Multi-channel demodulation control system based on optical fiber sensing

Abstract

The utility model discloses a multichannel demodulation control system based on optical fiber sensing, and relates to the demodulation control field of optical fiber sensing. Comprising a scanning laser, a coupler, an etalon, a photoelectric detector, a filter amplifier, a hardware acquisition module, a software analysis module, an optical splitter, an FBG sensor, a front-end control computer, a server and a monitoring host. The multi-channel demodulation control system based on optical fiber sensing can resolve various optical fiber sensors such as an optical fiber thermometer, an optical fiber pressure gauge, an optical fiber strain gauge, a micro-electro-mechanical optical fiber accelerometer, an optical fiber reinforcement meter, an optical fiber concrete strain gauge and an optical fiber dynamometer, and supports series and parallel connection networking among the sensors. Meanwhile, the system is designed with the functions of self-detection, fault alarm and the like, so that the requirements of electromagnetic compatibility design and industrial environment adaptability are met.

Description

Technical Field

[0001] The utility model relates to the field of demodulation control of optical fiber sensing, in particular to a multi-channel demodulation control system based on optical fiber sensing. Background Art

[0002] As optical fiber communication and related technologies become increasingly mature, research on sensing technology using fiber Bragg gratings as sensitive materials has received widespread attention, and fiber Bragg grating sensing technology has developed rapidly. At present, fiber Bragg grating sensing technology using FBG as the sensing element is still the mainstream of research and development. At the same time, research efforts on other types of fiber Bragg grating sensors are also increasing.

[0003] Since a series of problems such as the stability of fiber Bragg grating performance, the cross-sensitivity effect of temperature and strain, the sensitization and desensitization packaging technology, the photoelectric conversion of the sensing signal demodulation and the cost performance have not been effectively solved, most research results are still in the laboratory research stage. In the field of fiber Bragg grating sensing research and development, light sources, demodulation schemes and multiplexing technologies have always been the focus of research. The following is divided into three parts to explain:

[0004] One is the research on the sensor itself and the sensor that can perform lateral strain sensing and high sensitivity, high resolution, and can simultaneously sense temperature and strain changes;

[0005] The second is an obstacle that limits the large-scale practical application of fiber Bragg grating sensors, the demodulation of sensing signals, and the goal is to develop low-cost, miniaturized, reliable and highly sensitive detection technology;

[0006] The third is the practical application research of fiber grating sensors, including packaging technology, temperature compensation technology, and sensor multiplexing network technology. For example, in applications, it is generally required that the reflection spectra of the gratings cannot overlap, while the bandwidth of the actual light source is limited, so the number of multiplexed gratings is limited; how to achieve large-scale, high-precision, fast and real-time measurement; how to solve the cross-sensitivity problem of temperature and strain, etc.

[0007] Among them, the main obstacle limiting the application of fiber grating sensors is the demodulation of the sensing signal. There are many demodulation methods being studied, but there are not many demodulation products that can be actually applied, and they are expensive. Therefore, it is of great significance to effectively solve the above problems and realize a cheap, stable, high-precision, high-resolution, large measurement range, and multi-grating multiplexed fiber optic sensor demodulation control system. In addition, the core component of the existing instruments, the fiber FP filter, is imported and expensive. The instrument accuracy is greatly affected by temperature, and temperature self-compensation and wavelength self-calibration cannot be achieved. At the same time, many instrument manufacturers use optical switches for switching, not synchronous acquisition, and their software customization performance is poor, the total price is expensive, and the cost performance is poor.

[0008] Existing demodulators can only measure reflective devices. In some engineering sites or laboratory research that have requirements on sensor sensitivity, it is necessary to use transmissive optical sensors such as long-period gratings for measurement. In previous uses, long-period fiber gratings or other transmissive fiber optic devices can only be demodulated and collected through expensive spectrometers or wavelength meters. This project sets a specific optical module in the optical path based on the spectral characteristics of the transmissive device, combined with the corresponding transmitted light photoelectric conversion circuit, to achieve signal demodulation of the transmissive device.

