KR20140102513A - Optical fiber displacement sensor having temperature compensation structure - Google Patents

Optical fiber displacement sensor having temperature compensation structure Download PDF

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Publication number
KR20140102513A
KR20140102513A KR1020130015953A KR20130015953A KR20140102513A KR 20140102513 A KR20140102513 A KR 20140102513A KR 1020130015953 A KR1020130015953 A KR 1020130015953A KR 20130015953 A KR20130015953 A KR 20130015953A KR 20140102513 A KR20140102513 A KR 20140102513A
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South Korea
Prior art keywords
optical fiber
pressure
displacement
fixing
sensor
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KR1020130015953A
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Korean (ko)
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이금석
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(주)에프비지코리아
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Priority to KR1020130015953A priority Critical patent/KR20140102513A/en
Publication of KR20140102513A publication Critical patent/KR20140102513A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/08—Testing mechanical properties
    • G01M11/088—Testing mechanical properties of optical fibres; Mechanical features associated with the optical testing of optical fibres

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

The present invention relates to a pressure displacement sensor using an optical fiber grating sensor. The pressure displacement sensor has a configuration for measuring displacement depending on pressure by comprising a main body which receives pressure inside; a diaphragm which is displaced inside the main body and is curved or recessed depending on the applied pressure; an optical fiber which delivers displacement measured depending on the applied pressure; an end side optical fiber fixing unit which fixes an end of the optical fiber by being fixed to the diaphragm; an optical fiber grating sensor for pressure measurement, which is connected between the optical fibers and measures the displacement by being relaxed or tense; and an I/O side optical fiber fixing end to which an I/O unit of the optical fiber is reliably fixed by a binder. By using the pressure displacement sensor with the optical fiber grating sensor, the pressure displacement sensor is easily installed and fixed, and the difficulties of construction is eliminated.

Description

[0001] OPTICAL FIBER DISPLACEMENT SENSOR HAVING TEMPERATURE COMPENSATION STRUCTURE [0002]

The present invention relates to a pressure displacement sensor using a fiber grating sensor, and more particularly, to a pressure displacement measurement device with a large error, which can measure pressure displacement more precisely, And more particularly, to a pressure displacement sensor using an optical fiber grating sensor capable of accurately measuring a displacement amount according to a pressure by compensating a change in a temperature change or a refractive index of the surrounding ambient air.

In general, the principle of fiber Bragg grating is that the principle of light propagation in an optical fiber is the principle of total reflection when light travels from a material with a high refractive index to a material with a low refractive index, And the light incident on the optical fiber core is reflected at the interface between the core layer having a high refractive index and the cladding layer having a low refractive index and is propagated along the optical fiber core portion.

The main component of the optical fiber is made of silica glass. The structure of the optical fiber is composed of a core portion which is a center of the optical fiber to which germanium is added so that the refractive index is slightly higher, and a cladding portion which is an overlay layer which protects the center.

Fiber Bragg The Bragg Grating Array Sensor (FBG) is an optical fiber Bragg Grating Array (FBG) that grids several optical fiber Bragg gratings on a single strand of optical fiber at a constant length and then modulates the wavelength of light reflected from each grating Is a sensor using different characteristics.

Generally, a germanium (Ge) material is added to the optical fiber core in order to increase the refractive index of the cladding rather than the cladding. In this process, structural defects may occur during the deposition of the material on the silica glass. In this case, when strong ultraviolet rays are irradiated on the optical fiber core, the refractive index of the optical fiber changes as the bonding structure of germanium is deformed.

The fiber Bragg grating refers to a periodic change in the refractive index of the optical fiber core using this phenomenon. This grating reflects only the wavelengths satisfying the Bragg condition and transmits the other wavelengths as they are. When the ambient temperature of the grating is changed or a tensile force is applied to the grating, the refractive index or length of the optical fiber is changed, so that the wavelength of the reflected light is changed. Therefore, by measuring the wavelength of the light reflected from the fiber Bragg grating, temperature, tensile, pressure, bending, etc. can be detected.

The most important application of this fiber Bragg grating sensor is to diagnose the condition of the structure. The fiber optic lattice sensor is installed inside the concrete in the production of bridges, dams, buildings, etc., and the safety condition of the structure can be diagnosed by sensing tensile distribution and bending degree inside the structure. In addition, it can be used for diagnosis of wing conditions of an aircraft or a helicopter.

