Reducing the Negative Effects of Grating through A-Scan Post Processing When Compensating for Poor Element Directivity

With respect to industrial NDT applications, increase in computation power has made elaborate post-processing of large ultrasonic array data sets a feasible alternative to traditional processing schemes. Instead of firing transmitter elements at staggered intervals to produce wave fronts, the full matrix of time domain signals (A-Scans) from every transmitter-receiver pair can be captured and post-processed, allowing for improved accuracy in imaging. In this paper, a new signal processing technique is introduced which modifies full matrix A-Scans as part of post-processing algorithm implementation, compensating for poor element directivity in directions away from element normals. Utilization of this technique is shown to reduce the negative effects of grating lobes in imaging over the previously known technique of boosting imaging intensity at angles where directivity of focusing elements is poor. Experimental results are presented to verify this.