CN117629057A - Device and method for measuring anti-disturbance environmental signals based on white light interference - Google Patents

Abstract

The invention discloses a device and method for measuring anti-disturbance environmental signals based on white light interference, which includes the following steps: S1. Adjust the reference light in the reference arm to cause beat frequency interference with the signal light passing through the event point to be measured; S2 , adjust the polarization state of the reference light to obtain a time domain interference signal under a certain polarization direction angle; S3. Perform Fourier transform on the time domain interference signal to obtain a frequency domain signal, and perform low-frequency filtering; then perform inverse Fourier transform , obtain the interference peak after normalization; S4, repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle; S5, convolve the multiple interference peaks; S6, perform the convolution result of the time domain interference peak Lorenz curve fitting is used to obtain the signal that ultimately eliminates environmental disturbances. The invention can eliminate phenomena such as peak "splitting" and "sawtooth-like deformation" of the white light interference system measurement signal in a cluttered disturbance environment, and can also eliminate other low-frequency noise caused by environmental disturbance.

Description

Device and method for measuring anti-disturbance environmental signals based on white light interference

Technical field

The invention relates to the field of optical measurement, and in particular to a device and method for measuring anti-disturbance environmental signals based on white light interference.

Background technique

White light interference technology is an effective method and solution for measuring weak optical signals. Utilizing the extremely short coherence length of white light, intensity detection and distance positioning of extremely weak signals can be achieved.

However, almost all current white light interference detection equipment can only measure in a static environment. The equipment itself must not have large or rapid disturbances, and the environment where the point to be measured must also be a stable static environment. Once the equipment itself shakes or the product to be tested is in a complex disturbance environment, the environmental disturbance will not only introduce more low-frequency noise, but also change the shape of the optical fiber of the test sample, thereby affecting the change of the polarization state of the light in it. These situations This will cause the measured curve to have thicker background noise, and at the same time, the original single smooth interference peak will be deformed into multiple sharp peaks, making the measurement results complex and difficult to identify, the distance accuracy difficult to determine, and due to the rapid and continuous changes in polarization state, the signal strength will decrease. It will also jump in a large range, and the measurement error will increase sharply.

Contents of the invention

The main purpose of the present invention is to provide a device and method for measuring anti-disturbance environmental signals based on white light interference, so as to significantly improve the signal-to-noise ratio of the final test results in a dynamic environment and truly and accurately restore the interference peak situation of the point to be measured.

The technical solution adopted by the present invention is:

A method for measuring anti-disturbance environmental signals based on white light interferometry is provided, including the following steps:

S1. Adjust the reference light in the reference arm to cause beat frequency interference between the reference light and the signal light passing through the event point to be measured, generating a time domain interference signal; the reference light and signal light are split from the broad spectrum light emitted by the white light source;

S2. Adjust the angle of the polarization state of the reference light to obtain the time domain interference signal at a certain angle between the polarization directions;

S3. Perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transform on the filtered frequency domain signal to obtain the time domain interference spectrum, and obtain the amplitude of the time domain interference spectrum. After normalization, the interference peak is obtained;

S4. Repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle, and obtain N beat frequency interference signals, correspondingly obtaining N interference peaks, where N is an integer;

S5. Convolve N interference peaks to obtain the time domain interference peak convolution result;

S6. Perform Lorentz curve fitting on the time domain interference peak convolution results to obtain the signal that ultimately eliminates environmental disturbance.

Following the above technical solution, when performing Lorentz curve fitting in step S6, specifically the highest amplitude of the N interference peaks is taken as the peak point of the fitting curve, and the average value of the median point of the N interference peaks is taken as the fitting curve. The midpoint of , and the average of the half-height widths of N interference peaks is taken as the half-height width of the fitting curve.

Following the above technical solution, adjusting the reference light in the reference arm in step S1 includes: continuously adjusting the optical path of the reference light by controlling the optical fiber delay line in the reference arm. When the optical path of the reference light is consistent with the measurement arm and passes through the event point to be measured, When the optical paths of the signal lights are equal, beat frequency interference occurs.

