Ocean temperature-depth sensor probe of fiber grating series structure

Abstract

The utility model discloses an ocean temperature-depth sensor probe with a fiber grating series structure, which comprises a shell, a detection cavity is arranged in the shell, one end of the shell corresponding to the detection cavity is provided with an opening, and the other end of the shell is provided with a fiber passing hole; the periphery of the pressure sensing diaphragm is sealed and fixed at the opening; the middle part of one side, close to the detection cavity, of the pressure sensing diaphragm is fixedly connected with a pressure sensing fiber grating; the first temperature sensing fiber bragg grating is located in the detection cavity and detects the temperature in the detection cavity, the first temperature sensing fiber bragg grating is used for compensating the data error of the pressure sensing fiber bragg grating influenced by the temperature of the pressure sensing diaphragm, and the first temperature sensing fiber bragg grating and the pressure sensing fiber bragg grating are connected in series through an optical fiber; the metal silver tube is fixed on the outer side of one end, corresponding to the optical fiber passing hole, of the shell, a second temperature sensing optical fiber grating is packaged in the metal silver tube, the second temperature sensing optical fiber grating and the first temperature sensing optical fiber grating are connected in series and measure the external environment temperature of the shell, and the temperature sensor is simple in structure, high in sensitivity and accurate in measurement result.

Description

Technical Field

[0001] The utility model belongs to the technical field of ocean measurement and sensing, and in particular relates to an ocean temperature and depth sensor probe with an optical fiber grating series structure. Background Art

[0002] Temperature and pressure parameters are the basis for obtaining parameters such as ocean sound velocity, flow velocity, density, and heat content. As basic equipment for ocean exploration, temperature and depth sensors occupy an important position in the fields of marine economy, marine ecology, and marine military. The disposable temperature profiler (XBT) used for ocean temperature and depth detection is a disposable device with advantages such as high flexibility, low price, and high detection efficiency. It is now an effective means for countries to quickly measure temperature and depth data. However, most traditional XBTs use electrical temperature measuring elements. In addition to using empirical formulas to measure depth, they also have problems such as low sensitivity, slow response time, and poor thermal stability. Fiber Bragg gratings have the characteristics of small size, anti-electromagnetic interference, pressure resistance, and corrosion resistance. As a good temperature and strain sensitive device, it shows high resolution and fast response speed during underwater detection, and can achieve high-sensitivity dynamic sensing of ocean temperature and depth data. Due to the low sensitivity of bare fiber Bragg gratings, most studies use different methods to enhance the sensitivity of fiber Bragg gratings, but existing studies still have problems such as low sensitivity, large size, long response time, and mismatch in the acquisition time of temperature and depth dual parameters.

[0003] Currently, most existing technologies use structures such as cantilever beams, bellows, and thin-walled cylinders to increase the pressure sensitivity of bare fiber Bragg gratings (FBGs), and use methods such as coating to increase the temperature sensitivity of bare FBGs. However, there are still problems such as insufficient sensitivity, insufficient response speed, and mismatch between temperature and depth time.

[0004] Chinese patent CN202210955473.1 discloses a fiber Bragg grating temperature and depth sensor probe structure. Although it can measure temperature and pressure independently, the transition setting of mercury affects the sensitivity and error of pressure measurement, and the structure is relatively complex and requires high precision.

[0005] Therefore, how to provide an ocean temperature depth sensor probe with a simple structure and high sensitivity is a problem that those skilled in the art need to solve urgently. Utility Model Content

[0006] In view of this, the utility model provides an ocean temperature and depth sensor probe with a fiber grating series structure, which can simultaneously improve temperature sensitivity and pressure sensitivity, while reducing temperature response time and pressure response time, so that the acquisition time of the temperature and depth dual parameters matches, and can realize temperature compensation for the pressure measuring part.

[0007] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: an ocean temperature and depth sensor probe with a fiber grating series structure, comprising:

[0008] A housing, wherein the housing has a detection cavity inside, wherein one end of the housing corresponding to the detection cavity is provided with an opening, and the other end of the housing is provided with an optical fiber through hole;

[0009] A pressure-sensitive diaphragm, wherein the periphery of the pressure-sensitive diaphragm is sealed and fixed to the opening, and a pressure-sensing optical fiber Bragg grating is fixedly connected to the middle of one side of the pressure-sensitive diaphragm close to the detection cavity;

