薄凸透镜是光学仪器中最重要、最基本的元件, 在天文、**、医学等众多领域发挥着重要作用。焦距是薄透镜、反射镜等光学系统最重要的特性参量, 因而准确测量薄透镜的焦距则显得尤为重要。实验室测量薄凸透镜焦距的方法有物距像距法、自准直法、光电法、平行光管法等。由于采用前3种方法测量透镜焦距的精度偏低, 针对该问题, 提出利用平行光管法测量薄凸透镜的焦距, 并对实验误差作简单分析。实验结果表明, 该方法可以高精度地测量薄凸透镜焦距, 相对误差仅为0.138%。因此, 采用平行光管法的薄凸透镜焦距测量方法是有效可行的。

Thin convex lenses are the most important and basic components of optical instruments. It plays an important role in many fields such as astronomy , military and medicine. The focal length is the most important characteristic parameter of optical systems such as thin lens and mirrors. Hence, it is particularly important to accurately measure the focal length of the thin lens. The methods for measuring focal length of thin convex lens are the object/image distance method, self-collimation method, optical-electrical method and parallel tube method in laboratory. Aiming at the problem of low accuracy of measuring the lens focal length by the first three methods, the parallel tube method was adopted to measure the focal length of thin convex lens and the experimental error was analyzed simply. Experimental result shows that, the method can measure the focal length of thin convex lens with high precision, the relative error is only 0.138 %. Therefore, the method for measuring focal length of thin convex lens by parallel tube method is effective and feasible.