Low coherent interference demodulation method based on chromatic dispersion characteristic and envelopment peak value

Abstract

The invention discloses a low coherent interference demodulation method based on a chromatic dispersion characteristic and an envelopment peak value. According to the method, an F-p sensor is chosen to serve as a sensing element, a double refraction optical wedge serves as an optical path difference space scanning element, an interference fringe is formed in a zero optical path difference local area, an F-P cavity length is demodulated according to the interference fringe, and therefore atmospheric pressure is felt. According to the method, firstly, Fourier filtering is carried out on an interference signal; then a low precision distance corresponding to a peak value position according to a peak value position obtained by the envelopment peak value method and a cluster refractive index of a low coherent interference system dispersion element is obtained; finally, a theoretical phase position is calculated by the utilization of the peak value position chromatic dispersion characteristic, and the distance error of the envelopment peak value method is determined according to the theoretical phase position and a measured phase position and high-precision demodulation is achieved. Under the condition that prior information is not needed, the system chromatic dispersion characteristic and the envelopment peak value are utilized to achieve wide-range high-precision measurement of low coherent interference. The low coherent interference demodulation method is applied to the optical fiber sensing filed, the three-dimensional shape detecting and optical chromatographic technique, and other distance measurement fields.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a low-coherence interference demodulation method based on dispersion characteristics and envelope peaks. Background technique [0002] Because low-coherence interferometry can effectively measure distance, it is widely used in three-dimensional shape measurement, low-coherence tomography technology, and all physical quantities that can be converted into distance information, such as temperature, strain, and pressure measurement. Low-coherence interference does not have the phase ambiguity problem in laser interference, so its measurement range is not limited to λ / 4, the measurement range is theoretically unlimited, and the measurement accuracy is high. [0003] Low-coherence interferometric demodulation methods include two methods based on interference pattern displacement and phase information: methods based on interference pattern displacement include envelope peak method a...

AI Technical Summary

Problems solved by technology

[0004] However, since low-coherence interferometric systems use broadband light sources, all demodulation methods are affected by dispersion, which can cause envelope peak offset errors, as well as phase offset errors, which will distort the demodulation results, and in severe cases, step sexual error

Generally speaking, eliminating or reducing the dispersion effect as much as possible on the system hardware settings or compensating the system dispersion error through prior information through software algorithms can reduce the error caused by the dispersion factor to a certain extent, but cannot completely eliminate it.

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