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

Area of Science:

• Optics
• Metrology
• Atmospheric Science

Background:

• Accurate measurement of the air refractive index is crucial for long-distance optical metrology.
• Environmental factors like humidity and temperature significantly affect air refractive index, complicating precise measurements.
• Existing methods often struggle with real-time correction in dynamic atmospheric conditions.

Purpose of the Study:

• To develop a novel multi-color method for self-correction of the air refractive index.
• To enable precise long-distance measurements in challenging environments, such as moist air.
• To improve the accuracy and reliability of interferometric measurements affected by atmospheric variations.

Main Methods:

• Utilizing dispersive interferometry of an optical frequency comb to obtain simultaneous optical path lengths at multiple wavelengths.
• Comparing interferometric measurements with calculations based on empirical air refractive index equations.
• Implementing a self-correction algorithm based on multi-wavelength data.

Main Results:

• Achieved high precision in optical length measurements with a standard deviation of 2.0×10^-9 over 2 hours.
• Demonstrated successful correction of the air refractive index.
• Attained a final correction uncertainty of 3.5×10^-7.

Conclusions:

• The proposed multi-color method offers a robust solution for real-time air refractive index self-correction.
• This technique significantly enhances the accuracy of long-distance interferometric measurements in moist air.
• The method shows potential for various applications in precision metrology and atmospheric monitoring.