Optical fiber ocean multi-parameter measurement device and method

Abstract

The present invention provides an optical fiber ocean multi-parameter measurement device and method, which can be applied to the field of ocean sensor technology. The optical fiber ocean multi-parameter measurement device includes: multiple intensity-modulated optical fiber sensors, which are used to respectively collect multiple light intensity signals sensed by multiple ocean parameters based on a monochromatic light source; multiple wavelength-modulated optical fiber sensors, which are used to respectively collect multiple spectral signals sensed by multiple ocean parameters based on a broadband light source; a processor, which uses a real-time demodulation algorithm to demodulate the multiple light intensity signals and the multiple spectral signals to obtain initial values of the ocean parameters corresponding to the multiple light intensity signals and the multiple spectral signals; and, based on the initial value of the first ocean parameter, compensates the initial value of a second ocean parameter associated with 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 field of ocean sensor technology, and more specifically to an optical fiber ocean multi-parameter measurement device and method. Background Art

[0002] Seawater temperature, pressure, salinity, pH, and dissolved oxygen are key oceanographic parameters for ocean research. These parameters are fundamental to understanding marine ecology, carbon cycling, hydrothermal activity, natural gas hydrate distribution, and resource exploration. Numerous types of sensors are available for detecting these parameters, including electrical oceanographic sensors, discrete sensors, and fiber-optic oceanographic sensors. Electrical oceanographic sensors are relatively mature, but they present technical challenges such as high cost, large size, difficulty in deployment, and susceptibility to electromagnetic interference. Discrete sensors also present technical challenges such as system complexity, low reliability, and difficulty integrating data. Fiber-optic oceanographic sensors utilize the sensitivity of optical fibers to environmental changes, integrating both sensing and transmission, making them suitable for marine environments. Therefore, fiber-optic oceanographic sensors have become a more ideal tool for monitoring the marine environment.

[0003] In the process of implementing the concept of the present invention, it was found that the related technologies have at least the following problems: for marine environment detection, optical fiber ocean sensors need to measure multiple marine parameters simultaneously, and there are cross-influences between the multiple marine parameters, which affects the measurement accuracy of the marine 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 that can measure multiple ocean parameters simultaneously and improve measurement accuracy.

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

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

[0007] According to an embodiment of the present invention, the parameter of dissolved oxygen includes a zero oxygen signal; when the above-mentioned second ocean parameter includes dissolved oxygen, the above-mentioned processor is used to determine the correction value of the above-mentioned zero oxygen signal based on the initial value of temperature according to a first correction model; wherein the above-mentioned 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 above-mentioned dissolved oxygen parameter includes a quenching constant; when the above-mentioned second ocean parameter includes dissolved oxygen, the above-mentioned processor is used to determine the correction value of the above-mentioned quenching constant based on the initial value of temperature and the measured value of pressure according to a second correction model; wherein the above-mentioned 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 above-mentioned dissolved oxygen parameter includes the saturated solubility of oxygen in water; when the above-mentioned second ocean parameter includes dissolved oxygen, the above-mentioned processor is used to determine the correction value of the above-mentioned 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 above-mentioned third correction model is obtained based on 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 above-mentioned optical fiber ocean multi-parameter measurement device also includes: a first light source, used to generate the above-mentioned monochromatic light source; a first optical fiber splitter, used to split the above-mentioned monochromatic light source and respectively input the above-mentioned multiple intensity-modulated optical fiber sensors; a light intensity photoelectric detection component, including multiple first interfaces, and the above-mentioned multiple first interfaces are correspondingly connected to the above-mentioned multiple intensity-modulated optical fiber sensors, for converting the light signals reflected back by the above-mentioned multiple intensity-modulated optical fiber sensors into the above-mentioned multiple light intensity signals, and transmitting the above-mentioned multiple light intensity signals to the above-mentioned processor.

