JP2007240247A - In-metal tube optical fiber coil type vibration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-metal tube optical fiber coil type vibration sensor which can be used under a high-temperature condition, has a sufficient environment resistance and enables a coil having a small diameter to be made up. <P>SOLUTION: A heatproof optical fiber (3) is made up by forming a metal film (2) on the outer circumferential surface of an optical fiber (1) composed of a core (1a) and a cladding (1d), and then inserted into a metal tube (5) and filled up with a filling material (7), and then wound in the form of a spiral coil and sealed at its ends (5a, 5b) by a sealing material (6). Since the heatproof optical fiber (3) which is employed in the sensor, has the metal film (2) formed on its outer circumferential surface, and is inserted into the metal tube (5), the sensor is made excellent in heat resistance and can be used under the high-temperature condition. Furthermore, since the heatproof optical fiber (3) is not exposed outside, the metal film (2) is not oxidized even under a high-temperature oxidizing gas atmosphere, and the sufficient environment resistance is realized. Any tension is hardly applied to the heatproof optical fiber (3) when bending the sensor, thereby enabling the coil having the small diameter to be made up. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an optical fiber coil type vibration sensor with a metal tube, and more specifically, an optical fiber coil type with a metal tube that can be used at high temperatures, has sufficient environmental resistance, and can make a small diameter coil. The present invention relates to a vibration sensor.

2. Description of the Related Art Conventionally, an optical fiber coil containing a metal tube in which an optical fiber composed of a core and a clad is put in a metal tube and wound in a coil shape is known (for example, see Patent Document 1).
On the other hand, a vibration sensor is known in which a heat-resistant optical fiber having a metal film formed on the outer periphery of an optical fiber composed of a core and a clad is wound in a coil shape (see, for example, Patent Document 2).

JP 2004-212522 A JP 2005-208025 A

The conventional optical fiber coil containing a metal tube is wound in a coil shape for length adjustment, and cannot be used as a vibration sensor. Also, the optical fiber is not heat resistant. That is, it cannot be used as a vibration sensor at high temperatures.
On the other hand, in a vibration sensor in which a conventional heat-resistant optical fiber is wound in a coil shape, the metal film is exposed to the outside, so that the metal film is oxidized when exposed to high-temperature oxidizing gas, and the optical fiber becomes brittle. There is a problem that the environmental resistance is not sufficient. If the metal film is made of gold, oxidation can be suppressed, but the adhesion with the optical fiber is weak and breakage occurs with a tension of about 7N to 12N, so that it is difficult to bend into a coil with a small diameter.
Accordingly, an object of the present invention is to provide an optical fiber coil type vibration sensor with a metal tube that can be used at high temperatures, has sufficient environmental resistance, and can produce a coil with a small diameter.

In a first aspect, the present invention relates to a heat-resistant optical fiber (3) in which a metal film (2) is formed on the outer peripheral surface of an optical fiber (1) comprising a core (1a) and a clad (1d). An optical fiber coil type vibration sensor (10) including a metal tube is provided, which is inserted into a spiral coil.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the first aspect, the heat-resistant light in which the metal film (2) is formed on the outer peripheral surface of the optical fiber (1) composed of the core (1a) and the clad (1d). Since the fiber (3) is used and is further put in the metal tube (5), it has excellent heat resistance and can be used at high temperatures. Further, since the heat-resistant optical fiber (3) is not exposed to the outside, the metal film (2) is not oxidized even in a high-temperature oxidizing gas atmosphere, and has sufficient environmental resistance. Furthermore, since the tension when bent to form a coil is applied to the metal tube (5) and not so much on the heat-resistant optical fiber (3), a wire having a small diameter can be made without disconnection.

In a second aspect, the present invention provides an optical fiber coil-type vibration sensor (10) containing a metal tube according to the first aspect, wherein the metal film (2) has a melting point of 500 ° C. or higher, Ag, Be, Co, Cr , Cu, Fe, Hf, Mn, Mo, Nb, Ni, Ta, Ti, W, Zr, or a metal formed of one or more layers made of an alloy containing them as a main component An optical fiber coil type vibration sensor (10) with a tube is provided.
In the optical fiber coil type vibration sensor (10) containing a metal tube according to the second aspect, the heat resistance can be improved.

In a third aspect, the present invention provides an optical fiber coil-type vibration sensor (10) containing a metal tube according to the first or second aspect, wherein the metal tube (5) has an elastic modulus of Ag, Be, Optical fiber coil type with a metal tube, characterized by being formed of Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Ta, Ti, W, Zr or an alloy containing them as a main component A vibration sensor (10) is provided.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the third aspect, the workability when bending can be improved.

