Dependence of optical properties of gold solid nanospheroids and spheroidal nanoshells on the dielectric environment has been studied in comparison with standard spherical models, i.e. with solid spheres and spherical nanoshells, respectively. The extinction and light scattering spectra were calculated using Mie theory, T-matrix, and the separation of variables methods. The sensitivity of plasmon resonance (PR) tuning to variations of the refractive index (n=1.3-l.7) was studied for particles with different equivolume size. In the case of nanoshells, the metal layer thickness was also varied. For nanoparticles with 15-nm equivolume diameter, the maximal PR shifts are observed in the case of spheroidal nanoshells and the calculated PR shifts decrease in the order: spheroidal nanoshells, solid spheroids, and spherical nanoshells. For particles with the 60-nm equivolume diameter, almost equal PR shifts are observed both for solid spheroids and spherical nanoshells, whereas the spheroidal nanoshells exhibit the maximal PR shifts. Other things being equal, the PR of silver nanoparticles is more sensitive to the dielectric environment as compared to the gold counterparts.

We describe synthesis process of an oligonucleotide-functionalized colloidal gold marker CG-l5-T₂₈, its optical properties and interaction with poly(A) in solution and on a solid-phase substrate. The marker is a complex of 15 nm diameter colloidal gold nanoparticles with covalently attached 5'-thiolated 28-base oligothymidine macromolecules. A positive hybridization reaction of the marker with poly(A) is observed by solid-phase analysis on hanging a spot color (from red to blue ) or on appearance of a red dye in dot-blot test as compared to control experiments with poly(U) target. The principles of spectrophotometric monitoring all stages of the marker preparation and application of spectrophotometry to detection of the polynucleotide hybridization in vitro are described. Experimental data were compared with theoretical calculations based on Mie theory for 2-layer model of gold core in polymeric shell with imaginary part of refractive index that typical for the real absorption spectra of NA. To explain the aggregation of CG-15-T₂₈ caused by interaction with poly(A) in solution, we suggest a new model differing from a standard model of cross-linker binding.

We report on a synthesis procedure and optical properties of composite Au-Ag spherical and rod-like nanoparticles. The synthesis protocol is based on a seed-mediated growth in the presence of soft templates in micellar aqueous solution of ionic surfactant (CTAB). Variation of Au/Ag molar ratio allows one to produce nanorods (NRs) with different aspect ratio. The disadvantage of the method is formation of appreciable amount of spherical nanoparticles. To separate rod-like particles from spheres and surfactant, we used a fractionation procedure that involves centrifugatiori of samples in the density gradient of glycerol. The separated NRs were suspended in water or 25% glycerol solutions and their extinction and differential light scattering (at 900) spectra were recorded for 450-850 ni-n wavelengths. Theoretical spectra were calculated by T-matrix method as applied to randomly oriented gold cylinders with semispherical ends. The simulated spectra for water and glycerol suspensions can be brought in close agreement with experimental observations if the aspect ratio is used as a fitting parameter. We discuss also the absorption and light scattering contribution to the total extinction spectra and deviation of the exact solution from the classical electrostatic approximation by Gans.

We consider integral transforms that can describe ideal imaging optical systems with circular impulse response. The integral transform, referred to as the Circular Radon transform (CRT), is considered as an average taken along all circumferences of fixed radius on the plane. The CRT can be optically realized using a Fourier correlator with amplitude filter, with its transmittance function being proportional to the Bessel function of zero order. Also, a mesooptics transform (MT) is considered that can be optically realized using a Fourier correlator with axicon in the spatial-frequency plane. An ability of applying the CRT to realize traditional Radon transform optically has been tested.

In this article the possibilities of different laser beams regeneration after an obstacle that can be the microparticle, trapped by the beam, are examined. The comparative analysis of regeneration properties of the Bessel beams, the Gauss-Laguerre modes and other beams, containing angular harmonics, is made. The forming of such beams has the maximum effectiveness with the help of phase diffractive optical elements. The experimental results of the Bessel beams regeneration, including those ofnone-zero order, are presented.

