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Gold nanostars are one of the new types of nanoparticles with advantages such as plasmon resonance tunability and low toxicity. Therefore, gold nanostars are promising candidates for various biomedical applications including bioimaging, cell optoporation and plasmonic photothermal therapy (PTT) in NIR I, II, and III optical transparency windows of biotissues. However, the stability and possible transformation of gold nanostars under laser irradiation still remains unexplored. In this work, we studied the photomodification of gold nanostars under the 1064-nm nanosecond pulsed laser irradiation by the transmission electron microscopy and spectrophotometry. The photostability of nanostars depends on their morphology and the plasmonic properties. Specifically, for large nanostars with a plasmon resonance at 950 nm remarkable changes occur at a threshold pulse energy of 5 μJ. At this threshold, a significant part of nanostars spikes melts and most of the nanostars start to transform into gold spheres. For higher pulse energies of about 50 μJ, all stars transform into spheres. For smaller gold stars with a plasmon resonance at 680 nm, the changes are less pronounced. Up to pulse energy of 50 μJ, they retain the shape of stars and have spikes on their surface. Moreover, the complete transformation of these stars into spheres does not occur up to pulse energy of about 150 μJ. The obtained results can be important for optimization of PTT treatment with gold nanostars and nanosecond laser irradiation.

The results of the research and design of a novel vacuum photosensor with a planar molybdenum blade structure are presented. The advanced prototype implements the principle of an increasing penetrability of the Schottky barrier for the metal&ndash, vacuum interfaces under the action of an external strong electrostatic field. Theoretical and experimental substantiation of the photosensor performance in a wide range of wavelengths (from 430 to 680 nm and from 800 to 1064 nm) beyond the threshold of the classical photoelectric effect is given. The finite element method was applied to calculate distribution of the optical and electrostatic fields inside the photosensor structure. The sensor current-to-light response was studied using the periodic pulsed irradiation with the tunable wavelength. It was shown that the nanoscale localization zones of two types are formed near the surface of the blade tip: the zone of an increased concentration of hot electrons localized inside the molybdenum blade, and the zone with an increased strength of the external electrostatic field localized outside the blade. In general, the mutual positions of these zones may not coincide, whereas the position of the first-type localization zone significantly varies with the changes in the wavelength of the irradiating light. This causes features in the spectrum of the quantum yield of the photosensor such as expressed non-monotonic behavior and occurrence of sharp dips. The design of the photosensor that provides matching of the positions for both types of localization zones was proposed, the manufactured prototypes of the designed device were experimentally studied. In the designed photosensor, the ballistic transport of photoelectrons in the vacuum gap with a strong field provides a possibility for the creation of ultra-fast optoelectronic devices, such as modulators, detectors, and generators.

The consistent patterns for local temperature fields under laser irradiation of biological tissue doped by effectively absorbing plasmon gold nanostars are discussed. Differences in the degree of spatial localization and the kinetics of the photoinduced temperature fields under irradiation by femto-, pico- and nanosecond pulses are revealed.

In this work, we investigate the spectral and polarization characteristics of a vacuum photosensor with a nanoscale molybdenum blade as a sensing element. The results of theoretical and experimental studies of the optical fields in the sensor and the photocurrent produced by laser beam irradiation in the range of wavelengths from the visible to the near infrared are presented. The existence of a photo-response far beyond the red threshold of the classical photoelectric effect is ensured by the localization of an external strong electrostatic field. Features of the field interaction of radiation with a molybdenum blade cause the registered spectral non-monotonicity of the photocurrent value, which corresponds to the results of theoretical studies. The ballistic transport of electrons in a vacuum is characterized by a high speed. Achieved results made the photosensor based on nanoscale molybdenum blade promising in the development of ultrafast vacuum micro and nanoelectronic devices.

In this work, we describe the technology and design of planar multilayer structure. It is used as a sensitive element of the vacuum photosensor. Metal and dielectric layers are of nanoscale thickness. It is shown that the use of a thin molybdenum blade in the structure ensures the localization of the electrostatic field and increases the photosensitivity of the vacuum sensor. Submicron inter-electrode gaps provide a short transit time of the electron beam caused by the action of a light pulse. The ballistic transport of electrons in a vacuum is characterized by a high speed.

