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The problem of nondestructive testing of microstructure parameters, both aerosols and water suspension, is actual for biology, medicine, and environmental control. Among the methods of optical investigations and diagnostics of light scattering media the holographic method plays a special role. A hologram of scattering volume allows us to reproduce the optical wave field to obtain information on the parameters of microparticles: size, shape, and spatial position. Usually this is done by analysis of the particle images reconstructed from the hologram. On the basis of calculated and experimental results, characteristics of holographic methods are analyzed in this paper. These estimations demonstrate a possibility to use the above methods for investigation of media in biomedical science and clinical practice. A lot of micro-organisms and other living particles are transparent or semitransparent ones. In this case the reconstructed image of the particle will show a spot formed due to light focusing by the particle in addition to its cross section. This circumstance allowed us to propose a method of determining of refractive index of transparent and semitransparent microparticles, that, in turn, can provide identification of the particles type. The development of this method is presented. To make measurement of the size-distribution of particles one can do this simultaneously with the reconstruction of scattering optical field from the hologram. In this case a small angle optical meter (for example, focusing lens) can be placed just behind the illuminated hologram. The reconstructed field is composed of the initial one and its conjugate. Each of these components as well as interference between them can bear an additional information on the medium. The possibility of extraction of this information is also discussed.
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