JP2010079061A - Mounting structure of optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of an optical fiber, which stably fixes the optical fiber for a long term and has a high degree of freedom of selection of the coating of the optical fiber. <P>SOLUTION: A first preform glass 24A and a second preform glass 24B are inserted in the optical fiber 14 and housed in a through-hole 23. The second preform glass 24B is placed on the lower side and the axis direction of the through-hole 23 is directed substantially vertical, the inserted part 21 is heated with a heater H to melt the first preform glass 24A. Thereafter, the inserted part 21 is cooled and hardened to fasten the optical fiber 14 in a hermetic seal state. Thus, a high fixing strength is kept for a long term. The fixing is performed by using a low melting point glass 24, the coating of the optical fiber 14 has the high flexibility of selection among polyimide resin, ultraviolet setting type resin and metal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical fiber sensor mounting structure that detects physical quantities such as acceleration, displacement, and inclination.

As a conventional physical quantity detection sensor, a sensor that extracts a change in electric signal based on changes in electric resistance, inductance, and capacitance is generally used.
Such an electrical physical quantity sensor is easily affected by electromagnetic interference and is not suitable for long-distance signal transmission. Furthermore, in the case of the laying situation of the physical quantity measurement object, for example, in the case of a flammable atmosphere, it has been necessary to have a configuration with special explosion-proof measures.

In recent years, many optical fiber type physical quantity detection sensors have been proposed as sensors that can cope with such problems.
Among them, one using an optical fiber in which a fiber Bragg grating (hereinafter abbreviated as FBG) is written has high accuracy, and a plurality of sensors can be multiplexed and installed on one optical fiber cable. Etc.
For this reason, it is possible to perform various measurements simultaneously at a plurality of measurement positions on a monitoring object attached in a wide range with a simple system configuration. Furthermore, a physical quantity measurement object that requires an explosion-proof structure because it uses the wavelength of light. It is attracting attention as having little influence from the facility situation.

Generally, when an FBG is used as a sensor for detecting various physical quantities, the optical fiber containing the FBG causes a stretching distortion or the like due to direct or indirect bending strain of the object to be measured and detects the physical quantity. It is necessary to have a fixing method that can transmit stably and stably. For this reason, a method using an adhesive has been proposed in order to fix the optical fiber to the holding portion (see, for example, Patent Documents 1 and 2).
Further, as a fixing method other than the adhesive, an optical fiber fixing method using soldering, brazing, welding, or the like, which is a metal joining means, has been proposed (for example, see Patent Documents 3 and 4).

Japanese Patent Laid-Open No. 11-173820 JP 2004-361264 A JP 2003-255151 A JP 2006-194704 A

However, in the past, when an optical fiber is fixed to a holding part using an adhesive, the optical fiber fixing strength may decrease due to the long-term use of the optical fiber sensor. Is difficult.
In the optical fiber fixing by the above method, there is a possibility that a deviation may occur in the adhesive strength in each optical fiber sensor, and this deviation causes the measurement accuracy to deteriorate and the stable measurement performance cannot be obtained. Can be mentioned.
In addition, in fixing an optical fiber by soldering, it is necessary to apply a metal coating to the optical fiber. Therefore, an increase in manufacturing cost due to the metal coating and a complicated manufacturing method are problems.
In addition, for fixing an optical fiber by soldering, an optical fiber coated with a metal coating by electroless plating or sputtering, and a fixing method using Au—Sn solder have been proposed. Advantages of this method include reduction of fixed strength variation and improvement of long-term stability.
However, as a problem or restriction of this method,
・ Since Au is included, solder material is expensive. ・ Necessity of material restriction or surface treatment of fixing member in consideration of solder wettability ・ Metal coating on optical fiber is necessary for fixing with solder.

  An object of the present invention is to provide an optical fiber mounting structure that can be stably fixed for a long period of time, has a low cost, and has a high degree of freedom in selecting an optical fiber.

