- Email: [email protected]
On linear acoustic birefringence in solids
ABSTRACTS The abstracts survey, a regular feature of each issue of ULTRASONICS, contains recent patent information and reports of new literature in the field. Copies of original articles are best obtained by writing to the journal in which they appeared. The addresses of these journals can be found in reference books such as World List of Scientific and Technical Publications, Willings Press Guide, Newspaper Press Directory, or (for American journals) Ayers.
ACUSTICA On linear acoustic birefringence Fischer, M., Zarembowitch, A. 28 (May 1973) 259-266
in solids
The analogy of polarization effects between light waves and elastic waves propagating through solids is reviewed by describing the following experiments: realization of wave, half-wave and quarter-wave plates based on the natural linear acoustical birefringence of cubic crystals; experimental evidence of uniaxial compression induced, and of high magnetic field induced, linear birefringence effects; circularly polarized acoustic wave generation through oblique reflection of plane acoustical transverse waves at the surface of separation between two media.
The velocity and absorption of ultrasound at 19.5 MHz were studied as a function of the concentration in binary solutions of pyridine with water, methanol, and ethanol. In addition, the compressibility and volume viscosity were calculated. Molecular processes are suggested to explain the variation of the ultrasonic properties of these binary solutions with respect to concentration. Improvement in the pulse-echo technique for ultrasonic attenuation measurements Tripathi, R. C., Gupta, A. K., Verma, G. P. 53 (April 1973) 1102-1106
very asymmetric and concentrated preponderantly in a direction making an angle ~‘/(l + el/ee) with the incident wave, K being the piezoelectric coupling coefficient. Higher-order finite-element analysis of topographic guides supporting elastic surface waves Lagasse, P. E. 53 (April 1973) 1116-1122 A method of computing the eigenmodes of acoustic waveguides of arbitrary cross section is described. It is a finite-element technique, based on a variational formulation of the guided-wave problem. The accuracy of the method is assessed by comparing numerical and experimental results for a few specific structures. In particular, an acoustic surface ridge waveguide with low dispersion over a broadband is described.
In the simple pulse-echo technique successive multiply-reflected pulses, received by the quartz transducer, are amplified by a wideband amplifier, detected, and finally displayed on the screen of a cathode ray oscilloscope. The observed pulse heights are compared for determination of ultrasonic absorption in the medium. The received pulses are connected to a Tadapter. From one of the outputs of this adapter the pulse pattern is observed on one of the beams of a double-beam oscilloscope, while the second output is connected to the input of a single-channel analyser. Using the analyser in this way, pulse heights can be determined directly in volts and their decibel levels can be read on a calibration curve to determine the ultrasonic absorption coefficient in the medium.
Anisotropic beamsteering and diffraction enhancement-retardation effects arc analysed. An anisotropic scaling theorem and an analytic, anisotropic lens maker’s equation are deduced. Experimental results, illustrating near and farfield diffraction pattern scaling, and contrasting aberration-corrected and cylindrical surface wave lenses are presented.
Electromagnetic leakage in high-frequency continuous-wave ultrasonics Miller, J. G. 53 (March 1973) 710-713
Diffraction of a Bleustein-Gulyaev wave by a conductive semi-infinite surface layer van der Pauw, L. J. 53 (April 1973) 1107-1115
Directive harmonic generation in the radiation field of a circular piston Lockwood, J. C., Muir, T. G., Blackstock, 53 (April 1973) 114881153
Electromagnetic Ieakage or cross talk between transmitter and receiver represents a severe limitation on the usefulness of continuous-wave (CW) ultrasonic methods at high frequencies. The problem of leakage is, however, entirely eliminated by use of a scheme known as the sampled-CW technique. The role of the sampled-CW technique in eliminating leakage is explicitly demonstrated by contrasting the results of CW and sampled-CW measurements under a variety of conditions.
The diffraction of a Bleustein-Gulaev surface wave by a semi-infinite conductive layer is investigated. It is assumed that the direction of propagation is normal to the edge of the semi-infinite conductive layer. It appears that, if the dielectric constant er of the piezoelectric material is large compared with the dielectric constant eo of the adjacent half-space, the relative power flow associated with the reflected surface wave is of the order (er/eu)‘. The relative power flow of the transmitted surface wave is of the order eo/ei. Hence, if eu/er < 1, the largest part of the incident power is converted into a bulk wave. The angular power distribution of the diffracted bulk waves appear to be
An experimental and theoretical investigation is presented of farfield distortion of a finiteamplitude wave generated by a circularpiston source. Nearfield distortion is neglected. Thus the boundary condition is that the acoustic signal at the beginning of the farfield is a pure sine wave of amplitude proportional to the small-signal directivity factor for the piston. The method of applying weak-shock theory to obtain directivity patterns and propagation curves is outlined. A criterion for the maximum range at which weak-shock theory is valid is derived for each harmonic. An ad hoc method of matching at this range the small-signal solution, with absorption included, to the weak-shock
Ultrasonic absorption in toluene Kor, S. K., Prasad, R. 28 (May 1973) 301-303 Hirai and Eyring’s concept of holes in a liquid lattice has been used to demonstrate the effect of pressure on the various contributions to the total ultrasonic absorption in toluene in the pressure range l-4 000 kg cm2 at 75°C.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
Ultrasonic studies in binary solutions of pyridine with water, methanol, and ethanol Thomas, K. N., Stumpf, F. B. 53 (March 1973) 714-718
238
Anisotropy, diffraction scaling, wave lenses, and focusing Mason, I. M. 53 (April 1973) 1123-1128
ULTRASONICS.
surface
SEPTEMBER
D. T
1973
ACUSTICA On linear acoustic birefringence Fischer, M., Zarembowitch, A. 28 (May 1973) 259-266
in solids
The analogy of polarization effects between light waves and elastic waves propagating through solids is reviewed by describing the following experiments: realization of wave, half-wave and quarter-wave plates based on the natural linear acoustical birefringence of cubic crystals; experimental evidence of uniaxial compression induced, and of high magnetic field induced, linear birefringence effects; circularly polarized acoustic wave generation through oblique reflection of plane acoustical transverse waves at the surface of separation between two media.
