Visualization of Mode Conversion of Lamb-Type Waves in Glass Plates Using Pulsed Light Source

Abstract

Presently, a number of visualization methods of sound waves are investigated in order to understand their behaviors in various mediums. In this study, we employ the visualization method using photoelasticity. In this method, the stress in elastic plates is visualized using the birefringence effect arising from ultrasound stress, through two orthogonal polarization plates. As visualization objects, we observed Lamb and Lamb-type waves under some conditions. Among them, the condition that the layer changes during the wave propagation is very interesting. Under this condition, not only Lamb and Lamb-type waves but also a propagating wave along the boundary appears at the same time. In this study, we can observe the mode conversion of elastic waves by changing the boundary condition during the wave propagation.

Introduction of measurement techniques in ultrasonic electronics: Basic principles and recent trends

“…55) As mentioned above, ultrasound interacts with light, and various measurement methods, devices, and applications based on this principle have been researched, forming a research field called acousto-optics. 30,31,34,39,40,[56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] Brillouin scattering is caused when light is incident to a medium in which an ultrasonic wave propagates and the light and the ultrasonic wave interact with each other. This phenomenon itself is interesting and is also utilized to measure material properties such as elasticity and so forth.…”

Three-Dimensional Quantitative Optical Measurement of Asymmetrically Focused Ultrasound Pressure Field

“…The instantaneous acoustic field can be measured in orders of magnitude shorter time without creating acoustic interference. 8,9) A lead zirconate titanate (PZT) transducer at 1.07 MHz with a spherical curvature radius of 75 mm, an outer diameter of 78 mm, and an inner diameter of 34 mm was used to generate the ultrasound pressure field to be reconstructed. It had four elements, electrically combined into two pairs, as shown in Fig.…”

“…In the development of this technique, an accurate and fast measurement of the HIFU pressure field is important. Optical ultrasonic field mapping [3][4][5][6][7][8][9] has the advantages of speed and its nature of not by interfering with the acoustic field compared with hydrophone measurement.…”

“…To reconstruct threedimensional images from optical measurement, we have been using a computed tomography (CT) algorithm. 7,8,10,11) For CT reconstruction, projection data of the pressure field, which, in this case, corresponds to optical phase distribution data, are generally needed at each angle. For a cylindrically symmetric filed, the measurement becomes much easier because the projection data at every angle become the same.…”

Sensitive tint visualization system for Lamb waves propagation in a glass plate

“…The conventional ''static'' photoelastic method and the sensitive tint method which use a continuous light source, can visualize static stresses in transparent solids [3][4][5]. If a pulse light source such as a strobe light is used, the time transition of the propagation of ultrasonic waves can be observed because ''dynamic'' stresses are produced by ultrasonic waves [6][7][8][9][10]. The sensitive tint method is also a useful visualization method for observing the direction of stress in a solid, i.e., the polarities of sound pressure can be visualized.…”