Abstract
As mentioned in the Introduction, the coherence effects in a propagation of optical waves in highly scattering nonuniform media with characteristic dimensions of nonuniformities of the order of or less than wavelength has attracted a great deal of attention by both experimentalists and theoreticians in recent years. The interest in this problem was stimulated by the fact that in such media there can occur in some areas both the constructive and destructive interference of multiple scattered optical waves. That gives rise to a number of nontrivial wave coherence effects. The observation of these effects opens new possibilities for the solution of the important problem of in situ optical diagnostics of highly scattering systems of nanoparticles and other mesoscopic structures with characteristic dimensions from 1 to 100 nm. Such diagnostics include the evaluation of the particle shapes and the characteristics of their distribution in space, including clustering and void formation, as well as particle movement effects, including Brownian motion and flow-induced stresses in nanosuspences. The diagnostics have important perspectives not only in scientific studies but also in practical applications, including the control of important industrial processes, environment monitoring, and medical diagnostics. In particular, the coherent, nonionizing optical scattering may serve as an effective substitute for X-ray-based techniques in medical imaging. Optical coherent scattering effects can be exploited for the detection and characterization of aerosols present in the atmosphere, including the detection of hazardous bioaerosols. The measurement of particle size and particle distribution by optical coherent scattering can serve for the rapid and accurate characterization of mesoscopic colloidal suspensions, which is important, in particular, in the industrial production of polymer latexes.