Elliptical polarized light

As discussed above, the reflection of linearly polarized light from a surface generally produces elliptically polarized light, because the parallel and perpendicular components are reflected with different efficiencies and different phase shifts. These changes in intensity and phase angle can be analyzed to characterize the reflecting system. This approach is called ellipsometry. 

In ellipsometric spectroscopy, an elliptically polarized light is allowed to reflect on the interface and the change in ellipticity and phase angle are determined from complex reflectivity. 

Smith, D. Y., 1976. Comments on the dispersion relations for the complex refractive index of circularly and elliptically polarized light, J. Opt. Soc. Am., 66, 454-460. 

Adding LCP and RCP components of different amplitudes, yields elliptically polarized light. The major axis of the ellipsoid is the sum of amplitudes AR and AL, and the minor axis is their difference, as shown in Fig. 5. The ellipticity 0 is defined as the arctangent of the ratio of the minor axis to the major axis ... 

Fig. 5. Elliptically polarized light emerging toward the observer through a circularly dichroic sample. The sign is defined by the chemical convention that

B. Koeman and H. Janeschitz-Kriegl, Analysis of slightly elliptically polarized light, J. Phys. E Sci. Instrum., 12, 625 (1979). 

Auzinsh, M.P. and Ferber, R.S. (1990). Orientation of atoms and molecules under excitation by elliptically polarized light, Opt. Spectrosc. (USSR), 68, 149-152. 

The paths described by the tip of E for the various values of <5 are summarized in Fig. 8.3. It is apparent that plane-polarized light is a special case of elliptically polarized light, as indeed is circularly polarized light. The sense of the... 

Fig. 8.3 How elliptically polarized light depends on the phase difference <5 between plane-polarized components.

Ellipsometry measures the orientation of polarized light undergoing oblique reflection from a sample surface. Linearly polarized light, when reflected from a surface, will become elliptically polarized, because of presence of the thin layer of the boundary surface between two media. Dependence between optical constants of a layer and parameters of elliptically polarized light can be found on basis of the Fresnel formulas described above. 

Figure 9.2. Conversion of linearly polarized light to elliptically polarized light passed through a birefringent crystal.

---