Ocean temperature-depth probe structure based on fiber bragg grating

Abstract

The invention discloses an ocean temperature-depth probe structure based on a fiber bragg grating, which comprises an anti-corrosion shell with a cavity, and is characterized in that the first end of the anti-corrosion shell is arranged in a penetrating manner; a piston which is impacted by seawater to move is slidably arranged in the first end; a leading-out optical fiber is arranged on the inward end face of the piston, one end of the leading-out optical fiber extends out of the anti-corrosion shell, the leading-out optical fiber is sequentially provided with a temperature compensation grating, a pressure measuring grating and a temperature measuring grating, and the center wavelength of the temperature compensation grating is the same as the center wavelength of the pressure measuring grating and smaller than the center wavelength of the temperature measuring grating. The temperature compensation grating and the pressure measuring grating are located in the cavity, and the pressure measuring grating is wrapped with a polycarbonate film; the piston is provided with an anti-corrosion pipe wrapping the outer side of the temperature compensation grating. A metal silver tube is arranged on the end face, relatively away from the first end, of the anti-corrosion shell, and a temperature measuring grating is packaged in the metal silver tube through epoxy glue.

Description

Technical Field

[0001] The invention relates to the field of optical fiber sensing technology, and in particular to an ocean temperature and depth probe structure based on optical fiber grating. Background Art

[0002] Temperature and pressure parameters are the basis for obtaining parameters such as ocean flow velocity, density, and heat content. On-site real-time monitoring of temperature and pressure parameters plays an important role in the development of marine resources, offshore operations, and prevention of global warming. Therefore, temperature and depth sensors used to detect temperature and pressure parameters, as basic equipment for ocean exploration, occupy an important position in the fields of marine economy, marine ecology, and marine military.

[0003] As a new type of passive sensor device, fiber Bragg grating has been widely used in temperature and depth sensors due to its advantages such as good insulation, high precision, anti-electromagnetic interference and wavelength encoding. However, most of the existing temperature and depth sensors use bare fiber Bragg gratings for temperature and pressure measurement, and have insufficient temperature sensitivity and pressure sensitivity, especially when detecting ocean temperature and pressure profile data in shallow sea (0 meters to 800 meters). The reliability is poor. Therefore, there is an urgent need for a temperature and depth sensor that can reliably detect ocean temperature and pressure profile data in shallow sea. Summary of the invention

[0004] In view of this, the present invention provides an ocean temperature and depth probe structure based on fiber grating to solve the problem of lack of a temperature and depth sensor that can reliably detect ocean temperature and pressure profile data in shallow seas.

[0005] The present invention provides an ocean temperature and depth probe structure based on fiber grating, comprising:

[0006] An anti-corrosion shell is provided with a cavity, and a first end of the anti-corrosion shell is penetrated along a first direction;

[0007] A piston is slidably disposed in the first end along a first direction, and the piston is used to move under the impact of seawater; an optical fiber is disposed on the end face of the piston facing inward along the first direction, one end of the optical fiber extends to the outside of the anti-corrosion shell, and a temperature compensation grating, a pressure measuring grating and a temperature measuring grating are sequentially disposed on the optical fiber in a direction away from the piston, the central wavelengths of the temperature compensation grating and the pressure measuring grating are the same, the central wavelength of the pressure measuring grating is smaller than the central wavelength of the temperature measuring grating, the temperature compensation grating and the pressure measuring grating are located in the cavity, and the outer side of the pressure measuring grating is wrapped with a polycarbonate film;

[0008] An anti-corrosion tube is arranged at the inward end of the piston and covers the outer side of the temperature compensation grating;

[0009] The metal silver tube is arranged on the end surface of the anti-corrosion shell relatively far away from the first end, and the temperature measuring grating is encapsulated in the metal silver tube by epoxy glue.

[0010] The ocean temperature and depth probe structure based on fiber grating according to the present invention has at least the following beneficial effects:

[0011] 1. A piston is slidably arranged at the opening of the first end, a temperature compensation grating and a pressure measuring grating with the same central wavelength are connected in series, and the temperature compensation grating is encapsulated in an anti-corrosion tube, and the pressure measuring grating is encapsulated with a polycarbonate film. When the seawater exerts an impact force on the piston so that the piston moves inward along a first direction, the pressure measuring grating detects the pressure parameter by responding to the deformation transmitted when the piston moves, and the temperature compensation grating and the anti-corrosion tube move synchronously with the piston, so that the temperature compensation grating is only affected by the internal temperature but not by the pressure, and the polycarbonate film has a lower Young's modulus, so that the temperature compensation grating and the polycarbonate film cooperate to The deformation transmitted when the piston moves is compensated and corrected to achieve pressure sensitization of the pressure grating, thereby improving the pressure sensitivity and reducing the pressure response time; the temperature grating is also encapsulated in a metal silver tube by epoxy glue, and the metal silver tube with a large thermal expansion coefficient and a large thermal conductivity coefficient performs temperature sensitization on the temperature grating, thereby improving the temperature sensitivity and reducing the temperature response time, so that the ocean temperature and depth probe structure has high pressure sensitivity and short pressure response time, as well as high temperature sensitivity and short temperature response time, thereby meeting the requirements for reliable detection of ocean temperature and pressure profile data in shallow seas.

