CN112129229A - Quasi-distributed displacement measurement device and method based on photoelectric oscillator - Google Patents

Abstract

The invention provides a quasi-distributed displacement measurement device and method based on a photoelectric oscillator, which can be applied to the field of multipoint displacement measurement. The invention realizes the selection of different sensing positions by the wavelength division multiplexing technology; the mutual reference structure of the two photoelectric oscillators is realized by a polarization multiplexing technology. After a specific sensing position is selected by a wavelength division multiplexing technology, two photoelectric oscillators with the same structure are formed by utilizing a polarization multiplexing technology, wherein one photoelectric oscillator is a reference photoelectric oscillator, and the other photoelectric oscillator is a measurement photoelectric oscillator. The two photoelectric oscillators share the long optical fiber delay module through the polarization multiplexing technology to form a mutual reference structure. And (3) carrying out frequency discrimination on the microwave signals generated by the two photoelectric oscillators to obtain the frequency change of the microwave signals in the measuring photoelectric oscillators caused by the displacement so as to form a frequency demodulation mode of the displacement. The wavelength of a tunable laser module in the photoelectric oscillator is tuned and measured, and the sensing positions are sequentially selected, so that quasi-distributed measurement is realized.

Description

Quasi-distributed displacement measurement device and method based on photoelectric oscillator

technical field

The invention belongs to the field of multi-point displacement measurement, and in particular relates to a quasi-distributed displacement measurement device and method based on a photoelectric oscillator.

Background technique

In recent years, with the development of science and technology, scientific research, production and construction have put forward more and more urgent needs for long-range and high-precision distance measurement, such as: production, assembly and operation monitoring of large-scale equipment and components; the earth's gravitational field Research; the needs of my country's space exploration, navigation and other fields.

There are six traditional optical measurement methods of distance and related parameters, including light intensity measurement, triangulation, confocal measurement, Doppler measurement, time-of-flight method, and optical coherence method. The light intensity measurement method usually includes a light source and a detector, which is simple in structure and low in cost, but has the problem that multi-target reflection interference affects the measurement accuracy. Triangulation usually includes a light source and photodetector array, which has the advantage of low cost, but its measurement capability is affected by the density of the photodetector array. The measurement distance of the confocal measurement method is usually only a few millimeters, which cannot meet the long-distance measurement. Doppler measurements cannot measure the distance to the target to be measured. The time-of-flight method is usually implemented based on light pulses, which can measure the target distance and speed at the same time, but its measurement resolution and test accuracy are low. Optical coherence method is a precise method of distance measurement, using light wave phase interference distance measurement. The above-mentioned six methods of optically measuring distance and its related parameters have serious challenges in measuring the displacement of long-distance targets in real time and with high precision, especially in the field of multi-point displacement measurement, the above-mentioned measurement solutions cannot provide corresponding technical support.

At present, large-scale, high-precision distance measurement has been achieved based on photoelectric oscillators. This method is based on the principle of cumulative amplification, uses the idea of amplifying the physical quantity to be measured and then measures, and uses a lower resolution to achieve high-precision measurement. There are two technical difficulties in distance measurement based on photoelectric oscillators: one is that since the target to be measured is located in the feedback loop, the influence of environmental factors such as temperature on the feedback loop will reduce the measurement accuracy of the system; the other is that due to the principle of cumulative amplification, It is necessary to increase the frequency of the photoelectric oscillator to improve the measurement accuracy, so the frequency of the photoelectric oscillator is usually tens of GHz, and the real-time measurement of the frequency of the microwave signal of tens of GHz increases the difficulty and cost of demodulation; the third is the existence of multi-target distance and displacement measurement. difficulty. Therefore, the influence of environmental factors such as temperature on the measurement results of distance and its related parameters and the high frequency of oscillator oscillation signal, the measurement difficulty is high, the demodulation cost is high, the difficulty is high, and the measurement accuracy is low, and the realization of multi-target distance and displacement measurement is an urgent problem to be solved. technical difficulties.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problems in the prior art that it is difficult to exclude the influence of external factors such as temperature on the measurement results, and the demodulation difficulty is high in cost, high in difficulty, low in measurement accuracy, and difficult to achieve in multi-target distance and displacement measurement. A quasi-distributed displacement measurement device and method based on a photoelectric oscillator can effectively overcome the influence of environmental factors such as temperature on the measurement results of distance and related parameters, reduce measurement difficulty, demodulation difficulty and demodulation cost, and achieve multi-target distance and Displacement measurement can be used in various occasions for long-distance displacement measurement.

In order to achieve the above purpose of the invention, the quasi-distributed displacement measuring device based on the photoelectric oscillator of the present invention includes a reference photoelectric oscillator, a measuring photoelectric oscillator, a frequency discrimination module, a frequency counting module, a spectrum measurement module and a signal processing module. The output microwave signal of the photoelectric oscillator has two channels, one of which is the microwave signal output by the reference photoelectric oscillator and the microwave signal output by the measuring photoelectric oscillator are input into the frequency discrimination module at the same time, and the microwave signal output by the other reference photoelectric oscillator is input into the frequency spectrum. measurement module; after the frequency discrimination module outputs the intermediate frequency signal, the intermediate frequency signal is input into the frequency counting module, and the frequency counting module and the above-mentioned spectrum measurement module output the information to the signal processing module, wherein:

Reference photoelectric oscillator, used to eliminate the influence of external factors including temperature on the measurement results of distance and its related parameters;

Measuring optoelectronic oscillators for comparing with reference optoelectronic oscillators to obtain values to be measured;

The frequency discrimination module is used to discriminate the microwave signal from the reference photoelectric oscillator and the microwave signal from the measurement photoelectric oscillator;

The frequency counting module is used to measure the real-time frequency of the intermediate frequency signal output by the frequency discrimination module;

The spectrum measurement module is used to obtain the oscillation signal of the reference photoelectric oscillator and the frequency interval between adjacent modes;

The signal processing module is used to calculate the distance and related parameters through formula calculation of the spectrum information of the microwave signal from the spectrum measurement module and the real-time frequency of the intermediate frequency signal measured by the frequency counting module;

The invention uses the reference photoelectric oscillator and the measurement photoelectric oscillator, the initial oscillation frequencies of the two photoelectric oscillators are the same, the initial loop delays of the two photoelectric oscillators are equal, and the initial frequency difference of the two photoelectric oscillators is zero, The environmental factors such as temperature have the same influence on the output frequencies of the two photoelectric oscillators, so that the measurement results are not affected by environmental factors such as temperature; the demodulation signal of the present invention is the frequency difference of the microwave signals of the two photoelectric oscillators, and the frequency difference of the microwave signals is Much smaller than the oscillator's oscillating signal, the measurement difficulty is small, and the demodulation cost is low.