In this paper, a theoretical model of the formation of a local temperature field in suspensions of microorganisms with embedded plasmonic gold nanorods under irradiation by low-intensity NIR laser light was considered. The results of numerical modeling of the optical properties of plasmon nanorods used in the experiments, and the results of multiscale modeling of the parameters of local hyperthermia with various types of distribution of the concentration of plasmon nanoparticles are presented. Found that the process of concentration of nanoparticles, functionalized with human immune globulins IgA and IgG, around the cells of microorganisms with the formation of "clouds" leads to the appearance of a microscale zone of elevated temperature. This ensures a synergistic effect of a multiplicative increase in the volume of the hyperthermia zone. The results of numerical simulation provide a justification for the experimentally observed increase in the bacterium killing ability at laser hyperthermia of the cellular environment doped with functionalized nanoparticles, without a noticeable increment in the recorded average sample temperature when irradiated with a low intensity laser beam of around 100 mW/cm2.

Numerical modeling of spectral absorption and scattering properties of structures manufactured as the ordered arrays of plasmon nanoparticles is carried out in this work. The results of numerical 2D simulation of selective heating of an array of plasmon resonant gold nanodiscs irradiated by a CW NIR laser (810 or 1064 nm) are presented. Calculations fit well to experimental data received. We demonstrate the possibility to control the local amplification of a shining laser field in the space between nanodiscs, as well as plasmon resonance absorption of each individual nanodisc. The perspectives of application of such nanostructures for providing of precision dosed-up thermal effects in cells and biological tissues are discussed.

An important direction in the development of X-ray computed tomography sensors in systems with increased scanning speed and spatial resolution is the creation of an array of miniature current sources. In this paper, we describe a new material based on gold nanostars (GNS) embedded in nanoscale diamond-like carbon (DLC) films (thickness of 20 nm) for constructing a pixel current source with photoinduced electron emission. The effect of localized surface plasmon resonance in GNS on optical properties in the wavelength range from UV to near IR, peculiarities of localization of field and thermal sources, generation of high-energy hot electrons, and mechanisms of their transportation in vacuum are investigated. The advantages of the proposed material and the prospects for using X-ray computed tomography in the matrix source are evaluated.

A mathematical model for the calculation of the optical and thermal properties of an ensemble of gold nanostars with different tip lengths L = 10 to 20 nm in an aqueous environment is proposed. The heating of a nanoparticle ensemble under irradiation by a laser pulse of a nanosecond duration: resonant λ = 808 nm and nonresonant λ = 1064 nm is studied. A significant blue shift of surface plasmon resonance during the formation of a vapor bubble around the nanoparticle was detected and described. Based on the analysis of the kinetics of nanoparticle heating under the action of a laser pulse before and after the formation of a vapor bubble, a theoretical description of the experimentally observed threshold nature of particle photomodification is given. It was found that the laser intensity Im necessary to achieve the melting temperature Tm (photomodification threshold) tends to increase with decreasing nanostar tip length and for an individual nanostar differs by an order of magnitude. However, up to 45% of the nanoparticles are heated to the melting temperature Tm by a single pulse with an intensity only 2.5 times higher than the minimum value of Im. At a wavelength of 1064 nm, Im is ∼6 times higher than at a wavelength of 808 nm.

The tunneling photo effect has been studied in a microdiode with an electrostatic field localized at an emitter based on a nanosized DLC structure. It is established the photocurrent, when the carbon nanoemitter is exposed by laser and tunable low-coherent radiation in the spectral range from UV to near IR with photons of low energy (below work function). A linear dependence of the photocurrent on the level of optical power in the range of micro- and milliwatt power is established. The effect of saturation of the current-voltage characteristics of the tunnel photocurrent associated with a finite concentration of non-equilibrium photoelectrons is observed. The observed spectral Watt-Amper characteristics can be adequately interpreted using a modified Fowler–Nordheim equation for non-equilibrium photoelectrons.

A model for calculating the electrostatic field in the system "probe of a tunnel microscope - a nanostructure based on a DLC film" was developed. A finite-element modeling of the localization of the field was carried out, taking into account the morphological and topological features of the nanostructure. The obtained results and their interpretation contribute to the development of the concepts to the model of tunnel electric transport processes. The possibility for effective usage of the tunneling microscopy methods in the development of new nanophotonic devices is shown.

