An archimedes spiral scanner for a lidar system and a scanning method

Abstract

The application provides an Archimedes spiral scanner and a scanning method for a laser radar system, and relates to the technical field of laser scanning.The Archimedes spiral scanner comprises a laser generator, a beam reducer, a spiral scanning disc and a single motor.The laser generator generates an initial light signal and outputs the initial light signal to the beam reducer.The beam reducer outputs the light signal to the spiral scanning disc along an optical axis after beam reduction.The spiral scanning disc deflects a light beam and outputs a target light beam to a scanning position.The single motor drives the spiral scanning disc to rotate around the optical axis, so that the target light beam is scanned along an Archimedes spiral path, and a radar scanning field is formed.The Archimedes spiral scanner for the laser radar system directly generates an Archimedes spiral scanning field by driving a single-piece spiral scanning disc to rotate through a single motor, so that the spiral scanning disc continuously changes the deflection state of the light beam, thereby simplifying the structure of the laser radar system and improving scanning stability and reliability.

Description

Technical Field

[0001] This invention belongs to the field of laser scanning technology, specifically relating to an Archimedes spiral scanner and scanning method for lidar systems. Background Technology

[0002] In the field of lidar and beam scanning technology, Archimedean spiral scanning is widely used in autonomous driving, environmental perception, and 3D modeling due to its advantages such as continuous coverage and controllable scanning range. Existing technologies typically employ a dual-axis galvanometer drive structure or a rotating biprism combination structure to achieve Archimedean spiral scanning. The dual-axis galvanometer structure requires the coordinated oscillation of two mutually perpendicular galvanometer axes, using precise timing to fit the spiral trajectory. The rotating biprism structure, on the other hand, changes the beam propagation direction by coordinating the refractive index difference and angle of two rotatable prisms. However, both structures require multiple drive components and complex synchronous control, resulting in a large system size, complex structure, and difficult assembly and debugging. Furthermore, differences in multi-axis dynamic response characteristics and mechanical transmission gaps easily lead to nonlinear distortion of the scanning trajectory. Additionally, the multiple refractions of the biprisms cause severe dispersion and energy loss, making it difficult to meet the high-precision and high-stability requirements of engineering applications. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an Archimedean spiral scanner and scanning method for lidar systems, thereby solving the aforementioned problems. The scanner uses a single motor to drive a single spiral scanning disk to rotate, causing the spiral scanning disk to continuously change the deflection state of the light beam, directly generating an Archimedean spiral scanning field. This simplifies the structure of the lidar system and improves scanning stability and reliability.

[0004] To solve the above-mentioned technical problems, the present invention provides an Archimedes spiral scanner for a lidar system, wherein the monolithic rotating Archimedes spiral scanner includes a laser generator, a beam shrinker, a spiral scanning disk, and a single motor. The laser generator is used to generate an initial optical signal, so that the initial optical signal is sent to the beam reducer through the laser output terminal of the laser generator; The beam shrinker is used to shrink the initial optical signal along the optical axis and output the shrunken beam to the spiral scanning disk. The spiral scanning disk is used to deflect the beam of light from the beam-contracting beam and output the target beam to the target scanning position; The single motor is used to drive the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

[0005] In the above scheme, the initial optical signal generated by the laser generator is beam-constricted along the optical axis by a beam reducer and output as a beam-constricted beam to a spiral scanning disk. The spiral scanning disk deflects the beam-constricted beam. Simultaneously, a single motor drives the spiral scanning disk to rotate around the optical axis, causing the spiral scanning disk to continuously change its deflection state of the beam-constricted beam during rotation. This causes the target beam output by the spiral scanning disk to sequentially point to each target scanning position along a preset Archimedean spiral path, thus forming an Archimedean spiral radar scanning field. Therefore, the above scheme only uses a single motor to drive the rotation of a single spiral scanning disk, that is, it directly generates a two-dimensional spiral scanning trajectory by relying solely on the rotational motion of a single optical element. It does not require multiple sets of drive components and complex synchronous control, thus significantly simplifying the structure of the lidar system, reducing the difficulty of assembly and debugging, and improving scanning stability and reliability through the inertia-free characteristics of continuous rotational motion.

[0006] Further, the beam shortener includes a first convex lens and a second convex lens, which are arranged at intervals along the optical axis. The beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal, so that the initial light signal is focused based on the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the second convex lens and outputs a narrowed beam to the spiral scanning disk.

[0007] In the above scheme, the beam shrinker employs a first convex lens and a second convex lens arranged at intervals along the optical axis. The initial optical signal is focused by the first convex lens, and the focused beam is output to the second convex lens. The focused beam is then collimated by the second convex lens, and the resulting beam shrinker is output to the spiral scanning disk. Through the focusing effect of the first convex lens and the collimating effect of the second convex lens, the initial optical signal is shrinked along the optical axis, resulting in a beam with a reduced diameter. This scheme uses only two convex lenses, resulting in a simple structure, minimal light energy loss, and the ability to output a high-quality beam shrinker. This ensures that the beam shrinker is accurately incident on the spiral scanning disk, providing stable incident conditions for subsequent light deflection, and thus facilitating laser scanning of the target beam along a preset Archimedean spiral path.

[0008] Furthermore, the beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal so that the initial light signal is focused based on the preset first focal length of the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the preset second focal length of the second convex lens, and the beam is output to the spiral scanning disk; Specifically, a first focal length and a second focal length are preset based on the surface shape parameters of the spiral scanning disk, so that the diameter of the beam-contracting beam matches the local curvature of the spiral scanning disk.

[0009] In the above scheme, the preset first focal length of the first convex lens and the preset second focal length of the second convex lens are preset according to the surface shape parameters of the spiral scanning disk, so that the diameter of the beam-contracting beam matches the local curvature of the spiral scanning disk. The spiral scanning disk has a continuously changing surface shape, and the local curvature is different at different radial positions. If the diameter of the beam-contracting beam is too large, the beam will cover multiple regions with different local curvatures at the same time, resulting in inconsistent light deflection; if the diameter of the beam-contracting beam is too small, the light energy utilization rate will be reduced. By presetting the first and second focal lengths according to the surface shape parameters, the diameter of the beam-contracting beam is precisely controlled to match the local curvature of the spiral scanning disk, ensuring that the beam-contracting beam propagates within a single local curvature region of the spiral scanning disk. This ensures that when the target beam is laser-scanned along the preset Archimedean spiral path, the divergence angle of the scanning spot is uniformly distributed, improving the scanning resolution and the consistency of the scanning field.

