Trong TN Iang, a=2mm,D=1m. Chieu dong thoi hai buc xa lamda1 va lamda2( lamda2>lamda1) thi van sang bac 3 cua lamda1 trung van sang bac k cua lamda2 va cach van trung tam 0,6 mm. Hoi k va lamda2
[tex]x=0,6=k.\lambda_2.D/a=3.\lambda_1.D/a[/tex]
[tex]==> \lambda_1=0,4\mu m ==> \lambda_2=3.\lambda_1/k[/tex]
[tex]0,4 < \lambda_2=1,2/k <= 0,76 ==> 1,57 <= k < 3 [/tex]
[tex]==> k=2 ==> \lambda_2=0,6 \mu m[/tex]