CN110308454B - Wind speed measurement system and method of quasi-non-blind-area Doppler coherent laser radar - Google Patents
Wind speed measurement system and method of quasi-non-blind-area Doppler coherent laser radar Download PDFInfo
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- CN110308454B CN110308454B CN201910608446.5A CN201910608446A CN110308454B CN 110308454 B CN110308454 B CN 110308454B CN 201910608446 A CN201910608446 A CN 201910608446A CN 110308454 B CN110308454 B CN 110308454B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/50—Systems of measurement based on relative movement of target
- G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
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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
- G01S7/481—Constructional features, e.g. arrangements of optical elements
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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
- G01S7/483—Details of pulse systems
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
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Abstract
The invention relates to the technical field of laser radars, in particular to a wind speed measuring system and method of a quasi-blind-area-free Doppler coherent laser radar. The invention has the advantages that: the invention adjusts the included angle between the laser transmitting optical axis and the laser receiving optical axis, and removes the influence of intermediate frequency signals on useful wind speed signals, thereby improving the signal-to-noise ratio and realizing the detection precision and the resolution capability of weak wind field signals.
Description
Technical Field
The invention relates to the technical field of laser radars, in particular to a wind speed measuring system and method of a quasi-blind-area-free Doppler coherent laser radar.
Background
The real-time atmospheric wind field information can provide atmospheric wind field data support for wind power generation site selection, climate monitoring and pollution transportation; meanwhile, real-time wind direction shear can also influence the stability of aircraft navigation, and the detection and early warning of a real-time wind field in the field of aviation are important for take-off and landing of civil aircraft. At present, more technical methods are used for acquiring the atmospheric wind field, for example, a conventional meteorological sounding balloon is used for measuring the atmospheric wind field, a microwave wind measuring radar is used for measuring the atmospheric wind field, a laser coherent radar is used for measuring the atmospheric wind field, and the like; various wind field measurement means are applied in different fields. The conventional sounding method is applied more in the meteorological field, and has the advantages that an atmospheric wind field is directly obtained according to the GPS position change of the sounding balloon, the measuring method is direct, and the measuring height can reach twenty-thirty kilometers at high altitude; the method has the defects that the period for measuring the wind field is long, and a group of wind profiles needs 1-2 hours. The microwave wind measuring radar is also applied more at present, has the advantages that the microwave can observe an atmospheric wind field all weather without being interfered by cloud layers, and has the defects that the transmitting/receiving antenna array of the microwave wind measuring radar has larger volume and low-altitude blind areas report about one hundred meters. For a laser coherent wind measuring radar, two systems of continuous laser and pulse laser coherent wind measuring exist at present, the continuous laser radar focuses on low-altitude wind field measurement, and the maximum measurement height is low; the pulse laser radar can measure a high-altitude wind field but has a large low-altitude blind area. The low altitude blind area of the continuously laser coherent wind measuring radar is reported to be about dozens of meters, and the blind area of the pulse laser radar, which is limited by the pulse width and interferes with the received signal due to the reflection of the transmitting laser end surface, is larger than that of the continuous laser radar and is about hundred meters. Therefore, the laser coherent wind-finding radar of the two systems does not solve the problem of low altitude blind areas.
Disclosure of Invention
The invention provides a system and a method for measuring the wind speed of a quasi-blind area-free Doppler coherent laser radar, aiming at the problems of large low-altitude blind area, low resolution and complex system of a laser coherent wind measurement technology.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a quasi-no blind area Doppler coherent laser radar wind speed measurement system, includes emitter, receiving arrangement, emitter launches to atmospheric laser emission optical axis and receiving arrangement's laser receiving optical axis and forms contained angle alpha, contained angle alpha angularly adjustable.
