Title :
Longitudinal critical angle singularities and their effect on V(Z) of the line-focus-beam acoustic microscope
Author :
Tsukahara, Yusuke ; Liu, Yongshen ; Néron, Christian ; Jen, C.K. ; Kushibiki, Jun-ichi
Author_Institution :
Industrial Mater. Inst., Nat. Res. Council, Boucherville, Que., Canada
fDate :
7/1/1994 12:00:00 AM
Abstract :
In order to investigate a mechanism which causes a velocity difference between the longitudinal wave and leaky surface skimming compressional wave (LSSCW) observed in a line-focus-beam acoustic microscope, the analytic property of an acoustic reflection coefficient and its effect on a V(z) analysis were studied. A pole hidden in the unphysical Riemann sheet close to the longitudinal branch point is found to be responsible for the abrupt phase change at the longitudinal critical angle. This, together with an effect of a dominant Rayleigh wave pole, affects the V(z) measurement of the LSSCW. A method to estimate the longitudinal and shear wave velocities is discussed.<>
Keywords :
acoustic microscopy; focusing; ultrasonic reflection; abrupt phase change; acoustic reflection coefficient; dominant Rayleigh wave pole; leaky surface skimming compressional wave; line-focus-beam acoustic microscope; longitudinal branch point; longitudinal critical angle singularities; shear wave velocities; unphysical Riemann sheet; velocity difference; Acoustic materials; Acoustic measurements; Acoustic reflection; Acoustic waves; Cause effect analysis; Councils; Microscopy; Optical materials; Solids; Surface acoustic waves;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
