Optical fiber ocean multi-parameter measuring device and method

Abstract

The invention provides an optical fiber ocean multi-parameter measuring device and method which can be applied to the technical field of ocean sensors. The optical fiber ocean multi-parameter measuring device comprises a plurality of intensity modulation type optical fiber sensors which are used for respectively acquiring a plurality of light intensity signals sensed by a plurality of ocean parameters based on a monochromatic light source; the plurality of wavelength modulation type optical fiber sensors are used for respectively acquiring a plurality of spectral signals sensed by the plurality of ocean parameters based on the broadband light source; the processor is used for respectively demodulating the plurality of light intensity signals and the plurality of spectral signals by using a real-time demodulation algorithm so as to obtain initial values of ocean parameters respectively corresponding to the plurality of light intensity signals and the plurality of spectral signals; and compensating an initial value of a second ocean parameter associated with the first ocean parameter based on the initial value of the first ocean parameter to obtain a measured value of the second ocean parameter.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the technical field of ocean sensors, and more particularly to an optical fiber ocean multi-parameter measurement device and method. Background Art

[0002] The temperature, pressure, salinity, pH value and dissolved oxygen of seawater are key ocean parameters for ocean research. Ocean parameters are the basis for understanding ocean ecology, carbon cycle, hydrothermal activities, natural gas hydrate distribution and resource exploration. There are many types of sensors for detecting ocean parameters, for example, electrical ocean sensors, discrete sensors, optical fiber ocean sensors, etc. Electrical ocean sensors are relatively mature, but there are technical problems such as high cost, large volume, difficult deployment, and susceptibility to electromagnetic interference. Discrete sensors have technical problems such as complex systems, low reliability and difficult data integration. Optical fiber ocean sensors utilize the sensitive characteristics of optical fibers to environmental changes, integrating sensing and transmission, and are suitable for the ocean environment. Therefore, optical fiber ocean sensors have become a more ideal tool for ocean environment detection.

[0003] In the process of implementing the concept of the present invention, it is found that the related art has at least the following problems: for ocean environment detection, optical fiber ocean sensors need to simultaneously measure multiple ocean parameters, and there are cross-influences between multiple ocean parameters, thus affecting the measurement accuracy of ocean parameters. Summary of the Invention

[0004] In view of the above problems, the present invention provides an optical fiber ocean multi-parameter measurement device and method capable of simultaneously measuring multiple ocean parameters and improving the measurement accuracy.

[0005] According to a first aspect of the present invention, there is provided an optical fiber ocean multi-parameter measurement device, the optical fiber ocean multi-parameter measurement device comprising: a plurality of intensity modulation type optical fiber sensors for respectively collecting a plurality of optical intensity signals sensed for a plurality of ocean parameters based on a monochromatic light source; a plurality of wavelength modulation type optical fiber sensors for respectively collecting a plurality of spectral signals sensed for a plurality of ocean parameters based on a broadband light source; a processor for respectively demodulating the plurality of optical intensity signals and the plurality of spectral signals by using a real-time demodulation algorithm to obtain initial values of the ocean parameters corresponding to the plurality of optical intensity signals and the plurality of spectral signals respectively; and compensating the initial value of a second ocean parameter associated with the first ocean parameter based on the initial value of the first ocean parameter to obtain a measured value of the second ocean parameter; wherein the first ocean parameter includes temperature; and the second ocean parameter includes at least one of the following: salinity, pressure, pH value and dissolved oxygen.

[0006] According to an embodiment of the present invention, when the second ocean parameter includes one of the following: salinity, pressure, pH value, the processor is configured to compensate the initial value of the second ocean parameter based on the initial value of temperature according to a compensation model to obtain the measured value of the second ocean parameter; wherein, the compensation model is obtained according to the calibration relationship between the measured experimental value of temperature and the measured experimental value of the fiber optic sensor for measuring the second ocean parameter.

[0007] According to an embodiment of the present invention, the parameter of dissolved oxygen includes a zero oxygen signal; when the second ocean parameter includes dissolved oxygen, the processor is configured to determine the correction value of the zero oxygen signal based on the initial value of temperature according to a first correction model; wherein, the first correction model is obtained according to the calibration relationship between the measured experimental value of temperature and the measured experimental value of the zero oxygen signal of the dissolved oxygen fiber optic sensor.

[0008] According to an embodiment of the present invention, the parameter of dissolved oxygen includes a quenching constant; when the second ocean parameter includes dissolved oxygen, the processor is configured to determine the correction value of the quenching constant based on the initial value of temperature and the measured value of pressure according to a second correction model; wherein, the second correction model is obtained according to the calibration relationship between the measured experimental value of temperature, the measured experimental value of pressure and the measured experimental value of the quenching constant of the dissolved oxygen fiber optic sensor.

[0009] According to an embodiment of the present invention, the parameter of dissolved oxygen includes the saturated solubility of oxygen in water; when the second ocean parameter includes dissolved oxygen, the processor is configured to determine the correction value of the saturated solubility of oxygen in water based on the initial value of temperature, the measured value of salinity and the measured value of pressure according to a third correction model; wherein, the third correction model is obtained according to the calibration relationship between the measured experimental value of temperature, the measured experimental value of salinity, the measured experimental value of pressure and the measured experimental value of the saturated solubility of oxygen in water of the dissolved oxygen fiber optic sensor.

[0010] According to an embodiment of the present invention, the fiber optic ocean multi-parameter measurement device further includes: a first light source for generating the monochromatic light source; a first fiber optic splitter for splitting the monochromatic light source and respectively incident on the plurality of intensity modulation type fiber optic sensors; a light intensity photoelectric detection component including a plurality of first interfaces, the plurality of first interfaces are correspondingly connected to the plurality of intensity modulation type fiber optic sensors for converting the optical signals reflected back by the plurality of intensity modulation type fiber optic sensors into the plurality of light intensity signals and transmitting the plurality of light intensity signals to the processor.

