H-ZLAF75C by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.59327\,\lambda^2}{\lambda^2 - 115.386} + \frac{0.299677\,\lambda^2}{\lambda^2 - 0.0568069} + \frac{2.18604\,\lambda^2}{\lambda^2 - 0.0127689}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.51 \times 10^{-6} + 2(1.55 \times 10^{-8})\,\Delta T + 3(-4.16 \times 10^{-11})\,\Delta T^2 + \frac{9.28 \times 10^{-7} + 2(8.84 \times 10^{-10})\,\Delta T}{\lambda - 0.264}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$