Preferably, the transmitting device comprises a transmitting optical fiber and a first beam expander which are sequentially arranged on a laser transmitting optical axis, the main vibration light is transmitted through the transmitting optical fiber and then passes through the first beam expander to be transmitted out of the transmitting device, and a transmitting moving assembly for driving the end face to move is further arranged at the output end face of the transmitting optical fiber;
the receiving device comprises a second beam expanding lens and a receiving optical fiber which are sequentially arranged on a laser receiving optical axis, receiving light penetrating through the second beam expanding lens is input into an input end face of the receiving optical fiber, and a receiving moving assembly for adjusting the position of the end face is arranged at the input end face of the receiving optical fiber.
Preferably, the launching moving assembly comprises a first fixing piece and a launching translation table, wherein the first fixing piece is used for fixing the output end face of the launching optical fiber, and the launching translation table is used for fixing the first fixing piece and driving the end face of the optical fiber on the first fixing piece to move in the set direction; similarly, the receiving and moving assembly comprises a second fixing piece and a receiving and translating table, wherein the second fixing piece is used for fixing the input end face of the receiving optical fiber, and the receiving and translating table is used for fixing the second fixing piece and driving the end face of the optical fiber on the second fixing piece to move in the set direction.
Preferably, the system further comprises a laser reflection unit, the laser reflection unit comprises a transmitting optical adjustment lens, a receiving optical adjustment lens and a blade prism, the transmitting optical adjustment lens reflects incident light emitted by the transmitting device to the upper edge position of one coated surface of the blade prism and then reflects the incident light to the atmosphere, the upper edge position of the other coated surface of the blade prism reflects the received light to the receiving optical adjustment lens, and the receiving optical adjustment lens continues to reflect the received light to a second beam expander in the receiving device.
Optimally, the angles of the transmitting optical adjusting lens and the receiving optical adjusting lens are adjustable.
Optimally, a diaphragm is arranged on the blade prism along the direction parallel to the laser receiving optical axis.
Preferably, the system further comprises a laser generation unit, wherein the laser generation unit comprises a laser, and the laser emitted by the laser is pulse laser or continuous laser.
The method for using the wind speed measuring system of the quasi-non-blind-area Doppler coherent laser radar further comprises a coupler, a photoelectric differential detector and a processing control unit, and the method comprises the following steps:
s1, adjusting the transmitting device and the receiving device to enable the laser transmitting optical axis of the transmitting device and the laser receiving optical axis of the receiving device to be located on the same plane, wherein the plane is a plane A;
s2, determining the displacement surfaces of the transmitting movable assembly and the receiving movable assembly, and ensuring that the displacement surfaces of the transmitting movable assembly and the receiving movable assembly are parallel to the plane A;
s3, the processing control unit controls the included angle between the moving direction of the emission moving component and the laser emission optical axis, and the position of the emission laser focusing focus is always on the laser emission optical axis in the moving process of the emission moving component; meanwhile, the processing control unit ensures that the echo signal at the focus of the transmitted laser is always coupled into the receiving optical fiber at the focus of the receiving device by adjusting the position of the receiving movable assembly;
s4, in the moving process of the transmitting moving assembly and the receiving moving assembly, calibrating according to the theoretical relation between the included angle alpha of the laser transmitting optical axis and the laser receiving optical axis and the positions of the transmitting moving assembly and the receiving moving assembly, obtaining the included angle between the laser transmitting optical axis and the laser receiving optical axis according to the translation amount of the transmitting moving assembly and the receiving moving assembly, and further obtaining the measurement height of the radar;
s5, after the echo signal with the designated height passes through the coupler and the local oscillator optical beat frequency, the photoelectric differential detector converts the beat frequency signal which is the optical signal into an electric signal and transmits the electric signal to the processing control unit for fast Fourier transform, and the radial wind speed of the current point is obtained.