The paper provides a justification and a comparative analysis of the scaling directions of the developed and investigated planar triode field emission cathode unit with the aim of increasing the maximum field current density up to 0.75 A-cm -2 without sacrificing durability. The design features of the vacuum device with a planar structure provided low-voltage control - at 150 V in the mode of long-term durability and not more than 250 V in the mode of the maximum permissible emission current.

Multiple factors and their impact on the stability of DLC field emission structures are discussed in the present work. Planar multi-electrode structures, in which the formation of zones of localization the electrostatic field of a certain topology performed, are examined. Estimates carried out demonstrated the existence of an effective solution for creating reliable and durable vacuum devices for electronics and photonics. Conclusions are confirmed by the results of experimental studies. Samples of devices showed an average current density of field emission 0.30-0.35 A/cm 2 .

The phenomenon of electron tunnel photoemission from the DLC film structure is discussed. Planar multi-electrode structure provides formation of zones of localization the electrostatic field of a certain topology. Under the influence of a strong electrostatic field, both equilibrium and nonequilibrium (photoexcited or "hot") electrons tunnel into the vacuum from the zone of concentration of electrostatic field. The results of experimental studies and theoretical simulations of the process show the saturation of photoemission current component with an increase in operating voltage. This fact makes it possible to realize the high-speed control of the spectral sensitivity of the photosensor. This is fundamentally important for applications in the modern electronic and photonic devices.

The results of the practical implementation of the concept of field-emission current source with high average current density of 0.1-0.3 A-cm-2 are shown. The durability of cathode samples at a level of 6000 hours is achieved under conditions of technical vacuum. A phenomenological model is suggested that describes the tunneling of both equilibrium and nonequilibrium electrons in a vacuum from the zone of concentration of electrostatic field. Conditions are discussed as the resulting increase in the emission current due to the connection mechanism of the photoelectric effect is thermodynamically favorable, that is not accompanied by an undesirable increase in the temperature of the local emission zone. It is shown that to ensure stability and durability of the cathode is also important to limit the concentration of equilibrium carriers using composite structures «DLC film on Mo substrate." This helps to reduce the criticality of the CVC. A possible alternative is to use a restrictive resistance in the cathode. However, this increases the heat losses and thus decreases assembly efficiency. The results of experimental studies of the structure showing the saturation of photoemission current component with an increase in operating voltage. This fact suggests the existence of an effective mechanism for control of emission at constant operating voltage. This is fundamentally important for the stabilization of field emission cathode, providing a reliability and durability. The single-photon processes and the small thickness DLC films (15-20 nm) provide high-speed process of control.

We consider the possibility of using gold nanoparticles to improve the image contrast of biotissue structures in reflection confocal laser microscopy. We present the results of experimental studies using gold nanospheres with a diameter of 60 nm compared to osmotically active immersion contrast agents based on glycerol.

The process of optical pulse formation in a solid state laser in the regime of induced mode synchronization and the development of breakage upon frequency detuning are considered based on a numerical solution of the Maxwell-Bloch equation. It is established that breakage of the sequence and shape of laser pulses in the course of an increase in the frequency detuning begins with the appearance of a periodic modulation of the pulse sequence envelope by low-frequency relaxation oscillations. These oscillations transform into regular spikes, which follow the scenario of period doubling that leads to a chaotic regime. It is also established that an optimum level of spontaneous noise exists at which the synchronization bandwidth is maximum, while the duration of pulses is minimum at a fixed loss modulation amplitude. This scheme of synchronization breakage was qualitatively confirmed in experiments on a YAG:Nd laser (λ = 1.06 μm) with cavity loss modulation at an intermode beat frequency.

