Multidepth synthetic aperture processing of ultrasonic data.
The characterization of the size, shape, and location of subsurface discontinuities in metals using multidepth synthetic aperture processing of ultrasonic data is considered. A technique is proposed to increase the lateral resolution and signal-to-noise ratio when metals of large thickness are tested. The first technique to achieve multidepth was dynamic focusing. The aperture in the proposed technique is simultaneously focused at several depths by means of a computer program, thus avoiding the fixed hardware required in the dynamic focusing technique. Experimental evidence is presented to indicate the improvement in resolution, due to multidepth processing, over the single-focus technique.
Elgarem
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Dept. of Electr. Eng., Northern Illinois Univ., De Kalb, IL.