Laser radar optical scanning system and laser radar

Abstract

The embodiment of the utility model discloses a laser radar optical scanning system and a laser radar. The laser radar optical scanning system comprises a laser transmitting module, a laser receiving module, a wedge prism module and a motor driving module. The wedge-shaped prism module comprises a first surface and at least two second surfaces, and the extension direction of the first surface intersects with the extension direction of the second surfaces; the motor driving module drives the wedge prism module to rotate around the first rotating shaft; the first rotating shaft is perpendicular to the first surface; the laser emission module emits parallel laser beams to the first surface of the wedge-shaped prism module, and the parallel laser beams are refracted to a target detection area through the wedge-shaped prism module so as to scan the target detection area when the wedge-shaped prism module rotates around the first rotating shaft; the laser receiving module receives the echo laser beam reflected by the target detection area. According to the system, the weight of the wedge prism module is reduced, and the driving power of the motor driving module is reduced.

Description

[0001] This application claims the priority of a Chinese patent application with the application number 2024209887397 and the title "A LiDAR Optical Scanning System and a LiDAR", which was filed with the Chinese Patent Office on May 9, 2024. Part or all of its content is incorporated herein by reference. Technical Field

[0002] Embodiments of the present utility model relate to the technical field of LiDAR, and in particular, to a LiDAR optical scanning system and a LiDAR. Background Art

[0003] The LiDAR optical scanning system is the "eye" of the LiDAR and is also an extremely crucial and important component of the LiDAR. At present, the detection technology of the LiDAR optical scanning system is mainly used for measuring land elevation and shallow sea topography, and can also obtain information such as 3D topographic features of the ocean, seawater quality monitoring, and ocean dynamics characteristics. The development of the LiDAR optical scanning system can meet the high-precision comprehensive measurement in environments such as land, coastal beaches, tides, shallow seas, and island reefs.

[0004] In order to achieve a scanning effect with a large detection area, a large detection field of view, and a high detection resolution, wedge prisms are widely used in the LiDAR optical scanning system. However, due to the large weight of the wedge prism, on the one hand, the stability is poor during rotation, and on the other hand, it is not conducive to the miniaturization design of the LiDAR optical scanning system. Summary of the Utility Model

[0005] Embodiments of the present utility model provide a LiDAR optical scanning system and a LiDAR, which can effectively reduce the weight of the wedge prism module, reduce the power of the motor drive module, and improve the stability of the motor drive rotation.

[0006] In a first aspect, embodiments of the present utility model provide a LiDAR optical scanning system, including a laser emission module, a laser reception module, a wedge prism module, and a motor drive module;

[0007] The wedge prism module includes a first surface and at least two second surfaces, each of the second surfaces is parallel, and the extension direction of the first surface intersects with the extension direction of the second surface;

[0008] The motor drive module drives the wedge prism module to rotate around a first rotation axis; wherein, the first rotation axis is perpendicular to the first surface;

[0009] The laser emission module emits a parallel laser beam to the first surface of the wedge prism module, and the parallel laser beam is refracted by the wedge prism module to the target detection area, so as to scan the target detection area when the wedge prism module rotates around the first rotation axis;

[0010] The laser reception module receives the echo laser beam reflected by the target detection area.

[0011] Optionally, the parallel laser beam emitted by the laser emission module is perpendicularly incident on the first surface of the wedge prism module, and after being refracted by the wedge prism module, it exits from the second surface of the wedge prism module to the target detection area;

[0012] The parallel laser beam is reflected by the target detection area, and is incident on the second surface of the wedge prism module, and after being refracted by the wedge prism module, it exits from the first surface of the wedge prism module to the laser reception module.

[0013] Optionally, the wedge prism module includes at least two wedge prisms, and the number of the wedge prisms is the same as the number of the second surfaces;

[0014] Each of the wedge prisms in the wedge prism module is integrally formed.

[0015] Optionally, the laser emission module includes a laser unit and a beam expanding and collimating unit;

[0016] The laser unit emits an initial laser beam;

[0017] The beam expanding and collimating unit is located on the propagation path of the initial laser beam, and the beam expanding and collimating unit expands and collimates the initial laser beam to obtain the parallel laser beam.

[0018] Optionally, the beam expanding and collimating unit includes a first lens and a second lens which are separately arranged;

[0019] The first lens and the second lens are sequentially located on the propagation path of the initial laser beam;

[0020] The first lens expands the initial laser beam, and the second lens collimates the expanded initial laser beam to obtain the parallel laser beam.

[0021] Optionally, the first lens has a positive optical power, and the second lens has a negative optical power.

[0022] Optionally, the laser emission module further includes a mirror unit;

[0023] The mirror unit is located on the propagation path of the parallel laser beam, and the mirror unit adjusts the propagation direction of the parallel laser beam so that the parallel laser beam is incident on the first surface of the wedge prism module.

[0024] Optionally, the laser receiving module includes a receiving lens unit and a photoelectric detection unit;

[0025] The receiving lens unit and the photoelectric detection unit are sequentially located on the propagation path of the echo laser beam;

[0026] The receiving lens unit converges the echo laser beam;

[0027] The photoelectric detection unit receives the echo laser beam after the converging process.

[0028] Optionally, the photoelectric detection unit is located on the focal plane of the receiving lens unit.

[0029] In a second aspect, an embodiment of the present invention further provides a lidar, including the lidar optical scanning system according to any one of the first aspects.

