Laser emission system and lidar

Abstract

This application relates to the field of lidar technology and provides a laser emitting system and lidar. The laser emitting system includes a diverging laser unit, a first pre-collimation module, a processing module unit, and a second pre-collimation module arranged sequentially. The processing module unit includes a first processing unit and a second processing unit. The beam emitted by the diverging laser unit is split into a first beam and a second beam after passing through the first pre-collimation module. The first beam passes through the second processing unit and then directly passes through the second pre-collimation module. The second beam passes through the first processing unit and then sequentially passes through the second processing unit and the second pre-collimation module. The emission direction of the second beam is the same as that of the first beam. This application improves the laser emission power, increases the far-field laser power density, and merges the near-field spots of multiple LD chips into one, resulting in a high-brightness far-field spot.

Description

Technical Field

[0001] This application belongs to the field of lidar technology, and more specifically, relates to a laser emitting system and lidar. Background Technology

[0002] The ranging capability of a lidar is positively correlated with its emission power; the most direct way to improve ranging capability is to increase the laser emission power. A lidar emission optical system typically includes a combination of optical elements such as collimating lenses, light-blocking apertures, reflectors, and windows to shape the emitted laser and suppress stray light. After absorption and multiple reflections by these optical elements, the emitted power is significantly reduced compared to the light emitted from a bare chip, thus decreasing the ranging capability. Furthermore, a single lidar emission chip, constrained by semiconductor tunneling and surface electric field effects, finds it difficult to significantly increase its emitted power under a given excitation current.

[0003] Currently, most high-power semiconductor-coupled lasers on the market use an optical system to collimate the laser's fast and slow axes. The collimated beam is then shaped into a square spot by a beam shaping system, and finally coupled to a single optical fiber via an aspherical or multi-lens focusing system to achieve high-power, high-brightness output. This method does not emphasize the coincidence of the far-field spot and far-field divergence angle, and its coupling efficiency is low. It also requires large-diameter multimode fibers, making it unsuitable for miniaturized lidar systems with low divergence angles.

[0004] Autonomous vehicles need to anticipate road conditions and make braking and steering responses in advance. The active ranging capability of lidar sensors determines the decision-making time of autonomous vehicles. Simply improving ranging capability is not a crucial lidar parameter; ensuring a sufficiently small far-field divergence angle is also essential. For example, a far-field divergence angle of less than 5 mrad is necessary to ensure that the light spot is smaller than the vehicle's outline within the 150-200m range, allowing the vehicle's shape to be distinguished in the point cloud image. The far-field divergence angle θ of the lidar emission system is determined by the area L of the LD chip's active region and the focal length f of the collimation system, θ ≈ arctan(L / f). Due to the overall size of the lidar, the focal length f of the collimation system cannot be infinitely long, thus limiting the size of the active region area of ​​the chip. Furthermore, the light output power of the LD chip is directly proportional to the area of ​​its active region.

[0005] In current lidar systems, not only are the requirements for far-field divergence angle and size limiting the emitted laser power of a single lidar LD chip, but the scanning beam is also emitted at fixed field-of-view intervals, with horizontal and vertical field-of-view resolutions ranging from 0.07° to 0.5°. Furthermore, the number of key targets within the lidar's field of view is limited, meaning that most of the lidar points emitted do not hit the target of interest, resulting in wasted emission frequency. Increasing the number of target echo points within the field of view using a fixed field-of-view approach requires increasing the emission repetition rate of the LD chip. However, excessively high repetition rates can easily lead to overheating and burnout of the LD chip. Summary of the Invention

[0006] The purpose of this application is to provide a laser emitting system and a lidar to solve the following technical problems:

[0007] The requirements for far-field divergence angle and size limit the emitted laser power of a single LD chip in lidar. The scanning beam is emitted at fixed field-of-view intervals, with horizontal and vertical field-of-view resolution ranging from 0.07° to 0.5°. However, the number of key targets within the radar's field of view is limited, and most of the lidar points emitted in the field of view do not hit the target of interest, resulting in a waste of emission frequency. To increase the number of target echo points within the field of view using a fixed field-of-view method, it is necessary to increase the emission repetition rate of the LD. However, an excessively high LD repetition rate can easily lead to overheating and burnout of the LD chip.

