A method and system for dual-wavelength laser ranging

Abstract

The application relates to the technical field of distance measurement, and discloses a method and system for distance measurement by using dual-wavelength laser, which comprises the following steps: emitting two laser signals with different wavelengths, modulating the two laser signals, forming an interference weaving grid in the transmission process of the two laser beams, analyzing the interference weaving grid, and generating a photon weaving density index; generating the interference weaving grid through asynchronous frequency modulation, combining the reflected signal and environmental data to generate a wavefront distortion feature quantity, accurately capturing the distortion of the light path, generating a phase distortion compensation coefficient by tracking the singular point trajectory, and then obtaining an adaptive distance scale and a distance measurement confidence level. The scheme effectively offsets high-frequency noise introduced by high-speed carrier vibration, solves the problem of lag in post-calibration in traditional distance measurement, and improves the accuracy of distance measurement.

Description

Technical Field

[0001] This invention relates to the field of ranging technology, and specifically to a method and system for ranging using dual-wavelength lasers. Background Technology

[0002] Currently, laser ranging often employs the dual-wavelength phase difference method for high-precision ranging. This method calculates the time difference by measuring the phase difference between two wavelength laser signals, and then achieves unambiguous and high-precision measurement of absolute distance by synthesizing the wavelength.

[0003] However, existing ranging methods still rely on optical receiving components, such as lenses and filters. These optical receiving components are usually designed based on standard environments. In different environments, the optical elements may change due to environmental changes. For example, on a high-speed moving vehicle, vibration can cause the receiving optical axis to jitter, which introduces huge high-frequency noise. This situation is usually mitigated by post-calibration, but it is impossible to sense and dynamically compensate for this real-time and rapidly changing optical path distortion during measurement, which may result in inaccurate distance measurements. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and system for dual-wavelength laser ranging, which solves the aforementioned problems.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A method for ranging using dual-wavelength lasers includes:

[0007] Step S1: Emits two laser signals of different wavelengths, modulates the two laser signals to form an interference weave grid during transmission, and analyzes the interference weave grid to generate a photon weave density index.

[0008] Step S2: Obtain the reflected laser signal, analyze the displacement of each node in the interference braided mesh based on the reflected laser signal to obtain the displacement vector field, and process the displacement vector field based on the photon braiding density index to generate wavefront distortion characteristic quantity;

[0009] Step S3: Track the motion trajectory of singular points in the wavefront distortion characteristic quantity, and analyze the influence of optical path distortion on dual-wavelength laser phase measurement based on the motion trajectory to generate phase distortion compensation coefficient.

[0010] Step S4: Apply the phase distortion compensation coefficient to the phase correction of the dual-wavelength laser to generate an adaptive distance scale;

[0011] Step S5: Analyze the stability of the ranging process based on the adaptive distance scale to obtain the ranging confidence level.

[0012] Furthermore, the two laser signals are modulated to form an interference weave grid during transmission, and the interference weave grid is analyzed to generate a photon weave density index, including:

[0013] Asynchronous frequency modulation of dual-wavelength lasers causes them to undergo continuous dynamic interference in the region of common transmission, forming an interference weave grid.

[0014] Spatiotemporal sampling is performed on the interference woven mesh to obtain a spatiotemporal image set. The spatiotemporal image set is then analyzed to obtain the mesh modulation depth.

[0015] Furthermore, the two laser signals are modulated to form an interference weave grid during transmission, and the interference weave grid is analyzed to generate a photon weave density index. This also includes:

[0016] Identify and analyze the bright interference fringe nodes in the spatiotemporal image set to generate the node spatial entropy;

[0017] By analyzing the spatiotemporal distribution of optical vortices in spatiotemporal image sets, the correlation length of the vortex chain is obtained;

[0018] The photon weaving density index is generated by fusing the grid modulation depth, node spatial entropy, and vortex chain association length.

[0019] Furthermore, based on the analysis of the displacement of each node in the interferometric braided mesh using reflected laser signals, a displacement vector field is obtained. This displacement vector field is then processed based on the photon braiding density index to generate wavefront distortion characteristics, including:

[0020] Based on reflected laser signals, the position changes of each node in the interferometric woven mesh are tracked to generate a node displacement vector field;

[0021] Based on the node displacement vector field, the set formed by the change in the connection relationship between adjacent nodes due to displacement is identified, and the node connection reconstruction rate is obtained.

[0022] In the nodal displacement vector field, the displacements of different nodes are analyzed to obtain the displacement ripple correlation degree.

[0023] Furthermore, based on the analysis of the displacement of each node in the interferometric braided mesh using reflected laser signals, a displacement vector field is obtained. This displacement vector field is then processed using the photon braiding density index to generate wavefront distortion characteristics. The method also includes:

[0024] Real-time acquisition of environmental data;

[0025] Based on environmental data and the correlation between displacement ripples, the interference of the environment on optical path propagation is analyzed, and the node anchorage rate is generated.

[0026] Based on the photon weaving density index, different nodal displacements in the nodal displacement vector field are corrected to obtain the weaving weighted displacement field;

[0027] The node connection reconstruction rate, node anchorage rate, and woven weighted displacement field are fused to generate wavefront distortion characteristic quantities.

