LiDAR

Abstract

The present application provides a laser radar including: a laser array arranged in a linear array or a planar array, arranged in the focal plane of a first optical component, and a first optical component arranged in the transmitting optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the transmitting end; and / or, a light detector array arranged in a linear array or a planar array, arranged in the focal plane of a second optical component, and the second optical component arranged in the receiving optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the receiving end. In the embodiment of the present application, the power density within the point cloud field of view angle area is increased by setting the first optical component at the light transmitting end, and / or the background light noise power within the point cloud field of view angle area is reduced by setting the second optical component at the receiving end, thereby improving the ranging capability of the radar.

Description

Technical Field

[0001] The present application relates to the field of optical ranging technology, and in particular to laser radar. Background Art

[0002] LiDAR is a detection device that calculates the distance of an object by emitting laser light and detecting the echo signal reflected by the laser light after it reaches the surface of the object. Therefore, LiDAR needs to include two parts: the light transmitting (Transmitter X) element and the light detecting (Receiver X) element, which can be called the light transmitting module and the light detecting module.

[0003] The laser radar includes an optical system, which is distributed in the light transmitting module and the light detecting module. For example, the light transmitting module includes a main lens group for collimating the transmitting signal of the laser, and the light detecting module includes a receiving lens for converging the echo signal to the detector. For the light transmitting module (or light detecting module), its field of view (FOV) is positively correlated with the longitudinal dimension of the light emitting surface of the light transmitting module (or the photosensitive surface of the light detecting module), and negatively correlated with the equivalent focal length of the transmitting and / or receiving lens (group). Among them, the longitudinal dimension of the light emitting surface (or photosensitive surface) is positively correlated with the height of the laser radar.

[0004] The height dimension of LiDAR products is an important parameter that customers pay attention to. In order to keep the LiDAR at a suitable height while covering a larger field of view (such as 105°), the focal length of the transmitting module and / or the detection module has to be reduced, such as replacing optical devices with shorter focal lengths, which will not only reduce the duty cycle of the light-emitting surface but also limit the vertical resolution. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the present application provides a light detection device and a detection method to solve the problems caused by the mutual constraints between the focal length and height of the above-mentioned laser radar, and can improve the ranging capability of the radar without increasing the height of the radar.

[0006] To achieve the above objectives and other related objectives, the present application provides a laser radar in a first aspect, including:

[0007] The optical transmission module is arranged at the focal plane of the first optical component, and includes: a laser array arranged in a linear array or a planar array, and is suitable for transmitting a transmission signal, and the transmission signal is transmitted along a transmission optical path;

[0008] A first optical component is provided in the emission light path, and has an equivalent focal length greater than a first preset value, so as to increase the power density within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the first preset value is the focal length of the main lens group unit;

[0009] The optical detection module comprises: an optical detector array arranged in a linear array or a planar array, and adapted to detect, from a receiving optical path, an echo signal reflected by the transmitting signal after encountering an obstacle.

[0010] In one embodiment of the present invention, the first optical component comprises: a main lens assembly unit, adapted to collimate the transmission signal;

[0011] It also includes: a first diverging unit, which is arranged between the laser array and the main lens group unit and is suitable for diverging the emission signal after being collimated by the main lens group unit, so that the first optical component has an equivalent focal length longer than a first preset value.

[0012] In one embodiment of the present invention, the equivalent focal length of the first optical component is M times the focal length of the main lens group unit, M>1, so that the area of ​​the light-emitting surface of each laser is increased by M2 times.

[0013] In one embodiment of the present invention, the first diverging unit comprises: a concave lens array, wherein each concave lens corresponds to an emission channel.

[0014] The embodiment of the present invention further provides another laser radar, including:

[0015] The optical transmission module comprises: a laser array arranged in a linear array or a planar array, suitable for emitting a transmission signal, wherein the transmission signal is transmitted along a transmission optical path;

[0016] The light detection module is arranged at the focal plane of the second optical component, and includes: a light detector array arranged in a linear array or a planar array, and is suitable for detecting the echo signal reflected by the transmission signal after encountering an obstacle from the receiving light path;

[0017] And the second optical component is arranged in the receiving light path, forming an equivalent focal length greater than a second preset value, so as to reduce the background light noise power within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the second preset value is the focal length of the main lens group unit.

[0018] In one embodiment of the present invention, the second optical component comprises: a receiving lens group unit, adapted to converge the received signal;

[0019] The second optical component further includes: a second diverging unit,

[0020] It is configured between the photodetector array and the receiving lens group unit so that the second optical component has an equivalent focal length longer than a second preset value and is suitable for diverging the receiving signal converged by the receiving lens group unit.

[0021] In one embodiment of the present invention, the equivalent focal length of the second optical component is P times the focal length of the main lens group unit, P>1, so that the acceptance angle area is reduced by P2 times.

[0022] In one embodiment of the present invention, the second diverging unit comprises: a concave lens array, wherein each concave lens corresponds to a detector arrangement.

[0023] In one embodiment of the present invention, the laser radar includes: a first optical component, arranged in the emission light path, forming an equivalent focal length greater than a first preset value, so as to increase the power density within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the first preset value is the focal length of the main lens group unit in the first optical component; the equivalent focal lengths of the first optical component and the second optical component are in a certain proportional relationship.

[0024] In summary, the present application provides a laser radar including: a laser array arranged in a linear array or a planar array, arranged in the focal plane of a first optical component, and a first optical component, arranged in the transmitting optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the transmitting end; and / or, a light detector array arranged in a linear array or a planar array, arranged in the focal plane of a second optical component, and the second optical component, arranged in the receiving optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the receiving end. In the embodiment of the present application, the power density within the point cloud field of view angle area is increased by setting the first optical component at the light transmitting end, and / or, the background light noise power within the point cloud field of view angle area is reduced by setting the second optical component at the receiving end, thereby improving the ranging capability of the radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1A A schematic diagram showing the relationship between the field of view and focal length of a light emitting module of a light detection system in an example.

[0026] Figure 1B A schematic diagram showing the relationship between the field of view and focal length of a light detection module of a light detection system in an example.

[0027] Figure 1C A schematic diagram showing the channel correspondence between the transmitting end and the receiving end of a horizontal scanning mechanical radar in an example.

[0028] Figure 2A A schematic diagram showing the light-emitting surface of a laser in an example.

[0029] Figure 2B exhibit Figure 2A A simplified representation of .

[0030] Figure 3 A schematic diagram showing a principle of illustrating the vertical resolution of a light emitting module in an example.

[0031] Figure 4 A schematic diagram showing the light transmitting and receiving circuits of a laser radar in one embodiment of the present application.

[0032] Figure 5A A schematic diagram of the structure of an optical transmission module in an embodiment of the present application is shown.

[0033] Figure 5B A schematic diagram showing the structure of an optical transmission module in another embodiment of the present application is shown.

[0034] Figure 6 Shown is a schematic diagram of the front view structure of the enlarged light-emitting surface formed at different focal lengths in the embodiment of the present application.

[0035] Figure 7 A schematic diagram showing the structure of the light detection module of the laser radar in an embodiment of the present application.

[0036] Figure 8 A schematic diagram showing the principle of determining the value of M according to the specific structural parameters of the optical transmission module in an embodiment of the present application.

