Laser self-mixing interference displacement reconstruction method and device based on single-sided time-frequency spectrum

Abstract

The present invention discloses a method and device for laser self-mixing interference displacement reconstruction based on a single-sided time-frequency spectrum. The method comprises the following steps: S1: collecting a self-mixing interference signal from a target object, performing a time-frequency transformation based on the self-mixing interference signal to obtain a double-sided time-frequency spectrum; S2: selecting and retaining a single-sided time-frequency spectrum from the double-sided time-frequency spectrum for analysis; S3: performing an inverse transformation on the single-sided time-frequency spectrum to obtain an analytical signal; S4: extracting the real and imaginary parts of the analytical signal and dividing them to obtain a tangent signal; S5: performing an inverse tangent operation on the tangent signal to obtain a motion phase; and S6: calculating the relationship between phase and distance based on the motion phase to obtain a displacement curve of the target object. The present invention eliminates the need for additional complex optical components to obtain orthogonal signals, simplifies the composition of the measurement system, and provides a novel, efficient, and economical solution for the field of displacement measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical measurement, and in particular relates to a laser self-mixing interference displacement reconstruction method and device based on a single-sided time-frequency spectrum. Background Art

[0002] Non-contact sensing technology plays a key role in fields such as biomedical monitoring and industrial manufacturing, and the need to accurately obtain information transmitted by vibrating targets in complex external environments is increasingly urgent. Self-mixing interferometry technology, which leverages the interference effect between the target's reflected light and the original laser light within a cavity, achieves highly sensitive, non-contact detection of target vibration information, and has therefore attracted widespread attention. In this process, demodulation of the self-mixing signal is particularly important, as it directly affects the accurate extraction of vibration information.

[0003] To achieve this goal, researchers have developed a variety of reconstruction methods, including fringe counting, phase unwrapping, quadrature phase demodulation, and current modulation. Among them, the quadrature phase demodulation method is considered a preferred solution due to its high efficiency and strong anti-interference ability. However, the quadrature phase demodulation method often requires the introduction of special optical elements such as wedge prisms, wave plates, liquid crystal phase shifters, beam splitters, and electro-optical modulators in the measurement system to obtain two self-mixing signals with a phase difference of 90 degrees. Therefore, although this method effectively solves the problem of determining the direction of movement of the target object, it also brings about the problems of complicated optical path, increased difficulty in instrument debugging, and may introduce non-orthogonal phase errors. In addition, it also leads to an increase in the cost of vibration sensors.

[0004] Therefore, in the orthogonal detection method, a high-precision reconstruction scheme with a simple optical path structure and low cost is urgently needed to promote the wider application of laser self-mixing interferometry technology in precision measurement.

[0005] Chinese patent publication number CN116045815A discloses a wedge-shaped orthogonal laser self-mixing interference displacement detection device, which includes a wedge, an adjustable attenuation plate, a laser, a first optical diaphragm, a second optical diaphragm, a micro-motion platform, a signal acquisition module, and a signal processing module; wherein the wedge, adjustable attenuation plate, laser, and first optical diaphragm are arranged in a straight line with the target to be measured to form a wedge-shaped orthogonal laser self-mixing interference optical path; the second optical diaphragm is carried by the micro-motion platform and is arranged on the reflection optical path of the wedge; the signal acquisition module is used to collect two self-mixing interference signals with phase difference emitted by the first optical diaphragm and the second optical diaphragm respectively during the detection process, and transmit them to the signal processing module; the signal processing module is used to provide a driving signal for the micro-motion platform to move the second optical diaphragm along the radial direction of the light spot; and is also used to obtain the displacement of the target to be measured from the self-mixing interference signal through a wedge-shaped orthogonal displacement detection algorithm. This invention adds a wedge tip to the external cavity of the laser self-mixing interference system to obtain two normalized self-mixing interference signals with a phase difference of 90°, which increases the complexity of the optical path and leads to an increase in the overall cost of the detection system. Summary of the Invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a laser self-mixing interference displacement reconstruction method and device based on single-sided time-frequency spectrum, which does not require the introduction of additional complex optical elements to obtain orthogonal signals, simplifies the composition of the measurement system, and provides a novel, efficient and economical solution for the field of displacement measurement.

