The use of the laser Doppler technique for measuring Lagrangian acceleration with a high spatial resolution is introduced. The requirements in system alignment and accuracy of signal processing is estimated. Specifications of the optical design and the signal processing are given.

In this paper, offered and explored are some principles for construction of a laser Doppler measuring system on the basis of an active interferometer with feedback and frequency bias. Presented is a block-diagram of the sign-sensitive laser Doppler velosimetr (LDV) and results of its metrological investigation. The errors of this LDV can be reduced down to 0.01%. Some theoretical questions are discussed as self-mixing LDV accuracy, Doppler signal spectrum width, the number of virtual interference fringes in the measurement volume. As well the self-mixing LDA pros and cons are discussed.

The analytical expressions are obtained for the energy ratio of high-frequency Doppler signal coherent and noncoherent components as functions of the inhomogeneities concentration and the optical scheme parameters. The problem has been solved for the light intensity in the photodetector plane, for the flat scattering surface and differential optical scheme of the Laser Doppler Anemometer (LDA). It is shown that said energy ratio is directly proportional to the inhomogeneities concentration and inversely proportional to the numerical aperture of the photodetector. Boundary values of the concentration are specified at which the effects of the coherent and noncoherent components are equal. It is shown that effect of the coherent component essentially grows for small photodetector apertures and high inhomogeneities concentration.

Optical Coherence Tomography (OCT) and Optical Coherence Doppler Tomography (OCDT) signals from one and two plain flows of a non-aggregating particulate suspension mimicking blood embedded into a stationary light scattering medium (2% Intralipid solution) with optical properties close to those of human skin were simulated implementing the Monte Carlo method. The role of multiple scattering in the OCT signals was analyzed. The maximal visualization depths for OCT imaging of different biotissue-like samples were estimated. It was shown that with an increase of embedding depth of the flow the reconstructed velocity values are smaller than the predefined ones and the reconstructed profile is stretched towards the rear border. In the case of two flows, it was shown that with an increase of the first flow velocity the reconstructed velocity values of the second flow increase too.

The research results of characteristics of various algorithms of PIV-images digital processing, obtained by a method of computer modeling, are considered. The comparative analysis of estimation methods of the shifts field of the PIV-images elements (a method of cross-correlation, a method of the minimum quadratic distance, a method of weighing and a phase method) is carried out.

Likelihood equations for optical signal with the shot noise and background noise were obtained. Computer simulation of its solution was performed for Gaussian pulse as for an example.

Experimental checking the method of the computer analysis interference fringes not requiring operations of the deployment of the phase is described. When use two with different length of the waves interferogram method gives the unambiguous result at differences of the optical move equal several hundreds lengths of the waves. The method can be easy widespread on all types of the phase measurements, including in radio and acoustic range.

The problem of image processing by nonlinear phenomena at the process of stimulated scattering of light simultaneously at different wavelengths is investigated. The influence of nonlinear effects and excitation conditions (the initial light intensity and excitation geometry) is considered. Experimental results and theoretical model of the image reconstruction are presented.

The distortions of a laser beam field caused by refraction effects are investigated. We solve the problem in the approximation of geometrical optics using methods of eikonal and amplitude perturbation. The intensity envelope distortions caused by convergence and divergence of geometrical rays inside the laser beam is analyzed. Analytical expressions describing the trajectory of a laser beam propagating in a medium with a weak perturbation of the refractive index caused by an acoustic wave are derived. The effects related to the spatial boundedness of the beam are studied. Based on a unified representation valid for a wide range of ratios of the acoustic wavelength to the beam radius, an interpretation of the refraction effects is presented. The distortions of the beam phase resulting from ray's refraction and corresponding increase of optical path are analyzed. The phase distortions are shown at an interference of two laser beams, for example in laser Doppler anemometer (LDA) applied for sound field diagnostics. An experimental setup has been designed to verify the theoretical investigations and to measure the acoustic field parameters. The values of the beam intensity deviations caused by refraction effects are measured and good agreement with calculation is obtained. The results derived may be used for recommendations giving for performing LDA measurements in the presence of acoustooptic effect (AOE).

Results from experimental spectropolarimetric researches in sodium vapors on 3s-3p transition and in a neon gas discharge on 1s₅-2p₂ and 1s₅-2p₄ transitions are submitted. The technique of the quantitative data reception on limiting sensitivity of measurements atomic systems as ground states, and metastable one's is described. Opportunities of a method in researches of the rarefied streams of molecular nitrogen are analyzed.

New approach to surface oil-flow visualization is suggested. This method can be called as Particle Image Surface Flow Visualization. The idea of new method is to register some small shift of oil film applied on investigated object surface and to restore the complete pattern of surface flow numerically. For this purpose some optically contrast hard particles are added to the oil film and two images of particle distribution at some time interval are acquired at the investigated test parameters. Pairs of images are processed with cross-correlation analysis similar to analysis used in Particle Image Velocimetry method to obtain the parameters of particles movement. Magnitude of particles shift is proportional to shear stress value that allows to determine separation zones, shock waves and boundary layer transition on investigated surface. Direction of particles shift is coincident with direction of surface streamline that allows to restore surface streamline pattern on investigated surface. Since only small shift of oil film is analyzed, multiple tests with different airflow parameters can be made using single model preparation. The results of method application for visualization of the flow from flat nozzle on the flat plate, for airfoil tests at low Reynolds numbers and for toy-car model tests at low Reynolds numbers are presented.

