Parameter determination method of curved reflector and coaxial laser radar

Abstract

The present invention provides a method for determining parameters of a curved reflector and a coaxial laser radar. The curved reflector is a single-curved cylindrical curved reflector mounted on the coaxial laser radar. The coaxial laser radar includes a cylindrical light-transmitting housing. The method comprises: determining the radius of curvature of a paraxial portion of a curve corresponding to the curved reflector based on the refractive index of the cylindrical light-transmitting housing for laser light, the outer diameter and inner diameter of the cylindrical light-transmitting housing, wherein the paraxial portion represents a preset region of the curve closest to the central axis of the cylindrical light-transmitting housing; substituting the radius of curvature of the paraxial portion of the curve and a preset conic coefficient into a standard equation for an aspheric curve to obtain an initial expression; and determining each aspheric coefficient in the initial expression using a damped least squares method and a preset evaluation function to obtain a curve expression for the curve. The present invention can improve the detection performance of the coaxial laser radar.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to a method for determining parameters of a curved reflector and a coaxial laser radar. Background Art

[0002] LiDAR, a precision sensing system, boasts excellent performance, including high ranging accuracy, high angular resolution, and high repetition rate. It is widely used in intelligent robots, autonomous tractors, intelligent / assisted driving, and security. Currently, LiDAR typically uses the rotation of the transceiver module or a plane mirror to rotate the reflected beam around its axis for scanning and detection. Compared to the former, the plane mirror rotation scanning method has a smaller and lighter motor drive load, making it easier to adjust dynamic balance. The system can achieve higher scanning frequencies and has greater reliability, attracting considerable attention.

[0003] As a critical component of LiDAR, the transparent housing protects and supports the radar, ensuring long-term, reliable operation. Because the rotating scanning beam is circularly symmetrical, the corresponding transparent housing is typically cylindrical. However, the inclusion of a transparent housing can affect the beam's transmission characteristics, reducing the LiDAR's angular resolution and detection accuracy. Summary of the Invention

[0004] In view of this, the present invention provides a method for determining parameters of a curved reflector and a coaxial laser radar, which can solve the problem of reduced laser radar detection performance caused by the laser radar's transparent shell.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining parameters of a curved reflector, wherein the curved reflector is a single-bent cylindrical curved reflector, and the curved reflector is installed in a coaxial laser radar, wherein the coaxial laser radar includes a cylindrical light-transmitting housing, including:

[0006] Determine the curvature radius of the paraxial portion of the curve corresponding to the curved reflector based on the refractive index of the cylindrical light-transmitting housing for laser light, the outer diameter and the inner diameter of the cylindrical light-transmitting housing, wherein the paraxial portion represents a predetermined region of the curve closest to the central axis of the cylindrical light-transmitting housing;

[0007] Substituting the curvature radius of the paraxial portion of the curve and a preset conic coefficient into the standard equation of the aspheric curve to obtain an initial expression;

[0008] The various aspheric coefficients in the initial expression are determined by using a damped least square method and a preset evaluation function to obtain a curve expression of the curve.

[0009] In a second aspect, an embodiment of the present invention provides a curved reflector, which is installed on a coaxial laser radar. The coaxial laser radar includes a cylindrical light-transmitting shell, and the parameters of the curved reflector are determined by the method described in claims 1 to 6.

[0010] In a third aspect, an embodiment of the present invention provides a coaxial laser radar, which includes a cylindrical light-transmitting shell and a curved reflector, wherein the curved reflector is a single-bent cylindrical curved reflector, wherein the parameters of the curved reflector are determined by the methods described in claims 1 to 6.

[0011] In a fourth aspect, an embodiment of the present invention provides a terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method described in the first aspect or any possible implementation of the first aspect are implemented.

[0012] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the method described in the first aspect or any possible implementation of the first aspect.

[0013] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0014] An embodiment of the present invention proposes a method for determining the parameters of a curved reflector, wherein the curved surface of the curved reflector is determined by determining various parameters of a curve on the curved surface of the curved reflector, and the effect of the cylindrical shell on the collimated light beam is compensated by the curved reflector to reduce the influence of the cylindrical transparent shell on the collimated detection light beam, thereby solving the problem of light spot divergence caused by the transparent shell in practical applications, improving the measurement accuracy of the laser radar and the receiving efficiency of the light-receiving and light-receiving path to increase the radar range. Moreover, the present invention does not introduce additional optical calibration elements to compensate for the divergence effect caused by the transparent shell on the collimated light beam, but instead compensates by modifying the surface shape of the reflector, making the system structure more compact and more flexible and convenient to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1Schematic diagram of the effect of a cylindrical light-transmitting housing on the collimated light beam characteristics of a laser radar provided by an embodiment of the present invention;

[0017] Figure 2 This is a flow chart of a method for determining parameters of a curved reflector provided by an embodiment of the present invention;

[0018] Figure 3 This is a horizontal cross-sectional diagram of a cylindrical light-transmitting housing provided by an embodiment of the present invention;

[0019] Figure 4 Schematic diagram of incident light with cross section yoz reflected by a curved reflector provided by an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of paraxial light transmission on an Xoy projection surface provided by an embodiment of the present invention;

[0021] Figure 6 1 is a schematic diagram of an even-order aspheric surface equation curve in a y′oh coordinate system provided by an embodiment of the present invention;

[0022] Figure 7 3 is a functional relationship diagram of various order terms of aspheric surfaces in the y′oh coordinate system provided by an embodiment of the present invention.

