CN116027300A - Laser radar device based on time lens effect - Google Patents
Laser radar device based on time lens effect Download PDFInfo
- Publication number
- CN116027300A CN116027300A CN202310129477.9A CN202310129477A CN116027300A CN 116027300 A CN116027300 A CN 116027300A CN 202310129477 A CN202310129477 A CN 202310129477A CN 116027300 A CN116027300 A CN 116027300A
- Authority
- CN
- China
- Prior art keywords
- pulse sequence
- radio frequency
- laser pulse
- outlet
- laser
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Landscapes
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a laser radar device based on time lens effect, which is used in a flight time testing method, and comprises: the laser radar device comprises a time lens system, a pulse laser source, an optical fiber circulator, a light beam transceiver, an optical amplifier, a photoelectric detector and a high-speed oscilloscope, wherein the time lens system is arranged at a receiving end of the laser radar device and is used for carrying out pulse width compression and peak power lifting on a received echo laser pulse sequence during ranging. The time lens system is arranged in the laser radar device to perform pulse width compression and peak power lifting on the received echo laser pulse sequence, so that the effect of improving the capability of the laser radar device for extracting a target object scattering signal from noise and the range measurement is achieved.
Description
Technical Field
The invention relates to the technical field of lasers, in particular to a laser radar device based on a time lens effect.
Background
The laser radar technology has the advantages of long detection distance, high ranging precision, high measurement speed and the like, and has wide application in the fields of automatic driving, intelligent robots, topographic mapping, atmosphere detection and the like. Under the push of the actively developed autopilot technology, the lidar technology is expected to have a global market size of more than one hundred billion RMB.
Currently, the time-of-flight test method is the most widely used ranging method in the laser radar technology, and the principle of the method is to calculate the distance of an object by measuring the time delay between a scattering pulse and a transmitting pulse of the object. In the mainstream time-of-flight test method, a 905nm or 1550nm pulse laser light source is used as a transmitting end and an avalanche photodiode is arranged for signal receiving. Compared with the laser pulse in the 905nm wave band, the 1550nm laser pulse has the advantages of high peak power, long detectable distance, high eye safety and the like, so that the 1550nm laser pulse has an important position in a laser radar ranging system of a time-of-flight test method. In lidar devices employing time-of-flight testing of 1550nm pulsed lasers, the reception of scattered signals from the target often depends on avalanche photodiodes. However, the limited gain of the avalanche photodiode limits the signal amplification capability, so that the weak signal is submerged in noise, and finally the ranging range of the laser radar device is limited. Therefore, how to enhance the capability of extracting the scattering signal of the target object from noise, improve the signal-to-noise ratio of the received signal, and prolong the range of distance measurement becomes a key scientific problem to be solved in the laser radar device of the time-of-flight test method.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: aiming at the existing technical defects in the laser radar device of the time-of-flight test method, the invention provides a laser radar device based on a time lens effect, which aims to enhance the capability of extracting a target object scattering signal from noise and realize the improvement of a ranging range and a ranging resolution.
The invention is realized by the following technical scheme: a lidar device based on time lens effect for use as a lidar device in a time-of-flight test method, comprising: and the time lens system is arranged at the receiving end of the laser radar device and is used for carrying out pulse width compression and peak power lifting on the received echo laser pulse sequence during ranging.
Further arrangement of the invention, the temporal lens system comprises: the device comprises a radio frequency signal generation module, a radio frequency amplifier, an electro-optic phase modulator and a dispersion medium;
the radio frequency signal generation module is connected with the radio frequency amplifier and is used for outputting square wave signals and sine wave signals with synchronous clocks;
the radio frequency amplifier is respectively connected with the radio frequency signal generating module and the electro-optic phase modulator, and is used for amplifying the sine wave signal in a power mode and driving the electro-optic phase modulator by using the sine wave signal after the power amplification;
the electro-optic phase modulator is respectively connected with the radio frequency amplifier and the dispersion medium, and the dispersion medium is used for providing dispersion and enabling the echo laser pulse sequence to be converted into a pulse cluster consisting of a plurality of narrow pulses in a time domain;
the time lens system obtains a specific dispersion value of the dispersion medium according to the modulation depth of the electro-optic phase modulator and through numerical optimization, so that the echo laser pulse sequence is converted into a pulse cluster consisting of a plurality of narrow pulses.
