CN116068584A - Non-blind area coherent laser radar - Google Patents
Non-blind area coherent laser radar Download PDFInfo
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- CN116068584A CN116068584A CN202310233574.2A CN202310233574A CN116068584A CN 116068584 A CN116068584 A CN 116068584A CN 202310233574 A CN202310233574 A CN 202310233574A CN 116068584 A CN116068584 A CN 116068584A
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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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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
- G01P13/02—Indicating direction only, e.g. by weather vane
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/26—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave
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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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- 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
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Abstract
The invention discloses a non-blind area coherent laser radar, which comprises: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator. The polarization modulation device is used for adjusting the polarization state of signals in the optical path, so that the polarization states of echo signals output by the local oscillation light and the circulator are the same, and the polarization state of a reflected signal of the telescope end surface which does not enter the telescope is different from the local oscillation light only by reflecting the reflected signal of the telescope end surface. The invention adjusts the polarization state of the signal in the light path through the polarization modulation device, and distinguishes the internal reflection light of the signal reflected by the end face of the telescope from the echo signal returned from the object to be measured, so that the internal reflection light cannot beat frequency with the local oscillation light, and the echo signal can beat frequency with the local oscillation light. The detection capability of the pulse laser radar is optimized by adjusting the polarization state, filtering out the dead zone distance caused by the internal reflection light.
Description
Technical Field
The invention relates to a laser radar, in particular to a blind-zone-free coherent laser radar.
Background
The laser wind measuring radar is used for measuring the wind direction and the wind speed in the high altitude. The laser radar wind measurement is used as a novel mobile wind measurement technology, the Doppler frequency shift principle of laser is utilized, and the wind speed and wind direction information is obtained by measuring the frequency change generated by the light wave reflection of aerosol particles encountering wind movement in the air, so that the vector wind speed and wind direction data of corresponding heights are calculated.
The echo signal generated by the interaction of the polarization-maintaining pulse laser emitted by the light source and the atmosphere and the local system local oscillation light generate a difference frequency signal, and the amplified difference frequency signal is measured at the same time, so that the radial wind speed can be obtained relatively easily. The light source part comprises a pulsed high-power laser (emergent light) and a narrow-linewidth continuous wave laser (local oscillation light), a small part of the emergent light is used for mixing with the local oscillation light, a large part of the emergent light is emitted into the atmosphere, then is scattered by aerosol or atmospheric molecules in the air to generate echo signals, and the echo signals are mixed with the local oscillation light after being received by the telescope; the detection part comprises two detectors, one is used for detecting the mixed signal of the frequency of the emergent light and the frequency of the local oscillation light, and the other is used for detecting the mixed signal of the echo signal and the local oscillation light. The light source part is composed of a continuous light source, a coupler, an AOM, a multistage amplifier and a circulator. The continuous light source is used for separating a small part of power to serve as local oscillation light through the coupler, then the other part of the continuous light source is used for generating pulse waveforms through the AOM acousto-optic modulator, pulse energy is lifted through the multistage amplifier, finally the pulse energy is emitted to the atmosphere through a port of the circulator 2, and weak back reflection light in the atmosphere can be received through the port 2 and emitted through the port 3 due to reversible light paths, so that the available signal light source to be measured is formed.
However, the inventors of the present invention studied to find that: pulse lidar generally has a Dead Time of several to several hundred nanoseconds, when a beam of laser pulse is emitted, an internal reflection signal is firstly generated at a laser emitting lens and is received by a detector, if an obstacle is too close, since the laser receiver is still in the Dead Time, pulse echoes of a close-range object can be submerged by the internal reflection signal, and thus the distance measurement of the close-range object is inaccurate.
The problem of inaccuracy in the detection of close objects by pulsed lidar is called "spot" and this is a difficult problem that plagues the industry as a whole, requiring the underlying detector hardware to evolve continuously. The short-distance zone with inaccurate ranging is usually set as a "dead zone", which is usually between 0 and 30m in size.
Disclosure of Invention
In order to solve the problems, the invention adds a deflection state rotator to distinguish the internal reflection light from the signal return light, so that the internal reflection light is not beaten with the local oscillation light, and the signal return light can beaten with the local oscillation light. Therefore, the dead zone distance caused by the internal reflection light is filtered, and the applicability of the pulse laser radar is optimized.