[0028] Furthermore, the motion trajectory of singular points in the wavefront distortion characteristic quantities is tracked, and the influence of optical path distortion on dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate phase distortion compensation coefficients, including:

[0029] From the wavefront distortion characteristics, the motion trajectory of singular points is traced and analyzed to generate the singular point trajectory curvature spectrum;

[0030] By analyzing the curvature spectrum of singular point trajectories, identifying the hysteresis time and curvature span of the trajectories, the singular point memory hysteresis factor is obtained.

[0031] Based on displacement ripple correlation, the phase winding effect of dual-wavelength lasers is analyzed, and wavelength phase winding is generated;

[0032] Based on the node anchorage rate, the intensity of the effect of environmental disturbance on the trajectory of singular points is evaluated, and the deviation integral generated by the trajectory is calculated to generate the singular point misalignment path integral.

[0033] Furthermore, the motion trajectory of singular points in the wavefront distortion characteristic quantities is tracked, and the influence of optical path distortion on dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate phase distortion compensation coefficients. This also includes:

[0034] By fusing the singularity memory hysteresis factor, wavelength phase entanglement degree, and singularity misalignment path integral, an equivalent distortion tensor matrix is ​​obtained.

[0035] The equivalent distortion tensor matrix is ​​mapped onto the synthetic wavelength scale of the dual-wavelength laser and calculated to generate the phase distortion compensation coefficient.

[0036] Furthermore, the phase distortion compensation coefficient is applied to the phase correction of the dual-wavelength laser to generate an adaptive distance scale, including:

[0037] Obtain the phase of a dual-wavelength laser signal;

[0038] Based on the phase distortion compensation coefficient, the differences in the influence of optical path distortion on the phase of each dual-wavelength laser are analyzed, and the distortion contribution weight is generated.

[0039] The phase of the dual-wavelength laser is calibrated based on the distortion contribution weight and the phase distortion compensation coefficient to generate an adaptive distance scale.

[0040] Furthermore, the stability of the ranging process is analyzed based on the adaptive distance scaling to obtain the ranging confidence level, including:

[0041] Analyze the numerical sequence formed by the adaptive distance scale in continuous measurements to generate scale evolution inertia;

[0042] Based on the node anchorage ratio and phase distortion compensation coefficient, the ability to maintain the effectiveness of the adaptive distance scale is analyzed, and hysteresis resistance values ​​are generated.

[0043] The scaling evolution inertia and hysteresis resistance values ​​are fused to generate the ranging confidence score.

[0044] Furthermore, a system employing dual-wavelength laser ranging, applied to the aforementioned method of employing dual-wavelength laser ranging, includes:

[0045] The laser interferometer is used to emit two laser signals of different wavelengths, modulate the two laser signals so that the two laser beams form an interference weave grid during transmission, and analyze the interference weave grid to generate the photon weave density index.

[0046] The distortion analysis unit is used to acquire the reflected laser signal, analyze the displacement of each node in the interference braided mesh based on the reflected laser signal, obtain the displacement vector field, and process the displacement vector field based on the photon braiding density index to generate wavefront distortion characteristic quantities.

[0047] The distortion compensation unit is used to track the motion trajectory of singular points in the wavefront distortion characteristic quantity, and analyze the influence of optical path distortion on dual-wavelength laser phase measurement based on the motion trajectory to generate phase distortion compensation coefficients.

[0048] The correction unit is used to apply the phase distortion compensation coefficient to the phase correction of the dual-wavelength laser and generate an adaptive distance scale;

[0049] The judgment unit is used to analyze the stability of the ranging process based on the adaptive distance scale and obtain the ranging confidence level.

[0050] In summary, the present invention has the following main beneficial effects:

[0051] By generating and analyzing an interferometric braided mesh using asynchronous frequency modulation, the photon braiding density index is obtained. Then, based on the analysis of the reflected signal, the node displacement is generated to produce a displacement vector field. Simultaneously, combined with environmental data analysis, wavefront distortion characteristics are obtained, enabling refined online perception of optical path distortion. Furthermore, by tracking the motion trajectory of singular points to generate a singular point trajectory curvature spectrum, the singular point memory hysteresis factor is extracted. Combined with wavelength phase winding degree and singular point misalignment path integral fusion, an equivalent distortion tensor matrix is ​​obtained, ultimately generating a precise phase distortion compensation coefficient. This can dynamically offset high-frequency noise interference introduced by high-speed carrier vibration, etc. The subsequently generated adaptive distance scale is the final ranging result, and its reliability is judged by the ranging confidence level. This can solve the lag problem of post-calibration in traditional ranging, improving the stability and accuracy of ranging. Attached Figure Description

[0052] Figure 1 This is a flowchart illustrating the steps of a dual-wavelength laser ranging method according to the present invention;

[0053] Figure 2 This is a schematic diagram of a dual-wavelength laser ranging system according to the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] refer to Figure 1 and Figure 2 A method for ranging using dual-wavelength lasers includes:

[0056] Step S1: Emits two laser signals of different wavelengths, modulates the two laser signals to form an interference weave grid during transmission, and analyzes the interference weave grid to generate a photon weave density index.

[0057] The difference between the two laser wavelengths corresponds to a combined wavelength between 10 centimeters and 1 meter, and both laser wavelengths are located in the visible to near-infrared band.

[0058] Step S2: Obtain the reflected laser signal, analyze the displacement of each node in the interference braided mesh based on the reflected laser signal to obtain the displacement vector field, and process the displacement vector field based on the photon braiding density index to generate wavefront distortion characteristic quantity;

[0059] Step S3: Track the motion trajectory of singular points in the wavefront distortion characteristic quantity, and analyze the influence of optical path distortion on dual-wavelength laser phase measurement based on the motion trajectory to generate phase distortion compensation coefficient.

