Acoustooptical phenomenon was anticipated theoretically by L. Brillouin in 1922. These anticipations were confirmed experimentally 10 years later. In the following years the influence of elastic wave on light wave propagation was described from many points of view, examined experimentally, and applied in practice. The first works describe interaction of unlimited plane waves but the fundamental meaning for practical applications has the description of real wave beams’ interaction. This problem still exists despite huge progress made in acoustooptical phenomenon’s investigations. Among numerous description methods applicable to various, specific acoustooptical interactions are also such ones, that make it possible to describe interaction of beams of arbitrary spatial distributions. However, in today’s applications of acoustooptical phenomenon such as modulators, filters, spectrum analyzers, etc. one uses mostly laser light. Light beams emitted by laser may in many cases be described as gaussian beams. It means, that the correct description of acoustooptical interaction involving optical gaussian beams has significant practical meaning. This paper presents the review of theoretical works describing acoustooptical interaction between optical gaussian beams and acoustical waves. Special attention has been paid the application of complex geometrical optics’ methods.

Theoretical and experimental investigation of collinear diffraction of divergent optic beams by ultrasonic waves near by the direction [110] of paratellurite crystal has been carried out. The diffraction has been examined in direction [110] forbidden in TeO₂ for acousto-optic interaction in the case of plane waves. It has been shown that the collinear diffraction along this direction exists only for divergent light and sound waves while efficiency of the diffraction increase with the growth of the divergence. The effect has been examined at the acoustic frequency f≈ 149 MHz and the wavelength of the non-collimated light λ=633 nm with the optical spreading up to 4°. A collinear acousto-optic filter on paratellurite applying the diffraction has the length of interaction l=2.7 cm. It has been proved the acoustic attenuation causes a decrease of efficiency of the diffraction and a broadening of a bandwidth of the device. The spectral resolution value as high as R~3000 has been obtained a λ=633 nm. The diffraction efficiency I₁/I₀≈0.8 and the wide angle aperture Δφ≈4° give perspectives to use the collinear diffraction in filters on the base of TeO₂ crystals.

ΩPropagation and reflection of plane elastic waves in the acousto-optic crystal tellurium dioxide is examined in the presentation. The reflection of the waves from a free and flat boundary separating the paratellurite crystal and the vacuum is investigated in the (001) and the (110) planes of TeO₂ in the case of glancing and inclined acoustic incidence on the boundary. The analysis shows that as much two elastic waves may be reflected from the crystal surface. Energy flow of one of the reflected waves propagates in a quasi-back direction with respect to the incident energy flow unusually reflected wave may be close to a unit in a wide variety of crystal cuts. Possible applications of the examined phenomena in acousto-optic devices are discussed in the presentation.

Acousto-optic (AO) interaction for a case when an acoustic signal contains three frequency components is theoretically and experimentally investigated. An existence of combinative frequencies at the multifrequency AO interaction is proved. A spatial distribution of transmitted and diffracted light intensities is demonstrated in approximation of three-step scattering process. The functioning of an AO spectrum analyzer is illustrated by an example of the three-frequency AO interaction. A new method for the expansion of the analyzer dynamic range is suggested. The efficiency of the method is experimentally confirmed.

Interesting phenomenon - drastic suppression of diffracted light first order side lobes, has been shown as a result of numerical simulation of light and sound beams interaction with equal cross-section field distribution and equal divergences.

Acousto-optic tunable filter (AOTF) is not obligatorily the better, the spectral selectivity is finer. It is often necessary to tune AOTF spectral transmission in accordance with certain problems. We have developed an APTF with variable parameters of spectral transmission. The device provides high values of partial diffraction efficiencies while simultaneous exiting of multiple acoustic waves with different frequencies. The wavelength selectivity varies from 5 through 30 nm, and its shape also varies from Gaussian to nearly rectangular. The results of this AOTF study have been listed and discussed. It has been shown that the specially developed software allowed changing the spectral transmission characteristics according to any given law. The possible areas of such device application have also been discussed.

