Determining Damping Loss in Modeling GHz Acoustic Block through Inverse Analysis for Accurate Ultrasonic Wavefront Computation Apparatus

The Ultrasonic wavefront computation apparatus (UWFCA) is designed to derive the Fourier Transform (FT) using gigahertz acoustic waves generated by piezoelectric transducer arrays. The waves propagate through acoustic blocks and an ultrasonic lens, yielding FT that can be digitized at the focal plane. In the full-wave simulation of the UWFCA, the damping loss within the acoustic blocks is usually approximated using an empirical value. However, the imprecise modeling of the GHz acoustic block can markedly degrade the accuracy of the FT results from UWFCA. To address this issue, we present an inverse analysis method to determine the damping loss in the GHz acoustic block for accurate UWFCA modeling based on measured data. We integrate the total displacement fields at different planes within the GHz acoustic block for various damping loss factors. Thus, the relationship between the loss and different damping loss factors is established. Based on the measured results, we employ regression method and inverse analysis to determine the accurate damping loss factor applicable to the gigahertz acoustic block. The simulated FT result agrees well with the analytical one, and the displacement distributions show how the acoustic waves form an FT pattern.