[0010] A first temperature sensing fiber Bragg grating, the first temperature sensing fiber Bragg grating is located in the detection cavity and detects the temperature in the detection cavity, the first temperature sensing fiber Bragg grating is used to compensate for the data error of the pressure sensing fiber Bragg grating affected by the temperature of the pressure sensing diaphragm, and the first temperature sensing fiber Bragg grating and the pressure sensing fiber Bragg grating are connected in series using an optical fiber;

[0011] A metal silver tube, wherein the metal silver tube is fixedly connected to the outer side of one end of the shell corresponding to the optical fiber through hole, wherein a second temperature sensing optical fiber Bragg grating is encapsulated in the metal silver tube, wherein the second temperature sensing optical fiber Bragg grating is connected in series with the first temperature sensing optical fiber Bragg grating and measures the external ambient temperature of the shell, and wherein the second temperature sensing optical fiber Bragg grating can be connected to an external regulating device through an output optical fiber.

[0012] The utility model has the following beneficial effects: a pressure-sensitive diaphragm is connected to the open end of a shell, and a pressure-sensing optical fiber Bragg grating is connected to the pressure-sensitive diaphragm. During measurement, the pressure-sensitive diaphragm is deformed by contact with seawater. At this time, the pressure-sensing optical fiber Bragg grating is subjected to the dual effects of force pressure and temperature, and its effective refractive index changes after being affected by external pressure and temperature, so that its central wavelength is shifted. The arranged first temperature-sensing optical fiber Bragg grating is used to detect the temperature in the detection cavity, so as to compensate for the influence of temperature on the pressure-sensing optical fiber Bragg grating, thereby ensuring the sensitivity and accuracy of pressure detection, and then measuring the depth of seawater at this position. The second temperature-sensing optical fiber Bragg grating is used to directly measure the seawater temperature of the external environment. In addition, the present invention performs pressure sensitivity tuning by adjusting the thickness and length of the pressure-sensing diaphragm of the pressure measuring part; and performs temperature sensitivity tuning by adjusting the radius of the metal silver tube of the temperature measuring part, so as to facilitate adjustment of the measurement sensitivity of temperature and pressure, and obtain the depth of seawater according to pressure data.

[0013] Preferably, the housing is a columnar housing formed of stainless steel, the pressure-sensitive diaphragm is a copper diaphragm, the pressure-sensitive diaphragm is welded and fixed to the open portion of the housing, and the pressure-sensing fiber grating is fixed to the center of the pressure-sensitive diaphragm by cyanoacrylate adhesive.

[0014] The resulting technical effect is: the stainless steel cylindrical shell is corrosion-resistant, has high strength characteristics, and can adapt to seawater environments. The pressure-sensitive diaphragm is a copper diaphragm, which has strong ductility and high sensitivity to compressive deformation.

[0015] Preferably, a metal partition is fixed inside the detection cavity of the shell, and a hole is provided on the metal partition for the optical fiber to pass through. The optical fiber between the pressure sensing optical fiber grating and the first temperature sensing optical fiber grating is fixed on the metal partition.

[0016] The resulting technical effect is that the metal partition provides a base for fixing the optical fiber, and when the first temperature sensing optical fiber Bragg grating is installed, the deformation thereof is prevented from being affected by external factors.

[0017] Preferably, the central wavelengths of the first temperature sensing fiber grating and the second temperature sensing fiber grating are the same, and the central wavelength of the pressure sensing fiber grating is greater than the central wavelength of the first temperature sensing fiber grating or the second temperature sensing fiber grating.

[0018] The resulting technical effect is: using fiber gratings with different central wavelengths for sensing to achieve differentiated detection of pressure and temperature.

[0019] Preferably, the pressure-sensitive diaphragm seals the opening so that the detection cavity is a closed cavity.

[0020] The resulting technical effect is that the sealed detection cavity enables the first temperature sensing fiber Bragg grating to detect data with high precision without being affected by seawater pressure, so as to compensate for the temperature data error of the pressure sensing fiber Bragg grating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the overall structural diagram of an ocean temperature and depth sensor probe with a fiber Bragg grating series structure of the utility model;

[0022] Figure 2 This is a bottom view of an ocean temperature and depth sensor probe with a fiber grating series structure according to the utility model.

[0023] 1 housing, 2 detection cavity, 3 pressure-sensitive diaphragm, 4 pressure-sensing fiber Bragg grating, 5 optical fiber, 6 first temperature-sensing fiber Bragg grating, 7 metal silver tube, 8 second temperature-sensing fiber Bragg grating, 9 lead-out optical fiber, 10 metal partition, 11 optical fiber fixing seat. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] See the attached Figures 1 to 2 According to an embodiment of the utility model, a fiber Bragg grating series structure ocean temperature and depth sensor probe comprises:

[0026] The housing 1 has a detection cavity 2 inside. The housing 1 has an opening at one end corresponding to the detection cavity 2 and an optical fiber through hole at the other end. When the optical fiber is led out, it needs to be packaged to ensure the sealing effect of the detection cavity.

