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首页> 外文会议>Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-Optics >Experimental investigation of time-reversal of photo-acoustic waves
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Experimental investigation of time-reversal of photo-acoustic waves

机译：光声波时间逆转的实验研究

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Ultrasound focusing through complex media can be achieved using time-reversal techniques. These techniques make use of back-propagating ultrasonic waves generated by localized sources. Such sources generally consist of high acoustic contrasts echoing ultrasonic waves generated by an incident ultrasonic field, or directly by point-like transducers inserted at the desired focusing location. In this work, we experimentally investigate time-reversal of acoustic waves generated by photo-acoustic emission. A frequency-doubled Q-switched Nd:YAG laser was used to illuminate phantom with 5-ns laser pulses. A 128-element ultrasonic transducer array, with a center frequency of 1.5 MHz, was used to detect acoustic waves generated by optically absorbing targets suspended in water. A dedicated 32-channel electronics was used to time-reverse and re-emit the detected ultrasonic field. Gel spheres dyed with India ink (diameter approximately 1-2 mm)illuminated by the laser beam were used to generate the photo-acoustic waves. Time-reversal of the detected field was performed to focus ultrasound in the presence of highly defocusing media in front of the transducer array. We demonstrate how this allows correcting for the aberration in order to provide good quality images in the isoplanetic region surrounding the photo-acoustic source.
机译：通过使用时间反转技术可以实现通过复介质的超声波聚焦。这些技术利用由局部源产生的背传播超声波。这些来源通常由入射超声场产生的超声波的高声学对比，或者直接通过插入所需聚焦位置的点状换能器。在这项工作中，我们通过实验研究了光声发射产生的声波的时间逆转。频率加倍的Q开关Nd：YAG激光器用于用5-ns激光脉冲照亮模体。一个128元件超声换能器阵列，中心频率为1.5MHz，用于检测通过悬浮在水中的光学吸收靶产生的声波。使用专用的32通道电子器件来逆转并重新发出检测到的超声波场。用激光束照射的印度油墨（直径约1-2毫米）染色的凝胶球用于产生光声波。在换能器阵列前面的高度散焦介质存在下，执行检测到的检测场的时间逆转。我们展示了这一点允许校正像差，以便在光声源围绕的Isoplencetic区域提供良好的质量图像。

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