[0011] According to an embodiment of the present invention, the above-mentioned fiber optic ocean multi-parameter measurement device further includes: a second light source for generating the above-mentioned broadband light source; a second optical fiber splitter for splitting the above-mentioned broadband light source and respectively incident on the above-mentioned multiple wavelength modulation type fiber optic sensors; a spectral optical path demodulation component including multiple second interfaces, the above-mentioned multiple second interfaces are correspondingly connected to the above-mentioned multiple wavelength modulation type fiber optic sensors, and are used for demodulating the optical signals reflected back by the above-mentioned multiple wavelength modulation type fiber optic sensors to obtain the above-mentioned multiple spectral signals; a linear array photodetector connected to the above-mentioned spectral optical path demodulation component, and is used for receiving the above-mentioned multiple spectral signals and transmitting the above-mentioned multiple spectral signals to the above-mentioned processor.

[0012] According to an embodiment of the present invention, the above-mentioned processor is used for demodulating multiple light intensity signals according to the light intensity demodulation program pre-burned in the above-mentioned processor to obtain the initial values of the ocean parameters corresponding to the above-mentioned multiple light intensity signals respectively; according to the spectral demodulation program pre-burned in the above-mentioned processor, demodulating multiple spectral signals to obtain the initial values of the ocean parameters corresponding to the above-mentioned multiple spectral signals respectively.

[0013] According to an embodiment of the present invention, the above-mentioned fiber optic ocean multi-parameter measurement device further includes: a touch interaction device for displaying the initial values and measured values of the above-mentioned multiple ocean parameters, as well as the compensation strategies for different second ocean parameters, so that the above-mentioned processor responds to the above-mentioned compensation strategy to compensate the initial value of the above-mentioned second ocean parameter.

[0014] Another aspect of the present invention provides a measurement method using the above-mentioned fiber optic ocean multi-parameter measurement device. The above-mentioned measurement method includes: using multiple intensity modulation type fiber optic sensors to respectively collect multiple light intensity signals sensed for multiple ocean parameters based on a monochromatic light source; using multiple wavelength modulation type fiber optic sensors to respectively collect multiple spectral signals sensed for multiple ocean parameters based on a broadband light source; using a real-time demodulation algorithm to respectively demodulate the above-mentioned multiple light intensity signals and the above-mentioned multiple spectral signals to obtain the initial values of the ocean parameters corresponding to the above-mentioned multiple light intensity signals and the above-mentioned multiple spectral signals respectively, and based on the initial value of the first ocean parameter, compensating the initial value of the second ocean parameter associated with the above-mentioned first ocean parameter to obtain the measured value of the above-mentioned second ocean parameter; wherein, the above-mentioned first ocean parameter includes temperature; the above-mentioned second ocean parameter includes one of the following: salinity, pressure, pH value, and dissolved oxygen.

[0015] According to an embodiment of the present invention, by combining fiber optic sensors with different principles and laying multiple intensity-modulated fiber optic sensors and multiple wavelength-modulated fiber optic sensors respectively, centralized demodulation of multiple light intensity signals can be performed. Centralized demodulation of multiple spectral signals can simultaneously measure five marine parameters including temperature, pressure, pH, dissolved oxygen, and salinity, simplify data recording, achieve simultaneous acquisition and rapid demodulation of multiple marine parameters, enable a more comprehensive set of parameters for the construction of a fiber optic marine multi-parameter detection system, and improve the efficiency of marine environment detection. According to the correlation relationship between the first marine parameter and the second marine parameter, compensation is performed on the initial value of the second marine parameter to calibrate the fiber optic sensor for marine parameters, so as to weaken the cross-influence between multiple marine parameters, reduce measurement errors, improve the measurement accuracy of multiple marine parameters, enhance the reliability of measurement data, and achieve synchronous and comprehensive detection of marine multi-parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above content and other objects, features, and advantages of the present invention will become clearer through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0017] Figure 1 FIG. shows a schematic diagram of the principle of a fiber optic marine multi-parameter measurement device according to an embodiment of the present invention.

[0018] Figure 2 FIG. shows a schematic diagram of the principle of a fiber optic marine multi-parameter measurement device according to an embodiment of the present invention.

[0019] Figure 3 FIG. shows a schematic diagram of the principle of a fiber optic marine multi-parameter measurement device according to another embodiment of the present invention.

[0020] Figure 4 FIG. shows a schematic diagram of the principle of a fiber optic marine multi-parameter measurement device according to still another embodiment of the present invention.

[0021] Figure 5 FIG. shows a schematic diagram of the principle of a fiber optic marine multi-parameter measurement device according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the purpose of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments can be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0023] The terms used herein are for describing specific embodiments only and are not intended to limit the present invention. The terms "comprising", "including" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not preclude the presence or addition of one or more other features, steps, operations or components.

[0024] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0025] In the case of using expressions such as "at least one of A, B, and C, etc.", generally it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0026] Optical fiber sensors measure various parameters based on changes in optical signals. Changes in external environmental parameters will modulate the optical signals transmitted in the optical fiber, and the measurement data can be obtained through demodulation. Optical fiber sensors have the advantages of small size, light weight, high sensitivity, anti-electromagnetic interference and corrosion, easy arraying, and long-distance transmission. In underwater measurement, it can avoid the short-circuit risk caused by cable water seepage of traditional electrical sensors, thereby extending the service life.