[0011] According to an embodiment of the present invention, the above-mentioned optical fiber ocean multi-parameter measurement device also 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-modulated optical fiber sensors; a splitting optical path demodulation component, including multiple second interfaces, and the above-mentioned multiple second interfaces are correspondingly connected to the above-mentioned multiple wavelength-modulated optical fiber sensors, for demodulating the optical signals reflected back by the above-mentioned multiple wavelength-modulated optical fiber sensors to obtain the above-mentioned multiple spectral signals; a linear array photodetector, connected to the above-mentioned splitting optical path demodulation component, 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 to demodulate multiple light intensity signals according to a light intensity demodulation program pre-burned in the above-mentioned processor, and obtain the initial values of the ocean parameters corresponding to the above-mentioned multiple light intensity signals respectively; according to the spectrum demodulation program pre-burned in the above-mentioned processor, it demodulates multiple spectrum signals and obtains the initial values of the ocean parameters corresponding to the above-mentioned multiple spectrum signals respectively.

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

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

[0015] According to an embodiment of the present invention, by combining optical fiber sensors based on different principles and laying multiple intensity-modulated optical fiber sensors and multiple wavelength-modulated optical fiber sensors, multiple light intensity signals can be centrally demodulated. By centrally demodulating multiple spectral signals, five ocean parameters, namely temperature, pressure, pH, dissolved oxygen, and salinity, can be measured simultaneously, which simplifies data recording and enables simultaneous acquisition and rapid demodulation of multiple ocean parameters. This enables the construction of an optical fiber ocean multi-parameter detection system with more comprehensive parameters and improves the efficiency of ocean environment detection. Based on the correlation between the first ocean parameter and the second ocean parameter, the initial value of the second ocean parameter is compensated to achieve calibration of the optical fiber sensor for the ocean parameters, thereby reducing the cross-influence between the multiple ocean parameters, reducing measurement errors, improving the measurement accuracy of the multiple ocean parameters, and improving the reliability of the measurement data, thereby achieving synchronous and comprehensive detection of the ocean multi-parameters. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0017] Figure 1 A schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to another embodiment of the present invention is shown.

[0020] Figure 4 A schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to another embodiment of the present invention is shown.

[0021] Figure 5 A schematic diagram of the principle of an optical fiber ocean multi-parameter measurement device according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[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 exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0023] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude 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] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with 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 is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0026] Fiber optic sensors measure various parameters based on changes in optical signals. Changes in external environmental parameters modulate the optical signal transmitted within the fiber, and measurement data is obtained through demodulation. Fiber optic sensors offer advantages such as small size, light weight, high sensitivity, resistance to electromagnetic interference and corrosion, ease of arraying, and long-distance transmission. In underwater measurements, they avoid the risk of short circuits caused by water seepage in cables, often associated with traditional electrical sensors, thereby extending their service life.

[0027] In the related art, by cascading optical fiber sensors of different structures, different sensing characteristics can be obtained, thereby realizing real-time sensing of multiple parameters. However, at present, this technology can usually only measure ocean physical parameters such as temperature and pressure at the same time, and the types of parameters measured are limited, which cannot meet the needs of complex marine environment monitoring. In the related art, regarding the measurement system and method for realizing simultaneous measurement of multiple parameters, for example, a miniaturized optical fiber output light-emitting diode is used as an excitation light source, combined with 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 sulfur ions. For example, using a calibration laser and three measurement lasers, it is possible to quickly and synchronously invert the water vapor velocity, temperature and partial pressure in a high-speed flow field with high precision. For example, multiple signal acquisition units are combined to detect multiple parameters such as temperature, humidity and conductivity. However, the above-mentioned methods of using optical fiber sensing technology, laser, or multi-signal measurement technology to perform multi-parameter measurement are mostly applicable to specific environments or measurement objects, and are difficult to be widely used in complex marine environments.

[0028] Fiber-optic ocean sensors for monitoring the ocean environment need to simultaneously measure multiple ocean parameters. However, these parameters can interact with each other, reducing measurement accuracy. For example, temperature fluctuations can affect the measurement of other ocean parameters. The complex ocean environment is subject to numerous interfering factors (such as currents and salinity fluctuations), which can affect the measurement accuracy of fiber-optic sensors. The coordinated operation of multiple fiber-optic sensors increases system complexity and integration difficulties, resulting in insufficient real-time data processing and the inability to meet the real-time data requirements of ocean environmental monitoring. Consequently, the technology behind fiber-optic ocean sensors for simultaneous multi-parameter measurement, system integration, and data processing is still immature.