Preferably, the system further includes a laser reflection unit, and in step S1, the angles of the laser emission mirror and the laser receiving mirror in the laser reflection unit are further adjusted to make the laser emission optical axis of the emission device and the laser receiving optical axis of the receiving device located on the same plane; in step S3, when the moving direction of the output end face of the transmitting optical fiber changes with the included angle of the laser emission optical axis, moving the transmitting optical adjustment lens to make the transmitting light edge coincide with the upper edge of the blade prism; meanwhile, the receiving optical adjusting lens is moved, so that the included angle between the laser transmitting optical axis and the laser receiving optical axis is as small as possible on the premise that the transmitting device and the receiving device do not cut light.
The invention has the advantages that:
(1) with the conventional coaxial structure, because the reflection of the end face of the optical fiber and the mirror surface causes the intermediate frequency signal to exist in the echo signal, the intermediate frequency signal may submerge the useful wind speed signal, and the wind speed at the lower height during the low altitude measurement cannot be detected. The invention adjusts the included angle between the laser transmitting optical axis and the laser receiving optical axis, and removes the influence of intermediate frequency signals on useful wind speed signals, thereby improving the signal-to-noise ratio and realizing the detection precision and the resolution capability of weak wind field signals. The invention realizes the measurement of wind profiles with different heights by adjusting the included angle alpha.
(2) The invention realizes that the laser transmitting optical axis and the laser receiving optical axis are coplanar, and the displacement surfaces in the transmitting moving assembly and the receiving moving assembly are parallel to the optical axis surface, thereby always keeping the brightest area near the optical axis of the echo signal in the center of the optical fiber end surface of the receiving device when the transmitting moving assembly and the receiving moving assembly move, and ensuring the receiving efficiency of the radar. Specifically, the transmitting optical fiber and the receiving optical fiber both use single-mode polarization-maintaining optical fibers, the diameter of the fiber core is about ten microns, and the receiving field of view is in the magnitude of micro-arc degree, so that the coupling efficiency is improved.
(3) The included angle between the laser transmitting optical axis and the laser receiving optical axis is obtained by calibrating the moving position of the transmitting moving component, and the radar measuring height is determined through the included angle, so that the laser transmitting optical axis and the laser receiving optical axis can be intersected at the height of several meters below the ground by changing the position of the output end surface of the transmitting optical fiber; the method realizes the quasi-non-blind area measurement of the atmospheric wind field. In addition, the invention can only detect the echo signals in the cross area of two beams of light of the laser emission optical axis and the laser receiving optical axis, and the height resolution is related to the length of the cross area only; the invention has small actual beam overlapping area and high measurement resolution.
(4) The wind measuring radar measures a wind field by taking air scattering light as a signal, and the air scattering signal is very weak; the invention adopts the blade prism to transmit and receive laser, can make the included angle between the laser transmitting optical axis and the laser receiving optical axis as small as possible under the determined transmitting/receiving caliber, can obviously increase the cross area at the measuring height, improve the effective echo volume and increase the echo signal intensity. In addition, the shading diaphragm is arranged at the top end of the blade prism, so that forward scattering light of emitted laser is prevented from entering the receiving device, an emitted light path and a received light path are completely independent, interference of the emitted light on the receiving device is avoided, and the imaging signal-to-noise ratio is improved.
(5) The invention is compatible with two systems of pulse laser and continuous laser; compared with the traditional pulse radar, when a pulse system is adopted, the receiving device only detects the echo signal near the crossed position of the optical axis, the echo signal is not influenced by the pulse width and is not interfered by the emitted laser, and the radar can detect the signal in ten meters at low altitude; and because pulse radar peak power is high, this scheme can accomplish the atmosphere wind field of measuring several kilometers of height scope equally.
(6) The processing control unit is used for detecting Doppler frequency shift signals caused by a wind field, obtaining the radial wind speed in the laser emission direction, and controlling the emitting device and the receiving device to realize the measurement of wind speeds and wind directions at different heights.
Drawings
FIG. 1 is a schematic diagram of the structural design of the radar of the present invention.
