Echo receiving system and laser radar

Abstract

The invention relates to an echo receiving system and a laser radar, which can effectively receive echo light with different polarization states so as to maximally utilize the echo light and ensure the detection capability of the laser radar. The echo receiving system comprises: a deflection scanning device; a polarizing beam splitter provided in a receiving / transmitting optical path of the deflection scanning device; the polarization modulation light splitting assembly is correspondingly arranged in a light path between the deflection scanning device and the polarization light splitter and is used for reflecting third polarized light in the echo light in a polarization state in a modulatable manner so as to form first polarized light; fourth polarized light in the echo light can be transmitted in a polarization state modulation manner so as to form second polarized light to be transmitted to the polarization beam splitter; and the echo detection assembly is correspondingly arranged on the reflection sides of the polarization beam splitter and the polarization modulation beam splitting assembly, and is used for receiving the second polarized light reflected by the polarization beam splitter and the first polarized light reflected and modulated by the polarization modulation beam splitting assembly for detection.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to an echo receiving system and a laser radar. Background Art

[0002] Frequency modulated continuous wave (FMCW) laser radar is a device that uses the interference between the local oscillator light of a linear scanning light source and the echo light to obtain the frequency difference, and then calculates the distance / speed of the target. In order to establish a coaxial optical path, existing FMCW laser radars usually need to be equipped with optical devices such as circulators. However, if the circulator uses a fiber coupling solution, the stress change of the optical fiber will disturb the polarization state of the echo optical link, thereby affecting the stability of the interferometric measurement.

[0003] In order to solve this problem, the prior art provides a LIDAR system with a multimode waveguide photodetector, which realizes the role of a circulator by combining a PBS (polarization beam splitter) with a free-space optical device. Although it will not disturb the polarization state of the echo optical link, the polarization change of the signal light by the target is unknown. If the polarization state of the echo light when it returns from the target to the polarization beam splitter happens to be P light, no echo light will be reflected by the polarization beam splitter to the photodetector, resulting in the LIDAR system being unable to obtain effective detection results. Summary of the invention

[0004] One advantage of the present invention is that it provides an echo receiving system and a laser radar, which can effectively receive echo light with different polarization states so as to maximize the use of the echo light and ensure the detection capability of the laser radar.

[0005] Another advantage of the present invention is that it provides an echo receiving system and a laser radar, wherein, in one embodiment of the present invention, the echo receiving system can respectively detect the P polarization component and the S polarization component in the echo light, which can not only realize the maximum efficiency detection of any echo polarization state, but also realize the analysis of the material of the target object.

[0006] Another advantage of the present invention is to provide an echo receiving system and a laser radar, wherein, in one embodiment of the present invention, the laser radar can share the same set of coaxial light transmitting and receiving circuit hardware to effectively reduce costs.

[0007] Another advantage of the present invention is to provide an echo receiving system and a laser radar, wherein, in one embodiment of the present invention, the laser radar can achieve the function of multiple transmission and multiple reception without additional cost.

[0008] Another advantage of the present invention is to provide an echo receiving system and a laser radar, wherein in order to achieve the above-mentioned purpose, no expensive materials or complicated structures are required in the present invention. Therefore, the present invention successfully and effectively provides a solution, not only providing a simple echo receiving system and a laser radar, but also increasing the practicality and reliability of the echo receiving system and the laser radar.

[0009] In order to achieve at least one of the above advantages or other advantages and purposes of the present invention, the present invention provides an echo receiving system, comprising:

[0010] A deflection scanning device having a light receiving and light emitting path and a plurality of scanning light paths corresponding to the light receiving and light emitting path;

[0011] a polarization beam splitter, arranged in the light-receiving and light-emitting path of the deflection scanning device, for transmitting the first polarized light propagating along the light-receiving and light-emitting path, and reflecting the second polarized light whose polarization direction is perpendicular to the first polarized light;

[0012] a polarization modulation splitting component, which is correspondingly arranged in the optical path between the deflection scanning device and the polarization beam splitter, and is used for modulating the polarization state to reflect the third polarized light in the echo light deflected by the deflection scanning device to form the first polarized light, and modulating the polarization state to transmit the fourth polarized light in the echo light deflected by the deflection scanning device, which is perpendicular to the polarization direction of the third polarized light, to form the second polarized light and propagate to the polarization beam splitter; and

[0013] The echo detection component is correspondingly arranged on the reflection side of the polarization beam splitter and the polarization modulation beam splitter component, and is used to receive the second polarized light reflected by the polarization beam splitter and the first polarized light reflected and modulated by the polarization modulation beam splitter component for detection.

[0014] According to an embodiment of the present application, the polarization modulation beam splitting component is further used to transmit the first polarized light from the polarization beam splitter in a modulated polarization state to form the fourth polarized light to propagate to the deflection scanning device.

[0015] According to one embodiment of the present application, the polarization modulation spectrometer component includes a non-reciprocal polarization rotator, a first polarization spectrometer element and a first phase delay element. The non-reciprocal polarization rotator and the first polarization spectrometer element are arranged in sequence in the optical path between the polarization spectrometer and the deflection scanning device. The non-reciprocal polarization rotator is used to rotate the polarization direction of the first polarized light from the polarization spectrometer by 0° to form the first polarized light propagating to the first polarization spectrometer element, and to rotate the polarization direction of the first polarized light from the first polarization spectrometer element by 90° to form the second polarized light propagating to the polarization spectrometer; the first phase delay element is arranged on the reflection side of the first polarization spectrometer element, and is used to delay the phase of the second polarized light reflected by the first polarization spectrometer element to form the first polarized light.