In a fourth aspect, the present invention provides the optical fiber coil-type vibration sensor (10) with a metal tube according to any one of the first to third aspects, wherein the thickness of the metal tube (5) is 1 mm or less. An optical fiber coil type vibration sensor (10) containing a metal tube is provided.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the fourth aspect, the workability when bending can be improved.

In a fifth aspect, the present invention relates to the heat-resistant light contained in the metal tube (5) in the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of the first to fourth aspects. Provided is an optical fiber coil type vibration sensor (10) containing a metal tube, wherein the length of the fiber (3) is longer than that of the metal tube (5).
In the optical fiber coil-type vibration sensor (10) with a metal tube according to the fifth aspect, the heat-resistant optical fiber (3) contained in the metal tube (5) is longer than the metal tube (5). As a result, almost no tension is applied to the heat-resistant optical fiber (3), and a coil with a small diameter can be made. Also, if the heat-resistant optical fiber (3) is long enough to allow the heat-resistant optical fiber (3) to contact the inner wall of the metal tube (5) at one or more points, vibrations are easily transmitted to the heat-resistant optical fiber (3), and sensitivity is improved. It can be improved.

In a sixth aspect, the present invention relates to the metal tube (10) inserted through the heat-resistant optical fiber (3) in the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of the first to fifth aspects. An end portion (5a, 5b) of 5) is sealed or substantially sealed, and an optical fiber coil type vibration sensor (10) containing a metal tube is provided.
In the above configuration, “sealing” refers to a state where there is no gap, and “substantially sealed” refers to a state where there is a slight gap.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the sixth aspect, the end portions (5a, 5b) of the metal tube (5) are sealed or substantially sealed, so the metal tube (5) It is possible to prevent the oxidizing gas from entering the inside of the metal tube (5) from the end portions (5a, 5b) of the metal tube or leakage of the filler (7) filled in the inside of the metal tube (5).

In a seventh aspect, the present invention relates to an end portion of the metal tube (5) inserted through the heat-resistant optical fiber (3) in the optical fiber coil type vibration sensor (10) containing a metal tube according to the sixth aspect ( 5a, 5b) provides an optical fiber coil type vibration sensor (10) containing a metal tube, which is sealed or substantially sealed with an adhesive.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the seventh aspect, sealing workability can be improved.

In an eighth aspect, the present invention relates to an end of the metal tube (5) inserted through the heat-resistant optical fiber (3) in the optical fiber coil-type vibration sensor (10) containing a metal tube according to the sixth aspect ( 5a and 5b) provide an optical fiber coil-type vibration sensor (10) containing a metal tube, wherein the diameter is reduced and the tube is sealed or substantially sealed.
In the optical fiber coil type vibration sensor (10) with a metal tube according to the eighth aspect, high heat resistance can be maintained.

In a ninth aspect, the present invention relates to an end portion of the metal tube (5) inserted through the heat-resistant optical fiber (3) in the optical fiber coil-type vibration sensor (10) containing a metal tube according to the sixth aspect ( An optical fiber coil type vibration sensor (10) containing a metal tube is provided in which a cap (9) is covered with a cap (9) on 5a, 5b) and is in a sealed or substantially sealed state.
With the optical fiber coil type vibration sensor (10) with a metal tube according to the ninth aspect, the workability of sealing can be improved.

In a tenth aspect, the present invention relates to the metal tube inserted through the heat-resistant optical fiber (3) in the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of the sixth to ninth aspects. An optical fiber coil type vibration sensor (10) containing a metal tube is provided, wherein the inside of (5) is filled with a filler (7).
In the optical fiber coil type vibration sensor (10) with a metal tube according to the tenth aspect, the filler (7) transmits vibration to the heat-resistant optical fiber (3), so that the sensitivity can be improved. In addition, since the edge part (5a, 5b) of the metal pipe (5) is sealed or substantially sealed, the filler (7) does not leak.

In an eleventh aspect, the present invention provides a protective tube characterized in that the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of the first to tenth aspects is fixed to a substrate (20). An incoming optical fiber coil type vibration sensor (100) is provided.
In the optical fiber coil type vibration sensor (100) with a metal tube according to the eleventh aspect, since the optical fiber coil type vibration sensor (10) with a metal tube is fixed to the substrate (20), operations such as transportation, storage and installation are performed. The handling with becomes easy.

  The optical fiber coil type vibration sensor (10, 100) containing a metal tube of the present invention can be used at a high temperature, has sufficient environmental resistance, and can be a small diameter coil.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor 10 with a metal tube according to a first embodiment.
This optical fiber coil type vibration sensor 10 with a metal tube includes a metal tube 5 wound around a spiral coil and a heat-resistant optical fiber 3 inserted into the metal tube 5 with a length that meanders in the metal tube 5. And a sealing material 6 that seals both ends of the metal tube 5.

