Laser radar

Abstract

The invention relates to a laser radar, and the laser radar comprises a transmitting array, laser pulses transmitted by the transmitting array form a light spot array at a preset distance, in the light spot array, the angle interval of adjacent light spots in a first direction is smaller than a first angle, and the angle interval of adjacent light spots in a second direction is smaller than a second angle. The first angle is determined according to the first resolution, and the second angle is determined according to the second resolution, so that the light spot array meets the first resolution requirement in the first direction and meets the second resolution requirement in the second direction. The maximum angle distribution of the light spots in the light spot array is smaller than the first preset value, the maximum angle distribution reflects the heat effect coupling between the light spots, and the maximum angle distribution of the light spots is smaller than the first preset value, so that the mutual heat influence between the light spots can be reduced, the heat effect coupling can be reduced, and the human eye safety of the laser radar can be improved.

Description

Technical Field

[0001] This application belongs to the field of laser detection, and particularly relates to a lidar. Background Art

[0002] Lidar is widely used in autonomous driving and needs to meet the requirements of ultra-long ranging ability and high resolution. The ultra-long ranging ability requires the lidar to emit high-power laser beams so as to receive echo signals with sufficient energy, and the high resolution requires the emitters that emit laser beams to be densely arranged. However, when a lidar with densely arranged emitters and high-power laser beams is used for target detection, it will cause damage to pedestrians' eyes. Summary of the Invention

[0003] In view of this, the embodiments of this application provide a lidar that meets the requirements of ultra-long ranging ability and high resolution of the lidar while meeting eye safety.

[0004] The first aspect of the embodiments of this application provides a lidar, which includes a transmitting array. The laser pulses emitted by the transmitting array form a spot array at a preset distance. In the spot array, the angular interval between adjacent spots in the first direction is less than a first angle, and the angular interval between adjacent spots in the second direction is less than a second angle. The maximum angular distribution of the spots in the spot array is less than a first preset value. The first angle is determined according to a first resolution, and the second angle is determined according to a second resolution.

[0005] In one embodiment, the angular interval between adjacent spots in the first direction is less than a third angle, or the angular interval between adjacent spots in the second direction is less than the third angle. The third angle is greater than the first angle and greater than the second angle. The maximum angular distribution of the spot combination formed by adjacent spots is less than the first preset value, and the maximum angular distribution of the spot combination is determined according to the side length of the region where the spot combination is located.

[0006] In one embodiment, the angular interval between adjacent spots in the first direction is greater than or equal to the third angle, and the angular interval between adjacent spots in the second direction is greater than or equal to the third angle. The third angle is greater than the first angle and greater than the second angle. The maximum angular distribution of a single spot is less than the first preset value, and the maximum angular distribution of a single spot is determined according to the side length of the region where the single spot is located.

[0007] In one embodiment, the light spots in the light spot array are the light spots formed by the laser pulses emitted by the emission array in the same emission, and the light spots in the light spot array correspond one-to-one to the emitters in the emission array; the angular interval between adjacent light spots in the first direction is equal to the arrangement interval of the emitters in the first direction; the angular interval between adjacent light spots in the second direction is equal to the arrangement interval of the emitters in the second direction.

[0008] In one embodiment, the lidar further includes a scanning device, the rotational speed of the scanning device in the first direction is less than a first preset speed, the rotational speed of the scanning device in the second direction is less than a second preset speed, and / or, the emission frequency of the laser pulses is less than a preset frequency, so that the angular interval between the light spots formed by adjacent laser pulses in the first direction is less than the first angle, and the angular interval between the light spots formed by adjacent laser pulses in the second direction is less than the second angle.

[0009] In one embodiment, the emission interval of the same laser pulse is greater than a first interval, and the opposite angle of the first duration is determined according to the thermal accumulation of one laser pulse.

[0010] In one embodiment, the emission interval of the same laser pulse is less than the first interval and greater than a second interval, and the opposite angle of the first duration is determined according to the thermal accumulation of two laser pulses.

[0011] In one embodiment, the emission interval of the same laser pulse is less than the second interval, and the opposite angle of the first duration is determined according to the thermal accumulation of three laser pulses.

