KR20100090590A - Multiplex physical quantity measuring method and system using optical multiple fiber bragg grating - Google Patents

Abstract

PURPOSE: A method and a system for measuring a number of physical parameters using a plurality of fiber gratings are provided to easily measure the change of the physical parameter to be measured by differently forming the patterns of the response waveforms reflected from each fiber grating to be able to be distinguished each other. CONSTITUTION: A system for measuring a number of physical parameters using a plurality of fiber gratings comprises an optical fiber sensor and a calculator. The optical fiber sensor consists of a plurality of fiber grating sensors which respectively create the different waveform patterns for the incident lights and are aligned along a light transfer path in a line. The calculator detects the wavelength movement of each waveform pattern from the light which has been transmitted to the fiber sensor, has reacted with each fiber grating sensor and then has been detected, and calculates the change of the physical parameter of a target for an environment in which the fiber grating sensor has been installed. The calculator comprises a light source(10), an light distributor and a calculating unit(40).

Description

Multiple physical quantity measuring method and system using optical multiple Fiber Bragg Grating}

The present invention relates to a method and system for measuring a physical quantity using an optical fiber grating, wherein a response waveform due to incident light between a plurality of optical fiber grating sensors is formed differently so that a change in the physical quantity to be measured can be easily measured for each sensor. It relates to a physical quantity measuring method and system.

As the optical fiber grating changes in temperature or strain, the wavelength of the optical signal reflected from the optical fiber grating is shifted. Therefore, the wavelength change of the light reflected from the optical fiber grating can be measured and used to determine what size of external temperature, strain, pressure, etc. has been applied from the amount of change in the wavelength.

Such optical fiber gratings are used as sensors in various fields such as diagnosis of structures.

Also, in the case of a structure such as a bridge, when a plurality of diagnostic points are used, optical fiber grating sensors with different center wavelengths reflected by incident light are arranged in a row to detect shifts of peak wavelengths, and thus the amount of physical quantity such as strain for each diagnostic point is detected. The change is measured.

However, in the case of arranging optical fiber grating sensors having different center wavelengths of reflected light with respect to incident light, the stresses applied to the optical fiber grating sensors interact with each other so that the shifted wavelength centers overlap each other or the positions of the center wavelengths are reversed. In this case, it is difficult to identify the problem. For example, if the center wavelength of the reflected light of the first optical fiber grating sensor and the center wavelength of the reflected light of the second optical fiber grating sensor are manufactured to be different by 1 nm, the wavelength of the first optical fiber grating sensor is shifted in the direction in which the reflected wavelength is increased. When the stress is applied and the second optical fiber grating sensor is stressed so that the wavelength is shifted in the direction in which the reflected wavelength is shortened, each of the shifted wavelength centers overlaps each other or the position of the center wavelength is reversed. There is a problem that cannot be distinguished.

The present invention was devised to improve the above problems, and the physical quantity measurement method using an optical fiber grating which can improve the measurement accuracy by making it possible to distinguish the response waveform for the physical quantity applied to each of the plurality of optical fiber grating sensors and The purpose is to provide a system.

In order to achieve the above object, a physical quantity measurement system using an optical fiber grating according to the present invention includes a plurality of optical fiber grating sensors that generate different waveform patterns for incident light, respectively, in which optical fiber gratings are arranged in a line along an optical transmission path. Wow; A calculator for detecting the wavelength shift of each of the waveform patterns from the light transmitted to the optical fiber sensor and reacted by each of the optical fiber grating sensors to calculate a change in a physical quantity to be measured for an environment in which the optical fiber grating sensors are installed; It is provided.

Preferably the calculator comprises a light source for emitting light to the optical fiber sensor; An optical splitter which transmits the input light emitted from the light source to the optical fiber sensor unit and outputs the light reflected from each of the optical fiber grating sensors of the optical fiber sensor unit to be separated from the input light; And a calculating unit for detecting the light output from the optical splitter and analyzing the wavelength shift of each waveform pattern from the detected light to calculate a change in the physical quantity to be measured.

More preferably, each of the optical fiber grating sensors is formed with different amplitudes and wavelength widths between the waveform patterns reflected on the input light.

In addition, it is preferable that each of the waveform patterns have different center wavelengths under the same environmental conditions and have an asymmetric shape with respect to the center wavelength.

The optical splitter may be applied to a circulator.

In addition, the physical quantity measurement method using the optical fiber grating according to the present invention to achieve the above object is a. Arranging a plurality of optical fiber grating sensors each generating a mutually different waveform pattern for incident light in a row along the optical transmission path; I. Transmitting input light to the optical fiber grating sensor; All. Computing a wavelength shift amount corresponding to the waveform pattern from the light reflected from the optical fiber grating sensors to calculate a change in the physical quantity to be measured for the environment in which the optical fiber grating sensor is installed.

