A new method is presented forimaging the small blood flow velocities in vessels by a spectral domain optical coherence tomography based on averagingphasedifferences between adjacent and interval A-lines at the same lateral position. The proposed method is theoretically developed and validated by measurements of flowing particles within a glass capillary with known mean velocities. Mean standard deviations of different flow velocities of the particles are determined by the proposed method and compared with those determined by conventional phase-resolved method. In vivo experiments on a mouse ear and the Doppler flow velocity maps are reconstructed by both methods. The experimental results demonstrate that the proposed method can significantly suppress the phase noise caused by phase instabilities, improve the signal-to-noise ratio of phase difference and accuracy of velocity measurement for small blood flow without increasing the time interval between adjacent A-lines.

optical coherence tomography  /  Doppler law  /  imaging of blood flow  /  signal-to-noise ratio