Fiber bragg grating demodulation system based on edge filter

Abstract

The invention discloses a fiber bragg grating demodulation system based on an edge filter. The system comprises a fiber bragg grating hardware unit and a fiber bragg grating hardware circuit unit connected with the fiber bragg grating hardware unit. The fiber grating hardware unit is provided with an edge filter; the fiber bragg grating hardware unit is used for collecting an optical signal with external temperature information and carrying out wavelength selection on the optical signal with the external temperature information so as to obtain a filtered optical signal; and the fiber grating hardware circuit unit is used for performing photoelectric signal conversion on the filtered optical signal to obtain an electric signal with external temperature information, performing amplification filtering and analog-to-digital conversion on the electric signal with the external temperature information to obtain an external temperature digital signal, and storing the external temperature digital signal. According to the invention, the temperature of the FBG sensor can be measured under different working conditions, and the accuracy of the obtained external temperature digital signal is improved.

Description

Technical Field

[0001] The invention relates to the field of fiber grating demodulation, and in particular to a fiber grating demodulation system based on an edge filter. Background Art

[0002] The fiber Bragg grating demodulation system uses a fiber Bragg grating sensor, an optical path system, and a hardware circuit board to convert the change of the external physical quantity to be measured into a photocurrent signal. The optical path system ensures that the circuit board can receive the signal to the greatest extent, and the hardware circuit board strives to process the signal as accurately and as real-time as possible.

[0003] The existing fiber Bragg grating demodulation system can perform temperature measurement of FBG sensors under different working conditions, but the accuracy of the temperature signal finally obtained still needs to be improved. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a fiber Bragg grating demodulation system based on an edge filter.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A fiber Bragg grating demodulation system based on an edge filter comprises a fiber Bragg grating hardware unit and a fiber Bragg grating hardware circuit unit connected to the fiber Bragg grating hardware unit;

[0007] The fiber Bragg grating hardware unit is provided with an edge filter; the fiber Bragg grating hardware unit is used to collect the optical signal with external temperature information, and perform wavelength selection on the optical signal with external temperature information to obtain the filtered optical signal;

[0008] The fiber grating hardware circuit unit is used to convert the filtered optical signal into an optical signal to obtain an electrical signal with external temperature information, amplify and filter the electrical signal with external temperature information, perform analog-to-digital conversion to obtain an external temperature digital signal, and store the external temperature digital signal.

[0009] Furthermore, the fiber Bragg grating hardware unit includes a fiber coupler, a fiber Bragg grating sensor and an edge filter; the fiber coupler is used to transmit an externally generated optical signal to the fiber Bragg grating sensor, and collect an optical signal with external temperature information reflected by the fiber Bragg grating sensor; the fiber Bragg grating sensor is used to reflect the optical signal with external temperature information to the fiber coupler; the edge filter is used to perform wavelength selection on the reflected optical signal with external temperature information collected in the fiber coupler to obtain a filtered optical signal.

[0010] Furthermore, the optical fiber coupler adopts a three-port polarization-maintaining circulator.

[0011] Furthermore, the edge filter adopts a long period fiber grating.

[0012] Furthermore, the fiber Bragg grating hardware circuit unit includes a photoelectric conversion circuit, an amplification and filtering circuit, and a signal processing module.

[0013] Furthermore, the signal processing module includes a DSP minimum control system, a power supply circuit, an analog-to-digital converter, a communication module and an external expansion storage circuit.

[0014] The present invention has the following beneficial effects:

[0015] The present invention constructs a fiber Bragg grating hardware unit and a fiber Bragg grating hardware circuit unit connected to the fiber Bragg grating hardware unit; the fiber Bragg grating hardware unit is provided with an edge filter; the fiber Bragg grating hardware unit is used to collect an optical signal with external temperature information, and perform wavelength selection on the optical signal with the external temperature information to obtain a filtered optical signal; the fiber Bragg grating hardware circuit unit is used to perform photoelectric signal conversion on the filtered optical signal to obtain an electrical signal with the external temperature information, amplify and filter the electrical signal with the external temperature information, perform analog-to-digital conversion to obtain an external temperature digital signal, and store the external temperature digital signal, so that the temperature of the FBG sensor can be measured under different working conditions, and the accuracy of the obtained external temperature digital signal is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of a fiber Bragg grating demodulation system based on an edge filter;

[0017] Figure 2 It is a schematic diagram of the structure of the signal processing module;

[0018] Figure 3 Schematic diagram of the circuit structure of the signal processing module. DETAILED DESCRIPTION

[0019] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0020] like Figure 1 As shown, a fiber Bragg grating demodulation system based on an edge filter includes a fiber Bragg grating hardware unit and a fiber Bragg grating hardware circuit unit connected to the fiber Bragg grating hardware unit.