[0010] Furthermore, the spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The spiral scanning disk is used to deflect the beam of light from the narrowed beam and output the target beam to the target scanning position, including: The incident surface of the spiral scanning disk is used to receive the beam contraction, so that the beam contraction locally generates light phase modulation based on the preset surface shape of the incident surface to obtain modulated light. The exit surface of the spiral scanning disk is used to receive the modulated light, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

[0011] In the above scheme, both the incident and exit surfaces of the spiral scanning disk have preset surface layouts. The incident surface is used to modulate the phase of the beam-contracting beam to obtain modulated light; the exit surface is used to deflect the modulated light, outputting the target beam to the target scanning position. By setting the beam phase modulation function and the light deflection function on the incident and exit surfaces respectively, the mutual constraints of surface parameters caused by simultaneously implementing two functions on the same surface can be avoided. The incident surface independently applies precise beam phase modulation to the beam-contracting beam based on its preset surface layout, and the exit surface then independently deflects the modulated light based on its preset surface layout. This scheme allows the preset surface layout of each surface to be optimized individually for its respective function, thereby improving the accuracy of beam phase modulation and light deflection, ensuring that the target beam is accurately scanned to the target scanning position along the preset Archimedean spiral path.

[0012] Furthermore, the specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

[0013] In the above scheme, the preset surface layout is determined step-by-step by acquiring the target scanning mode and setting the spiral mode coefficient, spiral size coefficient, and spiral period coefficient through preset Archimedean spiral parameter equations, preset coordinate rotation transformation relationships, and preset polar coordinate transformation relationships. Since designing the disk-shaped surface distribution directly in the polar coordinate system is highly complex, the initial surface distribution is first obtained in the Cartesian coordinate system. Then, the spiral coordinate mapping phase in the rotated coordinate system is obtained by rotating by a preset angle. Finally, it is transformed into a disk-shaped surface distribution in the polar coordinate system through preset polar coordinate transformation relationships. This decomposes the surface design of the spiral scanning disk into multiple controllable steps. The above scheme reduces the design difficulty of the preset surface layout, enabling the incident and exit surfaces to perform precise light phase modulation and light deflection on the beam-shrinking beam based on the obtained preset surface layout, thereby ensuring stable scanning of the target beam along the preset Archimedean spiral path.

[0014] Furthermore, the target scanning mode includes a constant velocity spiral scanning mode and a constant angle spiral scanning mode, wherein: When the target scanning mode is a constant velocity spiral scanning mode, the spiral mode coefficient is determined to be half, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is half. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the radial distribution relationship of the surface slope along the radial direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the square root of the radius. Based on the radial distribution relationship, the preset surface layout of the spiral scanning disk is determined. When the target scanning mode is an isoangular spiral scanning mode, the spiral mode coefficient is set to one, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is one. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the tangential distribution relationship of the surface slope along the tangential direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the radius. Based on the tangential distribution relationship, the preset surface layout of the spiral scanning disk is determined.

[0015] In the above scheme, the target scanning modes include a constant velocity spiral scanning mode and an isoangular spiral scanning mode, corresponding to spiral mode coefficients of 1 / 2 and 1, respectively. When the spiral mode coefficient is 1 / 2, the exponent of the change in surface height with the horizontal and vertical coordinates in the initial surface distribution in the Cartesian coordinate system is 1 / 2. After preset coordinate rotation transformation and preset polar coordinate transformation, a radial distribution relationship is obtained in the polar coordinate system where the radial slope of the disk-shaped surface distribution is inversely proportional to the square root of the radius. The preset surface layout determined based on this radial distribution relationship enables the target beam to achieve constant velocity spiral scanning. When the spiral mode coefficient is 1, the exponent of the change in surface height with the horizontal and vertical coordinates in the initial surface distribution in the Cartesian coordinate system is 1. After preset coordinate rotation transformation and preset polar coordinate transformation, a tangential distribution relationship is obtained in the polar coordinate system where the tangential slope of the disk-shaped surface distribution is inversely proportional to the radius. The preset surface layout determined based on this tangential distribution relationship enables the target beam to achieve isoangular spiral scanning. The target scanning mode can be switched by selecting the spiral mode coefficient without changing the hardware structure.

[0016] Furthermore, the single motor is used to drive the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, including: The single motor is used to drive the spiral scanning disk to rotate around the optical axis based on a preset motor angular velocity, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, wherein the scanning frame rate of the Archimedean spiral radar scanning field is proportional to the preset motor angular velocity.

[0017] In the above scheme, a single motor drives the helical scanning disk to rotate around the optical axis based on a preset motor angular velocity, and the scanning frame rate of the Archimedean spiral radar scanning field is proportional to the preset motor angular velocity. The scanning frame rate is determined by the time it takes for the helical scanning disk to complete one full rotation cycle. Each rotation of the single motor completes one full laser scanning cycle along the preset Archimedean spiral path, forming one frame of the Archimedean spiral radar scanning field. By adjusting the preset motor angular velocity, the scanning frame rate can be directly and linearly changed without the need for additional synchronization control components. Simultaneously, the continuous rotation of the helical scanning disk around the optical axis driven by the single motor avoids the start-stop inertia caused by discontinuous motion, resulting in a smooth and continuous scanning trajectory of the target beam along the preset Archimedean spiral path, thereby improving the scanning stability and reliability of the Archimedean spiral radar scanning field.

[0018] This invention provides a scanning method for a lidar system. The method is applied to an Archimedean spiral scanner used in a lidar system. The Archimedean spiral scanner includes a laser generator, a beam reducer, a spiral scanning disk, and a single motor. The method includes the following steps: The laser generator generates an initial optical signal, which is then transmitted to the beam shortener through the laser output terminal of the laser generator. The initial optical signal is compressed along the optical axis by the beam shortener, and the compressed beam is output to the spiral scanning disk. Based on the spiral scanning disk, the beam of light is deflected and the target beam is output to the target scanning position; The single motor drives the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

[0019] In the above scheme, Archimedean spiral scanning is achieved through the steps of generating an initial light signal with a laser generator, beam contraction with a beam shortener, deflection of the light by a spiral scanning disk, and rotation of the spiral scanning disk around the optical axis by a single motor. The laser generator generates an initial light signal, which is then contracted along the optical axis by the beam shortener and output to the spiral scanning disk. The spiral scanning disk deflects the contracted beam, outputting a target beam to the target scanning position. Simultaneously, the single motor drives the spiral scanning disk to rotate around the optical axis, causing the target beam output by the spiral scanning disk to perform laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field. This scheme uses only a single motor to drive the spiral scanning disk, directly generating a two-dimensional spiral scanning trajectory through the deflection of light from a single spiral scanning disk. It eliminates the need for multiple drive components and complex synchronization control, thus simplifying the structure of the lidar system, reducing assembly and debugging difficulty, and improving scanning stability and reliability through continuous rotational motion.

