Laser emission system and laser radar

Abstract

The invention relates to the technical field of laser radars, and provides a laser emission system and a laser radar wherein the laser emission system comprises a divergent laser unit, a first pre-collimation module, a processing module unit and a second pre-collimation module which are arranged in sequence, and the processing module unit comprises a first processing unit and a second processing unit. A light beam emitted by the divergent laser unit is divided into a first light beam and a second light beam after passing through the first pre-collimation module, the first light beam directly passes through the second pre-collimation module after passing through the second processing unit, and the second light beam sequentially passes through the second processing unit and the second pre-collimation module after passing through the first processing unit. The emergent direction of the second light beam is consistent with the emergent direction of the first light beam. The laser emitting power is improved, the far-field laser power density is improved, near-field light spots of a plurality of LD chips are combined together, and high-brightness far-field light spots are obtained.

Description

Technical Field

[0001] The present application belongs to the field of laser radar technology, and more specifically, to a laser emission system and a laser radar. Background Art

[0002] The ranging capability of LiDAR is positively correlated with the transmission power. The most direct way to improve the ranging capability is to increase the laser transmission power. The LiDAR transmission optical system generally includes a combination of optical components such as collimating lenses, shading apertures, reflectors and windows to achieve the shaping of the output laser and the elimination of stray light. After absorption and multiple reflections by these optical components, the output power has dropped significantly compared to the light output of the bare chip, and the ranging capability has decreased accordingly. However, a single LD transmitting chip is constrained by the semiconductor tunneling effect and the surface electric field effect. Under the specified excitation current, it is difficult to significantly increase the output power.

[0003] At present, the common high-power semiconductor coupled lasers on the market use an optical system to collimate the fast and slow axes of the laser. The collimated beam is integrated into a square spot through a beam shaping system, and then coupled to a single optical fiber through an aspheric or multi-lens group focusing system to achieve high-power and high-brightness spot output. This method does not emphasize the overlap of far-field spot and far-field divergence angle, and the coupling efficiency is not high. It requires a large-diameter multimode optical fiber and is not suitable for LiDAR transmission systems in miniaturized and low-divergence application scenarios.

[0004] Autonomous vehicles need to prejudge road conditions and make advance braking and steering responses. The active ranging capability of LiDAR sensors determines the decision time of autonomous vehicles. Improving ranging capability alone is not an important LiDAR parameter. It is also necessary to ensure that the far-field divergence angle is small enough. For example, the far-field divergence angle must be less than 5mrad to ensure that the light spot is smaller than the outline of the car in the range of 150 to 200m, and the shape of the vehicle can be distinguished in the point cloud image. The far-field divergence angle θ of the LiDAR transmitting system is determined by the area L of the LD chip's active area and the focal length f of the collimation system. θ≈arctan(L / f) is limited by the overall size of the LiDAR. The focal length f of the collimation system cannot be infinitely long, so the size of the chip's luminous active area will also be limited, and the light output power of the LD chip is proportional to the area of ​​the luminous active area.

[0005] In the current laser radar system, not only the requirements of far-field divergence angle and size limit the output laser power of a single LD chip of the laser radar, but also the scanning beam is emitted at fixed field of view angle intervals, and the horizontal and vertical field of view resolution ranges from 0.07° to 0.5°. Then the key targets within the radar field of view are limited, and most of the laser radar points emitted from the field of view do not hit the target of interest, resulting in a waste of emission point frequency. In order to increase the number of target echo points within the field of view in a fixed field of view angle, it is necessary to increase the luminescence repetition rate of the LD chip. If the repetition rate of the LD chip is too high, it is easy to cause the LD chip to overheat and burn. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a laser emission system and a laser radar to solve the following technical problems:

[0007] The requirements for far-field divergence angle and size limit the output laser power of a single LD chip of the LiDAR. The scanning beam is emitted at fixed field of view angle intervals, and the horizontal and vertical field of view resolution ranges from 0.07° to 0.5°. The number of key targets within the radar field of view is limited, and most of the LiDAR points emitted from the field of view do not hit the target of interest, resulting in a waste of emission point frequency. In order to increase the number of target echo points within the field of view in a fixed field of view angle, it is necessary to increase the LD's light emission repetition rate. Too high a LD repetition rate can easily cause the LD chip to overheat and burn out.

