Interferometer for measuring the absolute refractive index of liquid water as a function of temperature at 1.064 µm.

I describe here a new simple method for measuring the absolute refractive index of liquid water as a function of temperature at a wavelength of 1.064 µm with a Michelson interferometer. The mirror of the measuring arm is located in a water cell and displaced by a well-known distance. Compensation for a change in the optical path length in the reference arm of the interferometer is not necessary.