A multi-parameter synchronous detection device based on open optical and optical path compensation

Abstract

This invention belongs to the field of water quality optical detection technology and discloses a multi-parameter synchronous detection device based on open optics and optical path compensation. The invention includes an open optics detection module, a signal acquisition module, an optical path compensation processing module, an environmental parameter sensing module, and a data storage and transmission module. The open optics detection module is electrically connected to the signal acquisition module, and both the signal acquisition module and the environmental parameter sensing module are electrically connected to the optical path compensation processing module. The optical path compensation processing module is also electrically connected to the data storage and transmission module. This device enables in-situ real-time synchronous detection of multiple parameters in the same water body. Furthermore, through hardware structure design and optical path compensation algorithm adaptation, it completes light source attenuation correction, turbidity scattering separation, transmittance temperature correction, and path attenuation compensation, significantly improving detection accuracy and long-term stability.

Description

Technical Field

[0001] This invention belongs to the field of water quality optical detection technology, specifically relating to a multi-parameter synchronous detection device based on open optics and optical path compensation. Background Technology

[0002] In water environment monitoring, parameters such as algal species and concentration, fluorescent dissolved organic matter (FDOM) content, and turbidity are core indicators reflecting eutrophication and ecological health of water bodies, and are of great significance for water environment quality assessment and early warning of water ecological disasters. Existing water quality bio-optical detection equipment generally suffers from the following defects: 1) Structural sealing defects: Most equipment uses a closed detection chamber, requiring water sample extraction, which disrupts the natural state of water flow. Furthermore, different parameter detection modules are independent of each other, making it impossible to guarantee that the detected object is the same water body, resulting in poor data correlation, insufficient accuracy, and difficulty in reflecting the in-situ characteristics of the water body; 2) Insufficient optical path interference processing: The detection signal contains multiple components such as algal fluorescence, FDOM fluorescence, turbidity scattered light, ambient light, and circuit noise. Existing equipment lacks effective signal separation and compensation mechanisms, leading to significant detection errors in complex water bodies; 3) Uncompensated signal attenuation: 4) Poor light source stability: The aging of LED light sources and the changes in luminescence intensity caused by current fluctuations lack real-time correction, resulting in insufficient long-term detection stability; 5) Unquantified temperature interference: The effect of temperature changes on the transmittance of water has not been quantitatively calculated, and the transmittance measurement error further interferes with the accuracy of signal attenuation compensation; 6) The optical window is easily contaminated: During the detection process, water impurities easily adhere to the optical window, and the existing equipment lacks an effective cleaning mechanism. Long-term use will reduce transmittance and affect the detection results.

[0003] Therefore, there is an urgent need to develop an open-structure device with full-link optical path compensation capabilities that can achieve simultaneous detection of multiple parameters in the same water body, in order to solve the above-mentioned defects of existing equipment and improve the accuracy, real-time performance and long-term stability of water environment detection. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a multi-parameter synchronous detection device based on open optics and optical path compensation. This device enables in-situ real-time synchronous detection of multiple parameters in the same water body. Simultaneously, through hardware structure design and adaptation of optical path compensation algorithms, it completes light source attenuation correction, turbidity scattering separation, transmittance temperature correction, and path attenuation compensation, significantly improving detection accuracy and long-term stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A multi-parameter synchronous detection device based on open optics and optical path compensation includes an open optics detection module, a signal acquisition module, an optical path compensation processing module, an environmental parameter sensing module, and a data storage and transmission module; the open optics detection module is electrically connected to the signal acquisition module, the signal acquisition module and the environmental parameter sensing module are both electrically connected to the optical path compensation processing module, and the optical path compensation processing module is electrically connected to the data storage and transmission module. The open optical detection module is an open structure without a closed detection cavity, which is in direct contact with the water body to be tested, realizing the excitation and acquisition of multi-parameter optical signals of the same water body, and the detection area of ​​all modules is the same water body area. The signal acquisition module is used to acquire optical signals, light source status signals and transmittance detection signals, and transmit the signals to the optical path compensation processing module; The environmental parameter sensing module is used to collect the temperature and water pressure parameters of the water body to be measured, providing environmental parameter basis for optical path compensation. The optical path compensation processing module is used to call the calibration parameters and execute a four-level optical path compensation algorithm of light source correction, turbidity separation, path attenuation compensation, and temperature correction to process the acquired signal and obtain the true values ​​of each parameter. The data storage and transmission module is used to store detection data and processing results, and to realize local storage and remote transmission of data.

