fraction

说明：  能够通过程序的方法实现光束经菲涅尔衍射后的光强分布，从而更加直观地理解和掌握其衍射特性，有助于更好地学习，对学习其衍射起到非常重要的作用
(The light intensity distribution of the beam after Finel diffraction can be realized through the program method, so that it can understand and master the diffraction characteristics more intuitively, and help to study better, and play a very important role in learning its diffraction.)