[0012] In one embodiment, the lidar further includes a zoom system, the laser pulse is emitted to the detection area through the zoom system, and the zoom system is used to increase the size of the light spot when it is determined that the distance of the object to be measured in the detection area is less than a first distance, and to reduce the size of the light spot when it is determined that the distance of the object to be measured in the detection area is greater than a second distance.

[0013] In one embodiment, the lidar further includes a power adjustment device, and the power adjustment device is used to reduce the power of the laser pulse when it is determined that the distance of the object to be measured in the detection area is less than the first distance.

[0014] In one embodiment, the wavelength of the laser pulse is in the near-infrared band and the wavelength is greater than a first preset value. The beneficial effects of the embodiments of the present application compared with the prior art are as follows: The laser pulses emitted by the emission array of the lidar form a spot array at a preset distance. In the spot array, the angular interval between adjacent spots in the first direction is less than a first angle, and the angular interval between adjacent spots in the second direction is less than a second angle. The first angle is determined according to a first resolution, and the second angle is determined according to a second resolution. Therefore, the spot array meets the first resolution requirement in the first direction and the second resolution requirement in the second direction. The maximum angular distribution of the spots in the spot array is less than a first preset value. The maximum angular distribution reflects the thermal effect coupling between the spots. The maximum angular distribution of the spots being less than the first preset value can reduce the mutual thermal influence between the spots, reduce the thermal effect coupling, and thus improve the eye safety of the lidar. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art.

[0016] Figure 1 are schematic diagrams of different spot arrays formed by the lidar provided in an embodiment of the present application;

[0017] Figure 2 is a schematic diagram for determining the maximum angular distribution provided in an embodiment of the present application;

[0018] Figure 3 are schematic diagrams of different spot shapes provided in an embodiment of the present application;

[0019] Figure 4 is a schematic diagram for determining the maximum angular distribution of two spots provided in an embodiment of the present application;

[0020] Figure 5 is a schematic diagram of the angular interval of the spots provided in an embodiment of the present application;

[0021] Figure 6 is a schematic diagram of the structure of a radar provided in an embodiment of the present application;

[0022] Figure 7 is a schematic diagram of a zoom system provided in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0024] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0025] It should be further understood that the term "and / or" used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0027] The vehicle-mounted lidar applied to autonomous driving can identify the positions of surrounding roads, buildings, and pedestrians during road travel, so as to construct a three-dimensional map. Therefore, it is required to meet ultra-long ranging capabilities and high resolution. Ultra-long ranging capabilities require the lidar to provide a high-power light source to ensure that sufficient echo signals can be received. High resolution requires the light sources in the emission array of the lidar to be densely arranged. The high-power light source and the dense arrangement of the emission array are likely to cause damage to the eyes of pedestrians on the road, thus limiting the ranging ability of the lidar.

[0028] Take the lidar's resolution in the vertical direction as an example.

[0029] To improve the scanning resolution of the lidar in the vertical direction, the light sources in the emission array of the lidar need to be closely stacked in the vertical direction, thus continuously reducing the vertical spacing between the light sources (i.e., transmitters) in the emission array. However, the dense arrangement between the light sources will cause a sharp decrease in the eye safety threshold. In addition, when the human eye observes an infinite distance, the lens will focus the incident pupil beam on the retina, forming a light spot on the retina, and the characteristics of the light spot are consistent with the arrangement characteristics of the light sources.

[0030] For example, since the maximum pupil diameter of the human eye is about 7 mm, according to the evaluation conditions of IEC 60825-1, as the distance changes (varying between 100 and 2000 mm), the acceptance angle of the human eye gradually decreases. At a distance of 100 mm, the acceptance angle is 4 degrees, and only the emission beams of some channels enter the human eye among all channels. Based on the maximum pupil diameter and acceptance angle of the human eye, for the spot arrangement designed for eye safety, only 4 to 6 spots need to be considered in the vertical direction. The light sources are vertically densely stacked, and there is mutual thermal influence in space between the corresponding formed spots, thus forming a more serious thermal effect and causing greater damage to the retina. In order not to change the angular resolution in the vertical direction, the emission time of each emitter in the emission array can be adjusted to form distributed spots, thereby reducing the coupling of thermal effects.

