We studied the extinction and integral scattering spectra of gold and silver nanorods with random or ordered orientations. The calculations were carried out for spheroids, right circular cylinders, circular cylinders with hemispherical ends (T-matrix method), and the rectangular prisms (Discrete Dipole Approximation, DDA). For particles with equivolume diameters greater than 20 nm, we have found a new resonance that is located between the usual plasmon resonances corresponding to the excitation of nanorods by the longitudinal or transversal electric fields. The new resonance can be excited only by TM incident wave, and its magnitude is maximal for orientation of the particle symmetry axis at 54° with respect to the light propagation direction. By contrast to the dominant scattering nature of the longitudinal resonance, the new resonance corresponds to the strong absorption comparable with scattering contribution to the total extinction. It is shown that the new resonance can be attributed to the quadrupole excitation of metal nanorods.

The static and dynamic light scattering (DLS) methods were applied to study the thermodynamic properties and disperse structure of water+surfactant+solubilizer systems. It is supposed that such systems possess a micellar structure that can be used to develop new effective forms of veterinary drugs. For preparation of drugs (antibiotics) in micellar form, water solutions of the surfactant Cremafor-EL (CR) with the co-solvent dimethylacetamide (DMA) were used. To evaluate the stability of micellar solutions, we measured the light scattering intensity at 90 degrees as a function of temperature (20-80° C) in a water+CR+DMA system. The size distribution of micelles was determined by DLS measurements followed by DynaLS software processing. As thermodynamic characteristics of solutions, the so-called cloud point temperatures (CPT) and absolute instability temperatures (AIT) were used. Specifically, the CPT was determined as the intersection point of two linear fittings for scattering intensity vs temperature plots. AIT was determined using the inverse light scattering intensity data plotted vs temperature and then extrapolated to zero. The micelle-size distributions were measured for three types of surfactants (CR, Tween-80, and Tween-20), as well as for water+CR+DMA systems.

We have fabricated nanometer spherical silicon and germanium particles by dissolving semiconductors in some melted metals (aluminum, indium). The first transmission electron microscopy images and electron microdiffraction patterns of the spherical Si and Ge particles are presented. The obtained spherical particles have sizes from hundreds nanometers to tens angstroms, the diameters of the smallest ones are about 1.5 nm that are close to calculated sizes of hypothetic silicon "fullerenes" Si₆₀.

We describe two variants of a method for determining the average composition of insoluble immune complex particles (IICP). The first variant is based on measuring the specific turbidity (the turbidity per unit mass concentration of the dispersed substance) and the average size of IICP determined from dynamic light scattering (DLS). In the second variant, the wavelength exponent (i.e., the slope of the logarithmic turbidity spectrum) is used in combination with specific turbidity measurements. Both variants allow the average biopolymer volume fraction to be determined in terms of the average refractive index of IICP. The method is exemplified by two experimental antigen+antibody systems: (i) lipopolysaccharide-protein complex (LPPC) of Azospirillum brasilense Sp245+rabbit anti-LPPC; and (ii) human IgG (hIgG)+sheep anti-hIgG. Our measurements by the two methods for both types of systems gave, on the average, the same result: the volume fraction of the IICP biopolymers is about 30%; accordingly, the volume fraction of buffer solvent is 70%.

Three procedures for determining the average size of colloidal gold (CG) nanoparticles are described. The first procedure is the dynamic light scattering (DLS) method. The others are based on the estimation of extinction or differential static light scattering (DSLS, at 90 degrees) peak positions. Experimental studies were carried out with four samples of CG (the average DLS-diameters were equal to 15, 20, 25, and 30 nm). In the case of DSLS, the angular slope of the calibration curve "peak position versus particle size" was 2.4 times greater than the extinction curve slope. In experiments with controlled polydispersity, two different colloid mixtures were used. Extinction spectra of samples were almost identical, whereas the DSLS spectra showed noticeable differences with a red shifted maximum. The theoretical simulations by the Mie theory are in agreement with these experimental observations. The DSLS technique seems more reliable and accurate in CG particle sizing, as compared with the usual absorption spectroscopy.