FIG. 2 is a schematic view showing the laser emission optical axis and the laser receiving optical axis being coplanar and a schematic view showing the moving direction of the translation stage.
Fig. 3 shows the doppler shift signal of the wind field actually measured by the present invention at a height of 8 meters.
FIG. 4 shows a wind field Doppler shift signal measured at 280 m height by using continuous laser according to the present invention.
FIG. 5 is a visibility monitoring curve for a test period in accordance with the present invention.
1-laser generating unit 11-laser 12-local oscillator light
2-laser emitting unit
21-first fixing piece 22-emission translation stage 23-first beam expander 24-emission optical fiber
3-laser reflection unit
31-transmitting optical adjusting lens 32-receiving optical adjusting lens 33-blade prism
4-laser receiving unit
41-second mount 42-receiving translation stage 43-second expander lens 44-receiving fiber
5-coupler 6-photoelectric differential detector 7-processing control unit 8-diaphragm
9-laser emission optical axis 10-laser reception optical axis
Detailed Description
As shown in fig. 1, a wind speed measuring system of a quasi-blind-area-free doppler coherent laser radar includes a laser generating unit 1, a transmitting device 2, a laser reflecting unit 3, a receiving device 4, a coupler 5, a photoelectric differential detector 6, and a processing control unit 7.
The laser generating unit 1 includes a laser 11, a beam splitter for splitting laser emitted from the laser 11 into two beams, wherein an acousto-optic modulator is arranged in the coaxial direction of one beam of laser, and a frequency shifter is integrated in the laser 11 to enable a fixed frequency difference to exist between a local oscillation light 12 and a main laser 13. The output end of the acousto-optic modulator outputs main oscillation light which is sent to the transmitting device (2), and the other beam is used as the oscillation light. The frequency of the laser changes after the laser passes through the acousto-optic modulator to generate fixed frequency shift. The main vibration light is emitted to the air through the emitting device 2 and the laser reflection unit 3 to measure Doppler frequency shift caused by the air, an echo signal carrying a Doppler frequency shift signal sequentially passes through the laser reflection unit 3 and the receiving device 4 to receive an optical signal and a local vibration optical signal emitted by the laser generation unit 1 and is input into the coupler 5 to be coupled, the optical signal at the output end of the coupler 5 is transmitted to the photoelectric differential detector 6, the photoelectric differential detector 6 converts the optical signal into an electrical signal and transmits the electrical signal to the processing control unit 7 to be processed, and then the air Doppler frequency shift signal is detected to obtain the atmospheric air speed.
The emitting device 2 comprises an emitting optical fiber 24 and a first beam expander 23 which are sequentially arranged on the laser emitting optical axis 9, the main vibration light passes through the first beam expander 23 after being transmitted by the emitting optical fiber 24 to be emitted out of the emitting device 2, and an emitting moving component for driving the end face to move is further arranged at the output end face of the emitting optical fiber 24. The launching moving assembly comprises a first fixing member 21 for fixing the output end face of the launching optical fiber 24, and a launching translation stage 22, wherein the launching translation stage 22 is used for fixing the first fixing member 21 and driving the optical fiber end face thereon to move in a set direction.
The receiving device 4 includes a second beam expander 43 and a receiving optical fiber 44 sequentially arranged on the laser receiving optical axis 10, the received light passing through the second beam expander 43 is input into the input end surface of the receiving optical fiber 44, and a receiving moving component for adjusting the position of the end surface is arranged at the input end surface of the receiving optical fiber 44. The receiving and moving assembly comprises a second fixing member 41 for fixing the input end face of the receiving optical fiber 44, and a receiving and translating table 42, wherein the receiving and translating table 42 is used for fixing the second fixing member 41 and driving the optical fiber end face thereon to move in the set direction.