The phenomenon of longitudinal spatial coherence of light and conditions of manifestation of this type of coherence in the interference experiments with Michelson interferometer are discussed. Manifestation of longitudinal spatial coherence of light of an extended thermal source at large (in comparison with length of longitudinal spatial coherence) and short lengths oftemporal coherence oflight has been experimentally shown.

The terahertz (THz) absorption spectra of plasmon modes in a grid-gated double-quantum-well (DQW) field-effect transistor (FET) structute is analyzed theoretically and numerically using the scattering matrix approach and is shown to faithfully reproduce strong resonant features of recent experimental observations of THz photoconductivity in such a structure. No traces ofthe interwell plasmon is found in THz absorption spectra.

On the basis of the generalized integral Mueller matrix of homogeneous anisotropic medium (Mar'enko and Savenkov, Optics and Spectroscopy, 76, 94-96, 1994; Savenkov, Chapter 4 in "From spectroscopy to remotely sensed spectra of terrestrial ecosystems," R.S. Muttiah, Eds., Kiuwer Academic Publishers, Dordrecht, The Netherlands, 2002) it is derived the correspondent differential Mueller matrix. The example of utilizing of the differential Mueller matrix for a phase medium to an approximation of linear dependence of anisotropy parameters from coordinate in propagatibn direction is presented.

The analysis of Mueller matrix measurement errors, total and for each of the matrix elements, for time-sequential Mueller polarimeter in the case of utilizing different types of Stokes polarimeters in receiving channel are carried out. The consideration concerns of two types of Stokes polarimeters: polarimeter based on four angular orientations of retarder and polarimeter based on phenomenological definition of the Stokes vector. It has been shown that the measurement errors depend on the type of anisotropy characterizing the studied object and the azimuth of linear anisotropy. This gives the extra opportunities for the reduction of errors of the Mueller matrix measurements.

The properties of the objects, which can be formed on the basis of only the deterministic and isotropic depolarization mechanisms, are studied. We found a test of attributing to this polarization class. The algorithm of the synthesis of objects attributing to the class has been presented.

In this paper the results for measurements of the Mueller matrices of Chlorophytum leaf, of upper and down side epidermis of Chlorophytum leaf are presented. To physically identify the multiplicative model of a Chiorophytum leaf basing on its Mueller matrices, the coherency matrix, its eigenanalysis and matrix of homogeneous anisotropy are discussed.

Potentials of two modalities of skin diagnostic with focused and expanded linearly polarized probe light are studied. For the focused beam (wavelength 650 nm) the photometric patterns of light backscattered from skin and collagenous tissue phantoms were recorded using digital camera. It is shown that equiintensity contours are well fitted with ellipses that appeared to follow the orientation of collagen fibers. In the peripheral zone from the entry point of the probe beam the ratio of the ellipses semi-axes is correlated with the ratio ofreduced scattering coefficients obtained from intensity profiles. In the vicinity of the entry point it depends on the mutual orientation of polarization vector and collagen fibers. For the expanded probe beam the digital mapping of the residual polarization degree of backscattered linearly polarized light allowed visualization of the hidden structure of earlier fibrosis of the mouse skin arisen from X-ray treatment. The structure of the skin fibrosis was enhanced using Fourier transform filtering of polarization degree pattern. The pattern scanning with Pearson correlation coefficient was developed to determine the orientation and characteristic size of hidden structure. Both modalities may be potentially used for diagnostic ofskin abnormalities, such as fibrosis.

The results of experimental study of influence of macroscopic optical anisotropy and scattering properties of tissue samples on their optical polarization characteristics, which can be measured in simple polarirnetric experiment, are presented. In-vitro samples of animal tissue (rat skin) were examined in these experiments. The experimental technique used is based on the detection of the intensities of the co- and cross-polarized components of the light transmitted through the scattered medium, which is rotated between two polarizes. It is shown that the whole rat skin has macroscopic optical birefringence with the average difference ofrefractive indices Δn ~ 0.00024.