The invention further provides that the method further comprises the following steps: a pulse laser source, an optical fiber circulator, a light beam transceiver, an optical amplifier, a photoelectric detector and a high-speed oscilloscope;
the pulse laser source is respectively connected with the radio frequency signal generation module and the optical fiber circulator and is used for outputting a laser pulse sequence;
the optical fiber circulator is provided with a first outlet, a second outlet and a third outlet, the first outlet is connected with the pulse laser source, the second outlet is connected with the optical beam transceiver, the third outlet is connected with the optical amplifier, the optical fiber circulator is used for transmitting the laser pulse sequence from the first outlet to the second outlet and then transmitting the laser pulse sequence to the optical beam transceiver, and the optical fiber circulator is also used for transmitting the received echo laser pulse sequence from the second outlet to the third outlet;
the beam transceiver is connected with the second outlet, and is used for enlarging the size of a transmitting end of the laser pulse sequence, compressing the divergence angle of the laser pulse sequence and irradiating the laser pulse sequence to a target object;
the optical amplifier is respectively connected with the third outlet and the electro-optic phase modulator, and is used for amplifying the power of the echo laser pulse sequence and transmitting the echo laser pulse sequence with the amplified power to the electro-optic phase modulator for time domain phase modulation;
the photoelectric detector is respectively connected with the dispersion medium and the high-speed oscilloscope, and is used for converting the echo laser pulse sequence processed by the time lens system into a radio frequency pulse sequence;
the high-speed oscilloscope is connected with the photoelectric detector, the high-speed oscilloscope is in clock synchronization with the radio frequency signal generation module, and the high-speed oscilloscope is used for observing and measuring the radio frequency pulse sequence.
According to the further arrangement of the invention, the working bandwidth of the radio frequency amplifier is 1-6GHz.
According to the invention, the high-level voltage of the square wave signal output by the radio frequency signal generation module is 5V, the low-level voltage is 0V, and the duty ratio of the square wave signal can be adjusted.
In a further arrangement of the invention, the electro-optic phase modulator is a silicon-based phase modulator or a thin film lithium niobate phase modulator.
According to the invention, the laser pulse sequence output by the pulse laser source is synchronous with the sine wave signal clock output by the radio frequency signal generating module.
According to the further arrangement of the invention, the central wavelength of the laser pulse sequence output by the pulse laser source is 1550nm.
In a further arrangement of the invention, the optical beam transceiver is an optical phased array chip or an optical lens.
The optical amplifier is a erbium-doped optical fiber amplifier, an erbium-ytterbium co-doped optical fiber amplifier or a semiconductor optical amplifier.
The invention has the beneficial effects that:
the invention provides a laser radar device based on time lens effect, which is used as a laser radar device in a time-of-flight test method, and comprises the following components: and the time lens system is arranged at the receiving end of the laser radar device and is used for carrying out pulse width compression and peak power lifting on the received echo laser pulse sequence during ranging. The time lens system is arranged in the laser radar device to perform pulse width compression and peak power lifting on the received echo laser pulse sequence, so that the capability of the laser radar device for extracting a target object scattering signal from noise is enhanced, and the effects of improving the ranging range and the ranging resolution are achieved.
Drawings
Fig. 1 is a schematic structural diagram of a preferred embodiment of a lidar device according to the present invention.
Fig. 2 is a simulation diagram of a laser pulse sequence output by the pulsed laser light source in fig. 1.
Fig. 3 is a simulation diagram of an echo laser pulse sequence received by the optical beam transceiver in fig. 1.
Fig. 4 is a simulation diagram of an echo laser pulse sequence before and after processing the echo laser pulse sequence by the time lens system in fig. 1.
Fig. 5 is a schematic structural diagram of another embodiment of a lidar device according to the present invention.
Description of the main reference signs
100. A laser radar device; A. a target; 1. a temporal lens system; 2. a pulsed laser source; 3. an optical fiber circulator; 4. a light beam transceiver; 5. an optical amplifier; 6. a photodetector; 7. a high-speed oscilloscope; 101. a radio frequency signal generation module; 102. a radio frequency amplifier; 103. an electro-optic phase modulator; 104. a dispersive medium; 401. a light beam emission part; 402. a light beam receiving section; a. a first outlet; b. a second outlet; c. and a third outlet.
Detailed Description
The invention provides a laser radar device based on a time lens effect, which is suitable for the technical field of laser, and for making the purposes, technical schemes and effects of the invention clearer and more definite, the invention is further described in detail below by referring to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In the description and claims, unless the context clearly dictates otherwise, the terms "a" and "an" and "the" may refer to either a single or a plurality.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
Examples
The invention introduces the concept of time lens effect into the laser radar device of the time-of-flight test method, namely, a time lens system is added into the laser radar device of the basic time-of-flight test method. As shown in fig. 1, the present invention provides a preferred embodiment of a lidar device 100 based on time lens effect, which can be applied to a time-of-flight test method, wherein a time lens system 1 is disposed at a receiving end of the lidar device 100 to improve a signal-to-noise ratio of a received signal of the lidar device 100, prolong a ranging range, and achieve an effect of improving ranging accuracy and ranging resolution of the lidar device 100.