[0020] Furthermore, the spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The step of deflecting the beam of light based on the spiral scanning disk and outputting the target beam to the target scanning position includes: The beam is received on the incident surface of the spiral scanning disk, so that the beam is locally phase-modulated based on the preset surface shape of the incident surface to obtain modulated light. The modulated light is received by the exit surface of the spiral scanning disk, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

[0021] In the above scheme, the spiral scanning disk achieves beam deflection by modulating the light phase at the incident surface and deflecting the light at the exit surface. The contracted beam is incident on the incident surface, and local phase modulation occurs based on a preset surface shape, resulting in modulated light. The modulated light is then incident on the exit surface, and local deflection occurs based on a preset surface shape, outputting the target beam to the target scanning position. By setting the light phase modulation and deflection on the incident and exit surfaces respectively, the mutual constraints on surface parameters caused by simultaneously implementing two functions on the same surface are avoided. The incident surface can independently apply precise light phase modulation to the contracted beam, and the exit surface can independently and precisely deflect the modulated light, thereby increasing the degree of freedom in beam control, reducing light phase modulation and deflection errors, improving the deflection efficiency and scanning accuracy of the target beam, and ensuring that the target beam accurately reaches the target scanning position along a preset Archimedean spiral path.

[0022] Furthermore, the specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

[0023] In the above scheme, the preset surface layout is determined step-by-step by acquiring the target scanning mode and setting the spiral mode coefficient, spiral size coefficient, and spiral period coefficient through preset Archimedean spiral parameter equations, preset coordinate rotation transformation relationships, and preset polar coordinate transformation relationships. Directly determining the preset surface layout based on the disk-shaped surface distribution in polar coordinates is highly complex. However, by first obtaining the initial surface distribution in Cartesian coordinates based on the preset Archimedean spiral parameter equations, then rotating the initial surface distribution by a preset angle based on the preset coordinate rotation transformation relationship to obtain the spiral coordinate mapping phase in the rotated coordinate system, and finally transforming the spiral coordinate mapping phase into a disk-shaped surface distribution in polar coordinates based on the preset polar coordinate transformation relationship, the setting of the preset surface layout can be decomposed into multiple controllable steps. This scheme reduces the design difficulty of the preset surface layout, allowing the incident and exit surfaces of the spiral scanning disk to perform light phase modulation and light deflection based on the obtained preset surface layout, thereby ensuring stable scanning of the target beam along the preset Archimedean spiral path and facilitating engineering implementation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of an Archimedes spiral scanner for a lidar system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the spiral scanning disk in an Archimedes spiral scanner for a lidar system according to an embodiment of the present invention; Figure 3 A schematic diagram of the surface shape of the constant velocity spiral scanning plate and the constant angle spiral scanning plate in the rectangular coordinate system and the polar coordinate system in an Archimedes spiral scanner for a lidar system provided in an embodiment of the present invention; Figure 4 A computer-aided design model diagram of an equal-speed spiral scanning plate and an equal-angle spiral scanning plate in an Archimedes spiral scanner for a lidar system, provided as an embodiment of the present invention; Figure 5 This is a schematic diagram of the overall structure of an Archimedes spiral scanner for a lidar system according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the Archimedean spiral scanning path and its wave vector decomposition in an Archimedean spiral scanner for a lidar system according to an embodiment of the present invention. Figure 7 This is a schematic diagram of the spiral coordinate mapping principle in an Archimedes spiral scanner for a lidar system provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the phase rotation of the spiral coordinate mapping in an Archimedes spiral scanner for a lidar system according to an embodiment of the present invention; Figure 9A flowchart of a scanning method for a lidar system is provided in one embodiment of the present invention; The components are: 1. Laser generator; 2. Beam reducer; 3. Single motor; 4. Spiral scanning disk; 5. Surface shape of the constant velocity spiral scanning plate in Cartesian coordinate system; 6. Surface shape of the constant velocity spiral scanning plate in polar coordinate system; 7. Surface shape of the equiangular spiral scanning plate in Cartesian coordinate system; 8. Surface shape of the equiangular spiral scanning plate in polar coordinate system; 9. Computer-aided design model of the constant velocity spiral scanning plate; 10. Computer-aided design model of the equiangular spiral scanning plate; 11. First lens in the beam reducer; 12. Second lens in the beam reducer; 13. Constant velocity spiral scanning path; 14. Equiangular spiral scanning path; 15. Constant velocity spiral scanning lattice when the number of scanning cycles N=10; 16. Equiangular spiral scanning lattice when the number of scanning cycles N=10; 17. Archimedean spiral scanning path in wave vector space; 18. Schematic diagram of spiral coordinate mapping principle; 19. Original spiral coordinate mapping phase; 20. Spiral coordinate mapping phase after rotation of 45°. Detailed Implementation

[0025] 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.

[0026] This embodiment provides an Archimedes spiral scanner for a lidar system. The monolithic rotating Archimedes spiral scanner includes a laser generator, a beam shrinker, a spiral scanning disk, and a single motor. The laser generator is used to generate an initial optical signal, so that the initial optical signal is sent to the beam reducer through the laser output terminal of the laser generator; The beam shrinker is used to shrink the initial optical signal along the optical axis and output the shrunken beam to the spiral scanning disk. The spiral scanning disk is used to deflect the beam of light from the beam-contracting beam and output the target beam to the target scanning position; The single motor is used to drive the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

[0027] In this embodiment, the initial optical signal generated by the laser generator is beam-constricted along the optical axis by a beam reducer and output as a beam-constricted beam to a spiral scanning disk. The spiral scanning disk deflects the beam-constricted beam. Simultaneously, a single motor drives the spiral scanning disk to rotate around the optical axis, causing the spiral scanning disk to continuously change its deflection state of the beam-constricted beam during rotation. This causes the target beam output by the spiral scanning disk to sequentially point to each target scanning position along a preset Archimedean spiral path, thus forming an Archimedean spiral radar scanning field. Therefore, this embodiment uses only a single motor to drive the rotation of a single spiral scanning disk, that is, it directly generates a two-dimensional spiral scanning trajectory by relying solely on the rotational motion of a single optical element. It eliminates the need for multiple sets of drive components and complex synchronous control, thereby significantly simplifying the structure of the lidar system, reducing the difficulty of assembly and debugging, and improving scanning stability and reliability through the inertia-free characteristics of continuous rotational motion.

[0028] Further, the beam shortener includes a first convex lens and a second convex lens, which are arranged at intervals along the optical axis. The beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal, so that the initial light signal is focused based on the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the second convex lens and outputs a narrowed beam to the spiral scanning disk.