[0006] Furthermore, the open optical detection module includes a ring LED excitation light source assembly, a light source attenuation correction unit, an optical window assembly, a transmittance detection light source assembly, and a photoelectric detection unit; the ring LED excitation light source assembly, the light source attenuation correction unit, and the photoelectric detection unit are all coaxially arranged with the optical window assembly, and the transmittance detection light source assembly is fixed outside the optical window assembly, and its central beam is not directly aligned with the axis of the optical window assembly.

[0007] Furthermore, the annular LED excitation light source assembly includes 15 LEDs with different center wavelengths, arranged uniformly in a ring. The center wavelengths of the LEDs are 350nm, 380nm, 400nm, 425nm, 435nm, 445nm, 455nm, 470nm, 505nm, 525nm, 550nm, 560nm, 590nm, 610nm, and 680nm, respectively. The inner diameter of the annular LED excitation light source assembly is 30mm, the outer diameter is 50mm, the spacing between adjacent LEDs is 24°, and each LED is set at a 45° angle to the coaxial center line. All 15 LEDs are modulated LEDs capable of emitting 1kHz modulated light, and they emit light sequentially in ascending order of wavelength, with each LED emitting light for 50ms.

[0008] Furthermore, the light source attenuation correction unit includes 15 photodiodes, each corresponding to one of the 15 LED emitters of the ring LED excitation light source assembly. Each photodiode is located on the back of the corresponding LED emitter and is used to collect the back light intensity of the corresponding LED emitter in real time, obtain the real-time light source status signal, and realize the real-time correction of LED light source attenuation.

[0009] Furthermore, the optical window assembly includes a sapphire glass window, a hydrophobic and oleophobic coating, and an automatic cleaning subunit. The sapphire glass window has a thickness of 2mm and a diameter of 60mm, with a light transmittance of ≥95% in the 300~700nm wavelength range. The hydrophobic and oleophobic coating is deposited on the outer surface of the sapphire glass window, resisting seawater corrosion and reducing the adhesion of water impurities. The automatic cleaning subunit includes a silicone cleaning brush and a micro drive motor. The silicone cleaning brush is attached to the outer surface of the sapphire glass window, and the micro drive motor is connected to the silicone cleaning brush for transmission. A timed wiping program can be set to clean the sapphire glass window and ensure light transmittance.

[0010] Furthermore, the transmittance detection light source component is the 16th LED emitter with a center wavelength of 680nm, capable of emitting 1KHz modulated light; the transmittance detection light source component is fixed to the outside of the optical window component by a stainless steel bracket, with a distance of 220mm from the optical window component, and the length error of the stainless steel bracket is ≤±0.5mm. The offset angle between the center beam of the transmittance detection light source component and the axis of the optical window component is 15°, to prevent the light from the ring LED excitation light source component from being directly reflected into the photoelectric detection unit.

[0011] Furthermore, the photodetector unit is a photomultiplier tube, coaxially arranged with the annular LED excitation light source assembly and the optical window assembly; the front end of the photomultiplier tube is equipped with an OD6-level 680nm filter, the filter has a transmittance of 90%, a half-width of 10nm, a wavelength range of 675~685nm, and an attenuation of ≥10 for non-680nm light. 6 The photomultiplier tube is designed to allow only the characteristic fluorescence of algae at 680nm and a small amount of scattered light to pass through. The photomultiplier tube is model H10722, with a cathode photoelectric sensitivity of 205μA / lm and an operating voltage of ±5V. It is used to convert the collected optical signals into electrical signals and transmit them to the signal acquisition module.

[0012] Furthermore, the signal acquisition module includes a 24-bit ADS1256 analog-to-digital converter chip. The ADS1256 chip has two acquisition channels. The first channel is electrically connected to the photodetector unit and is used to acquire the optical electrical signal and transmittance detection signal output by the photomultiplier tube. The second channel is electrically connected to the light source attenuation correction unit and is used to acquire the light source status signal and dark current signal output by the photodiode. The ADS1256 chip has a sampling rate of 1000 SPS, and the median algorithm is used to extract the raw data during the acquisition process to reduce signal interference.

