CN114924254A - Laser radar system based on direct detection and detection method - Google Patents
Laser radar system based on direct detection and detection method Download PDFInfo
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Abstract
The invention provides a laser radar system based on direct detection and a detection method, wherein the system comprises: the device comprises a signal transmitting module, a transceiving module, a reference light receiving module, a return light receiving module and a signal processing module; the signal transmitting module is used for transmitting laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal; the receiving and transmitting module is used for transmitting the incident second optical signal to a detection target and receiving a third optical signal which is scattered by the detection target and then returns; the reference light receiving module is used for acquiring a first electric signal according to the incident first optical signal; the return light receiving module is used for acquiring a second electric signal according to the incident third optical signal; and the signal processing module is used for generating point cloud data of the detection target based on the first electric signal and the second electric signal. The laser radar system and the detection method based on direct detection can improve the anti-interference capability and the space scanning efficiency.
Description
Technical Field
The invention relates to the technical field of laser detection, in particular to a laser radar system based on direct detection and a detection method.
Background
In the automatic driving technology, an environment sensing system is a basic and crucial ring and is a guarantee for safety and intelligence of an automatic driving automobile. In the environment perception sensor, the laser radar has incomparable advantages in the aspects of reliability, detection range, distance measurement precision and the like.
Common autopilot scene often requires many laser radar equipment to work simultaneously in limited space, so traditional multi-thread laser radar is simple piles up laser emitter's number and expands parallel channel number, carry out the pseudo-random encryption to the one-way passageway and need extra regulation and control and equipment, the detection receiving system of collocation array, can cause the apparent rising of hardware cost and system complexity, and the malicious attack of external interference signal can't be resisted to the predictability of pseudo-random modulation, also can cause very big influence to autopilot's security.
Due to the true randomness and good correlation characteristics, the chaotic signal is an ideal signal choice in laser radar application. However, the chaotic laser radar in the prior art outputs a broadband chaotic signal by adopting schemes such as optical feedback and the like, has high system complexity, and is not easy to expand in a parallelization manner. Therefore, how to make the lidar have both low system complexity and high channel isolation is an important issue to be solved in the industry at present.
Disclosure of Invention
The invention provides a laser radar system based on direct detection and a detection method, which are used for overcoming the defects of complex structure and low channel isolation of a radar system outputting chaotic signals in the prior art, simplifying the system complexity of a laser radar, reducing the cost and simultaneously considering the high isolation of each channel.
The invention provides a laser radar system based on direct detection, which comprises: the device comprises a signal transmitting module, a transceiving module, a reference light receiving module, a return light receiving module and a signal processing module;
the signal transmitting module is used for transmitting laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal;
the transceiver module is used for transmitting the incident second optical signal to a detection target and receiving a third optical signal returned after scattering by the detection target;
the reference light receiving module is used for acquiring a first electric signal according to the incident first optical signal;
the return light receiving module is used for acquiring a second electric signal according to the incident third optical signal;
the signal processing module is used for generating point cloud data of the detection target based on the first electric signal and the second electric signal;
the chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the phases of the first optical signal and the second optical signal are the same as the chaotic detection signal.
According to the laser radar system based on direct detection provided by the invention, the optical-frequency comb generator comprises one or more of a microcavity optical comb, a mode-locked laser and an electro-optical comb.
According to the direct detection-based laser radar system provided by the invention, the reference light receiving module comprises a first demultiplexing unit and a first photodetector array.
According to the laser radar system based on direct detection provided by the invention, the return light receiving module comprises a second demultiplexing unit and a second photodetector array.
According to the laser radar system based on direct detection provided by the invention, the return light receiving module comprises a second photodetector array.
According to the laser radar system based on direct detection provided by the invention, the transceiver module comprises a circulator and a transmitting unit;
the first end of the circulator is connected with the signal transmitting module, the second end of the circulator is connected with the transmitting unit, and the third end of the circulator is connected with the return light receiving module.
The laser radar system based on direct detection further comprises a display device for displaying the point cloud data.
The invention also provides a detection method of the laser radar system based on direct detection, which comprises the following steps:
the signal transmitting module transmits laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal;
the receiving and transmitting module transmits the incident second optical signal to a detection target and receives a third optical signal which is scattered by the detection target and then returns;
the reference light receiving module acquires a first electric signal according to the incident first optical signal;
the return light receiving module acquires a second electric signal according to the incident third optical signal;
the signal processing module generates point cloud data of the detection target based on the first electric signal and the second electric signal;
the chaotic detection signal comprises a plurality of laser signals with parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
According to the detection method of the laser radar system based on the direct detection, the point cloud data of the detection target is generated based on the first electric signal and the second electric signal, and the method comprises the following steps:
performing autocorrelation detection based on the first electrical signal and the second electrical signal to obtain time delay and reflectivity information of each detection channel;
and generating point cloud data of the detection target based on the time delay and reflectivity information of each detection channel.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the detection method according to any one of the above methods when executing the program.
The invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements a detection method as described in any of the above.
The invention also provides a computer program product comprising a computer program which, when executed by a processor, implements the detection method as described in any one of the above.
