CN101210842A - A static pressure self-compensating fiber grating hydrophone - Google Patents

Abstract

The present invention relates to the technical field of optical fiber sensors, and discloses a static pressure self-compensating fiber optic grating hydrophone. The main body of the fiber optic grating hydrophone is a cylindrical support tube 10 with an axially symmetrical structure. The fiber optic grating hydrophone includes : the fiber grating 20 installed on the central axis of the support cylinder 10 is used to measure underwater sound; the first piston 21 and the second piston 22 respectively installed at both ends of the fiber grating 20 are used to transmit the water sound pressure to the fiber grating 20 The first fiber hole 13 and the second fiber hole 14 respectively opened in the central axis of both ends of the support cylinder 10 are used to lead out the pigtail of the fiber grating 20 . By utilizing the invention, the ability of the fiber grating hydrophone to withstand hydrostatic pressure is improved while ensuring the high sensitivity of the fiber grating hydrophone.

Description

A static pressure self-compensating fiber grating hydrophone

technical field

The invention relates to the technical field of optical fiber sensors, in particular to a static pressure self-compensating 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 more sensitive to temperature changes. At the same time, the ability to resist hydrostatic pressure Also relatively poor.

Therefore, how to improve the ability to withstand hydrostatic pressure 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

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a static pressure self-compensating fiber grating hydrophone, so as to improve the ability of the fiber grating hydrophone to withstand hydrostatic pressure while ensuring the high sensitivity of the fiber grating hydrophone.

(2) Technical solution

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

A static pressure self-compensating fiber grating hydrophone, the main body of the fiber grating hydrophone is a cylindrical support tube 10 with an axially symmetrical structure, and the fiber grating hydrophone includes:

The fiber grating 20 installed on the central axis of the support cylinder 10 is used to measure underwater sound;

The first piston 21 and the second piston 22 respectively installed at both ends of the fiber grating 20 are used to transmit the water sound pressure to the fiber grating 20;

A first fiber hole 13 and a second fiber hole 14 respectively opened in the central axis of both ends of the support cylinder 10 are used to lead out the pigtails of the fiber grating 20 .

Axisymmetrically distributed long holes 15 are formed in the axial middle of the side wall of the support cylinder 10 for allowing water to enter the interior of the support cylinder 10 and act on the first piston 21 and the second piston 22 .

The first piston 21 and the second piston 22 are fixedly connected to the fiber grating 20 by bonding, and drive the fiber grating 20 to move axially inside the support cylinder 10 .

Both ends of the support cylinder 10 are respectively provided with a first water inlet hole 11 and a second water inlet hole 12 along the radial direction of the support cylinder 10. The first water inlet hole 11 intersects and communicates with the first optical fiber hole 13. The water inlet hole 12 intersects and communicates with the second optical fiber hole 14 for introducing water with balanced static pressure.

The pigtails of the fiber grating 20 are bonded and fixed at the first fiber hole 13 and the second fiber hole 14 outside the support cylinder 10 .

(3) Beneficial effects

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. Hydrostatic pressure resistance. The hydrostatic pressure is introduced into the other side of the first piston 21 and the second piston 22 through the first water inlet hole 11 and the second water inlet hole 12 to balance the static pressure and improve the static pressure resistance of the hydrophone.

Description of drawings

Fig. 1 is a schematic structural diagram of a static pressure self-compensating fiber grating hydrophone provided by the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in Figure 1, Figure 1 is a schematic structural view of the static pressure self-compensating fiber grating hydrophone provided by the present invention, the main body of the fiber grating hydrophone is a cylindrical support tube 10 with an axially symmetrical structure, the fiber The grating hydrophone includes: a fiber grating 20 installed on the central axis of the support cylinder 10 for measuring underwater sound; a first piston 21 and a second piston 22 respectively installed at both ends of the fiber grating 20 for measuring the water sound pressure Passed to the fiber grating 20; the first fiber hole 13 and the second fiber hole 14 respectively opened in the central axis of the two ends of the support cylinder 10 are used to lead out the pigtail of the fiber grating 20.

