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.