A non-blind area coherent lidar comprising: the device comprises a continuous light source, a coupler, a pulse generator, an amplifier, a circulator, a telescope and a polarization modulation device;
the continuous light source is used for outputting continuous polarized light;
the coupler is used for dividing signals output by the continuous light source into two paths, wherein one path is used as pulse light and outputs the pulse light to the pulse generator, and the other path is used as local oscillation light and outputs the pulse light;
the pulse generator is used for converting the output continuous light into pulse light;
the circulator comprises an input end, a receiving and transmitting end and an output end, wherein the input end is used for receiving a pulse signal output by the pulse generator, the receiving and transmitting end is used for outputting the input signal to the telescope and receiving an echo signal returned from the telescope, and the output end is used for outputting the echo signal received by the receiving and transmitting end;
the polarization modulation device is used for adjusting the polarization state of signals in the optical path, so that the polarization states of echo signals output by the local oscillation light and the circulator are the same, and the polarization state of a reflected signal of the telescope end surface which does not enter the telescope is different from the local oscillation light, and the reflected signal is reflected only from the telescope end surface;
and the continuous light source, the coupler, the pulse generator and the circulator are all connected by adopting polarization maintaining optical fibers.
Further, the polarization modulation device comprises a polarization state rotator and a polarization state changer;
the polarization state rotator is connected with one output end of the coupler and is used for rotating the polarization state of local oscillation light output by the coupler by 90 degrees; the polarization state rotator is formed by vertically and continuously forming cat eyes of two polarization-maintaining optical fibers;
the polarization state changer is arranged in the emergent light path of the telescope, when the pulse light emitted by the telescope passes through the polarization state changer, the polarization state of the signal is rotated 45 degrees, and when the echo signal passes through the polarization state changer again, the polarization state of the signal is continuously rotated 45 degrees in the same direction; the polarization state of the echo signal output by the circulator is different from the polarization state of the pulse light input by the circulator by 90 degrees; the polarization state of the reflected signal of the telescope end face is the same as that of the signal output by the continuous light source.
Further, the polarization modulation device comprises two identical polarization state changers, namely a first polarization state changer and a second polarization state changer;
the first polarization state changer is arranged in a light path between the receiving and transmitting end of the circulator and the telescope, and when pulse light emitted by the receiving and transmitting end passes through the first polarization state changer, the polarization state of the signal is rotated by 45 degrees; after the signal reflected by the end face of the telescope passes through the first polarization state changer, the polarization state of the signal continues to rotate 45 degrees; the polarization state of the reflected signal of the telescope end face returned to the circulator is 90 degrees different from the polarization state of the signal output by the continuous light source;
the second polarization state changer is arranged in an emergent light path of the telescope, when pulse light emitted by the telescope passes through the second polarization state changer, the polarization state of the signal is rotated 45 degrees, when the echo signal passes through the second polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction, and when the echo signal passes through the first polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction; the polarization state of the echo signal returned to the circulator is the same as the polarization state of the local oscillation.
Further, the polarization state changer is used for rotating the polarization state by 90 degrees in whole after passing the optical signal forward and backward once each.
Further, the polarization state changer is a 45-degree Faraday rotator.
Further, the polarization state changer is a 1/4 wave plate.
Further, the polarization state changer is a 1/4 zero-order wave plate.
Further, the device also comprises a balance detector, wherein the balance detector is used for carrying out balance detection on the local oscillation light and the echo signal.
The invention adjusts the polarization state of the signal in the light path through the polarization modulation device, and distinguishes the internal reflection light of the signal reflected by the end face of the telescope from the echo signal returned from the object to be measured, so that the internal reflection light cannot beat frequency with the local oscillation light, and the echo signal can beat frequency with the local oscillation light. The detection capability of the pulse laser radar is optimized by adjusting the polarization state, filtering out the dead zone distance caused by the internal reflection light.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions and advantages of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a coherent laser radar without blind areas according to embodiment 1 of the present invention;
fig. 2 is a block diagram of a coherent laser radar without blind areas according to embodiment 2 of the present invention;
FIG. 3 is a schematic diagram of a polarization rotator and a polarization changer;
fig. 4 is a block diagram of a coherent laser radar without blind areas according to embodiment 3 of the present invention;
fig. 5 is a block diagram of a coherent laser radar without blind areas according to embodiment 4 of the present invention;
FIG. 6 is a block diagram of a coherent lidar without blind areas according to embodiment 5 of the present invention;
fig. 7 is a block diagram of a coherent lidar without blind areas according to embodiment 6 of the present invention;
fig. 8 is a block diagram of a coherent laser radar without blind areas according to embodiment 7 of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1:
as shown in fig. 1, the present invention provides a non-blind area coherent laser radar, comprising: the device comprises a continuous light source, a coupler, a pulse generator, an amplifier, a circulator, a telescope and a polarization modulation device;
the continuous light source is configured to output continuous polarized light.
The coupler is used for dividing signals output by the continuous light source into two paths, one path is used as pulse light and output to the pulse generator, and the other path is used as local oscillation light and output.
The pulse generator may be an acousto-optic modulator AOM, an electro-optic modulator EOM, etc.
The pulse generator is used for converting the output continuous light into pulse light.