[0021] In an optional embodiment of the present invention, the fiber Bragg grating hardware unit is provided with an edge filter; the fiber Bragg grating hardware unit is used to collect the optical signal with external temperature information, and perform wavelength selection on the optical signal with external temperature information to obtain the filtered optical signal.

[0022] The fiber Bragg grating hardware unit includes a fiber coupler, a fiber Bragg grating sensor and an edge filter; the fiber coupler is used to transmit an externally generated optical signal to the fiber Bragg grating sensor, and collect an optical signal with external temperature information reflected by the fiber Bragg grating sensor; the fiber Bragg grating sensor is used to reflect the optical signal with external temperature information to the fiber coupler; the edge filter is used to select the wavelength of the reflected optical signal with external temperature information collected in the fiber coupler to obtain a filtered optical signal.

[0023] As shown in the table, considering the applicable range of wavelengths in the sensing system and the problem of loss during transmission, the present invention decides to use ASE light source as the broadband light source of the sensing system. Its spectral range is 1528-1603nm and the central wavelength is 1565nm. At the same time, the ASE light source is highly compatible with optical fiber and can be easily integrated into the optical fiber system. The good flatness of the spectrum ensures uniform light output. In addition, its excellent stability and reliability ensure stable performance in long-term operation.

[0024] The fiber coupler uses a three-port polarization-maintaining circulator. As a multi-port fiber optic device, the fiber optic circulator has the "asymmetric transmission" characteristic, which makes the light incident from a certain port all emitted from the next port, ensuring that the optical signal can only propagate in one direction. Taking the three-port fiber optic circulator as an example, if the light is incident from port 1, it can and can only be emitted from port 2. The reflected light formed by the light emitted from port 2 after reflection still enters port 2, but the reflected light will not be emitted from port 1, but from port 3. This design avoids the phenomenon that the reflected light causes light pollution or damage to other optical components.

[0025] The edge filter uses a long-period fiber grating. In the present invention, the reflected light is divided into two optical signals with the same characteristics after passing through the circulator and the beam splitter. According to the experimental design, one of the signals needs to be processed by the edge filter. The edge filter plays the role of wavelength selection, improving the signal-to-noise ratio and simplifying the system. Its performance has a great influence on the sensitivity, accuracy and reliability of the system, so the selection of the edge filter is also one of the keys. The period of the long-period fiber grating (LPFG) is usually above the millimeter level. Due to the long period, the LPFG has a relatively wide response range to the wavelength of the incident light, so it can achieve the filtering effect of the optical signal within a specific wavelength range. The working principle of LPFG is based on coupling effect and diffraction effect. When the incident light passes through the LPFG, part of the light will be coupled with the periodically changing refractive index structure. At the same time, due to the periodic refractive index change, the incident light will be diffracted. Optical signals of different wavelengths will be affected by diffraction to varying degrees when passing through the LPFG. The coupling effect and diffraction effect cause the optical signal to be attenuated or reflected at a specific wavelength, thereby achieving the filtering function. Long-period fiber gratings have low reflectivity for uncoupled wavelengths, allowing them to pass unimpeded, reducing losses. At the same time, they are sensitive to changes in environmental conditions and are transmissive band-stop filters, making them suitable for use as power supply filters.

[0026] In an optional embodiment of the present invention, the fiber grating hardware circuit unit is used to convert the filtered optical signal into an optical-electrical signal to obtain an electrical signal with external temperature information, amplify and filter the electrical signal with external temperature information, perform analog-to-digital conversion to obtain an external temperature digital signal, and store the external temperature digital signal.

[0027] The fiber Bragg grating hardware circuit unit includes a photoelectric conversion circuit, an amplification and filtering circuit, and a signal processing module.

