设计了一款2.4倍变焦距的紧凑型数码镜头，焦距的变化范围是3~7.2 mm，视场的变化范围是62°~30°。该镜头是个3组结构，第1组是个固定组，2，3组是变倍组，共有4个透镜。该镜头组是一个典型的负正正（NPP）结构，第1组是一个负透镜，第2组是一个正透镜组，第3组是一个正透镜。其中，第2组包含两个透镜，这样有利于色差的控制。镜头中所有透镜的材料均为塑料材料。调制传递函数被用来评价变焦距系统的成像质量。变焦镜头的调制传递函数值在空间频率142 lp/mm，0.7视场处，均大于0.3。该镜头的总长度为10.7 mm。该镜头的像质可以很好地满足消费性电子产品的要求。

A compact zoom lens with 2.4X optical zoom is presented. Its effective focal length ranges from 3 to 7.2 mm and its angle of field ranges from 62° to 30°. The zoom lens belongs to three-groups structure, including the first fixed group and the second and the third variable groups, and consists of four pieces of lenses. The zoom lens configuration is negative-positive-positive(NPP) type. The first lens group is a single negative lens. The second lens group consisting of two lens elements is a positive lens group. And, the third lens group is a single positive lens. The second lens group can effectively correct chromatic aberration. All lens elements are made up of plastic materials. Modulation transfer function(MTF) is used to evaluate the zoom lens image quality. The MTF of zoom lens is greater than 0.3 at 142 lp/mm in the 0.7 field of view. The total track length of the lens is about 10.7 mm. Due to its excellent image quality, the lens can be applied to many consumer electronic products.