Design method for concave-focusing transducer with super formation surface

Abstract

The invention discloses a design method for a concave-focusing transducer with a super formation surface and belongs to the technical of ultrasonic focusing. By virtue of constructing a super formation surface structure on the surface of a traditional concave focusing transducer and utilizing a cavity resonance mode of the super formation surface structure, the radiation efficiency of the focusing transducer is enhanced. When surface acoustic evanescent waves supported by the super formation surface structure spatially meets a phase matching condition, a coherent diffraction enhancement effect is caused, and improvement on the focusing property is realized; the concave-focusing transducer belongs to innovation of the ultrasonic focusing field; the super formation surface meets the generalized reflection and refraction Snell's law and is capable of realizing discontinuous modulation on phases; by virtue of modulating the super formation surface through a periodic wavy structure, the super formation surface of the concave focusing transducer is capable of regulating and controlling the sound field distribution within a specific frequency range and thus improving the main sidelobe ratio.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic focusing, and relates to a design method for a concave focusing transducer with a metasurface, more specifically, the radiation efficiency is improved through the cavity resonance and coherent diffraction enhancement effect of the metasurface structure, and the focusing is optimized The sound field realizes the focusing method that improves the focusing gain and the ratio of main and side lobe. Background technique [0002] Focusing transducers are an important device in medical ultrasound applications. The common ones are spherical self-focusing transducers and acoustic lens focusing transducers. The spherical self-focusing transducer makes piezoelectric ceramics as a concave surface, and uses the concave radiation surface to focus directly, and the focusing effect is better. High-intensity focused ultrasound (HIFU) technology is a new type of non-invasive trauma treatment technology, which h...

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Problems solved by technology

However, this application belongs to the design of the acoustic lens. Because of the curvature of the acoustic lens, there is an acoustic path difference on the acoustic lens emission interface, which in turn leads to a large difference in the initial phase and transmittance of the effective radiation surface of the acoustic wave. It can be applied to the situation of small opening angle, and defects such as multi-focus will appear in the case of large opening angle; and the physical mechanism of the application is to concentrate the diffracted energy to the focus area through the acoustic collimation effect to reduce the side lobe amplitude, Improve focus gain, so this application can only be applied to planar transducers, but not to concave focusing transducers, which has its limitations in application

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