Optical window pollution self-immunization water body transparency detector

Abstract

The application discloses the technical fields of environmental monitoring and water analysis and relates to a water transparency detector with self-immunization of optical window pollution, which comprises a light source, a first reflector, a beam splitter, a sample cell, a second reflector and a third reflector. The first reflector reflects the light of the light source to the beam splitter, and the beam splitter divides the light into transmitted light and reflected light. The transmitted light transmits through the sample cell and is converged by the second reflector to a transmitted end photoelectric detector. The reflected light is converged by the third reflector to a reference end photoelectric detector. The water transparency can be calculated according to the light intensity of the transmitted end photoelectric detector and the reference end photoelectric detector. The application dynamically offsets the error caused by the optical window pollution, light source fluctuation and detector drift through a double-light-path signal and a clean and polluted window pollution error double-ratio real-time compensation algorithm, so that the measurement accuracy can be ensured without a physical cleaning device. In addition, the application can monitor the change trend of the light intensity ratio and actively sense the degree of optical window pollution.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring and water analysis technology, and in particular to a water transparency detector with an optical window that is self-immune to pollution. Background Technology

[0002] Water transparency is one of the important and intuitive indicators for evaluating water quality, and it is widely used in water quality monitoring and evaluation of rivers, lakes, reservoirs, and coastal waters. Traditional measurement methods, such as the Sebschler disk method, are simple, but they are greatly affected by human judgment and lighting conditions, resulting in low efficiency. Furthermore, they cannot achieve continuous online monitoring, making it difficult to meet the real-time and continuous data requirements of modern water quality monitoring networks.

[0003] To address this need, existing online optical translucency meters have emerged, most of which employ a direct-light optical path structure, calculating transparency by measuring the attenuation of light after it passes through a water sample. These instruments are gradually being applied in scenarios such as river management, water source safety early warning, wastewater treatment plant effluent monitoring, aquaculture water quality monitoring, and smart environmental protection IoT. However, during long-term, unattended deployments in these scenarios, these instruments face a common and severe technical challenge: their optical windows are inevitably contaminated by microbial adhesion, algae growth, sediment deposition, and oil adhesion, leading to a continuous decrease in window transmittance, severe signal drift, and significant measurement errors. Simultaneously, this reduces the efficiency of acquiring the original light signal, thus affecting the instrument's detection range.

[0004] Currently, the main solutions in the industry for optical window contamination fall into two categories: one is to rely on frequent manual cleaning and maintenance, which brings huge workload and high operation and maintenance costs, and causes monitoring data interruption; the other is to use active cleaning devices such as mechanical scraping, ultrasonic cleaning or chemical cleaning, but these methods significantly increase the complexity, cost, power consumption and failure rate of the system.

[0005] In terms of optical compensation technology, existing technologies employ dual-optical-path designs, attempting to compensate for the effects of factors such as light source fluctuations through a reference optical path. However, these traditional dual-optical-path compensation schemes have significant limitations: they typically only compensate for aging or fluctuations in the light source itself, failing to effectively address common path attenuation caused by optical window contamination. This is because when the optical window is contaminated, both the transmission and reference optical paths are usually affected to varying degrees, significantly reducing the compensation effect. Furthermore, these schemes lack real-time diagnostic capabilities for the degree of contamination, failing to provide early warnings and maintenance before signal distortion occurs, still requiring periodic manual intervention.

[0006] Therefore, developing an online transparency detector that can be immune to or automatically compensate for window contamination effects from the measurement principle, and that combines high reliability, low maintenance, and long-term stability, has become an urgent technical challenge to break through industry application bottlenecks and promote the development of water quality monitoring technology. Summary of the Invention

[0007] To address the aforementioned problems in existing technologies, this invention provides a water transparency detector with an optical window that is self-immunizing against contamination. It innovatively employs a dual-optical-path structure constructed from three parabolic mirrors, with one optical path used for transmitting the sample and the other for reference. The water transparency can be calculated by measuring the light intensity of the two optical paths.

[0008] The technical solution of the present invention is as follows:

[0009] An optical window pollution self-immunization water transparency detector includes a light source 1, a first reflector 2, a beam splitter 3, a sample cell 4, a transmission end photodetector 5, a reference end photodetector 6, a modulation drive circuit 7, a transmission signal conditioning circuit 8, a reference signal conditioning circuit 9, a second reflector 10, a third reflector 11, and a processing and display unit.