[0029] The present invention provides an optical fiber ocean multi-parameter measurement device and method, in order to solve at least one of the above technical problems.

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

[0031] like Figure 1 As shown, the optical fiber ocean multi-parameter measurement device includes a plurality of intensity-modulated optical fiber sensors 101 , a plurality of wavelength-modulated optical fiber sensors 102 and a processor 103 .

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

[0033] like Figure 1 As shown, in one embodiment, the plurality of intensity-modulated optical fiber sensors 101 may include n intensity-modulated optical fiber sensors, for example, intensity-modulated optical fiber sensor I, intensity-modulated optical fiber sensor II, and intensity-modulated optical fiber sensor III. The plurality of wavelength-modulated optical fiber sensors 102 may include m wavelength-modulated optical fiber sensors, for example, wavelength-modulated optical fiber sensor I, wavelength-modulated optical fiber sensor II, and wavelength-modulated optical fiber 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, an indicator-based fiber optic pH sensor, or a tapered fiber optic salinity sensor based on evanescent waves. In one embodiment, the wavelength-modulated fiber optic sensor I can be a fiber Bragg grating fiber optic temperature sensor, or a composite Fabry-Perot (Fabry-Perot) fiber optic pressure / temperature / salinity sensor. In one embodiment, optical fiber can be used for signal transmission, eliminating the risk of short circuits caused by water seepage in traditional electrical sensors, improving the stability and reliability of the measurement device, and making it more flexible and easier to deploy. In one embodiment, multiple fiber optic sensors can be installed directly on board a vessel for in-situ measurement, avoiding errors that may be introduced during signal acquisition, transportation, and storage, and ensuring accurate and real-time measurement results.

[0035] The operating principle of fiber optic sensors is typically based on the interaction between optical signal information (such as intensity, wavelength, phase, and polarization state) and the physical or chemical quantity being measured. The optical or physical properties of a fiber optic sensor's sensing element or the optical fiber itself are often influenced not only by the physical quantity being measured but also by other environmental parameters, a phenomenon known as cross-sensitivity. Based on the type and characteristics of each fiber optic sensor, the correlation between oceanographic parameters is studied, allowing for targeted compensation of a second oceanographic parameter and real-time calibration of the fiber optic sensor corresponding to that second oceanographic parameter.

[0036] According to an embodiment of the present invention, by combining optical fiber sensors based on different principles and laying multiple intensity-modulated optical fiber sensors and multiple wavelength-modulated optical fiber sensors, multiple light intensity signals can be centrally demodulated, multiple spectral signals can be centrally demodulated, and five ocean parameters, namely temperature, pressure, pH, dissolved oxygen, and salinity, can be measured simultaneously, simplifying data recording and achieving simultaneous acquisition and rapid demodulation of multiple ocean parameters. This enables the construction of an optical fiber ocean multi-parameter detection system with more comprehensive parameters and improves the efficiency of ocean environment detection. Based on the correlation between the first ocean parameter and the second ocean parameter, the initial value of the second ocean parameter is compensated to achieve calibration of the optical fiber sensor for the ocean parameters, thereby reducing the cross-influence between the multiple ocean parameters, reducing measurement errors, improving the measurement accuracy of the multiple ocean parameters, and improving the reliability of the measurement data, thereby achieving synchronous and comprehensive detection of the ocean multi-parameters.

[0037] According to an embodiment of the present invention, when the second ocean parameter includes one of the following: salinity, pressure, and 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 a measured value of the second ocean parameter; wherein the compensation model is obtained based on a calibration relationship between the measured experimental value of the temperature and the measured experimental value of the optical fiber 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 is a polynomial expression containing multiple variables that can describe complex nonlinear relationships. By introducing cross terms and higher-order terms, the multi-parameter coupling effect can be accurately modeled. Cross-sensitivity can then be eliminated through inversion calculations, thereby improving the measurement accuracy of ocean parameters.

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

[0040] The compensation model can be expressed as a second-order multivariate polynomial as shown in Formula (1), based on the initial temperature value , the initial value of the second ocean parameter Compensation is performed to obtain the measured value of the second ocean parameter .

