S-LAM51 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.63847\,\lambda^2}{\lambda^2 - 0.00904853} + \frac{0.188331\,\lambda^2}{\lambda^2 - 0.037274} + \frac{1.47502\,\lambda^2}{\lambda^2 - 137.77}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.39 \times 10^{-6} + 2(1.16 \times 10^{-8})\,\Delta T + 3(-3.52 \times 10^{-11})\,\Delta T^2 + \frac{4.18 \times 10^{-7} + 2(3.81 \times 10^{-10})\,\Delta T}{\lambda - 0.279}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$