The details of a technique to measure solid surface velocity and detect particle movement are presented. This technique is based on the measurements of the frequency change of scattered light of particles crossing the fringes of a nearly Bessel beam formed by an axicon. Experimental results are presented and confirm the theoretical analysis and numerical simulations. Measurements of the movement of wires through the fringes were also performed.
"Measuring solid surface velocity and detection of particle movement by laser Bessel beams," Optical Engineering 55(9), 091411 (18 July 2016). https://doi.org/10.1117/1.OE.55.9.091411