SRAS: Spatially Resolved Acoustic Spectroscopy
We can use the O-SAM to map the SAW velocity in one or more directions, if we use a technique we have called spatially resolved acoustic spectroscopy (SRAS). This allows us to image micro- and macro-structure, probe coating thicknesses, and potentially image residual surface stress and porosity. The lateral resolution achievable is currently of the order of 50µm, and the velocity resolution of the order of 1ms-1.
More information and pictures to follow... in the mean time, here are some links to some papers:
 Steve D. Sharples, Matt Clark, Wenqi Li and Mike G. Somekh, "Rapid imaging of microstructure using spatially resolved acoustic spectroscopy," presented at the 1st International Symposium on Laser Ultrasonics, Montréal, Canada, July 16-18, 2008.
 Steve D. Sharples, Matt Clark, Mike G. Somekh, Elizabeth E. Sackett, Lionel Germain and Martin A. Bache, "Rapid grain orientation imaging using spatially resolved acoustic spectroscopy," presented at the International Congress on Ultrasonics, Vienna, April 9-13, 2007.
 S. D. Sharples, M. Clark, and M. G. Somekh, "Spatially resolved acoustic spectroscopy for fast noncontact imaging of material microstructure," Optics Express 14, 10435-10440, 2006.
 S. D. Sharples, M. Clark and M. G. Somekh, "Fast noncontact imaging of material microstructure using local surface acoustic wave velocity mapping," in IEEE International Ultrasonics Symposium, 1-4, 886-889, 2005.