Walter G. Mayer

Optical Methods for the Ultrasonic Determination of the Elastic Constants of Sapphire

Three optical methods, formerly only used for isotropic media, are applied to find the ultrasonic velocities in sapphire. From the results the elastic constants are calculated for this crystal. The elastic moduli are determined from measurements of ultrasonic velocities in different crystallographic directions, and Youngs modulus is plotted as function of these directions.

Determination of Ultrasonic Velocities by Measurement of Angles of Total Reflection

A simple method, based on the total reflection of a sound beam from a liquid‐solid boundary at the critical angles, is described. With this method, it is possible to measure the velocity of longitudinal and shear waves in the solid by locating the angles of maximum reflection in the liquid.

Corrected Values of the Elastic Moduli of Sapphire

Corrected values of the elastic moduli of sapphire are given based on earlier work of the authors but using more accurate crystal orientations.

LIGHT DIFFRACTION BY ULTRASONIC SURFACE WAVES.

The diffraction pattern produced by monochromatic light reflected from a solid on which an ultrasonic surface wave is propagated is shown to be useful in the determination of velocity and amplitude of the surface wave. The formalism describing the interaction of light and ultrasonic surface wave is compared to the theory applicable to light diffraction by ultrasonic waves through transparent media. [Work supported by the U. S. Office of Naval Research.]

Optical Method for Ultrasonic Velocity Measurements at Liquid‐Solid Boundaries

An optical method is used to measure the energy ratio of reflected and incident ultrasonic waves at a liquid‐solid interface. The ultrasonic velocities in the solid are calculated from the angles of maximum reflection in the liquid.

Light Diffraction by Two Distorted Ultrasonic Waves

Light intensities in the orders of diffraction patterns produced by two distorted ultrasonic waves 180° out of phase are investigated. In the case where the two waves have the same intensity, the first diffraction orders vanish. The simultaneous increase in light intensity in the second orders is a measure of the second harmonic present in the waves, given for varying distances from the transducers. The change in light intensities in the zero and second orders is given for varying pressure ratios of the two waves.

Effects of Transducer Alignment on Light Diffraction by Ultrasonic Waves

Light‐diffraction patterns produced by wide ultrasonic beams of 5.235 and 8.786 Mc/sec are investigated for normal and slightly nonnormal incidence. A method for the correct alignment of the transducer is described. The results are discussed regarding agreement between experiment and theory.

On Elastic Constants and Ultrasonic Velocities in Some Crystal Groups

Expressions are given relating ultrasonic velocities in single crystals to the elastic constants. Without introducing approximations these expressions can be used in a relatively simple manner to evaluate the elastic constants. As an example the procedure is outlined for the trigonal system, based on existing velocity measurements in corundum. Some of the general expressions indicate certain invariance properties of the velocities in simple crystal groups. These properties can be used to check the results of certain velocity measurements or to determine the velocity of certain modes of vibration in some crystallographic directions.

Ultrasonic Velocity Measurements at Solid‐Liquid Interfaces

An optical method is described with which the energy ratio of incident to reflected ultrasonic waves at a solid‐liquid boundary can be measured for various angles of incidence. The method consists of comparing the light intensity distribution in the diffraction patterns produced by the incident and the reflected waves. The ultrasonic velocity in the solid is calculated from these measurements using the technique of locating the angles of maximum reflection in the liquid [W. G. Mayer, J. Acoust. Soc. Am. 32, 1213 (1960)]. Results are given for some solids. (This work supported by the Office of Naval Research, U. S. Navy, and by the National Science Foundation.)

Light Diffraction by Progressive Ultrasonic Waves in Plexiglas

The optical grating produced by a progressive ultrasonic wave in Plexiglas is used to verify directly the Raman‐Nath theory for solids after it is shown that no finite amplitude distortion of the waveform is present. The absorption coefficient is determined by evaluating the diffraction pattern. (This work was supported by the Office of Naval Research, U. S. Navy, and by a National Science Foundation grant.)