[0041] (1);

[0042] in, 、 、 、 、 、 is a calibration coefficient obtained based on the calibration relationship between the temperature measurement experiment value and the measurement experiment of the optical fiber 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 the compensation model formula (1).

[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] The first compensation relationship is applicable to optical fiber sensors with linear measurements. When the temperature and the sensitivity of the second ocean parameter are in a linear relationship, the fourth term in formula (1) can be discarded. and the fifth The second compensation relationship is applicable to optical fiber sensors with linear measurements. When the temperature and the sensitivity of the second ocean parameter have a nonlinear relationship, the fifth term in formula (1) can be discarded. The third compensation relationship is applicable to fiber optic sensors for nonlinear measurements.

[0050] In one embodiment, the second ocean parameter can be pressure. In a Fabry-Perot cavity-based pressure fiber sensor, the materials comprising the FP cavity (e.g., the fiber end face, substrate, adhesive, diaphragm, etc.) undergo thermal expansion and contraction, changing the physical length of the FP cavity. The refractive index of the transmission medium within the FP cavity (e.g., air, certain gases, certain liquids, etc.) may also change with temperature.

[0051] For pressure fiber optic sensors, the usual design goal is to have a good linear relationship between pressure and deformation. When the temperature and pressure sensitivity of the fiber optic pressure sensor are linearly related, the first compensation relationship can be selected; when the temperature and pressure sensitivity of the fiber optic pressure sensor are nonlinear, the second compensation relationship can be selected, which may have higher compensation accuracy. According to the first compensation relationship or the second compensation relationship, the initial value based on the temperature , the initial value of pressure Compensate and get the measured value of pressure .

[0052] In one embodiment, the second ocean parameter can be salinity. Fiber-optic salinity sensors based on tapered optical fibers primarily rely on the unique structure of the optical fiber and the propagation properties of light. The sensing principles of tapered optical fibers (such as evanescent waves and mode interference) rely on the refractive index difference between the fiber core and the external environment (water), making them sensitive to changes in the refractive index of water. The refractive index of water varies with temperature and salinity. Generally, increasing temperature causes the refractive index of water to decrease, while increasing salinity causes it to increase. Therefore, temperature changes can mask the effects of salinity changes.

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

[0054] For salinity fiber optic sensors and pH fiber optic sensors, the measurement is usually based on nonlinear relationships, and it is suitable to select the third compensation relationship. According to the third compensation relationship, the initial value based on the temperature , for the initial value of salinity Compensate with the initial pH value to obtain the measured value of salinity and pH measurements.

[0055] According to an embodiment of the present invention, the second ocean parameter may be dissolved oxygen (DO). The dissolved oxygen parameter includes a zero oxygen signal , quenching constant and the saturated solubility of oxygen in water The saturated solubility of oxygen in water Can be used to measure dissolved oxygen concentration Perform unit conversion. Dissolved oxygen concentration That is, the output parameter of the dissolved oxygen fiber optic sensor.

[0056] In one embodiment, a fluorescence quenching-based dissolved oxygen fiber sensor measures dissolved oxygen concentration in water by detecting a phenomenon called fluorescence quenching. The probe of the dissolved oxygen fiber sensor is coated with a fluorescent dye that emits fluorescence when excited by light of a specific wavelength. When the fluorescent dye comes into contact with dissolved oxygen molecules, the fluorescence intensity decreases, a phenomenon known as fluorescence quenching.

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

[0058] (4);

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

[0060] Temperature affects dissolved oxygen parameters: In fiber-optic dissolved oxygen sensors based on fluorescence quenching, the fluorescence lifetime and intensity of the fluorescent material are susceptible to temperature. As temperature increases, nonradiative transitions increase, and the fluorescence lifetime and intensity generally decrease. The collision efficiency between oxygen and the fluorescent material is also affected by temperature. Generally, increasing temperature accelerates molecular motion, increasing collision efficiency, but sometimes factors such as solubility can also influence this. The combined effect of these two effects results in different fluorescence lifetimes and intensities at the same oxygen concentration, measured at different temperatures.

