A Fiber Optic Sensor Based on Sine Wave Modulation

An optical fiber sensor, sine wave modulation technology, applied in the direction of using optical devices to transmit sensing components, can solve the problems of difficult to filter clean, variable frequency, unfavorable optical fiber sensors, etc., to achieve a wide range of applications, small phase detection error , Improve the effect of sensing accuracy

Inactive Publication Date: 2019-09-13
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, on the one hand, the high-frequency component itself will affect the phase detection of the cosine wave (the position of the zero-crossing point changes); The electrical characteristics are equivalent to capacitance, and the voltage at both ends cannot jump, so the falling edge of the sawtooth wave cannot be infinitely short) and the elasticity of the optical fiber itself and many other factors, the frequency is variable, and it is difficult to filter out cleanly; and , when using a filter, in addition to affecting the amplitude-frequency characteristics of the output signal, it will also affect the phase-frequency characteristics of the signal at the same time, that is, the phase of the filter will be affected near the cut-off frequency, which is very important for relying on phase changes. It is very disadvantageous for fiber optic sensors that measure changes in stress

Method used

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  • A Fiber Optic Sensor Based on Sine Wave Modulation
  • A Fiber Optic Sensor Based on Sine Wave Modulation
  • A Fiber Optic Sensor Based on Sine Wave Modulation

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Experimental program
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Effect test

Embodiment 1

[0026] Embodiment 1 Overall structure of the present invention

[0027] Such as figure 1 As shown, the overall structure of the present invention has, the pump source 1 (980nm laser, maximum output power is 1W) is connected with the 980nm end of the optical wavelength division multiplexer 2 (980 / 1550nm wavelength division multiplexer), and the optical wavelength division multiplexer The 1550nm end of the device 2 is connected to one end of the delay line adjustable optical fiber 11 (VDL-40-15-S9-1-FA type electric optical fiber delay line of Sichuan Yuxingguang Technology Co., Ltd.), and the other end of the delay line adjustable optical fiber 11 One end is connected with the input end of the first optical isolator 10 (1550nm polarization-independent optical isolator), and the control end of the delay line adjustable optical fiber 11 is connected with the output port of the level conversion chip 12, and the input port of the level conversion chip 12 is connected with the outp...

Embodiment 2

[0029] Embodiment 2 function transformation circuit

[0030] The structure of the function conversion circuit 24 is as follows: one end of the capacitor C3 is connected to the pin 12 of the trigonometric function converter U1 and one end of the resistor R2, and the other end of the capacitor C3 is used as the input terminal of the function conversion circuit 24, which is recorded as the port ACOS_in , connected to the output end of the photoelectric conversion circuit 23; the other end of the resistor R2 is grounded; the pins 2, 3, 4, 5, 8, 11, 13 of the trigonometric function converter U1 are grounded, and the pins 9, 10 are connected to the capacitor C2 One end is connected to -12V power supply, the other end of capacitor C2 is grounded; pin 6 of trigonometric function converter U1 is connected to pin 7, pin 16 is connected to +12V power supply and one end of capacitor C1, and the other end of capacitor C1 is grounded; The pin 1 of the trigonometric function converter U1 is ...

Embodiment 3

[0031] Embodiment 3 Adaptive Amplitude Normalization Circuit

[0032] Because the amplitude of the signal output by the function conversion circuit 24 is small, and is affected by multiple parameters in the optical path and the circuit, the size is indefinite, so the present invention designs an adaptive amplitude normalization circuit 25, which is used to convert the signal output by the function conversion circuit 24 The amplitude is normalized to the optimal size to further improve the accuracy of demodulation. The structure of the adaptive amplitude normalization circuit 25 is that one end of the capacitor C9 is connected to one end of the resistor R3 and the pin 3 of the chip U2, the other end of the resistor R3 is grounded, and the other end of the capacitor C9 is used as an adaptive amplitude normalization The input end of the circuit 25 is recorded as the port ADAPT_in, which is connected with the port ACOS_out of the function transformation circuit 24; the pin 1, the ...

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Abstract

The invention discloses an optical fiber sensor based on sine wave modulation, and belongs to the technical field of optical fiber sensors. The main structure is a pump source (1), an optical wavelength division multiplexer (3), an erbium doped fiber (3) and the like. According to the optical fiber sensor based on sine wave modulation, a sinusoidal signal is used as a modulation signal, high-frequency interference is not generated, and the invention has the characteristics of being more reliable in operation, high in sensing precision, wide in application range and the like.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensors, in particular to an optical fiber sensor based on sine wave modulation. Background technique [0002] Fiber Bragg grating (FBG) is widely used in the field of sensing technology due to its advantages of anti-electromagnetic interference, chemical resistance, small transmission loss, small size and light weight, and easy mass production. Especially in micro-stress detection, temperature detection in harsh environments, etc., fiber optic sensors have unique advantages. On the one hand, very small changes in temperature or stress can be detected sensitively by fiber Bragg gratings, with high sensitivity. On the one hand, in harsh environments such as humidity and strong electromagnetic interference, the fiber Bragg grating is not easy to damage, the working performance is not affected, and the signal transmission is not disturbed. These advantages make Bragg fiber grating sensors wide...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01D5/353
Inventor 汝玉星孙茂强于广安毕琳旭杨忠岗
Owner JILIN UNIV
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