The applications of liquid crystal variable retarders in the production of spin‐polarized electrons and in the determination of the polarization of optical radiation from atoms excited by polarized electrons are discussed. The advantages of using liquid crystal variable retarders in the measurement of Stokes parameters are insensitivity to the incident photon direction, large transmission diameter, variable retardation over large wavelength range without mechanical movement, andinsitucalibration. ©1996 American Institute of Physics.