[0037] Fig. 9 A schematic diagram of the front view structure of the concave lens array and the layout of the magnified light-emitting surface formed at different focal lengths in the embodiment of the present application is shown.

[0038] Fig. 10A A schematic diagram showing the structure of a laser radar with a paraxial optical path structure in one embodiment of the present application.

[0039] Fig. 10B A schematic diagram showing the front view of the laser array and the light detector array of a laser radar with a paraxial optical path structure in one embodiment of the present application.

[0040] Fig. 10C exhibit Fig. 10B Schematic diagram of the curve of the simulation results of the ranging capability of the laser radar.

[0041] Fig.11A A schematic diagram showing the structure of a laser radar with a coaxial optical path structure in one embodiment of the present application.

[0042] Fig. 11B A schematic diagram showing the structure of a laser radar with a coaxial optical path structure in another embodiment of the present application.

[0043] Fig. 12A A schematic diagram showing the optical path of the emitting end without a sleeve in an embodiment of the present application.

[0044] Fig. 12B A schematic diagram of the optical path of the emitting end of the sleeve in the embodiment of the present application is shown.

[0045] Fig. 12C A schematic diagram of the optical path of the receiving end of the sleeve in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0046] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and application systems without departing from the spirit of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0047] The following is a detailed description of the embodiments of the present application with reference to the accompanying drawings so that those skilled in the art can easily implement the present application. The present application can be embodied in a variety of different forms and is not limited to the embodiments described herein.

[0048] In order to clearly describe the present application, components irrelevant to the description are omitted, and the same reference symbols are given to the same or similar components throughout the specification.

[0049] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0050] When a device is said to be "on" another device, it may be directly on the other device, but there may also be other devices between it. In contrast, when a device is said to be "directly" on another device, there are no other devices between it.

[0051] Although the terms first, second, etc. are used to describe various elements in this article in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface are described. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate that there are the described features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0052] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present application. The singular form used herein also includes the plural form unless the sentence clearly indicates the contrary meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0053] Terms indicating relative space, such as "below" and "above", may be used to more easily describe the relationship of one device illustrated in the drawings relative to another device. Such terms refer not only to the meaning indicated in the drawings, but also to other meanings or operations of the device in use. For example, if the device in the drawings is turned over, a device that was described as being "below" other devices is described as being "above" the other devices. Therefore, the exemplary term "below" includes both above and below. The device can be rotated 90° or other angles, and the terms indicating relative space are interpreted accordingly.

[0054] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which this application belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with the relevant technical literature and the contents of the current disclosure, and unless defined, shall not be overly interpreted as ideal or very formal meanings.

[0055] LiDAR is a device that measures distance based on an optical detection system. Currently, there are requirements for high precision and large field of view in the application scenarios of LiDAR (such as autonomous driving). At the same time, in actual scenarios, the size of LiDAR needs to be reduced as much as possible. In particular, the height of LiDAR is one of the parameters that customers pay the most attention to. However, there is a contradiction between large field of view and low height, which affects the performance of LiDAR. The following example illustrates the principle.

[0056] See also Figure 1A and Figure 1B , which is a schematic diagram showing the relationship between field of view and focal length in an optical detection system in an example. Figure 1A Schematic diagram showing the relationship between the field of view and focal length of the light transmitting module in the light detection system. Figure 1B A schematic diagram showing the relationship between the field of view and focal length of the light detection module of the light detection system.

[0057] according to Figure 1A or Figure 1B The triangle corresponding to the field of view FOV shown in the figure can be calculated:

[0058]

[0059] Wherein, a is the height (or longitudinal dimension) of the light-emitting surface of a single laser 101A or the photosensitive surface of a single photodetector 101B, and f is the focal length of lenses 102A and 102B (both are schematically indicated as f in the figure, but this does not mean that the focal lengths of the two optical paths are limited to be the same, but is only to avoid confusion caused by too many numbers). For a laser radar, the field of view of a single laser / single detector satisfies formula (1). At the same time, in an ideal situation (when multiple lasers / detectors can be connected seamlessly in the longitudinal direction), whether it is a single light-emitting surface 101A / single photosensitive surface 101B or the height of all multiple lasers / detectors in the longitudinal direction, formula (1) is satisfied, and the size of the field of view is positively correlated with the height of the laser radar.

[0060] Therefore, it can be inferred from formula (1) that the size of the light-emitting surface of the laser radar's light-emitting module and the photosensitive surface of the detection module are positively correlated with the size of the laser radar. In particular, the height of the laser radar is a more important parameter than the width and depth. In various application scenarios, a suitable height is usually required to fit the limited installation space.

[0061] Moreover, from formula (1), it can be seen that the size of the field of view FOV is positively correlated with the size of the light-emitting surface and the light-sensitive surface, and negatively correlated with the equivalent focal length f of the optical components (such as the main lens group) in the light-emitting module and the light-detecting module. It can be seen that if a larger FOV is to be maintained, either a is increased or f is reduced. However, increasing a may increase the height of the laser radar, so f is generally reduced to achieve the purpose, but this will cause problems that affect the performance of the laser radar.

[0062] In addition, for radar systems, there is a certain correspondence between transmission and reception. The transmission and reception paths may be different, and the focal plane layouts of transmission and reception may also be different, but in the end, we hope that the transmitted light will fall on a certain area on the target, and the reflected light from this area will just return to the detector, that is, the transmission and reception can match, and the transmission and reception channels can correspond. To avoid confusion, some terms are defined below.

[0063] Scan line number: that is, the number of channels for laser transmission and reception, or the minimum number of addressable channels. Generally, lasers and detectors are configured in a 1:1 ratio, and the number of scan lines is equal to the number of lasers or detectors, and also equal to the number of transmitting channels or receiving channels. At the same time, there are also situations where multiple detectors share one laser, or vice versa, or there may even be staggered situations. At this time, it is necessary to specifically distinguish the minimum number of addressable channels.

[0064] Divergence angular area: refers to the angular area of ​​the laser light-emitting area of ​​a certain channel projected into the far field through the optical system.

[0065] Receiving angular area: refers to the angular area of ​​the detector photosensitive surface of a certain channel projected into the far field through the optical system.

[0066] Point cloud field of view angle area: refers to the overlapping part of the divergence angle and the receiving angle. This is the actual range covered by the point cloud and is the superposition of all target reflection echo signals within this range. In different optical path designs, the point cloud field of view angle area shows different relative relationships with the divergence angle area and the receiving angle area. For example, the point cloud field of view angle area can be equal to the divergence angle area and smaller than the receiving angle area, or equal to the receiving angle area and smaller than the divergence angle area, or equal to the overlapping part of the two. In the most ideal case, the point cloud field of view angle area is consistent with both the divergence angle and the receiving angle area.

[0067] The field of view FOV often includes the horizontal field of view HFOV and the vertical field of view VFOV, which refers to the total angular range of detection of all transmitting and receiving channels.

[0068] refer to Figure 1C , on the left is the transmitter (TX), which is equipped with multiple lasers (referring to the smallest addressable light-emitting unit).

[0069] On the right is the receiving end (RX, receiver), which is equipped with multiple detectors (also refers to the minimum addressable unit).

