The alignment of liquid crystals (LCs) on a two-easy-axis substrate is investigated. The two-easy-axis substrate distorts and frustrates the orientation of the LCs next to it, and hence influences the effective birefringence of the LC cell. Experimental findings reveal that the rubbing strengths in the different rubbing directions and the cell thickness substantially influence the effective birefringence of the LC cell. The surface anchoring energetic competition between the different rubbing directions contributes to the observed results.
