Study of transparent particles in the volume of optical medium using digital holography and singular-optics approach

摘要

The study of particles that are transparent to the probing radiation but introduce a phase delay appears to be relevant especially in the fields of biology and medicine. In this paper, we propose an approach to the study of the distribution of transparent particles suspended in a volume of optical medium, which combines the method of digital holography and the concept of singular optics. For the numerical study of the particles, we use a method, based on the obtainment and analysis of zerograms that correspond to the spatial distributions of amplitude zeros of the complex amplitude of the field. We explore the features of the application of analysis of the amplitude zero distributions in solving the problem of studying transparent particles suspended in a volume of the optical medium. We investigate the effect of various particle parameters on the recorded hologram and the structure and distribution of the amplitude zeros of the electromagnetic field. We demonstrate the use of histograms of distributions of local densities of amplitude zeros for the characterization of a higher number of transparent particles in volume. Numerical experiments on the use of analysis of the amplitude zeros of the field have shown that there are a number of particular qualities in the distribution of the zeros of amplitude, which can be subsequently used to develop more accurate and efficient method of characterization of transparent particles.