CN104133202A - 2mum coherent wind lidar polarization state matching and correcting system - Google Patents
2mum coherent wind lidar polarization state matching and correcting system Download PDFInfo
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- CN104133202A CN104133202A CN201410228849.4A CN201410228849A CN104133202A CN 104133202 A CN104133202 A CN 104133202A CN 201410228849 A CN201410228849 A CN 201410228849A CN 104133202 A CN104133202 A CN 104133202A
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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
- 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
- G01S7/497—Means for monitoring or calibrating
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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
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/95—Lidar systems specially adapted for specific applications for meteorological use
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- 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
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Abstract
The invention relates to a 2mum coherent wind lidar polarization state matching and correcting system, which comprises a 2mum laser, a first single-mode polarization-maintaining fiber, an acoustooptic frequency shifter, a second single-mode polarization-maintaining fiber, a tail fiber-type Grin lens, a lambda/2 wave plate, a lens, a polarization beam splitter prism, a lambda/4 wave plate, an off-axis optical antenna, a stepper motor drive device, a polarizer, a first tail fiber-type coupling lends, a double-channel polarization state analyzer system, a second fiber beam splitter, a photodiode, a coaxial cable, and an oscilloscope. The system can monitor each polarization state situation of reference local oscillation laser signals and laser echo signals in the coherent wind lidar system in real time. when polarization state of two light beams are not matched, the double-channel polarization state analyzer system can automatically correct the polarization state of the laser until matching is realized, thereby greatly improving the heterodyne efficiency of the coherent wind lidar system and improvising detection sensitivity of the system.
Description
Technical field
The present invention relates to a kind of 2 mu m coherent anemometry laser radar polarization state coupling and correction systems, this system can Real-Time Monitoring 2 mu m coherent anemometry laser radar systems in the polarization state match condition of local oscillator reference laser signal and echo laser signal, be applicable in the coherent wind laser radar system based on spaceborne, airborne and foundation platform.
Background technology
Coherent wind laser radar, with features such as the detection sensitivity of its nearly quantum noise limit, high s/n ratio, high precision clear sky detectivities, is widely used in weak laser acquisition of signal field.Anemometry laser radar has been proved to be one of effective means of studying at present Small and Medium Sized meteorologic phenomena, all significant to all many-sides such as weather forecast, military and national defense, aviation safety early warning.
Coherent wind laser radar, taking aerocolloidal Mie scattering in atmosphere as basis, is operated in medium-wave infrared or LONG WAVE INFRARED optical band, and micropulse heterodyne detection can directly extract Doppler frequency information from weather echo.Wherein 2 mu m coherent Doppler anemometry laser windfinding radars, adopt all solid state 2 μ m laser instruments as emissive source, and its wave band is in atmospheric window, eye-safe, and strong security, is the focus of studying in the world.
Coherent wind laser radar is the initiatively measurement means of high precision based on heterodyne detection technology, and heterodyne detection of laser is generally acknowledged minimum wavelength Detection Techniques.Pertinent literature and experimental data show, direct detection of laser mode minimum detectable power is generally in 10-9W magnitude, and heterodyne detection can be realized nearly minimum wavelength and surveys (10
-11more than W magnitude).Visible, the high several orders of magnitude of heterodyne detection remolding sensitivity direct detection, but the difficulty of heterodyne detection technology is also much higher than direct detection.
As everyone knows, there is its peculiar added losses factor in heterodyne detection of laser system, is referred to as heterodyne efficiency.Therefore, heterodyne efficiency is one of important parameter index of evaluating Heterodyne Detection System performance.Heterodyne efficiency is affected by following factor mainly: waveform shape, distribution of amplitudes, phasic difference, local oscillator light light intensity and the polarization state of transmitting light beam and local beam.Wherein, front 4 influence factors only need to carry out can easily meeting after the rectification of single, and polarization state coupling is the key factor that affects heterodyne efficiency in heterodyne detection of laser system, and directly determine heterodyne detection and the direct detection superiority in tiny signal field of detecting.The system or equipment that current existing coherent wind laser radar system does not all carry out Real-Time Monitoring, coupling and corrects polarization state, therefore, is badly in need of design a kind of for carrying out polarization state monitoring and the method for correcting.