The work is devoted to the development of a new direction in creating of broadband photo sensors which distinctive feature is the possibility of dynamic adjustment of operating frequency range. The author’s results of study of red threshold control of classic photoelectric effect were the basis for the work implementation. This effect was predicted theoretically and observed experimentally during irradiation of nanoscale carbon structure of planar-edge type by stream of low-energy photons. The variation of the accelerating voltage within a small range allows you to change photoelectric threshold for carbon in a wide range - from UV to IR. This is the consequence of the localization of electrostatic field at tip of the blade planar structure and of changes in the conditions of non-equilibrium electrons tunneling from the boundary surface of the cathode into the vacuum. The generation of nonequilibrium electrons in the carbon film thickness of 20 nm has a high speed which provides high performance of photodetector. The features of the use of nanoscale carbon structure photocurrent registration as in the prethreshold regime, and in the mode of field emission existence are discussed. The results of simulation and experimental examination of photosensor samples are given. It is shown that the observed effect is a single-photon tunneling. This in combination with the possibility of highspeed dynamic tuning determines the good perspectives for creation of new devices working in the mode of select multiple operating spectral bands for the signal recording. The architecture of such devices is expected to be significantly simpler than the conventional ones, based on the use of tunable filters.

Morphology at Intravenous Particle Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 774 29.5 Local Laser Hyperthermia and Thermolysis of Normal Tissues, Transplanted andSpontaneous Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 781 29.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 792We describe an application of plasmonic silica/gold nanoshells to produce a controllable local laser hyperthermia or thermolysis of tissues with the aim of the enhancement of cancer photothermal therapy. Laser irradiation parameters are optimized on the basis of preliminary experimental studies using a test-tube phantom and laboratory rats. Temperature distributions on the animal skin surface at hypodermic and intramuscular injection of gold nanoparticle suspensions and affected by the laser radiation are measured in vivo with a thermal imaging system. It is shown that the temperature in the volume region of nanoparticle location can substantially exceed the surface temperature recorded by the thermal imaging system. The results of temperature measurements are compared with tissue histology results. Nanoshell-based photothermal therapy in several animal models of human tumors gave highly promising results; the dosage information, thermal response, and tumor outcomes for these experiments are presented.

Kinetics, biodistribution, and histological studies were performed to evaluate the particle-size effects on the distribution of 15 nm and 50 nm PEG-coated colloidal gold (CG) particles and 160 nm silica/gold nanoshells (NSs) in rats and rabbits. The above nanoparticles (NPs) were used as a model because of their importance for current biomedical applications such as photothermal therapy, optical coherence tomography, and resonance-scattering imaging. The dynamics of NPs circulation in vivo was evaluated after intravenous administration of 15 nm CG NPs to rabbit, and the maximal concentrations of gold were observed 15-30 min after injection. Rats were injected in the tail vein with PEG-coated NPs (about 0.3 mg Au/kg rats). 24 h after injection, the accumulation of gold in different organs and blood was determined by atomic absorption spectroscopy. In accordance with the published reports, we observed 15 nm particles in all organs with rather smooth distribution over liver, spleen and blood. By contrast, the larger NSs were accumulated mainly in the liver and spleen. For rabbits, the biodistribution was similar (72 h after intravenous injection). We report also preliminary data on the light microscopy and TEM histological examination that allows evaluation of the changes in biotissues after gold NPs treatment.

We describe an application of plasmonic silica/gold nanoshells to produce a controllable laser hyperthermia in tissues with the aim of the enhancement of cancer photothermal therapy. Laser irradiation parameters are optimized on the basis of preliminary experimental studies using a test-tube phantom and laboratory rats. Temperature distributions on the animal skin surface at hypodermic and intramuscular injection of gold nanoparticle suspensions and affectations by the laser radiation are measured in vivo with a thermal imaging system. The results of temperature measurements are compared with tissue histology.

This paper deals with the problem of using semiconductor laser radiation (wavelength 810 nm) for healing skin and mucous cancer of small animal. Opportunities of using different types of lasers for clinical applications under oncological diseases of skin and oral mucous have been analyzed. We determined power densities and duration of laser irradiation for different types of tumors. IR thermograph was used for noninvasive temperature monitoring in the area of tumor localization. For noninvasive measuring and registration of spatial distribution of radiation temperature of investigated objects, we used IR Imager IRISYS 4010 Infrared Integrated System Ltd (UK).

Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA > (Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole ( >, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

Nanoshells are nanoparticles that consist of ultra-t metal shells surrounding core materials such as si Gold nanoshells (GNSs) have already been used in various applications, such as analytical diagnostics photothermal-based therapies, and in vivo optical visualization, based in part on their ability to diffra and absorb light of varying wavelengths. The effic of nanoshell technologies, however, is limited b gaps in our current understanding of the thermal interactions between nanoshell particles and laser light pulses or continuous waves in the conte complex biological environments. Irradiation, even with moderate pulses o energy, can induce melting, evaporation, and fragmentation of nanoshells These events can drastically alter the intended therapeutic effects and lea the formation of vapor bubbles as well as acoustic waves and shock waves

Light-induced inactivation of dynamic response of somatic frog nerve on electrical pulsed excitation was study ex vivo. The light-sensitive Indocianin Green has been used on photodynamic induced inactivation of the processes generation nerve pulses. Inactivation of consequence action potential of somatic frog nerve using excitation of electrical pulsed was achieved by irradiation with diode laser light in a IR spectral region (λ=810 nm, P~1W/cm2) in the case of Indocianin green. It was discovered that Indocianine green decrease of the amplitude compound action potential of the ensemble neurons. Experiments show effective destruction of cancer cells of ear, mouth and skin by local injection of plasmon resonant gold nanoshells and semiconductor laser (810 nm) irradiation. For destruction such tumors pulse duration was not less than 1microsecond and pulse separation 10 at average power density 1-3 W/sm2 and energy density 100-200 J/sm2

The method of the local (>200 pm) functional injury of somatic frog's nerve using UV-A radiation of N2 laser (λ=337nm , P~10-100 mW) was realized. The level of injury was assessed from the decrease of compound action potential of the nerve stimulated extracellularly by electrical pulses of millisecond duration. Study of dynamic response of the bundle of axons revealed the decrease of the number of action potential which can be generated (less than 1O). This decrease may be attributed to destruction of action transport or/and voltage-activated ion channels of axon membrane. The dose dependence of the level of nerve injury was studied using varied both intensity and duration of UV-A irradiation.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The method of the local functional injury of somatic frog's nerve using high coherent UV-A radiation of N 2 laser (λ=337nm, P~10 mW), coherent mercury-vapor lamp radiation (λ=365; 312 nm P Σ ~2 mW/cm 2 ) and low-coherence UV-A sun radiation (400-315 nm, PΣ~10 mW) was realized. The level of injury was assessed from the decrease of compound action potential of the nerve stimulated extracellularly by electrical pulses of millisecond duration. Study of dynamic response of the bundle of axons revealed the decrease of the number of action potential which can be generated (less than 10 5 ). This decrease may be attributed to destruction of action transport and/or voltage-activated ion channels of axon membrane. The dose dependence of the level of nerve injury was studied using varied both intensity and duration of high and low-coherent UV-A irradiation.

Dynamic response of the somatic frog nerve under electrical pulsed excitation and processes of inactivation under local laser influence (λ=900 nm) was investigated ex vivo . The dependence of propagation speed of action potential from external laser power was discovered. The propagation speed of action potential was growing up in axons bunch of frog’s somatic nerve with increasing of laser power. More than 90% of axons were inactivated when the power of probing radiation was equal to 10W, and the propagation speed increased up to 50%. Strong fluctuation of propagation speed compound action potential and its amplitude was discovered in ensemble of neurons near threshold. Complex dynamic of compound action potential was discovered. Excitation threshold was growing up with increasing the power of laser radiation and only several neurons from ensemble were activated.

We have observed for the first time the dynamics of a speckle field generated in bulk scattering partly ordered media or low-mode optical fibers probed by a laser diode ( λ = 654 nm) and a compact diode-pumped YAG:Nd laser ( λ = 532 nm) in the regime of frequency tuning. The dynamic coherent speckle-photo-chromic effect can be observed provided that the deviation of the probing radiation frequency is comparable with or greater than the effective phase delay difference between modes in the optical fiber of between waves in the random scattering medium. Using the proposed photochromic speckle technique, it is possible to determine the intermode dispersion of fibers with a length on the order of one meter and the dispersion of phase delay in test fluoroplastic structures in the regimes of several fold scattering (for a sample thickness of 10-20 μm) or multiple scattering (for a thickness of up to ~ 2 cm).

