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Abstract

A method of fabricating large area birefringent grating films requires directing a UV beam through a large-scale LC polymer film alignment template on which a predetermined periodic alignment pattern has been imprinted and onto a photo-alignment layer such that the pattern is transferred thereon. The alignment template is fabricated by directing a collimated linearly polarized UV beam through a birefringent prism to produce two UV beams, which are directed onto a photo-alignment layer through a uniform quarter-wave plate to create a UV hologram which imprints the desired pattern onto the photo-alignment layer. These steps are repeated on different portions of the photo-alignment layer to create a large-scale photo-alignment layer. The photo-alignment layer, with a desired alignment pattern transferred with UV exposure through an alignment template, is then coated with a polymerizable LC material such that the desired pattern is followed by the liquid crystal molecules in the coating, which is then exposed with a UV beam so as to photo-polymerize the polymerizable LC material, and the coating is continued till the total coating thickness reaches either quarter-wave or half-wave retardation values at the wavelength of the UV source passing through the alignment template. Alternatively, a new alignment template can also be fabricated using a pre-existing alignment template with a half-wave retardation at the exposing UV wavelengths, and the alignment periodicity of the new alignment template is about half as the periodicity in the pre-existing alignment template.

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First Claim