Open AccessHigh-accuracy measurement system for the refractive index of air based on a simple double-beam interferometry
Author(s) -
Hongtang Gao,
Zhongyu Wang,
Wei Zou,
Yuzhang Liu,
Shoujin Sun
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.413252
Subject(s) - optics , refractive index , interferometry , observational error , optical path , system of measurement , interference (communication) , accuracy and precision , measurement uncertainty , optical path length , materials science , physics , computer science , mathematics , telecommunications , channel (broadcasting) , statistics , quantum mechanics , astronomy
A measurement system based on a simple double-beam interferometry is built to realize the measurement of air refractive index with high accuracy. The basic principle of the system is that, through measuring the change of optical path difference caused by rapid and smooth vacuumization, measurement of refractive index of air is converted to length measurement. Error correction and signal processing are studied to ensure high-accuracy measurement of the refractive index of air. Three applicable methods are used in system. The system based on the methods realize the subdivision and counting of interference fringe by software with three-error correction, error compensation for the end-window plates' thickness change caused by vacuumization, steady realization of high vacuum conditions. To verify the accuracy and reliability of the system, the measurement results are compared with that obtained from the method based on empirical Edlén's formula. Analysis result shows that the expanded measurement uncertainty of the system is U = 5×10 -9 , with k = 2. The system can be used to compensate the laser wavelength error caused by the refractive index of air with high accuracy.