[0027] A pressure-sensitive diaphragm 3, the periphery of which is sealed and fixed at the opening, and a pressure-sensing optical fiber Bragg grating 4 is fixedly connected to the middle of one side of the pressure-sensitive diaphragm 3 close to the detection cavity 2;

[0028] A first temperature sensing fiber Bragg grating 6, which is located in the detection cavity 2 and detects the temperature in the detection cavity. The first temperature sensing fiber Bragg grating 6 is used to compensate for the data error of the pressure sensing fiber Bragg grating affected by the temperature of the pressure sensing diaphragm. The first temperature sensing fiber Bragg grating 6 and the pressure sensing fiber Bragg grating 4 are connected in series using an optical fiber 5;

[0029] The metal silver tube 7 is a cylindrical shell with a radius of 2.5 mm, which is fixedly welded to the outer side of one end of the shell 1 corresponding to the optical fiber through-hole. A second temperature sensing optical fiber Bragg grating 8 is encapsulated in the metal silver tube 7. The second temperature sensing optical fiber Bragg grating 8 is connected in series with the first temperature sensing optical fiber Bragg grating 6 and measures the external ambient temperature of the shell. The second temperature sensing optical fiber Bragg grating 8 can be connected to an external adjustment device through an output optical fiber 9.

[0030] The present invention is provided with a first temperature sensing fiber Bragg grating 6 for temperature compensation, because the pressure sensing fiber Bragg grating 4 will be affected by the pressure and temperature of the pressure sensing diaphragm 3 at the same time, and the data measured at this time is the result of the combined effect of the two, so the first temperature sensing fiber Bragg grating 6 is provided to measure the internal temperature of the shell, eliminating the error caused by the temperature effect on the pressure sensing fiber Bragg grating 4. If there is no temperature compensation of the first temperature sensing fiber Bragg grating 6, the data obtained by the pressure sensing fiber Bragg grating 4 will not be pure pressure data, but the effect of the combined effect of pressure and temperature, which directly affects the accuracy of the data.

[0031] In some other embodiments, the shell 1 is a rectangular cylindrical shell formed of stainless steel, the pressure-sensitive diaphragm 3 has a certain elasticity, specifically a copper diaphragm with a length of 15 mm, a width of 8 mm and a thickness of 1.5 mm, the pressure-sensitive diaphragm 3 is welded and fixed to the open part of the shell 1, and the pressure-sensing fiber grating 4 is fixed to the center of the pressure-sensitive diaphragm 3 by cyanoacrylate glue, and the pressure-sensing fiber grating is a fiber grating with a central wavelength of 1560 nm.

[0032] In some other specific embodiments, a metal partition 10 is fixed inside the shell 1 corresponding to the detection cavity. The metal partition is made of 304 stainless steel and is located 7 mm below the pressure-sensitive diaphragm. The metal partition 10 is provided with a perforation for the optical fiber to pass through. The perforation is provided with an optical fiber fixing seat 11 for fixing the optical fiber. The optical fiber 5 between the pressure sensing optical fiber grating 4 and the first temperature sensing optical fiber grating 6 is fixed on the metal partition 10.

[0033] In some other specific embodiments, the central wavelength of the first temperature sensing fiber grating 6 and the second temperature sensing fiber grating 8 is the same, both of which are 1540 mm fiber gratings, and the central wavelength of the pressure sensing fiber grating 4 is greater than the central wavelength of the first temperature sensing fiber grating 6 or the second temperature sensing fiber grating 8.

[0034] In other embodiments, the pressure-sensitive diaphragm 3 seals the opening so that the detection cavity 2 is a closed cavity, thereby preventing the pressure effect of external seawater on the first temperature sensing fiber Bragg grating.

[0035] Specific working principle:

[0036] During detection, the external pressure directly acts on the rectangular pressure-sensitive diaphragm, and the center of the pressure-sensitive diaphragm in the x direction forms a uniform deformation, which directly drives the pressure-sensing fiber Bragg grating to bend and deform. The pressure-sensing fiber Bragg grating is affected by both pressure and temperature. Its effective refractive index changes under the influence of external pressure and temperature, causing its central wavelength to shift. When the laser is transmitted through the optical fiber, the band that meets the fiber Bragg grating conditions will be reflected back. The mediation equipment can calculate the external pressure and temperature information through the reflected light. Placing the pressure-sensing fiber Bragg grating and the first temperature-sensing fiber Bragg grating together inside the rectangular cylindrical shell can be regarded as being subjected to the same temperature to achieve temperature compensation.