[0008] To achieve the above objectives, firstly, the technical solution adopted in this application is:

[0009] A laser emitting system is provided, comprising a diverging laser unit, a first pre-collimation module, a processing module unit, and a second pre-collimation module arranged sequentially. The processing module unit includes a first processing unit and a second processing unit. The laser beam emitted by the diverging laser unit is split into a first beam and a second beam after passing through the first pre-collimation module. The first beam passes directly through the second pre-collimation module after passing through the second processing unit. The second beam passes through the second processing unit and then sequentially passes through the second processing unit and the second pre-collimation module. The emission direction of the second beam is the same as that of the first beam.

[0010] In one feasible technical solution of this application, the laser emitting system further includes a circuit board, on which the diverging laser unit, the first pre-collimation module and the processing module unit are all mounted, and the first pre-collimation module is located between the diverging laser unit and the processing module unit.

[0011] In one feasible technical solution of this application, the diverging laser unit includes multiple LD chips, which are placed side by side on a straight line, and the straight line is arranged parallel to and spaced apart from the first pre-collimation module.

[0012] In one feasible technical solution of this application, the diverging laser unit further includes a heat sink mounted on the circuit board, and the plurality of LD chips and the first pre-collimation module are all mounted on the heat sink.

[0013] In one feasible technical solution of this application, the first pre-collimation module is a single fast-axis collimation lens.

[0014] In one feasible technical solution of this application, the second pre-collimation module includes a second fast-axis collimating lens and a slow-axis collimating lens arranged at intervals, with the second fast-axis collimating lens located between the slow-axis collimating lens and the processing module unit.

[0015] In one feasible technical solution of this application, the first processing unit includes a waveplate and a first beam steering unit, the waveplate is attached to the light-incident side of the first beam steering unit, and the light-outcident side of the first beam steering unit is attached to the first light-incident side of the second processing unit.

[0016] In one feasible technical solution of this application, the second processing unit includes a beam compensation unit and a second beam steering unit, wherein the beam compensation unit is attached to the second light-incident side of the second beam steering unit.

[0017] In one feasible technical solution of this application, the diverging laser unit includes multiple LD chips, which are staggered relative to the processing module unit. The first pre-collimation module includes multiple fast-axis collimating lenses, which are arranged in a one-to-one correspondence with the multiple LD chips.

[0018] In one feasible technical solution of this application, the diverging laser unit further includes a plurality of heat sinks mounted on the circuit board, wherein the plurality of heat sinks are arranged in a one-to-one correspondence with the plurality of LD chips, and the LD chips are mounted on the heat sinks.

[0019] In one feasible technical solution of this application, the first processing unit includes a half-wave plate and a reflecting unit, the half-wave plate is attached to the light-incident side of the reflecting unit, and the light-exiting side of the reflecting unit is attached to the first light-incident side of the second processing unit.

[0020] In one feasible technical solution of this application, the second processing unit includes a clamping and positioning unit and a beam-combining unit, wherein the beam-combining unit is clamped between the clamping and positioning unit and the reflection unit.

[0021] In one feasible technical solution of this application, the circuit board is provided with a first mounting surface and a second mounting surface, the first mounting surface is higher than the second mounting surface, the first pre-collimation module is mounted on the first mounting surface, and the first processing unit and the second processing unit are both mounted on the second mounting surface.

[0022] To achieve the above objectives, secondly, the technical solution adopted in this application is:

[0023] A lidar is provided, including the laser emitting system described above.