Following the above technical solution, the optical fiber delay line continuously changes the optical path of light passing through it by moving the position of the internal reflector, thereby continuously changing the arm length of the reference arm.

Following the above technical solution, adjusting the reference light in the reference arm in step S1 includes frequency shifting, specifically moving the reference light up or down by a fixed frequency.

The invention also provides a system for measuring anti-disturbance environmental signals based on white light interference, including:

The reference arm adjustment module is used to adjust the reference light in the reference arm so that the reference light interferes with the signal light passing through the event point to be measured to generate a time domain interference signal; the reference light and signal light are broad spectrum emitted by the white light source. Light is formed by splitting;

The polarization adjustment module is used to adjust the angle of the polarization state of the reference light to obtain a time domain interference signal at a certain angle between the polarization directions;

The frequency domain transformation module is used to perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transformation on the filtered frequency domain signal to obtain the time domain interference spectrum, and perform low-frequency filtering on the time domain interference signal. The interference peak is obtained after amplitude normalization of the interference spectrum;

The convolution module is used to repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle, and convolve the N interference peaks in the obtained N beat frequency interference signals to obtain the time domain interference peak volume. Product result, N is an integer;

The curve fitting module is used to perform Lorentz curve fitting on the time domain interference peak convolution results to obtain a signal that ultimately eliminates environmental disturbances.

The invention also provides a device for measuring anti-disturbance environmental signals based on white light interference, including:

White light source;

The first optical fiber coupler divides the broad-spectrum light emitted by the white light source into two beams, one beam of signal light enters the measurement arm, and the other beam of reference light enters the reference arm;

A measuring arm, in which the event point to be measured is set, and the signal light is reflected back through the event point to be measured and enters the second optical fiber coupler;

The reference arm is used to adjust the reference light, so that after passing through the reference arm, it enters the second optical fiber coupler and causes beat frequency interference with the signal light; the reference arm is also used to adjust the polarization state of the reference light during each beat frequency interference process. ;

a second optical fiber coupler, at which the incident signal light of the measurement arm and the reference light of the reference arm are coupled;

Control and signal acquisition module, used to collect beat frequency interference signals;

A signal processor, configured to perform signal processing using the method of measuring anti-disturbance environmental signals based on white light interference as claimed in claim 1, to obtain a final signal that eliminates environmental disturbances.

Following the above technical solution, the reference arm includes an optical fiber delay line, and the optical path of the reference light is continuously adjusted by controlling the optical fiber delay line. When the optical path of the reference light is equal to the optical path of the signal light passing through the event point to be measured in the measurement arm, When, beat frequency interference occurs.

Following the above technical solution, the reference arm includes an electric polarization controller for randomly changing the polarization state of the reference light.

Following the above technical solution, the reference arm also includes a frequency shifter for moving the reference light up or down at a fixed frequency.

The present invention also provides a computer storage medium, which stores a computer program that can be executed by a processor. The computer program executes the method for measuring anti-disturbance environmental signals based on white light interference described in the above technical solution.

The beneficial effects produced by this invention are: by utilizing the rapid multiple changes of polarization state during the beat frequency interference process, multiple sets of data are obtained, and the interference results of adjusting a certain polarization angle are obtained each time, and the impact of polarization on the interference intensity is avoided through polarization adjustment. , while improving the accuracy of measurement; in addition, through multiple measurements, the obtained signal is replaced by low-frequency filtering, frequency domain transformation, convolution, normalization and curve fitting, completely eliminating the problem of interference in a disturbed environment. The peak "splitting" and "saw-like deformation" of the white light interference system measurement signal result curve can also eliminate other low-frequency noise caused by environmental disturbance, so that the final test results can also be accurate in a dynamically changing measurement environment. Very nice peak curve and excellent signal to noise ratio.

Furthermore, the position of the internal reflector is moved through the optical fiber delay line, and the optical path of the light passing through it is continuously changed, thereby continuously changing the length of the reference arm, thereby achieving measurement of the range to be measured of the signal arm of the corresponding length.