[0023] Figure 8 This is a point diagram of the exit surface and the 10m image plane of a plane reflector provided by an embodiment of the present invention in a sequential mode with Vx=0°, Vz=0° field of view;

[0024] Figure 9 This is a schematic diagram of a coaxial optical path curved reflector transceiver system provided by an embodiment of the present invention;

[0025] Figure 10 It is a coaxial optical path model provided by an embodiment of the present invention;

[0026] Figure 11 is an optimized aspheric curve diagram provided by an embodiment of the present invention;

[0027] Figure 12 : is a correction curve diagram of various order aspheric terms after optimization provided by an embodiment of the present invention;

[0028] FIG13( a ) is a point diagram of the output surface and the target surface of the field of view with Vx=0°, Vz=0° in a sequential mode provided by an embodiment of the present invention;

[0029] FIG13( b ) is a point diagram of the output surface and the target surface of the field of view with Vx=0°, Vz=1° in a sequential mode provided by an embodiment of the present invention;

[0030] FIG13( c ) is a point diagram of the output surface and the target surface in a sequential mode with Vx=0°, Vz=-1° provided by an embodiment of the present invention;

[0031] FIG13( d ) is a point diagram of the output surface and the target surface in a sequential mode with Vx=1° and Vz=0° provided by an embodiment of the present invention;

[0032] FIG13( e ) is a point diagram of the output surface and the target surface in a sequential mode with Vx=-1°, Vz=0° provided by an embodiment of the present invention;

[0033] Figure 14 This is a result diagram comparing a simulated flat reflector and a curved reflector in a non-sequential mode provided by an embodiment of the present invention;

[0034] Figure 15 1 is a schematic structural diagram of a device for determining parameters of a curved reflector provided in an embodiment of the present invention;

[0035] Figure 16 is a schematic diagram of a terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

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

[0038] Figure 1 Schematic diagram of the effect of the cylindrical light-transmitting housing of the laser radar on the collimated beam characteristics provided by the embodiment of the present invention. Figure 1 As shown, since the light beam rotation scanning is distributed in a circularly symmetrical manner, the light-transmitting housing that matches it is usually a cylindrical structure.

[0039] To ensure measurement accuracy, the laser radar must align the light transmitting and receiving paths before each measurement to make the light transmitting and receiving paths parallel so that valid data can be observed. This process is called light beam collimation, and the resulting light beam is called a collimated beam.

[0040] The introduction of a transparent shell will affect the beam transmission characteristics. After the laser beam is collimated by the transmitting lens, it is transmitted parallel to the z-axis. The plane reflector is at a 45-degree angle to the horizontal plane and rotates around the z-axis. The beam is reflected by the reflector and then emitted horizontally. The cylindrical transparent shell has different effects on the beam in the vertical section parallel to the z-axis and the horizontal section perpendicular to the z-axis. Figure 1 As shown, the z axis is the cylindrical axis. In the section parallel to the cylindrical axis, as shown Figure 1 In the vertical cross section, the light-transmitting housing acts as a parallel plate structure without changing the transmission direction of the light beam.

[0041] However, in the section perpendicular to the cylinder axis, i.e. Figure 1 In the horizontal cross-section, the transparent shell acts like a negative meniscus lens to diverge the light beam. The collimated light beam passes through the plane reflector and then through the cylindrical shell. The transparent shell causes the originally collimated light beam to diverge to a certain extent, which has a great impact on the detection angle resolution and accuracy of the lidar system.

[0042] To solve this problem, an embodiment of the present invention provides a method for determining parameters of a curved reflector, see Figure 2 , which shows a flow chart of the implementation of the method for determining parameters of a curved reflector provided by an embodiment of the present invention, and is described in detail as follows:

[0043] In step 201, the curvature radius of the paraxial portion of the curve corresponding to the curved reflector is determined based on the refractive index of the cylindrical light-transmitting housing for the laser, the outer diameter length and the inner diameter length of the cylindrical light-transmitting housing. The paraxial portion is used to represent a preset area of the curve closest to the central axis of the cylindrical light-transmitting housing.

[0044] In an embodiment of the present invention, the curved reflector is a single-curved cylindrical reflector, which is installed in a coaxial laser radar comprising a cylindrical light-transmitting housing. Compared to a double-curved free-form reflector, the single-curved cylindrical reflector employed in this embodiment of the present invention has a simpler mirror structure and is easier to manufacture, thus reducing production costs.

[0045] In a possible implementation, the refractive index of the cylindrical light-transmitting housing to the laser light is determined according to the material of the cylindrical light-transmitting housing and the operating wavelength of the laser light.

[0046] Figure 3 This is a horizontal cross-sectional diagram of a cylindrical light-transmitting housing provided by an embodiment of the present invention, combined with Figure 1 and Figure 3 The outer diameter of the cylindrical light-transmitting shell is R1, and the inner diameter is R2.

[0047] In a possible implementation, the curvature radius of the paraxial portion of the curved reflector is determined according to a first formula, which is:

[0048]

[0049] Among them, R G is the curvature radius of the paraxial part of the curved reflector, n is the refractive index of the cylindrical light-transmitting shell to the laser, R1 is the outer diameter of the cylindrical light-transmitting shell, and R2 is the inner diameter of the cylindrical light-transmitting shell.

[0050] The following is combined with Figure 1 , Attachment Figure 3 To the attached Figure 5 The derivation process of the first formula is described.

[0051] Combine Figure 1 In the embodiment of the present invention, the cross section perpendicular to the x-axis is referred to as a vertical cross section, and the cross section perpendicular to the z-axis is referred to as a horizontal cross section. Figure 4 Schematic diagram of incident light with cross section yoz reflected by a curved reflector provided by an embodiment of the present invention, where cross section yoz is a cross section perpendicular to the x-axis.

[0052] Consider the normal vector characteristics and beam vector relationship of each section equation F(0,y,z)=0 of the curved reflector on the cross section perpendicular to the x-axis. The light beam on the y-axis is at position (0,y,0) with an incident vector S=(0,0,1) and is incident on the curved reflector F(x,y,z)=0 and the section equation F(0,y,z)=0 of the yoz plane. Since the cylindrical shell on this cross section forms an equivalent effect of a parallel plate, it will not affect the direction of the transmitted light beam. Therefore, the section equation F(0,y,z)=0 is required to be a section L equation. The section L equation is:

[0053]

[0054] Wherein, L0 is the length of the transversal line L, where the transversal line L coincides with the origin o of the coordinate axis.

[0055] After determining the intercept equation, combined with Figure 4 According to the surface continuity relationship, the required curved surface can be formed by scanning along the curve G with the tangent line L as the generatrix, that is, the curved surface of the curved reflector in the embodiment of the present invention. Assume that the equation of the curve G is:

[0056]

[0057] Since the reflecting surface is a single curved surface, the curve G is in the plane perpendicular to the transversal line L, and the equation of the curve G can be transformed into:

[0058]

[0059] Through this analytical model, the problem of solving the three-dimensional space surface is transformed into the problem of solving the curve G, which greatly simplifies the system parameter relationship and design difficulty, and is conducive to subsequent design optimization.