Referring to fig. 1, in a preferred embodiment of the present invention, the lidar device 100 includes: the time lens system 1, the pulse laser source 2, the optical fiber circulator 3, the optical beam transceiver 4, the optical amplifier 5, the photoelectric detector 6 and the high-speed oscilloscope 7. The laser radar apparatus 100 emits a laser pulse sequence to a target object a and receives an echo laser pulse sequence reflected from the target object a during ranging, so that the time lens system 1 is disposed at a receiving end of the laser radar apparatus, and the time lens system 1 is configured to perform pulse width compression and peak power boost on the received echo laser pulse sequence during ranging. The time lens system 1 comprises a radio frequency signal generation module 101, a radio frequency amplifier 102, an electro-optic phase modulator 103 and a dispersion medium 104, wherein the radio frequency signal generation module 101, the radio frequency amplifier 102, the electro-optic phase modulator 103 and the dispersion medium 104 are built at a receiving end of the laser radar device 100.
Because the pulse width of the echo laser pulse sequence directly influences the distance measurement resolution, the distance measurement accuracy is influenced by the distance measurement resolution. The pulse width and ranging resolution satisfy the following mathematical relationship: pulse width = 2 x ranging resolution +.. Meanwhile, according to the relation between the ranging precision and the ranging resolution: the square of the distance measurement accuracy is proportional to the square of the distance measurement resolution, so that the value of the distance measurement resolution can be reduced by narrowing the pulse width, and the value of the distance measurement accuracy is further reduced. Therefore, narrowing the pulse width can improve the ranging resolution and ranging accuracy of the lidar system. Therefore, in the preferred embodiment of the present invention, the time lens system 1 is used for performing pulse width compression and peak power boost on the received echo laser pulse sequence during ranging, so as to improve the ranging accuracy and the ranging resolution of the laser radar apparatus 100.
Further, in the preferred embodiment of the present invention, the rf signal generating module 101 is connected to the pulse laser source 2 and the rf amplifier 102, respectively, and the rf signal generating module 101 is configured to output a square wave signal and a sine wave signal with synchronous clocks; the radio frequency signal generating module 101 is connected with the pulse laser source 2 and is used for providing the square wave clock signal for the pulse laser source 2; the radio frequency signal generating module 101 is further connected to the radio frequency amplifier 102, and is configured to transmit the sine wave signal to the radio frequency amplifier 102 for power amplification.
The pulse laser source 2 is respectively connected with the radio frequency signal generating module 101 and the optical fiber circulator 3, the pulse laser source 2 is used for outputting a laser pulse sequence, the output laser pulse sequence is in clock synchronization with the square wave signal output by the radio frequency signal generating module 101, and the repetition frequency of the laser pulse sequence is determined by the repetition frequency of the square wave signal.
The radio frequency amplifier 102 is respectively connected with the radio frequency signal generating module 101 and the electro-optic phase modulator 103, and the radio frequency amplifier 102 is configured to receive and amplify the sine wave signal, and drive the electro-optic phase modulator 103 with the sine wave signal after power amplification.
Specifically, referring to fig. 1, in a preferred embodiment of the present invention, when a specific measurement experiment is performed, the rf signal generating module 101 outputs two paths of rf signals with synchronous clocks, one path of rf signal is the square wave signal, the high level voltage of the square wave signal is 5V, the low level voltage is 0V, the repetition frequency of the square wave signal can reach MHz magnitude, the repetition frequency of the square wave signal can be specifically set to 1MHz, and the duty ratio of the square wave signal can be adjusted. The other path of radio frequency signal output by the radio frequency signal generating module 101 is the sine wave signal, the frequency adjustable range of the sine wave signal is 1-6GHz, the average power is kept above 0dBm in the adjustable frequency range, and in a specific experiment, the average power of the sine wave signal is kept at 0dBm in the adjustable frequency range.
The pulse laser source 2 is a high-power pulse fiber laser, the simulation result of the laser pulse sequence output by the pulse laser source is shown in fig. 2, the output light pulse, i.e. the laser pulse sequence, is synchronous with the square wave signal clock, the center wavelength of the laser pulse sequence is 1550nm, the repetition frequency can reach MHz magnitude, and in the preferred embodiment, the repetition frequency is synchronous with the square wave signal and is set to be 1MHz. In addition, the pulse width of the laser pulse sequence output by the pulse laser source 2 can be adjusted within the range of 2-20ns, and the peak power of the laser pulse sequence can reach hundred watts, specifically 500W.
The radio frequency amplifier 102 is a high-power high-gain power amplifier, the working bandwidth of the radio frequency amplifier is in the GHz level, the specific working bandwidth can be 1-6GHz, and the output power of the radio frequency amplifier 102 can reach 30dBm; and the radio frequency amplifier 102 is connected to the electro-optic phase modulator 103, and the radio frequency amplifier 102 outputs the sine wave signal after power amplification to drive the electro-optic phase modulator 103.
With continued reference to fig. 1, in a preferred embodiment of the present invention, the fiber optic circulator 3 has a first outlet a, a second outlet b and a third outlet c, the first outlet a is connected to the pulsed laser source 2, the second outlet b is connected to the optical beam transceiver 4, the third outlet c is connected to the optical amplifier 5, the fiber optic circulator 3 is configured to transmit the laser pulse sequence from the first outlet a to the second outlet b, and then transmit the laser pulse sequence to the optical beam transceiver 4, and the fiber optic circulator 3 is further configured to transmit the received echo laser pulse sequence from the second outlet b to the third outlet c to the optical amplifier 5.