[0060] Step S4: Apply the phase distortion compensation coefficient to the phase correction of the dual-wavelength laser to generate an adaptive distance scale;

[0061] Step S5: Analyze the stability of the ranging process based on the adaptive distance scale to obtain the ranging confidence level.

[0062] In one embodiment, two laser signals are modulated to form an interference weave grid during transmission, and the interference weave grid is analyzed to generate a photon weave density index, including:

[0063] Asynchronous frequency modulation of dual-wavelength lasers causes them to undergo continuous dynamic interference in the common transmission region, forming an interference weave grid. Specifically, this involves: applying sawtooth wave modulation to the optical frequency of the first laser beam, causing its frequency to periodically change linearly around the center value with an amplitude of 100 kHz and a rate of 1 kHz; and applying sinusoidal wave modulation to the optical frequency of the second laser beam, causing its frequency to periodically fluctuate around the center value with an amplitude of 50 kHz and a rate of 1.5 kHz.

[0064] Because the sawtooth and sine waves of the two beams of light have different waveforms and frequencies, the two laser beams produce an unsteady phase difference in the common transmission region due to different modulation laws. When they coincide in space, the positions of their constructive and destructive interference will move rapidly and non-uniformly in space with the change of instantaneous frequency difference. The positions of constructive and destructive interference are the bright and dark fringes. Over time, they form a light field grid that is constantly woven and reconstructed in spacetime, which is the interference weaving grid.

[0065] Spatiotemporal sampling of the interferometric braided mesh is performed to obtain a spatiotemporal image set. The spatiotemporal image set is then analyzed to obtain the mesh modulation depth. Specifically, this includes: spatiotemporal sampling of the interferometric braided mesh, acquiring an interferogram sequence within a complete modulation period at a frame rate of 15 kHz to obtain a spatiotemporal image set, wherein the complete modulation period is 2 milliseconds.

[0066] Analyze the light intensity change of each pixel in the spatiotemporal image set along the time axis and calculate the time series variance of its light intensity value; then statistically average the time series variances of all pixels in the image to obtain the average variance.

[0067] Pixels whose time series variance is greater than 30% of the average variance are identified and marked as high dynamic range (HMR) pixels. The grid modulation depth is obtained by dividing the number of HMR pixels by the total number of pixels in the image.

[0068] In one embodiment, two laser signals are modulated to form an interference weave grid during transmission, and the interference weave grid is analyzed to generate a photon weave density index. The method further includes:

[0069] The process involves identifying and analyzing bright interference fringe nodes in a spatiotemporal image set to generate node spatial entropy. Specifically, in the spatiotemporal image set, for each frame of the image, 70% of its light intensity value is used as a threshold to identify all pixels whose light intensity value exceeds this threshold. Among these pixels, those whose light intensity value is higher than their eight neighboring pixels are selected and these pixels are used as the bright interference fringe nodes of that frame of the image.

[0070] The entire image plane is evenly divided into ten concentric sector regions of equal area. Within a complete 2-millisecond sampling period, the total number of interference bright fringe nodes identified in all time frames is found, and the number of times the interference bright fringe nodes fall into each of the ten sector regions is counted.

[0071] Calculate the proportion of bright fringe nodes in each sector to the total number of bright fringe nodes. Multiply the proportion of each sector by the logarithm of that proportion to base 2. Then sum the products of all sectors and take the negative value to obtain the node spatial entropy.

[0072] The spatiotemporal distribution of optical vortices in the spatiotemporal image set is analyzed to obtain the vortex chain association length. Specifically, this includes: for each frame of spatiotemporal image in the spatiotemporal image set, the spatial second derivative of the normalized light intensity of each pixel is calculated, i.e., the curvature; pixels with curvature less than -0.1 are selected as candidate points; and the normalized light intensity values ​​of the eight neighboring pixels around each candidate point are obtained.

[0073] Two quantitative conditions must be met simultaneously: First, the light intensity value of a candidate point must be greater than the light intensity values ​​of all eight of its neighboring pixels; Second, in at least four main directions (up, down, left, and right), the light intensity values ​​of the pixels immediately adjacent to the center point and the diagonal pixels must satisfy a monotonically decreasing relationship. Specifically, for each direction, the light intensity values ​​at these three positions—from the center point to the immediately adjacent pixel, and then to the diagonal pixel on that direction—should decrease sequentially, and the difference between adjacent values ​​must be greater than 0.05. A candidate point that satisfies both of these conditions is an optical vortex in the frame image.

[0074] In the time dimension, three consecutive frames (corresponding to 0.2 milliseconds) are used as an analysis window. Within an analysis window, if the spatial distance between two optical vortices determined in two consecutive frames is less than 2 pixels, then the two are associated as the same vortex chain.

[0075] For each vortex chain, obtain the positions (coordinates) of all vortex points it contains on the image plane; calculate the standard deviation of the positions of all vortex points in each vortex chain, use it as the association length of the chain, and calculate the mean of the association lengths of all chains, which is the vortex chain association length.

[0076] The photon weaving density index is generated by fusing the grid modulation depth, node spatial entropy, and vortex chain association length. Specifically, the grid modulation depth, node spatial entropy, and vortex chain association length are normalized to the 0-1 interval, the grid modulation depth is exponentially calculated using the node spatial entropy as the exponent to obtain an intermediate value, and the intermediate value is multiplied by the vortex chain association length to obtain the photon weaving density index.