[0030] An embodiment of the present invention provides a lidar optical scanning system and a lidar. The lidar optical scanning system includes a laser emitting module, a laser receiving module, a wedge prism module, and a motor driving module; the wedge prism module includes a first surface and at least two second surfaces, the second surfaces are parallel to each other, and the extending direction of the first surface intersects with the extending direction of the second surfaces; the motor driving module drives the wedge prism module to rotate around a first rotation axis; wherein, the first rotation axis is perpendicular to the first surface; the laser emitting module emits a parallel laser beam to the first surface of the wedge prism module, and the parallel laser beam is refracted by the wedge prism module to the target detection area, so as to scan the target detection area when the wedge prism module rotates around the first rotation axis; the laser receiving module receives the echo laser beam reflected by the target detection area. The wedge prism module in this lidar optical scanning system includes a first surface and at least two second surfaces, and the wedge prism module presents a structure similar to a serrated shape, effectively reducing the outer diameter and wedge angle of the entire wedge prism module, reducing the weight of the wedge prism module, reducing the driving power of the motor driving module, improving the stability of the rotation process of the motor driving the wedge prism module, and also eliminating the need to set a motor driving module with a high driving power, which can effectively reduce the volume of the motor driving module. Moreover, the structure in this lidar optical scanning system is simple and stable, and can perform 360° scanning on the target detection area when the wedge prism module rotates, with high scanning efficiency, a large scanning field of view angle, improving the accuracy and quantity of information acquisition in the detection area, and also being beneficial to improving the uniformity of the laser point cloud image formed by scanning. Brief Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of a lidar optical scanning system provided by an embodiment of the present utility model;

[0033] Figure 2 It is a schematic overall structural diagram of a wedge prism module provided by an embodiment of the present utility model;

[0034] Figure 3 It is a schematic structural diagram of the first surface of a wedge prism module provided by an embodiment of the present utility model;

[0035] Figure 4 It is a schematic cross-sectional structural diagram of a wedge prism module provided by an embodiment of the present utility model;

[0036] Figure 5 It is a schematic scanning trajectory diagram of a wedge prism module provided by an embodiment of the present utility model;

[0037] Figure 6 It is a schematic scanning principle diagram of a wedge prism module provided by an embodiment of the present utility model;

[0038] Figure 7 It is a schematic scanning principle diagram of a dynamic scanning provided by an embodiment of the present utility model;

[0039] Figure 8 It is a schematic diagram of the wavefront and root mean square radius of a laser beam provided by an embodiment of the present utility model;

[0040] Figure 9 It is a schematic diagram of the full field point spread function of a laser beam provided by an embodiment of the present utility model;

[0041] Figure 10 It is a schematic diagram of the optical modulation transfer function of a laser beam provided by an embodiment of the present utility model;

[0042] Figure 11 It is a schematic diagram of the irradiation intensity of the point spread function of a laser beam provided by an embodiment of the present utility model;

[0043] Figure 12 It is a schematic diagram of another optical modulation transfer function of a laser beam provided by an embodiment of the present utility model;

[0044] Figure 13 It is a schematic diagram of the point spread function of a laser beam in a sub-field of view provided by an embodiment of the present utility model;

[0045] Figure 14 It is a schematic diagram of the point spread function of a laser beam in the full field of view provided by another embodiment of the present utility model;

[0046] Figure 15 It is a schematic diagram of the irradiation intensity of the point spread function of a laser beam provided by another embodiment of the present utility model. Detailed implementation manners

[0047] The present utility model will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present utility model, rather than limiting the present utility model. In addition, it should be noted that, for the sake of description, only parts related to the present utility model are shown in the drawings, rather than all the structures.

[0048] The terms used in the embodiments of the present utility model are only for the purpose of describing specific embodiments, and are not intended to limit the present utility model. It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present utility model are described from the angles shown in the drawings, and should not be construed as limiting the embodiments of the present utility model. In addition, in the context, it should also be understood that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also be indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes, and do not indicate any order, quantity, or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0049] The term "including" and its variations used in the present utility model are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0050] It should be noted that the concepts such as "first" and "second" mentioned in the present utility model are only used to distinguish the corresponding contents, and are not used to limit the order or the interdependent relationship.

[0051] It should be noted that the modifications of "one" and "multiple" mentioned in the present utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0052] Figure 1 It is a schematic structural diagram of a lidar optical scanning system provided by an embodiment of the present utility model. Figure 2 It is a schematic overall structural diagram of a wedge prism module provided by an embodiment of the present utility model. Figure 3 It is a schematic structural diagram of a first surface of a wedge prism module provided by an embodiment of the present utility model. Figure 4 It is a schematic cross-sectional structural diagram of a wedge prism module provided by an embodiment of the present utility model. As Figures 1-4 shown, the lidar optical scanning system includes a laser emission module 10, a laser reception module 20, a wedge prism module 30, and a motor drive module ( Figure 1 and Figure 2 not shown in the figure); the wedge prism module 30 includes a first surface 31 and at least two second surfaces 32, the second surfaces 32 are parallel to each other, and the extension direction of the first surface 31 intersects with the extension direction of the second surfaces 32; the motor drive module drives the wedge prism module 30 to rotate around a first rotation axis 33; wherein, the first rotation axis 33 is perpendicular to the first surface 31; the laser emission module 10 emits a parallel laser beam to the first surface 31 of the wedge prism module 30, and the parallel laser beam is refracted by the wedge prism module 30 to a target detection area, so as to scan the target detection area when the wedge prism module 30 rotates around the first rotation axis 33; the laser reception module 20 receives the echo laser beam reflected by the target detection area.

[0053] Specifically, the lidar optical scanning system includes a laser emission module 10, a laser reception module 20, a wedge prism module 30, and a motor drive module. Among them, the wedge prism module 30 includes a first surface 31 and at least two second surfaces 32, the second surfaces 32 are parallel to each other, and the extension direction of the first surface 31 intersects with the extension direction of the second surfaces 32. Exemplarily, the first surface 31 of the wedge prism module 30 can be a right-angle surface, and the second surface 32 of the wedge prism module 30 can be an inclined surface, and the right-angle surface and the inclined surface form the wedge angle of the wedge prism module 30. In addition, exemplarily, the outer shape of the wedge prism module 30 can be circular, and the cross-sectional shape is wedge-shaped / serrated. In this way, the consistency of the included angle between the extension direction of each second surface 32 and the extension direction of the first surface 31 is ensured, so that the wedge prism module 30 presents a structure similar to a serrated shape. Compared with the structure in which the wedge prism module 30 only includes one first surface 31 and one second surface 32 (the extension direction of the first surface 31 intersects with the extension direction of the second surface 32), this embodiment can effectively reduce the outer diameter and wedge angle of the entire wedge prism module 30, and reduce the weight of the wedge prism module 30.