Further, the reference photoelectric oscillator includes a laser source module, an optical coupling module, an electro-optical modulation module 1, a polarization control module 1, a polarization beam combining module 01, a delay measurement module, a polarization beam combining module 02, a photoelectric detection module 1, a microwave Amplifying module 1, microwave filtering module 1, microwave coupling module 1, wherein:

A laser source module, tunable, for generating optical signals with continuously changing output wavelengths;

The optical coupling module is used to divide a beam of optical signals from the laser source module into two beams of optical signals, one beam is transmitted to the electro-optical modulation module 1, and the other beam is transmitted to the electro-optical modulation module 2;

The electro-optical modulation module 1 is used to modulate the optical signal input from the optical coupling module to the electro-optical modulation module 1;

The polarization control module 1 is used to control the polarization direction of the optical signal input to the input port S port of the polarization beam combining module 01 is the same as the main axis of the S port;

The polarization beam combining module 01 is used to combine the optical signal input from the input port S port and the optical signal input from the input port P port. The polarization beam combining module 01 has two input ports S port and P port, and the two input ports are main The polarization directions are perpendicular to each other;

Delay measurement module, used to select the measurement position and make the two photoelectric oscillators have the same delay;

The polarization beam combining module 02 is used to split the synthesized optical signal into two optical signals whose polarization directions are perpendicular to each other. One beam enters the photoelectric detection module 1 through the output port S port, and the other beam enters the measurement module through the output port P port. Photoelectric detection module 2 in the photoelectric oscillator;

The photoelectric detection module 1 is used to convert the optical signal from the output port S port of the polarization beam combining module 02 into a microwave signal;

The microwave amplifying module 1 is used to amplify the microwave signal from the photoelectric detection module 1;

The microwave filtering module 1 is used for filtering the microwave signal from the microwave amplifying module 1;

The microwave coupling module 1 is used to divide the microwave signal from the microwave filter module 1 into three beams, one beam is fed back to the electro-optic modulation module 1, the other beam is output to the frequency discrimination module, and the other beam is output to the spectrum measurement module;

The above-mentioned laser source module is tunable, and different displacement measurement positions are selected by tuning the wavelength of the optical signal to realize multi-target distance and displacement measurement;

The above-mentioned optical coupling module pigtail is a polarization-maintaining optical fiber, which ensures that the polarization direction of the optical signal input to the electro-optical modulation module 1 is the same as its main axis, thereby reducing polarization loss;

Further, the measurement photoelectric oscillator includes a laser source module, an optical coupling module, an electro-optical modulation module 2, a polarization control module 2, a polarization beam combining module 01, a delay measurement module, a polarization beam combining module 02, a photoelectric detection module 2, a microwave Amplifying module 2, microwave filtering module 2, microwave coupling module 2, wherein:

A laser source module, tunable, for generating optical signals with continuously changing output wavelengths;

The optical coupling module is used to divide a beam of optical signals from the laser source module into two beams of optical signals, one beam is transmitted to the electro-optical modulation module 1, and the other beam is transmitted to the electro-optical modulation module 2;

The electro-optical modulation module 2 is used to modulate the optical signal input from the optical coupling module to the electro-optical modulation module 2;

The polarization control module 2 is used to control the polarization direction of the optical signal input to the input port P of the polarization beam combining module 01 is the same as the main axis of the P port;

The polarization beam combining module 01 is used to combine the optical signal input from the P port of the input port and the optical signal input from the input port S port. The polarization beam combining module 01 has two input ports S ports and P ports, and one output port C port , the polarization directions of the main axes of the two input ports are perpendicular to each other, and the polarization beam combining module 01 is output to the fiber delay module 1 through the output port C port;

Delay measurement module, used to select the measurement position and make the two photoelectric oscillators have the same delay;

The polarization beam combining module 02 is used to split the optical signal from the input port C port of the polarization beam combining module 02 into two beams of optical signals whose polarization directions are perpendicular to each other, and one beam enters the reference photoelectric oscillator through the output port S port. Photoelectric detection module 1, another beam enters photoelectric detection module 2 through the output port P port;

The photoelectric detection module 2 is used to convert the optical signal from the output port P of the polarization beam combining module 02 into a microwave signal;

The microwave amplifying module 2 is used to amplify the microwave signal from the photoelectric detection module 2;

The microwave filtering module 2 is used for filtering the microwave signal from the microwave amplifying module 2;

The microwave coupling module 2 is used to divide the microwave signal from the microwave filter module 2 into two beams, one beam is fed back to the electro-optic modulation module 2, and the other beam is output to the frequency discrimination module;

The above-mentioned laser source module is tunable, and different displacement measurement positions are selected by tuning the wavelength of the optical signal to realize multi-target distance and displacement measurement;

The above-mentioned optical coupling module pigtail is a polarization-maintaining fiber, which ensures that the polarization direction of the light input to the electro-optical modulation module 2 is the same as its main axis, thereby reducing polarization loss;

Further, the delay measurement module includes an optical fiber delay module and a displacement measurement position. There are n+1 optical fiber delay modules and n displacement measurement positions, and n is a natural number. The above-mentioned n+1 optical fiber delay modules and n displacement measurement positions. The positions are alternately connected, and the n+1th fiber delay module transmits the optical signal to the input port C port of the polarization beam combining module 02, where:

Optical fiber delay module, used to provide energy storage medium for reference optoelectronic oscillator and measurement optoelectronic oscillator;

When the wavelength of the optical signal output from the optical fiber delay module 1 is consistent with the working wavelength of the wavelength division multiplexing module in the displacement measurement position, the displacement measurement position is selected.

