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Published April 2014 | Published
Journal Article Open

Calibration-free structured-illumination photoacoustic flowgraphy of transverse flow in scattering media


We propose a calibration-free photoacoustic (PA) method for transverse flow measurements. In this method, a pulsed periodically structured (i.e., grating patterned) optical beam is used to illuminate flowing absorptive particles in an optically scattering medium. The PA signal amplitudes measured over consecutive laser pulses carry an imprint of the illumination structure. The modulation frequency of the imprint is proportional to the component of the flow speed projected onto the normal axis of the striped illumination pattern. This method can tolerate high particle density, and is insensitive to the particle size, thus calibration-free. Bovine blood and microsphere phantoms were used to validate the proposed method. Blood flow in a mouse ear was measured in vivo as well.

Additional Information

© 2014 SPIE. Paper 130871R received Dec. 5, 2013; revised manuscript received Feb. 27, 2014; accepted for publication Mar. 21, 2014; published online Apr. 9, 2014. The authors would like to thank Professor James Ballard for manuscript editing. We also appreciate technical assistance and useful discussions with Arie Krumholz, Yong Zhou Liang S. Gao, and Yan Liu. This research was supported by the National Institutes of Health (Grant Nos. DP1 EB016986 (NIH Director's Pioneer Award), R01 EB016963, R01 EB008085, R01 CA134539, U54 CA136398, R01 CA157277, and R01 CA159959. L.V.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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