In-situ Optimization of Acoustic Hologram with Digital Twin

Abstract

As the use of acoustophoresis methods such as ultrasonic haptic sensation, acoustic levitation, acoustic streamings, and displays becomes more prevalent, the need for the accurate generation of acoustic holograms has increased. However, experimental results have shown that the actual acoustic field may differ from the simulated field owing to uncertainties in the transducer position, power and phase, or from nonlinearity and inhomogeneity in the field. Traditional methods for experimentally optimizing acoustic holograms require prior calibration and do not scale well with the number of variables. Our proposed digital twin approach combines feedback from experimental measurements in the physical setup with numerically obtained derivatives of the loss function using automatic differentiation to optimize the loss function. This approach is faster and more efficient than the classical finite difference approach, making it beneficial for various applications such as acoustophoretic volumetric displays, ultrasonic haptic sensations, focused ultrasound therapy, and non-destructive testing.