Furthermore, because disturbances or environmental noise are generally low-frequency, such as tens of kHz or hundreds of khz, by shifting the frequency of the reference light, the signal beat frequency can be more easily separated from the low-frequency disturbance, which facilitates signal collection.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1A is a flow chart of a method for measuring anti-disturbance environmental signals based on white light interference according to an embodiment of the present invention;

1B is a schematic structural diagram of a system for measuring anti-disturbance environmental signals based on white light interferometry according to an embodiment of the present invention;

Figure 1C is a schematic structural diagram of a device for measuring anti-disturbance environmental signals based on white light interference according to an embodiment of the present invention;

Figure 2 is a schematic diagram comparing the beat frequency signals of the white light interference system in the stable state and the disturbed state;

Figure 3 is a schematic diagram of the time domain signal obtained by Fourier transformation of the time domain interference signal and filtering out the low frequency noise and then inverse Fourier transformation;

Figure 4 is a schematic diagram showing the comparison of the interference peaks after normalizing the amplitude of the beat signal in the white light interference system in the stable state and the disturbed state;

Figure 5 is a curve effect diagram after convolution of the transformed interference signals one by one;

Figure 6 is a schematic diagram of replacing the original time domain interference peak with the fitted curve;

In Figure 1C: 1 is the white light source, 2 is the first fiber coupler, 3 is the frequency shifter, 4 is the fiber delay line, 5 is the electric polarization controller, 6 is the circulator, 7 is the point under test DUT, 8 is The second optical fiber coupler, 9 is the control and acquisition module, 10 is the signal processor, 11 is the signal arm, and 12 is the reference arm.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

It should be noted that the diagrams provided in the embodiments of the present invention only illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show the components related to the present invention rather than the number and shape of the components in actual implementation. And size drawing, in actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complex.

In the present invention, it should also be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner" and "outer" appear etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, Constructed and operated in a specific orientation and therefore should not be construed as limiting this application. In addition, the terms "first" and "second", if they appear, are for descriptive and distinguishing purposes only and are not to be understood as indicating or implying relative importance.

This invention is mainly used to effectively eliminate the situation where the low-frequency disturbance noise of the interference signal and the dynamic change of the polarization state in the disturbance environment cause the signal intensity of the point to be measured to jump randomly. The high signal-to-noise ratio restores the original signal peak shape, making the signal more stable and positioning. More precise.

Example 1

As shown in Figure 1A, the method of measuring anti-disturbance environmental signals based on white light interference in this embodiment includes the following steps:

S1. Adjust the optical path of the reference light in the reference arm so that the reference light and the signal light passing through the event point to be measured occur beat frequency interference to generate a time domain interference signal; the reference light and signal light are split from the broad spectrum light emitted by the white light source. become;

S2. Adjust the polarization state of the reference light to obtain the time domain interference signal at a certain angle between the polarization directions;

S3. Perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transform on the filtered frequency domain signal to obtain the time domain interference spectrum, and obtain the amplitude of the time domain interference spectrum. After normalization, the interference peak is obtained;

S4. Repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle, and obtain N times of beat frequency interference signals, correspondingly obtaining N times of interference peaks;

S5. Convolve N interference peaks to obtain the time domain interference peak convolution result;

S6. Perform Lorentz curve fitting on the time domain interference peak convolution results to obtain a signal that finally eliminates environmental anti-disturbance.