[0031] It can be understood that the emitters included in the emission array can be Vertical-Cavity Surface-Emitting Lasers (VCSELs for short), or Edge Emitting Lasers (EELs for short). The type of emitter is not restricted in this embodiment. It can be understood that on the basis of determining the type of emitter, the wavelength of the emitter is in the mid- to long-wavelength band (such as 905 nm, 940 nm), and preferably an emission and reception device with a longer wavelength can effectively improve the eye safety threshold.

[0032] For example, Figure 1 in (a) shows the way that the spot array of the same emission is arranged in a row, and the spot array of the same emission is adjusted to Figure 1 the way shown in (b) of Figure 1 arranged in 4 rows, or adjusted to be arranged in 2 rows as shown in (c) of Figure 1 or (d) of

[0033] According to IEC 60825-1, the coupling of the thermal effect of the spot imaging on the retina can be described by the opposing angle. Under the irradiation of repetitive pulses for a long time, the corresponding long-term opposing angle is expressed as

[0034]

[0035] Under the irradiation of repetitive pulses for a short time, the corresponding short-term opposing angle is expressed as

[0036]

[0037] where γ x , γ y are the acceptance angles in the x and y directions respectively, AE and AEL are the reachable transmitted energy and the limit of reachable transmitted energy respectively, where the calculation formula of AEL is provided by IEC 60825-1, C6 is the correction factor related to the opposite angle, T2 is the pulse duration divergence time for a long time, and t is the pulse duration emission time for a short pulse.

[0038] According to the long-time opposite angle formula and the short-time opposite angle formula, the condition to avoid thermal effect coupling is to make the long-time opposite angle formula equal to the short-time opposite angle formula.

[0039] It can be understood that the single-pulse time interval is often less than 625 μs. In order to make the long-time opposite angle formula equal to the short-time opposite angle formula, the light spot needs to satisfy the limit of the maximum angular distribution.

[0040] The maximum angular distribution of light spots with different shapes or combinations of light spots can be expressed as the average value of the sum of the length and width of the area where the light spot or the combination of light spots is located. For example, as Figure 2 shown, the shape of the light spot is rectangular, and the length and width of the rectangle are a and b respectively, then the maximum angular distribution of the light spot is (a + b) / 2.

[0041] If the light spot is circular, the maximum angular distribution of the light spot is the average value of the sum of the length and width of the circumscribed rectangle of the light spot.

[0042] The present application provides a lidar, including a transmitting array. The laser pulses emitted by the transmitting array form a light spot array at a preset distance, where the preset distance is within the detection area of the lidar. It can be understood that the light spot array may include array light spots in the first direction or array light spots in the second direction. It can be understood that when the light spot array includes light spots in the first direction, the angular interval between adjacent light spots in the first direction is less than the first angle, and the maximum angular distribution of the light spot is less than the first preset value. It can be understood that when the light spot array includes light spots in the second direction, the angular interval between adjacent light spots in the second direction is less than the second angle, and the maximum angular distribution of the light spot is less than the first preset value.

[0043] In another embodiment, the present application provides a lidar, including a transmitting array. The laser pulses emitted by the transmitting array form a spot array at a preset distance. Wherein, the preset distance is within the detection area of the lidar. In the spot array, the angular interval between adjacent spots in the first direction is less than a first angle, and the angular interval between adjacent spots in the second direction is less than a second angle. The first angle is determined according to a first resolution, and the second angle is determined according to a second resolution. Therefore, the lidar meets the requirements of the first resolution in the first direction and the second resolution in the second direction. Wherein, as an optional implementation manner, the first direction is perpendicular to the second direction, and the first direction and the second direction can be the vertical direction and the horizontal direction respectively. The maximum angular distribution of the spots in the spot array is less than a first preset value. Wherein, the first preset value can be 5 mrad, and the first preset value is determined according to the condition that the opposite angles in a short time (a first duration) and the opposite angles in a long time (a second duration) are equal. Wherein, the second duration is greater than 10 seconds, and the first duration is less than 625 microseconds. Since the maximum angular distribution of the spots is less than the first preset value, the spot array will not cause damage to the human eye, and the eye safety of the lidar can be ensured. Therefore, the lidar provided by the present application can meet the eye safety while meeting the requirements of the ultra-long ranging ability and high resolution of the lidar.