The laser radar system and the detection method based on direct detection provided by the invention output broad-band chaotic detection signals with multiple parallel detection channels based on the generation state of the optical frequency comb controlled in the signal transmitting module, and divide the chaotic detection signals into two paths. One route of the reference light receiving module is used for carrying out channel separation on a first optical signal separated from the chaotic detection signal and then converting the first optical signal into a first electric signal, the other route of the reference light receiving module is used for simultaneously transmitting a second optical signal, returning and receiving a third optical signal returned after scattering of the detection target, and carrying out channel separation on the third optical signal through the returning light receiving module and then converting the third optical signal into a second electric signal. And scanning point cloud data of the detection target through the cross-correlation characteristics of the first electric signal and the second electric signal under each detection channel of the signal processing module. The high isolation of each channel is also considered when the low-cost parallelization extension of the laser radar system is realized, and then the anti-interference ability and the space scanning efficiency in the detection process are improved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a direct detection-based lidar system according to the present invention;
FIG. 2 is a second schematic diagram of a direct detection-based lidar system according to the present invention;
FIG. 3 is a third schematic structural diagram of a laser radar system based on direct detection according to the present invention;
FIG. 4 is a fourth schematic diagram of the structure of the laser radar system based on direct detection provided by the present invention;
FIG. 5 is a schematic flow chart of a detection method of a laser radar system based on direct detection provided by the present invention;
fig. 6 is a schematic structural diagram of an electronic device provided in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that embodiments of the application are capable of operation in sequences other than those illustrated or described herein, and that the terms "first," "second," etc. are generally used in a generic sense and do not limit the number of terms, e.g., a first term can be one or more than one.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Fig. 1 is a schematic structural diagram of a direct detection-based lidar system provided by the invention. As shown in fig. 1, a direct detection-based lidar system according to an embodiment of the present invention includes: the optical transceiver module comprises a signal transmitting module 110, a transceiver module 120, a reference light receiving module 130, a return light receiving module 140 and a signal processing module 150.
It should be noted that, for an application scenario of the laser radar system based on direct detection, the embodiment of the present invention is not limited to this specifically. For example, it may be environment perception for smart driving, smart cities, unmanned planes, robots, military technologies, etc.
For any application scenario, including direct detection based lidar systems and probe targets, the number of probe targets may be one or more.
The direct detection-based laser radar system transmits a detection signal (laser beam) to a detection target, compares the received signal reflected from the detection target with the transmission signal, and obtains relevant information of the detection target after proper processing, such as parameters of distance, direction, height, speed, attitude, even shape and the like, so as to detect, track and identify the detection target such as ground objects, airplanes, missiles and the like in the environment.
Specifically, the lidar system based on direct detection is provided with a signal transmitting module 110, a transceiver module 120, a reference light receiving module 130, a return light receiving module 140 and a signal processing module 150, wherein the signal transmitting module 110 can simultaneously generate multi-channel parallel chaotic detection signals with orthogonal broadband and time domain, a part of the chaotic detection signals are divided into reference light signals, and the reference light signals are transmitted to the reference light receiving module 130 for signal conversion to obtain output signals of reference light. A part of the optical signal is separated from the chaotic probe signal, and is simultaneously transmitted to the surface of the probe target by the transceiver module 120, and the received probe target reflection signal is transmitted to the return optical receiving module 140 as a return optical signal for signal conversion, so as to obtain an output signal of the return light. And then the signal processing module 150 receives the output signal of the reference light and the output signal of the return light, and simultaneously performs multi-channel correlation detection to obtain point cloud data of the detection target in a three-dimensional space.
The signal transmitting module 110 is configured to transmit a light source to the optical frequency comb generator to generate a parallel chaotic detection signal, where the parallel chaotic detection signal is divided into a first optical signal and a second optical signal.
The chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
The optical comb is a broadband spectrum composed of a plurality of spectral comb teeth with stable frequencies and strictly equal intervals, and is represented as a series of equally spaced ultrashort pulse outputs in the time domain. The optical frequency comb is used as a measuring ruler for accurately measuring the frequency of other light sources.
It should be noted that, before the signal emitting module 110 operates, the incident laser needs to be obtained from the pump light source in advance, and the arrangement of the pump light source is not particularly limited in the embodiment of the present invention.
Alternatively, the pump light source may be a component separate from the direct detection based lidar system.
Illustratively, the pump light source includes, but is not limited to, a narrow linewidth laser, a hybrid integrated external cavity laser, or an on-chip integrated tunable semiconductor laser, etc., capable of providing a laser output.
Alternatively, the pump light source and the optical frequency comb may be integrated into the signal transmitting module 110 of the direct detection-based lidar system.
Illustratively, the signal transmitting module 110 may be integrated with the optical-frequency comb generator by the pump light source, in an integration manner including, but not limited to, hybrid integration, heterogeneous integration, monolithic integration, and the like.
Preferably, the signal transmission module 110 may include a pumping light source, an optical frequency comb generator, a beam splitter, and an optical amplifier.
Specifically, since the detection channels corresponding to the comb teeth of the optical frequency comb have different central wavelengths, the built-in optical frequency comb generator modulates the laser into the chaotic detection signal and outputs the chaotic detection signal simultaneously in each detection channel, and then the built-in beam splitter divides the output chaotic detection signal into the first optical signal and the second optical signal, and transmits the first optical signal to the reference optical receiving module 130, and simultaneously transmits the second optical signal to the transceiver module 120.