[0077] By applying asynchronous frequency modulation to dual-wavelength lasers to generate an interferometric braided mesh, and combining spatiotemporal sampling with multi-dimensional parameter analysis to generate a photon braiding density index, online sensing and dynamic compensation of optical path distortion can be achieved. This addresses the pain points of existing laser ranging methods, which rely on optical receiving components, are susceptible to high-frequency noise from environmental vibrations, and cannot be calibrated in real time. The interferometric braided mesh can accurately capture changes in the optical field caused by optical path distortion, and the fusion analysis of mesh modulation depth, node spatial entropy, and vortex chain correlation length can quantify the degree of optical field distortion. Measurement deviations can be corrected in real time without post-calibration, improving the accuracy and stability of ranging in complex environments such as high-speed moving vehicles, and reducing dependence on the environmental adaptability of optical receiving components.

[0078] In one embodiment, the displacement of each node in the interferometric braided mesh is analyzed based on the reflected laser signal to obtain a displacement vector field. The displacement vector field is then processed based on the photon braiding density index to generate wavefront distortion characteristics, including:

[0079] Based on reflected laser signals, the position changes of each node in the interferometric braided mesh are tracked to generate a node displacement vector field. Specifically, the spatiotemporal image sequence of the interferometric braided mesh is acquired at a frame rate of 15 kHz based on reflected laser signals. The interferometric bright fringe nodes identified in the spatiotemporal image set are directly used. In the time dimension, the correlation window is 0.2 milliseconds (corresponding to 3 consecutive frames).

[0080] Nodes with a spatial distance of less than 1 pixel unit and a light intensity difference of less than 10% between the candidate point and the current node are identified as the same node at different times. Only nodes whose lifespan spans the entire associated window are tracked, and their pixel displacement in the last frame is calculated based on their position coordinates in the first frame within the window.

[0081] Each pixel corresponds to an actual distance of 0.1 mm, which is used as a calibration coefficient. The pixel displacement of each node is multiplied by the calibration coefficient to obtain its actual physical displacement vector. The physical displacement vectors of all such nodes are integrated to generate a node displacement vector field.

[0082] Based on the node displacement vector field, the set formed by the change in the connection relationship of adjacent nodes due to displacement is identified, and the node connection reconstruction rate is obtained. Specifically, based on the node displacement vector field, in the first frame, all other nodes are identified as its adjacent nodes within a circular area with a radius of 0.3 mm centered on the actual position of each node, forming an initial connection set.

[0083] In the last frame, after updating the node positions based on the physical displacement vector, adjacent nodes are re-identified with the same radius to form the final connection set. The two sets are compared, and the number of connection pairs that initially existed but ultimately did not exist is counted as the number of broken connections, and the number of connection pairs that initially did not exist but ultimately existed is counted as the number of new connections.

[0084] The node connection reconstruction rate is obtained by dividing the sum of the number of broken connections and the number of new connections by the total number of initial connections in the initial connection set.

[0085] In the node displacement vector field, the displacement of different nodes is analyzed to obtain the displacement ripple correlation degree. Specifically, in the node displacement vector field, each node is taken as the source node in turn, and the displacement direction of the source node is its physical displacement vector; a one-dimensional analysis axis is established with the position of the source node in the first frame of the window as the origin, and the positive direction of the analysis axis is consistent with the displacement direction.

[0086] For other nodes, calculate the position difference vector between them and the source node in the first frame of the window, project this position difference vector onto the analysis axis, and the resulting scalar value is the radial distance component; then project the physical displacement vector of each other node onto the displacement direction of the source node, and the resulting scalar value is the projection value.

[0087] For all other nodes whose radial distance components are in the range of 0 to 0.5 mm, count the number of nodes. Divide the projection value of each node by its radial distance component to obtain multiple ratios. Calculate the average of these ratios, which is the displacement ripple correlation degree of the entire displacement vector field.

[0088] In one embodiment, the displacement of each node in the interferometric braided mesh is analyzed based on the reflected laser signal to obtain a displacement vector field. The displacement vector field is then processed based on the photon braiding density index to generate wavefront distortion characteristics. The method further includes:

[0089] Real-time acquisition of environmental data, including equivalent turbulence intensity, temperature, vibration amplitude, and vibration frequency;

[0090] Based on the correlation between environmental data and displacement ripples, the interference of the environment on the propagation of the optical path is analyzed, and the node anchorage rate is generated. Specifically, the parameters in the environmental data are normalized to the 0-1 range, and the weights of turbulence intensity, temperature, vibration amplitude and vibration frequency are assigned to 0.4, 0.2, 0.25 and 0.15, respectively. The four parameters are multiplied by their corresponding weights and then added together to obtain the environmental interference index.

[0091] Subtract the displacement ripple correlation from the environmental disturbance index to obtain the displacement field difference under environmental disturbance. Multiply the displacement field difference by 2 and calculate the reciprocal of its natural index (e is the base). Normalize the reciprocal to the 0-1 interval, which is the node anchorage rate.

[0092] Among them, turbulence intensity is the most important and fastest factor causing random distortion of the optical wavefront in the atmospheric channel. It directly causes intensity flicker, angle of arrival fluctuation and phase change of the laser beam. These effects distort the structure of the interference weave mesh, mainly manifested as irregular and rapid drift of node positions and frequent reconstruction of connection relationships. Therefore, it is given the highest weight of 0.4.

