CN101210832A - Fiber Bragg Grating Hydrophone - Google Patents

Abstract

A fiber grating hydrophone, characterized in that it includes: a support tube, the support tube is the main body of the fiber grating hydrophone, the support tube is cylindrical; a first end cover and a second end cover, the The first end cap and the second end cap are respectively installed on the two ends of the support cylinder, and the center of the first end cap and the second end cap has a small hole; a first elastic body 4 and a second elastic body, the first The elastic body and the second elastic body are located on both sides of the support tube near the end; a fiber grating, the fiber grating is located in the middle of the support tube, and the pigtail of the fiber grating runs through the first elastic body and the second elastic body, And lead out through the small holes on the first end cap and the second end cap.

Description

Fiber Bragg Grating Hydrophone

technical field

The invention relates to the technical field of optical fiber sensors, in particular to an optical fiber grating hydrophone.

Background technique

Compared with the corresponding conventional sensors, optical fiber sensors also have obvious advantages in terms of sensitivity, dynamic range, and reliability. They are particularly prominent in the fields of national defense and military applications, and are listed as key national defense technologies by many countries.

Optical fiber hydrophone is an instrument that detects signals such as pressure and sound in liquids by using the light transmission characteristics of optical fiber and various modulation effects generated by its interaction with the surrounding environment. Compared with traditional piezoelectric sensors, it has the following main advantages: wide frequency band, high sound pressure sensitivity, no electromagnetic interference, light weight, can be designed into any shape, and combines information sensing and optical information transmission Etc.

In view of the above technical advantages of fiber optic hydrophones, it can meet the requirements of various developed countries in the fields of petroleum and military affairs, and research has been actively carried out in this area.

Among the common intensity-modulated, digital, and fiber-optic grating hydrophones, fiber-optic grating hydrophones are currently the main research direction.

Fu Haiwei and Fu Junmei et al. reported a fiber grating pressure sensor, which uses the method of bonding one end of the fiber grating to the linear diaphragm for sensitization, and drives the fiber grating to generate pressure through the displacement of the circular diaphragm in the normal direction. strain to detect pressure. The optical fiber pressure sensor produced in this way requires prestressed bonding of optical fibers, and adopts point bonding, the process is complicated, the linear diaphragm is thin, it is difficult to measure high pressure, and it is sensitive to temperature changes.

Therefore, how to reduce the volume of the fiber optic hydrophone probe while ensuring high pressure measurement sensitivity is one of the important technologies that must be solved for the large-scale application of fiber optic hydrophones.

Contents of the invention

technical problem to be solved

In view of this, the main purpose of the present invention is to provide a fiber Bragg grating hydrophone to reduce the volume of the fiber Bragg grating hydrophone and ensure the high sensitivity of the fiber Bragg grating hydrophone.

Technical solutions

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A kind of optical fiber grating hydrophone of the present invention is characterized in that, comprises:

A support cylinder, the support cylinder is the main body of the fiber grating hydrophone, and the support cylinder is cylindrical;

A first end cover and a second end cover, the first end cover and the second end cover are respectively installed at both ends of the support cylinder, and a small hole is opened in the center of the first end cover and the second end cover;

A first elastic body 4 and a second elastic body, the first elastic body and the second elastic body are located on both sides near the end in the support tube;

A fiber grating, the fiber grating is located in the middle of the support cylinder, the pigtail of the fiber grating runs through the first elastic body and the second elastic body, and is drawn out through the small holes on the first end cap and the second end cap .

The first end cap and the second end cap are sleeved and sealed with the two ends of the support cylinder through threads or bonding.

Axisymmetrically distributed long holes are also opened in the axial middle of the side wall of the support cylinder.

Wherein the first elastic body and the second elastic body are solidified and formed in the support cylinder, and are closely bonded to the optical fiber grating.

Wherein the first elastic body and the first end cap, the second elastic body and the second end cap respectively form a sealed air chamber.

The material of the first elastic body and the second elastic body is silicon rubber or polyurethane rubber.

Between the first elastic body and the second elastic body and the inner wall of the support cylinder, between the first end cap and the second end cap and the support cylinder, and in the small holes on the first end cap and the second end cap Coated with sealant.

Beneficial effect

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. Small size. The volume of the fiber grating hydrophone can be largely reduced through the method of encapsulating the tubular polymer elastomer. In this technical solution, the outer diameter of the support cylinder may be less than 10 mm.

2. The sound pressure sensitivity is easy to control. The sound pressure sensitivity of the fiber grating hydrophone can be adjusted by adjusting the outer diameter of the support cylinder 1, the thickness of the elastic bodies 4 and 5, and material parameters such as elastic modulus.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings, wherein:

Fig. 1 is a structural sectional view of a fiber grating hydrophone provided by the present invention.

FIG. 2 is a top view of FIG. 1 .