The chaotic detection signal comprises a plurality of laser beams with different central wavelengths, and is used for establishing a mapping relation between a laser radar system based on direct detection and detection target azimuth information through a diffraction grating principle.
Wherein the number of the laser beams is the same as the number of comb teeth (i.e., detection channels) of the optical frequency comb. The embodiment of the invention does not specifically limit the generation process of the chaotic detection signal.
Illustratively, the multi-wavelength chaotic sounding signal may consist of comb teeth produced by a single optical-frequency comb.
Illustratively, the multi-wavelength chaotic detection signal may be composed of a plurality of comb teeth generated by optical frequency combs.
The embodiment of the invention does not specifically limit the light splitting process of the chaotic detection signal.
Preferably, after the laser received by the signal transmitting module 110, the laser is modulated into the chaotic detection signal by the built-in optical frequency comb and then is simultaneously output, the chaotic detection signal output by the optical frequency comb is amplified by the built-in optical amplifier and is output after reaching the required power, and the amplified chaotic detection signal is received by the built-in beam splitter and is split into the first optical signal and the second optical signal.
Wherein the first optical signal and the second optical signal have the same phase. The optical amplifier is composed of an optical fiber amplifier or an on-chip optical amplifier, and the beam splitter can be a common beam splitter prism.
The transceiver module 120 is configured to transmit the incident second optical signal to the detection target, and receive a third optical signal returned after scattering by the detection target.
It should be noted that the detection target refers to an object to be detected in any application scenario of the laser radar system based on direct detection.
The second optical signal refers to an incident optical signal received by the detection target.
The third optical signal is an optical signal reflected by the object when the incident light is incident on the surface of the object to be detected.
Specifically, the transceiver module 120 receives the second optical signal distributed by the signal transmitter module 110, first performs spatial separation on parallel detection channels in the second optical signal by using a built-in diffraction grating and a prism, and simultaneously transmits each separated laser beam in the second optical signal to the surface of the detection target. Next, the third optical signal reflected by the detection target is received, and deflection control is performed on the third optical signal, so that the reflected light of all the detection channels in the third optical signal is simultaneously emitted to the return light receiving module 140.
The embodiment of the present invention does not specifically limit the arrangement of the transceiver module.
Optionally, the transceiver module 120 may implement coaxial transceiving by discrete elements such as a diffraction grating, a prism, a polarization controller, or an on-chip optical antenna array, and this structure is not particularly limited in this embodiment of the present invention.
Illustratively, the transceiver module 120 may be implemented using a discrete diffraction grating and an element or system with one-dimensional deflection steering functionality. The functional elements include the use of the diffraction grating principle or the dispersive principle of photorefractive to achieve spatial separation of the second optical signals of the parallel channels and simultaneously control of deflection in another dimension for all channels, and any variant derivative that meets the spirit of the elements set forth above is intended to be included within the scope of protection.
For example, the transceiver module 120 may employ an on-chip integrated transmission system for transmitting the second optical signal, such as an optical phased array system or a focal plane array. The light emission mode of the on-chip integrated emission system comprises the end face emission of the waveguide array at the edge of the optical chip and the emission of the waveguide array in the direction vertical to the surface of the optical chip. Any variant derivative that meets the above stated spirit is intended to be included within the scope of protection.
Alternatively, the transceiver module 120 may implement off-axis transceiving by using a transmitting unit and a receiving unit that are independent of each other, and this structure is not particularly limited in this embodiment of the present invention.
Illustratively, the transmitting unit is composed of a set of diffraction gratings and prisms, and the transmitting unit is configured to transmit the second optical signal output by the signal transmitting module 110 to the surface of the detection target after performing spatial dispersion separation on the second optical signal, so as to form a transmitting optical path.
Illustratively, the receiving unit is composed of another set of diffraction grating and prism, and is configured to receive a third optical signal reflected by the detection target for each wavelength of the laser beam, form a receiving optical path, and output the third optical signal to the return light receiving module 140.
The reference light receiving module 130 is configured to obtain a first electrical signal according to the incident first optical signal.
Specifically, the reference light receiving module 130 receives the first optical signal distributed by the signal transmitting module 110, separates and focuses the first optical signals with different center wavelengths on an optical domain by using the diffraction grating principle, converts the separated first optical signals into first electrical signals, and transmits the first electrical signals to the signal processing module 150.
The first electrical signal reflects laser beams with different central wavelengths in the first optical signal, and the responsivity of a corresponding detection channel on a photoelectric detector is based on the photoelectric effect generated by the interaction of optical radiation and substances.
And the return light receiving module 140 is configured to obtain a second electrical signal according to the incident third optical signal.
Specifically, the return light receiving module 140 receives the third optical signal output by the transceiver module 120, separates and focuses the third optical signal with different central wavelengths on an optical domain according to the diffraction grating principle, converts the separated third optical signal into a second electrical signal, and transmits the second electrical signal to the signal processing module 150.
And the second electric signal reflects the laser beams with different central wavelengths in the third optical signal, and the responsivity of the corresponding detection channel on the photoelectric detector is based on the photoelectric effect generated by the interaction of the optical radiation and the substance.
And a signal processing module 150 configured to generate point cloud data of the detection target based on the first electrical signal and the second electrical signal.
