S-LAM52 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.73443\,\lambda^2}{\lambda^2 - 0.0100691} + \frac{0.151554\,\lambda^2}{\lambda^2 - 0.0470635} + \frac{1.46225\,\lambda^2}{\lambda^2 - 140.084}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.33 \times 10^{-6} + 2(1.04 \times 10^{-8})\,\Delta T + 3(-3.33 \times 10^{-11})\,\Delta T^2 + \frac{6.18 \times 10^{-7} + 2(7.64 \times 10^{-10})\,\Delta T}{\lambda - 0.246}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$