Device and method for calibrating temperature of fiber bragg grating temperature sensor in low-temperature environment

Abstract

A device and method for calibrating the temperature of a fiber bragg grating temperature sensor in a low-temperature environment are provided. The calibration device comprises a cylinder body, a coverplate, an isothermal block, a lead pipe, a heating block and a calibration module. The upper end of the cylinder body has an opening. The lower end of the cylinder body is closed. A low-temperature medium is disposed in the cylinder body. The cover plate is installed at the upper end of the cylinder body and is provided with a liquid inlet for injecting the low-temperature medium, an exhaust portand a vacuum port. The isothermal block is immersed in the low-temperature medium. The isotherm on the isothermal block is provided with a platinum resistor and a plurality of fiber bragg gratings. The fiber bragg grating are connected in series via optical fibers. The lead pipe extends through the cover plate into the cylinder body. The fiber bragg gratings extend out of cylinder body via the lead pipe by the optical fibers. The platinum resistor extends out of cylinder body via the lead pipe by a signal line. The heating block is disposed on the outer wall of the lead pipe. A heating blockpower line is also arranged in the lead pipe. The calibration module is connected with the optical fibers outside the cylinder body and the signal line of the platinum resistor, and obtains the temperature of the platinum resistor and the temperature of respective fiber bragg gratings according to an obtained signal.

Description

technical field [0001] The invention relates to the field of optical fiber technology, in particular to a temperature calibration device and calibration method for an optical fiber grating temperature sensor in a low temperature environment. Background technique [0002] In the field of high-temperature superconducting power, due to strong electromagnetic interference, temperature sensors such as Pt platinum resistors and thermocouples have insufficient measurement accuracy in measuring liquid nitrogen temperature. Fiber Bragg grating sensors, as passive sensors, transmit temperature signals through light and are not subject to electromagnetic interference. At the same time, it has the characteristics of corrosion resistance, small size, light weight, and high measurement accuracy. It is widely used in the normal temperature environment, but in the low temperature liquid nitrogen environment, due to the nonlinear relationship between the thermo-optic coefficient, thermal expa...

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Problems solved by technology

[0004] (1) For the sensitized fiber grating, if the temperature value is directly derived from the theoretical formula without reference calibration, it will lead to large errors in actual use;

[0005] (2) In the process of fiber grating calibration, it needs to go through many times of heating and cooling in the liquid nitrogen temperature zone. Only one fiber grating sensor is calibrated at a time, and the efficiency is low

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