[0009] Therefore, it is necessary to propose a multi-channel demodulation control system based on optical fiber sensing to solve the above problems. Utility Model Content

[0010] The main purpose of the utility model is to provide a multi-channel demodulation control system based on optical fiber sensing, which can effectively solve the problems in the background technology.

[0011] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0012] A multi-channel demodulation control system based on optical fiber sensing, comprising a scanning laser, a coupler, an etalon, a photodetector, a filter amplifier, a hardware acquisition module, a software analysis module, an optical splitter, an FBG sensor, a front-end control computer, a server and a monitoring host, wherein the output end and input end of the scanning laser and the output end and input end of the coupler are connected to each other, the input end of the scanning laser is electrically connected to a driver, the output end of the coupler is connected to the input end of the etalon and the optical splitter, the output end of the optical splitter is connected to the input end of the FBG sensor, the output end of the etalon is connected to the input end of the photodetector, the output end of the photodetector is connected to the input end of the filter amplifier, the output end of the filter amplifier is connected to the input end of the hardware acquisition module, and the output end of the hardware acquisition module is connected to the input end of the software analysis module;

[0013] The system comprises a hardware circuit, wherein the hardware circuit comprises a DSP minimum system, an A / D acquisition module, an FP filter control module, a serial port transmission module, and a storage module;

[0014] Includes FPGA and ARM modules.

[0015] Preferably, the scanning laser is composed of a broadband light source and an adjustable FP filter, there are at least two FBG sensors, and the reflection wavelength of each FBG sensor is different, and a piezoelectric body is installed in the cavity of the FBG sensor, and the piezoelectric body is used to load a sawtooth scanning voltage and to adjust the cavity length of the FP cavity.

[0016] Preferably, the photodetector is used to convert the optical signal into an analog electrical signal, the A / D acquisition module is used to amplify and synchronously acquire the signal, and the DSP minimum system is used to store the acquired data in an internal storage module, read it from the memory when processing the data, and process the data through a microprocessor to demodulate the wavelength data.

[0017] Preferably, the FP filter control module is used to generate a periodic sawtooth wave with adjustable amplitude and bias to provide a scanning voltage for the FP filter, and the serial port transmission module is used to send the demodulated wavelength data to a host computer through a customized communication protocol.

[0018] Preferably, the FPGA and ARM modules are used for signal preprocessing and fault alarm, and the FPGA and ARM modules are equipped with including but not limited to industrial-grade LC / APC, FC / APC optical interfaces, and network interfaces compliant with industrial communication RJ45 standards. The FPGA and ARM modules are used for communication with the fan master control and the fan server, and the FPGA and ARM modules can be selected to include but not limited to Ethernet, RS485, and CAN protocols.

[0019] Preferably, the front-end control computer includes collecting and displaying received data, the collection is a hardware collection module, the server includes forwarding commands and transfer, the monitoring host includes executing collection and uploading, and the front-end control computer, server and monitoring host are used to issue collection commands, command feedback, and read and upload data.

[0020] Beneficial Effects

[0021] Compared with the prior art, the utility model provides a multi-channel demodulation control system based on optical fiber sensing, which has the following beneficial effects:

[0022] 1. This multi-channel demodulation control system based on optical fiber sensing can calculate a variety of optical fiber sensors such as optical fiber thermometers, optical fiber pressure gauges, optical fiber strain gauges, micro-electromechanical optical fiber accelerometers, optical fiber rebar gauges, optical fiber concrete strain gauges and optical fiber dynamometers. It supports serial and parallel networking between sensors and can realize simultaneous calculation of multiple types and hundreds of sensors. The system is designed with self-detection and fault alarm functions to meet the requirements of electromagnetic compatibility design and industrial environment adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the utility model system;

[0024] Figure 2 It is a structural schematic diagram of the acquisition function of the utility model. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific implementation methods.

