LAUSR

Ultrasonic tomography (UT) is an available method for processing monitoring. In this study, a novel dual-excitation method (DEM) for ultrasonic tomography for improving imaging quality is proposed. The DEM was defined and explained first in the study. Two typical bubble flow patterns were established to evaluate the effectiveness of the method using linear back projection (LBP) and fan-shaped LBP (FLBP). In order to quantitatively analyze the imaging quality, the image correlation coefficient (ICC) and the position error (PE) were chosen as two evaluation indexes. For two different bubble flow patterns with a 16-transducer UT system, the ICCs were improved by 13% and 15%, whereas the PEs were reduced by 19% and 4% by the DEM, respectively. Then, the influence of the noise was discussed. Thereafter, two postimaging methods, such as the sum-imaging method (SIM) and the multiplication-imaging method (MIM), were proposed and applied to further enhance the imaging quality. Compared with the original imaging quality, the PEs were reduced by 28% and 6% for the two different bubble flow patterns. The results indicated that the DEM could significantly improve the imaging quality, especially when MIM is assisted for image reconstruction.