All-metal packaged high-temperature resistant fiber bragg grating sensor and manufacture method thereof

Abstract

The invention provides an all-metal packaged high-temperature resistant fiber bragg grating sensor and a manufacture method thereof. Regenerated fiber bragg gratings obtained through high temperature annealing treatment are taken as sensitive elements, so that the gratings can not be erased even under high temperature; and the magnetron sputtering method capable of enabling fibers and metal to be bonded more satisfactorily is adopted to form a bonding layer and a conducting layer on the surface of the fibers. The method is carried out in a water-free environment and avoids coarsening, sensitization and other processes in chemical plating, so that little damage is caused to the fibers; after magnetron sputtering, a protection layer is formed through thickening by adopting the electroplating method, and the fibers are embedded into a flexible structure metal substrate by adopting the electroplating method, so that the all-metal package is realized; and no organic polymer material is used in the whole process, so that the application of the sensor under high temperature is ensured, the temperature sensitivity and the strain sensitivity are improved, at the same time, the strain transmission efficiency is also improved due to adoption of the flexible structure metal substrate, and the installation is convenient.

Description

technical field [0001] The invention relates to an all-metal packaged high temperature resistant optical fiber grating sensor and a manufacturing method thereof. Background technique [0002] Optical fiber sensor is a device that uses optical fiber as the medium to detect the change of light transmission characteristics due to changes in the environment (physical quantity, chemical quantity or biomass, etc.) of all or part of the optical fiber when light propagates in the optical fiber. Optical fiber sensors are widely used in various industries due to their small size, light weight, high precision and sensitivity, anti-electromagnetic interference, anti-radiation, corrosion resistance, fire prevention, explosion protection, and long life. [0003] The fiber grating sensor is a kind of fiber optic sensor, which belongs to the wavelength modulation fiber optic sensor. Fiber Bragg Grating sensors obtain sensing information through wavelength modulation caused by changes in th...

AI Technical Summary

Problems solved by technology

[0009] (1) For ordinary fiber gratings, the reflectivity of the grating begins to decay when it exceeds 200°C, and it will be completely "erased" at around 680°C, so ordinary fiber grating sensors can only be used below 200°C;

[0010] (2) In the preparation of fiber gratings, the organic coating layer on the surface of the fiber is usually stripped, exposing the fiber to a humid environment, and it is susceptible to mechanical damage that leads to cracks on the surface, which greatly reduces the strength of the fiber, so in Grating must be overcoated after writing for encapsulation protection

When the temperature is higher than 400°C, the polymer material is completely decomposed, so that the optical fiber loses its protection in the harsh environment, and is susceptible to heat-mechanical loads, causing cracks to initiate on the surface and slowly expand over time, resulting in a decrease in the strength of the optical fiber and eventually leading to breakage, which is difficult to achieve. Long-term monitoring of high-temperature equipment

[0011] (3) The existing fiber grating sensor and the measured component are mostly connected by organic adhesives, which will cause redundancy in the measurement, low strain transfer efficiency, poor linearity and repeatability, The long-term reliability is poor, and the aging of the organic adhesive is accelerated as the temperature rises. When the temperature exceeds 250°C, most of the organic adhesives begin to soften or even decompose, and the connection between the sensor and the high-temperature measured component cannot be realized

[0012] (4) Since the main component of the optical fiber is quartz (SiO 2 ), its thermal-optic coefficient and thermal expansion coefficient are relatively small, making the temperature sensitivity of unpackaged fiber grating sensors low

Casting and laser cladding methods have more restrictions on the cladding metal. Low melting point metals are difficult to meet high temperature application requirements. The melting temperature of high melting point metals is too high, which is easy to damage the fiber grating. At the same time, it will generate a lot of thermal stress, which will easily lead to fiber breakage. And these two kinds of methods all can't guarantee to obtain the metal coating layer of uniform thickness along the axial direction on the fiber grating surface, thus can produce polarization phenomenon and influence spectral quality; A metallized packaging structure and method for optical fiber sensitive components, a Chinese patent application number 200510020086.5 discloses a wet chemical metallization process on the surface of quartz fiber gratings, and a Chinese patent application number 201010504623.4 discloses an electroless plating on the surface of quartz optical fibers and a method combining chemical plating and electroplating, such as a metal-coated optical fiber disclosed in Chinese Patent Application No. 02816378.8 and a metal-coated optical fiber disclosed in Chinese Patent Application No. 03804115.4, obtained by chemical plating The combination between the coating and the optical fiber is poor, and the uniformity of the coating is poor, which is difficult to meet the needs of high-sensitivity sensors. Exposing the optical fiber to a plating solution containing water, acid, and alkaline corrosives will also greatly reduce the strength of the optical fiber; Coating is difficult to make, and the material of the crucible used for evaporating substances will also evaporate and become impurities in the coating, and the coating obtained by evaporation is too thin, which is neither enough to protect the optical fiber nor transmit the strain of the measured component

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