[0070] In the middle is the point cloud field of view angle. The horizontal position of each point represents the horizontal angle. The horizontal angle θ shifts as the radar rotor rotates. The vertical position represents the pitch angle γ=β.

[0071] See you again Figure 2A and Figure 2B , a schematic diagram of a light emitting surface of a laser in an example is shown. The laser is exemplarily a vertical cavity surface emitting laser 200 (Vertical Cavity Surface Emitting Laser, VCSEL). Figure 2A This is a top view of a more practical VCSEL. Figure 2B Based on Figure 2A An abstract and simplified schematic diagram. The luminous duty cycle refers to the ratio of the area covered by the luminous surface to the total area, which can be the ratio of the sum of the areas of each luminous point 201 in the diagram to the dotted box 202 or the entire VCSEL top surface area. In short, the luminous duty cycle is limited by OA / PITCH. Among them, OA is the area of ​​one of the luminous points 201, and PITCH is the pitch of adjacent luminous points 201 in the longitudinal direction (that is, the distance between the centers of adjacent luminous points, as indicated by the double-headed arrows in the figure). It can be seen that the larger the OA or the smaller the pitch, the higher the duty cycle. It should be noted that this is just an example. In this application, there is no limitation on the type of laser. For example, the laser can be an EEL (Edge Emitting Laser), a VCSEL, or a PCSEL (Photonic Crystal Surface Emitting Semiconductor Lasers). Similarly, in the present application, there is no limitation on the type of detector. For example, the photodetector may be an APD, a single photon avalanche diode array SPAD(s), or a silicon photomultiplier SiPM.

[0072] Further, such as Figure 3 As shown, when the optical transmission module adopts, for example, a laser array as the laser array, the vertical angular resolution of the laser radar is determined by the ratio d / f between the center distance d of adjacent lasers 301 and 302 arranged longitudinally (or in columns) and the equivalent focal length f of the main lens group (here only a convex lens 303 is shown as an equivalent case in the embodiment, and the actual main lens group may include multiple lens groups, which is not limited here), that is, it is positively correlated with d and negatively correlated with f.

[0073] Based on the above, it can be seen that there is still room for improvement in the optical path system of existing LiDAR. On the one hand, in order to cover a larger field of view (such as 105°) and to maintain the height without increasing, the focal length has to be reduced as much as possible. On the other hand, the duty cycle of the laser's light-emitting surface is limited by the light-emitting point area / light-emitting point pitch, resulting in a low duty cycle. On the other hand, the vertical resolution is limited by d / f.

[0074] In view of the above, a laser radar is provided in an embodiment of the present application, which achieves a longer equivalent focal length with a relatively short physical size through optical improvements, thereby increasing the power density within the point cloud field of view angular area, and / or reducing the background light noise power within the point cloud field of view angular area, thereby improving the radar's ranging capability.

[0075] Figure 4 A schematic diagram of a laser radar light receiving and transmitting path is shown. The laser radar may specifically include:

[0076] The optical emission module, i.e., a laser array arranged in a linear array or a planar array, is arranged corresponding to the first optical component, for example, it can be arranged in the focal plane of the first optical component, and is suitable for emitting an emission signal, and the emission signal is transmitted along the emission optical path. The first optical component can be formed with an equivalent focal length greater than the first preset value.

[0077] The light detection module, that is, the light detector array arranged in a linear array or a planar array, is arranged corresponding to the second optical component, for example, it can be arranged in the focal plane of the second optical component, and is suitable for detecting the echo signal reflected after the transmission signal reaches the object. The second optical component can be formed with an equivalent focal length greater than the second preset value. Thus, by setting the optical components of the laser radar transmitting end and / or receiving end, the focal length of the receiving / transmitting side can be elongated, and the power density within the point cloud field of view angle area can be increased while keeping the height of the radar unchanged, and / or the background light noise power within the point cloud field of view angle area can be reduced, thereby greatly improving the ranging capability of the radar.

[0078] The following is a more detailed introduction from each side of the transmitting TX end and the receiving RX end.

[0079] like Figure 5A As shown, a schematic diagram of the structure of an optical transmission module in an embodiment of the present application is shown.

[0080] The optical transmission module includes: a laser array 501 and a first optical component.

[0081] The laser array 501 includes a plurality of lasers 511. The plurality of lasers 511 may be arranged in a linear array or a planar array. Each laser 511 is configured to output an emission signal, that is, to emit a laser. Exemplarily, the laser 511 may be implemented as a vertical cavity surface emitting laser (VSCEL) or an edge emitting laser (EEL).

[0082] The first optical component is disposed on the emission light path and is configured with an equivalent focal length greater than a first preset value. Figure 5A As shown in the example, the first optical component includes: a main lens group unit, which can be a main lens group originally used for collimating the transmission signal in the optical transmission module, Figure 5A In the example, an equivalent convex lens 502 is shown; and a first diverging unit is used to diverge the transmitted signal. Figure 5A The first diverging unit is exemplarily presented as a concave lens array 503. Each concave lens 531 in the concave lens array 503 is set corresponding to a laser 511 (a single addressable and controllable unit to be turned on or off) to lengthen the focal length of the emission light path (relative to the focal length formed by the emission light path of the main lens group alone), thereby realizing the improvement of the light-emitting surface of the laser 511 corresponding to the single pixel (relative to the size of the laser in the solution of setting the laser at the focal plane A of the main lens group unit, but in fact, in the solution with a longer focal length of the present application, the laser is only set at the focal plane B, not at A). At the point cloud level, it is to increase the power density within the point cloud field of view area, that is, the energy of the transmitting end used to form one of the points in the point cloud is greater. The pixel refers to a pixel point or point cloud in the point cloud map formed by the corresponding laser radar. For example, the light-emitting surface of each laser / the photosensitive surface of each light detector can correspond to a pixel point, and then the transceiver unit together constitutes a channel, which also corresponds to the above-mentioned line beam. The pitch between two adjacent concave lenses 531 in the concave lens array 503 may be the same as the center distance between adjacent lasers 511 .

[0083] It should be noted that the main lens group unit is exemplarily represented by a convex lens 502 in the figure. In fact, the convex lens 502 is only a representation of the main lens group unit. The main lens group unit can be a main lens group in the light transmitting module, which can include multiple lenses (for example Figure 4 The main lens assembly unit may have a first focal length, which is represented by the distance f" from the main plane C of the convex lens 502 to its one-fold focus (the corresponding focal plane is A).

[0084] In some embodiments, the concave lens array 503 is configured between the laser array 501 and the main lens group unit, and each concave lens 531 in the concave lens array 503 is arranged corresponding to a laser 511 .

[0085] The concave lens array 503 is suitable for diverging the transmission signal and then converging it through the main lens group unit, so as to form an equivalent focal length of the first optical component that is longer than the first preset value. For example, f" is the main lens group (i.e. Figure 5A The main lens unit is represented by a convex lens, but it is usually a main lens unit. Figure 5A In the figure, the focal length of the main lens group unit = main lens group = positive lens = convex lens = the leftmost lens), f is the equivalent focal length of the combination of the two lenses in the figure (i.e., convex lens 502 + concave lens array 503), and L is the physical entity size. Among them, the main plane after the combination of the positive and negative lens groups (i.e., convex lens 502 + concave lens array 503) will move forward. As shown in the figure, the left end point of f has moved forward to the left compared to the left end point of f", that is, the main plane D located at the left end point of f has moved forward to the left compared to the main plane C of the main lens group unit, and the entire focal plane will move backward, for example, from A to B. When calculating the focal length, the position of the main plane D can be determined based on the reverse extension line of the converging light, and its reverse extension line can be seen Figure 5A This is also an advantage of the optical path: L<f, which realizes a longer equivalent focal length f with a relatively short physical size L.