[0093] The vibration amplitude represents the impact of mechanical vibration on the optical path. Vibration can cause the overall offset or jitter of the transmitting and receiving optical platforms, thereby causing all nodes to produce relatively consistent directional displacements. This effect is global, so it is assigned a weight of 0.25.

[0094] The effects of temperature changes are relatively slow and gradient-like. They cause thermal expansion of optical components and supporting structures, which in turn slowly alters the optical path collimation and focal length. This is mainly manifested as the gradual scaling, rotation, or slow deformation of the interference mesh. Within the modulation period, its intensity is usually low, hence the weight is 0.2. The vibration frequency itself does not directly determine the magnitude of the displacement, but it determines the temporal characteristics of the vibration interference. This scheme uses a high-frequency sampling of 15kHz, which can capture most of the influence of the vibration frequency. The vibration frequency is mainly used to distinguish between high-frequency jitter and low-frequency drift. Its direct contribution to the stability index of node anchorage rate is relatively low, and it is mainly used as an auxiliary factor, hence the weight is 0.15.

[0095] Based on the photon weaving density index, different node displacements in the node displacement vector field are corrected to obtain the weaving weighted displacement field. Specifically, based on the node displacement vector field, each node is assigned a photon weaving density index corresponding to its spatial position. The photon weaving density index is used as a power to calculate the power of 2 to obtain an intermediate coefficient between 1 and 2.

[0096] Multiply the node anchorage rate by the intermediate coefficient, and then multiply by the physical displacement vector of the node to obtain its woven weighted displacement vector. Integrate the woven weighted displacement vectors of all nodes to form a woven weighted displacement field.

[0097] The node connection reconstruction rate, node anchorage rate and woven weighted displacement field are fused to generate wavefront distortion characteristic quantities. Specifically, the average modulus of the woven weighted displacement vector of all nodes in the woven weighted displacement field is calculated and used as the average displacement intensity.

[0098] Divide the 360-degree direction of all woven weighted displacement vectors into 12 30-degree sector regions, count the frequency of the direction of all woven weighted displacement vectors falling into each region, and calculate its Shannon entropy to obtain the displacement direction disorder; multiply the node connection reconstruction rate by (π divided by 2) to obtain the angle, and calculate the sine value of the angle.

[0099] Multiply the node anchorage ratio by π to obtain the angle, and calculate the cosine value of the angle; multiply the average displacement strength by the displacement direction disorder, and then multiply by (1 + sine value minus cosine value) to obtain the wavefront distortion characteristic quantity.

[0100] By combining the analysis of reflected laser signals to obtain the displacement vector field of nodes, and integrating the node connection reconstruction rate, node anchorage rate and braided weighted displacement field to generate wavefront distortion characteristics, online sensing and dynamic compensation of optical path distortion are achieved. At the same time, environmental data is integrated for collaborative analysis to accurately distinguish the influence of different environmental interferences. Based on the photon braiding density index, the node displacement is corrected to improve the accuracy and comprehensiveness of distortion sensing, enhance the anti-interference ability of ranging in complex environments, and improve the accuracy and stability of ranging.

[0101] In one embodiment, the motion trajectory of singular points in the wavefront distortion characteristic quantity is tracked, and the influence of optical path distortion on dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate phase distortion compensation coefficients, including:

[0102] From the wavefront distortion features, the motion trajectory of singular points is tracked and analyzed to generate the singular point trajectory curvature spectrum. Specifically, in the woven weighted displacement field, points whose woven weighted displacement vector magnitude exceeds twice the average displacement intensity and whose angle with the average displacement direction of the surrounding 8 adjacent nodes is greater than 60 degrees are identified as singular points.

[0103] At a time interval of 0.2 milliseconds, the spatial coordinates of each singular point are continuously tracked in the subsequent 4 time intervals to form its motion trajectory; for each motion trajectory, the instantaneous curvature formed by its three adjacent points is calculated in millimeters; all instantaneous curvatures of all trajectories are divided into multiple intervals with a width of 0.05 millimeters, and the number of instantaneous curvatures falling into each curvature interval is counted.

[0104] The distribution spectrum plotted in the coordinate system with the median of the curvature interval as the x-axis and the number of normalized values ​​as the y-axis is the curvature spectrum of the singular point trajectory.

[0105] Analyzing the curvature spectrum of singular point trajectories, identifying the hysteresis time and curvature span of the trajectories, and obtaining the singular point memory hysteresis factor, specifically includes: in the curvature spectrum of singular point trajectories, regions with instantaneous curvature greater than 0.2 per millimeter are designated as high curvature regions; for the motion trajectory of each singular point, the time points when its instantaneous curvature first enters and finally leaves the high curvature region are identified, and the difference between these two time points is calculated as the hysteresis time of the trajectory;

[0106] For all instantaneous curvatures in the high curvature region on the trajectory, calculate the difference between their maximum and minimum values, and use it as the curvature span of the trajectory;

[0107] Multiply the average hysteresis time of all trajectories by the average curvature span to obtain the singularity memory hysteresis factor.

[0108] Based on displacement ripple correlation, the phase winding effect of dual-wavelength lasers is analyzed to generate wavelength phase winding. Specifically, this includes: obtaining the composite wavelength of the dual-wavelength laser in millimeters; for the dual-wavelength laser, calculating the reciprocal of the ratio of each wavelength to the composite wavelength; multiplying the displacement ripple correlation by the singularity memory hysteresis factor, and then multiplying it by the reciprocal of the ratio of the corresponding wavelengths to obtain the first winding and the second winding, respectively; and substituting the first winding and the second winding into the hyperbolic tangent function to calculate the wavelength phase winding of each dual-wavelength laser.