However, in the field of pressure displacement sensors, no field of applying an optical fiber lattice sensor has been found. As shown in FIG. 1, in the conventional pressure displacement sensor F 0 , the optical fiber (a) A diaphragm b, a main body c, and a tension wire w.

The pressure displacement sensor F 0 according to the related art is provided with a diaphragm b on the lower side to which pressure is applied in the body c to receive pressure therein and a tension wire Wire, w), and an optical fiber (a) is attached to the middle of the tension wire (w). Since the optical fiber a is merely attached to the outside of the tension wire w rather than being interrupted in the middle of the tension wire w, the tension or relaxation of the optical fiber a is sufficiently transmitted to the optical fiber a It was difficult.

The tension wire w may be composed of a wire or a steel tube and an error due to the tension contraction of the wire or the steel pipe is excessively large and furthermore a fine displacement due to the curvature of the diaphragm b is generated on the tension wire w It is impossible to measure by accurate pressure displacement.

In addition, it is very difficult to attach the tension wire w and the diaphragm (b), and there is no means to fix the diaphragm wire (w) and the diaphragm (b) after attachment. Therefore, problems such as disconnection of the fixed attachment and breakage of the diaphragm are frequently caused.

When the tension wire w and the diaphragm b are attached to each other, the tension wire w must be precisely aligned with the center of the diaphragm b so that when the pressure is applied, the diaphragm b, It is very difficult to fit the tension wire w to the center of the diaphragm b by directly fixing the tension wire w to the diaphragm b.

DISCLOSURE OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a pressure displacement sensor using an optical fiber according to the prior art has a tension wire which is hardly realizable, The present invention also provides a pressure displacement sensor using an optical fiber lattice sensor that uses an optical fiber instead of the optical fiber and includes an end optical fiber fixing part to facilitate fixing installation and overcome the difficulty of construction.

Another object of the present invention is to provide a pressure displacement sensor using a conventional optical fiber by using a tension wire using a wire or a steel tube as a member which can be stretched or shrunk and attaching an optical fiber to the tension wire, , An error due to tension and shrinkage is largely generated. In this case, an optical fiber that transmits tension and contraction pressure displacement instead of tension wire is used, and an optical fiber Bragg grating Sensor is connected to the pressure sensor to precisely and precisely prevent an error.

It is a further object of the present invention to provide a tension wire which is difficult to precisely align the tension wire with the center of the diaphragm and thus can not accurately measure the amount of displacement of the diaphragm due to curvature and depression of the diaphragm during pressure application. Side optical fiber fixing part at the center of the diaphragm so that the optical fiber can be accurately connected to the center part of the diaphragm so that the displacement amount can be more accurately measured when the pressure is applied, and a pressure displacement sensor using the optical fiber lattice sensor .

Another object of the present invention is to fix only the end-end strand of the optical fiber to which the measured pressure displacement information is transmitted to the end-side optical fiber fixing portion. Such an operation is extremely difficult, and if the tensile force is applied after installation, An optical fiber grating sensor including an end side support for supporting the end side optical fiber fixing part so that the optical fiber forms a loop on the outer periphery of the end side optical fiber fixing part so as to be able to set the optical fiber more stably, And to provide a pressure displacement sensor using the same.

It is a further object of the present invention to provide a method of manufacturing an end-side support, in which a material of the end-side support is made of aluminum having a larger coefficient of thermal expansion because the steel support generally shrinks or expands as the temperature changes, The present invention provides a pressure displacement sensor using an optical fiber grating sensor capable of accurately and precisely measuring a pressure displacement amount by compensating displacement caused by contraction and expansion of the support.

Another object of the present invention is to provide a temperature-compensating optical fiber lattice sensor for measuring the temperature of the optical fiber lattice sensor for pressure measurement, which is caused by an external temperature change, The present invention provides a pressure displacement sensor using an optical fiber grating sensor that can compensate for the refractive index and wavelength variation of the pressure gauge fiber lattice sensor according to the temperature change to reduce the error and measure more precise pressure displacement.

