KR20170064605A - manufacturing apparatus for radiation tolerant FBG sensor and manufacturing method using thereof - Google Patents

manufacturing apparatus for radiation tolerant FBG sensor and manufacturing method using thereof Download PDF

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KR20170064605A
KR20170064605A KR1020150169938A KR20150169938A KR20170064605A KR 20170064605 A KR20170064605 A KR 20170064605A KR 1020150169938 A KR1020150169938 A KR 1020150169938A KR 20150169938 A KR20150169938 A KR 20150169938A KR 20170064605 A KR20170064605 A KR 20170064605A
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optical fiber
hydrogen
radiation
chamber
manufacturing
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KR1020150169938A
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Korean (ko)
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김종열
이남호
정현규
이금석
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한국원자력연구원
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
    • G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02123—Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

An apparatus for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention includes a chamber for providing a sealed space in which an optical fiber is accommodated, a hydrogen injecting means for injecting hydrogen at a predetermined pressure into a chamber accommodating the optical fiber, And a UV laser irradiation means for forming a grating on the optical fiber by irradiating a UV laser onto the hydrogen-added optical fiber in the chamber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a manufacturing apparatus for a radiation-induced optical fiber grating sensor,

The present invention relates to an apparatus for manufacturing an internal radiation optical fiber grating sensor and a manufacturing method using the same, and more particularly, to an apparatus for manufacturing an internal radiation optical fiber grating sensor capable of minimizing radiation effects by optimizing hydrogen loading conditions and UV laser irradiation conditions And a manufacturing method thereof.

Radiation-resistant optical fiber is a special optical fiber with radiation-resistant properties with minimal or no optical loss and optical fiber damage in a radiation environment.

In recent years, the generation of nuclear power generation facilities has been increasing due to the rapid population growth worldwide and the increase in energy demand due to the industrialization of developing countries. In this situation, it is necessary to continuously monitor the temperature of nuclear facilities such as nuclear reactor pressure vessel, cooler, etc. in order to judge the safety situation of nuclear power generation facilities in real time and to take appropriate action. Thermocouple, thermistor, or radiation temperature sensor, which is a thermocouple temperature sensor operating at high temperature, is used for temperature measurement of nuclear facilities, but temperature sensor sensitivity, corrosion resistance, sensor probe damage, and drift And a drift phenomenon. Therefore, a sensor technology using an optical fiber is attracting attention.

Fiber Bragg grating (FBG) is an alternative to conventional electrical and mechanical sensors. It is a sensor technology using fiber Bragg grating (FBG) in optical fiber. It has high accuracy, small size, electromagnetic interference (EMI) Performance and so on. Studies on the radiation effects of FBG have shown that they are resistant to radiation and have suitable properties as temperature sensors in nuclear reactors and space environments.

This FBG has a characteristic of reflecting only the wavelength satisfying the Bragg condition of the following equation (1), and transmitting the other wavelengths as it is.

[Equation 1]

λ B = 2n eff Λ

In Equation (1),? B is the Bragg wavelength, neff is the effective refractive index, and? Is the interval between the gratings. Equation (2) can be obtained by applying the temperature variable (T) to Equation (1).

&Quot; (2) "

λ B (T) = λ B (T 0) + α 0 (TT 0)

In the equation 2, λ B (T 0) indicates the reference temperature (T 0) Bragg wavelength, α 0 is the temperature sensitivity (temperature sensitivity) in.

Generally, the temperature sensitivity coefficient (α 0 = dλ / dT) of the FBG is about 10 pm / ° C at a wavelength of 1,550 nm when T = T 0 .

However, in order to apply the FBG temperature sensor to the radiation environment, the radiation dependence of the range of λ B (T 0 ) changed by radiation and the temperature sensitivity coefficient should be considered. The radiation sensitivity of the FBG is greatly influenced by the chemical composition of the optical fiber and the lattice fabrication techniques such as hydrogen loading and laser conditions.

