Linear polarizers are present in all kind of optical systems. These devices behave as vector projectors in the polarization direction assuming quasi-transverse beams in the paraxial domain. Nevertheless, the performance of polarizers used in combination with focused beams requires a more in-depth analysis. Understanding this behavior is essential in microscopy applications because of the non-negligible longitudinal irradiance in the focal plane. In this talk, we discuss the effect of polarizers on the focused electric field. Experimental results show a good agreement with theoretical predictions based on considering linear polarizers as anisotropic plates.