[0026] like Figure 1-2 As shown, a multi-channel demodulation control system based on optical fiber sensing includes a scanning laser, a coupler, an etalon, a photodetector, a filter amplifier, a hardware acquisition module, a software analysis module, an optical splitter, an FBG sensor, a front-end control computer, a server and a monitoring host. The output end and input end of the scanning laser and the output end and input end of the coupler are connected to each other. The input end of the scanning laser is electrically connected to a driver. The output end of the coupler is connected to the input end of the etalon and the optical splitter. The output end of the optical splitter is connected to the input end of the FBG sensor. The output end of the etalon is connected to the input end of the photodetector. The output end of the photodetector is connected to The input end of the filter amplifier is connected, the output end of the filter amplifier is connected to the input end of the hardware acquisition module, the output end of the hardware acquisition module is connected to the input end of the software analysis module, including a system hardware circuit, the system hardware circuit includes a DSP minimum system, an A / D acquisition module, an FP filter control module, a serial port transmission module, a storage module, including an FPGA and an ARM module, the scanning laser is composed of a broadband light source and an adjustable FP filter, the number of FBG sensors is at least two, and the reflection wavelength of each FBG sensor is different, a piezoelectric body is installed in the cavity of the FBG sensor, the piezoelectric body is used to load a sawtooth wave scanning voltage, and It is used to adjust the cavity length of the FP cavity. The photodetector is used to convert the optical signal into an analog electrical signal. The A / D acquisition module is used to amplify and synchronously acquire the signal. The DSP minimum system is used to store the acquired data in the internal storage module. When processing the data, it is read out from the memory and processed by the microprocessor to demodulate the wavelength data. The FP filter control module is used to generate a periodic sawtooth wave with adjustable amplitude and bias, and provide a scanning voltage for the FP filter. The serial port transmission module is used to send the demodulated wavelength data to the host computer through a customized communication protocol. The FPGA and ARM modules are used for signal preprocessing and fault Alarm, FPGA and ARM modules are equipped with including but not limited to industrial-grade LC / APC, FC / APC optical interfaces, and network interfaces that comply with the industrial communication RJ45 standard. FPGA and ARM modules are used to communicate with the fan master control and fan server. FPGA and ARM modules can be selected but not limited to Ethernet, RS485, and CAN protocols. The front-end control computer includes collecting and displaying received data. The collection is a hardware collection module. The server includes forwarding commands and transfer. The monitoring host includes executing collection and uploading. The front-end control computer, server and monitoring host are used to issue collection commands, command feedback, and read and upload data.

[0027] This system can calculate a variety of fiber optic sensors such as fiber optic thermometers, fiber optic pressure gauges, fiber optic strain gauges, micro-electromechanical fiber optic accelerometers, fiber optic rebar gauges, fiber optic concrete strain gauges, and fiber optic dynamometers. It supports series and parallel networking between sensors and can realize simultaneous calculation of multiple types and hundreds of sensors. The system is designed with self-detection and fault alarm functions to meet the requirements of electromagnetic compatibility design and industrial environment adaptability.

[0028] It should be noted that the utility model is a multi-channel demodulation control system based on optical fiber sensing. When in use, the light emitted by the scanning laser composed of a broadband light source + an adjustable FP filter passes through a coupler and enters a plurality of sensing FBGs with different reflection wavelengths. The light that meets the Bragg condition is reflected back and then enters the adjustable optical fiber FP filter through a coupler. A sawtooth wave scanning voltage is applied to the piezoelectric body on the FP cavity to adjust the length of the FP cavity. If the transmission peak of the FP filter coincides with the reflection peak of the FBG, the transmission light intensity of the FP filter reaches the maximum. Different scanning voltages correspond to different wavelengths of the transmission light. In this way, at different times in the same scanning cycle, multiple FBG reflection wavelengths pass through the FP cavity, and then the optical signal is converted into an electrical signal through photoelectric conversion. After amplification, filtering and other conditioning circuits, the optical signal finally enters the data acquisition card and is sent to the computer for signal processing in combination with the host computer software. Finally, the measured signal is demodulated.

