CN116106917A - Parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system - Google Patents

Parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system Download PDF

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CN116106917A
CN116106917A CN202211691854.XA CN202211691854A CN116106917A CN 116106917 A CN116106917 A CN 116106917A CN 202211691854 A CN202211691854 A CN 202211691854A CN 116106917 A CN116106917 A CN 116106917A
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laser
optical fiber
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陈孝林
杨峰
阳琴
曾诚
徐诗月
杨镇源
高剑波
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South West Institute of Technical Physics
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/50—Systems of measurement based on relative movement of target
    • G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/115—Q-switching using intracavity electro-optic devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
    • H01S3/1301—Stabilisation of laser output parameters, e.g. frequency or amplitude in optical amplifiers
    • 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

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

The invention belongs to the technical field of laser radars, and discloses a parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system, wherein lasers with different wavelengths emitted by a narrow linewidth single-frequency optical fiber laser array enter an electro-optical modulator after passing through a wavelength division multiplexer, an arbitrary waveform generator and a microwave amplifier modulate laser carriers output after passing through an optical fiber coupler through the electro-optical modulator, modulated light is divided into two beams of light by a beam splitter, one beam of local oscillation light, one beam of detection light enters an optical fiber circulator after being subjected to power amplification by an EDFA amplifier, then the detection light is emitted to an object after being dispersed by a triangular prism, reflected detection light enters the circulator after being incident to the triangular prism, light mixed with the local oscillation light enters the optical fiber coupler, and the light after entering the wavelength division multiplexer obtains an intermediate frequency signal through a photoelectric detector, and then real-time N paths of parallel fast Fourier transform is performed, so that N paths of distance and speed synchronous measurement are realized. The invention improves the data acquisition rate and the image refreshing rate of the laser radar and enlarges the field angle of the laser radar.

Description

Parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system
Technical Field
The invention belongs to the technical field of laser radars, and relates to a parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system.
Background
Laser radar (Lidar) is an active remote sensing technology that uses laser to image, detect and range, because the wavelength of laser is several orders of magnitude shorter than that of microwave, laser radar has higher angular resolution, distance resolution and speed resolution than microwave radar, greater range finding distance, stronger anti-interference capability and smaller volume and mass, significantly expanding the range of use of radar. The laser radar irradiates a target area through laser actively emitted by the emission system, then the detection system detects and processes laser echo signals reflected by the target to obtain characteristic information such as distance, speed and azimuth of the target, so that the target is detected, tracked and identified, and the laser radar is widely applied to automatic driving.
The traditional laser radar is generally unique in measurement target, cannot realize simultaneous ranging and speed measurement, and has a measurement blind area. However, the laser radar application scenario often involves simultaneous measurement of multiple measurement targets, where it is difficult for a conventional laser radar to meet the measurement requirements.
The frequency modulation continuous wave laser radar adopts a modulation signal with the frequency changing along with time to carry out coherent measurement, and detects through measuring the frequency difference between an echo signal and a local oscillation signal, so that the demodulation of the signal can be realized by using a smaller receiving end bandwidth, and higher measurement resolution can be realized relatively easily. In addition, compared with the traditional time-of-flight (TOF) method using pulse laser signals, the frequency modulation continuous wave does not need a high-precision timer and a receiver, does not have a distance blind area, can provide a larger distance measurement range and higher resolution and sensitivity, is not influenced by ambient light and other laser transmitters in theory, has higher signal-to-noise ratio and is safe for human eyes.
In the process of realizing the invention, the inventor finds that the prior continuous wave laser radar technology based on frequency modulation has the following problems: when the laser radar is applied to laser point cloud sampling, although the more the sampling is, the more accurate the measurement result is, the sampling rate cannot meet the existing needs due to the frequency and scanning speed of the carrier signal.
Disclosure of Invention
Object of the invention
The purpose of the invention is that: in order to solve the problems in the prior art of the frequency modulation continuous wave laser radar, the distance measurement and the speed measurement of multiple targets and multiple fields of view are realized, and the parallel linear frequency modulation continuous wave laser radar distance measurement and speed measurement system is provided, so that the distance measurement and the speed measurement of multiple targets in a field of view in a certain area can be simultaneously carried out without a mechanical vibrating mirror after the parallel linear frequency modulation of multiple paths of lasers is realized.
