CN106707291A - Laser radar system - Google Patents

Abstract

The embodiment of the present invention discloses a laser radar system, including a light source module, a modulation optical module, a transmitting and receiving module, a detection module, and a signal processing module; the dual-wavelength laser beam is converted into a dual-frequency linear frequency modulation by performing linear modulation on the modulated optical module. Continuous wave laser beam; one of the beams is used as a local oscillator beam, and the other beam is used as a signal light interacting with the detection target, and the signal light is scattered by the detection target. The signals are coherently beat to obtain dual-wavelength Doppler shift difference information. The technical solution of this application adopts a dual-wavelength linear frequency modulation laser, which greatly reduces the influence of nonlinear frequency modulation and atmospheric turbulence effects on speed measurement resolution, and realizes simultaneous ranging and speed measurement of detection targets. It has high detection accuracy, anti-electromagnetic interference, and no Advantages of distance blind zone and so on.

Description

A laser radar system

technical field

The invention relates to the field of radar, in particular to a laser radar system.

Background technique

With the development of optical technology, lidar has developed rapidly in the fields of navigation, aerospace, meteorological element measurement, and atmospheric environment monitoring due to its advantages such as good directionality, high temporal and spatial resolution, high precision, and non-contact measurement. Wide range of applications.

Lidar is a radar system that emits laser beams to detect characteristic quantities such as the position and speed of targets, and is mainly composed of laser transmitters, optical receivers, and information processing systems. By transmitting a detection signal (laser beam) to the target, and then processing the received signal reflected from the target (target echo) and the transmitted signal, the relevant information of the target can be obtained, such as target distance, azimuth, height , speed, attitude, and even shape parameters, so as to realize the detection, tracking and identification of aircraft, missiles and other targets.

Dual-frequency coherent lidar is a radar system that detects the difference of dual-wavelength Doppler frequency shifts through coherent beat frequency to invert the speed of the measured target. It needs to extract information from Doppler frequency shift to Doppler frequency shift difference , which suppresses the broadening of the Doppler frequency shift spectral line caused by speckle noise, greatly reduces the impact of speckle noise caused by atmospheric turbulence on the speed measurement resolution, and transforms the signal processing link from the optical path part to the circuit with mature technology part. It can realize short-distance or long-distance accurate speed measurement, and has great application potential in long-distance or portable detection, atmospheric remote sensing and other fields. However, it is difficult for dual-frequency coherent lidar to achieve simultaneous ranging and speed measurement. On the other hand, traditional laser radar has extremely high range resolution after applying linear frequency modulation technology, and has important applications in close-range precision detection, three-dimensional range imaging and autonomous safe soft landing of space capsules, but nonlinear frequency modulation and atmospheric turbulence effects seriously affect the The actual ranging resolution and speed measurement resolution of its system.

Contents of the invention

The purpose of the embodiment of the present invention is to provide a laser radar system, which can simultaneously realize the distance measurement and speed measurement of the measured target, and greatly reduce the influence of nonlinear frequency sweep and atmospheric turbulence effects on the speed measurement resolution, distance resolution and speed resolution. High strength, anti-electromagnetic interference and no distance blind zone.

In order to solve the above technical problems, embodiments of the present invention provide the following technical solutions:

An embodiment of the present invention provides a laser radar system, including:

Light source module, modulating light module, transmitting and receiving module, detection module and signal processing module;

Wherein, the light source module is used to emit dual-wavelength laser beams with preset wavelengths;

The modulation optical module is used to linearly modulate the dual-wavelength laser beam to emit a dual-frequency chirped continuous wave laser beam;

The transmitting and receiving module is used to divide the dual-frequency LFM continuous wave laser beam into a first laser beam and a second laser beam, the first laser beam is incident on the detection target, and the second laser beam is used as a local oscillator light beam; and receiving the backscattered echo signal of the detection target;

The detection module is used to optically beat the local oscillator light beam and the echo signal to obtain Doppler frequency shift information, and at the same time convert the optical signal into an electrical signal;

The signal processing module is used for microwave beating the electrical signal to obtain Doppler frequency shift difference information.

