半波带法研究夫琅禾费单缝衍射的局限性分析

Analysis on Limitations of the Half-wave-strip Method in Studying Fraunhofer Single-slit Diffraction

本文对半波带法研究夫琅禾费单缝衍射的局限性进行了分析.在半波带法的基础上对单缝波阵面进行了更精细的分割,采用振幅矢量图解法对半波带法给出的明纹条件进行了修正,修正后的明纹条件表明,决定单缝衍射明纹振幅的不足一个半波带,而并非恰好一个半波带.同时,利用该方法还得到了衍射光强,与积分法求解衍射光强相比,这一方法在物理上更直观,在数学上更简洁.此外,与半波带法对单缝波阵面进行有限分割相比,该方法充分体现了衍射现象和干涉现象之间的区别和所采取的计算方法的不同,更有利于学生加深对衍射本质的理解.

This article analyzed the limitations of the half-wave strip method in studying single-slit Fraunhofer diffraction.The single-slit wave front was further sliced into fine strips on the basis of the slicing according to half-wave strip method,based on which graphic method of amplitude vector was adopted to modify the bright fringe condition given by the half-wave strip method.The modified bright fringe condition indicates that the bright fringe amplitude of single-slit diffraction is determined by less than one half-wave strip other than exactly one half-wave strip.Meanwhile,the diffraction intensity was also obtained applying this method,which is more intuitive in physics and simple in mathematics.Moreover,compared with the half-wave strip method in which the single-slit wave front is sliced into limited strips,this method also completely embodies the distinction between diffraction phenomena and interference phenomena and the difference in their studying methods,which is more helpful for students to deepen the comprehension on essence of diffraction.