[0054] The motor drive module can drive the wedge prism module 30 to rotate. As the weight of the wedge prism module 30 decreases, the drive power of the motor drive module can also be reduced. There is no need to set a motor drive module with high drive power, which can effectively reduce the volume of the motor drive module. Moreover, it can also improve the stability and safety of the rotation process of the motor driving the wedge prism module 30. Further, the motor drive module can drive the wedge prism module 30 to rotate around a first rotation axis 33 perpendicular to the first surface 31 to ensure a larger spatial measurement range in the subsequent scanning process. Exemplarily, if the lidar optical scanning system is in a normal horizontal placement state, the motor drive module can drive the wedge prism module 30 to rotate around the first rotation axis 33 in a large range of 360° in the vertical direction, unidirectionally, continuously, and smoothly, and a larger light passing aperture can also be obtained. It should be noted that the horizontal direction and the vertical direction described in this embodiment are two mutually perpendicular directions. In addition, any other mutually perpendicular directions can also be realized, that is, if the wedge prism module 30 is placed on the first plane, the motor drive module can drive the wedge prism module 30 to rotate around the first rotation axis 33 in a large range of 360° in the first direction, unidirectionally, continuously, and smoothly, where the first direction is perpendicular to the first plane.

[0055] In addition, exemplarily, the wedge prism module 30 can be built into the motor drive module, making the internal structure of the entire lidar optical scanning system more compact, effectively reducing the volume and weight of the entire lidar optical scanning system, enabling the lidar optical scanning system to be carried on a smaller unmanned aerial vehicle platform to complete detection work, reducing the working cost, and improving the safety of the working process. Figure 5 It is a schematic diagram of the scanning trajectory of a wedge prism module provided by an embodiment of the present invention. As Figure 5 shown, during the process of the wedge prism module 30 rotating one circle around the first rotation axis 33, the laser beam emitted from the second surface 32 of the wedge prism module 30 can form a complete conical shape, and all point to the target detection area, that is, the scanning trajectories of the scanning points on the target detection area are circular, thereby performing circular scanning on the target detection area. At the same time, the conical scanning trajectory formed by the wedge prism module 30 can achieve ground object saturated coverage scanning, with higher scanning efficiency and a larger scanning field of view.

[0056] The laser emission module 10 can emit a parallel laser beam to the first surface 31 of the wedge prism module 30, and the parallel laser beam can be refracted by the wedge prism module 30 to the target detection area, so as to scan the target detection area when the wedge prism module 30 rotates around the first rotation axis 33. That is, through a rotating wedge prism module 30, the laser beam incident on the first surface 31 of the wedge prism module 30 and emitted from the second surface 32 of the wedge prism module 30 circularly scans the target detection area as the wedge prism module 30 rotates. At this time, the scanning trajectories of the scanning points on the target detection area are circular, and the incident angles of the laser beam emitted from the second surface 32 of the wedge prism module 30 at the scanning points on the target detection area are equal, without the need to pre-calibrate the incident angles at each scanning point, effectively simplifying the usage steps of the lidar optical scanning system and also facilitating the subsequent back-end calculation process of the laser receiving module 20. In addition, exemplarily, the constant incident angle at each scanning point is also beneficial to improving the uniformity of the laser point cloud image formed by scanning. And, exemplarily, during the scanning process of the lidar optical scanning system, the laser emission module 10 can continuously emit laser pulses, and the wedge prism module 30 rotates around the first rotation axis 33 in the same direction at the same time, which is beneficial to improving the scanning efficiency and extending the service life of the optical scanning system.

[0057] The laser receiving module 20 can receive the echo laser beam reflected by the target detection area. Exemplarily, the laser receiving module 20 can receive the echo laser beam that is reflected by the target detection area and transmitted through the wedge prism module 30 in sequence, so that at least part of the propagation path of the parallel laser beam incident on the wedge prism module 30 coincides with the propagation path of the echo laser beam reflected to the wedge prism module 30, which is beneficial to simplifying the rotation process of the wedge prism module 30. Exemplarily, it is beneficial to keep the wedge prism module 30 rotating at a constant speed.

[0058] In the technical solution of the embodiment of the present utility model, the lidar optical scanning system includes a laser emission module, a laser reception module, a wedge prism module, and a motor drive module; the wedge prism module includes a first surface and at least two second surfaces, the second surfaces are parallel to each other, and the extension direction of the first surface intersects with the extension direction of the second surfaces; the motor drive module drives the wedge prism module to rotate around a first rotation axis; wherein, the first rotation axis is perpendicular to the first surface; the laser emission module emits a parallel laser beam to the first surface of the wedge prism module, and the parallel laser beam is refracted by the wedge prism module to the target detection area, so as to scan the target detection area when the wedge prism module rotates around the first rotation axis; the laser reception module receives the echo laser beam reflected by the target detection area. The wedge prism module in the lidar optical scanning system includes a first surface and at least two second surfaces, and the wedge prism module presents a structure similar to a sawtooth, effectively reducing the outer diameter and wedge angle of the entire wedge prism module, reducing the weight of the wedge prism module, reducing the driving power of the motor drive module, improving the stability of the rotation process of the motor driving the wedge prism module, and also eliminating the need to set a motor drive module with high driving power, which can effectively reduce the volume of the motor drive module. Moreover, the structure in the lidar optical scanning system is simple and stable, and can perform 360° scanning on the target detection area when the wedge prism module rotates, with high scanning efficiency, a large scanning field of view, improving the accuracy and quantity of information acquisition in the detection area, and also being beneficial to improving the uniformity of the laser point cloud image formed by scanning.