The selected displacement measurement position to provide a measurement position;

The rest of the displacement measurement positions that are not selected are regarded as an optical fiber delay module;

Further, taking the displacement measurement position 1 as an example, the structure of the other displacement measurement positions is the same as that of the displacement measurement position 1; the displacement measurement position 1 includes a wavelength division multiplexing module 11, a polarization beam combining module 11, a reference optical delay module 1, and a polarization control module. 11. Displacement sensing module 1, polarization control module 12, polarization beam combining module 12, wavelength division multiplexing module 12, wherein:

The wavelength division multiplexing module 11 is used to input the optical signal from the optical fiber delay module to the polarization beam combining module 11 through the input port C port of the polarization beam combining module 11;

The polarization beam combining module 11 is used to divide the optical signal from the input port C port of the polarization beam combining module 11 into two beams, one of which is input to the reference optical delay module 1 through the output port S port, and the other beam is passed through the output port. The P port is input to the displacement sensing module 1;

Refer to the optical delay module 1, which is used to ensure that the initial feedback loop delays of the two photoelectric oscillators are the same;

The polarization control module 11 is used to control the polarization direction of the optical signal input to the input port S port of the polarization beam combining module 12 is the same as the main axis of the S port;

Displacement sensing module 1, which is used to convert the measured displacement and real-time distance into the optical delay change of the optoelectronic feedback loop in the optoelectronic oscillator;

The polarization control module 12 is used for controlling the polarization direction of the optical signal input to the input port P port of the polarization beam combining module 12 to be the same as the main axis of the P port;

The polarization beam combining module 12 is used to combine the optical signal input from the input port P port of the polarization beam combining module 12 and the optical signal input from the input port S port of the polarization beam combining module 12. The polarization beam combining module 12 has two inputs Port S port and P port, one output port C port, the polarization directions of the main axes of the two input ports are perpendicular to each other, and the polarization beam combining module 12 outputs the optical signal to the wavelength division multiplexing module 12 through the output port C port;

The wavelength division multiplexing module 12 inputs the optical signal from the output port C port of the polarization beam combining module 12 into the next optical fiber delay module;

The structure of other displacement measurement positions is the same as that of displacement measurement position 1;

The above-mentioned reference optical delay module 1 is used to ensure that the initial feedback loop delay of the two photoelectric oscillators is the same, and to eliminate the influence of the loop delay on the measurement result;

The present invention also provides a quasi-distributed displacement measurement method based on an optoelectronic oscillator, comprising the following steps:

A. In the reference photoelectric oscillator, the laser source module is tunable to generate an optical signal that continuously changes the output wavelength and input the optical signal into the optical coupling module. The optical coupling module divides the optical signal into two beams, one of which is input to the measurement The electro-optical modulation module 2 of the photoelectric oscillator, another beam of optical signal is input to the electro-optical modulation module 1; the optical signal input to the electro-optical modulation module 1 is modulated by the microwave signal in the electro-optical modulation module 1, and the optical signal modulated by the microwave signal is controlled by polarization Module 1 inputs the input port S port of the polarization beam combining module 01. The polarization beam combining module 01 combines the optical signals from the input port S port and the input port P port, and the combined optical signal is output by the polarization beam combining module 01. Port C is output to the optical fiber delay module 1, and the optical fiber delay module 1 transmits the optical signal to the displacement measurement position. The wavelength division multiplexing module of each displacement measurement position has different working wavelengths. When the wavelength is the same as the wavelength of the optical signal transmitted to the displacement measurement position, the displacement measurement position is selected as the measurement position, and the other displacement measurement positions are equivalent to an optical fiber delay module. The optical signal output by the optical fiber delay module 1 passes through the selected displacement measurement position. After the wavelength division multiplexing module in , the optical signal is divided into two beams through the input port C port of the polarization beam combining module, and one of the optical signals is transmitted through the output port S port of the polarization beam combining module. Referring to the optical delay module, another optical signal is transmitted to the displacement sensing module through the output port P of the polarization beam combining module; the optical signal transmitted to the reference optical delay module passes through the polarization control module and then passes through the input port S of the polarization beam combining module The port is transmitted into the polarization beam combining module, and the optical signal transmitted into the displacement sensing module passes through the displacement sensing module and then enters the polarization beam combining module through the input port P port of the polarization beam combining module; the polarization beam combining module will come from the input port S port After combining with the optical signal of the input port P port, it is transmitted to the wavelength division multiplexing module through the input port C port of the polarization beam combining module. The optical signal transmitted by the wavelength division multiplexing module passes through the optical fiber delay module and the unselected displacement measurement position. Then, through the input port C port of the polarization beam combining module 02 through an optical fiber delay module, the polarization beam combining module 02 divides the optical signal from the input port C port into two beams, and one of the optical signals passes through the polarization beam combining module 02. The output port P port is transmitted to the photoelectric detection module 2 for measuring the photoelectric oscillator, and another optical signal is transmitted to the photoelectric detection module 1 through the output port S port of the polarization beam combining module 02; the photoelectric detection module 1 will receive the received After the optical signal is converted into a microwave signal, it is amplified by the microwave amplifying module 1 and filtered by the microwave filtering module 1. The filtered microwave signal is divided into two beams by the microwave coupling module 1. One of the microwave signals is transmitted to the frequency discrimination module, and the other is transmitted to the frequency discrimination module. A beam of microwave signal is transmitted to the electro-optical modulation module 1 to form an optoelectronic feedback loop of the reference optoelectronic oscillator;

