S-LAL59 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.13963\,\lambda^2}{\lambda^2 - 0.00493295} + \frac{0.805228\,\lambda^2}{\lambda^2 - 0.020248} + \frac{1.29488\,\lambda^2}{\lambda^2 - 93.4747}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[5.63 \times 10^{-6} + 2(2.04 \times 10^{-8})\,\Delta T + 3(-5.33 \times 10^{-12})\,\Delta T^2 + \frac{5.86 \times 10^{-7} + 2(7.5 \times 10^{-10})\,\Delta T}{\lambda - 0.176}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$