[0024] In summary, this application includes at least one of the following beneficial technical effects:

[0025] The large-aperture beam is split into two. The first and second beams are processed by different units, which change the laser shape of the two parts respectively. Finally, they are modulated and combined to output a beam with twice the energy power density.

[0026] Simultaneously, by increasing the number of LDs and arranging them side-by-side or staggered, the emitted lasers from multiple LDs can be combined and output. Through the first and second processing units, the basic principle of total internal reflection of polarized light can be used to observe the spot shape and divergence angle of the combined laser in the far field. The relative positions of each optical element can be continuously adjusted until the technical requirements for the far field divergence angle are met. This avoids wasting the emission frequency, eliminates the need to increase the emission repetition rate of the LD, and prevents the LD chip from overheating and burning out.

[0027] This system improves laser output power and far-field laser power density, and combines the near-field spots of multiple LD chips to obtain a high-brightness far-field spot. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram illustrating the core principle of the radar field-of-view stitching device provided in this application embodiment.

[0030] Figure 2 This is a schematic diagram of the planar structure of the radar field-of-view stitching device according to Embodiment 1 of this application.

[0031] Figure 3 This is a schematic diagram of the installation structure of various components on the circuit board in Embodiment 2 of this application.

[0032] The following are the labeling elements in the figure:

[0033] 100. Diverging laser unit; 11. LD chip; 12. Heat sink;

[0034] 200. First pre-collimation module;

[0035] 300. Processing module unit; 31. First processing unit; 311. Waveplate; 312. First beam steering unit; 313. Half-waveplate; 314. Reflection unit; 32. Second processing unit; 321. Beam compensation unit; 322. Second beam steering unit; 323. Clamping and positioning unit; 324. Beam combining unit;

[0036] 400. Second pre-collimation module; 41. Second fast-axis collimating lens; 42. Slow-axis collimating lens;

[0037] 500, Circuit board; 51, First mounting surface; 52, Second mounting surface. Detailed Implementation

[0038] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0039] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0040] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0042] Please refer to the following: Figures 1-3 The laser emitting system and lidar provided in the embodiments of this application will now be described.

[0043] This application provides a laser emitting system; please refer to [link / reference]. Figure 1 The system includes a diverging laser unit 100, a first pre-collimation module 200, a processing module unit 300, and a second pre-collimation module 400 arranged sequentially. The processing module unit 300 includes a first processing unit 31 and a second processing unit 32. The beam emitted by the diverging laser unit 100 is split into a first beam and a second beam after passing through the first pre-collimation module 200. The first beam passes directly through the second pre-collimation module 400 after passing through the second processing unit 32. The second beam passes through the first processing unit 31 and then sequentially passes through the second processing unit 32 and the second pre-collimation module 400. The emission direction of the second beam is the same as that of the first beam.

[0044] Furthermore, in this embodiment, the laser emission system also includes a circuit board 500, on which the diverging laser unit 100, the first pre-collimation module 200 and the processing module unit 300 are all mounted, and the first pre-collimation module 200 is located between the diverging laser unit 100 and the processing module unit 300.

[0045] Specifically, in this embodiment, the first pre-collimation module 200 is a single fast-axis collimation lens, and the second pre-collimation module 400 includes a second fast-axis collimation lens 41 and a slow-axis collimation lens 42 arranged at intervals, with the second fast-axis collimation lens 41 located between the slow-axis collimation lens 42 and the processing module unit 300.

[0046] To facilitate understanding of the technical solutions of the embodiments of this application by those skilled in the art, the first processing unit 31 includes a waveplate 311 and a first beam steering unit 312. The waveplate 311 is attached to the light-incident side of the first beam steering unit 312, and the light-outceasing side of the first beam steering unit 312 is attached to the first light-incident side of the second processing unit 32.

[0047] In this embodiment of the application, the second processing unit 32 includes a beam compensation unit 321 and a second beam steering unit 322, with the beam compensation unit 321 attached to the second light incident side of the second beam steering unit 322.