The movement of the emission translation stage 22 realizes the focusing of the emission laser at different heights; meanwhile, the position of the receiving translation stage 42 is adjusted to realize the emission of the echo signal at the focal point of the laser, and the movement of the receiving translation stage 42 enables the input end face of the receiving optical fiber 44 to be always positioned at the focal point of the receiving device.
In this embodiment, the transmitting device 2 and the receiving device have the same structure, and mass production is possible, thereby reducing production cost.
The laser reflection unit 3 includes an emitting optical adjustment lens 31, a receiving optical adjustment lens 32, and a blade prism 33, where the emitting optical adjustment lens 31 reflects the incident light emitted from the emitting device 2 to the upper edge position of one coated surface of the blade prism 33 and then reflects the incident light to the atmosphere, the upper edge position of the other coated surface of the blade prism 33 reflects the received light to the receiving optical adjustment lens 32, and then the receiving optical adjustment lens 32 continues to reflect the received light to the second beam expander 43 in the receiving device 4. The angles of the transmitting optical adjustment lens 31 and the receiving optical adjustment lens 32 are adjustable. The transmitting optical adjustment lens 31, the receiving optical adjustment lens 32 and the blade prism 33 in the optical lens group 3 function as: the upper edge of the emission beam is coincided with the upper edge of the blade prism, the upper edge of the receiving beam is coincided with the upper edge of the blade prism, the included angle between the emission optical axis 9 and the laser receiving optical axis 10 can be reduced as much as possible through two coincidence operations, and the overlapping area of the two beams is improved so as to improve the intensity of echo signals. And a diaphragm 8 is arranged on the blade prism 33 along the direction parallel to the laser receiving optical axis 10. When the emission translation stage 22 moves, the direction of the emission beam changes, and the laser irradiated to the upper edge of the blade prism 33 is diffracted to cause part of the laser to be directly incident into the receiving device 4; and the laser forward scattered light may also enter the receiving means 4. The signal intensity of the direct or forward scattered light of the emitting device 2 is much stronger than the signal intensity of the backward scattered light of the air at the measurement altitude. The diaphragm 8 tightly connected with the upper edge of the blade prism 33 plays a role in avoiding the interference of the emitted light beam signal to the received signal, and the complete independence of the transmitting device 2 and the receiving device 4 is realized.
The specific method for using the system is as follows:
s1, adjusting the emitting device 2 and the receiving device 4 to enable the laser emitting optical axis 9 of the emitting device 2 and the laser receiving optical axis 10 of the receiving device 4 to be located on the same plane, wherein the plane is a plane A;
s2, determining the displacement surfaces of the transmitting movable assembly and the receiving movable assembly, and ensuring that the displacement surfaces of the transmitting movable assembly and the receiving movable assembly are parallel to the plane A;
s3, the processing control unit 7 controls the included angle between the moving direction of the emission moving component and the laser emission optical axis 9, and the position of the focusing focus of the emitted laser is ensured to be always on the laser emission optical axis 9 in the moving process of the emission moving component; meanwhile, the processing control unit 7 ensures that the echo signal at the focus of the transmitted laser is always coupled into the receiving optical fiber 44 at the focus of the receiving device 4 by adjusting the position of the receiving moving component;
s4, in the moving process of the transmitting moving assembly and the receiving moving assembly, calibrating according to the theoretical relation between the included angle alpha of the laser transmitting optical axis 9 and the laser receiving optical axis 10 and the positions of the transmitting moving assembly and the receiving moving assembly, obtaining the included angle between the laser transmitting optical axis 9 and the laser receiving optical axis 10 according to the translation amount of the transmitting moving assembly and the receiving moving assembly, and further obtaining the measurement height of the radar;
s5, after the echo signal with the designated height passes through the coupler 5 and the local oscillator optical beat frequency, the photoelectric differential detector 6 converts the beat frequency signal which is the optical signal into an electric signal and transmits the electric signal to the processing control unit 7 for fast Fourier transform, and the radial wind speed of the current point is obtained.