  The optical fiber attachment structure of the present invention is an optical fiber attachment structure attached to a pair of holding portions in which both ends of an optical fiber having a diffraction grating formed at the center are relatively displaced, and the pair of holding portions are It has insertion parts formed with through holes through which the optical fiber passes, and between these insertion parts and the optical fiber has a hermetic seal shape with a low melting point glass whose thermal expansion coefficient is smaller than the thermal expansion coefficient of the holding part It is characterized by being fastened and fixed to.

  In the invention of this configuration, the holding portion and both side portions of the diffraction grating of the optical fiber are fastened and fixed in a hermetic seal shape with low-melting glass in the through hole, so that a high fixing strength is obtained and the fixing strength is maintained for a long time. Can be maintained. For this reason, compared with the optical fiber attachment structure using an adhesive agent etc., there is little possibility that the fixed strength deviation will occur between the optical fiber sensors, and an optical fiber sensor having stable measurement accuracy can be obtained.

In addition, since it is fastened and fixed in a hermetic seal shape with a low melting point glass, there is a high degree of freedom in selecting the coating of the usable optical fiber, and the selection can be made in consideration of the cost, sensor application, type, and the like.
For this reason, the coating of the optical fiber can be manufactured by a resin coating such as polyimide, and the coating cost of the optical fiber can be reduced at a low cost.

  In the optical fiber mounting structure of the present invention, each of the holding parts includes a support part connected to the insertion part, and one of the support parts is connected to a fixed part fixed to the detected part, and the support part Of these, the other is connected to the weight portion, and the weight portion and the fixed portion are preferably connected to each other via a substantially plate-like elastic member.

  In the invention of this configuration, it is not necessary to fix the optical fiber directly to the fixing portion and the weight portion, and it can be indirectly fixed via the holding portion, so that the assembly adjustment of the optical fiber sensor can be performed more easily. it can.

In the optical fiber mounting structure of the present invention, it is preferable that the insertion portion and the support portion are integrated with each other by metal joining means.
In the invention of this configuration, by making the holding portion into a shape that is divided into the support portion and the insertion portion, it is possible to increase the selectivity of the material and the degree of freedom of the shape of each of the support portion and the insertion portion.

In the optical fiber mounting structure of the present invention, it is preferable that the insertion portion is formed in a multistage shape in which the diameter dimension of the through hole is different along the axial direction.
In the invention of this configuration, the cross-sectional shape of the through hole of the holding portion is a multistage type, so that it is possible to prevent the molten glass from flowing out of the through hole when the low-melting glass is heated and melted.

In the optical fiber mounting structure of the present invention, it is preferable that the insertion portion includes an optical fiber protection portion that protrudes outside the two openings of the through hole.
In the invention of this configuration, by providing the optical fiber protection part outside the opening part, the optical fiber and the fixing part can be formed into a continuous shape, and the place where stress is concentrated can be eliminated to prevent the optical fiber from being broken. It becomes.

The optical fiber mounting structure of the present invention preferably has a configuration in which the cross-sectional shape of the through hole is other than circular.
In the invention of this configuration, the same effects as described above can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, in description of each embodiment, the same component is attached | subjected with the same code | symbol and description is abbreviate | omitted.
A first embodiment will be described with reference to FIGS. FIG. 1 is a perspective view of an acceleration sensor according to a first embodiment of the present invention.
As shown in FIG. 1, an acceleration sensor 1 as an optical fiber sensor includes a sensing unit 10 that elastically deforms due to an inertial force due to acceleration, and an optical fiber 14 that is a linear member that follows the elastic deformation of the sensing unit 10. These are housed in a detector housing (not shown).

  The sensing unit 10 is manufactured by cutting using a metal material such as stainless steel, and has a rectangular parallelepiped fixing portion 11 attached to the detector housing, and a rectangular parallelepiped shape that receives an inertial force due to an acceleration change of the fixing portion 11. And a leaf spring 13 as an elastic member which is a plate-like elastic body connecting the fixed portion 11 and the weight portion 12.

