S-LAH53V by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.96601\,\lambda^2}{\lambda^2 - 0.0107818} + \frac{0.205143\,\lambda^2}{\lambda^2 - 0.0463728} + \frac{1.23201\,\lambda^2}{\lambda^2 - 97.6941}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[9.36 \times 10^{-6} + 2(1.13 \times 10^{-8})\,\Delta T + 3(-1.33 \times 10^{-11})\,\Delta T^2 + \frac{8.08 \times 10^{-7} + 2(8.51 \times 10^{-10})\,\Delta T}{\lambda - 0.236}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$