Commercial auto-stereoscopic display systems have equipped optical lenticular lens sheets in order to realize the function which is able to support two images or views to right and left eyes of viewers. In applications of auto-stereoscopic display, the method of using the lenticular lens sheet, also called time- or spatial-multiplexed method, is first proposed as a patent by Ichinose [1]. The method has more advantages, which includes high luminous performance, movable of eyes position with constant view distance and watchable of multi-viewer. Besides, it can be also easily manufactured to make it very popular. Owing to the superiority, some studies about lenticular lens sheets have been proposed. Berkel et al. [2] have proposed several researches about the method of using lenticular lens sheets on multi-view auto-stereoscopic displays, and he has also proposed that slanted lenticular lens sheets or pixels could be improved the effect of flipped image by boundaries of lens and pixel [3–5]. 2D/3D switchable display is first realized by a method of dual-lenticular lens sheets [6]. Moreover, the method of using lenticular lens sheets has been proposed to be replaced by liquid crystal, LC, lens arrays, [7–9] in order to control viewer distance based on a function of tunable focal length. For the method, some issues of LC lenses should be solved like non-smooth potential in the LC layer and to improve the lens power [10–12].
Liquid crystal-based square lens array with tunable focal length