Summary of the invention
Technology of the present invention is dealt with problems and is: overcome prior art deficiency, a kind of 2 mu m coherent anemometry laser radar polarization state coupling and correction systems are provided, this system can Real-Time Monitoring coherent wind laser radar system in reference local oscillator laser signal and laser echo signal polarization state situation separately, in the time of the polarization state mismatch of this two-beam, the polarization state of binary channels polarization state monitoring analysis system meeting automatic straightening laser is until coupling, thereby significantly improve the heterodyne efficiency of system, improve system detection sensitivity.
Technical solution of the present invention is: a kind of 2 mu m coherent anemometry laser radar polarization state couplings are provided and have corrected structure, comprise: 2 μ m laser instruments, the first single-mode polarization maintaining fiber, acousto-optic frequency shifters, the first fiber optic splitter, the second single-mode polarization maintaining fiber, binary channels Polarization instrument, tail-fiber type Green GRIN Lens, the first concentric cable, λ/2 wave plate, lens, polarization beam splitter prism, λ/4 wave plate, from axle optical antenna, drive unit, polaroid, coupled lens, the second fiber optic splitter, optical-fiber bundling device, photodiode, the second concentric cable, oscillograph, the 3rd single-mode polarization maintaining fiber and the 4th single-mode polarization maintaining fiber,
Acousto-optic frequency shifters comprises input port, 1 order diffraction output port, 0 order diffraction output port, frequency modulation (PFM) port and radio-frequency power modulation port, and binary channels Polarization instrument system comprises first signal input port and secondary signal input port;
2 μ m laser instrument Emission Lasers signals, are input to acousto-optic frequency shifters after the input port by the first single-mode polarization maintaining fiber and acousto-optic frequency shifters; To 5.2V, to 1.0V, make acousto-optic frequency shifters reach diffraction efficiency maximal value radio-frequency power modulation port voltage modulated the voltage-regulation of modulation port, from 0 order diffraction port and 1 order diffraction port output two-way laser signal; The laser beam of 1 order diffraction port output, through the transmission of the second single-mode polarization maintaining fiber, after the tail-fiber type Green GRIN Lens that is 0.23 collimation, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate and lens, becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping becomes right-hand circular polarization signal from linear polarization signal after polarization beam splitter prism and λ/4 wave plate, right-hand circular polarization signal enters into from axle optical antenna, from axle optical antenna to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through large gasoloid, produces back scattering laser signal, and back scattering laser signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal is received from axle optical antenna and after the wave plate of λ/4, polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction rotated 90 degree, is polarized beam splitter prism reflection;
Laser beam after polarization beam splitter prism reflection is after the polaroid in over-driving device, be coupled through coupled lens, then be divided into two-way laser signal through the second fiber optic splitter, wherein a road laser signal enters binary channels Polarization instrument from first signal input port after the 3rd single-mode polarization maintaining fiber;
Be divided into two-way by 2 μ m laser of 0 order diffraction output port output of acousto-optic frequency shifters after via the first fiber optic splitter, wherein a road laser enters binary channels polarization analysis instrument through the secondary signal input port of binary channels polarization analysis instrument;
Binary channels polarization analysis instrument calculates respectively from the poincare sphere angle of cut of the laser signal of first signal input port and secondary signal input port input, and change this poincare sphere angle of cut into voltage signal and input to the external drive signal of drive unit as drive unit via the first concentric cable, polaroid is the rotation taking 0.02 degree as stepping amount under the drive of drive unit, until the poincare sphere angle of cut that binary channels polarization analysis instrument calculates is equalled zero;
Restraint laser after the 4th single-mode polarization maintaining fiber via second of the second fiber optic splitter beam splitting, as the first input signal of optical-fiber bundling device, restraint second input signal of laser as optical-fiber bundling device via second of the first fiber optic splitter beam splitting, the two-way input signal of optical-fiber bundling device closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device, this laser beam directly and on the photosurface of photodiode interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph via concentric cable and shows; The equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
The concrete computation process of the described poincare sphere angle of cut is: the poincare sphere radius that makes binary channels polarization analysis instrument inside is s
0, the coordinate of the point from the laser signal of first signal input port and secondary signal input port input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ.
Described beam shaping process is specially: regulate the polarization direction of λ/2 wave plate and monitor transmitted through the optical signal power after polarization beam splitter prism, until this performance number maximum; Lens are positioned over simultaneously and realize the shaping process to laser beam from tail-fiber type Green GRIN Lens light output end 60mm place.