[0007] The technical solutions of the present invention are as follows:

[0008] In one aspect, the present invention provides a method for laser self-mixing interference displacement reconstruction based on a single-sided time-frequency spectrum, comprising the following steps:

[0009] S1: Collect the self-mixing interference signal of the target object, and perform time-frequency transformation on the self-mixing interference signal to obtain a bilateral time-frequency spectrum.

[0010] S2: Selecting and retaining a unilateral time-spectrum for analysis from the bilateral time-spectrum graph.

[0011] S3: Perform inverse transform on the single-sided time-frequency spectrum to obtain the analytical signal.

[0012] S4: extracting the real part and the imaginary part of the analytical signal, and dividing the two to obtain a tangent signal.

[0013] S5: Perform an inverse tangent operation on the tangent signal to obtain the motion phase.

[0014] S6: Calculate the relationship between the phase and the distance according to the motion phase to obtain the displacement curve of the target object.

[0015] Preferably, the time-frequency transformation in step S1 includes but is not limited to: short-time Fourier transform and Wigner quasi-probability distribution.

[0016] Preferably, the unilateral time-frequency spectrum selected and retained for analysis in step S2 is specifically:

[0017] The single-sided time-frequency spectrum for analysis is selected and retained according to the target's movement direction: when the target is far away from the laser, the positive frequency part of the time-frequency matrix is ​​selected and retained; when the target is close to the laser, the negative frequency part of the time-frequency matrix is ​​selected and retained.

[0018] Preferably, obtaining the target object's motion direction includes but is not limited to: representing the self-mixing interference signal as the phase part of a complex exponential, and extracting the instantaneous frequency containing the target object's motion direction information through time-frequency domain transformation processing; or calculating the target object's motion direction using the tilt characteristics of the time domain signal.

[0019] Preferably, in step S3, the inverse transformation of the unilateral time-frequency spectrum to obtain the analytical signal is specifically:

[0020] After performing inverse time-frequency transform on the single-sided time-frequency spectrum, we get an analytical signal with orthogonal real and imaginary parts: in is the signal phase in the presence of optical feedback interference.

[0021] Preferably, the calculation formula of the displacement curve of the target object is specifically:

[0022]

[0023] Where L(t) is the displacement curve of the target; t is time; λ is the center wavelength of the laser; The motion phase.

[0024] Preferably, the target object motion type measured by the self-mixing interference signal is simple harmonic motion or non-simple harmonic motion.

[0025] On the other hand, the present invention provides a laser self-mixing interference displacement reconstruction device based on a single-sided time-frequency spectrum, comprising a time-frequency analysis and extraction module and a phase displacement recovery module.

[0026] The time-frequency analysis extraction module is used to convert the self-mixing interference signal from the time domain to the time-frequency domain to generate a bilateral time-frequency spectrum, select and retain the unilateral time-frequency spectrum for analysis, and perform inverse transformation on the retained unilateral time-frequency spectrum to obtain the analytical signal.

[0027] The phase displacement recovery module is used to extract phase information from the analytical signal and obtain the displacement curve of the target object.

[0028] On the other hand, the present invention also provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and runnable on the processor, wherein when the processor executes the computer program, it implements the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum as described in any embodiment of the present invention.

[0029] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum as described in any embodiment of the present invention.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] This method specifically preserves the desired negative frequency components when processing the time-frequency spectrum, enabling a more comprehensive understanding of the characteristics of the self-mixing interference signal and improving the accuracy and reliability of displacement measurement. Furthermore, by avoiding the need for complex optical components, the measurement system is simplified and costs are reduced, providing a novel and effective solution for displacement measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the overall flow chart of the laser self-mixing interference displacement reconstruction method based on unilateral time-frequency spectrum described in the present invention;

[0033] Figure 2 This is a diagram showing the architecture of the laser self-mixing interference displacement reconstruction method based on unilateral time-frequency spectrum described in the present invention;

[0034] Figure 3 1 is a diagram showing the simulation results of the present invention for simple harmonic oscillation displacement reconstruction;

[0035] Figure 4 This is a simulation result diagram of the present invention for reconstructing the simple harmonic vibration displacement of a signal affected by speckle;

[0036] Figure 5 This is a diagram showing the experimental results of the present invention for the reconstruction of anharmonic vibration displacement. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in combination with specific embodiments of the present application and with reference to the accompanying drawings.