[0016] According to one embodiment of the present application, the non-reciprocal polarization rotator includes a polarization rotation element and a Faraday rotator element which are sequentially arranged in an optical path between the polarization beam splitter and the first polarization beam splitter element; the polarization rotation element is used to rotate the transmitted light propagating to the Faraday rotator element by -45° relative to the polarization direction of the incident light from the polarization beam splitter, and to rotate the transmitted light propagating to the polarization beam splitter by +45° relative to the polarization direction of the incident light from the Faraday rotator element; the Faraday rotator element is used to rotate the transmitted light by +45° relative to the polarization direction of the incident light.

[0017] According to an embodiment of the present application, the polarization beam splitter and the first polarization beam splitting element are both PBS prisms arranged horizontally in the transmission direction, and are used to transmit P light and reflect S light.

[0018] According to one embodiment of the present application, the polarization modulation spectrometer component includes a first Faraday rotator, a second Faraday rotator and a second polarization spectrometer element, the first Faraday rotator and the second polarization spectrometer element are arranged in sequence in the optical path between the polarization spectrometer and the deflection scanning device, and the second Faraday rotator is correspondingly arranged on the reflection side of the second polarization spectrometer element; the first Faraday rotator and the second Faraday rotator are both used to rotate the transmitted light by +45° relative to the polarization direction of the incident light, and the second polarization spectrometer element is used to transmit +45° linearly polarized light and reflect -45° linearly polarized light.

[0019] According to an embodiment of the present application, the second polarization beam splitting element is a PBS prism arranged with a transmission direction inclined at +45°.

[0020] According to one embodiment of the present application, the echo detection component includes a first detection component, a second detection component and a detection result analysis module; the first detection component corresponds to the polarization modulation spectrometer component, and is used to receive and detect the first polarized light from the polarization modulation spectrometer component to obtain a first detection result; the second detection component corresponds to the polarization spectrometer, and is used to receive and detect the second polarized light from the polarization spectrometer to obtain the second detection result.

[0021] According to one embodiment of the present application, the first detection component includes a first mixer and a first balanced detector, the first mixer corresponds to the polarization modulation spectrometer component, and is used to interfere the echo light from the polarization modulation spectrometer component with the local oscillator light from the laser emission system to form an interference signal; the first balanced detector is simultaneously connected to the first mixer and the detection result analysis module, and is used to perform interference measurement on the interference signal from the first mixer to obtain a first detection result output to the detection result analysis module.

[0022] According to one embodiment of the present application, the second detection component includes a second mixer, a second balanced detector and a second phase delay element, the second phase delay element is not connected to the reflection side of the polarization splitter, and is used to delay the phase of the second polarized light reflected by the polarization splitter to form the first polarized light; the second mixer corresponds to the second phase delay element, and is used to make the echo light from the second phase delay element interfere with the local oscillator light from the laser emission system to form an interference signal; the second balanced detector is connected to the second mixer and the detection result analysis module at the same time, and is used to perform interference measurement on the interference signal from the second mixer to obtain a second detection result output to the detection result analysis module.

[0023] According to another aspect of the present application, the present application further provides a laser radar, including:

[0024] A laser emission system for emitting signal light to a target object so as to be reflected by the target object to form echo light; and

[0025] Any of the above-mentioned echo receiving systems is used to receive echo light from the target object to detect the target object.

[0026] According to one embodiment of the present application, the laser emitting system includes a polarization laser emitting component for emitting a first polarized light and a beam splitting component for splitting a light beam propagating along a main optical path into light beams propagating along multiple branch optical paths; the polarization laser emitting component is located in the main optical path of the beam splitting component, and the polarization beam splitter and echo detection component in the echo receiving system are respectively located in the branch optical paths of the beam splitting component.

[0027] According to one embodiment of the present application, the laser emission system further includes a linearity correction module, which is located in a branch optical path of the beam splitting component and is used to receive the local oscillator light split by the beam splitting component to correct the frequency linearity of the polarized laser emission component.

[0028] According to one embodiment of the present application, the beam splitting assembly is a 1×4 beam splitter or is composed of three 1×2 beam splitters connected in series.

[0029] According to one embodiment of the present application, the number of first detection components and second detection components in the echo detection component is N; the laser emission system further includes a polarization-maintaining optical amplifier located in the optical path between the polarization laser emission component and the beam splitting component; the beam splitting component includes a 1×3 beam splitter whose input end is connected to the polarization laser emission component, a 1×N beam splitter whose input end is connected to the 1×3 beam splitter, and a 1×2N beam splitter whose input end is connected to the 1×3 beam splitter; the linearity correction module is connected to an output end of the 1×3 beam splitter; the N output ends of the 1×N beam splitter are all connected to the polarization beam splitter; the 2N output ends of the 1×2N beam splitter are respectively connected to the N first mixers of the first detection components and the N second mixers of the second detection components in a one-to-one correspondence.

