P-LASF47 by Schott

$$n(\lambda) = \sqrt{1 + \frac{1.85543\,\lambda^2}{\lambda^2 - 0.0100328} + \frac{0.315855\,\lambda^2}{\lambda^2 - 0.0387095} + \frac{1.28562\,\lambda^2}{\lambda^2 - 94.5422}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[7.87 \times 10^{-6} + 2(1.09 \times 10^{-8})\,\Delta T + 3(-1.56 \times 10^{-11})\,\Delta T^2 + \frac{7.58 \times 10^{-7} + 2(8.92 \times 10^{-10})\,\Delta T}{\lambda - 0.218}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$