Optionally, the modulating optical module includes:

modulator and signal generator;

Wherein, the modulator is used to perform linear frequency modulation on the dual-wavelength laser beam; the signal generator is connected to the modulator and used to provide the modulator with a modulation signal.

Optionally, the modulating optical module further includes:

A filter, the filter is connected to the modulator, and is used for filtering the background noise in the dual-frequency linear continuous wave laser beam.

Optionally, the modulating optical module further includes:

A laser amplifier, the laser amplifier is connected to the filter, and is used to amplify the energy of the filtered dual-frequency linear continuous wave laser beam.

Optionally, the transmitting and receiving module includes:

a first beam splitter, a second beam splitter, an optical transceiver and a circulator;

Wherein, the first beam splitter is connected to the laser amplifier for dividing the dual-frequency linear continuous wave laser beam into the first laser beam and the second laser beam;

The circulator is respectively connected with the optical transceiver device, the first beam splitter and the second beam splitter, and is used to inject the first laser beam into the optical transceiver device, and transmit the first laser beam to the optical transceiver device. two laser beams are incident on the second beam splitter; and the echo signal is incident on the second beam splitter;

The optical transceiver device is used to inject the first laser beam onto the detection target, receive the scattered echo signal after interacting with the detection target, and inject it into the circulator;

The second beam splitter is used for incident the echo signal and the second laser beam to the detection module.

Optionally, the detection module includes:

A balanced detector, the balanced detector is connected to the second beam splitter, and is used for optically beating the second laser beam and the echo signal to obtain a dual-frequency Doppler frequency shift signal.

Optionally, the signal processing module includes:

Acquisition card and data processing device;

The acquisition card is connected to the balance detector for acquiring signals;

The data processing device is connected with the acquisition card, and is used for microwave beating the electrical signal to obtain a dual-frequency Doppler frequency shift difference signal, so as to invert the distance and speed information of the target.

Optionally, the transmitting and receiving module also includes:

An attenuator is connected to the first beam splitter and the second beam splitter respectively, and is used to attenuate the second laser beam, and the attenuated beam is used as the local oscillator light beam.

Optionally, the data processing device includes:

DSP data processing unit and computer.

An embodiment of the present invention provides a laser radar system, including a light source module, a modulation optical module, a transmitting and receiving module, a detection module, and a signal processing module; the dual-wavelength laser beam is converted into a dual-frequency linear frequency modulation by linear modulation through the modulation optical module Continuous wave laser beam; one of the beams is used as a local oscillator beam, and the other beam is used to interact with the detection target and the echo signal is scattered by the detection target; by coherently beating the local oscillator beam and the echo signal to obtain Obtain dual-wavelength Doppler frequency shift difference information.

The technical solution of this application adopts a dual-wavelength linear frequency-modulated laser, and the system structure and signal processing part are relatively simple compared with the prior art; since the atmospheric turbulence has the same influence on the two frequency-modulated beams, the impact caused by the unevenness of the detection target and the atmospheric turbulence effect is reduced. The influence of speckle noise; because linear continuous wave is used as the coherent beam, the distance resolution is high and the distance has no blind zone; in addition, the distance measurement and speed measurement of the detection target can be realized at the same time. On the basis of optical beat frequency, microwave beat frequency is further carried out to obtain Doppler frequency shift difference information, because any error term acting on the phase of two chirp signals with different frequencies at the same time will not affect microwave beat frequency The phase of the obtained difference frequency signal solves the problem of frequency sweep nonlinearity; since the frequency of the difference frequency signal is much lower than that of the intermediate frequency signal commonly used in daily life, it can resist electromagnetic interference to a certain extent.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a structural block diagram of a laser radar system provided in an embodiment of the present invention in a specific implementation manner;

FIG. 2 is a schematic diagram of a system structure of an exemplary application scenario provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of the working principle of the lidar system in FIG. 2 .

detailed description

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The terms "first", "second", "third" and "fourth" in the specification and claims of this application and the above drawings are used to distinguish different objects, rather than to describe a specific order . Furthermore, the terms "comprising" and "having", and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the listed steps or units, but may include unlisted steps or units.

Please refer to FIG. 1 . FIG. 1 is a structural block diagram of a laser radar system in a specific implementation mode provided by an embodiment of the present invention.

