Underwater far-field detection fluorescent sensor
Through the combination of the side separation light-emission structure and the backscattering function, the problem of the fluorescent signal in the far-floor detection fluorescent sensor being submerged is solved, and the efficient collection and detection of far-field fluorescent signals is achieved, which is suitable for underwater miniaturization detection.
Patent Information
- Application Number
- CN202510521328.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-25
AI Technical Summary
The detection range of existing underwater detection fluorescence sensors is mostly near-field detection. As the distance from the optical path window of the fluorescence collection increases, the three-dimensional angle of fluorescence collection decreases rapidly, resulting in the fluorescence signal of the distant water body being submerged and cannot be distinguished.
The side separation light-emission structure is adopted, and the excitation light path area and the collection light path area are offset. Combined with the backscattering function, it reduces near-field fluorescence interference and improves the collection efficiency of far-field fluorescence signals.
Effectively resolve far-field fluorescence signals, reduce near-field fluorescence interference, improve the detection accuracy of underwater remote fluorescence detection sensors, and meet the needs of underwater miniaturization.
Smart Images
Figure CN120369623A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of underwater optical detection equipment, and in particular to an underwater far-field detection fluorescence sensor. Background Art
[0002] The ocean covers 71% of the Earth's surface area and harbors rich natural resources. In the natural environment, specific fluorescent substances emit specific wavelengths of fluorescence after absorbing the energy of excitation light of a specific wavelength. According to this property, specific substances can be detected by an optical sensor that emits and collects specific wavelengths of light, and this technology has been widely applied in the biological field, medical field, etc. China has a vast ocean area. With the progress of science and technology, in-situ ocean fluorescence sensors have been widely applied to ocean environment detection, such as applications in detecting marine biota, undersea oil exploration, and detecting oil spills from undersea oil pipelines, which greatly saves manpower and material resources and has broad application prospects.
[0003] The optical path structure is crucial for the design of an optical sensor. A high-quality optical path can significantly improve the signal-to-noise ratio of the input optical signal of the optical sensor and its anti-interference ability.
[0004] The applicant of the present invention has found that the existing underwater detection fluorescence sensors have at least the following technical problems:
[0005] The detection range of existing underwater detection fluorescence sensors is mostly near-field detection, and the optical path design of underwater detection fluorescence sensors is coaxial or oblique incidence design. In the coaxial optical path, the excitation light optical path and the collected light optical path are coaxial. The excitation light is emitted from the window and irradiates the water body, and the fluorescence of the water body is detected by adding it to the sensor through the window. In the oblique incidence optical path, the excitation light and the fluorescence collection optical path are non-coaxial. Among them, the excitation optical path shapes and filters the light of the light source and then emits the light, and the fluorescent substances in the irradiated area will be excited to emit fluorescence.
[0006] Due to the absorption, scattering and other effects of the water body on the excitation light, and the excitation light has a tendency to gradually diverge in water. Since the fluorescence intensity is proportional to the excitation light intensity in a dilute solution, the fluorescence intensity gradually decreases as the distance from the excitation light exit window increases. More importantly, as the distance from the window of the fluorescence collection optical path increases, the solid angle of fluorescence collection rapidly decreases, approximately following a square decay, which will result in the fluorescence signal of the water body near the window of the fluorescence collection optical path being much stronger than that of the water body in the distance, and further cause the fluorescence signal of the water body in the distance to be submerged and indistinguishable.
[0007] Therefore, there is an urgent need for an underwater far-field detection fluorescence sensor to solve the above technical problems. Summary of the Invention
[0008] The object of the present invention is to provide an underwater far-field detection fluorescence sensor, so as to solve the technical problem existing in the prior art that as the distance from the window of the fluorescence collection optical path increases, the solid angle of fluorescence collection rapidly decreases, approximately following a square attenuation, which will result in the fluorescence signal of the water body close to the window of the fluorescence collection optical path being much stronger than that of the water body in the distance, and further cause the fluorescence signal of the water body in the distance to be submerged and indistinguishable. The preferred technical solutions among the many technical solutions provided by the present invention and the many technical effects that can be produced will be elaborated in detail below.
