CN201075028Y - High sensitivity fiber grating underwater sound sensor - Google Patents

Abstract

The utility model relates to a high sensitivity optical fiber grating underwater acoustic sensor. The utility model is provided with two cavity bodies which are arranged centro-symmetrically at the interior of a polymer sealing-packing body, both ends of the cavity bodies are sealed, and an optical fiber grating penetrates the cavity body and is fixed on the position of an axis of the polymer sealing-packing body for formation. Further, the tail fiber of the optical fiber grating penetrates a central through hole of a base, so as to fix the polymer sealing-packing body on the base. The polymer sealing-packing body is a cylindrical body, and the cross sections of the cavity bodies can be round, oval, square or D-shaped. The utility model is characterized in that the acoustic pressure sensitivity is high, which is higher than the underwater acoustic sensor prepared by directly adopting the optical fiber grating by 3 to 4 number grades, the utility model is fully characterized by light weight, small structure, high sensitivity and so on, so the utility model has the important application prospect in the field of underwater acoustic detection.

Description

The high-sensitivity optical fiber grating underwater sound sensor

Technical field

The utility model belongs to the fiber grating sensing technology field, is specifically related to a kind of high-sensitivity optical fiber grating underwater sound sensor.

Background technology

Present various underwater acoustic transducer or underwater sound sensor etc. have very important using value at aspects such as marine acoustics environment detection, the detection of target acoustic characteristic, submarine acoustic characteristic research.But, can not satisfy the demand that association area further develops because there are deficiencies such as volume is big, sensitivity is low, operating distance is near in present underwater sound sensor.

Recently have advantages such as light weight, structure be little with the underwater sound sensor of optical fiber preparing grating, can realize potential microminiaturized sonde configuration, have extraordinary anti-acceleration performance index and anti-current noise ability, have very important using value aspect the structure towed sonar battle array.Yet because the pressure sensitivity of fiber grating self is lower, make that the underwater sound sensor sensitivity of directly adopting fiber grating to make is lower, be difficult to be used for surveying underwater sound signal, therefore study a kind of novel high-sensitivity optical fiber grating underwater sound sensor and be very important.

Summary of the invention

The purpose of this utility model is to provide a kind of high-sensitivity optical fiber grating underwater sound sensor, and the pressure sensitivity of crucial solution fiber grating self is lower, to overcome the deficiency of prior art.

The utility model mainly utilize in the polymer encapsulated body the cavity body structure effect to external world underwater sound signal carry out enhanced sensitivity and amplify, to improve the sensing sensitivity of fiber grating greatly to underwater sound signal.Its ultimate principle is, when having extraneous sound pressure signal, the existence of cavity body will cause the inner nonaxisymmetry stress that produces of polymer encapsulated body to be applied on the fiber grating, and the numerical value of this stress will be much larger than extraneous sound pressure signal, thereby realizes that stress amplifies.Under the elasto-optical effect effect, the stress that is applied on the fiber grating will cause the variation of fiber grating effective refractive index and axial strain, thereby causes the centre wavelength of fiber grating to be shifted.This shows that this kind optical fiber grating submarine sound signal sensor is converted into the displacement of fiber grating centre wavelength with extraneous sound pressure signal, thereby realize measurement sound pressure signal.

The solution that the utility model adopts, two cavity body that the center that it is provided with by a polymer encapsulated body inside is symmetrically distributed, this cavity body is sealed at both ends, and fiber grating passes and is fixed on the axis of polymer encapsulated body and forms.This is basic structure of the present utility model.

Further the tail optical fiber of fiber grating is passed the central through hole of pedestal and above-mentioned polymer encapsulated body is fixed on the pedestal, be provided with four screws at the pedestal periphery, when being used for underwater sound sensing measurement with other in succession structure be connected.

The profile of described polymer encapsulated body can be right cylinder, cylindroid, square column etc.

The xsect of the cavity body in the described polymer encapsulated body can be circle, ellipse, square or D shape; Described two cavity body are symmetrically distributed about the axis centre of polymer encapsulated body.

Characteristics of the present utility model are to have higher sound pressure sensitivity, than high 3～4 orders of magnitude of underwater sound sensor of direct employing fiber grating making.The utility model has not only improved the acoustic pressure sensing sensitivity of fiber grating, has also effectively protected fiber grating, has expanded the application or the scope of fiber grating greatly.In addition, the utility model demonstrates fully characteristics such as have light weight, structure is little, antijamming capability is strong, can be used for making microminiaturized probe, therefore has important application prospects in underwater sound field of detecting.

Below in conjunction with drawings and Examples the utility model is elaborated.

Description of drawings

Fig. 1 is a basic structure synoptic diagram of the present utility model;

Fig. 2 is the A-A sectional view of Fig. 1;

Fig. 3 is the B-B sectional view of Fig. 1.

Wherein 1. pedestals, 2. polymer encapsulated body, 3. cavity body, 4. tail optical fiber, 5. fiber grating, 6. screw.