In this study, we propose to apply the method optical coherence tomography (OCT) for paper characterization. A PC-controlled experimental measurement system for OCT-imaging of paper is described in detail. A superluminescent diode is used as a light source in a Michelson interferometer. A rapid scanning optical delay line is using a piezo-transducer to modulate the measurement signal for optical heterodyne detection. Amplification, filtering and demodulation are performed by the unit specially designed for this purpose. Experimental measurements include the OCT slice imaging of a paper sample and comparison with a SEM-image. Also some results in surface profilometry are presented briefly. Discussion part gives some ideas of further research that will be carried out in the future.

A procedure of inspection of femtosecond laser induced mass transfer processes has been suggested that is based on pump-probe Doppler tomography. In the experiments we used mode-locked Ti:sapphire laser with output power up to 150 mW.. In our experiments focused laser radiation induced on the surface of the target mass transfer processes (melting and convection). The Doppler shifted backscattered radiation was registered by heterodyne scheme based on Michelson interferometer. We have obtained information about depth and distribution of convection flows within melted paraffin bath with high spatial resolution (Dz~15mm). We propose optical heterodyning technique based on OCT for obtaining temporal distribution of backscattered photons from media irradiated by Cr:forsterite femtosecond laser. The temporal resolution is about 60 fs. The technique was used for sheet paper porosity diagnostics.

Flow velocity of scattering intralipid mixture within the glass capillary is measured using Doppler Optical Coherence Tomography (DOCT) technique. In the DOCT system, interference fringe frequency shift contains information about velocity of mixture. Due to scattering, interference fringe parameters are disturbed and stochastic fringe processing method should be used to evaluate fringe frequency. Interferometric signal frequency and other parameters have been estimated dynamically using discrete nonlinear Kalman filtering method. The stochastic filtering methodology and nonlinear Kalman filtering method are considered with application to experimental DOCT data processing.

The possibility to describe interference fringes by stochastic differential equations is demonstrated. Evaluation of interference fringes is based on the idea to define the interference fringe intensity variation as a nonlinear transform of supposed dynamic system evolution, where the system parameters like fringe amplitude, frequency and phase are described by the discrete stochastic differential equations. It allows realizing the optimal recurrence prediction-correction algorithms for dynamic fringe processing, in which fringe signal is predicted to a following discretization step using full information available before this step, and fringe signal prediction error is used for step-by-step dynamic correcting the fringe parameters. This approach has been applied to low-coherence interference fringe processing and 2-D fringe pattern analysis with the 2-D prediction procedure that increases the noise-immunity and data processing speed of fringe evaluation in non-destructive optical testing and material science.

The analysis of dependence of total errors for objects with different anisotropy and error distribution over elements of experimental Mueller matrix for dynamic (dual rotating retarder-DRR) polarimeter is carried out. These results discloses new direction and matter of optimization of the Mueller matrix measurement.

The solutions of spectral problem (i.e. finding eigenpolarizations and eigenvalues) can be used for the classification of polarization objects. The paper presents the classification based on spectral problem solutions, which determine the conditions when the polarization object either isotropically absorbs the intensity of incident electromagnetic radiation or isotropically shift the phase. This approach enables us to highly enrich the existing classifications and avoid their deficiencies.

Decomposition for the Jones matrix on the basis of matrices of circular and linear anisotropy was recently developed by Mar’enko and Savenkov¹, and extended on the Mueller matrix formalism by Savenkov and Oberemok in^2,3. The effect of experimental error on the decomposition as well as its transition trough the decomposition have been studied. The numerical experiment on decomposition of disturbed Mueller matrices is realized. The experiment is carried out within wide range of experimental error: from 0% up to 10%. As a result, it has been shown that the variance of the recovered parameters of anisotropy does not exceed an added noise up to its amplitude of 8%.

We describe here a method for tomographic reconstruction of the optical properties of a diffuse scattering object. The data are the integrated intensity (for absorption coefficient μa) and the mean arrival time (for reduced scattering coefficient μs), obtained from the temporal point spread function (tpsf) measurements. In both the cases we used a nonlinear optimization method to minimize the mean-squared error between the experimental data and the computed data. For computing the forward data, a diffusion equation is used as the model for light propagation. The main contribution of this work is the generation of the approximate location of the inhomogeneity in the object and its approximate value through a simple backpropagation of the data, which are input as a priori known starting information to the iterative reconstruction algorithm. Two advantages follow: (i) with background optical properties assumed to be known, the number of unknowns reduces to those inside the known inhomogeneity, which reduces the dimension of the inversion problem; (ii) initial estimate of the μa or μs values helps to get a quicker convergence to the actual solution. It is shown that without the a priori information from the backprojection algorithm, the inversion either took a much longer time or failed to converge.