Specifically, the signal processing module 150 receives a first electrical signal output from the reference light receiving module 130 and a second electrical signal output from the return light receiving module 140, performs correlation calculation according to the first electrical signal and the second electrical signal under each detection channel, demodulates the time delay of the detection channel, and calculates point cloud data of the detection target accordingly.
The point cloud data of the detection target includes, but is not limited to, depth, reflectivity, speed and other related information of the detection target in the three-dimensional space.
The embodiment of the invention outputs wide-band chaotic detection signals with multiple parallel detection channels based on the generation state of the optical frequency comb controlled in the signal transmission module, and divides the chaotic detection signals into two paths. One route of the reference light receiving module is used for channel separation of a first optical signal divided by the chaotic detection signal and then converting the first optical signal into a first electric signal, the other route of the reference light receiving module is used for simultaneously transmitting a second optical signal and returning to receive a third optical signal reflected by the detection target, and the return light receiving module is used for channel separation of the third optical signal and then converting the third optical signal into a second electric signal. And scanning point cloud data of the detection target through the cross-correlation characteristics of the first electric signal and the second electric signal under each detection channel of the signal processing module. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
On the basis of any one of the above embodiments, the optical-frequency comb comprises one or more of a mode-locked laser and an optical-frequency comb.
Specifically, the optical frequency comb generator in the signal transmitting module 110 modulates according to the incident laser and a modulation parameter (for example, frequency or power), and generates laser beams with corresponding wavelengths under each detection channel, so as to summarize the chaotic detection signal as a whole.
The number and the type of the optical frequency comb generators are not particularly limited in the embodiment of the invention.
Alternatively, the optical-frequency comb generator may include one. Illustratively, the optical frequency comb generator includes, but is not limited to, a mode-locked laser, an electro-optical comb, or a modulating device such as a resonant cavity.
Alternatively, the optical-frequency comb generator may include a plurality. Illustratively, optical-frequency comb generators include, but are not limited to, a combination of modulation devices such as microcavity optical combs, mode-locked lasers, electrical-optical combs, or resonant cavities.
The embodiment of the invention outputs broadband chaotic detection signals with multiple parallel detection channels based on the generation state of the control optical frequency comb. And then, scanning point cloud data of a detection target by the cross-correlation characteristics of the first electric signal and the second electric signal under each detection channel of the signal processing module. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
On the basis of any of the above embodiments, the reference light receiving module 130 includes a first demultiplexing unit and a first photodetector array.
It should be noted that the first demultiplexing unit may be formed by a discrete fiber filter element or an on-chip optical demultiplexer chip.
The first photodetector array may be formed from a plurality of discrete photodetectors or an on-chip integrated photodetector array.
Specifically, the reference light receiving module 130 in the laser radar system based on direct detection is composed of a first demultiplexing unit and a group of first optical detector arrays, and after wavelength separation is performed on the first optical signal by the first demultiplexing unit, the first optical detector arrays convert the collected first optical signals under each detection channel into corresponding first electrical signals.
And the first demultiplexing unit is used for separating the detection channels of the first optical signal according to the corresponding central wavelength of the first optical signal so as to extract the optical signals under different wavelengths.
The type of the first demultiplexing unit includes, but is not limited to, any on-chip device or system with a wavelength demultiplexing function, such as an arrayed waveguide grating, a cascaded mach-zehnder interferometer, a micro-ring resonator array, and the like, and the embodiment of the present invention is not particularly limited.
And the first optical detector array is used for converting optical signals under different wavelengths into digital electric domain signals to obtain responsivity under corresponding detection channels.
The type of the first photo-detector array includes, but is not limited to, any on-chip detector scheme that relies on waveguide transmission and manipulation, such as an on-chip integrated detector, and the embodiments of the present invention are not limited in particular.
In the embodiment of the invention, based on the fact that the first optical signal is incident to the reference light receiving module, after wavelength separation is carried out by the first demultiplexing unit, the collected first optical signal under each detection channel is converted into the corresponding first electric signal through the first optical detector array. And then, scanning point cloud data of a detection target by the signal processing module based on the first electric signals under each detection channel according to the cross-correlation characteristic of the chaotic signals. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
Fig. 2 is a second schematic structural diagram of a lidar system based on direct detection provided by the present invention. As shown in fig. 2, on the basis of any of the above embodiments, the returning light receiving module 240 includes a second demultiplexing unit 241 and a second photodetector array 242.
It should be noted that the second demultiplexing unit 241 may have a similar composition structure to the first demultiplexing unit 231.
The second photo-detector array 242 may have a similar composition as the first photo-detector array 232.
Specifically, the return light receiving module 240 in the direct detection-based lidar system is composed of a second demultiplexing unit 241 and a group of second photodetector arrays 242, and after wavelength separation is performed on the third optical signal by the second demultiplexing unit 241, the second photodetector arrays 242 convert the collected third optical signal under each detection channel into corresponding second electrical signals.
The second demultiplexing unit 241 is configured to separate the detection channels according to the corresponding center wavelength of the third optical signal, so as to extract optical signals at different wavelengths.