The laser radar system may include a light source module 1 , a modulated light module 2 , a transmitting and receiving module 3 , a detection module 4 and a signal processing module 5 .

The light source module 1 is used to emit dual-wavelength laser beams with preset wavelengths. The center frequencies of the two laser beams are different, and the value of the wavelength can be selected according to the needs of users or experimenters, which is not limited in the present invention. The light source module can be a dual-frequency laser source, or can emit two laser beams with different wavelengths from two laser sources.

In a specific embodiment, the laser source can be a dual-frequency laser, a mode-locked laser, or a seed-implanted semiconductor laser.

The modulation optical module 2 is used for linearly modulating the dual-wavelength laser to emit a dual-frequency linear continuous wave laser beam. Frequency modulation or phase modulation can be used. When the frequency modulation is performed on it, the output is the output dual-frequency linear frequency modulation continuous wave laser beam. Since the frequency modulation of two light beams with different center frequencies in time is simpler for subsequent operations than phase modulation, it is preferable to linearly modulate the frequencies of the two light beams. Since the linear continuous wave has the advantages of no blind spot and high distance resolution for the detection target, the dual-frequency linear continuous wave laser beam is selected as the coherent beam to detect the detection target.

Specifically, the modulating optical module 2 may include a modulator 21 and a signal generator 22 . The modulator 21 is connected to the laser for linearly modulating the dual-wavelength laser. The EOM modulator has good characteristics, so the optional EOM modulator can be used for linearly modulating the dual-wavelength laser. Of course, it can also be any other type Modulator. The signal generator 22 is connected with the modulator 21 to provide the modulation signal for the modulator 21. The signal generator 22 can be a triangular wave signal generator or a sawtooth wave signal generator. Of course, other signal generators, such as square wave, can also be selected. Signal generator.

Optionally, in some implementations of this embodiment, the modulating optical module 2 may also include, for example:

A filter 23, connected to the modulator 21, is used for filtering the background noise in the dual-frequency linear continuous wave laser beam. Since the laser beam emitted by the laser will inevitably be mixed with the stray light of the laser beam with a non-preset wavelength, and the system will inevitably be mixed with all other interferences that have nothing to do with the useful signal during the transmission of the laser beam or during modulation. Therefore, it needs to be filtered to obtain a relatively pure coherent beam, which is conducive to improving the detection accuracy.

The filter 23 can be a high-pass filter, a low-pass filter, a digital filter or a grating, which type can be chosen by those skilled in the art according to actual needs, and the present invention does not make any limitation on this.

In other implementations of this embodiment, it may also include:

A laser amplifier 24, which can be connected to the filter 23, is used to amplify the energy of the filtered dual-frequency linear continuous wave laser beam. Due to the limitation of the laser beam in some occasions (for example, affected by nonlinear effects such as stimulated Brillouin scattering), the power (energy) of the laser beam is small (low), which is not good for subsequent operations, and it is likely to affect the detection Therefore, it is necessary to increase the laser amplifier to amplify the power of the coherent beam. It is beneficial to improve the time resolution, spatial resolution and detection distance of lidar, and it is also conducive to improving the detection accuracy.

It should be noted that if there is no filter 23 in the system, the laser amplifier 24 can be directly connected to the modulator 21 .

The transmitting and receiving module 3 is used to divide the dual-frequency linear continuous wave laser beam into a first laser beam and a second laser beam, the first laser beam is incident on the detection target, and the second laser beam is used as a local oscillator light beam; echo signal.

Specifically, the transmitting and receiving module 3 may include a first beam splitter 31 , a circulator 32 , an optical transceiver device 33 and a second beam splitter 34 .

The first beam splitter 31 can be connected with the laser amplifier 24, and is used for splitting the dual-frequency linear continuous wave laser beam into two beams, that is, the first laser beam and the second laser beam.

The beam splitter separates the two laser beams so that they can be transmitted according to the preset optical path. The beam splitter uses the first laser beam split by the dual-wavelength laser beam as a signal beam to interact with the detection target and generate an echo signal, and the second laser beam is used as a local oscillator beam to interact with the echo signal coherent to obtain Doppler shift information.