Therefore, when the FBG sensor is exposed to the radiation environment, the movement of the Bragg wavelength (λ B ) and the change of the temperature sensitivity coefficient (α 0 ) occur, and the reliability of the sensor measurement becomes poor. In particular, the OH-bonds inside the optical fiber generated by hydrogen loading during the FBG process can increase the radiation sensitivity of the lattice due to the radiolysis. Also, since the laser process can damage the optical fiber in the lattice process, it can affect the damage caused by the radiation.

Meanwhile, during the FBG process, a depletion of GeO defects (Oxygen deficient germanium) existing in the optical fiber core region may include a photo-sensitization improvement process in which the bonds are broken by UV laser irradiation to generate GeE to cause a refractive index change.

Korean Patent Registration No. 10-1465156

An apparatus for manufacturing an internal radiation optical fiber grating sensor and a manufacturing method therefor according to an embodiment of the present invention aim to solve the above-mentioned problems.

Manufacture of radiation-induced optical fiber grating sensor capable of minimizing radiation effects by accelerating the generation of Ge defect by accelerating the generation of optical sensitivity by adding hydrogen to the optical fiber (hydrogen loading) and optimizing hydrogen loading condition and UV laser irradiation condition And a manufacturing method using the same.

The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

The apparatus for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention includes a chamber for providing a sealed space in which an optical fiber is accommodated, a hydrogen injecting means for injecting hydrogen at a certain pressure into a chamber in which the optical fiber is accommodated, Sensing means for confirming the amount of hydrogen injected into the chamber, and UV laser irradiation means for forming a grating on the optical fiber by irradiating a UV laser onto the hydrogen-added optical fiber in the chamber.

The apparatus further includes a heat treatment means for receiving the optical fiber, which has been irradiated with the UV laser, into the inner space and performing the heat treatment.

The sensing means includes an FBG sensor and monitoring means for monitoring a Bragg wavelength change of the FBG sensor according to a hydrogen injection amount.

The monitoring means may be provided as an OSI (Optical Sensing Interrogator).

A manufacturing method using an apparatus for manufacturing a radiation-induced optical fiber grating sensor according to an embodiment of the present invention includes placing an optical fiber in a chamber, injecting hydrogen through the hydrogen injecting means at a pressure of 100 atm for 110 to 130 hours, A second step of removing the optical fiber from the chamber and irradiating the UV laser for 60 to 80 seconds at an intensity of 24 to 26 mJ / cm 2 through the UV laser irradiation unit to form a grating on the optical fiber; .

The method further includes a third step of performing heat treatment for 20 to 30 hours at a temperature of 80 to 100 ° C through the heat treatment unit of the optical fiber on which the second step has been performed.

An apparatus for manufacturing a radiation-resistant optical fiber grating sensor according to an embodiment of the present invention and a method for manufacturing a radiation-resistant optical fiber grating sensor using the same include a method of adding hydrogen to an optical fiber (hydrogen loading) And further, the hydrogen loading conditions and the UV laser irradiation conditions are optimized to minimize the influence of radiation.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a configuration of a chamber and hydrogen injection means in an apparatus for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention; FIG.
FIG. 2 is a view showing a schematic configuration of a UV laser irradiation means in an apparatus for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention.
FIG. 3 is a view showing a schematic configuration of a heat treatment means in an apparatus for manufacturing an internal radiation optical fiber grating sensor according to another embodiment of the present invention.
FIG. 4 is a flowchart of a method of manufacturing a radiation ray grating sensor according to an embodiment of the present invention.
FIG. 5 is a schematic view showing a state in which an FBG sensor is installed in a gamma-ray irradiation facility in order to test the radiation effect of the FBG sensor.
6 is a graph showing the radiation effects of the FBG sensors fabricated by setting the hydrogen loading times to 72 hours, 120 hours, 168 hours, and 240 hours.
FIG. 7 is a graph showing the radiation effects of the FBG sensors fabricated by setting the hydrogen loading times to 72 hours, 120 hours, and 168 hours.
8 is a graph showing the radiation effects of the FBG sensors fabricated by setting the hydrogen loading condition to 72 hours and varying the UV laser exposure conditions.
9 is a graph showing the radiation effects of the FBG sensors fabricated by setting the hydrogen loading condition to 120 hours and varying the UV laser exposure conditions.
10 is a graph showing the radiation effects of the FBG sensors fabricated by setting the annealing time at 24 hours, and setting the annealing temperature conditions at 100 ° C, 150 ° C, and 200 ° C.
11 is a graph comparing internal radiation of a conventional FBG sensor and an FBG sensor manufactured by the manufacturing method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