[0010] The light source 1, the first reflecting mirror 2, the beam splitter 3, the sample cell 4, the transmission end photodetector 5, and the second reflecting mirror 10 together form the transmission light path; the modulation driving circuit 7 generates a sinusoidal modulation signal of a specific frequency, which drives the light source 1 to emit modulated light. The modulated light is reflected by the first reflecting mirror 2 to form parallel light, which is called incident light; the incident light irradiates the beam splitter 3.

[0011] The beam splitter 3 has a planar structure. After the incident light shines on the beam splitter 3, part of it is transmitted through the beam splitter 3 and the rest is reflected by the beam splitter 3. The incident light that passes through the beam splitter 3 shines on the sample cell 4.

[0012] The sample cell 4 is made of an optically transparent corrosion-resistant material. The area of ​​the sample cell 4 that is irradiated by incident light is called the optical window. After the incident light irradiates the optical window and passes through the sample cell 4, it is called transmitted light. The transmitted light irradiates the second reflector 10, and the second reflector 10 reflects the transmitted light to the transmission end photodetector 5. The transmission signal conditioning circuit 8 is connected to the transmission end photodetector 5 and converts the optical signal received by the transmission end photodetector 5 into an electrical signal.

[0013] The beam splitter 3, the reference end photodetector 6, and the third reflecting mirror 11 together form a reflected light path; the incident light is reflected by the beam splitter 3 to form reflected light; the reflected light illuminates the third reflecting mirror 11; the third reflecting mirror 11 reflects the reflected light to the reference end photodetector 6; the reference signal conditioning circuit 9 converts the optical signal on the reference end photodetector 6 into an electrical signal.

[0014] The processing and display unit includes a signal acquisition module and a microprocessor. The signal acquisition module is connected to the transmission signal conditioning circuit 8 and the reference signal conditioning circuit 9, and converts the electrical signals of the transmission signal conditioning circuit 8 and the reference signal conditioning circuit 9 from analog quantities to digital quantities, which are respectively called the transmission end signal and the reference end signal. The microprocessor receives the transmission end signal and the reference end signal and calculates the water transparency.

[0015] Furthermore, the first reflector 2, the second reflector 10, and the third reflector 11 are all parabolic reflectors; the light source is located at the focal point of the first reflector 2; the transmission end photodetector 5 is located at the focal point of the second reflector 10; and the reference end photodetector 6 is located at the focal point of the third reflector 11.

[0016] Furthermore, the first reflector 2, the second reflector 10, and the third reflector 11 are made of aluminum alloy, and the reflective surfaces are coated with an enhanced high-reflectivity protective film suitable for the near-infrared band.

[0017] Furthermore, the light source 1 is a near-infrared LED lamp assembly with a wavelength of 840~910 nm;

[0018] The number of near-infrared LED light groups is 6 to 10;

[0019] The near-infrared LED light assembly is housed within a removable quartz sleeve.

[0020] Furthermore, the transmittance of the beam splitter is 50% to 70%.

[0021] Furthermore, the material of the sample cell 4 is fused silica or borosilicate glass.

[0022] Furthermore, the transmission end photodetector 5 and the reference end photodetector 6 are silicon photodiodes.

[0023] Furthermore, the transmitted light path is perpendicular to the reflected light path.

[0024] A method for detecting water transparency using an optical window contamination self-immunization device includes the following steps:

[0025] S1. With the optical window clean, inject pure water sample into sample cell 4, process and display unit record and store the transmission end signal I_measure and reference end signal I_ref at this time, and calculate the reference ratio R_clean = I_measure / I_ref;

[0026] S2. Inject the water sample to be tested into the sample cell 4, and the processing and display unit acquires the transmission signal value I_measure and the reference signal value I_ref in real time.

[0027] S3. Calculate the ratio of the transmitted signal to the reference signal R = I_measure / I_ref, compare it with the clean baseline ratio, compensate for the optical window contamination error in real time, and output the corrected water transmittance T_water = R / R_clean.

[0028] S4. Calculate the SDD value of the water body based on T_water and the built-in transmittance and Sage disk depth (SDD) calibration model; if the R value continues to drop to the preset threshold, the processing display unit will issue an alarm for recalibration or disassembly and cleaning of the sample cell.

