MP-BACD5N by Hoya

$$n(\lambda) = \sqrt{2.48951 - 0.012245\,\lambda^2 + 0.0129426\,\lambda^{-2} + 0.000349045\,\lambda^{-4} - 1.77723 \times 10^{-5}\,\lambda^{-6} + 9.11372 \times 10^{-7}\,\lambda^{-8}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[3.33 \times 10^{-6} + 2(1.01 \times 10^{-8})\,\Delta T + 3(-4.77 \times 10^{-11})\,\Delta T^2 + \frac{6.07 \times 10^{-7} + 2(6.78 \times 10^{-10})\,\Delta T}{\lambda - 8.15 \times 10^{-9}}\right] \Delta T = T - T_0, \quad T_0 = 23\,°\text{C}$$