The input signal of described binary channels polarization analysis instrument secondary signal input port and the second input signal of optical-fiber bundling device produce in the following way:
Laser signal produces laser signal along separate routes through being arranged on 2 μ m laser instruments the 3rd fiber optic splitter afterwards, this shunt laser signal produces laser signal along separate routes after the first fiber optic splitter, wherein a road shunting sign is as the input signal of binary channels polarization analysis instrument secondary signal input port, and another road shunting sign is as the second input signal of optical-fiber bundling device.
The input signal of described binary channels polarization analysis instrument secondary signal input port and the second input signal of optical-fiber bundling device produce in the following way:
Laser signal produces laser signal along separate routes through being arranged on 2 μ m laser instruments the 3rd fiber optic splitter afterwards, one tunnel shunt laser signal as the second input signal of optical-fiber bundling device, is input to acousto-optic frequency shifters after the input port of another road shunting sign by the first single-mode polarization maintaining fiber and acousto-optic frequency shifters after the 5th single-mode polarization maintaining fiber; The voltage of regulating frequency modulation port is to 5.2V and radio-frequency power modulation port voltage to 1.0V, reach after diffraction efficiency maximal value, from 0 order diffraction port output, after the 6th single-mode polarization maintaining fiber as the input signal of binary channels polarization analysis instrument secondary signal input port.
The input signal of described binary channels polarization analysis instrument secondary signal input port and the second input signal of optical-fiber bundling device produce in the following way:
Laser signal produces laser signal along separate routes through the 3rd fiber optic splitter being arranged on after 2 μ m laser instruments, a road along separate routes laser signal after the 8th single-mode polarization maintaining fiber as the input signal of binary channels polarization analysis instrument secondary signal input port;
After the input port of another road shunting sign by the first single-mode polarization maintaining fiber and acousto-optic frequency shifters, be input to acousto-optic frequency shifters; The voltage of regulating frequency modulation port, to 5.2V and radio-frequency power modulation port voltage to 1.0V, reaches after diffraction efficiency maximal value, from 0 order diffraction port output, after the 7th single-mode polarization maintaining fiber as the second input signal of optical-fiber bundling device.
The present invention's beneficial effect is compared with prior art:
(1) the present invention adopts extinction ratio to be better than 1000:1, response spectrum scope is the analyzer of 650～2100nm linear polarizer as 2 μ m echo laser signal light, and which has easy to adjust, and spectral response range is wide, 2 μ m extinction coefficient highs;
(2) the present invention adopts the polarization state form of binary channels input polarization analyser real-time analysis reference local oscillator laser signal and laser echo signal, for correction system provides input parameter, this method has the polarization state situation of change that can distinguish real-time analysis reference local oscillator laser and laser echo signal, can backup system and the coupling of polarization state, from qualitative and quantitative two aspects for system polarization state coupling provides input parameter with rectification;
(3) the present invention adopts the reference local oscillator laser of Polarization instrument output and the poincare sphere polarization state parameter of echo laser signal is analyzed, and analysis result is converted into the driving current signal of stepper motor, make stepper motor drive the sense of rotation of polaroid, finally realize the rectification to polarization state direction, improve system heterodyne efficiency, the feature of which is: system adopts full fibre-optical closed-loop loop, system is simply compact, modularization integration mode, both ensure quantum limit detection sensitivity, enriched systemic-function simultaneously.
Brief description of the drawings
Fig. 1 is the system schematic of embodiment one;
Fig. 2 is the system schematic of embodiment two;
Fig. 3 is the system schematic of embodiment three;
Fig. 4 is the system schematic of embodiment four.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is further described in detail.