[0028] like Figure 2 As shown, the signal processing module includes a DSP minimum control system, a power supply circuit, an analog-to-digital converter, a communication module and an external expansion storage circuit.

[0029] In the DSP minimum control system, the chip is the brain of the system, which controls the working process of each module; the crystal oscillator is the pulse of the system, responsible for the clock signal, and is the working benchmark of each module. It can generate clock signals of other frequencies through the phase-locked loop PLL. The reset signal is used to ensure that the system is in a known state when it starts, and can clear the status of various registers to ensure the normal initialization of the system; the core voltage of the DSP chip is 1.9V, and the I / O and Flash programming voltage is 3.3V. These voltages all need to be provided by the power supply, and the peripheral circuit working voltage is also provided by the power supply; the JTAG module is a tool for downloading programs, burning and debugging. In JTAG mode, CCS software can access all resources on the chip and perform online design of DSP.

[0030] The power supply circuit is a key step in the DSP application design. Accurate and stable power supply is the key to ensure the stable operation of each module. In the design of the power supply circuit, it is necessary to consider that the system requires voltages of different amplitudes when working, and is very sensitive to the voltage fluctuations of the power supply. Therefore, a reasonable power supply circuit design is of great significance for the normal operation of the power supply chip and the accurate achievement of the required output voltage value. In order to ensure the smooth operation of the system, the power supply circuit of the present invention must be reliable and stable. In the present invention, the core voltage of the F28335 processor is 1.9V, and the I / O interface voltage is 3.3V. At the same time, during the operation of the hardware circuit, a freeze may occur. Therefore, a reliable reset circuit is of great significance in circuit design. Taking into account factors such as input and output voltages and current power consumption, the dual-channel low-dropout voltage regulator TPS767D301 is selected as the chip of the system power supply circuit in this system. It can provide 3.3V and 1.9V voltages for the system, maintain the stability of the output voltage, and has the characteristics of fast transient response. It can achieve the high precision and low power consumption requirements of the power supply system. The circuit of the signal processing module is as follows Figure 3 shown.

[0031] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0032] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0033] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0034] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0035] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A fiber Bragg grating demodulation system based on an edge filter, characterized in that: It includes a fiber Bragg grating hardware unit and a fiber Bragg grating hardware circuit unit connected to the fiber Bragg grating hardware unit; The fiber Bragg grating hardware unit is provided with an edge filter; the fiber Bragg grating hardware unit is used to collect the optical signal with external temperature information, and perform wavelength selection on the optical signal with external temperature information to obtain the filtered optical signal; The fiber grating hardware circuit unit is used to convert the filtered optical signal into an optical signal to obtain an electrical signal with external temperature information, amplify and filter the electrical signal with external temperature information, perform analog-to-digital conversion to obtain an external temperature digital signal, and store the external temperature digital signal.

2. The fiber Bragg grating demodulation system based on edge filter according to claim 1, characterized in that: The fiber Bragg grating hardware unit includes a fiber coupler, a fiber Bragg grating sensor and an edge filter; the fiber coupler is used to transmit an externally generated optical signal to the fiber Bragg grating sensor, and collect an optical signal with external temperature information reflected by the fiber Bragg grating sensor; the fiber Bragg grating sensor is used to reflect the optical signal with external temperature information to the fiber coupler; the edge filter is used to select the wavelength of the reflected optical signal with external temperature information collected in the fiber coupler to obtain a filtered optical signal.

3. The fiber Bragg grating demodulation system based on edge filter according to claim 2, characterized in that: The fiber coupler uses a three-port polarization-maintaining circulator.

4. The fiber Bragg grating demodulation system based on edge filter according to claim 2, characterized in that: The edge filter uses long period fiber grating.

5. The fiber Bragg grating demodulation system based on edge filter according to claim 1, characterized in that: The fiber Bragg grating hardware circuit unit includes a photoelectric conversion circuit, an amplification and filtering circuit, and a signal processing module.

6. The edge filter-based fiber Bragg grating demodulation system according to claim 5, characterized in that: The signal processing module includes a DSP minimum control system, a power supply circuit, an analog-to-digital converter, a communication module and an external expansion storage circuit.

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