An optically-transparent transducer with a high-NA and wide-bandwidth for photoacoustic microscopy (PAM)
An optically-transparent transducer with a high-NA and wide-bandwidth for photoacoustic microscopy (PAM)
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一种用于光声显微镜 (PAM) 的具有高数值孔径和宽带的光学透明传感器
DOI：
10.1117/12.2576834
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Zou, Jun
中科院分区：
文献类型：
--
作者：
Fang, Cheng;Zou, Jun
在光声显微镜 (PAM) 中，超声换能器在检测 PA 信号中发挥着关键作用。然而，传统的超声换能器是光学不透明的，这可能会阻碍激励激光有效传递到目标上。最近，人们研究了光学透明超声换能器来解决这个问题。然而，迄今为止所展示的透明换能器要么具有较小的数值孔径（NA），要么具有较窄的带宽，这限制了它们的声焦斑尺寸，从而限制了可实现的空间分辨率。在本文中，我们报告了一种新型聚焦透明聚偏二氟乙烯 (PVDF) 换能器，其数值孔径高达 0.64，声脉冲回波带宽达 120%。实验表征表明，其声学中心频率和带宽分别为 36 MHz 和 44 MHz。声焦点直径和区域分别为37.8μm和210μm。借助新型透明换能器，双模态声分辨率 PAM (AR-PAM) 和脉冲回波超声显微镜 (PEUSM) 已通过埋入鸡胸肉不同深度的黑色墨水填充聚酰亚胺管组成的目标进行了演示。成像结果表明，即使穿透深度大于 3 mm，（声学）横向和轴向分辨率也能保持。
In photoacoustic microscopy (PAM), the ultrasound transducer plays a critical role in detecting the PA signals. However, conventional ultrasound transducers are optically opaque, which could hinder the effective delivery of the excitation laser onto the target. Recently, optically-transparent ultrasound transducers have been investigated to address this issue. Nevertheless, the transparent transducers demonstrated so far have either a small numerical aperture (NA) or narrow bandwidth, which limits their acoustic focal spot sizes and therefore achievable spatial resolutions. In this paper, we report a new focused transparent polyvinylidene fluoride (PVDF) transducer with a high NA of 0.64 and a wide acoustic pulseecho bandwidth of 120%. Experiment characterization shows that it has an acoustic center frequency and bandwidth of 36 MHz and 44 MHz, respectively. The acoustic focal diameter and zone are 37.8 μm and 210 μm, respectively. With the new transparent transducer, dual-modal acoustic-resolution PAM (AR-PAM) and pulse-echo ultrasound microscopy (PEUSM) have been demonstrated with a target consisting of black-ink-filled polyimide tubing buried in chicken breast at different depths. The imaging results show that both the (acoustic) lateral and axial resolutions can be maintained even at a penetration depth of larger than 3 mm.