CN105974397A - Polarization laser radar calibration method based on Jones matrix, and polarization laser radar - Google Patents

Abstract

The invention discloses a polarization laser radar calibration method based on a Jones matrix, and a polarization laser radar. The method is used for correcting a depolarization ratio of a polarization laser radar. According to the calibration method, the polarization direction of emission laser is changed by use of a half-wave plate, through angle change of the half-wave plate, a depolarization ratio of the angle change of the half-wave plate and a depolarization ratio change rate value are obtained, a Diff function comparing a depolarization ratio function with a depolarization ratio change rate function is established, the Diff function is fitted by use of a least square method, a Jones matrix constant of a system is obtained, and according to the Jones matrix constant, a corresponding half-wave plate optimization rotation angle is obtained; and when the polarization laser radar carries out long-distance detection, the half-wave plate optimization rotation angle is maintained unchanged, and by use of the Jones matrix constant, the depolarization ratio is corrected by use of the Jones matrix in a receiving optical path. According to the invention, bidirectional determination is realized through the Jones matrix constant and the half-wave plate angle, the scaling precision is high, and relative errors are small.

Description

Polarization lidar scaling method based on Jones matrix and polarization lidar

Technical field

The present invention relates to the scaling method of a kind of polarization lidar and use the polarization lidar system of the method, tool Body relates to a kind of polarization lidar scaling method based on Jones matrix.

Background technology

Jones matrix is used to describe the polarizer change action to polarized light, it is believed that random polarization light can be by it Two components of light vector constitute column matrix and represent, know superposition and synthesis and the polarization of emergent light of polarized light State.

Polarization lidar is a kind of effective tool studying Sand Dust Aerosol and cirrus, to closing weight in atmospheric seeing Want.In polarization lidar, parallel echo-signal reflects the detection information of Mie scattering lidar, and altitude return signal is with flat The ratio of row echo-signal is and moves back Depolarization Ratio, is the Depolarization Ratio of nonspherical particle rear orientation light, the depolarization of polarization lidar Ratio may be considered the indicator of nonspherical particle, can reflect shape and the thing phase of scattering particles, can be used for distinguishing constituent of atomsphere Liquid, admixture, ice cloud and aerosol type, it is seen then that all information of polarization lidar all rely on the standard of Depolarization Ratio Really detection, and the accurately detection of Depolarization Ratio depends on system parameter calibration.

Existing polarization lidar scaling method such as McGill method, embeds half-wave plate and receives system light path, rotate 45 Degree is so that plane of polarization output signal axially matches with receptor polarization.This method eliminates the needs to benchmark Depolarization Ratio, but Need the precise angle that half-wave plate rotates.In addition, use non-polarized light to produce identical signal at multichannel and demarcate polarization Parameters of laser radar system is also conventional method, but the method is confined to preferable non-polarized light and is difficult to obtain.Even if Obtain non-polarized light, need to consider the photon counting intensity of non-polarized light, and single Detection Techniques can only be used, tested Journey is also required to switchable optical path measurements two channel of polarization continuous laser pulse, also needs to obtain polarized beam intuitively simultaneously The optical reflectivity of beam splitter and conversion parameter.

Summary of the invention

The invention aims to solve defect present in prior art, it is provided that one can effectively determine half-wave plate Precise angle, the scaling method that calibration precision is high, relative error is little.

In order to achieve the above object, the invention provides a kind of polarization lidar scaling method based on Jones matrix, The method is for revising the Depolarization Ratio of polarization lidar；Scaling method of the present invention utilizes half-wave plate to change the polarization launching laser Direction, by the Angulation changes to half-wave plate, it is thus achieved that with depolarization ratio and the Depolarization Ratio rate of change value of the change of half-wave plate angle, build The vertical Diff function comparing Depolarization Ratio function and Depolarization Ratio rate of change function, uses method of least square to intend Diff function Close, it is thus achieved that the Jones matrix constant of this system, obtain corresponding half-wave plate according to Jones matrix constant and optimize the anglec of rotation；Polarization When laser radar carries out long-range detection, keep half-wave plate to optimize the anglec of rotation constant, use Jones matrix constant utilization to connect Receive the Jones matrix in light path, Depolarization Ratio is modified.

