A nutrient salt sensor structure based on spectroscopy and its control method

Abstract

The present invention discloses a nutrient salt sensor structure based on spectroscopy and a control method thereof, comprising: a light source, an optical path component and a detection component arranged in sequence; the optical path component comprises: a first lens and a second lens arranged at both ends, and a spectroscope, a first optical window and a second optical window arranged in sequence between the first lens and the second lens; the first lens is arranged close to the output end of the light source, and the second lens is arranged close to the receiving end of the detection component; a photodiode is arranged on the upper part of the spectroscope. The present invention realizes stable control and calibration of the light source through the special design of the optical path component, improves the measurement accuracy of the sensor, and is assisted by a control system, by collecting spectral data and ambient light data, and performing calculations and processing, eliminates the influence of ambient light on the measurement results, improves the anti-interference ability of the sensor, and achieves accurate acquisition of instrument spectral data relative to the prior art, so that the obtained water quality parameters are more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater environmental parameter monitoring, specifically to a technology for testing or analyzing materials by means of measuring the chemical or physical properties of the materials, and more particularly to a nutrient salt sensor structure based on spectroscopy and a control method thereof. Background Art

[0002] Nutrient sensor is a device used to detect the nutrient content in water. It plays a vital role in marine ecological research, water quality monitoring and environmental management. In the prior art, nitrate sensors based on ultraviolet spectroscopy are mainly based on the interaction between ultraviolet light and nitrate molecules in water. This type of sensor uses ultraviolet spectroscopy technology to measure the nitrate concentration in water. The specific principle is as follows:

[0003] Ultraviolet absorption characteristics: Nitrate molecules (especially NO3- ions) have specific absorption characteristics in the ultraviolet region (about 200-400 nanometers). When ultraviolet light passes through water containing nitrates, nitrate molecules absorb light of specific wavelengths, resulting in a decrease in light intensity.

[0004] Spectral measurement: The sensor emits ultraviolet light of a specific wavelength and measures the light intensity after it passes through the water. By analyzing the absorption spectrum, the concentration of nitrate can be calculated.

[0005] However, the above prior art has the following problems:

[0006] 1. During the use of the sensor, the light source energy may decrease or the sensor output data may be incorrect due to improper operation.

[0007] 2. The ambient light in the operating environment may change due to day and night changes or other reasons, affecting the sensor measurement results.

[0008] 3. During long-term use, the spectrometer in the sensor may have inaccurate spectral data output.

[0009] Therefore, it is necessary to provide a nutrient salt sensor structure based on spectroscopy and a control method thereof to solve the above technical problems. Summary of the invention

[0010] The present invention overcomes the deficiencies of the prior art and provides a nutrient salt sensor structure based on spectroscopy and a control method thereof.

[0011] To achieve the above object, the technical solution adopted by the present invention is: a nutrient salt sensor structure based on spectroscopy, comprising: a light source, an optical path component, a detection component and a control system arranged in sequence;

[0012] The optical path component comprises: a first lens and a second lens arranged at two ends, and a beam splitter, a first optical window and a second optical window arranged in sequence between the first lens and the second lens; the first lens is arranged close to the output end of the light source, and the second lens is arranged close to the receiving end of the detection component;

[0013] A photodiode is arranged on the upper part of the beam splitter; the beam splitter is arranged at an angle to divide the passing light beam into two parts, one part changes its angle and is incident on the photodiode, and the other part continues to propagate along the original light path direction;

[0014] The detection assembly includes: a spectrometer, and an incident optical fiber arranged at a receiving end of the spectrometer;

[0015] The control system includes: a spectral data acquisition module, a light source trigger module, an ambient light acquisition module, a light intensity calibration module and a data processing module; the spectral data acquisition module is responsible for controlling the spectrometer to start and end the acquisition of spectral data; the light source trigger module is used to control the flashing time and frequency of the light source; the ambient light acquisition module is used to collect spectral data when there is no light source; the light intensity calibration module performs light source brightness calibration based on the energy value returned by the photodiode; the data processing module is used to receive data from the spectral data acquisition module and the ambient light acquisition module, and calculate the spectral data without environmental noise after the light source passes through the water sample, and summarize it to obtain a spectral data group.

