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Aqueous dispersed media and films based on edible or succinate chitosan with single-walled carbon nanotubes (SWCNTs) were manufactured. Infrared spectroscopy and Raman spectroscopy were used to study the structural changes associated with formation of intermolecular junctions between chitosan and SWCNT. Nonlinear optical characteristics of liquid samples exposed to pulsed laser radiation of nanosecond duration were determined experimentally and calculated theoretically. The composition of the medium based on succinate chitosan and SWCNT providing the largest nonlinear absorption coefficient (902 cm/GW) was determined. The sample with this composition had lower threshold radiation intensity (2.7 MW/cm2), at which nonlinear effects are generated in the medium and liquid-to-solid transition occurs. The results obtained in this work are useful for laser-based production of three-dimensional cellular and tissue-engineered structures used in cardiovascular surgery.

The layers (thickness 0.3-100 μm) of composite nanomaterials in the matrix of collagen (CG) and filler of single-walled carbon nanotubes (SWCNT) are studied. The layers were prepared by applying an aqueous dispersion of CG/SWCNT (~1 wt.% CG, 0.1 wt.% SWCNT, remaining water) on the substrates by silk-screening and evaporation of the liquid part under normal conditions or under the action of laser radiation (LR). It is established that the density ρ and the specifice conductivity σ of the layers change under the action of LR. It is predicted that the obtained values of ρ≈1.4÷1.9 g/cm3 and σ ~10-1÷102 S/m are acceptable for the use of CG/SWCNT layers in medical applications.

The change in the dimensions of the aggregates of the laser solders components during their heating and subsequent denaturation has been investigated. It has been revealed that only the bovine serum albumin aggregates with a hydrodynamic radius of 4.1 ± 0.7 nm are subject to denaturation, and the aggregates of multiwalled carbon nanotubes do not affect denaturation.

The results of biostructures formation based on carbon nano frame in a protein matrix are presented. The binding mechanism of single-walled carbon nanotubes under the influence of laser radiation is described. The energy change during the formation of the nano frame covalent bonds reaches - 7.36 eV/atom. Experiments on growing bone and cartilage tissue cells on samples were conducted.

This article presents the studies results for nonlinear optical characteristics of protein aqueous dispersions (bovine serum albumin and bovine collagen) with single-walled carbon nanotubes (SWCNTs). These characteristics were obtained using Z-scan experiments and fixed sample location experiments with a fixed position of the sample. Calculations were made using a method based on the radiation transfer equation.

The conductivity of layers (thickness ~ 0.5-20 μm) of composite nanomaterials consisting of bovine serum albumin (BSA) with single-walled carbon nanotubes (SWCNTs) has been studied. The BSA/SWCNT composite nanomaterial was prepared according to a route map, some steps of which are: the preparation of an aqueous dispersion based on BSA and SWCNT; preparation of substrates; deposition of BSA/SWCNT dispersion on substrates; application of water paste from SWCNT on substrates; irradiation of layers by lasers when they were in a liquid state; drying of samples; carrying out electrical and temperature measurements. Half of the layer was covered with a light-tight hollow box and the other half of the layer was laser irradiated. The laser irradiation of the layer was carried out for about 20 sec, at which time the layers completely became dry, while the other half of the layer remained in liquid. Conductivity was increased (70 ÷ 650) % by laser irradiation of the layers when they were in the liquid state. Maximum values of specific conductivity for BSA/SWCNT-1 S/m layers, and for layers SWCNT - 70 kS/m. The investigated electrically conductive layers of 99 wt.% BSA/0.3 wt.% SWCNT are promising for medical practice.

