Optical phase measurement emphasized

In undergraduate optics laboratory, one thing that is not easily achieved is quantitative measurement of optical phase. The reason is that optical phase measurement usually requires expensive interferometers. We demonstrate measurement of relative optical phase shift upon total internal reflection. Total internal reflection, though known by every student of optics, is remembered by 100% reflection at an interface when angle of incidence is greater than the critical angle, that is, it seems all the same beyond the critical angle. This is not entirely true if one considers the optical phase, which keeps changing upon total internal reflection as the angle of incidence is varied. Furthermore, for linear polarization states perpendicular to or in the plane of incidence (sand p- polarization), optical phase changes differently upon total internal reflection. Therefore, a linearly polarized beam composed of both s- and p- polarization undergoing total internal reflection becomes elliptically polarized. We show how to determine relative optical phase change between s- and p- polarization states through analysis of the outgoing elliptically polarized beam. Such optical phase change can also be theoretically calculated using Fresnel equations.