Abstract

We present a simple method for characterizing polarization retarders based on the fact that a retarder of a given thickness will have a phase retardation Δϕ that varies with wavelength. In fact, Δϕ is directly proportional to the thickness and birefringence of the material and inversely proportional to the wavelength. If the retarder is placed between two polarizing filters (either parallel or crossed), the transmitted intensity will be colored as a result of this variation. A spectral transmission curve of this sandwich can be obtained from a spectrophotometer, and the resulting data are very easy to interpret. The curve will be sinusoidally varying function of the optical frequency, and the frequency of this variation depends on the retardation. The wavelengths where the transmission is a maximum, a minimum, or one-half, respectively, correspond to the wavelengths at which the retardation has a value of a full wave, a halfwave, or a quarterwave.

© 1989 Optical Society of America