Extractions of particle positions from inline holograms using a single coefficient of Wigner–Ville distribution (WVD) are experimentally verified. WVD analysis of holograms gives local variation of fringe frequency. Regardless of an axial position of particles, one of the WVD coefficients has the unique characteristics of having the lowest amplitude and being located on a line with a slope inversely proportional to the particle position. Experimental results obtained using two image sensors with different resolutions verify the feasibility of the present method.
A new method for extracting information from particle holograms by using a single coefficient of Wigner-Ville distribution (WVD) is proposed to obviate drawbacks of conventional numerical reconstructions. Our previous study found that analysis of the holograms by using the WVD gives output coefficients which are mainly confined along a diagonal direction intercepted at the origin of the WVD plane. The slope of this diagonal direction is inversely proportional to the particle position. One of these coefficients always has minimum amplitude, regardless of the particle position. By detecting position of the coefficient with minimum amplitude in the WVD plane, the particle position can be accurately measured. The proposed method is verified through computer simulations.
Properties of Wigner-Ville distribution’s coefficients obtained from in-line holograms are studied. It is found that the WVD coefficients corresponding to local fringe frequencies are mainly confined along a diagonal stripe intercepted at the origin of the WVD plane. The slope of this diagonal stripe is inversely proportional to the particle position. One of the coefficients always has minimum amplitude, regardless of the particle position.