[0029] In this embodiment, the beam shrinker employs a first convex lens and a second convex lens arranged at intervals along the optical axis. The initial optical signal is focused by the first convex lens, and the focused beam is output to the second convex lens. The focused beam is then collimated by the second convex lens, and the resulting beam shrinks to the spiral scanning disk. Through the focusing effect of the first convex lens and the collimating effect of the second convex lens, the initial optical signal is shrinked along the optical axis, resulting in a beam with a reduced diameter. This embodiment uses only two convex lenses, resulting in a simple structure, minimal light energy loss, and the ability to output a high-quality beam shrinking beam. This ensures that the beam shrinking beam is accurately incident on the spiral scanning disk, providing stable incident conditions for subsequent light deflection, and thus facilitating laser scanning of the target beam along a preset Archimedean spiral path.

[0030] Furthermore, the beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal so that the initial light signal is focused based on the preset first focal length of the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the preset second focal length of the second convex lens, and the beam is output to the spiral scanning disk; Specifically, a first focal length and a second focal length are preset based on the surface shape parameters of the spiral scanning disk, so that the diameter of the beam-contracting beam matches the local curvature of the spiral scanning disk.

[0031] In this embodiment, the preset first focal length of the first convex lens and the preset second focal length of the second convex lens are preset according to the surface shape parameters of the spiral scanning disk, so that the diameter of the beam-contracting beam matches the local curvature of the spiral scanning disk. The spiral scanning disk has a continuously changing surface shape, and the local curvature is different at different radial positions. If the diameter of the beam-contracting beam is too large, the beam will simultaneously cover multiple regions with different local curvatures, resulting in inconsistent light deflection; if the diameter of the beam-contracting beam is too small, the light energy utilization rate will be reduced. By presetting the first and second focal lengths according to the surface shape parameters, the diameter of the beam-contracting beam is precisely controlled to match the local curvature of the spiral scanning disk, ensuring that the beam-contracting beam propagates within a single local curvature region of the spiral scanning disk. This ensures that when the target beam performs laser scanning along the preset Archimedean spiral path, the divergence angle of the scanning spot is uniformly distributed, improving the scanning resolution and the consistency of the scanning field.

[0032] Please see Figure 1 and Figure 2 In one embodiment, the Archimedes spiral scanner for a lidar system includes a laser generator 1, a beam reducer 2, a single motor 3, and a spiral scanning disk 4.

[0033] The laser output end of the laser generator 1 is aligned with the beam reducer 2 to generate an initial optical signal, so that the initial optical signal is sent to the beam reducer 2 through the laser output end.

[0034] The beam reducer 2 consists of two focal lengths respectively. and The first convex lens 11 and the second convex lens 12 are configured to compress the initial optical signal along the optical axis and output the compressed beam to the spiral scanning disk 4.

[0035] The single motor 3 is a DC adjustable speed motor, used to drive the spiral scanning disk 4 to rotate around the optical axis.

[0036] The spiral scanning disk 4 is loaded with a specially designed surface shape or phase distribution to deflect the beam of light passing through the scanning disk and output the target beam to the target scanning position. When the spiral scanning disk 4 is rotated under the drive of a single motor 3, the local normal vector at the laser incident point changes continuously, so that the spiral scanning disk 4 continuously changes its deflection state of the beam of light during the rotation, thereby causing the target beam output by the spiral scanning disk 4 to perform laser scanning along a preset Archimedean spiral path, forming an Archimedean spiral radar scanning field.

[0037] from Figure 1 As can be seen, there is a gap between the beam reducer 2 and the spiral scanning disk 4. By precisely adjusting the distance d between the two convex lenses in the beam reducer 2, the local curvature of the spiral scanning disk 4 can be matched to achieve the optimal scanning spot output, making the divergence angle of the scanning spot uniformly distributed throughout the scanning field. It should be noted that the spiral scanning disk 4 has a continuously changing surface shape, and the local curvature is different at different radial positions. If the diameter of the beam reducer is too large, the beam will simultaneously cover multiple regions with different local curvatures, resulting in inconsistent light deflection. If the diameter of the beam reducer is too small, the light energy utilization rate will be reduced.

[0038] By precisely adjusting the distance d between the two convex lenses, the diameter of the beam-contracting beam can be accurately controlled to match the local curvature of the spiral scanning disk 4. This ensures that the beam-contracting beam propagates within a single local curvature region of the spiral scanning disk 4, thereby guaranteeing that the divergence angle of the scanning spot is uniformly distributed when the target beam is laser-scanned along a preset Archimedean spiral path, thus improving the scanning resolution and the consistency of the scanning field.

[0039] In some embodiments of this example, in order to fully utilize the beam deflection effect, the incident laser beam should be precisely incident on the center position of the annulus of the spiral scanning disk 4. Deviating from the center will cause deformation of the spiral scanning field.

[0040] In some embodiments of this example, the spiral scanning disk 4 can be manufactured by single-point diamond turning, and its material can be polymethyl methacrylate (PMMA) or quartz glass. In this embodiment, the spiral scanning disk 4 is shaped by turning the spiral scanning disk surface on the surface of a polymethyl methacrylate (PMMA) sheet. This process enables precise control and helical scanning of the laser beam.

[0041] In this embodiment, the spiral scanning mode can be achieved by adjusting the spiral scanning disk surface shape coefficient. When parameter n=1 / 2, it is a constant velocity spiral scan; when parameter n=1, it is an equal angle spiral scan. It should be noted that parameter n is a fundamental parameter in the Archimedes spiral parametric equation. When generating the phase or surface shape of the spiral scanning disk, it can be set via software code. The Archimedes spiral principle corresponding to this parameter is a well-known basic mathematical principle, and this embodiment only borrows this principle to design the beam scanning device.

[0042] In this embodiment, a single motor 3 drives a single spiral scanning disk 4 to rotate. That is, the two-dimensional spiral scanning trajectory is directly generated by the rotational motion of a single optical element. There is no need to configure multiple sets of driving components and complex synchronization control, which significantly simplifies the structure of the lidar system, reduces the difficulty of assembly and debugging, and improves the scanning stability and reliability through the non-inertia characteristics of continuous rotational motion.

[0043] Furthermore, the spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The spiral scanning disk is used to deflect the beam of light from the narrowed beam and output the target beam to the target scanning position, including: The incident surface of the spiral scanning disk is used to receive the beam contraction, so that the beam contraction locally generates light phase modulation based on the preset surface shape of the incident surface to obtain modulated light. The exit surface of the spiral scanning disk is used to receive the modulated light, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

[0044] In this embodiment, both the incident and exit surfaces of the spiral scanning disk are provided with preset surface layouts. The incident surface is used to perform light phase modulation on the beam-contracting beam to obtain modulated light; the exit surface is used to deflect the modulated light to output the target beam to the target scanning position. By setting the light phase modulation function and the light deflection function on the incident and exit surfaces respectively, the mutual constraints of surface parameters caused by simultaneously implementing two functions on the same surface can be avoided. The incident surface independently applies precise light phase modulation to the beam-contracting beam based on its preset surface layout, and the exit surface then independently deflects the modulated light based on its preset surface layout. This embodiment allows the preset surface layout of each surface to be optimized individually for its respective function, thereby improving the accuracy of light phase modulation and light deflection, and ensuring that the target beam is accurately scanned to the target scanning position along the preset Archimedean spiral path.

