Proceedings Volume 3581

Acousto-Optics and Applications III

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Proceedings Volume 3581

Acousto-Optics and Applications III

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Volume Details

Date Published: 11 November 1998
Contents: 7 Sessions, 52 Papers, 0 Presentations
Conference: Acousto-Optics and Applications III 1998
Volume Number: 3581

Table of Contents

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Table of Contents

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  • Fundamental Problems in Acousto-Optics
  • Acousto-Optical Interaction Experiments
  • Acousto-Optic Devices
  • Acousto-Optical Studies of Materials
  • Photoacoustics
  • Scanning Acoustical Microscopy
  • Miscellaneous
Fundamental Problems in Acousto-Optics
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Quantitative ultrasound field mapping by means of light-diffraction tomography
Rainer Reibold, Piotr Kwiek
Light-diffraction tomography is a non-invasive measuring technique for mapping ultrasonic fields. Provided that there is weak acousto-optical interaction, data acquisition at normal light incidence is the appropriate technique. In the range of strong acousto-optical interaction, data acquisition and evaluation are as easy to perform as for weak acousto-optical interaction provided that Bragg incidence is used. Both techniques are complementary to each other and can be utilized in a frequency range which has not been accessible so far.
Sound pulse imaging in the optical near field of a Bragg diffracted-light pulse
Filip Windels, Oswald Jozef Leroy
A light pulse and a sound pulse, each consisting of a fundamental tone and its N-1 harmonics, influence each other by means of the acousto optical interaction. The optical near field intensity pattern, where all the diffracted light beams still overlap and interfere with each other, contains all the information of the sound pulse. We show that, for a given light pulse, one can reconstruct out of this optical near field, all the frequencies, amplitudes and phases of the sound pulse.
Fuzzy wave vector diagram for strong acousto-optic interaction
Adrian Korpel
It is shown that for strong acousto-optic interaction,the conventional wave vector diagram must be replaced with a fuzzy triangle representing the dynamics in the interaction region.
Comparison of integrated magneto-optics and integrated acousto-optics
Chen S. Tsai
Significant advances have been made in both integrated magnetooptics and integrated acoustooptics in recent years. In this paper similarities in the basic Bragg interaction geometry and the characteristics associated with acoustooptics (AO) and magnetooptic (MO) Bragg diffractions, and a comparison of the resulting AO and MO Bragg cell modulators in center carrier frequency, bandwidth and their electronic tunability, modulation/switching speed, diffraction efficiency, substrate material, and fabrication technologies are presented. Further R and D toward ultimate realization of integrated AO and MO device modules are also discussed.
Schlieren photography in physics
M. A. Breazeale
Schlieren photography has been used many years in physics; however it has proved to be exceptionally valuable in the study of ultrasonic waves in liquids. Part of the reason for its value is that many of the ultrasonic phenomena studied have their optical analogies. Thus, when one studies ultrasonic images the actually is studying a general wave phenomena from a perspective that is impossible with light alone. Examples are given of ultrasonic schlieren photographs as are conclusions possible from their study.
Lensless spatial filtering using acousto-optic modulators
We review the role of acousto-optic (AO) modulators in programmable real-time image processing. Using one AO cell, 1D high pass filtering and edge enhancement has recently been demonstrated. Two AO cells in tandem can be used to remove asymmetries for using one AO cell. We also show notch filtering characteristics of an AO cell by developing a technique to determine the spatial transfer functions numerically for various cases of beam incidence on an AO modulator. Normal incidence and incidence at twice the Bragg angle are investigated as examples.
Temporal modulation of light in complex acousto-optic arrangements explained by phase-vector analysis
Italo Gabrielli
The principles of the phase-vector analysis are recalled by transparencies showing elementary linear and sinusoidal diffracting agents. More complex acousto-optic systems are then analyzed which produce temporal modulated diffraction fringes. They are, in addition to a stationary field of stationary US waves: A) Two adjacent US beams propagating in opposite directions, with their frequencies in ratio 2/3. B) Two adjacent US beams of the same wavelength, propagating in two liquids with velocities in mutual ratio 3/2. C) One US beam of wavelength (Lambda) adjacent to an amplitude grating of constant K equals (Lambda) /3. D) One US beam adjacent to a phase grating of the same wavelength. The predictions are presented by plots reporting, as a function of time, the evolution of the amplitude and of the vector-angle of the light diffraction to a single fringe in the far-field. When the light vector-angle shows, in addition to the Doppler shift, frequency modulation, an additional plot shows such deviations from a linear angular evolution. Unattended predictions are presented, and their experimental verification is advised. The lecture is integrated by a videocassette, reporting the argument by animations.
