H-ZLAF91 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.384293\,\lambda^2}{\lambda^2 - 0.0575837} + \frac{2.44632\,\lambda^2}{\lambda^2 - 0.0137641} + \frac{1.89452\,\lambda^2}{\lambda^2 - 128.019}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.69 \times 10^{-6} + 2(1.29 \times 10^{-8})\,\Delta T + 3(-3.72 \times 10^{-11})\,\Delta T^2 + \frac{1.06 \times 10^{-6} + 2(1.39 \times 10^{-9})\,\Delta T}{\lambda - 0.259}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$