Among them, in step S2, in a beat frequency interference, the polarization state of the reference light can be randomly changed. Each time the polarization state is adjusted, the measurement result is scanned once at the point to be measured. When the polarization state is adjusted K times, the results are measured K times. Take The maximum value of all sub-interference peaks is used as the measurement result of the final peak. The polarization state adjustment method is: all polarization directions can be adjusted in each beat frequency interference, that is, 360° traversal and rapid scanning; it can also be fixed in a certain direction and adjusted to a different fixed direction before the next measurement. , traversing 360° after multiple measurements. Each time the polarization state is adjusted, the two arms interfere once at the current polarization angle. After multiple measurements, the probability of a smaller angle between the two polarizations increases. At this time, selecting the maximum value of all interference peaks is The angle between the polarization states of the two lights is the smallest. When the angle is 0, it is in the same direction. At this time, it is closest to the true reflection intensity of the event point to be measured. The more measurements are taken, the greater the probability of being in the same direction, and the more accurate the measurement signal is. , the more stable it is.

Furthermore, because white light is broad spectrum light and its coherence length is extremely short (generally on the order of um to tens of um), it can be approximately considered that coherence occurs when the lengths of the reference arm and the measurement arm are completely equal. Therefore, in step S1 The optical path of the reference light is continuously adjusted by controlling the fiber delay line in the reference arm. When the optical path of the reference light is equal to the optical path of the signal light passing through the event point to be measured in the measurement arm, beat frequency interference occurs.

Further, when performing Lorentz curve fitting in step S6, the highest amplitude of the N interference peaks is specifically taken as the peak point of the fitting curve, and the average value of the median point of the N interference peaks is taken as the center of the fitting curve. point, and the average value of the half-height width of N interference peaks is taken as the half-height width of the fitting curve. Since the position of the event point to be measured remains unchanged, and each delay line scan and data collection are synchronized, theoretically the width and center point position of each interference peak are exactly the same, so it is more accurate to average the half-height width and center position of the peak. Reduce system errors and improve accuracy.

In one embodiment of the present invention, the optical fiber delay line can change the optical path of light passing through it by controlling scanning, thereby changing the entire reference arm arm length (optical path). For example, the optical fiber delay line continuously changes the optical path of light passing through it by moving the position of the internal reflector, thereby continuously changing the length of the reference arm.

Figure 2 is a schematic diagram comparing the beat frequency signals of the white light interference system in the steady state and the disturbed state; because the disturbance or environmental noise is generally low frequency, such as tens of kHz or hundreds of khz, and the optical frequency is generally in the THz range, so Difference frequency detection is the mainstream signal detection method. The beat frequency mentioned above is the difference frequency part of the signal. Regardless of whether the optical signal itself is a single frequency or a wide spectrum within a certain range, the difference frequency after beat frequency interference is not affected. The final frequency is subtracted and becomes a moving fixed frequency, which makes it easier to isolate the signal beat frequency from low-frequency disturbances and facilitate signal collection. The fixed frequency Δf at which the reference light moves is the beat frequency, so the size of Δf determines the detection and demodulation of the signal. For example, moving the fixed frequency Δf to tens of MHz or hundreds of MHz not only facilitates signal detection and filtering, but also isolates environmental disturbances.

It can be seen that this embodiment completely eliminates the peak "splitting" and "sawtooth-like deformation" of the white light interference system measurement signal result curve in a disturbed environment by adjusting the polarization state, frequency domain transformation, convolution, and curve fitting replacement. It can also eliminate other low-frequency noise caused by environmental disturbances. The final test result can also have a very beautiful peak curve and excellent signal-to-noise ratio in a dynamically changing measurement environment. While ensuring that the positioning accuracy remains unchanged and the peak height is more accurate and stable, it perfectly solves the limitation that the original white light interference system can only obtain stable test results by measuring in a static environment, greatly broadening the application of white light interference technology. Scenes.

Example 2

This embodiment is based on Embodiment 1 and is mainly a system embodiment for implementing the method of Embodiment 1.