Embodiment

As Fig. 1, Fig. 2 and Fig. 3, simple structure of the present utility model, two cavity body 3 that the center that it is provided with by a polymer encapsulated body 2 inside is symmetrically distributed, this cavity body 3 is sealed at both ends, and fiber grating 5 passes and is fixed on the axis of this polymer encapsulated body 2 and forms.

The profile of described polymer encapsulated body 2 can be cylindrical body, as right cylinder, cylindroid, square column etc.The utility model is that cylindrical polymer encapsulated body 2 is an example with profile only.

The xsect of the cavity body 3 in the described polymer encapsulated body 2 can be circle, ellipse, square or D shape; Described two cavity body 3 are symmetrically distributed about the axis centre of polymer encapsulated body 2.

Pedestal 1 is flat board or disc, and polymer encapsulated body 2 embeds wherein, and both adopt high-strength adhesive to connect.

Further the tail optical fiber 4 of fiber grating 5 one ends of above-mentioned basic structure is passed the central through hole of pedestal 1, and above-mentioned polymer encapsulated body 2 is fixed on the pedestal 1, and be provided with four screws 6 at pedestal 1 periphery, when being used for underwater sound sensing measurement with other in succession structure be connected.

Tail optical fiber 4, the one end tail optical fibers that described fiber grating 5 two ends exist pass from the thin through hole at pedestal 1 center, and are used to connect optical system; Other end freedom, or can be used as the array multiplex channel of a plurality of described optical fiber grating submarine sound signal sensors, and then with the tail optical fiber 4 of its fiber grating 5 serial or parallel connection successively and form array.

Fiber grating 5 on the described central shaft that is packaged in polymer encapsulated body 2 is Fiber Bragg Grating FBG.

The manufacturing materials of described polymer encapsulated body 2 can be selected polyurethane material or polyamide material for use.

In order to guarantee higher acoustic pressure sensing sensitivity, require the diameter dimension of each xsect of two cavity body 3 to be not less than 1/3rd of polymer encapsulated body 2 cross-sectional diameter sizes.Guaranteeing to shorten the distance between cavity body 3 central axis and polymer encapsulated body 2 central axis under the prerequisite that 2 making of polymer encapsulated body require as far as possible.For guaranteeing watertightness of the present utility model and stress intensity, the packaging body around the cavity body 3 will guarantee certain thickness simultaneously, to be fit to the intensity of needs.

As shown in Figure 1, polymer encapsulated body 2 is the right cylinder of Φ 20.0 * 50.0mm profile in the present embodiment, and its manufacturing materials is a polyurethane.The xsect of cavity body 3 is that diameter is the circle of Φ 7.0mm, and the distance between its central axis and polymer encapsulated body 2 central axis is 4.5mm, and the polymer encapsulated body thickness at cavity body 3 two ends is 3.0mm.To be the fiber grating pressure sensitivity become greatly with the increase of cavity body 3 radiuses common rule, reduces with the increase of the distance of two cavity body 3.

The utility model of constructing thus reaches in the sound pressure sensitivity at 500Hz frequency place-162dB (0dB=1pm/uPa), and it is 70dB that I is surveyed acoustic pressure $(0\mathrm{dB}=1\mathrm{uPa}/\sqrt{\mathrm{Hz}}).$

When the utility model is used for the underwater sound signal measurement, need only other stationary installations that four screws 6 that pedestal 1 periphery is had connect sensor-based systems, the thin through hole that tail optical fiber 4 front ends pass pedestal 1 is connected with other optical systems.But the shift amount of external optical system detection fiber grating 5 centre wavelengths that connected by tail optical fiber 4 this moment can be realized the measurement to faint sound pressure signal.

Though describe the utility model in detail with reference to the foregoing description, should be appreciated that the utility model is not limited to the disclosed embodiments, for the technician of this professional domain, can carry out various changes to its form and details.The utility model is intended to contain the interior various modification of spirit and scope of appended claims.

Claims (5)

1. high-sensitivity optical fiber grating underwater sound sensor, it is characterized in that it is to be provided with two cavity body (3) that the center is symmetrically distributed by polymer encapsulated body (a 2) inside, this cavity body (3) is sealed at both ends, and a fiber grating (5) passes and is fixed on the axial location of this polymer encapsulated body (2) and forms.

2. high-sensitivity optical fiber grating underwater sound sensor as claimed in claim 1, the tail optical fiber (4) that it is characterized in that described fiber grating (5) one ends passes the central through hole of pedestal (1) and polymer encapsulated body (2) is fixed on the pedestal (1), and is provided with four screws (6) at pedestal (1) periphery.

3. high-sensitivity optical fiber grating underwater sound sensor as claimed in claim 1 or 2, what it is characterized in that described polymer encapsulated body (2) is shaped as right cylinder, oval cylinder or square body.

4. high-sensitivity optical fiber grating underwater sound sensor as claimed in claim 1 or 2 is characterized in that the xsect of the cavity body (3) in the described polymer encapsulated body (2) can be circle, ellipse, square or D shape.

5. high-sensitivity optical fiber grating underwater sound sensor as claimed in claim 1 is characterized in that described fiber grating (5) is a Fiber Bragg Grating FBG.

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