[0016] In a preferred embodiment of the present invention, the light source is a xenon lamp that flashes and emits light.

[0017] In a preferred embodiment of the present invention, the first optical window and the second optical window have the same specifications and are arranged in parallel.

[0018] In a preferred embodiment of the present invention, the light source, the first lens, the beam splitter, the first optical window, the second optical window, the second lens, the incident optical fiber and the spectrometer are arranged coaxially.

[0019] In a preferred embodiment of the present invention, the first lens and the second lens have the same specifications, the first lens collimates the light from the light source and converts it into parallel light, and the second lens focuses the parallel light passing through the second optical window.

[0020] A control method for a nutrient salt sensor structure based on spectroscopy according to any one of the above items comprises the following steps:

[0021] A1. The spectrometer starts collecting spectral data;

[0022] A2, trigger the xenon lamp to flash, so that the spectrometer can collect the spectrum data of the xenon lamp after it passes through the water sample, and the photodiode can collect the intensity of the flashing xenon light after it is split by the spectroscope. The spectrum distribution data obtained by the spectrometer is recorded as S1;

[0023] A3, the spectrometer starts to collect data on ambient light, and the spectrum data obtained by the spectrometer is recorded as S2;

[0024] A4. Calculate the spectrum data Sd1=S1-S2 after the xenon lamp passes through the water sample without environmental noise;

[0025] A5. After several cycles of collection and calibration of the light intensity value of the photodiode, a spectrum data set obtained by multiple measurements is obtained, and the spectrum data set is recorded as G (G = {Sd1, Sd2, Sd3 ... Sdn});

[0026] A6. After selecting the spectral data, select the spectral data Sdm and calculate the water quality parameters through the algorithm.

[0027] In a preferred embodiment of the present invention, in A2, when the turbidity of the water sample is low, the xenon lamp flashes once, and when the turbidity of the water sample is high, the xenon lamp flashes repeatedly several times.

[0028] In a preferred embodiment of the present invention, a sampling test is first performed to distinguish and detect the turbidity level of the water sample. The turbidity level is divided according to: The turbidity is higher.

[0029] In a preferred embodiment of the present invention, during the acquisition process, the total time for the spectrometer to integrate the ambient light is equal to the total integration time for the spectrometer to integrate the xenon lamp flashing process.

[0030] In a preferred embodiment of the present invention, in said S6, the method for calculating the water quality parameters is to select three wavelength data in the spectrum data Sdm as characteristic spectrum: x, y, z;

[0031] Calculation of turbidity value of water sample: where k 1 is the slope of the linear relationship between the turbidity value and the absorbance at x, lg is the logarithm, Nx is the light intensity at x in Sdm measured in the in situ environment, Nx 1 is the light intensity of x in the Sdm of pure water measured in the laboratory;

[0032] Calculation of COD of water samples: where k 2 is the slope of the linear relationship between COD and the absorbance at y, lg is the logarithm, Ny is the light intensity at y in Sdm measured in the in situ environment, Ny 1 is the light intensity of y in Sdm of pure water measured in the laboratory;

[0033] Calculation of nitrate concentration in water samples: where k 3 NO 3 The slope value of the linear relationship between the absorbance at z and lg is the logarithm, Nz is the light intensity at z in Sdm measured in the in situ environment, Nz 1 is the light intensity of z in the Sdm of pure water measured in the laboratory.

[0034] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0035] (1) The present invention provides a nutrient salt sensor structure based on spectroscopy. Through the special design of the optical path component, the stable control and calibration of the light source are achieved, thereby improving the measurement accuracy of the sensor. With the assistance of a control system, the influence of ambient light on the measurement results is eliminated by collecting spectral data and ambient light data, and performing calculations and processing, thereby improving the anti-interference ability of the sensor. Compared with the prior art, the accurate acquisition of instrument spectral data is achieved, making the obtained water quality parameters more accurate.

