Low-coherence self-referencing velocimetry.
Low-coherence self-referencing velocimetry optically measures the relative velocity between a point in a particle-laden fluid and a (potentially moving) reference surface. Low-coherence light scattered off the particles and off the reference surface is coupled into an interferometer with variable optical delay in one arm and an acousto-optical modulator in the second arm. The measurement location is set relative to the reference surface. Its location can be scanned along a line by adjusting the optical delay in the interferometer. The spatial resolution is typically tens of micrometers. Only one low-coherence light beam is required for each component of the velocity vector. Proof-of-principle measurements in Taylor-Couette flow are presented.
Kempe
Andreas
A
Institute of Fluid Dynamics, ETH Zürich, Zürich, Switzerland. kempe@ifd.mavt.ethz.ch
Schlamp
Stefan
S
Rösgen
Thomas
T