[0013] Furthermore, the optical path compensation processing module is an STM32F407 microcontroller, which has built-in calibration parameters such as light source reference value, absolute transmittance reference value, temperature conversion coefficient, wavelength correction coefficient, turbidity correction coefficient, and FDOM weighting factor, as well as a four-level optical path compensation algorithm of light source correction, turbidity separation, path attenuation compensation, and temperature correction. The STM32F407 microcontroller is used to receive input signals from the signal acquisition module and the environmental parameter sensing module, call the built-in calibration parameters to execute the optical path compensation algorithm, perform light source attenuation correction, turbidity scattering signal separation, transmittance calculation and temperature correction, and target signal (FDOM, algae) path attenuation compensation on the original signal, and obtain the true values ​​of algae species and concentration, FDOM content, turbidity, and transmittance, and transmit the processing results to the data storage and transmission module.

[0014] Furthermore, the environmental parameter sensing module includes a water temperature sensor and a water pressure sensor, both of which are in direct contact with the water body to be measured. They are used to collect the temperature and water pressure parameters of the water body in real time. The collected parameters are transmitted to the optical path compensation processing module to provide environmental parameter basis for transmittance temperature correction and optical path compensation algorithms.

[0015] Furthermore, the data storage and transmission module includes a 32G Class 10 SD card and a communication interface; the 32G Class 10 SD card is electrically connected to the optical path compensation processing module and is used to locally store the original acquired signals, environmental parameters, calibration parameters, and optical path compensation processing results; the communication interface is an RS485 interface or a serial-to-USB interface, used to remotely transmit the detection data and processing results to an external terminal to realize remote monitoring and analysis of the data.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: 1. The device of the present invention is an open structure without a closed detection chamber, which directly contacts the water body to be tested, does not interfere with the natural state of water flow, and the detection area of ​​all detection modules is the same water body area, ensuring the consistency of the detection objects of parameters such as algae, FDOM, and turbidity, with high data correlation and authenticity, accurately reflecting the in-situ characteristics of the water body, and realizing the synchronous detection of multiple parameters in the same water body.

[0017] 2. This invention adapts the photodiode of the light source attenuation correction unit to the light source attenuation correction step of the optical path compensation algorithm, thereby correcting the light source attenuation caused by LED aging and current fluctuations in real time. By adapting the transmittance detection light source component to the transmittance calculation and temperature correction steps of the optical path compensation algorithm, it quantitatively compensates for the water propagation attenuation of excitation light and fluorescence, reducing detection errors in high-turbidity and high-chromaticity water bodies and improving detection accuracy. Hardware and algorithm adaptation achieves end-to-end optical path compensation. Through the time-division excitation design of the ring LED excitation light source component and the OD6-level filter setting of the photodetector unit, combined with the turbidity scattering signal separation step of the optical path compensation algorithm, it effectively separates algal fluorescence, FDOM fluorescence, and interference signals such as ambient light, circuit noise, and turbidity scattering light, significantly improving the signal-to-noise ratio of the detection signal.

[0018] 3. This invention collects water temperature using a water temperature sensor in an environmental parameter sensing module. Combined with the temperature conversion coefficient and wavelength correction coefficient of the optical path compensation algorithm, a quantitative conversion relationship between temperature and transmittance is established. This effectively reduces the interference of temperature changes on transmittance measurement and signal attenuation compensation, further improving detection accuracy. The ring-shaped LED excitation light source assembly contains 15 LEDs with different center wavelengths, 14 of which are adapted to the fluorescence characteristics of different algae such as green algae, dinoflagellates, cyanobacteria, diatoms, and cryptophytes, providing high-quality raw fluorescence signals for distinguishing algae species and concentrations, enabling accurate detection of various algae.