Acousto-optic tunable filter (AOTF) wavelength defines the device ability to process and transmit information. Although this parameter is the most important for AOTF spectrometric applications, it also plays an important part for AOTF providing multispectral processing of images. Hence, it is necessary to provide AOTF selectivity measurements by such way the information possibilities of the device would be strictly characterized by the measured value. This method has been developed and listed in the presented work. The theoretical basis of this method as well as its experimental implementation of the presented method is discussed. It has been found that the only AOTF selectivity beforehand admissible probability of information unit loss.

A detailed description of multichannel Bragg cells and their insertion in a versatile crossbar optical switch architecture is presented here. The cells utilize for the first time an acousto-optic scattering geometry in GaAs which displays advantageous characteristics in the design of a telecommunication spatial switch: low crosstalk and access delay, insensitivity to optical polarization, relatively low insertion losses.

Two different acousto-optical tunable filter based imagers for acquisition the spectral data of optical objects are described. The first imaging spectrometer is intended mostly for astronomical observations and studying the planets and emission objects: planetary nebulae and Seyfert galaxies. The spectrometer is based on the tunable TeO₂ acousto-optical filter that combines simultaneously both high spatial resolution and high spectral resolution. The acousto-optical filter with a 13 Å pass band at wavelength 6328 Å operates in the wavelength range 6300-11000 Å. The spatial resolution of the spectrometer is about 1 angular sec. The geometry of acousto-optical interaction as well as design peculiarities of the acousto-optical filter is discussed. The astronomical observations were performed at the Crimea laboratory of Sternberg Astronomical Institute. The telescope was 600 mm f/12.5 Cassegraine Zeiss-600. Series of spectral images of the planetary nebulae NGC 7027 in the vicinity of the 6563 Å Hα and 6586 Α N [II]emitting lines are obtained. The performed measurements of the rapid spectral variability of Hαemission line in the nuclear of the Seyfert galaxy NGC 4151 (redshift Z=0.003) are also discussed. In this paper we describe also the laboratory visible - to - near infrared acousto-optical spectral imager. TeO₂ based acousto-optical filter with 15Å pass band and tuning wavelength range 6000 - 1400 Å is used in this imager. Image - forming optics, RF electronics and factors influencing on the image quality is discussed.

A method of phase object visualization based on selective properties of acousto-optic diffraction is described. It is shown that in the optimal case the distribution of light intensity in the visualized image is proportional to the phase gradient in the acousto-optic interaction plane. The resolution and the contract of the visualized image are determined primarily by the divergence angle of the acoustic beam. Some experimental results as well as examples of computer simulation are presented for illustration of potentialities of the method.

Results are presented of a theoretical study of optical image processing based on two-dimensional acousto-optic filtration of the spatial spectrum of images. Most attention is concentrated on the analysis on the analysis of the acousto-optic transfer function form and its dependence on crystal cut, geometry of acousto-optic interaction and ultrasound frequency. Results of computer simulation of acousto-optic spatial filtering are illustrated by the example of an object in the form of an amplitude grating. For this object, effects of image differentiation and integration are demonstrated.

The paper is devoted to the theoretical and experimental investigation of spatial resolution of images obtained during acousto-optic spectral filtration. The consideration was carried out for a wide angle acousto-optic filter designed on the base of paratellurite single crystal. The crystal was cut in the (1 1 0) plane with the direction of acoustic wave propagation at the angle 10 ° relative to the axis [110]. It was found that optical quality of a filtered image is influenced by a spectral bandwidth of a filter. The spectral bandwidth is determined by a length of piezoelectric transducer that generates ultrasonic waves in an acousto-optic cell. The dependence of a number of resolvable spots on the piezotransducer length was examined theoretically. It was shown that a wavelength of the filtered radiation influences the quality of the processed image. Precise and approximate equations have been derived to determine the spectral passband of the acousto-optic filer, the angular field of view of a single pixel, the angular aperture of the device and the number of resolvable spots in a line. Resolution of the images obtained during the acousto-optic filtration was also measured in the experiment.