[0059] Optionally, continuing to refer to Figures 1-4 , the parallel laser beam emitted by the laser emission module 10 is perpendicularly incident on the first surface 31 of the wedge prism module 30, and after being refracted by the wedge prism module 30, exits from the second surface 32 of the wedge prism module 30 to the target detection area; the parallel laser beam is reflected by the target detection area and is incident on the second surface 32 of the wedge prism module 30, and after being refracted by the wedge prism module 30, exits from the first surface 31 of the wedge prism module 30 to the laser reception module 20.

[0060] Specifically, this embodiment mainly describes the propagation path of the laser beam in the lidar optical scanning system. The parallel laser beam emitted by the laser emission module 10 can be perpendicularly incident on the first surface 31 of the wedge prism module 30, and through the refraction of the wedge prism module 30, it exits from the second surface 32 of the wedge prism module 30 to the target detection area. It can be understood that since the parallel laser beam is perpendicularly incident on the first surface 31 of the wedge prism module 30, the incident angle between the parallel laser beam and the first surface 31 of the wedge prism module 30 is the same, and the deflection angle of the parallel laser beam by the wedge prism module 30 is the same. Then, the exit angle between the laser beam exiting from the second surface 32 of the wedge prism module 30 and the second surface 32 of the wedge prism module 30 is also the same. There is no need to pre-calibrate the incident angle and exit angle of the laser beam. That is to say, the laser beam exiting from the second surface 32 of the wedge prism module 30 can also be approximately understood as a parallel laser beam. This parallel laser beam forms a diffuse reflection in the target detection area, and part of the parallel laser beam can "return along the original path". That is, the parallel laser beam is reflected by the target detection area and is incident on the second surface 32 of the wedge prism module 30. This part of the reflected laser beam can also be approximately understood as a parallel laser beam, and the incident angle between this part of the reflected laser beam and the second surface 32 of the wedge prism module 30 can be understood as the same. Through the refraction of the wedge prism module 30, the deflection angle of the parallel laser beam by the wedge prism module 30 is the same. Then, the laser beam exiting from the first surface 31 of the wedge prism module 30 can also be approximately understood as a parallel laser beam. And according to the reversibility of the optical path, this parallel laser beam can perpendicularly exit from the first surface 31 of the wedge prism module 30 and be incident on the laser reception module 20 on the path. In this way, the path of the parallel laser beam from the first surface 31 of the wedge prism module 30 to the second surface 32 of the wedge prism module 30 coincides with the path of the parallel laser beam from the second surface 32 of the wedge prism module 30 to the first surface 31 of the wedge prism module 30, effectively reducing the probability of detection blind spots, ensuring the compactness of the internal structure of the lidar optical scanning system, and being conducive to the miniaturization design of the system. In addition, exemplarily, when the motor drive module drives the wedge prism module 30 to rotate, the parallel laser beam can be perpendicularly incident on the first surface 31 of the wedge prism module 30, or the parallel laser beam can also be incident at a preset angle with respect to the normal of the first surface 31 of the wedge prism module 30. Exemplarily, this preset angle can be determined according to specific detection requirements.

[0061] In addition, the lidar optical scanning system further includes a window plate module 40, which is located on the propagation path of the laser beam emitted from the second surface 32 of the wedge prism module 30, and the window plate module 40 is also located on the propagation path of the laser beam reflected by the target detection area and incident on the second surface 32 of the wedge prism module 30. In this way, the propagation of the emitted laser beam and the incident laser beam share the same window plate module 40, forming a quasi-coaxial emission and reception system, effectively reducing the detection blind area of the lidar optical scanning system and ensuring the compactness of the internal structure of the lidar optical scanning system.

[0062] Optionally, continuing to refer to Figures 1-4 , the wedge prism module 30 includes at least two wedge prisms 34, and the number of wedge prisms 34 is the same as the number of the second surfaces 32; each wedge prism 34 in the wedge prism module 30 is integrally formed.

[0063] Specifically, the wedge prism module 30 can be understood as a combination of multiple wedge prisms 34. In this embodiment, only the case where the wedge prism module 30 includes two wedge prisms 34 is taken as an example for drawing. In fact, the wedge prism module 30 can also include more than two wedge prisms 34. In this embodiment, each wedge prism 34 in the wedge prism module 30 is integrally formed. In this way, the cutting and preparation steps of the wedge prism module 30 can be effectively simplified, and there is no need to combine the single wedge prisms 34 by means of adhesion, etc., avoiding problems such as falling off due to poor adhesion between two adjacent wedge prisms 34 and even the failure of the deflection ability of the wedge prism module 30 to optics. It can be understood that the number of the wedge prisms 34 is not limited in this embodiment, and only a structural diagram of the wedge prism module 30 including two wedge prisms 34 is exemplarily given in the specification drawings. In fact, the number of the wedge prisms 34 can also be other. As the number of the wedge prisms 34 increases, the overall quality of the wedge prism module 30 is further reduced.

[0064] In a specific embodiment, by way of example, the material of the wedge prism module 30 can be H-ZLAF82. The refractive index of the wedge prism module 30 corresponding to this material can be 2.001, the dispersion coefficient of the wedge prism module 30 can be 29.134, the radius of curvature of the first surface 31 of the wedge prism module 30 can be infinite, the radius of curvature of the second surface 32 of the wedge prism module 30 can be infinite, the thickness of the wedge prism module 30 can be 45.4 mm to 47.5 mm, the maximum outer diameter of the wedge prism module 30 can be 140 mm, the clear aperture of the wedge prism module 30 can be 135 mm, antireflection films in the wavelength range of 532 nm ± 10 nm can be provided on both the first surface 31 and the second surface 32 of the wedge prism module 30, the half field of view angle of the incident light beam corresponding to the wedge prism module 30 can be 0 to 20°, the thickness range of the thinnest position of the wedge prism module 30 can be greater than 5 mm, and the weight range of the wedge prism module 30 can be less than 1 kg. In addition, by way of example, the first surface 31 of the wedge prism module 30 can be a right-angle surface, and the second surface 32 of the wedge prism module 30 can be an inclined surface. The right-angle surface and the inclined surface form the wedge angle of the wedge prism module 30. That is, the wedge angles of the respective wedge prisms 34 can be determined according to the material and the field of view angle requirements.

