Optical retardation of rub-induced scratches in a polyimide-treated substrate

Optical retardation measurements were performed on rubbed polymide-coated substrates used for liquid-crystal cells. Based on measurements with and without a refractive index matching fluid, the retardation component due to the rub-induced scratches was extracted, and found to dominate the total retardation at higher rubbing strengths. Additionally, atomic force microscope measurements were performed to examine the rub-induced surface topography. The retardation calculated from the topography measurements was found to be in agreement with the optical results. (C) 1998 American Institute of Physics.