[0086] Based on the above, it can be understood that for the optical transmission module (i.e., the TX end), based on the optical path of the original main lens group of the laser radar (i.e., the main lens group unit / convex lens 502 in the figure), a concave lens array 503 is added in the embodiment of the present application to be combined with it to lengthen the focal length, that is, the focal length is lengthened from the focal length f" of the main lens group to the equivalent focal length f of the combination of two lenses (i.e., convex lens 502 + concave lens 530 in the concave lens array 503), let M be the focal length magnification, M = f / f". Optionally, the main plane spacing of the first diffusion unit from the main lens group unit can be less than f".

[0087] According to formula (1), when the FOV remains unchanged and the focal length f increases equivalently, a increases equivalently, which means that the luminous surface of each pixel increases equivalently. Therefore, the luminous energy of a single pixel (corresponding to a point in the point cloud image of the laser radar) can be increased, and the power density within the corresponding point cloud field of view area increases (i.e., more luminous points 201 are included in the same area), and the distance measurement capability also increases proportionally, for example, the distance measurement capability can be increased from 200m to 300m.

[0088] It should be noted that for a VSCEL laser, the viewing angle is relatively large, which may cause the emitted light F1 and F2 to deviate from the concave lens 530. This part of the light that has not passed through the concave lens 530 will be defocused, and the echo signal formed after being sent out through the main lens group unit at a relatively large divergence angle may be received by the light detectors of other channels, thereby forming crosstalk; or, it may deviate from the main lens group unit and form signal loss. For this reason, in some embodiments, the viewing angle of the laser array can be compressed.

[0089] like Figure 5B As shown, a schematic diagram of the structure of an optical transmission module in another embodiment of the present application is shown.

[0090] Figure 5B A laser array 501 and a first optical component of another embodiment are shown.

[0091] In this embodiment, the first optical component includes a main lens group unit and a micro lens group unit 503 .

[0092] It should be noted that Figure 5B The main lens group unit is still equivalently represented by a convex lens 502. The main lens group unit may have a first focal length, which is represented in the figure as the distance f" from its main plane C to its one-fold focus (corresponding to the focal plane A).

[0093] In this embodiment, the microlens group unit 504 includes not only the concave lens array 503 but also a microlens array 505. Figure 5B In the embodiment, the microlens array 551 is arranged between the laser array 501 and the concave lens array 503. Since the light-emitting surface of each laser 511 (such as VCSEL) has multiple light-emitting points, the microlenses 551 (specifically micro-convex lenses) in the microlens array 551 are arranged corresponding to one light-emitting point to converge the light emitted from the light-emitting point and transmit it to the corresponding concave lens 531. In other words, the divergence angle of the light emitted by each light-emitting point can be compressed through the microlens array 551, and the divergence angle of the emission signal output by the laser 511 and the laser array 501 can be suppressed, thereby avoiding Figure 5A The F1 and F2 light rays deviate from the concave lens array 503.

[0094] The principle of this embodiment is described in detail. Figure 5A Example, Figure 5B In the embodiment, the focal length extension is achieved by the equivalent focal length of the combination of three lenses (ie, the convex lens 502 + the concave lens 530 in the concave lens array 503 + the micro lens 551 in the micro lens array 505 ). Figure 5B f" is the main lens group ( Figure 5BThe main lens unit is represented by a convex lens instead, but it is usually a main lens unit. Figure 5B In the figure, the focal length of the main lens group unit = main lens group = positive lens = convex lens = leftmost lens), f is the equivalent focal length of the combination of the three lenses in the figure (i.e., convex lens 502 + concave lens 530 in concave lens array 503 + microlens 551 in microlens array 505), and L is the physical entity size. Among them, the principal plane after the combination of the positive and negative lens groups (i.e., convex lens 502 + concave lens 530 in concave lens array 503) will move forward, as shown in the figure, the left end point of f has moved forward to the left compared to the left end point of f", that is, the principal plane D of the left end point of f has moved forward to the left compared to the principal plane C of the main lens group unit, and the entire focal plane will move backward, for example, from A to B. When calculating the focal length, the position of the principal plane is determined according to the reverse extension line of the converging light, and the reverse extension line can be seen Figure 5B This is also an advantage of the optical path: L<f, which realizes a longer focal length f with a relatively short physical entity size L.

[0095] For the TX end, based on the optical path of the original main lens group unit (i.e., the main lens group), a concave lens array 503 is used in the embodiment of the present application to lengthen the focal length, and a microlens array 505 is used to compress and limit the divergence angle of the laser 501, so as to lengthen the focal length from the focal length f" of the main lens group unit to the equivalent focal length f, and let M be the focal length magnification, M = f / f". According to formula (1), the FOV remains unchanged, and as the focal length f increases, a increases accordingly, that is, the light-emitting surface is increased. Furthermore, the luminous energy of a single pixel (corresponding to a point in the point cloud image of the laser radar) can be increased, the power density within the corresponding point cloud field of view angle area is increased, and the distance measurement capability is also proportionally increased.

[0096] Exemplarily, the pitch between two adjacent microlenses in the microlens array 504 is the same as the pitch of the light-emitting point. It should be noted that the three concave lenses corresponding to the three lasers 511 and the three microlenses corresponding to each laser 511 shown in the figure are all schematic numbers, and do not limit their specific implementation.

[0097] exist Figure 5A and Figure 5B In the example, the light emitting surface B of the laser array 501 (including the light emitting surface of each laser) is located on the focal plane of the equivalent lens of the first optical component, so as to maintain a distance of equivalent focal length f from the principal plane D of the equivalent lens.

[0098] In order to see the increase of the luminous surface more intuitively, you can refer to Figure 6 shown.

[0099] exist Figure 6, a schematic diagram of the front view structure of the enlarged light-emitting surface formed at different focal lengths in the embodiment of the present application is shown. Figure 6 From left to right, the comparison of the size of the light-emitting surface is shown in the cases where M is less than but approximately 1 (i.e., the light-emitting surface is not enlarged, or the light path without a concave lens is used, such as the light path including only the main lens group unit), M is less than but approximately 2, and M is less than but approximately 4; the equivalent enlargement of the light-emitting area of ​​the eight light-emitting surfaces 11, 12, 13, 14, 21, 22, 23 and 24 in three cases is shown. Figure 5A or Figure 5B and Figure 6 To understand, Figure 5A , Figure 5B The three lasers arranged vertically in the middle side view can be located in one column, for example, corresponding to Figure 6 Where M is less than but close to 2, corresponding to a row of light-emitting surfaces 11, 12 and 13. Each laser is provided with a micro-concave lens Y in a concave lens array. For intuitive illustration, only Figure 6 A concave lens is drawn on the right side of the middle image by selecting a light-emitting surface 21, which is presented as a circle surrounding the light-emitting surface 21. In fact, other lasers are also equipped with corresponding concave lenses, which are just omitted here. It should be noted that the diameter of the concave lens is larger than the diameter of the light-emitting surface so that the light-emitting surface can be fully covered and more light from the transmitted signal can be received. However, the height of the laser radar should also be considered to limit the diameter of the concave lens to an appropriate size.