[0045] Please see Figure 3 and Figure 4 In one embodiment, Figure 3 The diagrams show the surface shapes of the constant velocity spiral scanning plate and the constant angle spiral scanning plate in rectangular coordinate system and polar coordinate system, respectively. Figure 4A computer-aided design (CAD) model of the constant velocity spiral scanning plate 9 and the constant angle spiral scanning plate 10 is shown. In this embodiment, the spiral scanning disk 4 has a preset surface layout on both its incident and exit surfaces. This layout is used to phase modulate and deflect the incident beam emitted by the laser generator 1 and then compressed by the beam reducer 2, thereby achieving Archimedean spiral scanning. The incident surface of the spiral scanning disk 4 receives the compressed beam, causing the compressed beam to undergo phase modulation based on the preset surface shape of the incident surface, resulting in modulated light. The exit surface of the spiral scanning disk 4 receives the modulated light, causing the modulated light to undergo deflection based on the preset surface shape of the exit surface, outputting the target beam to the target scanning position. By setting the light phase modulation function and the light deflection function on the incident surface and the exit surface respectively, the mutual constraints on the surface shape parameters caused by simultaneously implementing the two functions on the same surface can be avoided. This allows the preset surface shape layout of each surface to be optimized individually for its respective function, thereby improving the accuracy of light phase modulation and light deflection, and ensuring that the target beam is accurately scanned to the target scanning position along the preset Archimedean spiral path. The surface shape of the spiral scanning disk 4 is represented by the following formula: in, , ,coefficient The coefficient is used to control the height of the curved surface to adjust the scanning field of view. Used to control the number of spiral scan cycles, coefficient Used to control the scanning mode, when =1 / 2 is a constant velocity spiral scan, when When =1, it is an equal-angle spiral scan. The size of the scanning plate. and These represent the radial and angular coordinate values ​​in the polar coordinate plane, respectively. This represents the surface shape distribution of a disk-shaped spiral scanning plate in polar coordinates.

[0046] It should be noted that the surface shape distribution of the disk-shaped spiral scanning plate in the polar coordinate system... It is a surface shape in a rectangular coordinate system It is derived through polar coordinate transformation, which transforms the reciprocating motion of the scanning plate into high-speed rotational motion without inertia, thereby obtaining better scanning performance and further improving the scanning stability and reliability of the lidar system.

[0047] It needs to be further explained that, Figure 3In this context, 0 represents the minimum value of the grayscale scale, corresponding to the minimum height of the spiral scanning plate surface; 1 represents the maximum value of the grayscale scale, corresponding to the maximum height of the spiral scanning plate surface. Polar coordinate transformation is the process of converting the spiral scanning plate surface in the rectangular coordinate system to the spiral scanning plate surface in the polar coordinate system.

[0048] Furthermore, the specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

[0049] In this embodiment, the preset surface layout is determined step-by-step by acquiring the target scanning mode and setting the spiral mode coefficient, spiral size coefficient, and spiral period coefficient through preset Archimedean spiral parameter equations, preset coordinate rotation transformation relationships, and preset polar coordinate transformation relationships. Since designing a disk-shaped surface distribution directly in the polar coordinate system is highly complex, the initial surface distribution is first obtained in the Cartesian coordinate system. Then, the spiral coordinate mapping phase in the rotated coordinate system is obtained by rotating by a preset angle. Finally, it is transformed into a disk-shaped surface distribution in the polar coordinate system through preset polar coordinate transformation relationships. This approach decomposes the surface design of the spiral scanning disk into multiple controllable steps. This embodiment reduces the design difficulty of the preset surface layout, enabling the incident and exit surfaces to perform precise light phase modulation and light deflection on the beam-shrinking beam based on the obtained preset surface layout, thereby ensuring stable scanning of the target beam along the preset Archimedean spiral path.

[0050] Furthermore, the target scanning mode includes a constant velocity spiral scanning mode and a constant angle spiral scanning mode, wherein: When the target scanning mode is a constant velocity spiral scanning mode, the spiral mode coefficient is determined to be half, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is half. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the radial distribution relationship of the surface slope along the radial direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the square root of the radius. Based on the radial distribution relationship, the preset surface layout of the spiral scanning disk is determined. When the target scanning mode is an isoangular spiral scanning mode, the spiral mode coefficient is set to one, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is one. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the tangential distribution relationship of the surface slope along the tangential direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the radius. Based on the tangential distribution relationship, the preset surface layout of the spiral scanning disk is determined.

[0051] In this embodiment, the target scanning modes include a constant-velocity spiral scanning mode and an isoangular spiral scanning mode, corresponding to spiral mode coefficients of 1 / 2 and 1, respectively. When the spiral mode coefficient is 1 / 2, the exponent of the change in surface height with the horizontal and vertical coordinates in the initial surface distribution in the Cartesian coordinate system is 1 / 2. After a preset coordinate rotation transformation and a preset polar coordinate transformation, a radial distribution relationship is obtained in the polar coordinate system where the radial slope of the disk-shaped surface distribution is inversely proportional to the square root of the radius. The preset surface layout determined based on this radial distribution relationship enables the target beam to achieve constant-velocity spiral scanning. When the spiral mode coefficient is 1, the exponent of the change in surface height with the horizontal and vertical coordinates in the initial surface distribution in the Cartesian coordinate system is 1. After a preset coordinate rotation transformation and a preset polar coordinate transformation, a tangential distribution relationship is obtained in the polar coordinate system where the tangential slope of the disk-shaped surface distribution is inversely proportional to the radius. The preset surface layout determined based on this tangential distribution relationship enables the target beam to achieve isoangular spiral scanning. The target scanning mode can be switched by selecting the spiral mode coefficient without changing the hardware structure.