[0065] Optionally, Figure 6 is a schematic diagram of the scanning principle of a wedge prism module provided by an embodiment of the present invention. As Figures 1-6 shown, the scanning field of view angle of the lidar optical scanning system for scanning the target detection area is less than or equal to 20°.

[0066] Specifically, the scanning principle of each wedge prism 34 in the wedge prism module 30 is that when a laser beam passes through the wedge prism 34, the laser beam will be deflected, and the deflection angle of the laser beam is related to the refractive index of the medium and the wedge angle of the wedge prism 34. Exemplarily, according to Snell's law, the deflection ability of the wedge prism module 30 for the laser beam satisfies the formula n1*sin(a) = n2*sin(b), where n1 represents the refractive index of the wedge prism module 30, n2 represents the refractive index of air (the region outside the wedge prism module 30), a represents the angle between the incident laser beam (which can be understood as the laser beam incident on the first surface 31 of the wedge prism module 30) and the normal direction, b represents the angle between the outgoing laser beam (which can be understood as the laser beam exiting from the second surface 32 of the wedge prism module 30) and the normal direction, and this normal direction is perpendicular to the second surface 32 of the wedge prism module 30. That is, the deflection angle c of the outgoing laser beam relative to the incident laser beam is c = b - a. When the deflection angle c of the outgoing laser beam relative to the incident laser beam is constant, during the process of the wedge prism module 30 rotating around the first rotation axis 33 to scan the target detection area, the size of the scanning field of view of the lidar optical scanning system for scanning the target detection area is constant, and the size of the scanning field of view of the lidar optical scanning system for scanning the target detection area is the same as the deflection angle c of the outgoing laser beam relative to the incident laser beam, thus forming a circular scanning trajectory.

[0067] To determine the deflection angle c, it is necessary to first determine the angle b between the outgoing laser beam and the normal direction, and the angle a between the incident laser beam and the normal direction. In the formula n1*sin(a) = n2*sin(b), the refractive index n1 of the wedge prism module 30 can be determined according to the material of the wedge prism module 30 and can be understood as known. The refractive index n2 of air can also be understood as known. Moreover, according to the complementary relationship of 90° angles, it can be determined that the angle a between the incident laser beam and the normal direction is equal to the wedge angle d of each wedge prism 34 in the wedge prism module 30. Then, according to the formula n1*sin(a) = n2*sin(b), the angle b between the outgoing laser beam and the normal direction can be calculated. Further, according to the formula c = b - a, the deflection angle c of the outgoing laser beam relative to the incident laser beam can be calculated. Moreover, since the second surfaces 32 in the wedge prism module 30 are parallel to each other, the wedge angles of the wedge prisms 34 in the wedge prism module 30 are equal, all being the wedge angle d. It can be understood that the refractive index of the medium is related to the material selection of the wedge prism 34, and the wedge angle of the wedge prism 34 can be determined according to actual needs. In this way, through the reasonable design of the material of the wedge prism 34 and the wedge angle of the wedge prism 34, the required deflection angle of the laser beam can be correspondingly determined, that is, the angle size of the scanning field of view for the lidar optical scanning system to scan the target detection area can be correspondingly determined. That is to say, according to the angle size of the scanning field of view for the lidar optical scanning system to scan the target detection area, the selection of the material of the wedge prism 34 and the wedge angle of the wedge prism 34 can also be deduced. In a specific embodiment, the refractive index n1 of the wedge prism module 30 can be 2.001, and the wedge angle d of each wedge prism 34 in the wedge prism module 30 can be 17.2°. Then, according to the formula n1*sin(a) = n2*sin(b), the angle b between the outgoing laser beam and the normal direction can be calculated as b = 37.2°. In this way, according to the formula c = b - a, the deflection angle c of the outgoing laser beam relative to the incident laser beam can be calculated as c = 37.2° - 17.2° = 20°. That is, the scanning field of view for the lidar optical scanning system to scan the target detection area is less than or equal to 20°. It can be understood that the realization of a 20° scanning field of view requires the reasonable selection of the material and wedge angle of the wedge prism module 30, and the 20° scanning field of view is the maximum value that can be achieved.