B. In the measurement of photoelectric oscillator, the laser source module can be tuned to generate an optical signal that continuously changes the output wavelength within a certain range and input the optical signal into the optical coupling module. The optical coupling module divides the optical signal into two beams, one of which is The optical signal is input to the electro-optical modulation module 1 of the reference photoelectric oscillator, and another beam of optical signal is input to the electro-optical modulation module 2; the optical signal input to the electro-optical modulation module 2 is modulated by the microwave signal in the electro-optical modulation module 2, and the light modulated by the microwave signal The signal is input to the input port P port of the polarization beam combining module 01 through the polarization control module 2, and the polarization beam combining module 01 combines the optical signals from the input port S port and the input port P port, and the combined optical signal is subjected to polarization beam combining. The output port C of module 01 is output to the optical fiber delay module 1, and the optical fiber delay module 1 transmits the optical signal to the displacement measurement position. The wavelength division multiplexing module of each displacement measurement position has different working wavelengths. When the wavelength of the multiplexing module is the same as the wavelength of the optical signal transmitted into the displacement measurement position, the displacement measurement position is selected as the measurement position, and the other displacement measurement positions are equivalent to an optical fiber delay module. The optical signal output by the optical fiber delay module 1 is selected by After the wavelength division multiplexing module in the displacement measurement position, the polarization beam combining module divides the optical signal into two beams through the input port C port of the polarization beam combining module, and one of the optical signals passes through the output port of the polarization beam combining module. The S port is sent to the reference optical delay module, and another optical signal is sent to the displacement sensing module through the P port of the output port of the polarization beam combining module; the optical signal sent to the reference optical delay module passes through the polarization control module and then passes through the polarization beam combining module. The S port of the input port is transmitted to the polarization beam combining module, and the optical signal transmitted to the displacement sensing module passes through the displacement sensing module and then enters the polarization beam combining module through the input port P port of the polarization beam combining module; The optical signals of the input port S port and the input port P port are combined and transmitted to the wavelength division multiplexing module through the input port C port of the polarization beam combining module. The optical signal transmitted by the wavelength division multiplexing module passes through the fiber delay module and is not selected. After the displacement measurement position of 1, the optical signal from the input port C is divided into two beams by the polarization beam combining module 02 through the input port C port of the polarization beam combining module 02 after passing through an optical fiber delay module n+1, one of which is The optical signal is transmitted to the photoelectric detection module 1 of the reference photoelectric oscillator through the output port S port of the polarization beam combining module 02, and another optical signal is transmitted to the photoelectric detection module 2 through the output port P port of the polarization beam combining module 02; The photoelectric detection module 2 converts the received optical signal into a microwave signal, which is amplified by the microwave amplifying module 2 and filtered by the microwave filtering module 2. The filtered microwave signal is divided into two beams by the microwave coupling module 2, and one beam of microwave The signal is transmitted to the frequency discrimination module, and another beam of microwave signal is transmitted to the electro-optical modulation module 2 to form an optoelectronic feedback loop for measuring the optoelectronic oscillator;

In step A and step B, the optical coupling module adjusts the polarization direction of the optical signal generated by the laser source module to be the same as the main axis of the electro-optic modulation module 1 and the electro-optic modulation module 2 respectively, so that the polarization loss is minimized; at the same time, this structure can avoid electro-optic modulation. The optical signals output by module 1 and electro-optic modulation module 2 are coherent;

C. a bundle of microwave signals transmitted to the frequency discrimination module in the above-mentioned steps A and a bundle of microwave signals transmitted to the frequency discrimination module in the above-mentioned steps B are subjected to frequency discrimination in the frequency discrimination module, and the frequency discrimination module obtains the intermediate frequency signal after frequency discrimination , the frequency discrimination module inputs the intermediate frequency signal into the frequency counting module, and the frequency counting module obtains the real-time frequency of the intermediate frequency signal and outputs the real-time frequency f _IF of the intermediate frequency signal to the signal processing module; One microwave signal of the measurement module obtains the oscillation frequency f ₁ of the reference photoelectric oscillator and the frequency interval f _FSR between the adjacent modes of the reference photoelectric oscillator and then transmits it to the signal processing module. The signal processing module is based on the real-time frequency of the intermediate frequency signal obtained above. Calculate f _IF , the oscillation frequency f ₁ of the reference photoelectric oscillator, and the frequency interval f _FSR between adjacent modes of the reference photoelectric oscillator to obtain the initial distance, displacement, and real-time distance of the target to be measured in the displacement measurement module.

The intermediate frequency signal output by the frequency discrimination module is only affected by the displacement in the displacement sensing module 1, and the signal processing module uses electronic technology to demodulate to improve the demodulation speed;

The reference photoelectric oscillator has the same structure as the measurement photoelectric oscillator. Among them, the feedback loops of the two optoelectronic oscillators have the same length, and the fiber delay module and the displacement measurement position ranging from hundreds of meters to several kilometers are shared by the two optoelectronic oscillators; the reference optical delay module 1 is used to ensure that the two optoelectronic The initial feedback loop delay of the oscillator is the same; the microwave filter module 1 and the microwave filter module 2 are both band-pass microwave filters, and their key indicators such as center frequency and 3dB bandwidth are the same. Since the structures of the two photoelectric oscillators are the same, the initial oscillation frequencies of the two photoelectric oscillators are the same, and the key indicators such as the center frequency and bandwidth of the microwave filter module 1 and the microwave filter module 2 are the same; therefore, environmental factors such as temperature affect the two photoelectric oscillators. The influence of the oscillator frequency is the same, thereby eliminating the influence of environmental factors such as temperature on the measurement results.

