A tunable-focus liquid crystal (LC) lens is prepared. The orientation of the LC is controlled using a homeotropic polyimide (PI) layer and a homogeneous PI layer. The homeotropic PI layer has a concave shape. The LC in the concave space presents a hybrid alignment and has a convex shape. As a result, the LC has a lens character with the shortest focal length in the voltage-off state. The focal length can be tuned from 9 to 15 cm when an applied voltage is changed from 0 to 8 Vrms. Our LC lens has no threshold voltage, and the fabrication procedure is relatively simple. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
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