S-LAM54 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.84213\,\lambda^2}{\lambda^2 - 0.00943993} + \frac{0.175469\,\lambda^2}{\lambda^2 - 0.0395281} + \frac{1.25751\,\lambda^2}{\lambda^2 - 86.5463}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[4.27 \times 10^{-6} + 2(1.66 \times 10^{-8})\,\Delta T + 3(-3.72 \times 10^{-11})\,\Delta T^2 + \frac{4.44 \times 10^{-7} + 2(5.21 \times 10^{-10})\,\Delta T}{\lambda - 0.257}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$