Light uniaxial system

In Eqs. (1) through (3), n and are the extraordinary and ordinary refractive indices of the locally uniaxial system, X is the wavelength of light in vacuum and p is the pitch of the twisted structure defined as the distance measured along the helical axis for the local optic axis to twist around a full 360 . It follows from Eqs. (l)-(3) that the major and minor axes of vibration of both elliptical eigenwaves are either parallel or perpendicular to the local optic axis L. The ellipticities of the eigenwaves, e. and e, are defined by... 

Equations (14)-(17) apply to isotropic media. In an orientationally ordered material the extinction coefficient becomes dependent on the angle between the alignment axis and the polarization direction of the incident light, and has the characteristics of a second rank tensor. At a microscopic level, the optical absorption depends on the angle between the molecular transition dipole moment iJ.j for the particular absorption band, and the electric field of the light wave. Restricting attention to uniaxial systems, an effective order parameter (5op) for optical absorption can be defined as ... 

Coordinate system to describe light propagation in a uniaxial system. 

A chiral system is a system that is not superposable on its mirror image. The number of independent measurements of different kinds needed to identify the sample as chiral depends on the knowledge of the system. If it is known, for example, that the system is an isotropic dissymmetric phase, one optical measurement is sufficient, whereas for an anisotropic uniaxial system more than one measurement is demanded. For the latter case the wavenumber dependence of the ellipticity and the rotation of the plane of polarization can be measured. Here the dispersion of the circular birefringence and dichroism can be, but needs not be, different from that of the linear birefringence and dichroism (Figure 3). Another possibility is the measurement of the rotation of the plane of polarization and the ellipticity for different azimuth orientations of the sample about the axis of propagation of the light beam. 

Consider a light wave propagating along the direction of the helix (z direction). For the locally uniaxial system, the electric displacement D and electric field E are related by the following constitutive equation ... 

Zircon belongs to the tetragonal system and is a positive uniaxial. The typical form shows the ill and the 110 planes. The two orientations selected for luminescence polarization study were the (110) plane, parallel to the basal section and the [100] row. In such cases the axis perpendicular to the (110) plane will be called X. The orientation notation is made according to the so-called Porto notation (Porto et al. 1956). The Xi(ZX2)Xi orientation means that the laser light entered parallel to the Xi axis of the crystal and is polarized in the Z direction, while the emission is collected along the Xi axis with X2 polarization. By polarization spectroscopy with a high spectral resolution (less then 0.1 nm) six lines are observed for the Dq- Fi transition of the Eu-II center instead of the maximum three allowed for an unique site (Fig. 5.12). In Z(XX)Z geometry which corresponds to observation of a-polarized luminescence we... 

Figure 24 provides an outline of the structure of the system concerned. By adjustment of the specimen width (1.3 m) to the speed of the conveyor, a uniaxial robot can move the camera and lighting unit in parallel, making possible the examination of the entire surface of the product. The camera and lighting are depicted in Figure 25. 

Fig 6. Schematic diagram of polarization measurements of a. Completely uniaxially oriented molecules, b. Two-dimensional system with partially oriented molecules, and c. Three-dimensional system with randomly oriented molecules. Axis of chromophoric group of the molecule lies along the double-headed arrows. The intensities of the incident exciting light and the fluorescence emission are represented by and //, respectively. The vertical and horizontal components of // are represented by J and /j respectively... 

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