The second demultiplexing unit 241 may include, but is not limited to, any on-chip device or system with wavelength demultiplexing function, such as an arrayed waveguide grating, a cascaded mach-zehnder interferometer, a micro-ring resonator array, etc., and the embodiments of the present invention are not limited in particular.
And the second optical detector array 242 is configured to convert optical signals with different wavelengths into digital electric domain signals, so as to obtain responsivity in a corresponding detection channel.
The second photo-detector array 242 may be any type of on-chip detector scheme that depends on waveguide transmission and manipulation, such as, but not limited to, on-chip integrated detectors, and the embodiments of the invention are not limited thereto.
Illustratively, a specific embodiment of detecting an object is given below:
the pump light source 211 inputs the optical frequency comb generator 212 to generate parallel broadband chaotic detection signals, the amplifier 213 amplifies the signals, and the beam splitter 214 divides the amplified signals into two paths:
one path is used as a first optical signal, so that the first demultiplexing unit 231 and the first photodetector array 232 in the reference light receiving module 230 perform photoelectric conversion to obtain a first electrical signal under each detection channel.
The other path is used as a second optical signal, so that the transceiver module 220 transmits the second optical signal under each detection channel to the detection target at the same time, and receives a third optical signal reflected by the detection target. And then the second demultiplexing unit 241 and the second photodetector array 242 in the return light receiving module 240 perform photoelectric conversion to obtain a second electrical signal under each detection channel.
Finally, the signal processing module 250 receives the first electrical signal and the second electrical signal under each detection channel, performs autocorrelation calculation, and scans out point cloud data of the detection target.
In the embodiment of the invention, based on the fact that the third optical signal is incident to the return light receiving module, after wavelength separation is performed by the second demultiplexing unit, the collected third optical signal under each detection channel is converted into the corresponding second electrical signal by the second optical detector array. And then, according to the cross-correlation characteristic of the chaotic signals, the signal processing module scans point cloud data of the detection target based on the second electric signals under each detection channel. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
Fig. 3 is a third schematic structural diagram of a direct detection-based lidar system provided by the present invention. As shown in fig. 3, on the basis of any of the above embodiments, the returning light receiving module 340 includes a second photodetector array 341.
It should be noted that the reference light receiving module 330 is still composed of a first demultiplexing unit 331 and a group of first photodetector arrays 332, and after the first optical signal is subjected to wavelength separation by the first demultiplexing unit 331, the first photodetector arrays 332 convert the collected first optical signals under each detection channel into corresponding first electrical signals.
Specifically, the returning light receiving module 340 in the direct detection-based lidar system is different from the reference light receiving module 330 in configuration, and is composed of only one set of second photodetector arrays 341, and the second photodetector arrays 341 directly receive the third optical signals under each detection channel at the same time and convert the third optical signals into corresponding second electrical signals.
The second photo-detector array 341 according to the embodiment of the invention is not limited in kind.
Preferably, the returning light receiving module 340 is simplified to a structure including only the second photo-detector array 341 because the second light signal has good orthogonality in time frequency and space, so that each detection channel has a higher isolation.
The second photo-detector array 341, may be a high sensitivity detector. The second photo-detector array 341 is used to directly receive all the optical signals and convert them into electrical signals.
Illustratively, a specific embodiment of detecting an object is given below:
the pump light source 311 inputs the optical frequency comb generator 312 to generate parallel broadband chaotic detection signals, the signals are amplified by the amplifier 313, and the amplified signals are divided into two paths by the beam splitter 314:
one path is used as a first optical signal, so that after wavelength separation is performed by the first demultiplexing unit 331 in the reference light receiving module 330, photoelectric conversion is performed by the first photodetector array 332 to obtain a first electrical signal under each detection channel.
The other path is used as a second optical signal, so that the transceiver module 320 transmits the second optical signal under each detection channel to the detection target at the same time, and receives a third optical signal reflected by the detection target. And then the second photodetector array 341 in the return light receiving module 340 performs photoelectric conversion to obtain a corresponding second electrical signal.
Finally, the signal processing module 250 receives the first electrical signal and the corresponding second electrical signal under each detection channel, performs autocorrelation calculation, and scans out the point cloud data of the detection target.
In the embodiment of the invention, the third optical signal is directly collected by the second optical detector array and converted into the corresponding second electrical signal based on the fact that the third optical signal is incident to the return light receiving module. And then, according to the cross-correlation characteristic of the chaotic signals, the signal processing module scans point cloud data of the detection target based on the second electric signals under each detection channel. The system complexity of the laser radar can be simplified, and the cost is reduced. Furthermore, the anti-interference capability and the space scanning efficiency in the detection process are improved.
Fig. 4 is a fourth schematic structural diagram of the direct detection-based lidar system provided by the invention. As shown in fig. 4, on the basis of any of the above embodiments, the transceiver module 420 includes a circulator 421 and a transmitting unit 422.
The first end of the circulator 421 is connected to the signal transmitting module 410, the second end of the circulator 421 is connected to the transmitting unit 422, and the third end of the circulator 421 is connected to the return light receiving module 440.
It should be noted that the circulator 421 is a multi-port device that sequentially transmits an incident wave entering any one port thereof to the next port in a direction determined by the static bias magnetic field.
The number of ports of the circulator 421 is at least 3, which is not particularly limited in the embodiment of the present invention. Wherein:
a first end of the circulator 421 is connected to the signal transmitting module 410, and a second end of the circulator 421 is connected to the transmitting unit 422 to construct a transmitting optical path.