The sensing unit 10 has a fixed part 11 and a weight part 12 with dimensions of, for example, a vertical direction of 12 mm, a horizontal direction of 25 mm, and a depth direction of 20 mm, and a leaf spring 13 having a thickness of 0.3 mm and a horizontal direction of 10 mm. , Formed in a dimension of 20 mm in the depth direction.
In addition, a pair of holding portions 20 are provided on the fixing portion 11 and the weight portion 12, and the optical fiber 14 is fixed in parallel and away from the leaf spring 13 by the holding portion 20.

The holding part 20 is made of a metal material such as stainless steel, and has an insertion part 21 formed in a rectangular parallelepiped shape having a through hole 23 through which the optical fiber 14 is inserted, and a plate shape formed integrally with the insertion part 21. The support part 22 which is a member is provided. The support portion 22 is a plate-like member having a plane having substantially the same area as the joint surfaces of the fixed portion 11 and the weight portion 12 to which metal joining such as welding and soldering is performed.
Specifically, the insertion part 21 is a rectangular part having a through hole 23 with a diameter of 1.5 mm, and has a length of 10 mm, a horizontal direction of 3.5 mm, and a height of 2.5 mm. The support part 22 is a stainless steel member, and is formed in dimensions of 25 mm in the horizontal direction, 20 mm in the depth direction, and 0.5 mm in the thickness direction.

  Further, the optical fiber 14 has an FBG 15 as a diffraction grating at a position facing the leaf spring 13, and both ends of the FBG 15 are provided in a support portion 22 that is metal-bonded to the fixed portion 11 and the weight portion 12, respectively. The through hole 23 of the inserted portion 21 is inserted, and the gap between the through hole 23 and the optical fiber 14 is filled with a low-melting glass 24 to be fastened and fixed.

Next, a method for fixing the optical fiber 14 to the holding unit 20 will be described with reference to FIGS. FIG. 2 is a schematic view for explaining a method of forming the optical fiber mounting structure for the acceleration sensor according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view for explaining a method of forming the optical fiber mounting structure for the acceleration sensor according to the first embodiment of the present invention. FIG. 4 is a perspective view of the optical fiber mounting structure of the acceleration sensor according to the first embodiment of the present invention.
As shown in FIG. 2, it is a kind of low melting point glass 24 before welding formed into a hollow cylindrical shape whose outer diameter is equal to or smaller than the inner diameter of the through hole 23 and whose inner diameter is equal to or larger than the outer diameter of the optical fiber 14. An optical fiber 14 including a plurality of first preform glasses 24A and a second preform glass 24B having the same shape as the first preform glass 24A and having a melting point higher than that of the first preform glass 24A. Is inserted into one of the two.
At this time, the first preform glass 24 </ b> A is continuously arranged from the side far from the FBG 15, and the second preform glass 24 </ b> B is inserted at a position closest to the FBG 15.

  The first preform glass 24A is inserted first through the through hole 23 on the side close to the leaf spring 13, and then the second preform glass 24B is inserted through the through hole 23. The one preform glass 24 </ b> A and the second preform glass 24 </ b> B are accommodated in the through holes 23. Thereafter, the holding unit 20 is arranged with its orientation adjusted so that the second preform glass 24B is on the lower side and the axial direction of the through hole 23 is substantially vertical.

  Next, as shown in FIG. 3, the insertion portion 21 through which the optical fiber 14 is inserted is mechanically sandwiched by a clip-type heater H, and heat is applied from the contact portion between the insertion portion 21 and the heater H to insert the insertion portion 21. The holding part 20 including the is heated locally and the first preform glass 24 </ b> A inside the through hole 23 is heated and melted. By maintaining this molten state for a predetermined time, the first preform glass 24 </ b> A adheres to the inner wall of the through hole 23. Then, the optical fiber 14 is tightened and fixed in a hermetic seal shape in the through hole 23 by cooling to room temperature and curing the first preform glass 24 </ b> A in the insertion portion 21.

