Photoacoustic Doppler Effect from Flowing Small Light-Absorbing Particles
From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.
Additional Information© 2007 The American Physical Society. Received 22 July 2007; published 29 October 2007. We would like to thank Geng Ku for experimental assistance and thank Erich Stein and Roger Zemp for useful discussion. This project is supported by National Institutes of Health Grants Nos. R01 EB000712 and R01 NS046214.
Published - PhysRevLett.99.184501.pdf