Multifocal point beam forming by a single ultrasonic transducer with 3D printed holograms

This paper reported a method for designing monolithic acoustic holograms with consideration of both amplitude and phase modulation, which can be used for multifocal point beam forming by a single element ultrasonic transducer in the frequency of megahertz range. Mask-image-projection-based stereolithography 3D printing technology was induced to manufacture the complex hologram with a pixel resolution of 25 mu m. A nine foci pattern and a letter U pattern acoustic field shown by a 2 MHz transducer and holograms were designed to validate the proposed designing method. Both the hydrophone testing and the simulation results indicated that the holograms designed by our method could form beam patterns accurately in the expected position. Published by AIP Publishing.