大焦深内窥镜光学系统设计

Design of a kind of large depth of focus endoscope system

医用内窥镜技术要求在大的物距范围内实现清晰成像,但其使用环境又对系统尺寸及镜片数目的要求非常严格,难以利用传统方法实现光学调焦。在传统的光学设计中,通常依靠减小相对孔径来增大系统焦深,往往会造成许多负面影响。介绍了一种电润湿型液体可变焦透镜,并在这一新型元件的基础上,设计了一种微型可调焦光学系统。该系统依靠外加电压控制液体透镜焦距做微小改变,从而校正由于物距变化产生的离焦,增大内系统的焦深,同时保证系统的微型结构。这一设计将使内窥镜的使用更加方便,有着广泛的应用前景。

Endoscope system is required to have large depth of focus. But it is very difficult to realize focal adjusting in endoscope by traditional methods, for its restricted requirements on the dimension of the system and the numbers of the lens. In normal optical design, stopping down the apperture is often adopted to extend the depth of focus of a system. But this method has many serious disadvantages such as decreasing the optical flux and the resolution at imaging plane. A kind of liquid lens based on electrowetting effect is introduced, which is considered as a kind of novel optical component. A micro focus controlling endoscope system is designed, in which the liquid lens is used as a core element. The focal length of the liquid lens can be adjnsted by an external electric field, which can compensate the defocusing of the system coused by the change of the object distance. This can make the endoscope system using more convenient and can have very wide application in the future.