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Automatic real-time compensation of wavelength of heterodyne interferometer
Author(s): Wei Jin; Qi Li; Yushu Shi; Sitian Gao; Wei Li; Shi Li
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Paper Abstract

Heterodyne interferometer is a nanometer measurement system that uses the laser wavelength as the working reference for length measurement. Under ideal conditions, the laser wavelength is the wavelength λ0 of the light wave in the vacuum, but in practical applications, the laser wavelength will change with the influence of the air refractive index and the refractive index of air is greatly affected by the environment. This will have a great influence on the measurement results of the high-precision and high-resolution nano-displacement measurement system. Therefore, it is necessary to correct the air refractive index to compensate the laser wavelength. In this paper, the air refractive index in the initial measurement is obtained by using the Edlen empirical formula. Then the relationship between the current air refractive index and the initial air refractive index is obtained by using the wavelength compensation unit to achieve the automatic real-time compensation of the wavelength. The wavelength compensation component is mainly composed of an interference mirror and a fixed length etalon. Through the measurement of air refractive index and the experiment of compensation, the feasibility of the method is confirmed. The relative error after wavelength compensation is less than 0.03% relative to the relative error before compensation.

Paper Details

Date Published: 7 March 2019
PDF: 8 pages
Proc. SPIE 11053, Tenth International Symposium on Precision Engineering Measurements and Instrumentation, 110533G (7 March 2019); doi: 10.1117/12.2512162
Show Author Affiliations
Wei Jin, China Jiliang Univ. (China)
Qi Li, National Institute of Metrology (China)
Yushu Shi, National Institute of Metrology (China)
Sitian Gao, National Institute of Metrology (China)
Wei Li, National Institute of Metrology (China)
Shi Li, National Institute of Metrology (China)


Published in SPIE Proceedings Vol. 11053:
Tenth International Symposium on Precision Engineering Measurements and Instrumentation
Jiubin Tan; Jie Lin, Editor(s)

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