Axisymmetrically distributed long holes 15 are formed in the axial middle of the side wall of the support cylinder 10 for allowing water to enter the interior of the support cylinder 10 and act on the first piston 21 and the second piston 22 .

The first piston 21 and the second piston 22 are fixedly connected to the fiber grating 20 by bonding, and drive the fiber grating 20 to move axially inside the support cylinder 10 .

When this fiber grating hydrophone provided by the present invention is placed in water (or other liquids), water (or other liquids) enters from the long hole 15 and acts on the first piston 21 and the second piston 22, making the first piston 21 and the second piston 22 The first piston 21 and the second piston 22 move towards the two ends of the support cylinder 10 respectively. Since the fiber grating 20 is fixed on the first piston 21 and the second piston 22, it is displaced toward the end of the support cylinder 10 by the first piston 21 and the second piston 22, and strain is generated in the axial direction of the fiber grating. For the fiber grating 20, 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.

Both ends of the support cylinder 10 are respectively provided with a first water inlet hole 11 and a second water inlet hole 12 along the radial direction of the support cylinder 10. The first water inlet hole 11 intersects and communicates with the first optical fiber hole 13. The water inlet hole 12 intersects and communicates with the second optical fiber hole 14 for introducing water with balanced static pressure.

When the fiber grating hydrophone provided by the present invention is placed at different depths in water, water can enter through the first water inlet 11, the first optical fiber hole 13, the second water inlet 12, and the second optical fiber hole 14 respectively. The other sides of the first piston 21 and the second piston 22 inside the support cylinder 10 are statically balanced with the water entering the interior of the grating hydrophone from the long hole 15 . Thereby offsetting the effect of static pressure, so that the hydrophone can work at different depths.

The pigtails of the fiber grating 20 are bonded and fixed at the first fiber hole 13 and the second fiber hole 14 outside the support cylinder 10, so as to prevent the negative impact of the external force on the fiber grating 20 on the hydrophone. Negative effects such as changing the positions of the first piston 21 and the second piston 22 and the like.

At the same time, the sensitivity of the fiber grating hydrophone can be adjusted by adjusting parameters such as the outer diameter of the support cylinder 10 and the stiffness of the first piston 21 and the second piston 22 .

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 (5)

1. A static pressure self-compensating fiber grating hydrophone is characterized in that the main body of the fiber grating hydrophone is a cylindrical support tube (10) with an axially symmetrical structure, and the fiber grating hydrophone comprises: An optical fiber grating (20) installed on the central axis of the support cylinder (10) is used for measuring underwater sound; The first piston (21) and the second piston (22) installed at both ends of the fiber grating (20) respectively, are used to transfer the water sound pressure to the fiber grating (20); A first optical fiber hole (13) and a second optical fiber hole (14) respectively opened in the central axis of both ends of the support cylinder (10) are used to lead out the pigtail of the optical fiber grating (20). 2. The static pressure self-compensating fiber grating hydrophone according to claim 1, characterized in that, the axial middle part of the side wall of the support cylinder (10) has an axisymmetrically distributed long hole (15) for making Water enters into the support cylinder (10) and acts on the first piston (21) and the second piston (22). 3. The static pressure self-compensating fiber grating hydrophone according to claim 1, wherein the first piston (21) and the second piston (22) are fixed to the fiber grating (20) by bonding connected, and drives the fiber grating (20) to move axially inside the support cylinder (10). 4. The static pressure self-compensating fiber grating hydrophone according to claim 1, characterized in that, the two ends of the support cylinder (10) are respectively provided with first water inlet holes along the radial direction of the support cylinder (10) (11) and the second water inlet (12), the first water inlet (11) intersects and communicates with the first optical fiber hole (13), and the second water inlet (12) intersects with the second optical fiber hole (14) And connected, used to introduce balanced static pressure water. 5. static pressure self-compensating fiber grating hydrophone according to claim 1, is characterized in that, the pigtail fiber of described fiber grating (20) is outside the first fiber optic hole (13) and the second fiber grating (10) in support cylinder (10). The optical fiber hole (14) is bonded and fixed.

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