[0068] In addition, when the lidar optical scanning system is mounted on a moving device such as a drone, the lidar optical scanning system can move along a direction. And during the process of the wedge prism module 30 rotating 360° around the first rotation axis 33, a 20° scanning field of view at the target detection area and a circular scanning trajectory can be obtained, thereby further obtaining a dynamic scanning laser point cloud image. Figure 7It is a schematic diagram of the scanning principle of dynamic scanning provided by an embodiment of the present invention. As Figures 1-7 shown, in the moving direction of the lidar optical scanning system, the scanning time required for a single circular scanning trajectory, the number of scanning points in a single circular scanning trajectory, and the detection resolution of the lidar optical scanning system can be determined according to the repetition frequency f (unit: KHz) of the lidar optical scanning system, the rotation speed V1 (unit: Hz) of the wedge prism module 30 rotating around the first rotation axis 33, the height direction distance H (unit: m) between the target detection area and the lidar optical scanning system, and the speed V2 (unit: m / s) of the lidar optical scanning system in the moving direction. Exemplarily, the repetition frequency f of the lidar optical scanning system can be 20 KHz, the rotation speed V1 of the wedge prism module 30 rotating around the first rotation axis 33 can be 20 Hz, the height direction distance H between the target detection area and the lidar optical scanning system can be 50 m, and the speed V2 of the lidar optical scanning system in the moving direction can be 6 m / s. Then, the scanning time T1 required for a single circular scanning trajectory can be determined according to the formula, that is, T1 = 1 / f = 1 / (20 * 10 3 )= 50 ms. The number of scanning points in a single circular scanning trajectory can be determined according to the formula, that is, A = f / V1 = (20 * 10 3 ) / 20 = 1000. The angular resolution α can be determined according to the formula, that is, α1 = 360° / A = 360° / 1000 = 0.36°. The resolution in the vertical direction can be determined according to the formula, that is, α2 = tan(α1) * H = tan(0.36°) * 50 = 0.31 m. The resolution in the horizontal direction / the moving direction of the lidar optical scanning system can be determined according to the formula, that is, α3 = V2 * T1 = 6 * 50 * 10 -3 = 0.3 m. That is to say, according to the above calculation process, it is determined that when the height direction distance H between the target detection area and the lidar optical scanning system is 50 m and the speed V2 of the lidar optical scanning system in the moving direction is 6 m / s, a detection resolution of 0.3 m at the target detection area can be achieved. And when the lidar optical scanning system is mounted on a moving device such as a drone, the detection resolution at the target detection area can be adjusted by adjusting the magnitude of the speed V2 of the lidar optical scanning system in the moving direction. Exemplarily, in a specific embodiment, the smaller the speed V2 of the lidar optical scanning system in the moving direction, the larger the detection resolution α3 at the target detection area. In this way, high-precision scanning detection of the lidar optical scanning system is achieved.

[0069] Optionally, continue to refer to Figure 1, the laser emission module 10 includes a laser unit 11 and a beam expanding and collimating unit 12; the laser unit 11 emits an initial laser beam; the beam expanding and collimating unit 12 is located on the propagation path of the initial laser beam, and the beam expanding and collimating unit 12 expands and collimates the initial laser beam to obtain a parallel laser beam.

[0070] Specifically, the laser emission module 10 includes a laser unit 11 and a beam expanding and collimating unit 12. Among them, the laser unit 11 emits an initial laser beam. Exemplarily, the laser unit 11 can select a 532nm solid-state laser, which has characteristics such as high output energy (15μj), high repetition frequency (20kHz), short laser wavelength, strong directivity, high frequency, little influence from external interference, and strong penetrability. Compared with fiber lasers, the solid-state laser in this embodiment has a smaller volume, higher luminous efficiency, and less heat radiation, effectively controlling the heat generation of the laser emission module 10, improving the reliability of the laser emission module 10, enhancing the structural compactness of the laser emission module 10, strengthening the recognition ability of low-reflectivity targets, and having stronger penetrability in water body detection. In addition, exemparily, the initial laser beam emitted by the laser unit 11 can be a continuous laser or a pulsed laser. Exemplarily, the initial laser beam emitted by the laser unit 11 can be a laser signal in the infrared or visible light band.

[0071] In addition, since the spot diameter and divergence angle of the initial laser beam emitted by the laser unit 11 may not meet the requirements of the subsequent scanning and detection process, a beam expanding and collimating unit 12 can be set on the propagation path of the initial laser beam. The beam expanding and collimating unit 12 can expand and collimate the initial laser beam to obtain a parallel laser beam and incident it on the wedge prism module 30. The parallel laser beam processed by the beam expanding and collimating unit 12 has a better spot diameter and divergence angle, and can also improve the long-distance detection ability of the lidar optical scanning system. Exemplarily, the requirement for the divergence angle in the subsequent scanning and detection process can be 1mrad. At this time, the influence of turbulence caused by water vapor on the spot of the parallel laser beam can be minimized, making the light energy per unit area more concentrated. Exemplarily, the beam expanding and collimating unit 12 can select the basic optical model of a Galilean inverse telescope.

[0072] Further, continue to refer to Figure 1 , the beam expanding and collimating unit 12 includes a first lens 121 and a second lens 122 that are separately arranged; the first lens 121 and the second lens 122 are sequentially located on the propagation path of the initial laser beam; the first lens 121 expands the initial laser beam, and the second lens 122 collimates the expanded initial laser beam to obtain a parallel laser beam. In a specific embodiment, optionally, the first lens 121 has a positive optical power, and the second lens 122 has a negative optical power.

[0073] Specifically, applying the principle of the basic optical model of the Galilean inverse telescope, the beam expanding and collimating unit 12 includes a first lens 121 and a second lens 122 that are separately arranged. The first lens 121 and the second lens 122 are successively located on the propagation path of the initial laser beam, and the first lens 121 and the second lens 122 are confocal. In this way, the total length of the beam expanding and collimating unit 12 can be effectively reduced. Exemplarily, the total length of the beam expanding and collimating unit 12 can be 85 mm. At this time, the processing cost performance of the first lens 121 and the second lens 122 and the structural compactness of the beam expanding and collimating unit 12 can be effectively satisfied. In addition, the beam expansion ratio / magnification of the beam expanding and collimating unit 12 is related to the optical power of the first lens 121 and the optical power of the second lens 122. Exemplarily, the spot diameter of the initial laser beam emitted by the laser unit 11 can be 1 mm, and the divergence angle can be 6 mrad. The beam expansion ratio / magnification of the beam expanding and collimating unit 12 can be 6 times. Then, the spot diameter of the parallel laser beam processed by the beam expanding and collimating unit 12 can be 6 mm, and the divergence angle can be 1 mrad.

