Tailoring ultrasonic beams with optoacoustic holography
Tailoring ultrasonic beams with optoacoustic holography
复制标题
利用光声全息技术定制超声波束
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
M. Ritsch
中科院分区：
文献类型：
--
作者：
Alex Meyer;Stefan Gspan;S. Bernet;M. Ritsch
提出了一种激光超声产生和超声全息相结合的方法，用于对产生的超声脉冲进行空间控制。超声波是通过光声效应在水箱中的吸收层处吸收激光脉冲而产生的。为了产生MHz范围内的定义的超声频率，使用声光调制器（AOM）对激光脉冲进行谐波时间调制。此外，激光强度在空间上受到控制。这是用高分辨率液晶空间光调制器（LCD）实现的。计算机生成的图案显示在LCD上，并由扩展的激光束投射到水箱中的吸收层。因此，发射的超声波以预定的方式出现，这是激光光学中的“衍射光学元件”的效果的声学模拟。光学超声产生和衍射转向的灵活方法有望在医学和技术超声诊断中获得新的应用。
A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an acousto-optic modulator (AOM). Additionally, the laser intensity is spatially controlled. This is realized with a high resolution liquid crystal spatial light modulator (LCD). A computer generated pattern is displayed at the LCD and projected by the expanded laser beam to an absorptive layer in the water tank. As a result, the emitted ultrasonic wave emerges in a predetermined way, which is an acoustical analogue to the effect of a "diffractive optical element" in laser optics. The flexible method of optical ultrasound generation and diffractive steering promises new applications in medical and technical ultrasound diagnostics.