Specifically, with continued reference to fig. 1, in a preferred embodiment of the present invention, the laser radar apparatus 100 guides the laser pulse sequence emitted from the pulsed laser source 2 from the first outlet a to the second outlet b through the arrangement of the optical fiber circulator 3, and sends the emitted laser pulse sequence to the optical beam transceiver 4; the received sequence of echo laser pulses passing through the beam transceiver 4 is then passed from the second outlet b to the third outlet c. Namely, a light beam coaxial receiving system is realized through the optical fiber circulator 3, so that the transmitting end and the receiving end of the light beam are the same end, and the bidirectional transmission of the laser pulse sequence and the echo laser pulse sequence is realized.
With continued reference to fig. 1, in a preferred embodiment of the present invention, further, when the target object a is detected, the optical beam transceiver 4 is used as a transmitting end and a receiving end of the lidar device 100, and interacts with the target object a through the optical beam transceiver 4. In the laser radar apparatus 100, the beam transceiver 4 functions as a laser beam expander, the beam transceiver 4 is connected to the second outlet b of the optical fiber circulator 3, the beam transceiver 4 is configured to expand a size of a transmitting end of the laser pulse sequence to be emitted, compress a divergence angle of the laser pulse sequence to be emitted, and transmit and irradiate the laser pulse sequence to the target object a; after the laser pulse sequence is sent to the target object a, the target object a scatters back to the echo laser pulse sequence, and a simulation result of the echo laser pulse sequence received by the beam transceiver is shown in fig. 3. The beam transceiver 4 also receives and transmits the echo laser pulse train scattered by the object a to the third outlet c of the fiber optic circulator 3.
In a further implementation of this embodiment, the optical beam transceiver 4 may be an optical phased array chip or an optical lens.
Specifically, the optical beam transceiver 4 may be an optical lens such as a silicon-based optical phased array chip, a MEMS (Micro-Electro-Mechanical System ) galvanometer, or a biaxial rotation galvanometer system, but is not limited thereto.
Further, the optical phased array chip may be adapted to the optical transceiver 4, i.e. the optical transceiver 4 may be configured as an optical phased array chip, which is a silicon-based optical chip, for improving the beam steering and beam receiving capabilities of the laser radar device 100. The optical phased array chip can realize light beam scanning without a mechanical structure, has the characteristics of wide scanning range, high pointing precision, large-size receiving aperture and the like. When the optical beam transceiver 4 is set as an optical phased array chip, a laser pulse sequence to be emitted is coupled to the optical phased array chip through an optical fiber, the chip is integrated by hundreds of phase shift waveguides, the phase shift of each waveguide is precisely controlled by a control circuit, and finally, scannable light spots are formed in the far field of the emergent end of the optical phased array chip, so that precise scanning of the target object A is realized. The optical pulse sequence reflected by the object A is also received by the optical phased array chip, is transmitted to the third outlet c along the original path through the second outlet b of the optical fiber circulator 3, and finally reaches the time lens system 1 for signal processing.
In other embodiments, the beam transceiver portion may use a different-axis receiving mode to perform transmission and reception instead of the coaxial receiving mode, and referring to fig. 5 specifically, another embodiment of the present invention provides a lidar device 100 substantially the same as the preferred embodiment of the present invention, which is different from the preferred embodiment of the present invention in that the beam transceiver portion may use a different-axis receiving mode to perform transmission and reception instead of the coaxial receiving mode. In another embodiment of the present invention, the transmitting end and the receiving end of the beam transceiver 4 are separated into a beam transmitting portion 401 and a beam receiving portion 402, and the laser pulse sequence output by the pulse laser source 2 is directly transmitted to the beam transmitting portion 401; and the echo laser pulse train scattered by the object a is received by the beam receiving section 402, and the echo laser pulse train is sent to the optical amplifier 5. Therefore, since the transmitting end and the receiving end of the optical beam transceiver 4 are separated, the arrangement of the optical fiber circulator 3 in the preferred embodiment shown in fig. 1 can be omitted. Other portions of the lidar device 100 according to another embodiment of the present invention have the same or similar structure as the preferred embodiment of the present invention, and will not be described herein.
With continued reference to fig. 1, in a preferred embodiment of the present invention, the optical amplifier 5 is connected to the third outlet c and the electro-optic phase modulator 103, and the optical amplifier 5 is configured to amplify the power of the echo laser pulse sequence and transmit the echo laser pulse sequence with amplified power to the electro-optic phase modulator 103 for performing time domain phase modulation.
Specifically, the optical amplifier 5 receives the echo laser pulse train transmitted from the third outlet c, and power-amplifies the received echo laser pulse train. The optical amplifier 5 may be an erbium-doped fiber amplifier (EDFA), an erbium-ytterbium co-doped fiber amplifier (EYDFA), a Semiconductor Optical Amplifier (SOA), or the like, which may amplify the optical signal power.