[0038] Example 1

[0039] When the target object moves relative to the laser, the information of its movement direction is contained in the frequency characteristics of the self-mixing interference signal. In order to accurately extract this information, the present embodiment provides a laser self-mixing interference displacement reconstruction method based on a single-sided time-frequency spectrum, which selects and retains the spectral components directly related to the movement direction of the target object, and then performs an inverse transformation on the selected single-sided time-frequency spectrum to obtain an analytical signal. Subsequently, the real and imaginary parts are extracted from the analytical signal, and the two are divided to obtain a tangent signal. An inverse tangent operation is then performed to obtain the motion phase, and finally the displacement curve of the target object is derived based on the phase information. When processing the time-frequency spectrum, the method described in this embodiment particularly retains the required negative frequency components, which can more comprehensively reveal the characteristics of the self-mixing interference signal and improve the accuracy and reliability of displacement measurement.

[0040] See Figure 1 As shown, the following steps are included:

[0041] S1: Collect the self-mixing interference signal of the target object, and perform time-frequency transformation on the self-mixing interference signal to obtain a bilateral time-frequency spectrum.

[0042] S2: Selecting and retaining a unilateral time-spectrum for analysis from the bilateral time-spectrum graph.

[0043] S3: Perform inverse transform on the single-sided time-frequency spectrum to obtain the analytical signal.

[0044] S4: extracting the real part and the imaginary part of the analytical signal, and dividing the two to obtain a tangent signal.

[0045] S5: Perform an inverse tangent operation on the tangent signal to obtain the motion phase.

[0046] S6: Calculate the relationship between the phase and the distance according to the motion phase to obtain the displacement curve of the target object.

[0047] As a preferred implementation of this embodiment, the time-frequency transformation in step S1 includes but is not limited to: short-time Fourier transform and Wigner quasi-probability distribution. In practical applications, there is no restriction on the selection of time-frequency transformation method. In this embodiment, short-time Fourier transform is preferably used as the time-frequency transformation method.

[0048] As a preferred implementation of this embodiment, when the target moves relative to the laser, the information about its direction of motion is contained in the main frequency of the self-mixing interference signal, reflecting the instantaneous frequency change of the self-mixing interference signal and providing us with important information about the direction of motion of the target. Therefore, by analyzing the sign of the instantaneous frequency, the corresponding spectrum can be selected and retained. Thus, based on the above principle, the spectral components directly related to the direction of motion of the target can be selected and retained. The unilateral time-frequency spectrum selected and retained for analysis in step S2 is specifically:

[0049] The single-sided time-frequency spectrum for analysis is selected and retained according to the target's movement direction: when the target is far away from the laser, the positive frequency part of the time-frequency matrix is ​​selected and retained; when the target is close to the laser, the negative frequency part of the time-frequency matrix is ​​selected and retained.

[0050] As a preferred implementation of this embodiment, obtaining the target's motion direction includes, but is not limited to: representing the self-mixing interference signal as the phase portion of a complex exponential and extracting the instantaneous frequency containing the target's motion direction information through time-frequency domain transformation; or calculating the target's motion direction using the tilt characteristics of the time-domain signal. The specific method for obtaining the target's motion direction can be selected based on actual needs. There is no fixed emphasis on the method used for obtaining the motion direction, and the selection is not directly related to the target's motion type and is not limited here.

[0051] Methods for obtaining the target object's motion direction can be roughly divided into two categories: time domain processing and frequency domain processing. This embodiment selects the complex exponential method as an example mainly based on the following two advantages: 1. Strong robustness of time-frequency domain processing: This method performs well in dealing with noise and interference, and can provide relatively accurate analysis results even in the case of poor signal quality. 2. Good performance in processing weak light feedback signals: The self-mixing signal obtained under weak light feedback intensity has unclear stripe tilt characteristics and becomes difficult to analyze, but the complex exponential method can effectively extract and process the self-mixing signal obtained under weak light feedback intensity, thereby accurately obtaining the motion direction.