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

[0009] A laser emission system is provided, comprising a divergent laser unit, a first pre-collimation module, a processing module unit and a second pre-collimation module arranged in sequence, the processing module unit comprising a first processing unit and a second processing unit, a light beam emitted by the divergent laser unit is divided into a first light beam and a second light beam after passing through the first pre-collimation module, the first light beam directly passes through the second pre-collimation module after passing through the second processing unit, the second light beam passes through the second processing unit and the second pre-collimation module in sequence after passing through the first processing unit, and the emission direction of the second light beam is consistent with the emission direction of the first light beam.

[0010] In an achievable technical solution of the present application, the laser emission system also includes a circuit board, the divergent laser unit, the first pre-collimation module and the processing module unit are all installed on the circuit board, and the first pre-collimation module is located between the divergent laser unit and the processing module unit.

[0011] In an achievable technical solution of the present application, the divergent laser unit includes a plurality of LD chips, and the plurality of LD chips 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 an achievable technical solution of the present application, the divergent laser unit further includes a heat sink portion mounted on the circuit board, and the plurality of LD chips and the first pre-collimation module are all mounted on the heat sink portion.

[0013] In a feasible technical solution of the present application, the first pre-collimation module is a single fast-axis collimating mirror.

[0014] In an achievable technical solution of the present application, the second pre-collimation module comprises a second fast-axis collimator and a slow-axis collimator arranged at intervals, and the second fast-axis collimator is located between the slow-axis collimator and the processing module unit.

[0015] In an achievable technical solution of the present application, the first processing unit includes a wave plate and a first light beam steering unit, the wave plate is adhered to the light incident side of the first light beam steering unit, and the light output side of the first light beam steering unit is adhered to the first light incident side of the second processing unit.

[0016] In an achievable technical solution of the present application, the second processing unit includes a beam compensation unit and a second beam steering unit, and the beam compensation unit is attached to the second light incident side of the second beam steering unit.

[0017] In an achievable technical solution of the present application, the divergent laser unit includes a plurality of LD chips, and the plurality of LD chips are staggered relative to the processing module unit; the first pre-collimation module includes a plurality of fast-axis collimating mirrors, and the plurality of fast-axis collimating mirrors are arranged in one-to-one correspondence with the plurality of LD chips.

[0018] In an achievable technical solution of the present application, the divergent laser unit further comprises a plurality of heat sinks mounted on the circuit board, the plurality of heat sinks are arranged in one-to-one correspondence with the plurality of LD chips, and the LD chips are mounted on the heat sinks.

[0019] In an achievable technical solution of the present application, the first processing unit includes a half-wave plate and a reflection unit, the half-wave plate is adhered to the light incident side of the reflection unit, and the light emitting side of the reflection unit is adhered to the first light incident side of the second processing unit.

[0020] In an achievable technical solution of the present application, the second processing unit includes a clamping and positioning unit and a beam combining unit, and the beam combining unit is clamped between the clamping and positioning unit and the reflecting unit.

[0021] In an achievable technical solution of the present application, a first mounting surface and a second mounting surface are provided on the circuit board, the first mounting surface is higher than the second mounting surface, the first pre-alignment module is installed on the first mounting surface, and the first processing unit and the second processing unit are both installed on the second mounting surface.

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

[0023] A laser radar is provided, comprising the above-mentioned laser emission system.

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

[0025] The large-aperture beam is divided into two parts. The first beam and the second beam are processed by different processing units, respectively changing the laser forms of the two parts, and finally modulated into one, thereby outputting a light spot with twice the energy power density.

[0026] At the same time, by increasing the number of LDs, arranging them side by side or staggered, the output lasers of multiple LDs are combined and output, and by using the basic principle of total reflection of polarized light, the first processing unit and the second processing unit can be used to observe the spot shape and divergence angle of the combined laser in the far field, and continuously adjust the relative positions of the optical elements until the technical requirements of the far-field divergence angle are met, which is not likely to cause waste of emission point frequency, and there is no need to increase the LD light repetition frequency, which is not likely to cause overheating and burning of the LD chip;

[0027] This system improves the laser output power, increases the far-field laser power density, and merges the near-field light spots of multiple LD chips together to obtain a high-brightness far-field light spot. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 A schematic diagram of the core principles of the radar field of view stitching device provided in an embodiment of the present application.