With continued reference to fig. 1, in a preferred embodiment of the present invention, the electro-optic phase modulator 103 is connected to the rf amplifier 102, the optical amplifier 5 and the dispersive medium 104, respectively. The electro-optical phase modulator 103 is configured to perform time-domain phase modulation on the echo laser pulse sequence with amplified power, the electro-optical phase modulator 103 further receives and uses the sine wave signal output by the radio frequency amplifier 102 to perform time-domain secondary phase modulation on the echo laser pulse sequence output by the optical amplifier 5, and the electro-optical phase modulator 103 introduces approximately linear chirp in the time domain of the echo laser pulse sequence.
Specifically, the electro-optic phase modulator 103 may be a silicon-based phase modulator or a thin film lithium niobate phase modulator, but is not limited thereto. The working bandwidth of the electro-optic phase modulator 103 is in GHz magnitude, specifically may be 10GHz, and the phase modulation depth relationship provided by the electro-optic phase modulator 103 is:
wherein, gamma is the phase modulation depth, V p V being the peak voltage of the sine wave signal π Is a half-wave voltage of the electro-optic phase modulator 103.
With continued reference to fig. 1, in a preferred embodiment of the invention, the dispersive medium 104 is connected to the electro-optic phase modulator 103 and the photodetector 6, respectively. The dispersive medium 104 is connected with the electro-optic phase modulator 103, and provides dispersion for the echo laser pulse sequence after phase modulation so as to compensate approximate linear chirp of the echo laser pulse sequence, so that the echo laser pulse sequence is converted into a pulse cluster consisting of a plurality of narrow pulses in a time domain, a single narrow pulse in the pulse cluster is close to a bandwidth limit pulse, and the peak power of the pulse cluster is obtained by optimal amplification factor.
Specifically, the dispersion medium 104 may be a single mode fiber or a long chirped bragg fiber grating. Furthermore, the total dispersion value D of the dispersive medium 104 should satisfy the approximate relationship:
wherein c is the light velocity, lambda is the central wavelength of the laser pulse 1550nm, f m For the frequency of the sine wave signal, γ is the phase modulation depth provided by the electro-optic phase modulator 103.
Therefore, with continued reference to fig. 1, in a preferred embodiment of the present invention, the time lens system 1 obtains a specific dispersion value of the dispersive medium 104 according to the modulation depth of the electro-optic phase modulator 103 and through numerical optimization, so as to convert the echo laser pulse sequence into a pulse cluster composed of a plurality of narrow pulses.
Specifically, when the echo laser pulse sequence passes through the electro-optic phase modulator 103, the radio frequency port of the electro-optic phase modulator 103 is added with the sine wave signal of the radio frequency amplified by power, so that the echo laser pulse sequence is approximately modulated by a secondary phase, and the effect is that approximately linear chirp is introduced to the echo laser pulse sequence in the time domain. Then, taking the dispersive medium 104 as a single-mode dispersion fiber as an example, a roll of single-mode dispersion fiber is used to compensate the linear chirp of the modulated echo laser pulse sequence back, and the final effect is that one echo laser pulse sequence is converted into a pulse cluster composed of a plurality of narrow pulses with narrower pulse widths. Without energy loss, the pulse width is narrowed, and the peak power of a single pulse is increased. By increasing the power of the rf signal and matching with the dispersive medium 104 with a specific dispersion value, the pulse width of the final pulse is the narrowest, and the corresponding peak power is the highest, so that the ratio of the peak power to the peak power of the original echo laser pulse sequence is larger, and the obtained peak power amplification factor of the pulse cluster is also the optimal.
Furthermore, it has been found through specific simulations that only a specific one of the dispersion values of the dispersive medium 104 will cause the final optical pulse width to be narrowest and the corresponding peak power to be highest. And, the dispersion value of the dispersive medium is correlated with the modulation depth of the electro-optic phase modulator 103. The echo laser pulse train is converted into a pulse train consisting of a plurality of narrow pulses depending on the modulation depth of the electro-optical phase modulator and the specific dispersion value of the dispersive medium. The single narrow pulse in the pulse cluster is close to the bandwidth limit pulse, and the peak power of the pulse cluster is amplified by the optimal magnification factor, so that the time lens system can re-gather the echo laser pulse sequence energy in the narrow pulse of the pulse cluster in the time domain, the time domain distribution of bottom noise is unchanged, and finally, the time domain signal-to-noise ratio of the pulse cluster is improved, and the ranging range of the laser radar device 100 is increased.
With continued reference to fig. 1, in a preferred embodiment of the present invention, the photodetector 6 is connected to the dispersive medium 104 and the high-speed oscilloscope 7, respectively, and the photodetector 6 is configured to convert the echo laser pulse sequence processed by the time lens system 1 into a radio frequency pulse sequence; the high-speed oscilloscope 7 is connected with the photoelectric detector 6, the high-speed oscilloscope 7 is in clock synchronization with the radio frequency signal generation module 101, and the high-speed oscilloscope 7 is used for observing and measuring the radio frequency pulse sequence.