In order to accomplish the above object, a pressure displacement sensor using the optical fiber grating sensor according to the present invention comprises: a body to which pressure is applied; A diaphragm contained in the interior of the body and curved or depressed according to an applied pressure; An optical fiber for transmitting the displacement measured according to the applied pressure; An end-side optical fiber fixing part fixed on the diaphragm to fix the end of the optical fiber; A fiber optic lattice sensor connected between the optical fibers for measuring displacement by being relaxed or tensed according to an applied pressure, and an input / output part of the optical fiber, the input / output part being fixed firmly with a fixing agent, .

The present invention further includes a support for holding the optical fiber and the optical fiber grating sensor by fixing the main body and the input / output side optical fiber fixing portion.

Side optical fiber fixing part is fixed to the input / output side optical fiber fixing part by a fixing agent, and the end side optical fiber fixing part is included in the optical fiber fixing part of the end side, And an end-side support which is supported by the end-side support.

The end side optical fiber fixing part includes a fixing pin which is supported by the end side optical fiber fixing part and is fixed to the end side optical fiber fixing part. And the end side support includes a displacement adjusting part for adjusting the displacement by selectively pressing and fixing the end side optical fiber fixing part in the longitudinal direction of the fixing groove .

The supporting member is made of iron and the end supporting member is made of aluminum to compensate the thermal expansion depending on the temperature.

The pressure-displacement sensor further includes a temperature-compensating fiber grating sensor for compensating a wavelength measured by the pressure-measuring fiber grating sensor according to a change in temperature, wherein the temperature-compensating fiber grating sensor comprises the pressure- The optical fiber grating sensor for pressure measurement is connected between the optical fibers at the input end side and the optical fiber grating sensor for temperature compensation is connected between the optical fibers at the output end side .

As described above, according to the pressure displacement sensor using the optical fiber grating sensor according to the present invention, it is possible to easily fix the pressure displacement sensor of the present invention by using an optical fiber and including the end side optical fiber fixing part, It is possible to overcome the difficulty of construction.

According to the pressure displacement sensor using the optical fiber grating sensor according to the present invention, an optical fiber is used instead of a tension wire in which an error is generated by attaching an optical fiber, and the optical fiber is cut to form an optical fiber Bragg grating sensor So that it is possible to obtain an effect that precise and error can be prevented.

According to the pressure displacement sensor using the optical fiber lattice sensor according to the present invention, the optical fiber is included in place of the tension wire, and the optical fiber fixing portion at the center of the diaphragm is included at the central portion so that the optical fiber can be accurately connected to the center portion of the diaphragm, It is possible to obtain an effect of more accurately measuring the amount of displacement at the time.

According to the pressure displacement sensor using the optical fiber lattice sensor according to the present invention, the optical fiber forms a loop on the outer periphery of the end side optical fiber fixing part so as to be stably fixed by the fixing material so that the optical fiber can be set more stably, The effect of being able to stably set the optical fiber can be achieved by including the end side support member supporting the optical fiber fixing portion.

According to the pressure displacement sensor using the optical fiber lattice sensor according to the present invention, the material of the end side support is formed of aluminum having a larger coefficient of thermal expansion to compensate the displacement caused by contraction and expansion of the support, It is possible to obtain an effect that measurement can be performed.

According to the pressure displacement sensor using the optical fiber grating sensor according to the present invention, a separate optical fiber grating sensor for temperature compensation is installed to compensate for the refractive index and the wavelength change of the optical fiber grating sensor for pressure measurement according to the temperature change, The effect of making it possible to measure the pressure displacement is obtained.

1 is a sectional view showing a pressure displacement sensor according to the prior art,
FIG. 2 is an operation diagram of a pressure displacement sensor using a fiber grating sensor,
3 is a perspective view illustrating a pressure displacement sensor using an optical fiber grating sensor according to an embodiment of the present invention,
4 is a perspective view illustrating a pressure displacement sensor using an optical fiber grating sensor according to another embodiment of the present invention,
5 is a perspective view illustrating a pressure displacement sensor using an optical fiber grating sensor according to another embodiment of the present invention.
FIG. 6 is a perspective view illustrating an end product of a pressure displacement sensor using an optical fiber grating sensor according to another embodiment of the present invention. FIG.