[0048] To better describe the technical solutions covered by this application, the following two specific embodiments are provided.

[0049] Example 1

[0050] Please see Figure 1 and Figure 2In the first embodiment of this application, the diverging laser unit 100 includes a plurality of LD chips 11 (for example, two are preferred in this first embodiment). The plurality of LD chips 11 are placed side by side on a straight line, and the straight line is arranged parallel to and spaced apart from the first pre-collimation module 200.

[0051] Meanwhile, in order to enhance the heat dissipation effect of the LD chip 11 and the first pre-collimation module 200 during operation, the diverging laser unit 100 also includes a heat sink 12 mounted on the circuit board 500, and multiple LD chips 11 and the first pre-collimation module 200 are mounted on the heat sink 12.

[0052] Example 2

[0053] Please see Figure 1 and Figure 3 In the second embodiment of this application, the diverging laser unit 100 includes a plurality of LD chips 11 (for example, two are preferred in this second embodiment as well). The plurality of LD chips 11 are staggered relative to the processing module unit 300. The first pre-collimation module 200 includes a plurality of fast-axis collimating lenses, and the plurality of fast-axis collimating lenses are arranged in a one-to-one correspondence with the plurality of LD chips 11.

[0054] In the second embodiment of this application, in order to enhance the heat dissipation effect of the LD chip 11 during operation, the divergent laser unit 100 further includes a plurality of heat sinks 12 mounted on the circuit board 500. The plurality of heat sinks 12 are arranged in a one-to-one correspondence with the plurality of LD chips 11, and the LD chips 11 are mounted on the heat sinks 12.

[0055] Understandably, in the second embodiment of this application, the first processing unit 31 includes a half-wave plate 313 and a reflection unit 314, and the half-wave plate 313 is specifically a half-wave plate 313. The half-wave plate 313 is attached to the light-incident side of the reflection unit 314, and the light-outcident side of the reflection unit 314 is attached to the first light-incident side of the second processing unit 32.

[0056] Understandably, the second processing unit 32 includes a clamping and positioning unit 323 and a beam-combining unit 324, with the beam-combining unit 324 clamped between the clamping and positioning unit 323 and the reflection unit 314.

[0057] Furthermore, in order to facilitate the precise installation of each component and maintain the stable emission of the beam, the circuit board 500 is provided with a first mounting surface 51 and a second mounting surface 52. The first mounting surface 51 is higher than the second mounting surface 52. The first pre-collimation module 200 is mounted on the first mounting surface 51, and the first processing unit 31 and the second processing unit 32 are both mounted on the second mounting surface 52.

[0058] This application also provides a lidar, including the laser emitting system described above. Apart from the laser emitting system, the other components of the lidar are similar to those of common lidars on the market, and will not be described in detail in this embodiment.

[0059] The laser emitting system provided in this application has the following expected technical effects compared with the prior art:

[0060] The large-aperture beam is split into two. The first and second beams are processed by different units, which change the laser shape of the two parts respectively. Finally, they are modulated and combined to output a beam with twice the energy power density.

[0061] Meanwhile, by increasing the number of LDs and arranging them side-by-side or staggered, the emitted lasers of multiple LDs can be combined and output. Through the first processing unit 31 and the second processing unit 32, the basic principle of total internal reflection of polarized light can be used to observe the spot shape and divergence angle of the combined laser in the far field. The relative positions of each optical element can be continuously adjusted until the technical requirements of the far field divergence angle are met. This avoids wasting the emission frequency, eliminates the need to increase the emission repetition rate of the LD, and prevents the LD chip 11 from overheating and burning out.

[0062] This system improves the laser output power and far-field laser power density, and combines the near-field spots of multiple LD chips 11 to obtain a high-brightness far-field spot.