[0052] Furthermore, this embodiment takes the self-mixing interference signal as the phase part of a complex exponential and extracts the instantaneous frequency containing the target object's motion direction information through time-frequency domain transformation as an example, specifically:

[0053] The self-mixing interference signal P(t) is expressed as:

[0054]

[0055] Where P(t) is the self-mixing interference signal power measured in actual measurement; t is time; is the signal phase with optical feedback interference, and also represents the motion phase of the target object; P o (t) is the power without light feedback.

[0056] The obtained self-mixing interference signal P(t) is expressed as the phase part e of the complex exponential i*P(t) .

[0057] For e i*P(t) Perform a time-frequency domain transformation to obtain a bilateral time-spectrum diagram. The time-domain features of the signal are converted into time-frequency domain features to reflect the changes in the signal spectrum over time at different moments.

[0058] The corresponding frequency value at which the frequency amplitude of the signal reaches the maximum at each moment is extracted to obtain the instantaneous frequency. The instantaneous frequency obtained at this time not only contains the numerical information of the frequency, but also implies the positive and negative signs of the frequency.

[0059] The instantaneous frequency extracted above is converted into a symbolic representation. In this conversion process, the following principle is followed: if the frequency value is positive, it is assigned a positive sign; if the frequency value is negative, it is assigned a negative sign.

[0060] Specifically, the symbol representation is not limited in practical applications and may include but is not limited to square wave signals and rectangular wave signals.

[0061] Furthermore, this embodiment selects a square wave signal as a symbolic representation, performs a time-frequency domain transformation on the original self-mixing interference signal to obtain a bilateral time-frequency spectrum, and then performs spectrum selection based on the square wave signal: if the square wave signal is positive, the positive frequency portion of the time-frequency spectrum is retained; if the square wave signal is negative, the negative frequency portion of the time-frequency spectrum is retained.

[0062] As a preferred implementation of this embodiment, an inverse transformation is performed on the obtained unilateral time-frequency spectrum containing positive and negative frequency components to convert the time-frequency domain features into time-domain features. The inverse transformation of the unilateral time-frequency spectrum to obtain the analytical signal in step S3 is specifically as follows:

[0063] After performing inverse time-frequency transform on the single-sided time-frequency spectrum, we get an analytical signal with orthogonal real and imaginary parts: in is the signal phase in the presence of optical feedback interference.

[0064] Furthermore, the real part of the analytical signal is extracted Imaginary part Dividing these two gives the tangent signal

[0065] For tangent signal Perform inverse tangent operation to obtain motion phase

[0066] The displacement curve of the target object is calculated according to the displacement curve formula of the target object.

[0067] As a preferred implementation of this embodiment, the calculation formula for the displacement curve of the target object is specifically:

[0068]

[0069] Where L(t) is the displacement curve of the target; t is time; λ is the center wavelength of the laser; The motion phase.

[0070] As a preferred implementation manner of this embodiment, the target object motion type measured by the self-mixing interference signal is simple harmonic motion or non-simple harmonic motion.

[0071] To verify the effectiveness and superiority of the method provided in this embodiment, some specific cases are provided below:

[0072] Application example 1:

[0073] See Figure 2 As shown in the figure, obtaining the target's motion direction takes the example of "using the self-mixing interference signal as the phase portion of a complex exponential and performing time-frequency domain transformation to extract the instantaneous frequency containing information about the target's motion direction." The instantaneous frequency is converted into a square wave signal. The corresponding time-frequency spectrum components are retained based on the square wave signal. After inverse transformation, an analytical signal with a 90-degree phase difference between the real and imaginary parts is obtained, which in turn yields the target displacement curve. Simple harmonic oscillation was tested using MATLAB software, and the simulation parameters are set as shown in Table 1.

