| Summary: | 碩士 === 國立中山大學 === 物理學系研究所 === 96 === This study proposes a polarization-independent liquid-crystal Fresnel lens using the twisted nematic liquid crystal (TN-LC). At the high voltage state, the TN-LC behaves as an optically anisotropic material which makes the proposed LC Fresnel lens possess a polarization-insensitive characteristic. Two kinds of LC Fresnel lens, photoresist type and patterned electrodes type, are prepared in our experiment. Experimental results reveal that the photoresist type has a high diffraction efficiency and a good polarization-independent characteristic. However, its diffraction efficiency cannot be switched off. Contrarily, the patterned electrode type has the characteristics of the switch-off and good polarization-independent with a moderate diffraction efficiency
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