TAFD35L by Hoya

$$n(\lambda) = \sqrt{3.52699 - 0.0144024\,\lambda^2 + 0.0400479\,\lambda^{-2} + 0.00169507\,\lambda^{-4} - 7.32109 \times 10^{-5}\,\lambda^{-6} + 1.08145 \times 10^{-5}\,\lambda^{-8}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.57 \times 10^{-6} + 2(9.7 \times 10^{-9})\,\Delta T + 3(-3.33 \times 10^{-11})\,\Delta T^2 + \frac{7.61 \times 10^{-7} + 2(9.11 \times 10^{-10})\,\Delta T}{\lambda - 0.247}\right] \Delta T = T - T_0, \quad T_0 = 23\,°\text{C}$$