  The metal tube 5 is, for example, a copper or stainless steel pipe having an inner diameter of 0.5 mm and a wall thickness of 0.1 mm to 1 mm, and is wound around a 5-turn coil having a diameter of about 20 mm.

As shown in FIG. 2, the heat-resistant optical fiber 3 has a configuration in which a metal film 2 is formed on the outer peripheral surface of a quartz or glass optical fiber 1 composed of a core 1a and a cladding 1d.
The metal film 2 is, for example, gold or nickel.
As a numerical example, the core 1a has a diameter of 10 μm, the cladding 1d has a diameter of 125 μm, and the metal film 2 has a thickness of 15 μm.

  The sealing material 6 is an inorganic adhesive.

FIG. 3 is a flowchart showing a manufacturing procedure of the optical fiber coil type vibration sensor 10 with a metal tube.
In step S1, the metal tube 5 is annealed at 800 ° C. in a reducing atmosphere.
In step S <b> 2, the heat-resistant optical fiber 3 is inserted into the metal tube 5 so as to meander in the metal tube 5.
In step S3, the metal tube 5 is wound in a spiral coil shape. When the kink state occurs when the metal tube 5 is bent, the kink can be prevented by bending the metal tube 5 with particles of 10 μm or less.
In step S4, the metal tube 5 wound around the coil is annealed at 800 ° C. in a reducing atmosphere.
In step S <b> 5, the end portions 5 a and 5 b of the metal tube 5 are sealed with the sealing material 6. For example, several mm of silica-based inorganic adhesive such as a trade name “Ceramabond 618” is filled in the end portions 5a and 5b of the metal tube 5 and baked at 93 ° C. for 2 hours at + 260 ° C. to be cured.

According to the optical fiber coil type vibration sensor 10 with the metal tube of the first embodiment, the following effects can be obtained.
(1) Since the heat-resistant optical fiber 3 in which the metal film 2 is formed on the outer peripheral surface is used and is further put in the metal tube 5, it has excellent heat resistance and can be used at high temperatures. Further, since the heat-resistant optical fiber 3 is not exposed to the outside, the metal film 2 is not oxidized even in a high-temperature oxidizing gas atmosphere, and has sufficient environmental resistance.
(2) Since the heat-resistant optical fiber 3 contained in the metal tube 5 meanders, the tension when bent is hardly applied to the heat-resistant optical fiber 3, and a coil having a small diameter can be made. Further, since the heat-resistant optical fiber 3 is in contact with the inner wall of the metal tube 5 at several points, vibration is easily transmitted to the heat-resistant optical fiber 3 and the sensitivity can be improved.
(3) Since the end portions 5 a and 5 b of the metal tube 5 are sealed, the oxidizing gas can be prevented from entering the inside of the metal tube 5 from the end portions 5 a and 5 b of the metal tube 5.

FIG. 4 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor 100 with a metal tube according to the second embodiment. FIG. 5 is a front view of the same.
In this optical fiber coil type vibration sensor 100 with a metal tube, the optical fiber coil type vibration sensor 10 with a metal tube according to the first embodiment is fixed to a substrate 20.
The substrate 20 is, for example, a stainless plate or a ceramic plate.
The fixing method is, for example, by paste or spraying.

  According to the optical fiber coil type vibration sensor 100 with the metal tube of the second embodiment, handling in operations such as transportation, storage, and installation becomes easy.

FIG. 6 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor 10 with a metal tube according to a third embodiment.
This optical fiber coil type vibration sensor 10 with a metal tube is obtained by filling the metal tube 5 with a filler 7 in the optical fiber coil type vibration sensor 10 with a metal tube according to the first embodiment.
The filler 7 is powder (for example, alumina powder or magnesium oxide powder) or liquid (for example, mercury).

  Filling the metal tube 5 with the filler 7 is performed after step S2 in FIG. 3 and before step S3.

  According to the optical fiber coil-type vibration sensor 100 with the metal tube of the third embodiment, the filler 7 transmits vibration to the heat-resistant optical fiber 3, so that the sensitivity can be improved. Since the filler 7 seals the end portions 5a and 5b of the metal tube 5, it does not leak.

FIG. 7 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor 10 with a metal tube according to a fourth embodiment.
In this optical fiber coil type vibration sensor 10 with a metal tube, instead of sealing the ends 5a and 5b of the metal tube 5 with the sealing material 6 in the optical fiber coil type vibration sensor 10 with a metal tube according to the third embodiment, The end portions 5a and 5b of the metal tube 5 are reduced in diameter by extrusion or drawing using a die or by mechanical caulking so as to be in a substantially sealed state.

