Ultrasonic Phased Array Sparse TFM Imaging Based on Virtual Source and Phase Coherent Weighting

Jin Yang,Lin Luo,Yu Zhang,Kai Yang

doi:10.1109/access.2020.3030246

Abstract

Total focus method (TFM) is an ultrasonic phased array imaging method and has a larger dynamic focusing range and higher spatial resolution than traditional imaging methods. But TFM needs to process a large amount of data, resulting in a long imaging time, which greatly limits its application and development in the industrial field. The sparse method can improve the computing efficiency by reducing the amount of data, but the resolution and intensity of sparse image are very low. This paper proposes a virtual source sparse TFM (VSSTFM) method based on phase coherent weighting (PCW) to improve the spatial resolution and intensity of the sparse TFM imaging. The layout of virtual sources in the virtual source array is designed and optimized by genetic algorithm. According to the phase distribution characteristics of the ultrasonic testing signal, a phase coherence factor is constructed to weight the VSSTFM image to further improve the image quality. Experimental results show that compared with conventional TFM, the proposed method can improve the imaging efficiency by 66.56 % while providing significantly higher image quality than TFM imaging.

Highlights

Compared with traditional ultrasonic testing, ultrasonic phased array testing has higher resolution and sensitivity, and adapts to various complex scenes, which makes it widely used in the nondestructive testing and has a bright prospect [1], [2]
This paper proposes a virtual source sparse total focusing method (TFM) (VSSTFM) method based on phase coherent weighting (PCW)
Compared with TFM, the array performance index (API) of sparse TFM images is obviously increased, which shows that the spatial imaging resolution of sparse TFM is greatly reduced

Summary

Introduction

Compared with traditional ultrasonic testing, ultrasonic phased array testing has higher resolution and sensitivity, and adapts to various complex scenes, which makes it widely used in the nondestructive testing and has a bright prospect [1], [2]. Holmes et al [3] first proposed the full matrix capture (FMC) and total focusing method (TFM) model in 2005. Compared with traditional phased array imaging, TFM uses a full matrix data, which can focus on any point of the imaging area and has excellent imaging quality. It has been gradually applied to many industrial fields, such as aerospace, nuclear industry, oil and gas, etc. The data of TFM is very large, and the imaging time is very long and cannot be imaged in real time, which limits its further development and application [7].

Results

Discussion

Conclusion