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为了在便携式设备上实现光学影像缩放，不包含机械式移动的光学系统开发是必要的，因此，我们对可电控改变焦距的液晶透镜所组成的光学系统进行研究，研究内容包含液晶透镜焦距对于放大率、变焦比以及对焦范围的关系.由于单片液晶透镜仅能达到对焦功能，因此我们首先利用两片液晶透镜组成的系统来计算不同物体距离的影像缩放条件.接着，我们利用三片液晶透镜，做到与机械式系统相同，可单独控制清楚物体平面距离以及控制影像大小的系统.实验结果表明：利用三片透镜屈光率从－11．3 m－1连续电控调整至24．9 m－1的液晶透镜，可实现清楚物体平面距离由10 cm连续调整至100 cm且缩放比为6．5∶1的光学缩放系统.我们利用不同调焦范围的液晶透镜，根据设计原理，来达成不同对焦范围与不同缩放比的电控光学缩放系统.

In order to realize optical zoom system on the portable devices,the optical system without any mechanical moving part is necessary.Therefore,we established the electrically tunable optical zoom system using liquid crystal(LC)lenses and investigated the relation between the focal length of the LC lens,magnification of images,zoom ratio and the obj ect distance.One LC lens can only have the function of focusing,therefore,first,we utilized two LC lenses to design the optical system and figure out the zoom ratio at different obj ect distance.Second,we used three LC lenses to establish the system that the function of focusing and zooming can be controlled independently and it is similar with the mechanically tunable system.Experimental results indicate that by using three LC lenses with tunable lens power ranging from -11.3 m-1 to 24.9 m-1 ,we can achieve electrically tunable optical zoom system.The object distance of the system can be changed form 10 cm to 100 cm continuously and the zoom ratio is 6 .5∶1 .According to the principles,we can achieve electrically tunable optical zoom system with different range of obj ect distance and different zoom ratio by LC lenses with different tunable lens power range.