Specifically, the photodetector 6 is a high-speed single-ended photodetector, and the photodetector 6 may be an InGaAs (indium gallium arsenide) photodiode, an InGaAs avalanche diode, or a Ge-Si (germanium silicon) photodetector, but is not limited thereto. The working bandwidth of the photoelectric detector 6 is not lower than 50GHz, and the detectors with the working bandwidths of 50GHz, 100GHz and the like can be replaced according to actual conditions; the working wavelength of the photodetector 6 is covered with 1500nm-1600nm.
The photodetector 6 is connected to the dispersive medium 104, and may detect the echo laser pulse sequence processed by the time lens system 1, that is, the pulse cluster, and photoelectrically convert a laser signal into an electrical signal, so as to obtain the radio frequency pulse sequence, where the radio frequency pulse sequence is a radio frequency narrow pulse cluster, and the repetition frequency of the radio frequency narrow pulse cluster is in the order of MHz, specifically may be 1MHz, and there are multiple radio frequency narrow pulses in one period. The radio frequency narrow pulse spacing is of the order of ns, which may be 0.29ns in particular.
With continued reference to fig. 1, the photodetector 6 is connected to the dispersive medium 104 and the high-speed oscilloscope 7, respectively. The photodetector 6 is connected to the dispersive medium 104, and is configured to detect the pulse cluster, and convert the pulse cluster laser signal into an electrical signal, so as to obtain a radio frequency narrow pulse sequence.
In addition, the high-speed oscilloscope 7 is connected with the photodetector 6 and is used for collecting and displaying the radio frequency narrow pulse sequence, and the high-speed oscilloscope can stably observe and accurately measure the radio frequency narrow pulse sequence with complex time domain waveforms. And the time information of the radio frequency narrow pulse sequence of the high-speed oscilloscope 7 can be calibrated to calculate the distance of the target object A. The working bandwidth of the high-speed oscilloscope 7 should be not lower than 50GHz, and may be specifically set to be 50GHz; the maximum time scale of the high-speed oscilloscope 7 is not smaller than 1 mu s per cell, and in practical application, the maximum time scale can be set to be 1 mu s per cell.
Further, in practical application, the distance of the target object a may be calculated by the following method: the waveform and time points of the received light pulse sequence can be observed and recorded with the high-speed oscilloscope 7, while at the same time the actual distance of the target object a is calibrated by using a standard commercial range finder. According to the calibration method, the relationship between the calibration distance and the time position of the optical pulse sequence can be linearly fitted by measuring different distances of the target object A and the time position of the corresponding echo optical pulse sequence on the high-speed oscilloscope 7 for a plurality of times. Then, a linear equation of the distance to be measured and the time position of the light pulse sequence can be obtained through linear regression. And finally, when testing other distance values, substituting the time information of the light pulse sequence acquired on the high-speed oscilloscope 7 into the linear regression equation to calculate the actual distance of the target object A.
Referring to fig. 1-4, the laser radar apparatus 100 according to the preferred embodiment of the present invention operates as follows:
when ranging is specifically performed, the radio frequency signal generating module 101 outputs two radio frequency signals respectively, one radio frequency signal is a square wave signal, and the one radio frequency signal is used as a clock signal to control the pulse laser source 2 to output a laser pulse sequence which is synchronous with the clock of the square wave signal and has the same repetition frequency; the other path of radio frequency signal is a sine wave signal, and the sine wave signal is transmitted to the radio frequency amplifier 102 for power amplification. The laser pulse sequence output by the pulse laser source 2 is transmitted from the first outlet a to the second outlet b of the optical fiber circulator 3, and is irradiated onto the target object a through the beam transceiver 4.
The sequence of echo laser pulses scattered by the object a is then received by the beam transceiver 4 and transmitted through the second outlet b of the fiber optic circulator 3 to the third outlet c into the optical amplifier 5. And the echo laser pulse sequence is subjected to power pre-amplification by the optical amplifier 5 to obtain the echo laser pulse sequence with amplified power, and the echo laser pulse sequence is transmitted to the electro-optic phase modulation for time domain phase modulation. The electro-optic phase modulator 103 performs secondary phase modulation on the echo laser pulse sequence with amplified power under the driving of the sine wave signal output by the radio frequency amplifier 102, and introduces approximately linear chirp, so as to obtain the echo laser pulse sequence after phase modulation. The dispersive medium 104 provides appropriate dispersion to the echo laser pulse train to compensate for the chirp of the echo laser pulse train after phase modulation, thereby enabling pulse width compression and peak power boost of the echo laser pulse train after phase modulation.
