ΔL 𝜆^2 /ΔL ng ng1 ng2 ng3 ng4
100 0.024025 4.26 5.639671362 5.652941176 5.761390887 5.775240385
200 0.0120125 4.25 2.819835681 2.826470588 2.880695444 2.887620192
300 0.008008333 4.17 1.879890454 1.884313725 1.920463629 1.925080128
400 0.00600625 4.16 1.40991784 1.413235294 1.440347722 1.443810096