Polarization interferometer technique has been developed for calibration of phase retardation elements such as quarter/half wave plate with known tolerance in each one. In addition, this technique is used to measure unknown retardation elements to identify its phase retardation. A polarizing beam splitter is placed after Sagnac interferometer to split the produced fringes into p and s polarization interferograms to be analyzed. The phase retardation measurements depend on two states, the reference state which includes recording the reference p and s interferogram images without placing the sample then measuring state at which the p and s interferogram images are recorded after placing the sample inside Sagnac interferometer. Six images are recorded for each interferogram under a controlled environment to calculate the repeatability of measurements and for uncertainty estimation. The detected images are mathematically processed to determine the phase retardation of the polarimetric components. The results are found to be in a good consequent with the data measured by Senarmont compensator method.