Polarization by Refraction

POLARIZATION OF REFRACTION

         When unpolarized light is incident on the surface of separation of two media,then the refracted light is partially polarized. Its vibration is more in the plane of incidence and less in the plane perpendicular to the plane of incidence.

            On changing the angle of incidence also, there is no change on the nature of the refracted beam I.e., for all angles of incidence (even for polarizing angle),the refracted beam is partially polarized. It must be remembered that when unpolarized light falls at the polarizing angle,the reflected light is completely plane-polarized.

So,as we know that an ordinary beam of light cam be supposed to be made up of two kinds of vibrations,one set vibrating in a perpendicular plane.when the beam of light falls on a thin glass plate at the polarizing angle, the light reflected from both the surfaces of the plate is completely plane polarized in the plane of incidence, I.e.,with vibrations perpendicular to the plane of incidence.but as only a small portion of incident beam is reflected,the intensity of reflected,the intensity of reflected beam is quite weak.Hence,in order to increase the intensity of plane polarized reflected beam we should increase the number of plates to increase thr number of reflections.

           By increasing the number of plates,more and more of the vibrations perpendicular to the plane of incidence are reflected and the rest are transmitted,but the vibrations parallel to the plane of incidence are entirely refracted.