nλ/2\mathrm{n} \lambda / 2nλ/2
(2n+1)λ/2(2 n+1) \lambda / 2(2n+1)λ/2
(n+1)λ/2(\mathrm{n}+1) \lambda / 2(n+1)λ/2
nλ\mathrm{n} \lambdanλ