[0030] According to one embodiment of the present application, the polarized laser emitting component is a first frequency-sweeping laser for directly emitting the first polarized light;

[0031] Alternatively, the polarized laser emitting assembly comprises a second frequency-sweeping laser for directly emitting second polarized light and a third phase delay element for converting the second polarized light into first polarized light, wherein the third phase delay element is located in the optical path between the second frequency-sweeping laser and the beam splitting assembly;

[0032] Alternatively, the polarized laser emitting assembly includes a third frequency-sweeping laser for directly emitting mixed polarized light and a polarizer for obtaining the first polarized light from the mixed polarized light, and the polarizer is located in the optical path between the third frequency-sweeping laser and the beam splitting assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic block diagram of a laser radar according to an embodiment of the present invention;

[0034] Figure 2 A first example of a laser radar according to the above embodiment of the present invention is shown;

[0035] Figure 3A second example of the laser radar according to the above embodiment of the present invention is shown;

[0036] Figure 4 A third example of the laser radar according to the above embodiment of the present invention is shown;

[0037] Figure 5 A fourth example of the laser radar according to the above embodiment of the present invention is shown;

[0038] Figure 6 A fifth example of the laser radar according to the above embodiment of the present invention is shown;

[0039] Figure 7 A schematic diagram of an optical path of a laser radar according to the fifth example of the present invention is shown;

[0040] Figure 8 A sixth example of the laser radar according to the above-described embodiment of the present invention is shown.

[0041] Main component symbol description: 1. Laser radar; 10. Laser emission system; 11. Polarized laser emission assembly; 111. First frequency-sweeping laser; 112. Second frequency-sweeping laser; 113. Third phase delay element; 114. Third frequency-sweeping laser; 115. Polarizer; 12. Beam splitting assembly; 1201. Trunk optical path; 1202. Branch optical path; 121. 1×4 beam splitter; 122. 1×2 beam splitter; 123. 1×3 beam splitter; 124. 1×N beam splitter; 125. 1×2N beam splitter; 13. Linearity correction module; 14. Polarization-maintaining amplifier; 20. Echo receiving system; 21. Deflection scanning device; 211. Transmitting and transmitting optical path; 212. Scanning optical path; 22, polarization beam splitter; 23, polarization modulation beam splitter component; 231, non-reciprocal polarization rotator; 2311, polarization rotation element; 2312, Faraday rotator element; 232, first polarization beam splitter element; 233, first phase delay element; 234, first Faraday rotator; 235, second Faraday rotator; 236, second polarization beam splitter element; 24, echo detection component; 241, first detection component; 2411, first mixer; 2412, first balanced detector; 242, second detection component; 2421, second mixer; 2422, second balanced detector; 2423, second phase delay element; 243, detection result analysis module.

[0042] The above description of the main component symbols is combined with the accompanying drawings and specific implementation methods to further illustrate the present invention in detail. DETAILED DESCRIPTION

[0043] 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.

[0044] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may be a central component at the same time.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0046] Considering that the polarization change of the target object to the signal light is unknown, if the polarization state of the echo light when it returns from the target object to the polarization beam splitter is exactly P light, no echo light will be reflected by the polarization beam splitter to the photodetector, resulting in the inability of the existing LIDAR system to obtain effective detection results. The present application provides an echo receiving system and a laser radar, which can effectively receive echo light with different polarization states, so as to maximize the use of the echo light and ensure the detection capability of the laser radar.

[0047] Specifically, refer to the attached Figures 1 to 8 As shown, an embodiment of the present invention provides a laser radar 1, which may include a laser emitting system 10 and an echo receiving system 20, wherein the laser emitting system 10 is used to emit signal light to a target object to be reflected by the target object to form echo light, and the echo receiving system 20 is used to receive the echo light from the target object and analyze it to achieve detection of the target object.

[0048] More specifically, if Figure 1 and Figure 2As shown, the echo receiving system 20 may include a deflection scanning device 21, a polarization beam splitter 22, a polarization modulation beam splitter component 23, and an echo detection component 24. The deflection scanning device 21 has a light receiving and transmitting path 211 and a plurality of scanning light paths 212 corresponding to the light receiving and transmitting path 211, and is used to deflect the propagation direction of the echo light propagating along different scanning light paths 212, so that the echo light propagates along the same light receiving and transmitting path 211. The polarization beam splitter 22 is disposed on the light receiving and transmitting path 211 of the deflection scanning device 21, and is used to transmit the first polarized light propagating along the light receiving and transmitting path 211, and reflect the second polarized light whose polarization direction is perpendicular to the first polarized light. The polarization modulation beam splitter component 23 is correspondingly arranged in the optical path between the deflection scanning device 21 and the polarization beam splitter 22, and is used to reflect the third polarized light in the echo light deflected by the deflection scanning device 21 in a modulated polarization state to form the first polarized light, and transmit the fourth polarized light in the echo light deflected by the deflection scanning device 21 in a modulated polarization state and perpendicular to the polarization direction of the third polarized light to form the second polarized light and propagate to the polarization beam splitter 22. The echo detection component 24 is correspondingly arranged on the reflection side of the polarization beam splitter 22 and the polarization modulation beam splitter component 23, and is used to receive the second polarized light reflected by the polarization beam splitter 22 and the first polarized light reflected and modulated by the polarization modulation beam splitter component for detection.

[0049] It is worth noting that although the target object is unknown to the polarization change of the signal light, that is, the polarization state of the echo light is often different from the polarization state of the local oscillator light, the echo receiving system 20 of the present application can simultaneously receive two polarized lights with mutually perpendicular polarization directions in the echo light for analysis, so as to maximize the use of the echo light and ensure the detection capability of the laser radar. In other words, if the third polarized light and the fourth polarized light are mixed in the echo light under the interference of the target object, the echo receiving system 20 can simultaneously receive the third polarized light and the fourth polarized light for analysis and detection; if there is only the third polarized light or the fourth polarized light in the echo light under the interference of the target object, the echo receiving system 20 can correspondingly receive the third polarized light or the fourth polarized light for analysis and detection, so as to achieve the most efficient detection of any echo polarization state.