[0109] Based on the node anchorage rate, the intensity of the effect of environmental disturbance on the trajectory of singular points is evaluated, and the deviation integral generated by the trajectory is calculated to generate the singular point misalignment path integral. Specifically, this includes: subtracting 1 from the reciprocal of the node anchorage rate to obtain the intensity coefficient of the effect of environmental disturbance on the trajectory of singular points; for the trajectory of each singular point, calculating the magnitude of the weighted displacement vector between its adjacent time points (interval of 0.2 milliseconds) to obtain the displacement magnitude sequence.

[0110] Multiply each displacement modulus in the displacement modulus sequence by the action intensity coefficient to obtain a set of weighted displacements. Calculate the sum of this set of weighted displacements and divide the sum by the total duration of the trajectory (0.8 milliseconds) to obtain the displaced path integral of the singular point. Calculate the mean of the displaced path integrals of all singular points, which is the singular point displaced path integral.

[0111] In one embodiment, the process of tracking the trajectory of singular points in the wavefront distortion characteristic quantity, analyzing the impact of optical path distortion on dual-wavelength laser phase measurement based on the trajectory, and generating a phase distortion compensation coefficient further includes:

[0112] The singularity memory hysteresis factor, wavelength phase winding degree, and singularity misalignment path integral are fused to obtain an equivalent distortion tensor matrix. Specifically, this includes: multiplying the singularity memory hysteresis factor and the singularity misalignment path integral to obtain an intermediate parameter; calculating the absolute value of the difference between the first wavelength phase winding degree and the second wavelength phase winding degree, and then multiplying the intermediate parameter by the absolute value of the difference to obtain the fusion factor.

[0113] The equivalent distortion tensor matrix is ​​obtained by multiplying the fusion factor by the phase winding degree of the first wavelength in the first row and first column; the equivalent distortion tensor matrix is ​​obtained by multiplying the fusion factor by the phase winding degree of the second wavelength in the first row and second column; the equivalent distortion tensor matrix is ​​obtained by multiplying the fusion factor by the singularity memory hysteresis factor in the second row and first column; and the equivalent distortion tensor matrix is ​​obtained by multiplying the fusion factor by the singularity misalignment path integral.

[0114] The equivalent distortion tensor matrix is ​​mapped onto the synthetic wavelength scale of the dual-wavelength laser and calculated to generate the phase distortion compensation coefficient. Specifically, this involves: calculating the sum of the absolute values ​​of the four elements of the equivalent distortion tensor matrix to obtain the absolute sum of the matrix; dividing the absolute sum of the matrix by the square of the synthetic wavelength to obtain the compensation value; multiplying the compensation value by the node anchorage ratio, taking the natural logarithm of the product, and then normalizing the natural logarithm to the 0-1 interval, which is the phase distortion compensation coefficient.

[0115] By accurately tracking the trajectory of singular points in wavefront distortion features, generating the singular point trajectory curvature spectrum and extracting the singular point memory hysteresis factor, and combining displacement ripple correlation analysis to analyze the phase entanglement effect of dual-wavelength lasers, the wavelength phase entanglement degree is obtained. Then, based on the node anchorage rate to assess the intensity of environmental disturbances, the singular point misalignment path integral is generated, and finally, the equivalent distortion tensor matrix is ​​obtained and mapped to generate phase distortion compensation coefficients. This achieves real-time online sensing and dynamic compensation of optical path distortion, avoiding the lag of traditional post-calibration, effectively suppressing the influence of high-frequency noise introduced by high-speed carrier vibration on dual-wavelength laser phase measurement, and improving the accuracy of absolute distance measurement.

[0116] In one embodiment, the phase distortion compensation coefficient is applied to the correction of the dual-wavelength laser phase to generate an adaptive distance scale, including:

[0117] Obtain the phase of a dual-wavelength laser signal;

[0118] Based on the phase distortion compensation coefficient, the differences in the influence of optical path distortion on the phase of each dual-wavelength laser are analyzed, and distortion contribution weights are generated. Specifically, the first wavelength phase winding degree and the second wavelength phase winding degree are added together to obtain the total winding degree; the first wavelength phase winding degree and the second wavelength phase winding degree are divided by the total winding degree to obtain the first initial weight and the second initial weight.

[0119] Multiply the phase distortion compensation coefficient by the first initial weight + (1 minus the phase distortion compensation coefficient multiplied by 0.5) to obtain the distortion contribution weight of the first wavelength; the distortion contribution weight of the second wavelength is calculated in the same way, thus obtaining the distortion contribution weight of each of the two wavelength lasers.

[0120] The phase of the dual-wavelength laser is calibrated based on the distortion contribution weight and the phase distortion compensation coefficient to generate an adaptive distance scale. Specifically, this includes obtaining the initial measured phase of each of the two wavelength lasers, which is the original phase value obtained after receiving the reflected laser signal.

[0121] Multiply the distortion contribution weight of the first wavelength by the initial measurement phase of the first wavelength, and then multiply the distortion contribution weight of the second wavelength by the initial measurement phase of the second wavelength to obtain the composite phase; multiply the phase distortion compensation coefficient by the node anchorage rate to obtain the dynamic reliability factor; multiply the dynamic reliability factor by the composite phase to obtain the calibrated composite phase.