[0074] In a specific embodiment, the first lens 121 has a positive optical power. The radius of curvature of the light incident surface of the first lens 121 can be -5 mm to -8 mm, the radius of curvature of the light exit surface of the first lens 121 can be 60 mm to 72 mm, the thickness of the first lens 121 can be 2 mm to 2.5 mm, the material of the first lens 121 can be JGS1, the diameter of the first lens 121 can be 7 mm. Anti-reflection films in the wavelength range of 532 nm ± 2 nm can be provided on both the light incident surface and the light exit surface of the first lens 121. The first lens 121 can be a spherical lens, and the focal length range of the first lens 121 can be -8.5 mm to -15 mm. The second lens 122 has a negative optical power. The radius of curvature of the light incident surface of the second lens 122 can be infinite, the radius of curvature of the light exit surface of the second lens 122 can be 35 mm to 40 mm, the thickness of the second lens 122 can be 4.3 mm to 4.6 mm, the material of the second lens 122 can be JGS1, the diameter of the second lens 122 can be 12 mm. Anti-reflection films in the wavelength range of 1535 nm ± 2 nm can be provided on both the light incident surface and the light exit surface of the second lens 122. The second lens 122 can be a spherical lens, and the focal length range of the second lens 122 can be 50 mm to 89 mm. In addition, the distance range between the light exit surface of the laser unit 11 and the light incident surface of the first lens 121 can be 9 mm to 15 mm, and the distance range between the light exit surface of the first lens 121 and the light incident surface of the second lens 122 can be 41 mm to 70 mm. Also, the constraint conditions of the beam expanding and collimating unit 12 are: the wavefront is less than 0.25λ, the RMS is less than 0.075λ, the divergence angle is less than 1 mrad, the total system length is less than 85 mm, and the exit pupil diameter is 6.4 mm.

[0075] According to the parameter settings of the components in the above laser emission module 10, the following simulation diagrams are exemplarily given in this embodiment. Figure 8 It is a schematic diagram of the wavefront and root mean square radius of a laser beam provided by an embodiment of the present invention. Figure 9 It is a schematic diagram of the full field point spread function of a laser beam provided by an embodiment of the present invention. Figure 10 It is a schematic diagram of the optical modulation transfer function of a laser beam provided by an embodiment of the present invention. Figure 11 It is a schematic diagram of the irradiation intensity of the point spread function of a laser beam provided by an embodiment of the present invention. As Figures 8-11 shown, it can be known that the RMS root mean square radius of the parallel laser beam emitted by the laser emission module 10 is 0.384 mrad, and the full field divergence angle is 0.768 mrad.

[0076] In addition, the laser emission module 10 further includes a mirror unit 13. The mirror unit 13 can be located on the propagation path of the parallel laser beam emitted by the beam expander collimator unit 12. The mirror unit 13 can adjust the propagation direction of the parallel laser beam so that the parallel laser beam is incident on the first surface 31 of the wedge prism module 30. Exemplarily, the mirror unit 13 can make the parallel laser beam incident in a direction perpendicular to the first surface 31 of the wedge prism module 30. Exemplarily, the wedge prism module 30 can be understood as a combination of multiple wedge prisms 34. In this embodiment, only an example in which the wedge prism module 30 includes two wedge prisms 34 is drawn here. In fact, the wedge prism module 30 can also include more than two wedge prisms 34. That is, exemplarily, the mirror unit 13 can make the parallel laser beam perpendicularly incident on the first surface 31 corresponding to one of the wedge prisms 34 of the wedge prism module 30. Further, after the wedge prism module 30 is driven by the motor drive module to rotate 180° / half a turn around the first rotation axis 33, the mirror unit 13 can also make the parallel laser beam perpendicularly incident on the first surface 31 corresponding to the other wedge prism 34 of the wedge prism module 30. In addition, in order to make the structure of the laser emission module 10 compact, multiple mirror units 13 can also be used to change the propagation direction of the parallel laser beam.

[0077] Optionally, continuing to refer to Figure 1 , the laser reception module 20 includes a receiving lens unit 21 and a photoelectric detection unit 22; the receiving lens unit 21 and the photoelectric detection unit 22 are sequentially located on the propagation path of the echo laser beam; the receiving lens unit 21 performs a converging process on the echo laser beam; the photoelectric detection unit 22 receives the echo laser beam after the converging process. Further, the photoelectric detection unit 22 is located on the focal plane of the receiving lens unit 21.

[0078] Specifically, the laser receiving module 20 includes a receiving lens unit 21 and a photoelectric detection unit 22. The receiving lens unit 21 and the photoelectric detection unit 22 are sequentially located on the propagation path of the echo laser beam. The receiving lens unit 21 performs convergence processing on the echo laser beam. It can be understood that the receiving lens unit 21 should match the wedge prism module 30, that is, the receiving lens unit 21 should be designed to match the size of the wedge prism module 30 to receive as many echo laser beams as possible. And, when the optical axis of the receiving lens unit 21 is colinear with the first rotation axis 33 around which the wedge prism module 30 is located, the receiving lens unit 21 and the wedge prism module 30 constitute a coaxial optical system, which can further improve the detection accuracy. Otherwise, it will constitute a paraxial optical system, which has a certain improvement ability on the adverse effects of close-range strong reflective targets. In a specific embodiment, the receiving lens unit 21 can be an aspheric lens, the curvature radius of the beam incident surface of the receiving lens unit 21 can be 81mm-82.5mm, the curvature radius of the beam exit surface of the receiving lens unit 21 can be infinite, the thickness of the receiving lens unit 21 can be 45.4mm-47.5mm, the material of the receiving lens unit 21 can be H-ZF2, the beam incident surface and the beam exit surface of the receiving lens unit 21 can be provided with an anti-reflection film with a wavelength range of 532nm±2nm, the RMS radius of the receiving lens unit 21 can be 60μm, the focal length of the receiving lens unit 21 can be 120mm, and the light aperture of the receiving lens unit 21 can be 135mm. In this way, the receiving lens unit 21 can quickly converge the echo laser beam, effectively compress the distance between the receiving lens unit 21 and the photoelectric detection unit 22, reduce the number of lenses in the receiving lens unit 21, and improve the light output power and structural compactness of the receiving lens unit 21. In addition, the distance between the beam exit surface of the receiving lens unit 21 and the photoelectric detection unit 22 can range from 90 mm to 94 mm. And the constraints of the laser receiving module 20 are: focal length less than 125 mm, outer diameter D = 150 mm, total system length less than 150 mm, and RMS radius less than 60 μm.

