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Focusing Of Longitudinal Ultrasonic Waves In Air With An Aperiodic Flat Lens, John T. Welter, Shamachary Sathish, Daniel Christensen, Philip Brodrick, Jason D. Heebl, Matthew Cherry
Focusing Of Longitudinal Ultrasonic Waves In Air With An Aperiodic Flat Lens, John T. Welter, Shamachary Sathish, Daniel Christensen, Philip Brodrick, Jason D. Heebl, Matthew Cherry
U.S. Air Force Research
Modeling and experimental results of an ultrasonic aperiodic flat lens for use in air are presented. Predictive modeling of the lens is performed using a hybrid genetic-greedy algorithm constrained to a linear structure. The optimized design parameters are used to fabricate a lens. A method combining a fiber-disk arrangement and scanning laser vibrometer measurements is developed to characterize the acoustic field distribution generated by the lens. The focal spot size is determined to be 0.88 of the incident wavelength of 8090 kHz at a distance of 2.5 mm from the lens. Theoretically computed field distributions, optimized frequency of operation, and …