2sin/dsin(/2)sin(/2)ENEsindk相邻主级大之间sindksin(1)dk正k级主极大正k+1级主极大si)1n(dk正k级主极大正k+1级主极大sin()sin()ENkENEk/2k/2()1ksin(())sin()1)1(ENkENEkNkNkNNkk1,2......10,,NkN0kNk1,2......1Nksin()0?sin(/2)kENkE/2/2/()//NNkNkNkNksin/2/(/)//dkNkkkN1,2......1Nk2sin/dsin(/2)sin(/2)ENEsindk相邻主级大之间sindksin(1)dk正k级主极大正k+1级主极大si)1n(dksin/kkNd1,2......10,,NkN0ksindk正k级主极大Nksin(1)dk正k+1级主极大1,2......1Nksin(/2)sin()0sin(/2)sin(/)kNkNkNk暗纹暗纹相邻主极大之间,共有N-1条暗纹。/2/kkN相邻缝的光程差:则相邻缝的位相差:缝数与主级大之间的暗纹sin/kkNd2sin/d22/Nkk1,2......1Nk12/kN2/kN22/2kN32/3kN……1(1)2/kNNN2缝3缝4缝5缝6缝1k2k3k4k5k2/32/322/kkN/23/22/54/56/58/5/32/34/35/322222暗纹暗纹主级大主级大dP●暗纹与次极大在两个主极大之间sindksin(1)dk考虑0级主极大与1级主极大之间sindkN1,2......1,0,NkNk‘等于0为0级主极大,k‘等于N为N级主极大,不与考虑。sin/dNdP●暗纹与次极大sin/dN共有N个缝,N很大缝对应的编号分别为:1,2,3,……,N则缝1与缝N/2+1之间的位相差为:/2sin/2//2NdNN则缝1与缝N/2+1干涉相消,缝2与缝N/2+1干涉相消,……,缝N/2与缝N干涉相消。为暗纹dP●暗纹与次极大sindkN1,2......1Nk同理证得则N个缝会整体干涉相消。均为暗纹则相邻两个主极大之间有N-1个暗纹。而相邻两个暗纹之间会有一个次级大,则N-1个暗纹间共有N-2个次极大。强度仅4%左右太弱有时看不到