https://www.nist.gov/publications/picometer-metrology-precise-measurement-refractive-index-pressure-and-temperature
Picometer Metrology for Precise Measurement of Refractive Index, Pressure, and Temperature | NIST
Feb 17, 2017 - Fabry-Perot interferometers can be used for very precise measurement of the refractive index of gasses.
pressure and temperature