Optical signal processing method for laser radar and laser radar

Abstract

The present invention relates to the field of laser radar technology, and discloses an optical signal processing method for laser radar and a laser radar, the method comprising: obtaining an echo optical signal of a close-range target; the echo optical signal is an optical signal reflected by the close-range target when the laser radar emits a laser beam to the close-range target; and regulating the light field distribution of the echo optical signal in a receiving optical system so that a detector receives part of the energy of the echo optical signal. In this way, by regulating the light field distribution of the echo light of the close-range target in the receiving optical system, the energy received by the detector is reduced, and the light collecting ability of the receiving optical system during close-range ranging is weakened, thereby solving the problem of oversaturation of the laser radar detector when a close-range strong signal is present.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to an optical signal processing method for laser radar and a laser radar. Background Art

[0002] When a laser radar with a scanning component is used for ranging, as the distance to the target increases, the energy of the reflected light from the target received by the detector decreases. In order to ensure stable detection of targets at long distances (such as more than 200 meters), higher laser emission energy and larger receiving optical apertures are required. However, when the target is close to the laser radar (such as less than 10 meters, 20 meters or 30 meters, etc., which varies with the size of the target reflectivity), under the above-mentioned energy and optical aperture conditions, the energy of the reflected light from the target received by the detector is often too large, exceeding the upper limit of its complete breakdown. In severe cases, the detector is directly damaged beyond recovery; in general, the detector takes a certain amount of time to recover, but during the recovery time, the laser radar ranging fails.

[0003] Therefore, how to solve the problem of detector breakdown in the above-mentioned laser radar when a strong signal is detected at close range is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an optical signal processing method for laser radar and laser radar, which can reduce the light collecting ability of the receiving optical system during close-range distance measurement and solve the problem of oversaturation of the laser radar detector when a strong signal is detected at close range. The specific scheme is as follows:

[0005] A method for processing optical signals for laser radar, comprising:

[0006] Acquire an echo light signal of a close-range target; the echo light signal is an optical signal reflected back by the close-range target when the laser radar emits a laser beam to the close-range target;

[0007] The light field distribution of the echo light signal in the receiving optical system is regulated so that the detector receives part of the energy of the echo light signal.

[0008] Preferably, in the above-mentioned optical signal processing method for laser radar provided by an embodiment of the present invention, the step of regulating the light field distribution of the echo optical signal in the receiving optical system includes:

[0009] A light blocking component is applied in the reflected light path of the close-range target to regulate the light field distribution of the echo light signal in the receiving optical system.

[0010] Preferably, in the above-mentioned optical signal processing method for laser radar provided in an embodiment of the present invention, applying a light blocking component in the reflected light path of the close-range target to regulate the light field distribution of the echo light signal in the receiving optical system includes:

[0011] A light blocking component is arranged in the reflection light path of the close-range target, and the light blocking component is used to block part of the energy of the light spot formed by the receiving optical system converging the echo light signal.

[0012] Preferably, in the above-mentioned optical signal processing method for lidar provided in an embodiment of the present invention, the light blocking component is located between the receiving optical system and the detector; or, the light blocking component is located on a side of the receiving optical system away from the detector.

[0013] Preferably, in the above-mentioned optical signal processing method for laser radar provided by an embodiment of the present invention, the step of regulating the light field distribution of the echo optical signal in the receiving optical system includes:

[0014] The field of view aperture is used to adjust the light field distribution of the echo light signal in the receiving optical system.

[0015] Preferably, in the above-mentioned optical signal processing method for laser radar provided in an embodiment of the present invention, the use of a field aperture to adjust the light field distribution of the echo light signal in the receiving optical system includes:

[0016] The boundary of the detector is used as a field aperture, and the detector is moved along a set direction so that the receiving optical system can focus the echo light signal part on the photosensitive surface of the detector.

[0017] Preferably, in the above-mentioned optical signal processing method for laser radar provided by an embodiment of the present invention, the step of regulating the light field distribution of the echo optical signal in the receiving optical system includes:

[0018] The focal length of the receiving optical system is increased to adjust the light field distribution of the echo light signal in the receiving optical system.

