Abstract Ultrasonic superresolution images can be generated using a polymer ball lens. Here, we provide an image formation model for this superresolution imaging method. The imaging system is comprised of a circular flat transducer operating in pulse-echo mode with a central frequency of 1 MHZ , and a ball lens centered in the beam axis of symmetry. The wavelength in water is λ 0 = 1.5 mm . The system experimentally achieves a resolution of 0.6 λ 0 in the focal plane at one wavelength away from the lens. Finite-element simulations are performed to compute the point-spread function of the system. The obtained numerical results are remarkably consistent with experimental data. For illustration purpose, the superresolution method is compared with a conventional ultrasonic system based on a spherically focused transducer. Our technique presents twice more resolution with a shorter depth-of-field of 2 λ 0 . Possible applications that take advantage of these features are discussed, as well as some limitations of the proposed technique.

中文翻译：

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使用聚合物球透镜的超声超分辨率成像模型

摘要 超声波超分辨率图像可以使用聚合物球透镜生成。在这里，我们为这种超分辨率成像方法提供了一个图像形成模型。成像系统由一个圆形平面换能器组成，该换能器在中心频率为 1 MHZ 的脉冲回波模式下工作，以及一个以光束对称轴为中心的球透镜。在水中的波长为 λ 0 = 1.5 mm 。该系统通过实验在距透镜一个波长的焦平面上实现了 0.6 λ 0 的分辨率。执行有限元模拟以计算系统的点扩展函数。所得数值结果与实验数据非常一致。出于说明目的，将超分辨率方法与基于球面聚焦换能器的传统超声系统进行了比较。我们的技术以 2 λ 0 的更短景深呈现两倍以上的分辨率。讨论了利用这些功能的可能应用，以及所提议技术的一些限制。