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Ultrasonic Beam Focusing and Steering of Array Transducers Based on a Time-Reversal Process

An analytical scheme is employed for the analysis of time-reversal beam focusing and steering in a homogeneous medium. More specifically, a nonparaxial multi-Gaussian beam model is used to simulate the focusing behavior of array transducers composed of multiple rectangular elements. The nonparaxial multi-Gaussian beam model is found to generate accurate beam fields beyond the nonparaxial region. Two different simulation cases are considered here for the focal points specified on and off the central axis of the array transducer. The simulation results show that the focal spot size increases with increasing focal length and focal angle. Furthermore, the maximum velocity amplitude does not always coincide with the specified focal point. Simulation results for the offaxis focusing cases demonstrate the accurate steering capability of the time-reversal focusing.

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