[0044] Wherein, the shape of the spots can be different shapes. For example, Figure 3 in (a) is a square spot, Figure 3 in (b) is a rectangular spot. Different shaped spots can ensure eye safety when the maximum angular distribution is less than the first preset value.

[0045] In one embodiment, the angular interval between adjacent spots in the first direction is less than a third angle, and / or the angular interval between adjacent spots in the second direction is less than a third angle. The third angle is greater than the first angle and greater than the second angle. Wherein, the third angle is the critical condition for taking two adjacent spots as a spot combination. The angular interval between adjacent spots in the first direction being less than the third angle means that the interval between adjacent spots in the first direction is relatively close, and the angular interval between adjacent spots in the second direction being less than the third angle means that the interval between adjacent spots in the second direction is relatively close. While the spot array meets the resolution in the first direction and / or the second direction, the maximum angular distribution of the spot combination formed by adjacent spots is less than the first preset value, and the maximum angular distribution of the spot combination is determined according to the side length of the area where the spot combination is located. Exemplarily, taking two spots with a relatively close distance as a whole, the maximum angular distribution of the two spots is the average value of the side lengths of the area where the two adjacent spots are located. For example, as Figure 4As shown, the side lengths of the two light spots are a and b respectively, then the maximum angular distribution of the two light spots is (a + 2b) / 2. The maximum angular distribution of the two light spots is less than the first preset value, which can ensure eye safety when the distance between the light spots is relatively close.

[0046] In another embodiment, the angular interval between adjacent light spots in the first direction is greater than or equal to the third angle, and / or the angular interval between adjacent light spots in the second direction is greater than or equal to the third angle, indicating that the adjacent light spots are relatively far apart in the first direction and / or the second direction. Then the maximum angular distribution of a single light spot is less than the first preset value, and the maximum angular distribution of a single light spot is determined according to the side length of the area where the single light spot is located.

[0047] It can be understood that, as another optional implementation manner of the present application, when the angular interval between adjacent light spots in the first direction is less than the third angle, or the angular interval between adjacent light spots in the second direction is less than the third angle, but the maximum angular distribution of the light spot combination formed by the adjacent light spots is greater than the first preset value, the adjacent light spots can be controlled to be emitted at intervals to reduce the maximum angular distribution of the light spots emitted in the same time, and at the same time, the angular resolution in the first direction or the second direction of the radar can be achieved through multiple emissions.

[0048] As Figure 5 shown in (a) of y Δθ x = 2Δθ, the minimum value of Δθ Figure 5 is 2Δθ. The light spot arrangement greater than 2Δθ in the horizontal direction can effectively reduce the thermal effect coupling of multiple light spots, thereby meeting the evaluation requirements of eye safety. As x shown in (b) of Figure 5 the distance between two adjacent light spots in the vertical direction is relatively close, and the maximum angular distribution of the two adjacent light spots needs to meet the requirements of the maximum angular distribution. Through the design of the combined light spots, the light spot energy distribution is made more concentrated, and the minimum value of Δθ

[0049] In one embodiment, the lidar includes a transmitting array and a receiving array corresponding to the transmitting array. The light spots in the light spot array are the light spots formed by the laser pulses emitted by the transmitting array in the same emission, and the light spots in the light spot array correspond one-to-one with the transmitters in the transmitting array. Among them, the light spots in the light spot array can be formed by the laser pulses emitted by all the transmitters in the transmitting array, or can be formed by the laser pulses emitted by some transmitters. Among the light spots formed by the emission of the transmitting array, the angular interval between adjacent light spots in the first direction is less than the first angle, the angular interval between adjacent light spots in the second direction is less than the second angle, and the maximum angular distribution of the light spots in the light spot array is less than the first preset value.