[0009] To achieve the above object, the present invention provides the following technical solutions:
[0010] An underwater far-field detection fluorescence sensor provided by the present invention includes a housing assembly and an excitation light assembly, an emission light assembly, a backscattered excitation assembly, a backscattered emission assembly, and a power supply and data acquisition assembly arranged inside the housing assembly, wherein:
[0011] The housing assembly includes a housing and an excitation light window, an emission light window, a backscattered excitation light window, a backscattered emission light window, and a watertight connector arranged on the housing;
[0012] The excitation light assembly is coaxially arranged with the excitation light window; the emission light assembly is coaxially arranged with the emission light window; the backscattered excitation assembly is coaxially arranged with the backscattered excitation light window; the backscattered emission assembly is coaxially arranged with the backscattered emission light window;
[0013] The power supply and data acquisition assembly is connected to the excitation light assembly, the emission light assembly, the backscattered excitation assembly, and the backscattered emission assembly, and is used for power supply and data transmission. The watertight connector is connected to the power supply and data acquisition assembly.
[0014] Preferably, the excitation light assembly includes an excitation light source, an excitation lens, and an excitation filter arranged coaxially at intervals in sequence, and the light-emitting point of the excitation light source is placed within the focal length of the excitation lens.
[0015] Preferably, the emission light assembly includes a photodetector, an emission lens, and an emission filter arranged coaxially at intervals in sequence, and the photosensitive surface of the photodetector is placed at the focus of the emission lens.
[0016] Preferably, the excitation light source is one of a laser diode or a photodiode.
[0017] Preferably, the wavelength of the laser diode is between 365 nm and 630 nm, the divergence angle is 5° - 60°, and the power consumption is 0.05 W - 10 W;
[0018] The response wavelength of the photodiode is between 365 nm and 800 nm.
[0019] Preferably, both the excitation lens and the emission lens are spherical or aspherical lenses, and the focal length is 3 mm - 20 mm;
[0020] Both the excitation filter and the emission filter are band-pass filters, and the optical density OD > 3.5.
[0021] Preferably, the photodetector is one of a photodiode, an avalanche diode, and a photomultiplier tube.
[0022] Preferably, the included angle α between the optical path of the backscattering excitation component and the optical path of the backscattering emission component is between 5° and 80°.
[0023] Preferably, four through holes are sequentially arranged on the same side of the surface of the housing, and the excitation light window, the emission light window, the backscattering excitation light window, and the backscattering emission light window are respectively placed in the through holes, and a sealing structure is arranged at each connection.
[0024] Preferably, the materials of the excitation light window, the emission light window, the backscattering excitation light window, and the backscattering emission light window are one of quartz, K9, acrylic, and sapphire.
[0025] The underwater far-field detection fluorescence sensor provided by the present invention, by arranging an excitation light window, an emission light window, a backscattering excitation light window, and a backscattering emission light window on the side of the housing, adopting a side-separated light-emitting structure, there is an offset between the excitation optical path region and the collection optical path region, ensuring that the fluorescence excited in the near field is not collected by the photodetector, and only the fluorescence in the far-field fluorescence excitation region can be collected by the photodetector, which can reduce the interference of near-field fluorescence and meet the requirements of the sensor for detecting fluorescence substances such as underwater far-field oil spills and microorganisms. In addition, compared with the existing end-face separated light-emitting sensor, the side-separated light-emitting structure can meet the underwater far-field fluorescence detection while the design of multiple light windows will not increase the diameter of the sensor, maximizing the use of the internal space of the sensor, thereby reducing the volume and weight of the sensor; and this sensor has a self-backscattering function, which can reduce the influence of the scattering of waterborne particulate matter on the fluorescence substance and improve the detection accuracy of the underwater remote fluorescence detection sensor. Description of the Drawings
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0027] Figure 1 It is a schematic structural diagram of an embodiment of the underwater far-field detection fluorescence sensor of the present invention;
[0028] Figure 2 It is a schematic principle diagram of the underwater far-field detection fluorescence sensor of the present invention;
[0029] Figure 3 It is a schematic principle diagram of the underwater far-field detection fluorescence sensor with a coaxial light window structure where the excitation light source is a laser diode;
[0030] Figure 4 It is a schematic structural diagram of the underwater far-field detection fluorescence sensor with a coaxial light window structure where the excitation light source is a laser diode.
