Particle tracking from in-line holograms by using single wavelet coefficient

We propose a new digital method for tracking position of particles from in-line holograms by using single wavelet coefficient. By computing a wavelet transform of the 1-D intensity profile of a hologram, resultant wavelet coefficients provide space-varying frequency information of an interference pattern. Our study finds that a dilation which is given by the maximum value of the real wavelet coefficient appeared at the center position of the interference pattern is determined by a recording distance and a wavelength of a coherent illuminating light. Therefore, this dilation can be used for extracting the recording distance of particles from the holograms. A feasibility of this method is experimentally verified by analyzing holograms of a line object.