[0060] Combined with the above analysis, the equation of the intercept L F(0,y,z)=0, that is Its normal vector is The reflection vector R(0,0,0)=(0,1,0), and the light rays of this curve are collimated and pass through the transparent housing while the angle remains unchanged.

[0061] In order to obtain the appropriate curvature radius of curve G near section yoz, it is assumed that the curvature radius of curve G in the near-axis part is R G The circle, its equation can be expressed as:

[0062]

[0063] The surface formed by scanning is a conical surface, and the equation is:

[0064]

[0065] The normal vector is:

[0066]

[0067] For the light at the paraxial position P(x′,0,0), analyze the light transmission characteristics of the paraxial light path on the projection surface xoy. Figure 5 This is a schematic diagram of paraxial light transmission on the xoy projection surface provided by an embodiment of the present invention. Figure 4 and Figure 5 , the intersection of the light at position P(x′,0,0) and the reflecting surface is The normal vector at the reflection point is:

[0068]

[0069] The reflected ray vector is:

[0070]

[0071] Combine Figure 5 According to the paraxial ray tracing relationship on the projection surface xoy, it can be calculated that when the shell beam compensation condition is met, the angle between the outgoing light and the y-axis is:

[0072]

[0073] The equivalent curvature radius on the projection surface can be obtained It is also possible to combine the relationship of the lens, the outer diameter R1, the inner diameter R2, and the refractive index n of the shell form an equivalent focal length at the center of the circle For a concave lens, the reflector needs to be of equal size at the center o, with the opposite focal length -f', so that the combined focal length of the reflector and the housing is infinite and does not produce an angular deflection effect on the light beam, thus obtaining From the paraxial relationship of the reflected light vector, we can get:

[0074]

[0075] From this we can get:

[0076]

[0077] In step 202, the curvature radius of the paraxial portion of the curve and the preset conic coefficient are substituted into the standard equation of the aspheric curve to obtain an initial expression.

[0078] In the embodiment of the present invention, from the perspective of spatial projection relationship, the paraxial region of the curve G is the region with a curvature radius of R G The spherical curve of the x-axis, the light and the reflection surface cross section are elliptical, and the ratio of the major axis to the minor axis is The radius of curvature at its vertex is After the radius of curvature of the paraxial region is determined, it is necessary to optimize and calculate the appropriate mirror parameters. The reflection surface formed by curve G is a single curved cylinder with a straight generatrix parallel to the z' axis on the coordinate system xy'z' rotated 45 degrees clockwise about the x-axis of the coordinate system xyz. According to the structural characteristics of the system, curve G is symmetrically distributed about the generatrix L, and the ideal curve G can be approximated by an even-order aspheric curve. Because even-order aspheric curves have many parameter variables that need to be determined, they are prone to falling into local minima when optimized using the damped least squares method. Without suitable initial values, the more variables there are, the more difficult it is to obtain ideal results. Therefore, the idea of optimization design is to minimize the number of variables and set suitable initial values.

[0079] To facilitate understanding of the present invention, the coordinate system involved in the embodiments of the present invention is described. Figure 1 The initial coordinate system oxyz is shown. The z-axis and y-axis in the initial coordinate system are rotated 45° clockwise about the x-axis to obtain the coordinate system oxy′z′, as shown in Figure 4 As shown. The curve G corresponding to the curved reflector is symmetrically distributed about the intercept L, that is, the y′ axis. Based on this, the y′oh coordinate system is established. In the y′oh coordinate system, the y′ axis is Figure 4The intersection of curve G and the y'-axis is the origin of the y'oh coordinate system. Curve G and the y'-axis form a plane. The h-axis lies on this plane, passes through the origin of the y'oh coordinate system, and is perpendicular to the y'-axis of the y'oh coordinate system. After determining the expression of curve G, the desired curved surface is formed by scanning along curve G with the intersection line L as the generatrix, i.e., the curved surface of the curved reflector in the embodiment of the present invention. Based on this, in the embodiment of the present invention, the process of determining the parameters of the curved reflector is the process of determining the various parameters of the curve expression of curve G.

[0080] At this time, the ideal curve G can be approximated by an even-order aspheric curve.

[0081] According to the standard equation form of even-order aspheric curve:

[0082]

[0083] Where y′(h) is used to express the mapping relationship between the value of y′ and the value of h in the y′oh coordinate system. The y′ axis is perpendicular to the h axis. o is the origin of the y′oh coordinate system. The curve is symmetrical about the y′ axis. o is the intersection of the curve and the y′ axis. k is the cone coefficient. r is the curvature radius of the near-axis part of the curve. a4, a6, a8, a 10 、a 12 、a 14 are the aspheric coefficients of each order. Combining the above paraxial beam analysis, we can determine the ideal radius of curvature at the center of the reflective surface. Curve G is a spherical curve near section yoz. The aspheric terms corresponding to the aspheric coefficients of each order can be considered as modifying curve G using different functional relationships to approximate the ideal curve.

[0084] Figure 6 is a schematic diagram of an even-order aspheric surface equation curve in a y′oh coordinate system provided by an embodiment of the present invention, Figure 7 3 is a functional relationship diagram of various order terms of aspheric surfaces in the y′oh coordinate system provided by an embodiment of the present invention. Figure 7 It shows that when the aspheric coefficients of each order are 1, the aspheric term and the normalized radial distance h / h m Relationship, h m is the maximum radial distance. The higher the coefficient order, the more obvious the correction is for large radial distances, while the smaller the effect is on the aspheric surface for small radial distances. In order to analyze the influence of each order coefficient, Taylor expansion is performed on the standard equation of the even-order aspheric curve, and the following is obtained:

[0085]

[0086] From the above formula, we can see that the cone coefficient k has an impact on all high-order terms.

[0087] Based on this, the initial expression is:

[0088]

[0089] Among them, y′(h) is used to represent the mapping relationship between the value of y′ and the value of h in the y′oh coordinate system. The y′ axis is perpendicular to the h axis. o is the origin of the y′oh coordinate system. The curve is symmetrical about the y′ axis. o is the intersection of the curve and the y′ axis. k is used to represent the preset cone coefficient. r is used to represent the curvature radius of the near-axis part of the curve. a4, a6, a8, a 10 、a 12 、a 14 is the aspheric coefficient.