[0036] (2) The present invention provides a nutrient salt sensor structure based on spectroscopy, in which a spectroscope and a photodiode are added behind the light source and the first lens to monitor the brightness signal of the xenon lamp, and to solve the problem of inaccurate measurement results caused by changes in the brightness of the xenon lamp. At the same time, with the help of the energy value returned by the photodiode, the brightness of the xenon lamp light source is calibrated and applied to the calculation of water quality parameters. This solves the problem of energy decline that may occur in the sensor light source during long-term use, as well as the problem of sensor output data error caused by improper use of the instrument.

[0037] (3) The present invention provides a control method for a nutrient salt sensor structure based on spectroscopy. The spectrometer continuously collects spectral data and intermittently triggers the xenon lamp to flash, respectively collecting spectral data and ambient light data, and calculating the difference between the spectral data and the ambient light data to obtain spectral data without ambient noise after the xenon lamp passes through a water sample. Compared with the prior art, the present invention solves the problem of ambient light changes caused by day and night changes or other reasons in the use environment, eliminates the influence of ambient light on the measurement results, and improves the anti-interference ability of the sensor.

[0038] (4) The present invention provides a control method for a nutrient salt sensor structure based on spectroscopy. In the case where the turbidity of a water sample is high, a xenon lamp is set to flash repeatedly several times in each integration period. Compared with the prior art, the present invention integrates the xenon lamp several times to ensure that even in an environment with high turbidity, the spectrometer can still receive sufficiently strong spectral data. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 It is a schematic structural diagram of a nutrient salt sensor based on spectroscopy according to a preferred embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of a control method of a nutrient salt sensor structure based on spectroscopy according to a preferred embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of collection control of a spectrometer and a xenon lamp when the turbidity of a water sample is low in a preferred embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of collection control of a spectrometer and a xenon lamp when the turbidity of a water sample is high in a preferred embodiment of the present invention.

[0044] In the figure: 100, light source; 200, optical path component; 210, first lens; 220, second lens; 230, spectrometer; 240, first optical window; 250, second optical window; 260, photodiode; 300, detection component; 310, spectrometer; 320, incident optical fiber. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0048] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0049] like Figure 1 As shown, the present invention provides a nutrient salt sensor structure based on spectroscopy, including: a light source 100, an optical path component 200, a detection component 300 and a control system arranged in sequence; the optical path component 200 includes: a first lens 210 and a second lens 220 arranged at both ends, and a beam splitter 230, a first optical window 240 and a second optical window 250 arranged in sequence between the first lens 210 and the second lens 220; the first lens 210 is arranged close to the output end of the light source 100, and the second lens 220 is arranged close to the receiving end of the detection component 300; a photodiode 260 is arranged on the upper part of the beam splitter 230; the beam splitter 230 is arranged at an angle to divide the passing light beam into two parts, one part changes its angle and is incident on the photodiode 260, and the other part continues to propagate along the original light path direction; the detection component 300 includes: a spectrometer 310, and an incident optical fiber 320 arranged at the receiving end of the spectrometer 310.

[0050] In this embodiment, the first lens 210 and the second lens 220 have the same specifications. The first lens 210 collimates the light from the light source 100 and converts it into parallel light, and the second lens 220 focuses the parallel light passing through the second optical window 250 .

[0051] The light source 100 in this embodiment is a xenon lamp that flashes and emits light; the flashing time of the xenon lamp is controlled by controlling the pulse signal of the xenon lamp.

[0052] In this embodiment, the inclination angle of the beam splitter 230 is preferably 45°, and the photodiode 260 is disposed directly above the beam splitter 230 .

[0053] In this embodiment, the first optical window 240 and the second optical window 250 have the same specifications and are arranged in parallel. A water sample to be tested is placed between the first optical window 240 and the second optical window 250 .

[0054] The light source 100, the first lens 210, the beam splitter 230, the first optical window 240, the second optical window 250, the second lens 220, the incident optical fiber 320 and the spectrometer 310 in this embodiment are arranged coaxially to achieve straight and stable propagation of light and improve the accuracy of spectrum data acquisition.