[0031] In the figure: 1. Outer shell; 2. Laser diode; 3. Excitation lens; 4. Excitation filter; 5. Excitation light window; 6. Photoelectric detector; 7. Emission lens; 8. Emission filter; 9. Emission light window; 10. Backscattered excitation light window; 11. Backscattered emission light window; 12. Watertight connector; 13. Photodiode; 14. Dichroic mirror; 15. In-out light window; 16. Coaxial light window pressure-resistant outer shell; 101. Outer shell assembly; 102. Excitation light assembly; 103. Emission light assembly; 104. Backscattered excitation assembly; 105. Backscattered emission assembly; 106. Power supply and data acquisition assembly; 107. Coaxial light window outer shell assembly; A. Excitation light path area; B. Collection light path area; C. Fluorescence excitation area; D. Coaxial light window fluorescence strong area; E. Coaxial light window fluorescence weak area; α. Angle between the backscattered excitation assembly light path and the backscattered emission assembly light path. Detailed implementation manners
[0032] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative work shall fall within the scope protected by the present invention.
[0033] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "lateral", "length", "width", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "side", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention 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 thus should not be construed as a limitation to the present invention.
[0034] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0035] Figure 1 is a structural schematic diagram of this embodiment, Figure 2 is a schematic diagram of the principle of this embodiment, as Figure 1 and Figure 2 shown, this embodiment provides an underwater far-field detection fluorescence sensor, which includes a housing assembly 101, an excitation light assembly 102, an emission light assembly 103, a backscattered excitation assembly 104, a backscattered emission assembly 105, and a power supply and data acquisition assembly 106. The excitation light assembly 102, the emission light assembly 103, the backscattered excitation assembly 104, the backscattered emission assembly 105, and the power supply and data acquisition assembly 106 are all arranged in the housing assembly 101.
[0036] Among them, the housing assembly 101 includes a housing 1 and an excitation light window 5, an emission light window 9, a backscattered excitation light window 10, a backscattered emission light window 11, and a watertight connector 12 provided on the housing 1.
[0037] The housing 1 in this embodiment is a hollow and sealed cylindrical shell, and the housing 1 is made of one of pressure-resistant stainless steel, titanium alloy, polymer material, and ceramic. Four through holes are sequentially arranged on the same side of the surface of the housing 1, and the excitation light window 5, the emission light window 9, the backscattered excitation light window 10, and the backscattered emission light window 11 are respectively placed in the through holes, and a sealing structure is provided at each connection.
[0038] Specifically, the materials of the excitation light window 5, the emission light window 9, the backscattered excitation light window 10, and the backscattered emission light window 11 in this embodiment are one of quartz, K9, acrylic, and sapphire. To improve the sealing performance, a rubber O-ring or epoxy resin glue is used for sealing.
[0039] In order to improve the detection sensitivity of the existing underwater fluorescence sensor, a large-diameter light window design is selected to improve the fluorescence collection efficiency. The conventional design is to design the light window on the pressure-resistant housing end cover. The large-diameter light window design will increase the diameter of the pressure-resistant housing of the sensor, which is particularly obvious in the non-coaxial light window design. Under the same pressure-resistant conditions, while increasing the diameter of the sensor, the thickness of the sensor housing also increases, which will lead to low utilization rate of the internal space of the sensor, large volume and overall weight of the whole machine, and does not meet the requirements of underwater miniaturized carrying.
[0040] In the underwater far-field detection fluorescence sensor of this embodiment, in order to reduce the volume and weight of the sensor, so as to better meet the requirements of underwater miniaturized loading and far-field fluorescence substance detection, an excitation light window 5, an emission light window 9, a backscattered excitation light window 10, and a backscattered emission light window 11 are arranged on the side of the outer shell 1. A side-separated light output structure is adopted. Through the separated optical path design, on the premise of ensuring sufficient fluorescence distance selectivity, the conflict between the diameter and sensitivity of end-face light output can be avoided, which is beneficial to reducing the outer diameter of the sensor and thus the weight of the outer shell on the premise of ensuring the same sensitivity. Moreover, the distance between the two light output windows of side light output is more diverse, which is beneficial to selecting an appropriate fluorescence detection range and reducing the problem that the long-distance fluorescence signal is completely submerged by the short-distance fluorescence signal due to the fluorescence collection solid angle problem. And the side-separated light output structure can meet the design requirements of large aperture and multiple light windows during far-field detection, making the best use of the internal space of the sensor and being more suitable for being carried by underwater small AUVs and other vehicles.
[0041] As Figure 1 and Figure 2 shown, the excitation light component 102 in this embodiment is coaxially arranged with the excitation light window 5. The excitation light component 102 includes an excitation light source, an excitation lens 3, and an excitation filter 4 that are coaxially arranged at intervals in sequence, and the light-emitting point of the excitation light source is placed within the focal length F of the excitation lens 3. The excitation light source in this embodiment is one of a laser diode 2 or a photodiode 13.