FIG. 1 is a view showing a schematic configuration of a chamber and hydrogen injecting means in an apparatus for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention. FIG. 2 is a cross- 1 is a diagram showing a schematic configuration of a UV laser irradiation means in a manufacturing apparatus.

The apparatus for fabricating an optical fiber grating sensor according to an embodiment of the present invention includes a chamber 110, a hydrogen injection unit 120, a sensing unit 130, and a UV laser irradiation unit 140.

The fiber grating sensor manufactured by the present invention can be used in a radiation environment, can be used in an extreme environment having high temperature and high pressure conditions, and can detect temperature, pressure, acceleration, displacement and the like.

First, the chamber 110 provides a closed space 111 in which the optical fiber 10 is accommodated. When the optical fiber 10 is injected into the chamber 110, hydrogen is injected.

The hydrogen injecting means 120 injects hydrogen into the chamber 110 containing the optical fiber 10 at a constant pressure to add hydrogen to the optical fiber 10. Hydrogen is stored in the hydrogen injecting means 120 and a valve 121 or a pressure gauge may be disposed on the flow path connecting the hydrogen injecting means 120 and the chamber 110. The amount of hydrogen injected into the chamber 110 can be adjusted by the configuration of the valve 121, and the injection pressure can be checked through the pressure gauge.

The sensing means 130 is provided to confirm the amount of hydrogen injected into the chamber 110.

Generally, the Bragg wavelength is shifted to a short wavelength in proportion to the amount of hydrogen as the optical fiber 10 undergoes a diffusion process after the hydrogen loading process. Therefore, when the hydrogen content in the optical fiber 10 can not be accurately known, it is difficult to manufacture a sensor having a desired Bragg wavelength.

Accordingly, the apparatus for manufacturing an optical fiber grating sensor according to the present invention includes the sensing means 130 for calculating the amount of hydrogen contained in the optical fiber 10 during the hydrogen loading process.

The UV laser irradiation means 140 irradiates a UV laser to form a grating 11 on the optical fiber 10 when the optical fiber 10 hydrogenated in the chamber 110 comes out of the chamber 110. At this time, the optical fiber 10 is mounted on the stage 141 or the like.

FIG. 3 is a view showing a schematic configuration of a heat treatment means in an apparatus for manufacturing an internal radiation optical fiber grating sensor according to another embodiment of the present invention.

According to another embodiment of the present invention, the apparatus may include a heat treatment unit 150 for receiving the optical fiber 10, which has been irradiated with the UV laser through the UV laser irradiation unit 140, in the inner space and performing the heat treatment.

The heat treatment unit 150 includes a chamber 151 into which the optical fiber 10 is injected, a heater 152 that supplies heat to the inside of the chamber 151, a temperature sensor that measures the temperature of the chamber 151 . ≪ / RTI >

According to another embodiment of the present invention, the sensing means 130 includes a reference FBG sensor 131, monitoring means 132 for monitoring a Bragg wavelength change of the FBG sensor 131 according to the hydrogen injection amount, ). Therefore, it is possible to monitor the change of the Bragg wavelength of the FBG sensor 131 and confirm the amount of hydrogen addition through the Bragg wavelength change.

In the present embodiment, the monitoring means may be provided as an OSI (Optical Sensing Interrogator). OSI (Optical Sensing Interrogator), which is a type of measuring instrument, can calculate the hydrogen addition amount of the optical fiber 10 based on the change of the grating wavelength with the reference FBG sensor 131. The change of the lattice wavelength of the FBG sensor 131 is determined by the Bragg wavelength of the FBG sensor 131 before injecting hydrogen into the chamber 110 and the Bragg wavelength of the FBG sensor 131 after injecting hydrogen into the chamber 110. [ . ≪ / RTI >

4 is a flow chart of a method of fabricating an internal radiation optical fiber grating sensor according to an embodiment of the present invention.