[0074] Table 1 Parameter setting table

[0075] symbol meaning value C Optical feedback factor 0.1 α Linewidth broadening factor 4 N Number of sampling points 6k <![CDATA[f s ]]> Sampling frequency 200kHz f Target vibration frequency 100Hz A Target vibration amplitude 3.25μm λ Laser wavelength 650nm

[0076] The self-mixing interference signal obtained by simulation is as follows Figure 3 As shown in (a), the obtained self-mixing signal P(t) is multiplied by the imaginary number i as the phase term of the e index: e i*P(t) .

[0077] For the above signal e i*P(t) Perform short-time Fourier transform to obtain the bilateral time-frequency spectrum of the signal changing with time, such as Figure 3 (b) shown.

[0078] The time-frequency ridge is extracted from the bilateral time-frequency spectrum. The time-frequency ridge is as follows: Figure 3 (b) is shown by the red line. The instantaneous frequency information contained in the time-frequency ridge is converted into a square wave signal, as shown in Figure 3 (c) is shown by the red line.

[0079] Perform short-time Fourier transform on the original self-mixing interference signal P(t), and retain the corresponding spectrum part according to the square wave signal. The result is as follows Figure 3 (c) shown.

[0080] Perform inverse short-time Fourier transform on the retained unilateral time-frequency spectrum to obtain the analytical signal. Select the real and imaginary parts of the analytical signal respectively. The results are as follows: Figure 3 As shown by the red and black lines in (d), the red line is the real signal The black line is the imaginary signal

[0081] Divide the two to get the tangent signal Using the inverse tangent function Motion phase And calculate the displacement curve. Among them, the reconstruction result is as follows Figure 3 As shown in (e), the blue curve is the reconstructed vibration displacement, and the red curve is the reference displacement.

[0082] The absolute error of reconstruction is Figure 3 As shown in (f), the root mean square error (red line) is 5.94 nm.

[0083] The results show that the displacement reconstruction method proposed in the present invention exhibits high reconstruction accuracy. At the same time, this method does not require complex calculations and additional optical elements, providing a novel, efficient and economical solution for the field of displacement measurement.

[0084] Application Example 2

[0085] In order to verify the effect of the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum proposed in this application under different linewidth broadening factors α and optical feedback factors C, simulations were performed for different parameter conditions of α and C.

[0086] The root mean square error of the reconstruction is shown in Table 2.

[0087] Table 2 Comparison of RMS error under different linewidth broadening factors α and optical feedback factors C

[0088] C / α 3 4 5 6 0.1 5.95nm 5.94nm 5.94nm 5.94nm 0.3 11.9nm 11.8nm 11.8nm 11.8nm 0.5 19.0nm 18.9nm 18.9nm 18.9nm 0.7 26.7nm 26.6nm 26.5nm 26.5nm 0.9 30.9nm 30.8nm 30.8nm 30.8nm

[0089] The results show that the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum proposed in this embodiment has a small root mean square error under different linewidth broadening factors α and optical feedback factors C, and the method is robust to the linewidth broadening factor α and the optical feedback factor C.

[0090] Application Example 3

[0091] Consider whether the speckle effect caused by the uneven surface of the vibrating target will affect the reconstruction of the signal during the actual detection process. Figure 4 (b) shown.

[0092] The absolute error of reconstruction is obtained as Figure 4 As shown in (g), the root mean square error (red line) is 9.14 nm.

[0093] The results show that the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum proposed in this embodiment is well adapted to the SMI signal amplitude attenuation changes caused by the speckle effect and has strong robustness.

[0094] Application Example 4

[0095] In order to verify the effect of the laser self-mixing interference displacement reconstruction method based on the single-sided time-frequency spectrum described in this embodiment in the experiment, the laser self-mixing interference signal obtained in the experiment was experimentally processed.

[0096] The experimental results of non-harmonic motion displacement reconstruction are as follows Figure 5 As shown in (f), the root mean square error of the reconstruction is 60 nm. The results show that the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum proposed in this embodiment can effectively process the experimental signal.

[0097] Example 2

[0098] Accordingly, this embodiment provides a laser self-mixing interference displacement reconstruction device based on a single-sided time-frequency spectrum, including a time-frequency analysis and extraction module and a phase displacement recovery module.