It is well known that there are some difficulties with the analytical solution of the main equations in the general light transport and scattering theory, which is widely used today in the biomedical optics and optical noninvasive medical diagnostics, in particular, if the optical turbid media are taking into account. As we have reported in some our previous publications we assume that marked problems in biomedical optics follow from the not quite correct formulation of main equations of the classical transport theory in application to biomedical noninvasive diagnostic tasks. To study more detailed this problem we had taken into consideration one simple and 1D theoretical modeling task for which we have tried to obtain the simple analytical solution for the backscattered flux. This report highlights the way to obtain expected result and differences between classical and our modified approaches.

We had investigated experimentally distribution of scattered photons in medium with defined optical properties. A method bases on the theory of diffusion wave spectroscopy (DWS), basic term of which is "photon density wave". We applied our setup for modeling of human mucous tissue.

Two modalities for speckle contrast monitoring of tissue structure modification in the case of diffuse scattered probe light detection is discussed. The first modality is based on the detection of dynamic speckle patterns in the image plane of the image-transferring optical system while the other one is based on speckle detection in the diffraction zone. In the latter case the combination of the image-transferring lens and fiber-optical bundle is used in order to collect the scattered light and to deliver it to the detection unit. Experimental results obtained using both speckle techniques are presented.

Thermally induced irreversible changes in mechanical properties of collagen-containing tissue such as tendon are analyzed in order to characterize the process of thermal denaturation of the collagenous matrix in tissues. Based on a simple phenomenological model of a partially denaturated tissue as a binary system consisting of an amorphous phase (denaturated collagen) and a structurized phase (collagen fibrillar structure), the consideration of the temperature-dependent evolution of the elastic module of a thermally modified tendon tissue is carried out. The activation energy of collagen denaturation is estimated with the use of experimental dependencies of the tendon elastic module on the temperature and heating time, which have been obtained by M.S. Wall et al.

The possibility of using wavelet transforms for reconstruction of complex nonperiodic motion in optical homodyne in-terferometrie is presented. The numerical simulation of object motion function reconstruction using Fourier and wavelet transforms is performed, and results comparative analysis is examined.

Determination method of the mechanical vibration amplitudes by the spectrum of the autodyne signal of the semiconductor laser for the sphericity of the light wave front is described. The relation between the focusing of the laser beam and form of the autodyne signal was obtained. Measurements of the vibration amplitude of the piezoelectric plate were carried out with the help of the semiconductor laser autodyne system.

Paper is devoted to consideration of the method of first order side lobes suppression for acoustical fields excited by disc-shape radiator. Numerical simulations results of radiator optimized variant are presented. Offered method can be applied for sound radiation directivity diagram improvement, for example, in acoustical microscopy.

The acoustooptic images of volume and plane light-absorbing objects imbedded in a rectangular cuvette with a scattering liquid were obtained under the intermediate scattering conditions when μLC less than 35 where μ is an extinction coefficient and LC is the length of the cuvette along the laser beam axis. Photodetector collected the scattered and ballistic components of laser radiation, transmitted through the scattering medium traversed by focused ultrasonic beam. The alternating current at ultrasonic frequency was used as an imaging parameter. The characteristics of the alternating current were experimentally studied to optimize a registration of the component corresponding to the sound-modulated scattered light. The quality of the acoustooptic imaging was analyzed in dependence on the registration conditions, on the value of the scattering parameter and on the form and size of objects imbedded into the scattering liquid. It was obtained that under the used conditions the location of imbedded ultrasound-transparent objects in direction perpendicular to the laser axis was quite exact with the satisfactory contrast and sharpness as opposed to that along the direction of laser beam. An image contrast and sharpness in lateral flat of the volume objects were higher than that of plane figure.