[0090] It can be seen that if we want to determine the curve expression of the curve, we need to determine the values of r, k and the aspheric coefficients of each order a4, a6, a8, a 10 、a 12 、a 14 value.

[0091] Among them, r is the curvature radius of the paraxial part of the curve corresponding to the curved reflector, that is, r = R G .

[0092] In one possible implementation, k is a preset value, such as an empirical value. In another possible implementation, from the above analysis, it can be seen that the cone coefficient k affects all high-order terms. To simplify the calculation, k is equal to -1, and the initial expression is:

[0093]

[0094] Among them, y′(h) is used to represent the mapping relationship between the value of y′ and the value of h in the y′oh coordinate system. The y′ axis is perpendicular to the h axis. o is the origin of the y′oh coordinate system. The curve is symmetrical about the y′ axis. o is the intersection of the curve and the y′ axis. r is used to represent the curvature radius of the near-axis part of the curve. a4, a6, a8, a 10 、a 12 、a 14 is the aspheric coefficient.

[0095] In step 203, each aspheric coefficient in the initial expression is determined by using the damped least square method and a preset evaluation function to obtain a curve expression of the curve.

[0096] In one possible implementation, the evaluation function is:

[0097]

[0098] By selecting s points (x i ,y i ), i = 1, ..., s, x i and y iRespectively represent the horizontal distance and vertical distance of the target point from the optical axis. For example, s=9, that is, 9 points are selected on the target surface, among which x1=-100mm, y1=-100mm; x2=-100mm, y2=0mm; x3=-100mm, y3=100mm; x4=0mm, y4=-100mm; x5=0mm, y5=0mm; x6=0mm, y6=100mm; x7=100mm, y7=-100mm; x8=100mm, y8=0mm; x9=100mm, y9=100mm, and the field of view corresponding to each point is divided into the form of Gaussian 3 rings and 6 arms to divide the light beam incident on the aperture of the receiving lens, and calculate the distance V between the intersection point of the light beam and the receiving photosensitive surface and the intersection point of the main light and the receiving photosensitive surface. The weight of each point is preset, so in the above evaluation function F, W i represents the weight, V i is the current value, T i is the target value.

[0099] The correction of each order aspheric coefficient function is separated, that is, the correction of the curve G by the fourth order aspheric coefficient a4 is only related to h 4 When a4=0, the radial distance h 4 It does not produce correction effect on the curve. According to the above paraxial relationship calculation, the curvature radius of the paraxial part of the curve r = R G , the cone coefficient k is selected as -1, and the values of the curvature radius and the cone coefficient are determined to reduce two variables in the aspheric optimization. In the paraxial region, the effects of the various order aspheric terms on the curve are very small. For the beam far from the paraxial region, the optimized aspheric reflector obtained by optimizing the aspheric coefficient is used to supplement the beam divergence of the transparent shell. The various order aspheric coefficients are used as variables and optimized in the following order: a4 is set as a variable, a6, a8, a 10 、a 12 、a 14 The aspheric coefficients of each order are set to zero, and the damped least squares method of the software is used to optimize and obtain the optimal a4. The evaluation functions before and after optimization are compared. If the change of the evaluation function does not exceed the threshold δF, the optimization is stopped; if the change of the evaluation function exceeds the evaluation threshold δF, the value of a4 is fixed and a6 is set as a variable to continue optimization, and then the optimal a6 is obtained by the damped least squares method optimization. The evaluation functions before and after optimization are compared. If the change of the evaluation function does not exceed the evaluation threshold δF, the optimization is stopped. If the change of the evaluation function exceeds the evaluation threshold δF, the values of a4 and a6 are fixed and a8 is set as a variable, and the optimal a8 is obtained by the damped least squares method optimization. The above steps are repeated until the change of the evaluation function does not exceed the threshold, or until the optimization of the aspheric coefficients of each order is completed, and the entire optimization process is completed.

[0100] In the embodiment of the present invention, the process of obtaining the aspheric coefficients of each order is as follows:

[0101] A4, A6, A8, A 10 、a 12 、a 14 Arrange in the preset order to obtain the sorting results;

[0102] The aspheric coefficients in the sorting results are optimized in sequence by the damped least squares method until the absolute value of the change in the evaluation function is less than or equal to the preset threshold. x When optimizing, a x Set as a variable and set the sort result at a x The value of the previously optimized coefficient is set as the optimal solution of the coefficient, and the value of the coefficient at a in the sorting result is set as the optimal solution of the coefficient. x The value after that is set to 0, a x is any aspheric coefficient in the sorted results.

[0103] In a possible implementation, in the sorting result, the aspheric coefficients are a4, a6, a8, a 10 、a 12 、a 14 , the aspheric coefficients in the sorting results are optimized in sequence by the damped least squares method until the change in the evaluation function is less than or equal to the preset threshold, including:

[0104] Set a4 as a variable, and set a6, a8, a 10 、a 12 、a 14 The value of is set to 0, and the damped least squares method is used to optimize to obtain the optimal solution of a4. The absolute value of the change in the evaluation function before and after the optimization of a4 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a4 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, and the values of other aspheric coefficients are 0;

[0105] If the absolute value of the change in the evaluation function before and after optimizing a4 is greater than the preset threshold, set a6 as a variable, set the value of a4 as the optimal solution of a4, and set a8 and a 10 、a 12 、a 14 The value of is set to 0, and the damped least squares method is used to optimize to obtain the optimal solution of a6. The absolute value of the change in the evaluation function before and after the optimization of a6 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a6 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, and the values of other aspheric coefficients are 0;

[0106] If the absolute value of the change in the evaluation function before and after optimizing a6 is greater than the preset threshold, set a8 as a variable, set the value of a4 to the optimal solution of a4, set the value of a6 to the optimal solution of a6, and set a 10 、a 12 、a 14 The value of is set to 0, and the damped least squares method is used to optimize to obtain the optimal solution of a8. The absolute value of the change in the evaluation function before and after the optimization of a8 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a8 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the values of other aspheric coefficients are 0;