The beam splitter can be an optical beam splitter, an optical fiber beam splitter, a polarization beam splitter, etc. Which type to use can be selected by the relevant technical personnel according to actual needs, and the present invention does not make any limitation thereto.

The circulator 32 is respectively connected with the optical transceiver device 33, the first beam splitter 31 and the second beam splitter 34, and is used for incident the first laser beam on the optical transceiver device 33, and incident the second laser beam on the second beam splitter. and the echo signal scattered by the detection target is incident on the second beam splitter 34 .

The circulator 32 is mainly used to convert multiple signals, and of course other devices can also be used as long as they can function as a circulator, which is not limited in the present invention.

The optical transceiver device 33 is used to inject the first laser beam onto the detection target, receive the echo signal emitted after interacting with the detection target, and incident it on the circulator 32 .

The optical transceiver 33 integrates transmitting and receiving, and can adopt kc705 optical transceiver, sfp optical transceiver, graphic image optical transceiver, communication protocol optical transceiver, fmc daughter card optical transceiver or dsp optical transceiver, etc., specifically Which type to use can be selected by those skilled in the art according to actual needs, which is not limited in the present invention.

The second beam splitter 34 is used for incident the echo signal and the second laser beam to the detection module.

It should be noted that if there is no laser amplifier 24 in the system, the first optical splitter 31 can be connected to the filter 23; if there is no filter 23 in the system, the first optical splitter 31 can be directly connected to the modulator 21.

Optionally, in some implementations of this embodiment, for example, it may also include:

The attenuator 35 is connected to the first beam splitter 31 and the second beam splitter 34 respectively, and is used to attenuate the second laser beam, and the attenuated beam is used as the local oscillator light beam. The attenuator 35 is used to attenuate the second laser beam (local oscillator light beam) by simulating the attenuation process of the beam in the atmosphere. Through the attenuation processing of the local oscillator light beam, the attenuation experienced by the local oscillator light beam and the echo signal in the transmission process is similar, which is conducive to the coherence of the two beams of light, and is conducive to obtaining more accurate Doppler frequency shift information, thereby having It is beneficial to improve the detection accuracy.

In a preferred embodiment, the attenuator 35 can be a continuously adjustable attenuator. Of course, other types of attenuators may also be used, and the specific type of attenuator to be used may be selected by the relevant technical personnel according to actual needs, and the present invention does not make any limitation thereto.

It should be noted that, without an attenuator, the second laser beam will be transmitted to the second beam splitter 34 through the first beam splitter 31; but when there is an attenuator, the second laser beam will be transmitted through the first splitter The beam 31 transmits to the attenuator 35 , and transmits to the second beam splitter 34 after being attenuated by the attenuator 35 .

The detection module 4 is used to optically beat the local oscillator light beam and the echo signal to obtain Doppler frequency shift information, and at the same time convert the optical signal into an electrical signal. A balance detector 41 may be included.

The balance detector 41 is connected with the second beam splitter 34, and is used for optically beating the second laser beam and the echo signal to obtain a dual-frequency Doppler frequency shift signal. The second beam splitter 34 injects the echo signal and the second laser beam into the balanced detector 41. After the echo signal and the second laser beam are mixed on the photosensitive surface of the detector, they can be separated by optical beat frequency. Obtain the dual-frequency Doppler frequency shift values of the two beams. Of course, other detectors, such as photodetectors, may also be used.

The signal processing module 5 is used to perform microwave beat frequency on the electric signal to obtain Doppler frequency shift difference information, including analog-to-digital conversion, data acquisition and data processing.

Signal processing module 5 may include:

Acquisition card 51 and data processing device 52.

The acquisition card 51 is connected with the balance detector 41 and is used for acquiring the dual-frequency Doppler frequency shift signal. In a preferred embodiment, the acquisition card 51 can be an A/D acquisition card, of course, other types of acquisition cards can also be used, which type is specifically used, the relevant technical personnel can choose according to actual needs, the present invention and make any restrictions on it.

The data processing device 52 is connected with the acquisition card 51, and is used for performing microwave beat frequency on the electric signal to obtain a dual-frequency Doppler frequency shift difference signal, so as to invert the distance and speed information of the target.