[0029] The beneficial technical effects of this invention are as follows:

[0030] This invention realizes a self-immune mechanism against optical window contamination. Through a unique dual-ratio algorithm (T_water = R / R_clean), it dynamically offsets errors caused by optical window contamination, light source fluctuations, and detector drift. This eliminates the need for the instrument to rely on any physical self-cleaning devices such as mechanical scrapers or ultrasonic waves, effectively solving the industry's core pain point of data drift caused by contamination. It also significantly reduces operation and maintenance costs and complexity, and ensures the accuracy of data during long-term online measurements.

[0031] This invention establishes a hardware platform for high signal-to-noise ratio and wide measurement range. It innovatively uses a large-aperture parabolic mirror to construct the optical system, which utilizes its focal characteristics to efficiently collect and converge light signals, greatly improving the capture efficiency of weak light signals and significantly expanding the dynamic detection range of the instrument. This provides physical assurance for the simultaneous and accurate measurement of water bodies with extremely high and extremely low transparency.

[0032] This invention achieves a high degree of system integration and strong reliability. Due to the innovative optical and algorithm design, the traditional moving cleaning components are completely eliminated, fundamentally eliminating failure modes such as mechanical wear and jamming. This makes the instrument structure more compact, consumes less power, and further improves its service life and operational reliability, making it especially suitable for deployment in harsh environments where it is unattended for a long time.

[0033] This invention endows the equipment with intelligent self-diagnosis and predictive maintenance capabilities. By intelligently monitoring the long-term trend of signal ratio changes through a microprocessor, it can proactively diagnose the state of contamination accumulation in the optical window and issue maintenance prompts in advance before performance deteriorates, guiding users to perform simple recalibration. This achieves an intelligent leap from "passive maintenance" to "predictive maintenance," greatly improving user experience and data reliability. Attached Figure Description

[0034] Figure 1 This is a block diagram illustrating the overall structure and working principle of a water transparency meter.

[0035] Figure 2 This is a flowchart of the adaptive compensation algorithm.

[0036] In the figure, the correspondence between the component names and the attached drawing numbers is as follows: 1. Light source; 2. First reflector; 3. Beam splitter; 4. Sample cell; 5. Transmission end photodetector; 6. Reference end photodetector; 7. Modulation drive circuit; 8. Transmission signal conditioning circuit; 9. Reference signal conditioning circuit; 10. Second reflector; 11. Third reflector. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the embodiment includes a housing, an optical detection system, a signal conditioning unit, and a processing and display unit.

[0039] The optical detection system includes a light source 1, a beam splitter 3, a transmission optical path, and a reference optical path, and is used to capture weak light signals.

[0040] Light source 1 is a near-infrared LED lamp assembly with a wavelength of 870 nm. There are 10 of them, which are housed in a detachable quartz sleeve to protect the near-infrared LED lamp assembly and facilitate lamp assembly replacement.

[0041] The beam splitter 3 has a transmittance of 70% and a reflectance of 30%. It is placed in the optical path emitted by the light source 1 and is used to split the beam into transmitted light and reference light.

[0042] The transmission optical path includes a first reflecting mirror 2 for collimating the light rays, a sample cell 4, a second reflecting mirror 10 for converging the light rays, and a photodetector 5 at the transmission end.

[0043] Both the first reflecting mirror 2 and the second reflecting mirror 10 are parabolic reflectors. The light source 1 is placed at the focal point of the first reflecting mirror 2, and the photodetector 5 at the transmission end is placed at the focal point of the second reflecting mirror 10. Both the first reflecting mirror 2 and the second reflecting mirror 10 are made of aluminum alloy and have an enhanced high-reflectivity protective film for the near-infrared band coated on their optical surfaces. Alternatively, both the first reflecting mirror 2 and the second reflecting mirror 10 can be made of gold-plated metal substrates to achieve higher reflectivity and corrosion resistance.

[0044] The sample cell 4 is made of an optically transparent corrosion-resistant material, including but not limited to fused silica or borosilicate glass, and can be connected to the main body of the embodiment via clamp flanges or quick-release buckles for easy disassembly, cleaning or replacement.

[0045] The photodetector 5 at the transmission end is a silicon photodiode.

[0046] The reference optical path includes a third reflecting mirror 11 for converging light rays and a reference end photodetector 9.

