Fig. 3.
(a) PA imaging of blood vessels in the mouse ear acquired with 532-nm wavelength. (b) Flow speed image measured by dual-pulse flowmetry. (c) and (d) flow speed profiles along with the dashed white line in (a) measured by the photoacoustic Doppler method and the dual-pulse method, respectively. (e) Linear relationship between the PA Doppler results and the dual-pulse results. A linear fitting gives the R2 of 0.9384. VPAD is the flow speed measured by PA Doppler method. V545/532 is the flow speed measured by the dual-pulse method. (f) Spectrum of the dual-pulse flow speed in the artery as labeled with a black star in figure a. A heartbeat rate of 4.6 Hz is observed. (g) Time-domain blood flow speed in the artery which is averaged by 100 times. The red line is a lowpass filtered result cut off at 10 Hz.