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Holographic color filters for liquid crystal displays

Authors Bao, Zhong
Issue Date 1997
Summary Holographic color filters for LCDs are discussed in this thesis. Transmission and reflection holographic color filters have been experimentally fabricated and charac-terized. Because of their high efficiency (>90%) and excellent color purity, holo-graphic color filters demonstrate superior optical performance in comparison to currently utilized dyed color filters whose efficiencies are typically on the order of 25 percent. The holographic color filters were fabricated by the simple interference of two plane-wave beams from an argon-ion laser in holographic recording materials. Tri-color RGB reflection and transmission color filters were obtained by selectively varying the relative angle between the two write beams or by changing the wavelength of the laser beams. The holographic recording material used in all the experiments was a photopolymer by DuPont which does not require any post-exposure wet-developing thereby minimizing film shrinkage and expansion which can cause a color shift. In our experiments, transmission and reflection color filters were fabricated with extremely high efficiencies (98% for transmission color filters, 94% for reflection color filters), and excellent color purities (>98% for blue and red colors,>82% for green color filters). The viewing angles for these filters were about 1.5 degrees and 15 degrees for transmission type and reflection type color filters respectively. A tech-nique of recording multiple gratings was utilized to increase the viewing angle. The center wavelengths of RGB three primary colors of the color filters were designed to match the response function of human eye and could be custom tailored for a wide variety of applications. The efficiency of the holographic color filters can be selected by changing the intensity ratio of the two write beams, exposure energy, or thickness of the holographic recording material. Experimental results indicate that holographic color filters can significantly improve the optical performance of the liquid crystal displays and this simple, versatile, and manufacturable technique is suitable for a wide variety of display requirements. Acknowledgments
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 1997
Language English
Format Thesis
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