An improved holographic method to obtain the three patterns, that is, Nisida and Saito's pattern, Fourney and Mate's pattern and dark-field isochromatics in photoelasticity is studied. The present method is to record two components of object polarization separately on a holographic plate and to reconstruct them by using orthogonally polarized reference beams through an alternating arrangement of strip polarizers whose adjacent transmission axes are perpendicular to each other. In this experimental method the three patterns are more easily obtained from a single double-exposure hologram than in the method of Lohmann used to reconstruct object polarization.