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Crystals 2017, 7(12), 383; https://doi.org/10.3390/cryst7120383

Far-field and Fresnel Liquid Crystal Geometric Phase Holograms via Direct-Write Photo-Alignment

Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC 27695, USA
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Academic Editors: Liang-Chy Chien and Charles Rosenblatt
Received: 1 December 2017 / Revised: 15 December 2017 / Accepted: 18 December 2017 / Published: 20 December 2017
(This article belongs to the Section Liquid Crystals)
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Abstract

We study computer-generated geometric-phase holograms (GPHs) realized by photo-aligned liquid crystals, in both simulation and experiment. We demonstrate both far-field and Fresnel holograms capable of producing far-field and near-field images with preserved fidelity for all wavelengths. The GPHs are fabricated by patterning a photo-alignment layer (PAL) using a direct-write laser scanner and coating the surface with a polymerizable liquid crystal (i.e., a reactive mesogen). We study various recording pixel sizes, down to 3 μm, that are easily recorded in the PAL. We characterize the fabricated elements and find good agreement with theory and numerical simulation. Because of the wavelength independent geometric phase, the (phase) fidelity of the replay images is preserved for all wavelengths, unlike conventional dynamic phase holograms. However, governed by the diffraction equation, the size and location of a reconstructed image depends on the replay wavelength for far-field and near-field GPHs, respectively. These offer interesting opportunities for white-light holography. View Full-Text
Keywords: liquid crystal; direct-write photo-alignment; computer-generated hologram liquid crystal; direct-write photo-alignment; computer-generated hologram
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Xiang, X.; Kim, J.; Escuti, M.J. Far-field and Fresnel Liquid Crystal Geometric Phase Holograms via Direct-Write Photo-Alignment. Crystals 2017, 7, 383.

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