CN218547000U - Imaging device, laser radar, and reception system for the same - Google Patents
Imaging device, laser radar, and reception system for the same Download PDFInfo
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- CN218547000U CN218547000U CN202222970429.6U CN202222970429U CN218547000U CN 218547000 U CN218547000 U CN 218547000U CN 202222970429 U CN202222970429 U CN 202222970429U CN 218547000 U CN218547000 U CN 218547000U
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Abstract
The application is applicable to the technical field of laser radars, and provides an imaging device, a laser radar and a receiving system thereof, wherein the receiving system of the laser radar comprises a receiving element, a polarization beam splitting element and a detector assembly; the receiving element is used for receiving the reflected light of the target to be detected and transmitting the received reflected light to the incident surface of the polarization beam splitting element; the polarization beam splitting element is used for separating a p polarization component from an s polarization component in the reflected light transmitted by the receiving element and transmitting the p polarization component and the s polarization component to the detector assembly; the detector assembly includes a first detector for detecting the p-polarization component and a second detector for detecting the s-polarization component; according to the scheme, the p and s polarization components in the reflected light collected by the receiving element are separated through the polarization beam splitting element and the detector assembly, the two detectors detect the p and s polarization components respectively, and the substance identification of the target to be detected is realized by utilizing the polarization difference.
Description
Technical Field
The application belongs to the technical field of laser radars, and particularly relates to an imaging device, a laser radar and a receiving system of the laser radar.
Background
The laser radar is a remote sensing technology which utilizes laser to complete three-dimensional detection and consists of an emitting system and a receiving system. The transmitting system is used for transmitting pulse laser to irradiate the target to be measured, the receiving system is used for receiving reflected light of the target to be measured, and the longitudinal distance of the object is calculated by recording the time difference between the transmitted pulse and the received pulse.
However, the conventional laser radar can only detect the position of the target, but cannot acquire material information of the target.
Therefore, there is a need to design a receiving system that can perform substance identification.
SUMMERY OF THE UTILITY MODEL
An object of the embodiment of the application is to provide an imaging device, a laser radar and a receiving system thereof, and the purpose is to solve the problem that the existing laser radar cannot acquire material information of a target.
The embodiment of the application is realized in such a way that the receiving system of the laser radar comprises a receiving element, a polarization beam splitting element and a detector assembly; the receiving element is used for receiving the reflected light of the target to be detected and transmitting the received reflected light to the incident surface of the polarization beam splitting element; the polarization beam splitting element is used for separating a p polarization component from an s polarization component in the reflected light transmitted by the receiving element and transmitting the p polarization component and the s polarization component to the detector assembly; the detector assembly includes a first detector for detecting the p-polarization component and a second detector for detecting the s-polarization component;
the polarization direction of the p-polarized light is in a plane formed by the incident light, the reflected light, the refracted light and the normal line, and the polarization direction of the s-polarized light is perpendicular to the plane formed by the incident light, the reflected light, the refracted light and the normal line.
The application also provides a laser radar which comprises a transmitting system and the receiving system, wherein the transmitting system at least comprises a laser and a deflection structure;
the laser is used for emitting light with set wavelength to irradiate a target to be detected, wherein the light with the set wavelength comprises p-direction polarized light and s-direction polarized light;
the deflection structure is arranged on an emergent light path of the laser and is used for deflecting the emergent light of the laser so as to enable the emergent light of the laser to be capable of scanning in a two-dimensional space.
The application also provides an imaging device, which comprises an illumination light source, a light collecting system and the receiving system;
the illumination light source is used for emitting laser in a p polarization direction or laser in an s polarization direction to a target to be measured;
the light collecting system is arranged on an emergent light path of the polarization beam splitting element;
for the receiving system of the laser radar provided in the above embodiment, the p-polarization component and the s-polarization component in the reflected light collected by the receiving element are separated by the polarization beam splitting element and the detector assembly, and are respectively detected by the two detectors, and the substance identification of the target to be detected is realized by using the polarization difference.
Drawings
Fig. 1 is a schematic structural diagram of a receiving system of a laser radar according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a laser radar according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of an imaging apparatus according to an embodiment of the present application;
FIG. 4 is a schematic diagram of the propagation principle of light in different media;
FIG. 5 shows reflectivity R of p-polarized component of reflected light from a glass according to an embodiment of the present application p Reflectivity R of s-polarization component si The variation trend with the incident angle is shown.
