Isolating single-particle holograms in a multiparticle digital hologram

A method is developed to isolate the interference-fringe pattern associated with an individual particle from a single digital in-line hologram containing overlapping patterns from multiple particles. The method is illustrated with a measured hologram of road-dust aerosol particles nominally 20-50 µm in size. It is further tested for 2.5-3.0 µm particles by simulation with the discrete dipole approximation. By incrementally degrading a hologram’s resolution, the method is shown to perform well for particles that are poorly resolved, at least for the first few central fringes in the pattern. The method may be useful in cases where particle characterization is done directly from a hologram, i.e., instead of from the reconstructed images.