Chen Hung-Shan, Lin Yi-Hsin
Department of Photonics, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan.
Opt Express. 2013 Jul 29;21(15):18079-88. doi: 10.1364/OE.21.018079.
Conventional endoscopic systems consisting of several solid lenses suffer from a fixed and limited depth-of-field (DOF). For practical applications, conventional endoscopes mechanically change the distance between the solid lenses of a lens module in order to change the focusing plane and DOF to see clearly in a scene. In this paper, we demonstrate an electrically tunable endoscopic system adopting a liquid crystal lens. By means of tunable focusing properties of the LC lens as a positive lens and a negative lens, the object at different objective distances can be imaged to the image sensor clearly and the corresponding depth-of-field can also help to enlarge the total spatial depth perception in a scene. The optical mechanism is discussed. In the experiments, under adjustment of three discrete lens powers of the LC lens, the viewing range or total spatial depth perception of the endoscopic system is from 76.4 mm to 12.4 mm which is 2x improved compared to the conventional one without LC lens. We believe this study can be extended to the applications of industrial and medical endoscopes.
由多个固体透镜组成的传统内窥镜系统存在固定且有限的景深（DOF）。在实际应用中，传统内窥镜通过机械方式改变透镜模块中固体透镜之间的距离，以改变聚焦平面和景深，从而在场景中清晰成像。在本文中，我们展示了一种采用液晶透镜的电可调内窥镜系统。借助液晶透镜作为正透镜和负透镜的可调聚焦特性，不同物距的物体可以清晰地成像到图像传感器上，相应的景深也有助于扩大场景中的总空间深度感知。文中讨论了光学机制。在实验中，在液晶透镜的三种离散透镜光焦度调整下，内窥镜系统的视场范围或总空间深度感知为76.4毫米至12.4毫米，与没有液晶透镜的传统内窥镜相比提高了2倍。我们相信这项研究可以扩展到工业和医疗内窥镜的应用中。