In the drawings: 100-a receiving system; 101-a receiving element; 102-a polarizing beam splitting element; 103-a first detector; 104-a second detector; 105-a light collection system; 106-digital micromirror array; 200-a transmission system; 201-a laser; 202-a deflection structure; 203-light emitting elements; 300-illumination source.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Specific implementations of the present application are described in detail below with reference to specific embodiments.
Fig. 1 is a schematic structural diagram of a receiving system of a lidar provided in an embodiment of the present application, where the receiving system 100 of the lidar includes a receiving element 101, a polarization beam splitting element 102, and a detector assembly;
the receiving element 101 is configured to receive reflected light of the target to be measured, and transmit the received reflected light to an incident surface of the polarization beam splitting element 102;
the polarization beam splitting element 102 is configured to separate a p-polarization component from an s-polarization component in the reflected light transmitted by the receiving element 101, and transmit the p-polarization component and the s-polarization component to the detector assembly;
the detector assembly comprises a first detector 103 and a second detector 104, the first detector 103 being arranged to detect the p-polarization component and the second detector 104 being arranged to detect the s-polarization component.
In an example of the embodiment, the reflected light of the target to be measured may be reflected light of the target to be measured after being irradiated by an external light source, a laser, or an illumination light source, and the receiving element 101 may be a single lens, a lens group, a fresnel lens, or the like; the first detector 103 and the second detector 104 may be photodiodes, photomultipliers or avalanche photodiodes.
The receiving system of laser radar that this embodiment provided, through polarization beam splitting component and the detector subassembly that sets up, the p in the reverberation that the receiving element was collected, s polarization component separate to detect respectively by two detectors, utilize the polarization difference to realize the material appraisal to the target that awaits measuring, receiving system's overall structure is simple, and the facilitate promotion is used.
The polarization beam splitting element utilizes the principle that light has different refractive indexes in different media, and as shown in fig. 4, the reflection phenomenon of light can be analyzed by the boundary condition of an electromagnetic field according to the electromagnetic theory of light. Splitting the electric vector of the incident light into a p-polarized component E parallel to the plane of incidence p And an s-polarized component E perpendicular to the plane of incidence s The reflectivity R of the p-polarized component in the reflected light p Reflectivity R of s-polarization component s Respectively as follows:
in which there is n 1 sin i 1 ＝n 2 sin i 2 ，n 1 And n 2 Refractive indices of air and of the object, i 1 For the angle of incidence of light on the object, n if the light is incident on the glass from air 1 ＝1，n 2 Reflectance R of =1.5,p polarization component p Reflectivity R of s-polarization component s The curve with the incident angle is shown in fig. 5. It can be seen that for a specular object such as glass, the reflectivity of the p-polarized component is always higher than that of the s-polarized component.
Thus, in the context of some embodiments, for a specular reflective object such as glass, smooth metal, etc., when the incident light is linearly polarized, the target reflected light is approximately linearly polarized:
when the incident light is linearly polarized light in the p polarization direction, p polarization components in the reflected light are more, and s polarization directions are less;
when the incident light is linearly polarized light in the s-polarization direction, the s-polarization component in the reflected light is more, and the p-polarization direction is less;
when the incident light is completely unpolarized light, the target reflected light is unpolarized light, and the s-polarization component is always higher than the p-polarization component.
For a general rough object, when light is incident on the surface of the object, the surface reflects the light in all directions, so that no matter whether the incident light is linearly polarized light or not, the target reflected light is always unpolarized light, and the p-polarized component is almost equivalent to the s-polarized component.
In summary, the polarization characteristics of the target light, i.e., the p-polarization component and the s-polarization component, are measured simultaneously with the measurement of the intensity of the target light, and the target component can be identified.
In another embodiment scenario, as shown in fig. 1, the polarizing beam splitting element is a polarizing beam splitting prism or a glancing prism, preferably the polarizing beam splitting element is a polarizing beam splitting prism.
In another embodiment, as shown in fig. 1, the sensitivity of the first detector 103 is different from the sensitivity of the second detector 104.
In this embodiment, the p and s polarization components are detected by two detectors with different sensitivities, so that the requirement on the dynamic range of the detectors is reduced, and the construction cost of the device is further reduced.
In addition, in some embodiment scenarios, for example, when the target object (i.e., the target to be detected) is a specular reflection object such as glass or smooth metal, the first detector 103 and the second detector 104 included in the detector assembly may also be detectors with the same sensitivity, and the detectors with the same sensitivity may simplify the complexity of the receiving system in building, reduce the difficulty in distinguishing, and facilitate maintenance.