[0019] The embodiment of the present invention further provides a laser radar, comprising: a laser, a receiving optical system, a detector and a control component;

[0020] The laser is used to emit a laser beam to a close-range target, so that the close-range target reflects the laser beam to obtain an echo light signal;

[0021] The regulating component is used to regulate the light field distribution of the echo light signal in the receiving optical system so that the detector receives part of the energy of the echo light signal.

[0022] Preferably, in the above-mentioned laser radar provided by the embodiment of the present invention, the regulating component is a light blocking component; and the light blocking component is located in the reflected light path of the close-range target.

[0023] Preferably, in the above-mentioned laser radar provided in an embodiment of the present invention, the regulating component is a field of view aperture.

[0024] It can be seen from the above technical scheme that the optical signal processing method for laser radar provided by the present invention includes: obtaining the echo light signal of a close-range target; the echo light signal is a light signal that is reflected back by the close-range target when the laser radar emits a laser beam to the close-range target; and regulating the light field distribution of the echo light signal in the receiving optical system so that the detector receives part of the energy of the echo light signal.

[0025] The optical signal processing method for laser radar provided by the present invention reduces the energy received by the detector by regulating the light field distribution of the echo light of the close-range target in the receiving optical system, thereby weakening the light collecting ability of the receiving optical system during close-range ranging, thereby solving the problem of oversaturation of the laser radar detector when a strong signal is present at close range.

[0026] In addition, the present invention also provides a corresponding laser radar for the optical signal processing method used for the laser radar, further making the above method more practical, and the laser radar has corresponding advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 A flowchart of a method for processing optical signals for a laser radar provided in an embodiment of the present invention;

[0029] Figure 2 This is one of the schematic diagrams of the principle of arranging the existing detector off the optical axis;

[0030] Figure 3 This is the second schematic diagram of the principle of arranging the existing detector off the optical axis;

[0031] Figure 4 A schematic diagram of applying a light blocking component in a reflected light path of a close-range target provided by an embodiment of the present invention;

[0032] Figure 5 A schematic diagram of using the boundary of the detector as a field stop provided in an embodiment of the present invention;

[0033] Figure 6 A schematic diagram of forming a diffuse light spot after increasing the focal length of the receiving optical system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention provides a method for processing optical signals for laser radar, such as Figure 1 As shown, the following steps are included:

[0036] S101, obtaining an echo light signal of a close-range target; the echo light signal is a light signal that is reflected back by a close-range target when a laser radar emits a laser beam to the close-range target.

[0037] In practical applications, the above-mentioned close-range target refers to a target that is close to the laser radar. The range of the close distance can be between 0 and a set threshold. The set threshold can vary with the target reflectivity, such as 10 meters, 20 meters or 30 meters, etc. The larger the target reflectivity, the larger the set threshold can be.

[0038] S102, regulating the light field distribution of the echo light signal in the receiving optical system so that the detector receives part of the energy of the echo light signal.

[0039] It should be noted that in a laser radar with scanning components, there are differences in the paths of echo light signals of long-distance targets and short-distance targets in the optical system. The present invention can specifically adjust the light field distribution of the echo light signals of short-distance targets in the receiving optical system to reduce the energy received by the detector.

[0040] In the above-mentioned optical signal processing method for laser radar provided in an embodiment of the present invention, the energy received by the detector is reduced by adjusting the light field distribution of the echo light of the close-range target in the receiving optical system, thereby weakening the light collecting ability of the receiving optical system during close-range ranging, thereby solving the problem of oversaturation of the laser radar detector when a strong signal is present at close range.

