测量玻璃和水的折射率,是光学中的一个基本实验。这里我们描述一个特别简单而在物理上又很有指导意义的测量方法。实验所需的仪器是一个小功率氦—氖激光器,一个测径器,螺旋测微器和一卷半透明的胶带。当一束激光打到一块毛玻璃上时,我们可以观察到围绕着光束中心的一个暗圆环,图1是一个这种暗环的照片,圆环的直径与 Measuring the refractive index of glass and water is a basic experiment in optics. Here we describe a particularly simple and physically instructive measurement method. The instrument required for the experiment was a low-power He-Ne laser, a caliper, a spiral micrometer and a roll of translucent tape. When a laser hits a piece of frosted glass, we can observe a dark ring around the center of the beam. Figure 1 is a picture of a dark ring with a diameter of