H-ZLAF92 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.86762\,\lambda^2}{\lambda^2 - 123.079} + \frac{0.375569\,\lambda^2}{\lambda^2 - 0.0596644} + \frac{2.45933\,\lambda^2}{\lambda^2 - 0.0141482}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-5.53 \times 10^{-7} + 2(1.56 \times 10^{-8})\,\Delta T + 3(-5.25 \times 10^{-11})\,\Delta T^2 + \frac{1 \times 10^{-6} + 2(1.17 \times 10^{-9})\,\Delta T}{\lambda - 0.275}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$