[0107] If the absolute value of the change in the evaluation function before and after optimizing a8 is greater than the preset threshold, a 10 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 12 and a 14 The value of is set to 0, and the damped least squares method is used for optimization to obtain a 10 The optimal solution of a 10 The absolute value of the change in the evaluation function before and after, if the optimization a 10 If the absolute value of the change in the evaluation function before and after is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the value of a 10 The value of a 10 The optimal solution of , the values of other aspheric coefficients are 0;

[0108] If we optimize a 10 The absolute value of the change in the evaluation function before and after is greater than the preset threshold, 12 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 10 The value of is set to a 10 The optimal solution is to 14 The value of is set to 0, and the damped least squares method is used for optimization to obtain a 12 The optimal solution of a 12 The absolute value of the change in the evaluation function before and after, if the optimization a 12 If the absolute value of the change in the evaluation function before and after is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the value of a 10 The value of a 10 The optimal solution, a 12 The value of a12 The optimal solution of , the values of other aspheric coefficients are 0;

[0109] If we optimize a 12 The absolute value of the change in the evaluation function before and after is greater than the preset threshold, 14 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 10 The value of is set to a 10 The optimal solution is to set a 12 The value of is set to a 12 The optimal solution of is optimized by damped least squares method, and we get a 14 The optimization ends when the optimal solution of any aspheric coefficient is obtained. The value of the aspheric coefficient is the optimal solution of the aspheric coefficient.

[0110] To facilitate understanding of the present invention, an example is used to illustrate the embodiment of the present invention. In other steps of the embodiment of the present invention and other possible implementations, if an example in this step is involved, unless otherwise specified, the values of the parameters and the symbols representing the parameters in the example remain consistent.

[0111] The transceiver lenses of a coaxial optical system can generally be implemented in two ways: the first is a transceiver lens with a perpendicular optical axis combined with a transflective lens; the second is a receiving lens with a hole cut in the center of the optical axis and a transmitting lens placed within the hole. The present embodiment uses a coaxial optical path with a receiving lens with a hole cut in the center. In this embodiment, the reflector is the curved reflector described above, the receiving lens has a hole cut in the center of the optical axis, and the transmitting lens is a conventional collimating lens placed within the hole of the receiving lens.

[0112] The optical axes of the receiving lens and the transmitting lens coincide, the transmitting lens with an aperture of d is placed in the center hole of the receiving lens, and the laser source is located at the focal plane f of the transmitting lens. e At the target surface at a distance of L, the light emitted from the laser source is collimated by the emitting lens and the beam width is d is the aperture of the transmitting lens, e is the width of the light source. According to the principle of geometric optics, different target (detection) distances L correspond to different conjugate distances of the receiving lens. Among them, f r is the focal length of the receiving lens in the coaxial laser radar. The width of the beam detected at this location is The position of the detector's photosensitive surface is for the maximum target distance L of the radar m The corresponding conjugate distance Rather than the focal plane position of the receiving lens.

[0113] Through simulation modeling and analysis using an optical sequence mode, in the example provided by the embodiment of the present invention, the cylindrical transparent housing of the laser radar is made of PMMA (polymethyl methacrylate), and the laser operating wavelength of the laser radar is 905nm. Therefore, the refractive index of the cylindrical transparent housing for the laser is n = 1.484. The outer diameter of the cylindrical transparent housing is R1 = 20mm, the inner diameter is R2 = 18mm, Vx = 0°, and Vz = 0°. That is, the field of view light beam with an angle of 0° to both the x-axis and the z-axis is reflected by a plane reflector and then transmitted through the transparent housing to the target surface with a maximum detection distance of 10m. Figure 8 In the prior art, when the reflector is a flat reflector, in the sequential mode, Vx = 0°, Vz = 0°, the point diagram of the exit surface of the field of view and the 10m image plane is combined with Figure 8 It can be seen that the light beam is basically not deflected in the y direction, but produces a large divergence effect in the x direction, and the light deflection angle δ is greater than 14 mrad.

[0114] In order to compensate for the deflection effect of the cylindrical light-transmitting housing on the light beam, an embodiment of the present invention provides a coaxial optical path curved reflector transceiver system, such as Figure 9 As shown in the figure, the flat reflector is changed to a curved reflector, and a coaxial optical path model is established for optimization.

[0115] Figure 10 This is a coaxial optical path model provided by an embodiment of the present invention, combined with Figure 10 , the focal length of the transmitting lens f e =10.08mm, the transmitting lens aperture d = 5.89mm, and the receiving lens focal length is f r =24.00mm, the receiving lens aperture is 26mm, where, combined with Figure 10 The target surface AB is imaged by the receiving lens to obtain the imaging surface A'B'. L' is the distance from the receiving lens to A'B'. By calculation, L'=24.058mm. The receiving detector is located at L'-f behind the focal plane. r =0.058mm, that is, at the conjugate surface of the maximum detection target surface, the curvature radius of the paraxial area of the curved reflector is calculated according to the above formula to obtain R G =780.50mm, the system's combined focal length is approximately -10 10 mm, satisfying the condition that the combined focal length of the paraxial system is infinite.

[0116] The evaluation function is obtained by Figure 10 Select 9 points (x i ,y i ), i = 1, ..., 9, x i and y iRespectively represent the horizontal distance and vertical distance of the target point from the optical axis, x1 = -100mm, y1 = -100mm; x2 = -100mm, y2 = 0mm; x3 = -100mm, y3 = 100mm; x4 = 0mm, y4 = -100mm; x5 = 0mm, y5 = 0mm; x6 = 0mm, y6 = 100mm; x7 = 100mm, y7 = -100mm; x8 = 100mm, y8 = 0mm; x9 = 100mm, y9 = 100mm. The field of view corresponding to each point is divided into the form of Gaussian 3 rings and 6 arms to divide the light beam incident on the aperture of the receiving lens. The distance V between the intersection point of the light beam and the receiving photosensitive surface and the intersection point of the main light ray and the receiving photosensitive surface is calculated. The weight of each point and the weight of each light beam are set to establish the evaluation function F, which can usually be expressed as: Where W i represents the weight, V i is the current value, T i is the target value.