[0050] In addition, the polarization modulation beam splitter component 23 is further used to transmit the first polarized light from the polarization beam splitter 22 in a modulated polarization state to form the fourth polarized light and propagate to the deflection scanning device 21; at the same time, the local oscillator light emitted by the laser emitting system 10 is implemented as the first polarized light, so that the local oscillator light emitted by the laser emitting system 10 can propagate along the light-receiving and light-emitting path 211 of the deflection scanning device 21 to sequentially pass through the polarization beam splitter 22 and the polarization modulation beam splitter component 23 to reach the deflection scanning device 21, and then propagate to the target object along the scanning light path 212 of the deflection scanning device 21 through the deflection scanning device 21. In this way, the laser emitting system 10 and the echo receiving system 20 in the laser radar 1 will share the deflection scanning device 21, the polarization beam splitter 22 and the polarization modulation beam splitter component 23, so that the emission path of the local oscillator light and the recovery path of the echo light are the same optical path, realizing the coaxial optical path transmission and reception function of the laser radar, which helps to reduce hardware and reduce costs.

[0051] For example, in the first example of the present application, Figure 2 As shown, the first polarized light can be implemented as P polarized light (P light for short), and correspondingly the second polarized light can be implemented as S polarized light (S light for short); at the same time, the third polarized light can be implemented as S light, and correspondingly the fourth polarized light can be implemented as P light.

[0052] Optionally, the polarization beam splitter 22 may be implemented as, but not limited to, a PBS prism arranged horizontally in the transmission direction, for transmitting P light and reflecting S light.

[0053] Alternatively, if Figure 1 and Figure 2 As shown, the polarization modulation splitter component 23 may include a non-reciprocal polarization rotator 231, a first polarization splitter element 232 and a first phase delay element 233. The non-reciprocal polarization rotator 231 and the first polarization splitter element 232 are sequentially arranged in the optical path between the polarization splitter 22 and the deflection scanning device 21; the non-reciprocal polarization rotator 231 is used to rotate the polarization direction of the first polarized light from the polarization splitter 22 by 0° to form the first polarized light propagating to the first polarization splitter element 232, and to rotate the polarization direction of the first polarized light from the first polarization splitter element 232 by 0° to form the first polarized light propagating to the first polarization splitter element 232, and to rotate the polarization direction of the first polarization light from the first polarization splitter element 232 by 0° to form the first polarized light propagating to the first polarization splitter element 232. The polarization direction of the first polarized light of the component 232 is rotated 90° to form a second polarized light propagating to the polarization beam splitter 22; the first polarization beam splitter element 232 is used to transmit the first polarized light and reflect the second polarized light; the first phase delay element 233 is arranged on the reflection side of the first polarization beam splitter element 232 to be located in the optical path between the first polarization beam splitter element 232 and the echo detection component 24, and is used to delay the phase of the second polarized light reflected by the first polarization beam splitter element 232 to form the first polarized light propagating to the echo detection component 24.

[0054] In this way, Figure 2 As shown, the P light emitted by the laser emission system 10 will successively pass through the polarization beam splitter 22, the non-reciprocal polarization rotator 231 and the first polarization beam splitter element 232 to propagate to the deflection scanning device 21, and then be deflected by the deflection scanning device 21 to propagate to the target object. At the same time, when the echo light deflected by the deflection scanning device 21 propagates to the first polarization beam splitter element 232, the S light in the echo light will first be reflected by the first polarization beam splitter element 232 to propagate to the first phase delay element 233, and then be delayed by the first phase delay element 233 to form the P light and propagate to the echo detection component 24; the P light in the echo light will first pass through the first polarization beam splitter element 232, and then be rotated by the non-reciprocal polarization rotator 231 to form the S light and propagate to the polarization beam splitter 22, and then be reflected by the polarization beam splitter 22 to propagate to the echo detection component 24.

[0055] Alternatively, if Figure 2 As shown, the non-reciprocal polarization rotator 231 may include a polarization rotation element 2311 and a Faraday rotator element 2312 sequentially arranged in the optical path between the polarization beam splitter 22 and the first polarization beam splitter element 232. The polarization rotation element 2311 is used to rotate the polarization direction of the transmitted light propagating to the Faraday rotator element 2312 by -45° relative to the incident light from the polarization beam splitter 22, and to rotate the polarization direction of the transmitted light propagating to the polarization beam splitter 22 by +45° relative to the incident light from the Faraday rotator element 2312; the Faraday rotator element 2312 is used to rotate the polarization direction of the transmitted light by +45° relative to the incident light.

[0056] In this way, Figure 2 As shown, the P light from the polarization beam splitter 22 first passes through the polarization rotation element 2311 to rotate by -45°, and then passes through the Faraday rotator element 2312 to rotate by +45°, so that the P light from the polarization beam splitter 22 is still P light after passing through the polarization rotation element 2311 and the Faraday rotator element 2312 in succession, so as to be transmitted to the first polarization beam splitter 232; at the same time, the P light from the first polarization beam splitter 232 first passes through the Faraday rotator element 2312 to rotate by +45°, and then passes through the polarization rotation element 2311 to rotate by +45°, so that the P light from the first polarization beam splitter 232 is converted into S light after passing through the Faraday rotator element 2312 and the polarization rotation element 2311 in succession, so as to be transmitted to the polarization beam splitter 22.

