Time reversal Bayesian ultrasonic array imaging for non-destructive testing

In non-destructive testing (NDT), it is desirable to have as much information as possible about the size, orientation, and shape of a defect. But due to the reflections in numerous dispersive acoustic modes and the mode conversion that occurs at the defects, the resulting images become very difficult to interpret. This paper designs time reversal (TR) based Bayesian estimators with the goal of compensating the effects of multi-modal propagation. We present a linear acoustic model for imaging the defects and use TR to reconstruct the image using a linear Minimum Mean Square Error (MMSE) beamformer. The simulation results show that the TR based MMSE beamformer is successful to achieve a significantly higher accuracy in localizing the scatterers as compared to its conventional counterpart.