Data processing means may include:

DSP data processing unit 521 and computer 522 .

The DSP data processing unit 521 is configured to perform microwave frequency beating on the electric signal converted from the second laser beam and the echo signal, so as to obtain a Doppler frequency shift difference signal. Since any error term acting on the phases of two chirp signals with different frequencies at the same time will not affect the phase of the difference frequency signal obtained by microwave beat frequency, the problem of frequency sweep nonlinearity and distance-velocity coupling is solved; The frequency of the frequency signal is much lower than that of the intermediate frequency signal commonly used in daily life, so it can resist electromagnetic interference to a certain extent. Between 300MHz, this happens to be the band used by broadcasting stations and wireless communication equipment, which has a wide coverage and intensive use. Therefore, the use of intermediate frequency signals makes traditional coherent lidar susceptible to interference from the electromagnetic environment, and the electromagnetic signals radiated by lidar during normal operation will also cause interference to other electronic devices. In the present invention, for example, when the frequency spacing is 20 GHz, the Doppler frequency shift difference caused by the wind speed of 30 m/s is only 4000 Hz, avoiding this band, so it has the characteristic of anti-electromagnetic interference.

In addition, the use of the DSP data processing unit can also realize real-time processing and display of data, which is conducive to improving user experience.

The calculator 522 is used to invert the distance and velocity information of the target according to the Doppler frequency shift difference signal. For example, atmospheric aerosol is used as a detection object, and the measurement of atmospheric wind speed can be realized by using the lidar system.

It should be noted that, in addition to calculating the distance and speed of the detection target, other information about the detection target can also be processed, such as imaging, temperature measurement and so on.

By adding the calculation module, it can realize inversion and display according to the collected signal, output or obtain the relevant information of the detection target, so that the overall system has more practical significance.

The technical solution of this application adopts a dual-wavelength linear frequency-modulated laser, and the system structure and signal processing part are relatively simple compared with the prior art; since the atmospheric turbulence has the same influence on the two frequency-modulated beams, the impact caused by the unevenness of the detection target and the atmospheric turbulence effect is reduced. The impact of speckle noise; because the linear continuous wave is used as the coherent beam, its distance resolution is high and there is no blind zone in the distance; in addition, the distance measurement and speed measurement of the detection target can be realized at the same time; the microwave shooting is further carried out on the basis of the optical beat frequency frequency to obtain Doppler frequency shift difference information, which solves the problem of frequency sweep nonlinearity and distance-velocity coupling; moreover, it is resistant to electromagnetic interference.

In order to better understand the idea and principle of the technical solution of the present application, the technical solution provided by the embodiment of the present invention is described below in a specific application scenario.

Using the electro-optic modulator whose modulation signal is a triangular wave signal, two continuous wave laser beams with different center frequencies (f ₁ , f ₂ ) are linearly modulated by adjusting the bandwidth B and the modulation frequency k within a certain period of time, as shown in Figure 3 The laser radar system structure, through the optical beat frequency first, extracts the Doppler frequency shift difference information at the microwave beat frequency, and measures the distance and speed of the object. As shown in Figure 3, f _d1 is the Doppler frequency shift value of the beam with the center frequency f ₁ , f _d2 is the Doppler frequency shift value of the beam with the center frequency f ₂ , fm=f ₁ -f ₂ is The center frequency difference of the two beams of light, f _d1 -f _d2 is the Doppler frequency shift difference of the two beams of light, and τ is the time delay between the local oscillator light and the signal light.

As can be seen from Figure 3, the radar system may include a dual-frequency laser source 1, an EOM electro-optic modulator 2, a signal generator 3, a filter 4, a laser amplifier 5, a beam splitter 6, a circulator 7, an optical transceiver 8, a detection Target 9 , continuously adjustable attenuator 10 , beam splitter 11 , balanced detector 12 , A/D acquisition card 13 , DSP data processing system 14 and computer 15 .

