Abstract
Although the traditional focused acoustic-vortex (FAV) beams can be realized by a spherical acoustic lens, the manipulation performance still suffers from the incomplete focusing at a preassigned point. In the current study, by applying the Fermat’s principle to the phase-coded circular array of planar sectorial sources, a hyperboloidal concave acoustic lens determined by the refractive index and the focal length is designed to construct hyperboloidal-focused acoustic-vortex (H-FAV) tweezers to improve the manipulation capability in a minimized focal region. Compared with the FAV beam, the peak-pressure of the H-FAV tweezer is obviously enhanced in a smaller-sized focal region, and the trapping capability of the tweezer can be greatly improved by the strengthened acoustic gradient force due to the smaller vortex radius. With the established 16-channel system, H-FAV beams of different orders are built using a hyperboloidal lens manufactured by 3-D printing. The experimental acoustic fields of pressure and phase show good agreements with numerical results and attest to the improved performance of H-FAV tweezers. Moreover, benefiting from the flexible and controllable focusing, the H-FAV tweezers exhibits prosperous perspectives in high-precision application fields of acoustic focusing, ultrasonic therapy, acoustic levitation and particle manipulation.
Published Version
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