1主极大(中央明纹中心) I rsin(using/n wsin6/元 =0处,Ip=l0(=Imx) aa e 2次极大(次级明纹中心 d/0→tga=a;图解法→ =aidd, y tga a << 用半波带 法可解释 2兀 元 半波带法较粗略 振幅矢量法精确十 c=-3.47x,-2.46兀,-1.43, +1.43兀,+2.46兀,+3.47兀, →asin6=-347,-2.46λ,-1.43, +1.43元,+2.46,+3.47元 1p=0.008310,0.01650,0.0472l0, 0.04720,0.0165L0,0.008310, 3极小(暗纹中心:asi=土(k=1,2,…)处,Ip=0;o   -2 - 2 y y1 = tg y2 =  · · · · 2 0 ] sin / sin( sin / ) [       a a I I 1.主极大(中央明纹中心): P = 0 , ( max ) 0 I I I  = 处 P = = 3.极小(暗纹中心): sin =  ( = 1,2, ) = 0; P a  k k  处，I  = -3.47π, -2.46π, -1.43π, +1.43π, +2.46π, +3.47π, asin = −3.47 , − 2.46, −1.43, + 1.43, + 2.46, + 3.47, 2.次极大(次级明纹中心): , 0 tg ; sin        = = → = d a dI 图解法 0.0472I0 , 0.0472I0 0.0165I , 0 , 0.0165I0 ,0.0083I0 0.0083I , 0 = , P I I0 , 半波带法较粗略 振幅矢量法精确 I次<<I0 用半波带 法可解释