Consistency of light intensity and frequency translated into phase retardation in determining a liquid crystal variable retarder

The liquid crystal variable retarder (LCVR) serves as optical polarization modulator for its large phase retardation under low driving voltage. However, the generated retardance exhibits nonlinear response with voltage and inflection points at integer multiple wavelengths in applications. Aiming at precisely regulating the retarder, this paper implements LCVR determination adopting light intensity and frequency as measurement quantities. Both the cosine variation of intensity in a dual-beam crossed polarized light path and the splitting frequency difference of two laser orthogonally polarized modes are recorded, from which phase retardation is translated for comparison. Results reveal good consistency of 10⁻³ ∼ 10⁻²λ between frequency and intensity measurements for different samples.