Scattering noise reduction
Research on denoising applied to ultrasound has always been of great interest in the ultrasound community
Want to get rid of structural noise ?
Testing parts made of coarse-grained steel is a major challenge in the aerospace, metallurgy, oil & gas, power generation and nuclear industries. These materials are typically used because of their ability to resist to high temperature and pressure. The ultrasonic inspection of these materials is complicated due to their heterogeneous structure and the resultant attenuation of sound. The acoustic scattering induced by the heterogeneity generates structural noise in the ultrasonic signals and images which reduces the signal-to-noise ratio (SNR).
The TPAC team has developed new inspection methods to address this inspection complexity. For example, one of these methods, called pDAS, is based on TPAC’s recent research work and can dramatically decrease structural noise while increasing flaw responses. The pDAS beamforming method can even be combined with TPAC’s other cutting-edge methods such as TFM or PWI. Another benefit of this technique is that it is as fast as more common approaches and can then replace them advantageously in inspection procedures.
The presented example is based on a measurement from an austenitic-ferritic stainless-steel block. The defects are side drilled holes with 0.4mm diameter. Images for TFM (upper-left) and pDAS (3 images) are presented in the figure below. The corresponding SNR values are also given. TFM gives a SNR of 26.6dB. The pDAS methods give 44.8, 59.2 and 71.9dB for different algorithm settings.