Azzam and Bashara

The theory and practice or ellipsometry has been comprehensively treated by Azzam and Bashara. A more practically oriented treatment can be found in two more recent books, which serve as a better starting point for the intending practitioner. The following brief synopsis can only serve to highlight the main points or the technique. 

Many different designs of ellipsometers have been suggested and a good overview is presented in Azzam and Bashara [3]. Here we discuss common roots of all arrangements and the underlying theory. 

Quantitative treatments of partially polarized light can be found in the texts by Born and Wolf [2], and Azzam and Bashara [5]. In this monograph, the light will be assumed to be perfectly polarized. It should be noted, however, that in many experimental situations depolarization can readily occur and care must be taken to either account for it, or to minimize this possibility. The most common source of depolarization in optical rhe-ometry is multiple scattering by such systems as dense suspensions and liquid crystals. 

The connection between the Stokes and Jones vectors, given by equation (1.59) can be used to relate the sixteen-component Mueller matrix to the four-component Jones matrix. Combining equations (2.1), (2.2), and (1.59), we have, using a notation similar to that developed in Azzam and Bashara [5], 

The Stokes vector representation of light polarization has often been used for ellipsometry measurements. (Another representation is the Jones vector representation, of which details can be found in the book by Azzam and Bashara listed under Further reading). In the Stokes representation, the polarization state of a light beam is given by its four-element Stokes vector, 

A good review article on optical constants and their measurement is that by Bell (1967). Determination of optical constants from reflectance measurements is treated by Wendlandt and Hecht (1966) and from internal reflection spectroscopy by Harrick (1967). Ellipsometric techniques are discussed at length by Azzam and Bashara (1977). 

Another important point is that reflection ellipsometers normally yield ratios of the reflection coefficients, R and Rm. The equations for these coefficients are nonlinear, transcendental, algebraic equations that must be solved simultaneously for the desired unknowns in an experiment. Techniques to solve these equations are presented in the monograph by Azzam and Bashara [5]. 

The reflectivity at stratified planar structures becomes more complicated if thin film structures are present. Still methods are available to make a straightforward calculation of the reflectivity. For thin film structures, a matrix method has been developed that still gives an analytical solution for the calculated reflectance (Azzam and Bashara 1977 Jackson 1998). 

---