Group-phase refractive index method for improving the accuracy in two-color interferometric length measurements

Zeng, Lijiang; Matsumoto, Hirokazu; Seta, Katuo

doi:10.1063/1.1149850

Cited by 1 publication

(1 citation statement)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The key point is to obtain a proper synthetic wavelength by combining two or more individual wavelengths [5,6]. The method is normally applied in length measurement [7][8][9], and some researchers have applied it in air refractive index measurement [10,11]. However, many practical applications of synthetic wavelength principle are limited, for the number of laser wavelengths meeting corresponding requests is fixed especially for measuring lasers that need good qualities of frequency stabilization and beam mode.…”

Section: Introductionmentioning

confidence: 99%

Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths

et al. 2012

View full text Add to dashboard Cite

A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited.

show abstract