Fig. 1. Schematic of blood passing through probe beam

Fig. 2. Schematic of single red blood cell passing through the vessel and probe beam

Fig. 3. Schematic of PA/OCT experimental system

Fig. 4. Blood flow velocity measured by PAM. (a) Image of blood in the vessel; (b) normalized P(t) signal;(c) calculated autocorrelation correlation function and fitted curves of P(t); (d) ratio of flow velocity measured by PAM to original flow velocity at different tilt angles

Fig. 5. Blood flow velocity measured by OCT. (a) Cross section image of vessel with blood; (b) B-scan image obtained by continuous A-line signal acquisition at the same position; (c) blood flow velocity profile in the vessel; (d) ratio of flow velocity measured by OCT to original flow velocity at different tilt angles