[0027] In the related art, by cascading optical fiber sensors with different structures, different sensing characteristics can be obtained, so as to realize real-time sensing of multiple parameters. However, currently this technology can usually only measure marine physical parameters such as temperature and pressure simultaneously, and the types of measured parameters are limited, which cannot meet the requirements of complex marine environment monitoring. In the related art, regarding measurement systems and methods for realizing simultaneous measurement of multiple parameters, for example, using a miniaturized optical fiber output type light-emitting diode as an excitation light source, combining optical fiber sensing technology and time-division multiplexing detection technology to realize in-situ measurement of various marine dissolved substances such as divalent iron ions, trivalent iron ions, manganese ions, and sulfide ions. For example, using one calibrated laser and three measurement lasers, it is possible to invert the water-gas velocity, temperature, and partial pressure in a high-speed flow field with high precision and rapid synchronization. For example, combining multiple signal acquisition units to detect multiple parameters of temperature, humidity, and conductivity. However, most of the above methods for measuring multiple parameters using optical fiber sensing technology, lasers, or multi-signal measurement technology are applicable to specific environments or measurement objects, and are difficult to be widely applied to complex marine environments.

[0028] For marine environment detection, fiber optic marine sensors need to simultaneously measure multiple marine parameters. However, there are cross - influences among multiple marine parameters, which reduces the measurement accuracy of marine parameters. For example, temperature changes may affect the measurement results of other marine parameters. The marine environment is complex and there are various interference factors (such as water flow, salinity changes, etc.), which affect the measurement accuracy of fiber optic sensors. The collaborative work of multiple fiber optic sensors increases the complexity and integration difficulty of the system, and the real - time performance of data processing is insufficient to meet the requirements of real - time data for marine environment monitoring. Therefore, the technologies of fiber optic marine sensors in aspects such as multi - parameter simultaneous measurement, system integration, and data processing are not yet mature.

[0029] The present invention provides a fiber optic marine multi - parameter measurement device and method, aiming to solve at least one of the above - mentioned technical problems.

[0030] Figure 1 The schematic diagram of the principle of the fiber optic marine multi - parameter measurement device according to an embodiment of the present invention is shown.

[0031] As Figure 1 shown, the fiber optic marine multi - parameter measurement device includes multiple intensity - modulated fiber optic sensors 101, multiple wavelength - modulated fiber optic sensors 102, and a processor 103.

[0032] According to an embodiment of the present invention, multiple intensity - modulated fiber optic sensors 101 are used to respectively collect multiple light intensity signals sensed for multiple marine parameters based on a monochromatic light source. Multiple wavelength - modulated fiber optic sensors 102 are used to respectively collect multiple spectral signals sensed for multiple marine parameters based on a broadband light source. The processor 103 is used to respectively demodulate the multiple light intensity signals and multiple spectral signals by using a real - time demodulation algorithm to obtain the initial values of the marine parameters corresponding to the multiple light intensity signals and multiple spectral signals, and to compensate the initial value of the second marine parameter associated with the first marine parameter based on the initial value of the first marine parameter to obtain the measured value of the second marine parameter; wherein, the first marine parameter includes temperature; the second marine parameter includes at least one of the following: salinity, pressure, pH value, and dissolved oxygen.

[0033] As Figure 1 shown, in one embodiment, multiple intensity - modulated fiber optic sensors 101 may include n intensity - modulated fiber optic sensors, for example: intensity - modulated fiber optic sensor I, intensity - modulated fiber optic sensor II, intensity - modulated fiber optic sensor III. Multiple wavelength - modulated fiber optic sensors 102 may include m wavelength - modulated fiber optic sensors, for example: wavelength - modulated fiber optic sensor I, wavelength - modulated fiber optic sensor II, wavelength - modulated fiber optic sensor III. n is a positive integer, and m is a positive integer.

[0034] In one embodiment, the intensity-modulated fiber optic sensor I can be a fiber optic dissolved oxygen sensor based on fluorescence quenching, or a fiber optic pH sensor based on an indicator, or a tapered fiber optic salinity sensor based on an evanescent wave, etc. In one embodiment, the wavelength-modulated fiber optic sensor I can be a fiber Bragg grating fiber optic temperature sensor, or a composite F-P (Fabry-Pérot) type fiber optic pressure / temperature / salinity sensor, etc. In one embodiment, fiber optic can be used to transmit signals, which can avoid the short-circuit risk caused by cable water seepage in traditional electrical sensors, improve the stability and reliability of the measurement device, make the measurement device more flexible and easier to deploy. In one embodiment, multiple fiber optic sensors can be directly installed on a ship for in-situ measurement, avoiding the errors that may be introduced during signal acquisition, transportation, and storage, and ensuring the accuracy and real-time nature of the measurement results.

[0035] The working principle of fiber optic sensors is usually based on the interaction between optical signal information (such as intensity, wavelength, phase, polarization state, etc.) and the physical or chemical quantity to be measured. The optical or physical properties of the sensing element of the fiber optic sensor or the fiber itself are often affected not only by the physical quantity to be measured but also by other environmental parameters, that is, cross-sensitivity. According to the types and characteristics of each fiber optic sensor, study the correlation relationship between ocean parameters, and specifically compensate for the second ocean parameter and calibrate the fiber optic sensor corresponding to the second ocean parameter in real time.

[0036] According to an embodiment of the present invention, by combining fiber optic sensors with different principles, laying multiple intensity-modulated fiber optic sensors and multiple wavelength-modulated fiber optic sensors respectively, centralized demodulation of multiple light intensity signals and centralized demodulation of multiple spectral signals can be performed, five ocean parameters including temperature, pressure, pH, dissolved oxygen, and salinity can be measured simultaneously, simplifying data recording, achieving simultaneous acquisition and rapid demodulation of multiple ocean parameters, enabling the construction parameters of the fiber optic multi-parameter ocean detection system to be more comprehensive, and improving the efficiency of ocean environment detection. According to the correlation relationship between the first ocean parameter and the second ocean parameter, compensate for the initial value of the second ocean parameter to calibrate the fiber optic sensor of the ocean parameter, so as to weaken the cross-influence between multiple ocean parameters, reduce measurement errors, improve the measurement accuracy of multiple ocean parameters, improve the reliability of measurement data, and achieve synchronous and comprehensive detection of multiple ocean parameters.

