Affiliations: [a] School of Information Science and Technology, ShanghaiTech University, Shanghai, China | [b] Yangjiang Nuclear Power Co., Ltd., Guangdong, China
Correspondence:
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Corresponding authors: Cai Long, School of Information Science and Technology, ShanghaiTech University, Shanghai, China. E-mail: longcai@shanghaitech.edu.cn. Chaofeng Ye, School of Information Science and Technology, ShanghaiTech University, Shanghai, China. E-mail: yechf@shanghaitech.edu.cn
Abstract: It is still a challenging problem to detect small defects for eddy current array probes, which requires the probes to possess excellent sensitivity, as well as high spatial resolution. This paper presents a novel high-resolution magnetic field imaging probe with two rows of tunneling magnetoresistance (TMR) array sensors. The bare die sensors are integrated on a printed circuit board by golden wire bonding technology. The two rows of sensors are placed staggered with each other. The data of the two arrays are merged into a matrix, in which way the image pixel pitch is increased to 0.25 mm. The probe employs a differential scheme to suppress the noise, so as to detect the weak signal of small defects. To highlight the weak defect indications, feature extraction and segmentation algorithms are developed. The experimental results confirm that the proposed method can inspect a small defect with dimensions 1 mm (length) × 0.1 mm (width) × 0.1 mm (depth) on a stainless-steel sample.