When the system further includes the laser reflection unit 3, in step S1, the angles of the laser emission mirror 31 and the laser receiving mirror 32 in the laser reflection unit 3 need to be adjusted, so that the laser emission optical axis 9 of the emission device 2 and the laser receiving optical axis 10 of the receiving device 4 are located on the same plane; in step S3, when the moving direction of the output end face of the emission optical fiber 24 changes with the included angle of the laser emission optical axis 9, the emission optical adjustment lens 31 is moved to make the emission optical edge coincide with the upper edge of the blade prism; meanwhile, the receiving optical adjusting lens 32 is moved, so that the included angle between the laser emitting optical axis 9 and the laser receiving optical axis 10 is as small as possible on the premise that the emitting device 2 and the receiving device 4 do not cut light.
In order to implement the most basic principle in this application, the laser reflection unit 3 in fig. 1 is removed to obtain a schematic diagram as shown in fig. 2.
In the figure, an X-O-Y plane represents a plane a where the transmitting optical axis 9 and the laser receiving optical axis 10 are located, displacement planes of the transmitting translation stage 22 and the receiving translation stage 42 are parallel to the plane a, a Y axis is parallel to the laser receiving optical axis 10, and an X axis is parallel to a central connecting line of the first beam expander 23 and the second beam expander 43. The output end face of the emission optical fiber 24 mounted thereon moves therewith under the drive of the emission translation stage 22, causing the orientation of the emission optical axis 9 to change in the a-plane. The distance between the intersection position of the laser emitting optical axis 9 and the laser receiving optical axis 10 and the system represents the detection distance of the radar. The driving direction of the receiving translation stage 42 is parallel to or coincident with the laser receiving optical axis 10, and the transmitting translation stage 22 and the receiving translation stage 42 respectively drive the corresponding optical fiber end faces to move simultaneously, so that the focus of the air scattering signal at the intersection point of the laser transmitting optical axis 9 and the laser receiving optical axis 10 on the second beam expander 43 just falls on the input end face of the receiving optical fiber 44.
The output end face of the emission optical fiber 24 is driven to move at the emission translation stage 22, so that the focal point position of the emission light beam is changed, and the installation angle beta of the emission translation stage 22 is calculated and designed, so that the focal point of the emission light beam is just at the intersection point of the laser emission optical axis 9 and the laser receiving optical axis 10 when the output end face of the emission optical fiber 24 moves in the moving direction. The method for determining the included angle alpha comprises the following steps: firstly, determining the distance delta between the central point of the first beam expander 23 and the central point of the second beam expander 43; secondly, a virtual measuring point (x, y) is determined on the laser receiving optical axis 10, the included angle alpha between the laser emitting optical axis 9 passing through the measuring point and the laser receiving optical axis 10 is calculated, and the central distance between the measuring point and the first beam expander 23 is calculated
Wherein (x, y)0) Is the second expander lens 43 center position coordinate. And then calculating the image distance v of the measurement point imaged on the first beam expander 23 according to the object-image relationship. Finally, the output end face position coordinates (x ', y') of the transmitting fiber 24 are calculated:
through the above formula, two groups of included angles α and the position coordinates of the output end face of the corresponding launching fiber 24 are calculated, and the installation angle β of the launching translation stage 22 is calculated.
After the theoretical relationship among the position coordinate of the output end face of the transmitting optical fiber 24, the focusing focal point coordinate of the transmitted laser, and the installation angle β of the transmitting translation stage 22 is obtained, the relationship between the displacement of the transmitting translation stage 22 and the included angle α between the laser transmitting optical axis 9 and the laser receiving optical axis 10 can be easily calculated according to the geometric relationship. However, since the initial positions of the emission translation stages 22 are relative, when the corresponding relationship between the theoretical coordinate and the actual position is not established, the focal position (x, y) of the emission laser and the output end face position (x ', y') of the emission optical fiber 24 need to be calibrated once under the actual atmospheric condition, so as to realize the correspondence between the theoretical coordinate system and the actual position. After calibration is completed, the measurement height of the radar can be calculated according to the relation between the translation amount of the emission translation table 22 and the included angle alpha.
