反射光光程差=2nd+λ/2=kλ时,干涉相长,n=1.5,d=1.2*10^-6m=1200nm,  k=1,2,3…

解出:  λ=4nd/(2k-1)=7200,2400,1440,1029,800,655,554,480,424,379,…nm
在可见光范围内反射最强的波长有: 655,554,480,424 nm