M-FDS910 by Hoya

$$n(\lambda) = \sqrt{3.16599 - 0.013492\,\lambda^2 + 0.0464992\,\lambda^{-2} + 0.00247141\,\lambda^{-4} - 8.6596 \times 10^{-5}\,\lambda^{-6} + 2.72593 \times 10^{-5}\,\lambda^{-8}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-5.47 \times 10^{-6} + 2(5.77 \times 10^{-9})\,\Delta T + 3(-3.7 \times 10^{-11})\,\Delta T^2 + \frac{9.25 \times 10^{-7} + 2(1.02 \times 10^{-9})\,\Delta T}{\lambda - 1.26 \times 10^{-9}}\right] \Delta T = T - T_0, \quad T_0 = 23\,°\text{C}$$