A kind of 2 mu m coherent anemometry laser radar polarization state couplings and rectification structure, be characterised in that and comprise: 2 μ m laser instruments 1, the first single-mode polarization maintaining fiber 2, acousto-optic frequency shifters 3, the first fiber optic splitter 4, the second single-mode polarization maintaining fiber 5, binary channels Polarization instrument 6, tail-fiber type Green GRIN Lens 7, the first concentric cable 8, λ/2 wave plate 9, lens 10, polarization beam splitter prism 11, λ/4 wave plate 12, from axle optical antenna 13, drive unit 14, polaroid 15, coupled lens 16, the second fiber optic splitter 17, optical-fiber bundling device 18, photodiode 19, the second concentric cable 20, oscillograph 21, the 3rd single-mode polarization maintaining fiber 22 and the 4th single-mode polarization maintaining fiber 23,
Acousto-optic frequency shifters 3 comprises input port 3-1,1 order diffraction output port 3-2,0 order diffraction output port 3-3, frequency modulation (PFM) port 3-4 and radio-frequency power modulation port 3-5, and binary channels Polarization instrument system 6 comprises first signal input port 6-1 and secondary signal input port 6-2;
Embodiment one: as shown in Figure 1,2 μ m laser instrument 1 Emission Lasers signals, are input to acousto-optic frequency shifters 3 after the input port 3-1 by the first single-mode polarization maintaining fiber 2 and acousto-optic frequency shifters 3 to the present embodiment; The voltage of regulating frequency modulation port 3-4 is to 5.2V, and radio-frequency power modulation port 3-5 voltage, to 1.0V, makes acousto-optic frequency shifters 3 reach diffraction efficiency maximal value, from 0 order diffraction port 3-3 and 1 order diffraction port 3-2 output two-way laser signal; The laser beam of 1 order diffraction port 3-2 output, through the transmission of the second single-mode polarization maintaining fiber 5, after the tail-fiber type Green GRIN Lens that is 0.23 7 collimations, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate 9 and lens 10, becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping wired polarization signal after polarization beam splitter prism 11 and λ/4 wave plate 12 becomes right-hand circular polarization signal, right-hand circular polarization signal enters into from axle optical antenna 13, from axle optical antenna 13 to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through atmospheric aerosol, produces back scattering laser signal, and this signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal returns along original optical path after receiving from axle optical antenna 13, and after λ/4 wave plate 12, polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction rotated 90 degree, be polarized beam splitter prism 11 and reflect;
Laser beam after polarization beam splitter prism 11 reflections is after the polaroid 15 in over-driving device 14, be coupled through coupled lens 16, then be divided into two-way laser signal through the second fiber optic splitter 17, wherein a road laser signal enters binary channels Polarization instrument 6 from first signal input port 6-1 after the 3rd single-mode polarization maintaining fiber 22;
Be divided into two-way by 2 μ m laser of 0 order diffraction output port 3-3 output of acousto-optic frequency shifters 3 after via the first fiber optic splitter 4, wherein a road laser enters binary channels polarization analysis instrument 6 through the secondary signal input port 6-2 of binary channels polarization analysis instrument 6;
Binary channels polarization analysis instrument 6 calculates respectively from the poincare sphere angle of cut of the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input, and change poincare sphere position angle difference into voltage signal and input to the external drive signal of drive unit 14 as drive unit 14 via the first concentric cable 8, polaroid 15 is the rotation taking 0.02 degree as stepping amount under the drive of stepper motor 14, until the poincare sphere angle of cut that binary channels polarization analysis instrument 6 calculates is equalled zero; The concrete computation process of the described poincare sphere angle of cut is: making the poincare sphere radius of binary channels polarization analysis instrument 6 inside is s
0, the coordinate of the point from the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ;
Restraint laser after the 4th single-mode polarization maintaining fiber 23 via second of the second fiber optic splitter 17 beam splitting, as the first input signal of optical-fiber bundling device 18, restraint second input signal of laser as optical-fiber bundling device 18 via second of the first fiber optic splitter 4 beam splitting, the two-way input signal of optical-fiber bundling device 18 closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device 18, this laser beam directly and on the photosurface of photodiode 19 interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph 21 via concentric cable 20 and shows; The equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
