Effect of surface discontinuities on V(z) and V(z, x) for the line-focus acoustic microscope

A Time-Resolved Line-Focus Acoustic Microscopy Technique for Surface-Breaking Crack Depth Determination

“…[8]. It should be mentioned that in order to capture the absolute time delay of each received wave, an absolute phase-shift (i.e.…”

“…4 shows the calculated waveforms at z0 = -3mm and x 0 = -1.5mm for three cases: ( a) a perfect surface; (b) a surface-breaking crack with its RR and TR [9] described by the solid lines in Fig. 5; ( c) an infinitely deep surface-breaking crack [8]. As mentioned in the previous section, subtractions are needed for the signals arriving at tr to get vr and v0 • The solid line in Fig.…”

Measuring Thin-Film Elastic Constants by Line-Focus Acoustic Microscopy

“…Calculating the angular spectrum function L,Ckx) follows the method presented by Li et al (16) with some modifications. Based on diffraction theory and some assumptions and approximations discussed by Atalar, (2) where r and 8m are the radius of curvature and the half-aperture angle of the lens, respectively; fL is its focal length; cos 8' = (1 -c .…”

Acoustic Microscopy Measurements to Correlate Surface Wave Velocity and Surface Roughness

“…The surface wave velocity can be obtained from the periodic variation of the V(z) curve [ 2 ] . For a smooth surface, the V(z) curve has been calculated analytically by Somekh et al [ 3 ] and Li et al [ 4 ], based on the Fourier optics approach.…”

“…The surface of the specimen is irregularly rough. The functions L1 (k~) and L2(kx), which are the angular spectrum functions of the acoustic lens, have been determined by Li et al [ 4 ] for a line-focus acoustic lens. The reflection function S(kx,k~), which is dependent on the material properties and the surface profile of the specimen, has been obtained by Li and Achenbach [ 5 ] for a sinusoidal surface by using the Rayleigh method.…”