Further, step C includes that the spectrum measurement module measures the spectrum of the microwave signal transmitted by the microwave coupling module 1 in the reference photoelectric oscillator, and transmits the spectrum information to the signal processing module to obtain the loop delay τ ₀ of the reference photoelectric oscillator, The initial loop length L ₀ , and the initial distance L' of the target to be measured in the displacement sensing module in the displacement measurement position; the loop delay τ ₀ =1/f _FSR , the loop length L ₀ =(cτ ₀ )/n , the initial distance L′=L ₀ of the target to be measured in the displacement measurement module; wherein, c represents the propagation speed of light in vacuum, and n represents the refractive index;

其中，c表示光在真空中的传播速度，n表示折射率；Further, step C includes, the signal processing module determines the displacement ΔL of the target to be measured in the displacement measurement module, the displacement ΔL of the target to be measured in the displacement measurement module and the output of the frequency discrimination module by the real-time frequency of the intermediate frequency signal measured by the frequency counting module. The relationship between the frequency of the intermediate frequency signal; then the displacement of the target to be measured in the displacement measurement module ΔL=L ₀ f _IF /f ₁ , the relationship between the displacement of the target to be measured in the displacement measurement module and the frequency of the intermediate frequency signal output by the frequency discrimination module is:

Among them, c represents the propagation speed of light in vacuum, and n represents the refractive index;

The invention realizes quasi-distributed displacement measurement based on wavelength division multiplexing technology; uses polarization multiplexing technology to make two photoelectric oscillators share a long photoelectric transmission link, realizes mutual reference structure, and eliminates the influence of external factors such as temperature on the displacement measurement results . The high-precision displacement measurement is realized by using the low-phase-noise high-frequency microwave signal generated by the photoelectric oscillator. The frequency difference of the microwave signals of the two photoelectric oscillators is used as the displacement demodulation quantity, which improves the measurement speed and reduces the demodulation cost. Finally, the displacement measurement based on photoelectric oscillator, which is temperature-insensitive, quasi-distributed, fast in measurement speed and high in measurement accuracy is realized.

Description of drawings

Fig. 1 is the principle diagram of the quasi-distributed displacement measuring device based on photoelectric oscillator;

Fig. 2 is the schematic diagram of displacement measurement position 1;

Fig. 3 is the schematic diagram of displacement measurement position 2;

Fig. 4 is the schematic diagram of displacement measurement position n;

Detailed ways

The specific embodiments of the present invention are described below with reference to the accompanying drawings, so that those skilled in the art can better understand the present invention. It should be noted that, in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

FIG. 1 is a schematic diagram of a quasi-distributed displacement measuring device based on a photoelectric oscillator of the present invention. As shown in Figure 1, the present invention includes a reference photoelectric oscillator, a measurement photoelectric oscillator, a frequency discrimination module, a frequency counting module, a spectrum measurement module and a signal processing module; the reference photoelectric oscillator includes a laser source module, an optical coupling module, Electro-optic modulation module 1, polarization control module 1, polarization beam combining module 01, fiber delay module 1, n+1 fiber delay modules, n displacement measurement positions, polarization beam combining module 02, photoelectric detection module 1, microwave amplification module 1 , microwave filter module 1, microwave coupling module 1; the measuring photoelectric oscillator includes a laser source module, an optical coupling module, an electro-optical modulation module 2, a polarization control module 2, a polarization beam combining module 01, an optical fiber delay module 1, n+1 fiber delay modules, n displacement measurement positions, polarization beam combining module 02 , photoelectric detection module 2 , microwave amplifying module 2 , microwave filtering module 2 , and microwave coupling module 2 .

In this embodiment, the laser generates an optical signal, and the optical signal is input into two electro-optical modulators through a 3dB optical coupler. The optical signal modulated by the electro-optical modulator passes through the polarization controller and is input into the polarization beam combiner; the polarization beam combiner combines the beams. The optical signal continues to transmit through the ordinary single-mode fiber several kilometers long, and then passes through the wavelength division multiplexer in the displacement measurement position, and then is transmitted to the polarization beam combiner through the wavelength division multiplexer, and the polarization beam combiner divides the optical signal into One beam of split light is passed into the optical delay line, and the other beam is passed into the displacement sensor; the optical signal passed into the optical delay line continues to pass into one polarization controller, and the incoming displacement sensor continues to pass into another polarization controller , the polarization beam combiner combines the optical signals from the two polarization controllers, the combined optical signal is transmitted to the single-mode fiber through the wavelength division multiplexer, and the optical signal transmitted through the single-mode fiber passes through the polarization beam combiner , the polarization beam combiner splits the incoming optical signal into a photodetector, and the photodetector converts the optical signal into a microwave signal; the microwave signal is amplified by a radio frequency/microwave broadband low-noise amplifier, filtered by a microwave bandpass filter, And through the microwave/RF coupler, the microwave/RF coupler divides the microwave signal into two channels, one is output to the broadband double-balanced mixer, the other is fed back to the electro-optical modulator, and finally forms an optoelectronic feedback loop of two electrical oscillators The microwave/RF coupler of the reference photoelectric oscillator divides the microwave signal into three channels, one is output to the electro-optical modulator, the other is output to the broadband double-balanced mixer, and the other is output to the spectrum measurer; the above-mentioned broadband double-balanced mixer The frequency counter transmits the frequency of the real-time intermediate frequency signal to the DSP digital signal processor, and the spectrum measurer transmits the spectrum information to the DSP digital signal processor.

Assuming that the spectrum measuring instrument measures the spectrum of the microwave signal coupled out by the microwave/RF coupler in the reference photoelectric oscillator, the oscillation frequency is f ₁ , and the frequency interval between adjacent modes is f _FSR , then the loop delay is τ ₀ = 1/f _FSR , the loop length is L ₀ =(cτ ₀ )/n, and the initial distance of the target to be measured is L′=L ₀ ; where c represents the propagation speed of light in vacuum, and n represents the refractive index.