Polarization changing and beam profile deformation effects of acousto-optics
Chen-Wen Tarn
A spatial Fourier transform approach is proposed to investigate the polarization changing and beam profiles deformation of light during the acoustooptic (AO) interaction in isotropic media. In this paper we consider two basic types of sound waves, namely, the longitudinal and shear waves to be interacted with the light in two interaction regimes, viz. the Bragg and Raman-Nath regimes. The perturbation of the permittivity is then caused by these kinds of acoustic waves and can be expressed in tensor forms. The evolution of different orders scattered light under the Bragg and Raman-Nath conditions can be properly described by a set of equations which are derived from the wave equation using a spatial Fourier transform approach. The solutions explicitly comprise the effects of the polarization changing, beam deformation, and propagational diffraction. It is shown that the spatial beam profiles of the scattered light is distorted during the process due to the effects the AO interaction and propagational diffraction. For both the cases of the longitudinal and shear sound waves, the degree of the profile deformation can be controlled by the changing the amplitude and frequency of the sound. It is also shown that the polarization states of the scattered light are different from the input light due to the AO effect. The degree of difference of the polarization states which depend on the propagation type, frequency, and amplitude of the sound wave can be examined through the use of two polarization parameters, the ellipticity and orientation of the major axis of the scattered light.
Light diffraction in a nonstationary acoustic field
A number of problems of light diffraction in a nonstationary acoustic field are considered in the paper with using the spectral method. Transient processes arising in the acoustooptic cell during an abrupt change of acoustic amplitude, frequency or phase are analyzed in detail. The effects of diffracted mode concurrence and modulation nonreciprocity which are typical for multifrequency diffraction in the strong acoustooptic interaction regime are studied both theoretically and experimentally.
Fine structure of high-order angular characteristics in the intermediate regime of acousto-optic interaction
Vladimir I. Balakshy, I. V. Krylov, T. G. Kulish, et al.
Angular characteristics of the second and third diffraction orders are theoretically analyzed and experimentally tested for the intermediate regime of acoustooptic interaction. It is established that there is for each order a number of optimal incidence angles of light that provide more effective scattering of light. In case of isotropic diffraction the optimal angles depend on acoustic frequency, whereas at anisotropic diffraction the angles are defined not only by the frequency, but also be optical anisotropy of the interaction medium.
Complex geometrical optics application to the Gaussian light beam Raman-Nath diffraction description
Roman J. Bukowski
The description of the gaussian on the planar ultrasound wave in Raman-Nath region by complex optical rays method is presented in this works. The case of the perpendicular light beam incidence relatively to the direction of propagation of the ultrasound beam of (Delta) z width was considered. The influence of such parameters as a size and position of the gaussian beam waist, a laser-screen distance, a position of the ultrasound beam and Raman-Nath parameter value on diffraction pattern was analyzed. That was proved that in some cases the diffraction beams have a fine structure. The final analytical formulas were illustrated by some graphs of the light intensity distributions in beams diffracted on ultrasound waves propagated in water.
Acousto-Optical Interaction Experiments
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Diffraction of light by ultrasound in acoustically anisotropic medium
Vitaly B. Voloshinov, O. Makarov
The paper is devoted to investigation of Bragg diffraction of light by ultrasound propagating in media possessing strong anisotropy of acoustic properties. It is shown that acoustic anisotropy of crystal influences on the process of light and sound interaction. In case of Bragg regime of acousto-optic interaction, intensity of diffracted light and frequency bandwidths of diffraction in the crystals differ from corresponding diffraction efficiencies and acoustic bandwidths in glass materials. During intermediate between Bragg and Raman-Nath regimes of interaction at normal incidence angles, a symmetry of optical intensity distribution over positive and negative diffraction maximums is broken. As a result of the performed research, unknown regimes of acousto-optic interaction provided by acoustic anisotropy of crystal are predicted. For example, collinear isotropic diffraction and interaction with low sensitivity to divergency of acoustic beams are described in the paper.