[0050] Among them, it can be understood that the angular interval between adjacent light spots in the first direction can be the angular interval between the light spots formed in the same emission, or can be the angular interval between the light spots formed in different emissions in the first direction; the angular interval between adjacent light spots in the second direction can be the angular interval between the light spots formed in the same emission, or can be the angular interval between the light spots formed in different emissions in the second direction. It can be understood that when the time interval between two adjacent emissions is less than the preset time interval value, the maximum angular distribution of the light spots is the maximum angular distribution of the light spots formed by two adjacent emissions. It can be understood that when the time interval between two adjacent emissions is greater than the preset time interval value, the maximum angular distribution of the light spots is the maximum angular distribution of the light spots formed in the same emission. Among them, the preset time interval value can be, for example, 5 us.

[0051] For example, the light spots in the light spot array are the light spots formed by the laser pulses emitted by the transmitting array continuously for multiple times, and the time interval between two adjacent laser pulse emissions is less than the preset time interval value. To ensure eye safety and resolution requirements, the angular interval between adjacent light spots in the first direction is less than the first angle, the angular interval between adjacent light spots in the second direction is less than the second angle, and the maximum angular distribution of the light spots in the light spot array formed by two adjacent emissions is less than the first preset value. It can be understood that if the time interval between two adjacent laser pulse emissions is greater than the preset time interval value, to ensure eye safety and resolution requirements, the angular interval between adjacent light spots in the first direction is less than the first angle, the angular interval between adjacent light spots in the second direction is less than the second angle, and the maximum angular distribution of the light spots in the light spot array formed in the same emission is less than the first preset value.

[0052] In one embodiment, the lidar further includes a scanning device. The laser pulses incident on the scanning device are reflected by the scanning device and then change the emission direction, thereby forming light spots at different positions in the detection area. The scanning device changes the light spot distribution in the first direction. Optionally, the scanning device can also change the light spot distribution in the second direction. As another alternative embodiment, the scanning device can also change the light spot distributions in the first direction and the second direction simultaneously. Among them, the scanning device can be a rotating mirror, a one-dimensional galvanometer, a two-dimensional galvanometer, a rotating platform, etc. The present application does not limit the specific form of the scanning device. It can be understood that when the scanning device changes the light spot distributions in the first direction and the second direction simultaneously, the scanning device in the first direction and the scanning device in the second direction can be the same device. For example, the scanning device can be a two-dimensional galvanometer. Optionally, the scanning device in the first direction and the scanning device in the second direction can also be different devices. When the scanning device in the first direction and the scanning device in the second direction are different devices, the scanning device in the first direction and the scanning device in the second direction can be the same or different. For example, the scanning device in the first direction can be a first rotating mirror, and the scanning device in the second direction can be a second rotating mirror. As another alternative embodiment, the scanning device in the first direction can be a galvanometer, and the scanning device in the second direction can be a rotating mirror. The present application does not make a unique limitation on this. When the lidar includes a scanning device and the emission interval of the lidar emission device is determined, the angular interval between the light spots formed by two adjacent emissions in the first direction can be controlled by controlling the rotation speed of the scanning device. For example, when there are scanning devices in both the first direction and the second direction of the lidar, after the adjacent two emission intervals of the lidar are determined, the rotation speed of the scanning device in the first direction is less than a first preset speed and greater than a second preset speed, and the rotation speed of the scanning device in the second direction is less than a third preset speed and greater than a fourth preset speed, so that the angular interval between the light spots formed by the laser beams of two adjacent emissions in the first direction is less than a first angle, and at the same time, the angular interval between the light spots formed by the laser beams of two adjacent emissions in the second direction is less than a second angle, and the maximum angular distribution of the light spots satisfies a first preset value. It can be understood that the first preset speed and the third preset speed can be set according to the detection requirements (resolution requirements) of the lidar, and the second preset speed and the fourth preset speed are set according to the lidar emission frequency and the human eye safety requirements. Therefore, when the emission time interval is determined, by controlling the rotation speed of the scanning device, the light spots formed by the laser pulses of two adjacent emissions can meet the requirements of the first resolution and the second resolution while achieving human eye safety.

[0053] In other embodiments, it is also possible to control the step size or step time of the scanning device in the first direction, so that the angular interval of the spots formed by the laser beams emitted twice adjacent to each other in the first direction is less than the first angle, and / or control the step size or step time of the scanning device in the second direction, so that the angular interval of the spots formed by the laser beams emitted twice adjacent to each other in the second direction is less than the second angle.