[0030] Figure 2 This is a schematic diagram of the planar structure of the radar field of view stitching device of Example 1 of the present application.

[0031] Figure 3 This is a schematic diagram of the installation structure of various accessories on the circuit board in Example 2 of the present application.

[0032] Among them, the reference numerals in the figure are:

[0033] 100, divergent laser unit; 11, LD chip; 12, heat sink;

[0034] 200, a first pre-collimation module;

[0035] 300, processing module unit; 31, first processing unit; 311, wave plate; 312, first beam steering unit; 313, half-wave plate; 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, a second pre-collimation module; 41, a second fast-axis collimation mirror; 42, a slow-axis collimation mirror;

[0037] 500, circuit board; 51, first mounting surface; 52, second mounting surface. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

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

[0040] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] Please also read Figure 1-Figure 3 , the laser emission system and laser radar provided in the embodiments of the present application are now described.

[0043] The present application embodiment provides a laser emission system. Figure 1 , including a divergent laser unit 100, a first pre-collimation module 200, a processing module unit 300 and a second pre-collimation module 400 arranged in sequence, the processing module unit 300 includes a first processing unit 31 and a second processing unit 32, the light beam emitted by the divergent laser unit 100 is divided into a first light beam and a second light beam after passing through the first pre-collimation module 200, the first light beam directly passes through the second pre-collimation module 400 after passing through the second processing unit 32, the second light beam passes through the first processing unit 31 and then passes through the second processing unit 32 and the second pre-collimation module 400 in sequence, and the emission direction of the second light beam is consistent with the emission direction of the first light beam.

[0044] Moreover, in the present embodiment, the laser emission system further includes a circuit board 500, on which the divergent 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 divergent 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 collimator, and the second pre-collimation module 400 includes a second fast-axis collimator 41 and a slow-axis collimator 42 arranged at intervals, and the second fast-axis collimator 41 is located between the slow-axis collimator 42 and the processing module unit 300 .

[0046] To facilitate technicians in this field to understand the technical solutions of the embodiments of the present application, the first processing unit 31 includes a wave plate 311 and a first light beam steering unit 312. The wave plate 311 is attached to the light incident side of the first light beam steering unit 312, and the light output side of the first light beam steering unit 312 is attached to the first light incident side of the second processing unit 32.

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

[0048] In order to better describe the technical solutions that can be covered by this application, the following two specific embodiments are provided.

[0049] Embodiment 1

[0050] See also Figure 1 and Figure 2In the first embodiment of the present application, the divergent laser unit 100 includes a plurality of LD chips 11 (for example, preferably two in the first embodiment), and the plurality of LD chips 11 are placed side by side on a straight line, and the straight line is parallel to the first pre-collimation module 200 and arranged at intervals.

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

[0052] Embodiment 2

[0053] See also Figure 1 and Figure 3 In the second embodiment of the present application, the divergent laser unit 100 includes a plurality of LD chips 11 (for example, the second embodiment is also preferably two), and 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 mirrors, and the plurality of fast-axis collimating mirrors are arranged one-to-one with the plurality of LD chips 11.

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

[0055] It can be understood that in embodiment 2 of the present 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 adhered to the light incident side of the reflection unit 314, and the light emitting side of the reflection unit 314 is adhered to the first light incident side of the second processing unit 32.

[0056] It can be understood that the second processing unit 32 includes a clamping and positioning unit 323 and a beam combining unit 324 , and the beam combining unit 324 is sandwiched between the clamping and positioning unit 323 and the reflecting unit 314 .

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

[0058] The embodiment of the present application also provides a laser radar, including the above-mentioned laser emission system, and the other accessories of the laser radar except the laser emission system are similar to the common laser radars on the market, and will not be repeated in this embodiment.

[0059] Compared with the prior art, the laser emission system provided in this application has the following expected technical effects:

[0060] The large-aperture beam is divided into two parts. The first beam and the second beam are processed by different processing units, respectively changing the laser forms of the two parts, and finally modulated into one, thereby outputting a light spot with twice the energy power density.