[0052] Please see Figure 5 In one specific embodiment of the present invention, Figure 5The diagrams show the Archimedean spiral scanning paths and scanning dot matrix diagrams corresponding to two target scanning modes. Figure 13 in the upper left shows the target beam scanning path in the constant velocity spiral scanning mode, Figure 14 in the upper right shows the target beam scanning path in the equal angle spiral scanning mode, Figure 15 in the lower left shows the scanning dot matrix distribution in the constant velocity spiral scanning mode when the number of scanning cycles N=10, and Figure 16 in the lower right shows the scanning dot matrix distribution in the equal angle spiral scanning mode when the number of scanning cycles N=10. 0 represents the minimum value of the grayscale scale, corresponding to the lowest grayscale value of the light spot in the scanning dot matrix; 1 represents the maximum value of the grayscale scale, corresponding to the highest grayscale value of the light spot in the scanning dot matrix.

[0053] In this embodiment, by acquiring different target scanning modes, different spiral mode coefficients can be set accordingly. Combined with preset spiral size coefficients and spiral period coefficients, and following the aforementioned preset surface layout setting process, a preset surface layout of the spiral scanning disk adapted to different scanning modes is obtained. This allows the target beam to scan along the corresponding preset Archimedean spiral path, enabling flexible switching of scanning modes without changing the hardware structure of the lidar system.

[0054] When the target scanning mode is a constant velocity spiral scanning mode, the spiral mode coefficient is determined to be half. At this time, the exponent of the surface height changing with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is half. After preset coordinate rotation transformation and preset polar coordinate transformation, the radial distribution relationship in the disk-shaped surface distribution in the polar coordinate system is obtained, where the radial slope of the surface is inversely proportional to the square root of the radius. The preset surface layout determined based on this radial distribution relationship causes the target beam to form as follows: Figure 5 The constant velocity spiral scanning path shown in mark 13 has a constant linear velocity of the target beam along the spiral. When the number of scanning cycles N=10, the corresponding scanning dot distribution is as follows. Figure 5 As shown in mark 15, the dot matrix is ​​uniformly distributed throughout the entire scanning field, which ensures that the lidar has a consistent scanning frame rate and point cloud density across the entire field of view.

[0055] When the target scanning mode is an isoangular spiral scanning mode, the spiral mode coefficient is set to one. At this time, the exponent of the surface height variation with the horizontal and vertical coordinates in the initial surface distribution in the Cartesian coordinate system is one. After preset coordinate rotation transformation and preset polar coordinate transformation, the tangential distribution relationship in the disk-shaped surface distribution in the polar coordinate system is obtained, where the surface slope along the tangential direction is inversely proportional to the radius. Based on this tangential distribution relationship, the preset surface layout determines the target beam formation as follows: Figure 5 The isoangular spiral scanning path, marked 14, maintains a constant angular increment for each rotation of the target beam. When the number of scanning cycles N=10, the corresponding scanning dot distribution is as follows. Figure 5As shown in mark 16, the dot matrix is ​​more densely distributed in the central region of the scanning field, which can improve the detection accuracy of the lidar for targets in the central field of view.

[0056] It should be noted that, Figure 5 The grayscale scale of the scanning dot matrix is ​​used to represent the grayscale value of the light spot, where 0 corresponds to the lowest grayscale value and 1 corresponds to the highest grayscale value. The distribution of grayscale values ​​intuitively reflects the distribution of light spot energy in the scanning field under different scanning modes. This embodiment can switch between constant velocity spiral scanning and constant angle spiral scanning modes using a single spiral scanning disk, which can adapt to the detection requirements of different lidar systems, while ensuring the accuracy of the scanning path and the uniformity of the scanning dot matrix, further improving the versatility and detection performance of the lidar system.

[0057] Please see Figure 6 , Figure 7 and Figure 8 In one embodiment, Figure 6 , Figure 7 and Figure 8 This illustrates the core principle of the spiral scanning disk preset surface layout design of the present invention. The light wave vector moving along the spiral scanning path can be orthogonally decomposed into two independent wave-component vectors in the x and y directions. and Similarly, independent wave vectors in the x and y directions and Vector synthesis can also be performed to obtain a new vector moving along the spiral path. Based on this principle of vector synthesis and decomposition, by simply adjusting the incident wave vector in the x and y directions, any scanning path can be generated in space, including the Archimedean spiral scanning path described in this invention. According to the parametric equations of the Archimedean spiral: Among them, coefficient This is the helix size coefficient, used to control the overall size of the helix; This is the spiral period coefficient, used to control the number of spiral periods; coefficient These are the spiral mode coefficients, used to control the scanning mode. When = 1 / 2 corresponds to the constant velocity spiral scanning mode, when =1 corresponds to the equal-angle spiral scanning mode.

[0058] From this, we can obtain the surface distribution formulas for controlling the wave vectors in the x and y directions respectively: It should be noted that, since light waves are vectors and satisfy the rules of vector composition and decomposition, the manipulation of light waves by a freeform surface can be decomposed into independent manipulations in the x and y directions. The manipulations in these two directions do not interfere with each other. Therefore, the formula for the overall initial surface distribution in the Cartesian coordinate system can be obtained as follows: When the incident ray remains stationary, and the initial surface shape (or phase distribution) is translated along a 45° direction on the xoy plane, Wave vector of direction Subject only to the regulation of the first item, Wave vector of direction Only subject to the regulation of the second term, at this time the wave vector and The composite trajectory in space is the Archimedes spiral, thus achieving the effect of generating a two-dimensional spiral scan by translating the scanning plate in only one dimension.

[0059] It should be noted that if the scanning plate is driven by translational reciprocating motion, it will be affected by mechanical inertia, resulting in a low scanning frequency and easy scanning field distortion. Therefore, it is necessary to convert the translational motion into rotational motion without inertia, that is, to convert the surface distribution in the rectangular coordinate system into the circular ring surface distribution in the polar coordinate system, in order to overcome the influence of mechanical inertia and achieve high-speed and stable scanning.

[0060] To achieve the transformation of the above motion form, the spiral coordinate mapping phase needs to be rotated by 45° to obtain a new coordinate mapping phase 20. The corresponding surface shape formula becomes: in, , Or 1, This refers to the size of the scanning plate.

[0061] Next, a polar coordinate transformation is performed on the rotated surface to obtain a disk-shaped surface in polar coordinates. The polar coordinate transformation formula used is: in, Through the above polar coordinate transformation, the surface shape distribution in the rectangular coordinate system can be obtained. Transform into a disk-shaped surface in polar coordinates Therefore, the surface shape of the spiral scanning plate in the polar coordinate system is represented by the following formula: in , and These represent the radial and angular coordinate values ​​in the polar coordinate plane, respectively. This represents the surface shape distribution of a disk-shaped spiral scanning plate in polar coordinates.

