A co-located polarization lidar system based on an optical rotator

Abstract

The present invention provides a transceiver co-located polarization laser radar system based on an optical rotator. In the transceiver co-located polarization laser radar system, the echo signal light obtained based on the outgoing signal light generated by a pulsed laser includes the signal light in the parallel polarization state and the signal light in the vertical polarization state. Since the polarization beam splitter cannot reflect the signal light in the parallel polarization state, the polarization plane of the echo signal light is rotated by the optical rotator to adjust the polarization state of the echo signal light, and the optical rotator is respectively put into the working state and the non-working state, so that all the polarization states in the echo signal light can be reflected by the polarization beam splitter to the signal detection and data processing system, which makes up for the defect that the polarization beam splitter can only reflect the signal light in one polarization direction, so that the transceiver co-located polarization laser radar system can analyze all the polarization information of the polarized light in different directions in the echo signal light, which greatly expands the detection performance and application scope of the polarization laser radar.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technologies, and more particularly, to a co-located transceiver polarization lidar system based on an optical rotator. Background Art

[0002] Since the development of polarization lidar, it has shown superior performance in aspects such as atmospheric detection. Polarization lidar can effectively observe the spatio-temporal distribution and optical properties of non-spherical particles in the atmosphere, and deduce atmospheric environments such as wind fields and dust.

[0003] Due to the powerful detection performance of polarization lidar, it has developed rapidly and achieved fruitful results. For example, the dual-wavelength three-channel lidar deployed in China's Meridian Project can obtain the atmospheric backscattering echo signal from near the ground to 110 km, and then invert parameters such as the density, temperature, and sodium layer density of the middle and upper atmosphere. The lidar network built by the European EARLINET program is used to monitor and study the transport characteristics of atmospheric aerosols and their impact on climate in a large area of Europe. Currently, a relatively complete polarization-mie lidar deployment has been achieved. Polarization lidar technology can complement a variety of advanced detection means and continuously improve the detection ability. The team of the University of Science and Technology of China combined superconducting technology with polarization lidar, effectively utilized the advantages of superconducting detectors such as high sensitivity, low noise, and high speed, and achieved high spatio-temporal resolution detection of continuous urban atmospheric aerosols and depolarization ratios. The team of Peking University proposed to use polarization detection to obtain clearer information on the essential differences of targets, and thus combined polarization remote sensing and lidar technology, which can not only further improve the accuracy and quantification level of ground object recognition, but also solve many bottleneck problems in earth remote sensing observation.

[0004] In addition, with the development of technologies such as atmospheric detection, ocean detection, aerospace, etc., and the maturity of the miniaturization technology of various radar components, polarization lidar has been extended to more and more fields: The 355-532 nm dual-wavelength fluorescence-Raman-elastic scattering lidar of the US AOL system is used to detect seawater optical parameters. The Italian FLIDAR-P system integrates functions such as detecting seawater elastic scattering, Raman scattering, and fluorescence characteristics, enriching the detection modes of ocean lidar. Spaceborne polarization lidar has great detection potential. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) jointly planned by the United States and France loaded a dual-wavelength orthogonally polarized cloud-aerosol lidar on a satellite to achieve spaceborne detection of clouds and aerosols by polarization lidar, and obtained many excellent observation results.

[0005] Traditional polarization lidars use transmit-receive separated telescopes, which require two sets of telescopes, a transmitting telescope and a receiving telescope. When receiving the signal light beam, since the polarization beam splitter only allows light with specific polarization directions to be reflected and transmitted, two detectors are needed to detect the signals of two polarization states in the received signal light beam, which greatly limits the cost and stability of the polarization lidar. Summary of the Invention

[0006] In view of this, the present invention provides a transmit-receive co-located polarization lidar system based on an optical rotator, and the technical solution is as follows:

[0007] A transmit-receive co-located polarization lidar system based on an optical rotator, the transmit-receive co-located polarization lidar system includes:

[0008] A pulsed laser, a polarization beam splitter, an optical rotator, a telescope, and a signal detection and data processing system, the polarization beam splitter can transmit the signal light of the parallel polarization state and reflect the signal light of the vertical polarization state;

[0009] The pulsed laser is used to generate the outgoing signal light of the parallel polarization state, and the outgoing signal light sequentially passes through the polarization beam splitter and the optical rotator and exits from the telescope;

[0010] The echo signal light obtained based on the outgoing signal light includes the signal light of the parallel polarization state and the signal light of the vertical polarization state;