[0012] 2. The central wavelength of the pressure measuring grating and the central wavelength of the temperature measuring grating are set to be different, so that the pressure measuring grating and the temperature measuring grating can detect the pressure parameter and the temperature parameter independently respectively, avoiding cross-interference.

[0013] In an optional embodiment, a PTFE diaphragm is arranged in the cavity, and the PTFE diaphragm divides the cavity into a first cavity and a second cavity along a first direction, the piston is slidably arranged in the first cavity, the anti-corrosion tube is arranged in the first cavity, and the pressure measuring grating is arranged in the second cavity.

[0014] In an optional embodiment, the material of the piston is set to 7075 aluminum alloy.

[0015] In an optional implementation, the material of the anti-corrosion tube is set to 304 stainless steel, and the anti-corrosion tube is welded and fixed to the piston.

[0016] In an optional embodiment, the material of the corrosion-resistant shell is set to 304 stainless steel.

[0017] In an optional embodiment, a through hole is provided through the bottom end of the corrosion-resistant shell along a first direction, and the optical fiber is passed through the through hole; the metal silver tube covers the through hole and is welded and fixed to the corrosion-resistant shell.

[0018] In an optional embodiment, a connecting platform is protruded from the inner bottom wall of the corrosion-resistant shell along the first direction close to the pressure measuring grating, and the through hole is arranged through the connecting platform.

[0019] In an optional embodiment, the spacing between the PTFE diaphragm and the pressure grating along the first direction is set to 5 mm to 9 mm.

[0020] In an optional implementation, the difference between the central wavelength of the pressure measuring grating and the central wavelength of the temperature measuring grating is greater than or equal to 240 nm.

[0021] In an optional embodiment, the cross-sectional shape of the piston perpendicular to the first direction is set to be square. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the cutaway front view structure of an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of a cutaway top view of the structure of an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] 100-anti-corrosion housing, 110-cavity, 111-first cavity, 112-second cavity, 120-PTFE diaphragm, 130-connecting platform, 200-piston, 310-output optical fiber, 320-temperature compensation grating, 330-pressure measuring grating, 340-temperature measuring grating, 350-polycarbonate membrane, 400-anti-corrosion tube, 500-metal silver tube, 510-epoxy glue. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0028] In the description of this embodiment, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting this embodiment. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] In the description of this embodiment, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0030] Combine the following Figure 1 and Figure 2 , describing an embodiment of the present invention.

[0031] According to an embodiment of the present invention, a marine temperature and depth probe structure based on fiber grating is provided, comprising an anti-corrosion shell 100 with a cavity 110, wherein the anti-corrosion shell 100 is penetrated at a first end along a first direction; a piston 200 is slidably arranged in the first end along a first direction, and the piston 200 is used to move under the impact of seawater; an output optical fiber 310 is arranged on the end face of the piston 200 facing inward along the first direction, and one end of the output optical fiber 310 extends to the outside of the anti-corrosion shell 100, and the output optical fiber 310 is sequentially provided with a temperature compensation grating 320, a pressure measuring grating 330 and a temperature measuring grating 340 in a direction away from the piston 200, and the temperature compensation grating 320 and the pressure measuring grating 330 and the temperature measuring grating 340 are arranged in sequence. The central wavelengths of the pressure measuring gratings 330 are the same, and the central wavelength of the pressure measuring gratings 330 is smaller than the central wavelength of the temperature measuring grating 340. The temperature compensation grating 320 and the pressure measuring grating 330 are located in the cavity 110. The outer side of the pressure measuring grating 330 is wrapped with a polycarbonate film 350, and the temperature measuring grating 340 is located outside the anti-corrosion shell 100; an anti-corrosion tube 400 is provided at the inward end of the piston 200, and the anti-corrosion tube 400 is coated on the outer side of the temperature compensation grating 320; a metal silver tube 500 is provided on the end face of the anti-corrosion shell 100 relatively away from the first end, and the temperature measuring grating 340 is encapsulated in the metal silver tube 500 by epoxy glue 510.

