Analysis of the polarization states of light through the experimental determination of the Stokes Parameters


Nowadays polarized light sources have various applications in optoelectronic devices, displays, stress tests on mechanical parts and even in studies of mineralogy. One of the main requirements is to determine the state of polarization (linear, circular, elliptical, or a superposition of them) of the light beam. In this work, we apply the emission ellipsometry technique to investigate the polarization states of different light sources. This technique is based on the theory of Stokes and the types of polarization are correlated to the Stokes parameters. The measurements were performed on beams of light from a polarized LASER, a polarized LASER passing through a quarter wave lag at ± 45 ° (circular polarization), a depolarized LED and the same LED with light reflected onto glass plate at various angles including the Brewster angle. The experimental setup is composed by an achromatic quarter wave plate, a linear polarizer and a photodetector. The results have presented a discrepancy of about 1% compared to the already known polarization of the light sources. Thus we have verified that the emission ellipsometry technique can be applied to determine the polarization state of light produced by sources in general.