Wherein, Diff function is: Diff=[Dep ' (θ)-Dep (θ)]²；Wherein Dep ' (θ) is Depolarization Ratio rate of change letter Number, Dep (θ) is Depolarization Ratio function.

Specifically comprise the following steps that

(1) laser launched by the laser instrument of polarization lidar, successively through beam expanding lens, linear polarizer, half-wave plate and reflection After mirror, vertically into air, backscatter signal is received by telescope, after the signal of reception is reflected mirror, collimating mirror, optical filter Enter beam splitter and resolve into the light of orthogonal both direction, respectively enter horizontal channel and vertical channel, two channel reception Echo-signal carries out data acquisition by Photodetection system；

(2) half-wave plate being rotated a low-angle, carry out half-wave plate and fix, repeatedly the conversion half-wave plate anglec of rotation is surveyed Amount, obtains the Depolarization Ratio function with the change of half-wave plate angle, according to Depolarization Ratio function according to the data that Photodetection system gathers Obtain Depolarization Ratio rate of change function, generate Depolarization Ratio functional image, determine according to image and described Diff function is carried out a young waiter in a wineshop or an inn Multiplication matching, it is thus achieved that Jones matrix constant ε_i, it is calculated the anglec of rotation that the half-wave plate of correspondence optimizes；Use polarization laser thunder Reaching when carrying out long-range detection, half-wave plate keeps the anglec of rotation of this optimization constant, uses the Jones matrix in reception system to repair Just from the echo-signal of two passages, thus revise Depolarization Ratio.

Present invention also offers a kind of polarization lidar using above-mentioned scaling method, including:

Emission system, is used for launching polarization laser signal, including laser instrument, beam expanding lens, linear polarizer, half-wave plate, rotation Gyration controls device and reflecting mirror；Laser launched by laser instrument, successively through beam expanding lens, linear polarizer, half-wave plate and reflecting mirror After, vertically into air；Described rotating angle control device is connected with described half-wave plate；

Reception system, forms the echo-signal of orthogonal both direction for receiving atmospheric backscatter signal, including hoping Remote mirror, reflecting mirror, collimating mirror, optical filter and beam splitter；Laser enters the backscatter signal of air and is received by telescope, receives Signal be reflected mirror, collimating mirror, optical filter successively after enter beam splitter and resolve into the echo-signal of orthogonal both direction, point Jin Ru horizontal channel and vertical channel；

Photodetection system, for the echo-signal that reception system is formed is changed into the signal of telecommunication and carries out data process, Including photomultiplier tube, photon counter and computer；Described photomultiplier tube is two, is respectively used to receive described reception system The horizontal channel of system and the echo-signal of vertical channel；Described computer by photon counter respectively with two photomultiplier tubes It is connected.

Wherein, rotating angle control device includes motor and machine carousel；The rotating shaft of machine carousel and motor Output shaft transmission be connected；Half-wave plate is connected with machine carousel.

Rotating angle control device also includes driving gear and driven gear；The output shaft of motor connects driving tooth Wheel, machine carousel periphery is provided with driven gear；Driving gear and driven gear are meshed；The center of machine carousel is provided with recessed Groove, half-wave plate is located in groove.

The present invention has the advantage that compared to existing technology and solves polarization laser thunder by Jones matrix is carried out conversion Reach Jones matrix constant to demarcate, determine the anglec of rotation that half-wave plate optimizes simultaneously；Utilize step motor control machinery simultaneously Rotating disk rotates, and drives half-wave plate to be fixed angular turn, it is ensured that the elaboration of operation, it is to avoid manual regulation is brought Error, solves the difficulty that cannot find half-wave plate precise angle in existing scaling method；By Jones matrix constant and half-wave Sheet angle is two-way to be determined, calibration precision is high, relative error is little.

Accompanying drawing explanation

Fig. 1 is the structural representation of polarization lidar of the present invention；

Fig. 2 is the structural representation of rotating angle control device in Fig. 1.

In figure, 1-laser instrument, 2-beam expanding lens, 3-linear polarizer, 4-half-wave plate, 5-rotating angle control device, 51-walks Enter motor, 52-machine carousel, 53-driving gear, 54-driven gear, 6-reflecting mirror, 7-air, 8-telescope, 9-reflecting mirror, 10-collimating mirror, 11-optical filter, 12-beam splitter, 13-photomultiplier tube, 14-photon counter, 15-computer.