[0032] The ocean temperature and depth probe structure of this embodiment is provided with a piston 200 slidably at the opening of the first end, a temperature compensation grating 320 and a pressure measuring grating 330 with the same central wavelength are connected in series, and the temperature compensation grating 320 is encapsulated in an anti-corrosion tube 400, and the pressure measuring grating 330 is encapsulated with a polycarbonate film 350. When the seawater exerts an impact force on the piston 200 so that the piston 200 moves inward along a first direction, the pressure measuring grating 330 detects the pressure parameter by responding to the deformation transmitted when the piston 200 moves, and the temperature compensation grating 320 and the anti-corrosion tube 400 move synchronously with the piston 200, so that the temperature compensation grating 320 is only affected by the internal temperature but not by the pressure, and the polycarbonate film 350 has a lower Young's modulus, so that the temperature compensation grating 320 is not affected by the pressure. The grating 320 and the polycarbonate film 350 cooperate to compensate for the deformation transmitted when the piston 200 moves, thereby realizing pressure sensitivity of the pressure measuring grating 330, thereby reducing the pressure response time while improving the pressure sensitivity; the temperature measuring grating 340 is also encapsulated in the metal silver tube 500 by epoxy glue 510, and the metal silver tube 500 with a large thermal expansion coefficient and a large thermal conductivity coefficient performs temperature sensitivity on the temperature measuring grating 340, thereby reducing the temperature response time while improving the temperature sensitivity, so that the ocean temperature and depth probe structure of this embodiment has higher pressure sensitivity and shorter pressure response time, as well as higher temperature sensitivity and shorter temperature response time, thereby meeting the requirements for reliable detection of ocean temperature and pressure profile data in shallow sea (0 meters to 800 meters).

[0033] The ocean temperature and depth probe structure of this embodiment also sets the central wavelength of the pressure measuring grating 330 and the central wavelength of the temperature measuring grating 340 to be different, so that the pressure measuring grating 330 and the temperature measuring grating 340 can detect the pressure parameter and the temperature parameter independently, avoid cross-interference, and further improve the reliability of detection. At the same time, because the pressure parameter and the temperature parameter are detected independently in this embodiment, the sensitivity and response speed can be tuned by adjusting the thickness of the piston 200 along the first direction, the Young's modulus of the polycarbonate film 350, and the radius of the metal silver tube 500, so that the pressure response acquisition time and the temperature response acquisition time are very small, and the pressure and temperature dual parameter acquisition time are matched; overcome the defects such as the mismatch of the pressure and temperature dual parameter acquisition time.

[0034] The ocean temperature and depth probe structure of this embodiment uses epoxy glue 510 to encapsulate the temperature measuring grating 340 in the metal silver tube 500, which can prevent chirping caused by the softness of the metal silver tube 500, and is conducive to improving the detection precision and accuracy of this embodiment.

[0035] Specifically, the temperature measuring grating 340 is packaged in the metal silver tube 500 in the following manner: after the epoxy glue 510 is applied to the outer surface of the temperature measuring grating 340, the metal silver tube 500 is then wrapped around the epoxy glue 510 for packaging, and finally the metal silver tube 500 is fixedly connected to the anti-corrosion housing 100. The metal silver tube 500 has a large thermal expansion coefficient and thermal conductivity, and has a strong ability to transmit temperature changes, and can effectively perform temperature sensitization on the temperature measuring grating 340.

[0036] It should be noted that the central axes of the anti-corrosion housing 100, the piston 200, the anti-corrosion tube 400 and the metal silver tube 500 of this embodiment coincide with each other, and the first direction mentioned in the text is parallel to the central axis of the anti-corrosion housing 100; for the convenience of description, this embodiment is described as follows: Figure 1 The first direction shown in FIG. 1 is described as the central axis direction of the corrosion-resistant housing 100 , but it should not be understood as a clear limitation on the central axis direction of the corrosion-resistant housing 100 .

[0037] Specifically, the epoxy glue 510 adopts a modified epoxy adhesive with a model number of DG-4.

[0038] It can be understood that the temperature measuring grating 340 in this embodiment adopts a technical route based on thermal expansion. Therefore, packaging the temperature measuring grating 340 with a metal silver tube 500 with a large thermal expansion coefficient and thermal conductivity can enhance temperature sensitivity, thereby reducing the temperature response time while improving the temperature sensitivity.