The method for manufacturing an internal radiation optical fiber grating sensor according to an embodiment of the present invention uses the apparatus for manufacturing an internal radiation optical fiber grating sensor described above. The optical fiber 10 is inserted into a chamber 110, (S110) injecting hydrogen into the optical fiber 10 at a room temperature for 110 to 130 hours at a pressure of 100 atmospheres (atmospheric pressure), and an optical fiber 10 to which hydrogen is added in the chamber 110 A second step S120 of forming a grating 11 on the optical fiber 10 by irradiating a UV laser for 60 to 80 seconds at an intensity of 24 to 26 mJ / cm2 through the UV laser irradiation means 140, .

In the first step S110, the optical fiber 10 is placed in the chamber 110 and hydrogen is injected at a room temperature for 110 to 130 hours through the hydrogen injecting means 120 at 100 atm and injected into the optical fiber 10 Adding hydrogen.

≪ Example 1 >

The optical fiber 10 was put into the chamber 110 and hydrogen was injected at room temperature at 100 atm through the hydrogen injecting means 120. The hydrogen loading conditions were changed to 72 hours, 120 hours, 168 hours, 240 hours 9 different FBG sensors were fabricated.

Table 1 summarizes the characteristics of nine FBG sensors manufactured through the first embodiment.

FBG Grating fabrication parameters
Properties of FBGs Fiber Hydrogen loading UV laser intensity
[mJ / cm2] Wavelength
[nm] Reflectivity [%] Temperature sensitivity [pm / ° C] FWHM
[pm] A1
SMF-28e 3 days 33.6 1549.76 20.57 10.0 69 A2
SMF-28e 3 days 37.5 1549.77 22.38 10.0 60 B1
SMF-28e 5 days 33.8 1549.74 72.46 10.0 83 B2
SMF-28e 5 days 36.3 1549.79 74.89 10.0 92 C1
SMF-28e 7 days 31.3 1549.76 74.89 10.0 94 C2
SMF-28e 7 days 33.6 1549.78 80.05 10.0 103 D1
SMF-28e 10 days 31.7 1549.77 56.35 9.9 83 D2
SMF-28e 10 days 33.6 1549.75 73.70 9.9 88 D3
SMF-28e 10 days 37.5 1549.83 38.35 9.9 88

In addition, the FBG sensor fabricated in this way was irradiated with gamma rays to analyze the radiation effects.

FIG. 5 is a schematic view showing a state in which an FBG sensor is installed in a gamma-ray irradiation facility in order to test the radiation effect of the FBG sensor.

The results of the radiation test for the fabricated FBG sensor are summarized in the cumulative dose and dose rate procedure of the Procedure for Measuring Radiation-Induced Attenuation in Optical Fibers and Optical Cables (TIA / EIA Std. 455-64) 31.7 kGy, and the dose rate was 105 Gy / min.

The change in Bragg wavelength for temperature rise during irradiation was measured by measuring temperature variation in the irradiation facility through a temperature sensor (Thermocouple, K type) installed around the FBG sensor, and then calculating the temperature sensitivity coefficient of each FBG sensor.

6 is a graph showing the radiation effects of the FBG sensors fabricated by setting the hydrogen loading times to 72 hours, 120 hours, 168 hours, and 240 hours.

Referring to FIG. 6, the radiation sensitivity of the FBG sensor fabricated by setting different hydrogen loading conditions to 72 hours, 120 hours, 168 hours, and 240 hours is closely related to the hydrogen loading time. As the hydrogen loading time becomes longer, It can be confirmed that the sensitivity tends to increase.

≪ Example 2 >

An optical fiber 10 was placed in a chamber 110 and hydrogen was injected at room temperature under a pressure of 100 atm through the hydrogen injecting means 120. The hydrogen loading condition was set to 72 hours except for 240 hours when the radiation sensitivity was the highest , 120 hours, and 168 hours, respectively, and 13 FBG sensors were fabricated in a second order.