A second end of the circulator 421 is connected to the transmitting unit 422, and a third end of the circulator 421 is connected to the return light receiving module 440 to construct a receiving optical path.
Specifically, the transceiver module 420 is composed of a circulator 421 and a transmitter 422, and the circulator 421 and the transmitter 422 cooperate to perform coaxial transceiving tasks under the condition that different ports receive incident light.
When the second optical signal output by the signal transmitting module 410 is used as the incident light at the first end of the circulator 421, the second optical signal is sequentially transmitted to the second end of the circulator 421 according to the direction of the transmitting optical path, and is output to the transmitting unit 422 to transmit the detection target.
Under the condition that the third optical signal output by the sending unit 422 is used as incident light at the second end of the circulator 421, the third optical signal is sequentially transmitted to the third end of the circulator 421 according to the direction of the receiving optical path, and is output to the return light receiving module 440 to perform photoelectric conversion on the third optical signal, so as to obtain a second electrical signal.
It is understood that the circulator 421 may be replaced by a device or system with a polarization splitting function, so that the transmitted second optical signal and the received third optical signal are in different polarization states, and then the corresponding processing is performed according to the corresponding optical paths.
It will be appreciated that the transceiver module 420 may also be configured to include a transmit unit and a receive unit to perform off-axis transceiving tasks, respectively. Wherein:
and a transmitting unit for receiving the second optical signal output by the signal transmitting module 410 and transmitting the second optical signal to the detection target.
And a receiving unit for receiving the third optical signal reflected by the detection target and outputting the third optical signal to the return optical receiving module 440.
Exemplary, a specific embodiment of detecting an object is given below:
the pumping light source 411 inputs an optical frequency comb generator 412 to generate parallel broadband chaotic detection signals, the signals are amplified by an amplifier 413, and the amplified signals are divided into two paths by a beam splitter 414:
one path is used as a first optical signal, so that after wavelength separation is performed by the first demultiplexing unit 431 in the reference light receiving module 430, photoelectric conversion is performed by the first photodetector array 432, and a first electrical signal under each detection channel is obtained.
The other path is used as a second optical signal to be used as incident light at the first end of the circulator 421 in the transceiver module 420, and the circulator 421 is matched with the transmitting unit 422 to simultaneously transmit the second optical signals under each detection channel to the detection target.
And, the third optical signal reflected by the detection target is received by the transmitting unit 422 to be used as the incident light at the second end of the circulator 421, and the circulator 421 cooperates with the transmitting unit 422 to transmit the third optical signal under each detection channel to the return light receiving module 440 at the same time. And then the returning light receiving module 340 performs photoelectric conversion to obtain a corresponding second electrical signal.
Finally, the signal processing module 250 receives the first electrical signal and the corresponding second electrical signal under each detection channel, performs autocorrelation calculation, and scans out point cloud data of the detection target.
The embodiment of the invention realizes deflection control based on the circulator, realizes spatial separation of parallel channels and simultaneously emits a second optical signal and a third optical signal by a transmission unit according to a diffraction grating principle or a light refraction dispersion principle. And then, the return light receiving module converts the third optical signal into a second point signal, and the point cloud data of the detection target is scanned through the signal processing module based on the second electric signal under each detection channel. The system complexity of the laser radar can be simplified, and the cost is reduced. Furthermore, the anti-interference capability and the space scanning efficiency in the detection process are improved.
On the basis of any one of the above embodiments, the system further comprises a display device for displaying the point cloud data.
In particular, in a direct detection based lidar system, a display device is communicatively connected to a signal processing module. After the point cloud data of the detection target scanned by the signal processing module, the point cloud data is packaged and transmitted to the display device, so that the display device can visualize the point cloud data of the detection target in a corresponding display interface.
The embodiment of the invention realizes the front-end visualization of the point cloud data of the detection target based on the display device, and is beneficial to the real-time monitoring of the detection process on the premise of improving the anti-interference capability and the space scanning efficiency in the detection process.
Fig. 5 is a schematic flow chart of a detection method of a laser radar system based on direct detection provided by the present invention. As shown in fig. 5, based on the content of any of the above embodiments, the method for detecting a laser radar system based on direct detection includes: step 501, a signal transmitting module transmits laser to an optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal.
The chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
It should be noted that the optical path design of the direct detection-based lidar system is to use pump laser as reference light. The execution subject of the detection method of the laser radar system based on direct detection is each component of the laser radar system based on direct detection.
Specifically, in step 501, since the detection channels corresponding to the comb teeth of the optical-frequency comb have different central wavelengths, the built-in optical-frequency comb generator modulates the laser into the chaotic detection signal and outputs the chaotic detection signal at the same time in each detection channel, the built-in beam splitter splits the output chaotic detection signal into a first optical signal and a second optical signal, and transmits the first optical signal to the reference light receiving module, and at the same time, transmits the second optical signal to the transceiver module.
The chaotic detection signal comprises a plurality of laser beams with different central wavelengths, and is used for establishing a mapping relation between a laser radar system based on direct detection and detection target azimuth information through a diffraction grating principle.