Detailed ways

As shown in FIG. 1 , FIG. 1 is a structural sectional view of the fiber grating hydrophone provided by the present invention. The fiber grating hydrophone includes: a support cylinder 1, the support cylinder 1 is the main body of the fiber grating hydrophone, and the support cylinder 1 is cylindrical. A first end cap 2 and a second end cap 3, the first end cap 2 and the second end cap 3 are respectively installed at both ends of the support cylinder 1 for sealing; the first end cap 2 and the second end cap There are small holes 7 and 8 in the center of 3, which are used to lead out the pigtail of the optical fiber 6; a first elastic body 4 and a second elastic body 5, the first elastic body 4 and the second elastic body 5 are located in the support cylinder 1 The two sides close to the end are used to feel the sound pressure and generate deformation. The material of the first elastic body 4 and the second elastic body 5 is silicon rubber or polyurethane rubber. The first elastic body 4 and the second elastic body 5 have a sealed Effect: a fiber grating 6, the fiber grating 6 is located in the middle of the support cylinder 1, the pigtail of the fiber grating 6 runs through the first elastic body 4 and the second elastic body 5, and passes through the first end cap 2 and The small holes 7, 8 on the second end cap 3 lead out.

The first end cap 2 and the second end cap 3 are sleeved and sealed with the two ends of the support cylinder 1 by threads or bonding.

Axisymmetrically distributed long holes 9 are also opened in the axial middle of the side wall of the support cylinder 1 . The long hole 9 communicates the inside of the hydrophone with the outside, so that the sound pressure can enter the inside of the hydrophone and act on the elastic body.

The first elastic body 4 and the second elastic body 5 are solidified and formed in the support cylinder 1 , and are closely bonded to the fiber grating 6 . In this way, when the elastic body is deformed by the sound pressure, the strain can be transmitted to the fiber grating 6, so that the fiber grating 6 generates a corresponding strain.

A sealed air chamber is formed between the first elastic body 4 and the first end cap 2 , and between the second elastic body 5 and the second end cap 3 . In this way, the end of the elastic body in contact with the airtight cavity can move within a certain range, thereby increasing the sensitivity of the hydrophone.

Among them, between the first elastic body 4 and the second elastic body 5 and the inner wall of the support tube 1, between the first end cover 2 and the second end cover 3 and the support tube 1, and between the first end cover 2 and the second end cover 2 The small holes 7 and 8 on the end cover 3 are coated with sealant.

When the fiber grating hydrophone is placed in water (or other liquids), water (or other liquids) enters from the hole 9 and acts on the opposite end faces of the first elastic body 4 and the second elastic body 5, thereby making the elastic The body is compressed, and the elastic body is pressed to produce displacement in the direction of the end cap. Since the elastic body and the fiber grating 6 are closely bonded, the fiber grating is driven to generate strain. For fiber gratings, the variation of the reflected wavelength is proportional to the applied strain, so the external pressure can be obtained by detecting the variation of the wavelength.

At the same time, the sensitivity of the fiber grating hydrophone can be adjusted by adjusting the outer diameter of the support cylinder 1, the thickness of the elastic bodies 4 and 5, and material parameters such as elastic modulus.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. an optical fiber grating sonic device is characterized in that, comprising:

One support tube, this support tube are the main body of optical fiber grating sonic device, and this support tube is a cylinder type;

One first end cap and second end cap, this first end cap and second end cap are installed in the two ends of support tube respectively, and the center of this first end cap and second end cap has aperture;

One first elastic body 4 and second elastic body, this first elastic body and second elastic body are positioned at the both sides of support tube near the end;

One fiber grating, this fiber grating is positioned at the centre of support tube, and the tail optical fiber of this fiber grating runs through described first elastic body and second elastic body, and draws by the aperture on described first end cap and second end cap.

2. optical fiber grating sonic device according to claim 1 is characterized in that, wherein said first end cap and second end cap are by the two ends socket and the sealing of screw thread or bonding and support tube.

3. optical fiber grating sonic device according to claim 1 is characterized in that, the side-wall shaft of wherein said support tube also has the slotted hole that rotational symmetry distributes to the middle part.

4. optical fiber grating sonic device according to claim 1 is characterized in that, wherein said first elastic body and second elastic body solidify to form in support tube, closely bond with fiber grating.

5. optical fiber grating sonic device according to claim 1 is characterized in that, constitutes the confined air air cavity respectively between wherein said first elastic body and first end cap, second elastic body and second end cap.

6. optical fiber grating sonic device according to claim 1 is characterized in that, wherein said first elastic body, the second elastomeric material is silicon rubber or urethane rubber.

7. according to claim 1 or 2 or 4 or 5 described optical fiber grating sonic devices, it is characterized in that, between the inwall of wherein said first elastic body and second elastic body and support tube, scribble fluid sealant between first end cap and second end cap and the support tube and in the aperture on first end cap and second end cap.

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