Transverse flow velocity measurement of carbon particles based on photoacoustic Doppler standard deviation calculated with autocorrelation method(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2018年第5期
- Page:
- 598-601
- Research Field:
- 医学信号处理与医学仪器
- Publishing date:
Info
- Title:
- Transverse flow velocity measurement of carbon particles based on photoacoustic Doppler standard deviation calculated with autocorrelation method
- Author(s):
- LU Tao; BAI Weiwei
- College of Electrical Engineering, Henan University of Technology, Zhengzhou 450001, China
- Keywords:
- ; Keywords: photoacoustic Doppler; transverse flow velocity measurement; bandwidth broadening; standard deviation; carbon particle suspension
- PACS:
- Q631
- DOI:
- DOI:10.3969/j.issn.1005-202X.2018.05.018
- Abstract:
- Abstract: In order to measure the flow velocity of carbon particle suspension perpendicular to the receiving axis of ultrasound transducer, the standard deviation of photoacoutic Doppler frequency spectrum which was calculated with an autocorrelation method was used to estimate the bandwidth broadening. A 532 nm pulsed laser with the repetition frequency of 20 Hz was used as a pumping source to generate photoacoustic signals which were then detected using a focused ultrasound transducer with a central frequency of 10 MHz. The suspension of carbon particles was driven by a micro-injection syringe pump. The photoacoustic signals in time domain were transformed into complex photoacoustic signals using Hilbert transformation before autocorrelation calculation. The standard deviation of Doppler bandwidth was calculated by averaging the autocorrelation results of several sequential A scans. Compared with the previously reported cross-correlation method based on sequential A scans, the advantage of the proposed method is that the time delay in autocorrelation can be customized. If the time delay was chosen much less than the time interval between the sequential A scans, aliasing can be avoided, moreover, the requirement for high laser repetition frequency up to several kHz in cross-correlation was avoided. The feasibility of the proposed method is preliminarily demonstrated by measuring the standard deviation of the carbon particle suspension with a transversal flow velocity from 5.0 to 8.4 mm/s. The experimental results revealed that the autocorrelation results were approximately distributed linearly within the measuring range.
Last Update: 2018-05-22