S-LAH60MQ by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.95539\,\lambda^2}{\lambda^2 - 0.0109111} + \frac{0.30255\,\lambda^2}{\lambda^2 - 0.0454667} + \frac{1.34311\,\lambda^2}{\lambda^2 - 113.581}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-5.59 \times 10^{-6} + 2(8.45 \times 10^{-9})\,\Delta T + 3(-3.12 \times 10^{-11})\,\Delta T^2 + \frac{8.18 \times 10^{-7} + 2(8.56 \times 10^{-10})\,\Delta T}{\lambda - 0.238}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$