[0117] According to the above calculation, the curvature radius r of the paraxial part of the curve G is determined as follows: G The cone coefficient k = -1, the evaluation function change threshold is set to δF = F * 0.1%, and the aspheric coefficients of each order are used as variables to perform software optimization through the following optimization sequence:

[0118] Set a4 as a variable, a6, a8, a 10 、a 12 、a 14 All aspheric coefficients of each order are set to zero, and the software's damped least squares method is used to optimize the optimal a4. The evaluation functions before and after optimization are compared. If the change in the evaluation function does not exceed the threshold δF, the optimization is stopped. If the change in the evaluation function exceeds the evaluation threshold δF, the value of a4 is fixed and a6 is set as a variable to continue optimization. The optimal a6 is then optimized using the damped least squares method. The evaluation functions before and after optimization are compared. If the change in the evaluation function does not exceed the threshold δF, the optimization is stopped. If the change in the evaluation function exceeds the evaluation threshold, the values of a4 and a6 are fixed and a8 is set as a variable. The optimal a8 is then optimized using the damped least squares method. The above steps are repeated until the change in the evaluation function does not exceed the threshold and the entire optimization process is completed. The above optimization process optimizes the aspheric coefficients of each order from low to high order, optimizing only one variable at a time, reducing the difficulty of optimization and the probability of the optimization falling into a local minimum. This is because the more optimization variables there are, the more local minimum values their combinations will have.

[0119] In addition, considering that the correction effect of each order aspheric coefficient on the curve G is different, under the same normalized parameter conditions, the low-order aspheric coefficient has a greater correction effect on the overall curve, and its optimization order is higher. After optimization, the aspheric parameters are:

[0120] a4=-1.218×10 -6 mm -3

[0121] a6=-8.730×10 -11 mm -5

[0122] a8=-2.725×10 -13 mm -7

[0123] a 10 =0mm -9

[0124] a 12 =0mm -11

[0125] a 14 =0mm -13

[0126] The optimization of the curve is obtained from the above calculation to satisfy the curve G paraxial area with a curvature radius of R G The parabolic equation is used as the initial condition, and the correction is gradually started from the fourth-order term. The lower the order of the aspheric term, the greater the correction effect on the curve. From a4 to a8, the evaluation function becomes smaller and smaller. When the evaluation function changes below the threshold at a8, the optimization stops and no higher-order correction is performed. Figure 11 is an optimized aspheric curve provided by an embodiment of the present invention, Figure 12 is a correction curve diagram of each order aspheric term after optimization provided by an embodiment of the present invention, such as Figure 11 and Figure 12 As shown in the figure, the aspheric terms with higher coefficient orders have a greater correction on the radial distance and a smaller effect on small radial distances, which is consistent with the above analysis.

[0127] Figure 13(a) to Figure 13(e)The point diagram of the exit surface and the 10m target surface corresponding to different fields of view of the curved reflector after simulation optimization in the sequence mode provided by the embodiment of the present invention. The calculation results show that for the field of view of Vx=0°, Vz=0°, the increase in the geometric radius of the light beam after transmission of 10m is less than 10mm, and the light deflection angle δ is less than 1mrad after the introduction of the reflector compensation, which is a significant improvement compared with the results of the plane reflector simulation. For the field of view of Vx=0°, Vz=1°, the increase in the geometric radius of the light beam after transmission of 10m is less than 10mm, and the light deflection angle δ is less than 1mrad after the introduction of the curved reflector compensation; for the field of view of Vx=0°, Vz=-1°, the increase in the geometric radius of the light beam after transmission of 10m is less than 30mm, and the light deflection angle δ is less than 3mrad after the introduction of the curved reflector compensation. For a field of view with Vx = 1° and Vz = 0°, the increase in the geometric beam radius after 10m of transmission is less than 30mm, and the introduction of a curved reflector for compensation results in a light deflection angle δ of less than 3mrad. For a field of view with Vx = -1° and Vz = 0°, the increase in the geometric beam radius after 10m of transmission is less than 30mm, and the introduction of a curved reflector for compensation results in a light deflection angle δ of less than 3mrad. The spot diagram shows that the optical system characteristics are symmetrical about the x-axis field of view, consistent with the symmetry of the structure.

[0128] Figure 14 This is a graph comparing the simulation results of a plane mirror and a curved mirror in non-sequential mode, provided by an embodiment of the present invention. The laser light source uses a three-segment edge-emitting laser diode with a power of 25W, a light-emitting area (W×H) of 120μm×20μm, and a sensor photosensitive surface diameter of 500μm. The left side of the radar is used as the 0° angle reference, with the clockwise direction being positive. The simulated position is 10m away and the beam characteristics on the photosensitive surface of the receiving detector are compared. The emission and reception spot patterns of the plane and curved mirrors show that at a 90° scanning angle, the plane mirror emits the beam vertically, with a smaller horizontal beam width and less influence from the transparent housing. The emission and reception spots maintain their basic shape, exhibiting a three-segment distribution. However, the reception spot exceeds the range of the photosensitive surface, losing some echo energy. At other angles, 0°, 30°, and 45°, the emission and reception spot shapes change, failing to exhibit a three-segment distribution. The comparative simulation results of introducing a curved reflector show that at scanning angles of 0°, 30°, 45°, and 90°, the transmitting and receiving light spots can still maintain their basic shapes, presenting a three-section distribution, and the receiving light spots are all within the range of the photosensitive surface, with no echo energy loss. The curved reflector can well compensate for the influence of the cylindrical housing on the coaxial light transmitting and receiving path.

[0129] An embodiment of the present invention proposes a method for determining the parameters of a curved reflector, wherein the curved surface of the curved reflector is determined by determining various parameters of a curve on the curved surface of the curved reflector, and the effect of the cylindrical shell on the collimated light beam is compensated by the curved reflector to reduce the influence of the cylindrical transparent shell on the collimated detection light beam, thereby solving the problem of light spot divergence caused by the transparent shell in practical applications, improving the measurement accuracy of the laser radar and the receiving efficiency of the light-receiving and light-receiving path to increase the radar range. Moreover, the present invention does not introduce additional optical calibration elements to compensate for the divergence effect caused by the transparent shell on the collimated light beam, but instead compensates by modifying the surface shape of the reflector, making the system structure more compact and more flexible and convenient to implement.