[0011] During the reception process of the echo signal light, in the first time period, the optical rotator is in the non-working state, and the signal light of the vertical polarization state passes through the telescope and the optical rotator to reach the polarization beam splitter, and the polarization beam splitter reflects the signal light of the vertical polarization state to the signal detection and data processing system; in the second time period, the optical rotator is in the working state, and the signal light of the parallel polarization state passes through the telescope to reach the optical rotator, and the optical rotator is used to adjust the polarization plane of the signal light of the parallel polarization state, so that the polarization state of the signal light of the parallel polarization state changes from the parallel polarization state to the vertical polarization state, and the polarization beam splitter reflects the signal light of the vertical polarization state to the signal detection and data processing system.

[0012] Optionally, in the above-mentioned transmit-receive co-located polarization lidar system, the outgoing signal light is linearly polarized light.

[0013] Optionally, in the above-mentioned transmit-receive co-located polarization lidar system, the telescope is a transmit-receive co-located telescope.

[0014] Optionally, in the above-mentioned transmit-receive co-located polarization lidar system, the echo signal light is elliptically polarized light.

[0015] Optionally, in the above-mentioned co-located polarization lidar system, the optical rotator is a Faraday rotator.

[0016] Optionally, in the above-mentioned co-located polarization lidar system, the co-located polarization lidar system further includes:

[0017] An amplifier for amplifying the signal power of the outgoing signal light.

[0018] Optionally, in the above-mentioned co-located polarization lidar system, the amplifier is an erbium-doped fiber amplifier.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] A co-located polarization lidar system based on an optical rotator provided by the present invention includes a pulsed laser, a polarization beam splitter, an optical rotator, a telescope, and a signal detection and data processing system. The polarization beam splitter can transmit the signal light in the parallel polarization state and reflect the signal light in the vertical polarization state. The pulsed laser is used to generate the outgoing signal light in the parallel polarization state. The outgoing signal light passes through the polarization beam splitter and the optical rotator in sequence and exits from the telescope. The echo signal light obtained based on the outgoing signal light includes the signal light in the parallel polarization state and the signal light in the vertical polarization state. During the reception of the echo signal light, in the first time period, the optical rotator is in the non-operating state, and the signal light in the vertical polarization state passes through the telescope and the optical rotator to reach the polarization beam splitter. The polarization beam splitter reflects the signal light in the vertical polarization state to the signal detection and data processing system. In the second time period, the optical rotator is in the operating state, and the signal light in the parallel polarization state passes through the telescope to reach the optical rotator. The optical rotator is used to adjust the polarization plane of the signal light in the parallel polarization state, so that the polarization state of the signal light in the parallel polarization state changes from the parallel polarization state to the vertical polarization state. The polarization beam splitter reflects the signal light in the vertical polarization state to the signal detection and data processing system. In this co-located polarization lidar system, the echo signal light obtained based on the outgoing signal light generated by the pulsed laser includes the signal light in the parallel polarization state and the signal light in the vertical polarization state. Since the polarization beam splitter cannot reflect the signal light in the parallel polarization state, the optical rotator is used to rotate the polarization plane of the echo signal light to adjust the polarization state of the echo signal light. By making the optical rotator be in the operating and non-operating states respectively, all polarization states in the echo signal light can be reflected by the polarization beam splitter to the signal detection and data processing system, making up for the defect that the polarization beam splitter can only reflect the signal light in one polarization direction, so that this co-located polarization lidar system can analyze all polarization information of the polarized light in different directions in the echo signal light, greatly expanding the detection performance and application range of this polarization lidar. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0022] Figure 1 It is a schematic structural diagram of a transceiver-separated polarization lidar system in the prior art;

[0023] Figure 2 It is a schematic structural diagram of a transceiver-collocated polarization lidar system in the prior art;

[0024] Figure 3 It is a schematic structural diagram of a transceiver-collocated polarization lidar system based on an optical rotator provided by an embodiment of the present invention;

[0025] Figure 4 It is a schematic optical path diagram of a polarization beam splitter of a transceiver-collocated polarization lidar system based on an optical rotator provided by an embodiment of the present invention;

[0026] Figure 5 It is a schematic optical path diagram of a polarization beam splitter of another transceiver-collocated polarization lidar system based on an optical rotator provided by an embodiment of the present invention;

[0027] Figure 6 It is a schematic optical path diagram of a polarization beam splitter of yet another transceiver-collocated polarization lidar system based on an optical rotator provided by an embodiment of the present invention. Detailed implementation manners

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] Based on the content recorded in the background art, the transceiver system structure of a polarization lidar can be divided into transceiver-separated and transceiver-collocated.