Laser radiation limiters can be made on the basis of working substances, which have strong nonlinear effects after reaching a certain critical value (threshold limiting). Thus, it becomes possible to obtain a high transmission for a safe beam and a sharply reduced transmission for a hazardous beam. To determine the nonlinear and linear optical properties of these materials there were carried out comprehensive spectroscopic studies, experiments by Z-scan methods with an open aperture and a fixed location of the limiter. Working substances was developed which is suspension of conjugates J-type phthalocyanine dimers Zn or Mg with single-walled carbon nanotubes (SWCNTs) in water. Created conjugates can be used not only for protecting eyes and light-sensitivity elements, but for forming three-dimensional tissueengineered structures. Using conjugates J-type phthalocyanine dimers Zn and Mg with SWCNTs will increase the optical absorption in the wavelength range of laser processing by reducing the thermal effect on other substances in the composition of this structure. The Nd:YAG laser was used as the laser radiation source for generating pulses of 16 ns duration at a wavelength of 532 nm with the linearly polarized laser beam in the horizontal plane and a shape of Gaussian type. The threshold of limiting, linear and nonlinear absorption coefficients were determined by output characteristic, that was obtained by fixed location of the limiter. Created working substances have values of the following order: linear absorption coefficient ~ 3 cm-1 for layer of 0.2 cm thickness, low limiting threshold ~ 1 MW·cm-2 and high value of the nonlinear absorption coefficient ~ 550 cm GW-1 . Knowing the nonlinear optical parameters, Z-scan data with an open aperture can be calculated for comparison with experimental data.

Some medical applications of composite nanomaterials containing carbon nanotubes are described. Particular applications are bone and cartilage tissue implants, biological solders for laser welding, artificial muscles, and highly conductive layers for electrodes of medical devices (defibrillators, cardiographs, encephalographs, etc.). Additionally, safety of composite nanomaterials with carbon nanotubes is discussed.

The nonlinear optical properties of dispersed carbon nanotube-based (CNT-based) media (dispersions) and solutions of polymethine dye PD-7098 and dicyanomethylenepyran dye DCM-627 have been studied. Values of the threshold intensity for nonlinear processes and nonlinear absorption coefficient were calculated. All CNT-based dispersions displayed a threshold effect, while in dyes no threshold effect was found.

The conductivity of layers (thickness 0.5 ÷ 50 μm) of composite nanomaterials consisting of bovine serum albumin (BSA) with single-walled carbon nanotubes (SWCNTs) has been studied. The aqueous dispersion of BSA / SWCNT was deposited on different substrates using the silk screening method. Conductivity was increased (30 ÷ 700) % by laser irradiation of the layers when they were in the liquid state. The investigated layers are promising for use in medical practice.

Increase the weld strength is main directions of development of laser welding technology. Laser solders are used to increase tensile strength of welds and reduce of tissue temperature necrosis. Soldering components interaction effect the solder tensile strength characteristics of laser welds. Tensile strengths for welds obtained using of solder various concentration BSA and SWCNT was measured. Dimensions laser solder aggregates were measured. The dependence between the dimensions of the aggregates of laser solder and the tensile strength of the weld has been revealed.

The results of experimental creation of nanocomposites using femtosecond laser are presented. We have theoretically proved the formation of a carbon nanotube frame in a protein matrix during laser structuring of single-walled carbon nanotubes. We have selected the technological parameters of synthesis of nanocomposites, which provide the proliferation of living cells.

This paper presents the composite biostructures created by laser structuring of the single-walled carbon nanotubes (SWCNTs) in an albumin matrix. Under the exposure of femtosecond laser radiation, the heating of the albumin aqueous solution causes liquid water to evaporate. As a result, we obtained a solid-state composite in the bulk or film form. Using the molecular dynamic method, we showed the formation of a framework from SWCNTs by the example of splicing of the open end of one nanotube with the defect region of another nanotube under the action of the laser heating. Laser heating of SWCNTs up to a temperature of 80°C to 100°C causes the C ? C bond formation. Raman spectra measured for the composite biostructures allowed us to describe the binding of oxygen atoms of amino acid residues of the albumin with the carbon atoms of the SWCNTs. It is found that the interaction energy of the nanotube atoms and albumin atoms amounts up to 580 ?? kJ / mol . We used atomic force microscopy to investigate the surface of the composite biostructures. The pore size is in the range of 30 to 120 nm. It is proved that the proliferation of the fibroblasts occurred on the surface of the composite biostructures during 72 h of incubation.

In this work, we studied the structural changes of bovine serum albumin (BSA) that occur due to its denaturation caused by the thermal heating of the protein dispersion. The characteristic Raman spectroscopy peaks indicate the BSA conformation. Specifically, 1578 cm−1 corresponds to the native conformation, and 1608 cm−1 and 1660 cm−1 correspond to the denatured state.

