Depolarization of white light by a birefringent crystal

The depolarization of white light upon passage through a birefringent crystal, due to the unequal phase retardation of different wavelengths is considered. Assuming the incident light to be completely linearly polarized with the spectral power distribution of a blackbody radiator, the degree of polarization remaining after passage through various thicknesses of birefringent material is calculated. The problem is simplified by assuming that there is no dispersion in the crystal. Results show that under the assumptions made, the light from a 3000 K source is less than 1% polarized after passage through 2.66 × 10−1 mm of quartz and 1.41 × 10−2 mm of calcite.