[0047] The third reflecting mirror 11 is a parabolic reflecting mirror, and the reference end photodetector 9 is placed at the focal point of the third reflecting mirror 11. The third reflecting mirror 11 is made of aluminum alloy and has an enhanced high-reflectivity protective film for the near-infrared band coated on its optical surface; the third reflecting mirror 11 can also be made of a gold-plated metal substrate to obtain higher reflectivity and corrosion resistance.

[0048] The reference end photodetector 9 is a silicon photodiode.

[0049] The transmitted light path is perpendicular to the reference light path.

[0050] The advantage of using three parabolic mirrors to construct a dual-optical-path structure is that it can improve the utilization rate of light energy and the light intensity on the photodetector, thereby improving the sensitivity and range of the detector.

[0051] The signal conditioning unit includes a modulation drive circuit 7, a transmission signal conditioning circuit 8, and a reference signal conditioning circuit 9, which are used to convert weak optical signals into electrical signals readable by the system.

[0052] The modulation drive circuit 7 generates a 339Hz sinusoidal control signal through the microsystem to drive the light source 1 to emit modulated light; the transmission signal conditioning circuit 8 and the reference signal conditioning circuit 9 are connected to the transmission photodetector 5 and the reference photodetector 6, respectively, to extract the two light intensity signals synchronized with the modulation frequency and convert them into electrical signals.

[0053] The processing and display unit includes a signal acquisition module, a microprocessor, and a display system. The signal acquisition module is connected to the signal conditioning unit and has the function of converting analog signals to digital signals. It is connected to the transmission signal conditioning circuit 8 and the reference signal conditioning circuit 9 and receives the electrical signals from both, which are referred to as the transmission end signal and the reference end signal, respectively.

[0054] The microprocessor is connected to the signal acquisition module and performs the following operations: implements a real-time contamination error compensation algorithm to achieve error compensation by calculating the real-time ratio of the transmission end signal to the reference end signal; converts the processed signal into a transparency measurement value according to the calibration model; monitors the trend of signal ratio changes to achieve intelligent diagnosis of the optical window contamination status; and generates maintenance prompt signals and abnormal alarm information.

[0055] The display system is a host computer with a human-machine interface, which can provide operation status monitoring, parameter setting, fault alarm and historical data analysis.

[0056] like Figure 2 As shown, the microprocessor performs the following operations:

[0057] S1. Calibration steps: With the optical window clean, inject pure water sample into sample cell 4, process and display unit record and store the transmission end signal I_measure and reference end signal I_ref at this time, and calculate the reference ratio R_clean = I_measure / I_ref;

[0058] S2. Measurement steps: Inject the water sample to be tested into the sample cell 4, and the processing and display unit acquires the transmission end signal I_measure and the reference end signal I_ref in real time;

[0059] S3. Compensation calculation steps: Calculate the ratio R = I_measure / I_ref between the transmission end signal and the reference end signal, compare it with the clean baseline ratio, compensate for optical window contamination error in real time, and output the corrected water transmittance T_water = R / R_clean.

[0060] S4. Results Output and Intelligent Prompt Steps: Calculate the SDD value of the water body based on T_water and the built-in transmittance and Sage Disk Depth (SDD) calibration model, and display the results; when the R value is detected to continuously decrease to the preset threshold, prompt the user to perform recalibration or disassemble and clean the sample cell, realizing intelligent self-diagnosis of the equipment.

[0061] The embodiment establishes a unique "self-immune" error compensation mechanism. Through a real-time compensation algorithm using dual optical path signals and the dual ratio of clean and contaminated windows, it dynamically offsets errors caused by optical window contamination, light source fluctuations, and detector drift, ensuring measurement accuracy without the need for physical cleaning devices. Furthermore, the embodiment implements intelligent self-diagnosis, proactively sensing the degree of optical window contamination and indicating maintenance needs by monitoring the trend of the signal ratio R, achieving a technological leap from passive measurement to intelligent self-sensing. The embodiment effectively solves industry pain points such as poor data reliability, frequent maintenance, and limited measurement range in long-term online monitoring, providing a high-precision, high-reliability, and low-maintenance-cost solution for water transparency detection.

