Liquid contact detection device and method based on optical fiber

Abstract

The invention discloses a liquid contact detection device and method based on an optical fiber, and the method comprises the steps: controlling a light emitter to emit light with a specific wavelength through a main control system, and forming a light source; light rays are transmitted to the optical fiber sensor through the optical fiber interface, are propagated in the optical fiber sensor through a path with a specific shape and then are captured through the optical fiber interface again, and the main control system controls the optical receiver to sample data to obtain optical data reflected by the optical transmitter through the optical fiber sensor; and the master control system analyzes the change of the intensity of the light data according to the collected light intensity data and judges whether the liquid is contacted or not. The scheme can be used for measuring dangerous liquid, overcomes the defect of low manual detection efficiency, and solves the problems of potential safety hazards of conductivity detection and easiness in being influenced by temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid detection, and in particular to an optical fiber-based liquid contact detection device and method. Background Art

[0002] Liquid detection plays a vital role in the fields of industrial production and safety inspection.

[0003] During the production process, liquid leakage may pose a serious threat to equipment and personnel safety. Liquid detection technology can be used to promptly detect potential leakage problems and take corresponding preventive measures to avoid possible equipment damage and personal injury.

[0004] When it comes to liquid storage, it is crucial to detect whether the liquid has reached a specific threshold. Liquid detection technology helps ensure that storage facilities meet specified capacity standards and prevent equipment failures or safety accidents caused by insufficient or excessive capacity.

[0005] In a liquid-enclosed space, the penetration of external liquid is extremely dangerous. Liquid detection technology can determine whether liquid has penetrated into the confined space, thereby ensuring the safety of the equipment in the space.

[0006] Traditional manual inspection methods have many drawbacks, especially during the inspection process, operators may encounter major safety risks. Liquid inspections are often carried out in complex environments, which may include narrow spaces, high temperature and high pressure areas, and the presence of toxic and hazardous substances. These factors significantly increase the risk of inspection work.

[0007] Traditional conductivity detection methods face some significant challenges and limitations in practical applications. This method is extremely susceptible to temperature changes, as temperature fluctuations can lead to inaccurate conductivity measurement results.

[0008] More importantly, when conducting conductivity testing in areas that are highly sensitive to electricity, there are certain safety risks that may pose potential threats to equipment and the environment. Due to the combined effect of these factors, traditional testing methods are greatly limited in accuracy and scope of application. Summary of the invention

[0009] In view of the above technical problems, the present invention provides a liquid contact detection device and method based on optical fiber, which overcomes the problems in traditional detection methods of being affected by the environment, leading to dangerous detection and inaccurate detection results.

[0010] The present invention is implemented by adopting the following technical scheme: an optical fiber-based liquid contact detection device, comprising an optical fiber sensor, an optical transmitter, an optical receiver, an optical fiber interface and a main control system; the optical fiber sensor is respectively connected to the optical transmitter and the optical receiver through the optical fiber interface, the optical transmitter and the optical receiver transmit data with the main control system, and the connection or disconnection of the optical fiber sensor and the optical transmitter or the optical receiver is controlled by the optical fiber interface.

[0011] Specifically, the optical fiber sensor comprises an optical fiber core, an optical fiber protective layer and an area in contact with the liquid to be measured, and the area in contact with the liquid to be measured is in a specific shape.

[0012] Specifically, the area of ​​the specific shape in contact with the liquid to be measured includes a curved shape of the central part of the optical fiber sensor.

[0013] Specifically, the light emitter includes a light emitting diode and a corresponding circuit to convert electrical energy into light energy.

[0014] Specifically, the optical receiver includes a photosensitive diode and a corresponding circuit to convert the received optical signal into an electrical signal.

[0015] Specifically, the main control system controls the optical fiber transmitter and processes the data of the optical fiber receiver and executes complex algorithms and instructions, including a single chip microcomputer, a DSP and an FPGA microprocessor.

[0016] Specifically, the main control also includes an A / D analog-to-digital converter to convert the analog signal of the optical receiver into a digital signal.

[0017] A liquid contact detection method based on optical fiber comprises the following steps: Step S1: The main control system controls the light emitter to emit light of a specific wavelength to form a light source; Step S2: The light is transmitted to the optical fiber sensor through the optical fiber interface, and after propagating through a path of a specific shape, it is captured again through the optical fiber interface. The main control system controls the optical receiver to sample the data and obtain the light data reflected back by the optical transmitter through the optical fiber sensor; Step S3: The main control system analyzes the change in light intensity based on the collected light intensity data to determine whether the light is in contact with liquid.