Composite biomaterial consists of bovine serum albumin 25 wt. % and single-walled carbon nanotubes

In this study, characteristics of bioconstructions created by laser nanostructuring of carbon nanotubes in a matrix of bovine serum albumin were determined. Two types of bioconstructions were obtained: volumetric samples and thin films. Weight loss of bioconstructions placed in a liquid for 14 days was from 2.45 to 22.81%. The samples have good compatibility with blood cells, the values of hemolysis in the presence of sample do not exceed 10%.

Specific conductivity of micron- and submicron-size composite nanomaterial layers based on biocompatible carboxymethylcellulose matrix and multi-walled carbon nanotube filler was studied. An ultra-dispersive suspension was applied to soft (aluminum foil, polyimide and polyester, cotton fabric, office paper) and hard (cover glass, silicon) surfaces using a silk-screen process. Specific conductivity of layers with thickness within the range 0.5-5 μm was demonstrated to be ~1.2⋅104-4⋅104 S/m, whereas the highest conductivity of the surface square was approximately 0.2 S. The examined nanomaterial can be used in electronics and biomedical engineering.

Determination of nonlinear optical characteristics of active substances of the limiters of high-power laser radiation was carried out with the help of non-threshold and new threshold models. Experimental data of z-scan with open aperture was obtained, which helped to determine values of the nonlinear optical characteristics for dispersion media with carbon nanotubes and graphene oxide. Advantages of threshold model experimental data processing in comparison with non-threshold model was shown.

The 5–50 μm-thick layers of a nanomaterial consisting of acrylic paint and multilayer carbon nanotubes (∼3 mass.%) are investigated. It is shown that laser radiation and heat treatment enhance the conductivity of the layers by a few orders of magnitude. The layers remain stable in water for over 200 h and exhibit a conductivity of ∼ (100–1000) S/m, which make them promising for application in biomedical electrodes and wearable electronics.

This work is concerned with studying the technique of dissected tissue laser welding using specific facility and nanosolder. The technique perfomance was studied on the hog stomach mucous membrane samples. Laser solder compositions that allow maximal durability of the tissue welding seam were revealed and its 3D structure was studied using x-ray microtomography. Biocompatibility of the laser nanosolder was proved.

3-D bioconstructions were created using the evaporation method of the water-albumin solution with carbon nanotubes (CNTs) by the continuous and pulsed femtosecond laser radiation. It is determined that the volume structure of the samples created by the femtosecond radiation has more cavities than the one created by the continuous radiation. The average diameter for multi-walled carbon nanotubes (MWCNTs) samples was almost two times higher (35-40 nm) than for single-walled carbon nanotubes (SWCNTs) samples (20-30 nm). The most homogenous 3-D bioconstruction was formed from MWCNTs by the continuous laser radiation. The hardness of such samples totaled up to 370 MPa at the nanoscale. High strength properties and the resistance of the 3-D bioconstructions produced by the laser irradiation depend on the volume nanotubes scaffold forming inside them. The scaffold was formed by the electric field of the directed laser irradiation. The covalent bond energy between the nanotube carbon molecule and the oxygen of the bovine serum albumin aminoacid residue amounts 580 kJ/mol. The 3-D bioconstructions based on MWCNTs and SWCNTs becomes overgrown with the cells (fibroblasts) over the course of 72 hours. The samples based on the both types of CNTs are not toxic for the cells and don't change its normal composition and structure. Thus the 3-D bioconstructions that are nanostructured by the pulsed and continuous laser radiation can be applied as implant materials for the recovery of the connecting tissues of the living body.

A new method for the formation of composite nanomaterials based on multi-walled and single-walled carbon nanotubes (CNT) on a silicon substrate has been developed. Formation is carried out by ultrasound coating of a silicon substrate by homogenous dispersion of CNTs in the albumin matrix and further irradiation with the continuous laser beam with a wavelength of 810 nm and power of 5.5 watts. The high electrical conductivity of CNTs provides its structuring under the influence of the laser radiation electric field. The result is a scaffold that provides high mechanical strength of nanocomposite material (250 MPa). For in vitro studies of materials biocompatibility a method of cell growth microscopic analysis was developed. Human embryonic fibroblasts (EPP) were used as biological cells. Investigation of the interaction between nanocomposite material and cells was carried out by optical and atomic force microscopy depending on the time of cells incubation. The study showed that after 3 hours incubation EPP were fixed on the substrate surface, avoiding the surface of the composite material. However, after 24 hours of incubation EPP fix on the sample surface and then begin to grow and divide. After 72 hours of incubation, the cells completely fill the sample surface of nanocomposite material. Thus, a nanocomposite material based on CNTs in albumin matrix does not inhibit cell growth on its surface, and favours their growth. The nanocomposite material can be used for creating soft tissue implants

