Flow velocity estimation using joint Spectral and Time domain Optical Coherence Tomography.

We propose a modified method of acquisition and analysis of Spectral Optical Coherence Tomography (SOCT) data to provide information about flow velocities. The idea behind this method is to acquire a set of SOCT spectral fringes dependent on time followed by a numerical analysis using two independent Fourier transformations performed in time and optical frequency domains. Therefore, we propose calling this method as joint Spectral and Time domain Optical Coherence Tomography (joint STdOCT). The flow velocities obtained by joint STdOCT are compared with the ones obtained by known, phase-resolved SOCT. We observe that STdOCT estimation is more robust for measurements with low signal to noise ratio (SNR) as well as in conditions of close-to-limit velocity measurements. We also demonstrate that velocity measurement performed with STdOCT method is more sensitive than the one obtained by the phase-resolved SOCT. The method is applied to biomedical imaging, in particular to in vivo measurements of retinal blood circulation. The applicability of STdOCT different measurement modes for in vivo examinations, including 1, 5 and 40 mus of CCD exposure time, is discussed.