Order parameter of liquid crystal on polyimide with polarized ultraviolet-light exposure

We report a brief method of measuring the order parameter of liquid crystal (LC) depending on the cell gap. The method utilizes polarized ultraviolet- light (UV) absorption of host-guest LC in a wedge cell. We applied this met hod to evaluate the order parameters of LC on polarized-UV-exposed polyimid e (PI) films compared with those on rubbed PI films. The results suggest th at the order parameter of LC gradually decreases with decreasing cell gap. Furthermore, the relative order parameters of LC on UV-exposed PI films sho w a stronger dependence on the LC layer thickness than those on rubbed PI f ilms.