HOLOGRAPHIC IMAGING OF SIDE-SCATTERING PARTICLES

An off-axis holographic system in the side-scattering mode has been st udied, and the requirements of fringe resolution and film sensitivity associated with holographic imaging of side-scattering particles analy sed. By assuming the Mie scattering model, the fringe distribution abo ut the y-axis (perpendicular to the plane of incidence of the referenc e light) was found to be asymmetrical, with unevenly distributed spaci ng, that is narrower in one x direction but greater in the side that i s close to the origin. It was demonstrated that commercially available holographic film was sufficient to resolve the fringe frequency over the entire area of the holographic plate, at alpha less than or equal to 60 degrees for z=120 mm, and that images of particles as small as 2 0 mu m could be recorded. Astigmatism was found to occur and be respon sible for the distortions of the particle images. Copyright (C) 1996 E lsevier Science Ltd.