Tunable achromatic liquid crystal waveplates.

The wavelength dependence of phase retarders is considered as a challenge in different applications such as polarimetric systems. A novel achromatic waveplate based on two nematic liquid crystal retarders is designed and demonstrated tunable over a wide spectral range using different voltages applied to the two retarders. The achromatic behavior is achieved based on the fact that the dispersion of the retardation of liquid crystals is voltage dependent. Achromatic quarter and half-waveplates are demonstrated using the same device as well as the tunability of the achromatic operation range.