[0054] The step time is equal to the time corresponding to two adjacent emissions. It can be understood that by controlling the step size of the scanning device per unit time, it is possible to reduce thermal accumulation while meeting the resolution requirements. For example, when the detection requirements (i.e., resolution requirements) are met, by increasing the step size of the scanning device per unit time or lengthening the time interval between two scans, the thermal accumulation caused by two adjacent emissions can be reduced while ensuring the angular interval between the spots.

[0055] In one embodiment, the lidar further includes an output lens assembly. The laser beam emitted by the emitter is emitted through the output lens assembly. The focal length of the output lens assembly is greater than a second preset value, so that the diameter of the spot formed by the laser beam within a preset distance is greater than a first preset value, thereby ensuring eye safety.

[0056] In one embodiment, the lidar further includes a beam adjustment module. The beam adjustment module includes a spot adjustment component. The laser beam emitted by the emitter is emitted through the spot adjustment component, so that the diameter of the spot formed by the laser beam within a first preset distance is greater than a first preset value, thereby ensuring eye safety.

[0057] In one embodiment, the beam adjustment module further includes a divergence angle reduction component. The laser beam emitted by the spot adjustment component is emitted through the divergence angle reduction component. The divergence angle reduction component is used to reduce the divergence angle of the laser beam at a distance greater than a second preset distance. The second preset distance refers to the far-field range of the laser beam (for example, the far-field range can be defined as a range greater than ten meters, where the specific value of the far-field range is not limited in this application), so as to avoid the divergence angle of the laser beam being too large within the far-field range and affecting the resolution. Among them, while reducing the divergence angle of the laser beam at a distance greater than the second preset distance, it is necessary to ensure that the diameter of the spot formed at the Gaussian beam waist of the laser beam is greater than a first preset value to ensure eye safety.

[0058] In the case where the lidar includes a scanning device, the emission frequency of the laser pulses in the emission array is less than a first preset frequency and greater than a second preset frequency, so as to reduce the interval between the spots formed by two adjacent laser pulses during the rotation of the scanning device, and make the angular interval of the spots formed by two adjacent laser beams in the first direction less than a first angle, and the angular interval of the spots formed by two adjacent laser beams in the second direction less than a second angle, while meeting the requirements of eye-safe thermal accumulation. Among them, the first preset frequency is related to the thermal accumulation of eye safety within a preset time, and the second preset frequency is related to the resolution of the lidar.

[0059] When eye safety is satisfied, the opposing angle of the first duration is equal to the opposing angle of the second duration. In one embodiment, the opposing angle of each spot in the first duration is less than a first threshold, that is, the opposing angle in the second duration is less than the first threshold. The limit of the maximum angle distribution is determined according to the opposing angle, and then the way of emitting laser pulses by the lidar is adjusted to obtain a spot array that meets eye safety.

[0060] When the emission interval of the laser pulses is short, thermal accumulation will occur in the continuously emitted laser pulses. In one embodiment, the emission interval of the laser pulses is greater than a first interval, and the opposing angle of the first duration is determined according to the thermal accumulation of 1 laser pulse. The first interval can be 5 us. The emission interval of the laser pulses is less than the first interval and greater than a second interval, and the opposing angle of the first duration is determined according to the thermal accumulation of 2 laser pulses. The second interval can be 2.5 us. The emission interval of the laser pulses is less than the second interval, and the opposing angle of the first duration is determined according to the thermal accumulation of 3 laser pulses. In the case where the emission interval of the laser pulses is small, the opposing angle is determined according to the thermal accumulation of the continuously emitted laser pulses, and then the limit conditions of the angular interval of each spot in the spot array are determined, so that the lidar can meet eye safety.

[0061] In another embodiment, if the emission interval of the laser pulses is less than the second interval, the spot array includes spots formed by continuously emitting laser pulses multiple times. In the spot array, the maximum angle distribution of the spots is less than a first preset value, so that the lidar can meet eye safety.