[0063] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A laser emission system, characterized by, The system includes a diverging laser unit (100), a first pre-collimation module (200), a processing module unit (300), and a second pre-collimation module (400) arranged sequentially. The processing module unit (300) includes a first processing unit (31) and a second processing unit (32). The beam emitted by the diverging laser unit (100) is split into a first beam and a second beam after passing through the first pre-collimation module (200). The first beam passes through the second processing unit (32) and then directly passes through the second pre-collimation module (400). The second beam passes through the first processing unit (31) and then sequentially passes through the second processing unit (32) and the second pre-collimation module (400). The emission direction of the second beam is the same as that of the first beam. The diverging laser unit (100) includes multiple LD chips (11), which are placed side by side on a straight line. The straight line is parallel to and spaced apart from the first pre-collimation module (200). The side-by-side placement can be either side-by-side or staggered.

2. The laser emission system of claim 1, wherein, The laser emission system further includes a circuit board (500), on which the diverging laser unit (100), the first pre-collimation module (200) and the processing module unit (300) are all mounted, and the first pre-collimation module (200) is located between the diverging laser unit (100) and the processing module unit (300).

3. The laser emission system of claim 2, wherein, The diverging laser unit (100) also includes a heat sink (12) mounted on the circuit board (500), and the plurality of LD chips (11) and the first pre-collimation module (200) are all mounted on the heat sink (12).

4. The laser emitting system as described in claim 2, characterized in that, The first pre-collimation module (200) is a single fast-axis collimation lens.

5. The laser emitting system as described in claim 2, characterized in that, The second pre-collimation module (400) includes a second fast-axis collimating lens (41) and a slow-axis collimating lens (42) arranged at intervals, with the second fast-axis collimating lens (41) located between the slow-axis collimating lens (42) and the processing module unit (300).

6. The laser emitting system as described in claim 1, characterized in that, The first processing unit (31) includes a waveplate (311) and a first beam steering unit (312). The waveplate (311) is attached to the light-incident side of the first beam steering unit (312), and the light-outcident side of the first beam steering unit (312) is attached to the first light-incident side of the second processing unit (32).

7. The laser emitting system as described in claim 6, characterized in that, The second processing unit (32) includes a beam compensation unit (321) and a second beam steering unit (322), wherein the beam compensation unit (321) is attached to the second incident light side of the second beam steering unit (322).

8. The laser emitting system as described in claim 2, characterized in that, The diverging laser unit (100) includes multiple LD chips (11), which are staggered relative to the processing module unit (300). The first pre-collimation module (200) includes multiple fast-axis collimating lenses, which are arranged in a one-to-one correspondence with the multiple LD chips (11).

9. The laser emitting system as described in claim 8, characterized in that, The diverging laser unit (100) also includes a plurality of heat sinks (12) mounted on the circuit board (500), and the plurality of heat sinks (12) are arranged in a one-to-one correspondence with the plurality of LD chips (11), and the LD chips (11) are mounted on the heat sinks (12).

10. The laser emitting system as described in claim 8, characterized in that, The first processing unit (31) includes a half-wave plate (313) and a reflecting unit (314). The half-wave plate (313) is attached to the light-incident side of the reflecting unit (314), and the light-outcident side of the reflecting unit (314) is attached to the first light-incident side of the second processing unit (32).

11. The laser emitting system as described in claim 10, characterized in that, The second processing unit (32) includes a clamping and positioning unit (323) and a beam combining unit (324), wherein the beam combining unit (324) is clamped between the clamping and positioning unit (323) and the reflection unit (314).

12. The laser emitting system as described in claim 2, characterized in that, The circuit board (500) is provided with a first mounting surface (51) and a second mounting surface (52). The first mounting surface (51) is higher than the second mounting surface (52). The first pre-collimation module (200) is mounted on the first mounting surface (51). The first processing unit (31) and the second processing unit (32) are both mounted on the second mounting surface (52).

13. A lidar, characterized in that, Includes the laser emitting system as described in any one of claims 1 to 12.

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