An optical path is an open thermodynamically nonequilibrium, spatially heterogeneous, non-stationary system. It can be described as a multicomponent set of elementary volumes in heat and mass transfer. In each system, at a given time interval, the thermodynamic equilibrium with the Boltzmann factor takes enough time for being established. The spatio-temporal parameters of the medium are "imprinted" in the modulation of the optical density of the channel and, accordingly, in the spatio-temporal modulations of the intensity and radiation pattern of signal beams. It is convenient to base the experimental control of the path state on the temperatures set at the control points and on the temperature distribution function.
An analysis technique is described within of the non-extensive Tsallis thermodynamics for experimentally recorded time scans, for displacement vectors, and for the drift velocity of the beam energy center. The variations of the Boltzmann-Gibbs entropy, the q-deformed Tsallis entropy and the available states number of the statistical ensemble of the recorded positions of the collimated wave beam energy center and its drift velocity are determined. To determine the type of attractors of the studied stochastic process, the spectra of Lyapunov exponents for the positional parameters of the wave beam are analyzed.
The amplitude distribution complex structure of the optical beam profile at the end of a long atmospheric path can be considered in terms typical of surface profile descriptions used in solid state physics or geophysics. The characteristic values for such approaches are based on the geometry analysis of constant level curves, directions of steepest descent from a given point on the surface and quadratic combinations describing the deformation of the analyzed surface. The matrix of local orientation values determined on the basis of the first spatial differentials is unique for the image. It can be used as a basis for describing the of the initial intensity distribution. Differential characteristics of the spatial structure make it possible to classify distortions of the beam profile by types of symmetry and direction of deformations. Differential characteristics of the spatial structure make it possible to classify distortions of the beam profile by types of symmetry and direction of deformations. It's possible to associate the observed spatial parameters with the meteorological conditions on the path and in the first approximation, restore the main directions of phase modulation in the observation plane.
Detailed analysis of optical cascades is usually performed using the matrix method of optics, which allows us to determine the transformation matrix of coordinates and the incidence angle of the beam for each element of the cascade. The convenience of matrix description lies in the unity of approach to both ray and wave propagation problems. A series of symmetrical and asymmetric optical cascades that are optimal for turning a wave beam in phase space and do not have forbidden rotation bands are considered using matrix optics methods. For the simplest symmetric two-lens cascades, the tuning characteristics are obtained that allow setting the rotation angle in the range ±π. Rotation control is performed by adjusting the external or internal "run" of the beam between the lenses. For specific cascades, the geometry of the forbidden zones of turns, physical analogs of turns at a complex angle are analyzed.
We have considered the problems of full-view matrix recorders of signals and energy wave beams for telecommunications, remote sensing and wireless energy transfer. The results of an experimental study of the temperature field being formed when working with sources of continuous coherent radiation of high power, inhomogeneous thermal degradation of the integral efficiency of the converter has been presented. We have also studied the influence of the energy-carrying beam form factor on the structure of the recorded signal and the efficiency of photoconversion. The problems of the thermal response of the photoconverting matrix have been considered when working on the borders of the quantum yield band of silicon photoconverters.
The approximating dependencies for the spatial characteristics of the intensity distribution of the wave beam in the registration plane are proposed. Was formulated algorithms for control the rotation of a profile without changing its structure, allowable tensile and compression deformities along selected directions. A three component multiplicative form for the ABCD matrix of the optical system-converter of the wave beam profile is discussed.
The experimental results of the time-frequency maps structure research are presented. The maps were received on the basis of Cohen class square mapping, particularly, using Wigner-Ville pseudo-distribution. Quasi synchronous monitoring of the atmospheric channel conditions and of a beam intensity spatial distribution is realized by means of the high-speed cameras of computer vision. The cameras record dynamics of a profile intensity distribution of a single-mode collimated signal beam at the receiving plane and that of the reflected sounding multimode beam. At an input of the long distance atmospheric path there comes the generalized Gaussian signal beam with the defined Rayleigh length and wavefront curvature. At the path output the spatial moments of the beam from the zero to the fourth orders are registered. The spatial moments allow to describe in details beam distortions along the propagation path with the temporary resolution not less than 1 ms.
Statistical and nonlinear dynamic properties of the vector components and spatial moments tensors for the intensity distribution profile of wave beam at the output of an atmospheric path are considered. As a reference parameter characterizing the state of the atmospheric path Rytov parameter was chosen. The ambiguity of the relation between the Rytov parameter and the dispersion characteristics of positional parameters for a collimated beam is proved experimentally.The methods allowing to select the number and type of regressors for predicting the beam profile variations at the temporal microscales are discussed.
The applicability of the returned spatial intensity distribution and its variation in time is discussed for the investigation of nonequilibrium and nonstationary properties of the optical path, in particular, for determining the degree of turbulent distortions, thermal nonequilibrium, transverse crosswind. The results of an experimental analysis of the spatial structures obtained in the focal plane of the registrator are considered for the case of collimated laser beams reflected from a retroreflector for the 1000 m inclined atmospheric path.
The photoconversions efficiency of powerful collimated coherent single-mode and multimode wave beams with λ= 808 nm and 1064 nm was studied and the experimental results are presented. A set photocells based on silicon with different topological structure is considered including monofacial and bifacial cells, as well as those that have a vertical orientation. Photocell characteristics (short-circuit current Isc, open-circuit voltage, Voc and fillfactor) obtained in the temperature range from 25°C to 50°C and also at a beam power, P, of up to 100 Suns are discussed.
The functional expansion of the operating model of a slightly inclined lengthy atmospheric path is described. The experimental setup contains the module of signal beam profile control, the module of a path state active meteooptic control and the module of a beam inclination adaptive correction. The testing results for the designed hardware-software complex under the on-line monitoring of dynamic and stochastic optical parameters of the path are presented. The spatial anisotropy of stochastic and dynamic parameters of the path and the beam was investigated experimentally. The tests of hardware-software adaptive control module for the beam energy center control were carried out using a combination of proportional, integral and differential correction algorithms with the demonstration of the response anisotropy on adaptive impact.