Embodiment two: as shown in Figure 2,2 μ m laser instrument 1 Emission Lasers signals, produce laser signal along separate routes by the 3rd fiber optic splitter 24 to the present embodiment, and wherein a road shunting sign is input to acousto-optic frequency shifters 3 after the input port 3-1 of acousto-optic frequency shifters 3; The voltage of regulating frequency modulation port 3-4 is to 5.2V, and radio-frequency power modulation port 3-5 voltage, to 1.0V, makes acousto-optic frequency shifters 3 reach diffraction efficiency maximal value, exports a road laser signal from 1 order diffraction port 3-2; This laser beam, through the transmission of the second single-mode polarization maintaining fiber 5, after the tail-fiber type Green GRIN Lens that is 0.23 7 collimations, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate 9 and lens 10, becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping becomes right-hand circular polarization signal from linear polarization signal after polarization beam splitter prism 11 and λ/4 wave plate 12, right-hand circular polarization signal enters into from axle optical antenna 13, from axle optical antenna 13 to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through atmospheric aerosol, produces back scattering laser signal, and this signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal returns along original optical path after receiving from axle optical antenna 13, and after λ/4 wave plate 12, polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction rotated 90 degree, be polarized beam splitter prism 11 and reflect;
Laser beam after polarization beam splitter prism 11 reflections is after the drive unit 14 with polaroid 15, be coupled through coupled lens 16, then be divided into two-way laser signal through the second fiber optic splitter 17, wherein a road laser signal enters binary channels Polarization instrument 6 from first signal input port 6-1 after the 3rd single-mode polarization maintaining fiber 22;
Another road laser signal that the 3rd fiber optic splitter 24 produces is divided into two-way after via the first fiber optic splitter 4, and wherein a road laser enters binary channels polarization analysis instrument 6 through the secondary signal input port 6-2 of binary channels polarization analysis instrument 6;
Binary channels polarization analysis instrument 6 calculates respectively from the poincare sphere angle of cut of the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input, and change poincare sphere position angle difference into voltage signal and input to the external drive signal of drive unit 14 as drive unit 14 via the first concentric cable 8, polaroid 15 is the rotation taking 0.02 degree as stepping amount under the drive of stepper motor 14, until the poincare sphere angle of cut that binary channels polarization analysis instrument 6 calculates is equalled zero; The concrete computation process of the described poincare sphere angle of cut is: making the poincare sphere radius of binary channels polarization analysis instrument 6 inside is s
0, the coordinate of the point from the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ;
Restraint laser after the 4th single-mode polarization maintaining fiber 23 via second of the second fiber optic splitter 17 beam splitting, as the first input signal of optical-fiber bundling device 18, restraint second input signal of laser as optical-fiber bundling device 18 via second of the first fiber optic splitter 4 beam splitting, the two-way input signal of optical-fiber bundling device 18 closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device 18, this laser beam directly and on the photosurface of photodiode 19 interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph 21 via concentric cable 20 and shows; The equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
Embodiment three: as shown in Figure 3,2 μ m laser instrument 1 Emission Lasers signals, produce laser signal along separate routes by the 3rd fiber optic splitter 24 to present embodiment, and wherein a road shunting sign is input to acousto-optic frequency shifters 3 after the input port 3-1 of acousto-optic frequency shifters 3; The voltage of regulating frequency modulation port 3-4 is to 5.2V, and radio-frequency power modulation port 3-5 voltage, to 1.0V, makes acousto-optic frequency shifters 3 reach diffraction efficiency maximal value, from 0 order diffraction port 3-3 and 1 order diffraction port 3-2 output two-way laser signal; The laser beam of 1 order diffraction port 3-2 output, through the transmission of the second single-mode polarization maintaining fiber 5, after the tail-fiber type Green GRIN Lens that is 0.23 7 collimations, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate 9 and lens 10, becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping becomes right-hand circular polarization signal from linear polarization signal after polarization beam splitter prism 11 and λ/4 wave plate 12, right-hand circular polarization signal enters into from axle optical antenna 13, from axle optical antenna 13 to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through atmospheric aerosol, produces back scattering laser signal, and this signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal returns along original optical path after receiving from axle optical antenna 13, and after λ/4 wave plate 12, polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction rotated 90 degree, be polarized beam splitter prism 11 and reflect;
Laser beam after polarization beam splitter prism 11 reflections is after the drive unit 14 with polaroid 15, be coupled through coupled lens 16, then be divided into two-way laser signal through the second fiber optic splitter 17, wherein a road laser signal enters binary channels Polarization instrument 6 from first signal input port 6-1 after the 3rd single-mode polarization maintaining fiber 22, and an other road is as the laser echo signal in coherent detection process;
Enter binary channels polarization analysis instrument 6 through the secondary signal input port 6-2 of binary channels polarization analysis instrument 6 by 2 μ m laser of 0 order diffraction output port 3-3 output of acousto-optic frequency shifters 3 after via the 6th single-mode polarization maintaining fiber 26;
