H-LAF50B by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.17461\,\lambda^2}{\lambda^2 - 82.6268} + \frac{1.6589\,\lambda^2}{\lambda^2 - 0.00805128} + \frac{0.413174\,\lambda^2}{\lambda^2 - 0.0269613}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[2.17 \times 10^{-6} + 2(1.36 \times 10^{-8})\,\Delta T + 3(-3.28 \times 10^{-11})\,\Delta T^2 + \frac{5.95 \times 10^{-7} + 2(8.86 \times 10^{-10})\,\Delta T}{\lambda - 0.161}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$