Optical fiber temperature sensor packaged by diamond casing and resistant to seawater erosion

Abstract

An optical fiber temperature sensor packaged by a diamond casing and resistant to seawater erosion comprises a long-period optical fiber grating which is packaged by a diamond casing, a cylindrical shell which is hollowed out inside, and a tensile structure which can provide constant tension. The tensile structure is composed of an optical fiber fixing cap, a spring, and a diamond casing fixing cap. According to the long-period optical fiber grating temperature sensor prepared by a diamond casing-based packaging method, corrosion and erosion to the long-period optical fiber grating caused by direct contact with seawater is prevented, the temperature change of outside seawater can be sensed quickly, and the underwater survival ability of the long-period optical fiber grating temperature sensor is increased greatly.

Description

technical field [0001] The invention relates to an optical fiber temperature sensor, in particular to an optical fiber temperature sensor encapsulated in a diamond sleeve and capable of resisting seawater erosion. Background technique [0002] Compared with traditional electromagnetic sensing technology, optical fiber sensing technology has the advantages of anti-electromagnetic interference, intrinsic insulation, reusability and low transmission loss. It plays an increasingly important role in national defense and civilian fields, and is listed by many countries. A new type of sensing technology that focuses on development. The fiber grating sensor is a sensor that uses the principle that the central wavelength of the fiber grating has a certain functional relationship with the external environmental parameters, and obtains the external environmental parameters by detecting the change of the wavelength. According to the size of the period, it can be divided into fiber Brag...

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Problems solved by technology

However, in the long-term ocean temperature measurement, it is found that if the fiber optic temperature sensors are "directly exposed to seawater" or "be exposed to seawater after simple packaging", they will still fail quickly

The inventor studied the mechanism of seawater erosion of optical fiber in the paper (Wavelengththevolutionoflong-periodfibergratingsinawaterenvironment, AppliedOptics, 52(11):2478-2483.), and found that the main reason is that seawater penetrates into the optical fiber material, causing the effective refraction of the long-period fiber grating core and cladding. The rate changes accordingly, causing the zero point of the sensor to drift and fail; at the same time, the tensile structure is also vulnerable to corrosion by infiltration of seawater and fails.

Without special protective measures, fiber optic sensors will not be able to work effectively in seawater for a long time

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