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Fast low-coherence interference demodulation method based on position related dispersion characteristics

A technology with low-coherence interference and dispersion characteristics, applied in the field of fast low-coherence interference demodulation, can solve problems such as step errors and interference order misjudgments, and achieve the effects of high accuracy, speed improvement, and simple calculation

Inactive Publication Date: 2014-04-30
TIANJIN UNIV
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Problems solved by technology

This will lead to the inconsistency between the peak information and the phase information of the low-coherence interference fringe envelope, when the inconsistency is greater than , it will lead to misjudgment of the level of interference, resulting in a step error

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  • Fast low-coherence interference demodulation method based on position related dispersion characteristics
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  • Fast low-coherence interference demodulation method based on position related dispersion characteristics

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Embodiment

[0044] figure 1 It is a diagram of the low-coherence interference demodulation device based on the position-dependent dispersion characteristic involved in the method of the present invention, and the working process is described in combination with the measurement of the external atmospheric pressure. The demodulation method of the present invention has been verified by experiment, see Figure 2 to Figure 6 .

[0045] Such as figure 1 As shown, the light emitted by the broadband light source (LED) 1 reaches the F-P sensor 3 through the coupler 2. The F-P sensor 3 is a sensitive element that senses the external atmospheric pressure. The two reflective surfaces of the F-P cavity constitute a sensing interferometer. The distance between the two reflecting surfaces of the F-P cavity in the interferometer has a linear relationship with the atmospheric pressure. The optical signal modulated by the F-P sensor 3 is derived from the outlet of the coupler 2 and enters the demodulat...

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Abstract

A fast low-coherence interference demodulation method based on position related dispersion characteristics belongs to the field of optical fiber sensing, particularly relates to the measurement of atmospheric pressure and is also suitable for three-dimensional shape detection, optical coherence tomography technologies and other measurement fields. The fast low-coherence interference demodulation method based on the position related dispersion characteristics comprises the steps that based on a low-coherence interference technology, an F-P sensor is used as a sensing interferometer, the atmospheric pressure is sensed through changes of cavity lengths, a demodulation interferometer formed by a polarizer, a double-refraction optical wedge and an analyzer is used for carrying out demodulation on optical signals modulated by the F-P sensor, and space low-coherence interference fringes are formed in a local area of zero optical path difference. According to the fast low-coherence interference demodulation method based on the position related dispersion characteristics, the position of an envelop peak value is obtained by adopting a low-precision centroid method, the position of the peak value of a central fringe of central wavelength interference fringes and the level of the central fringe are obtained through calculation according to system position related dispersion characteristics and a phase shift method, in this way, the accurate position of the peak value of a zero-level fringe of the central wavelength interference fringes is restored, and thus fast high-precision demodulation on distances is achieved.

Description

technical field [0001] The invention relates to a fast low-coherence interference demodulation method based on position-related dispersion characteristics, belonging to the field of optical fiber sensing. Background technique [0002] Phase-shifting method and low-coherence interferometry are two important distance measurement methods in the field of optical interference, which are widely used in the fields of three-dimensional shape detection, optical coherence tomography and optical fiber sensing, such as pressure and refractive index measurement. The phase shift method has the characteristics of high precision and fast processing speed, but due to the problem of phase ambiguity, its measurement range is limited to Inside, therefore, are commonly used for smooth surface measurements. The low-coherence interferometry can overcome the phase ambiguity problem in the phase-shift method, and theoretically there is no limit to the measurement range. However, the shape of low...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D5/26G02F2/00
Inventor 刘铁根江俊峰王双刘琨尹金德石俊锋吴振海张学智
Owner TIANJIN UNIV
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