S-LAM7 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.71015\,\lambda^2}{\lambda^2 - 0.0105161} + \frac{0.256943\,\lambda^2}{\lambda^2 - 0.050281} + \frac{1.63986\,\lambda^2}{\lambda^2 - 146.181}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[4.3 \times 10^{-6} + 2(1.23 \times 10^{-8})\,\Delta T + 3(-3.62 \times 10^{-11})\,\Delta T^2 + \frac{7.71 \times 10^{-7} + 2(8.56 \times 10^{-10})\,\Delta T}{\lambda - 0.265}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$