[0030] For a traditional transceiver-separated polarization lidar, the positions and angles of its transmitting telescope and receiving telescope must be precisely adjusted to achieve better performance. Moreover, the cost of its transceiver system is high, and the transmitting system and the receiving system each have a set of independent optical paths. The equipment costs and maintenance costs of the two systems are much higher than those of a single-telescope system. Refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a transceiver-separated polarization lidar system in the prior art. In a transceiver-separated polarization lidar, the transmitting and receiving telescopes are separated. By reasonably setting and measuring the geometric overlap factor between the two, the polarization intensities of the echoes in different polarization directions can be extracted from the received signals. In a traditional transceiver-separated polarization lidar system, a continuous laser generates polarized light, which is power-amplified by an amplifier and then emitted by a telescope after passing through an isolator. The signal laser encounters a target and scatters an echo. The receiving telescope collects the echo signal. When the signal light passes through a Polarization Beam Spliter (PBS), the vertically polarized state and the horizontally polarized state are separated and enter two optical fibers. The two polarized lights are respectively collected by detectors to form two electrical signals, which then enter the signal acquisition and data processing system. Since adjusting the coaxiality of the optical axes of the transmitting and receiving telescopes and adjusting the sufficient overlapping area of their fields of view for the target is a complex process, and this balanced state is unstable and vulnerable to the environment where the telescopes are located.

[0031] For traditional co-located transceiver polarization lidars, refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a co-located transceiver polarization lidar system in the prior art. In a traditional co-located transceiver polarization lidar, the same telescope barrel is used for both signal transmission and reception, and the receiving and transmitting optical paths are separated by time-division multiplexing. In a traditional co-located transceiver polarization lidar system, signals are transmitted or received in a time-division manner within a single pulse period. During the signal transmission time, a pulsed laser emits a polarized pulsed laser, and its polarization state is denoted as P. This P-polarized light forms a signal light after passing through an amplifier. The form of the polarization beam splitter is set so that the P-polarized light can pass through. After passing through a quarter-wave plate, it becomes a circularly polarized signal light and is emitted by the telescope. The scattered signal light is collected by the telescope. The S-polarized light can be obtained after passing through the quarter-wave plate. This S-polarized light is reflected by the polarization beam splitter and enters the detector and the signal detection and data processing system. When receiving the signal light, since the polarization beam splitter only allows light of a specific polarization direction to be reflected and transmitted, only the component of the received signal beam in one polarization direction can be detected.

[0032] Currently, Japanese scholars have used two polarization beam splitters (PBS) and a Faraday rotator to achieve the separation of polarized light in different directions of the lidar echo signal and verified its functionality in the spatial optical path. However, the optical path of this system is relatively complex, so it has not been widely used, and there is no similar all-fiber system implemented.

[0033] Based on this, in an embodiment of the present invention, a co-located polarization lidar system based on an optical rotator is provided. The co-located polarization lidar system includes a pulsed laser, a polarization beam splitter, an optical rotator, a telescope, and a signal detection and data processing system. The polarization beam splitter can transmit the signal light in the parallel polarization state and reflect the signal light in the perpendicular polarization state. The pulsed laser is used to generate the outgoing signal light in the parallel polarization state. The outgoing signal light sequentially passes through the polarization beam splitter and the optical rotator and exits from the telescope. The echo signal light obtained based on the outgoing signal light includes the signal light in the parallel polarization state and the signal light in the perpendicular polarization state. During the reception process of the echo signal light, within the first time period, the optical rotator is in the non-operating state, and the signal light in the perpendicular polarization state passes through the telescope and the optical rotator to reach the polarization beam splitter. The polarization beam splitter reflects the signal light in the perpendicular polarization state to the signal detection and data processing system. Within the second time period, the optical rotator is in the operating state, and the signal light in the parallel polarization state passes through the telescope to reach the optical rotator. The optical rotator is used to adjust the polarization plane of the signal light in the parallel polarization state, so that the polarization state of the signal light in the parallel polarization state changes from the parallel polarization state to the perpendicular polarization state. The polarization beam splitter reflects the signal light in the perpendicular polarization state to the signal detection and data processing system. In this co-located polarization lidar system, the echo signal light obtained based on the outgoing signal light generated by the pulsed laser includes the signal light in the parallel polarization state and the signal light in the perpendicular polarization state. Since the polarization beam splitter cannot reflect the signal light in the parallel polarization state, an optical rotator is used to rotate the polarization plane of the echo signal light to adjust the polarization state of the echo signal light. By respectively making the optical rotator in the operating and non-operating states, all polarization states in the echo signal light can be reflected by the polarization beam splitter to the signal detection and data processing system, making up for the defect that the polarization beam splitter can only reflect the signal light in one polarization direction, enabling this co-located polarization lidar system to analyze all polarization information of the polarized light in different directions in the echo signal light, and greatly expanding the detection performance and application range of this polarization lidar.