(II) technical scheme
In order to solve the technical problems, the invention provides the parallel linear frequency modulation continuous wave laser radar ranging speed measuring system which is used for carrying out simple linear frequency modulation and prism dispersion light splitting on lasers with different wavelengths, so that fusion detection of a plurality of targets under a certain view field can be realized, the parallel linear frequency modulation can also be used for greatly improving the laser radar data sampling rate, in addition, the view field angle can be enlarged and the angle resolution can be improved simultaneously under the scanning mode of a vibration mirror without depending on the dispersion of a triple prism, the problem that the requirement on a mechanical structure is high because a vibration mirror needs to be scanned for large-view field detection of the traditional laser radar is solved, and meanwhile, the stability of the whole system is improved.
The invention relates to a parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system, which comprises: the system comprises a narrow linewidth single-frequency fiber laser array 1-1 to 1-N, N multiplied by 1 wavelength division multiplexer 2, an arbitrary waveform generator 3, a microwave amplifier 4, an electro-optic modulator 5, a 1 multiplied by 2 fiber beam splitter 6, an EDFA amplifying mode 7, a circulator 8, a triple prism 9, a target 10, a 2 multiplied by 1 fiber coupler 11, a 1 multiplied by N wavelength division demultiplexer 12, a photoelectric detector array 13-1 to 13-N and a data acquisition and signal processing system 14.
The narrow linewidth single frequency fiber laser array 1-N emits laser light as continuous light, the output port of the laser light array is connected with the optical signal input port of the N x 1 wavelength division multiplexer 2, the waveform output port of the arbitrary waveform generator 3 is connected with the input port of the microwave amplifier 4, the output port of the microwave amplifier 4 is connected with the microwave signal input port of the electro-optic modulator 5, the optical signal output port of the electro-optic modulator 5 is connected with the input port of the 1 x 2 fiber beam splitter 6, two paths of output light are formed after the beam splitting of the 1 x 2 fiber beam splitter 6, one path of the output light is used as local oscillation light, the other path of the output light is used as detection light, the local oscillation light is connected with the input port of the 2 x 1 fiber coupler 11, and the detection light is connected with the input port of the EDFA amplifier 7, the output port of the EDFA amplifier 7 is connected with the first port of the circulator 8, the second port of the circulator 8 is connected with the triple prism 9, light with different wavelengths is dispersed and emitted into the space to detect the target object 10, light reflected by the target object 10 is received by the triple prism 9, the received light signal is output through the third port of the circulator 8 and then is connected with the input port of the 2X 1 optical fiber coupler 11, the output port of the 2X 1 optical fiber coupler 11 is connected with the input port of the 1X N demultiplexer 12, the output port of the 1X N demultiplexer 12 is respectively connected with the input ports of the photoelectric detector arrays 13-1 to 13-N, and the output ports of the photoelectric detector arrays 13-1 to 13-N are respectively connected with the data acquisition and signal processing system 14.
