A lidar illumination device and a lidar system

Abstract

An embodiment of the present invention discloses a laser radar lighting device and a laser radar system. In one specific embodiment, the device includes: a semiconductor laser, a pyramid prism, a lens assembly, and a receiving lens; the semiconductor laser is used to emit a Gaussian beam; the lens assembly is used to preliminarily collimate the Gaussian beam emitted by the semiconductor laser and output it to the top surface of the pyramid prism; the pyramid prism is used to split the preliminarily collimated Gaussian beam input from its top surface and output multiple split beams from its bottom surface to the target to be measured, so that the split beams are incoherently superimposed on the surface of the target to be measured to form a flat-top beam for illumination. This embodiment utilizes the spectral characteristics of the pyramid prism itself to split the preliminarily collimated beam and incoherently superimpose it on the surface of the target to be measured to obtain a flat-top beam with uniform intensity, good distance transmission characteristics, and field of view matching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser radar. More particularly, it relates to a laser radar illumination device and a laser radar system. BACKGROUND

[0002] Laser radar is an optoelectronic remote sensing detection device that uses laser as a radiation source to actively measure the distance, i.e. depth data, of a measurement target by using the intensity, phase, polarization, etc. of the reflected light echo.

[0003] The laser radar illumination device mainly serves to illuminate the measurement target, and the quality of the illumination beam has a great influence on the measurement accuracy and imaging quality. The semiconductor laser, i.e. laser diode, in the laser radar illumination device is a kind of active illumination light source suitable for laser radar. The semiconductor laser has a special resonant cavity structure and working mode, and the spatial distribution of the light beam is asymmetric, and the light intensity distribution is uneven within the respective divergence angle. The unshaped semiconductor laser beam cannot meet the illumination requirements of the laser radar system, because the asymmetry of the illumination field does not match the receiving surface of the sensor, which is not conducive to fully utilizing the light energy, and the uneven distribution of the light intensity within the illumination field leads to a reduction in the available dynamic range of the system.

[0004] At present, the commonly used semiconductor laser beam homogenization techniques include: diffuse reflector, diffractive optical element, binary diffraction grating, liquid crystal spatial light modulator, compound eye lens, optical fiber, and integrating rod, etc.

[0005] However, the inventors have found that the method of using a diffractive optical element can achieve flat-top uniform illumination, but cannot maintain the spatial propagation characteristics. The quality level of the binary diffraction grating is restricted by the development level of micro-fine processing technology, and the laser damage threshold is low, which has difficulties in the application of strong laser systems. The laser damage threshold of the liquid crystal spatial light modulator is low, and the device is expensive and not easy to integrate. The compound eye lens can only produce a uniform light beam within a specific range, and the edge has a considerable proportion of non-uniform area. These methods have low coupling efficiency and high coupling cost, and have great technical difficulties, which are also not conducive to miniaturization and integration. The methods of using optical fibers and integrating rods have low coupling efficiency and high coupling cost, and have great technical difficulties, which are also not conducive to miniaturization and integration.

[0006] In summary, the illumination of laser radar needs to meet three conditions of field matching, high-quality uniformity, and good distance transmission characteristics, but these homogenization illumination techniques have different degrees of deficiencies, which are not suitable or cannot meet the illumination requirements of laser radar. SUMMARY

[0007] The application aims to provide a laser radar lighting device and a laser radar system for homogenizing light through a pyramid prism to solve at least one of the problems in the prior art.

[0008] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0009] The first aspect of the application provides a laser radar lighting device, comprising:

[0010] a semiconductor laser, a lens group and a pyramid prism;

[0011] The semiconductor laser is configured to emit a Gaussian beam.

[0012] The lens group is configured to preliminarily collimate the Gaussian beam emitted by the semiconductor laser and output to the top surface of the pyramid prism.

[0013] The pyramid prism is configured to divide the preliminarily collimated Gaussian beam input from the top surface thereof and output a plurality of divided beams from the bottom surface thereof to a target to be measured, so that the divided beams are incoherently superimposed on the surface of the target to be measured to form a flat-top beam for illumination.

[0014] Further, the pyramid prism comprises a quadrangular pyramid part and a cuboid part, the conical surface of the quadrangular pyramid part serving as the top surface of the pyramid prism, and the surface of the cuboid part away from the quadrangular pyramid part serving as the bottom surface of the pyramid prism.

[0015] Further, the bottom surface of the quadrangular pyramid part is coplanar with the surface of the cuboid part close to the quadrangular pyramid part.