[0062] The design process of the aforementioned preset surface layout is completely consistent with the step-by-step setting method described above in this invention, namely, firstly, the target scanning mode is obtained and the corresponding spiral mode coefficient n and spiral size coefficient are determined. and spiral period coefficient The initial surface distribution in a Cartesian coordinate system is obtained based on the preset Archimedean spiral parameter equations. Then, the initial surface distribution is rotated by 45° to obtain the spiral coordinate mapping phase in the rotated coordinate system. Finally, it is transformed into a disk-shaped surface distribution in a polar coordinate system through a preset polar coordinate transformation relationship, thus determining the preset surface layout of the spiral scanning disk. This step-by-step design method decomposes the originally complex disk-shaped surface design in polar coordinates into multiple controllable and simple steps, significantly reducing the design difficulty while ensuring the accuracy of the surface distribution. This allows the incident and exit surfaces of the spiral scanning disk to precisely modulate the phase of the beam and deflect the beam based on the obtained preset surface layout, thereby ensuring stable scanning of the target beam along the preset Archimedean spiral path.

[0063] It should be noted that, Figure 6 This is a schematic diagram of the Archimedean spiral scanning path and its wave vector decomposition according to an embodiment of the present invention. The left figure shows the Archimedean spiral scanning path in the wave vector space, and the right figure shows the curves of the x-direction and y-direction wave vectors obtained by the decomposition of the scanning path as a function of the scanning path length. The wave vector in the x-direction; y is the wave vector in the y direction; L is the scanning path length. Figure 7 This is a schematic diagram of the spiral coordinate mapping principle according to an embodiment of the present invention, showing the physical process by which incident light generates an Archimedean spiral scanning path through spiral coordinate mapping after passing through the scanning plate; The incident light wave vector; denoted as the outgoing light wave vector; O is the origin of the coordinate system; C is the incident point on the scanning plate and the center point of the phase modulation region; x, y, z are the coordinate axes of the three-dimensional rectangular coordinate system; u, v are the coordinate axes of the scanning plane coordinate system; The scanning plate surface shape distribution is shown in a rectangular coordinate system; 45° is the angle between the scanning plate and the x-axis and the phase rotation angle; the spiral coordinate mapping is the transformation process of mapping the coordinates on the scanning plate to the Archimedean spiral coordinates on the scanning plane. Figure 8This is a schematic diagram of the phase rotation of the spiral coordinate mapping according to an embodiment of the present invention. The left figure shows the original spiral coordinate mapping phase distribution, and the right figure shows the spiral coordinate mapping phase distribution after rotation by 45°. The phase modulation region is the area on the scanning plate used to modulate the phase of the incident beam.

[0064] Furthermore, the single motor is used to drive the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, including: The single motor is used to drive the spiral scanning disk to rotate around the optical axis based on a preset motor angular velocity, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, wherein the scanning frame rate of the Archimedean spiral radar scanning field is proportional to the preset motor angular velocity.

[0065] In this embodiment, a single motor drives the helical scanning disk to rotate around the optical axis based on a preset motor angular velocity, and the scanning frame rate of the Archimedean spiral radar scanning field is proportional to the preset motor angular velocity. The scanning frame rate is determined by the time it takes for the helical scanning disk to complete one full rotation cycle. Each rotation of the single motor completes one full laser scanning cycle along the preset Archimedean spiral path, forming one frame of the Archimedean spiral radar scanning field. By adjusting the preset motor angular velocity, the scanning frame rate can be directly and linearly changed without the need for additional synchronization control components. Simultaneously, the continuous rotation of the helical scanning disk around the optical axis driven by the single motor avoids the start-stop inertia caused by discontinuous motion, resulting in a smooth and continuous scanning trajectory of the target beam along the preset Archimedean spiral path, thereby improving the scanning stability and reliability of the Archimedean spiral radar scanning field.

[0066] Please see Figure 9 This embodiment also provides a scanning method for a lidar system. The method is applied to an Archimedean spiral scanner used in a lidar system. The Archimedean spiral scanner includes a laser generator, a beam reducer, a spiral scanning disk, and a single motor. The method includes the following steps: Step S1: Generate an initial optical signal based on the laser generator, and send the initial optical signal to the beam shortener through the laser output terminal of the laser generator; Step S2: Based on the beam shrinker, the initial optical signal is beam-shrinked along the optical axis, and the beam-shrinking beam is output to the spiral scanning disk; Step S3: Based on the spiral scanning disk, the beam of light is deflected and the target beam is output to the target scanning position; Step S4: Based on the single motor driving the spiral scanning disk to rotate around the optical axis, the target beam output by the spiral scanning disk is laser scanned along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

[0067] In this embodiment, Archimedean spiral scanning is achieved through the steps of generating an initial light signal with a laser generator, beam contraction by a beam shortener, deflection of the light by a spiral scanning disk, and rotation of the spiral scanning disk around the optical axis by a single motor. The laser generator generates an initial light signal, which is then contracted along the optical axis by the beam shortener and output to the spiral scanning disk. The spiral scanning disk deflects the contracted light beam, outputting a target beam to the target scanning position. Simultaneously, a single motor drives the spiral scanning disk to rotate around the optical axis, causing the target beam output by the spiral scanning disk to perform laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field. This embodiment uses only a single motor to drive the spiral scanning disk to rotate, directly generating a two-dimensional spiral scanning trajectory through the deflection of light from a single spiral scanning disk. This eliminates the need for multiple drive components and complex synchronization control, simplifying the structure of the lidar system, reducing assembly and debugging difficulty, and improving scanning stability and reliability through continuous rotational motion.

[0068] Furthermore, the spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The step of deflecting the beam of light based on the spiral scanning disk and outputting the target beam to the target scanning position includes: The beam is received on the incident surface of the spiral scanning disk, so that the beam is locally phase-modulated based on the preset surface shape of the incident surface to obtain modulated light. The modulated light is received by the exit surface of the spiral scanning disk, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

[0069] In this embodiment, the spiral scanning disk achieves beam deflection by modulating the beam phase at the incident surface and deflecting the beam at the exit surface. The contracted beam is incident on the incident surface, and localized phase modulation occurs based on a preset surface shape, resulting in modulated light. The modulated light is then incident on the exit surface, and localized deflection occurs based on the preset surface shape, outputting the target beam to the target scanning position. By setting the beam phase modulation and deflection on the incident and exit surfaces respectively, the mutual constraints on surface parameters caused by simultaneously implementing two functions on the same surface are avoided. The incident surface can independently apply precise beam phase modulation to the contracted beam, and the exit surface can independently and precisely deflect the modulated light, thereby increasing the degree of freedom in beam control, reducing beam phase modulation and deflection errors, improving the deflection efficiency and scanning accuracy of the target beam, and ensuring that the target beam accurately reaches the target scanning position along a preset Archimedean spiral path.