[0130] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0131] The embodiment of the present invention further provides a curved reflector, which is installed in a coaxial laser radar. The coaxial laser radar includes a cylindrical light-transmitting shell. Figure 2 The corresponding method embodiment determines the parameters of the curved reflector. The curved reflector compensates for the effect of the cylindrical housing on the collimated light beam, thereby reducing the impact of the cylindrical transparent housing on the collimated detection beam. This solves the problem of light spot divergence caused by the transparent housing in practical applications, improves the measurement accuracy of the laser radar and the receiving efficiency of the light-receiving and light-transmitting circuit, and increases the radar's range. Furthermore, the present invention does not introduce additional optical calibration elements to compensate for the divergence of the collimated light beam caused by the transparent housing. Instead, it compensates by modifying the surface shape of the reflector, making the system structure more compact and more flexible and convenient to implement.

[0132] The embodiment of the present invention further provides a coaxial laser radar, which includes a cylindrical light-transmitting housing and a curved reflector, wherein the curved reflector is a single-bent cylindrical curved reflector, wherein the parameters of the curved reflector are obtained by Figure 2 Determined by the method of the corresponding embodiment.

[0133] In another possible implementation, the coaxial laser radar also includes a receiving lens and a transmitting lens. The receiving lens has a hole at the center of the optical axis, and the transmitting lens is placed in the hole of the receiving lens.

[0134] The coaxial laser radar provided in the embodiment of the present invention compensates for the effect of the cylindrical shell on the collimated light beam by installing a curved reflector, thereby reducing the influence of the cylindrical transparent shell on the collimated detection light beam, solving the problem of light spot divergence caused by the transparent shell in actual application, improving the laser radar measurement accuracy and the receiving efficiency of the light-receiving and light-transmitting path to increase the radar range. In addition, the present invention does not introduce additional optical calibration elements to compensate for the divergence effect caused by the transparent shell on the collimated light beam, but instead uses the surface shape of the reflector to compensate, making the system structure more compact and more flexible and convenient to implement.

[0135] The following are device embodiments of the present invention. For details not fully described therein, reference may be made to the corresponding method embodiments described above.

[0136] Figure 15 A schematic diagram of the structure of a device for determining parameters of a curved reflector provided by an embodiment of the present invention is shown. For ease of explanation, only the portion related to the embodiment of the present invention is shown, which is described in detail as follows:

[0137] like Figure 15 As shown, the parameter determination device 15 of the curved reflector includes: a curvature radius determination module 151 and an expression determination module 152;

[0138] A curvature radius determination module 151 is configured to determine the curvature radius of a paraxial portion of a curve corresponding to the curved reflector based on the refractive index of the cylindrical light-transmitting housing for laser light, the outer diameter, and the inner diameter of the cylindrical light-transmitting housing. The paraxial portion represents a predetermined region of the curve closest to the central axis of the cylindrical light-transmitting housing.

[0139] The expression determination module 152 is used to substitute the curvature radius of the paraxial part of the curve and the preset conic coefficient into the standard equation of the aspheric curve to obtain an initial expression; and determine the various aspheric coefficients in the initial expression through the damped least squares method and the preset evaluation function to obtain the curve expression of the curve.

[0140] An embodiment of the present invention proposes a parameter determination device for a curved reflector, which determines the curved surface of the curved reflector by determining various parameters of the curve on the curved surface of the curved reflector. The curved reflector compensates for the effect of the cylindrical shell on the collimated light beam, thereby reducing the influence of the cylindrical transparent shell on the collimated detection light beam, solving the problem of light spot divergence caused by the transparent shell in actual application, improving the measurement accuracy of the laser radar and the receiving efficiency of the light-receiving and light-receiving path to increase the radar range. Moreover, the present invention does not introduce additional optical calibration elements to compensate for the divergence effect caused by the transparent shell on the collimated light beam, but instead compensates by modifying the surface shape of the reflector, making the system structure more compact and more flexible and convenient to implement.

[0141] The device for determining parameters of a curved reflector provided in this embodiment can be used to execute the above-mentioned method for determining parameters of a curved reflector. Its implementation principle and technical effects are similar and will not be described in detail in this embodiment.

[0142] Figure 16 FIG is a schematic diagram of a terminal provided by an embodiment of the present invention. Figure 16 As shown, the terminal 16 of this embodiment includes: a processor 160, a memory 161, and a computer program 162 stored in the memory 161 and executable on the processor 160. When the processor 160 executes the computer program 162, the steps of the above-mentioned method for determining parameters of the curved reflector are implemented, for example Figure 2 Alternatively, when the processor 160 executes the computer program 162, the functions of the modules / units in the above-mentioned device embodiments are realized, for example Figure 15 Functions of modules 151 to 152 are shown.

[0143] Exemplarily, the computer program 162 may be divided into one or more modules / units, which are stored in the memory 161 and executed by the processor 160 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 162 in the terminal 16.

[0144] The terminal 16 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The terminal 16 may include, but is not limited to, a processor 160 and a memory 161. Those skilled in the art will understand that Figure 16 This is merely an example of the terminal 16 and does not constitute a limitation on the terminal 16 . The terminal may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the terminal may also include input and output devices, network access devices, buses, etc.

[0145] The processor 160 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0146] The memory 161 may be an internal storage unit of the terminal 16, such as a hard disk or memory of the terminal 16. The memory 161 may also be an external storage device of the terminal 16, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the terminal 16. Furthermore, the memory 161 may include both an internal storage unit of the terminal 16 and an external storage device. The memory 161 is used to store the computer program and other programs and data required by the terminal. The memory 161 may also be used to temporarily store data that has been output or is about to be output.

[0147] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0148] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0149] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of 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 the present invention.

[0150] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical functional division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, and can be electrical, mechanical, or other forms.

[0151] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0152] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0153] If the integrated module / unit 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 present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above-mentioned parameter determination method embodiments of each curved reflector. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practices, computer-readable media does not include electrical carrier signals and telecommunication signals.