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Refer to Figure 3 , Figure 3 which is a schematic structural diagram of a co-located polarization lidar system based on an optical rotator provided by an embodiment of the present invention.

[0036] A co-located polarization lidar system based on an optical rotator, the co-located polarization lidar system includes:

[0037] A pulsed laser 11, a polarization beam splitter 13, an optical rotator 14, a telescope 15, and a signal detection and data processing system 16. The polarization beam splitter 13 can transmit the signal light in the parallel polarization state 19 and reflect the signal light in the perpendicular polarization state 20.

[0038] The pulsed laser 11 is used to generate the outgoing signal light 17 in the parallel polarization state 19. The outgoing signal light 17 passes through the polarization beam splitter 13 and the optical rotator 14 in sequence and exits from the telescope 15.

[0039] The echo signal light 18 obtained based on the outgoing signal light 17 includes the signal light in the parallel polarization state 19 and the signal light in the perpendicular polarization state 20.

[0040] During the reception of the echo signal light 18, in the first time period, the optical rotator 14 is in an inoperative state. The signal light in the perpendicular polarization state 20 passes through the telescope 15 and the optical rotator 14 and reaches the polarization beam splitter 13. The polarization beam splitter 13 reflects the signal light in the perpendicular polarization state 20 to the signal detection and data processing system 16. In the second time period, the optical rotator 14 is in an operative state. The signal light in the parallel polarization state 19 passes through the telescope 15 and reaches the optical rotator 14. The optical rotator 14 is used to adjust the polarization plane of the signal light in the parallel polarization state 19, so that the polarization state of the signal light in the parallel polarization state 19 changes from the parallel polarization state 19 to the perpendicular polarization state 20. The polarization beam splitter 13 reflects the signal light in the perpendicular polarization state 20 to the signal detection and data processing system 16.

[0041] In this embodiment, in the direction of the outgoing signal light 17 generated by the pulsed laser 11, a polarization beam splitter 13, an optical rotator 14, and a telescope 15 are arranged in sequence. A signal detection and data processing system 16 is arranged in the direction where the polarization beam splitter 13 reflects the signal light.

[0042] Further, referring to Figure 4 , Figure 4 is a schematic optical path diagram of the polarization beam splitter of a co-located polarization lidar system based on an optical rotator provided by an embodiment of the present invention.

[0043] The outgoing signal light 17 in the parallel polarization state 19 generated by the pulsed laser 11 is pulsed laser. When the outgoing signal light 17 exits, since the polarization beam splitter 13 transmits the signal light in the parallel polarization state 19 and reflects the signal light in the perpendicular polarization state 20, the outgoing signal light 17 will pass through the polarization beam splitter 13.

[0044] The outgoing signal light 17 is transmitted through the polarization beam splitter 13, passes through the optical rotator 14, and then exits through the telescope 15 and enters the atmosphere. When the object to be detected in the atmosphere encounters the outgoing signal light 17, the outgoing signal light 17 will be reflected to form an echo signal light 18.

[0045] Since the polarization state of the outgoing signal light 17 changes during reflection, the echo signal light 18 contains two different polarization states, that is, the signal light with parallel polarization state 19 and the signal light with perpendicular polarization state 20. After the echo signal light 18 is received by the telescope 15, it passes through the optical rotator 14 and reaches the polarization beam splitter 13.

[0046] During the reception of the echo signal light 18, since the echo signal light 18 includes signal lights with two different polarization states, the optical rotator 14 is used for optical rotation to reflect all the echo signal lights 18 into the signal detection and data processing system 16. At this time, there will be two different time periods.