The relationship between the melting point T1 of the first preform glass 24A, the melting point T2 of the second preform glass 24B, and the heating temperature TH of the heater H is such that T2>TH> T1.
For this reason, since only the first preform glass 24A melts when heated by the heater H, the second preform glass 24B is used as a bottom lid for preventing outflow when the first preform glass 24A is heated and melted. can do.

As shown in FIG. 4, similarly to these series of steps, the optical fiber 14 is fastened and fixed to the other insertion portion in the through hole 23, so that both ends of the FBG 15 are in the low melting glass 24 in the through hole 23 of the insertion portion 21. Thus, the optical fiber mounting structure 2 is formed that is fastened and fixed in a hermetic seal shape.
Further, the support portion 22 of the optical fiber attachment structure 2 is fixed to the fixing portion 11 and the weight portion 12 by metal joining means such as welding or caulking. In addition, when fixing, it fixes in the state which applied some tension so that FBG15 may not loosen.

  As a result, when acceleration due to vertical vibration is applied to the acceleration sensor 1, the weight 12 is displaced up and down by inertial force, causing the FBG 15 to undergo expansion and contraction distortion. The expansion / contraction strain of the FBG 15 becomes a reflection wavelength change or a transmission wavelength change of light from the FBG. In addition, since the amount of expansion / contraction strain of the FBG 15 depends on the amount of displacement of the weight 12 that correlates with the increase / decrease in acceleration, it is possible to measure the magnitude of acceleration by measuring the amount of change in reflected wavelength or the amount of change in transmitted wavelength. An acceleration sensor 1 can be obtained.

Therefore, in the first embodiment, the following operational effects can be achieved.
(1) The first preform glass 24 </ b> A and the second preform glass 24 </ b> B are inserted through the optical fiber 14 including the FBG 15. The first preform glass 24 </ b> A and the second preform glass 24 </ b> B are accommodated in the through holes 23. Thereafter, the second preform glass 24B is placed on the lower side, and the axial direction of the through hole 23 is set to a substantially vertical direction.
Next, the insertion part 21 through which the optical fiber 14 is inserted is clamped by the heater H, the insertion part 21 is locally heated, and the first preform glass 24A inside is heated and melted. Then, the optical fiber 14 is tightened and fixed in a hermetic seal shape in the through hole 23 by cooling to room temperature and curing the first preform glass 24 </ b> A in the insertion portion 21.

Therefore, the insertion portion 21 and the optical fiber 14 on both sides of the FBG 15 can be closely adhered to the inner wall of the through hole 23 without gaps, and the optical fiber 14 and the insertion portion 21 are fastened and fixed in a hermetic seal shape. be able to.
Therefore, since a high fixing strength can be obtained and the fixing strength can be maintained for a long period of time, there is less possibility of causing a deviation in measurement accuracy between the acceleration sensors 1 as compared with the fixing of the optical fiber 14 using an adhesive or the like. , Stable acceleration detection by the FBG 15 becomes possible.
Therefore, the acceleration sensor 1 can maintain stable measurement accuracy for a long time.

  In addition, since the fixing is performed by the low melting point glass 24, it is possible to select various coatings such as polyimide, ultraviolet curable resin, and metal coating for the coating of the optical fiber 14 on both sides of the FBG 15.

(2) The insertion part 21 is sandwiched between clip-type heaters H, and heat is applied from the contact part between the insertion part 21 and the heater H to locally heat the holding part 20 including the insertion part 21, so that the inside of the through hole 23 The first preform glass 24A is heated and melted.
For this reason, by setting the heating method to local heating of only the insertion portion 21, the heating time and the heating area are minimized, and even if the coating of the optical fiber 14 is a resin coating such as polyimide, the heating effect is minimized. To the limit.

(3) After the holding part 20 is arranged so that the second preform glass 24B is on the lower side and the axial direction of the through hole 23 is substantially vertical, the first preform glass 24A is Heated and melted.
For this reason, since the axial direction of the through-hole 23 is a vertical direction, the glass after heating and melting spreads uniformly between the outer periphery of the optical fiber 14 and the inner periphery of the through-hole 23, and thus hermetically sealed. Can be tightened and fixed.