Specifically, in step 502, the transceiver module receives the second optical signal distributed by the signal transmitting module, first performs spatial separation on parallel detection channels in the second optical signal by using a built-in diffraction grating and a prism, and simultaneously transmits each separated laser beam in the second optical signal to the surface of the detection target. And then, receiving a third optical signal reflected by the detection target, and performing deflection control on the third optical signal so that the reflected light of all detection channels in the third optical signal is simultaneously emitted to the return light receiving module.
The embodiment of the present invention does not specifically limit the transceiving scheme of the transceiving module.
Optionally, the transceiver module is matched with a transmitting unit by a circulator, and under the condition that different ports receive incident light, the transceiver module jointly executes coaxial transceiving tasks.
And under the condition that a second optical signal output by the signal transmitting module is used as incident light of the first end of the circulator, the second optical signal is transmitted to the second end of the circulator according to the direction sequence of the transmitting light path and is output to the sending unit so as to transmit the detection target.
And under the condition that the third optical signal output by the sending unit is used as incident light of the second end of the circulator, the third optical signal is transmitted to the third end of the circulator according to the direction sequence of the receiving optical path and is output to the return optical receiving module so as to perform photoelectric conversion on the third optical signal, and a second electrical signal is obtained.
Optionally, the transceiver module is used for performing off-axis transceiving tasks by matching a receiving unit and a transmitting unit.
Under the condition that the second optical signals output by the signal transmitting module are used as incident light of the transmitting unit, and after wavelength separation is carried out by the transmitting unit, the second optical signals which are parallel in a multi-channel mode are simultaneously output to transmit the detection target.
Under the condition that a reflected third optical signal generated on the surface of the detection target is used as incident light of the receiving unit, and after wavelength separation is carried out by the receiving unit, the multichannel parallel third optical signal is simultaneously output to the return light receiving module so as to carry out photoelectric conversion on the third optical signal and obtain a second electric signal.
Specifically, in step 503, the reference light receiving module receives the first optical signal distributed by the signal transmitting module, separates and focuses the first optical signals with different central wavelengths on the optical domain by using the diffraction grating principle, converts the separated first optical signals into first electrical signals, and transmits the first electrical signals to the signal processing module.
The first electrical signal reflects laser beams with different central wavelengths in the first optical signal, and the responsivity of a corresponding detection channel on a photoelectric detector is based on the photoelectric effect generated by the interaction of optical radiation and substances.
Specifically, in step 504, the return light receiving module receives the third optical signal output by the transceiver module, separates and focuses the third optical signal with different central wavelengths on an optical domain according to the diffraction grating principle, converts the separated third optical signal into a second electrical signal, and then transmits the second electrical signal to the signal processing module.
And the second electric signal reflects the laser beams with different central wavelengths in the third optical signal, and the responsivity of the corresponding detection channel on the photoelectric detector is based on the photoelectric effect generated by the interaction of the optical radiation and the substance.
And 505, generating point cloud data of the detection target by the signal processing module based on the first electric signal and the second electric signal.
Specifically, in step 505, the signal processing module receives a first electrical signal output from the reference light receiving module and a second electrical signal output from the return light receiving module, performs correlation calculation according to the first electrical signal and the second electrical signal under each detection channel, demodulates the time delay of the detection channel, and accordingly calculates the point cloud data of the detection target.
The point cloud data of the detection target includes, but is not limited to, depth, reflectivity, speed and other related information of the detection target in the three-dimensional space.
The embodiment of the invention outputs broadband chaotic detection signals with multiple parallel detection channels based on the generation state of the optical frequency comb controlled in the signal transmitting module, and divides the chaotic detection signals into two paths. One route of the reference light receiving module is used for carrying out channel separation on a first optical signal separated from the chaotic detection signal and then converting the first optical signal into a first electric signal, the other route of the reference light receiving module is used for simultaneously transmitting a second optical signal, returning and receiving a third optical signal reflected by the detection target, and carrying out channel separation on the third optical signal through the returning light receiving module and then converting the third optical signal into a second electric signal. And scanning point cloud data of a detection target through the cross-correlation characteristics of the first electric signal and the second electric signal under each detection channel of the signal processing module. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
On the basis of any one of the above embodiments, generating point cloud data of a detection target based on the first electric signal and the second electric signal includes: and performing autocorrelation detection based on the first electric signal and the second electric signal to obtain the time delay and reflectivity information of each detection channel.
Specifically, in step 505, the signal processing module uses the received first electrical signal and the second electrical signal under each probing channel to perform correlation detection on the corresponding probing channel at the same time, and demodulates the time delay and reflectivity strength information of each probing channel from the peaks of the first electrical signal and the second electrical signal.
And generating point cloud data of the detection target based on the time delay and reflectivity information of each detection channel.
Specifically, the signal processing module performs fusion according to the time delay and reflectivity strength information of each detection channel to obtain point cloud data such as depth, reflectivity and the like of each scanning point of a detection target in a three-dimensional space.
It is understood that, after step 505, the result of obtaining each point cloud data may be displayed in front end through a display device.
According to the embodiment of the invention, based on the cross-correlation characteristics of the first electric signal and the second electric signal under each detection channel, the time delay and reflectivity information of each detection channel is demodulated, and then fusion scanning is carried out on the time delay and reflectivity information to obtain point cloud data of a detection target. The system complexity of the laser radar can be simplified, the cost is reduced, and meanwhile, the high isolation of each channel is also considered, and further, the anti-interference capability and the space scanning efficiency in the detection process are improved.