[0079] The photoelectric detection unit 22 can be located on the focal plane of the receiving lens unit 21, and the photoelectric detection unit 22 can receive the echo laser beam after convergence processing, that is, the receiving lens unit 21 can converge the received echo laser beam onto the photoelectric detection unit 22 to improve the detection capability of the wedge prism module 30 to the target detection area. Exemplarily, the photosensitive surface diameter of the photoelectric detection unit 22 can be 500 μm.

[0080] According to the parameter settings of the components in the above-mentioned laser receiving module 20, this embodiment exemplarily provides the following simulation examples. Figure 12It is a schematic diagram of the optical modulation transfer function of another laser beam provided by an embodiment of the present utility model. Figure 13 It is a schematic diagram of the point spread function of a laser beam in a sub-field provided by an embodiment of the present utility model. Figure 14 It is a schematic diagram of the point spread function of another laser beam in the full field provided by an embodiment of the present utility model. Figure 15 It is a schematic diagram of the irradiation intensity of the point spread function of another laser beam provided by an embodiment of the present utility model, as Figures 12-15 shown.

[0081] Based on the same concept, an embodiment of the present utility model also provides a lidar, which includes a lidar optical scanning system provided in any one of the embodiments of the present utility model. Therefore, the lidar provided by the embodiment of the present utility model has the corresponding beneficial effects of the lidar optical scanning system provided by the embodiment of the present utility model, which will not be elaborated here. Of course, in addition to including the above-mentioned lidar optical scanning system, the lidar also includes other components, such as an information processing system, etc., which will not be described in detail here.

[0082] Note that the above is only a preferred embodiment of the present utility model and the applied technical principle. Those skilled in the art will understand that the present utility model is not limited to the specific embodiments described here, and various obvious changes, re-adjustments, combinations with each other and substitutions can be made by those skilled in the art without departing from the protection scope of the present utility model. Therefore, although the present utility model has been described in more detail through the above embodiments, the present utility model is not limited to the above embodiments. Without departing from the concept of the present utility model, more other equivalent embodiments can be included, and the scope of the present utility model is determined by the scope of the appended claims.

Claims

1. A laser radar optical scanning system, characterized in that: It includes a laser transmitting module, a laser receiving module, a wedge prism module and a motor driving module; The wedge-shaped prism module includes a first surface and at least two second surfaces, each of the second surfaces is parallel, and an extension direction of the first surface intersects with an extension direction of the second surface; The motor driving module drives the wedge-shaped prism module to rotate around a first rotation axis; wherein the first rotation axis is perpendicular to the first surface; The laser emission module emits a parallel laser beam to the first surface of the wedge-shaped prism module, and the parallel laser beam is refracted by the wedge-shaped prism module to the target detection area, so as to scan the target detection area when the wedge-shaped prism module rotates around the first rotation axis; The laser receiving module receives the echo laser beam reflected by the target detection area.

2. The laser radar optical scanning system according to claim 1, characterized in that: The parallel laser beam emitted by the laser emission module is vertically incident on the first surface of the wedge-shaped prism module, and is refracted by the wedge-shaped prism module and emitted from the second surface of the wedge-shaped prism module to the target detection area; The parallel laser beam is reflected by the target detection area and incident on the second surface of the wedge-shaped prism module, and is refracted by the wedge-shaped prism module and emitted from the first surface of the wedge-shaped prism module to the laser receiving module.

3. The laser radar optical scanning system according to claim 2, characterized in that: The wedge prism module includes at least two wedge prisms, and the number of the wedge prisms is the same as the number of the second surfaces; Each of the wedge-shaped prisms in the wedge-shaped prism module is integrally formed.

4. The laser radar optical scanning system according to any one of claims 1, 2 and 3, characterized in that: The laser emission module includes a laser unit and a beam expansion and collimation unit; The laser unit emits an initial laser beam; The beam expansion and collimation unit is located on the propagation path of the initial laser beam, and the beam expansion and collimation unit performs beam expansion and collimation processing on the initial laser beam to obtain the parallel laser beam.

5. The laser radar optical scanning system according to claim 4, characterized in that: The beam expansion and collimation unit comprises a first lens and a second lens which are separately arranged; The first lens and the second lens are sequentially located on a propagation path of the initial laser beam; The first lens performs beam expansion processing on the initial laser beam, and the second lens performs collimation processing on the expanded initial laser beam to obtain the parallel laser beam.

6. The laser radar optical scanning system according to claim 5, characterized in that: The first lens has positive refractive power, and the second lens has negative refractive power.

7. The laser radar optical scanning system according to claim 4, characterized in that: The laser emission module also includes a reflector unit; The reflector unit is located on a propagation path of the parallel laser beam, and the reflector unit adjusts a propagation direction of the parallel laser beam so that the parallel laser beam is incident on the first surface of the wedge prism module.

8. The laser radar optical scanning system according to any one of claims 1, 2, 3, 5, 6, and 7, characterized in that: The laser receiving module includes a receiving lens unit and a photoelectric detection unit; The receiving lens unit and the photoelectric detection unit are sequentially located on the propagation path of the echo laser beam; The receiving lens unit performs convergence processing on the echo laser beam; The photoelectric detection unit receives the echo laser beam after the convergence process.

9. The laser radar optical scanning system according to claim 8, characterized in that: The photoelectric detection unit is located on the focal plane of the receiving lens unit.

10. A laser radar, characterized in that: It comprises the laser radar optical scanning system as described in any one of claims 1 to 9.

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