The correlation structure of 2-D Stokes vector parameters of physiologically normal and pathologicaly changed biotissues is investigated. The totality of diagnostically urgent interconnections between biotissue physiological state and statistical moments of 2-D Stokes vector parameters is found.

The interconnection between geometry of biotissue structure and their polarization properties has been studied. It has been shown that for physiologically normal biotissues polarization properties of radiation scattered on architectonic nets formed by protein fibrils possess the fractal character. Pathological changes of biotissues architectonics are accompanied with the transformation of self-similar structure of Mueller-matrix images into stochastic and statistic ones.

The possibilities of characterization of the relaxation processes in thermally treated collagenous tissues with the use of the cumulant analysis of speckle intensity fluctuations are discussed. This method deals with the correlation analysis of spatial-temporal fluctuations of laser light multiply scattered by thermally modified tissue under the condition of polarization discrimination of detected speckle-modulated optical signals. Experimental results, which were obtained with ex-vivo cartilage samples, are presented.

Optimization of nonlinear discrete Kalman filtering computational process is considered in application to dynamic processing of interferometric signals in Optical Coherence Tomography. Processing speed of low-coherence fringe signals is assessed when using discrete nonlinear Kalman filtering algorithm implemented by Intel Pentium 4 processor.

Fringe pattern analysis is widely used in moire, holographic and speckle interferometry for solving problems of nondestructive testing of objects. In the paper, the method of analysis of noisy fringe patterns and fringe phase retrieval is considered. The method is based on iterative evaluation of fringe amplitude, local fringe step (frequency) and local fringe orientation. High noise-immunity of the method proposed was verified experimentally when processing complicated fringe patterns with recovering full fringe phase.

Some results obtained with developed high resolution scanning acoustical microscope are shown in present paper. Designed and developed system is capable for capturing both bulk acoustical images, as well as the plane images obtained as cuts in desirable section of an object; so, so-called B-scan as well as C-scan are realized. Created systems provided with the set ofacoustical objectives for working frequencies from 25 MHz to I GHz having different apertures of sound beam and different focus distances. Results of investigation of technical and biological objects are briefly discussed.

We introduce a CCD camera detection scheme in dynamic light scattering that provides information on the single-scattered auto-correlation function even for fairly turbid samples. Our approach allows access to the extensive range of systems that show low-order scattering by selective detection of the singly scattered light. Model experiments on slowly relaxing suspensions of latex spheres in glycerol were carried out to verify validity range of our approach.

Optical tomography (OT) recovers the cross-sectional distribution of optical parameters inside a highly scattering medium from information contained in measurements that are performed on the boundaries of the medium. The image reconstruction problem in OT can be considered as a large-scale optimization problem, in which an appropriately defined objective functional needs to be minimized. Most of earlier work is based on a forward model based iterative image reconstruction (MOBIIR) method. In this method, a Taylor series expansion of the forward propagation operator around the initial estimate, assumed to be close to the actual solution, is terminated at the first order term. The linearized perturbation equation is solved iteratively, re-estimating the first order term (or Jacobian) in each iteration, until a solution is reached. In this work we consider a nonlinear reconstruction problem, which has the second order term (Hessian) in addition to the first order. We show that in OT the Hessian is diagonally dominant and in this work an approximation involving the diagonal terms alone is used to formulate the nonlinear perturbation equation. This is solved using conjugate gradient search (CGS) without re-estimating either the Jacobian or the Hessian, resulting in reconstructions better than the original MOBIIR reconstruction. The computation time in this case is reduced by a factor of three.

