S-LAH52Q by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.91082\,\lambda^2}{\lambda^2 - 0.0103565} + \frac{0.239855\,\lambda^2}{\lambda^2 - 0.0413805} + \frac{1.1616\,\lambda^2}{\lambda^2 - 96.6037}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.08 \times 10^{-5} + 2(1.21 \times 10^{-8})\,\Delta T + 3(-1.6 \times 10^{-11})\,\Delta T^2 + \frac{8.62 \times 10^{-7} + 2(8.63 \times 10^{-10})\,\Delta T}{\lambda - 0.222}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$