[0122] The adaptive distance scale can be obtained by multiplying the calibrated composite phase by the composite wavelength and then dividing by twice pi (2π).

[0123] In one embodiment, the stability of the ranging process is analyzed based on an adaptive distance scale to obtain the ranging confidence level, including:

[0124] The numerical sequence formed by the adaptive distance scale in continuous measurement is analyzed to generate the scale evolution inertia. Specifically, the following steps are taken: a sequence is formed by the adaptive distance scale values ​​of the most recent 15 consecutive measurements. The difference between two adjacent values ​​in the sequence is calculated by subtracting the previous value from the next value. Multiple differences are obtained. If the difference is greater than 0, it is marked with a positive sign (+). If the difference is less than zero, it is marked with a negative sign (-). If the difference is equal to 0, the sign of the previous difference is used to obtain the sign sequence.

[0125] The number of segments in a statistical symbol sequence that contain consecutive identical symbols, with the minimum standard for consecutive symbols being two identical symbols, can be used to calculate the scaling inertia by dividing the sequence length by the number of segments.

[0126] Based on the node anchorage ratio and phase distortion compensation coefficient, the ability to maintain the effectiveness of the adaptive distance scale is analyzed, and the hysteresis resistance value is generated. Specifically, the node anchorage ratio and the phase distortion compensation coefficient are multiplied to obtain the comprehensive resistance factor, and the absolute value of the difference between the phase distortion compensation coefficient and 0.5 is calculated and used as the instantaneous imbalance degree.

[0127] Multiply the overall resistance factor by (1 minus the instantaneous imbalance) and normalize the result to the hysteresis resistance value.

[0128] The scaling evolution inertia and hysteresis resistance values ​​are fused to generate ranging confidence. Specifically, this includes: multiplying the scaling evolution inertia and hysteresis resistance values ​​to obtain parameters; calculating the absolute value of the difference between the node anchorage rate at the current time and the node anchorage rate at the previous time, and multiplying the absolute value by the phase distortion compensation coefficient to obtain a correction term.

[0129] After subtracting the correction term from the parameters, the calculation result is normalized to the 0-1 interval, which is the ranging confidence level. When the ranging confidence level is >0.8, the adaptive distance scale is considered reliable and is used as the distance measured by the dual-wavelength laser; otherwise, the calculation is repeated from step S1 to step S5 until the ranging confidence level is >0.8. The maximum number of recalculations is 5. If the number of recalculations exceeds 5, manual intervention is required.

[0130] By generating distortion contribution weights through phase distortion compensation coefficients, the initial measurement phase of dual-wavelength lasers is accurately corrected and an adaptive distance scale is generated. Simultaneously, the ranging confidence level is generated by fusing the scale evolution inertia and hysteresis resistance values. This achieves real-time dynamic correction of the dual-wavelength laser phase, effectively offsetting the interference of high-frequency noise introduced by high-speed carrier vibration on phase measurement, improving the adaptability of the adaptive distance scale to complex environments, and evaluating the reliability of the adaptive distance scale through the ranging confidence level. This solves the problem of lag in traditional post-calibration and improves the accuracy of dual-wavelength laser ranging.

[0131] In one embodiment, a system employing dual-wavelength laser ranging, applied to the aforementioned method for dual-wavelength laser ranging, includes:

[0132] The laser interferometer is used to emit two laser signals of different wavelengths, modulate the two laser signals so that the two laser beams form an interference weave grid during transmission, and analyze the interference weave grid to generate the photon weave density index.

[0133] The distortion analysis unit is used to acquire the reflected laser signal, analyze the displacement of each node in the interference braided mesh based on the reflected laser signal, obtain the displacement vector field, and process the displacement vector field based on the photon braiding density index to generate wavefront distortion characteristic quantities.

[0134] The distortion compensation unit is used to track the motion trajectory of singular points in the wavefront distortion characteristic quantity, and analyze the influence of optical path distortion on dual-wavelength laser phase measurement based on the motion trajectory to generate phase distortion compensation coefficients.

[0135] The correction unit is used to apply the phase distortion compensation coefficient to the phase correction of the dual-wavelength laser and generate an adaptive distance scale;

[0136] The judgment unit is used to analyze the stability of the ranging process based on the adaptive distance scale and obtain the ranging confidence level.

[0137] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of dual-wavelength laser ranging, characterized by, The method comprises the following steps: Step S1, two laser signals of different wavelengths are emitted, the two laser signals are modulated, the two laser beams form an interference woven grid during transmission, and the interference woven grid is analyzed to generate a photon woven density index, which comprises: Asynchronous frequency modulation is performed on the dual-wavelength laser to cause continuous dynamic interference in the common transmission area to form an interference woven grid; The interference woven grid is spatio-temporally sampled to obtain a set of spatio-temporal images, and the set of spatio-temporal images is analyzed to obtain a grid modulation depth; Interference bright fringe nodes in the set of spatio-temporal images are identified and analyzed to generate a node spatial entropy; The spatio-temporal distribution of optical vortices in the set of spatio-temporal images is analyzed to obtain a vortex chain correlation length; The grid modulation depth, the node spatial entropy, and the vortex chain correlation length are fused to generate a photon woven density index; Step S2, the reflected laser signal is obtained, the displacement of each node in the interference woven grid is analyzed based on the reflected laser signal to obtain a displacement vector field, and the displacement vector field is processed based on the photon woven density index to generate a wavefront distortion feature quantity; Step S3, the motion trajectory of a singular point in the wavefront distortion feature quantity is tracked, and the influence of optical path distortion on dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate a phase distortion compensation coefficient; Step S4, the phase distortion compensation coefficient is applied to the correction of the dual-wavelength laser phase to generate an adaptive distance scale; Step S5, the stability of the ranging process is analyzed according to the adaptive distance scale to obtain a ranging confidence.