[0070] Furthermore, the specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

[0071] In this embodiment, the preset surface layout is determined step-by-step by acquiring the target scanning mode and setting the spiral pattern based on the spiral mode coefficient, spiral size coefficient, and spiral period coefficient, through preset Archimedean spiral parameter equations, preset coordinate rotation transformation relationships, and preset polar coordinate transformation relationships. Directly determining the preset surface layout based on the disk-shaped surface distribution in polar coordinates is highly complex. Instead, by first obtaining the initial surface distribution in Cartesian coordinates based on the preset Archimedean spiral parameter equations, then rotating the initial surface distribution by a preset angle based on the preset coordinate rotation transformation relationship to obtain the spiral coordinate mapping phase in the rotated coordinate system, and finally transforming the spiral coordinate mapping phase into a disk-shaped surface distribution in polar coordinates based on the preset polar coordinate transformation relationship, the setting of the preset surface layout can be decomposed into multiple controllable steps. This embodiment reduces the design difficulty of the preset surface layout, allowing the incident and exit surfaces of the spiral scanning disk to perform light phase modulation and light deflection based on the obtained preset surface layout, thereby ensuring stable scanning of the target beam along the preset Archimedean spiral path and facilitating engineering implementation.

[0072] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An Archimedean spiral scanner for a lidar system, characterized in that, The Archimedes spiral scanner includes a laser generator, a beam reducer, a spiral scanning disk, and a single motor; The laser generator is used to generate an initial optical signal, so that the initial optical signal is sent to the beam reducer through the laser output terminal of the laser generator; The beam shrinker is used to shrink the initial optical signal along the optical axis and output the shrunken beam to the spiral scanning disk. The spiral scanning disk is used to deflect the beam of light from the beam-contracting beam and output the target beam to the target scanning position; The single motor is used to drive the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

2. An Archimedean spiral scanner for a lidar system according to claim 1, characterized in that, The beam shortener includes a first convex lens and a second convex lens, which are arranged at intervals along the optical axis. The beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal, so that the initial light signal is focused based on the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the second convex lens and outputs a narrowed beam to the spiral scanning disk.

3. An Archimedean spiral scanner for a lidar system according to claim 2, characterized in that, The beam shortener is used to shorten the initial optical signal along the optical axis and output the shortened beam to the spiral scanning disk, including: The first convex lens is used to receive the initial light signal so that the initial light signal is focused based on the preset first focal length of the first convex lens, and the focused beam is output to the second convex lens; The second convex lens is used to receive the focused beam so that the focused beam is collimated based on the preset second focal length of the second convex lens, and the beam is output to the spiral scanning disk; Specifically, a first focal length and a second focal length are preset based on the surface shape parameters of the spiral scanning disk, so that the diameter of the beam-contracting beam matches the local curvature of the spiral scanning disk.

4. An Archimedean spiral scanner for a lidar system according to claim 1, characterized in that, The spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The spiral scanning disk is used to deflect the beam of light from the narrowed beam and output the target beam to the target scanning position, including: The incident surface of the spiral scanning disk is used to receive the beam contraction, so that the beam contraction locally generates light phase modulation based on the preset surface shape of the incident surface to obtain modulated light. The exit surface of the spiral scanning disk is used to receive the modulated light, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

5. An Archimedean spiral scanner for a lidar system according to claim 4, characterized in that, The specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

6. An Archimedean spiral scanner for a lidar system according to claim 5, characterized in that, The target scanning modes include constant velocity spiral scanning mode and constant angle spiral scanning mode, wherein: When the target scanning mode is a constant velocity spiral scanning mode, the spiral mode coefficient is determined to be half, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is half. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the radial distribution relationship of the surface slope along the radial direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the square root of the radius. Based on the radial distribution relationship, the preset surface layout of the spiral scanning disk is determined. When the target scanning mode is an isoangular spiral scanning mode, the spiral mode coefficient is set to one, so that the exponent of the change of surface height with the horizontal and vertical coordinates in the initial surface distribution in the rectangular coordinate system is one. Then, after the initial surface distribution is transformed by the preset coordinate rotation and preset polar coordinates, the tangential distribution relationship of the surface slope along the tangential direction in the disk-shaped surface distribution in the polar coordinate system is obtained, which is inversely proportional to the radius. Based on the tangential distribution relationship, the preset surface layout of the spiral scanning disk is determined.

7. An Archimedean spiral scanner for a lidar system according to claim 1, characterized in that, The single motor drives the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, including: The single motor is used to drive the spiral scanning disk to rotate around the optical axis based on a preset motor angular velocity, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field, wherein the scanning frame rate of the Archimedean spiral radar scanning field is proportional to the preset motor angular velocity.

8. A scanning method for a lidar system, characterized in that, This method is applied to an Archimedean spiral scanner for a lidar system, the Archimedean spiral scanner including a laser generator, a beam shortener, a spiral scanning disk, and a single motor, and the method includes the following steps: The laser generator generates an initial optical signal, which is then transmitted to the beam shortener through the laser output terminal of the laser generator. The initial optical signal is compressed along the optical axis by the beam shortener, and the compressed beam is output to the spiral scanning disk. Based on the spiral scanning disk, the beam of light is deflected and the target beam is output to the target scanning position; The single motor drives the spiral scanning disk to rotate around the optical axis, so that the target beam output by the spiral scanning disk performs laser scanning along a preset Archimedean spiral path, thereby forming an Archimedean spiral radar scanning field.

9. A scanning method for a lidar system according to claim 8, characterized in that, The spiral scanning disk has a preset surface layout on both its incident and exit surfaces. The step of deflecting the beam of light from the converging beam based on the spiral scanning disk and outputting the target beam to the target scanning position includes: The beam is received on the incident surface of the spiral scanning disk, so that the beam is locally phase-modulated based on the preset surface shape of the incident surface to obtain modulated light. The modulated light is received by the exit surface of the spiral scanning disk, so that the modulated light is locally deflected based on the preset surface shape of the exit surface, and the target beam is output to the target scanning position.

10. A scanning method for a lidar system according to claim 9, characterized in that, The specific process for setting the preset surface layout is as follows: Obtain the target scanning pattern, and determine the spiral mode coefficient, spiral size coefficient, and spiral period coefficient based on the target scanning pattern; The initial surface distribution in the Cartesian coordinate system is obtained based on the preset Archimedes spiral parameter equation, the spiral mode coefficient, the spiral size coefficient, and the spiral period coefficient. Based on a preset coordinate rotation transformation relationship, the initial surface distribution is rotated by a preset angle to obtain the spiral coordinate mapping phase in the rotated coordinate system; Based on a preset polar coordinate transformation relationship, the phase of the spiral coordinate mapping in the rotated coordinate system is transformed into a disk-shaped surface distribution in the polar coordinate system; The preset surface layout of the spiral scanning disk is determined based on the disk-shaped surface distribution in the polar coordinate system.

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