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Optical fibre fourier transformation white light interferometric method

A Fourier transform and inverse Fourier transform technology, applied in the field of fiber Fourier transform white light interferometry, can solve problems such as low accuracy, and achieve the effect of improving measurement accuracy

Active Publication Date: 2008-04-09
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

[0004] The purpose of the present invention is to provide a high-precision optical fiber Fourier transform white light interferometry method for the problem of low accuracy of the Fourier transform peak frequency measurement method

Method used

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  • Optical fibre fourier transformation white light interferometric method
  • Optical fibre fourier transformation white light interferometric method
  • Optical fibre fourier transformation white light interferometric method

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Embodiment Construction

[0042] specific implementation plan

[0043] The present invention will be further described below in conjunction with drawings and embodiments.

[0044] Fig. 1 is an embodiment figure of the inventive method, and the cavity length measurement of the external cavity type French-Pau interference type (EFPI) optical fiber sensor is explained to the inventive method; The measurement method of the present invention has been verified by experiment, referring to Fig. 2~ 5.

[0045] The light emitted by the broadband light source 1 is input to the fiber tunable F-P filter 3 through the optical isolator 2, and the fiber-tunable F-P filter 3 is driven by the sawtooth wave generator 10 to output the wavelength-scanning narrow-band light, and the wavelength-scanning narrow-band light is The fiber coupler 4 is divided into two paths, one of which passes through the etalon 5 and the fiber grating 6, and the photodetector 8 detects the transmission spectrum of the etalon 5 and the fiber gr...

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Abstract

An optical fiber Fourier measurement with switching white light interferometer implements Fourier transforms on white light spectrum output from transducer interferometer, the carrier frequency is Fourier spectrum defined by interferometer optical path difference, two sets of carrier frequency components are separated and symmetrical in the frequency space; one set of components is filtered for anti-Fourier transforms and plural logarithm operation, phase information of the transducer interferometer is set as an imaginary part of signals and separated from the background formed by lighting source spectrum outline and interference fringes contrast; the phase information of the transducer interferometer is limited within (minus Pi, Pi) according to operation procedure, the 2 Pi phases polarize of phase information is phase unwrapped, the measuring range is not limited with the 2 Pi phase; absolute optical path difference of transducer interferometer is calculated from phase information, thus realizing testing. The method of the invention prominently increases accuracy of white light spectrum peak measuring method and Fourier peak value frequency switching method.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber Fourier transform white light interferometry method. Background technique [0002] Interferometric fiber optic sensors, such as Fabry-Perot (Fabry-Perot), Mach-Zehnder (Mach-Zehnder), Michelson (Michelson, Sagnac), have high measurement Sensitivity, widely used. To be measured, such as strain, temperature, displacement or pressure, etc., act on the sensing interferometer, causing the change of the optical path difference of the interferometer, and demodulating the optical path difference from the output interference signal of the interferometer, so as to realize the measurement of the measured physical quantity Measurement. [0003] White light interferometry (WLI) utilizes a broadband light source or a wavelength-scanning light source to detect the output white light spectrum of a sensing interferometer to perform absolute measurements of the opt...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01J3/28G01J3/45G01J3/26G01J9/02G01D5/353
Inventor 江毅唐才杰
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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