天大工程光学(下)期末考试试卷及答案

                                                                                           whenm=1,  三、计算(共50分) 1.(15分)解:由已知条件知小孔位置对应的衍射角        由双缝衍射公式                                         其中                               ,                             , a为缝宽、d为相邻两缝间隔得: 当                 时,    I=0。即          时,  I=0上式整理得:                                                                               代入m=4,5,6,7得:     为缺少的波长。 2.(20分)解:1)从两个缝发出的光到达P0点时的相位差为                                               P0点的光强为                          当相位差满足                             或薄片厚度满足               时,P0点的光强最大。当相位差满足                                 或薄片厚度满足                              时,P0点的光强最小。 2) 上面的缝宽增加到2d时,P0点的光强复振幅为此时P0点的光强度为                                              3.(15分)解:如图所示 P1⊥P2 ==