The velocity and absorption of ultrasound at 19.5 MHz were studied as a function of the concentration in binary solutions of pyridine with water, methanol, and ethanol. In addition, the compressibility and volume viscosity were calculated. Molecular processes are suggested to explain the variation of the ultrasonic properties of these binary solutions with respect to concentration. Improvement in the pulse-echo technique for ultrasonic attenuation measurements Tripathi, R. C., Gupta, A. K., Verma, G. P. 53 (April 1973) 1102-1106
very asymmetric and concentrated preponderantly in a direction making an angle ~‘/(l + el/ee) with the incident wave, K being the piezoelectric coupling coefficient. Higher-order finite-element analysis of topographic guides supporting elastic surface waves Lagasse, P. E. 53 (April 1973) 1116-1122 A method of computing the eigenmodes of acoustic waveguides of arbitrary cross section is described. It is a finite-element technique, based on a variational formulation of the guided-wave problem. The accuracy of the method is assessed by comparing numerical and experimental results for a few specific structures. In particular, an acoustic surface ridge waveguide with low dispersion over a broadband is described.
In the simple pulse-echo technique successive multiply-reflected pulses, received by the quartz transducer, are amplified by a wideband amplifier, detected, and finally displayed on the screen of a cathode ray oscilloscope. The observed pulse heights are compared for determination of ultrasonic absorption in the medium. The received pulses are connected to a Tadapter. From one of the outputs of this adapter the pulse pattern is observed on one of the beams of a double-beam oscilloscope, while the second output is connected to the input of a single-channel analyser. Using the analyser in this way, pulse heights can be determined directly in volts and their decibel levels can be read on a calibration curve to determine the ultrasonic absorption coefficient in the medium.
Anisotropic beamsteering and diffraction enhancement-retardation effects arc analysed. An anisotropic scaling theorem and an analytic, anisotropic lens maker’s equation are deduced. Experimental results, illustrating near and farfield diffraction pattern scaling, and contrasting aberration-corrected and cylindrical surface wave lenses are presented.
Electromagnetic leakage in high-frequency continuous-wave ultrasonics Miller, J. G. 53 (March 1973) 710-713
Diffraction of a Bleustein-Gulyaev wave by a conductive semi-infinite surface layer van der Pauw, L. J. 53 (April 1973) 1107-1115
Directive harmonic generation in the radiation field of a circular piston Lockwood, J. C., Muir, T. G., Blackstock, 53 (April 1973) 114881153
Electromagnetic Ieakage or cross talk between transmitter and receiver represents a severe limitation on the usefulness of continuous-wave (CW) ultrasonic methods at high frequencies. The problem of leakage is, however, entirely eliminated by use of a scheme known as the sampled-CW technique. The role of the sampled-CW technique in eliminating leakage is explicitly demonstrated by contrasting the results of CW and sampled-CW measurements under a variety of conditions.
The diffraction of a Bleustein-Gulaev surface wave by a semi-infinite conductive layer is investigated. It is assumed that the direction of propagation is normal to the edge of the semi-infinite conductive layer. It appears that, if the dielectric constant er of the piezoelectric material is large compared with the dielectric constant eo of the adjacent half-space, the relative power flow associated with the reflected surface wave is of the order (er/eu)‘. The relative power flow of the transmitted surface wave is of the order eo/ei. Hence, if eu/er < 1, the largest part of the incident power is converted into a bulk wave. The angular power distribution of the diffracted bulk waves appear to be
An experimental and theoretical investigation is presented of farfield distortion of a finiteamplitude wave generated by a circularpiston source. Nearfield distortion is neglected. Thus the boundary condition is that the acoustic signal at the beginning of the farfield is a pure sine wave of amplitude proportional to the small-signal directivity factor for the piston. The method of applying weak-shock theory to obtain directivity patterns and propagation curves is outlined. A criterion for the maximum range at which weak-shock theory is valid is derived for each harmonic. An ad hoc method of matching at this range the small-signal solution, with absorption included, to the weak-shock
Ultrasonic absorption in toluene Kor, S. K., Prasad, R. 28 (May 1973) 301-303 Hirai and Eyring’s concept of holes in a liquid lattice has been used to demonstrate the effect of pressure on the various contributions to the total ultrasonic absorption in toluene in the pressure range l-4 000 kg cm2 at 75°C.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
Ultrasonic studies in binary solutions of pyridine with water, methanol, and ethanol Thomas, K. N., Stumpf, F. B. 53 (March 1973) 714-718
238
Anisotropy, diffraction scaling, wave lenses, and focusing Mason, I. M. 53 (April 1973) 1123-1128
ULTRASONICS.
surface
SEPTEMBER
D. T
1973