[0100] according to Figure 6 It can be seen that with the change of M, according to the single luminous surface diameter in the three cases, it is enlarged by M times from a0→a1→a2, and the luminous surface area is enlarged by M times from a0→a1→a2. 2 times magnification. When the light-emitting surface corresponding to each laser becomes larger, the long-range capability of the laser increases. At the point cloud level, the power density within the point cloud field of view angle area can be increased, thereby improving the distance measurement capability of the laser radar. In addition, although in the case where M is less than but close to 4, the light-emitting surfaces of the most adjacent lasers are relatively close (such as light-emitting surface 11 and light-emitting surface 13), when the emission angle area a2" equivalent to the far field will be a2 / M, there will be no overlap and the problem of not being able to be identified as two light-emitting surfaces. It should be noted that when the equivalent focal length of the first optical component is M times the focal length of the main lens group unit, if the laser is set on the focal plane of the first optical component, the entire area of ​​each laser is M times the area of ​​the laser if it is set on the focal plane of the main lens group unit. 2 If the duty cycle of the laser remains unchanged, the area of ​​the light-emitting surface of each laser will increase by M compared to the area of ​​the light-emitting surface if it is set on the focal plane of the main lens group. 2 times.

[0101] Alternatively, Figure 6 It can be seen that the height size can be maintained by adjusting the layout of the light-emitting surface under different focal magnifications M. Figure 6 Comparing the heights h0, h1, and h2 in the three cases, h2 is slightly larger than h1, and h1 is slightly larger than h0, but their differences can be ignored in actual situations. That is to say, the height size of the laser radar can be almost unchanged, but the emitting surface of each laser has obtained M 2 times magnification, at the point cloud level, the power density within the point cloud field of view can be increased by M 2 times, thus improving the distance measurement capability of the laser radar.

[0102] In another example, the focal length of the optical detection module can be enlarged by similar optical components. For the detection end, while lengthening the focal length, the receiving angle area can be reduced while keeping the area of ​​the receiving device unchanged, thereby reducing the background light noise power within the point cloud field of view angle area, thereby also improving the radar's distance measurement capability.

[0103] like Figure 7 As shown, a schematic diagram of the structure of the optical detection module of the laser radar in the embodiment of the present application is shown. The optical detection module includes an optical detector array 701, including a plurality of optical detectors 711 arranged in an array. The optical detector 711 is configured to detect that the emission signal reaches an object and is reflected to achieve detection. Among them, a "channel" is formed between one or more optical detectors 711 and one or more lasers, such as a channel is formed between a light detector and a laser, and the echo signal of the laser's emission signal is received by the optical detector 711 belonging to the same channel, and each channel corresponds to the detection of a certain field of view angle or a certain field of view angle range (receiving angle area). In a specific example, each of the optical detectors 711 can be implemented by, for example, SiPM (Silicon Photo Multiplier) or SPAD (s) (Single Photon Avalanche Diode).

[0104] Exemplarily, the optical detection module may further include a second optical component arranged corresponding to the optical detector array 701. The second optical component specifically includes a second converging unit and a second diverging unit. Figure 6In the figure, the second converging unit may be an existing lens or lens group for converging echo signals, and may be equivalently shown as the convex lens 702 on the far left in the figure, for converging echo signals for transmission to the photodetector array 701. The second diverging unit may be implemented as a concave lens array 703, wherein each concave lens 731 is respectively arranged corresponding to a photodetector 711; accordingly, the pitch between the concave lenses 731 adjacent in the longitudinal direction may be equal to the spacing between the centers of adjacent photodetectors 711 in a column of the photodetector array 701.

[0105] The focal length of the convex lens 702 is f2", which is schematically shown in the figure as the length from the main plane G of the convex lens 702 to its focal plane H. Exemplarily, the distance between the main plane G of the convex lens 702 and the concave lens array 703 may be within the focal length f2" of the equivalent lens.

[0106] The principal plane of the equivalent lens formed by the combination of the convex lens 702 and the concave lens array 703 is I, which is shifted to the left compared to G. It can be understood that, compared with the previous figure 5A, Figure 5B The principle is the same. The position of the I plane can be determined by the reverse extension lines K1 and K2 in the figure. For the sake of intuitiveness and clarity, it is simply represented in a simplified manner ("...") in the figure, and it should be understood by referring to the previous figure.

[0107] Thus, as shown in the figure, a focal length f2 is formed that is extended compared to the focal length f2" of the convex lens 702, and the distance from I to the focal plane J. Optionally, the photosensitive surface of the light detector array 701 can be located on the focal plane J at the right end of f2 to obtain the focusing of the echo signal. The physical length from G to J is L2, and it can be seen that f2 exceeds the physical distance limit of L2.

[0108] Different from the focal length extension of the optical transmitter module (i.e., TX end), for the receiving end of the laser radar, under the premise of ensuring that as many real detection signals as possible are received (echo signals reflected after the transmitted signal encounters obstacles), it is necessary to reduce the received background light intensity as much as possible to improve the signal-to-noise ratio. The following formula gives the background light P on the receiving side: B :

[0109]

[0110] Where pb is the background radiation density; BW is the half-height width of the filter (nm); ρ is the reflectivity of the target; tr is the optical efficiency of the receiving lens; A is the effective aperture (m), Sr is the effective area of ​​the detector, and f is the focal length.

[0111] According to the above formula, it can be seen that by extending the focal length of the light detection module (i.e., the RX end), the background light noise power within the point cloud field of view angle area can be reduced, the signal-to-noise ratio can be improved, and the ranging capability of the entire laser radar can be improved while maintaining the height size of the laser radar. In addition, if the equivalent focal length of the second optical component is P times the focal length of the main lens group unit at the receiving end, P>1, the receiving angle area can be reduced by P 2 It should be noted that the use of different letter symbols for the transmitting end and the receiving end, such as M and P, to represent the magnification of the extended focal length of the optical component, is only to illustrate that the transmitting and receiving sides can use different magnifications, but it is understandable that the transmitting and receiving sides can also be set to the same magnification. In some places in the article, only M is discussed, and P is similar, and no secondary description is made in the application.

[0112] In addition to the light transmitting module and the light detecting module, the laser radar usually also includes a control module (not shown) for controlling the light transmitting module to transmit the transmitting signal and controlling the light detecting module to detect the data of the echo signal, and can calculate the data to obtain the detection result.

[0113] According to the above-mentioned embodiments or a combination of the embodiments, the various problems described above can be solved. On the one hand, by making the optical path of the light emitting module and the light detecting module obtain a larger focal length, it is possible to increase the focal length of the laser radar by M times while maintaining the total height of the focal plane, so that the overall size of the laser radar remains almost unchanged. On the other hand, for the transmitting module TX, the size of the light-emitting surface corresponding to a single pixel point can be increased, thereby increasing the power density; for the receiving module RX, the receiving angle area can be reduced, thereby reducing the background light noise power within the point cloud field of view angle area; and thus, both are beneficial to improving the ranging capability; and the increase in f reduces d / f, which means that the angular difference between adjacent lasers in the vertical direction is reduced, thereby improving the vertical angle resolution. On the other hand, Figure 5B A microlens array is arranged in front of the laser array to focus the emission signal, which is also beneficial to further improve the utilization efficiency of the emitted light.

