A ZnSe phase retarder is developed, which can conrest linearly polarized CO2 laser light into circularly polarized light by using pile-of-plates as polarization analyzer, This element has the features of non-deliquation, laser damage threshold being greater than 40MW/cm2, long lifetime, and high conversion efficiency in the wavelength range between 0.60-14μm.It has been used in high-power laser systems.