H-ZF52TT by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.409983\,\lambda^2}{\lambda^2 - 0.0621421} + \frac{2.37517\,\lambda^2}{\lambda^2 - 185.055} + \frac{1.83914\,\lambda^2}{\lambda^2 - 0.0136093}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-6.18 \times 10^{-6} + 2(1.63 \times 10^{-8})\,\Delta T + 3(-4.5 \times 10^{-11})\,\Delta T^2 + \frac{1.12 \times 10^{-6} + 2(1.19 \times 10^{-9})\,\Delta T}{\lambda - 0.291}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$