Polarization Of Light By Reflection

Which is not possible

At , refracted ray will go tangentially as shown in Fig 2(b). Beyond this angle of incidence i.e. the transmitted ray will not exist. The complete radiation will be reflected back in the same medium, Fig 2(c). This phenomena is termed as total internal reflection. The minimum angle at which this phenomena occurs is termed as the critical angle . 

             ----------------------(2)

                           ----------------- (3)

where and are the phase shift on reflection (for ) for s and p components respectively.

Fig 3 shows the variation of and as a function angle of incidence .

A specific polarized light falling beyond a critical angle, will under go a change in polarization because of relative changes in the phases after reflection for s and p components. For example, a linearly polarized light may become an elliptically polarized light depending upon the phase difference and amplitude of s and p components. As an example, let us consider a plane polarized light falling on glass .( n=1.51) –air interface at an angle of 55 (> )on glass as shown in figure 4.  

The phase changes on reflection are 58.6 and 103 for s and p polarized light respectively. Therefore the phase difference  . Therefore the reflected light will be elliptically polarized. Thus total internal reflection phenomena can be used to get the desired elliptically (or circularly) polarized light.