Ultrasound Reflection-Mode Tomography Using Fan-Shaped-Beam Insonification

Abstrucl-In pursuing the objective of developing an inexpensive and simple microprocessor-based real-time imaging system for nondestructive testing (NDT) applications two tasks have been performed. First, data reduction techniques have been developed, which reduce and simplify the processing task considerably. Secondly, existing imaging techniques have been improved, and new ones developed, to improve the quality of the images. The data-reduction scheme involves dispensing with the carrier information of the pulses and using, for image reconstruction, only the peaks of the rectified RF pulses and their corresponding times of arrival. The processing algorithm is a simplified form of convolution backprojection. The latter task has given particular attention to imaging defects in rods and pipes by incorporating information from shear scanning, as well as compression scanning, in the final images. Computer simulation and images of test samples, as well as images of real defects in steel, aluminium, and polyester resin cylindrical samples are presented.

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