Data acquisition system for geophysical diffraction tomography

Geophysical diffraction tomography is an emerging technique that shows promise as a tool for quantitative, high-resolution subsurface imaging. The technique possesses similarities to both X-ray CAT scanners and conventional geophysical seismic profiling. The imaging approach employed in diffraction tomography is a generalization of that used in CAT scanners to account for the diffraction (ray bending) which occurs in the propagation of the longer wavelength acoustic energy. While CAT scanners are devices that rotate about the region to be imaged, geophysical tomography is necessarily limited to fixed instrument configurations such as those employed in geophysical seismic profiling. The geophysical diffraction tomography effort has focused on reducing this technique to practice. This paper presents an overview of the current status of this effort including sample reconstructions obtained through numerical experiments, a description of the hardware, and examples of data collected in the field. Specific emphasis is given to the instrumentation since this represents a significant advance in the state-of-the-art of geophysical data collection and processing. The power of this system is demonstrated by an example of an actual subsurface image obtained in the field. 4 references, 9 figures