The circulator comprises an input end, a receiving end and an output end, wherein the input end is used for receiving a pulse signal output by the pulse generator, the receiving end is used for outputting the input signal to the telescope and receiving an echo signal returned from the telescope, and the output end is used for outputting the echo signal received by the receiving end. In the drawings and embodiments of the present invention, the input end corresponds to port 1, the receiving end corresponds to port 2, and the output end corresponds to port 3.
The polarization modulation device is used for adjusting the polarization state of signals in the optical path, so that the polarization states of echo signals output by the local oscillation light and the circulator are the same, and the polarization state of a reflected signal of the telescope end surface which does not enter the telescope is different from the local oscillation light only by reflecting the reflected signal of the telescope end surface which does not enter the telescope.
And the continuous light source, the coupler, the pulse generator and the circulator are all connected by adopting polarization maintaining optical fibers.
In the embodiment of the invention, the polarized light output by the continuous light source is slow axis light, namely P polarized light. Of course, in other embodiments, other polarization states of light are also possible.
Preferably, the device further comprises a balance detector, wherein the balance detector is used for carrying out balance detection on the local oscillation light and the echo signal.
The invention adjusts the polarization state of the signal in the light path through the polarization modulation device, and distinguishes the internal reflection light of the signal reflected by the end face of the telescope from the echo signal returned from the object to be measured, so that the internal reflection light cannot beat frequency with the local oscillation light, and the echo signal can beat frequency with the local oscillation light. The detection capability of the pulse laser radar is optimized by adjusting the polarization state, filtering out the dead zone distance caused by the internal reflection light.
Example 2:
as shown in fig. 2, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises a polarization state rotator and a polarization state changer.
The polarization state rotator is connected with one output end of the coupler and is used for rotating the polarization state of local oscillation light output by the coupler by 90 degrees; the polarization state rotator is formed by vertically and continuously forming cat eyes of two polarization-maintaining optical fibers.
The polarization maintaining fiber comprises a fiber core and two stress rods. The two stress rods are symmetrical relative to the fiber core in the fiber cross section, and the combination of the stress rods of the polarization maintaining fiber is also called a cat eye of the polarization maintaining fiber.
The polarization state rotator can change the polarization state of the optical signals transmitted in the optical fibers by vertically and continuously arranging the cat eyes of the two optical fibers, and rotate the polarization state by 90 degrees.
The polarization state changer is arranged in the emergent light path of the telescope, when the pulse light emitted by the telescope passes through the polarization state changer, the polarization state of the signal is rotated 45 degrees, and when the echo signal passes through the polarization state changer again, the polarization state of the signal is continuously rotated 45 degrees in the same direction; the polarization state of the echo signal output by the circulator is different from the polarization state of the pulse light input by the circulator by 90 degrees; the polarization state of the reflected signal of the telescope end face is the same as that of the signal output by the continuous light source.
As shown in FIG. 2, the non-blind area coherent laser radar provided by the invention comprises a continuous light source, a coupler, a polarization state rotator, a pulse generator, an amplifier, a circulator, a telescope and a polarization state changer. The optical signal output by the continuous light source is slow axis light, a small part of power is split by the coupler and is used as local oscillation light after passing through the polarization state rotator, and the local oscillation light is fast axis light. The other part then generates a pulse waveform by means of a pulse generator and the pulse energy is lifted by means of an amplifier and then injected into the telescope through port 2 of the circulator. Because of the reflection effect generated by the end face of the telescope, a small part of light is directly reflected back to the circulator and is emitted out through the port 3, namely, the internal reflection light is slow axis light; wherein most of the light enters the polarization state changer after passing through the telescope, and the light is emitted to a target to be measured, such as the atmosphere after the polarization state of the light is changed. Because the light path is reversible, weak signal return light in the atmosphere can reversely enter the polarization state changer and generate polarization state change, the detection light and the signal return light are rotated by 90 degrees after passing through the polarization state changer in the forward direction and the reverse direction, become fast axis light, enter the port 2 of the circulator for receiving, and are emitted through the port 3 to form the detection return light which is the fast axis light. The return light of the present invention is also referred to as an echo signal or return light.
Therefore, when the local oscillation light is fast axis light, the internal reflection light is slow axis light, and the detection return light is fast axis light, the local oscillation light only forms beat frequency signals with the detection return light, and cannot form any signals with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
Fig. 3 is a schematic diagram of a polarization rotator and a polarization changer. As can be seen from fig. 3, the polarization state rotator and the polarization state modifier operate differently.
As shown in fig. 3, the function of the polarization rotator is to rotate the polarization by 90 degrees when the optical signal is passing in the forward direction. The function of the polarization state changer is to rotate the polarization state by 90 degrees as a whole after passing the optical signal forward and backward once each.