[0019] 4. The hydrophobic and oleophobic coating of the optical window component of this invention reduces the adhesion of water impurities. Combined with the timed wiping function of the automatic cleaning subunit, it ensures the light transmittance of the optical window, avoids detection errors caused by window contamination, and improves the long-term detection stability of the device. The device has a minimum test cycle of 1 second and can achieve in-situ real-time detection and output of multiple parameters such as algae, FDOM, turbidity, light transmittance, water temperature, and water pressure. It can accurately capture parameter changes in dynamic water environments and is suitable for various dynamic water environment monitoring scenarios such as rivers, lakes, and oceans. Furthermore, it achieves local storage of massive amounts of data via a 32G SD card and remote data transmission via RS485 and serial-to-USB interfaces, balancing local data retention and remote monitoring and analysis, and adapting to diverse water environment monitoring needs such as laboratory analysis, on-site monitoring, and remote early warning. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of each module of the present invention; Figure 2 This is a schematic diagram of the structure of the open optical detection module of the present invention; Figure 3 This is a top-view three-dimensional structural diagram of the present invention; Figure 4This is a bottom-view three-dimensional structural diagram of the present invention; Figure 5 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 6 This is a schematic diagram of the cross-sectional structure of the lower half of the present invention; Figure 7 This is a schematic diagram of the principle structure of the present invention.

[0021] The reference numerals in the figure are as follows: 1. Open-type optical detection module; 11. Ring LED excitation light source assembly; 111. LED emitter; 12. Light source attenuation correction unit; 121. Photodiode; 13. Optical window assembly; 131. Sapphire glass window; 132. Hydrophobic and oleophobic coating; 133. Automatic cleaning subunit; 1331. Silicone cleaning brush; 1332. Miniature drive motor; 14. Transmittance detection light source assembly; 141. 16th LED emitter; 142. Stainless steel bracket; 15. Photodetector unit; 151. Photomultiplier tube; 152. Filter; 2. Signal acquisition module; 21. ADS1256 analog-to-digital converter chip; 3. Optical path compensation processing module; 31. STM32F407 microcontroller; 4. Environmental parameter sensing module; 41. Water temperature sensor; 42. Water pressure sensor; 5. Data storage and transmission module; 51. 32G Class 10 SD card; 52. Communication interface. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] like Figures 1 to 7 As shown, a multi-parameter synchronous detection device based on open optics and optical path compensation includes an open optics detection module 1, a signal acquisition module 2, an optical path compensation processing module 3, an environmental parameter sensing module 4, and a data storage and transmission module 5. The open optics detection module 1 is electrically connected to the signal acquisition module 2, the signal acquisition module 2 and the environmental parameter sensing module 4 are both electrically connected to the optical path compensation processing module 3, and the optical path compensation processing module 3 is electrically connected to the data storage and transmission module 5.

[0024] In this embodiment, the open optical detection module 1 is an open structure without a closed detection cavity, which is in direct contact with the water body to be tested. It includes a ring LED excitation light source assembly 11, a light source attenuation correction unit 12, an optical window assembly 13, a transmittance detection light source assembly 14, and a photoelectric detection unit 15. The ring LED excitation light source assembly 11, the light source attenuation correction unit 12, and the photoelectric detection unit 15 are all coaxially arranged with the optical window assembly 13. The transmittance detection light source assembly 14 is fixed to the outside of the optical window assembly 13, and its central beam is not directly aligned with the axis of the optical window assembly 13.

[0025] The ring-shaped LED excitation light source assembly 11 includes 15 LEDs 111 with different center wavelengths, arranged uniformly in a ring. The inner diameter is 30 mm, the outer diameter is 50 mm, the spacing between adjacent LEDs 111 is 24°, and each LED 111 forms a 45° angle with the coaxial center line. The center wavelengths of the LEDs 111 are 350 nm, 380 nm, 400 nm, 425 nm, 435 nm, 445 nm, 455 nm, 470 nm, 505 nm, 525 nm, 550 nm, 560 nm, 590 nm, 610 nm, and 680 nm, respectively. All of them are modulated LEDs that can emit 1 kHz modulated light. They emit light in time-division manner according to the wavelength from smallest to largest, and the single light emission time is 50 ms. Among them, 350 nm and 400 nm are used to excite FDOM to produce fluorescence, 680 nm is used to excite turbidity particles to produce scattering signals, and the remaining wavelengths are used to excite different algae to produce 680 nm characteristic fluorescence.