According to the method and system for measuring physical quantity using an optical fiber grating according to the present invention, since the pattern of the response waveform reflected from each optical fiber grating sensor is formed to be distinguishable from each other, it is possible to easily measure the change in physical quantity to be measured. Provide advantages.

Hereinafter, a method and system for measuring physical quantity using an optical fiber grating according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a physical quantity measurement system using an optical fiber grating according to the present invention.

Referring to FIG. 1, the measurement system includes a light source 10, a circulator 20, a plurality of optical fiber grating sensors 31 to 33, and a calculator 40.

The optical fiber sensor unit has a plurality of optical fiber grating sensors 31 to 33 that respectively generate different waveform patterns with respect to incident light, and are arranged in a line along the optical transmission path.

In the illustrated example, the optical fiber sensor unit has a structure in which the first optical fiber grating sensor 31, the second optical fiber grating sensor 32, and the third optical fiber grating sensor 33 are connected in series, and the number applied is shown. Of course, not limited to.

Each of the optical fiber grating sensors 31 to 33 is formed to have different amplitudes and wavelengths between waveform patterns reflected with respect to input light input from the light source 10.

Here, the waveform patterns of the optical fiber grating sensors 31 to 33 are the first optical fiber grating sensor 31, the second optical fiber grating sensor 32 of FIG. 1 in the same environment, for example, without the same temperature and external force. As shown in FIGS. 2 to 4 in which the waveform patterns reflected by the third optical fiber grating sensors 33 corresponding to the incident light are enlarged, the center wavelengths λ1, λ2, and λ3 are different from each other, and the amplitude and the wavelength width are different from each other. It is formed differently.

In other words, when looking at each waveform pattern, the amplitude of the wavelengths is sequentially smaller in the order of the first optical fiber lattice sensor 31, the third optical fiber lattice 33, and the second optical fiber lattice sensor 32. The wavelength width that can be implanted is in a form sequentially narrower in the order of the second optical fiber lattice sensor 32, the third optical fiber lattice 33, and the first optical fiber lattice sensor 31. Therefore, even if the waveform patterns overlap each other or are reversed at the time of position movement, the waveform patterns can be easily distinguished.

Each of the optical fiber grating sensors 31 to 33 has a structure in which a plurality of gratings are formed to be spaced apart from each other in the optical fiber.

Here, the grating is applied to one side of the optical fiber formed by irradiating the ultraviolet light to be spaced apart from each other. In the drawings, the grid is illustrated vertically for better understanding.

The optical fiber grating sensors 31 to 33 may be formed by a known method such as a method of irradiating ultraviolet rays.

A method of forming an optical fiber grating by irradiating ultraviolet rays is a conventional method, that is, a mask formed by focusing light emitted from a laser light source (not shown) through a focusing lens (not shown), and then forming a slit corresponding to a desired grating spacing ( It is possible to use a method of irradiating the optical fiber through the (not shown).

In this case, each of the optical fiber grating sensors 31 to 33 has the intensity, irradiation time, lattice spacing, gap variation between the lattice, irradiated so that the waveform patterns of the reflected light with respect to the incident light are different from each other, the doping material such as germanium What is necessary is just to manufacture suitably combining methods, such as adjustment of the addition amount of (Ge).

Preferably, the reflected wave patterns of the optical fiber grating sensors 31 to 33 manufactured by this method in the same environment, for example, at the same temperature conditions, have different center wavelengths, and the discrimination power between the wavelength patterns is further increased. In order to increase, it is preferable that the left and right waveforms are formed to have an asymmetrical shape with respect to the center wavelength.

The calculator detects the wavelength shift of the waveform pattern inherent in each optical fiber grating sensor 31 to 33 known from the light transmitted to the optical fiber sensor unit and reacted by each of the optical fiber grating sensors 31 to 33 to detect the wavelength shift of the optical fiber grating sensor 31. To 33) calculate the change of the physical quantity to be measured, for example, the temperature or the strain, with respect to the environment in which each is installed.

The calculator includes a light source 10, a circulator 20, and a calculator 40.

The light source 10 is applied to emit broadband light of a wide wavelength band that can cover the wavelength band of each waveform pattern of the optical fiber sensor unit.

The circulator 20 is applied as an optical splitter to transmit the input light emitted from the light source 10 to the optical fiber sensor unit, and to separate light reflected from each of the optical fiber grating sensors 31 to 33 from the optical fiber sensor unit from the input light. Output

Unlike the illustrated example, the optical coupler may be applied as the optical splitter.