A study by means of the Schlieren technique for visualization of ultrasonic beams, has revealed that when leaky Rayleigh waves, propagating along the horizontal edge of a thick, fluid loaded solid plate, are scattered at the extremity of the plate, they travel around the corner and start leaking into the liquid along the Rayleigh angle measured from the normal to the vertical edge of the plate. Furthermore the study reveals that leaky Rayleigh waves are stimulated by the border of an incident ultrasonic bounded beam, more than by the interior of the beam. Comparison with an earlier work shows that the characteristics of the scattering of leaky Rayleigh waves at the edge of the plate is very different from that of Scholte - Stoneley waves.

After a short description of the Ultrasonic Polar Scan Technique for characterizing composites, the paper describes and experimental method, based on the combination of Schlieren photography and a wide bounded ultrasonic beam of frequency 10 MHz, used to detect the fiber direction in composites. Experiments are described on unidirectional and fabric fiber reinforced composites. This method is not based on Lamb wave phenomena, which can be complicated for interpretation by NDT engineers, but rather is based on relatively simple principles, i.e. inhomogeneity and symmetry of composites.

In this paper the main idea and method for bulk holographic video realization is considered. By digital simulation the steps of hologram recording and image reconstruction is shown. The prospects and some shortcomings of the suggested method are discussed.

Regularities in some complex systems can sometimes be expressed in terms of simple laws. A peculiar regularity is identified concerning photoacoustic (optoacoustic) phenomena. In particular, the acoustic signals following phase transitions in liquid irradiated by laser pulses are distributed by magnitude according to the Zjif’s law. This power law distribution describes many man made and naturally occurring phenomena, including city sizes, incomes, word frequencies, and earthquake magnitudes. This law suggests connection with anomalous decay, i.e. it implies that small occurrences are extremely common, whereas large instances are extremely rare. We use this law for signal processing in the course of optoacoustic diagnostics of diluted suspensions. The irradiation of an inhomogeneous liquid sample with a long train of short laser pulses and subsequent recording of a histogram of the magnitudes of the acoustic responses can serve as a diagnostic tool for various applications. The absorption of an incident light by a suspended particle may cause a cavitation event. The random cavitation events also obey the Zipf’s law, this fact being used for detection of individual particles.

In the presented work the new method of the analysis of particle distribution in the emulsion according to the sizes with the increased resolution by means of the scattering of light is considered. A significant increase in the possibilities of the proposed method is achieved due to the additional introduction into the emulsion of physically powerful ultrasonic flow and make use of the frequency-phase method of detection. Fundamental special features of procedure and some technical questions are discussed.

This work presents analysis of localized acoustic modes using theory given by B. Djafari-Rouchani et al. and Rytov model of elastic waves propagation in periodical medium. Localized modes were considered for Au/V nanostructures. Experimentally Au/V nanostructures on MgO substrate with period 120-240 Å were studied. Changes of light reflectivity coefficient of these nanostructures caused by femtosecond laser beam excitation were measured. Analysis of experimental results of reflectivity dependence on delay time of probe beam was made over the range up to 150 ps. The dependences of localized modes frequency on thickness of nanostructure bilayers were obtained. Measured frequencies of localized modes remain in agreement to the theoretical values.

An acoustic wave changes, by definition, the pressure of the gas medium. The power delivered to the pulsed gas laser changes the pressure (and temperature) of the laser medium. The monitoring of the acoustic wave in the laser cavity, taken as a specific acoustic resonator, can be an easy measure of the local changes of the laser gas pressure. The changes of the pressure involve changes of the laser gas density, and changes of the refractive index, as a consequence. It leads to a frequency tuning of the laser optical resonator. In the case of the CO2 laser a rotational line hopping phenomenon is observed as a result. In other words, a single frequency operation of the RF excited CO2 laser with a pulsed plasma is problematic. The main goal of the experiment is to give a picture of the laser plasma behavior during the pulsed excitation of the CO2 laser medium.