Hereinafter, a pressure displacement sensor using an optical fiber grating sensor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Before describing the pressure displacement sensors F, F 1 , F 2 , and F 3 using the optical fiber grating sensor of the present invention, it is preferable that the operating relationship in which the displacement amount according to the pressure is measured using the optical fiber grating sensor I want to explain.

FIG. 2 is a cross-sectional view illustrating the operation of the pressure displacement sensor according to the present invention, in which displacement occurs before and after pressure application. It is to be understood that the constitution and the merge of the present invention are omitted since they are only schematic views of the operating relationship of the present invention.

The diaphragm 4 formed inside the main body 5 of the pressure displacement sensor of the present invention is kept in a horizontal state as shown in the left side. Therefore, no external force acts on the optical fiber 1 connected to the central portion. Accordingly, the optical fiber grating sensor 2 connected between the optical fibers 1 is not affected by stress, shrinkage, or the like, so that the wavelength of the optical fiber grating sensor 2 is not changed internally.

However, after pressure application, the diaphragm 4 inside the main body 5 is curved upward by the pressure P applied from below as shown in the right figure. With this curvature, the central portion of the diaphragm 4 has a vertical displacement (delta) according to the pressure. The optical fiber 1 and the optical fiber grating sensor 2 connected to the central portion of the curved diaphragm 4 are subjected to an external force in the axial direction to be contracted. As a result, the optical fiber grating sensor 2 causes a change in wavelength, and the amount of displacement? In accordance with the pressure can be measured.

The optical fiber 1 and the optical fiber grating sensor 2 are arranged in such a manner that the tension P is applied to the lower portion of the diaphragm 4, Thus forming a completely different wavelength.)

Hereinafter, preferred embodiments and configurations of the pressure displacement sensors F, F 1 , F 2 and F 3 using the optical fiber grating sensor according to the present invention will be described in detail with reference to the accompanying drawings.

According to an embodiment of the present invention, as shown in FIG. 3, the optical fiber 1 may be formed of an optical fiber 1 having one input / output end so that the pressure displacement can be measured. Side optical fiber fixing portion 8 fixed to the central portion of the diaphragm 4 in which the displacement according to the displacement is formed.

According to an embodiment of the present invention shown in FIG. 3, the pressure displacement sensor F 1 of the present invention includes a main body 5 to which pressure is applied; A diaphragm 4 contained in the interior of the body and curved or depressed according to an applied pressure; An optical fiber (1) for transmitting a displacement measured according to an applied pressure; An end side optical fiber fixing part 8 fixed on the diaphragm to fix the end of the optical fiber; A fiber optic lattice sensor 2 connected between the optical fibers for measuring a displacement by relaxing or tensing according to an applied pressure; An input / output side optical fiber fixing end 12 on which input / output portions of the optical fiber are firmly fixed by a fixing material 14; And a support table (6) for restraining the main body and the input / output side optical fiber fixing part to fix and support the optical fiber and the optical fiber grating sensor.

As shown in FIG. 1, the optical fiber 1 functions to measure and transmit a wavelength according to a pressure displacement measured by the optical fiber grating sensor 2 for measuring pressure. The use of such an optical fiber 1 can be applied by directly connecting the optical fiber grating sensor 2 by cutting it in the middle by using the optical fiber 1 as an optical fiber 1 as compared with that used as a tension wire in the related art.

In addition, an error occurs in the measurement of the pressure displacement due to the expansion or contraction of the tension wire itself used in conventional wire, steel pipe, etc., but since the expansion and contraction hardly occur in the optical fiber 1, The problem of generating an error can be solved.

Since the optical fiber 1 and the optical fiber grating sensor 2 are not expanded or contracted by an external force but are changed by the axial force to cause a change in the wavelength of the optical fiber grating sensor 2, It is possible to more precisely measure the amount of micro displacement according to the present invention.

As shown in FIG. 1, the pressure-measuring optical fiber grating sensor 2 is integrally connected in the middle of cutting the optical fiber 1, and when a displacement of the diaphragm 4 is generated according to a downward pressure, The internal wavelength is changed according to the pressure, so that the micro displacement amount due to the pressure can be accurately measured.