[0114] In some embodiments, reference may be made to Figure 8 and Fig. 9 , in order to explore the reasonable value of M.

[0115] Compared with before Figure 5A and Figure 5B Similar, in Figure 8 In the figure, f" is the focal length of the convex lens 802 equivalent to the main lens unit, f is the focal length of the first optical component, and L is the physical size. The equivalent focal length achieved by the combination of the convex lens 802 and the concave lens 803 is f, and f = M*f". It should be noted that, Figure 8The figure schematically shows the optical path of an emission signal of one of the light-emitting points of a laser 801 after being compressed by a microlens 804 and then diffused by a corresponding concave lens 803. Not all the light-emitting points of the laser 801 are drawn, nor are other lasers and corresponding other concave lenses (representing concave lenses) drawn, but they can actually exist.

[0116] According to the markings shown in the figure, the calculation formula of M is as follows (2):

[0117] M=f / f"=Δy / Δy"≈a / β (2)

[0118] Wherein, Δy is the height of the laser on the focal plane after the extended focal length (y direction), i.e., the height of the light-emitting surface corresponding to this position, and Δy" is the height of the light-emitting surface equivalent to the focal plane of the convex lens 802. In order to maximize the magnification M, the cone angle β = (laser divergence angle θ * OA / PITCH) needs to be as small as possible, and the F value (aperture value) should be designed. f is the focal length, D is the aperture diameter) is smaller, that is, the main lens (i.e. the main lens group) with a relatively large aperture. Figure 8 , the main lens cone angle = α; the divergence angle of the laser 801 = θ; β is related to the light output quality of the laser 801 itself on the one hand, and the compression effect of the microlens array on the other hand.

[0119] In addition, the upper limit of M can also be derived. After enlarging the focal length f, the divergence angle of the light-emitting surface of the same area (which can be understood as a unchanged) is proportionally reduced (common divergence angle θ = 2 × arctan (a / 2f)), and the angular resolution is improved, so the lasers in the laser array are allowed to be arranged in multiple columns (N columns) in an interlaced manner.

[0120] The number of staggered columns N should be limited. N may affect the width of the radar product. Although the width is not as important as the height, it cannot be ignored. If there are N columns of lasers staggered, considering that all the light emitted by each laser can pass through the concave lenses set one by one (for example Fig. 9 If the laser is covered by concave lenses, the height of the luminous surface needs to be slightly smaller than the pitch of the adjacent concave lenses. It should be noted that the specific size of the luminous height is related to the shape of the laser. If the laser is round, the height refers to the diameter of the entire laser; if the laser is rectangular, the height refers to the width or length of the laser.

[0121] refer to Fig. 9 , showing a schematic diagram of an enlarged light-emitting surface in another embodiment of the present application.

[0122] Fig. 9From left to right, the eight light-emitting surfaces are shown in three cases: M is less than but approximately 1, N=1; M is less than but approximately 2, N=2; M is less than but approximately 4, N=4. That is, the leftmost corresponds to M is less than but approximately 1, N=1, showing that the eight light-emitting surfaces 11 to 24 are not enlarged and arranged in one column; the middle corresponds to M is less than but approximately 2, N=2, showing that the eight light-emitting surfaces are all enlarged by nearly 4 times and arranged in 2 columns; the rightmost corresponds to M is less than but approximately 4, N=4, showing that the eight light-emitting surfaces are all enlarged by nearly 16 times and arranged in 4 columns.

[0123] The figure also shows, by way of example, the concave lenses corresponding to each laser, such as the ring Z surrounding the light-emitting surface 11 in the figure. In order to prevent the emission signal of the laser from avoiding the concave lens, a constraint condition can be set that the concave lens needs to completely cover the light-emitting surface. If the height of the light-emitting surface before magnification is y0, the height of the light-emitting surface after magnification of approximately 2 times is y1, and the height of the light-emitting surface after magnification of approximately 4 times is y2, in order to allow all concave lenses to cover the light-emitting surface, the pitch of adjacent concave lenses in the longitudinal direction, such as y2, needs to be less than the height of Z (if Z is a circle, the height is the length of its diameter).

[0124] Under the restrictions described in the above embodiment, the following formula can be obtained:

[0125] The height of the light-emitting surface after magnification = M * the height of the light-emitting surface before magnification < the pitch of the concave lens = the focal length of the main lens unit (equivalent convex lens) * vertical angular resolution * N;

[0126] About: The height of the light-emitting surface after magnification is less than the pitch of the concave lens; it is intuitively visible, Fig. 9 The edges of the luminous surfaces (11-24) magnified approximately 2 times and 4 times are schematically drawn as dotted lines, while the edges of the concave lenses are schematically drawn as solid lines, and the dotted edges corresponding to each luminous surface fall into the solid line ring of the corresponding concave lens. The figure schematically indicates that the luminous surface 11 falls into the concave lens Z when it is magnified approximately 4 times.

[0127] About: The height of the luminous surface after magnification = M * the height of the luminous surface before magnification; reference Fig. 9 If the luminous surface is enlarged by 2 times, the height of the luminous surface after enlargement is y1; if the luminous surface is enlarged by 4 times, the height of the luminous surface after enlargement is y2; the pixel height before enlargement is y0, y2=2*y1=4*y0.

[0128] About: Concave lens pitch = main lens unit focal length * vertical angular resolution * N, reference Fig. 9 , the concave lens pitch is the distance between the centers of adjacent light-emitting surfaces. In the diagram, the distance b is used as the unit of measurement. The distance b is equal to the focal length of the main lens unit * the vertical angular resolution. The concave lens pitch is equal to N times the distance b. Fig. 9As shown in the figure, when the light-emitting surface is magnified by two times, the pitch of the concave lens is 2b; when the light-emitting surface is magnified by four times, the pitch of the concave lens is 4b.

[0129] The height of the light-emitting surface before magnification by M* < the focal length of the main lens group unit * the vertical angular resolution * N. Substituting y0, f", and d / f, we get M*y0 < b*N; if we can arrange adjacent light-emitting surfaces with almost no gap without considering process limitations, then y0 ≈ b. Therefore, we can obtain M (magnification factor) < N (the number of stagger-arranged columns). In other words, the entire optical path cannot be magnified without limit, and the number of columns N that the lasers can be arranged in is the upper limit of the magnification factor M, that is, M < N.

[0130] As Figure 6 and Fig. 9 , it can be seen that in the three cases of M = N = 1, M = N = 2, and M = N = 4, under the limitation of M < N, the increase in the height direction after arranging the light-emitting surfaces is extremely small and can be ignored compared to the size of the entire lidar, that is, h0 ≈ h1 ≈ h2. Thus, while improving the ranging ability of the lidar by extending the focal length of the emission module, there is no increase in the height direction.

[0131] It should be noted that the situation of the receiving end is similar. If the detector array is set as a Q-column detector with a staggered arrangement and the equivalent focal length of the second optical component is P times the focal length of the main lens group unit, then Q > P, which will not be elaborated here.