The measured height and the position of the receiving translation stage 42 conform to a basic object-image relationship; after one-time calibration, the corresponding relationship between the object-image relationship and the position of the receiving translation stage 42 can be established. After the corresponding relationship between the theoretical positions and the actual positions of the motion of the output end face of the transmitting optical fiber 24 and the input end face of the receiving optical fiber 44 is determined, the transmitting translation stage 22 and the receiving translation stage 42 can be quantitatively controlled by the processing control unit 7 under the actual atmospheric condition, so that the measurement of wind fields with different heights can be realized. In the invention, the launching translation stage 22 only needs to move in one direction and does not need to move in a two-dimensional direction, so that the workload of adjusting the launching translation stage 22 is reduced, and meanwhile, a driving structure and a guiding structure which are needed by moving in one dimension can be saved, thereby saving the system cost.
According to the design, the Doppler frequency shift signal caused by air movement with the height of 8 meters is measured in actual atmosphere, and the test result is shown in FIG. 3; the test result proves that the invention has the capability of measuring the atmospheric wind field within 10 meters of low altitude, and achieves the expected purpose. Meanwhile, the Doppler frequency shift signals caused by wind speed with the height of 16 meters and the height of 280 meters are realized by electrically controlling the positions of the transmitting translation stage 22 and the receiving translation stage 42.
Atmospheric visibility in a test period is measured by using an visibility meter, and the measurement result shows that the visibility exceeds 50 kilometers, so that the atmospheric visibility test method belongs to a test condition that the air is very clean. The lower the visibility, the stronger the echo signal and the easier the test, and the higher the visibility, the more difficult the test is. In addition, in order to further verify the system capacity, the whole system is arranged on a supporting platform, a two-dimensional scanning rotary table is arranged below the supporting platform, and the two-dimensional scanning rotary table realizes rotation in the horizontal plane direction and rotation in the vertical direction. The doppler shift signal for a measurement height of 280 meters varies with the azimuth of rotation of the two-dimensional turntable as shown in fig. 4. The system can obtain Doppler frequency shift signals with the height of 8 meters in low altitude, particularly the height of 280 meters in clean atmosphere with the visibility exceeding 50 kilometers based on the rotation azimuth angle of the two-dimensional rotary table, and the experimental result is shown in figure 5.
The invention is not to be considered as limited to the specific embodiments shown and described, but is to be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (4)
1. A wind speed measuring system of a quasi-blind-area-free Doppler coherent laser radar is characterized by comprising a transmitting device (2) and a receiving device (4), wherein a laser transmitting optical axis (9) transmitted to the atmosphere by the transmitting device (2) and a laser receiving optical axis (10) of the receiving device (4) form an included angle alpha, and the included angle alpha is adjustable;
the transmitting device (2) comprises a transmitting optical fiber (24) and a first beam expander (23) which are sequentially arranged on a laser transmitting optical axis (9), main vibration light is transmitted through the transmitting optical fiber (24) and then penetrates through the first beam expander (23) to be transmitted out of the transmitting device (2), and a transmitting moving component for driving the end face to move is further arranged at the output end face of the transmitting optical fiber (24);
the receiving device (4) comprises a second beam expanding lens (43) and a receiving optical fiber (44) which are sequentially arranged on the laser receiving optical axis (10), the received light passing through the second beam expanding lens (43) is input into the input end face of the receiving optical fiber (44), and a receiving moving assembly for adjusting the position of the end face is arranged at the input end face of the receiving optical fiber (44).
