Index of Refraction

[Akhenathon]

Hi, all.

IOR of materials are measured in the Fraunhofer D-line of the spectrum (the sodium emission, 589.592 nm).

The A-coefficient in the Cauchy equation is the material IOR, when wavelength tends to infinity.

Indigo asks for the IOR and the B-coefficient. Which one is the correct value for the IOR: the A-coefficient or the tabulated IOR (measured in the D-line)?

Thanks in advance.

[OnoSendai]

The A coefficient.

[Akhenathon]

Thank you, Ono.