As shown in Figure 1B, this embodiment's system for measuring anti-disturbance environmental signals based on white light interferometry mainly includes:

The reference arm adjustment module is used to adjust the reference light in the reference arm so that the reference light interferes with the signal light passing through the event point to be measured to generate a time domain interference signal; the reference light and signal light are broad spectrum emitted by the white light source. Light is formed by splitting;

The polarization adjustment module is used to adjust the polarization state of the reference light to obtain a time domain interference signal under a certain polarization direction angle;

The frequency domain transformation module is used to perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transformation on the filtered frequency domain signal to obtain the time domain interference spectrum, and perform low-frequency filtering on the time domain interference signal. The interference peak is obtained after amplitude normalization of the interference spectrum;

The convolution module is used to repeat multiple measurements so that the angle of adjusting the polarization state of the reference light covers a complete cycle, and convolves the N interference peaks in the obtained N beat frequency interference signals to obtain the time domain interference peak. convolution result;

The curve fitting module is used to perform Lorentz curve fitting on the time domain interference peak convolution results to obtain a signal that ultimately eliminates environmental anti-disturbance.

By implementing the method embodiments, the system may have the functions of the method embodiments. This system can completely avoid phenomena such as peak "splitting" and "saw-tooth deformation" of the white light interference system measurement signal result curve in a cluttered and disturbed environment. It can also eliminate other low-frequency noise caused by environmental disturbance, so that the final The test results can also have very beautiful peak curves and excellent signal-to-noise ratio in dynamically changing measurement environments. Neither positioning accuracy nor peak height changes as the original signal is deformed.

Example 3

This embodiment is based on Embodiment 1 and is mainly a device for implementing the method of Embodiment 1.

As shown in Figure 1C, the device for measuring anti-disturbance environmental signals based on white light interference in this embodiment includes:

White light source 1 is used to emit white light, which is broad spectrum light;

The first optical fiber coupler 2 divides the broad spectrum light emitted by the white light source into two beams, one beam of signal light enters the measurement arm, and the other beam of reference light enters the reference arm;

Measuring arm 11, the event point to be measured is set in the measurement arm, and the signal light is reflected back into the second optical fiber coupler after passing through the event point to be measured;

The reference arm 12 is used to adjust the reference light (mainly adjusting the optical path and frequency), so that after passing through the reference arm, it enters the second optical fiber coupler and causes beat frequency interference with the signal light; the reference arm is also used to adjust the beat frequency at each beat frequency. During the interference process, the polarization state of the reference light is randomly changed to obtain a time domain interference signal at an angle between random polarization directions;

The second optical fiber coupler 8, the incident signal light of the measurement arm and the reference light of the reference arm are coupled at the second optical fiber coupler, and beat frequency interference occurs;

The control and signal acquisition module 9 is used to control the acquisition of beat frequency interference signals;

The signal processor 10 is used to perform signal processing using the method of measuring anti-disturbance environmental signals based on white light interference described in the above technical solution to obtain the final anti-disturbance environmental signal. Signal processor 10 may be a computer.

As shown in Figure 1C, specifically, the measurement arm 11 and the reference arm 12 of the device for measuring signals in a disturbed environment based on white light interferometry are connected in parallel between the first fiber coupler 1 and the second fiber coupler 8. The measurement arm 11 includes an optical fiber circulator 6, and the reference arm 12 includes a frequency shifter 3, an optical fiber delay line 4, and an electric polarization controller 5 that are connected in sequence. The frequency shifter 3 can move the frequency of light upward or downward to a fixed frequency through some modulation method. The optical fiber delay line 4 can change the optical path of light passing through it by controlling scanning, thereby changing the entire reference arm arm length (optical path). The electric polarization controller 5 randomly changes the polarization state of light to any direction by changing the shape of the optical fiber. The control and signal acquisition module can also control the operation and work of the optical fiber delay line 4, frequency shifter 3 and electric polarization controller 5, and collect signal data after beat frequency interference.

Further, the polarization type of the white light source can be single mode, and the wavelength of the white light source can be O band (wavelength range is 1530nm to 1565nm), C band (wavelength range is 1530nm to 1565nm) or L band (wavelength range is 1530nm to 1565nm) etc range.

