Air-coupled ultrasonic imaging method based on wavelet analysis and related algorithms

TLDR: In this paper, an air-coupled ultrasonic imaging method based on wavelet analysis and related algorithms is presented. But the method is not suitable for the detection of small size defects.

Abstract: The invention discloses an air-coupled ultrasonic imaging method based on wavelet analysis and related algorithms. Imaging is carried out by using wavelet coefficients of a sub-band and related coefficients of a reference signal as characteristic quantities, enabling effective elimination measurement-induced white Gaussian noise and strength fluctuation noise of air-coupled ultrasonic transmitting signals and improving signal to noise ratio of an image. Meanwhile, whether small size defects exist or not is judged through minimum values of related coefficients, thus adaptively adjusting a smooth filter window, the size of the smooth window is enlarged upon a large defect size, thereby reducing background noise, the size of the window is reduced upon a small defect size, highlighting signal details and thereby implementing 'adaptive focusing' and improving the ability to detect small defects. The imaging method has a promising application prospect in the field of air-coupled ultrasonic detection.