Arrays 1-1 to 1-N consisting of N narrow linewidth single frequency fiber lasers with different wavelengths emit laser light with the wavelengths of lambda respectively 1 ～λ N The reference numerals 15-1 to 15-N in FIG. 2 (a). The laser emitted by the laser arrays 1-N is combined into a single-path output through the N multiplied by 1 wavelength division multiplexer 2 and then enters the electro-optical modulator 5, the arbitrary waveform generator 3 and the microwave amplifier 4 modulate the laser carrier through the electro-optical modulator 5 to realize single-sideband linear frequency modulation signals under carrier suppression, and the modulated time-frequency diagrams are shown in the figure 2 (b) with the labels of 16-1-16-N respectively. Warp electricityThe modulated light 16-1 to 16-N after the light modulator 5 is divided into two beams of light by a 1X 2 optical fiber beam splitter 6, wherein one beam is local oscillation light and the other beam is detection light. The detection light enters a first port of the optical fiber circulator 8 after being subjected to power amplification by the EDFA amplifier 7, is dispersed and emitted to the target object 10 by the triangular prism 9 after passing through a second port of the optical fiber circulator 8, and is reflected by the target object 10 to the triangular prism 9 to obtain echo signals, wherein the time-frequency diagram of the echo signals is shown in the accompanying figure 2 (c), and the labels are 17-1 to 17-N respectively. The echo signal enters the third port of the circulator 8 and then is output to be mixed with local oscillation light, and enters the 2 x 1 optical fiber coupler 11. The output light of the 2 x 1 optical fiber coupler 11 is subjected to 1 x N wavelength division multiplexing to obtain light with N wavelength components, the light is received by a photoelectric detector to obtain an intermediate frequency signal, the intermediate frequency signal is subjected to filtering and sampling to perform real-time N paths of parallel fast Fourier transformation, and the synchronous measurement of N paths of distances and speeds can be realized by using the data acquisition and signal processing system 14. The invention is based on laser radar parallel linear frequency modulation and prism dispersion, can greatly improve data acquisition rate and radar resolution, and the dispersion of the prism can also enlarge the laser radar field angle and improve the laser radar angle resolution in a non-galvanometer scanning mode, and in addition, the parallel linear frequency modulation mode can also overcome the crosstalk problem in the traditional multi-view detection process.
Further: the laser emitted by the narrow linewidth single-frequency fiber lasers 1-1 to 1-N is continuous light, N is an integer greater than or equal to 10, and the linewidth is smaller than 10kHz.
Further: the wavelength lambda of the narrow linewidth single frequency fiber laser 1-1 to 1-N 1 ～λ N The wavelength arrays are sequentially arranged from large to small and are marked as 15-1 to 15-N, 1550nm is used as a central wavelength of the wavelength arrays, the wavelength interval change range is not less than 100nm, the wavelength bands are safe to human eyes, and the atmospheric transmission loss is small.
Further: the NX 1 wavelength division multiplexer 2 combines the emitted light with different wavelengths 15-1 to 15-N and outputs the combined light in a single path.
Further: the arbitrary waveform generator 3 sends out two paths of orthogonal linear frequency modulation signals with triangular wave or saw tooth wave, and triangular wave is taken as an example in fig. 2.
Further: the microwave amplifier 4 amplifies the power of the two paths of orthogonal linear frequency modulation signals sent by the arbitrary waveform generator 3, and meets the input requirement of the electro-optical modulator 5 on microwave power.
Further: the orthogonal linear frequency modulation signals sent by the arbitrary waveform generator 3 generate two paths of orthogonal radio frequency signals after passing through the microwave amplifier 4, and the electro-optical modulator 5 is driven to perform parallel inhibition modulation on N laser carriers 15-1-15-N with different wavelengths, and the modulated laser is single-sideband modulated laser 16-1-16-N and consists of a positive first-order sideband or a negative first-order sideband.
Further: the electro-optical modulator 5 is an IQ modulator (double parallel mach-zehnder modulator), and the electro-optical modulator 5 is used for performing parallel linear frequency modulation on N beams of emitted laser emitted by the narrow-linewidth single-frequency fiber laser 1-N array, so as to realize single-sideband modulation under the inhibition of N beams of carrier waves, and the reference number is 16-1-16-N; compared with a Mach-Zehnder modulator, the system can realize larger sideband carrier rejection ratio and improve the signal-to-noise ratio of the system.
Further: the bandwidths of the arbitrary waveform amplifier 3, the microwave amplifier 4 and the electro-optic modulator 5 are all larger than 15GHz, wherein the arbitrary waveform generator 3 generates triangular wave or sawtooth wave linear frequency modulation signals with the bandwidths larger than 15 GHz. The bandwidth of the photodetector arrays 13-1 to 13-N is greater than 1GHz.
Further: the single sideband modulated lasers 16-1 to 16-N of N different wavelengths after modulation by the electro-optic modulator 4 are very weak in power, typically less than 1mW per wavelength component.
Further: the 1×2 fiber beam splitter 6 splits the modulated light into two beams with a power ratio of 90:10. Wherein 90% of the light beams are used as detection light, and 10% of the light beams are used as local oscillation light.