Binary channels polarization analysis instrument 6 calculates respectively from the poincare sphere angle of cut of the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input, and change poincare sphere position angle difference into voltage signal and input to the external drive signal of drive unit 14 as drive unit 14 via the first concentric cable 8, polaroid 15 is the rotation taking 0.02 degree as stepping amount under the drive of stepper motor 14, until the poincare sphere angle of cut that binary channels polarization analysis instrument 6 calculates is equalled zero; The concrete computation process of the described poincare sphere angle of cut is: making the poincare sphere radius of binary channels polarization analysis instrument 6 inside is s
0, the coordinate of the point from the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ;
Restraint laser after the 4th single-mode polarization maintaining fiber 23 via second of the second fiber optic splitter 17 beam splitting, as the first input signal of optical-fiber bundling device 18, another road that the 3rd fiber optic splitter 24 produces laser signal along separate routes, after the 5th single-mode polarization maintaining fiber 25 as the second input signal of optical-fiber bundling device 18, the two-way input signal of optical-fiber bundling device 18 closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device 18, this laser beam directly and on the photosurface of photodiode 19 interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph 21 via concentric cable 20 and shows, the equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
Embodiment four: present embodiment as shown in Figure 4,2 μ m laser instrument 1 Emission Lasers signals, produce laser signal along separate routes by the 3rd fiber optic splitter 24, wherein a road shunt laser signal is input to acousto-optic frequency shifters 3 after the input port 3-1 of acousto-optic frequency shifters 3; The voltage of regulating frequency modulation port 3-4, to 5.2V and radio-frequency power modulation port 3-5 voltage to 1.0V, reaches diffraction efficiency maximal value, from 0 order diffraction port 3-3 and 1 order diffraction port 3-2 output two-way laser signal; The laser beam of 1 order diffraction port 3-2 output, through the transmission of the second single-mode polarization maintaining fiber 5, after the tail-fiber type Green GRIN Lens that is 0.23 7 collimations, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate 9 and lens 10, becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping becomes right-hand circular polarization signal from linear polarization signal after polarization beam splitter prism 11 and λ/4 wave plate 12, right-hand circular polarization signal enters into from axle optical antenna 13, from axle optical antenna 13 to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through atmospheric aerosol, produces back scattering laser signal, and this signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal returns along original optical path after receiving from axle optical antenna 13, and after λ/4 wave plate 12, polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction rotated 90 degree, be polarized beam splitter prism 11 and reflect;
Laser beam after polarization beam splitter prism 11 reflections is after the drive unit 14 with polaroid 15, be coupled through coupled lens 16, then be divided into two-way laser signal through the second fiber optic splitter 17, wherein a road laser signal enters binary channels Polarization instrument 6 from first signal input port 6-1 after the 3rd single-mode polarization maintaining fiber 22, and an other road is as the laser echo signal in coherent detection process;
Another road shunting sign of the 3rd fiber optic splitter 24 secondary signal input port 6-2 through binary channels polarization analysis instrument 6 after the 8th single-mode polarization maintaining fiber 28 enters binary channels polarization analysis instrument 6;
Binary channels polarization analysis instrument 6 calculates respectively from the poincare sphere angle of cut of the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input, and change poincare sphere position angle difference into voltage signal and input to the external drive signal of drive unit 14 as drive unit 14 via the first concentric cable 8, polaroid 15 is the rotation taking 0.02 degree as stepping amount under the drive of stepper motor 14, until the poincare sphere angle of cut that binary channels polarization analysis instrument 6 calculates is equalled zero; The concrete computation process of the described poincare sphere angle of cut is: making the poincare sphere radius of binary channels polarization analysis instrument 6 inside is s
0, the coordinate of the point from the laser signal of first signal input port 6-1 and secondary signal input port 6-2 input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ;
Restraint laser after the 4th single-mode polarization maintaining fiber 23 via second of the second fiber optic splitter 17 beam splitting, as the first input signal of optical-fiber bundling device 18, after the input port 3-1 of another road shunting sign of the 3rd fiber optic splitter 24 by the first single-mode polarization maintaining fiber 2 and acousto-optic frequency shifters 3, be input to acousto-optic frequency shifters 3; The voltage of regulating frequency modulation port 3-4 is to 5.2V and radio-frequency power modulation port 3-5 voltage to 1.0V, reach after diffraction efficiency maximal value, from 0 order diffraction port 3-3 output, after the 7th single-mode polarization maintaining fiber 27 as the second input signal of optical-fiber bundling device 18, the two-way input signal of optical-fiber bundling device 18 closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device 18, this laser beam directly and on the photosurface of photodiode 19 interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph 21 via concentric cable 20 and shows; The equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
The content not being described in detail in instructions of the present invention belongs to professional and technical personnel in the field's known technology.