[0057] Optionally, the polarization rotation element 2311 may be, but is not limited to, implemented as a specially designed half-wave plate for positively rotating the polarization direction of light incident from a first direction by 45°, and negatively rotating the polarization direction of light incident from a second direction opposite to the first direction by 45°.

[0058] Optionally, the Faraday rotator element 2312 may be, but is not limited to, implemented as a specially designed Faraday rotator plate for positively rotating the polarization direction of the transmitted light by 45° relative to the polarization direction of the incident light.

[0059] Optionally, the first polarization beam splitter element 232 may be implemented as, but not limited to, a PBS prism arranged horizontally in the transmission direction, for transmitting P light and reflecting S light.

[0060] Optionally, the first phase delay element 233 can be, but is not limited to, implemented as a specially designed half-wave plate for rotating the polarization direction of the transmitted light by 90° relative to the polarization direction of the incident light, ie, converting the S light passing through the first phase delay element 233 into P light.

[0061] It is worth noting that the deflection scanning device 21 can be implemented as, but is not limited to, a rotating mirror, a galvanometer mirror, a MEMS mirror, and an optical phased array, as long as it can achieve laser scanning, and this application will not go into details.

[0062] In addition, since the laser radar can further identify the material of the target object when receiving and detecting the P light component and the S light component in the echo light respectively, Figure 1 and Figure 2 As shown, the echo detection component 24 of the present application may include a first detection component 241, a second detection component 242 and a detection result analysis module 243; the first detection component 241 corresponds to the polarization modulation spectrometer component 23, and is used to receive and detect the first polarized light from the polarization modulation spectrometer component 23 to obtain a first detection result; the second detection component 242 corresponds to the polarization spectrometer 22, and is used to receive and detect the second polarized light from the polarization spectrometer 22 to obtain a second detection result; the detection result analysis module 243 can be communicatively connected to the first detection component 241 and the second detection component 242, and is used to analyze the first detection result and the second detection result to identify the material of the target object.

[0063] Optionally, the detection result analysis module 243 of the present application can be implemented as detection result analysis software and hardware. In this way, the first detection component 241 and the second detection component 242 respectively output the first detection result and the second detection result to the detection result analysis software and hardware, and the intensity of the different polarized lights (such as P light and S light) in the recovered light can be analyzed to distinguish the degree of change of the polarization state of the local oscillation light caused by the target object, and then the material of the target object can be analyzed.

[0064] Alternatively, if Figure 2 As shown, the first detection component 241 may include a first mixer 2411 and a first balanced detector 2412. The first mixer 2411 corresponds to the polarization modulation spectrometer component 23 and the laser emission system 10 at the same time, and is used to interfere the echo light from the polarization modulation spectrometer component 23 with the local oscillator light from the laser emission system 10 to form an interference signal; the first balanced detector 2412 is simultaneously connected to the first mixer 2411 and the detection result analysis module 243, and is used to perform interference measurement on the interference signal from the first mixer 2411 to obtain a first detection result output to the detection result analysis module 243.

[0065] It is worth noting that, since the local oscillator light emitted by the laser emission system 10 of the present application and the echo light from the polarization modulation spectrometer 23 are both first polarized light, the local oscillator light and the echo light can interfere in the first mixer 2411, and then be detected by the first balanced detector 2412 to obtain a first detection result. It is understandable that the balanced detector mentioned in the present application refers to a detection device including two photodetectors, which can output the photocurrents detected by the two photodetectors after differential processing.

[0066] In addition, since only the echo light and the local oscillator light with the same polarization state can interfere, and the echo light from the polarization beam splitter 22 is the second polarization light, and the local oscillator light from the laser emission system 10 is the first polarization light, the second detection component 242 needs to convert the echo light from the polarization beam splitter 22 into the first polarization light before mixing the echo light with the local oscillator light.

[0067] Alternatively, if Figure 2As shown, the second detection component 242 may include a second mixer 2421, a second balanced detector 2422 and a second phase delay element 2423; the second phase delay element 2423 is located on the reflection side of the polarization beam splitter 22, and is used to delay the phase of the second polarized light reflected by the polarization beam splitter 22 to form a first polarized light; the second mixer 2421 corresponds to the second phase delay element 2423 and the laser emission system 10 at the same time, and is used to make the echo light from the second phase delay element 2423 interfere with the local oscillation light from the laser emission system 10 to form an interference signal; the second balanced detector 2422 is connected to the second mixer 2421 and the detection result analysis module 243 at the same time, and is used to perform interference measurement on the interference signal from the second mixer 2421 to obtain a second detection result output to the detection result analysis module 243. It is understandable that the second phase delay element 2423 can be but is not limited to being implemented as a specially designed half-wave plate for rotating the polarization direction of the transmitted light by 90° relative to the incident light, that is, converting the S light passing through the first phase delay element 233 into P light.

[0068] According to the above embodiments of the present application, Figure 1 and Figure 2 As shown, the laser emission system 10 may include a polarization laser emission component 11 for emitting a first polarized light and a beam splitting component 12 for splitting a light beam propagating along a main optical path 1201 into light beams propagating along multiple branch optical paths 1202. The polarization laser emission component 11 is located in the main optical path 1201 of the beam splitting component 12, and the polarization beam splitter 22, the first mixer 2411 and the second mixer 2421 are respectively located in the branch optical path 1202 of the beam splitting component 12. The beam splitting component 12 is used to split the first polarized light from the polarization laser emission component 11 into first polarized lights propagating to the polarization beam splitter 22, the first mixer 2411 and the second mixer 2421, respectively. It can be understood that the branch optical path 1202 in the beam splitting component 12 of the present application can realize optical path deflection by setting a reflective element such as a total reflection mirror, so that the split light is correspondingly propagated to the polarization splitter 22, the first mixer 2411 and the second mixer 2421; of course, in other examples of the present application, the main optical path 1201 in the beam splitting component 12 can also be provided with a reflective element for optical path deflection, so as to adapt to the system layout requirements, and the present application will not go into details about this.