The connection relationship of each device is as follows:

The output end of the dual-frequency laser source 1 is connected to the input end of the EOM electro-optic modulator 2, the output end of the EOM electro-optic modulator 2 is connected to the input end of the filter 4, and the control signal input end of the triangular wave signal generator 3 is connected to the EOM electro-optic modulator The control signal output terminal of 2 is connected, and the output terminal of filter 4 is connected with the input terminal of laser amplifier 5, and the output terminal of laser amplifier 5 is connected with the input terminal of beam splitter 6; Divided into two beams, the output of port A is signal light, and the output of port B is local oscillator light; the output A of the beam splitter 6 is connected to the A port of the circulator 7, and the output B of the beam splitter 6 is connected to the continuous The input end of the attenuator 10 is connected; the C port of the circulator 7 is connected with the A port of the beam splitter 11; the B port of the circulator 7 is connected with the optical transceiver 8, and the light beam emitted by the optical transceiver 8 is irradiated on the detection target 9 Above, the backscattered signal from the detection target 9 is collected by the optical transceiver device 8, and then transmitted to the beam splitter 11 through the B terminal and the C terminal of the circulator 7 successively; the output terminal of the continuously adjustable attenuator 10 is connected with the The B port of the beam splitter 11 is connected, the local oscillator light and the signal light are mixed through the beam splitter 11 and then connected to the balance detector 12, the output end of the balance detector 12 is connected to the input end of the A/D acquisition card 13, and the A/D The output end of the acquisition card 13 is connected with the input end of the DSP data processing system 14 , and the output end of the DSP data processing system 14 is connected with the computer 15 .

In the following, the principle of distance measurement and speed measurement of detection targets will be described. In order to simulate the nonlinearity of frequency modulation in actual simulation situations, f _e (t) is introduced as a linear frequency deviation, and f _e (0)=f _e (T/2 )=0, after one single-frequency signal is modulated, the frequency and phase of its upper-sweep frequency band in one cycle are:

f ₁ ⁺ (t) = f ₁ + kt + f _e (t),

In the formula, k=B/(T/2)=2B/T, and δ _R ＝c/2B, the unit of B is MHz, the modulation bandwidth is determined by the distance resolution, T is the modulation period (ms), is the initial phase.

The electric field of the dual-frequency LFM laser in one period can be:

E(t)=E ₁ (t)+E ₂ (t) t∈(0,T),

where E ₁ and E ₂ are amplitudes, with is the phase angle.

The electric field for detecting target scattering signal can be expressed as:

E'(t)=E ₁ '(t)+E' ₂ (t) t∈(0,T),

In the formula, E ₁ `=E ₁ /α, α is the total loss of reflected light. When signal light and local oscillator light are mixed and detected on the photosensitive surface of the balance detector, the detector only responds to signals within the bandwidth range.

When t∈(τ, T/2), the light field illuminance of the detector is:

In the formula, I＝E ₁ ² +E ₁ ' ² , Δf ₁ ⁺ (t)=kτ+f _e (t)−fe ₍ t−τ)=Δf ₁ +Δf _e (t).

If the Doppler effect is considered and τ changes with time, we can get:

Similarly, there can be:

again Available:

In the formula, f _d1 =2νf ₁ /c, f _d2 =2νf ₂ /c, ν is the speed of the detection target, and c is the speed of light.

When t∈(T/2, T/2+τ), similarly, there can be:

When t∈(T/2+τ, T), similarly, there can be:

I ₁ (t) and I ₂ (t) can be collected by the A/D acquisition card after being detected by the detector. After the collected signal is processed by the DSP data signal, it is mixed again, and the above formula is expanded, which includes many The items of the Puler frequency shift information are:

In the formula,

In summary, the distance and speed of the detection target can be calculated as follows:

In the formula, when ν is a positive value, it means that the detection target is approaching the lidar; if it is negative, it means that the target is moving away from the lidar.