Since the optical fiber grating sensor 2 is generally made of a glass material such as an optical fiber 1 connected thereto, if the optical fiber grating sensor 2 is formed together with the tension wire as in the prior art, the tension wire of completely different material is cut, It was impossible to install. However, in the present invention, the optical fiber grating sensor 2 can be integrally connected by cutting the grating in the middle by using the optical fiber 1 instead of the tension wire, so that the optical fiber grating sensor 2 can measure the pressure displacement along the wavelength, So that it can be transmitted through the optical fiber 1.

As described above, the present invention overcomes the difficulty of construction by forming the optical fiber 1 and the optical fiber grating sensor 2 integrally, and overcomes the problem of occurrence of errors due to the expansion and contraction due to the installation of the conventional tension wire, The optical fiber 1 can be cut off from the form of attaching the sensor 2 to the outer periphery of the tension wire and formed integrally with the optical fiber 1 in the middle, thereby making it possible to measure the pressure displacement amount more precisely and accurately.

The technology of such a fiber grating sensor has been fully described in the Background of the Invention and will not be described below.

As shown in FIG. 3, the diaphragm 4 is formed of a stainless steel material which is inserted into the main body 5 and is formed as a horizontally clogged member. The diaphragm 4 may be curved or depressed according to a lower pressure. That is, it is preferable that the diaphragm 4 has a restoring force and is made of a stainless steel material which is curved or depressed according to the lower pressure, and then can be returned to its original state when the pressure is removed.

The diaphragm 4 tends or relaxes the optical fiber 1 and the optical fiber grating sensor 2 fixed to the central portion by forming a vertical displacement? While being curved and depressed according to the applied pressure of the lower portion. The operation and function of this operation will be described in detail with reference to FIG.

As shown in FIG. 3, the main body 5 is formed of an iron member including the diaphragm 4 therein and having a large rigidity. It is preferable that the main body 5 is formed in a cylindrical shape so that the diaphragm 4 is clogged in the inside and is easily curved and depressed by the pressure applied to the bottom.

Thus, the main body 5 includes a pressure applying portion at a lower portion thereof, which is not shown in FIG. 3 but is shown in FIG. An external pressure is applied through the pressure application unit to generate a displacement? At the center of the diaphragm 4. [

As shown in FIG. 3, the support 6 is a member for supporting and fixing the input / output side optical fiber fixing part 12 to the main body 5, and is generally formed parallel to the optical fiber 1 in the longitudinal direction. One side of the support base 6 is fixed to both sides of the main body 5 and the other side is firmly fixed to both ends of the input / output side optical fiber fixing portion 12. [

As described above, the support 6 fixes and fixes the input / output side optical fiber fixing portion 12 and the main body 5 so that the optical fiber 1 and the optical fiber grating sensor 2, which are formed in the longitudinal direction therebetween, . (The constraint fixation of such an optical fiber 1 is constrained by fixed fixation to the end side optical fiber fixing portion 8 and fixation fixation using the fixing agent 14 to the input / output side optical fiber fixing portion 12.)

The support base 6 is generally made of an iron material, but is not limited thereto. Any material may be used as long as it is rigid and firmly fixed. If the support 6 is made of iron, an error may occur in the displacement due to thermal expansion due to external temperature changes. The error due to the thermal expansion of the support table 6 may be compensated by the end side support described below.

As shown in FIG. 3, the end-side optical fiber fixing part 8 is fixed at one end to the central part of the diaphragm 4, and the other end is fixed to the distal end of the optical fiber 1. In the present invention, since the tension wire is directly fixed to the diaphragm 4 in the prior art, it is difficult to install the tension wire in the middle of the diaphragm 4 by including the end- It was almost impossible to install the center of gravity to be fixed, which can be solved.

That is, the end-side optical fiber fixing part 8 is first firmly fixed to the central part of the diaphragm 4, and then the end of the optical fiber 1 is fixed to the end-side optical fiber fixing part 8 , It can be installed more easily and installed precisely at the center of the diaphragm. Accordingly, the pressure displacement sensor of the present invention can measure the pressure displacement amount more precisely.

As shown in FIG. 3, the input / output side optical fiber fixing part 12 is fixedly fixed to one side of the support 6, and the input / output part of the optical fiber 1 is formed at a central part thereof across the length direction. Thus, the optical fiber 1 is firmly fixed to the input / output side optical fiber fixing portion 12 by the fixing agent 14.

