Enhanced pulsed thermoacoustic imaging by noncoherent pulse compression
Enhanced pulsed thermoacoustic imaging by noncoherent pulse compression
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DOI：
10.1063/5.0062148
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发表时间：
2021-11-07
影响因子：
3.2
通讯作者：
Deng, Yiming
中科院分区：
文献类型：
--
作者：
Alzuhiri, Mohand;Song, Jian;Deng, Yiming
微波诱导热声成像（TAI）是一种结合电磁辐射和超声波的混合成像技术，可实现高对比度和亚毫米空间分辨率。这些特性使TAI成为检测材料异常的良好候选者，这些材料异常改变了材料的电特性，而材料密度没有明显的变化。传统的脉冲TAI系统通过向成像目标发送单个短脉冲然后检测所生成的压力信号来工作;因此，需要非常高的高峰功率微波脉冲或数据平均来产生具有高信噪比（SNR）的图像。在本文中，我们提出了提高信噪比的脉冲TAI系统，通过使用非相干脉冲压缩。在该方法中，预定义的脉冲编码信号被用于照射成像的样本，并且接收到的压力信号与和激励信号的功率分布相关的模板交叉相关。所提出的方法可以很容易地部署到脉冲TAI系统，而不需要对RF源进行重大的系统修改，因为它只需要一个定时电路来控制RF脉冲的触发时间。在本文中，我们通过实验证明，所提出的方法大大提高了信噪比的TAI信号和图像，并可用于减少采集时间，通过降低数据平均的数量或降低所需的峰值功率从RF源。
Microwave-induced thermoacoustic imaging (TAI) is a hybrid imaging technique that combines electromagnetic radiation and ultrasonic waves to achieve high imaging contrast and submillimeter spatial resolution. These characteristics make TAI a good candidate to detect material anomalies that change the material electric properties without a noticeable variation in material density. Conventional pulsed TAI systems work by sending a single short pulse to the imaged target and then detecting the generated pressure signal; therefore, a very high peak power microwave pulse or data averaging is needed to produce images with a high signal-to-noise ratio (SNR). In this paper, we propose to enhance the SNR of pulsed TAI systems by using non-coherent pulse compression. In this approach, a predefined pulse coded signal is used to illuminate the imaged sample and the received pressure signal is cross correlated with a template that is related to the power profile of the excitation signal. The proposed approach can be easily deployed to pulsed TAI systems without the need for major system modifications to the RF source because it only requires a timing circuit to control the triggering time of the RF pulses. In this paper, we demonstrate experimentally that the proposed approach highly improves the SNR of TAI signals and images and can be used to reduce the acquisition time by lowering the number of data averaging or reduce the required peak power from RF sources.