[0016] Further, the included angle between the opposite conical surfaces of the quadrangular pyramid part is designed to satisfy the following condition:

[0017]

[0018] wherein, α is the included angle between the opposite conical surfaces of the quadrangular pyramid part, K is the F number of the preliminarily collimated beam, and n is the refractive index of the material of the pyramid prism.

[0019] Further, the first optical axis of the Gaussian beam emitted by the semiconductor laser and the second optical axis of the preliminarily collimated beam output by the lens group are coaxial, and the second optical axis and the optical axes of the divided beams output by the pyramid prism are parallel to each other.

[0020] Further, the top surface and the bottom surface of the pyramid prism are coated with an anti-reflection film.

[0021] Further, the materials of the lens group and the pyramid prism are K9 glass or quartz.

[0022] The second aspect of the present application provides a laser radar system, comprising:

[0023] A laser radar system, characterized in that comprising:

[0024] At least one laser radar illuminating device as described in the first aspect, for outputting a plurality of segmented light beams to a target to be measured, so that the segmented light beams are incoherently superimposed on the surface of the target to be measured to form a flat-top light beam for illumination;

[0025] The segmented light beams are incoherently superimposed on the surface of the target to be measured to form a flat-top light beam for illumination and are reflected;

[0026] A receiving lens for receiving the flat-top light beam reflected by the target to be measured;

[0027] A detection sensor for detecting the flat-top light beam reflected by the target to be measured received by the receiving lens;

[0028] A processing and display module for processing and displaying the data detected by the detection sensor.

[0029] Further, the optical axis of the segmented light beam output by the laser radar illuminating device is parallel to the receiving optical axis of the receiving lens.

[0030] Further, the laser radar system comprises a plurality of laser radar illuminating devices and the plurality of laser radar illuminating devices are arranged in an array.

[0031] The present application has the following beneficial effects:

[0032] The present application utilizes the light splitting characteristics of the pyramid prism itself to segment the light beam after preliminary collimation and incoherently superimpose on the surface of the target to be measured to obtain a flat-top light beam with uniform intensity, good distance transmission characteristics and meeting the field of view matching. BRIEF DESCRIPTION OF DRAWINGS

[0033] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0034] Figure 1 Fig. 1 shows a structural schematic diagram of an illuminating device provided by an embodiment of the present application when the target to be measured is illuminated with shadows;

[0035] Figure 2 Fig. 2 shows a structural schematic diagram of a laser radar system provided by an embodiment of the present application when the target to be measured is illuminated without shadows;

[0036] Figure 3 Fig. 3 shows a structural schematic diagram of a preliminary collimated Gaussian light beam incident to a pyramid prism provided by an embodiment of the present application;

[0037] Figure 4 A structure diagram showing that the split beams provided by one embodiment of the present application are incoherently superimposed on the surface of the target to be measured is shown.

[0038] Figure 5 A combined image of the image taken by the camera, the image obtained using the pyramid prism, and the image obtained without using the pyramid prism at different detection distances and different targets to be measured provided by one embodiment of the present application is shown.

[0039] Legend of reference signs:

[0040] 1, a laser radar illuminating device; 11, a semiconductor laser; 12, a lens group; 13, a pyramid prism; 2, a receiving lens; 3, a detection sensor; 4, a target to be measured. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the present application, the present application will be further described below in conjunction with embodiments and drawings. Similar components are denoted by the same reference signs in the drawings. It should be understood by those skilled in the art that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0042] A laser radar illuminating device 1, comprising:

[0043] a semiconductor laser 11, a lens group 12, and a pyramid prism 13;

[0044] The semiconductor laser 11 is configured to emit a Gaussian beam;

[0045] The lens group 12 is configured to preliminarily collimate the Gaussian beam emitted by the semiconductor laser 11 and output to the top surface of the pyramid prism;

[0046] The pyramid prism 13 is configured to split the preliminarily collimated Gaussian beam input from the top surface thereof and output a plurality of split beams from the bottom surface thereof to the target to be measured 4, so that the split beams are incoherently superimposed on the surface of the target to be measured 4, forming a flat-top beam for illumination.

[0047] In one possible implementation, the pyramid prism 13 comprises a four-pyramid body and a cuboid body, the conical surface of the four-pyramid body serving as the top surface of the pyramid prism 13, and the surface of the cuboid body away from the four-pyramid body serving as the bottom surface of the pyramid prism 13.

[0048] The bottom surface of the four-pyramid body is coplanar with the surface of the cuboid body close to the four-pyramid body. Further, the pyramid prism 13 is an integrally formed structure, so that the contact surface between the four-pyramid body and the cuboid body has sufficient light transmittance.

