When a laser beam is aimed at a wire, a circle of light can be observed on a screen perpendicular to the wire. Explain this phenomenon and investigate how it depends on the relevant parameters.
当一个激光束瞄准一根金属丝，在垂直于金属丝的屏幕上可以观察到一个环形光线。解释这个现象并研究其与相关参量的依赖性。