Table 2 summarizes the characteristics of the FBG sensors 13 fabricated through the second embodiment.

FBG Grating fabrication parameters
Properties of FBGs Fiber Hydrogen loading UV laser intensity
[mJ / cm2] Wavelength
[nm] Reflectivity [%] Temperature sensitivity [pm / ° C] FWHM
[pm] 3-3-1 SMF-28e 3 days 26.00 1540.29 55.3 10.6 110 3-3-2 SMF-28e 3 days 26.00 1541.43 61.3 10.8 110 3-1-3 SMF-28e 3 days 26.00 1542.65 67.0 10.7 110 3-2-1 SMF-28e 3 days 26.00 1545.23 65.3 10.7 110 3-2-4 SMF-28e 3 days 26.00 1548.71 61.0 10.7 110 5-2-1 SMF-28e 5 days 31.00 1550.13 68.5 10.7 110 5-3-2 SMF-28e 5 days 29.00 1551.31 79.3 10.5 110 5-3-3 SMF-28e 5 days 30.00 1552.51 81.5 10.7 100 5-3-4 SMF-28e 5 days 31.00 1553.63 81.0 10.7 120 7-2-1 SMF-28e 7 days 27.00 1530.70 79.3 10.1 140 7-2-2 SMF-28e 7 days 28.00 1531.76 73.8 10.1 110 7-2-3 SMF-28e 7 days 27.00 1532.92 67.0 10.1 120

FIG. 7 is a graph illustrating the influence of radiation on hydrogen loading conditions of a second-order FBG sensor with hydrogen loading conditions set at 72 hours, 120 hours, and 168 hours.

As can be seen from FIG. 7, the second-order FBG sensor also exhibited weaker radiation due to the increase of Bragg wavelength shift as the hydrogen loading time was longer. The hydrogen loading time satisfying the radiation characteristics was 3 ~ Five days were confirmed to be appropriate.

In the second step S120, the hydrogen-doped optical fiber 10 is taken out from the chamber 110 and is irradiated with ultraviolet rays through the UV laser irradiation means 140 for 60 to 80 seconds at an intensity of 24 to 26 mJ / And forming a grating 11 on the optical fiber 10.

In the step of irradiating the UV laser, if the optical fiber 10 is overexposure to the UV laser, the core and the cladding inside the optical fiber 10 are damaged, thereby increasing the sensitivity of the radiation. Therefore, when the UV laser condition is optimized, the radiation resistance characteristics can be improved.

≪ Example 3 >

Eight FBG sensors were fabricated by changing the hydrogen loading conditions of the optical fiber to 72 hours and 120 hours, respectively, and changing the UV laser exposure time to 30 seconds, 60 seconds, 90 seconds, and 120 seconds.

Table 3 summarizes the characteristics of eight FBG sensors manufactured through the third embodiment.

FBG Grating fabrication parameters
Properties of FBGs H2
loading UV Laser condition
Wavelength
[nm] Reflectivity [%] Temperature sensitivity [pm / ° C] FWHM
[pm] Intensity
[mJ / cm2] Repetition
Rate
[Hz] Irradiation
Time
[sec] 3-30-1 3 days 26.00 10 30 1520.84 6.8 10.3 100 3-61-1 3 days 26.00 10 60 1525.66 29.3 10.4 090 3-90-1 3 days 26.00 10 90 1521.11 49.8 10.2 100 3-120-1 3 days 26.00 10 120 1523.50 77.8 10.2 130 5-30-1 5 days 26.00 10 30 1518.30 41.3 10.2 100 5-61-1 5 days 26.00 10 60 1528.12 58.3 10.2 100 5-91-1 5 days 26.00 10 90 1528.27 83.5 10.2 130 5-120-1 5 days 25.55 10 120 1523.39 79.0 10.2 140

In addition, the effects of radiation on the FBG sensors were evaluated under the conditions of total cumulative dose of 34.3 kGy and dose rate of 115 Gy / min.