3, the input / output side of the optical fiber 1 is fixed to the input / output side optical fiber fixing portion 12 and the end thereof is fixed to the end side optical fiber fixing portion 8 to thereby include the pressure measuring optical fiber sensor 2 The optical fiber 1 is firmly fixed within the pressure displacement sensor F 1 of the present invention. Accordingly, the pressure displacement can be accurately measured by being relaxed and relaxed only by the pressure displacement (delta) due to the lower diaphragm 4 without receiving external influences at all.

According to another embodiment of the present invention, the optical fiber 1 has an input end and an output end optical fiber as shown in FIG. 4. The optical fiber 1 forms two strands in the pressure displacement sensor F 2 of the present invention .

The optical fiber 1 formed in such a two-stranded configuration can more reliably set the optical fiber 1. That is, in the above-mentioned embodiment, it is very difficult to fix the end of the optical fiber 1 to the end side optical fiber fixing part 8, and since the end is fixed after the installation, It is possible to overcome the difficulty of such construction and to set a more stable and robust setting.

According to another embodiment of the present invention shown in FIG. 4, the pressure displacement sensor F 2 of the present invention is configured such that the optical fiber forms a loop on the outer periphery of the end side optical fiber fixing part 8 and is wound and fixed by a fixing agent, An input end and an output end of the optical fiber 1 can be fixed to the input / output side optical fiber fixing part 12 by a fixing agent.

The end portion side support 7 may further include an end portion side support 7 to which the end portion side optical fiber fixing portion 8 is supported and supported. Side optical fiber fixing portion 8 includes a fixing pin 9 which is inserted into the fixing groove and supported by the fixing groove 9. The optical fiber fixing portion 8 includes a fixing portion 9, And a groove 11.

And a displacement regulating unit 10 for selectively pressing and fixing the end side optical fiber fixing unit in the longitudinal direction of the fixing optical fiber to adjust the displacement, Is made of iron and the end side support 7 is made of aluminum to compensate for the thermal expansion depending on the temperature.

The optical fiber 1, the pressure measuring optical fiber grating sensor 2, the diaphragm 4, the main body 5, the support 6, the end optical fiber fixing part 8, the input / output side optical fiber fixing part 12, (14) and the like have been fully described in the embodiment of the present invention with reference to FIG. 3, and the operation relationship will be described below while examining other configurations in detail.

As shown in FIG. 4, the optical fiber 1 is inserted into the pressure displacement sensor F 2 of the present invention and wound around the loop, and then flows out of the input end 1a and the output end 1b of the optical fiber. As the stranded optical fiber 1 is formed, one side becomes the input terminal 1a and the other side becomes the output terminal 1b.

In this case, the optical fiber 1 is first inserted into the pressure displacement sensor of the present invention, then formed as a loop on the outer periphery of the end-side optical fiber fixing part 8 and is wound and drawn out to form two strands 1a and 1b .

The two strands of optical fibers 1a and 1b thus formed are fixedly fixed to the end side optical fiber fixing part 8 at one end of the optical fiber 1 in the embodiment of the present invention described above with reference to FIG. It is difficult to install and after the installation, the coupling force is weak and can be easily released. Therefore, it is desired to achieve a more stable setting by simplifying the installation and improving the binding force.

4, according to the configuration of the end optical fiber fixing part 8 and the input / output side optical fiber fixing part 12, the shape of the loop of the two optical fibers 1a, Function.

First, the end-side optical fiber fixing portion 8 is shaped so that the optical fiber 1 can be wound in a loop shape, and may be formed into a pulley shape having a cylindrical outer circumferential surface, as shown in FIG.

In particular, the optical fiber mounting groove 11 may be formed on the outer circumferential surface of the end-side optical fiber fixing part 8 so that the optical fiber 1 can be wound up in a loop shape.

Since the optical fiber mounting groove 11 is to be able to be caught and locked in the groove, the optical fiber mounting groove 11 may be formed as an elongated groove having the same shape as the outer shape of the optical fiber 1.

Since the optical fiber 1 is inserted into the optical fiber mounting groove 11 and is looped on the outer circumferential surface of the optical fiber fixing portion 8 and then the movement thereof is restricted, To be firmly fixed and fixed. This is because the minute pressure displacement due to the diaphragm 4 can be measured through the optical fiber grating sensor 2 for measuring pressure due to the sticking.