Zernike Polynomials have been successfully used for many years in optics. Nevertheless there are some recent discussions regarding their accuracy when applied to surfaces such as the human cornea. A set of synthetic surfaces resembling several common corneal anomalies was sampled and was also used to compute the optical path difference using a simple ray-tracing procedure. The Root Mean Square Error between the Zernike Polynomials fit and the theoretical elevation and WF error surface was computed for both surfaces and for all number of Zernike terms. We have found that RMSE for the simplest, most symmetric corneal surface (spherical shape) and for the most complex shape (post-radial keratotomy) both the optical path difference and surface elevation, for 1 through 36 Zernike terms, range from: 421.4 to 0.8 microns, and 421.4 to 8.2 microns, respectively; mean RMSE for maximum Zernike terms for both surfaces were 4.5 microns. Computations in this work suggest that, for surfaces such as post-RK, keratoconus or post-keratoplasty, even more than 36 terms may be necessary in order to obtain minimum precision requirements. We suggest that the number of Zernike Polynomial should not be a global fixed conventional value but rather based on specific surface properties.

The possibility of the reconstruction of a complex non-harmonic function of the moving object by means of autodyne interference system is represented in this work. The results of the experiment show the possibility to determine the parameters of complex nonharmonic movements of the reflector. It is obvious that the use of multistage digital filtering in the course of autodyne experiment allows us to reduce the influence of the noise distortion on restored signal.

The algorithm of analysis of videoirnage of tread pattern trace has been presented. The videoimage comparison is carried out with the help of image subtraction method. Realization of method of recognition of tire tread pattern has been described. The experimental results are given.

By analyzing spatial distribution of the laser radiation modulated by ultrasound (the ac photocurrent at ultrasonic frequency) in scattering medium, images of some optical inhomogeneities have been obtained. The signal registration conditions corresponded to the optimal ones to measure the ballistic component of scattered laser light. The changes of the acousto-optic contrast and sharpness were investigated in dependence on the form and size of the absorbing light objects and on the scaftering medium parameters. The image quality of plane and volume buried objects with an equal section in plane orthogonal to the laser radiation axis was similar, quite high, and didn't depend on the object position along this axis.

We report the results of experiments conducted to determine optical and mechanical properties of tissue mimicking phantoms that are designed for optical elastography. In optical elastography the readout mechanism for displacement is optical, and the mechanical and optical properties of the phantom are to be tailored to match those of the tissue being imaged. The optical characterization is based on diffusive nature of light propagation including scattering anisotropy and boundary reflection. The anisotropy factor (g) is measured using a relatively thin sample (where single scattering assumption is valid) through experimentally measuring the angular intensity transmittance. The measured intensity distributions are fitted to, known theoretically available intensity distributions, which have scattering anisotropy (g) as one of the parameters, to extract g. The scattering coefficient (μ_S) and refractive index (n) are obtained using a thicker slab (multiple scattering regime) from where angle-resolved intensity transmittance is measured. Computed intensity distributions using Monte-Carlo(MC) simulations are curve fitted to extract 'μ_s' and 'n' which are used in the Monte-Carlo simulation. The visco-elastic properties such as frequency dependent elastic and loss moduli of the phantom are determined by measuring the complex modulus using a dynamic mechanical analyzing system.

Temporal fluctuations of coherent light scattered by ensembles of particles with a complex character of motion are studied on the base of Monte-Carlo simulations. The developed statistical models are considered to mimic some features of bacterial motility, which appear due to various physical and chemical factors (e.g. presence of attractants, existence of temperature gradients, etc.). The relation between the scaling properties of intensity fluctuations and that of scatter motions is analyzed in application to characterization of scattering systems with complex scatter dynamics.

Monte-Carlo technique is applied to study the light transport from a localized light source in layered multiple scattering media with the expressed macroscopic anisotropy of underlying layers. The shape and orientation of the equal intensity profiles and the pathlength distributions of backscattered light are analyzed in the dependence on the distance between the source and detection point. Obtained results are compared with the experimental results obtained by other authors in the experiments with tissue phantoms and in-vivo human and mouse skin.