D-ZF93-25 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.43302\,\lambda^2}{\lambda^2 - 101.185} + \frac{2.13631\,\lambda^2}{\lambda^2 - 0.0138161} + \frac{0.630184\,\lambda^2}{\lambda^2 - 0.0658578}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.28 \times 10^{-5} + 2(3.34 \times 10^{-8})\,\Delta T + 3(-1.53 \times 10^{-10})\,\Delta T^2 + \frac{2.75 \times 10^{-6} + 2(2.52 \times 10^{-9})\,\Delta T}{\lambda - 0.299}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$