Further: the EDFA amplifier 7 performs optical-optical amplification on the weak linear frequency modulation signals 16-1 to 16-N after passing through the 1X 2 optical fiber beam splitter 6, and the amplified modulated laser power is more than or equal to 100mW in each path.
Further: the triple prism 9 disperses modulated signal lights 16-1 to 16-N with different wavelengths and then emits the modulated signal lights with a certain angle of view to be used as detection light, the detection light is reflected by the target object 10 and then enters the triple prism 9 to obtain echo signals 17-1 to 17-N, and the echo signals enter a receiving port of the circulator after passing through the triple prism. The triangular prism 9 described above may also be replaced by a grating or wedge prism.
Further: the 2X 1 optical fiber coupler 11 couples the local oscillation light 16-1 to 16-N and the echo signal 17-1 to 17-N and outputs the signals in a single path.
Further: the 1 XN demultiplexer 12 outputs light of the 2X 1 optical fiber coupler 11 according to wavelength lambda 1 ～λ N And decomposing into N paths of output.
Further: the parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system does not contain any optical isolator. So that the system can receive the optical signals reflected by the moving object by using the dispersion of the optical fiber circulator 8 and the triangular prism 9 after transmitting laser, the function of receiving and transmitting simultaneously is achieved, and the complexity of the system is reduced.
Further: the data acquisition and signal processing system 14 includes an amplifier, a low pass filter, an analog to digital converter, and a processing module.
Further: the parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system is characterized in that all the other devices except a triangular prism 9 at a transmitting and receiving end are optical fiber devices, and all the devices are connected by adopting optical fibers, so that the carrying and the miniaturization of a system device are facilitated.
The invention uses the array 1-N composed of N narrow linewidth single frequency fiber lasers to carry out simple linear frequency modulation and triple prism dispersion light splitting, and can realize the distance measurement and speed measurement of the parallel multi-view linear frequency modulation continuous wave laser radar without mechanical galvanometer scanning.
(III) beneficial effects
According to the parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system provided by the technical scheme, frequency modulation nonlinearity is not introduced when the random waveform generator 3, the microwave amplifier 4 and the electro-optic modulator 5 are adopted to modulate the laser carrier wave; the laser arrays with different wavelengths are subjected to simple parallel linear frequency modulation and prism dispersion light splitting, so that the data acquisition rate and the image refreshing rate of the laser radar can be greatly improved, the field angle of the laser radar is enlarged, and parallel multi-field linear frequency modulation continuous wave laser ranging and speed measuring can be realized without mechanical components such as galvanometer scanning. The system provides a realization possibility for realizing large-scale parallel and ultra-high data acquisition for the laser radar.
Drawings
FIG. 1 is a schematic diagram of a system for measuring range and speed of a parallel linear frequency modulated continuous wave laser radar of the present invention.
Fig. 2 is a schematic diagram of the parallel lidar ranging and speed measuring system of fig. 1.
Marked in fig. 1: (1) The narrow linewidth single-frequency fiber laser arrays are respectively numbered 1-1 to 1-N; (2) an N x 1 wavelength division multiplexer; (3) an arbitrary waveform generator; (4) a microwave amplifier; (5) an electro-optic modulator; (6) a 1 x 2 fiber optic beam splitter; (7) an EDFA amplifier; (8) a circulator; (9) a triangular prism; (10) a target; (11) a 2 x 1 fiber coupler; (12) a 1 xn demultiplexer; (13) The photoelectric detector arrays are respectively 13-1 to 13-N; (14) a data acquisition and signal processing system.
The label in fig. 2: (a) The wavelength array emitted by the narrow linewidth single-frequency laser has wavelengths of lambda 1-lambda N and marks of 15-1-15-N respectively; (b) The time-frequency diagrams of the N modulated linear frequency modulation continuous wave arrays are respectively numbered 16-1 to 16-N; (c) N linear frequency modulation continuous wave arrays detect light and echo time frequency diagrams, and echo time frequency labels are 17-1 to 17-N respectively.
Detailed Description
To make the objects, contents and advantages of the present invention more apparent, the following detailed description of the present invention will be given with reference to the accompanying drawings and examples.