[0061] The effect of pressure on dissolved oxygen parameters: On the one hand, hydrostatic pressure increases the solubility of gases (a pressure effect that follows Henry's law). The greater the depth, the higher the pressure, and the higher the concentration of oxygen that can be dissolved in the water at the same saturation. When converting sensor readings to concentration units, the effect of pressure on saturation concentration must be considered. On the other hand, hydrostatic pressure may compress the polymer matrix of the sensing membrane of the dissolved oxygen fiber optic sensor, changing its free volume and structure, which may change the diffusion coefficient of oxygen within the membrane and directly affect the quenching constant. , causing the dissolved oxygen fiber optic sensor to give different readings at the same oxygen partial pressure, and the magnitude of the effect depends on the mechanical properties of the membrane material and the pressure range.

[0062] Salinity affects dissolved oxygen parameters: Increased salinity reduces the physical solubility of oxygen in water (the salting-out effect). At the same temperature, pressure, and air saturation, the dissolved oxygen concentration (e.g., mg / L or μmol / L) in saltwater is lower than in freshwater. Salinity compensation is required to convert the sensor's raw signal into commonly used concentration units (e.g., mg / L or μmol / L).

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

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

[0065] (5);

[0066] in, 、 、 It is a calibration coefficient based on 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.

[0067] According to an embodiment of the present invention, the processor is used to determine a corrected 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 based on a calibration relationship between the measured experimental value of the temperature, the measured experimental value of the pressure and the measured experimental value of the quenching constant of the dissolved oxygen fiber optic sensor.

[0068] Quenching constant It can reflect the relative change of fluorescence intensity under aerobic and anaerobic conditions, and the quenching constant It mainly depends on the diffusion coefficient of oxygen in the sensing membrane 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 two-variable second-order polynomial:

[0070] (6);

[0071] in, 、 、 、 、 、 It is a calibration coefficient based on the calibration relationship between the measured experimental values of temperature, pressure and the measured experimental value of the quenching constant of the dissolved oxygen optical fiber sensor.

[0072] According to an embodiment of the present invention, the processor is used to determine a correction value of the saturated solubility of oxygen in water based on a third correction model, based on the initial value of temperature, the measured value of salinity, and the measured value of pressure; wherein the third correction model is obtained based on a 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.

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

[0074] (7);

[0075] in, 、 、 、 、 、 、 、 、 It is a calibration coefficient based on the calibration relationship between the experimental measurement values of temperature, salinity, and pressure and the experimental measurement value of the saturated solubility of oxygen in water of the dissolved oxygen fiber optic sensor.

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

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

[0078] like Figure 2 As 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 configured to generate a monochromatic light source. The first optical fiber splitter 105 is configured to split the monochromatic light source into beams, which are then incident on multiple intensity-modulated optical fiber sensors 101. The light intensity photoelectric detection assembly 106 includes multiple first interfaces, each of which is connected to the multiple intensity-modulated optical fiber sensors 101. The light intensity photoelectric detection assembly 106 is configured to convert the light signals reflected from the multiple intensity-modulated optical fiber sensors 101 into multiple light intensity signals, and transmit the multiple light intensity signals to the processor 103.

[0080] like Figure 2 As shown, in one embodiment, the first light source 104 and the first fiber optic splitter 105 can be connected via optical fibers. The first fiber optic splitter 105 and the n intensity-modulated fiber optic sensors 101 can be connected via n Y-shaped optical fibers. The light intensity photoelectric detection assembly 106 includes n first interfaces, which can be FC (Ferrule Connector) interfaces, respectively connected to the other ends of the n Y-shaped optical fibers. The light intensity photoelectric detection assembly 106 also includes n light intensity photodetectors, wherein light intensity photodetector I is connected to intensity-modulated fiber optic sensor I via Y-shaped optical fibers; light intensity photodetector II is connected to intensity-modulated fiber optic sensor II via Y-shaped optical fibers; and light intensity photodetector III is connected to intensity-modulated fiber optic sensor III via Y-shaped optical fibers, forming n independent measurement channels.