[0062] Lasers in the 400 - 1400nm wavelength band can pass through the anterior eye media (such as the cornea, aqueous humor, and lens), and through the lens effect of the lens, a concentrated light spot is formed on the retina. Thermal accumulation occurs under single or long - term irradiation of laser pulses. High - power and dense pulsed light spots are prone to excessive thermal accumulation, which can damage the retina. Lasers of different wavelengths are absorbed by the anterior eye media with different energies. Visible light in the 450 - 850nm band passes through the anterior eye media with a very high transmittance, while the transmittance of laser pulses in the 900 - 980nm near - infrared band gradually decreases. According to the wavelength - related correction factor C4 in the IEC60825 - 1 standard, it can be expressed as

[0063] C4 = 10 0.002(λ-700)

[0064] where λ is the wavelength. In the 900 - 980nm band, the longer the wavelength, the larger the value of C4, and the higher the corresponding human - eye safety threshold. In the embodiments of the present application, the wavelength of each laser pulse is in the 900 - 980nm near - infrared band and is greater than the first preset value. That is, while meeting the detection requirements, the wavelength of the laser pulse is increased as much as possible, which can reduce the pupil - entrance energy and improve safety when the lidar is detecting.

[0065] As Figure 6 shown, a lidar provided by an embodiment of the present application includes:

[0066] A laser - emitting module 61 for emitting a laser beam;

[0067] A beam - adjusting module 62 for adjusting the laser beam so that the diameter of the light spot formed by the laser beam within the first preset distance is greater than the first preset value;

[0068] The laser - emitting module 61 needs to satisfy that the angular interval between the emission channels of adjacent emitters for emitting the laser beam is greater than a preset angle, and / or the time interval between adjacent emissions of the laser beam is greater than a preset duration.

[0069] Among them, the beam - adjusting module 62 includes an exit - lens assembly, and the focal length of the exit - lens assembly is greater than a second preset value, so that the diameter of the light spot formed by the laser beam within the first preset distance is greater than the first preset value.

[0070] Among them, the beam - adjusting module 62 may further include a light - spot adjusting component for increasing the divergence angle of the laser beam so that the diameter of the light spot formed by the laser beam within the first preset distance is greater than the first preset value.

[0071] The beam - adjusting module 62 includes a divergence - angle reducing component for reducing the divergence angle of the laser beam at a distance greater than the second preset distance.

[0072] The beam adjustment module 62 further includes a scanning device, which is used to access the detection laser, emit the detection laser to a preset area, scan the preset area using a preset scanning mode corresponding to the preset area, and the scanning device is also used to receive the echo laser reflected from the preset area and output the echo laser; by setting the scanning step and scanning speed of the scanning device, the lidar can further improve the detection resolution of the lidar while meeting the requirements of eye safety, and meet the detection requirements of the lidar.

[0073] The lidar further includes a receiving and detecting module 63, which is used to receive the echo laser and convert it into an electrical signal;

[0074] The lidar further includes a signal acquisition and processing module 64, which is used to acquire the electrical signal and process the electrical signal to obtain the detection information of the preset area.

[0075] In one embodiment, the lidar further includes a zoom system. The laser pulse is emitted to the detection area through the zoom system. The zoom system is used to increase the size of the light spot when it is determined that the distance of the object to be measured in the detection area is less than the first distance, so as to reduce the energy of the laser pulse entering the human eye and improve eye safety. When it is determined that the distance of the object to be measured in the detection area is greater than the second distance, the size of the light spot is reduced, so that the energy of the laser pulse is more concentrated, so as to enhance the energy of the echo signal received during long-distance detection.

[0076] For example, as Figure 7 shown in (a), the zoom system includes two fixedly placed convex lenses 71 and convex lens 72 and a concave lens 73 with an adjustable position. In the scenario of short-distance detection, the position of the concave lens 73 is adjusted by an electric drive unit to form an expanded beam light spot in the detection area, so as to reduce the energy entering the human eye and improve eye safety. As Figure 7 shown in (b), in the scenario of long-distance detection such as on a highway, the position of the concave lens 73 is adjusted by an electric drive unit to form a converging light spot in the detection area, so that the energy is more concentrated.

