Patterned alignment of liquid crystals has been studied actively in recent years to control the behavior of light by the Pancharatnam-Berry phase. While the photoalignment technique easily allows directed alignment by linearly polarized light irradiation, single-exposure methods to achieve patterned alignment are limited. In this article, we propose the utilization of a Fabry-Perot resonator containing a patterned, uniaxially anisotropic medium as a wavelength-selective, polarization filter that duplicates the pattern in the resonator. We experimentally demonstrate single-exposure photoalignment of pattern period 3.5 µm and numerically show that pattern periods as small as 2 µm are feasible using an inexpensive LED light source. The proposed structure thus has application potential as photoalignment exposure masks.