[0042] Among them, the wavelength of the laser diode is between 365nm - 630nm, the divergence angle is 5° - 60°, and the power consumption is 0.05W - 10W; the response wavelength of the photodiode is between 365nm - 800nm.
[0043] The emission light component 103 in this embodiment is coaxially arranged with the emission light window 9; the emission light component 103 includes a photodetector 6, an emission lens 7, and an emission filter 8 that are coaxially arranged at intervals in sequence, and the photosensitive surface of the photodetector 6 is placed at the focus of the emission lens 7. The photodetector in this embodiment is one of a photodiode, an avalanche diode, and a photomultiplier tube.
[0044] The excitation lens 3 and the emission lens 7 in this embodiment are both spherical or aspherical lenses, and the focal length is 3mm - 20mm; the excitation filter 4 and the emission filter 8 are both band-pass filters, and the optical density OD > 3.5.
[0045] In this embodiment, there is an offset between the excitation optical path region A and the collection optical path region B, ensuring that the near-field excited fluorescence is not collected by the photodetector. Only the fluorescence within the far-field fluorescence excitation region C can be collected by the photodetector 6. Ensuring that the near-field excited fluorescence is not collected by the photodetector and only the fluorescence within the far-field fluorescence excitation region can be collected by the photodetector can reduce the interference of near-field fluorescence and meet the requirements for detecting fluorescence substances such as underwater far-field oil spills and microorganisms by the sensor.
[0046] Existing underwater fluorescence detection sensors do not have a backscattering correction function, which will cause the influence of particulate matter scattering in the water on the fluorescence substance, thereby affecting the detection accuracy of the underwater fluorescence detection sensor.
[0047] Regarding this, as Figure 1 and Figure 2 shown, the underwater far-field detection fluorescence sensor in this embodiment is provided with a backscattering excitation component 104 and a backscattering emission component 105. The backscattering excitation component 104 is coaxially arranged with the backscattering excitation optical window 10; the backscattering emission component 105 is coaxially arranged with the backscattering emission optical window 11. The included angle α between the optical path of the backscattering excitation component 104 and the optical path of the backscattering emission component 105 in this embodiment is between 5° and 80°. The specific angle needs to be simulated using optical software to find a suitable angle according to actual usage requirements.
[0048] This underwater far-field detection fluorescence sensor can reduce the interference of particulate matter scattering in the water on fluorescence detection through its own backscattering correction function, thereby improving the detection accuracy of the underwater far-field detection fluorescence sensor. It can detect substances in the underwater far-field region and has the advantages of simple structure, high reliability, small volume, and strong pressure resistance.
[0049] As Figure 1 and Figure 2 shown, the power supply and data acquisition component 106 in this embodiment is connected to the excitation light component 102, the emission light component 103, the backscattering excitation component 104, and the backscattering emission component 105 for power supply and data transmission. The watertight connector 12 is connected to the power supply and data acquisition component 106.
[0050] The power supply and data acquisition component 106 in this embodiment is internally provided with a power supply battery, which can meet the self-contained operation of the device, that is, the power supply and data acquisition component 106 powers the entire sensor and collects and analyzes the data generated by the excitation light component 102, the emission light component 103, the backscattering excitation component 104, and the backscattering emission component 105.
[0051] The working principle of this underwater far-field detection fluorescence sensor is as follows: The excitation lens shapes the excitation light of the excitation light source and then emits the light. The fluorescent substance in the irradiated area will be excited to emit fluorescence. Since the intensity of the excitation light decays as the optical path of the excitation light becomes longer, and the fluorescence generated therefrom also weakens from strong to weak, it is necessary to avoid the area with strong near-field fluorescence when detecting substances in the underwater far-field area. In the present invention, the excitation light optical path and the fluorescence emission optical path are not coaxial, which can avoid the fluorescence interference in the near-field area; by adding a backscattering component, the influence of particulate matter scattering in the water on fluorescence detection can be reduced, thereby improving the detection accuracy of the underwater far-field detection fluorescence sensor.
