This equipment uses goniometer and a pinhole photodetector to determine the Brewster’s angle and to study polarization of reflected light. Intensities of the reflected light polarized in the plane of incidence and perpendicular to the plane are obtained as a function of the angle of incidence. The results should be consistent with Fresnel's laws of reflection.

A linearly polarized light beam does not get reflected at a planar boundary between two optical materials if it is polarized in the plane of incidence and the incidence angle is equal to the Brewster's angle.