(4) When the first preform glass 24A is heated and melted, the relationship between the melting point T1 of the first preform glass 24A, the melting point T2 of the second preform glass 24B, and the heating temperature TH of the heater H is T2> TH > T1.
For this reason, since only the first preform glass 24A melts when heated by the heater H, the second preform glass 24B is used as a bottom lid for preventing outflow when the first preform glass 24A is heated and melted. be able to.

Hereinafter, a second embodiment will be described with reference to FIG. FIG. 5 is an exploded perspective view of a main part of the acceleration sensor according to the second embodiment of the present invention.
As shown in FIG. 5, the holding portion 20 is manufactured by cutting using a metal material such as stainless steel, and is a separate member in which the insertion portion 21 having the through hole 23 and the support portion 22 are divided. These members are integrally formed by joining.
Other configurations are the same as those in the first embodiment, and the description thereof is omitted.

In the method of forming the optical fiber attachment structure 2 of the second embodiment, the optical fiber 14 through which the first preform glass 24A and the second preform glass 24B are inserted is inserted and accommodated in the through hole 23.
Thereafter, the insertion part 21 is adjusted and arranged so that the second preform glass 24B is on the lower side and the axial direction of the through hole 23 is substantially vertical.

And the penetration part 21 is heated locally with the heater H, and internal 1st preform glass 24A is heated and fuse | melted. Then, the optical fiber 14 is tightened and fixed in a hermetic seal shape in the through hole 23 by cooling to room temperature and curing the first preform glass 24 </ b> A in the insertion portion 21.
Further, the other insertion portion 21 also fastens and fixes the optical fiber 14 in the same manner.
Finally, the insertion portion 21 and the support portion 22 are metal-bonded to form the optical fiber attachment structure 2 in which the holding portion 20 and the optical fiber 14 are fastened and fixed.
However, in order to prevent outflow due to remelting of the first preform glass 24A due to heating during metal bonding, the bonding temperature is lower than the melting point of the first preform glass 24A, and the bonding time is heated by the heater H.・ It should be shorter than the melting time.

Therefore, in 2nd Embodiment, there can exist the effect of (1) to (4), and also there can exist the following effect.
(5) The holding part 20 of the second embodiment is a separate member in which the insertion part 21 and the support part 22 are divided. After the insertion part 21 and the optical fiber 14 are fastened and fixed, the insertion part 21 is provided. And the support portion 22 are integrally formed.
For this reason, the holding part 20 is divided into the support part 22 and the insertion part 21, thereby increasing the degree of freedom of the material selectivity and shape of the insertion part 21, the support part 22, and the sensing part 10. It becomes possible to do.

  Further, since the insertion portion 21 is a separate member from the support portion 22, tightening and fixing work can be performed only with the optical fiber 14 and the insertion portion 21. When performing, the work space can be made compact, and the tightening and fixing work can be facilitated. Therefore, the workability of tightening and fixing can be improved.

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a cross-sectional view of a main part of the acceleration sensor according to the third embodiment of the present invention.
As shown in FIG. 6, the holding portion 20 is manufactured by cutting using a metal material such as stainless steel, and includes an insertion portion 21 having a through hole 23 and a support portion 22. The two openings are formed with different diameters.

Specifically, the first opening 23A on the side where the insertion portions 21 face each other, that is, the side close to the leaf spring 13 (see FIG. 1), is formed to have a diameter substantially the same as the diameter of the optical fiber 14 to be inserted. The second opening 23 </ b> B on the side is a through-bore hole formed larger than the diameter of the optical fiber 14.
A gap between the through hole 23 and the optical fiber 14 is filled with the first preform glass 24A.
Other configurations are the same as those in the first embodiment, and the description thereof is omitted.

  In the method of forming the optical fiber mounting structure 2 of the third embodiment, the optical fiber 14 is inserted and accommodated in the through hole 23 from the first opening 23A. Thereafter, the holding part 20 is adjusted and arranged so that the first opening 23A is on the lower side and the axial direction of the through hole 23 is substantially vertical.