Strong collinear and quasi-collinear interaction of three-dimensional beams
Vladimir N. Parygin, Alex V. Vershoubskiy, Yu. Resvov
The peculiarities of collinear and quasi collinear acoustooptical interaction in which the energy propagation directions of incident optical and acoustic beams coincide is theoretically investigated. The approximation of slightly divergent optical and acoustic beams in anisotropic medium is used. The problem of slightly divergent acoustic beam propagation in an anisotropic medium within the limits of parabolic approximation is discussed. Generalized equations describing the quasi-collinear interaction of light and sound in an anisotropic medium are obtained. An approximate method of solution of these equations in the case of the light beam from invariancy during diffraction is suggested. Both transmitted and diffracted beams are considered to have Gaussian distribution of amplitude with their radii slowly varying along the interaction coordinate. The system of first order equations that bound characteristics of transmitted and diffracted light beams and of acoustic beam is deduced. The solution of these equations in the case of strong acoustooptical interaction is analyzed.
Bragg gratings in slab lasers
We present the way of forming Bragg gratings in so-called slab lasers. Four running waves in the space of a slab optical resonator create an induced diffraction grating like acousto-optical or holographic gratings. The experimental evidences were performed on a RF excited CO2 slab- waveguide laser.
Acousto-radiospectroscopy (ARFS) and applications
C. J. Lewa, J. D. de Certaines, J.-M. Franconi
There are presented here some methods of detecting and imaging the elastic waves and, hence, measuring and imaging visco-elastic properties of the matter by recording magnetic resonance (MR) effects with radio frequencies. The experimental verification of these proposals was successful. One can therefore consider acousto-electromagnetic methods in the RF region or acousto-radiospectroscopy. The methods worked out so far are: MR Elastography in frequency and phase domain, and Elasto-Magentic Resonance Spectroscopy.
A dozen Bragg effects in tellurium dioxide single crystal
The paper is devoted to the theoretical and experimental investigation of Bragg diffraction of light by shear acoustic waves in tellurium dioxide single crystal. Various cases of Bragg anisotropic interaction accompanied by a change of optical modes in the material are examined. Unknown types of isotropic diffraction of light by shear acoustic waves in paratellurite are investigated as well. Frequency dependencies of Bragg angles for different interaction types in the crystal are calculated and measured thus confirming the basic statement that not only the traditional anisotropic but also previously unknown isotropic regimes of AO interaction may be simultaneously observed in the birefringent crystal.
Near field of light diffracted by ultrasound in an isotropic medium with acoustically induced anisotropy
Erik Blomme, Grzegorz Gondek, Tomasz Katkowski, et al.
A theoretical model is presented for the study of the near field of light diffracted by ultrasound in an isotropic medium which becomes birefringent in the presence of an acoustic wave. Due to the interference with the sound wave, the diffracted light wave in its near field is seen to act as a quasi-monochromatic light wave which is partially polarized. The degree of coherence ins sen to coincide with the degree of polarization and can be controlled acoustically. Hence coherent laser light can be transformed into incoherent light by sending it through an isotropic material with acoustically induced birefringence. In the experimental part of the work, the non-diagonal elements of the diffracted light beam coherency matrix were measured and a good agreement with the theoretical model was obtained.
Optical measurements of Leaky-Rayleigh waves in air
Laszlo Adler, Michel de Billy, Christophe Mattei, et al.
Due to the difficulties associated with ultrasonic generation and detection in air in the megaHertz region, air-coupled nondestructive evaluation has only recently been explored. In this work, a shear transducer is mounted directly over the edge of a solid specimen so that it can generate a bulk mode in the interior of the solid as well as a Rayleigh wave along the surface. A recently developed optical heterodyne interferometer proved to be sensitive to the leaky-Rayleigh wave in air more than a centimeter away from the solid surface. Results of velocity and attenuation measurement of leaky-Rayleigh waves for several solids will be presented. The technique can also be applied to pates to measure leaky-Lamb velocity and attenuation in air. This method can be used for low optical reflectivity solid surfaces: thus it can be extended for non-contact nondestructive evaluation applications.
