Target acoustic field and transducer state optimization using Diff-PAT

Abstract

Phased array transducers (PATs) are used in many applications, from airborne ultrasonic tactile displays to acoustic levitation. Acoustic holograms play a significant role in determining the performance of these applications. Many PATs and optimizers have been developed; however, only the following have been demonstrated in the literature: “phase” and “phase and amplitude” control of transducers and “phase” and “amplitude” only control at target points. Thus, most of the combinations of transducer state and target acoustic field conditions are yet to be explored. Here, we explore such combinations using Diff-PAT, one of the latest acoustic hologram optimizers. Diff-PAT is based on automatic differentiation and stochastic gradient descent. This optimizer achieves higher accuracy than conventional optimizers. We formulated multiple loss functions and wave propagators to enable each combination of the operation mode and quantitatively assessed the performance of each combination. The developed optimizers will offer new opportunities in the field and could allow further simplifications in PAT applications.