基于自相关方法的光声多普勒碳颗粒悬混液流速测量  

Photoacoustic Doppler flowmetry of carbon particles flow using autocorrelation method

作　　者：卢涛[1] 白薇薇[1] LU Tao;BAI Wei-wei(College of Electrical Engineering,Henan University of Technology,Zhengzhou 450001,China)

机构地区：[1]河南工业大学电气工程学院,郑州450001

出　　处：《医疗卫生装备》2018年第3期15-18,共4页Chinese Medical Equipment Journal

基　　金：河南省自然科学基金(162300410054);河南省省属高校基本科研业务费专项(2015RCJH13)

摘　　要：目的:采用自相关方法测量直径为数十微米的碳颗粒悬混液的轴向流速。方法:采用基于连续独立A扫光声信号的自相关方法计算光声多普勒频移。光声信号由波长为532 nm、重复频率为20 Hz的脉冲激光激励,采用中心频率为5 MHz的超声换能器、低噪声前置放大器和示波器采集、存储光声信号。碳颗粒悬混液由微量注射泵驱动。时域光声信号由希尔伯特变换转变为复信号,然后由复光声信号的自相关计算多普勒频移,最后由若干独立A扫光声信号自相关的平均值得到光声多普勒频移。结果:该方法的可行性通过测量流速范围为5~60 mm/s的碳颗粒悬混液得到了初步验证,实验结果显示信号的自相关结果与速度预设值之间呈近似线性分布。结论:基于自相关方法测量光声多普勒碳颗粒悬混液流速可行,可以使用中心频率较高的超声换能器进一步提高频移测量的自相关结果和流速值之间的线性相关性。Objective To measure the axial flowing velocity of a suspension carbon particles of tens of micrometer-scale with an autocorrelation method.Methods The photoacoustic Doppler frequency shift was calculated from a series of individual A scans using an autocorrelation method.A 532 nm pulsed laser with the repetition rate of 20 Hz was used as a pumping source to generate photoacoustic signals.The photoacoustic signals were detected using a focused PZT ultrasound transducer with central frequency of 5 MHz.The suspension of carbon particles was driven by a syringe pump.The complex photoacoustic signal was calculated by the Hilbert transformation from time-domain photoacoustic signal.The complex photoacoustic signal was then autocorrelated to calculate Doppler frequency shift.The photoacoustic Doppler frequency shift was calculated by averaging the autocorrelation results of individual A scans.Results The feasibility of the proposed autocorrelation method was preliminarily demonstrated by quantifying the motion of a carbon particles suspension flow from 5 to 60 mm/s.The experimental results showed that the autocorrelation result approximately agreed with the setting velocity linearly.Conclusion It's feasible to measure photoacoustic Doppler flowmetry of carbon particles,and an ultrasonic transducer with high central frequency may promote the linear correlation between the autocorrelation result and flow rate during frequency shift measurement

关 键 词：自相关 光声多普勒流速测量 脉冲激光 碳颗粒悬混液 生物光子学 

分 类 号：R318[医药卫生—生物医学工程]