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

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

[0083] According to an embodiment of the present invention, second light source 107 is used to generate a broadband light source. Second optical fiber splitter 108 is used to split the broadband light source and transmit the split light to multiple wavelength-modulated optical fiber sensors 102. A splitting optical path demodulation component 109 includes multiple second interfaces, each of which is connected to a plurality of wavelength-modulated optical fiber sensors 102. The multiple second interfaces are used to demodulate the optical signals reflected from the multiple wavelength-modulated optical fiber sensors 102 to obtain multiple spectral signals. A linear array photodetector 110 is connected to splitting optical path demodulation component 109 and is used to receive the multiple spectral signals and transmit them to processor 103.

[0084] like Figure 3As shown, in one embodiment, the second light source 107 and the second fiber optic splitter 108 can be connected via optical fibers. The second fiber optic splitter 108 and the m wavelength-modulated fiber optic sensors 102 can be connected via m Y-type optical fibers. The optical splitter demodulation assembly 109 includes m second interfaces, which can be FC interfaces, respectively connected to the other ends of the m Y-type optical fibers. The optical splitter demodulation assembly 109 also includes m optical splitter demodulators, wherein optical splitter demodulator I is connected to wavelength-modulated fiber optic sensor I via Y-type optical fibers; optical splitter demodulator II is connected to wavelength-modulated fiber optic sensor II via Y-type optical fibers; and optical splitter demodulator III is connected to wavelength-modulated fiber optic sensor III via Y-type optical fibers, forming m independent measurement channels.

[0085] According to an embodiment of the present invention, processor 103 is configured to demodulate the plurality of light intensity signals according to a light intensity demodulation program pre-programmed into the processor to obtain initial values of ocean parameters corresponding to the plurality of light intensity signals. Furthermore, processor 103 is configured to demodulate the plurality of spectral signals according to a spectral demodulation program pre-programmed into the processor to obtain initial values of ocean parameters corresponding to the plurality of spectral signals.

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

[0087] like Figure 4 As 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 different compensation strategies for the second ocean parameters, so that the processor 103 compensates the initial value of the second ocean parameter in response to the compensation strategy.

[0089] According to an embodiment of the present invention, processor 103 is pre-programmed with compensation algorithms designed based on the principles and characteristics of each sensor, including compensation models, a first correction model, a second correction model, and a third correction model. Touch interaction device 111 can select a corresponding compensation strategy based on the compensation requirements of the fiber-optic sensors connected to the fiber-optic ocean multi-parameter measurement device through the interactive interface.

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

[0091] like Figure 5As shown, in one embodiment, intensity-modulated fiber optic sensors 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 evanescent waves. Wavelength-modulated fiber optic sensors may include: a fiber Bragg grating fiber temperature sensor, and a composite FP-type fiber optic pressure sensor. Three intensity-modulated fiber optic sensors and two wavelength-modulated fiber optic sensors are placed in a marine environment.

[0092] like Figure 5 As shown, in one embodiment, the first light source can be a 405nm laser light source, which can be a fiber-coupled laser light source. The first fiber optic splitter can be a 1x3 fiber optic splitter. The three intensity-modulated fiber optic sensors can 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). The 405nm laser light source is received by three Y-shaped optical fibers. The other ends of the three Y-shaped optical fibers are then connected to the three FC interfaces of the light intensity photoelectric detection assembly, and the reflected light signals are input to photodetector I, photodetector II, and photodetector III, respectively. Photodetector I, photodetector II, and photodetector III can be silicon photodetectors with built-in amplification, with a wavelength range of 200nm-1100nm and an output voltage range of 0V-10V in high-impedance output mode.

[0093] like Figure 5 As shown, in one embodiment, the second light source can be an SLD (Superluminescent Diode) broadband light source, which can be a near-infrared broadband light source with a central wavelength of 1550 nm and a wavelength range of 1500 nm to 1600 nm. The second optical fiber splitter can be a 1x2 optical fiber splitter, and the two wavelength-modulated optical fiber sensors can include optical fiber sensor IV (a composite FP-type optical fiber pressure sensor) and optical fiber sensor V (a fiber Bragg grating optical fiber temperature sensor). They respectively receive the near-infrared broadband light source with a central wavelength of 1550 nm via two Y-type optical fibers and then reflect the optical signals to splitter optical path demodulator I and splitter optical path demodulator II, respectively.

