We report an experimental method for high-precision refractive index measurement using a Michelson interferometer setup with a femtosecond optical frequency comb as the light source. We demonstrate this technique by measuring the refractive index of air, under different pressures, inside a 29 m multipass cell. Both spectral and temporal interferograms are recorded. The method has a sensitivity of 6.2×10<sup>−9</sup> and a standard error of 7.4×10<sup>−8</sup> at fixed parameters (pressure and temperature). The possible variation of the density factor from the Lorentz-Lorenz equation is also discussed.
© 2005 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.4530) Instrumentation, measurement, and metrology : Optical constants
Instrumentation, Measurement, and Metrology
J. Zhang, Z. H. Lu, and L. J. Wang, "Precision measurement of the refractive index of air with frequency combs," Opt. Lett. 30, 3314-3316 (2005)