It was Ètienne Louis Malus, at the end of 1809, who demonstrated experimentally that light transmitted by a plate of glass, with appropriate incidence, is partially polarized and the light transmitted by a stack of plates, with the same incidence, is totally polarized.
Today we know not only that with Brewster incidence the beam reflected by a plate of glass is totally polarized linearly and vibrates perpendicularly to the incidence plane, but also that its intensity is approximately 7.3% of the incident.
Therefore, in the beam transmitted by the first plate in the stack, a part, having the same intensity as the reflected part, is polarized rectilinearly and vibrates on the incidence plane, while the remaining part is not polarized and the total intensity transmitted, if absorption is neglected, is 92.7% of the incident intensity.
In a generic plate in the stack, 7.3% of the non polarized component of the incident beam is reflected and polarized rectilinearly, with the plane of vibration perpendicular to the plane of incidence and, in the beam transmitted, a part of the non-polarized component, having the same intensity as that which has been subtracted from it by reflection, adds to the rectilinearly polarized component, which vibrates on the plane of incidence.
...continues