CN212694031U - Laser radar system - Google Patents
Laser radar system Download PDFInfo
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- CN212694031U CN212694031U CN202021535301.1U CN202021535301U CN212694031U CN 212694031 U CN212694031 U CN 212694031U CN 202021535301 U CN202021535301 U CN 202021535301U CN 212694031 U CN212694031 U CN 212694031U
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Abstract
The utility model relates to a laser radar system, which comprises a light source module, a receiving lens, a detection module and a processing module; the light source module emits a laser beam; irradiating the laser beam to an object to be detected, and reflecting the laser beam by the object to be detected to form a reflected beam; the receiving lens receives the reflected light beam; the detection module comprises a photosensitive unit with a preset area, is arranged on a focal plane of the receiving lens or between the receiving lens and the focal plane, and detects the intensity of the reflected light beam to obtain an echo energy signal; the detection module also reduces the difference between a detected first echo energy signal and a detected second echo energy signal, wherein the first echo energy signal is an echo energy signal of an object to be detected within a preset distance of the receiving lens, and the second echo energy signal is an echo energy signal of the object to be detected outside the preset distance of the receiving lens; the processing module is electrically connected with the detection module and is used for processing the echo energy signal to obtain target information of the object to be detected.
Description
Technical Field
The utility model relates to a radar technical field, in particular to laser radar system.
Background
When the laser radar measures the object information, the object to be measured is illuminated by laser, reflected light carrying the object information is received by the receiving lens, and the detector is used for converting optical signals into electric signals and reading and recording the electric signals by the digital circuit.
The echo energy of a near object detected by a conventional laser radar detector is too different from that of a far object, and when the echo energy of the far object is detected, the detected echo energy of the near object may be saturated, and even the detector is damaged.
SUMMERY OF THE UTILITY MODEL
Based on this, it is necessary to provide a laser radar system to solve the problem that the echo energy of a near object detected by a conventional laser radar detector is too different from the echo energy of a far object.
A lidar system comprising:
the light source module is used for emitting laser beams;
the laser beam irradiates an object to be detected, and the laser beam is reflected by the object to be detected to form a reflected beam;
the receiving lens is used for receiving the reflected light beam;
the detection module comprises a photosensitive unit with a preset area, is arranged on a focal plane of the receiving lens or between the receiving lens and the focal plane, and is used for detecting the intensity of the reflected light beam to obtain an echo energy signal;
the detection module is further configured to reduce a difference between a detected first echo energy signal and a detected second echo energy signal, where the first echo energy signal is an echo energy signal of an object to be detected located within a preset distance from the receiving lens, and the second echo energy signal is an echo energy signal of the object to be detected located outside the preset distance from the receiving lens;
and the processing module is electrically connected with the detection module and is used for processing the echo energy signal to obtain the target information of the object to be detected.
In the laser radar system, the detection module with the photosensitive unit with the preset area is arranged on the focal plane of the receiving lens or between the receiving lens and the focal plane, the detection module can detect most of echo energy of an object to be detected which is positioned outside the preset distance of the receiving lens, namely a second echo energy signal, the detection module can only detect a small part of echo energy of the object to be detected which is positioned inside the preset distance of the receiving lens, namely a first echo energy signal, so that the difference between the detected first echo energy signal and the second echo energy signal can be reduced, when the detection module can detect the echo energy of an object at a far distance, namely the second echo energy signal can be detected, the detection module detects the echo energy of the object at a near position to be saturated, and the detection module can be prevented from being damaged.
In one embodiment, the predetermined area is
Where ω is the angle of view of the receiving lens, and f is the equivalent focal length of the receiving lens.
In one embodiment, the target information includes reflectivity, distance, position, speed, posture and shape of the object to be measured.
In one embodiment, the light source module includes:
a laser for emitting a laser beam; and
and the lens unit is arranged on the light path of the laser beam and is used for shaping and collimating the laser beam.
In one embodiment, the receiving lens is further configured to perform convergence and shaping processing on the reflected light beam, so that the spot size of the reflected light beam is adapted to a photosensitive unit with a preset area of the detection module.
In one embodiment, the receiving lens includes a converging mirror and a shaping mirror, the converging mirror is used for converging the reflected light beams, and the shaping mirror is used for respectively shaping the converged reflected light beams.
In one embodiment, the detection module is one of an avalanche photodiode, a charge coupled device, a complementary metal oxide semiconductor, and a multi-pixel photon counter.
In one embodiment, the detection module includes a filter, and the filter is configured to perform filtering processing on the echo energy signal and transmit the filtered echo energy signal to the processing module.
In one embodiment, the receiving lens comprises a single lens or a cemented lens or a lens group.
In one embodiment, the single lens, the cemented lens and/or the lens group are made of metamaterials.