[0037] According to an embodiment of the present invention, when the second ocean parameter includes one of the following: salinity, pressure, pH value, the processor is used to compensate for the initial value of the second ocean parameter based on the initial value of temperature according to the compensation model to obtain the measured value of the second ocean parameter; wherein, the compensation model is obtained according to the calibration relationship between the measured experimental value of temperature and the measured experimental value of the fiber optic sensor used to measure the second ocean parameter.

[0038] In one embodiment, the compensation model can be represented by a multivariate polynomial. A multivariate polynomial refers to a polynomial expression containing multiple variables, which can describe complex non-linear relationships. By introducing cross terms and high-order terms, the multi-parameter coupling effect can be accurately modeled, and then the cross-sensitivity can be eliminated through inversion calculation, thereby improving the measurement accuracy of ocean parameters.

[0039] In one embodiment, the processor can be a microprocessor. According to the compensation model, only the influence of temperature needs to be compensated, and the microprocessor can handle operations with relatively low model complexity and low calculation cost.

[0040] The compensation model can use a second-order multivariate polynomial as the following formula (1), based on the initial value of temperature , to compensate the initial value of the second ocean parameter and obtain the measured value of the second ocean parameter .

[0041] (1);

[0042] Where , , , , , are calibration coefficients obtained according to the calibration relationship between the measured experimental values of temperature and the measured experiments of the fiber optic sensor corresponding to the second ocean parameter.

[0043] According to the measurement characteristics of the second ocean parameter, three compensation relationships can be set according to formula (1) of the compensation model.

[0044] The first compensation relationship can be expressed as:

[0045] (2);

[0046] The second compensation relationship can be expressed as:

[0047] (3);

[0048] The third compensation relationship can be expressed as formula (1);

[0049] Wherein, the first compensation relationship is applicable to fiber optic sensors with linear measurement. When the sensitivity of temperature and the second ocean parameter is a linear relationship, the fourth term and the fifth term in formula (1) can be discarded. The second compensation relationship is applicable to fiber optic sensors with linear measurement. When the sensitivity of temperature and the second ocean parameter is a non-linear relationship, the fifth term in formula (1) can be discarded The third compensation relationship is applicable to fiber optic sensors for non-linear measurement.

[0050] In one embodiment, the second ocean parameter may be pressure. For a pressure fiber optic sensor based on a Fabry-Perot cavity, the materials forming the F-P cavity (such as fiber end faces, substrates, adhesives, diaphragms, etc.) will expand and contract thermally, changing the physical length of the F-P cavity. The refractive index of the transmission medium (such as air, a specific gas, a specific liquid, etc.) within the F-P cavity may also change with temperature.

[0051] For a pressure fiber optic sensor, the general design purpose is based on a good linear relationship between pressure and deformation. When the temperature and the pressure sensitivity of the fiber optic pressure sensor are in a linear relationship, the first compensation relationship can be selected; when the temperature and the pressure sensitivity of the fiber optic pressure sensor are in a non-linear relationship, the second compensation relationship can be selected, and the compensation accuracy may be higher. According to the first compensation relationship or the second compensation relationship, based on the initial value of temperature , the initial value of pressure is compensated to obtain the measured value of pressure .

[0052] In one embodiment, the second ocean parameter may be salinity. A salinity fiber optic sensor based on a tapered fiber mainly relies on the special structure of the fiber and the propagation characteristics of light. The sensing principle of the tapered fiber (such as evanescent wave, mode interference, etc.) depends on the refractive index difference between the fiber core and the external environment (water), and thus is sensitive to changes in the refractive index of water. The refractive index of water changes with temperature and salinity. Generally, an increase in temperature will cause a decrease in the refractive index of water, while an increase in salinity will cause an increase in the refractive index of water. Therefore, changes in temperature may mask the influence of salinity changes.

[0053] In one embodiment, the second ocean parameter may be pH value. For a pH value fiber optic sensor based on an indicator, the acid dissociation constant of the indicator is temperature-dependent. The absorption spectrum or fluorescence spectrum characteristics (such as peak wavelength, intensity, quantum yield, etc.) of the indicator dye itself may change with temperature.

[0054] For salinity fiber optic sensors and pH value fiber optic sensors, the measurement is usually based on a non-linear relationship and is suitable for selecting the third compensation relationship. According to the third compensation relationship, based on the initial value of temperature , the initial value of salinity and the initial value of pH are compensated to obtain the measured value of salinity and the measured value of pH.

[0055] According to an embodiment of the present invention, the second ocean parameter may be Dissolved Oxygen (DO). The parameters of dissolved oxygen include the zero oxygen signal , the quenching constant and the saturated solubility of oxygen in water . The saturated solubility of oxygen in water can be used for unit conversion of the concentration of dissolved oxygen . The concentration of dissolved oxygen is the output parameter of the dissolved oxygen fiber optic sensor.

[0056] In one embodiment, the fluorescence quenching-based dissolved oxygen fiber optic sensor measures the concentration of dissolved oxygen in water by detecting the fluorescence quenching phenomenon. The probe of the dissolved oxygen fiber optic sensor is coated with a fluorescent dye to emit fluorescence under the excitation of light at a specific wavelength. When the fluorescent dye comes into contact with dissolved oxygen molecules, the fluorescence intensity will decrease, which is called fluorescence quenching.

[0057] The change in fluorescence intensity can be described by the Stern-Volmer equation:

[0058] (4);

[0059] where, the zero oxygen signal represents the intrinsic fluorescence intensity under zero oxygen conditions; is the fluorescence intensity under actual conditions.

[0060] The influence of temperature on the parameters of dissolved oxygen: For a fluorescence quenching-based dissolved oxygen fiber optic sensor, the fluorescence lifetime or intensity of its fluorescent substance is itself susceptible to temperature: as the temperature increases, non-radiative transitions increase, and the fluorescence lifetime or intensity usually decreases. The collision efficiency between oxygen and the fluorescent substance is also affected by temperature: usually as the temperature increases, molecular motion speeds up, and the collision efficiency increases, but sometimes factors such as solubility changes also have an impact. Under the superposition of the two effects, at the same oxygen concentration, the fluorescence lifetime or intensity measured at different temperatures is different.