The calculation unit 40 detects the light output from the circulator 20 applied to the optical splitter, analyzes the spectrum of the detected light, analyzes the wavelength shift of each waveform pattern, and measures the physical quantity, for example, temperature or strain. Calculate the change.

The calculator 40 calculates a physical quantity from the spectrum of the detected light with reference to a lookup table in which a temperature or strain value corresponding to the wavelength shift of each waveform pattern is recorded in advance.

The calculator 40 may be configured to store the calculated physical quantity in a storage device or to display the same through a display device, and may be constructed to transmit measurement information wirelessly when the remote controller is configured to transmit remotely.

Hereinafter, a measurement process by the physical quantity measurement system using the optical fiber grating will be described.

First, a plurality of optical fiber grating sensors 31 to 33, which respectively generate different waveform patterns with respect to incident light, are arranged in a line with each other along the optical transmission path.

Here, each of the optical fiber grating sensors 31 to 33 may be disposed to correspond to the measurement target position.

Next, light is transmitted from the light source 10 to the optical fiber grating sensors 31 to 33 along the light transmission path through the circulator 20.

Subsequently, the wavelength shift amount is calculated based on the waveform pattern of each of the optical fiber grating sensors 31 to 33 known from the light reflected from the optical fiber grating sensors 31 to 33 and the optical fiber grating sensors 31 to 33 are installed. Calculate the change in the physical quantity to be measured for the environment.

That is, as shown in FIG. 5, the first optical fiber lattice sensor 31 is moved in a direction in which the wavelength of the center wavelength is increased by the external environment, and the second optical fiber lattice sensor 32 is caused by another external environment. Even if the center wavelength location is moved in the direction of decreasing wavelength and overlapped or inverted, the waveform can be distinguished from each other by waveforms having different peaks and wavelength widths.

Similarly, even if the third optical fiber lattice sensor 33 overlaps with the waveform pattern of the first optical fiber lattice sensor 31 or the wavelength pattern of the second optical fiber lattice sensor 33 or the position is reversed due to an external environment. Different waveform patterns can distinguish one another.

1 is a view showing a physical quantity measurement system using an optical fiber grating according to the present invention,

2 to 4 are enlarged waveform diagrams showing examples of waveform patterns reflected from the optical fiber grating sensors of FIG. 1,

FIG. 5 is a waveform diagram illustrating an example in which a unique waveform pattern is moved according to a change in a physical quantity applied to each of the optical fiber grating sensors of FIG. 1.

Claims (7)

A plurality of optical fiber grating sensors each generating mutually different waveform patterns with respect to incident light, the optical fiber sensor parts being aligned in a line with each other along an optical transmission path; A calculator for detecting a wavelength shift of each of the waveform patterns from the light transmitted to the optical fiber sensor and reacted by each of the optical fiber grating sensors to calculate a change in a physical quantity to be measured for an environment in which the optical fiber grating sensors are installed; Physical quantity measurement system using an optical fiber grating characterized in that it comprises a. The method of claim 1, wherein the calculator A light source for emitting light to the optical fiber sensor; An optical splitter which transmits the input light emitted from the light source to the optical fiber sensor unit and outputs the light reflected from each of the optical fiber grating sensors of the optical fiber sensor unit to be separated from the input light; And a calculation unit for detecting the light output from the optical splitter and analyzing the wavelength shift of each waveform pattern from the detected light to calculate a change in the physical quantity to be measured. . The physical quantity measurement system of claim 2, wherein each of the optical fiber grating sensors is formed to have different amplitudes and wavelength widths between waveform patterns reflected with respect to input light. The physical quantity measurement system of claim 3, wherein the waveform patterns have different center wavelengths under the same environmental conditions and have an asymmetric shape with respect to the center wavelength. The physical quantity measurement system using an optical fiber grating according to claim 3, wherein the optical splitter is a circulator. end. Arranging a plurality of optical fiber grating sensors that respectively generate mutually different waveform patterns for incident light, aligned in a line with each other along an optical transmission path; I. Transmitting input light to the optical fiber grating sensor; All. Calculating a change in the physical quantity to be measured with respect to an environment in which the optical fiber grating sensors are installed by calculating a wavelength shift amount corresponding to the waveform pattern from the light reflected from the optical fiber grating sensors; Physical quantity measurement method using an optical fiber grating. The method of claim 6, wherein each of the optical fiber grating sensors has a shape in which amplitudes and wavelength widths of wave patterns reflected from input light are different from each other.

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