[0047] Reference Figure 5 , Figure 5 is a schematic optical path diagram of the polarization beam splitter of another co-located polarization lidar system based on an optical rotator provided by an embodiment of the present invention.

[0048] Reference Figure 6 , Figure 6 is a schematic optical path diagram of the polarization beam splitter of yet another co-located polarization lidar system based on an optical rotator provided by an embodiment of the present invention.

[0049] During the first time period, the optical rotator 14 is in a non-operating state. At this time, the outgoing signal light 17 with parallel polarization state 19 is emitted by the pulsed laser 11, passes through the polarization beam splitter 13 as shown in Figure 4 , then passes through the optical rotator 14 and the telescope 15 and enters the atmosphere. After being reflected by the detection object, the echo signal light 18 enters the telescope 15. At this time, the optical rotator 14 is not operating, and the signal light with parallel polarization state 19 and the signal light with perpendicular polarization state 20 both pass through the optical rotator 14 and reach the polarization beam splitter 13. As shown in Figure 6 , the polarization beam splitter 13 transmits the signal light with parallel polarization state 19 and does not enter the signal detection and data processing system 16. As shown in Figure 5 , the polarization beam splitter 13 reflects the signal light with perpendicular polarization state 20 and enters the signal detection and data processing system 16. The signal detection and data processing system 16 only performs signal acquisition and data processing on the signal light with perpendicular polarization state 20.

[0050] During the second time period, the optical rotator 14 is in the working state. At this time, through the reflection of the detection object, the echo signal light 18 enters the telescope 15. Since the optical rotator 14 is in the working state at this time, the polarization state of the signal light in the parallel polarization state 19 is rotated and changed by the optical rotator 14, and the signal light in the parallel polarization state 19 is changed into the signal light in the vertical polarization state 20, as Figure 5 shown. The polarization beam splitter 13 reflects the signal light in the vertical polarization state 20 into the signal detection and data processing system 16. The signal detection and data processing system 16 only performs signal acquisition and data processing on the signal light in the vertical polarization state 20. At this time, since the polarization state of the signal light in the vertical polarization state 20 is changed by the optical rotator 14, it does not enter the signal detection and data processing system 16.

[0051] Optionally, the outgoing signal light 17 is linearly polarized light.

[0052] In this embodiment, when the pulsed laser 11 generates the outgoing signal light 17, the outgoing signal light 17 is set as linearly polarized light, so that the outgoing signal light 17 is single and the device is simpler. Then the polarization state of the outgoing signal light 17 in the parallel polarization state 19 is set as the parallel polarization state. Since the polarization beam splitter 13 transmits the light in the parallel polarization state, the outgoing signal light 17 can directly pass through the polarization beam splitter 13 when it exits, and the entire outgoing system will also become relatively simple.

[0053] Optionally, the telescope 15 is a transceiver co-located telescope.

[0054] In this embodiment, the transceiver co-located telescope can respectively transmit and receive signal light in the same lens barrel.

[0055] Optionally, the echo signal light 18 is elliptically polarized light.

[0056] In this embodiment, it should be noted that the echo signal light 18 includes the signal light in the parallel polarization state 19 and the signal light in the vertical polarization state 20. The signal light in the parallel polarization state 19 and the signal light in the vertical polarization state 20 are combined into elliptically polarized light.

[0057] Optionally, the optical rotator 14 is a Faraday optical rotator.

[0058] In this embodiment, it should be noted that the optical rotator 14 can adopt a Faraday optical rotator, or other optical rotators 14, or other optical rotation devices can also be used to perform optical rotation on it. In this embodiment, only the Faraday optical rotator is taken as an example, and no specific limitation is made.

[0059] When the optical rotator 14 performs optical rotation, a time-division multiplexing technique is adopted. Since the output signal light 17 generated by the pulsed laser 11 is pulsed laser, there will be a certain interval for the output signal light 17. The optical rotator 14 collects the signal light with parallel polarization state 19 and the signal light with perpendicular polarization state 20 in different time periods, and then the signal detection and data processing system 16 processes the signal light with parallel polarization state 19 and the signal light with perpendicular polarization state 20 collected at different times, and all polarization information of the signal light with parallel polarization state 20 and the signal light with perpendicular polarization state 20 can be obtained. By collecting multiple groups of data for comparative analysis, parameters such as depolarization ratio can be obtained, and atmospheric parameters can be calculated and inverted.