[0069] Alternatively, if Figure 1 and Figure 2As shown, the laser emission system 10 may further include a linearity correction module 13, which is located in a branch optical path 1202 of the beam splitting component 12 and is used to receive the local oscillator light split by the beam splitting component 12 to correct the frequency linearity of the polarized laser emission component 11. It can be understood that the linearity correction module 13 of the present application can be, but is not limited to, composed of a non-equal-arm interferometer.

[0070] Optionally, in the above example of the present application, Figure 2 As shown, the polarized laser emitting assembly 11 may be, but is not limited to, implemented as a first swept laser 111 for directly emitting first polarized light.

[0071] It is worth noting that since the laser emission system 10 requires at least four branch optical paths 1202, Figure 2 As shown, the beam splitter component 12 of the present application can be implemented as, but not limited to, a 1×4 beam splitter 121, one input end of the 1×4 beam splitter 121 is connected to the first frequency-sweeping laser 111, and the four output ends of the 1×4 beam splitter 121 are respectively connected to the polarization beam splitter 22, the first mixer 2411, the second mixer 2421 and the linearity correction module 13, for splitting one first polarized light from the first frequency-sweeping laser 111 into four first polarized lights, so as to propagate to the polarization beam splitter 22, the first mixer 2411, the second mixer 2421 and the linearity correction module 13 respectively. It can be understood that the 1×4 beam splitter 121 mentioned in the present application can realize that after one optical signal is input, it is distributed to four output ports according to a certain power ratio.

[0072] In addition, in order to achieve the desired beam splitting effect, in the second example of the present application, as Figure 3 As shown, the beam splitting component 12 can also be composed of three 1×2 beam splitters 122 connected in series, and can also split one path of first polarized light into four paths of first polarized light. It is understandable that in other examples of the present application, the beam splitting component 12 can also be composed of a 1×2 beam splitter 122 and a 1×3 beam splitter or other combinations, as long as it can split one path of first polarized light into four paths of first polarized light, and the present application will not repeat them.

[0073] It is worth noting that in the third example of the present application, Figure 4As shown, the polarized laser emitting assembly 11 may include a second frequency-sweeping laser 112 for directly emitting a second polarized light and a third phase delay element 113 for converting the second polarized light into a first polarized light. The third phase delay element 113 is located in the optical path between the second frequency-sweeping laser 112 and the beam splitting assembly 12, and is used to delay the phase of the second polarized light from the second frequency-sweeping laser 112 to form a first polarized light propagating to the beam splitting assembly 12, thereby ensuring that the local oscillator light emitted by the laser emitting system 10 is always the first polarized light, so as to facilitate interference with the echo light to achieve distance measurement or speed measurement of the target object.

[0074] Of course, in the fourth example of the present application, Figure 5 As shown, the polarized laser emitting assembly 11 may also include a third frequency sweeping laser 114 for directly emitting mixed polarized light and a polarizer 115 for obtaining first polarized light from the mixed polarized light. The polarizer 115 is located in the optical path between the third frequency sweeping laser 114 and the beam splitting assembly 12, and is used to obtain the first polarized light propagating to the beam splitting assembly 12 from the mixed polarized light from the third frequency sweeping laser 114, ensuring that the local oscillator light emitted by the laser emitting system 10 is always the first polarized light. It can be understood that the mixed polarized light mentioned in the present application may refer to mixed light containing the first polarized light and the second polarized light.

[0075] It is worth mentioning that Figure 6 and Figure 7 A fifth example of the laser radar 1 according to the present application is shown. Compared with the first example according to the present application, the laser radar 1 according to the fifth example of the present application is different in that: the third polarized light is implemented as -45° linear polarized light, and the fourth polarized light is implemented as +45° linear polarized light; at this time, the polarization modulation spectrometer 23 in the echo receiving system 20 may include a first Faraday rotator 234 for rotating the polarization direction of the transmitted light by +45° relative to the polarization direction of the incident light, and a Faraday rotator 235 for rotating the polarization direction of the transmitted light by +45° relative to the polarization direction of the incident light. The first Faraday rotator 234 and the second polarization beam splitter 236 are sequentially arranged in the optical path between the polarization beam splitter 22 and the deflection scanning device 21, and the second Faraday rotator 235 is correspondingly arranged on the reflection side of the second polarization beam splitter 236 to be located in the optical path between the second polarization beam splitter 236 and the first detection component 241.

[0076] In this way, Figure 7As shown, the first polarized light from the polarization beam splitter 22 is first rotated by +45° by the first Faraday rotator 234 to form +45° linear polarized light, and then passes through the second polarization beam splitter element 236 to propagate to the deflection scanning device 21 to achieve beam scanning of the target object. The +45° linear polarized light in the echo light from the deflection scanning device 21 first passes through the second polarization beam splitter element 236 to propagate to the first Faraday rotator 234, and then is rotated by +45° by the first Faraday rotator 234 to form S polarized light, and then is reflected by the polarization beam splitter 22 to propagate to the second detection component 242; at the same time, the -45° linear polarized light in the echo light from the deflection scanning device 21 is first reflected by the second polarization beam splitter element 236 to propagate to the second Faraday rotator 235, and then is rotated by +45° by the second Faraday rotator 235 to form P polarized light, and then propagates to the first detection component 241.

