A method to determine liquid crystal (LC) anchoring properties, that exploits the changes induced in a rubbed polyimide (PI) film upon exposure to linearly polarized ultra-violet light, has been devised. The width of the Gaussian PI chain distribution is determined from the measured rotation of the PI film's index ellipsoid, the long axis of which is also the LC easy axis, as a function of exposure time. A quasi-microscopic surface free energy is used to model the anchoring properties. This approach provides a simple LC material independent method for determining the LC anchoring properties.