Transmission decreases as the applied AC voltage amplitude increases (half‐to zero‐waves retardance). The relationship between transmittance T and retardance (in degrees) for crossed polarizer configuration is given by: T(Θ) = 1/2 [1 ‐cos(Θ)] Tmax, where Tmax is the maximum transmittance when retardance is exactly one‐half wave (or 180°).

Maximum transmission is dependent upon properties of the LC Variable Retarder as well as the polarizers used in your system. Extinction ratio is defined as the maximum transmission (LC cell at half‐wave) divided by the minimum transmission (LC cell at zero waves). Values exceeding 1000:1 can be obtained for a single wavelength by optimizing the applied voltage levels for minimum and maximum transmission. We guarantee a minimum extinction ratio of 500:1 at your specified wavelength.

A Liquid Crystal Variable Attenuator can be configured with high-efficiency calcite or beam-splitting polarizers to maximize light transmittance and increase damage threshold. With a linearly polarized input beam and a calcite polarizer, transmittance values exceed 90% at most wavelengths. Very high extinction ratios, in excess of 5000:1, can be achieved with custom double attenuators. In this design, two Liquid Crystal Variable Retarders are combined with three polarizers.