High-accuracy simultaneous measurement of particle size and location using interferometric out-of-focus imaging

A method based on unidirectional gradient-matched algorithm and Fourier transform technique is proposed to simultaneously extract the location and the number of fringes/fringe spacing of a particle interferogram. The position coordinate (x,y) of a particle can be determined with high accuracy because of the elimination of the fringe within the particle fringe pattern. Furthermore, the method can be employed to achieve sub-pixel frequency extraction when combined with an improved Rife algorithm. The performance of the method has been verified by numerical simulations and experimental measurements. The results suggest that the method presented here is highly beneficial to applications such as spray, in accurately measuring both the particle size and its location.