The output end of the white light source 1 is connected to the input end of the first optical fiber coupler 2. One of the output ends of the first optical fiber coupler 2 is used as a signal light and connected to the input end of the optical fiber circulator 6. The other one is used as a reference light and connected to the frequency shifter 3. After the output end of the frequency converter 3, connect the optical fiber delay line 4 and the electric polarization controller 5 in sequence, and finally connect the second optical fiber coupler 8; the second port of the optical fiber circulator 6 in the signal arm (i.e., the measurement arm) receives the test product (and The event point to be tested is DUT (Design Under Test), and the third port is connected to the second optical fiber coupler 8.

The white light source 1 emits broad-spectrum light, which is divided into two paths through the first optical fiber coupler 2. One path enters the optical fiber circulator 6 as signal light. After being reflected by the DUT of the event point to be measured at the second port, it comes out of the third port and enters the second optical fiber. Coupler 8, the other channel serves as the reference light and passes through the frequency shifter 3 to shift the frequency of the reference light by Δf, then enters the fiber delay line 4, continuously adjusts the optical path of the reference light, and finally enters the electric polarization controller 5 to randomly change the reference light polarization state, the reference light finally also enters the second optical fiber coupler 8. And beat frequency interference occurs here with the signal light reflected back from the DUT. Because white light is broad-spectrum light, its coherence length is extremely short (generally on the order of um to tens of um, and it can be approximately considered that coherence occurs when the two arm lengths are completely equal).

The operation and work of the optical fiber delay line 4, the frequency shifter 3 and the electric polarization controller 5 are all controlled by the control and signal acquisition module 9.

The signal processor 10 controls the data acquisition time to be synchronized with the optical fiber delay line scanning time on the software, and reads the collected scanning interference data to the host computer. When building the interference structure, control the total optical path length of the reflected light of the sample to be measured to fall within the total optical path range of the reference arm of the delay line scan.

Adjust the electric polarization controller. Each time the polarization state is rotated, the measurement result is scanned once at the point to be measured. If the polarization state is adjusted N times, the results are measured N times. The maximum value of all interference peaks is taken as the final peak measurement result.

Each measurement corresponds to the interference of the two arms at the current polarization angle. After multiple measurements, the probability that the angle between the two polarizations is smaller becomes greater (at this time, the maximum value of all interference peaks is selected to correspond to the two paths of light. The angle between the polarization states is the smallest, and when the angle is 0, it is in the same direction; at this time, it is closest to the true reflection intensity of the point to be measured. The more measurements are taken, the greater the probability of being in the same direction, and the more accurate and stable the intensity measurement is.)

Since the position of the event point remains unchanged, and each delay line scan and data collection are synchronized, theoretically the width and center point position of each interference peak are exactly the same, so averaging the half-height width and center position of the peak can further reduce System errors and improved accuracy.

The static interference signal conforms to the type of uniform broadening of the spectral line. Lorentz curve fitting is used, which is consistent with the actual interference spectral line situation. The highest amplitude of the interference peak in all sets of results is taken as the peak point A of the fitting curve, and all sets of interference peaks are taken. The average of the median points is taken as the midpoint x ₀ of the fitted signal, and the half-maximum width of all peaks Taking the average, the entire beat frequency interference peak is fitted using the Lorentz curve; where/> .

The base noise in the scanning result curve is filtered by FFT and then inversely FFT transformed back. The noise thickness will be greatly reduced. Convolution of multiple sets of data at the same time not only eliminates environmental and system noise, but also greatly improves the signal-to-noise ratio.

The device's method of eliminating white light interferometer measurement of anti-disturbance signals specifically includes the following steps:

S1. After the light emitted by the white light source passes through the first optical fiber coupler, the light source signal is divided into two channels and enters the measurement arm and the reference arm respectively. By scanning the optical fiber delay line, when the optical paths of the two arms are equal, the two optical fibers interfere with the measurement signal beat frequency at the second optical fiber coupler, and the second optical fiber coupler outputs a perturbation beat frequency signal with DUT reflection intensity information, instantly domain interference signal;