[0029] The system hardware circuit mainly includes DSP minimum system, A / D acquisition module, FP filter control module, serial port transmission module and storage module. After the photoelectric detector converts the optical signal of the fiber Bragg grating sensor system into an analog electrical signal, the A / D acquisition module amplifies and synchronously acquires the signal. The sampling rate is high and the data volume is large. The DSP first stores the acquired data in the internal storage module and reads it out from the memory when processing the data. After the signal acquisition is completed, the microprocessor processes the data and demodulates the wavelength data. The FP filter control module generates a periodic sawtooth wave with adjustable amplitude and bias to provide a scanning voltage for the FP filter. The serial port transmission module mainly sends the demodulated wavelength data to the host computer through a customized communication protocol.

[0030] The system has built-in FPGA and ARM modules, and has functions such as signal preprocessing and fault alarm. Its interface is equipped with industrial-grade LC / APC or FC / APC optical interface and industrial communication RJ45 standard network interface. It can complete communication with the fan master control / fan server. Ethernet, RS485, CAN and other protocols are available.

[0031] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A multi-channel demodulation control system based on optical fiber sensing, including a scanning laser, a coupler, an etalon, a photodetector, a filter amplifier, a hardware acquisition module, a software analysis module, an optical splitter, an FBG sensor, a front-end control computer, a server and a monitoring host, characterized in that: The output end and input end of the scanning laser and the output end and input end of the coupler are connected to each other, the input end of the scanning laser is electrically connected to a driver, the output end of the coupler is connected to the input end of the etalon and the optical splitter, the output end of the optical splitter is connected to the input end of the FBG sensor, the output end of the etalon is connected to the input end of the photodetector, the output end of the photodetector is connected to the input end of the filter amplifier, the output end of the filter amplifier is connected to the input end of the hardware acquisition module, and the output end of the hardware acquisition module is connected to the input end of the software analysis module; The system comprises a hardware circuit, wherein the hardware circuit comprises a DSP minimum system, an A / D acquisition module, an FP filter control module, a serial port transmission module, and a storage module; Includes FPGA and ARM modules.

2. The multi-channel demodulation control system based on optical fiber sensing according to claim 1, characterized in that: The scanning laser is composed of a broadband light source and an adjustable FP filter. There are at least two FBG sensors, and the reflection wavelength of each FBG sensor is different. A piezoelectric body is installed in the cavity of the FBG sensor. The piezoelectric body is used to load a sawtooth scanning voltage and to adjust the cavity length of the FP cavity.

3. The multi-channel demodulation control system based on optical fiber sensing according to claim 1, characterized in that: The photoelectric detector is used to convert the optical signal into an analog electrical signal, the A / D acquisition module is used to amplify and synchronously acquire the signal, and the DSP minimum system is used to store the acquired data in the internal storage module, read it from the memory when processing the data, and process the data through the microprocessor to demodulate the wavelength data.

4. The multi-channel demodulation control system based on optical fiber sensing according to claim 1, characterized in that: The FP filter control module is used to generate a periodic sawtooth wave with adjustable amplitude and bias to provide a scanning voltage for the FP filter, and the serial port transmission module is used to send the demodulated wavelength data to the host computer through a customized communication protocol.

5. The multi-channel demodulation control system based on optical fiber sensing according to claim 1, characterized in that: The FPGA and ARM modules are used for signal preprocessing and fault alarm. The FPGA and ARM modules are equipped with, including but not limited to, industrial-grade LC / APC, FC / APC optical interfaces, and network interfaces that comply with the industrial communication RJ45 standard. The FPGA and ARM modules are used for communication with the fan master control and the fan server. The FPGA and ARM modules can be selected to include but are not limited to Ethernet, RS485, and CAN protocols.

6. The multi-channel demodulation control system based on optical fiber sensing according to claim 1, characterized in that: The front-end control computer includes collecting and displaying received data, the collection is a hardware collection module, the server includes forwarding commands and transfer, the monitoring host includes executing collection and uploading, and the front-end control computer, server and monitoring host are used to issue collection commands, command feedback, and read and upload data.

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