the medium as a result of selective quenching the corresponding regions of the transmission spectrum of the given material. The polarizationsensitive materials based on biopolymer matrix and organic azo dyes have been used. The obtained results can be used for creating spectral-selective polarization element with high-speed.

An innovative polarization-holographic imaging sensor is presented for the determination of the distribution of polarization state of light reflected from the different objects. Only one integral polarization-holographic diffraction element developed by us is used for real-time analysis of the polarization state of light. The simultaneous measurement of the intensities of four diffracted beams from the element and the appropriate software enable the complete polarization state of an analyzable light (the four Stokes parameters) to be obtained in real- time. The polarization state of light reflected from the object enables to obtain the physical-chemical characteristics of the object’s surface. The theoretical model and software were developed. The experimental results are shown for different samples. Such sensor has many advantages compared to conventional devices of polarization optics: operation in real time; a wide spectral range; they differ by compactness, universality, simplicity, liht waight and comparative cheapness.

The paper outlines the capabilities of color recording of monochromatic polarized light using the phenomenon of vector polyphotochromism. This effect was revealed within the framework of research and development of organic polarization-sensitive media conducted by us

Polarization-sensitive media based on polymers and functional chromophores have deservedly occupied their niche

among photonic materials that are increasingly contributing to the possibilities of richer light sensing, in the field of

optical communications, information transfer, its storage, display, etc. within a wide range of applications. The media

considered here are represented by multiple highly polar compositions based on functional azo dyes doped in a

compatible biopolymer as a matrix. This paper presents our specific studies on the influence of molecular-structural

factors on the photoanisotropic properties of polarization-sensitive compositions. The illustrative examples show

evidence of the finding of one of the factors that work out the light sensitivity of the materials for multiple times. This

factor was the molecular aggregation of the chromophoric component. Quite accurate comparisons are shown of the

improvement in photoresponsibility of various compositions with the mutual combination of their chromophoric

molecules, in particular as a result of their component dimerization. In the overwhelming majority of azochromophoric

dimers demonstrate greater sensitivity to actinic polarized light rather than their predecessor versions. The paper also

demonstrates an example of going beyond the framework of dimerization towards the further development of the

aggregation of molecules with the formation of azopolymers. The latter turned out to be promising in the case of the

correct implementation of increasing integration of the components of the studied materials.

Keywords: organic polarization-sensitive materials, polymeric photoanisotropic compositions, azobenzene, azo

compounds, light polarization, photoanisotropy, photoresponsible media, molecular-structural factors.