[0041] It is understandable that the time-of-flight method is generally used when LiDAR is used for ranging. In order to ensure that the echo light of the distant target can be received by the detector, the detector needs to be arranged away from the optical axis of the receiving optical system (assuming that the LiDAR receiving and transmitting optical systems are coaxially arranged). Figure 2 As shown, when the laser radar 1 measures the distance to the target 2 at a distance of L, the time t = 2*L / C elapses when the light flies from the laser radar 1 to the target 2 and then flies back to the laser radar 1 again, where C is the speed of light. During the flight of the light, the scanning component of the laser radar 1 is continuously working, and its scanning angle is α = t*ω, where ω is the angular velocity. Usually, in order to increase the laser radar 1's ability to collect the echo light of the target 2, a receiving optical system 4 is set in front of the detector 3. It is assumed that the detector 4 is located on the optical axis h of the receiving optical system 4, that is, the image point position of the 0° field of view of the receiving optical system 4. Due to the influence of the scanning component, there is an angle α (or 2α angle, etc., which is related to the specific optical system design) between the echo light of the target 2 and the optical axis h of the receiving optical system 4. The position where the echo light is concentrated will deviate from the optical axis h of the receiving optical system 4, and the position of the detector 3 will also deviate from the optical axis h of the receiving optical system 4, with a deviation of d. It can be seen that the optimal position of the detector 3 deviating from the optical axis of the lens is affected by the distance of the target 2.

[0042] Since the structures of the receiving optical system 4 are various, in order to maintain generality, the plane reflector, window and other parts without optical focal length are ignored, and only the lens part with optical focal length is taken for explanation. Figure 3 shown.

[0043] When the laser radar measures the distance to a close target, the laser beam is emitted from the laser, then flies to the target and is reflected by the target, and finally flies back to the laser radar to complete a distance measurement process. Since the distance between the target and the radar is short, a distance measurement process takes a very short time, and the scanning angle of the scanning component is very small and can be ignored. Figure 3 As shown, the target's echo light is incident on the receiving optical system 4 at approximately 0°. After being focused by the receiving optical system 4, the energy converges into a light spot on the photosensitive surface 31 of the detector 3, which is located on the optical axis of the receiving optical system 4. Since the focal plane of the receiving optical system 4 is usually a conjugate plane of the infinitely distant target, only the infinitely distant target can be converged into a very small point on the focal plane after passing through the receiving optical system 4. For a close-range target, when its echo light converges at point A, it will be dispersed into a larger light spot a.

[0044] Similarly, when the laser radar measures the distance to a long-distance target, the time consumed for a distance measurement process is relatively long. Accordingly, the influence of the scanning component cannot be ignored, causing the target's echo light to be incident on the receiving optical system at an angle α. After being focused by the receiving optical system 4, the energy is gathered into a smaller light spot b on the photosensitive surface 31 of the detector 3, and the light spot is located at position B on the focal plane.

[0045] In practical applications, in order to take into account a certain distance measurement range, the laser radar needs to arrange the detector away from the optical axis so that the echo light of both long-distance targets and short-distance targets can fall on the photosensitive surface of the detector. Since the reflected light energy of short-distance targets is high, it is easy to break through the detector. To this end, the present invention can specifically regulate the light field distribution of the echo light signal of the short-distance target in the receiving optical system.

[0046] In specific implementation, in the above-mentioned optical signal processing method for lidar provided in an embodiment of the present invention, step S102 regulates the light field distribution of the echo light signal in the receiving optical system, which may specifically include: applying a light blocking component in the reflected light path of the close-range target to regulate the light field distribution of the echo light signal in the receiving optical system.

[0047] In a specific implementation, a light blocking component is applied in the reflected light path of the close-range target to regulate the light field distribution of the echo light signal in the receiving optical system. Specifically, it may include: setting a light blocking component in the reflected light path of the close-range target, and using the light blocking component to block part of the energy of the light spot formed by the echo light signal converged by the receiving optical system.

[0048] In a specific implementation, the light shielding component may be located between the receiving optical system and the detector; or, the light shielding component may be located on a side of the receiving optical system away from the detector.

[0049] by Figure 4 For example, the light blocking component is a light blocking plate 5, which is located between the receiving optical system 4 and the detector 3. The light blocking plate 5 can block half of the energy of the light spot a. It should be noted that the light blocking component is not limited to the light blocking plate 5, but can also be other components that can block light; the shape of the light blocking plate 5 is not limited to a flat plate shape, but can also be a special shape; the specific position of the light blocking component can be arranged at a convenient position in the optical system. In addition, the method of applying the light blocking component of the present invention is not limited to the reflected light path of a close-range target, but can also partially block the reflected light path of a distant target at the same time.

[0050] Furthermore, in a specific implementation, in the above-mentioned optical signal processing method for lidar provided in an embodiment of the present invention, step S102 regulates the light field distribution of the echo light signal in the receiving optical system, which may specifically include: using a field of view aperture to regulate the light field distribution of the echo light signal in the receiving optical system.

