ANGULAR DEPENDENCE OF TWO-PHOTON ABSORPTION IN CdP2

In CdP2 linearly circular dichroism and frequency dependence of the two-photon absorption coefficient р have been studied in detail, however, we do not know the value of the absolute value of в and its dependence on polarization azimuth. Purpose of research: testing of possibilities of direct method of measuring the coefficient of two- photon absorption in solids. Object of research - monorcycles CdP2. The research method is experimental. The angular dependence of the two-photon absorption coefficient CdP2 and the intensity of light at the sample output is established. When designing and manufacturing elements of power optics and correlators from univalent crystals, one must take into account the following dependencies. KEYWORDS: POLARIZATION, TWO-PHOTON ABSORPTION, CdP2, POLARIZATION AZIMUTH

Time since deaht estimation by the method of the three- dimensional-frequency polarizing maping filtering of polycrystalline cerebro-spinal fluid films images

There are many new methods ware researched in recent years for time since death estimation and laser polarimetric techniques are one of the most perspectiv of them. Thay have demonstrated the high accuracy and objectivity of biological tissue investigation for various intervals of post-mortem period. The purpose of the work. The post-mortem interval establishment by statistical analysis of the dynamics changes of coordinate distributions of values polarization azimuth (PA) of the polycrystalline films of liquor (PFL) using the three-dimensional-frequency filtering method of biological multiscale layers investigation. Materials and methods. Objects of investigation are PFL, taken in 67 corpses with accurately known time of death and 6 healthy volunteers. Coordinate distributions of PA image values were estimated for each sample of PFL in the optical arrangement of the Stokes polarimeter using the method of two-dimensional distributions of Stokes-parameters measurement. The value of statistical points of the 1 - 4 th order was perfomed for each two-dimensional distribution of PFL images PE values. Statistical processing of the calculated values of set of points that characterize the PA distributions within representative sampling was carry out. The depending on the time change of the most sensitive points of statistical values were built to achieve values stabilization. Results and conclusions. Optimal interval in 30 hours and the accuracy of the time since death determination 80 min for the large-scale component of polycrystalline films of liquor and optimal interval in 14 hours and the accuracy of the time since death determination 30 min for the small-scale component of polycrystalline films of liquor were established by the method of two- dimensional Stokes-polarimetric mapping of liquor images polarization azimuth values distribution.

Observation of Optical Soliton-Like Propagation in Dye-Doped Nematic Liquid Crystals with Homogeneous Alignment

Nonlinear light propagation in a dye-doped liquid crystal (LC) was investigated experimentally. A laser beam with wavelength far from the absorption peak of the material was coupled into an LC cell with homogeneous alignment, and the propagation in the cell was observed. When the polarization azimuth of the incident light was orthogonal to the orientation direction of the LC, soliton-like propagation was obtained for milliwatts of light power in spite of the low absorption. We clarified that the observed nonlinearity is due principally to the photothermal effect enhanced by the dye.

High-precision estimation of split PS-wave time delays and polarization directions

The measurement of split PS-wave time delays and polarization directions is notoriously difficult in field data, partly because the signals are small and overprinted by competing mechanisms. This contribution describes a new processing method that suppresses many of the overprinted traveltime and amplitude anomalies, allowing depth-averaged split PS-wave time delays and polarization directions to be measured simply and precisely. These depth-averaged properties are then inverted using a simple forward model, allowing an earth model of split PS-wave time delays and polarization azimuths to be estimated without the need for layer stripping. In the field data used as an example, the processing and inversion methods are used to estimate split PS-wave time delays and polarization directions for ten layers spanning about 500 m depth from the seabed downward. Inversions using data-error covariances estimated from prestack data show model uncertainties less than 0.3 ms of time delay and 3° of polarization azimuth. However, it is clear that if the data-error covariances cannot be estimated from prestack data, due to low fold for example, model uncertainties would rise considerably. Repeating the inversions using data-error covariances of a postulated form leads to a range of maximum-likelihood models. When the data-error covariances cannot be estimated from prestack data, it seems reasonable to report precision levels implied by the spread of maximum-likelihood models, which in this case is up to 0.5 ms of time delay and 20° of polarization azimuth. The principal achievement of this processing and inversion scheme is to constrain a relatively large number of depth layers with similar levels of model uncertainty. The depth resolution available to this new method may have important implications for the development of tight-gas and shale-gas plays, in which variations of stress, strain, and fracture properties in discrete layers are important.

Modeling Reorientation Dynamics of Electrically Assisted Light-Induced Gliding of Nematic Liquid-Crystal Easy Axis

The phenomenological torque balance model previously introduced to describe the electrically assisted light-induced gliding is generalized to study the reorientation dynamics of the nematic liquid crystal easy axis at photoaligned azo-dye films under the combined action of in-plane electric field and reorienting UV light linearly polarized at varying polarization azimuth,φp. We systematically examine the general properties of the torque balance model by performing analysising the bifurcations of equilibria at different values of the polarization azimuth and apply for the model to interpret the experimental results. These involve observation of the pronounced purely photoinduced reorientation atφp≠0, as opposed to the case where the light polarization vector is parallel to the initial easy axis (φp=0), and the reorientation is almost entirely suppressed. In the regions between electrodes with nonzero electric field, the effects described by the model are that (a) the dynamics of reorientation slows down withφpand (b) the sense of easy axis rotation is independent of the sign ofφp.