[0055] The control system in this embodiment includes: a spectral data acquisition module, a light source trigger module, an ambient light acquisition module, a light intensity calibration module and a data processing module; the spectral data acquisition module is responsible for controlling the spectrometer to start and end the acquisition of spectral data; the light source trigger module is used to control the flashing time and frequency of the light source; the ambient light acquisition module is used to collect spectral data when there is no light source; the light intensity calibration module performs light source brightness calibration based on the energy value returned by the photodiode; the data processing module is used to receive data from the spectral data acquisition module and the ambient light acquisition module, and calculate the spectral data without environmental noise after the light source passes through the water sample, and summarize it to obtain a spectral data group.

[0056] It is worth mentioning that after receiving the signal, the xenon lamp flashes and emits light. The emitted light is collimated by the first lens 210 to generate parallel light. The parallel light passes through the rear end beam splitter 230 to divide the light beam into two parts. One part is incident on the photodiode 260 for monitoring the energy of the light emitted by the xenon lamp, and the other part continues to propagate, passes through the first optical window 240 to illuminate the water body, and the light after passing through the water sample passes through the second optical window 250 to irradiate the data receiving end. In the data receiving end, the light is focused by the second lens 220 and is incident on the incident optical fiber 320 of the spectrometer 310, and is finally received by the spectrometer 310 to obtain spectral data.

[0057] The present invention adds a spectroscope 230 and a photodiode 260 behind the light source 100 and the first lens 210 to monitor the brightness signal of the xenon lamp and solve the problem of inaccurate measurement results caused by changes in the brightness of the xenon lamp. At the same time, with the help of the energy value returned by the photodiode 260, the brightness of the xenon lamp light source 100 is calibrated and applied to the calculation of water quality parameters. This solves the problem of energy decline that may occur in the sensor light source 100 during long-term use, as well as the problem of sensor output data error caused by improper use of the instrument.

[0058] The present invention realizes stable control and calibration of the light source through the special design of the optical path component, thereby improving the measurement accuracy of the sensor, and is assisted by a control system. By collecting spectral data and ambient light data, and performing calculations and processing, the influence of ambient light on the measurement results is eliminated, and the anti-interference ability of the sensor is improved. Compared with the existing technology, the accurate acquisition of instrument spectral data is achieved, making the obtained water quality parameters more accurate.

[0059] like Figure 2 As shown, the present invention also provides a control method for a nutrient salt sensor structure based on spectroscopy, comprising the following steps:

[0060] A1. The spectrometer starts collecting spectral data.

[0061] A2. Trigger the xenon lamp to flash, so that the spectrometer can collect the spectral data of the xenon lamp after it passes through the water sample. At the same time, the photodiode collects the intensity of the flashing xenon light after it is split by the spectroscope. The spectral distribution data obtained by the spectrometer is recorded as S1.

[0062] A3. The spectrometer starts to collect data on ambient light, and the spectral data obtained by the spectrometer is recorded as S2.

[0063] A4. Calculate the spectral data Sd1=S1-S2 without environmental noise after the xenon lamp passes through the water sample.

[0064] A5. After several cycles of collection and calibration with the light intensity value of the photodiode, a spectral data set obtained by multiple measurements is obtained, and the spectral data set is recorded as G (G = {Sd1, Sd2, Sd3...Sdn}).

[0065] A6. After selecting the spectral data, select the spectral data Sdm and calculate the water quality parameters through the algorithm.

[0066] During the acquisition process, the total time for the spectrometer to integrate ambient light is equal to the total time for the spectrometer to integrate the xenon lamp flashing process. This ensures that the detection time of the two spectral data is consistent, and improves the accuracy of the calculation of the spectral data without environmental noise after the xenon lamp passes through the water sample.

[0067] It is worth explaining that the light intensity value is calibrated. For example, the light intensity value measured in the laboratory is 5, and after long-term use, the value becomes 4. The calibration means that the actual light intensity is 5 / 4 times the test light intensity.

[0068] In the present invention, the spectrometer continuously collects spectral data, intermittently triggers the xenon lamp to flash, collects spectral data and ambient light data respectively, calculates the difference between the spectral data and the ambient light data, and obtains spectral data without environmental noise after the xenon lamp passes through the water sample. Compared with the prior art, the problem of ambient light changes caused by the use environment due to day and night changes or other reasons is solved, the influence of ambient light on the measurement results is eliminated, and the anti-interference ability of the sensor is improved.