[0061] The influence of pressure on the parameters of dissolved oxygen: On the one hand, hydrostatic pressure will increase the solubility of gases (following the pressure effect of Henry's law). The greater the depth, the higher the pressure, and the higher the concentration of oxygen that water can dissolve at the same saturation. When it is necessary to convert the sensor reading to a concentration unit, the influence of pressure on the saturation concentration must be considered. On the other hand, hydrostatic pressure may compress the sensing film polymer matrix of the dissolved oxygen fiber optic sensor, changing its free volume and structure, thereby possibly changing the diffusion coefficient of oxygen in the film and directly affecting the quenching constant , resulting in different readings of the dissolved oxygen fiber optic sensor at the same oxygen partial pressure. The magnitude of the influence depends on the mechanical properties of the membrane material and the pressure range.

[0062] Effect of salinity on dissolved oxygen parameters: An increase in salinity reduces the physical solubility of oxygen in water (salting-out effect). At the same temperature, pressure, and air saturation, the dissolved oxygen concentration (e.g., in mg / L or μmol / L) in salt water is lower than that in fresh water. When converting the original signal of the sensor to a common concentration unit (e.g., mg / L or μmol / L), salinity compensation is required.

[0063] According to an embodiment of the present invention, the processor is configured to determine a correction value of the zero-oxygen signal based on the initial value of the temperature according to a first correction model; wherein, the first correction model is obtained according to the calibration relationship between the measured experimental values of the temperature and the measured experimental values of the zero-oxygen signal of the dissolved oxygen fiber optic sensor.

[0064] In one embodiment, the zero-oxygen signal is used to calibrate and verify the accuracy of the dissolved oxygen fiber optic sensor. The intrinsic fluorescence intensity of the fluorescent material of the dissolved oxygen fiber optic sensor generally decreases with increasing temperature (thermal quenching). The zero-oxygen signal is usually non-linearly affected by temperature and may be close to exponential decay. Within a limited temperature range, the first correction model can be simplified to a low-order polynomial:

[0065] (5);

[0066] wherein, , , are calibration coefficients according to the calibration relationship between the measured experimental values of the temperature and the measured experimental values of the zero-oxygen signal of the dissolved oxygen fiber optic sensor.

[0067] According to an embodiment of the present invention, the processor is configured to determine a correction value of the quenching constant based on the initial value of the temperature and the measured value of the pressure according to a second correction model; wherein, the second correction model is obtained according to the calibration relationship between the measured experimental values of the temperature, the measured experimental values of the pressure, and the measured experimental values of the quenching constant of the dissolved oxygen fiber optic sensor.

[0068] The quenching constant can reflect the relative change in fluorescence intensity under aerobic and anaerobic conditions. The quenching constant mainly depends on the diffusion coefficient of oxygen in the sensing film of the dissolved oxygen fiber optic sensor and the quenching reaction rate constant. Both the diffusion coefficient and the quenching reaction rate constant are strongly affected by temperature and, to a certain extent, by pressure.

[0069] In one embodiment, the second correction model can be simplified to a binary second-order polynomial:

[0070] (6);

[0071] Among them, , , , , , are calibration coefficients according to the calibration relationship between the measured experimental values of temperature, the measured experimental values of pressure, and the measured experimental values of the quenching constant of the dissolved oxygen fiber optic sensor.

[0072] According to an embodiment of the present invention, the processor is configured to determine a corrected value of the saturated solubility of oxygen in water based on the initial value of temperature, the measured value of salinity, and the measured value of pressure according to the third correction model; wherein, the third correction model is obtained according to the calibration relationship between the measured experimental values of temperature, the measured experimental values of salinity, the measured experimental values of pressure, and the measured experimental values of the saturated solubility of oxygen in water of the dissolved oxygen fiber optic sensor.

[0073] In one embodiment, the saturated solubility of oxygen in water is determined by complex physical and chemical laws and includes complex logarithmic, exponential, and higher-order polynomial terms. Within a limited range of temperature, salinity, and pressure, the third correction model can be simplified to a relatively low-order three-variable polynomial:

[0074] (7);

[0075] Among them, , , , , , , , , are calibration coefficients according to the calibration relationship between the measured experimental values of temperature, the measured experimental values of salinity, the measured experimental values of pressure, and the measured experimental values of the saturated solubility of oxygen in water of the dissolved oxygen fiber optic sensor.

[0076] According to an embodiment of the present invention, according to the initial value of the calculated temperature, the measured value of the compensated salinity, and the measured value of pressure, the parameters of the dissolved oxygen can be corrected according to the corresponding first correction model, second correction model, and third correction model to realize the correction of the initial value of the dissolved oxygen and obtain the measured value of the dissolved oxygen.

[0077] Figure 2 shows a schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to an embodiment of the present invention.

[0078] As Figure 2 shown, the optical fiber ocean multi-parameter measurement device further includes a first light source 104, a first optical fiber splitter 105, and a light intensity photoelectric detection component 106.

[0079] According to an embodiment of the present invention, the first light source 104 is used to generate a monochromatic light source. The first optical fiber splitter 105 is used to split the monochromatic light source and respectively incident on a plurality of intensity modulation type optical fiber sensors 101. The light intensity photoelectric detection component 106 includes a plurality of first interfaces, and the plurality of first interfaces are correspondingly connected to the plurality of intensity modulation type optical fiber sensors 101, and are used to convert the optical signals reflected back by the plurality of intensity modulation type optical fiber sensors 101 into a plurality of light intensity signals and transmit the plurality of light intensity signals to the processor 103.