[0018] Specifically, the step S3 of judging whether the optical fiber sensor is in contact with the liquid specifically includes: if the light intensity decreases, it is judged that the optical fiber sensor is in contact with the liquid; if the light intensity increases, it is judged that the optical fiber sensor is not in contact with the liquid.

[0019] The beneficial effects of the present invention are as follows: the optical fiber sensor proposed in the present invention is made of optical fiber, which has the characteristic of being non-conductive. Therefore, the method can be used to measure dangerous liquids, such as gasoline, alcohol, etc.; in addition, it can detect whether the measured area is in contact with the liquid, reduce the interference of impurities in the liquid on the measurement results, eliminate the safety hazards when detecting in areas that are highly sensitive to electricity, overcome the low efficiency of manual detection, and solve the safety hazards of conductivity detection and the problem of susceptibility to temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 is a structural block diagram of a liquid detection device in an embodiment of the present invention; Figure 2 A structural diagram of an optical fiber sensor in one embodiment of the present invention; Figure 3 A structural diagram of an optical fiber sensor in another embodiment of the present invention; Figure 4 A schematic diagram of a program flow of a liquid detection method in one embodiment of the present invention; Figure 5 A line graph showing the relationship between the light intensity inside the optical fiber of the optical fiber sensor in contact with alcohol and time in one embodiment of the present invention; Figure 6 This is a line graph showing the relationship between the light intensity inside the optical fiber of the optical fiber sensor in contact with tap water and time in one embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0024] The following is combined with Figures 1 to 6, some embodiments of the present invention are described in detail. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0025] The present invention proposes a liquid contact detection device and method based on optical fiber. In a preferred embodiment, the liquid contact detection device based on optical fiber includes an optical fiber sensor, an optical transmitter, an optical receiver, an optical fiber interface and a main control. The optical fiber sensor is made of an optical fiber. Optical fiber is the abbreviation of optical fiber. It is a fibrous structure made of glass or plastic material and can effectively transmit light from the optical transmitter.

[0026] In this embodiment, the optical fiber sensor includes an optical fiber core, an optical fiber protective layer, and a specific shape. The specific state area is the area in contact with the measured liquid; the specific shape refers to the bending shape of the central part of the optical fiber sensor.

[0027] In this embodiment, the optical transmitter is composed of a light emitting diode and a circuit. The light emitting diode is a semiconductor device that can convert electrical energy into light energy. The optical receiver is composed of a photosensitive diode and a circuit. The photosensitive diode is a photoelectric conversion device that can convert the received optical signal into an electrical signal. The optical fiber interface is used to connect or disconnect the optical fiber sensor with the optical transmitter or optical receiver. The main control refers to a microprocessor such as a single chip microcomputer, DSP, FPGA, etc. that can execute complex algorithms and instructions, and is responsible for controlling the optical fiber transmitter and processing the data of the optical fiber receiver.

[0028] The corresponding optical fiber-based liquid contact detection method proposed by the present invention includes: The main control system controls the light transmitter to emit light of a specific wavelength to form a light source. These lights are transmitted to the fiber optic sensor through the fiber optic interface. After propagating through a path of a specific shape, they are captured by the light receiver again through the fiber optic interface. The main control system samples the light receiver to obtain the light data reflected back by the light transmitter through the fiber optic sensor. By analyzing the changes in the intensity of the light data, the main control system can determine whether the fiber optic sensor has come into contact with liquid.

[0029] In this embodiment, the specific wavelength is selected according to the absorbance of the measured liquid to the wavelength of light; the specific shape of the optical fiber sensor includes a U-shape, a circle, and other shapes that increase light leakage. The change in the intensity of the light data determines whether the sensor is in contact with the liquid. If the light intensity decreases, the optical fiber sensor is in contact with the liquid, and if the light intensity increases, the optical fiber sensor is not in contact with the liquid.