Applications of laser interferometry
Many industrial processes require non-contact sensors for various reasons, including high temperature, moving parts, hostile environment or simply the necessity for remoteness. This paper present a review of our recent research and development on the measurement of out-of-plane displacement by four laser optical methods. These are: (1) a point displacement method at 30 Hz, (2) a shearographic fringe imager in the kHz frequency range, (3) a double probe interferometer for time-of-flight measurements in the low MHz frequency range, and (4) Fabry-Perot speckle interferometer for measurement of relative displacement amplitude also in the low MHz range. Each of the methods is presented in the context of an industrial application.
Acousto-Optic Devices
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Integrated acousto-optics in compound semiconductor waveguide structures
Chen S. Tsai
Compound semiconductor waveguide substrates have been recognized for sometime for their potential for realization of monolithic integrated acoustooptics (AO) devices and circuits. Recent theoretical and experimental studies on AO Bragg interactions in GaAs-based waveguide substrates and the most recent studies in InP-based waveguide substrates have made advances toward this potential. It is clear that many of the science and technology that are being developed in conjunction with the InP-based photonics integrated circuits may be employed for realization of monolithic integrated AO devices and circuits. Such future integrated AO devices and circuits should facilitate utilization of photons, phonons and electrons in a common material substrate for a variety of applications in information processing and communications, and sensing that are not possible with utilization of two particles alone.
Optical implementation of the wavelet transform using smart pixels
Daniel M. Litynski, Barry L. Shoop, Dirk A. Hall, et al.
Wavelet transforms have found many practical applications in signal processing, including image processing, pattern recognition, and feature extraction. Since the wavelet transform is fundamentally given by the correlation of an input signal with a family of daughter wavelets, any real- time correlator can be used to implement the wavelet transform. Optical correlators are particularly well suited to this application, since the wavelet transform of a 1D signal produces a 2D wavelet transform. In this paper,w e discuss implementations of the wavelet transform using acousto-optic correlators and smart pixels as spatial light modulators. Smart pixels integrate both electronic processing and optical devices in a 2D array, which takes full advantage of the programmability of electronics and the parallel processing of optical devices. We describe a specific smart pixel implementation consisting of analog liquid crystal integrated on silicon 2.0-micrometers CMOS circuitry; and present experimental results of the wavelet transform implementation. An acousto-optic architecture for real-time wavelet correlators using this device will also be presented.
Acousto-optic processor for phase and frequency measurement
Mieczyslaw Szustakowski, Leon Jodlowski, Idzi Merta, et al.
The system of an acousto-optic processor for phase and frequency measurements is considered in the paper. Interaction between the laser light and acoustic waves result in appearance of the interference pattern in the focal plane a 600 mm lens. All parts of the AO system are discussed in details. The analyze of the disturbing factors influence on the interference pattern is also discussed.
Calculation and modeling of an ultrasonic radiator's directional characteristics
Virgilijus Minialga, Stanislovas Sajauskas
The calculations of directional characteristics of ultrasonic transducer were carried out by using data from holographic interferometric measurements. The acceptable correspondence between measured and calculated values was received. These results induced modeling of directional characteristics of mathematically simulated distribution of vibration on the surface of flat or cylindrical radiator. Some examples of directional characteristics are shown.
Acousto-electro-optic interferometer for rf phase control
It is present da general discussion about acousto-optic and electro-optic interferometric system for RF phase control. After point out the most important problems of such systems it is presented the one arm interferometer based on a collinear acousto-optic modulator and an electro-optic modulator. This proposed setup is compared with the two arms interferometers and its characteristics as insertion loss and bandwidth are discussed.
Electroluminescent effects and the possibility of their practical applications
Tadeusz Pustelny, E. Borysewicz, Barbara M. Pustelny, et al.
The possibility of the electroluminophore semiconductors of the II-VI group to the construction of the electric field intensity sensors are presented. Using ZnS:Mn and ZnS:Cu luminophors, the fiber optic intensity of electric field sensors were elaborated. This kind of electric field sensors belong to the group of intensity fiber optic sensors. Electroluminescent phenomena of two groups pf electroluminescent effects are classified as: 1) internal electroluminescence and 2) carrier-injection electroluminescence. In the paper there are described sensors based on carrier-electric injection electroluminescence.