[0026] The light source attenuation correction unit 12 includes 15 photodiodes 121, which correspond one-to-one with 15 LEDs 111. They are set on the back of the LEDs 111 and collect the back light intensity of the corresponding LEDs 111 in real time to obtain the real-time light source status signal, providing hardware support for light source attenuation correction.

[0027] The optical window assembly 13 includes a sapphire glass window 131, a hydrophobic and oleophobic coating 132, and an automatic cleaning subunit 133. The sapphire glass window 131 has a thickness of 2 mm, a diameter of 60 mm, and a light transmittance of ≥95% in the 300~700nm wavelength band. The hydrophobic and oleophobic coating 132 is deposited on the outer side of the sapphire glass window 131 and is resistant to seawater corrosion. The automatic cleaning subunit 133 includes a silicone cleaning brush 1331 and a micro drive motor 1332. The silicone cleaning brush 1331 is attached to the outer side of the sapphire glass window 131, and the micro drive motor 1332 drives the silicone cleaning brush 1331 to perform a rotating wiping motion. It can be set to wipe once per hour, with each wipe lasting 10 seconds, to ensure the light transmittance of the sapphire glass window 131.

[0028] The transmittance detection light source assembly 14 is the 16th LED emitter 141 with a center wavelength of 680nm, emitting 1KHz modulated light; it is fixed to the outside of the sapphire glass window 131 at 220mm by a stainless steel bracket 142, the length error of the stainless steel bracket 142 is ≤±0.5mm, and the center beam of the 16th LED emitter 141 is offset from the axis of the sapphire glass window 131 by 15° to avoid the light from the ring LED excitation light source assembly 11 being directly reflected into the photoelectric detection unit 15.

[0029] The photoelectric detection unit 15 is a photomultiplier tube 151 of model H10722, with a cathode photosensitive sensitivity of 205μA / lm and an operating voltage of ±5V. It is coaxially arranged with the ring LED excitation light source assembly 11 and the optical window assembly 13. An OD6-grade 680nm filter 152 is installed at its front end. This filter has a transmittance of 90%, a half-width of 10nm, a wavelength range of 675~685nm, and an attenuation of ≥10% for non-680nm light. 6 The light is doubled, allowing only 680nm fluorescence from algae and a small amount of scattered light to pass through. The optical signal is converted into an electrical signal and then transmitted to the signal acquisition module 2.

[0030] The signal acquisition module 2 is a 24-bit ADS1256 analog-to-digital converter chip 21 with a sampling rate of 1000 SPS. It has two acquisition channels. The first channel is electrically connected to the photomultiplier tube 151 to acquire optical electrical signals and transmittance detection signals. The second channel is electrically connected to the photodiode 121 to acquire light source status signals and photodiode dark current signals. During the acquisition process, the median algorithm is used to extract the raw data to reduce signal interference. The converted digital signal is transmitted to the optical path compensation processing module 3.

[0031] The optical path compensation processing module 3 is an STM32F407 microcontroller 31, which has built-in calibration parameters such as light source reference value, absolute transmittance reference value, temperature conversion coefficient, wavelength correction coefficient, turbidity correction coefficient, and FDOM weighting factor, as well as a four-level optical path compensation algorithm of light source correction, turbidity separation, path attenuation compensation, and temperature correction. The STM32F407 microcontroller 31 receives the input signals from the signal acquisition module 2 and the environmental parameter sensing module 4, calls the calibration parameters to execute the optical path compensation algorithm, processes the original signal, and obtains the true values ​​of algae species and concentration, FDOM content, turbidity, and transmittance.

[0032] The environmental parameter sensing module 4 includes a water temperature sensor 41 and a water pressure sensor 42, both of which are in direct contact with the water body to be measured. They collect water temperature t and water pressure parameters in real time and transmit them to the STM32F407 microcontroller 31 to provide environmental parameter basis for transmittance temperature correction and optical path compensation algorithms.

[0033] The data storage and transmission module 5 includes a 32G Class 10 SD card 51 and an RS485 communication interface 52. The 32G Class 10 SD card 51 is electrically connected to the STM32F407 microcontroller 31 and stores the original acquired signals, environmental parameters, calibration parameters, and optical path compensation processing results. The RS485 communication interface 52 remotely transmits the detection data and processing results to an external monitoring terminal to realize remote monitoring and analysis of the data. It can also be replaced with a serial port to USB interface as needed.