  And the penetration part 21 is heated locally with the heater H, and internal 1st preform glass 24A is heated and fuse | melted. Thereafter, the first preform glass 24 </ b> A is cooled to room temperature and cured in the insertion portion 21, thereby forming the optical fiber attachment structure 2 that is filled in a hermetic seal shape in the through hole 23 and that fastens and fixes the optical fiber 14.

Therefore, in the third embodiment, the effects (1) to (3) can be achieved, and the following effects can be achieved.
(6) In the through hole 23 of the insertion portion 21 of the third embodiment, the second opening 23B is formed larger than the diameter of the optical fiber 14, and the opposite first opening 23A is substantially the same as the diameter of the optical fiber 14. It is a through counterbore formed in the same diameter.
For this reason, when the first preform glass 24A is heated and melted in the through hole 23, the first opening 23A is substantially the same as the diameter of the optical fiber 14, so the second preform glass 24B is not used. The first preform glass 24A can be prevented from flowing out of the through hole 23.
Therefore, it is not necessary to use the second preform glass 24B, and the low melting point glass 24 can be a single type, so that the manufacturing cost can be reduced.

Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
FIG. 7 is a perspective view of a main part of the acceleration sensor according to the fourth embodiment of the present invention.
As shown in FIG. 7, the holding part 20 is manufactured by cutting using a metal material such as stainless steel, and includes an insertion part 21 having a through hole 23 and a support part 22. Further, a substantially quadrangular pyramid-shaped optical fiber protection part 21 </ b> A is formed along the optical fiber 14 outside all the openings of the through holes 23.

The optical fiber protection portion 21A is formed of a protective adhesive, and the bottom surface of the quadrangular pyramid is in contact with the side surface of the insertion portion 21 having the opening portion of the through hole 23. They are formed in substantially the same area.
Other configurations are the same as those in the first embodiment, and the description thereof is omitted.

  In the method of forming the optical fiber attachment structure 2 of the fourth embodiment, the optical fiber attachment structure 2 in which the holding portion 20 and the optical fiber 14 are fastened and fixed is formed as in the first embodiment. Thereafter, the protective adhesive 21 </ b> A is formed by applying a protective adhesive in a substantially quadrangular pyramid shape along the optical fiber 14 outside all the openings of the through holes 23.

Therefore, in the third embodiment, the effects (1) to (4) can be achieved, and the following effects can be achieved.
(7) The insertion portion 21 of the fourth embodiment includes an optical fiber protection portion 21 </ b> A along the optical fiber 14 outside the opening of the through hole 23.
For this reason, since the optical fiber 14 and the insertion portion 21 can be fixed in a continuous shape by providing the optical fiber protection portion 21A outside the opening, it is possible to eliminate the stress concentration and prevent the optical fiber 14 from being broken. It becomes.

Although the present invention has been described with reference to preferred embodiments, the present invention is not limited to the above-described embodiments, and modifications and the like within a scope that can achieve the object of the present invention are included in the present invention. is there.
For example, although the cross-sectional shape of the through hole 23 is circular, it is not limited to this and may be an elliptical or polygonal through hole.

  The coating of the optical fiber 14 is a polyimide coating, but is not limited thereto, and may be an ultraviolet curable resin or a metal coating. In the case of a metal coating, it is clamped and fixed with a low melting point glass with the coating remaining, whereas in the case of an ultraviolet curable resin, it is clamped and fixed after it is burned out by the heat of melting of the low melting point glass. For this reason, no matter which coating is selected, the fastening strength and long-term stability are high due to the tightening effect.

Although the shape of the fixing | fixed part 11 and the insertion part 21 was a rectangular parallelepiped, it is not restricted to this, A cylindrical shape and a polygonal shape may be sufficient.
And the insertion part 21 and the insertion part 21 are bonded and fixed to the both ends of the leaf | plate spring 13, and it can apply to this invention also as a form which displaces one leaf | plate spring 13. FIG.