[0037] This device directly transmits uniform deformation to the fiber Bragg grating through the pressure-sensitive diaphragm, thereby achieving higher pressure sensitivity and pressure response speed; through the technical route based on thermal expansion, the metal silver tube is directly used to encapsulate the fiber Bragg grating, thereby achieving higher temperature sensitivity and temperature response speed; and the pressure operation speed is very small compared with the temperature response speed, achieving the matching of temperature and depth acquisition time. In addition, the pressure sensitivity can be tuned by adjusting the thickness and length of the rectangular pressure-sensitive diaphragm of the pressure measurement part, and the temperature sensitivity can be tuned by adjusting the radius of the metal silver tube of the temperature measurement part.

[0038] The first temperature sensing fiber Bragg grating is only affected by the temperature inside the detection cavity, and the second temperature sensing fiber Bragg grating is only affected by the external temperature. The structure of this device is designed and constructed with metal and optical elements of small size (all within 20mm), and the finished product is easy to carry; this structure can be used for temperature and depth measurement in deep sea areas of the ocean.

[0039] As for the device and the method of use disclosed in the embodiment, since they correspond to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0040] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ocean temperature and depth sensor probe with a fiber Bragg grating series structure, characterized in that: include: A housing (1), wherein a detection cavity (2) is provided inside the housing (1), and an opening is provided at one end of the housing (1) corresponding to the detection cavity (2), and an optical fiber threading hole is provided at the other end; A pressure-sensitive diaphragm (3), wherein the periphery of the pressure-sensitive diaphragm (3) is sealed and fixed to the opening, and a pressure-sensing optical fiber Bragg grating (4) is fixedly connected to the middle of one side of the pressure-sensitive diaphragm (3) close to the detection cavity (2); a first temperature sensing optical fiber Bragg grating (6), the first temperature sensing optical fiber Bragg grating (6) being located in the detection cavity (2) and detecting the temperature in the detection cavity, the first temperature sensing optical fiber Bragg grating (6) being used to compensate for the data error of the pressure sensing optical fiber Bragg grating affected by the temperature of the pressure sensing diaphragm, the first temperature sensing optical fiber Bragg grating (6) being connected in series with the pressure sensing optical fiber Bragg grating (4) using an optical fiber (5); A metal silver tube (7) is fixedly connected to the outer side of one end of the housing (1) corresponding to the optical fiber through hole, and a second temperature sensing optical fiber grating (8) is encapsulated in the metal silver tube (7). The second temperature sensing optical fiber grating (8) is connected in series with the first temperature sensing optical fiber grating (6) to measure the external ambient temperature of the housing, and the second temperature sensing optical fiber grating (8) can be connected to an external regulating device via a lead-out optical fiber (9).

2. The ocean temperature and depth sensor probe of the fiber Bragg grating series structure according to claim 1, characterized in that: The housing (1) is a columnar housing formed of stainless steel, the pressure-sensitive diaphragm (3) is a copper diaphragm, the pressure-sensitive diaphragm (3) is welded and fixed to the open portion of the housing (1), and the pressure-sensing optical fiber grating (4) is fixed to the center of the pressure-sensitive diaphragm (3) by cyanoacrylate glue.

3. The ocean temperature and depth sensor probe of the fiber Bragg grating series structure according to claim 1, characterized in that: A metal partition (10) is fixed inside the housing (1) corresponding to the detection cavity, the metal partition (10) is provided with a perforation for the optical fiber to pass through, and the optical fiber (5) between the pressure sensing optical fiber grating (4) and the first temperature sensing optical fiber grating (6) is fixed on the metal partition (10).

4. The ocean temperature and depth sensor probe of the fiber Bragg grating series structure according to claim 1, characterized in that: The central wavelengths of the first temperature sensing optical fiber grating (6) and the second temperature sensing optical fiber grating (8) are the same, and the central wavelength of the pressure sensing optical fiber grating (4) is greater than the central wavelength of the first temperature sensing optical fiber grating (6) or the second temperature sensing optical fiber grating (8).

5. The ocean temperature and depth sensor probe of the fiber Bragg grating series structure according to claim 1, characterized in that: The pressure-sensitive diaphragm (3) seals the opening so that the detection cavity (2) becomes a closed cavity.

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