S-NBH52V by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.51337\,\lambda^2}{\lambda^2 - 0.00987078} + \frac{0.212341\,\lambda^2}{\lambda^2 - 0.0462844} + \frac{1.54149\,\lambda^2}{\lambda^2 - 126.979}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.73 \times 10^{-6} + 2(7.81 \times 10^{-9})\,\Delta T + 3(-1.96 \times 10^{-11})\,\Delta T^2 + \frac{7.27 \times 10^{-7} + 2(8.31 \times 10^{-10})\,\Delta T}{\lambda - 0.248}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$