New techniques research mechanisms of photdynamic reactions at somatic frog nerve was approved. Dosimetry PDT with minimum time resolution ~1ms determined by changing the amplitude of compound action potential of somatic frog nerve. Light-induced inactivation of dynamic response of somatic frog nerve on electrical pulsed excitation was study ex vivo. The light-sensitive dyes: methylene blue (Mb), Indocianin green and eryhtrocin-B has been used on photodynamic induced inactivation of the processes generation nerve pulses. Inactivation of consequence action potential of somatic frog nerve using excitation of electical pulsed was achieved by irradiation with He-Ne laser light in a red spectral region (λ=633 nm, power level 2-20 mW), diode laser (λ=805 nm, P

Dynamic response of the somatic frog nerve on electrical pulsed excitation was investigated ex vivo. Strong fluctuation of consequence compound action potential in ensemble of neurons near-threshold was discovered. The nonlinear response of the Hodgkin-Huxley model neurons with external electrical pulsed was investigated and numeral results correlation with experiments. Complex dynamic of compound action potential was discovered when on-line time of stimulatory electrical pulses comparable with nerve refractory period. New techniques research nonlinear behavior using photodynamic reactions or UV-A radiation at somatic frog nerve was approved. This nonlinear dynamic regime was controlling laser induced inactivation of processes in membrane of nerve.

The method of scattering media probing with the use of low-coherent light source with the controllable width of emission spectrum is considered. The contrast of partially coherent speckles is suggested as the diagnostical parameter. The additional polarization discrimination of detected speckles gives the possibility to select the components of scattered field which propagate in probed medium at different distances. Experimental results obtained for weakly ordered systems characterized by non-diffuse scattering regimes are presented.

The nonlinear response of the Hodgkin-Huxley model neuron with external electrical pulsed was investigated. Dynamic response of somatic frog nerve on electrical pulsed duration was study in vitro. Transcutaneous millisecond of excitation of the ganglion cell of the human retina by electric uses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The dynamics of actively mode-locked laser is investigated and the results of numerical simulations are presented. Different regimes corresponding to the relaxation oscillations and spiking are observed depending on the noise level and frequency detuning. The numerical results demonstrate in detail the processes of destroying synchronization and pulse-train instabilities.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We tried to probe photon path statistics by analyzing the change of speckle contrast with different coherence length of source. The speckle contrast is strong function of both photon path statistics inside scattering media and coherence function of a source. By introducing explicit formula for speckle contrast, we can relate photon path statistics with measured speckle contrast and coherence of source in reverse manner. To realize this idea, we formulated this relationship and performed several MC simulations and basic experiments for various scattering media. Although the present result is very rough, it shows some possibility of using this method to find photon propagation statistics inside turbid media such as tissues and thin polymer film.

Measurement of retinal visual acuity in 230 patient with different types of cataract (senile, posterior capsular, nuclear, complicated) before and after extraction has shown high correlation between these values. Double `red' (He-Ne (lambda) equals 633 nm or diode laser GaAlAs (lambda) equals 630 - 650 nm) and `green' (YAG:Nd laser (lambda) equals 532 nm) retinometer has allowed to determinate the angle of resolution of the retina practically for all types of cataract. Applied speckle-technologies have permitted the range of retinal angular resolution to be estimated with the help of laser retinometer at the stage of preoperative cataract diagnosis. Speckle-modulated laser fields arising at in vitro measurements of different types of human cataracts lenses have been investigated experimentally. Computer analysis of digital images has allowed to estimate of destruction of the spatial coherence of a laser beam scattered by a turbid lens. Effect of saturation of the average speckles size in multiple-scattering biotissues gives good opportunities to determine preoperative retinal visual acuity for any type of cataracts in vivo.

Speckle-modulated laser fields arising at in vitro measurements of different types of human cataractous lenses have been investigated experimentally. Computer analysis of digital images has allowed to estimate of destruction of the spatial coherence of a laser beam scattered by a turbid lens. Applied speckle-technologies have permitted the range of retinal angular resolution to be estimated with the help of laser retinometer at the stage of preoperative cataract diagnosis. Effect of saturation of the average speckles size in multiple-scattering biotissues gives good opportunities to determine preoperative retinal visual acuity for any type of cataracts in vivo.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The scenario of the transition from a stationary state to the regime of generation of optical dynamic chaos is studied, which appears in He-He laser with delayed feedback. The coefficient of feedback is proportional to the output laser power and the changes of the discharge current. Depending on the coefficient of the signal of feedback subharmonic we observed the cascade of bifurcations of doubling period, the inverse cascade, the cycles with period f/3 and f/5, and the regime of dynamic chaos whose spectrum has no resonance frequencies. The range of existence of the observed regimes depended greatly on the degree of nonlinearly of the watt- ampere energy characteristics, defined by the processes of saturation of inversion of population and the controlled pressure of gas in the active element. Optical chaos in such non-linear systems appears, when the delay is greater than the life times of the metastable states of helium and neon that determine the internal dynamics of the laser. These results can be used for creation of optical generators of amplitude and frequency noise and information security systems.

