3-D ultrasonic image reconstruction in frequency domain using a virtual transducer model

Area of Science:

• Non-destructive Testing
• Ultrasonic Imaging
• Signal Processing

Background:

• Traditional ultrasonic image reconstruction methods like DAS-based synthetic aperture imaging are inefficient for 3-D reconstruction.
• Existing methods often neglect transducer geometry effects, limiting image resolution.
• High-resolution 3-D ultrasonic imaging is crucial for accurate defect detection.

Purpose of the Study:

• To develop a novel 3-D ultrasonic image reconstruction method.
• To overcome the limitations of existing methods in terms of efficiency and accuracy.
• To achieve high-resolution 3-D imaging considering wave diffraction and transducer geometry.

Main Methods:

• Proposed a 3-D ultrasonic image reconstruction method based on the synthetic aperture wavenumber algorithm.
• Modeled a focused transducer as a virtual planar transducer in the frequency domain.
• Utilized non-uniform fast Fourier transform and deconvolution for image reconstruction.

Main Results:

• Achieved a lateral resolution of 290.2 μm, surpassing the transducer's theoretical limit (523.24 μm).
• Reconstructed a 3-D image (1000×100×100 pixels) in 0.744 seconds, compared to 1163.8 seconds for time-domain SAFT.
• Demonstrated significantly improved efficiency and accuracy in 3-D ultrasonic image reconstruction.

Conclusions:

• The proposed synthetic aperture wavenumber algorithm offers superior lateral resolution and efficiency for 3-D ultrasonic imaging.
• The method effectively accounts for wave diffraction and transducer geometry, enabling refocusing in non-focal zones.
• This approach shows significant potential for real-time 3-D non-destructive testing applications with advanced hardware.