[0154] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A method for determining parameters of a curved reflector, characterized in that: The curved reflector is a single-bent cylindrical curved reflector, which is installed in a coaxial laser radar. The coaxial laser radar includes a cylindrical light-transmitting housing, including: Determine the curvature radius of the paraxial portion of the curve corresponding to the curved reflector based on the refractive index of the cylindrical light-transmitting housing for laser light, the outer diameter and the inner diameter of the cylindrical light-transmitting housing, wherein the paraxial portion represents a predetermined region of the curve closest to the central axis of the cylindrical light-transmitting housing; Substituting the curvature radius of the paraxial portion of the curve and a preset conic coefficient into the standard equation of the aspheric curve to obtain an initial expression; Determine each aspheric coefficient in the initial expression by using a damped least squares method and a preset evaluation function to obtain a curve expression of the curve; Determining the curvature radius of the paraxial portion of the curve corresponding to the curved reflector according to the refractive index of the cylindrical light-transmitting housing to the laser, the outer diameter length and the inner diameter length of the cylindrical light-transmitting housing includes: The curvature radius of the paraxial portion of the curve is determined according to a first formula, wherein the first formula is: Among them, R G is the curvature radius of the paraxial portion of the curve, n is the refractive index of the cylindrical light-transmitting housing to laser light, R1 is the outer diameter of the cylindrical light-transmitting housing, and R2 is the inner diameter of the cylindrical light-transmitting housing.

2. The method according to claim 1, characterized in that The initial expression is: Wherein, y′(h) is used to represent the mapping relationship between the value of y′ and the value of h in the y′oh coordinate system, the y′ axis is perpendicular to the h axis, o is the origin of the y′oh coordinate system, the curve is symmetrically distributed about the y′ axis, o is the intersection of the curve and the y′ axis, k is used to represent the preset cone coefficient, R G The curvature radii of the paraxial portion of the curve are represented by a4, a6, a8, and a 10 、a 12 、a 14 is the aspheric coefficient.

3. The method according to claim 2, characterized in that k is equal to -1, and the initial expression is:

4. The method according to claim 2 or 3, characterized in that The determining of each aspheric coefficient in the initial expression by the damped least square method and a preset evaluation function includes: A4, A6, A8, A 10 、a 12 、a 14 Arrange in the preset order to obtain the sorting results; The aspheric coefficients in the sorting results are optimized in sequence by the damped least squares method until the absolute value of the change in the evaluation function is less than or equal to the preset threshold value. x When optimizing, a x Set as a variable, and set the sort result in a x The value of the coefficient that has been optimized before is set as the optimal solution of the coefficient, and the value of the coefficient at a in the sorting result is set as the optimal solution of the coefficient. x The value after that is set to 0, a x is any aspheric coefficient in the sorting results.

5. The method according to claim 4, characterized in that In the sorting results, the aspheric coefficients are a4, a6, a8, a 10 、a 12 、a 14 , the aspheric coefficients in the sorting results are optimized in sequence by the damped least squares method until the change in the evaluation function is less than or equal to a preset threshold value, including: Set a4 as a variable, and set a6, a8, a 10 、a 12 、a 14 The value of a4 is set to 0, and the damped least squares method is used for optimization to obtain the optimal solution of a4. The absolute value of the change in the evaluation function before and after the optimization of a4 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a4 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, and the values of other aspheric coefficients are 0; If the absolute value of the change in the evaluation function before and after optimizing a4 is greater than the preset threshold, set a6 as a variable, set the value of a4 as the optimal solution of a4, and set a8 and a 10 、a 12 、a 14 The value of a6 is set to 0, and the damped least squares method is used for optimization to obtain the optimal solution of a6. The absolute value of the change in the evaluation function before and after the optimization of a6 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a6 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, and the values of other aspheric coefficients are 0; If the absolute value of the change in the evaluation function before and after optimizing a6 is greater than the preset threshold, set a8 as a variable, set the value of a4 to the optimal solution of a4, set the value of a6 to the optimal solution of a6, and set a 10 、a 12 、a 14 The value of is set to 0, and the damped least squares method is used to optimize to obtain the optimal solution of a8. The absolute value of the change in the evaluation function before and after the optimization of a8 is determined. If the absolute value of the change in the evaluation function before and after the optimization of a8 is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the values of other aspheric coefficients are 0; If the absolute value of the change in the evaluation function before and after optimizing a8 is greater than the preset threshold, a 10 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 12 and a 14 The value of is set to 0, and the damped least squares method is used for optimization to obtain a 10 The optimal solution of a 10 The absolute value of the change in the evaluation function before and after, if the optimization a 10 If the absolute value of the change in the evaluation function before and after is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the value of a 10 The value of a 10 The optimal solution of , the values of other aspheric coefficients are 0; If we optimize a 10 The absolute value of the change in the evaluation function before and after is greater than the preset threshold, 12 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 10 The value of is set to a 10 The optimal solution is to set a 14 The value of is set to 0, and the damped least squares method is used for optimization to obtain a 12 The optimal solution of a 12 The absolute value of the change in the evaluation function before and after, if the optimization a 12 If the absolute value of the change in the evaluation function before and after is less than or equal to the preset threshold, the optimization ends, the value of a4 is the optimal solution of a4, the value of a6 is the optimal solution of a6, the value of a8 is the optimal solution of a8, and the value of a 10 The value of a 10 The optimal solution, a 12 The value of a 12 The optimal solution of , the values of other aspheric coefficients are 0; If we optimize a 12 The absolute value of the change in the evaluation function before and after is greater than the preset threshold, 14 If set as a variable, the value of a4 is set to the optimal solution of a4, the value of a6 is set to the optimal solution of a6, the value of a8 is set to the optimal solution of a8, and a 10 The value of is set to a 10 The optimal solution is to set a 12 The value of is set to a 12 The optimal solution of is optimized by damped least squares method, and we get a 14 The optimization ends when the optimal solution of any aspheric coefficient is obtained. The value of the aspheric coefficient is the optimal solution of the aspheric coefficient.

6. A curved reflector, characterized in that: The curved reflector is installed on a coaxial laser radar, which includes a cylindrical light-transmitting shell. The parameters of the curved reflector are determined by the method described in any one of claims 1 to 5.

7. A coaxial laser radar, characterized in that: The coaxial laser radar includes a cylindrical light-transmitting shell and a curved reflector, wherein the curved reflector is a single-bent cylindrical curved reflector, wherein the parameters of the curved reflector are determined by the method described in any one of claims 1 to 5.

8. A terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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