[0069] In step A2, when the turbidity of the water sample is low, the xenon lamp flashes once, and when the turbidity of the water sample is high, the xenon lamp flashes several times repeatedly; firstly, a sampling test is performed to distinguish the turbidity of the water sample. The turbidity level is divided according to: The turbidity is higher.

[0070] When the turbidity of the measured water sample is low, the acquisition control of the spectrometer and the xenon lamp is as follows: Figure 3 As shown, before the xenon lamp is triggered t2, the spectrometer starts integration t1, and when the xenon lamp finishes flashing t3, the integration of the spectrometer ends t4. Then, the xenon lamp is not operated, and the spectrometer is used alone to integrate the ambient light. The integration start time is t5, and the integration end time is t6, wherein t6-t5=t4-t1. At this point, one data collection sub-cycle is completed.

[0071] The time of t1-t6 is preferably t2-t1<0.1ms, t4-t3<0.1ms, and the flashing time of the xenon lamp under low turbidity is preferably t3-t2=200ms.

[0072] When the turbidity of the measured water sample is high, the acquisition control of the spectrometer and the xenon lamp is as follows: Figure 4 As shown, before the xenon lamp is triggered for the first time t2, the spectrometer starts integration t1, when the xenon lamp finishes the first flash t3, the xenon lamp flashes repeatedly for several times, after the xenon lamp flashes repeatedly, the spectrometer integration ends t4, then, without operating the xenon lamp, the spectrometer integrates the ambient light alone, the integration starts at t5, and ends at t6, where t6-t5=t4-t1, and a data collection sub-cycle is completed. Integrating the xenon lamp several times can ensure that the spectrometer can still receive sufficiently strong spectral data even in an environment with high turbidity.

[0073] Among them, the time t1-t6 is preferably t2-t1<0.1ms, t4-t3<0.1ms, the flashing time of the xenon lamp under high turbidity is preferably t3-t2=(number of flashes×100+100)ms, the interval time between each flash of the xenon lamp under high turbidity is preferably 100ms, and the number of flashes of the xenon lamp under high turbidity is 5 to 10 times per integration period.

[0074] In step A6, the water quality parameter is calculated by selecting three wavelength data in the spectrum data Sdm as characteristic spectra, such as 630nm, 254nm, and 220nm;

[0075] Calculation of turbidity value of water sample: where k 1 is the slope value of the linear relationship between the turbidity value and the absorbance at 630 nm, lg is the logarithm, N630 is the light intensity of 630 in Sdm measured in the in situ environment, and N6300 is the light intensity of 630 in Sdm of pure water measured in the laboratory;

[0076] Calculation of COD of water samples: where k 2 is the slope value of the linear relationship between COD and the absorbance at 254, lg is the logarithm, N254 is the light intensity of 254 in Sdm measured in the in situ environment, and N2540 is the light intensity of 254 in Sdm of pure water measured in the laboratory;

[0077] Calculation of nitrate concentration in water samples: where k 3 NO 3 The slope value of the linear relationship between N220 and the absorbance at 220, lg is the logarithm, N220 is the intensity of 220 in Sdm measured in the in situ environment, and N2200 is the intensity of 220 in Sdm of pure water measured in the laboratory.

[0078] It is worth noting that k in the above calculation formula 1 , k 2 , k 3 And the logarithm lg, those skilled in the art can easily obtain it by looking up the table, and will not be elaborated here. Through the nutrient salt sensor structure based on spectroscopy and the control method thereof of the present invention, after obtaining multiple groups of spectral data, it is relatively easy to calculate accurate water quality parameters.

