S-LAL52 by Ohara

$$n(\lambda) = \sqrt{2.74187 - 0.0127192\,\lambda^2 + 0.016307\,\lambda^{-2} + 0.000614142\,\lambda^{-4} - 4.82426 \times 10^{-5}\,\lambda^{-6} + 2.88759 \times 10^{-6}\,\lambda^{-8}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-4.1 \times 10^{-6} + 2(1.15 \times 10^{-8})\,\Delta T + 3(3.8 \times 10^{-11})\,\Delta T^2 + \frac{2.44 \times 10^{-7} + 2(2.82 \times 10^{-10})\,\Delta T}{\lambda - 0.299}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$