Laser welding device for biological tissue has been developed. The main device parts are the radiation system and adaptive thermal stabilization system of welding area. Adaptive thermal stabilization system provided the relation between the laser radiation intensity and the weld temperature. Using atomic force microscopy the structure of composite which is formed by the radiation of laser solder based on aqua- albuminous dispersion of multi-walled carbon nanotubes was investigated. AFM topograms nanocomposite solder are mainly defined by the presence of pores in the samples. In generally, the surface structure of composite is influenced by the time, laser radiation power and MWCNT concentration. Average size of backbone nanoelements not exceeded 500 nm. Bulk density of nanoelements was in the range 10 6 -10 8 sm -3 . The data of welding temperature maintained during the laser welding process and the corresponding tensile strength values were obtained. Maximum tensile strength of the suture was reached in the range 50-55°C. This temperature and the pointwise laser welding technology (point area ~ 2.5mm) allows avoiding thermal necrosis of healthy section of biological tissue and provided reliable bonding construction of weld join. In despite of the fact that tensile strength values of the samples are in the range of 15% in comparison with unbroken strips of pigskin leather. This situation corresponds to the initial stage of the dissected tissue connection with a view to further increasing of the joint strength of tissues with the recovery of tissue structure; thereby achieved ratio is enough for a medical practice in certain cases.

The possibility of limiting the intensity of laser radiation using a light-induced critical scattering of light at optothermodynamic conversion of stratified solutions of triethylamine/water and 2-butoxyethanol/water into the labile supercritical region between the spinodal and binodal through the critical point of stratified is shown.

Porous biocompatible three-dimensional nanocomposite materials were screened for improved mechanical properties. These nanocomposite materials should be potentially appropriate as filling for surgical implants and for regenerative medicine. Nanocomposite materials based on albumin and carbon nanotubes manufactured using laser technology meet these requirements. Density of nanocomposite materials (∼1200 kg/m3) is about 10% higher than density of their matrix materials (albumin and water). Hardness of nanocomposite materials (∼300 MPa) is about five times higher than hardness of crystalline albumin. This value is significantly higher than hardness of organic glass (PMMA) and aluminum (150-200 MPa). It is close to the hardness of native human bone tissue (∼500 MPa). Reduced hardness of nanocomposite materials (∼0.3 MPa/(kg/m3)) is close to this value in native human bone tissue (0.1-0.3 MPa/(kg/m3)). It is slightly lower than the similar value in titanium and its alloys (∼0.8 MPa/(kg/m3)) and significantly higher than this parameter in organic glass (∼0.13 MPa/(kg/m3) or aluminum (∼0.07 MPa/(kg/m3)). High hardness of nanocomposite materials is probably due to their nanotubular texture. This texture is induced by laser radiation.

The paper represents the results of nonlinear absorption study for solutions of deciaminomethylenepyran dyes DCM 627 and DCM-684 (yuloidine) at wavelength of 532 nm with 350 ps pulse duration obtained with the use of z-scan technique. It is shown that the induced absorption detected is due to two-photon absorption. Nonlinear and two-photon coefficients of absorption are evaluated. The results of numerical simulation are presented.

Use of organic dyes for improvement of the efficiency and targeting accuracy of laser treatment of biological tissues is considered. It is shown that some organic materials provide effective protection of adjacent tissues by reducing the intensity of optical radiation outside the laser surgery site. They also can eliminate the detrimental effect of random reflections of intense laser radiation upon its passage through semitransparent cartilaginous tissue. Advantages of diphthalocyanine dyes (broad spectral region of radiation absorption, high resistance to heat and light, solubility in low-toxic organic dyes) are described.

