I3

Light reflecting off a mirror actually penetrates a short distance into the mirror surface material. In metals, this distance is very short (much less than a wavelength) and so can be neglected. But metals tend to also ab-sorb ~10% of the light, which is undesirable. Today's modern multi-layer thin-film coatings, on the other hand, don't absorb any light, but light tends to penetrate further into them, usually further for the p-polarization than for the s-polarization. Suppose that light at a wave-length of 1mm with 45o linear polarization reflects off a thin-film-coated

mirror (let n = 2 for both polarizations in the dielectric coating). If the p-polarization penetrates 2mm into the thin-film material, and the s-polarization only penetrates 1.875 mm, what will be the polarization of the reflected light? What if the light has a wavelength of 500nm (use the same refractive indices and penetration depths)? Write down Jones matrices for the mirror for the two cases.