[0061] At the same time, by increasing the number of LDs, arranging them side by side or staggered, the output lasers of multiple LDs are combined and output, and by using the basic principle of total reflection of polarized light, the first processing unit 31 and the second processing unit 32 can be used to observe the spot shape and divergence angle of the combined laser beam in the far field, and the relative positions of the optical elements are continuously adjusted until the technical requirements of the far-field divergence angle are met, which is not likely to cause waste of emission point frequency, and there is no need to increase the light repetition rate of LD, and it is not likely to cause overheating and burning of the LD chip 11;

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

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

Claims

1. A laser emission system, characterized in that: The invention comprises a divergent laser unit (100), a first pre-collimation module (200), a processing module unit (300) and a second pre-collimation module (400) which are arranged in sequence; the processing module unit (300) comprises a first processing unit (31) and a second processing unit (32); a light beam emitted by the divergent laser unit (100) is divided into a first light beam and a second light beam after passing through the first pre-collimation module (200); the first light beam directly passes through the second pre-collimation module (400) after passing through the second processing unit (32); the second light beam passes through the first processing unit (31) and then passes through the second processing unit (32) and the second pre-collimation module (400) in sequence; and the emission direction of the second light beam is consistent with the emission direction of the first light beam.

2. The laser emitting system according to claim 1, characterized in that: The laser emission system further comprises a circuit board (500), the divergent laser unit (100), the first pre-collimation module (200) and the processing module unit (300) are all mounted on the circuit board (500), and the first pre-collimation module (200) is located between the divergent laser unit (100) and the processing module unit (300).

3. The laser emitting system according to claim 2, characterized in that: The divergent laser unit (100) comprises a plurality of LD chips (11), wherein 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 from the first pre-collimation module (200).

4. The laser emitting system according to claim 3, characterized in that: The divergent laser unit (100) further comprises 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 both mounted on the heat sink (12).

5. The laser emitting system according to claim 2, characterized in that: The first pre-collimation module (200) is a single fast-axis collimating mirror.

6. The laser emitting system according to claim 2, characterized in that: The second pre-collimation module (400) comprises a second fast-axis collimator (41) and a slow-axis collimator (42) arranged at intervals, and the second fast-axis collimator (41) is located between the slow-axis collimator (42) and the processing module unit (300).

7. The laser emitting system according to claim 1, characterized in that: The first processing unit (31) comprises a wave plate (311) and a first light beam steering unit (312); the wave plate (311) is adhered to the light incident side of the first light beam steering unit (312); and the light exit side of the first light beam steering unit (312) is adhered to the first light incident side of the second processing unit (32).

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

9. The laser emitting system according to claim 2, characterized in that: The divergent laser unit (100) comprises a plurality of LD chips (11), the plurality of LD chips (11) are placed in an offset manner relative to the processing module unit (300), and the first pre-collimation module (200) comprises a plurality of fast-axis collimating mirrors, the plurality of fast-axis collimating mirrors are arranged in a one-to-one correspondence with the plurality of LD chips (11).

10. The laser emitting system according to claim 9, characterized in that: The divergent laser unit (100) further comprises a plurality of heat sinks (12) mounted on the circuit board (500), the plurality of heat sinks (12) being arranged in one-to-one correspondence with the plurality of LD chips (11), and the LD chips (11) being mounted on the heat sinks (12).

11. The laser emitting system according to claim 9, characterized in that: The first processing unit (31) comprises a half-wave plate (313) and a reflection unit (314), wherein the half-wave plate (313) is adhered to the light incident side of the reflection unit (314), and the light emitting side of the reflection unit (314) is adhered to the first light incident side of the second processing unit (32).

12. The laser emitting system according to claim 12, characterized in that: The second processing unit (32) comprises a clamping and positioning unit (323) and a beam combining unit (324), and the beam combining unit (324) is clamped between the clamping and positioning unit (323) and the reflecting unit (314).

13. The laser emitting system according to 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-alignment 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).

14. A laser radar, characterized in that: Comprising a laser emission system as described in any one of claims 1 to 13.

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