3, the input and output ends 1a and 1b of the two strands of the optical fiber are fixedly supported by the support 6, So that the fixing agent 14 is formed on each of the two strands and is firmly fixed.

As shown in FIG. 4, the input / output side optical fiber fixing part 12 is a member extending in a cross shape. Optical fibers 1a and 1b are attached to the transverse members respectively, and the longitudinal members are fixed to the supporting frame 6 Shape.

As shown in FIG. 4, the end portion side support body 7 supports and fixes the end portion side optical fiber fixing portion 8, and is usually formed parallel to the support portion 6 in the longitudinal direction, As shown in FIG. And may be made of aluminum metal in the material thereof.

The reason why the end side support 7 is made of aluminum is that the support 6 is made of iron so that it can be compensated when the thermal expansion according to temperature is mutually compensated. The coefficient of thermal expansion of the aluminum, which is the material of the end side support 7, is 2.5 times larger than the coefficient of thermal expansion of the material of the support 6. That is, as shown in FIG. 4, the length of the support 6 is much longer than the length of the end-side support 7, so that the length of the support 6 when the thermal expansion occurs due to the temperature change is relatively long. Accordingly, it is possible to effectively compensate the expansion of the support base 6 when the temperature changes through the aluminum-made end side support 7 having a coefficient of thermal expansion larger than that of iron, which is the material of the support base 6 will be.

4, the fixing pin 9 is inserted into the fixing groove 15 of the end side support 7 to support the end side optical fiber fixing part 8, and the end side optical fiber And may be formed as a protrusion protruding in the center of the side surface of the fixing portion 8. In this way, the end portion of the optical fiber fixing portion 8 is held in the fixing groove 15 by being inserted into the fixing groove 15.

The fixing grooves 16 are formed as through holes formed in the side surface of the end side support 7, particularly in the shape extending in the longitudinal direction. The fixing pin 9 of the end-side optical fiber fixing part 8 is supported in the fixing groove 16 in the longitudinal direction.

As shown in FIG. 4, the displacement adjusting unit 10 is formed to penetrate from the upper portion of the end side support 7 to the upper portion of the fixing groove 16, It is made of fixed compression bolts. The displacement adjusting unit 10 functions to adjust the displacement by selectively pressing and fixing the fixing pin 9 of the end side optical fiber fixing unit in the longitudinal direction of the fixing groove.

That is, when the displacement adjusting part 10 is tightened after the pressure displacement sensor as in the embodiment of FIG. 4 of the present invention is installed, the tensile force is applied by pressing the end side optical fiber fixing part 8, 4) can be moved upwards to control the displacement. On the other hand, when the bolt of the displacement adjusting part 10 is loosened, the central part of the diaphragm 4 can be downwardly moved to adjust the displacement.

According to another embodiment of the present invention, as shown in FIG. 5, an optical fiber having an input end and an output end is provided. In addition to the pressure gauge fiber optic lattice sensor 2, It is possible to compensate for the change in the wavelength due to the change in refractive index inside the pressure gauge fiber optic lattice sensor 2 according to the temperature change inside the pressure displacement sensor F 3 of the present invention including the lattice sensor 3 .

By including the optical fiber grating sensor 3 for temperature compensation in this way, different wavelengths are exhibited in the optical fiber grating sensor according to the change of the refractive index according to the temperature change. The temperature-compensating optical fiber grating sensor 3 By compensating this, it is possible to reduce the error of the wavelength and to measure more precise pressure displacement.

According to another embodiment of the present invention shown in FIG. 5, the pressure displacement sensor F 3 of the present invention is generally the same as that of the embodiment of FIG. 4 except that the outer circumference of the end- The optical fiber 1 wound in a loop shape is wound around the input / output side optical fiber fixing part 12 in a loop shape and then pulled out to the outside.

As shown in FIG. 5, it is preferable that the temperature-compensated fiber grating sensor 3 is formed at a portion where the periphery of the optical fiber grating sensor 3 is looped around the input / output side optical fiber fixing portion 12. In particular, it is preferable that the temperature-compensating fiber grating sensor 3 is connected between the optical fiber grating sensor 2 for pressure measurement and the other end of the optical fiber. For example, the pressure gauge fiber optic lattice sensor 2 may be connected between the optical fibers 1a on the input side and the temperature-compensating fiber grating sensor 3 may be connected between the optical fibers 1b on the output side.