[0077] It can be understood that in this example of the present application, the second polarization beam splitter 236 can be implemented as, but is not limited to, a PBS prism arranged with a transmission direction inclined at +45°, for transmitting +45° linear polarized light and reflecting -45° linear polarized light.

[0078] It is worth noting that in order to realize the multi-transmit and multi-receive LiDAR, Figure 8 The sixth example of the laser radar 1 according to the present application is shown. Compared with the first example according to the present application, the laser radar 1 according to the sixth example of the present application is different in that: the echo detection component 24 in the echo receiving system 20 may include N first detection components 241 and N second detection components 242; the laser emitting system 10 may include a polarized laser emitting component 11, a beam splitting component 12, a polarization-maintaining optical amplifier 14 located in the optical path between the polarized laser emitting component 11 and the beam splitting component 12, and a linearity correction module 13; the beam splitting component 12 It may include a 1×3 beam splitter 123 whose input end is connected to the polarized laser emitting assembly 11, a 1×N beam splitter 124 whose input end is connected to the 1×3 beam splitter 123, and a 1×2N beam splitter 125 whose input end is connected to the 1×3 beam splitter 123; the linearity correction module 13 is connected to an output end of the 1×3 beam splitter 123; the N output ends of the 1×N beam splitter 124 are all connected to the polarization beam splitter 22; the 2N output ends of the 1×2N beam splitter 125 are respectively connected to N first mixers 2411 and N second mixers 2421 in a one-to-one correspondence. It is understood that N mentioned in the present application refers to a positive integer greater than or equal to 2.

[0079] In this way, Figure 8As shown, the P light emitted by the polarized laser emitting assembly 11 is first amplified and output by the polarization-maintaining optical amplifier 14, and then split into three P lights by the 1×3 beam splitter 123 to propagate to the 1×N beam splitter 124, the 1×2N beam splitter 125 and the linearity correction module 13 respectively; then, the 1×N beam splitter 124 splits one P light into N P lights that are spatially parallel to each other as signal lights 1-N, and then passes through the echo receiving system 20 of the present application. The provided coaxial light transmission and receiving path 211 and multiple scanning light paths 212 are propagated to the target object to be reflected to form echo light S1-SN and P1-PN; at the same time, the 1×2N beam splitter 125 splits one P light into 2N P lights parallel to each other in space as local oscillator light S1-SN and P1-PN, which are mixed and interfered with the echo light S1-SN and P1-PN in the corresponding mixers respectively, so as to be received and detected by the corresponding balanced detectors to obtain N detection results. It can be understood that the laser radar 1 in this example of the present application can enable the N-transmitting and N-receiving radar system to share the same set of hardware of the coaxial light transmission and receiving path without adding additional costs.

[0080] Optionally, in this example of the present application, Figure 8 As shown, the N second mixers 2421 in the N second detection components 242 can share one second phase delay element 2423 .

[0081] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. An echo receiving system, characterized in that: include: A deflection scanning device having a light receiving and light emitting path and a plurality of scanning light paths corresponding to the light receiving and light emitting path; a polarization beam splitter, arranged in the light-receiving and light-emitting path of the deflection scanning device, for transmitting the first polarized light propagating along the light-receiving and light-emitting path, and reflecting the second polarized light whose polarization direction is perpendicular to the first polarized light; a polarization modulation splitting component, which is correspondingly arranged in the optical path between the deflection scanning device and the polarization beam splitter, and is used for modulating the polarization state to reflect the third polarized light in the echo light deflected by the deflection scanning device to form the first polarized light, and modulating the polarization state to transmit the fourth polarized light in the echo light deflected by the deflection scanning device, which is perpendicular to the polarization direction of the third polarized light, to form the second polarized light and propagate to the polarization beam splitter; and The echo detection component is correspondingly arranged on the reflection side of the polarization beam splitter and the polarization modulation beam splitter component, and is used to receive the second polarized light reflected by the polarization beam splitter and the first polarized light reflected and modulated by the polarization modulation beam splitter component for detection.

2. The echo receiving system according to claim 1, characterized in that: The polarization modulation beam splitting component is further used for transmitting the first polarized light from the polarization beam splitter in a polarization-state-modulated manner to form the fourth polarized light and propagate it to the deflection scanning device.

3. The echo receiving system according to claim 2, characterized in that: The polarization modulation spectrometer component includes a non-reciprocal polarization rotator, a first polarization spectrometer element and a first phase delay element. The non-reciprocal polarization rotator and the first polarization spectrometer element are arranged in sequence in the optical path between the polarization spectrometer and the deflection scanning device. The non-reciprocal polarization rotator is used to rotate the polarization direction of the first polarized light from the polarization spectrometer by 0° to form the first polarized light propagating to the first polarization spectrometer element, and to rotate the polarization direction of the first polarized light from the first polarization spectrometer element by 90° to form the second polarized light propagating to the polarization spectrometer; the first phase delay element is arranged on the reflection side of the first polarization spectrometer element, and is used to delay the phase of the second polarized light reflected by the first polarization spectrometer element to form the first polarized light.

