Digital processing for improved elevation resolution in a three-dimensional tapered phased array imaging system

Three-dimensional ultrasonic imaging with a tapered-thickness phased array (TPA) is investigated. Image data from the lateral and axial dimensions come from conventional B-scan techniques. Information from the third dimension, the elevation dimension, is obtained from frequency analysis of the received signal. The greatest limitation of this system is that the elevation resolution of the image, determined by the quality factor of the tapered transducer element, is significantly worse than the lateral resolution using standard image reconstruction algorithms. By means of digital image restoration techniques based on the degradation model, the elevation resolution can be improved. These methods are discussed, and results from their application to the sampled data from a TPA imaging system are presented. The limitations and uses of these techniques are addressed