Spectroscopic Ellipsometry is a powerful technique for the optical characterization of thin films and bulk materials, such as dielectrics, semiconductors, polymers, and metals. This technique is based on the change in the polarization state of light reflected from the sample surface. The information that can be obtained concerns the refractive index, extinction coefficient, dielectric function, sample thickness, and surface structure of the material. Ellipsometric measurements can be performed as a function of wavelength or angle of incidence; in the latter case, the technique is referred to as Variable Angle Spectroscopic Ellipsometry (VASE).
The results are highly accurate, as ellipsometric measurements concerns the variation of the polarization state, which is independent of beam intensity and any potential fluctuations. Additionally, the ability to vary the angle of incidence and the wavelength of the incident light in an automated manner further enhances the precision of the technique.
Ellipsometry is a non-destructive method that does not require a reference sample and does not need special sample preparation, making it ideal for in-situ applications. However, it requires accurate analysis and processing of the experimental data, which is typically performed using dedicated software.
This technique is particularly useful for characterizing materials such as organic and inorganic films, nanostructured surfaces, complex hybrid films, plasmonic and magneto-optical samples, and photovoltaic materials.

Vase Ellipsometer- J.A. Woollam Inc. Corp

Woollam Vase  is an accurate and versatile variable angle of incidence ellipsometer used for used for characterizing solid samples of various types and materials (semiconductors, dielectrics, polymers, metals), including bulk samples, thin films, and multilayers.
Technical specifications:
● autoretarder  and spot focusing optics (~200 microns) for determining the optical functions of solid samples;
● spectral range: 193 nm – 1700 nm (UV-Vis-NIR);
● analysis software: WVASE32 (Woollam Inc.).
Available configurations:
● transmission and reflection ellipsometry;
● single-beam specular reflectivity measurements (angle of incidence: 15°/75°).
Applications:
● determination of optical functions and surface characteristics (e.g. roughness) of isotropic and anisotropic bulk samples;
● study of coatings (single or multilayer) on isotropic and anisotropic bulk samples (determining of optical functions, thickness and sample modelling).