[0094] like Figure 5As shown, in one embodiment, the processor can be a single-chip microcomputer. The light intensity photoelectric detection component is connected to multiple channels of the analog-to-digital converter of the single-chip microcomputer peripheral resources, and adopts a multi-channel continuous conversion mode based on the direct memory access transmission mode to perform analog-to-digital conversion on the analog voltage signals of the three light intensity signals. The linear array photodetector is connected to the serial port resources of the single-chip microcomputer, and transmits the analog voltage signals of the two spectral signals to the single-chip microcomputer through serial port communication, and performs analog-to-digital conversion on the analog voltage signals of the two spectral signals. The single-chip microcomputer demodulates the digital signals of the three light intensity signals according to the light intensity demodulation program pre-burned in the single-chip microcomputer, and obtains the initial value of the ocean parameter salinity, the initial value of the pH value, and the initial value of the dissolved oxygen. The single-chip microcomputer demodulates the digital signals of the two spectral signals according to the spectral demodulation program pre-burned in the single-chip microcomputer, and obtains the initial value of the ocean parameter temperature and the initial value of the pressure.

[0095] like Figure 5 As shown, in one embodiment, the touch interaction device includes a Bluetooth connector for wirelessly connecting to external devices, increasing the flexibility of data detection. The touch interaction device also includes a touch screen for wired display and touch functions. The touch screen can be a serial port screen with a capacitive touch module, which is burned with the demodulation algorithm and interactive interface program required for data display. The touch interaction device can monitor the sensor operating status and data analysis results in real time.

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

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

[0098] In one embodiment, the intensity-modulated fiber optic sensor may also include a fluorescence quenching-based fiber optic dissolved oxygen sensor and an indicator-based fiber optic pH sensor. The wavelength-modulated fiber optic sensor may also include a composite FP-type fiber optic pressure sensor and a composite FP-type fiber optic temperature and salinity sensor. Two intensity-modulated fiber optic sensors and two wavelength-modulated fiber optic sensors are placed in a marine environment. Processor 103 pre-programs the corresponding demodulation algorithms and compensation models based on the corresponding fiber optic sensors to perform real-time measurements of seawater temperature, pressure, salinity, pH, and dissolved oxygen.

[0099] The fiber-optic ocean multi-parameter measurement device according to the embodiment of the present invention adopts an integrated and modular design, and is lightweight, compact, and has low power consumption and cost. The fiber-optic ocean multi-parameter measurement device according to the embodiment of the present invention is equipped with a user-friendly software interface that can display a variety of ocean parameter measurement data in real time, achieving data visualization, facilitating real-time detection and understanding of ocean environmental conditions, simplifying the operating process, and shortening measurement time. The fiber-optic ocean multi-parameter measurement device according to the embodiment of the present invention provides both wired and wireless data transmission modes, increasing the flexibility of data detection. The fiber-optic ocean multi-parameter measurement device according to the embodiment of the present invention can also be extended to real-time measurement and demodulation applications of other fiber-optic ocean sensors.

[0100] The present invention also provides a measurement method using an optical fiber ocean multi-parameter measurement device, the measurement method comprising: utilizing multiple intensity-modulated optical fiber sensors, based on a monochromatic light source, to respectively collect multiple light intensity signals sensed for multiple ocean parameters; utilizing multiple wavelength-modulated optical fiber sensors, based on a broadband light source, to respectively collect multiple spectral signals sensed for multiple ocean parameters; utilizing a real-time demodulation algorithm, respectively demodulating the multiple light intensity signals and the multiple spectral signals, to obtain initial values of the ocean parameters corresponding to the multiple light intensity signals and the multiple spectral signals, respectively, and compensating for 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 comprises temperature; and the second ocean parameter comprises one of the following: salinity, pressure, pH value, and dissolved oxygen.

[0101] It will be understood by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention may be combined and / or coupled in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or couplings fall within the scope of the present invention.