To this end, with continued reference to fig. 1, the rf signal generating module 101, the rf amplifier 102, the electro-optic phase modulator 103 and the dispersive medium 104 constitute the time lens system 1. The time lens system 1 converts the echo laser pulse sequence into a pulse cluster composed of a plurality of narrow pulses, and as shown in fig. 4, the simulation result of fig. 4 compares the time-domain variation of the echo laser pulse sequence before and after the time lens system processing, and indicates the time before the time lens system 1 is used for processing, and indicates the time after the time lens system 1 is used for processing by using an output. Fig. 4 (b) is a partial enlargement of the time domain of fig. 4 (a), the time window length of fig. 4 (a) is 2000ns, and the time window length of fig. 4 (b) is 50ns. Wherein a single narrow pulse within the pulse train is close to the bandwidth limited pulse. In addition, the time lens system 1 re-collects the echo laser pulse sequence energy in the narrow pulse of the pulse cluster in the time domain, the time domain distribution of bottom noise is not changed, and finally, the time domain signal-to-noise ratio of the pulse cluster is improved, and the range of the laser radar device 100 is increased. The time lens system is arranged to achieve the effects of pulse width compression and peak power lifting of the echo laser pulse sequence.
Therefore, the time lens system 1 composed of the radio frequency signal generating module 101, the radio frequency amplifier 102, the electro-optic phase modulator 103 and the dispersive medium 104 completes the peak power elevation and pulse width compression of the echo laser pulse sequence, and a pulse cluster composed of a plurality of narrow pulses is obtained. The pulse clusters are subjected to photoelectric conversion by the photoelectric detector 6 to obtain a radio frequency narrow pulse sequence. And finally, the high-speed oscilloscope 7 carries out high-speed acquisition and measurement on the radio frequency narrow pulse sequence and displays the time domain waveform of the radio frequency narrow pulse sequence. Finally, the distance of the target object A is calculated by calibrating the time information of the radio frequency narrow pulse sequence, and the distance detection of the target object A is completed.
In summary, the laser radar apparatus 100 according to the preferred embodiment of the present invention performs time-domain compression on a weak echo laser pulse sequence and improves the peak power of a single pulse by using the advantages of pulse width compression and peak power improvement of the time lens system 1 in cooperation with the laser radar ranging system of the time-of-flight test method, so as to enhance the time-domain signal-to-noise ratio of the echo laser pulse sequence, so that the laser radar apparatus 100 can effectively extract echo signals from noise, and achieve the effect of greatly improving the ranging range and the measurement accuracy.
In summary, the laser radar device 100 provided by the invention has the following advantages:
according to the laser radar device provided by the invention, the time lens system is arranged in the laser radar device, and the time lens system is used for carrying out pulse width compression and peak power lifting on the received echo laser pulse sequence, so that the effects of improving the capability of the laser radar device for extracting a target object scattering signal from noise, the ranging precision and the ranging resolution are achieved.
It should be understood that the above description of the related technical solutions of the present invention is specific and should not be construed as limiting the scope of the present invention, which is defined by the appended claims. Those skilled in the art should not need any inventive changes or modifications according to the above-mentioned preferred embodiments of the present invention, and all such technical solutions are included in the scope of the present invention.
Claims (10)
1. A lidar device based on time lens effect for use as a lidar device in a time-of-flight test method, comprising: and the time lens system is arranged at the receiving end of the laser radar device and is used for carrying out pulse width compression and peak power lifting on the received echo laser pulse sequence during ranging.
2. The lidar device according to claim 1, wherein the time lens system comprises: the device comprises a radio frequency signal generation module, a radio frequency amplifier, an electro-optic phase modulator and a dispersion medium;
the radio frequency signal generation module is connected with the radio frequency amplifier and is used for outputting square wave signals and sine wave signals with synchronous clocks;
the radio frequency amplifier is respectively connected with the radio frequency signal generating module and the electro-optic phase modulator, and is used for amplifying the sine wave signal power and driving the electro-optic phase modulator by using the sine wave signal after power amplification;
the electro-optic phase modulator is respectively connected with the radio frequency amplifier and the dispersion medium, and the dispersion medium is used for providing dispersion and enabling the echo laser pulse sequence to be converted into a pulse cluster consisting of a plurality of narrow pulses in a time domain;
the time lens system obtains a specific dispersion value of the dispersion medium according to the modulation depth of the electro-optic phase modulator and through numerical optimization, so that the echo laser pulse sequence is converted into a pulse cluster consisting of a plurality of narrow pulses.