[0052] The following is a detailed description through specific embodiments:
[0053] Example 1
[0054] An underwater far-field detection fluorescence sensor is used for detecting underwater far-field fluorescent substances. The overall structure is as Figure 1 shown. The sensor is of cable type. The housing assembly 101 is a hollow sealed housing composed of a pressure-resistant housing 1, an excitation light window 5, an emission light window 9, a backscattering excitation light window 10, a backscattering emission light window 11, and a watertight connector 12. Among them, the excitation light window 5 and the emission light window 9 are sealed with the cylindrical housing through rubber O-rings, and the backscattering excitation light window 10 and the backscattering emission light window 11 are sealed with the cylindrical housing by using epoxy resin glue. The excitation light window 5, the emission light window 9, the backscattering excitation light window 10, and the backscattering emission light window 11 are all made of sapphire material. The material of the pressure-resistant housing 1 is titanium alloy. A watertight connector 12 is provided at the rear end cover. The watertight connector 12 is a commercially available multi-core watertight connector, and the watertight connector 12 can be connected to a small AUV through a cable to transmit and upload the collected data in real time. The excitation light source uses a laser diode with a wavelength of 375 nm, an optical power of 2 W, and a power consumption of 5 W. The excitation lens 3 is an aspherical lens with a focal length of 6 mm, and the emission lens 7 is a spherical lens with a focal length of 3 mm - 20 mm. The excitation filter 4 and the emission filter 8 are band-pass filters with an optical density OD > 5.5. The included angle α between the optical paths of the backscattering excitation component 104 and the backscattering emission component 105 is 36°.
[0055] Comparative Example 1
[0056] As Figure 4As shown in the figure, the difference between this comparative example and Example 1 lies in: a coaxial underwater far-field detection fluorescence sensor. The coaxial optical window housing assembly 107 is a hollow sealed housing composed of a coaxial optical window pressure-resistant housing 16, an incident and exit optical window 15, a backscattered excitation optical window 10, a backscattered emission optical window 11, and a watertight connector 12. Among them, the incident and exit optical window 15 is sealed with the front end cover of the coaxial optical window pressure-resistant housing 16 through a rubber O-ring. The backscattered excitation optical window 10, the backscattered emission optical window 11, and the front end cover of the coaxial optical window pressure-resistant housing 16 are sealed with epoxy resin glue. The incident and exit optical window 15, the backscattered excitation optical window 10, and the backscattered emission optical window 11 are all made of sapphire. The coaxial optical window pressure-resistant housing 16 is made of titanium alloy. Its rear end cover is provided with a watertight connector 12. The watertight connector 12 is a commercially available multi-core watertight connector. The watertight connector 12 can be connected to a small AUV through a cable to transmit the collected data in real time.
[0057] The excitation light source, the excitation lens 3, and the excitation filter 4 are arranged coaxially and at intervals in sequence to form an excitation optical path. The excitation optical path enters the emission optical path through the reflection of the dichroic mirror 14. The dichroic mirror 14 can transmit fluorescence and is placed at a 45° angle to the excitation optical path. The photodetector 6, the emission lens 7, and the emission filter 8 are arranged coaxially and at intervals in sequence to form an emission optical path. The collection optical path passes through the dichroic mirror 14, and the emission optical path is arranged on the other side of the excitation light reflection surface of the dichroic mirror 14 and is placed at a 90° angle to the excitation optical path.
[0058] The excitation light source uses a laser diode with a wavelength of 385 nm, an optical power of 1 W, and a power consumption of 3 W. The excitation lens 3 is an aspherical lens with a focal length of 5 mm. The emission lens 7 is a spherical lens with a focal length of 3 mm - 15 mm. The excitation filter 4 and the emission filter 8 are band-pass filters with an optical density OD > 5. The included angle α between the optical path of the backscattered excitation component 104 and the optical path of the backscattered emission component 105 is 36°.
[0059] Results of Comparative Experiment 1:
[0060] Diesel is used as a fluorescent substance and dispersed in tap water.
[0061] For the coaxial optical path, the contribution of the fluorescence signal of the water body at a distance of 0 cm - 20 cm from the window to the output signal is 3211 mV, and the contribution of the fluorescence signal of the water body at a distance of 100 cm - 200 cm from the window to the output signal is 195 mV.
[0062] Using the structure in Example 1, the contribution of the fluorescence signal of the water body at a distance of 0 cm - 20 cm from the window to the output signal is 257 mV, and the contribution of the fluorescence signal of the water body at a distance of 100 cm - 200 cm from the window to the output signal is 210 mV. The fluorescence signal of the water body at 100 cm - 200 cm can be effectively resolved.