Drawings
FIG. 1 is a schematic diagram of a lidar system in one embodiment provided herein;
FIG. 2 is a schematic diagram of a lidar system in one embodiment provided herein;
FIG. 3 is a schematic diagram of a lidar system in one embodiment provided herein;
fig. 4 is a schematic position diagram of a first object to be detected, a second object to be detected, a receiving lens and a detection module in an embodiment of the disclosure.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
When the laser sensor emits a narrow beam to the scattering ground object, the area of a light spot irradiated by the beam on the scattering ground object can be approximately given by the following formula:
wherein A istaserIs the spot area, R is the laser detection distance, i.e. the distance between the lidar system and the object to be measured, betatThe beam width corresponds to the divergence angle of the laser light.
Therefore, the energy density of the laser beam irradiated on the scattering ground object is:
wherein S issFor the energy density of the laser beam impinging on the scattering ground object, PtEnergy is emitted for the laser.
Since the laser wavelength is generally much smaller than the size of the scattering ground object, the effective area irradiated on the ground object can be simplified into the projection area of the scattering ground object, part of the energy projected onto the scattering ground object is absorbed, and the rest is scattered in various directions, so that the scattering energy is:
wherein, PsFor scattered energy, ρ is the reflectance, AsIs the illuminated area of the scattering ground object.
Assuming that the incident laser light is uniformly scattered into a cone with a solid angle Ω, if the receiver can receive energy, the receiver receives energy density SrComprises the following steps:
energy P entering the receiverrComprises the following steps:
wherein D isrIs the receiver optical aperture.
In conventional lidar systems, the receive field of view is generally greater than or equal to the transmit field of view, when
Approximately 1, the energy falling on the receiver can be approximated as:
from the above equation, it can be determined that, for a fixed lidar system, the transmitting power of the laser is unchanged, the aperture of the receiving lens is unchanged, and if an object to be measured with the same reflectivity is measured, the energy detected by the detector is in inverse square relation to R. For example, objects with the same reflectivity are respectively located at 0.1m (meter) and 100m, the echo energy of the object located at 0.1m detected by the detector is 10 of the echo energy of the object located at 100m detected by the detector6Therefore, when the detector can detect the echo energy of the object to be detected at a far position, the echo energy of the object to be detected at a near position detected by the detector may be saturated, and even the detector may be damaged. The receiving device comprises a receiving lens and a detector.
Referring to fig. 1, an embodiment of the present application provides a laser radar system, which includes a light source module 10, a receiving lens 20, a detection module 30, and a processing module 40. The light source module 10 is used to emit a laser beam. The laser beams are respectively irradiated to the object 100 to be measured, and the laser beams are reflected by the object 100 to be measured to form reflected beams. The receiving lens 20 is used for receiving the reflected light beam. The detection module 30 includes a photosensitive unit with a preset area, and the detection module 30 is disposed on a focal plane of the receiving lens 20 or between the receiving lens 20 and the focal plane, and is configured to detect the intensity of the reflected light beam to obtain an echo energy signal. The detection module 30 is further configured to reduce a difference between a detected first echo energy signal and a detected second echo energy signal, where the first echo energy signal is an echo energy signal of the object 100 to be measured located within a preset distance of the receiving lens 20, and the second echo energy signal is an echo energy signal of the object 100 to be measured located outside the preset distance of the receiving lens 20. The processing module 40 is electrically connected to the detecting module 30, and the processing module 40 is configured to process the echo energy signal to obtain target information of the object 100 to be detected.
The object to be measured 100 includes a first object to be measured 101 and a second object to be measured 102. All objects 100 to be measured within a predetermined distance from the receiving lens 20 are first objects 101 to be measured, and all objects 100 to be measured outside the predetermined distance from the receiving lens 20 are second objects 102 to be measured.
Within the field of view of the receiving lens 20, as the object 100 gradually moves away from the receiving lens 20, the image plane of the object 100 gradually approaches from far to the focal plane, and the size of the image gradually decreases, and when the image of the object 100 is located at the focal plane of the receiving lens 20, the size of the image of the object 100 is as follows
Therefore, the detection module 30 having the light sensing unit with the predetermined area is disposed on the focal plane of the receiving lens 20 or between the receiving lens 20 and the focal plane, the detection module 30 can detect most of the echo energy reflected by the second object to be detected 102, i.e. the second echo energy signal, and the detection module 30 can only detect a small portion of the echo energy reflected by the first object to be detected 101, i.e. the first echo energy signal, so that the difference between the first echo energy signal and the second echo energy signal detected by the detection module 30 can be reduced, so that when the detection module 30 can detect the echo energy of a far object, i.e. can detect the second echo energy signal, the detection module 30 detects that the echo energy of a near object is saturated, and the detection module 30 can be prevented from being damaged.
