为减小机械补偿式连续变焦热像仪在变焦过程中的光轴漂移, 根据连续变焦原理, 对系统初始参数进行反复优化, 保证补偿组移动曲线的平滑度, 并将变倍组与补偿组的凸轮曲线设计为非线性变化曲线, 既保证了焦距变化的均匀性, 又减小了因凸轮转动引起的光轴漂移。利用多项式及三角函数拟合出了不同视场角下的光轴漂移曲线, 并利用动态软件补偿技术来弥补光轴漂移的系统误差。结果表明, 处理后的光轴漂移量可以控制在一个CCD像元尺寸左右, 且具有较强的鲁棒性, 对同类变焦镜头的设计及使用具有一定的参考价值。

In order to reduce the optical axis drift of the mechanical compensating continuous zoom thermal imager during zooming, on the basis of the researches on the structure and principle of the continuous zoom infrared thermal imager, we optimized the initial system parameters to ensure the smoothness of the compensation group moving curve, and designed the cam curves of the zoom group and compensation group to be non-linear, which could ensure the uniformity of the focal length and reduce the optical axis drift caused by the rotation of the cam. For systematic errors, we fitted the axis drift curve by using trigonometric functions and polynomials, and took advantage of dynamic software compensation techniques to compensate the optical axis drift. The results show that the optical axis drift can be controlled within about a charged couple device (CCD) pixel size in this method. This way has strong robustness,which can provide a certain reference value for similar zoom lens design.