[0132] The applications and effects of the above solutions will be illustrated below through various embodiments of lidars.

[0133] As Fig. 10A shown, it is a schematic structural diagram of a lidar with a paraxial optical path structure in an embodiment of the present application. Fig. 10B It is a schematic layout structural diagram of the laser array and the optical detection component of the lidar with a paraxial optical path structure in an embodiment of the present application when viewed from the front. Fig. 10C Show Fig. 10B a schematic curve diagram of the ranging simulation result of the lidar in the figure.

[0134] As Fig. 10AAs shown, in this example, a laser radar 100 with a paraxial optical path structure is shown, that is, there is no overlapping segment between the transmission optical path of the transmission signal and the detection optical path of the echo signal. In a possible specific example, the laser radar 100 can be a mechanical laser radar 100, that is, it includes a rotating mechanism. The number of lines of the laser radar 100 can be more than 32 lines, such as 32 lines, 64 lines, 128 lines, 256 lines, etc., among which 128 lines, if the laser 1011 and the light detector 1041 form a channel in a one-to-one manner, means that there are 128 lasers 1011 and 128 light detectors 1041 corresponding to each other to form 128 channels. Multiple lasers 1011 can be arranged in multiple columns.

[0135] In the optical transmission module 1000, the laser array includes a laser array 1001, wherein the transmission signal light output by each laser 1011 (which may be processed by a microlens array first) is processed in turn by each concave lens 1022 and a main lens group unit 1021 (equivalent to a convex lens) of the first optical component 1002, and then emitted from the laser radar 100, and reflected by the obstacle P to form an echo signal. The echo signal enters the laser radar 100, and is sequentially converged to the light detection module 1003 by a receiving lens group unit 1051 (equivalent to a convex lens) and each concave lens 1052 of an optional second optical component 1005. The light detection component in the light detection module 1003 may include a light detector array 1004, wherein a light detector 1041 of a channel corresponding to the echo signal can detect the echo signal.

[0136] The first optical component 1002 and the second optical component 1005 respectively form an extended equivalent focal length, for example, M times the focal length of the original lens group, so that the distance measurement capability of the laser radar 100 is improved, so that a farther obstacle P can be detected. Optionally, M can be a magnification of 1.5 times or more.

[0137] based on Fig. 10A The laser radar 100 with a paraxial optical path structure can be used, for example Fig. 10B The layout structure of the laser array 1001B and the photodetector array 1004B is shown, wherein two columns of lasers 1011B are arranged non-aligned, and two columns of photodetectors 1041B are arranged non-aligned.

[0138] Based on the adoption of Fig. 10A and Fig. 10B The laser radar 100 with a paraxial optical path structure is used for ranging simulation, and the simulation results are as follows Fig. 10C As shown. Fig. 10CIn the figure, the horizontal axis is the maximum measurable distance (corresponding to the distance measurement capability of the laser radar 100), and the vertical axis is the detection probability. It can be seen that under the condition of 90% detection probability, the maximum measurable distance reaches about 90 meters, while when the solution of the embodiment of the present application is not adopted, the maximum measurable distance of the same type of laser radar is only about 45 meters. Therefore, by extending the focal length to improve the distance measurement in the embodiment of the present application, the actual improvement of the distance measurement capability can be more than 2 times.

[0139] In addition to being applied to laser radars with off-axis optical path structures, in some embodiments, the solution of the present application can also be applied to laser radars with coaxial optical path structures, where coaxial means that the same optical path segment exists between the transmitting optical path and the detecting optical path.

[0140] like Fig.11A As shown, a schematic diagram of the structure of a laser radar with a coaxial optical path structure in an embodiment of the present application is shown.

[0141] The laser radar comprises:

[0142] The spectroscopic unit 1103 arranged in the overlapping optical path section is suitable for receiving the transmission signal from the first optical path section connected to the laser array (the laser array 1101 in this example) and refracting or directly irradiating it to the overlapping optical path section, and is suitable for receiving the echo signal from the overlapping optical path section and directly irradiating or deflecting it to the second optical path section connected to the light detector array 1102; wherein the main lens group unit 1104 (such as the main lens group in the aforementioned embodiment) and the first divergent unit 1105 (such as the concave lens array in the aforementioned embodiment) in the first optical component are respectively arranged in the overlapping optical path section and the first optical path section.

[0143] Exemplarily, the light splitting unit 1103 may be implemented by, for example, a reflector or a polarizing unit (such as a polarizing plate, a polarizing prism, etc.). In the illustrated example, the emission signal output by the laser array may first be diverged by the first diverging unit 1105 disposed in the first optical path segment and then enter the light splitting unit 1103, so as to be redirected (for example, turned, such as reflected, etc.) by the light splitting unit 1103 to the overlapping optical path segment (i.e., the optical path segment shared by the emission optical path and the detection optical path), transmitted to the left to the main lens group unit 1104 through the overlapping optical path segment, and emitted after being converged, as indicated by the emission optical path indicated by the black solid arrow in the figure.

[0144] Furthermore, the laser radar also includes a scanning unit 1106 (such as a galvanometer, a rotating mirror) to select the transmission signal of the channel to be detected to be emitted to the laser radar, and cooperate with the main lens group unit 1104 (a convex lens is shown in the figure as an example) and the first diverging unit 1105 to obtain a relatively extended equivalent focal length of the optical transmission module; and, the echo signal of the channel to be detected is selected to turn into the overlapping optical path section, and is transmitted to the right to the spectroscopic unit 1103, and is redirected (for example, directly) by the spectroscopic unit 1103 to the second optical path section connected to the optical detection component (in this example, the laser array 1102), and is transmitted to the laser array 1102 along the second optical path section, as indicated by the gray arrow in the figure. The receiving optical path. Possibly, the scanning unit 1106 may include one or more resonant single-axis micro-electromechanical system (MEMS) galvanometers to perform two-dimensional rotation to select the transmission signal and echo signal of the desired detection channel for transmission.

[0145] In the illustrated optional example, only a convex lens 1107 may be provided in the second optical path segment to focus the echo signal without providing a concave lens.

[0146] By configuring the focal lengths of the optical detection module (RX end) and the optical transmission module (TX end) to be in a certain proportional relationship, for example, the equivalent focal length of the optical detection module is several times (for example, K = 3.5 times) the equivalent focal length of the first optical component; and optionally, in the laser array 1101 of the laser array, the laser can use an edge emitting laser (EEL) to illuminate the entire receiving field of view by utilizing its small luminous area and high brightness; in the optical detector array 1102 of the optical detection component, the optical detector can be implemented using SiPM, and the size of the optical detector array 1102 can also be several times (for example, K) that of the laser array 1101. Thus, obtaining an ultra-long detection focal length greatly improves the ranging capability of the laser radar, for example, from 200 meters to 300 meters.

[0147] For example Fig. 11B As shown, Fig.11A The difference between the embodiments is that in the laser array 1101B of the laser array, the laser can be implemented by VCSEL to replace Fig.11A The EEL in the embodiment can further improve the ranging capability. Accordingly, in this example, a microlens array 1109 can be set up (a convex lens can also be added in the first optical path section) to compress the divergence angle of the VCSEL and leave the periphery of the light-emitting aperture for the detection optical path. Fig. 11B In the embodiment, the divergence angle of the laser is compressed and transmitted along the middle part of the coaxial optical path (indicated by the thin solid arrow), while the echo signal is transmitted in the peripheral area relative to the middle part (indicated by the thick solid arrow).