[0077] In one embodiment, the lidar further includes a power adjustment device, which is used to reduce the power of the laser pulse when it is determined that the distance of the object to be measured in the detection area is less than the first distance, so as to reduce the energy of the laser pulse entering the human eye, and thus can improve eye safety.

[0078] In the above embodiments, by adjusting each component of the lidar, in the spot array formed by the lidar within the detection area, the angular interval between adjacent spots in the first direction is less than the first angle, the angular interval between adjacent spots in the second direction is less than the second angle, and the maximum angular distribution of each spot in the spot array is less than the first preset value. Thus, while meeting the ranging requirements and resolution requirements of the lidar, the mutual thermal influence between spots can be reduced, and the thermal effect coupling can be decreased. Furthermore, the eye safety of the lidar can be improved.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A lidar, characterized in that, The lidar includes a transmitting array, and laser pulses emitted by the transmitting array form a spot array at a preset distance; in the spot array, the angular interval between adjacent spots in the first direction is less than a first angle, and the angular interval between adjacent spots in the second direction is less than a second angle; the maximum angular distribution of the spots in the spot array is less than a first preset value; the first angle is determined according to a first resolution, and the second angle is determined according to a second resolution.

2. The lidar according to claim 1, wherein, The angular interval between adjacent spots in the first direction is less than a third angle, or the angular interval between adjacent spots in the second direction is less than the third angle, the third angle is greater than the first angle and greater than the second angle, and the maximum angular distribution of the spot combination formed by adjacent spots is less than the first preset value, and the maximum angular distribution of the spot combination is determined according to the side length of the area where the spot combination is located.

3. The lidar according to claim 1, characterized in that, The angular interval between adjacent spots in the first direction is greater than or equal to a third angle, and the angular interval between adjacent spots in the second direction is greater than or equal to the third angle, the third angle is greater than the first angle and greater than the second angle, and the maximum angular distribution of a single spot is less than the first preset value, and the maximum angular distribution of a single spot is determined according to the side length of the area where the single spot is located.

4. The lidar according to claim 1, characterized in that, The spots in the spot array are the spots formed by the laser pulses emitted by the transmitting array at the same time, and the spots in the spot array correspond to the emitters in the transmitting array one by one; the angular interval between adjacent spots in the first direction is equal to the arrangement interval of the emitters in the first direction; the angular interval between adjacent spots in the second direction is equal to the arrangement interval of the emitters in the second direction.

5. The lidar according to claim 1, characterized in that, The lidar further includes a scanning device, the rotation speed of the scanning device in the first direction is less than a first preset speed, the rotation speed of the scanning device in the second direction is less than a second preset speed, and / or the emission frequency of the laser pulses is less than a preset frequency, so that the angular interval between the spots formed by two adjacent laser pulse emissions in the first direction is less than the first angle, and the angular interval between the spots formed by two adjacent laser pulse emissions in the second direction is less than the second angle.

6. The lidar according to any one of claims 1 to 5, characterized in that, The emission interval of the same laser pulse is greater than a first interval, and the opposite angle of the first duration is determined according to the thermal accumulation of 1 laser pulse.

7. The lidar according to any one of claims 1 to 5, characterized in that, The emission interval of the same laser pulse is less than the first interval and greater than a second interval, and the opposite angle of the first duration is determined according to the thermal accumulation of 2 laser pulses.

8. The lidar according to any one of claims 1 to 5, characterized in that, The emission interval of the same laser pulse is less than the second interval, and the opposite angle of the first duration is determined according to the thermal accumulation of 3 laser pulses.

9. The lidar according to any one of claims 1 to 5, characterized in that, The lidar further includes a zoom system, the laser pulses are emitted towards the detection area through the zoom system, and the zoom system is used to increase the size of the spots when it is determined that the distance of the object to be measured in the detection area is less than a first distance, and to reduce the size of the spots when it is determined that the distance of the object to be measured in the detection area is greater than a second distance.

10. The lidar according to claim 9, characterized in that, The lidar further includes a power adjustment device, and the power adjustment device is configured to reduce the power of the laser pulse when it is determined that the distance of the object to be measured in the detection area is less than the first distance.

11. The lidar according to claim 1, characterized in that, The wavelength of the laser pulse is in the near-infrared band, and the wavelength is greater than a first preset value.

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