Detailed description of the invention

The present invention is described in detail below in conjunction with the accompanying drawings.

As it is shown in figure 1, polarization lidar of the present invention includes emission system, reception system and Photodetection system.Launch System includes laser instrument 1, beam expanding lens 2, linear polarizer 3, half-wave plate 4, rotating angle control device 5 and reflecting mirror 6.Receive system System includes telescope 8, reflecting mirror 9, collimating mirror 10, optical filter 11 and beam splitter 12.Photodetection system includes photomultiplier tube 13, photon counter 14 and computer 15.

Laser instrument 1 utilizes that one semiconductor pumped, narrow linewidth, continuous print seed laser laser are injected into high energy pulse Obtaining high power, narrow linewidth, the laser of 532nm output in laser oscillator, pulse energy is 10mJ, and pulse repetition rate is 11Hz.The laser of the 532nm sent expands through beam expanding lens 2, and regulation expands border 2, makes the angle of divergence of laser must be less than system The angle of visual field, to ensure the abundant application of laser energy.The linear polaroid of laser 3 after expanding, laser becomes line polarized light, Now, laser polarizes in the same direction.Light path, through half-wave plate 4, drives half-wave plate 4 to rotate by rotating angle control device 5 Fixing low-angle, regulation laser polarization state can mate with polarizing beam splitter mirror (PBS) 12.Laser is through 45 degree of reflecting mirrors 6, by level The laser vertical of transmission enters air 7.Laser produces the scattering of different directions, wherein backscatter signal quilt after entering air 7 (wherein on the focal plane of telescope 8, focus has been placed around aperture diaphragm to telescope 8, to compress the angle of visual field limit of reception system Make the telescopical angle of visual field to receive), the vertical light received is become the optical signal of level, this reflecting mirror 9 by 45 degree of reflecting mirrors 9 Can be used for regulating laser center axial.The flashlight of reflecting mirror 9 reflection is directional light through collimating mirror 10 collimation, in then utilizing The a length of 532nm of cardiac wave, narrow band pass filter 11 compressed background light with a width of 0.35nm.After filtering, the light after collimation is through polarization Beam splitter 12, resolves into the light of orthogonal both direction, respectively enters horizontal channel and vertical channel；Two received are led to The echo-signal in road converts optical signal into the signal of telecommunication by the photomultiplier tube 13 in Photodetection system, utilizes photon counting Device 14 gathers photomultiplier transit signal, in input computer 15, carries out data process.

Wherein, telescope 8 uses triumphant match Green (Casse grain) telescope of a diameter of 200mm.Collimating mirror 10 uses The biconvex lens of 2f=100mm, its effect is that the converged light that telescope 8 receives is become directional light.Optical filter 11 is by backward Scattered light collimation is for directional light, and to utilize centre wavelength be 532nm, the narrow band pass filter compressed background light of bandwidth 0.1nm, and peak value leads to The rate of mistake reaches 70%, filters the light of other frequency ranges in addition to launching laser, to improve the signal to noise ratio of whole system.Polarizing beam splitter mirror 12 light that the different polarization states laser received is divided into orthogonal both direction are so that photomultiplier tube collection.Photodetector Using photomultiplier tube 13 to convert optical signals into the signal of telecommunication, for avoiding introducing unnecessary error, detector uses isotype Number, using this model detector of H10682 in such a system, convert light signals into the signal of telecommunication, this detector is photon meter Number type detectors, pulse number number represent the number of photon.The photon counting that photon counter 14 uses model to be P7882 Card, the sampling resolution of this photon counting card is 12, and sampling rate is single channel 200MHz.The range resolution ratio of single channel signal For 15m, twin-channel range resolution ratio is 30m.Owing to polarization lidar is the dual pathways, therefore range resolution ratio is set to 30m。

As in figure 2 it is shown, rotating angle control device 5 includes motor 51 and machine carousel 52.Motor 51 defeated Shaft connects driving gear 53, and machine carousel 52 periphery is provided with driven gear 54.Driving gear 53 and driven gear 54 are meshed. The center of machine carousel 52 is provided with groove, and half-wave plate 4 is located in groove.Motor 51 is used for controlling machine carousel 52 and rotates Frequency, angle.In the present system, in order to draw the relation between depolarization ratio and half-wave plate 4 rotational angle, half-wave plate 4 rotates To each angle, draw corresponding depolarization ratio.Launching laser repetition rate according to laser instrument 1 is 1000 hertz, gathers 60000 Laser pulse, controls motor and rotates stop 1 minute the most afterwards, add execution motor 51 rotation time and sentence state The disconnected time, controlling machine carousel 52 rotational frequency is 1/62 hertz, and rotational angle is 2 degree.