Dispersive and composite nanomaterials based on multi-walled and single-walled carbon nanotubes and its conjugates with dye of zinc phthalocyanine were produced. The composition and the structure of dispersive and composite materials were investigated using analytical methods of spectroscopy and microscopy. Nonlinear characteristic of nanomaterials of limiters by direct nonlinear scanning and Z-scan method were investigated. Studies suggest the possibility of using such nanomaterials in laser intensity limiters. Proposed threshold model characterizing limiters of powerful laser radiation takes into account the threshold nature of nonlinear interaction of irradiation with the nonlinear material. Threshold effect of nonlinear interaction of laser irradiation with several nonlinear material based on multi-walled and single-walled carbon nanotubes was experimentally found. It was shown that threshold model fit better with experimental data of Z-scan.

Work is devoted to the search new materials of laser irradiation limiter. Were created nanomaterials (dispersion and composites) for limiters based on multiwalled and singlewalled carbon nanotubes. Were carried out studies of the structure of nanomaterials by atomic force microscopy. Investigated the thermal and photo stability of the samples. Measured and calculated nonlinear optical properties of nanomaterials by direct scanning and Zscan. A comparison of theoretical and practical nonlinear optical characteristics. And also investigated the electrical conductivity of liquid and solid nanomaterials. Keywords—laser; limiter; nanomaterials, dispers; composites; carbon nanotubes; transmittance The search for new materials for laser limiters now is carrying out among of nanoparticles (NP) with strong nonlinear behavior. The NP could be either fullerenes and graphenes or carbon nanotubes (CNT). We have developed the PC program for modeling laser irradiation transferring through nanocomposites (NC) and nanodispersive (ND) media. We have investigated nanocomposites and nanodispersions based on metallic or semiconducting single-walled CNT (SWNT). As shows atomic force microscopy investigation the most of nanotubes are present in clusters of separated free fibrils. This is the evidence of high nanotube dispersion. In the case of ND with multi-walled CNT (MWNT) there is a presence of the same features on the surface with typical lateral sizes from tenth of micron up to microns and height from nanometers to hundreds of nanometers. Besides the NPs with height from 10 to 100 nm are present in the form of agglomerates and separate ball-like structures. The typical need-like structures was not observed. The average diameter of NP was in 10-30 nm range. The features exceeding this value were agglomerates of NP. The spectral characteristics of MWNT ND were stable under the heating up to 40 °C during about 85 hours. The room temperature stability was as long as 940 hours. The NDs are also stable under LED irradiation at the wave length 365, 630 and 810 nm and power 30-80 mW during 50-65 hours. We used solid state Nd:YAG laser LS-2132UTF (1-3 harmonics, single pulse energy – up to 200 mJ, single pulse length 7 ns, frequency of pulse repeating 15 Hz, power density of laser pulse up to 450 MW/sm 2 ). Nonlinear characteristics of nanomaterials was measured with making use of straight nonlinear transmittance method. The sample was placed in the convergent beam of laser irradiation with using positive spherical lens F = 500 mm. The laser irradiation intensity was measured with using polarized Glan’s lens. Linear transmittance T0 of ND based on tetrahydrofuran (THF) was 55 -70 %, while attenuation coefficient (KO) of laser irradiation was ~ 13 for carboxyl SWNT and ~ 9 for MWNT and 13-14 for SWNT functionalized by zinc phthalocyanine derivatives. According to the results of the Z-scan, the beam radius in the waist 20-25 nm. The nonlinear absorption coefficient β is equal to 30-35 cm/GW in CNT dispersions in DMF and 45-50 in THF dispersions. A role to play here can distinguish the boiling point of liquids: 153 C for DMF and 65,6 C for THF. Probability shock boiling determines the scattering intensity laser irradiation. So nonlinearity dispersion medium of THF increase. Optically uniform NC based on MWNT was prepared during polymerization and mechanical stirring and ultrasound treatment of ND in THF. After that the benzoyl peroxide promoter was added into the solution with keeping out at 45 С for 24 hours. To improve NC quality we added THF modifier. The irradiation wave length was 532 nm for NC based on polymethyl methacrylate with carboxyl SWNT and KO was ~ 8 at T0 ~ 60 %. The nonlinear absorption coefficient β is equal to 0.5-1.6 cm/GW in CNT dispersions in polymethyl methacrylate. The specific conductivity of dried NC layers based on MWNT is several orders higher then for initial NDs. The current-voltage characteristics for these layers remain almost linear while they are not linear for ND. The conductivity of NCs layers grows several times after annealing. The highest conductivity was for thin layers (less than 5 μm). There are number of reasons for high conductivity for CNT-based NCs: high aspect ratio of nanotubes and optimal composition of nanomaterials that consist of isolating matrix and conductive additive (CNT). Such composition of nanomaterials enables effective evaporation and burning out of polymer organics during annealing. The residue consisting of conductive graphite form between nanotubes increases the layer conductance. Finally annealing leads to good binding between matrix and CNT as well as between CNTs due to strong matrix carbonization. This work was provided by the Foundation of the President of the Russian Federation for state support of young Russian scientists (Grants SP-2477.2012.4).