As shown in fig. 1, in the parallel chirped continuous wave laser radar ranging and speed measuring system of the embodiment, a narrow linewidth single frequency optical fiber laser array 1-1 to 1-N, N ×1 wavelength division multiplexer 2, an arbitrary waveform generator 3, a microwave amplifier 4, an electro-optic modulator 5, a 1×2 optical fiber beam splitter 6, an EDFA amplifier, a circulator 8, a prism 9, a target object 10, a 2×1 optical fiber coupler 11, a 1×n wavelength division demultiplexer 12, a photoelectric detector array 13-1 to 13-N, and a data acquisition and signal processing system 14;
as shown in fig. 2The schematic diagram of the laser radar ranging and speed measuring system takes triangular waves as an example, and the wavelength array emitted by the narrow linewidth single-frequency laser has the wavelength lambda respectively 1 ～λ N The reference numerals are 15-1 to 15-N respectively; the time-frequency diagrams of the N modulated linear frequency modulation continuous wave signal arrays are respectively numbered 16-1 to 16-N; n linear frequency modulation continuous wave arrays detect light and echo time frequency diagrams, and echo signal time frequency labels are 17-1 to 17-N respectively.
The narrow linewidth single frequency optical fiber lasers 1-N are used for generating N wavelengths near 1550nm which are safe to human eyes and respectively are lambda 1 ～λ N The seed light source is suppressed by carrier wave in the signals modulated by the arbitrary waveform generator 3, the microwave amplifier 4 and the electro-optic modulator 5, and the modulated laser is single sideband modulated laser 16-1 to 16-N, and consists of positive first-order sidebands or negative first-order sidebands.
The single sideband modulated light output 16-1 to 16-N after the laser with N wavelengths passes through the electro-optical modulator 5, the wavelength is lambda i The positive first-order sideband light intensity and the negative first-order sideband light intensity after being modulated are respectively as follows:
f i ＝c/n i λ i
S + =-E i exp[j2πf i t+jθ(t)]J 1 (β)
S _ ＝-E i exp[j2πf i t-jθ(t)]J 1 (β)
wherein i is an integer of 1 to N, E i The output wavelength coupled by the wavelength division multiplexer 2 for the narrow linewidth single frequency laser arrays 1-N is lambda i F is the light intensity of i Is the carrier frequency of the laser, n i Is of wavelength lambda i Refractive index of light in optical fiber, carrier frequency J of laser 1 And (beta) is a first-order Bessel function, beta is a modulation depth, and theta (t) is a triangular wave or sawtooth wave linear frequency modulation signal emitted by an arbitrary waveform generator, wherein the beta is related to the bias voltage and half-wave voltage ratio of the electro-optic modulator.
The modulated light is divided into two beams after passing through a 1X 2 optical fiber beam splitter 6, one beam is used as detection light, and the distance and the speed of a moving object are detected; one path is local oscillation light, and is used for carrying out coherent detection on the received echo signals. And calculating the object distance and the movement speed according to the frequency difference between the echo signals 17-1 to 17-N and the local oscillation light 16-1 to 16-N.
The system uses the triple prism 9 to disperse the detection lights 16-1 to 16-N with different wavelengths, irradiates the target object 10 with a certain view field and receives the echo signals 17-1 to 17-N reflected by the moving object, thereby achieving the function of realizing simultaneous receiving and transmitting of multiple view fields without a scanning galvanometer of a mechanical structure. The object 10 is moved to select an object such as a moving car, and it should be noted here that the object can be measured at the same time as long as it is within the scattering angle.
The detected echo signals 17-1 to 17-N are received by the triple prism 9, then pass through the third port of the optical fiber circulator 8, and enter the 2X 1 optical fiber coupler with local oscillation light 16-1 to 16-N for coherent mixing, and the mixed light is processed by the 1 XN demultiplexer 12 according to the wavelength lambda of the light wave 1 ～λ N And the signals are decomposed into N paths of output and then received by a photoelectric detector to obtain intermediate frequency signals.
