手术显微镜是显微外科手术中不可或缺的工具，大物镜是整个手术显微镜的关键部位之一。针对手术过程中工作距和系统放大倍率需根据不同的使用情况进行调整，设计了一套连续变焦大物镜。所设计的连续变焦大物镜由正、负透镜组组成，选用机械变焦补偿形式，通过沿光轴方向移动正透镜组，实现术面观察范围Φ20 mm～Φ125 mm、工作距150～350 mm、焦距230~400 mm，可同时满足连续变焦和工作距可调，并给出正、负透镜组间隔与变焦位置的采样曲线，导程量较小。

Operating microscope is a necessary tool in microscope surgical operation, and the object lens is one important part of the operating microscope. The working distance and magnification in the operation should be adjusted to meet the needs of different users, thus a continuous zoom object lens was designed. The continuous zoom object lens is consisted of a set of double agglutinate positive lenses and negative lenses, which is zoomed by mechanical compensatation and moves axially. The operating area of the continuous zoom object lens is from Φ20 mm to Φ125 mm, the working distance is from 150 mm to 350 mm, and the focus is from 230 mm to 400 mm. The interval between the positive and negative lenses and the curve of zoom position was also put forward.