[0039] It can be understood that the sensing principle of fiber Bragg grating is that when a beam of wide spectrum passes through the grating fiber, the light wave that meets the fiber Bragg wavelength condition will be reflected, and the remaining light waves will continue to propagate through the grating; temperature and strain are two direct physical quantities that cause the change of the central wavelength of the reflected light; when the ambient temperature or the strain on the fiber Bragg grating changes, it can cause the change of the effective refractive index and grating period of the fiber core, so that the fiber Bragg grating wavelength drifts; by obtaining the change in the fiber Bragg grating wavelength, the absolute measurement of strain or temperature value can be achieved. In a specific application, the end of the export optical fiber 310 extending outside the corrosion-resistant housing 100 is connected to the fiber Bragg grating demodulator, and the fiber Bragg grating demodulator is connected to a computer, and the ocean temperature and pressure profile data information in the shallow sea are calculated on the computer.

[0040] like Figure 1As shown, in some embodiments, a PTFE diaphragm 120 is disposed in the cavity 110, and the PTFE diaphragm 120 divides the cavity 110 into a first cavity 111 and a second cavity 112 along a first direction, the piston 200 is slidably disposed in the first cavity 111, the anti-corrosion pipe 400 is disposed in the first cavity 111, and the pressure measuring grating 330 is disposed in the second cavity 112. The PTFE diaphragm 120 has the function of only permeating air but not water, which can reduce the leakage caused by accidental poor connection between the piston 200 and the inner wall of the anti-corrosion housing 100, reduce the impact on the detection of the pressure measuring grating 330, and ensure the stability of the ocean temperature and depth probe structure of this embodiment during the detection process.

[0041] Specifically, the material of the piston 200 is set to 7075 aluminum alloy; so that the piston 200 has good strength and lightness to ensure that it moves along the first direction close to the pressure measuring grating 330 under the external force of seawater impact; and has strong corrosion resistance and good wear resistance, and is suitable for marine detection environment.

[0042] Specifically, the piston 200 is arranged in a direction perpendicular to the cross-sectional shape of the first direction, so as to better respond to the impact force exerted by the seawater to generate a displacement moving along the first direction close to the pressure measuring grating 330 .

[0043] Specifically, the material of the anti-corrosion tube 400 is set to 304 stainless steel, and the anti-corrosion tube 400 is welded and fixed to the piston 200; with this arrangement, the anti-corrosion tube 400 has a strong corrosion resistance. Even if seawater enters the first cavity 111 due to accidental poor connection between the piston 200 and the inner wall of the anti-corrosion shell 100, it will not cause corrosion of the anti-corrosion tube 400, thereby extending the service life; and the anti-corrosion tube 400 and the piston 200 are fixed by welding. Compared with one-piece molding, this embodiment can use special corrosion-resistant materials to make the piston 200 and use conventional corrosion-resistant materials to make the anti-corrosion tube 400, which is beneficial to reducing the manufacturing cost of the ocean temperature and depth probe structure of this embodiment.

[0044] In some embodiments, the material of the corrosion-resistant shell 100 is set to 304 stainless steel; the corrosion-resistant shell 100 has a strong corrosion resistance and a low material cost, which is conducive to reducing the manufacturing cost of the ocean temperature and depth probe structure of this embodiment.

[0045] Specifically, the bottom end of the corrosion-resistant housing 100 is provided with a perforation along the first direction, and the perforation is for the optical fiber 310 to pass through; the metal silver tube 500 covers the perforation and is welded and fixed to the corrosion-resistant housing 100. By waterproofing and blocking the perforation, it is helpful to prevent seawater from entering the second cavity 112 through the perforation and affecting the detection of the pressure measuring grating 330, thereby ensuring the stability of the ocean temperature and depth probe structure of this embodiment during the detection process.

[0046] Specifically, a connecting platform 130 is protruded from the inner bottom wall of the corrosion-resistant shell 100 along the first direction close to the pressure grating 330, and the perforation is arranged through the connecting platform 130. This arrangement shortens the size of the portion of the lead-out optical fiber 310 located between the pressure grating 330 and the connecting platform 130, which helps to reduce the risk of the lead-out optical fiber 310 being pulled apart.

[0047] It can be understood that the lead-out optical fiber 310 and the inner wall of the perforation are sealed by a sealant.

[0048] Specifically, the spacing between the PTFE diaphragm 120 and the pressure measuring grating 330 along the first direction is set to 5 mm to 9 mm, and preferably 7 mm in the present embodiment; this achieves the goal of shortening the size of the ocean temperature and depth probe structure along the first direction in the present embodiment on the basis of meeting the requirements for reliable detection of ocean temperature and pressure profile data in shallow seas, making it easy to carry and use.