[0099] The time-frequency analysis and extraction module is used to convert the self-mixing interference signal from the time domain to the time-frequency domain to generate a bilateral time-frequency spectrum, select and retain the unilateral time-frequency spectrum for analysis, and perform an inverse transform on the retained unilateral time-frequency spectrum to obtain the analytical signal. This module is used to implement the functions of steps S1, S2, and S3 in Example 1 and will not be repeated here.

[0100] The phase displacement recovery module is used to extract phase information from the analytical signal to obtain the displacement curve of the target object. This module is used to implement the functions of steps S4, S5, and S6 in Example 1 and will not be described in detail here.

[0101] Example 3

[0102] This embodiment provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum as described in any embodiment of the present invention is implemented.

[0103] Example 4

[0104] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum as described in any embodiment of the present invention is implemented.

[0105] In the embodiments of the present application, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can represent: a, b, c, a and b, a and c, b and c or a and b and c, where a, b, c can be single or multiple.

[0106] Those skilled in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented using a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0107] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0108] In the several embodiments provided in this application, if any function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of this application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory; hereinafter referred to as: ROM), random access memory (Random Access Memory; hereinafter referred to as: RAM), magnetic disk or optical disk, and other media that can store program code.

[0109] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum, characterized in that: The following steps are involved: S1: Collect the self-mixing interference signal of the target object, and perform time-frequency transformation on the self-mixing interference signal to obtain a bilateral time-frequency spectrum; S2: selecting and retaining a unilateral time-spectrum for analysis from the bilateral time-spectrum graph; The unilateral time-frequency spectrum selected and retained for analysis is specifically: The single-sided time-frequency spectrum for analysis is selected and retained according to the target's direction of motion: when the target is far away from the laser, the positive frequency portion of the time-frequency matrix is ​​selected and retained; when the target is close to the laser, the negative frequency portion of the time-frequency matrix is ​​selected and retained; S3: Perform inverse transform on the single-sided time-frequency spectrum to obtain the analytical signal; The inverse transformation of the unilateral time-frequency spectrum to obtain the analytical signal is specifically: After performing inverse time-frequency transform on the single-sided time-frequency spectrum, we get an analytical signal with orthogonal real and imaginary parts: ,in is the signal phase with optical feedback interference, that is, the motion phase of the target object; S4: extracting the real part and the imaginary part of the analytical signal, and dividing the two to obtain a tangent signal; S5: Performing arc tangent operation on the tangent signal to obtain the motion phase; S6: Calculate the relationship between phase and distance based on the motion phase to obtain the displacement curve of the target object; The calculation formula of the displacement curve of the target object is specifically: Where, is the displacement curve of the target; For time; is the laser center wavelength; The motion phase.

2. The laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum according to claim 1 is characterized in that: The time-frequency transformation in step S1 includes but is not limited to: short-time Fourier transform or Wigner quasi-probability distribution.

3. The laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum according to claim 1, characterized in that: Obtaining the target's direction of motion includes but is not limited to: representing the self-mixing interference signal as the phase part of a complex exponential, and extracting the instantaneous frequency containing the target's direction of motion information through time-frequency domain transformation processing; or calculating the target's direction of motion using the tilt characteristics of the time domain signal.

4. The laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum according to claim 1, characterized in that: The target object motion type measured by the self-mixing interference signal is simple harmonic motion or non-simple harmonic motion.

5. A laser self-mixing interference displacement reconstruction device based on single-sided time-frequency spectrum, characterized in that: The device is used to implement the laser self-mixing interference displacement reconstruction method based on the single-sided time-frequency spectrum according to any one of claims 1 to 4, comprising a time-frequency analysis and extraction module and a phase displacement recovery module; The time-frequency analysis extraction module is used to convert the self-mixing interference signal from the time domain to the time-frequency domain to generate a bilateral time-frequency spectrum, select and retain the single-sided time-frequency spectrum for analysis, and perform inverse transformation on the retained single-sided time-frequency spectrum to obtain the analytical signal; The phase displacement recovery module is used to extract phase information from the analytical signal and obtain the displacement curve of the target object.

6. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum as described in any one of claims 1 to 4 when executing the computer program.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the laser self-mixing interference displacement reconstruction method based on single-sided time-frequency spectrum according to any one of claims 1 to 4 is implemented.

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