In the embodiment of the present invention, the frequency of two continuous waves with different center frequencies is linearly modulated in time to obtain a dual-frequency chirp laser, and the frequency modulation bandwidth B and the difference f _m of the dual-frequency center frequency are much smaller than the dual-frequency center frequency f ₁ and f ₂ , so the influence of atmospheric turbulence on the two frequency-modulated lasers is almost the same, and they are insensitive to atmospheric turbulence. As for the nonlinear frequency deviation f _e (t) caused by the nonlinearity of the frequency sweep, in the signal processing process, the microwave beat frequency makes the nonlinear frequency deviation items cancel each other out, and the obtained difference frequency signal does not contain the nonlinear frequency deviation items. To sum up, the lidar system not only realizes the simultaneous distance measurement and speed measurement of the detection target, but also greatly reduces the influence of nonlinear frequency modulation and atmospheric turbulence effects on the speed measurement resolution. It has high detection accuracy, anti-electromagnetic interference, and no distance blind zone.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related information, please refer to the description of the method part.

Professionals can further realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the possible For interchangeability, in the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be directly implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any Any other known storage medium.

The laser radar system provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (9)

1. a kind of laser radar system, it is characterised in that including：

Light source module, modulation optical module, transmitting and receiving module, detecting module and signal processing module；

Wherein, the light source module is used for the dual-wavelength laser light beam of outgoing preset wavelength；

The modulation optical module is used to carry out linear modulation to the dual-wavelength laser light beam, continuous with outgoing double frequency linear frequency modulation Ripple laser beam；

The transmitting and receiving module be used for by the double frequency linear frequency modulation continuous wave laser beam be divided into first laser light beam and Second laser light beam, the first laser light beam is incident to detection target, and the second laser light beam is used as local oscillator light light beam；And Receive the detection target backscattering echo signal；

The detecting module is used to carry out optical beat to the local oscillator light light beam and the echo-signal, to obtain Doppler frequently Shifting information, while converting optical signals into electric signal；

The signal processing module is used to carry out microwave beat frequency to the electric signal, to obtain Doppler frequency shift difference information.

2. system according to claim 1, it is characterised in that the modulation optical module includes：

Modulator and signal generator；

Wherein, the modulator is used to carry out linear frequency modulation to the dual-wavelength laser light beam；The signal generator with it is described Modulator is connected, for providing modulated signal for the modulator.

3. system according to claim 2, it is characterised in that the modulation optical module also includes：

Wave filter, the wave filter is connected with the modulator, for the back of the body in the double frequency LINEAR CONTINUOUS ripple laser beam Scape noise is filtered.

4. system according to claim 3, it is characterised in that the modulation optical module also includes：

Laser amplifier, the laser amplifier is connected with the wave filter, for the double frequency LINEAR CONTINUOUS ripple after filtering to be swashed The energy of light light beam is amplified.

5. system according to claim 4, it is characterised in that the transmitting and receiving module includes：

First beam splitter, the second beam splitter, optical transmitting and receiving device and circulator；

Wherein, first beam splitter is connected with the laser amplifier, for by the double frequency LINEAR CONTINUOUS ripple laser beam It is divided into the first laser light beam and the second laser light beam；

The circulator is connected with the optical transmitting and receiving device, first beam splitter and second beam splitter respectively, uses In the first laser light beam is incident into the optical transmitting and receiving device, the second laser light beam is incident to described second point Beam device；And the echo-signal is incided into second beam splitter；

The optical transmitting and receiving device is used to for the first laser light beam to be incident to the detection target, and receives and the spy Survey objectives interation after scatter echo-signal and be incident to the circulator；

Second beam splitter is used to for the echo-signal to be incident to the detecting module with the second laser light beam.

6. system according to claim 5, it is characterised in that the detecting module includes：

Balanced detector, the balanced detector is connected with second beam splitter, for the second laser light beam and institute Stating echo-signal carries out optical beat, to obtain dual frequency doppler frequency shift signal.

7. system according to claim 6, it is characterised in that the signal processing module includes：

Capture card and data processing equipment；

The capture card is connected with the balanced detector, for gathering signal；

The data processing equipment is connected with the capture card, for carrying out microwave beat frequency to the electric signal, to obtain double frequency Doppler frequency shift difference signal, with the distance and velocity information of this inverting target.

8. the system according to claim 5-7 any one, it is characterised in that the transmitting and receiving module also includes：

Attenuator, is connected with first beam splitter with second beam splitter respectively, for entering to the second laser light beam Row decay, through the light beam after decay as the local oscillator light light beam.

9. system according to claim 8, it is characterised in that the data processing equipment includes：

DSP data processing units and computer.