Optical Anisotropy

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optical anisotropy

[′äp·tə·kəl ‚an·ə′sä·trə·pē]
The behavior of a medium, or of a single molecule, whose effect on electromagnetic radiation depends on the direction of propagation of the radiation.

Optical Anisotropy


the difference in the optical properties of a medium as a function of the direction of propagation of optical radiation (light) in the medium and of the state of polarization of the radiation. Optical anisotropy, especially in crystal optics, is frequently understood to mean only the phenomenon of double refraction. However, it is more correct to also classify rotation of the plane of polarization, which occurs in optically active substances, as optical anisotropy.

The natural optical anisotropy of most crystals is due to the character of their structure (the difference in different directions of the field of forces binding the particles in the crystal lattice) and, in the case of some optically active crystals, also to the peculiarities of the excited state of the electrons and “ion cores” in the crystals. The natural optical activity (rotation of the plane of polarization) of substances that manifest it in any state of aggregation (crystalline, amorphous, liquid, or gaseous) is related to the asymmetric structure of the individual molecules of the substances and to the differences—resulting from this asymmetry—in the interactions of the molecules with variously polarized radiation.

Induced (artificial) optical activity arises in media that are by nature optically isotropic, upon exposure to external fields that single out certain directions in the media. These may be an electric field (the Kerr effect), a magnetic field (the Cotton-Mouton and Faraday effects), or a field of elastic forces (the phenomenon of photoelasticity). Double refraction in a fluid flow (the Maxwell effect) and in media through which light fluxes of superhigh intensity (usually laser radiation) are transmitted is also classified as artificial optical anisotropy.


References in periodicals archive ?
Interesting and unexpected optical anisotropy were observed for these films deposited at non-normal angles of incidence.
v] light scattering intensity consists of an optical anisotropy ingredient and a density fluctuation ingredient contribution.
The interference pattern of the writing beams leads to a spatially modulated optical anisotropy of the phase type [DELTA]n([chi]) (refractive index modulation) and/or the amplitude type [DELTA][alpha]([chi]) (absorption modulation) and also, in the case of azobenezene functionalized polymers, to the surface modulation [DELTA]d([chi]).
The consecutive events have different effects on the optical anisotropy of the ensemble of polymer chains.
The evolution of optical anisotropy under deformation is also simulated by coupling the mechanical anisotropy due to molecular alignment to the optical properties.

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