High-velocity-flow imaging with real-time Doppler optical coherence tomography.

We present a real-time time-domain Doppler optical coherence tomography (OCT) system based on the zero-crossing method for velocity measurements of fluid flows with attainable velocities up to 10 m/s. In the current implementation, one-dimensional and two-dimensional velocity profiles of fluid flows ranging from 1 cm/s to more than 3 m/s were obtained for both laminar and turbulent flows. The line rate was approximately 500 Hz, and the images were treated in real time.

A zero-crossing detection method applied to Doppler OCT.

We present a numerical method based on the detection of the zero-crossing points in an OCT signal for the measurement of the Doppler frequency in a laminar flow. This method is compared to other processing approaches currently used in Doppler OCT. The results show that in the case of laminar flow the zero-crossing method gives the most precise results, especially in the higher velocity regime.

An assessment of the Wigner distribution method in Doppler OCT.

Analyzing the experimental data of the velocity distribution in a fluid flow using Doppler Optical Coherence Tomography (OCT), we compared the Wigner distribution method to the short-time Fourier transform method, the Hilbert-based phase-resolved method and the autocorrelation method. We conclude that the pseudo Wigner-distribution signal processing method is overall more precise than other often-used methods in Doppler OCT for the analysis of cross-sectional velocity distributions.