3. The lidar device according to claim 2, further comprising:
a pulse laser source, an optical fiber circulator, a light beam transceiver, an optical amplifier, a photoelectric detector and a high-speed oscilloscope;
the pulse laser source is respectively connected with the radio frequency signal generation module and the optical fiber circulator and is used for outputting a laser pulse sequence;
the optical fiber circulator is provided with a first outlet, a second outlet and a third outlet, the first outlet is connected with the pulse laser source, the second outlet is connected with the optical beam transceiver, the third outlet is connected with the optical amplifier, the optical fiber circulator is used for transmitting the laser pulse sequence from the first outlet to the second outlet and then transmitting the laser pulse sequence to the optical beam transceiver, and the optical fiber circulator is also used for transmitting the received echo laser pulse sequence from the second outlet to the third outlet;
the beam transceiver is connected with the second outlet, and is used for enlarging the size of a transmitting end of the laser pulse sequence, compressing the divergence angle of the laser pulse sequence and irradiating the laser pulse sequence to a target object;
the optical amplifier is respectively connected with the third outlet and the electro-optic phase modulator, and is used for amplifying the power of the echo laser pulse sequence and transmitting the echo laser pulse sequence with the amplified power to the electro-optic phase modulator for time domain phase modulation;
the photoelectric detector is respectively connected with the dispersion medium and the high-speed oscilloscope, and is used for converting the echo laser pulse sequence processed by the time lens system into a radio frequency pulse sequence;
the high-speed oscilloscope is connected with the photoelectric detector, is synchronous with the clock of the radio frequency signal generation module and is used for performing radio frequency pulse sequence on the radio frequency signal generation module
The columns were observed and measured.
4. The lidar device according to claim 2, wherein the operating bandwidth of the radio frequency amplifier is 1-6GHz.
5. The lidar device according to claim 2, wherein the high-level voltage of the square wave signal outputted by the radio frequency signal generation module is 5V, the low-level voltage is 0V, and the duty ratio of the square wave signal is adjustable.
6. The lidar device according to claim 2, wherein the electro-optical phase modulator is a silicon-based phase modulator or a thin film lithium niobate phase modulator.
7. The lidar device according to claim 3, wherein the laser pulse sequence output by the pulse laser source is clock-synchronized with the sine wave signal output by the radio frequency signal generation module 。
8. The lidar device according to claim 3, wherein the center wavelength of the laser pulse train output by the pulse laser source is 1550nm.
9. The lidar device according to claim 3, wherein the optical beam transceiver is an optical phased array chip or an optical lens.
10. The lidar device according to claim 3, wherein the optical amplifier is a erbium-doped fiber amplifier, an erbium-ytterbium co-doped fiber amplifier, or a semiconductor optical amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310129477.9A CN116027300A (en) | 2023-01-31 | 2023-01-31 | Laser radar device based on time lens effect |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310129477.9A CN116027300A (en) | 2023-01-31 | 2023-01-31 | Laser radar device based on time lens effect |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116027300A true CN116027300A (en) | 2023-04-28 |
Family
ID=86076058
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310129477.9A Pending CN116027300A (en) | 2023-01-31 | 2023-01-31 | Laser radar device based on time lens effect |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116027300A (en) |
-
2023
- 2023-01-31 CN CN202310129477.9A patent/CN116027300A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100362366C (en) | Apparatus and method for distance measurement using chaos laser of optical fiber laser device | |
| Palojarvi et al. | Integrated time-of-flight laser radar | |
| Healey | Instrumentation principles for optical time domain reflectometry | |
| US20210116311A1 (en) | Self-calibration detection device and temperature demodulation method oriented to fiber raman temperature sensing system | |
| CN111796297B (en) | Parallel frequency modulation continuous wave laser ranging device based on erbium glass laser | |
| CN115210603B (en) | Laser radar and laser radar control method | |
| CN102623880B (en) | Device for locking laser frequency of seed light based on seed injection type laser | |
| CN107356914B (en) | Calibration system for satellite-borne laser radar detector | |
| CN111175780A (en) | Injection locking frequency modulation continuous wave laser radar speed measuring device and method | |
| CN111025320A (en) | Phase type laser ranging system and ranging method | |
| CN111708004A (en) | Novel laser ranging method and laser radar system | |
| US20230194724A1 (en) | HIGH-DYNAMIC-RANGE HYBRID SOLID-STATE LiDAR SYSTEM BASED ON TRANSPONDER ARRAY MODULE | |
| CN111712908A (en) | Method and apparatus for measuring carrier lifetime | |
| CN115308715A (en) | Method and system for sparse modulation wind-measuring radar | |
| CN113917474A (en) | Laser ranging method, laser ranging system and laser radar system thereof | |
| CN116679310B (en) | FMCW laser measuring device | |
| CN111239754A (en) | Laser radar system based on frequency-adjustable continuous wave and imaging method thereof | |
| US11782078B2 (en) | Method and apparatus for pulsed power measurement | |
| CN116027300A (en) | Laser radar device based on time lens effect | |
| CN109239731B (en) | Device and method for realizing detection and amplification of spatial weak signal based on spontaneous Brillouin scattering | |
| CN116106917A (en) | Parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system | |
| CN116893422A (en) | High-speed interference time light detection and ranging system and method and device for determining distance | |
| CN211905692U (en) | Triangular wave type frequency modulation continuous wave laser radar speed measurement system | |
| EP3835818A1 (en) | Improved lidar with reduced photon noise | |
| CN112986965A (en) | Real-time calibration device for differential cross section of water vapor differential absorption laser radar |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |