S-LAH95 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{2.15637\,\lambda^2}{\lambda^2 - 0.0122881} + \frac{0.329558\,\lambda^2}{\lambda^2 - 0.0555508} + \frac{1.72179\,\lambda^2}{\lambda^2 - 124.439}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[9.86 \times 10^{-7} + 2(1.06 \times 10^{-8})\,\Delta T + 3(-1.51 \times 10^{-11})\,\Delta T^2 + \frac{9.56 \times 10^{-7} + 2(1.15 \times 10^{-9})\,\Delta T}{\lambda - 0.265}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$