The criteria were determined for simultaneous observation of scattered and unscattered (ballistic) peaks in temporal distribution of a narrow pulsed laser beam passed through a strongly scattering medium. Conditions were found for such an observation on the basis of non-stationary two-flux model for radiation transport. Calculation results permitted the definition of a compromise between the parameters of the initial laser pulse and the properties of a scattering medium. This provided the separate observation of various types of photons. The theoretical calculations were confirmed by experiments on recording pulse profiles of passed radiation of fs-laser in a water–milk solution.

A threshold model is described which permits one to determine the properties of limiters for high-powered laser light. It takes into account the threshold characteristics of the nonlinear optical interaction between the laser beam and the limiter working material. The traditional non-threshold model is a particular case of the threshold model when the limiting threshold is zero. The nonlinear characteristics of carbon nanotubes in liquid and solid media are obtained from experimental Z-scan data. Specifically, the nonlinear threshold effect was observed for aqueous dispersions of nanotubes, but not for nanotubes in solid polymethylmethacrylate. The threshold model fits the experimental Z-scan data better than the non-threshold model. Output characteristics were obtained that integrally describe the nonlinear properties of the optical limiters.

Results of in vivo experimental study of the biocompatibility and replacement of rabbit cartilage tissue with volume nanocomposite materials are described. The nanocomposite material was fabricated using a laser method. The possible use of the investigated nanocomposite in implants into animal cartilaginous tissue was tested.

The important problem of modern laser medicine is the decrease of an exposure of biological tissues outside of an operational field and can be solved by optical radiation limiting. Organic dyes with reversibly darkening can be placed onto surfaces of irradiated tissues or can be introduced in solder for laser welding of vessels. The limiting properties of a set of nontoxic organic compounds were investigated. Nonlinear optical properties of dyes having reverse saturable absorption (pyran styryl derivatives, cyanine and porphyrine compounds) were studied under XeCl and YAG:Nd (II harmonics) lasers excitation. The effect of attenuation of a visible laser radiation is obtained for ethanol solutions of cyanines: radiation attenuation coefficient ( AC) = 25-35 at N/S = 100-250 MW/cm 2 . In water solutions of such compounds in UV spectrum range AC 10. The spectral characteristics of compounds appeared expedient enough to operational use in laser limiters (broad passband in visible range of a spectrum). Under the data of Z-scanning (the scheme F/10) value AC 70 was reached. The limiting of power laser radiation in visible ( = 532 nm) and UV- ( = 308 nm) spectral region and nanosec ond pulse duration (7 -13 ns) across porphyrine solutions and their complexes with some metals (13 compounds) was investigated too. The comparative study of optical limiting dependence on intensity of laser radiation, solvent type and concentration of solutions was carried out for selectewavelength. There was shown a possible use of pyran styryl derivatives DCM as limiters of visual laser radiation. To understand a mechanism of laser radiation limitation the light i nduced processes were experimentally and theoretically studied in organic molecules. The quantum-chemical investigation of one cyanine compound was carried out. There were noted the perspectives of laser radiation limiting by a pplication of inverted schemes of traditional laser shutters. Usage of phenomena of light-induced opalescence in one-component liquids and spi nodal decay in stratifying liquid solutions is proposed. KEYWORDS: Laser radiation, limiting, materials, medical use

The selection of ballistic photons from a radiation, passed through a biological medium, is necessary for obtaining qualitative images in optical tomography. Within the framework of a non-stationary two-flux model of radiation transport in high scattering medium there is found the fraction of ballistic photons as function on macroscopic characteristics of a medium. With the purpose of separation of photons the application of bisphthalocianine dyes of rare-earth and transitional elements is considered. The experiments on deriving contrasted images in margarine and water solution of milk are carried out.