In another embodiment, the detector assembly further comprises a controller, the controller is connected with a memory, and the memory stores a pre-calibration database;
the controller is used for judging the material of the target to be detected according to the difference between the p-polarization component and the s-polarization component;
or judging the material of the target to be detected according to the comparison between the difference and the data in the pre-calibration database.
In this embodiment, the pre-calibration database is formed by pre-calibrating according to the material characteristics of the known object, that is, the object made of the known material is used in advance to pre-calibrate the intensity difference detected by the first detector 103 and the second detector 104.
In another embodiment, as shown in fig. 2, there is provided a lidar comprising a transmitting system 200 and a receiving system 100 as described in any of the above, the transmitting system 200 comprising at least a laser 201 and a deflecting structure 202;
the laser 201 is configured to emit light with a set wavelength to irradiate a target to be detected, where the light with the set wavelength includes p-direction polarized light and s-direction polarized light;
the deflection structure 202 is arranged on an emergent light path of the laser and is used for deflecting the emergent light of the laser, so that the emergent light of the laser can be scanned in a two-dimensional space.
In an example of this embodiment, the set wavelength light at least includes p-direction polarized light and s-direction polarized light, and the lidar may be applied to substance identification or other remote sensing fields, and has the following modes when performing substance identification:
emitting p-direction polarized light through the laser 201 to irradiate a target to be detected, namely a target object, wherein if the intensity detected by the first detector 103 is higher than that detected by the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to the intensity detected by the second detector 104, the target object is a common diffuse reflection object;
emitting polarized light in the s direction to irradiate a target object through the laser 201, wherein if the intensity detected by the first detector 103 is lower than that detected by the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to the intensity detected by the second detector 104, the target object is a common diffuse reflection object;
emitting completely unpolarized light through the laser 201 to irradiate a target object, wherein if the intensity detected by the first detector 103 is lower than that detected by the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to the intensity detected by the second detector 104, the target object is a normal diffuse reflection object.
In addition, in one implementation scenario, pre-calibration of the material may be performed and used as a reference to determine the material characteristics of the target. That is, the strength difference detected by the first detector 103 and the second detector 104 is pre-calibrated by using an object with a known material in advance, so that the material of the target to be detected can be determined according to the strength difference detected by the first detector 103 and the second detector 104 during the test.
In conclusion, the material of the target to be detected is judged by the detection in the multiple modes, and the whole system is simple in structure and high in applicability.
In another embodiment, as shown in fig. 2, the emission system further comprises an emission light element 203, and the emission light element 203 is disposed on an exit light path of the deflection structure 202 and is used for emitting the exit light of the deflection structure 202 to the object to be measured.
In this embodiment, the deflecting structure 202 is one of a rotating polygon mirror, a micro-electro-mechanical system (MEMS) galvanometer, and a digital micro-mirror array (DMD), and the light emitting element is a single lens or a lens group composed of a plurality of lenses.
The specific structure of the deflecting structure 202 and the light emitting element in this embodiment is not limited thereto, and in practical applications, those skilled in the art can flexibly select and adjust the deflecting structure and the light emitting element as required to implement the present embodiment, and detailed descriptions thereof are omitted here.
As shown in fig. 3, in another embodiment, an imaging device is provided based on the receiving system of the laser radar, and is applied to single-pixel imaging; the imaging device comprises an illumination source 300, a light collecting system 105 and a receiving system 100 as described in any of the above;
the illumination light source 300 is used for emitting laser in a p-polarization direction or laser in an s-polarization direction to a target to be measured;
the light collecting system 105 is disposed on the path of the outgoing light from the polarization beam splitting element 102.
In this embodiment, the polarization beam splitter 102 may be a digital micromirror array (DMD) 106; the illumination light source 300 is not limited to a laser, and may be a sunlight or a conventional illumination lamp, in which a solid line represents emitted light and a dotted line represents received light, such as an LED lamp or other illumination lamps; the light collection system comprises one or more light collectors through which the outgoing light from the polarization beam splitting element 102 is collected, and the digital micromirror array (DMD) 106 is configured to: the target light of different sub-fields (sub-field 1, sub-field 2, sub-field 3) generated by the illumination light irradiating the object is imaged on the DMD through the receiving element 101, and the target light corresponding to different sub-fields is reflected into the light collecting system by the micromirrors at different positions on the DMD for collection;
in addition, the polarization direction of the p-polarized light in this embodiment is in the plane formed by the incident, reflected, refracted light and the normal line, and the polarization direction of the s-polarized light is perpendicular to the plane formed by the incident, reflected, refracted light and the normal line.