[0030] In one embodiment, if Figure 1 As shown, Figure 1 This is a structural block diagram of the optical fiber-based liquid contact detection device provided by the present invention. The optical fiber-based liquid contact detection device structure includes: 100- Main control: A microprocessor such as a single-chip microcomputer, DSP, or FPGA that can execute complex algorithms and instructions, responsible for controlling the fiber optic transmitter and processing the data of the fiber optic receiver; 200-Light emitter: It is composed of light-emitting diodes and circuits, converting electrical energy into light energy; 300- Optical receiver: It is composed of a photodiode and a circuit, and converts the received optical signal into an electrical signal; 400 and 500 - Fiber optic interface: connect or disconnect the fiber optic sensor with the optical transmitter or receiver; 600-Fiber optic sensor: includes a fiber core, a fiber protective layer, and a specific shape, where the specific shape area is the area in contact with the liquid to be measured; Reference Figure 2 and Figure 3 As shown, the structure of the optical fiber sensor includes: 601 and 602-Fiber protection layer: The fiber protection layer has good chemical corrosion resistance and can protect the fiber core from erosion and contamination by liquids, ensuring the accuracy of detection. The fiber protection layer is usually made of corrosion-resistant materials such as polytetrafluoroethylene (PTFE) or polyimide (PI). The thickness and material selection should be determined according to the properties of the liquid being measured; Core bend: The specific shape of the core bend can significantly increase the degree of light leakage in the optical fiber. The specific shape changes the transmission path of the light inside the optical fiber, causing the light that originally propagates along a straight line to be refracted and scattered when encountering the bend. In this embodiment, the refraction and scattering phenomena will cause part of the light to no longer continue to move along the axis of the optical fiber, but to deviate from the original path, thereby increasing the light leakage; the degree and angle of the bending of a specific shape have a direct impact on the degree of light leakage. If the bending radius is too small or the angle is too sharp, the light will suffer greater refraction and scattering at the bend, thereby exacerbating the light leakage; if the bending radius is larger or the angle is gentler, the refraction and scattering of the light at the bend will be relatively weakened, and the light leakage will be reduced accordingly. Figure 3 and Figure 2 The only difference is the bending shape of the fiber core.

[0031] In this embodiment, the main control includes an A / D analog-to-digital converter, which can convert the analog signal of the optical receiver into a digital signal.

[0032] Reference Figure 4 As shown, the main control program flow includes: S1-The master controller issues a command to turn on the optical transmitter; S2-master collects data from the optical receiver; S3-Determine whether there is contact with liquid based on the collected light intensity data.

[0033] In one embodiment, the specific detection steps include: the main control selects the STM32F407ZGT6 microcontroller launched by STMicroelectronics, the main control includes the minimum circuit for the operation of the microcontroller, the optical transmitter and the receiver select Avago HFBR-1414 and HFBR-2414, in order to facilitate the connection of the optical fiber sensor with the optical transmitter and the receiver, the optical fiber interface selects the ST interface, and the optical fiber selects PMMA optical fiber with a core diameter of 1mm and an outer diameter of 4.5mm.

[0034] Draw an optical transmitter and an optical receiver driving circuit, reserve a control pin in the optical transmitter driving circuit, reserve a signal sampling pin in the optical receiver driving circuit, connect the main control pin to the optical transmitter driving circuit control pin, and connect the main A / D analog-to-digital converter pin to the optical receiver driving circuit signal sampling pin. It should be noted that in the optical receiver driving circuit drawn in this embodiment, the relationship between the optical signal and the electrical signal is inversely proportional. The lower the voltage, the greater the light intensity, and the higher the voltage, the smaller the light intensity. The voltage range is 0-3300mV. The closer the collected electrical signal is to 0mV, the greater the light intensity. Conversely, the closer to 3300mV, the smaller the light intensity.

[0035] Connect the serial port pin of the master controller to the computer. The data collected by the master controller is printed in the computer through the serial port. It should be noted that this step is only for the convenience of observing the data.

[0036] In this embodiment, a fiber optic sensor is made by taking a complete fiber optic with a length of 100 cm, removing 10 cm of the protective layer at both ends of the fiber optic, removing 10 cm of the protective layer at the center of the fiber optic, retaining the fiber core, inserting the two ends of the fiber optic into the ST adapter respectively, fixing the fiber optic and the ST adapter with hot melt adhesive, and bending the center part of the fiber optic in the liquid area to be measured by the fiber optic sensor into Figure 2 The shape is fixed with hot melt adhesive, and the ST adapters at both ends of the optical fiber sensor are connected to the optical transmitter and the optical receiver.