FIG. 8 is a graph showing a radiation effect of an FBG sensor manufactured by varying UV laser exposure conditions under a hydrogen loading condition of 3 days, FIG. 9 is a graph showing the influence of UV laser exposure conditions under a hydrogen loading condition of 3 days, Fig. 3 is a graph showing the radiation effect of the FBG sensor. Fig.

Referring to FIGS. 8 to 9, the FBG sensor fabricated by changing the UV laser exposure condition tends to have an increased radiation sensitivity as the UV laser exposure time becomes longer. In particular, when the exposure time of the UV laser is more than 90 seconds based on the laser output 26 mJ / cm 2, it is confirmed that the fWHM is formed by more than 100 pm due to the laser overexposure and the resolution is decreased.

In addition, when the hydrogen loading time is 3 days or less and the UV laser exposure time irradiation time is 30 seconds, the reflectance is less than 10%, and sensor measurement may be difficult.

Therefore, the process conditions satisfying the radiation characteristics and basic characteristics of the FBG sensor are hydrogen loading time of 110-130 hours, UV laser irradiation intensity of 24-26 mJ / cm 2, repetition rate of 10 Hz, As shown in Fig.

For reference, the design conditions of the radiation-induced FBG sensor can be as shown in Table 4.

Properties of radiation hard FBGs
Wavelength, λB
[nm] Reflectivity
[%] Temperature sensitivity
[pm / ° C] FWHM
[pm] BWS, ΔλB
[pm] 1510-1550 > 50 10.0 ± 0.5 90-100 <15 pm
@> 10kGy

According to another embodiment of the present invention, the optical fiber 10 subjected to the second step (S120) is subjected to a heat treatment at a temperature of 80 to 100 ° C. for 20 to 30 hours through a heat treatment unit 150 (S130).

In FBG sensor fabrication, hydrogen remaining in the optical fiber after grating formation may change the final Bragg wavelength. Thus, the annealing temperature and time are important process conditions that determine the characteristics of the FBG sensor.

<Example 4>

Eighteen FBG sensors were fabricated by changing the annealing temperature conditions to 100 deg. C, 150 deg. C, and 200 deg. C while the hydrogen loading condition was set to 120 hours and the annealing time was fixed to 24 hours.

Table 5 summarizes the characteristics of the FBG sensors 18 manufactured through the fourth embodiment.

FBG Grating fabrication parameters
Properties of FBGs H2
loading UV Laser Irradiation
Time
[sec] Annealing condition Wavelength
[nm] Reflectivity [%] Temperature sensitivity [pm / ° C] FWHM
[pm] Time
[hour] Temperature
[° C] 5-100-1 5 days 70 24 100 1526.77 44.0 10.3 90 5-100-2 5 days 70 24 100 1527.83 66.3 10.4 100 5-100-3 5 days 70 24 100 1529.00 60.3 10.4 100 5-101-1 5 days 70 24 100 1531.70 69.3 10.4 110 5-101-2 5 days 70 24 100 1532.78 63.0 10.4 100 5-101-3 5 days 80 24 100 1534.00 41.3 10.4 100 5-150-1 5 days 75 24 150 1526.80 55.3 10.3 90 5-150-2 5 days 75 24 150 1527.85 63.0 10.3 110 5-150-3 5 days 75 24 150 1529.02 63.7 10.4 100 5-151-1 5 days 75 24 150 1531.71 29.3 10.4 90 5-151-2 5 days 78 24 150 1532.87 60.3 10.4 100 5-151-3 5 days 78 24 150 1533.95 47.5 10.4 90 5-200-1 5 days 78 24 200 1526.71 63.0 10.4 100 5-200-2 5 days 78 24 200 1527.79 60.3 10.4 100 5-200-3 5 days 78 24 200 1528.94 58.3 10.4 100 5-201-1 5 days 75 24 200 1531.69 39.3 10.5 90 5-201-2 5 days 75 24 200 1532.79 55.3 10.5 100 5-201-3 5 days 75 24 200 1533.95 20.7 10.5 90

10 is a graph showing the radiation effects of the FBG sensor fabricated by changing the annealing temperature conditions to 100 ° C, 150 ° C, and 200 ° C with the annealing time fixed to 24 hours.