Referring to fig. 2, in one embodiment, the light source module 10 includes a laser 11 and a lens unit 12. The laser 11 is used to emit a laser beam. The lens unit 12 is disposed on the optical path of the laser beam, and is configured to shape and collimate the laser beam. The lens unit 12 may be a lens assembly, a single lens with a single aperture, a lens group, a plurality of cylindrical mirrors, or a plurality of spherical mirrors. Since the laser beam emitted by the laser 11 may be relatively divergent, the lens unit 12 performs spatial shaping, and thus, an efficient collimating and shaping effect can be achieved. Thus, the lens unit 12 projects the laser beam after the shaping and collimating processes onto the object 100 to be measured.
In one embodiment, the receiving lens 20 is further configured to converge and shape the reflected light beam to adapt the spot size of the reflected light beam to the photosensitive unit with a predetermined area of the detecting module 30.
Referring to fig. 3, in one embodiment, the receiving lens 20 includes a converging mirror 21 and a shaping mirror 22, the converging mirror 21 is used for converging the reflected light beams, and the shaping mirror 22 is used for respectively shaping the converged reflected light beams. In this embodiment, the converging mirror 21 converges the reflected light beam, and the converged reflected light beam is shaped by the shaping mirror 22, so that the spot size of the reflected light beam is adapted to the photosensitive unit of the preset area of the detection module 30, and the reflected light beam directly irradiates the photosensitive unit of the detection module 30 in the form of an approximate plane wave, so as to eliminate the difference of pixel points caused by different detection areas and different illumination intensities, thereby improving the imaging quality.
In one embodiment, the receiving lens 20 includes a single lens for receiving the reflected light beam, and the reflected light beam is incident to the detecting module 30 after passing through the single lens. Alternatively, the receiving lens 20 includes a cemented lens for receiving the reflected light beam, and the reflected light beam is incident to the detecting module 30 through the cemented lens. Alternatively, the receiving lens 20 includes a lens set, and the lens set includes a plurality of lenses, which are sequentially disposed on the light path transmitted by the reflected light beam according to a predetermined sequence, and are used for receiving the reflected light beam, and the reflected light beam is incident to the detecting module 30 through the lens set. The einzel lens, the cemented lens, and/or the lens groups may be made of metamaterials. The single lens, the cemented lens and the lens group can be combined at will.
In one embodiment, the predetermined area is
Where ω is the angle of view of the receiving lens 20, f is the equivalent focal length of the receiving lens 20, and the size of the image of the object 100 at the focal plane of the receiving lens 20 is
Thus, the area of the light sensing unit of the detection module 30 is
And is disposed at a focal plane of the receiving lens 20, the detecting module 30 can detect all the echo energy of the object 100 to be detected imaged at the focal plane, and can reduce the difference between the first echo energy signal and the second echo energy signal detected by the detecting module 30, and the area of the light sensing unit of the detecting module 30 is set as
The photosensitive unit of the detection module 30 can have a high utilization rate, and waste is avoided.
Referring to fig. 4, in fig. 4, the first object 101 to be measured is located within a predetermined distance of the receiving lens 20, i.e. a near object relative to the receiving lens 20, and the second object 102 to be measured is located outside the predetermined distance of the receiving lens 20, i.e. a far object relative to the receiving lens 20, the near object forms a first real image 201 through the receiving lens 20, and the far object forms a second real image 202 through the receiving lens 20. Within the field of view of the receiving lens 20, as the object 100 gradually moves away from the receiving lens 20, the image plane of the object 100 gradually gets closer from far to the focal plane, and the size of the image gradually decreases, as shown in the first real image 201 and the second real image 202. The second real image 202 is located at the focal plane of the receiving lens 20 and the size of the second real image 202 is
When it is exposed to lightThe area of the unit is greater than or equal to
The detection module 30 is disposed at a focal plane of the receiving lens 20, and the detection module 30 can detect all the echo energy reflected by the second object to be detected 102, and can detect only a small portion of the echo energy reflected by the first object to be detected 101, so as to reduce a difference between the first echo energy signal and the second echo energy signal detected by the detection module 30. When the area of the photosensitive unit is larger than or equal to
The detection module 30 is disposed between the receiving lens 20 and the focal plane of the receiving lens 20, and the detection module 30 can detect most of the echo energy reflected by the second object to be measured 102, and can only detect a small portion of the echo energy reflected by the first object to be measured 101, so that the difference between the first echo energy signal and the second echo energy signal detected by the detection module 30 can be reduced.
In one embodiment, the detection module 30 includes a filter for filtering the echo energy signal and transmitting the filtered echo energy signal to the processing module 40. It can be understood that the echo energy signal output by the detection module 30 includes a common-mode dc component and a noise signal, and therefore, the echo energy signal needs to be filtered by a filter to remove the common-mode dc component and the high-frequency signal in the echo energy signal, so as to improve the signal-to-noise ratio of the echo energy signal.