The criteria were determined for simultaneous observation of scattered and unscattered (ballistic) peaks in temporal distribution of a narrow pulsed laser beam passed through a strongly scattering medium. Conditions were found for such an observation on the basis of non-stationary two-flux model for radiation transport. Calculation results permitted to define a compromise between parameters of the initial laser pulse and properties of a scattering medium. This has provided the separate observation of various types of photons. The theoretical calculations were confirmed by experiments on recording pulse profiles of passed radiation of fs-laser in a water-milk solution.

The dependence of the optical density of a model strongly scattering medium-aqueous milk solution on its layer thickness was investigated. IR lasers generating pulses of various short (from nanosecond to femtosecond) duration were used as the radiation sources. There were determined the dependences of the attenuation coefficients of such pulses on the solution concentration in the areas of low and more high optical densities of the solution layer for different values of radiation detector angular aperture. A modification of the two-flux Kubelka-Munk model was used to derive an expression describing the dependence of the transmission of a solution layer on its parameters when radiation detectors with a finite angular aperture are used. The absorption and scattering coefficients of the medium were obtained. A comparison of the calculations and experiments revealed a forward scattering anisotropy of short-duration laser radiation in an aqueous milk solution characteristic for the Mie's scattering.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

There are some difficulties in the use of a well-known X-ray computer tomography technique due to the strong light scattering in biological tissues. We propose to analyze the whole light scattering picture for the development of novel processing algorithms in tomographical imaging. Time-resolved experiments on the forward scattering of IR-light from a model of biological media illuminated by a picosecond YAG-laser with 10 ps pulse duration have been performed. The scattering radiation was recorded by a streak camera having 1.5 ps time resolution. From these results and theoretical considerations the analytic expression for intensity against time distribution of the laser radiation passed through the media has been obtained. The expression can be used as the basis for tomographical reconstruction.

Time profiles of picosecond Nd:YAG-laser radiation transmitted through homogeneous and inhomogeneous scattering models of biological objects contrasted by new dyphtalocyanine dyes have been investigated. These dyes have specially synthesized as the contrasting substances for biological tissues in order to increase signal-to-noise ratio in optical image processing. By using this dye contrasting technique the ratio improvement has been demonstrated in time-resolved experiments on determination of inner details for some model biological objects.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

For successful application of laser tomography methods for earlier medical diagnostics the signal-to-noise ratio (contrast) must be increased. For this purpose it is possible to use the absorbing dyes. We have theoretically investigated optical imaging conditions in high scattering medium on a model object. In our experiments a YAG:Nd laser generating picosecond pulses was employed. Output radiation has been recorded by a high speed streak camera with 1.5 ps temporal resolution. The high stability of the laser and of measurement scheme characteristics was provided. We looked for the contrasting substances having tropism with pathologically changed tissue of the tumor. For this purpose some dyphthalocyanines were synthesized. The experiments with laboratory animals have demonstrated that saturated dye concentrations were noticeably lower than toxicologic dangerous concentration values. We have demonstrated a possibility of the contrasting for a model object. The experimental temporal profile of scattered radiation can be explained by the nonstationary two-flow theory.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The introduction of sulpho groups into molecule of mono- and diphthalocyanines of hafnium and zirconium gave rise to the formation of water soluble compounds. This allows us to extend the field of their applications. The dyes of this class have been found to be efficient photosensitizers for PDT of cancer.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Suitable methods for synthesis of water soluble diphthalocyanines of rare earth elements have been developed. The synthesis was carried out by direct sulphonation of corresponding unsubstituted analogues. The sulphonation degree depends on the nature of a sulphonated agent, reaction time and molecular ratio of reagents. This allows us to vary the number of sulpho groups from one to the values corresponding to full sulphonation.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.