2. The method of claim 1, wherein, The displacement of each node in the interference woven grid is analyzed based on the reflected laser signal to obtain a displacement vector field, and the displacement vector field is processed based on the photon woven density index to generate a wavefront distortion feature quantity, which comprises: Based on the reflected laser signal, the position changes of each node in the interference woven grid are tracked to generate a node displacement vector field; Based on the node displacement vector field, a set formed by the change of the connection relationship between adjacent nodes due to displacement is identified to obtain a node connection reconstruction rate; In the node displacement vector field, the displacement of different nodes is analyzed to obtain a displacement ripple correlation degree.

3. The method of claim 2, wherein the method further comprises: The displacement of each node in the interference woven grid is analyzed based on the reflected laser signal to obtain a displacement vector field, and the displacement vector field is processed based on the photon woven density index to generate a wavefront distortion feature quantity, which further comprises: Real-time acquisition of environmental data; Based on the environmental data and the displacement ripple correlation degree, the interference of the environment on the light path propagation is analyzed to generate a node anchoring rate; Based on the photon woven density index, the displacement of different nodes in the node displacement vector field is corrected to obtain a woven weighted displacement field; The node connection reconstruction rate, the node anchoring rate, and the woven weighted displacement field are fused to generate a wavefront distortion feature quantity.

4. The method of claim 3, wherein, The motion trajectory of a singular point in the wavefront distortion feature quantity is tracked, and the influence of optical path distortion on dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate a phase distortion compensation coefficient, which comprises: From the wavefront distortion feature quantity, the motion trajectory of the singular point is tracked and analyzed to generate a singular point trajectory curvature spectrum; The singular point trajectory curvature spectrum is analyzed to identify the hysteresis time and curvature span of the trajectory to obtain a singular point memory hysteresis factor; Based on the displacement ripple correlation degree, the phase wrapping effect of the dual-wavelength laser is analyzed to generate a wavelength phase wrapping degree; Based on the node anchoring rate, the influence strength of environmental disturbance on the singular point motion trajectory is evaluated, and the deviation integral generated by the motion trajectory is calculated to generate a singular point dislocation path integral.

5. The method of claim 4, wherein the method further comprises: The motion trajectory of the singular point in the wavefront distortion characteristic quantity is tracked, and the influence of the optical path distortion on the dual-wavelength laser phase measurement is analyzed based on the motion trajectory to generate a phase distortion compensation coefficient, and the phase distortion compensation coefficient includes: The singular point memory hysteresis factor, the wavelength phase wrapping degree, and the singular point dislocation path integral are fused to obtain an equivalent distortion tensor matrix; The equivalent distortion tensor matrix is mapped to the combined wavelength scale of the dual-wavelength laser and calculated to generate a phase distortion compensation coefficient.

6. The method of claim 5, wherein, The phase distortion compensation coefficient is applied to the correction of the dual-wavelength laser phase to generate an adaptive distance scale, including: Obtaining the phase of the dual-wavelength laser signal; Based on the phase distortion compensation coefficient, the influence difference of the optical path distortion on the respective phases of the dual-wavelength laser is analyzed to generate a distortion contribution weight; According to the distortion contribution weight and the phase distortion compensation coefficient, the dual-wavelength laser phase is calibrated to generate an adaptive distance scale.

7. The method of claim 6, wherein the method further comprises: According to the adaptive distance scale, the stability of the ranging process is analyzed to obtain a ranging confidence, including: The numerical sequence formed by the adaptive distance scale in continuous measurement is analyzed to generate a scale evolution inertia; Based on the node anchoring rate and the phase distortion compensation coefficient, the ability to maintain the effectiveness of the adaptive distance scale is analyzed to generate a hysteresis resistance value; The scale evolution inertia and the hysteresis resistance value are fused to generate a ranging confidence.

8. A system for dual-wavelength laser ranging, applied to the method for dual-wavelength laser ranging according to any one of claims 1-7, characterized in that, Including: A laser interference unit for emitting two laser signals of different wavelengths, modulating the two laser signals, forming an interference weaving grid in the transmission process of the two lasers, and analyzing the interference weaving grid to generate a photon weaving density index; A distortion analysis unit for obtaining reflected laser signals, analyzing the displacement of each node in the interference weaving grid based on the reflected laser signals to obtain a displacement vector field, and processing the displacement vector field based on the photon weaving density index to generate wavefront distortion characteristic quantities; A distortion compensation unit for tracking the motion trajectory of the singular point in the wavefront distortion characteristic quantity, and analyzing the influence of the optical path distortion on the dual-wavelength laser phase measurement based on the motion trajectory to generate a phase distortion compensation coefficient; A correction unit for applying the phase distortion compensation coefficient to the correction of the dual-wavelength laser phase to generate an adaptive distance scale; A judgment unit for analyzing the stability of the ranging process according to the adaptive distance scale to obtain a ranging confidence.

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