Specifically, the imaging apparatus is used for substance identification, and has the following modes:
the illumination light source is set as: the illumination light is p-polarized laser and irradiates a target object, and if the intensity detected by the first detector 103 is lower than that detected by the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to the intensity detected by the second detector 104, the target object is a common diffuse reflection object;
the illumination light is s-polarized laser, and if the intensity detected by the first detector 103 is lower than the intensity detected by the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to the intensity detected by the second detector 104, the target object is a normal diffuse reflection object.
The illumination light is completely unpolarized laser or sunlight, and if the intensity detected by the first detector 103 is lower than that of the second detector 104, the target object is glass or metal; if the intensity detected by the first detector 103 is equivalent to that of the second detector 104, the target object is a general diffuse reflection object. Similarly, an object with a known material may be used in advance to pre-calibrate the intensity difference detected by the first detector 103 and the second detector 104, so that in an actual test, the material of the target to be detected may be determined according to the intensity difference detected by the first detector 103 and the second detector 104.
In addition, in some embodiment scenarios, the first detector 103 and the second detector 104 are used to detect p-polarized components and s-polarized components of the target light, so that when the target object is a specular reflection object such as glass or smooth metal, the intensity difference between the p-polarized components and the s-polarized components in the target light is large, and at this time, the two detectors with different sensitivities can be used to detect the components, respectively, thereby reducing the requirement on the dynamic range of the detectors.
In summary, the receiving system of the laser radar provided by the above embodiment performs substance identification by using polarization difference based on the laser radar and the imaging device provided by the receiving system, and includes a receiving element, a polarization beam splitting element, and a first detector and a second detector included in a detector assembly; the polarization beam splitting element is used for separating p and s polarization components of target object reflected light collected by the receiving element, the p and s polarization components are detected by the two detectors respectively, substance identification is carried out on the target object by utilizing polarization difference, the structure is relatively simple, the polarization beam splitting element can be applied to laser detection and single-pixel imaging, and the application field is wide.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (8)
1. A receiving system of a laser radar is characterized by comprising a receiving element, a polarization beam splitting element and a detector assembly;
the receiving element is used for receiving the reflected light of the target to be detected and transmitting the received reflected light to the incident surface of the polarization beam splitting element;
the polarization beam splitting element is used for separating a p polarization component from an s polarization component in the reflected light transmitted by the receiving element and transmitting the p polarization component and the s polarization component to the detector assembly;
the detector assembly includes a first detector for detecting the p-polarized component and a second detector for detecting the s-polarized component.
2. The lidar receiving system of claim 1, wherein the polarizing beam splitting element is a polarizing beam splitting prism or a glantler prism.
3. The lidar receiving system of claim 1, wherein a sensitivity of the first detector is different from a sensitivity of the second detector.
4. The lidar receiving system of claim 1, wherein the detector assembly further comprises a controller, the controller coupled to a memory, the memory storing a pre-calibration database;
the controller is used for judging the material of the target to be detected according to the difference between the p-polarization component and the s-polarization component;
or judging the material of the target to be detected according to the comparison between the difference and the data in the pre-calibration database.
5. Lidar characterized in that it comprises a transmitting system and a receiving system according to any of claims 1-4, said transmitting system comprising at least a laser and a deflecting structure;
the laser is used for emitting light with set wavelength to irradiate a target to be detected, wherein the light with the set wavelength comprises p-direction polarized light and s-direction polarized light;
the deflection structure is arranged on an emergent light path of the laser and is used for deflecting the emergent light of the laser so as to enable the emergent light of the laser to be capable of scanning in a two-dimensional space.
6. The lidar of claim 5, wherein the transmitting system further comprises a transmitting optical element disposed in an exit optical path of the deflecting structure for emitting the exit light of the deflecting structure toward an object to be measured.
7. The lidar of claim 6, wherein the deflecting structure is one of a rotating polygon mirror, a MEMS galvanometer, a digital micromirror array; the light emitting element adopts a single lens or a lens group consisting of a plurality of lenses.
8. An imaging device comprising an illumination source, a light collection system and a receiving system according to any one of claims 1 to 4;
the illumination light source is used for emitting laser in a p polarization direction or laser in an s polarization direction to a target to be measured;
the light collecting system is arranged on an emergent light path of the polarization beam splitting element.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222970429.6U CN218547000U (en) | 2022-11-08 | 2022-11-08 | Imaging device, laser radar, and reception system for the same |
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| CN202222970429.6U CN218547000U (en) | 2022-11-08 | 2022-11-08 | Imaging device, laser radar, and reception system for the same |
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