[0049] The application utilizes the light splitting characteristics of the pyramid prism 13 itself to split the primary collimated light beam and to superimpose the split light beams incoherently on the surface of the target object to obtain a flat-top light beam with uniform intensity, good distance transmission characteristics and matching field of view.

[0050] In one possible implementation, the included angle between the opposite conical surfaces of the quadrangular pyramid is designed to satisfy the following condition:

[0051]

[0052] wherein α is the included angle between the opposite conical surfaces of the quadrangular pyramid, K is the F number of the primary collimated light beam, and n is the refractive index of the material of the pyramid prism 13.

[0053] The first optical axis of the Gaussian light beam emitted by the semiconductor laser 11 and the second optical axis of the primary collimated light beam output by the lens group 12 are coaxial, and the second optical axis and the optical axes of the split light beams output by the pyramid prism 13 are parallel to each other.

[0054] In one possible implementation, the top surface and the bottom surface of the pyramid prism 13 are coated with an anti-reflection film.

[0055] The anti-reflection film is coated on the surface of the pyramid prism 13 to increase the transmittance of the light beams incident on and emitted from the pyramid prism 13.

[0056] In one possible implementation, the materials of the lens group 12 and the pyramid prism 13 are K9 glass or quartz.

[0057] In one specific implementation, the semiconductor laser 11 emits a Gaussian light beam to the lens group 12, the lens group 12 performs primary collimation on the Gaussian light beam and sends the primary collimated light beam to the top surface of the pyramid prism 13, and the pyramid prism 13 splits the primary collimated light beam and outputs split light beams to the target object, which are superimposed incoherently on the surface of the target object to obtain a flat-top light beam for illumination. In order to ensure that the split light beams can be effectively superimposed, avoid the occurrence of a part (i.e., a shadow) on which the split light beams cannot be irradiated after the split light beams irradiate the surface of the target object, the following design is required: Figure 2

[0058] As shown in Figure 3 and Figure 4 The relationship between the beam angle of the split light beam and the included angle between the two adjacent conical surfaces of the pyramid prism 13 is determined as follows:

[0059] δ = (n-1) α (2)

[0060] ​Wherein, δ is the angle between the two light rays with the largest angle and the illumination boundary of the Gaussian light beam after primary collimation; α is the angle between the relative cone surfaces of the four-pyramid; n is the refractive index of the material of the pyramid prism 13.

[0061] Determine the value of the angle between the two light rays with the largest angle and the illumination boundary of the Gaussian light beam after primary collimation after being incident on the pyramid prism 13.

[0062]

[0063] Wherein, δ is the angle between the two light rays with the largest angle and the illumination boundary of the Gaussian light beam after primary collimation; K is the F number of the primary collimated light beam.

[0064] The formula (2) is brought into the formula (3) to obtain the value range of the angle between the two sides of the pyramid prism 13.

[0065] In order to ensure that the split light beam does not appear after being irradiated to the surface of the target to be measured, the angle between the relative cone surfaces of the four-pyramid is designed to satisfy the following conditions:

[0066]

[0067] Wherein, α is the angle between the relative cone surfaces of the four-pyramid, K is the F number of the primary collimated light beam, and n is the refractive index of the material of the pyramid prism.

[0068] In combination with the contents of Figure 2 , Figure 3 and Figure 4 , the split light beam includes a first light beam, a second light beam, a third light beam, and a fourth light beam, and the Gaussian light beam after primary collimation is split into four light beams symmetrical about the split light beam optical axis by the pyramid prism 13, wherein the light beam irradiated on the P1 surface is split by the pyramid to be irradiated on the S1 region of the target to be measured as the first light beam. Similarly, the light beam irradiated on the P2 surface is split by the pyramid to be irradiated on the S2 region of the target to be measured as the second light beam, the light beam irradiated on the P3 surface is split by the pyramid to be irradiated on the S3 region of the target to be measured as the third light beam, and the light beam irradiated on the P4 surface is split by the pyramid to be irradiated on the S4 region of the target to be measured as the fourth light beam.

[0069] As shown in Figure 4 , on the basis of satisfying formula (1), by using pyramid prisms 13 with different angles, the size is adjusted, and then the size of the shadow area of the target to be measured is adjusted to eliminate the shadow area; the split Gaussian light beam after primary collimation is effectively superimposed.

[0070] In a specific embodiment, the semiconductor laser 11 has a wavelength in the near-infrared band, including but not limited to 850 nm, 905 nm, 940 nm, and 1550 nm. The lens group 12 is an optical lens group 12, and the material of the lens group 12 and the pyramid prism 13 are both K9 glass or quartz. K9 glass is an optical glass. The advantage of using K9 glass as the material is its low price. However, the purity of K9 glass quartz is low, and the absorption rate of light will be higher. Although the corresponding quartz glass has a higher cost, the purity of quartz is high, and the absorption rate of light will be lower.