A solution to the phase problem in optics is considered within the context of the analysis of time-dependent signals. The analysis concerns, in particular, determination of amplitude and phase structure of signals and processes of ultrashort duration. The operation of the scheme is based on the registration of two spectra of the investigated radiation separated spatially. The first spectrum corresponds to the signal directly, while the other one is formed by summation of two spectra shifted geometrically with respect to each other by a distance of the order of the spectral device resolution. The description of the summarized spectrum contains the frequency derivative. The information obtained allows one to determine the amplitude and phase structure of the signal.

Diagnostics of the local and field characteristics of moving medium in tasks of hydrodynamics, gas dynamics and geochanges, measurement of the local velocities and the fields of velocities in flows, the radial fluctuations of the earth's surface, research of the dynamic structure of shock waves and the dynamic disturbances induced by the shock wave in the air are discussed.

For solving of actual problems in material science, industry TDI SIE SB RAS has developed some 3D opto-electronic measuring technologies and systems for dimensional inspection. Applications and results of industrial testing of laser measuring machine, opto-electronic shadow system and optical low-coherent radar as well as automatic laser diagnostic system for ensuring the safety in atomic and railway industry are discussed.

The results of effective application of different visualization methods complemented each other in industrial aerodynamic wind tunnels are presented. These methods allow one to visualize the peculiarities of flow field over flying vehicle models, to understand the nature of aerodynamic performance changes (especially in the case of integration of visualization with balance tests), to improve aerodynamic characteristics and accuracy of their extrapolation to flight conditions.

For hydrodynamic examinations of the turbid three-phase streams with air bubbles and with a depth more than 500 mm for the first time it is developed 2D Laser Doppler Semiconductor Anemometer LADO5-LMZ. Anemometer signal processor base on <> and new procedure of adaptive selection of Doppler frequency. Complex testing of method and measuring tools have been done. Outcomes of full-scale experiments on diagnostic of nonstationary flow behind the vane wheel rotor in draught tube of the Frensis water turbine are presented from optimum regimes of activity to forced. Water discharge which has been calculated from water turbine universal performance model and calculated by measuring axial velocity profiles was compared. It is shown that the maximum aggregate error of definition of the consumption does not exceed 5%.

The purpose of the work is the theoretically and experimentally investigation of Gaussian laser beam diffraction by a single particle or gas bubble moving in a liquid. The size of the bubble or particle is assumed to be comparable with the radius of the beam. The results of this investigation are applied to develop and implement the technique for simultaneous measurements of the bubble or particle radius and velocity. It is shown that the field diffracted by a bubble exceeds the refracted and reflected fields in the beam propagation direction. The diffracted field is simulated using the scattering theory for a spherical particle based on the Kirchhoff approach. In addition to scattering on bubbles or spherical particles diffraction by a moving cylindrical particle is analyzed. An experimental setup has been designed to verify the theoretical background of the technique. The fields radiated by the central part of the laser beam and scattered by a particle or bubble in the forward direction are incident on the photo detector placed at the center of the observation plane. As a bubble or particle moves, the diffraction pattern (diffraction shadow) shifts over the observation plane. This results in variations of the photo detector output current. It is shown that the radius of the laser beam that is optimum for measurements should be approximately equal to the radius of the first Fresnel zone. Based on the research results, recommendations for the choice of the setup parameters and for determination of the measurement error are given.

We describe and analyze the experimental realization of the speckle interferometry scheme designed to measure deformation of an object surface. It can be shifted along the surface itself as well as turned or inclined. In contrast to the classical speckle interferometric schemes, we use a specially formed two-dimensional pattern of random binary structure as a speckle structure. The pattern being illuminated by the white light is photographed with the use of a digital camera. Further processing of the information related to the Fourier transformation of the pictures registered and determination of the obtained fringe structure period is carried out in PC.

The operation of the laser system for turbulence diagnostics with the hybrid fiber-optic sensor (HYFOS) in a mode of the digital photographic recording of the 2-D accumulated signal is investigated. The accumulated signal allows obtaining direct estimations of 2-D turbulent fluctuation probability density functions defining processes of turbulent transport. The effective velocity range may be adjusted widely by change of the geometrical and physical properties of the sensitive fiber optic unit. The results of computer simulation and test measurements in an air turbulent jet and the comparison with LDA measurements as well as considerations for ambiguity and transfer function of the sensor are given.

Specific features of application of Pressure Sensitive Paint (PSP) method for propeller blades investigation are discussed. Pressure fields on both sides of the blade of twin-blade propeller model were measured by PSP. The model was investigated at rotation rates up to 5300 rpm at blades pitch angles 15°, 35° and 45° without external airflow. Propeller thrust, torque and blade pitch moment were calculated. Thrust and torque were also measured by balance. Good agreement between PSP and balance results can confirm the reliability of PSP measurements on propellers.