The reason for this is that the wavelength at which the error is measured is measured at a refractive index that is changed according to the temperature change measured at the pressure displacement measured by the optical fiber sensor 2 for pressure measurement and transmitted through the output end 1b of the optical fiber The modified refractive index is again applied to reduce the error again in the optical fiber sensor 3 for temperature compensation.

FIG. 6 is a view showing a state in which the pressure displacement sensor F using the optical fiber grating sensor according to the embodiment of FIG. 5 is completed and installed. The embodiment shown in FIG. 6 has a case 13 for protecting the optical fiber 1 and the optical fiber grating sensor 2, 3, etc. included in the pressure displacement sensor F of the present invention and preventing the optical fiber 1, I complete it by covering it as a whole.

The present invention according to the embodiment of FIG. 6 includes a pressure applying unit 15 that is covered by the case 13 and applies pressure to the lower portion of the main body 5 to operate the diaphragm 4 therein can do.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

F, F 0 , F 1 , F 2 , F 3 : The pressure displacement sensor
a: optical fiber b: diaphragm c: body w: tension wire
1: fiber optic `1a: fiber optic input
1b; Fiber optic output stage 2: Fiber grating sensor for pressure measurement
3: Fiber grating sensor for temperature compensation 4: Diaphragm (stainless steel)
5: Main body 6: Support (iron)
7: end side support (aluminum) 8: input / output side optical fiber fixing portion
9: Fixing pin 10: Displacement adjusting part
11: optical fiber mounting groove 12: end optical fiber fixing portion
13: Case 14: Fixing agent
15: pressure applying part 16: fixing groove
P: applied pressure 隆: displacement amount according to pressure

Claims (7)

A body to which pressure is applied;
A diaphragm contained in the interior of the body and curved or depressed according to an applied pressure;
An optical fiber for transmitting the displacement measured according to the applied pressure;
An end-side optical fiber fixing part fixed on the diaphragm to fix the end of the optical fiber;
A fiber optic lattice sensor connected between the optical fibers for pressure measurement for measuring displacement by relaxing and tensing according to applied pressure,
Wherein the optical fiber grasper includes an input / output side optical fiber fixed end where the optical fiber is firmly fixed with a fixing agent, and measures a displacement according to a pressure. The apparatus according to claim 1, wherein the pressure displacement sensor
Output side optical fiber fixing portion,
Wherein the optical fiber grating sensor further comprises a support for fixing the optical fiber grating sensor. 3. The method of claim 2,
Wherein the end portion side optical fiber fixing portion is formed by looping the optical fiber around the optical fiber fixing portion, and the optical fiber fixing portion is fixed by a fixing agent. The method of claim 3,
And a mounting groove is formed on the outer circumference of the end optical fiber fixing part to form an optical fiber loop and to be wound and fixed. 5. The method of claim 4,
Wherein an input end and an output end of the optical fiber are fixed to the input / output side optical fiber fixing part by a fixing agent. 6. The method of claim 5,
Wherein the pressure displacement sensor further comprises an end side support body including the end side optical fiber fixing part. The method according to claim 6,
Wherein the end side support includes a longitudinal fixing groove in which the end side optical fiber fixing portion is supported and fixed,
Wherein the end-side optical fiber fixing part includes a fixing pin inserted into and supported by the fixing groove.
KR1020130015953A 2013-02-14 2013-02-14 Optical fiber displacement sensor having temperature compensation structure KR20140102513A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105115440A (en) * 2015-08-19 2015-12-02 华中科技大学 Partial displacement measurement method based on fiber grating sensor
KR101653908B1 (en) * 2015-02-25 2016-09-02 부경대학교 산학협력단 Optical fiber pressure sensor and pressure measuring method using the same

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101653908B1 (en) * 2015-02-25 2016-09-02 부경대학교 산학협력단 Optical fiber pressure sensor and pressure measuring method using the same
CN105115440A (en) * 2015-08-19 2015-12-02 华中科技大学 Partial displacement measurement method based on fiber grating sensor
CN105115440B (en) * 2015-08-19 2017-09-12 华中科技大学 A kind of local displacement measuring method based on fiber-optic grating sensor

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