S2. Perform Fourier transform on the obtained time domain interference signal to obtain the frequency domain signal. Filter out all low frequency items in the spectrum and only retain the beat frequency items and perform inverse Fourier transform to obtain a pure time domain interference spectrum. For the interference spectrum After taking the amplitude and normalizing it, the interference peak is obtained; as shown in Figure 3, it is a schematic diagram of the time domain interference signal obtained by Fourier transform to obtain the spectrum, filtering out the low-frequency noise and then inverse Fourier transform to obtain the time domain signal;

S3. Use the electric polarization controller to randomly change the polarization state of the reference arm and scan the fiber delay line. Follow steps S1 and S2 to obtain N sets of normalized interference peak results after inverse Fourier transformation; as shown in Figure 4, it is white light Schematic diagram of the comparison of interference peaks after normalizing the amplitude of the beat frequency signal of the interference system in the stable state and the disturbed state;

S4. Each set of results is convolved sequentially to obtain the final high signal-to-noise ratio time domain interference peak result; as shown in Figure 5, it is the curve effect diagram after convolution of the transformed interference signals one by one;

S5. Take the highest amplitude of the interference peak in all groups of results as the peak point A of the fitting curve, take the average of the median points of the interference peaks in all groups as the midpoint x ₀ of the fitting signal, and take the half-height of all peaks The width is averaged as the half-height width of the fitted signal , the entire beat frequency interference peak is fitted using the Lorentz curve; where/> ;

S6. The fitted curve replaces the original time domain interference peak after convolution, and the final signal processing result is obtained, as shown in Figure 6, which is a schematic diagram of the fitted curve replacing the original time domain interference peak.

The working band, polarization, splitting ratio, electric or manual operation of the light source, fiber delay line, frequency shifter, polarization controller, fiber coupler mentioned in this embodiment are not limited to those mentioned in the embodiment. Professionals can flexibly select devices with different indicators and performance based on this device or method to achieve similar effects.

In summary, the present invention effectively realizes that by using the device and method, the signal-to-noise ratio of the test results of the white light system measuring the reflection signal of the point to be measured in a dynamic environment is improved, and the interference peak situation of the point to be measured can be truly and accurately restored. , eliminating the phenomenon of "splitting" of interference peak deformation caused by disturbance, which makes it difficult to accurately measure the signal intensity and worsens the positioning accuracy of the event point position.

Example 4

This application also provides a computer-readable storage medium, such as flash memory, hard disk, multimedia card, card-type memory (for example, SD or DX memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory Memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disks, optical disks, servers, App application malls, etc., on which computer programs and programs are stored The corresponding function is implemented when executed by the processor. When the computer-readable storage medium of this embodiment is executed by a processor, the method of measuring anti-disturbance environmental signals based on white light interferometry of the method embodiment is implemented.

It should be pointed out that according to the needs of implementation, each step/component described in this application can be split into more steps/components, or two or more steps/components or partial operations of steps/components can be combined into new ones. steps/components to achieve the objectives of the invention.

The sequence number of each step in the above embodiment does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (10)