The purpose that above-mentioned polarization lidar carries out system calibrating is, by polarization lidar Jones matrix constant, The demarcation of atmospheric molecule Depolarization Ratio so that polarization lidar is unified under same standard in the data of follow-up long-range detection, Demarcation to polarization lidar Jones matrix constant to convert based on to this system Jones matrix, to solve.

Optically-based Jones matrix, conversion, solution procedure as follows:

In view of this polarimetric radar laser transmitting system and the system of reception, photomultiplier tube is used to record optical component polarization State can describe by equation below:

${\stackrel{\→}{E}}_R=M_{PMT}\·M_{PBS}\·M_{Opt}\·M_{\mathrm{Re}t}\·{\stackrel{\→}{E}}_T---\left(1\right)$

Wherein, M_PMT、M_PBSAnd M_RetIt is photomultiplier tube 13, beam splitter 12 and chronotron (half-wave plate 4) optics Jones respectively Matrix, M_OptOptics Jones matrix for telescope in polarization lidar 8, reflecting mirror 9, beam expanding lens 2 and other devices.WithIt is respectively and receives light and launch the polarization state of light.Delayer increases phase theta/2 along fast axle, and corresponding slow axis postpones θ/2 Phase place.Therefore, Jones matrixMiddle φ is the Phase delay that delayer causes.If rotation retarder φ, can basis The corresponding anglec of rotation obtains the Jones matrix that delayer is corresponding with good groundsly, as follows:

$M_{\mathrm{Re}t}=\left[\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{cc}1& 0\\ 0& e^{i\mathrm{\φ}}\end{array}\right]\·\left[\begin{array}{cc}cos\mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& cos\mathrm{\θ}\end{array}\right]---\left(2\right)$

Wherein, θ be the fast axle of delayer and beam splitter 12 axially between angle.If optics essence in this radar system Close, it is sufficient to ignore device error, then formula (1) can be written as:

${\left[\begin{array}{c}{\stackrel{\→}{E}}_{\left|\right|}\\ {\stackrel{\→}{E}}_{\⊥}\end{array}\right]}_R={\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]}_{PMT}\·{\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]}_{PBS}{\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]}_{Opt}\·\left[\begin{array}{cc}cos\mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{cc}1& 0\\ 0& e^{i\mathrm{\φ}}\end{array}\right]\·\left[\begin{array}{cc}cos\mathrm{\θ}& sin\mathrm{\θ}\\ -\sin \mathrm{\θ}& cos\mathrm{\θ}\end{array}\right]\·\left[\begin{array}{c}1\\ 0\end{array}\right]---\left(3\right)$

But, for actual optics, need to consider that photomultiplier tube (PMT) gain, beam splitter (PBS) phase place are done Disturb, chronotron phase error and launch the impact that brings of laser polarization degree, formula (3) can be written as follows:

${\left[\begin{array}{c}{\stackrel{\→}{E}}_{\left|\right|}\\ {\stackrel{\→}{E}}_{\⊥}\end{array}\right]}_R={\left[\begin{array}{cc}1& 0\\ 0& G\end{array}\right]}_{PMT}\·{\left[\begin{array}{cc}1& P_{12}\\ P_{21}& P_{22}\end{array}\right]}_{PBS}{\left[\begin{array}{cc}1& O_{12}\\ O_{21}& O_{22}\end{array}\right]}_{Opt}\·\left[\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{cc}1& 0\\ 0& e^{i(\mathrm{\π}+{\mathrm{\ϵ}}_6)}\end{array}\right]\·\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{c}1\\ x\end{array}\right]---\left(4\right)$

Wherein it is desired to consider the phase delay error that half-wave plate causes as delayer, for backscattering echo signal There is also, between two photomultiplier tubes of detection, the variable G caused by Effect on Detecting difference, actually used polarized beam is divided Shu Jing, phase interference is also to need to consider.Therefore, Jones matrix has three above unknown quantity.Wherein, P₁₂、P₂₁、P₂₂Point Not Wei the Jones matrix parameter of beam splitter, ε₆It it is half slide Phase delay parameter.After demarcation, normalization and unknown quantity substitute, Formula (4) is rewritable is:

$\left[\begin{array}{c}{\stackrel{\→}{E}}_{\left|\right|}\\ {\stackrel{\→}{E}}_{\⊥}\end{array}\right]=\left[\begin{array}{cc}1& {\mathrm{\ϵ}}_1\\ {\mathrm{\ϵ}}_2& {\mathrm{\ϵ}}_3\end{array}\right]\·\left[\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{cc}1& {\mathrm{\ϵ}}_4\\ {\mathrm{\ϵ}}_5& e^{i(\mathrm{\π}+{\mathrm{\ϵ}}_6)}\end{array}\right]\·\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\·\left[\begin{array}{c}1\\ {\mathrm{\ϵ}}_7\end{array}\right]---\left(5\right)$

In formula (5),WithIt is respectively backscattering echo signal level direction and the polarization state of vertical direction.Examine Consider the relation of energy and amplitude, ε_iFor Jones matrix constant (i=1-6), the Depolarization Ratio function of definition system is:

Wherein,WithIt is respectively vertical channel and the energy amplitude of horizontal channel.Can be seen that from formula (6), Depolarization Ratio It it is the function about half-wave plate anglec of rotation θ.By the angle that rotatable halfwave plate is different, it is thus achieved that Depolarization Ratio function is a series of Value.If the unknown quantity provided in formula (5), the Depolarization Ratio rate of change function with θ change will be obtained.Definition Diff function ratio is relatively Dep (θ) function and Dep ' (θ) function, as follows:

Diff=[Dep ' (θ)-Dep (θ)]²

Use method of least square that above-mentioned formula is fitted, it is thus achieved that Jones matrix constant ε_i, it is thus achieved that Jones of this system Matrix constant.Actual ghosts signal is as follows with the relation of detectable signal:

${\left[\begin{array}{c}{\stackrel{\→}{E}}_{\left|\right|}\\ {\stackrel{\→}{E}}_{\⊥}\end{array}\right]}_D=\left[\begin{array}{cc}1& {\mathrm{\ϵ}}_1\\ {\mathrm{\ϵ}}_2& {\mathrm{\ϵ}}_3\end{array}\right]\·{\left[\begin{array}{c}{\stackrel{\→}{E}}_{\left|\right|}\\ {\stackrel{\→}{E}}_{\⊥}\end{array}\right]}_R---\left(7\right)$

Thus, detectable signalIt is to be recorded by this polarization lidar system, ε_1-3Drawn by demarcation, Can calculate simply according to formula 7, the Depolarization Ratio for other objects such as aerosol, cloud is also so to draw.

In polarization lidar system, in order to obtain the optimum observation to backscatter signal Depolarization Ratio, carrying out far Before distance observation, when needing to find divergencing laser to mate optimal with polarizing beam splitter mirror 12, the angle that half-wave plate rotates is right with this Polarization lidar systematic parameter accurate calibration.

Before demarcation is carried out, collimated light path, check system photophobism situation and line situation, it is ensured that device is placed appropriate. Select the night sunny, sky is clean, ignore the impact that experiment is caused by atmospheric aerosol and atmospheric molecule, in calibration process, Control machine carousel 52 rotational angle, frequency by motor 51, drive half-wave plate 4 to rotate fixing low-angle, change backward Echo-signal.In each anglec of rotation, after angle rotates, measure two channel signals.Two channel photomultipliers 13 gather 5000 Individual laser pulse signal, repeats above two steps, it is thus achieved that the signal in multiple angles.

Data process is carried out by computer 15.Signal is processed by 5.625 meters to 6 kms as demarcating region, Draw the Depolarization Ratio functional value with the change of half-wave plate 4 anglec of rotation and Depolarization Ratio rate of change functional value, function Diff function is entered Row least square fitting, draws Jones matrix constant ε_i, calculate according to formula (7)WillBring public affairs into In formula (5), calculate half-wave plate 4 anglec of rotation, fix this angle, when carrying out long-range detection, keep the half-wave plate anglec of rotation Constant, use Jones matrix correction in receiving light path to return from the back scattering of polarization lidar two channel photomultiplier Ripple signal, thus revise Depolarization Ratio.