  The holding unit 20 is cut, but may be other than cutting such as casting, forging, and powder molding. In addition, other than metal materials such as stainless steel, ceramics may be used as long as the thermal expansion coefficient is equal to or higher than the value of the low melting point glass to be heated and melted.

  Although the plurality of first preform glasses 24A are inserted into the optical fiber 14, the present invention is not limited to this, and a single first preform glass 24A having a long width may be used.

  The local heating of the holding unit 20 is the local heating from the contact location by the clip-type heater H, but is not limited to this, and may be non-contact heating by high frequency induction heating or a halogen heater, for example.

  Although the support portion 22 and the fixing portion 11 and the weight portion 12 are metal-joined, the present invention is not limited to this, and other fixing methods such as screwing, caulking, and adhesive, and combinations of these two or more fixing methods. May be.

  In the second embodiment, the insertion portion 21 and the optical fiber 14 are fastened and fixed and then joined to the support portion 22. However, the present invention is not limited to this, and after the insertion portion 21 and the support portion 22 are joined, the optical fiber 14 is changed. It may be tightened and fixed. In this case, restrictions on the joining temperature and joining time between the insertion part 21 and the support part 22 can be eliminated.

  The present invention can be used for an acceleration sensor and other measuring devices for detecting physical quantities.

1 is a perspective view of an acceleration sensor according to a first embodiment of the present invention. Schematic for demonstrating the formation method of the optical fiber attachment structure of the acceleration sensor of 1st Embodiment of this invention. The schematic sectional drawing for demonstrating the formation method of the optical fiber attachment structure of the acceleration sensor of 1st Embodiment of this invention. The perspective view of the optical fiber attachment structure of the acceleration sensor of 1st Embodiment of this invention. The disassembled perspective view of the principal part of the acceleration sensor of 2nd Embodiment of this invention. Sectional drawing of the principal part of the acceleration sensor of 3rd Embodiment of this invention. The perspective view of the principal part of the acceleration sensor of 4th Embodiment of this invention.

Explanation of symbols

1. Acceleration sensor (optical fiber sensor)
DESCRIPTION OF SYMBOLS 2 ... Optical fiber mounting structure 10 ... Sensing part 11 ... Fixed part 12 ... Weight part 13 ... Leaf spring (elastic member)
DESCRIPTION OF SYMBOLS 14 ... Optical fiber 20 ... Holding part 21 ... Insertion part 21A ... Optical fiber protection part 22 ... Support part 23 ... Through-hole 23A ... First opening part (opening part)
23B ... Second opening (opening)
24 ... Low melting glass 24A ... First preform glass (low melting glass)
24B ... Second preform glass (low melting point glass)

Claims (6)

An optical fiber attachment structure attached to a pair of holding parts that are relatively displaced at both ends of an optical fiber having a diffraction grating formed in the center,
The pair of holding portions includes insertion portions formed with through holes through which the optical fiber is passed, and the thermal expansion coefficient between the insertion portions and the optical fiber is lower than the thermal expansion coefficient of the holding portion. An optical fiber mounting structure characterized by being fastened and fixed in a hermetic seal shape with a melting point glass. The optical fiber mounting structure according to claim 1,
Each of the holding parts includes a support part connected to the insertion part, and one of these support parts is connected to a fixed part fixed to the detected part, and the other of the support parts is connected to a weight part. The weight portion and the fixed portion are connected to each other via a substantially plate-like elastic member. In the optical fiber mounting structure according to claim 2,
The optical fiber mounting structure, wherein the insertion portion and the support portion are integrated with each other by metal joining means. In the optical fiber mounting structure according to any one of claims 1 to 3,
The optical fiber mounting structure, wherein the insertion portion is formed in a multistage shape in which the diameter dimension of the through hole is different along the axial direction. In the optical fiber mounting structure according to any one of claims 1 to 4,
The optical fiber mounting structure, wherein the insertion portion includes an optical fiber protection portion projecting outside the two openings of the through hole. In the optical fiber mounting structure according to any one of claims 1 to 5,
An optical fiber mounting structure, wherein the through hole has a cross-sectional shape other than circular.

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