[0034] The working process of the device of the present invention is as follows: 1. Equipment installation and initialization: Fix the device at the monitoring point of the water body to be tested (e.g., 1m underwater in a lake), so that the open optical detection module 1 is in direct contact with the water body, and the transmittance detection light source component 14 and the optical window component 13 are kept at a distance of 220mm; start the device, the STM32F407 microcontroller 31 loads all built-in calibration parameters, and completes the device initialization; 2. Signal Acquisition Cycle Execution: With a minimum test cycle of 1 second, four stages are executed sequentially: ① 50ms Background Signal Acquisition: All LEDs are off, photomultiplier tube 151 acquires background signal D (ambient light + circuit noise), and the second channel of ADS1256 chip acquires the dark current of photodiodes and simplifies it to 0; ② 750ms Excitation Light Signal Acquisition: 15 LEDs 111 emit light sequentially for 50ms according to wavelength from smallest to largest, the first channel of ADS1256 chip acquires the original signal output by photomultiplier tube 151, and the second channel synchronously acquires the light source status signal of the corresponding photodiode 121; ③ 50ms Transmittance Detection: The 16th LED 141 emits light, and the first channel of ADS1256 chip acquires the original signal of 680nm absolute transmittance; ④ 150ms Environmental Parameter Acquisition and Algorithm Processing: Water temperature sensor 41 and water pressure sensor 42 acquire water temperature and water pressure parameters and transmit them to STM32F407 microcontroller 31; 3. Optical path compensation processing: The STM32F407 microcontroller calls the calibration parameters and executes the four-level optical path compensation algorithm to sequentially complete the light source attenuation correction, turbidity scattering signal separation, transmittance calculation and temperature correction, and path attenuation compensation of FDOM and algal fluorescence signals, so as to obtain the true values ​​of algal species and concentration, FDOM content, turbidity and transmittance. 4. Data storage and transmission: The STM32F407 microcontroller 31 transmits all processed parameters (algae, FDOM, turbidity, light transmittance, water temperature, and water pressure) to a 32G Class 10 SD card 51 for local storage, and at the same time transmits them remotely to an external terminal through the RS485 communication interface 52 to realize real-time data monitoring.

[0035] The device of this invention achieves synchronous detection of multiple parameters in the same water body through an open structure design. By combining the deep adaptation of hardware structure and optical path compensation algorithm, it completes full-link optical path compensation, effectively solving the problems of low detection accuracy, poor stability and insufficient data authenticity of existing equipment. It has high detection accuracy, strong real-time performance and good long-term stability, and is suitable for in-situ real-time monitoring of various water environments such as rivers, lakes and oceans.

[0036] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-parameter synchronous detection device based on open optical and optical path compensation, characterized in that: It includes an open optical detection module (1), a signal acquisition module (2), an optical path compensation processing module (3), an environmental parameter sensing module (4), and a data storage and transmission module (5); the open optical detection module (1) is electrically connected to the signal acquisition module (2), the signal acquisition module (2) and the environmental parameter sensing module (4) are both electrically connected to the optical path compensation processing module (3), and the optical path compensation processing module (3) is electrically connected to the data storage and transmission module (5); The open optical detection module (1) is an open structure without a closed detection cavity, which is in direct contact with the water body to be tested, and the detection area of ​​all modules is the same water body area. The open optical detection module (1) includes a ring LED excitation light source assembly (11), a light source attenuation correction unit (12), an optical window assembly (13), a transmittance detection light source assembly (14), and a photoelectric detection unit (15). The ring LED excitation light source assembly (11), the light source attenuation correction unit (12), and the photoelectric detection unit (15) are all coaxially arranged with the optical window assembly (13). The transmittance detection light source assembly (14) is fixed outside the optical window assembly (13), and its central beam is not directly aligned with the axis of the optical window assembly (13).