[0079] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A control method for a nutrient salt sensor structure based on spectroscopy, the nutrient salt sensor structure based on spectroscopy comprising: The light source, light path component, detection component and control system are arranged in sequence, characterized in that: The optical path component comprises: a first lens and a second lens arranged at two ends, and a beam splitter, a first optical window and a second optical window arranged in sequence between the first lens and the second lens; the first lens is arranged close to the output end of the light source, and the second lens is arranged close to the receiving end of the detection component; A photodiode is arranged on the upper part of the beam splitter; the beam splitter is arranged at an angle to divide the passing light beam into two parts, one part changes its angle and is incident on the photodiode, and the other part continues to propagate along the original light path direction; The light source is a xenon lamp that flashes and emits light; The detection assembly includes: a spectrometer and an incident optical fiber arranged at a receiving end of the spectrometer; The control system includes: a spectral data acquisition module, a light source trigger module, an ambient light acquisition module, a light intensity calibration module and a data processing module; the spectral data acquisition module is responsible for controlling the spectrometer to start and end the acquisition of spectral data; the light source trigger module is used to control the flashing time and frequency of the light source; the ambient light acquisition module is used to collect spectral data when there is no light source; the light intensity calibration module performs light source brightness calibration based on the energy value returned by the photodiode; the data processing module is used to receive data from the spectral data acquisition module and the ambient light acquisition module, and calculate the spectral data without environmental noise after the light source passes through the water sample, and summarize to obtain a spectral data group; The control method comprises the following steps: A1. The spectrometer starts collecting spectral data; A2, trigger the xenon lamp to flash, so that the spectrometer can collect the spectrum data of the xenon lamp after it passes through the water sample, and the photodiode can collect the intensity of the flashing xenon light after it is split by the spectroscope. The spectrum distribution data obtained by the spectrometer is recorded as S1; A3, the spectrometer starts to collect data on ambient light, and the spectrum data obtained by the spectrometer is recorded as S2; A4. Calculate the spectral data of the xenon lamp after passing through the water sample without environmental noise ; A5. After several cycles of collection and calibration of the light intensity value of the photodiode, a spectral data set obtained by multiple measurements is obtained. The spectral data set is recorded as ; A6. After selecting the spectral data, the spectral data Sdm is selected and the water quality parameters are calculated by the algorithm; In A2, when the turbidity of the water sample is low, the xenon lamp flashes once, and when the turbidity of the water sample is high, the xenon lamp flashes repeatedly several times, and the spectrometer integrates the xenon lamp several times; First, take a sample and test it to determine the turbidity of the water sample. The turbidity level is determined based on: The turbidity is higher.

2. The control method of a nutrient salt sensor structure based on spectroscopy according to claim 1, characterized in that: The first optical window and the second optical window have the same specifications and are arranged in parallel.

3. The control method of a nutrient salt sensor structure based on spectroscopy according to claim 1, characterized in that: The light source, the first lens, the beam splitter, the first optical window, the second optical window, the second lens, the incident optical fiber and the spectrometer are arranged coaxially.

4. The control method of a nutrient salt sensor structure based on spectroscopy according to claim 1, characterized in that: The first lens and the second lens have the same specifications. The first lens collimates the light from the light source and converts it into parallel light, and the second lens focuses the parallel light passing through the second optical window.

5. The control method of a nutrient salt sensor structure based on spectroscopy according to claim 1, characterized in that: During the acquisition process, the total integration time of the spectrometer for ambient light is equal to the total integration time of the spectrometer for the xenon lamp flashing process.

6. The control method of a nutrient salt sensor structure based on spectroscopy according to claim 1, characterized in that: In A6, the water quality parameter is calculated by selecting three wavelength data in the spectrum data Sdm as characteristic spectrum: x, y, z; Calculation of turbidity value of water sample: ,in is the slope of the linear relationship between the turbidity value and the absorbance at x, is the logarithm, is the light intensity of x in Sdm measured in the in-situ environment, is the light intensity of x in the Sdm of pure water measured in the laboratory; Calculation of COD of water samples: ,in is the slope value of the linear relationship between COD and absorbance at y, is the logarithm, is the light intensity of y in Sdm measured in the in-situ environment, is the light intensity of y in Sdm of pure water measured in the laboratory; Calculation of nitrate concentration in water samples: ,in for The slope value of the linear relationship between and absorbance at z, is the logarithm, is the light intensity of z in Sdm measured in the in situ environment, is the light intensity of z in the Sdm of pure water measured in the laboratory.

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