[0051] Preferably, in a specific implementation, in the above-mentioned optical signal processing method for lidar provided in an embodiment of the present invention, a field of view aperture is used to regulate the light field distribution of the echo light signal in the receiving optical system, which may specifically include: using the boundary of the detector as the field of view aperture, and moving the detector along a set direction so that the receiving optical system can converge part of the echo light signal on the photosensitive surface of the detector.

[0052] Assume that the size of the detector photosensitive surface has been selected. Figure 5 For example, the detector 3 is moved along the vector AB using the boundary of the detector 3 as the field of view aperture, thereby increasing the eccentricity of the detector 3 and causing part of the energy of the light spot a to be lost outside the photosensitive surface 31 of the detector 3 .

[0053] In practical applications, a newly added component (such as a plate with a hole in the middle) can also be used as a field stop, but this may increase the cost and workload. Therefore, directly using the boundary of the detector 3 as the field stop is a better way.

[0054] Furthermore, in a specific implementation, in the above-mentioned optical signal processing method for lidar provided in an embodiment of the present invention, step S102 regulates the light field distribution of the echo light signal in the receiving optical system, which may specifically include: increasing the focal length of the receiving optical system to regulate the light field distribution of the echo light signal in the receiving optical system.

[0055] Assume that the size of the detector photosensitive surface has been selected. Figure 6 For example, increase the size of spot a (form a diffuse spot) so that part of the energy of spot a is lost outside the photosensitive surface of the detector. The specific measure to increase spot a is to increase the focal length of the receiving optical system. According to optical principles, under the same aperture of the receiving optical system, the larger the focal length, the slower the light in front of the detector converges, that is, the larger the spot a. It should be noted that from the radar ranging equation, it can be seen that the ranging performance of the lidar is related to the aperture of the optical system, but not to the focal length. Therefore, if the aperture of the receiving optical system remains unchanged, increasing the focal length will not weaken the ranging performance of the radar for long-distance targets.

[0056] In addition, it should be pointed out that the above-mentioned measures such as adding a light baffle in the optical path, using a field aperture, and increasing the focal length of the receiving optical system can be implemented separately or in combination. These measures can be used to specifically regulate the light field distribution of the reflected light of a close-range target in the receiving optical system, ultimately reducing the energy received by the detector, thereby reducing the problem of oversaturation of the LiDAR detector when a strong signal is present at close range.

[0057] Based on the same inventive concept, an embodiment of the present invention also provides a laser radar. Since the principle of solving the problem by the laser radar is similar to the aforementioned optical signal processing method for laser radar, the implementation of the laser radar can refer to the implementation of the optical signal processing method for laser radar, and the repeated parts will not be repeated.

[0058] In a specific implementation, the laser radar provided by the embodiment of the present invention specifically includes: a laser, a receiving optical system, a detector and a control component;

[0059] A laser is used to emit a laser beam to a close-range target, so that the close-range target reflects the laser beam to obtain an echo light signal;

[0060] The regulating component is used to regulate the light field distribution of the echo light signal in the receiving optical system so that the detector receives part of the energy of the echo light signal.

[0061] In the above-mentioned laser radar provided in the embodiment of the present invention, the light field distribution of the echo light of the close-range target in the receiving optical system can be regulated by the regulating component, so that the energy received by the detector is reduced, thereby weakening the light collecting ability of the receiving optical system during close-range ranging, thereby solving the problem of oversaturation of the laser radar detector when a strong signal is present at close range.

[0062] In a specific implementation, in the above-mentioned laser radar provided in an embodiment of the present invention, the control component can be a light shielding component; the light shielding component can be located in the reflection light path of a close-range target. The light shielding component can block part of the energy of the light spot formed by the receiving optical system converging the echo light signal. Preferably, the light shielding component can be located between the receiving optical system and the detector; or, the light shielding component can be located on the side of the receiving optical system away from the detector.

[0063] In a specific implementation, in the above-mentioned laser radar provided in an embodiment of the present invention, the regulating component may be a field aperture. Preferably, the boundary of the detector is used as the field aperture, and the detector is moved along a set direction, so that the receiving optical system can focus part of the echo light signal on the photosensitive surface of the detector.