1. A method for measuring anti-disturbance environmental signals based on white light interference, which is characterized by including the following steps: S1. Adjust the reference light in the reference arm to cause beat frequency interference between the reference light and the signal light passing through the event point to be measured, generating a time domain interference signal; the reference light and signal light are split from the broad spectrum light emitted by the white light source; S2. Adjust the angle of the polarization state of the reference light to obtain the time domain interference signal at a certain angle between the polarization directions; S3. Perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transform on the filtered frequency domain signal to obtain the time domain interference spectrum, and obtain the amplitude of the time domain interference spectrum. After normalization, the interference peak is obtained; S4. Repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle, and obtain N beat frequency interference signals, correspondingly obtaining N interference peaks, where N is an integer; S5. Convolve N interference peaks to obtain the time domain interference peak convolution result; S6. Perform Lorentz curve fitting on the time domain interference peak convolution results to obtain the signal that ultimately eliminates environmental disturbance. 2. The method for measuring anti-disturbance environmental signals based on white light interference according to claim 1, characterized in that when performing Lorentz curve fitting in step S6, the highest amplitude of the N interference peaks is specifically used as the fitting curve. of the peak points, take the average of the median points of the N interference peaks as the midpoint of the fitting curve, and take the average of the half-height widths of the N interference peaks as the half-height width of the fitting curve. 3. The method of measuring anti-disturbance environmental signals based on white light interference according to claim 1, characterized in that, in step S1, adjusting the reference light in the reference arm includes: continuously adjusting the reference light by controlling the optical fiber delay line in the reference arm. When the optical path of the reference light is equal to the optical path of the signal light passing through the event point to be measured in the measurement arm, beat frequency interference occurs. 4. The method of measuring anti-disturbance environmental signals based on white light interference according to claim 3, characterized in that the optical fiber delay line continuously changes the optical path of light passing through it by moving the position of the internal reflector, and then continuously changes the reference arm arm. long. 5. The method for measuring anti-disturbance environmental signals based on white light interference according to claim 1, characterized in that, in step S1, adjusting the reference light in the reference arm includes frequency shifting, specifically moving the reference light upward or downward at a fixed frequency. 6. A system based on white light interferometry to measure anti-disturbance environmental signals, which is characterized by including: The reference arm adjustment module is used to adjust the reference light in the reference arm so that the reference light interferes with the signal light passing through the event point to be measured to generate a time domain interference signal; the reference light and signal light are broad spectrum emitted by the white light source. Light is formed by splitting; The polarization adjustment module is used to adjust the angle of the polarization state of the reference light to obtain a time domain interference signal at a certain angle between the polarization directions; The frequency domain transformation module is used to perform Fourier transform on the time domain interference signal to obtain the frequency domain signal, and perform low-frequency filtering; perform inverse Fourier transformation on the filtered frequency domain signal to obtain the time domain interference spectrum, and perform low-frequency filtering on the time domain interference signal. The interference peak is obtained after amplitude normalization of the interference spectrum; The convolution module is used to repeat multiple measurements, adjust the angle of the polarization state of the reference light to cover a complete cycle, and convolve the N interference peaks in the obtained N beat frequency interference signals to obtain the time domain interference peak volume. Product result, N is an integer; The curve fitting module is used to perform Lorentz curve fitting on the time domain interference peak convolution results to obtain a signal that ultimately eliminates environmental disturbances. 7. A device for measuring anti-disturbance environmental signals based on white light interference, which is characterized by including: white light source; The first optical fiber coupler divides the broad spectrum light emitted by the white light source into two beams, one beam of signal light enters the measurement arm, and the other beam of reference light enters the reference arm; A measuring arm, in which the event point to be measured is set, and the signal light is reflected back through the event point to be measured and enters the second optical fiber coupler; The reference arm is used to adjust the reference light, so that after passing through the reference arm, it enters the second optical fiber coupler and causes beat frequency interference with the signal light; the reference arm is also used to adjust the polarization state of the reference light during each beat frequency interference process. ; a second optical fiber coupler, at which the incident signal light of the measurement arm and the reference light of the reference arm are coupled; Control and signal acquisition module, used to collect beat frequency interference signals; A signal processor, configured to perform signal processing using the method of measuring anti-disturbance environmental signals based on white light interference as claimed in claim 1, to obtain a final signal that eliminates environmental disturbances. 8. The device for measuring anti-disturbance environmental signals based on white light interference according to claim 7, characterized in that the reference arm includes an optical fiber delay line, and the optical path of the reference light is continuously adjusted by controlling the optical fiber delay line. When the reference light When the optical path of the signal light in the measuring arm is equal to the optical path of the signal light passing through the event point to be measured, beat frequency interference occurs. 9. The device for measuring anti-disturbance environmental signals based on white light interference according to claim 7, characterized in that the reference arm includes an electric polarization controller for randomly changing the polarization state of the reference light. 10. The device for measuring anti-disturbance environmental signals based on white light interferometry according to claim 7, characterized in that the reference arm further includes a frequency shifter for moving the reference light upward or downward at a fixed frequency.