Hologram coherence effects

Holograms formed from opaque particles in a clear aperture illuminated with quasi-monochromatic, partially coherent light are considered. The method used to formulate the general boundary-value problem for the pair of wave equations propagating the mutual-coherence function is described. The effect of a reduction in spatial coherence on the resolution limit of a Fraunhofer (far-field) hologram is discussed. Bandwidth considerations of the same hologram define a usable far-field region from which resolvable reconstructions can be expected. The effects of spatial coherence upon Fresnel (near-field) holograms are shown, and experimental results that confirm these calculations are presented.