Liquid Crystal Variable Retarders’ Phase Retardation Measurement with Quarter-Wave Plate and the Validation

Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardation – an important technical parameter for LCVRs. In this paper, using polarization condition change of polarized light, a set of measurement systems is built. Through the measurement of the relative value of luminous intensity instead of the absolute value which can be easy affected by ambient light and the illuminant instability, it can comparative accurately acquire electrically controlled phase retardation of LCVRs. With the light source of He-Ne laser with the wave 632.8 nm, at temperature 25 °C, a standard quarter-wave plate has been measured, with the relative error less than 1 %.