[0071] More specifically, in order to increase the light transmittance of the pyramid prism 13 , the anti-reflection film in this embodiment is a near-infrared band anti-reflection film.

[0072] In another aspect, the present invention provides a laser radar system comprising:

[0073] At least one laser radar lighting device 1 as described above, configured to output a plurality of split light beams to a target 4 to be measured, such that the split light beams are incoherently superimposed on the surface of the target to be measured to form a flat-top beam for illumination;

[0074] Receiving lens 2, used to receive the flat-top beam reflected by the target to be measured;

[0075] The detection sensor 3 is used to detect the flat-top beam reflected by the target to be measured and received by the receiving lens 2;

[0076] The processing and display module is used to process and display the data detected by the detection sensor 3.

[0077] In one possible implementation, the optical axis of the split light beam output by the laser radar lighting device (1) is parallel to the receiving optical axis of the receiving lens 2.

[0078] In one possible implementation, the laser radar system includes a plurality of laser radar lighting devices 1 and the plurality of laser radar lighting devices 1 are distributed in an array.

[0079] In one possible implementation, the system further includes a power supply module, which is used to supply power to the laser radar lighting device 1, the detection sensor 3, and the processing and display module respectively.

[0080] In a specific embodiment, Figure 3 As shown, the leftmost column is the actual image captured by the camera of the present invention, the middle column is the image captured when the pyramid prism 13 is not used in the present invention, and the rightmost column is the image captured when the pyramid prism 13 is used in the present invention; more specifically, Figure 3The image in the first row is when the detection distance is 1.21 m; the image in the second row is when the detection distance is 3.75 m; the image in the third row is when the detection distance is 7.79 m; and the image in the fourth row is when the detection distance is 18.71 m. It can be obviously seen from the figure that the image collected after the light is shaped by the pyramid prism 13 is more complete, comprehensive and has more information elements than the image collected without the pyramid prism 13 under different detection distances and different scenes.

[0081] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional 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 systems or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0082] It should also be noted that in the description of the present application, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0083] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not limitations on the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A laser radar lighting device, characterized in that: include: Semiconductor laser, lens assembly and pyramid prism; The semiconductor laser is used to emit a Gaussian beam; The lens group is used to preliminarily collimate the Gaussian beam emitted by the semiconductor laser and output it to the top surface of the pyramid prism; The pyramid prism is used to split the preliminarily collimated Gaussian beam input from its top surface and output multiple split beams from its bottom surface to the target to be measured, so that the split beams are incoherently superimposed on the surface of the target to be measured to form a flat-top beam for illumination; The pyramid prism includes a quadrangular pyramid portion and a rectangular parallelepiped portion, the conical surface of the quadrangular pyramid serves as the top surface of the pyramid prism, and the surface of the rectangular parallelepiped away from the quadrangular pyramid serves as the bottom surface of the pyramid prism; The angle between the opposite cone surfaces of the quadrangular pyramid is designed to meet the following conditions: (1) in, is the angle between the opposite cone faces of the tetrahedron, K is the F degree of the initial collimated beam, n is the refractive index of the pyramid prism material; The bottom surface of the quadrangular pyramid is coplanar with the surface of the cuboid close to the quadrangular pyramid.

2. The device according to claim 1, characterized in that The first optical axis of the Gaussian beam emitted by the semiconductor laser and the second optical axis of the preliminary collimated beam output by the lens group are coaxial, and the second optical axis and the optical axes of each split beam output by the pyramid prism are parallel to each other.

3. The device according to claim 1, characterized in that The top and bottom surfaces of the pyramid prism are coated with anti-reflection films.

4. The device according to claim 1, characterized in that The lens group and the pyramid prism are made of K9 glass or quartz.

5. A laser radar system, characterized in that: include: At least one laser radar lighting device according to any one of claims 1 to 4, configured to output a plurality of split light beams to a target to be measured, so that the split light beams are incoherently superimposed on the surface of the target to be measured to form a flat-top beam for illumination; A receiving lens, used for receiving the flat-top beam reflected by the target to be measured; A detection sensor is used to detect the flat-top light beam received by the receiving lens and reflected by the target to be measured; The processing and display module is used to process and display the data detected by the detection sensor.

6. The system according to claim 5, characterized in that The optical axis of the split light beam output by the laser radar lighting device is parallel to the receiving optical axis of the receiving lens.

7. The system according to claim 5, characterized in that The laser radar system includes a plurality of laser radar lighting devices, and the plurality of laser radar lighting devices are distributed in an array.

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