Claims (6)
1. a mu m coherent anemometry laser radar polarization state is mated and corrects structure, it is characterized in that comprising: 2 μ m laser instruments (1), the first single-mode polarization maintaining fiber (2), acousto-optic frequency shifters (3), the first fiber optic splitter (4), the second single-mode polarization maintaining fiber (5), binary channels Polarization instrument (6), tail-fiber type Green GRIN Lens (7), the first concentric cable (8), λ/2 wave plate (9), lens (10), polarization beam splitter prism (11), λ/4 wave plate (12), from axle optical antenna (13), drive unit (14), polaroid (15), coupled lens (16), the second fiber optic splitter (17), optical-fiber bundling device (18), photodiode (19), the second concentric cable (20), oscillograph (21), the 3rd single-mode polarization maintaining fiber (22) and the 4th single-mode polarization maintaining fiber (23),
Acousto-optic frequency shifters (3) comprises input port (3-1), 1 order diffraction output port (3-2), 0 order diffraction output port (3-3), frequency modulation (PFM) port (3-4) and radio-frequency power modulation port (3-5), and binary channels Polarization instrument system (6) comprises first signal input port (6-1) and secondary signal input port (6-2);
2 μ m laser instrument (1) Emission Lasers signals, are input to acousto-optic frequency shifters (3) after the input port (3-1) by the first single-mode polarization maintaining fiber (2) and acousto-optic frequency shifters (3); By the voltage-regulation of modulation port (3-4) to 5.2V, by radio-frequency power modulation port (3-5) voltage modulated to 1.0V, make acousto-optic frequency shifters (3) reach diffraction efficiency maximal value, from 0 order diffraction port (3-3) and 1 order diffraction port (3-2) output two-way laser signal; The laser beam of 1 order diffraction port (3-2) output, through the transmission of the second single-mode polarization maintaining fiber (5), after the tail-fiber type Green GRIN Lens (7) that is 0.23 collimation, forms coherent wind laser radar pulse signal via intercept;
After the beam shaping of coherent wind laser radar pulse signal via λ/2 wave plate (9) and lens (10), becoming diameter is 1～2mm, the angle of divergence is the laser beam of 1mrad, laser beam after shaping becomes right-hand circular polarization signal from linear polarization signal after polarization beam splitter prism (11) and λ/4 wave plate (12), right-hand circular polarization signal enters into from axle optical antenna (13), from axle optical antenna (13) to laser beam expand with alignment procedure after laser signal is transmitted into free space;
The laser signal being transmitted in free space reflects through large gasoloid, produces back scattering laser signal, and back scattering laser signal is Left-hand circular polarization laser; Left-hand circular polarization back scattering laser signal is received from axle optical antenna (13) and after λ/4 wave plate (12), polarization state becomes linearly polarized laser from Left-hand circular polarization, and its polarization direction has rotated 90 degree, be polarized beam splitter prism (11) reflection;
Laser beam after polarization beam splitter prism (11) reflection is after the polaroid (15) in over-driving device (14), be coupled through coupled lens (16), then be divided into two-way laser signal through the second fiber optic splitter (17), wherein a road laser signal enters binary channels Polarization instrument (6) from first signal input port (6-1) after the 3rd single-mode polarization maintaining fiber (22);
Be divided into two-way by 2 μ m laser of 0 order diffraction output port (3-3) output of acousto-optic frequency shifters (3) after via the first fiber optic splitter (4), wherein a road laser enters binary channels polarization analysis instrument (6) through the secondary signal input port (6-2) of binary channels polarization analysis instrument (6);
Binary channels polarization analysis instrument (6) calculates the poincare sphere angle of cut of the laser signal of inputting from first signal input port (6-1) and secondary signal input port (6-2) respectively, and change this poincare sphere angle of cut into voltage signal and input to the external drive signal of drive unit (14) as drive unit (14) via the first concentric cable (8), polaroid (15) is the rotation taking 0.02 degree as stepping amount under the drive of drive unit (14), until the poincare sphere angle of cut that binary channels polarization analysis instrument (6) calculates is equalled zero,
Restraint laser after the 4th single-mode polarization maintaining fiber (23) via second of the second fiber optic splitter (17) beam splitting, as the first input signal of optical-fiber bundling device (18), restraint second input signal of laser as optical-fiber bundling device (18) via second of the first fiber optic splitter (4) beam splitting, the two-way input signal of optical-fiber bundling device (18) closes Shu Chengyi road 2 μ m laser signals via optical-fiber bundling device (18), this laser beam directly and on the photosurface of photodiode (19) interferes, produce intermediate-freuqncy signal, this intermediate-freuqncy signal is input to oscillograph (21) via concentric cable (20) and shows, the equal zero intermediate-freuqncy signal in moment of the poincare sphere angle of cut is the intermediate-freuqncy signal of signal to noise ratio (S/N ratio) maximum.