[0080] As Figure 2 shown, in one embodiment, the first light source 104 and the first optical fiber splitter 105 can be connected by an optical fiber. The first optical fiber splitter 105 and the n intensity modulation type optical fiber sensors 101 can be connected by n Y-shaped optical fibers. The light intensity photoelectric detection component 106 includes n first interfaces, and the first interfaces can be FC (Ferrule Connector) interfaces, and are respectively connected to the other ends of the n Y-shaped optical fibers. The light intensity photoelectric detection component 106 further includes n light intensity photodetectors. Among them, the light intensity photodetector I is connected to the intensity modulation type optical fiber sensor I through a Y-shaped optical fiber; the light intensity photodetector II is connected to the intensity modulation type optical fiber sensor II through a Y-shaped optical fiber; the light intensity photodetector III is connected to the intensity modulation type optical fiber sensor III through a Y-shaped optical fiber, constituting n independent measurement channels.

[0081] Figure 3 The schematic diagram of the principle of the optical fiber ocean multi-parameter measurement device according to another embodiment of the present invention is shown.

[0082] As Figure 3 shown, the optical fiber ocean multi-parameter measurement device further includes a second light source 107, a second optical fiber splitter 108, a spectroscopic optical path demodulation component 109 and a linear array photodetector 110.

[0083] According to an embodiment of the present invention, the second light source 107 is used to generate a broadband light source. The second optical fiber splitter 108 is used to split the broadband light source and respectively incident on a plurality of wavelength modulation type optical fiber sensors 102. The spectroscopic optical path demodulation component 109 includes a plurality of second interfaces, and the plurality of second interfaces are correspondingly connected to the plurality of wavelength modulation type optical fiber sensors 102, and are used to demodulate the optical signals reflected back by the plurality of wavelength modulation type optical fiber sensors 102 to obtain a plurality of spectral signals. The linear array photodetector 110 is connected to the spectroscopic optical path demodulation component 109 and is used to receive the plurality of spectral signals and transmit the plurality of spectral signals to the processor 103.

[0084] As Figure 3As shown, in one embodiment, the second light source 107 and the second optical fiber splitter 108 can be connected by an optical fiber. The second optical fiber splitter 108 and the m wavelength modulation type optical fiber sensors 102 can be connected by m Y-shaped optical fibers. The spectral light path demodulation component 109 includes m second interfaces, and the second interfaces can be FC interfaces, which are respectively connected to the other ends of the m Y-shaped optical fibers. The spectral light path demodulation component 109 further includes m spectral light path demodulators. Among them, the spectral light path demodulator I is connected to the wavelength modulation type optical fiber sensor I through a Y-shaped optical fiber; the spectral light path demodulator II is connected to the wavelength modulation type optical fiber sensor II through a Y-shaped optical fiber; the spectral light path demodulator III is connected to the wavelength modulation type optical fiber sensor III through a Y-shaped optical fiber, constituting m independent measurement channels.

[0085] According to an embodiment of the present invention, the processor 103 is used to demodulate multiple light intensity signals according to the light intensity demodulation program pre-burned in the processor to obtain the initial values of the ocean parameters respectively corresponding to the multiple light intensity signals. According to the spectral demodulation program pre-burned in the processor, multiple spectral signals are demodulated to obtain the initial values of the ocean parameters respectively corresponding to the multiple spectral signals.

[0086] Figure 4 The schematic diagram of the principle of the optical fiber ocean multi-parameter measurement device according to another embodiment of the present invention is shown.

[0087] As Figure 4 shown, the optical fiber ocean multi-parameter measurement device further includes a touch interaction device 111.

[0088] According to an embodiment of the present invention, the touch interaction device 111 is used to display the initial values and measured values of multiple ocean parameters, as well as the compensation strategies for different second ocean parameters, so that the processor 103 compensates the initial values of the second ocean parameters in response to the compensation strategies.

[0089] According to an embodiment of the present invention, the processor 103 is pre-burned with compensation algorithms designed according to the principles and characteristics of each sensor, including compensation models, first correction models, second correction models, third correction models, etc. The touch interaction device 111 can select corresponding compensation strategies according to the compensation requirements of the optical fiber sensors connected to the optical fiber ocean multi-parameter measurement device on the interaction interface.

[0090] Figure 5 The schematic diagram of the principle of the optical fiber ocean multi-parameter measurement device according to still another embodiment of the present invention is shown.

[0091] As Figure 5As shown, in one embodiment, an intensity modulation type fiber optic sensor may include: a fiber optic dissolved oxygen sensor based on fluorescence quenching, a fiber optic pH sensor based on an indicator, and a tapered fiber optic salinity sensor based on an evanescent wave. A wavelength modulation type fiber optic sensor may include: a fiber Bragg grating fiber optic temperature sensor and a composite F-P type fiber optic pressure sensor. Three intensity modulation type fiber optic sensors and two wavelength modulation type fiber optic sensors are placed in a marine environment.

[0092] As Figure 5 shown, in one embodiment, the first light source may be a 405 nm laser light source, and the 405 nm laser light source may be a fiber coupled laser light source. The first fiber optic splitter may be a 1*3 fiber optic splitter. The three intensity modulation type fiber optic sensors may include fiber optic sensor I (a fiber optic dissolved oxygen sensor based on fluorescence quenching), fiber optic sensor II (a fiber optic pH sensor based on an indicator), and fiber optic sensor III (a tapered fiber optic salinity sensor based on an evanescent wave). They receive the 405 nm laser light source through three Y-shaped fiber optics, and then the other ends of the three Y-shaped fiber optics are connected to three FC interfaces of a light intensity photoelectric detection component, and the reflected optical signals are respectively input into photodetector I, photodetector II, and photodetector III. Photodetector I, photodetector II, and photodetector III may be silicon photodetectors with built-in amplification, with a wavelength range of 200 nm - 1100 nm and an output voltage range of 0 V - 10 V in the high impedance output mode.