其中，L₀表示环路长度，f₁表示参考光电振荡器的频谱显示的振荡频率，c表示光在真空中的传播速度，n表示折射率。Assuming that the real-time frequency of the intermediate frequency signal output from the broadband double-balanced mixer measured by the frequency counter is f _IF , the displacement of the target to be measured in the displacement measurement module is ΔL=L ₀ f _IF /f ₁ , and the target to be measured in the displacement measurement module is ΔL=L 0 f IF /f 1 . The relationship between the displacement and the frequency of the IF signal output by the frequency discrimination module is:

Among them, L ₀ represents the loop length, f ₁ represents the oscillation frequency displayed by the spectrum of the reference optoelectronic oscillator, c represents the propagation speed of light in vacuum, and n represents the refractive index.

The DSP digital signal processor obtains the real-time distance of the target to be measured as L=L′+ΔL according to the above-obtained initial distance of the target to be measured and the displacement of the target to be measured.

2 to 4 are schematic diagrams of displacement measurement positions of the present invention. As shown in Figures 2 to 4, the displacement measurement position includes a wavelength division multiplexing module, a polarization beam combining module, a reference optical delay module, a polarization control module, a displacement sensing module, a polarization control module, a polarization beam combining module, and a wavelength division multiplexing module. Use modules.

In this embodiment, the single-mode fiber transmits the optical signal into the wavelength division multiplexer, and the wavelength division multiplexer at each displacement measurement position has different working wavelengths. When the wavelength of the incoming optical signal is consistent with the working wavelength of the wavelength division multiplexer When the wavelength division multiplexer transmits the optical signal into the input port C port of the polarization beam combiner, the polarization beam combiner divides the optical signal into two beams, one of which is transmitted through the output port S port of the polarization beam combiner. The incident light delay line and the optical delay line are transmitted to the input port S port of the polarization beam combiner through the polarization controller; another optical signal is transmitted to the displacement sensor through the output port P port of the polarization beam combiner, and the displacement sensor is passed through the polarization controller. The input port P port of the polarization beam combiner; the polarization beam combiner combines the optical signal of the input port S port with the optical signal of the input port P port into a beam and transmits it to the wavelength division complex through the output port C of the polarization beam combiner. When the wavelength of the incoming optical signal is inconsistent with the working wavelength of the wavelength division multiplexer, the single-mode fiber transmits the optical signal to the wavelength division multiplexer, and the wavelength division multiplexer transmits the optical signal to the next wavelength division multiplexer. The wavelength division multiplexer then transmits the optical signal to the single-mode fiber.

Claims (9)

