光栅常数d，波长l1=400，l2=600d*sin60°=k1*l1d*sin60°=k2*l2当k1=33，k2=20时，k1*l1=k2*l2=13.2umd=13.2/sin60°=15.2um
dsinθ=k1*λ1dsinθ=k2*λ2k1/k2=λ1/λ2=3/2=6/4所以 k1=6 k2=4 d=k1*λ1/sinθ=3.05 微米