[0093] As Figure 5 shown, in one embodiment, the second light source may be an SLD (Superluminescent Diode) broadband light source, and the SLD broadband light source may be a near-infrared broadband light source with a central wavelength of 1550 nm, and the wavelength range may be 1500 nm - 1600 nm. The second fiber optic splitter may be a 1*2 fiber optic splitter. The two wavelength modulation type fiber optic sensors may include fiber optic sensor IV (a composite F-P type fiber optic pressure sensor) and fiber optic sensor V (a fiber Bragg grating fiber optic temperature sensor). They receive the near-infrared broadband light source with a central wavelength of 1550 nm through two Y-shaped fiber optics, and then respectively reflect the optical signals to a spectral optical path demodulator I and a spectral optical path demodulator II.

[0094] As Figure 5As shown, in one embodiment, the processor can be a single-chip microcomputer. The light intensity optoelectronic detection component is connected to multiple channels of the analog-to-digital converter of the single-chip microcomputer peripheral resources, and the analog voltage signals of the three light intensity signals are subjected to analog-to-digital conversion by adopting a multi-channel continuous conversion mode based on the direct memory access transfer mode. The linear array optoelectronic detector is connected to the serial port resource of the single-chip microcomputer, and the analog voltage signals of the two spectral signals are transmitted to the single-chip microcomputer through serial port communication, and the analog voltage signals of the two spectral signals are subjected to analog-to-digital conversion. The single-chip microcomputer demodulates the digital signals of the three light intensity signals according to the light intensity demodulation program pre-burned inside the single-chip microcomputer to obtain the initial values of the ocean parameters salinity, pH value, and dissolved oxygen. The single-chip microcomputer demodulates the digital signals of the two spectral signals according to the spectral demodulation program pre-burned inside the single-chip microcomputer to obtain the initial values of the ocean parameters temperature and pressure.

[0095] As Figure 5 shown, in one embodiment, the touch interaction device includes a Bluetooth connector to connect to an external device in a wireless connection manner, increasing the flexibility of data detection. The touch interaction device further includes a touch screen to implement the display function and the touch function in a wired connection manner. The touch screen can be a serial port screen with a capacitive touch module, and an interaction interface program for demodulation algorithms and data display is burned. The touch interaction device can detect the working state of the sensor and the data analysis result in real time.

[0096] In one embodiment, the serial port screen can display the initial values of temperature, pressure, salinity, pH value, and dissolved oxygen. It can also display the type of the corresponding fiber optic sensor. According to the type of the fiber optic sensor corresponding to the ocean parameter, the corresponding compensation strategy is selected. For example, for the evanescent wave-based tapered fiber optic salinity sensor corresponding to the ocean parameter salinity, it is suitable to use the third compensation relationship. The third compensation relationship and the calibration coefficient of the third compensation relationship are selected to calibrate the evanescent wave-based tapered fiber optic salinity sensor, adjust the state of the evanescent wave-based tapered fiber optic salinity sensor, and obtain the measured value of the ocean parameter salinity. Similarly, the measured values of the ocean parameters pressure and pH value are obtained. Similarly, based on the initial value of temperature, the measured value of salinity, and the measured value of pressure, the first correction model, the second correction model, the third correction model, and the corresponding calibration coefficients are selected to correct the parameter of dissolved oxygen, and the measured value of the ocean parameter dissolved oxygen is obtained. The serial port screen can also display the initial value of temperature, the measured value of pressure, the measured value of salinity, the measured value of pH value, and the measured value of dissolved oxygen in real time according to the burned display program.

[0097] In one embodiment, the fiber optic ocean multi-parameter measurement device further includes a power supply to provide power for the above-mentioned device equipment.

[0098] In one embodiment, the intensity modulation type fiber optic sensor may further include: a fiber optic dissolved oxygen sensor based on fluorescence quenching, and a fiber optic pH sensor based on an indicator. The wavelength modulation type fiber optic sensor may further include: a composite F-P type fiber optic pressure sensor and a composite F-P type fiber optic temperature and salinity sensor. Two intensity modulation type fiber optic sensors and two wavelength modulation type fiber optic sensors are placed in a marine environment. The processor 103 measures the seawater temperature, pressure, salinity, pH value, and dissolved oxygen in real time according to the corresponding demodulation algorithms and compensation models pre-programmed in the corresponding fiber optic sensors.

[0099] The fiber optic marine multi-parameter measuring device according to the embodiment of the present invention adopts an integrated and modular design, with light weight, small volume, low power consumption, and low cost. The fiber optic marine multi-parameter measuring device according to the embodiment of the present invention is configured with a user-friendly software interface, which can display the measurement data of various marine parameters in real time, realize data visualization, facilitate real-time detection and understanding of the marine environment conditions, simplify the operation process, and shorten the measurement time. The fiber optic marine multi-parameter measuring device according to the embodiment of the present invention provides two data transmission modes, wired and wireless, increasing the flexibility of data detection. The fiber optic marine multi-parameter measuring device according to the embodiment of the present invention can also be extended to the real-time measurement and demodulation applications of other fiber optic marine sensors.

[0100] The present invention also provides a measurement method using the fiber optic marine multi-parameter measuring device. The measurement method includes: using a plurality of intensity modulation type fiber optic sensors, based on a monochromatic light source, respectively collecting a plurality of light intensity signals sensed for a plurality of marine parameters; using a plurality of wavelength modulation type fiber optic sensors, based on a broadband light source, respectively collecting a plurality of spectral signals sensed for a plurality of marine parameters; using a real-time demodulation algorithm to demodulate the plurality of light intensity signals and the plurality of spectral signals respectively to obtain the initial values of the marine parameters corresponding to the plurality of light intensity signals and the plurality of spectral signals respectively, and based on the initial value of the first marine parameter, compensating the initial value of the second marine parameter associated with the first marine parameter to obtain the measured value of the second marine parameter; wherein, the first marine parameter includes temperature; the second marine parameter includes one of the following: salinity, pressure, pH value, and dissolved oxygen.

