Multi-color method for the self-correction of the air refractive index.

ABSTRACT

We propose a multi-color method for the self-correction of the air refractive index based on the dispersive interferometry of an optical frequency comb. This method can be applied to correct the air refractive index for long-distance measurements in moist air. Optical lengths of multiple wavelengths were obtained simultaneously by the dispersive interferometry of an optical frequency comb. Interferometric measurement results and calculations from the empirical equation of air refractive indices were similar, with a standard deviation of 2.0×10-9 throughout the 2 h continuous measurement period. By applying the multi-color method, correction of the air refractive index with an uncertainty of 3.5×10-7 was achieved.