[0148] Please refer to Fig. 12Aand Fig. 12B The figure is used to illustrate the effect of encapsulating the optical path section from each laser to the corresponding concave lens in a sleeve in the embodiment of the present application. The inner wall of the sleeve is made of an absorbing material to absorb light.

[0149] like Fig. 12A The optical path diagram shown takes the emission optical path as an example. Although the light-emitting surface can be magnified without using a sleeve, it is necessary to maintain the focal length of the main lens group * the vertical angular resolution. Otherwise, the emission signal (such as C) of the light-emitting point near the edge of the laser 1201 may avoid the concave lens (concave lens 1202) and enter the main lens group unit (such as the main lens group, not drawn in this diagram). This part of the emission signal that has not passed through the first divergent unit will be defocused, and the echo signal that is likely to be formed after being sent out through the main lens group unit at a larger divergence angle will be received by the light detectors of other channels, thereby forming crosstalk. Therefore, this part of potential stray light can be absorbed by an absorbing material.

[0150] like Fig. 11B In the optical path diagram shown, the optical path section between the laser 1201 and the corresponding concave lens 1202 is encapsulated by the sleeve 1203, so that the emission signal that originally avoided the concave lens 1202 can be reflected and limited to pass through the concave lens 1202 and then reach the main lens group unit, so that this part of the emission signal will not be defocused, so that the light-emitting area of ​​the same or similar size as the concave lens can be achieved. For VCSEL, because the light-emitting area is increased, the corresponding peak power is also increased.

[0151] Similarly, if Fig. 12C As shown, it is used to illustrate the effect of the optical path section between the concave lenses 1302 corresponding to the echo signal in the embodiment of the present application being encapsulated in the sleeve 1303 and then reaching each detector 1301. The optical path is similar to the transmitting end, and also absorbs potential stray light, thereby improving the signal-to-noise ratio. The details will not be repeated here.

[0152] In summary, the present application provides a laser radar including: a laser array arranged in a linear array or a planar array, arranged in the focal plane of a first optical component, and a first optical component, arranged in the transmitting optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the transmitting end; and / or, a light detector array arranged in a linear array or a planar array, arranged in the focal plane of a second optical component, and the second optical component, arranged in the receiving optical path, forming an equivalent focal length greater than the focal length of the main lens group unit at the receiving end. In the embodiment of the present application, the power density within the point cloud field of view angle area is increased by setting the first optical component at the light transmitting end, and / or, the background light noise power within the point cloud field of view angle area is reduced by setting the second optical component at the receiving end, thereby improving the ranging capability of the radar.

[0153] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A laser radar, characterized in that: include: The optical transmission module is arranged at the focal plane of the first optical component, and includes: a laser array arranged in a linear array or a planar array, and is suitable for emitting a transmission signal, and the transmission signal is transmitted along a transmission optical path; A first optical component is provided in the emission light path, and has an equivalent focal length greater than a first preset value, so as to increase the power density within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the first preset value is the focal length of the main lens group unit; The equivalent focal length of the first optical component is M times the focal length of the main lens unit, M>1; The optical detection module comprises: an optical detector array arranged in a linear array or a planar array, and adapted to detect, from a receiving optical path, an echo signal reflected by the transmitting signal after encountering an obstacle.

2. The laser radar according to claim 1, characterized in that: The first optical assembly comprises: a main lens assembly unit, adapted to collimate the transmitted signal; It also includes: a first diverging unit, which is arranged between the laser array and the main lens group unit and is suitable for diverging the emission signal after being collimated by the main lens group unit, so that the first optical component has an equivalent focal length longer than a first preset value.

3. The laser radar according to claim 2, characterized in that: The area of ​​the light-emitting surface of each laser is increased by M 2 times.

4. The laser radar according to claim 2, characterized in that: The first diverging unit comprises: a concave lens array, wherein each concave lens corresponds to an emission channel.

5. The laser radar according to claim 4, characterized in that: The vertical pitch between adjacent concave lenses in the concave lens array is not less than the height of the light emitting surface of the laser.

6. The laser radar according to claim 1, characterized in that: The laser array includes N columns of lasers arranged in an interlaced manner, and the equivalent focal length of the first optical component is M times the focal length of the main lens group unit, where N>M.

7. The laser radar according to claim 4, characterized in that: At least a portion of the optical path section between each laser and the corresponding concave lens is encapsulated in a sleeve, and the inner wall of the sleeve is made of an absorbing material.

8. The laser radar according to claim 1 or 4, characterized in that: The first optical component further includes: a microlens array, wherein each microlens is arranged corresponding to a light-emitting point of the laser.

9. The laser radar according to claim 1, characterized in that: The laser radar is a mechanical laser radar or a MEMS laser radar with a rotating mechanism.

10. The laser radar according to claim 1, characterized in that: The laser array comprises a plurality of lasers, wherein the lasers are vertical cavity surface emitting lasers or edge emitting lasers or photonic crystal structure surface emitting semiconductor lasers; and / or the photodetector is a single photon avalanche diode or a silicon photomultiplier tube.

11. A laser radar, characterized in that: include: The optical transmission module comprises: a laser array arranged in a linear array or a planar array, suitable for emitting a transmission signal, wherein the transmission signal is transmitted along a transmission optical path; The light detection module is arranged at the focal plane of the second optical component, and includes: a light detector array arranged in a linear array or a planar array, and is suitable for detecting the echo signal reflected by the transmission signal after encountering an obstacle from the receiving light path; and the second optical component is arranged in the receiving optical path, and has an equivalent focal length greater than a second preset value, so as to reduce the background light noise power within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the second preset value is the focal length of the main lens group unit; The equivalent focal length of the second optical component is P times the focal length of the main lens unit, where P>1.

12. The laser radar according to claim 11, characterized in that: The second optical component comprises: a receiving lens group unit, adapted to converge the received signal; The second optical component also includes: a second diverging unit, which is arranged between the light detector array and the receiving lens group unit, so that the second optical component has an equivalent focal length longer than a second preset value, suitable for diverging the receiving signal converged by the receiving lens group unit.

13. The laser radar according to claim 11, characterized in that: The receiving angle area is reduced 2 times.

14. The laser radar according to claim 12, characterized in that: The second diverging unit comprises: a concave lens array, wherein each concave lens corresponds to a detector setting.

15. The laser radar according to claim 14, characterized in that: The vertical pitch between adjacent concave lenses in the concave lens array is greater than the height of the receiving surface of each detector.

16. The laser radar according to claim 11, characterized in that: The detector array includes Q columns of detectors arranged in an interlaced manner, and the equivalent focal length of the second optical component is P times the focal length of the main lens group unit, Q>P.

17. The laser radar according to claim 11, characterized in that: include: The first optical component is arranged in the emission light path, and has an equivalent focal length greater than a first preset value, so as to improve the power density within the point cloud field of view angle area, thereby improving the ranging capability of the radar; wherein the first preset value is the focal length of the main lens group unit in the first optical component; the equivalent focal lengths of the first optical component and the second optical component are in a certain proportional relationship.

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