光在非均匀介质中传播规律的演示

光在介质中的传播规律遵循费马原理，如：在均匀介质中，光沿直线传播．在非均匀介质中，光的传播轨迹比较复杂，与非均匀介质的状态有密切关系．尽管海市蜃楼和沙漠幻影是大自然中能够看到的光在非均匀介质中的传播现象，但只有在一定条件下才能出现，不是随时可以看到的．为了能在光学教学中让学生能够看到光在非均匀介质中的传播，本文利用白糖溶液和水之间扩散形成的浓度非均匀区域，实现了光线的非直线传播．通过光线实际传播的路径，计算了非均匀区域液体折射率的相对变化．这一演示实验取材简单，容易实现，对学生思维训练具有一定的借鉴意义．

EXPERIMENTAL DEMONSTRATION OF THE PROPAGATION OF LIGHT IN AN INHOMOGENEOUS MEDIUM

The law of propagation of light in a medium follows the Fermat＇s principle. For example, in a homogenous medium the rays will be straight lines. In an inhomogeneous medium, the paths of rays are complicated and related with the variation of refractive index. The superior mirage above cold water and the interior mirage above the hot land surface are natural phenomena of the propagation of light in an inhomogeneous medium. However, they can appear only under certain conditions and cannot appear at any time. In order to observe the mirage phenomena in the optics teaching classroom, in this paper, nonlinear transmission of light was achieved in the interchange area between water and sugar solution. The relative variation of refractive index was calculated from the actual path of light. The demonstrative experiment was simple and easily performed, and the students can learn some of scientific research training from it.