An investigation of the potential of polarized light scattering for the characterization of irregular particles

Abstract

An investigation has been carried out into the possibility of using polarization methods to characterize clouds of irregular particles. Measurements were made at scattering angles between approximately 115 • and 135 • , where it was expected that polarization effects would have maximum variation with shape. It was found that the angular variation of any polarization property was similar for most particles. Further, as a consequence of reciprocity, the useful parameters were limited to the scattered intensities for two incident polarization states and one cross-polarized intensity. The only useful correlation appeared to be between cross-polarization and the 'roundness' of the particles, although different correlations are observed between particles which are inherently isotropic and those which are anisotropic. The main conclusion of the study is that polarization can be used to measure the average roundness of particles in a cloud and has the potential to discriminate between crystals of different structure.

Simultaneous measurement of angular and spectral properties of light scattering for characterization of tissue microarchitecture and its alteration in early precancer

“…For uniform sphere particles, equals 1 in the backward direction [27]. It was also shown that the ratio of to highly correlates with the average roundness of particles [39].…”

On the statistics of the entropy-depolarization relation in random light scattering

“…Within these considerations, the particles can have any size, shape, orientation and distribution; but we will assume further that the medium is isotropic, an isotropy that may be only in the statistical sense. This class of scattering media have been studied extensively and several applications have been discussed [13,14,15,16,17,18]. Fig.…”

“…A value greater than unity for these parameters is termed "anomalous depolarization" [21]. As a matter of fact, many experimental and theoretical results up to date show that for disordered media the cross-polarization ratios are never simultaneously greater than unity [14,15,16,17]. We proceed our simulation by randomly choosing the free parameters m 01 , m 11 , m 22 , m 23 and m 33 in the range −1 ≤ m i j ≤ 1.…”

Optical properties of irregularly shaped particles

“…Remind that q = 1 for identical spheres. We see, therefore, that backscattering region is potentially informative for the different particulate media discrimination (Card and Jones 1999).…”

“…So there will be no light coming from the system of spherical particles, placed between crossed polarizers. This is not the case for irregularly shaped particles (Card and Jones 1999). Note, that both q and r do not depend on the size of particles in the framework of the geometrical optics approximation (Kokhanovsky and Jones 2002).…”