[0064] In addition, by setting the focal length of the receiving optical system in the above-mentioned laser radar provided by the embodiment of the present invention to be higher, a diffuse light spot can be formed on the photosensitive surface of the detector, thereby solving the problem of over-saturation of the laser radar detector when a strong signal is present at a close range, especially in the scenario of switching to ranging of close-range targets after ranging of long-range targets.

[0065] For more specific working processes of the above-mentioned components, please refer to the corresponding contents disclosed in the above-mentioned embodiments, which will not be repeated here.

[0066] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the devices, equipment, and storage media disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0067] In summary, an optical signal processing method and laser radar for laser radar provided in an embodiment of the present invention include: obtaining an echo optical signal of a close-range target; the echo optical signal is an optical signal reflected back by the close-range target when the laser radar emits a laser beam to the close-range target; and regulating the light field distribution of the echo optical signal in the receiving optical system so that the detector receives part of the energy of the echo optical signal. The above optical signal processing method reduces the energy received by the detector by regulating the light field distribution of the echo light of the close-range target in the receiving optical system, thereby weakening the light collecting ability of the receiving optical system during close-range ranging, and further solving the problem of oversaturation of the laser radar detector when there is a strong signal at close range. In addition, the present invention also provides a corresponding laser radar for the optical signal processing method for laser radar, which further makes the above method more practical, and the laser radar has corresponding advantages.

[0068] Finally, it should be noted that, in this article, relational terms such as first and second, etc. 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 these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0069] The optical signal processing method for laser radar and laser radar provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for processing optical signals for laser radar, characterized in that: include: Acquire an echo light signal of a close-range target; the echo light signal is an optical signal reflected back by the close-range target when the laser radar emits a laser beam to the close-range target; The light field distribution of the echo light signal in the receiving optical system is regulated so that the detector receives part of the energy of the echo light signal.

2. The optical signal processing method for laser radar according to claim 1, characterized in that: The step of regulating the light field distribution of the echo light signal in the receiving optical system comprises: A light blocking component is applied in the reflected light path of the close-range target to regulate the light field distribution of the echo light signal in the receiving optical system.

3. The optical signal processing method for laser radar according to claim 2, characterized in that: The step of applying a light blocking component in the reflected light path of the close-range target to adjust the light field distribution of the echo light signal in the receiving optical system comprises: A light blocking component is arranged in the reflection light path of the close-range target, and the light blocking component is used to block part of the energy of the light spot formed by the receiving optical system converging the echo light signal.

4. The optical signal processing method for laser radar according to claim 3, characterized in that: The light shielding component is located between the receiving optical system and the detector; or, the light shielding component is located on a side of the receiving optical system away from the detector.

5. The optical signal processing method for laser radar according to claim 2, characterized in that: The step of regulating the light field distribution of the echo light signal in the receiving optical system comprises: The field of view aperture is used to adjust the light field distribution of the echo light signal in the receiving optical system.

6. The optical signal processing method for laser radar according to claim 5, characterized in that: The method of using a field aperture to regulate the light field distribution of the echo light signal in the receiving optical system includes: The boundary of the detector is used as a field aperture, and the detector is moved along a set direction so that the receiving optical system can focus the echo light signal part on the photosensitive surface of the detector.

7. The optical signal processing method for laser radar according to claim 2, characterized in that: The step of regulating the light field distribution of the echo light signal in the receiving optical system comprises: The focal length of the receiving optical system is increased to adjust the light field distribution of the echo light signal in the receiving optical system.

8. A laser radar, characterized in that: include: Lasers, receiving optical systems, detectors and control components; The laser is used to emit a laser beam to a close-range target, so that the close-range target reflects the laser beam to obtain an echo light signal; The regulating component is used to regulate the light field distribution of the echo light signal in the receiving optical system so that the detector receives part of the energy of the echo light signal.

9. The laser radar according to claim 8, characterized in that: The regulating component is a light blocking component; the light blocking component is located in the reflected light path of the close-range target.

10. The laser radar according to claim 8, characterized in that: The regulating component is a field diaphragm.

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