Morris Paul, Hurrell Andrew, Shaw Adam, Zhang Edward, Beard Paul
Department of Medical Physics and Bioengineering, University College London, London, United Kingdom.
J Acoust Soc Am. 2009 Jun;125(6):3611-22. doi: 10.1121/1.3117437.
A dual sensing fiber-optic hydrophone that can make simultaneous measurements of acoustic pressure and temperature at the same location has been developed for characterizing ultrasound fields and ultrasound-induced heating. The transduction mechanism is based on the detection of acoustically- and thermally-induced thickness changes in a polymer film Fabry-Perot interferometer deposited at the tip of a single mode optical fiber. The sensor provides a peak noise-equivalent pressure of 15 kPa (at 5 MHz, over a 20 MHz measurement bandwidth), an acoustic bandwidth of 50 MHz, and an optically defined element size of 10 microm. As well as measuring acoustic pressure, temperature changes up to 70 degrees C can be measured, with a resolution of 0.34 degrees C. To evaluate the thermal measurement capability of the sensor, measurements were made at the focus of a high-intensity focused ultrasound (HIFU) field in a tissue mimicking phantom. These showed that the sensor is not susceptible to viscous heating, is able to withstand high intensity fields, and can simultaneously acquire acoustic waveforms while monitoring induced temperature rises. These attributes, along with flexibility, small physical size (OD approximately 150 microm), immunity to Electro-Magnetic Interference (EMI), and low sensor cost, suggest that this type of hydrophone may provide a practical alternative to piezoelectric based hydrophones.
已开发出一种双传感光纤水听器，它能够在同一位置同时测量声压和温度，用于表征超声场和超声诱导加热。其传感机制基于检测沉积在单模光纤尖端的聚合物薄膜法布里-珀罗干涉仪中由声学和热学引起的厚度变化。该传感器的峰值等效噪声压力为15 kPa（在5 MHz时，测量带宽为20 MHz），声学带宽为50 MHz，光学定义的元件尺寸为10微米。除了测量声压外，还可以测量高达70摄氏度的温度变化，分辨率为0.34摄氏度。为了评估该传感器的热测量能力，在模拟组织的体模中的高强度聚焦超声（HIFU）场焦点处进行了测量。结果表明，该传感器不易受粘性加热影响，能够承受高强度场，并且在监测温度升高的同时可以同时获取声学波形。这些特性，连同灵活性、小尺寸（外径约150微米）、抗电磁干扰（EMI）以及低成本，表明这种类型的水听器可能为基于压电的水听器提供一种实用的替代方案。