1. based on the quasi-distributed displacement measuring device of photoelectric oscillator, it is characterized in that: comprise reference photoelectric oscillator, measuring photoelectric oscillator, frequency discrimination module, frequency counting module, spectrum measurement module and signal processing module, described reference photoelectric oscillation The output microwave signal of the device is two channels, one of the microwave signals and the output microwave signal of the measuring photoelectric oscillator are input into the frequency discrimination module at the same time, and the other microwave signal is input to the spectrum measurement module; after the frequency discrimination module outputs the intermediate frequency signal, the intermediate frequency signal In the input frequency counting module, the frequency counting module and the above-mentioned spectrum measurement module output information to the signal processing module. 2. The quasi-distributed displacement measuring device based on an optoelectronic oscillator according to claim 1, wherein the reference optoelectronic oscillator comprises a laser source module, an optical coupling module, an electro-optical modulation module 1, a polarization control module 1, Polarization beam combining module 01, delay measurement module, polarization beam combining module 02, photoelectric detection module 1, microwave amplifying module 1, microwave filtering module 1, microwave coupling module 1, the polarization beam combining module 01 is provided with two input ports S port, P port and an output port C port, the polarization beam combining module 02 is provided with an input port C port and two output ports S port, P port; the laser module generates an optical signal input light with a wavelength of λ ₁ Coupling module, the optical coupling module divides the optical signal into two beams, one of which is input to the electro-optical modulation module 1, and the other optical signal is input to the electro-optical modulation module 2 for measuring the photoelectric oscillator; the optical signal input to the electro-optical modulation module 1 is in the The electro-optic modulation module 1 is modulated by a microwave signal; the optical signal modulated by the microwave signal is transmitted to the polarization control module 1, and the polarization control module 1 is transmitted to the input port S port of the polarization beam combining module 01, and then the light of the polarization beam combining module 01 is transmitted. The signal is transmitted to the delay measurement module through the output port C port of the polarization beam combining module 01, and the delay measurement module transmits the optical signal into the input port C port of the polarization beam combining module 02, and the optical signal is transmitted through the output port S port of the polarization beam combining module 02. The photoelectric detection module 1 converts the optical signal into a microwave signal. The microwave signal is amplified by the microwave amplifying module 1 and then filtered by the microwave filtering module 1, and passes through the microwave coupling module 1. The microwave coupling module 1 divides the microwave signal into There are two beams, one of which is introduced into the frequency discrimination module, and the other is fed back to the electro-optical modulation module 1 to form an optoelectronic feedback loop of the reference optoelectronic oscillator. 3. The quasi-distributed displacement measuring device based on an optoelectronic oscillator according to claim 1, wherein the measuring optoelectronic oscillator comprises a laser source module, an optical coupling module, an electro-optical modulation module 2, a polarization control module 2, Polarization beam combining module 01, delay measurement module, polarization beam combining module 02, photoelectric detection module 2, microwave amplifying module 2, microwave filtering module 2, microwave coupling module 2, the polarization beam combining module 01 is provided with two input ports S port, P port and an output port C port, the polarization beam combining module 02 is provided with an input port C port and two output ports S port, P port; the laser module generates an optical signal input light with a wavelength of λ ₁ Coupling module, the optical coupling module divides the optical signal into two beams, one of which is input into the electro-optical modulation module 1 for measuring the photoelectric oscillator, and the other optical signal is input into the electro-optical modulation module 2; the optical signal input into the electro-optical modulation module 2 is in The electro-optical modulation module 2 is modulated by the microwave signal; the optical signal modulated by the microwave signal is transmitted to the polarization control module 2, and the polarization control module 2 is transmitted to the input port P port of the polarization beam combining module 01, and then the light of the polarization beam combining module 01 is transmitted. The signal is transmitted to the delay measurement module through the output port C of the polarization beam combining module 01, and the delay measurement module transmits the optical signal into the input port C port of the polarization beam combining module 02 and then transmits the optical signal through the output port P of the polarization beam combining module 02. The signal is transmitted to the photoelectric detection module 2, and the photoelectric detection module 2 converts the optical signal into a microwave signal. The microwave signal is amplified by the microwave amplifying module 2 and then filtered by the microwave filtering module 2, and passes through the microwave coupling module 2. The microwave coupling module 2 converts the microwave signal It is divided into two beams, one of which is introduced into the frequency discrimination module, and the other is fed back to the electro-optical modulation module 1 to form an optoelectronic feedback loop of the reference optoelectronic oscillator. 4. The quasi-distributed displacement measurement device based on photoelectric oscillator according to claim 2 or 3, wherein the delay measurement module comprises an optical fiber delay module and a displacement measurement position, and the optical fiber delay module has n+1, There are n displacement measurement positions, and n is a natural number. The above n+1 fiber delay modules are alternately connected to n displacement measurement positions, and the n+1th fiber delay module transmits the optical signal to the input port C of the polarization beam combining module 02 port. 5. The quasi-distributed displacement measurement device based on an optoelectronic oscillator according to claim 2 or 3, wherein the displacement measurement position 1 comprises a wavelength division multiplexing module 11, a polarization beam combining module 11, a reference optical delay Module 1, polarization control module 11, displacement sensing module 1, polarization control module 12, polarization beam combining module 12, wavelength division multiplexing module 12, the polarization beam combining module 11 is provided with an input port C port and two outputs port S port, P port, the polarization beam combining module 12 is provided with two input ports S port, P port and one output port C port, the optical fiber delay module transmits the optical signal into the wavelength division multiplexing module 11, the wave The multiplexing module 11 transmits the optical signal to the input port C port of the polarization beam combining module 11 , and the polarization beam combining module 11 divides the optical signal into two beams, one of which passes through the output port S port of the polarization beam combining module 11 . The incoming reference light delay module 1 and the reference light delay module 1 are passed into the input port S port of the polarization beam combining module 12 through the polarization control module 11 ; another optical signal is transmitted through the output port P port of the polarization beam combining module 11 . Into the displacement sensing module 1, the displacement sensing module 1 is transmitted to the input port P port of the polarization beam combining module 12 through the polarization control module 12; A bundle of signals is synthesized and transmitted to the wavelength division multiplexing module 12 through the output port C port of the polarization beam combining module 12, and the wavelength division multiplexing module 12 transmits the optical signal to the next optical fiber delay module. The structure of the displacement measurement position, Connections are the same. 6. The quasi-distributed displacement measurement method based on photoelectric oscillator, is characterized in that: comprise the following steps: A. In the reference photoelectric oscillator, the laser source module is tunable to generate an optical signal that continuously changes the output wavelength and input the optical signal into the optical coupling module. The optical coupling module divides the optical signal into two beams, one of which is input to the measurement The electro-optical modulation module 2 of the photoelectric oscillator, another beam of optical signal is input to the electro-optical modulation module 1; the optical signal input to the electro-optical modulation module 1 is modulated by the microwave signal in the electro-optical modulation module 1, and the optical signal modulated by the microwave signal is controlled by polarization Module 1 inputs the input port S port of the polarization beam combining module 01. The polarization beam combining module 01 combines the optical signals from the input port S port and the input port P port, and the combined optical signal is output by the polarization beam combining module 01. Port C is output to the optical fiber delay module 1, and the optical fiber delay module 1 transmits the optical signal to the displacement measurement position. The wavelength division multiplexing module of each displacement measurement position has different working wavelengths. When the wavelength is the same as the wavelength of the optical signal transmitted to the displacement measurement position, the displacement measurement position is selected as the measurement position, and the other displacement measurement positions are equivalent to an optical fiber delay module. The optical signal output by the optical fiber delay module 1 passes through the selected displacement measurement position. After the wavelength division multiplexing module in , the optical signal is divided into two beams through the input port C port of the polarization beam combining module, and one of the optical signals is transmitted through the output port S port of the polarization