[0101] Those skilled in the art can understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0102] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. An optical fiber ocean multi-parameter measurement device, characterized in that, The fiber optic ocean multi-parameter measurement device includes: A plurality of intensity modulation type fiber optic sensors, which are used to respectively collect a plurality of optical intensity signals sensed by a plurality of ocean parameters based on a monochromatic light source; A plurality of wavelength modulation type fiber optic sensors, which are used to respectively collect a plurality of spectral signals sensed by a plurality of ocean parameters based on a broadband light source; A processor, which is used to demodulate the plurality of optical intensity signals and the plurality of spectral signals respectively by using a real-time demodulation algorithm to obtain the initial values of the ocean parameters corresponding to the plurality of optical intensity signals and the plurality of spectral signals respectively; based on the initial value of the first ocean parameter, compensate the initial value of the second ocean parameter associated with the first ocean parameter to obtain the measured value of the second ocean parameter; wherein, the first ocean parameter includes temperature; the second ocean parameter includes at least one of the following: salinity, pressure, pH value, and dissolved oxygen.

2. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, In the case where the second ocean parameter includes one of the following: salinity, pressure, pH value, The processor is used to compensate the initial value of the second ocean parameter based on the initial value of temperature according to a compensation model to obtain the measured value of the second ocean parameter; wherein, the compensation model is obtained according to the calibration relationship between the measured experimental value of temperature and the measured experimental value of the fiber optic sensor used to measure the second ocean parameter.

3. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The parameter of the dissolved oxygen includes a zero oxygen signal; in the case where the second ocean parameter includes dissolved oxygen, The processor is used to determine the correction value of the zero oxygen signal based on the initial value of temperature according to a first correction model; wherein, the first correction model is obtained according to the calibration relationship between the measured experimental value of temperature and the measured experimental value of the zero oxygen signal of the dissolved oxygen fiber optic sensor.

4. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The parameter of the dissolved oxygen includes a quenching constant; in the case where the second ocean parameter includes dissolved oxygen, The processor is used to determine the correction value of the quenching constant based on the initial value of temperature and the measured value of pressure according to a second correction model; wherein, the second correction model is obtained according to the calibration relationship between the measured experimental value of temperature, the measured experimental value of pressure, and the measured experimental value of the quenching constant of the dissolved oxygen fiber optic sensor.

5. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The parameter of the dissolved oxygen includes the saturated solubility of oxygen in water; in the case where the second ocean parameter includes dissolved oxygen, The processor is used to determine the correction value of the saturated solubility of oxygen in water based on the initial value of temperature, the measured value of salinity, and the measured value of pressure according to a third correction model; wherein, the third correction model is obtained according to the calibration relationship between the measured experimental value of temperature, the measured experimental value of salinity, the measured experimental value of pressure, and the measured experimental value of the saturated solubility of oxygen in water of the dissolved oxygen fiber optic sensor.

6. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The fiber optic ocean multi-parameter measurement device further includes: A first light source, which is used to generate the monochromatic light source; A first fiber optic splitter, which is used to split the monochromatic light source and respectively incident the plurality of intensity modulation type fiber optic sensors; The light intensity photoelectric detection component includes a plurality of first interfaces, and the plurality of first interfaces are correspondingly connected to the plurality of intensity modulation type fiber optic sensors, and are used for converting the optical signals reflected back by the plurality of intensity modulation type fiber optic sensors into the plurality of light intensity signals, and transmitting the plurality of light intensity signals to the processor.

7. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The fiber optic ocean multi-parameter measuring device further includes: A second light source, which is used for generating the broadband light source; A second fiber optic splitter, which is used for splitting the broadband light source and respectively injecting it into the plurality of wavelength modulation type fiber optic sensors; A spectral optical path demodulation component, which includes a plurality of second interfaces, and the plurality of second interfaces are correspondingly connected to the plurality of wavelength modulation type fiber optic sensors, and are used for demodulating the optical signals reflected back by the plurality of wavelength modulation type fiber optic sensors to obtain the plurality of spectral signals; A linear array photodetector, which is connected to the spectral optical path demodulation component, and is used for receiving the plurality of spectral signals and transmitting the plurality of spectral signals to the processor.

8. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The processor is used for demodulating the plurality of light intensity signals according to the light intensity demodulation program pre-burned in the processor to obtain the initial values of the ocean parameters respectively corresponding to the plurality of light intensity signals; and demodulating the plurality of spectral signals according to the spectral demodulation program pre-burned in the processor to obtain the initial values of the ocean parameters respectively corresponding to the plurality of spectral signals.

9. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that, The fiber optic ocean multi-parameter measuring device further includes: A touch interaction device, which is used for displaying the initial values and measured values of the plurality of ocean parameters, as well as the compensation strategies for different second ocean parameters, so that the processor compensates the initial values of the second ocean parameters in response to the compensation strategies.

10. A measurement method using the optical fiber ocean multi-parameter measurement device according to any one of claims 1-9, characterized in that, The measuring method includes: Using a plurality of intensity modulation type fiber optic sensors, based on a monochromatic light source, respectively collecting a plurality of light intensity signals sensed for a plurality of ocean parameters; Using a plurality of wavelength modulation type fiber optic sensors, based on a broadband light source, respectively collecting a plurality of spectral signals sensed for a plurality of ocean parameters; Using a real-time demodulation algorithm to respectively demodulate the plurality of light intensity signals and the plurality of spectral signals to obtain the initial values of the ocean parameters respectively corresponding to the plurality of light intensity signals and the plurality of spectral signals, and based on the initial value of the first ocean parameter, compensating the initial value of the second ocean parameter associated with the first ocean parameter to obtain the measured value of the second ocean parameter; wherein, the first ocean parameter includes temperature; the second ocean parameter includes one of the following: salinity, pressure, pH value, and dissolved oxygen.

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