[0037] Reference Figure 4 Write a program to turn on the light transmitter drive circuit control pin, the light transmitter emits light, and at the same time turn on the A / D analog-to-digital conversion to convert the optical signal of the light receiver into an electrical signal. The signal is collected at a time interval of 100ms. When the voltage is greater than 2500mV, it is determined that the optical fiber sensor is in contact with liquid.

[0038] 75% alcohol solution and tap water were selected as the measured liquids. The detection area of ​​the optical fiber sensor was in direct contact with the measured liquids. When the detection area of ​​the optical fiber sensor was transferred from the air environment to the liquid environment, the degree of light leakage inside the optical fiber would increase, thereby causing the strength of the collected electrical signal to increase. Once the strength of the electrical signal exceeded the set threshold of 2500mV, it was determined that the optical fiber sensor had been in contact with the liquid.

[0039] like Figure 5 : A line graph showing the relationship between the light intensity inside the optical fiber of the optical fiber sensor in contact with alcohol and time. It should be noted that the light signal has been converted into a voltage signal and is in inverse proportion to the voltage signal; Figure 6 : A line graph showing the relationship between the light intensity inside the optical fiber of the optical fiber sensor in contact with tap water and time. It should be noted that the light signal has been converted into a voltage signal and is inversely proportional. Figure 5 and Figure 6 It can be seen that when the optical fiber sensor is not in contact with the liquid, its voltage is maintained at about 400mV. When the sensor contacts the liquid, the voltage rises rapidly to nearly 3300mV. When the optical fiber sensor leaves the measured liquid, the voltage drops back to about 400mV. It is worth noting that at the moment of contact with the liquid, the voltage jumps from 400mV to 3300mV almost instantly. According to this embodiment, it can be seen that the optical fiber-based liquid contact detection device and method provided by the present invention has extremely high sensitivity.

[0040] For the aforementioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily required by the present application.

[0041] The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the changes and modifications made by those skilled in the art shall be within the scope of protection of the appended claims of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A liquid contact detection device based on optical fiber, characterized in that: It includes an optical fiber sensor, an optical transmitter, an optical receiver, an optical fiber interface and a main control system; the optical fiber sensor is connected to the optical transmitter and the optical receiver respectively through the optical fiber interface, the optical transmitter and the optical receiver transmit data with the main control system, and the connection or disconnection of the optical fiber sensor and the optical transmitter or the optical receiver is controlled by the optical fiber interface.

2. The optical fiber-based liquid contact detection device according to claim 1, characterized in that: The optical fiber sensor comprises an optical fiber core, an optical fiber protective layer and an area in contact with a liquid to be measured, and the area in contact with the liquid to be measured is in a specific shape.

3. The optical fiber-based liquid contact detection device according to claim 2, characterized in that: The area of ​​the specific shape that contacts the measured liquid includes a curved shape of the central part of the optical fiber sensor.

4. The optical fiber-based liquid contact detection device according to claim 1, characterized in that: The light emitter includes a light emitting diode and a corresponding circuit to convert electrical energy into light energy.

5. The optical fiber-based liquid contact detection device according to claim 1, characterized in that: The optical receiver includes a photodiode and a corresponding circuit to convert the received optical signal into an electrical signal.

6. The optical fiber-based liquid contact detection device according to claim 1, characterized in that: The main control system controls the optical fiber transmitter and processes the data of the optical fiber receiver and executes complex algorithms and instructions, including a single chip microcomputer, a DSP and an FPGA microprocessor.

7. The optical fiber-based liquid contact detection device according to claim 6, characterized in that: The main control also includes an A / D analog-to-digital converter, which converts the analog signal of the optical receiver into a digital signal.

8. An optical fiber-based liquid contact detection method, implemented based on an optical fiber-based liquid contact detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step S1: The main control system controls the light emitter to emit light of a specific wavelength to form a light source; Step S2: The light is transmitted to the optical fiber sensor through the optical fiber interface, and after propagating through a path of a specific shape, it is captured again through the optical fiber interface. The main control system controls the optical receiver to sample the data and obtain the light data reflected back by the optical transmitter through the optical fiber sensor; Step S3: The main control system analyzes the change in light intensity based on the collected light intensity data to determine whether the light is in contact with liquid.

9. The optical fiber-based liquid contact detection method according to claim 8, characterized in that: The step S3 of judging whether the optical fiber sensor is in contact with the liquid specifically includes: if the light intensity decreases, it is judged that the optical fiber sensor is in contact with the liquid; if the light intensity increases, it is judged that the optical fiber sensor is not in contact with the liquid.

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