[0062] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, and for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. A water transparency detector with an optical window that is self-immune to pollution, characterized in that: The detector includes a light source (1), a first reflector (2), a beam splitter (3), a sample cell (4), a transmission end photodetector (5), a reference end photodetector (6), a modulation drive circuit (7), a transmission signal conditioning circuit (8), a reference signal conditioning circuit (9), a second reflector (10), a third reflector (11), and a processing and display unit. The light source (1), the first reflector (2), the beam splitter (3), the sample cell (4), the transmission end photodetector (5), and the second reflector (10) together form the transmission light path; the modulation drive circuit (7) generates a sinusoidal modulation signal of a specific frequency, which drives the light source (1) to emit modulated light. The modulated light is reflected by the first reflector (2) to form parallel light, which is called incident light; the incident light irradiates the beam splitter (3); The beam splitter (3) has a planar structure. After the incident light shines on the beam splitter (3), part of it is transmitted through the beam splitter (3), and the rest is reflected by the beam splitter (3). The incident light that passes through the beam splitter (3) shines on the sample cell (4). The sample cell (4) is made of an optically transparent corrosion-resistant material. The area of ​​the sample cell (4) irradiated by incident light is called the optical window. After the incident light irradiates the optical window and passes through the sample cell (4), it is called transmitted light. The transmitted light irradiates the second reflector (10), and the second reflector (10) reflects the transmitted light to the transmission end photodetector (5). The transmission signal conditioning circuit (8) is connected to the transmission end photodetector (5) and converts the optical signal received by the transmission end photodetector (5) into an electrical signal. The beam splitter (3), the reference end photodetector (6), and the third reflector (11) together form a reflected light path; the incident light is reflected by the beam splitter (3) to form reflected light; the reflected light shines on the third reflector (11); the third reflector (11) reflects the reflected light onto the reference end photodetector (6); the reference signal conditioning circuit (9) converts the optical signal on the reference end photodetector (6) into an electrical signal; The processing and display unit includes a signal acquisition module and a microprocessor; the signal acquisition module is connected to the transmission signal conditioning circuit (8) and the reference signal conditioning circuit (9), and converts the electrical signals of the transmission signal conditioning circuit (8) and the reference signal conditioning circuit (9) from analog quantities to digital quantities, which are respectively called the transmission end signal and the reference end signal; the microprocessor receives the transmission end signal and the reference end signal and calculates the water transparency; The detection method includes the following steps: S1. With the optical window clean, inject pure water sample into the sample cell (4), process and display unit record and store the transmission end signal I_measure and the reference end signal I_ref at this time, and calculate the reference ratio R_clean = I_measure / I_ref; S2. Inject the water sample to be tested into the sample cell (4), and the processing and display unit acquires the transmission signal value I_measure and the reference signal value I_ref in real time. S3. Calculate the ratio of the transmitted signal to the reference signal R = I_measure / I_ref, compare it with the clean baseline ratio, compensate for the optical window contamination error in real time, and output the corrected water transmittance T_water = R / R_clean. S4. Calculate the SDD value of the water body based on T_water and the built-in transmittance and Sage disk depth calibration model; if the R value continues to drop to the preset threshold, the processing display unit will issue an alarm for recalibration or disassembly and cleaning of the sample cell.

2. The water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that: The first reflector (2), the second reflector (10) and the third reflector (11) are all parabolic reflectors; the light source is located at the focal point of the first reflector (2); the transmission end photodetector (5) is located at the focal point of the second reflector (10); and the reference end photodetector (6) is located at the focal point of the third reflector (11).

3. The water transparency detector with self-immunization against optical window contamination according to claim 2, characterized in that: The first reflector (2), the second reflector (10) and the third reflector (11) are made of aluminum alloy and are coated with an enhanced high-reflectivity protective film suitable for the near-infrared band.

4. The water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that: The light source (1) is a near-infrared LED lamp group with a wavelength of 840~910 nm; The number of near-infrared LED light groups is 6 to 10; The near-infrared LED light assembly is housed within a removable quartz sleeve.

5. A water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that, The transmittance of the beam splitter is 50%~70%.

6. A water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that, The sample cell (4) is made of fused silica or borosilicate glass.

7. A water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that: The transmission end photodetector (5) and the reference end photodetector (6) are silicon photodiodes, i.e., SiPhotodiodes.

8. A water transparency detector with self-immunization against optical window contamination according to claim 1, characterized in that, The transmitted light path is perpendicular to the reflected light path.

Images