H-LAK59A by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.63613\,\lambda^2}{\lambda^2 - 0.0086977} + \frac{0.169162\,\lambda^2}{\lambda^2 - 0.0295057} + \frac{0.929985\,\lambda^2}{\lambda^2 - 82.4994}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-5.25 \times 10^{-6} + 2(1.39 \times 10^{-8})\,\Delta T + 3(-3.66 \times 10^{-11})\,\Delta T^2 + \frac{5.03 \times 10^{-7} + 2(5.22 \times 10^{-10})\,\Delta T}{\lambda - 0.184}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$