2. a kind of 2 mu m coherent anemometry laser radar polarization state couplings according to claim 1 and rectification structure, is characterized in that: the concrete computation process of the described poincare sphere angle of cut is: making the inner poincare sphere radius of binary channels polarization analysis instrument (6) is s
0, the coordinate of the point from the laser signal of first signal input port (6-1) and secondary signal input port (6-2) input on poincare sphere in spherical coordinate system is respectively (s
0, ψ, θ) and (s
0, χ, θ), ψ and χ are poincare sphere position angle, the poincare sphere angle of cut is: ψ-χ.
3. a kind of 2 mu m coherent anemometry laser radar polarization state couplings according to claim 1 and rectification structure, it is characterized in that: described beam shaping process is specially: regulate the polarization direction of λ/2 wave plates (9) and monitor transmitted through the optical signal power after polarization beam splitter prism (11), until this performance number maximum; Lens (10) are positioned over simultaneously and realize the shaping process to laser beam from tail-fiber type Green GRIN Lens (7) light output end 60mm place.
4. a kind of 2 mu m coherent anemometry laser radar polarization state couplings according to claim 1 and rectification structure, is characterized in that: the second input signal of the input signal of described binary channels polarization analysis instrument (6) secondary signal input port (6-2) and optical-fiber bundling device (18) produces in the following way:
Laser signal produces laser signal along separate routes through being arranged on 2 μ m laser instruments (1) the 3rd fiber optic splitter (24) afterwards, this shunt laser signal produces laser signal along separate routes after the first fiber optic splitter (4), wherein a road shunting sign is as the input signal of binary channels polarization analysis instrument (6) secondary signal input port (6-2), and another road shunting sign is as the second input signal of optical-fiber bundling device (18).
5. a kind of 2 mu m coherent anemometry laser radar polarization state couplings according to claim 1 and rectification structure, is characterized in that: the second input signal of the input signal of described binary channels polarization analysis instrument (6) secondary signal input port (6-2) and optical-fiber bundling device (18) produces in the following way:
Laser signal produces laser signal along separate routes through being arranged on 2 μ m laser instruments (1) the 3rd fiber optic splitter (24) afterwards, one tunnel shunt laser signal as the second input signal of optical-fiber bundling device (18), is input to acousto-optic frequency shifters (3) after the input port (3-1) of another road shunting sign by the first single-mode polarization maintaining fiber (2) and acousto-optic frequency shifters (3) after the 5th single-mode polarization maintaining fiber (25); The voltage of regulating frequency modulation port (3-4) is to 5.2V and radio-frequency power modulation port (3-5) voltage to 1.0V, reach after diffraction efficiency maximal value, from 0 order diffraction port (3-3) output, after the 6th single-mode polarization maintaining fiber (26) as the input signal of binary channels polarization analysis instrument (6) secondary signal input port (6-2).
6. a kind of 2 mu m coherent anemometry laser radar polarization state couplings according to claim 1 and rectification structure, is characterized in that: the second input signal of the input signal of described binary channels polarization analysis instrument (6) secondary signal input port (6-2) and optical-fiber bundling device (18) produces in the following way:
Laser signal produces along separate routes laser signal through being arranged on 2 μ m laser instruments (1) the 3rd fiber optic splitter (24) afterwards, a road along separate routes laser signal after the 8th single-mode polarization maintaining fiber (28) as the input signal of binary channels polarization analysis instrument (6) secondary signal input port (6-2);
After the input port (3-1) of another road shunting sign by the first single-mode polarization maintaining fiber (2) and acousto-optic frequency shifters (3), be input to acousto-optic frequency shifters (3); The voltage of regulating frequency modulation port (3-4) is to 5.2V and radio-frequency power modulation port (3-5) voltage to 1.0V, reach after diffraction efficiency maximal value, from 0 order diffraction port (3-3) output, after the 7th single-mode polarization maintaining fiber (27) as the second input signal of optical-fiber bundling device (18).
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| CN106199559B (en) * | 2016-06-30 | 2018-09-07 | 中国科学技术大学 | A kind of while atmospheric sounding wind speed and depolarization ratio coherent laser radar |
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| CN110780310A (en) * | 2019-12-31 | 2020-02-11 | 杭州爱莱达科技有限公司 | Polarization diversity dual-channel speed measuring and distance measuring coherent laser radar measuring method and device |
| CN112945083A (en) * | 2021-01-29 | 2021-06-11 | 中国科学院长春光学精密机械与物理研究所 | Parallel phase shift digital holographic microscopic imaging system with optical fiber interconnection |
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