S-LAM59 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.63056\,\lambda^2}{\lambda^2 - 0.00899691} + \frac{0.186995\,\lambda^2}{\lambda^2 - 0.0368012} + \frac{1.30014\,\lambda^2}{\lambda^2 - 122.24}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.01 \times 10^{-6} + 2(1.19 \times 10^{-8})\,\Delta T + 3(-3.79 \times 10^{-11})\,\Delta T^2 + \frac{5.89 \times 10^{-7} + 2(6.69 \times 10^{-10})\,\Delta T}{\lambda - 0.214}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$