Fig. 6 illustrates a physical structure diagram of an electronic device, which may include, as shown in fig. 6: a processor (processor)610, a communication Interface 620, a memory (memory)630 and a communication bus 640, wherein the processor 610, the communication Interface 620 and the memory 630 complete communication with each other through the communication bus 640. Processor 610 may invoke logic instructions in memory 630 to perform a direct detection based detection method for a lidar system, the method comprising: the signal transmitting module transmits laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal; the receiving and transmitting module transmits the incident second optical signal to a detection target and receives a third optical signal returned after scattering by the detection target; the reference light receiving module acquires a first electric signal according to the incident first optical signal; the return light receiving module acquires a second electrical signal according to the incident third optical signal; the signal processing module generates point cloud data of a detection target based on the first electric signal and the second electric signal; the chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
In addition, the logic instructions in the memory 630 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention or a part thereof which substantially contributes to the prior art may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention further provides a computer program product, the computer program product comprising a computer program, the computer program being stored on a non-transitory computer-readable storage medium, wherein when the computer program is executed by a processor, the computer is capable of executing the detection method of the direct detection-based lidar system provided by the above methods, and the method comprises: the signal transmitting module transmits laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal; the receiving and transmitting module transmits the incident second optical signal to a detection target and receives a third optical signal returned after scattering by the detection target; the reference light receiving module acquires a first electric signal according to the incident first optical signal; the return light receiving module acquires a second electric signal according to the incident third optical signal; the signal processing module generates point cloud data of a detection target based on the first electric signal and the second electric signal; the chaotic detection signal comprises laser signals with multiple parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program, which when executed by a processor, implements a method for detecting a laser radar system based on direct detection provided by the above methods, the method including: the signal transmitting module transmits laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal; the receiving and transmitting module transmits the incident second optical signal to a detection target and receives a third optical signal which is scattered by the detection target and then returns; the reference light receiving module acquires a first electric signal according to the incident first optical signal; the return light receiving module acquires a second electric signal according to the incident third optical signal; the signal processing module generates point cloud data of a detection target based on the first electric signal and the second electric signal; the chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. Based on the understanding, the above technical solutions substantially or otherwise contributing to the prior art may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the various embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A direct detection based lidar system comprising: the device comprises a signal transmitting module, a transceiving module, a reference light receiving module, a return light receiving module and a signal processing module;
the signal transmitting module is used for transmitting laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal;
the transceiver module is used for transmitting the incident second optical signal to a detection target and receiving a third optical signal returned after scattering by the detection target;
the reference light receiving module is used for acquiring a first electric signal according to the incident first optical signal;
the return light receiving module is used for acquiring a second electric signal according to the incident third optical signal;
the signal processing module is used for generating point cloud data of the detection target based on the first electric signal and the second electric signal;
the chaotic detection signal comprises a laser signal with multiple parallel detection channels, and the phases of the first optical signal and the second optical signal are the same as the chaotic detection signal.
2. The direct detection-based lidar system of claim 1, wherein the optical-frequency comb generator comprises one or more of a microcavity optical comb, a mode-locked laser, and an electro-optical comb.
3. The direct detection-based lidar system of claim 2, wherein the reference light receiving module comprises a first demultiplexing unit and a first photodetector array.
4. The direct detection-based lidar system of claim 3, wherein the return light receiving module comprises a second demultiplexing unit and a second photodetector array.
5. The direct detection-based lidar system of claim 3, wherein the return light receiving module comprises a second photodetector array.
6. The direct-detection-based lidar system of claim 1, wherein the transceiver module comprises a circulator and a transmit unit;
the first end of the circulator is connected with the signal transmitting module, the second end of the circulator is connected with the transmitting unit, and the third end of the circulator is connected with the return light receiving module.
7. The direct detection-based lidar system of any of claims 1-6, further comprising a display device for displaying the point cloud data.
8. A detection method based on a direct detection based lidar system according to any of claims 1 to 7, comprising:
the signal transmitting module transmits laser to the optical frequency comb generator to generate a parallel chaotic detection signal, and the parallel chaotic detection signal is divided into a first optical signal and a second optical signal;
the receiving and transmitting module transmits the incident second optical signal to a detection target and receives a third optical signal returned after scattering by the detection target;
the reference light receiving module acquires a first electric signal according to the incident first optical signal;
the return light receiving module acquires a second electrical signal according to the incident third optical signal;
the signal processing module generates point cloud data of the detection target based on the first electric signal and the second electric signal;
the chaotic detection signal comprises a plurality of laser signals with parallel detection channels, and the first optical signal and the second optical signal are the same as the chaotic detection signal.
9. The direct detection-based lidar system detection method of claim 8, wherein the generating point cloud data of the detection target based on the first electrical signal and the second electrical signal comprises:
performing autocorrelation detection based on the first electrical signal and the second electrical signal to obtain time delay and reflectivity information of each detection channel;
and generating point cloud data of the detection target based on the time delay and reflectivity information of each detection channel.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the detection method according to claim 8 or 9 when executing the program.
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