Fourier transforming the echo signal 17-i received by the light of the ith wavelength component in the rising and falling frequency bands of the triangular wave, respectively, at two beat frequencies f i-1 And f i-2 Bringing it into the distance and velocity formula:
Figure BDA0004021613840000081
Figure BDA0004021613840000082
the method can realize simultaneous ranging and speed measurement of N directions according to the parallel linear frequency modulation continuous wave laser radar mode, and can obtain the horizontal angle information of the ith ranging target object. Wherein T is the modulation period of the triangular wave linear frequency modulation signal, B is the modulation bandwidth of the linear frequency modulation signal, lambda i Center wavelength of ith laser emission of narrow linewidth single frequency fiber laser arrays 1-1 to 1-N, θ i For the triple prism to the wavelength lambda i Dispersion of (3)The angle, i.e. the horizontal angle of the object, is shown in fig. 1.
The intermediate frequency signals obtained by the N-channel parallel linear frequency modulation transmission/reception are subjected to filtering and sampling, then are subjected to real-time N-channel parallel fast Fourier transformation, and the synchronous measurement of the distance and the speed of the N-channel is realized by using a data acquisition and signal processing system.
The detection view angle of the invention is the difference between the dispersion angle of the minimum wavelength and the maximum wavelength after the dispersion of the triple prism.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.

Claims (10)

1. The utility model provides a parallel linear frequency modulation continuous wave laser radar range finding speed measurement system which characterized in that includes: a narrow linewidth single frequency fiber laser array (1-N), an N multiplied by 1 wavelength division multiplexer (2), an arbitrary waveform generator (3), a microwave amplifier (4), an electro-optic modulator (5), a 1 multiplied by 2 fiber beam splitter (6), an EDFA amplifying mode 7, a circulator (8), a triple prism (9), a target object (10), a 2 multiplied by 1 fiber coupler (11), a 1 multiplied by N wavelength division multiplexer (12), a photoelectric detector array (13-1-13-N) and a data acquisition and signal processing system (14);
the narrow linewidth single frequency fiber laser array (1-N) emits laser, the output port of the array is connected with the optical signal input port of the N x 1 wavelength division multiplexer (2), the waveform output port of the arbitrary waveform generator (3) is connected with the input port of the microwave amplifier (4), the output port of the microwave amplifier (4) is connected with the microwave signal input port of the electro-optic modulator (5), the optical signal output port of the electro-optic modulator (5) is connected with the input port of the 1 x 2 fiber beam splitter (6), two paths of output light are formed after the 1 x 2 fiber beam splitter (6) splits, one path of the output light is used as local oscillation light, the other path of the local oscillation light is used as detection light, the local oscillation light is connected with the input port of the 2 x 1 fiber coupler (11), the detection light is connected with the input port of the EDFA amplifier (7), the output port of the EDFA amplifier (7) is connected with the first port of the circulator (8), the second port of the circulator (8) is connected with the prism (9), after light with different wavelengths is dispersed, the object (10) is emitted into space, after the object (10) is separated, the object (1 x 2) is coupled with the input port of the optical fiber (2 x 2) through the prism (11) after the optical fiber (2) is coupled with the input port of the three port of the optical fiber coupler (11), the output ports of the 1 XN wavelength division demultiplexer (12) are respectively connected with the input ports of the photoelectric detector arrays (13-1 to 13-N), and the output ports of the photoelectric detector arrays (13-1 to 13-N) are respectively connected with the data acquisition and signal processing system (14).