[0049] Specifically, the difference between the central wavelength of the pressure measuring grating 330 and the central wavelength of the temperature measuring grating 340 is greater than or equal to 240nm; the central wavelengths of the pressure measuring grating 330 and the temperature compensation grating 320 are both 1310nm, and the central wavelength of the temperature measuring grating 340 is 1550nm; it is ensured that the central wavelengths of the pressure measuring grating 330 and the temperature measuring grating 340 change with the external temperature or pressure without overlapping, thereby realizing independent detection of pressure parameters and temperature parameters.

[0050] In this embodiment, the piston 200 is 15 mm long, 8 mm wide and 6 mm thick; the anti-corrosion tube 400 has a radius of 4 mm and a length of 15 mm; the radius of the metal silver tube 500 is 3 mm; this makes the size of the assembled ocean temperature and depth probe structure of this embodiment relatively compact for easy carrying and use.

[0051] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended invention.

Claims

1. An ocean temperature and depth probe structure based on fiber Bragg grating, characterized in that: include: An anti-corrosion shell (100) is provided with a cavity (110), and the anti-corrosion shell (100) is penetrated at a first end along a first direction; A piston (200) is slidably disposed in the first end along a first direction, and the piston (200) is used to move under the impact of seawater; The piston (200) is provided with an optical fiber (310) on its end surface facing inward along a first direction, one end of the optical fiber (310) extending outside the anti-corrosion housing (100), and the optical fiber (310) is provided with a temperature compensation grating (320), a pressure measuring grating (330) and a temperature measuring grating (340) in sequence in a direction away from the piston (200), the temperature compensation grating (320) and the pressure measuring grating (330) having the same central wavelength, the pressure measuring grating (330) having a smaller central wavelength than the temperature measuring grating (340), the temperature compensation grating (320) and the pressure measuring grating (330) being located in the cavity (110), and the outer side of the pressure measuring grating (330) being wrapped with a polycarbonate film (350); An anti-corrosion tube (400) is disposed at an inward end of the piston (200) and covers the outside of the temperature compensation grating (320); The metal silver tube (500) is arranged on an end surface of the anti-corrosion housing (100) relatively far away from the first end, and the temperature measuring grating (340) is encapsulated in the metal silver tube (500) by epoxy glue (510).

2. The structure of an ocean temperature and depth probe based on fiber Bragg grating according to claim 1, characterized in that: A PTFE diaphragm (120) is arranged in the cavity (110), and the PTFE diaphragm (120) divides the cavity (110) into a first cavity (111) and a second cavity (112) along a first direction. The piston (200) is slidably arranged in the first cavity (111), the anti-corrosion tube (400) is arranged in the first cavity (111), and the pressure measuring grating (330) is arranged in the second cavity (112).

3. The ocean temperature and depth probe structure based on fiber grating according to claim 1 or 2, characterized in that: The material of the piston (200) is set to be 7075 aluminum alloy.

4. The ocean temperature and depth probe structure based on fiber Bragg grating according to claim 3 is characterized in that: The material of the anti-corrosion tube (400) is set to be 304 stainless steel, and the anti-corrosion tube (400) is welded and fixed to the piston (200).

5. The structure of an ocean temperature and depth probe based on fiber Bragg grating according to claim 2, characterized in that: The material of the corrosion-resistant housing (100) is set to be 304 stainless steel.

6. The structure of an ocean temperature and depth probe based on fiber grating according to claim 5, characterized in that: A perforation is provided at the bottom end of the anti-corrosion shell (100) along a first direction, and the lead-out optical fiber (310) passes through the perforation; the metal silver tube (500) covers the perforation and is fixed to the anti-corrosion shell (100) by welding.

7. The ocean temperature and depth probe structure based on fiber Bragg grating according to claim 6, characterized in that: A connecting platform (130) is protrudingly provided on the inner bottom wall of the anti-corrosion housing (100) along a first direction close to the pressure measuring grating (330), and the through hole is arranged through the connecting platform (130).

8. The ocean temperature and depth probe structure based on fiber Bragg grating according to claim 2 or 7, characterized in that: The spacing between the PTFE diaphragm (120) and the pressure grating (330) along the first direction is set to 5 mm to 9 mm.

9. The ocean temperature and depth probe structure based on fiber grating according to claim 1 or 2, characterized in that: The difference between the central wavelength of the pressure measuring grating (330) and the central wavelength of the temperature measuring grating (340) is greater than or equal to 240 nm.

10. The ocean temperature and depth probe structure based on fiber Bragg grating according to claim 1 or 2, characterized in that: The cross-sectional shape of the piston (200) perpendicular to the first direction is set to be a square.

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