[0060] According to all the above embodiments, when the echo signal light 18 passes through the optical rotator 14, since the polarization beam splitter 13 can only reflect the light in one polarization direction, by adjusting whether the optical rotator 14 is in the working state, the polarization state of the signal light with parallel polarization state 19 can be adjusted. For example, when the rotation angle of the optical rotator 14 is 0 degrees, the optical rotator 14 is in the non-working state, and the echo signal light 18 all passes through the optical rotator. The polarization beam splitter 13 can only reflect the signal light with perpendicular polarization state 20, and the signal light with parallel polarization state 19 is transmitted. When the rotation angle of the optical rotator 14 is 90 degrees, the optical rotator 14 is in the working state, and the signal light with parallel polarization state 19 in the echo signal light 18 is rotated by the optical rotator into the signal light with perpendicular polarization state 20, so that the polarization information of the signal light with parallel polarization state 19 enters the signal detection and data processing system 16, and the signal light with perpendicular polarization state 20 is rotated by the optical rotator into polarized light with other polarization states.

[0061] Optionally, the co-located polarization lidar system further includes:

[0062] An amplifier 12, and the amplifier 12 is used to amplify the signal power of the output signal light 17.

[0063] In this embodiment, the amplifier 12 amplifies the output signal light with parallel polarization state 19 into a signal light with a larger power, so that a sufficiently large signal can be received after being reflected by the object to be detected.

[0064] Optionally, the amplifier 12 is an erbium-doped fiber amplifier (EDFA).

[0065] In this embodiment, the use of the erbium-doped fiber amplifier EDFA can directly amplify the optical signal, breaking through the limitation of the original optical / electrical / optical mode for amplifying the optical signal, making long-distance, large-capacity, and high-speed fiber optic communication possible.

[0066] It should be noted that the erbium-doped fiber amplifier (EDFA) compensates the power of the signal light emitted by the pulsed laser 11. In this embodiment, only the erbium-doped fiber amplifier (EDFA) is taken as an example. Other amplifiers 12 can also be used, or other optical signal amplification devices can be used to amplify the optical signal, without specific limitation.

[0067] The above has introduced in detail a co-located polarization lidar system based on an optical rotator provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0068] It should be noted that the various embodiments in this specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices 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 description of the method part.

[0069] It also should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements inherent to the process, method, article or device, but also other elements inherent to these process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0070] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A co-located polarization lidar system based on an optical rotator, characterized in that, the co-located polarization lidar system includes: a pulsed laser, a polarization beam splitter, an optical rotator, a telescope, and a signal detection and data processing system, where the polarization beam splitter can transmit the signal light in the parallel polarization state and reflect the signal light in the perpendicular polarization state; the pulsed laser is used to generate the outgoing signal light in the parallel polarization state, and the outgoing signal light sequentially passes through the polarization beam splitter and the optical rotator and exits from the telescope; the echo signal light obtained based on the outgoing signal light includes the signal light in the parallel polarization state and the signal light in the perpendicular polarization state; during the reception process of the echo signal light, within the first time period, the optical rotator is in a non-operating state, and the signal light in the perpendicular polarization state passes through the telescope and the optical rotator to reach the polarization beam splitter, and the polarization beam splitter reflects the signal light in the perpendicular polarization state to the signal detection and data processing system; within the second time period, the optical rotator is in an operating state, and the signal light in the parallel polarization state passes through the telescope to reach the optical rotator, and the optical rotator is used to adjust the polarization plane of the signal light in the parallel polarization state so that the polarization state of the signal light in the parallel polarization state changes from the parallel polarization state to the perpendicular polarization state, and the polarization beam splitter reflects the signal light in the perpendicular polarization state to the signal detection and data processing system.

2. The co-located polarization lidar system according to claim 1, characterized in that, the outgoing signal light is linearly polarized light.

3. The co-located polarization lidar system according to claim 1, characterized in that, the telescope is a co-located telescope.

4. The co-located polarization lidar system according to claim 1, characterized in that, the echo signal light is elliptically polarized light.

5. The co-located polarization lidar system according to claim 1, characterized in that, the optical rotator is a Faraday rotator.

6. The co-located polarization lidar system according to claim 1, characterized in that, the co-located polarization lidar system further includes: an amplifier, and the amplifier is used to amplify the signal power of the outgoing signal light.

7. The co-located polarization lidar system according to claim 6, characterized in that, the amplifier is an erbium-doped fiber amplifier.

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