4. The echo receiving system according to claim 3, characterized in that: The non-reciprocal polarization rotator comprises a polarization rotation element and a Faraday rotator element which are sequentially arranged in an optical path between the polarization beam splitter and the first polarization beam splitter element; the polarization rotation element is used to rotate the transmitted light propagating to the Faraday rotator element by -45° relative to the polarization direction of the incident light from the polarization beam splitter, and to rotate the transmitted light propagating to the polarization beam splitter by +45° relative to the polarization direction of the incident light from the Faraday rotator element; the Faraday rotator element is used to rotate the transmitted light by +45° relative to the polarization direction of the incident light.

5. The echo receiving system according to claim 3, characterized in that: The polarization beam splitter and the first polarization beam splitting element are both PBS prisms arranged horizontally in the transmission direction, and are used to transmit P light and reflect S light.

6. The echo receiving system according to claim 2, characterized in that: The polarization modulation spectrometer component includes a first Faraday rotator, a second Faraday rotator and a second polarization spectrometer element. The first Faraday rotator and the second polarization spectrometer element are arranged in sequence in the optical path between the polarization spectrometer and the deflection scanning device, and the second Faraday rotator is correspondingly arranged on the reflection side of the second polarization spectrometer element; the first Faraday rotator and the second Faraday rotator are both used to rotate the transmitted light by +45° relative to the polarization direction of the incident light, and the second polarization spectrometer element is used to transmit +45° linearly polarized light and reflect -45° linearly polarized light.

7. The echo receiving system according to claim 6, characterized in that: The second polarization beam splitting element is a PBS prism arranged with a transmission direction inclined at +45°.

8. The echo receiving system according to any one of claims 1 to 7, characterized in that: The echo detection component includes a first detection component, a second detection component and a detection result analysis module; the first detection component corresponds to the polarization modulation spectrometer component, and is used to receive and detect the first polarized light from the polarization modulation spectrometer component to obtain a first detection result; the second detection component corresponds to the polarization spectrometer, and is used to receive and detect the second polarized light from the polarization spectrometer to obtain the second detection result.

9. The echo receiving system according to claim 8, characterized in that: The first detection component includes a first mixer and a first balanced detector. The first mixer corresponds to the polarization modulation spectrometer component and is used to interfere the echo light from the polarization modulation spectrometer component with the local oscillator light from the laser emission system to form an interference signal. The first balanced detector is connected to the first mixer and the detection result analysis module at the same time, and is used to perform interference measurement on the interference signal from the first mixer to obtain a first detection result output to the detection result analysis module.

10. The echo receiving system according to claim 8, characterized in that: The second detection component includes a second mixer, a second balanced detector and a second phase delay element, wherein the second phase delay element is not connected to the reflection side of the polarization splitter, and is used to delay the phase of the second polarized light reflected by the polarization splitter to form the first polarized light; the second mixer corresponds to the second phase delay element, and is used to make the echo light from the second phase delay element interfere with the local oscillator light from the laser emission system to form an interference signal; the second balanced detector is connected to the second mixer and the detection result analysis module at the same time, and is used to perform interference measurement on the interference signal from the second mixer to obtain a second detection result output to the detection result analysis module.

11. A laser radar, characterized in that include: A laser emission system, used for emitting signal light to a target object so as to be reflected by the target object to form echo light; and The echo receiving system according to any one of claims 1 to 10, wherein the echo receiving system is used to receive echo light from the target object to detect the target object.

12. The laser radar according to claim 11, characterized in that: The laser emitting system includes a polarized laser emitting component for emitting a first polarized light and a beam splitting component for splitting a light beam propagating along a main optical path into light beams propagating along multiple branch optical paths; the polarized laser emitting component is located in the main optical path of the beam splitting component, and the polarized beam splitter and echo detection component in the echo receiving system are respectively located in the branch optical paths of the beam splitting component.

13. The laser radar according to claim 12, characterized in that: The laser emission system further includes a linearity correction module, which is located in a branch optical path of the beam splitting component and is used to receive the local oscillator light split by the beam splitting component to correct the frequency linearity of the polarized laser emission component.

14. The laser radar according to claim 13, characterized in that: The beam splitter assembly is a 1×4 beam splitter or is composed of three 1×2 beam splitters connected in series.

15. The laser radar according to claim 13, characterized in that: The number of first detection components and second detection components in the echo detection component is N; the laser emission system further includes a polarization-maintaining optical amplifier located in the optical path between the polarization laser emission component and the beam splitting component; the beam splitting component includes a 1×3 beam splitter whose input end is connected to the polarization laser emission component, a 1×N beam splitter whose input end is connected to the 1×3 beam splitter, and a 1×2N beam splitter whose input end is connected to the 1×3 beam splitter; the linearity correction module is connected to an output end of the 1×3 beam splitter; the N output ends of the 1×N beam splitter are all connected to the polarization beam splitter; the 2N output ends of the 1×2N beam splitter are respectively connected to the N first mixers of the first detection components and the N second mixers of the second detection components in a one-to-one correspondence.

16. The laser radar according to any one of claims 12 to 15, characterized in that: The polarized laser emitting component is a first frequency-sweeping laser for directly emitting the first polarized light; Alternatively, the polarized laser emitting assembly comprises a second frequency-sweeping laser for directly emitting second polarized light and a third phase delay element for converting the second polarized light into first polarized light, wherein the third phase delay element is located in the optical path between the second frequency-sweeping laser and the beam splitting assembly; Alternatively, the polarized laser emitting assembly includes a third frequency-sweeping laser for directly emitting mixed polarized light and a polarizer for obtaining the first polarized light from the mixed polarized light, and the polarizer is located in the optical path between the third frequency-sweeping laser and the beam splitting assembly.

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