FIG. 8 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor 10 with a metal tube according to a fifth embodiment.
In this optical fiber coil type vibration sensor 10 with a metal tube, instead of sealing the ends 5a and 5b of the metal tube 5 with the sealing material 6 in the optical fiber coil type vibration sensor 10 with a metal tube according to the third embodiment, The cap 9 is put on the end portions 5a and 5b of the metal tube 5 so as to be substantially sealed.
The cap 9 is formed by, for example, covering a cylindrical thin copper sleeve on the end portions 5a and 5b of the metal tube 5 and then reducing the diameter by mechanical caulking.

  The optical fiber coil type vibration sensor with a metal tube of the present invention can be used to detect vibration in a high temperature environment such as a rock near a volcanic magma.

It is a partial cross section top view which shows the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 1. FIG. It is sectional drawing of a heat resistant optical fiber. It is a flowchart which shows the manufacture procedure of the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 1. FIG. It is a partial cross section top view which shows the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 2. FIG. It is a front view which shows the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 2. FIG. It is a partial cross section top view which shows the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 3. FIG. FIG. 6 is a partial cross-sectional top view showing an optical fiber coil type vibration sensor with a metal tube according to a fourth embodiment. It is a partial cross section top view which shows the optical fiber coil type | mold vibration sensor containing a metal tube concerning Example 5. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 1a Core 1d Cladding 2 Metal film 3 Heat-resistant optical fiber 5 Metal tube 6 Sealing material 7 Filling material 9 Cap 10 Optical fiber coil type vibration sensor with metal tube 100 Optical fiber coil type vibration sensor with metal tube

Claims (11)

  A heat-resistant optical fiber (3) having a metal film (2) formed on the outer peripheral surface of an optical fiber (1) composed of a core (1a) and a clad (1d) is inserted into a metal tube (5) to form a spiral coil. An optical fiber coil type vibration sensor (10) containing a metal tube.   The optical fiber coil type vibration sensor (10) with a metal tube according to claim 1, wherein the metal film (2) is Ag, Be, Co, Cr, Cu, Fe, Hf, Mn, Mo having a melting point of 500 ° C or higher. , Nb, Ni, Ta, Ti, W, Zr or a single layer or a plurality of layers made of an alloy containing them as a main component. ).   The optical fiber coil type vibration sensor (10) with a metal tube according to claim 1 or 2, wherein the metal tube (5) has an elastic modulus of 200 GPa or less, Ag, Be, Co, Cr, Cu, Fe, Hf. , Mn, Mo, Nb, Ni, Ta, Ti, W, Zr, or an optical fiber coil type vibration sensor (10) containing a metal tube, characterized in that it is made of an alloy containing them as a main component.   The optical fiber coil type vibration sensor (10) with a metal tube according to any one of claims 1 to 3, wherein the metal tube (5) has a thickness of 1 mm or less. Optical fiber coil type vibration sensor (10).   The length of the heat-resistant optical fiber (3) contained in the metal tube (5) is the optical fiber coil-type vibration sensor (10) containing a metal tube according to any one of claims 1 to 4. An optical fiber coil type vibration sensor (10) containing a metal tube, characterized by being longer than the metal tube (5).   In the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of claims 1 to 5, ends (5a, 5b) of the metal tube (5) inserted through the heat-resistant optical fiber (3). Is a sealed or substantially sealed state, an optical fiber coil type vibration sensor (10) containing a metal tube.   7. An optical fiber coil type vibration sensor (10) with a metal tube according to claim 6, wherein the ends (5a, 5b) of the metal tube (5) inserted through the heat-resistant optical fiber (3) are sealed with an adhesive. An optical fiber coil type vibration sensor (10) containing a metal tube, characterized by being in a stopped state.   In the optical fiber coil type vibration sensor (10) with a metal tube according to claim 6, the ends (5a, 5b) of the metal tube (5) inserted through the heat-resistant optical fiber (3) are reduced in diameter. An optical fiber coil type vibration sensor (10) containing a metal tube, which is substantially sealed.   The optical fiber coil type vibration sensor (10) with a metal tube according to claim 6, wherein a cap (9) is provided at an end (5a, 5b) of the metal tube (5) through which the heat-resistant optical fiber (3) is inserted. An optical fiber coil type vibration sensor (10) with a metal tube, which is covered and substantially sealed.   An optical fiber coil type vibration sensor (10) with a metal tube according to any one of claims 6 to 9, wherein a filler (7) is provided inside the metal tube (5) through which the heat-resistant optical fiber (3) is inserted. ) Filled metal tube optical fiber coil type vibration sensor (10).   An optical fiber coil type vibration sensor (100) containing a protective tube, wherein the optical fiber coil type vibration sensor (10) containing a metal tube according to any one of claims 1 to 10 is fixed to a substrate (20). .

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