Analytic evaluation of sampled aperture ultrasonic imagingtechniques for NDE

摘要

This paper presents a theoretical comparison of three genericnsampled aperture ultrasonic imaging systems for nondestructivenevaluation. The imaging systems are categorized according to theirnsource-receiver combination for data acquisition: common-source,nback-scatter, and full-array imaging. First, forward modeling isnperformed for a point source and a point receiver. This is then used tonmodel the received data set for each of the imaging categories.nSubsequently, the inversion algorithm for each category is derived, andntheir performance is evaluated in terms of resolution, noise, andncomputation. We show that in terms of resolution, back-scatter imagingnis the best, followed by full-array and common-source imaging. However,nin terms of material noise, full-array imaging is the best, withnback-scatter and common-source imaging having the same material noisenresponse. Full-array imaging is the only system with inherent redundancynto reduce electronic noise, but at the expense of significantly morencomputation. The physical transducer is in the full-array category,nallowing mechanical scanning to be traded for dynamic focusing andncomputational power