In one embodiment, the filter is a passive filter. It can be understood that the passive filter, also called as LC filter, is a filter circuit formed by using the combination design of inductor, capacitor and resistor, can filter out a certain or multiple harmonics, and has the advantages of simple structure, low cost, high operation reliability, low operation cost, etc., so the passive filter adopted in the embodiment is beneficial to simplifying the structural design of the laser radar system and reducing the production cost. It is to be understood that the filter may also be an active filter, and the present embodiment is not limited to the type of the filter.
The detection module 30 may be one of an avalanche photodiode, a charge coupled device, a complementary metal oxide semiconductor, and a multi-pixel photon counter. The avalanche photodiode can amplify the echo energy signal to improve the sensitivity of detection. The charge coupled device, the avalanche photodiode and the complementary metal oxide semiconductor sensor have a function of converting an optical signal into an electrical signal, so that the charge coupled device, the avalanche photodiode and the complementary metal oxide semiconductor sensor can be used as a detector to convert a reflected light beam into an echo energy signal. In addition, other devices having the function of converting the optical signal into the electrical signal can be used as the detection module 30, and the utility model discloses do not specifically limit the implementation of the detection module 30.
The target information includes the reflectivity, distance, position, speed, attitude, and shape of the object 100 to be measured. The processing module 40 may convert the echo energy signal into a digital signal, and further calculate target information of the object 100 to be detected, so as to detect, track and identify the object 100 to be detected. In one embodiment, the processing module 40 may be a micro-control unit or a computer.
The laser radar system provided in the above embodiment, the detection module having the light sensing unit with the preset area is disposed on the focal plane of the receiving lens or between the receiving lens and the focal plane, the detection module can detect most of the echo energy of the object to be detected located outside the preset distance of the receiving lens, that is, the second echo energy signal, the detection module can only detect a small portion of the echo energy of the object to be detected located within the preset distance of the receiving lens, that is, the first echo energy signal, so that the difference between the detected first echo energy signal and the detected second echo energy signal can be reduced, when the detection module can detect the echo energy of the object far away, that is, when the detection module can detect the second echo energy signal, the detection module detects that the echo energy of the object near the detecting module is not saturated, and can prevent the detection module from being damaged.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A lidar system, comprising:
the light source module is used for emitting laser beams;
the laser beam irradiates an object to be detected, and the laser beam is reflected by the object to be detected to form a reflected beam;
the receiving lens is used for receiving the reflected light beam;
the detection module comprises a photosensitive unit with a preset area, is arranged on a focal plane of the receiving lens or between the receiving lens and the focal plane, and is used for detecting the intensity of the reflected light beam to obtain an echo energy signal;
the detection module is further configured to reduce a difference between a detected first echo energy signal and a detected second echo energy signal, where the first echo energy signal is an echo energy signal of an object to be detected located within a preset distance from the receiving lens, and the second echo energy signal is an echo energy signal of the object to be detected located outside the preset distance from the receiving lens;
and the processing module is electrically connected with the detection module and is used for processing the echo energy signal to obtain the target information of the object to be detected.
2. The lidar system of claim 1, wherein the predetermined area is
Where ω is the angle of view of the receiving lens, and f is the equivalent focal length of the receiving lens.
3. The lidar system of claim 1, wherein the target information comprises reflectivity, distance, position, velocity, attitude, and shape of the object under test.
4. The lidar system of claim 1, wherein the light source module comprises:
a laser for emitting a laser beam; and
and the lens unit is arranged on the light path of the laser beam and is used for shaping and collimating the laser beam.
5. The lidar system of claim 1, wherein the receiving lens is further configured to focus and shape the reflected light beam to adapt a spot size of the reflected light beam to a photosensitive unit of a predetermined area of the detection module.
6. The lidar system according to claim 5, wherein the receiving lens comprises a converging lens and a shaping lens, the converging lens is configured to converge the reflected light beams, and the shaping lens is configured to shape the converged reflected light beams respectively.
7. The lidar system of claim 1, wherein the detection module is one of an avalanche photodiode, a charge coupled device, a complementary metal oxide semiconductor, and a multi-pixel photon counter.
8. The lidar system of claim 1, wherein the detection module comprises a filter configured to filter the echo energy signal and transmit the filtered echo energy signal to the processing module.
9. The lidar system of claim 1, wherein the receiving lens comprises a single lens or a cemented lens or a lens group.
10. The lidar system of claim 9, wherein the einzel lens, the cemented lens, and/or the lens group are made of a metamaterial.
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| CN202021535301.1U CN212694031U (en) | 2020-07-29 | 2020-07-29 | Laser radar system |
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| CN202021535301.1U CN212694031U (en) | 2020-07-29 | 2020-07-29 | Laser radar system |
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| CN212694031U true CN212694031U (en) | 2021-03-12 |
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