2. The parallel chirped continuous wave laser radar ranging and speed measuring system as claimed in claim 1, wherein the narrow linewidth single frequency fiber laser arrays (1-1 to 1-N) emit laser light with wavelength of λ respectively 1 ～λ N The reference number is (15-1-15-N); laser emitted by the laser arrays (1-N) is combined into a single-path by the N multiplied by 1 wavelength division multiplexer (2) and then enters the electro-optical modulator (5), the arbitrary waveform generator (3) and the microwave amplifier (4) modulate laser carriers by the electro-optical modulator (5) to realize single-sideband linear frequency modulation signals under carrier suppression, and modulated light (16-1-16-N) after passing through the electro-optical modulator (5) is divided into two beams by the 1 multiplied by 2 optical fiber beam splitter (6), wherein one beam is local oscillation light and the other beam is detection light; the detection light enters a first port of an optical fiber circulator (8) after being subjected to power amplification by an EDFA (enhanced data transfer amplifier) amplifier (7), is emitted to a target object (10) after being dispersed by a triple prism (9) after being subjected to second port of the optical fiber circulator (8), and is reflected by the target object (10) to the triple prism (9) to obtain echo signals (17-1-17-N), and the echo signals (17-1-17-N) enter a third port of the circulator (8) and are output to be mixed with local oscillation light entering a 2X 1 optical fiber coupler (11); the output light of the 2X 1 optical fiber coupler (11) is subjected to 1 XN wavelength division multiplexing to obtain light with N wavelength components, the light is received by a photoelectric detector to obtain an intermediate frequency signal, the intermediate frequency signal is subjected to filtering and sampling to perform real-time N paths of parallel fast Fourier transformation, and a data acquisition and signal processing system (14) is used for realizing N paths of distanceSynchronous measurement of separation and velocity.
3. The parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system according to claim 2, wherein the laser emitted by the narrow linewidth single frequency fiber laser (1-1 to 1-N) is continuous light, N is an integer greater than or equal to 10, and the linewidth is less than 10kHz.
4. A parallel chirped continuous wave lidar ranging and speed measuring system as claimed in claim 3, characterized in that the arbitrary waveform generator (3) emits two orthogonal chirped signals with triangular or saw-tooth waveform.
5. The parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system according to claim 4, wherein the orthogonal linear frequency modulation signal sent by the arbitrary waveform generator (3) is processed by the microwave amplifier (4) to generate two paths of orthogonal radio frequency signals, the electro-optical modulator (5) is driven to perform parallel inhibition modulation on N laser carriers (15-1-15-N) with different wavelengths, the modulated laser is single-sideband modulated laser (16-1-16-N) and consists of a positive first-order sideband or a negative first-order sideband.
6. The parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system according to claim 5, wherein the electro-optical modulator (5) is an IQ modulator, and the electro-optical modulator (5) performs parallel linear frequency modulation on N beams of emitted laser light emitted by the narrow linewidth single frequency fiber laser (1-N) array, so as to realize single sideband modulation under N beams of carrier suppression.
7. The parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system according to claim 6, wherein the bandwidths of the arbitrary waveform generator (3), the microwave amplifier (4) and the electro-optic modulator (5) are all larger than 15GHz, and the bandwidths of the photoelectric detector arrays (13-1 to 13-N) are larger than 1GHz.
8. The parallel chirped continuous wave lidar ranging and speed measuring system according to claim 7, wherein the 1 x 2 fiber beam splitter (6) splits the modulated light into two beams with a power ratio of 90:10, wherein 90% of the beams are used as probe light and 10% of the beams are used as local oscillation light.
9. The parallel chirped continuous wave laser radar ranging and speed measuring system according to claim 8, wherein the EDFA amplifier (7) performs optical-optical amplification on the weak chirped signals (16-1 to 16-N) after passing through the 1 x 2 optical fiber beam splitter (6), and the amplified modulated laser power is 100mW or more in each path.
10. The parallel chirped continuous wave laser radar ranging and speed measuring system according to claim 9, wherein the 2 x 1 optical fiber coupler (11) couples local oscillation light (16-1 to 16-N) and echo signals (17-1 to 17-N) and outputs the signals in a single path; the 1 XN demultiplexer (12) outputs light of the 2X 1 optical fiber coupler (11) according to wavelength lambda 1 ～λ N And decomposing into N paths of output.
CN202211691854.XA 2022-12-28 2022-12-28 Parallel linear frequency modulation continuous wave laser radar ranging and speed measuring system Pending CN116106917A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116931002A (en) * 2023-09-07 2023-10-24 深圳市速腾聚创科技有限公司 Laser radar and mobile device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116931002A (en) * 2023-09-07 2023-10-24 深圳市速腾聚创科技有限公司 Laser radar and mobile device
CN116931002B (en) * 2023-09-07 2023-12-29 深圳市速腾聚创科技有限公司 Laser radar and mobile device

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