Acousto-optic cell performances: an application in optical packet synchronization
Youssef Naciri, V. Quintard, Andre Perennou, et al.
In this paper we present a new application of acoustooptic cell used as a fast deflector. First, we have measured the principal performance of the acoustooptic cell like the diffraction efficiency, the number of deflection points, the switching time and the geometry of the diffracted beam. Afterwards we present an application of the optical fast deflector for telecommunication network. It is an optical packets synchronizer device based on the association of acoustooptic cell and fiber delay lines.
Influence of distortion in optical track on errors of phase and frequency measurement by acousto-optic processing
Leon Jodlowski
This paper analyzes the influence of small distortion of optical axes of camera CCD on errors of measurement of signal phase and signal frequency. As an example procedures of obtaining a minimum error in experimental setup of acoustooptic processor and results are described here.
Phase measurement errors in acousto-optic processing in the case of various power levels
Leon Jodlowski, Robert Bobrowicz
The influence of various power levels of electrical signal led-into the inputs of acousto-optic modulator on the phase measurement errors is considered in the paper. The phenomenon of CCd camera saturation above a certain threshold and the fact of existence of unequal values of power in both channels of 2-channel AO modulator are discussed.
Early proposal for an acousto-optic gramophone
Robert C. Chivers
Some of the work of Professor AO Rankine, first presented to the Physical Society of London in 1919 is reviewed. Prior to discussing his work, elements of acousto-optics, and developments to that time are sketched in order to provide a content for Rankine's innovations. His initial proposal was for a system to transmit speech sounds over distances of several kilometers using light waves. Various possibilities were discussed, the most successful of which was based on the interference of a vertical grid with a superimposed image of itself. This proposal was shortly followed by a successful demonstration of the possibility of using this 'photophone' in conjunction with a rapidly moving photographic film to record any type of sounds. They could then be replayed using a relatively simple optical system and a selenium detector. Some comments are made on the ration between Rankine's system and more recent developments in optical sound recording.
Acousto-Optical Studies of Materials
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Acousto-optical features of polysilane oligomer polymers
Ivan V. Kityk, Bouchta Sahraoui, Janusz Berdowski
Acousto-optical parameters in the polysilane Sin(CH3)2n + 2 oligomers with the different number of monomers n were investigated as the functions of n and thickness. The maximal value of the acousto-optical quality coefficients was reached at n equals 10 and thickness about 1.25 nm. It was proposed to use the polysilane oligomers as the acousto-optical modulators and deflectors. The influence of the oligomer monomer numbers n on the behavior of the acousto-optical parameters was unambiguously shown. Simultaneously dependence of the acousto-optical coefficients on the thickness of the samples was shown. The data on the acousto-optical quality correlate well with the data obtained by the sound losses in the external electrical fields.
Determination of the bonding qualities of layered gold/silicon systems using higher SAW modes
Thomas Blum, Klaus Kosbi, Ulla Scheer, et al.
Dispersion curves of SAWs propagating on the surface of a layered system wee obtained by measurement of the surface wave velocities for various ultrasonic frequencies. Results are presented for two and three layered specimens: gold/silicon and gold/chromium/silicon. A comparison with numerically simulated dispersion curves shows that Sezawa modes were measured. The elastic constants, namely c11 and c44, of gold films with thicknesses up to 2 micrometers were determined by minimization the difference between the theoretical and the experimental values in a least-square sense. The resulting Young modulus E yields information about a stiffer layer structure caused by the influence of an chromium interlayer. The modification of the interface between film and substrate is characterized. The results confirm the use of chromium for better adhesion.
Brillouin light scattering in piezoelectric crystals
The article provides a description of the hypersonic acoustic wave frequency measurements in the piezoelectric LiTaO3 crystal. Especially it contains the description of an experiment preparation. The main purpose was an observation of the acoustic waves in the same crystallographic direction, however for different frequencies of the acoustic waves, to find dispersion relations for the wave velocities. Before the measurements calculations of the frequencies were performed. For the calculation ultrasonic data were used. A comparison with current hypersonic results shows a difference in the values of the acoustic wave frequency. The c66 elastic constant of the LiTaO3 was also examined in the range of frequencies equal to 20.4 GHz-29.4 GHz.
Brillouin scattering in the LiTaO3 crystal: dispersion of the acoustic wave velocity
What follows is a description of the hypersonic acoustic wave velocity measurements in the LiTaO3 crystal. Before the measurements calculations of the velocity, frequency and state of the acoustic wave polarization were performed. For the calculation ultrasonic data were used. A comparison with current hypersonic results shows a dispersion in the velocity of the acoustic waves.
Piezoceramics for acousto-optics applications
Gabriel Dobrescu, Maria Robu, Marian V. Lazar, et al.
This paper presents an experimental study on the behavior of piezoceramics of PZT type, having a high compliance obtained in laboratory, and their applications in acousto-optics. The PZT type piezoceramic materials with high compliance and electrostrictive coefficients were used for optoelectronic applications, such as: low power bimorph piezoceramic transducers for optical vibrating systems, laser interferometers, remote command signals in optoelectronic systems, bar code systems, micropositioners for laser systems, etc.
Photoacoustics
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Photothermal cell for measurement of thermal parameters
Jerzy Bodzenta, Jacek Mazur
An experimental setup with well defined boundary conditions is proposed for photothermal measurement of thermal parameters of opaque, plate-like samples. One dimension mode of temperature field in layered structure and simple-single ray description of photodeflection detection is used for theoretical description of experimental results.
Mirage effect description as applied to complex ray optics
Roman J. Bukowski
The complex optical rays method application to the gaussian beam propagation in the region with so-called thermal waves is presented in this work. The case of light beam perpendicular incident relatively to the plane thermal waves of (Delta) z width direction of propagation is considered. Here was assumed that the light refraction index changes caused by thermal waves influence only on the light wave phase. The typical experimental setup was considered in which the light probing beam intensity changes are registered by quadrant photodiode. Such parameters as size and position of the gaussian beam waist, the laser-screen distance, the thermal waves beam position, as well so 'traditional' parameters as thermal waves frequency and the probing beam - thermal waves source distance influence on so-called normal signal from quadrant photodiode is analyzed. The final analytical relations are illustrated by normal signal graphs quantity caused by thermal waves in air.
Effect of Cr+3 and Cr+4 ions on the photoacoustic spectrum of the Cr-doped Y3Ga5O12 garnet
Anna Sikorska, Benedykt Kuklinski, Stanislaw Zachara, et al.
The effect of nonradiative processes on spectroscopic properties of the Y3Ga5O12 crystal doped with Cr+4 has been examined. For this reason, the absorption, emission and photoacoustic spectra of the same have been measured and analyzed. For the interpretation of the obtained result the role of the nonradiative interconfigurational transfer between highly excited vibronic levels was considered. It is concluded that this relaxation mode is probably the reason for almost purely nonradiative character of the Cr+4 centers in the investigated medium.
Relation between the photoacoustic signal shape and the thermal parameters of the sample
Malgorzata Kopycinska-Mueller, Janusz W. Szurkowski
There is commonly assumed in photoacoustic studies that the answer to sinusoidal excitation to the system is sinusoidal. In the presented contribution, using so-called an open-type photoacoustic cell, the effect of thermal signal shape was evaluated. In the studies, water was used as a reference medium of well-determined thermal diffusivity. Fresh and degraded oils were selected as studied liquids. The values of (alpha) obtained for fresh oils and degraded ones are in agreement with the table reference data reported for similar kinds of oils.
Photothermic method for characterization of the thermal properties of oil layers
S. Pogorzelski, Janusz W. Szurkowski, Antoni Sliwinski
The model layered system of thin olive oil layers spread on the water surface was studied using a photoacoustic method. Dramatic changes in the signal phase and rather slight variations in the signal amplitude were observed in reference to the oil-water interface probing. Applying a principal relation of the depth profiling approach between the thermal diffusion length and thermal diffusivity the latter for a particular layer thickness 25 micrometers , was evaluated to be 1.22 by 10-3/s being a characteristic value for kind of oils examined.
Investigation of technical working fluid properties by photoacoustic spectroscopy
Jerzy Motylewski, Bogdan Wislicki, Kazimierz Krawczyk
The goal of our investigations is to evaluate the photoacoustic spectroscopy technique a new tool for examination of technical working fluids properties. In the paper the last of spectrophotometric and photoacoustic measurements, concerning properties changes of oils and fuels after oxidation are presented. The photoacoustic experimental investigations of lubricating oils degradation in various conditions are outlined.
Scanning Acoustical Microscopy
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Evaluation of imperfect gold/glass interfaces using scanning acoustic microscopy
Klaus Kosbi, Thomas Blum, Ulla Scheer, et al.
A quantitative measurement method for the evaluation of thin film adhesion is desired in a wide range of thin film applications. As an example, we investigated the bonding conditions of gold layers on glass substrate. The interface was modified by introducing a thin layer of silicone oil. With increasing oil thickness we assume the adhesion to get worse. Using quantitative scanning acoustic microscopy (SAM) surface acoustic waves (SAW) dispersion curves were measured. Significant variations with the oil layer thickness were found. By fitting the measured data to theoretical curves, stiffness constants which describe the quality of adhesion, can be derived. Our theoretical model is based on the quasi-static model developed by BAIK and THOMPSON. Variation of the interfacial stiffness constants leads to good adhesion Rayleigh-type SAWs propagate on the samples, whereas in the case of bad adhesion a Sezawa-type SAW is generated. The SAM measurements are in good agreement with destructive measurements using the scratch test.
Implementation of the wavelet transform for V(z) analysis in acoustic microscopy
Ulla Scheer, Thomas Blum, Klaus Kosbi, et al.
The scanning acoustic microscope is a powerful tool for the study of the physical and elastic properties of materials. Surface and interior structures of a specimen can be imaged nondestructively. The elastic micro analysis of bulk materials and layered structures is carried out by measuring the so-called V(z) function, which includes examination of the reflection function of solid materials, measurement of the phase velocity and attenuation of leaky surface acoustic waves and determination of the elastic constants of the material. Therefore, V(z) is a very important effect in acoustic microscopy for material characterization and so its precise analysis is desirable. A wavelet based filtering of the measured V(z) curve will be shown in order to remove short period oscillations caused by internal lens reverberations. Furthermore, the continuous wavelet transform of the V(z) data indicates irregularities in the experimental setup.
Application of scanning acoustic and scanning probe microscopy on biological materials to assess elastomechanical properties
Hans-Joachim Hein, D. Matern
The principles of scanning acoustic microscope (SAM) and the scanning probe microscope (SPM) are presented. Especially the modes for application on biological specimen are described. We focused our attention on the possibilities to determine the elastomechanical properties of tissues. For bone structures the V(z)-behavior is used to determine tissue properties. From this the sound propagating velocity has been calculated to assess the modulus of elasticity. We applied this method on cortical bone and to assess the mineralization at the callus tissue after distraction. In similar manner the SPM as completing techniques is applied. For this method we used the so-called 'tapping mode' for diminishing the influence of scanning procedure on the surface of specimen. It has been shown that the apatite crystals are imaged as light areas and the more soft collagen as darker regions. On this way the dimensions of crystals and the thickness of collagen fibers between them could be measured. The angle dependency of elastomechanical properties could be shown by cutting the bone samples under different angles and by measurement of sound propagating velocities into these specimens as well their imaging by SPM. The results are discussed and related to clinical findings.
Determination of the elastic properties of carbon thin films using scanning acoustic microscopy
A. Pageler, Klaus Kosbi, Ulf G. Brauneck, et al.
Scanning acoustic microscopy is used to determine elastic properties of carbon thin films. The films have been deposited by fullerene-argon-ionbeam deposition on crownglass substrates. With V(z) measurements, their elastic constants and experimental dispersion relations can be obtained. These are compared with numerically calculated dispersion relations. Using a simplex method for least- square data fitting the Young's modulus, the shear modulus and Poisson's ratio of the measured carbon thin films were determined.
Technique for automatically testing the reliability of V(z) interpretation gained from scanning acoustic microscopy of microstructured objects
Uwe Laun, Siegfried Boseck
In the past, the acoustic microscope has been used to measure the microelastic properties of many bulk and layered materials. This is carried out by measuring the so-called V(z)-function, which includes the velocity of the surface waves on the specimen. For complicated materials with inherent microstructure like human bones, the interpretation of this measurement technique becomes more difficult due various acoustical effects at elastic discontinuities. A simple technique for testing the reliability of the V(z)- interpretation is given and the examination of the newly defined reliability-factors is presented as a possibility for detecting some unusual properties in microstructured objects.
Detection of the defocused transfer function of a confocal reflection acoustic microscope (SAM) by imaging of a step and a sphere
Pavel Zinin, Wieland Weise, Siegfried Boseck
The main advantage of the SAM is given by the fact, that the image contrasts are constructed by the ultrasonic waves and their reaction with the elastic discontinuities of the specimen. Some pat of the image structure is depending on the material distributions and their elastic parameters; another will be modified by the imaging conditions of the instrument. Image interpretation is closely related to these two classes of image contrast. Whereas the first kind of contrasts - especially known by the V(z)-function - mostly is used for microcharacterization of thin films and solids, the second kind of contrasts is deduced from the wave optical considerations, applied on the confocal acoustic reflection microscope and can be treated like amplitude contrast and phase transfer functions. These are useful for the description of structures, to reveal their real shape or distribution on the surface or inside the bulk specimen especially for reconstruction processes by inverse filtering in the Fourier domain of the image structure signals. It is shown, how the optical transfer function of the instrument can be found and is separated into the modulation transfer function (MTF) and the phase transfer function. The classical method is to analyze the images of scratches and material steps. Another way is to detect the MTF by imaging a sphere and scanning it at several focus positions.
Miscellaneous
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Pressure field of finite amplitude underwater sources
Eugeniusz Kozaczka, Grazyna Grelowska
The paper present results of experimental investigations of nearfield of finite amplitude underwater sources. Field distribution of a plane circular piston source and a focused circular source are determined. A course of phenomenon of a wave distortion are illustrated by showing distributions of fundamental and harmonic components of radiated wave in chosen cross-sections of the nearfield area.
Velocity of Rayleigh surface waves and Poisson's ratio of a medium
Eugeniusz Soczkiewicz
Values of the ratios of Rayleigh surface wave velocity and transverse bulk wave velocity as well as longitudinal bulk wave velocity have been calculated in terms of their dependence on Poisson's ratio values. Calculations have been performed for isotropic media and the whole range of thermodynamically permissible values of Poisson's ratio. Possibility of approximation of the obtained result by means of polynomial functions has been investigated.
Sonofluorescence method
Huamao Li
In this paper, a new sonofluorescence method is proposed. Based upon the method, the author has obtained the sonofluorescence emission spectrum of an aqueous luminol- NaOH solution, and displayed the cavitation field distribution in a sonochemical glass reactor.
Influence of the refractive profile of a waveguide on the sensitivity of a planar difference interferometer
Roman Rogozinski, Kazimierz Gut, Pawel Karasinski, et al.
The work presents the possibility to control the changes involving the difference of the propagation of waveguide modes TE0, TM0, TM1 by respective selection of technological parameters while producing the optics channel of the planar interferometer by ion-exchange technique in glass. The influence of the refractive profile of waveguide structure on the sensitivity of interferometer was observed.
All-optical acousto-optic effect
Pankaj K. Das, R. Filkins, Casimer M. DeCusatis, et al.
In conventional acousto-optic devices ultrasound signals are generated in a solid medium by applying an RF electrical signal to a piezoelectric transducer, which is bonded to the optical medium. However, it is well known that ultrasound can be generated in solids by sing high power optical pulses incident on the medium. This offers the potential to perform acousto-optic modulation without the piezoelectric transducers and associated electronics. This method can be utilized to modulate a lower power laser beam using a second higher power laser source. Using femtosecond optical pulses, acousto-optic interaction in the terahertz regime becomes feasible. In this paper, these all-optical acousto-optic devices are utilized for signal processing applications. Some preliminary experimental results using laser generated ultrasound in different substrates will be given.
New algorithms for phase unwrapping: implementation and testing
Krzysztof Kotlicki
In this paper it is shown how the regularization theory was used for the new noise immune algorithm for phase unwrapping. The algorithm were developed by M. Servin, J.L. Marroquin and F.J. Cuevas in Centro de Investigaciones en Optica A.C. and Centro de Investigacion en Matematicas A.C. in Mexico. The theory was presented. The objective of the work was to implement the algorithm into the software able to perform the off-line unwrapping on the fringe pattern. The algorithms are present as well as the result and also the software developed for the implementation.