H-ZF62 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{2.55247\,\lambda^2}{\lambda^2 - 162.451} + \frac{0.465682\,\lambda^2}{\lambda^2 - 0.0695601} + \frac{2.02895\,\lambda^2}{\lambda^2 - 0.0147711}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-6.75 \times 10^{-6} + 2(1.69 \times 10^{-8})\,\Delta T + 3(-4.1 \times 10^{-11})\,\Delta T^2 + \frac{9.81 \times 10^{-7} + 2(1.32 \times 10^{-9})\,\Delta T}{\lambda - 0.322}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$