This paper describes some achievements in the field of the diffraction of ultrasound on corrugated surfaces. Both single and double corrugated surfaces are considered. A demonstration of the capability of the inhomogeneous wave theory to simulate backward displacement of ultrasonic bounded beams (observed by Breazeale and Torbett, Appl. Phys. Let. 29(8), 456-458, 1976) has been demonstrated very recently [Nico F. Declercq, Joris Degrieck, Rudy Briers, Oswald Leroy, Appl. Phys. Let. 82(15), 2533-2534, 2003]. The current report applies the theory of the diffraction of inhomogeneous waves and shows how this theory is capable of simulating, explaining and understanding the experiments mentioned above. The theory reveals the existence of leaky Scholte - Stoneley waves, which is a novel phenomenon that was first reported from a theoretical point of view [Nico F. Declercq, Joris Degrieck, Rudy Briers, Oswald Leroy, J. Acoust. Soc. Am. 112(5), 2414, 2002] and was shortly after discovered experimentally [A.A. Teklu, M.A. Breazeale, J. Acoust. Soc. Am. 113(4), 2283-2284, 2003]. Moreover, the present paper shows that the classical Fourier decomposition of bounded beams is unable to simulate the backward beam displacement. This work also elucidates the nature of Wood anomalies in Diffraction spectra. Furthermore, it is known that singly corrugated surfaces have the ability to stimulate surface acoustic waves by means of diffraction. However, this diffraction occurs in a single plane. Sound impinging a doubly corrugated surface is scattered in many directions. Therefore, such surfaces possess the ability to generate surface waves in many directions, depending on the corrugation and depending on the frequency. Numerical simulation is possible if continuity of stress and strain is considered. The present paper reports advanced numerical simulations based on all physical parameters of the system and shows what surface waves are generated, under what conditions and under what angle. Such a device may be used to send surfaces in directions that are determined by their frequency.

This paper describes a short history of the radiation mode theory (RMT) in ultrasonics. The RMT originates from electromagnetism where it has proved to be very efficient in the field of wave guides and discontinuities. In ultrasonics the RMT made its entrance only a decade ago and has already proved to be very efficient in describing the interaction of sound with discontinuities such as a step on a plate, a liquid wedge, the extremity of a plate and much more. It is likely that the development of the RMT for 2D isotropic media has come almost to an end. This papers lists some of the results obtained so far. Further extensions to more complicated media re to be expected the coming decade.

Active control of vibration suppression of a circular fluid-loaded plate is analytically studied. The purpose of this theoretical work is to present a general model of the response of a thin circular plate mounted to a frame with a metal collar. The model is based upon the geometry and properties of an experimental set-up consisting of a hard-walled cylinder with a thin plate at one end. The plate is excited on one side by a uniform periodic force with constant amplitude and radiating into free space. The system equations are formulated taking into account the coupling effect between structure and acoustic medium. The control problem lies in using piezoceramic actuators working in pair to control theory is then applied to the system model using a linear quadratic regulator (LQR). The feedback control is realized via circular piezoelectric ceramic elements glued to the central part of the plate.

The aim of the paper is theoretical analysis of the finite amplitude waves interaction problem for the biharmonic transmitting array. We assume that the array consists of 16 circular pistons of the same dimensions that regrouped in two sections. Two different arrangements of radiating elements were considered. In this situation the radiating surface is non-continuous without axial symmetry. The mathematical model was built on the basis of the Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation. To solve the problem the finite-difference method was applied. On-axis pressure amplitude for different frequency waves as a function of distance from the source, transverse pressure distribution of these waves at fixed distances from the source and pressure amplitude distribution for them at fixed planes were examined. Especially changes of normalized pressure amplitude for difference frequency were studied. The paper presents mathematical model and some results of theoretical investigations obtained for different values of source parameters.

The study of ultrasonic properties of water-based magnetic fluid EMG-605 is presented. The measurements of velocity and attenuation of ultrasound were carried out as a function of temperature, frequency, magnetic field strength and the angle between the wave and the direction of magnetic liquid. The model takes into account mutual interaction of magnetic clusters giving skeleton’s stiffness and interaction of clusters with free liquid producing attenuation and dispersion of waves for transversally isotropic system. A good agreement between experimental data and the predictions of theoretical model was obtained.