许多应用都期望以大视场搜索定位目标，以小视场瞄准跟踪目标。提出并设计一款小型化两档7.5^×变焦距成像系统，其工作于486 nm～656 nm的可见光波段，短焦视场为±15°，长焦视场为±2°，两视场下F数均为2.8，系统总长仅为60 mm。系统由玻璃镜片及注塑镜片混合组成，包含一个前固定组和一个可动组，通过可动组在2个变焦位置间的切换完成广角搜索功能和长焦凝视功能的转换，具有小型化、轻量化、低成本的优势。

Many applications expect to search for targets with a large field of view (FOV) , and identify the targets in a relative small FOV. A miniaturized two-step 7.5^× zoom system was proposed and designed, which worked in the visible band of 486 nm~656 nm with a wide-angle FOV of ±15°, telephoto FOV of ±2°, F-number in both FOV of 2.8, and overall length of 60 mm. The system consisted of glass lenses and plastic-injection lenses, which contained one front fixed group and one movable group. The conversion of wide-angle search function and long-focus gaze function was completed by switching the movable group between two zoom positions, which had the advantages of miniaturization, lightweight and low cost.