Claims (6)

1. polarization lidar scaling method based on Jones matrix, the method is for revising the Depolarization Ratio of polarization lidar； It is characterized in that, the method utilizes half-wave plate to change the polarization direction launching laser, by the Angulation changes to half-wave plate, it is thus achieved that With depolarization ratio and the Depolarization Ratio rate of change value of the change of half-wave plate angle, set up and compare Depolarization Ratio function and Depolarization Ratio rate of change letter The Diff function of number, uses method of least square to be fitted Diff function, it is thus achieved that the Jones matrix constant of this system, according to fine jade This matrix constant obtains corresponding half-wave plate and optimizes the anglec of rotation；When polarization lidar carries out long-range detection, keep half-wave It is constant that sheet optimizes the anglec of rotation, uses described Jones matrix constant and utilizes the Jones matrix in receiving light path, entering Depolarization Ratio Row is revised.

Scaling method the most according to claim 1, it is characterised in that described Diff function is:Diff =[Dep’()-Dep ()] ² ；WhereinDep’()For Depolarization Ratio rate of change function,Dep( )For Depolarization Ratio function.

Scaling method the most according to claim 2, it is characterised in that comprise the following steps:

(1) laser launched by the laser instrument of polarization lidar, successively after beam expanding lens, linear polarizer, half-wave plate and reflecting mirror, Vertically into air, backscatter signal is received by telescope, and the signal of reception enters after being reflected mirror, collimating mirror, optical filter Beam splitter resolves into the light of orthogonal both direction, respectively enters horizontal channel and vertical channel, the echo of two channel reception Signal carries out data acquisition by Photodetection system；

(2) half-wave plate being rotated a low-angle, carry out half-wave plate and fix, half-wave plate often rotates an angle according to photodetection The data of system acquisition obtain the depolarization ratio of correspondence, and repeatedly the conversion half-wave plate anglec of rotation measures, it is thus achieved that with half-wave plate The Depolarization Ratio function of angle change, obtains Depolarization Ratio rate of change function according to Depolarization Ratio function, generates Depolarization Ratio functional image, root Determine according to image and described Diff function is carried out least square fitting, it is thus achieved that Jones matrix constantε _i , it is calculated correspondence The anglec of rotation that half-wave plate optimizes；When using polarization lidar to carry out long-range detection, half-wave plate keeps the rotation of this optimization Angle is constant, and the Jones matrix correction in use reception system is from the echo-signal of two passages, thus revises Depolarization Ratio.

4. a polarization lidar, it is characterised in that including:

Emission system, is used for launching polarization laser signal, including laser instrument, beam expanding lens, linear polarizer, half-wave plate, the anglec of rotation Degree controls device and reflecting mirror；Laser launched by laser instrument, successively after beam expanding lens, linear polarizer, half-wave plate and reflecting mirror, hangs down Straight enter air；Described rotating angle control device is connected with described half-wave plate；

Reception system, forms the echo-signal of orthogonal both direction for receiving atmospheric backscatter signal, including telescope, Reflecting mirror, collimating mirror, optical filter and beam splitter；Laser enters the backscatter signal of air and is received by telescope, the letter of reception Enter beam splitter after number being reflected mirror, collimating mirror, optical filter successively and resolve into the echo-signal of orthogonal both direction, enter respectively Enter horizontal channel and vertical channel；

Photodetection system, for the echo-signal that reception system is formed is changed into the signal of telecommunication and carries out data process, including Photomultiplier tube, photon counter and computer；Described photomultiplier tube is two, is respectively used to receive described reception system Horizontal channel and the echo-signal of vertical channel；Described computer by photon counter respectively with two photomultiplier tube phases Even.

Polarization lidar the most according to claim 4, it is characterised in that described rotating angle control device includes stepping Motor and machine carousel；The rotating shaft of described machine carousel is connected with the output shaft transmission of described motor；Described half-wave plate with Described machine carousel is connected.

Polarization lidar the most according to claim 5, it is characterised in that described rotating angle control device also includes main Moving gear and driven gear；The output shaft of described motor connects driving gear, and machine carousel periphery is provided with described driven tooth Wheel；Described driving gear and driven gear are meshed；The center of described machine carousel is provided with groove, and groove is located at by half-wave plate In.