短焦段数字电影变焦放映镜头的设计

为了填补国内短焦段数字电影变焦放映镜头的空白及满足国内数字电影市场对大投射比镜头的需求,本文采用机械补偿式变焦原理,利用ZEMAX光学设计软件自主研发设计出一款适用于0.65英寸、单数字光处理器、1.3K数字电影放映机的短焦段连续变焦数字电影放映镜头.镜头包括前固定组、变倍组、补偿组和后固定组,由8组10片玻璃球面透镜组成,其中变倍组由一片负透镜构成,补偿组由两组双胶合透镜组构成.镜头总长170mm,全口径70mm,变焦范围为14.5～18.2mm,相对孔径为1/2,投射比范围为0.99∶1～1.23∶1,后工作距离为32.6mm.镜头凸轮曲线的设计采用等间隔变焦的方法,设计出了平滑稳定、斜率适宜、压力角小的凸轮曲线,具有加工方便、加工准确度高、变倍组升角容易控制且焦距变化均匀的优点.整个镜头结构简单、体形小、重量轻、成本低.

Optical Design of Digital Movie Zoom Projection Lens

To fill the vacancy of domestic short focal range digital movie zoom projection lens and to meet the requirement of the market, a digital movie zoom projection lens for 0.65 inch DLP 1.3 K digital movie projector was designed by the mechanical compensation method. It includes the former fixed group, the zoom group, the compensation group and the last fixed group. It is composed of ten glass sphere lenses, and the zoom group is composed of one negative lens, the compensation group is composed of two doublet lenses. The total length of the digital movie zoom projection lens is 170 mm, the full aperture is 70 mm. Its focal length range is 14.5～18.2 mm, F-number is 2, projection ratio range is 0.99∶1～1.23∶1, and the BFL is 32.6 mm. The cam curves were designed with the method of equal interval zoom. The image quality in each focal length is excellent with advantages of simple structure, small size, and low cost, and its cam curves are smooth without cam inflexions and processed easily.