Abstract: In Optical Doppler tomography (ODT), or color Doppler optical coherence tomography, the signal component of primary interest arises from moving scatterers, such as flowing blood cells in blood vessels. Clutter rejection filters are provided and used to remove undesired components from the ODT signal, such as clutter induced by stationary scatterers (e.g., the relatively stationary tissue of a blood vessel wall). Empirical results indicate that such clutter rejection filters can be employed to achieve ODT images from which blood vessel diameter can more accurately be estimated than images obtained using conventional ODT techniques. Further, Doppler images obtained using the clutter rejection filter technique disclosed herein exhibit fewer background artifacts induced by the relative motion of stationary scatterers with respect to the scanning probe.

Abstract: The Doppler bandwidth extracted from the standard deviation of the frequency shift in phase-resolved optical Doppler tomography (ODT) is used to image the velocity component transverse to the probing beam. The effective numerical aperture (NA) of the optical objective determines the slope of the dependence of the standard deviation on velocity. In the case where the angle between the probing beam and flow direction is within ±15 degrees to the perpendicular, the Doppler frequency shift is very sensitive to angle position while the Doppler bandwidth is insensitive to flow direction. Linear dependence of the flow velocity on the Doppler bandwidth allows accurate measurement of flow velocity without precise determination of flow direction. In addition, it also extends the dynamic range of the average frequency shift mapping method used in the phase-resolved ODT.

Abstract: The Doppler bandwidth extracted from the standard deviation of the frequency shift in phase-resolved optical Doppler tomography (ODT) is used to image the velocity component transverse to the probing beam. The effective numerical aperture (NA) of the optical objective determines the slope of the dependence of the standard deviation on velocity. In the case where the angle between the probing beam and flow direction is within ±15 degrees to the perpendicular, the Doppler frequency shift is very sensitive to angle position while the Doppler bandwidth is insensitive to flow direction. Linear dependence of the flow velocity on the Doppler bandwidth allows accurate measurement of flow velocity without precise determination of flow direction. In addition, it also extends the dynamic range of the average frequency shift mapping method used in the phase-resolved ODT.