Poincaré sphere representation for the anisotropy of phase singularities and its applications to optical vortex metrology for fluid mechanical analysis

Abstract

A new technique for fluid mechanics measurement is proposed that makes use of the elliptic anisotropy of phase singularities in the complex signal representation of a speckle-like pattern. Based on the formal analogy between the polarization field of a vector wave and the gradient field of the complex signal, the Poincaré sphere representation has been used to characterize the phase singularities that serve as unique fingerprints attached to the seeding particles moving with the flow. Experimental results for flow velocity and acceleration measurement are presented that demonstrate the validity of the proposed optical vortex metrology for fluid mechanics measurement.