beam combining module. Referring to the optical delay module, another optical signal is transmitted to the displacement sensing module through the output port P of the polarization beam combining module; the optical signal transmitted to the reference optical delay module passes through the polarization control module and then passes through the input port S of the polarization beam combining module The port is transmitted into the polarization beam combining module, and the optical signal transmitted into the displacement sensing module passes through the displacement sensing module and then enters the polarization beam combining module through the input port P port of the polarization beam combining module; the polarization beam combining module will come from the input port S port After combining with the optical signal of the input port P port, it is transmitted to the wavelength division multiplexing module through the input port C port of the polarization beam combining module. The optical signal transmitted by the wavelength division multiplexing module passes through the remaining fiber delay modules and the unselected displacement After measuring the position, through an optical fiber delay module through the input port C port of the polarization beam combining module 02, the polarization beam combining module 02 divides the optical signal from the input port C port into two beams, and one of the optical signals passes through the polarization beam combining. The output port P port of the module 02 is transmitted to the photoelectric detection module 2 for measuring the photoelectric oscillator, and another optical signal is transmitted to the photoelectric detection module 1 through the output port S port of the polarization beam combining module 02; the photoelectric detection module 1 will receive The received optical signal is converted into a microwave signal, amplified by the microwave amplifying module 1, and filtered by the microwave filtering module 1. The filtered microwave signal is divided into two beams by the microwave coupling module 1, and one of the microwave signals is transmitted to the frequency discrimination module. , another beam of microwave signal is transmitted to the electro-optical modulation module 1 to form an optoelectronic feedback loop of the reference optoelectronic oscillator; B. In the measurement of photoelectric oscillator, the laser source module can be tuned to generate an optical signal that continuously changes the output wavelength within a certain range and input the optical signal into the optical coupling module. The optical coupling module divides the optical signal into two beams, one of which is The optical signal is input to the electro-optical modulation module 1 of the reference photoelectric oscillator, and another beam of optical signal is input to the electro-optical modulation module 2; the optical signal input to the electro-optical modulation module 2 is modulated by the microwave signal in the electro-optical modulation module 2, and the light modulated by the microwave signal The signal is input to the input port P port of the polarization beam combining module 01 through the polarization control module 2, and the polarization beam combining module 01 combines the optical signals from the input port S port and the input port P port, and the combined optical signal is subjected to polarization beam combining. The output port C of module 01 is output to the optical fiber delay module 1, and the optical fiber delay module 1 transmits the optical signal to the displacement measurement position. The wavelength division multiplexing module of each displacement measurement position has different working wavelengths. When the wavelength of the multiplexing module is the same as the wavelength of the optical signal transmitted into the displacement measurement position, the displacement measurement position is selected as the measurement position, and the other displacement measurement positions are equivalent to an optical fiber delay module. The optical signal output by the optical fiber delay module 1 is selected by After the wavelength division multiplexing module in the displacement measurement position, the polarization beam combining module divides the optical signal into two beams through the input port C port of the polarization beam combining module, and one of the optical signals passes through the output port of the polarization beam combining module. The S port is sent to the reference optical delay module, and another optical signal is sent to the displacement sensing module through the P port of the output port of the polarization beam combining module; the optical signal sent to the reference optical delay module passes through the polarization control module and then passes through the polarization beam combining module. The S port of the input port is transmitted to the polarization beam combining module, and the optical signal transmitted to the displacement sensing module passes through the displacement sensing module and then enters the polarization beam combining module through the input port P port of the polarization beam combining module; The optical signals of the input port S port and the input port P port are combined and transmitted to the wavelength division multiplexing module through the input port C port of the polarization beam combining module. The optical signal transmitted by the wavelength division multiplexing module passes through the fiber delay module and is not selected. After the displacement measurement position of 1, the optical signal from the input port C is divided into two beams by the polarization beam combining module 02 through the input port C port of the polarization beam combining module 02 after passing through an optical fiber delay module n+1, one of which is The optical signal is transmitted to the photoelectric detection module 1 of the reference photoelectric oscillator through the output port S port of the polarization beam combining module 02, and another optical signal is transmitted to the photoelectric detection module 2 through the output port P port of the polarization beam combining module 02; The photoelectric detection module 2 converts the received optical signal into a microwave signal, which is amplified by the microwave amplifying module 2 and filtered by the microwave filtering module 2. The filtered microwave signal is divided into two beams by the microwave coupling module 2, and one beam of microwave The signal is transmitted to the frequency discrimination module, and another beam of microwave signal is transmitted to the electro-optical modulation module 2 to form an optoelectronic feedback loop for measuring the optoelectronic oscillator; C. a bundle of microwave signals transmitted to the frequency discrimination module in the above-mentioned steps A and a bundle of microwave signals transmitted to the frequency discrimination module in the above-mentioned steps B are subjected to frequency discrimination in the frequency discrimination module, and the frequency discrimination module obtains the intermediate frequency signal after frequency discrimination , the frequency discrimination module inputs the intermediate frequency signal into the frequency counting module, and the frequency counting module obtains the real-time frequency of the intermediate frequency signal and outputs the real-time frequency f _IF of the intermediate frequency signal to the signal processing module; One microwave signal of the measurement module obtains the oscillation frequency f ₁ of the reference photoelectric oscillator and the frequency interval f _FSR between the adjacent modes of the reference photoelectric oscillator and then transmits it to the signal processing module. The signal processing module is based on the obtained real-time frequency of the intermediate frequency signal. Calculate f _IF , the oscillation frequency f ₁ of the reference photoelectric oscillator, and the frequency interval f _FSR between adjacent modes of the reference photoelectric oscillator to obtain the initial distance, displacement, and real-time distance of the target to be measured in the displacement measurement module. 7. The quasi-distributed displacement measurement method based on photoelectric oscillator according to claim 6, characterized in that: in step A, when the wavelength of the wavelength division multiplexing module in the displacement measurement position and the optical signal of the incoming displacement measurement position When the wavelengths are different, the optical signal transmitted to the displacement measurement position passes through the wavelength division multiplexing module in the displacement measurement position and then transmits to the next wavelength division multiplexing module, and then transmits the optical signal to the next optical fiber delay module. 8. The quasi-distributed displacement measurement method based on an optoelectronic oscillator according to claim 6, wherein step C comprises: the spectrum measurement module measures the spectrum of the microwave signal transmitted by the microwave coupling module 1 in the reference optoelectronic oscillator, and Pass the spectrum information into the signal processing module to obtain the loop delay τ ₀ of the reference photoelectric oscillator, the initial loop length L ₀ , and the initial distance L' of the target to be measured in the displacement sensing module in the displacement measurement position; the loop Delay time τ ₀ =1/f _FSR , loop length L ₀ =(cτ ₀ )/n, initial distance L′=L ₀ of the target to be measured in the displacement measurement module; where c represents the propagation speed of light in vacuum , and n represents the refractive index. 9. The quasi-distributed displacement measurement method based on photoelectric oscillator according to claim 7 or 8, wherein step C comprises, the signal processing module determines the displacement measurement by the real-time frequency of the intermediate frequency signal measured by the frequency counting module The relationship between the displacement ΔL of the target to be measured in the module, the displacement ΔL of the target to be measured in the displacement measurement module and the frequency of the intermediate frequency signal output by the frequency discrimination module; then the displacement of the target to be measured in the displacement measurement module ΔL=L ₀ f _IF /f ₁ , The relationship between the displacement of the target to be measured in the displacement measurement module and the frequency of the intermediate frequency signal output by the frequency discrimination module is:

Among them, c represents the speed of light propagation in a vacuum, and n represents the refractive index.

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