FBG (fiber bragg grating) interrogator

Abstract

The invention relates to an FBG interrogator which is characterized by comprising a scanning light source (1), a coupler (2) with a splitting ratio of 99 :1, a PLC (programmable logic controller) shunt module (3), a plurality of 3dB couplers (4), a FBG array (6), a reference light path (7), a data collection module (12), a main control panel (13), an industrial personal computer (17) and a display (18), wherein the reference light path (7) comprises a first reference optical grating (8), a second reference optical grating (9), a third reference optical grating (10) and a temperature sensor; the temperature sensor is connected with the main control panel; the wave length lambada 2 of the first reference optical grating (8) and the wave length lambada 3 of the second reference optical grating (9) are close to one end of the wave length of a system; the wave length lambada 4 of the third reference optical grating (10) is close to the other end of the wave length of the system; and the proportion of the difference between the lambada 4 and the lambada 3 and the difference between the lambada 3 and the lambada 2 ranges between 4 : 1 and 7 :1. Compared with the prior art, a costly FP etalon is replaced with three simple reference gratings and one temperature sensor, and the gratings and the temperature sensor form the reference light path, so that creep deformation of the scanning light source and influence on the demodulation accuracy which is caused by the change of the output wave length of the light source due to hysteresis and drift are eliminated very effectively.

Description

technical field [0001] The invention relates to a fiber grating demodulator. Background technique [0002] In recent years, temperature and pressure sensor measurement systems based on fiber gratings have been widely used in the fields of electric energy, petrochemical industry, rail transit, tunnels and bridges, and become a bright spot of economic growth. Related technologies have also become a hot research topic. Fiber Bragg grating measurement technology can realize long-distance real-time measurement and monitoring, and has the characteristics of wide measurement range, high precision and high stability, especially in strong electromagnetic interference occasions or explosion-proof occasions. [0003] Traditionally, fiber grating demodulation technology uses spectrometers, color filters and wavelength meters, but these demodulation systems have disadvantages such as high price and large volume, which are not suitable for engineering applications. For this reason, many ...

AI Technical Summary

Problems solved by technology

The traditional method is to use FP etalons with good thermal stability to realize the reference optical path, but FP etalons are expensive and only suitable for laboratory principle verification, not suitable for practical engineering applications

At the same time, in multi-channel applications, because the number and spacing of gratings in each channel are different, the signal size reflected by the gratings is different. How to make the grating signal detection circuit universal and compatible to meet the requirements of different channels is also demodulation The content of the program needs to be studied. At present, there is no good solution from the published prior art.

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