The total radiation dose was 31.0 kGy and the dose rate was 115 Gy / min for 18 FBG sensors manufactured with different annealing conditions.

As a result, as shown in FIG. 10, as the annealing temperature was raised, the radiation sensitivity was increased. When the annealing was performed at 200 ° C as compared with the annealing temperature of 100 ° C, the BSW change was more than two times higher. Therefore, in order to improve the radiation resistance of the FBG sensor, it is confirmed that a stabilization period in which sufficient annealing is performed for 24 hours while maintaining the annealing temperature at 80 to 100 ° C is required.

11 is a graph comparing internal radiation of a conventional FBG sensor and an FBG sensor manufactured by the manufacturing method according to the present invention.

As a result of comparison, the FBG sensor manufactured by the manufacturing method according to the present invention showed a BWS change of about 5 pm (± 0.5 ° C) based on the accumulated dose of 18 kGy, and the IR radiation characteristic was confirmed to be 7 times or more better than that of the standard FBG.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.

10: Fiber optic 11: Grid
110: chamber 111: space
120: hydrogen injection means 130: sensing means
131: FBG sensor 132: monitoring means
140: UV laser irradiation means 141: stage
150: heat treatment means 151: chamber
152: heater

Claims (6)

An apparatus for manufacturing an optical fiber grating sensor for use in a radiation environment,
A chamber for providing a sealed space in which the optical fiber is accommodated;
Hydrogen injecting means for injecting hydrogen at a constant pressure into the chamber accommodating the optical fiber;
Sensing means for confirming an amount of hydrogen injected into the chamber;
And UV laser irradiation means for irradiating a UV-irradiated optical fiber in the chamber with a UV laser to form a grating on the optical fiber. The method according to claim 1,
And heat treatment means for accommodating the optical fiber having been irradiated with the UV laser as an internal space and performing heat treatment. The method according to claim 1,
The sensing means comprises:
FBG sensor;
And monitoring means for monitoring a Bragg wavelength change of the FBG sensor according to a hydrogen injection amount. The method of claim 3,
Wherein the monitoring means comprises an OSI (Optical Sensing Interrogator). A method for manufacturing an intracardiac radiation optical fiber grating sensor using the apparatus for manufacturing an internal radiation optical fiber grating sensor according to any one of claims 1 to 4,
A first step of introducing hydrogen into the optical fiber by injecting hydrogen through the hydrogen injecting means at a pressure of 100 atm for 110 to 130 hours after the optical fiber is placed in the chamber;
And a second step of removing the optical fiber from the chamber and forming a grating on the optical fiber by irradiating the optical fiber through the UV laser irradiation means with an intensity of 24 mJ / cm 2 to 26 mJ / cm 2 for 60 seconds to 80 seconds. A method for manufacturing a radiation - induced optical fiber grating sensor. 6. The method of claim 5,
And a third step of performing heat treatment for 20 to 30 hours at a temperature of 80 ° C to 100 ° C through the heat treatment means of the optical fiber on which the second step has been performed.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110794512A (en) * 2019-12-04 2020-02-14 中国工程物理研究院激光聚变研究中心 Grating writing method, grating writing device, optical fiber and optical fiber laser
CN115236797A (en) * 2022-08-12 2022-10-25 武汉理工大学 High-temperature-resistant weak-fiber grating array and preparation method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110794512A (en) * 2019-12-04 2020-02-14 中国工程物理研究院激光聚变研究中心 Grating writing method, grating writing device, optical fiber and optical fiber laser
CN110794512B (en) * 2019-12-04 2021-02-05 中国工程物理研究院激光聚变研究中心 Grating writing method, grating writing device, optical fiber and optical fiber laser
CN115236797A (en) * 2022-08-12 2022-10-25 武汉理工大学 High-temperature-resistant weak-fiber grating array and preparation method thereof
CN115236797B (en) * 2022-08-12 2024-04-16 武汉理工大学 High-temperature-resistant weak fiber grating array and preparation method thereof

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