Measurement and Compensation of Nonlinearity in Homodyne Interferometer

Homodyne 간섭계에서의 비선형성 측정과 보정

  • 김종윤 (충북대학교 대학원 정밀기계공학과) ;
  • 엄태봉 (한국표준과학연구원) ;
  • 정규원 (충북대학교 기계공학부) ;
  • 최태영 (충남대학교 대학원 수학과) ;
  • 이건희 (충남대학교 대학원 수학과)
  • Published : 2001.09.01

Abstract

The nonlinearity of a laser interferometer usually ranges from sub-nanometer to several manometers. This nonlinearity, which has periodic characteristics, limits the accuracy of the interferometer at the sub-nanometer level. The nonlinearity error of the one-frequency homodyne interferometer with quadrature fringe detection results from a number of factors including polarization mixing by imperfect optical elements, unequal gain of photo detectors, lack of quadrature between two signals and misalignment. In this paper, we described a method for measuring and compensating the nonlinearity of homodyne interferometer using the elliptical fitting technique with least-square method. Experimental results demonstrate that $^\pm$3.5 nm nonlinearity can be reduced to $^\pm$0.2 nm level.

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References

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