2. The multi-parameter synchronous detection device based on open optical and optical path compensation according to claim 1, characterized in that: The annular LED excitation light source assembly (11) includes 15 LEDs (111) with different center wavelengths, arranged in a uniform ring. The center wavelengths of the LEDs (111) are 350nm, 380nm, 400nm, 425nm, 435nm, 445nm, 455nm, 470nm, 505nm, 525nm, 550nm, 560nm, 590nm, 610nm, and 680nm, respectively. The inner diameter of the annular LED excitation light source assembly (11) is 30mm, the outer diameter is 50mm, the spacing between adjacent LEDs (111) is 24°, and each LED (111) is set at a 45° angle to the coaxial center line. All 15 LEDs (111) are modulated LEDs that can emit 1KHz modulated light, and they emit light sequentially in order of increasing wavelength.

3. The multi-parameter synchronous detection device based on open optical and optical path compensation according to claim 2, characterized in that: The light source attenuation correction unit (12) includes 15 photodiodes (121), which correspond one-to-one with the 15 LED emitters (111) of the ring LED excitation light source assembly (11). Each photodiode (121) is located on the back of the corresponding LED emitter (111) and is used to collect the back light intensity of the corresponding LED emitter (111) in real time.

4. The multi-parameter synchronous detection device based on open optical and optical path compensation according to claim 1, characterized in that; The optical window assembly (13) includes a sapphire glass window (131), a hydrophobic and oleophobic coating (132), and an automatic cleaning subunit (133). The sapphire glass window (131) has a thickness of 2 mm, a diameter of 60 mm, and a light transmittance of ≥95% in the 300~700 nm wavelength band. The hydrophobic and oleophobic coating (132) is deposited on the outer surface of the sapphire glass window (131). The automatic cleaning subunit (133) includes a silicone cleaning brush (1331) and a micro drive motor (1332). The silicone cleaning brush (1331) is attached to the outer surface of the sapphire glass window (131), and the micro drive motor (1332) is connected to the silicone cleaning brush (1331) for transmission.

5. The multi-parameter synchronous detection device based on open optical and optical path compensation of claim 1, wherein: The transmittance detection light source component (14) is the 16th LED light emitter (141), with a center wavelength of 680nm, which can emit 1KHz modulated light; the transmittance detection light source component (14) is fixed to the outside of the optical window component (13) by a stainless steel bracket (142), with a distance of 220mm from the optical window component (13), the length error of the stainless steel bracket (142) is ≤±0.5mm, and the offset angle between the center beam of the transmittance detection light source component (14) and the axis of the optical window component (13) is 15°.

6. The multi-parameter synchronous detection apparatus based on open optical and optical path compensation of claim 1, wherein: The photodetector unit (15) is a photomultiplier tube (151). The front end of the photomultiplier tube (151) is equipped with an OD6 level 680nm filter (152). The transmittance of the filter (152) is 90%, the half bandwidth is 10nm, and the wavelength is 675~685nm. The photomultiplier tube (151) is model H10722, the cathode photoelectric sensitivity is 205μA / lm, and the operating voltage is ±5V.

7. The multi-parameter synchronous detection device based on open optics and optical path compensation as described in claim 1, characterized in that: The signal acquisition module (2) includes a 24-bit ADS1256 analog-to-digital converter chip (21). The ADS1256 analog-to-digital converter chip (21) has two acquisition channels. The first channel is electrically connected to the photoelectric detection unit (15), and the second channel is electrically connected to the light source attenuation correction unit (12). The sampling rate of the ADS1256 analog-to-digital converter chip (21) is 1000 SPS. The median algorithm is used to extract the raw data during the acquisition process.

8. The multi-parameter synchronous detection device based on open optics and optical path compensation as described in claim 1, characterized in that: The optical path compensation processing module (3) is an STM32F407 microcontroller (31).

9. The multi-parameter synchronous detection device based on open optics and optical path compensation as described in claim 1, characterized in that: The environmental parameter sensing module (4) includes a water temperature sensor (41) and a water pressure sensor (42), both of which are in direct contact with the water body to be measured and are used to collect the temperature and water pressure parameters of the water body to be measured in real time.

10. The multi-parameter synchronous detection device based on open optics and optical path compensation as described in claim 1, characterized in that: The data storage and transmission module (5) includes a 32G Class 10 SD card (51) and a communication interface (52); the 32G Class 10 SD card (51) is electrically connected to the optical path compensation processing module (3); the communication interface (52) is an RS485 interface or a serial port to USB interface.

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