[0063] Results of Comparative Experiment 2:
[0064] Quinine sulfate was used as a fluorescent substance and dissolved in tap water.
[0065] For the coaxial optical path, the contribution of the fluorescence signal of the water body at a distance of 0 cm - 20 cm from the window to the output signal was 5482 mV, and the contribution of the fluorescence signal of the water body at a distance of 100 cm - 200 cm from the window to the output signal was 375 mV.
[0066] Using the structure in Example 1, the contribution of the fluorescence signal of the water body at a distance of 0 cm - 20 cm from the window to the output signal was 612 mV, and the contribution of the fluorescence signal of the water body at a distance of 100 cm - 200 cm from the window to the output signal was 437 mV, and the fluorescence signal of the water body at 100 cm - 200 cm could be effectively resolved.
[0067] Conclusion: The fluorescence intensity in the strong fluorescence region D of the coaxial optical window is much greater than the fluorescence signal intensity in the weak fluorescence region E of the signal coaxial optical window, which causes the fluorescence signal in the weak fluorescence region E of the coaxial optical window to be "submerged", thus making it difficult to detect the signal of the sample to be measured. Since the separated optical window optical path structure avoids the interference of strong fluorescence in the near-field region, the detection sensitivity of the underwater far-field detection fluorescence sensor to far-field fluorescent substances is improved.
[0068] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims
1. An underwater far-field detection fluorescence sensor, characterized in that, It includes a housing assembly and an excitation light assembly, an emission light assembly, a backscattering excitation assembly, a backscattering emission assembly, and a power supply and data acquisition assembly disposed inside the housing assembly, where: The housing assembly includes a housing and an excitation light window, an emission light window, a backscattering excitation light window, a backscattering emission light window, and a watertight connector disposed on the housing; The excitation light assembly is coaxially disposed with the excitation light window; the emission light assembly is coaxially disposed with the emission light window; the backscattering excitation assembly is coaxially disposed with the backscattering excitation light window; the backscattering emission assembly is coaxially disposed with the backscattering emission light window; The power supply and data acquisition assembly is connected to the excitation light assembly, the emission light assembly, the backscattering excitation assembly, and the backscattering emission assembly, and is used for power supply and data transmission. The watertight connector is connected to the power supply and data acquisition assembly.
2. The underwater far-field detection fluorescence sensor according to claim 1, characterized in that: The excitation light assembly includes an excitation light source, an excitation lens, and an excitation filter that are coaxially and spaced apart in sequence. The light emitting point of the excitation light source is placed within the focal length of the excitation lens.
3. An underwater far-field detection fluorescence sensor according to claim 2, characterized in that: The emission light assembly includes a photodetector, an emission lens, and an emission filter that are coaxially and spaced apart in sequence. The photosensitive surface of the photodetector is placed at the focus of the emission lens.
4. An underwater far-field detection fluorescence sensor according to claim 2 or 3, characterized in that: The excitation light source is one of a laser diode or a photodiode.
5. An underwater far-field detection fluorescence sensor according to claim 4, characterized in that: The wavelength of the laser diode is between 365 nm and 630 nm, the divergence angle is 5° - 60°, and the power consumption is 0.05 W - 10 W; The response wavelength of the photodiode is between 365 nm and 800 nm.
6. The underwater far-field detection fluorescence sensor according to claim 3, characterized in that: Both the excitation lens and the emission lens are spherical or aspherical lenses, and the focal length is 3 mm - 20 mm; Both the excitation filter and the emission filter are band-pass filters, and the optical density OD > 3.
5.
7. An underwater far-field detection fluorescence sensor according to claim 3, characterized in that: The photodetector is one of a photodiode, an avalanche diode, or a photomultiplier tube.
8. An underwater far-field detection fluorescence sensor according to any one of claims 1-3, characterized in that: The included angle α between the optical path of the backscattering excitation assembly and the optical path of the backscattering emission assembly is between 5° and 80°.
9. An underwater far-field detection fluorescence sensor according to any one of claims 1-3, characterized in that: Four through holes are sequentially arranged on the same side of the surface of the housing. The excitation light window, the emission light window, the backscattering excitation light window, and the backscattering emission light window are respectively placed in the through holes, and a sealing structure is provided at each connection.
10. An underwater far-field detection fluorescence sensor according to claim 9, characterized in that: The materials of the excitation light window, the emission light window, the backscattering excitation light window, and the backscattering emission light window are one of quartz, K9, acrylic, or sapphire.