2. The wind speed measurement system of the quasi-blind-area-free Doppler coherent laser radar is characterized in that the launching moving assembly comprises a first fixing piece (21) for fixing the output end face of the launching optical fiber (24), a launching translation stage (22), and the launching translation stage (22) is used for fixing the first fixing piece (21) and driving the optical fiber end face thereon to move in a set direction; similarly, the receiving and moving assembly comprises a second fixing member (41) for fixing the input end face of the receiving optical fiber (44), and a receiving and translating table (42), wherein the receiving and translating table (42) is used for fixing the second fixing member (41) and driving the optical fiber end face on the second fixing member to move in the set direction.
3. The wind speed measurement system of the quasi-blind-area-free Doppler coherent lidar according to claim 1, further comprising a laser generating unit (1), wherein the laser generating unit (1) comprises a laser (11), and the laser emitted by the laser (11) is a pulse laser or a continuous laser.
4. Method of using a system for wind velocity measurement of a quasi-blind-area-free doppler coherent lidar according to any of claims 1-3, characterized in that the system further comprises a coupler (5), a photo-differential detector (6), a processing control unit (7), the method comprising the steps of:
s1, adjusting the transmitting device (2) and the receiving device (4) to enable the laser transmitting optical axis (9) of the transmitting device (2) and the laser receiving optical axis (10) of the receiving device (4) to be located on the same plane, wherein the plane is a plane A;
s2, determining the displacement surfaces of the transmitting movable assembly and the receiving movable assembly, and ensuring that the displacement surfaces of the transmitting movable assembly and the receiving movable assembly are parallel to the plane A;
s3, the processing control unit (7) controls the moving direction of the transmitting moving component to further change the included angle between the laser transmitting optical axis (9) and the laser receiving optical axis (10), and the position of the focusing focus of the transmitted laser is ensured to be always on the laser transmitting optical axis (9) in the moving process of the transmitting moving component according to the set angle; meanwhile, the processing control unit (7) ensures that the echo signal at the focus of the transmitted laser is always coupled into the receiving optical fiber (44) at the focus of the receiving device (4) by adjusting the position of the receiving moving component;
s4, in the moving process of the transmitting moving assembly and the receiving moving assembly, calibrating according to the theoretical relation between the included angle alpha of the laser transmitting optical axis (9) and the laser receiving optical axis (10) and the positions of the transmitting moving assembly and the receiving moving assembly, obtaining the included angle between the laser transmitting optical axis (9) and the laser receiving optical axis (10) according to the translation amount of the transmitting moving assembly, and further obtaining the measurement height of the radar;
s5, after the echo signal with the designated height passes through the coupler (5) and the local oscillator optical beat frequency, the photoelectric differential detector (6) converts the beat frequency signal which is the optical signal into an electric signal and transmits the electric signal to the processing control unit (7) for fast Fourier transform, and the radial wind speed of the current point is obtained.
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| TWI739397B (en) * | 2020-04-17 | 2021-09-11 | 崑山科技大學 | LiDAR point cloud data processing method and its use in wind field analysis |
| CN113540950B (en) * | 2021-07-15 | 2023-03-14 | 中国人民解放军国防科技大学 | Electro-optic modulation depth real-time measurement and control system and method based on VIPA etalon |
| EP4379422A1 (en) * | 2021-08-17 | 2024-06-05 | Huawei Technologies Co., Ltd. | Transceiver optical system, lidar, terminal device, and method and apparatus |
| CN114265016B (en) * | 2021-12-28 | 2023-04-14 | 河北德冠隆电子科技有限公司 | Multi-angle adjustment wide area radar sensor system and method |
| CN114706099B (en) * | 2022-06-07 | 2022-11-22 | 成都凯天电子股份有限公司 | Laser wind finding radar optical module and measuring method thereof |
| CN117434296B (en) * | 2023-12-15 | 2024-03-15 | 南京牧镭激光科技股份有限公司 | Method, equipment and storage medium for measuring wind speed of fan impeller surface by laser double radars |
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