Special features of speckle-modulated laser fields arising at in vitro measurements of different types of human cataractous lenses have been investigated experimentally. Computer analysis of digital images has allowed for estimation of destruction of the spatial coherence of a laser beam scattered by a turbid lens. Applied speckle-technologies have permitted the range of retinal angular resolution to be estimated with the help of laser retinometer at the stage of preoperative cataract diagnosis. An extent of laser retinometry at measuring visual acu9ity in patients with any type of cataract, and an incorrectness of its estimation by means of opto types charts have been set up.

Spectral characteristic biophotoreceptor in the human eye were determined using reflected optical wave from the retina and in this measurement have been used microspectrometric techniques. This measurements is possible only in vitro. We present new non-invasive correlation method ocular low coherence interferometry, which can be used in ophthalmology. Number of observed fringes in the Michelson interferometer is connected with spectral width biophotorecipient across Wiener-Khinchine transformation in case using of the partial coherent light sources. Such method allow determinate spectral sensitivity rod if sounded light is low intensity and application optical filter permit value red and violet border human eye. Change width interference fringes it is possible simultaneity measurement space sensitivity of the human retina which is very important in the ophthalmic diagnostic.

Measurement of retinal visual acuity (RVA) in 170 patient with different types of cataract (senile, complicated, posterior capsular ) before and after cataract extraction and also in vitro measurement of RVA with extracted cataractal lenses has shown that laser retinometer can be used for evaluating visual acuity within 0.3 - 1, practically for all types of cataract. Experimental in vitro studies of speckle-modulated laser field arising after transmission through different type of human cataractous lenses are presented. Computer analysis of digital imaging has allowed us to determine the degree of destruction of spatial coherence of scattered laser beam and the angle of resolution of retina using Retinal Analyzer of Vision (AROLI) in diagnosis of cataract. Approbation of topographic digital videosystem used for determing the extent of opacities in cataractous lenses in vivo and its use in measuring diapasons RVA for different type of cataracts is presented. The system consists of the modified slit lamp, CCD camera ( ELECTRIM) and PC PENTIUM with corresponding software.

We report the results concerning the regimes of transition to the temporal chaos in an optical system with the feedback based on the single-mode frequency-stabilized laser.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In the paper theoretical and experimental study of forming of interference pattern with a high contrast at the retina cataractous eye is presented. The high contrast of retinal fringes is reached by control of the parameters of incident beam with regular interference fringes. Experimental result have been done for the model objects that can be described in the framework of 'random phase screen' approximation. Some recommendations for clinical application are suggested.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Coherent optical time, frequency and heterodyne domain methods of dynamic parameters diagnostic of microwave transistors are discussed. Possibilities of optoelectronic and electrooptic station at the probing by picosecond pulses using mode-locked laser are considered. Peculiarities of microwave modulation of injective heterolaser and MESFET dynamic photoresponse are discussed. The determination of microwave transistor gain and noise coefficients using laser heterodyne methods at the probing of the active area drain- source is shown.

Experimental in vitro studies of speckle-modulated laser field arising after transmission through different type of human cataracties lenses are presented. Computer analysis of digital imaging has allowed to determinate the degree of destruction of spatial coherence scattered laser beam and the angle of resolution of the retina using Retinal Analyzer of Vision in diagnosis of cataract. Comparison with clinical investigation in vivo has been made.

It is shown experimentally and theoretically that due to interaction of totally or partially coherent light beams with such tissues as the human eye sclera and skin which undergo the refractive indices matching the collimated and total transmission, diffuse reflection and speckle structure of transmitted beams are changing in accordance with transition from multiple to low-step scattering. The scleral samples in a final stage of tissue optical clearing have the same properties as an optical retarder.