S-TIH10 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.61549\,\lambda^2}{\lambda^2 - 0.0119831} + \frac{0.262433\,\lambda^2}{\lambda^2 - 0.059651} + \frac{2.09426\,\lambda^2}{\lambda^2 - 181.658}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.13 \times 10^{-6} + 2(1.15 \times 10^{-8})\,\Delta T + 3(-4.29 \times 10^{-11})\,\Delta T^2 + \frac{8.62 \times 10^{-7} + 2(1.18 \times 10^{-9})\,\Delta T}{\lambda - 0.295}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$