Laser generation of narrow‐band surface waves

1992 ◽  
Vol 92 (5) ◽  
pp. 2527-2531 ◽  
Author(s):  
Jin Huang ◽  
Sridhar Krishnaswamy ◽  
Jan D. Achenbach
Keyword(s):  
Surface Waves ◽  
Narrow Band ◽  
Laser Generation

Remote laser generation of narrow-band surface waves through optical fibers

1999 ◽  
Vol 46 (6) ◽  
pp. 1551-1557 ◽  
Author(s):  
F.L. Di Scalea ◽  
T.P. Berndt ◽  
J.B. Spicer ◽  
B.B. Djordjevic
Keyword(s):  
Surface Waves ◽  
Optical Fibers ◽  
Narrow Band ◽  
Laser Generation

Laser-generation of narrow-band surface waves

2002 ◽  
Author(s):  
J. Huang ◽  
S. Krishnaswamy ◽  
J.D. Achenbach
Keyword(s):  
Surface Waves ◽  
Narrow Band ◽  
Laser Generation

scholarly journals Automated detection and association of surface waves

1994 ◽  
Vol 37 (3) ◽  
Author(s):  
R. G. North ◽  
C. R. D. Woodgold
Keyword(s):  
Surface Waves ◽  
Group Velocity ◽  
Rayleigh Waves ◽  
Arrival Time ◽  
Narrow Band ◽  
Broad Band ◽  
Detection Algorithm ◽  
Automated Detection ◽  
Short Period ◽  
Group Velocities

An algorithm for the automatic detection and association of surface waves has been developed and tested over an 18 month interval on broad band data from the Yellowknife array (YKA). The detection algorithm uses a conventional STA/LTA scheme on data that have been narrow band filtered at 20 s periods and a test is then applied to identify dispersion. An average of 9 surface waves are detected daily using this technique. Beamforming is applied to determine the arrival azimuth; at a nonarray station this could be provided by poIarization analysis. The detected surface waves are associated daily with the events located by the short period array at Yellowknife, and later with the events listed in the USGS NEIC Monthly Summaries. Association requires matching both arrival time and azimuth of the Rayleigh waves. Regional calibration of group velocity and azimuth is required. . Large variations in both group velocity and azimuth corrections were found, as an example, signals from events in Fiji Tonga arrive with apparent group velocities of 2.9 3.5 krn/s and azimuths from 5 to + 40 degrees clockwise from true (great circle) azimuth, whereas signals from Kuriles Kamchatka have velocities of 2.4 2.9 km/s and azimuths off by 35 to 0 degrees. After applying the regional corrections, surface waves are considered associated if the arrival time matches to within 0.25 km/s in apparent group velocity and the azimuth is within 30 degrees of the median expected. Over the 18 month period studied, 32% of the automatically detected surface waves were associated with events located by the Yellowknife short period array, and 34% (1591) with NEIC events; there is about 70% overlap between the two sets of events. Had the automatic detections been reported to the USGS, YKA would have ranked second (after LZH) in terms of numbers of associated surface waves for the study period of April 1991 to September 1992.

Theory of Laser Generation of Surface Waves Using Optically Absorbing Coatings

1983 ◽  
Author(s):  
R.E. Higashi ◽  
R.K. Mueller ◽  
W.P. Robbins
Keyword(s):  
Surface Waves ◽  
Laser Generation

Normal mode sound propagation in an ocean with random narrow‐band surface waves

1993 ◽  
Vol 94 (1) ◽  
pp. 279-292 ◽  
Author(s):  
G. V. Anand ◽  
Mathews K. George
Keyword(s):  
Surface Waves ◽  
Normal Mode ◽  
Sound Propagation ◽  
Narrow Band

scholarly journals Laser Generation of Narrow Band Ultrasound

1989 ◽  
pp. 505-512 ◽  
Author(s):  
James W. Wagner ◽  
John B. Deaton
Keyword(s):  
Narrow Band ◽  
Laser Generation

Laser Generation of Surface Waves on Cylinder with a Slow Coating

2008 ◽  
Vol 25 (12) ◽  
pp. 4314-4317 ◽  
Author(s):  
Zhang Shi-Gong ◽  
Hu Wen-Xiang
Keyword(s):  
Surface Waves ◽  
Laser Generation

A pulsed photoacoustic investigation of ultrasonic mode conversion

1986 ◽  
Vol 64 (9) ◽  
pp. 1334-1340 ◽  
Author(s):  
D. A. Hutchins ◽  
F. Nadeau ◽  
P. Cielo
Keyword(s):  
Nondestructive Testing ◽  
Surface Waves ◽  
Mode Conversion ◽  
Pulsed Laser ◽  
Longitudinal Shear ◽  
Laser Generation ◽  
Bulk Waves ◽  
Interferometric Detection

Experiments have been undertaken into the generation and detection of ultrasonic transients in metals over a 40-MHz bandwidth, using pulsed-laser generation and interferometric detection. Longitudinal, shear, and surface waves have been investigated, and their form compared favorably to theory. The techique has been used to study the interaction of surface and bulk waves with slots in the surface of a plate. It has been shown that significant mode conversion occurred from surface to bulk waves and vice versa. The significance of this result to nondestructive testing is discussed.

Laser generation of narrow-band and directed ultrasound

Ultrasonics ◽  
1989 ◽  
Vol 27 (6) ◽  
pp. 323-330 ◽  
Author(s):  
A.D.W. McKie ◽  
J.W. Wagner ◽  
J.B. Spicer ◽  
C.M. Penney
Keyword(s):  
Narrow Band ◽  
Laser Generation
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