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

Claims

1. An optical fiber ocean multi-parameter measurement device, characterized in that: The optical fiber ocean multi-parameter measurement device comprises: Multiple intensity-modulated optical fiber sensors are used to respectively collect multiple light intensity signals sensed by multiple ocean parameters based on a monochromatic light source; Multiple wavelength-modulated optical fiber sensors are used to collect multiple spectral signals sensed by multiple ocean parameters based on a broadband light source; A processor is configured to demodulate the plurality of light intensity signals and the plurality of spectral signals respectively using a real-time demodulation algorithm to obtain initial values of ocean 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 ocean parameter, compensate the initial value of a second ocean parameter associated with 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; Wherein, the parameter of dissolved oxygen includes a quenching constant; when the second ocean parameter includes dissolved oxygen, the processor is used to determine the corrected 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 based on 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 optical fiber sensor.

2. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that: In the case where the second ocean parameter comprises 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 the temperature according to the compensation model to obtain the measured value of the second ocean parameter; wherein the compensation model is obtained based on the calibration relationship between the measured experimental value of the temperature and the measured experimental value of the optical fiber 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 dissolved oxygen parameter also 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 dissolved oxygen parameter also 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 corrected value of the saturated solubility of oxygen in water based on a third correction model, an initial value of temperature, a measured value of salinity, and a measured value of pressure; wherein the third correction model is obtained based on a 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.

5. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that: The optical fiber ocean multi-parameter measurement device also includes: a first light source, configured to generate the monochromatic light source; a first optical fiber splitter, configured to split the monochromatic light source and respectively inject the light into the plurality of intensity modulated optical fiber sensors; The light intensity photoelectric detection component includes multiple first interfaces, which are correspondingly connected to the multiple intensity modulated optical fiber sensors, and are used to convert the light signals reflected back by the multiple intensity modulated optical fiber sensors into the multiple light intensity signals, and transmit the multiple light intensity signals to the processor.

6. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that: The optical fiber ocean multi-parameter measurement device also includes: a second light source, configured to generate the broadband light source; a second optical fiber splitter, configured to split the broadband light source and respectively inject the beams into the multiple wavelength-modulated optical fiber sensors; The optical splitting path demodulation component includes a plurality of second interfaces, the plurality of second interfaces correspondingly connected to the plurality of wavelength modulated optical fiber sensors, and used for demodulating the optical signals reflected back by the plurality of wavelength modulated optical fiber sensors to obtain the plurality of spectral signals; A linear array photoelectric detector is connected to the light splitting optical path demodulation component, and is used to receive the multiple spectral signals and transmit the multiple spectral signals to the processor.

7. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that: The processor is used to demodulate multiple light intensity signals according to a light intensity demodulation program pre-burned in the processor to obtain initial values of ocean parameters corresponding to the multiple light intensity signals; and to demodulate multiple spectral signals according to a spectral demodulation program pre-burned in the processor to obtain initial values of ocean parameters corresponding to the multiple spectral signals.

8. The optical fiber ocean multi-parameter measurement device according to claim 1, characterized in that: The optical fiber ocean multi-parameter measurement device also includes: The touch interaction device is used to display the initial values and measured values of the multiple ocean parameters, as well as different compensation strategies for the second ocean parameter, so that the processor compensates the initial value of the second ocean parameter in response to the compensation strategy.

9. A measurement method using the optical fiber ocean multi-parameter measurement device according to any one of claims 1 to 8, characterized in that: The measuring method comprises: Using multiple intensity-modulated optical fiber sensors, based on a monochromatic light source, multiple light intensity signals sensed by multiple ocean parameters are collected respectively; Using multiple wavelength-modulated optical fiber sensors, based on a broadband light source, to collect multiple spectral signals sensed by multiple ocean parameters; Using a real-time demodulation algorithm, the multiple light intensity signals and the multiple spectral signals are demodulated respectively to obtain initial values of ocean parameters corresponding to the multiple light intensity signals and the multiple spectral signals, respectively, and based on the initial value of the first ocean parameter, the initial value of a second ocean parameter associated with the first ocean parameter is compensated to obtain a measured value of the second ocean parameter; wherein the first ocean parameter includes temperature; and the second ocean parameter includes one of the following: salinity, pressure, pH value and dissolved oxygen.

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