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Liquid crystal alignment layers are prepared using a noncontact method based on laser ablation. Nonpolarized light from a KrF excimer laser at 248 nm is exposed through a phase mask to etch gratings of period 1.1 μm onto polyimide alignment layers. Twisted nematic cells were prepared using one rubbed and one grating aligned surface, and azimuthal anchoring energies were found from measurements of the twist angles as a function of grating depth. The measured anchoring energies agree with those predicted from the minimization of elastic strain energy when the liquid crystal directors at the surface are aligned parallel to the groove of the grating. This suggests that topographical rather than epitaxial alignment is achieved.

Periodic surface structures have been observed on organic polymers when photoablated using low coherence excimer lasers. Both unpolarized and linearly polarized radiation at 248 and 308 nm produce well ordered, micron-scale structures over dimensions greatly exceeding the coherence area of the laser at the surface. Surface scattered wave effects appear to explain these structures.

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