The invention adjusts the polarization state of the signal in the light path through the polarization state rotator and the polarization state changer, and distinguishes the internal reflection light of the signal reflected by the end face of the telescope from the echo signal returned from the object to be measured, so that the internal reflection light cannot beat frequency with the local oscillation light, and the echo signal can beat frequency with the local oscillation light. The detection capability of the pulse laser radar is optimized by adjusting the polarization state, filtering out the dead zone distance caused by the internal reflection light.
Example 3:
as shown in fig. 4, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises a polarization state rotator and a polarization state changer.
The polarization state rotator is connected with one output end of the coupler and is used for rotating the polarization state of local oscillation light output by the coupler by 90 degrees; the polarization state rotator is formed by vertically and continuously forming cat eyes of two polarization-maintaining optical fibers.
The polarization maintaining fiber comprises a fiber core and two stress rods. The two stress rods are symmetrical relative to the fiber core in the fiber cross section, and the combination of the stress rods of the polarization maintaining fiber is also called a cat eye of the polarization maintaining fiber.
The polarization state rotator can change the polarization state of the optical signals transmitted in the optical fibers by vertically and continuously arranging the cat eyes of the two optical fibers, and rotate the polarization state by 90 degrees.
The polarization state changer is used for rotating the polarization state by 90 degrees in whole after passing the optical signal forward and backward once.
The polarization state changer is a 45-degree Faraday rotator.
As shown in FIG. 4, the polarization maintaining pulse light source is composed of the continuous light source, the coupler, the pulse generator and the amplifier. The polarization state changer is composed of a 45-degree Faraday rotation plate, the polarization state is rotated by 45 degrees when the linear polarization passes forward, the polarization state is rotated by 45 degrees continuously in the same direction after the linear polarization passes backward, and the forward and the backward are rotated by 90 degrees.
The polarization-maintaining pulse light source generates a pulse light signal which is slow axis light, and simultaneously generates a continuous light signal which is also slow axis light. The continuous optical signal is changed into fast axis light after passing through the vertical continuous connection point of the cat eye, which is local oscillation light. The pulsed optical signal is input from port 1 of the circulator and output from port 2, and still is slow axis light. When it passes through the telescope, a small portion of it is reflected back into the circulator port 2, also slow axis light, due to the weak reflection at the end face, and exits from port 3, forming internally reflected light, also slow axis light. In addition, most pulse light signals (P polarized light) enter a Faraday rotation piece with an angle of 45 degrees after passing through the telescope, the polarization state is rotated by 45 degrees, after being reflected by a detection object in a short distance, the pulse light signals reversely pass through the Faraday rotation piece again, and the polarization state is rotated by 45 degrees again in the same direction, so that return light at the moment is S polarized light, then enters the circulator port 2 after continuously passing through the telescope, at the moment is fast axis light, and finally, the return light is output through the circulator port 3 to form signal return light, and the signal return light is the fast axis light.
Therefore, when the local oscillation light is fast axis light, the internal reflection light is slow axis light, the detection return light is fast axis light, the local oscillation light only forms beat frequency signals with the detection return light, and any signals are not formed with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
Example 4:
as shown in fig. 5, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises a polarization state rotator and a polarization state changer.
The polarization state rotator is connected with one output end of the coupler and is used for rotating the polarization state of local oscillation light output by the coupler by 90 degrees; the polarization state rotator is formed by vertically and continuously forming cat eyes of two polarization-maintaining optical fibers.
The polarization maintaining fiber comprises a fiber core and two stress rods. The two stress rods are symmetrical relative to the fiber core in the fiber cross section, and the combination of the stress rods of the polarization maintaining fiber is also called a cat eye of the polarization maintaining fiber.
The polarization state rotator can change the polarization state of the optical signals transmitted in the optical fibers by vertically and continuously arranging the cat eyes of the two optical fibers, and rotate the polarization state by 90 degrees.
The polarization state changer is used for rotating the polarization state by 90 degrees in whole after passing the optical signal forward and backward once.
The polarization state changer is a 1/4 wave plate. Preferably, the polarization state changer is a 1/4 zero-order wave plate. However, other stages of 1/4 wave plates are also suitable for use in the present invention.
The polarization-maintaining pulse light source consists of the continuous light source, coupler, pulse generator and amplifier. The polarization state rotator is formed by vertically and continuously forming two polarization maintaining fiber cat eyes. The polarization state changer consists of a 1/4 zero-order wave plate which is placed at 45 degrees with the optical axis. The transmitted P polarized light is changed into circularly polarized light after passing through the wave plate, and is changed into S polarized light after being reflected by the wave plate, so that the forward direction and the reverse direction are rotated by 90 degrees together.
The polarization-maintaining pulse light source generates a pulse light signal which is slow axis light, and simultaneously generates a continuous light signal which is also slow axis light. The continuous optical signal is changed into fast axis light after passing through the vertical continuous connection point of the cat eye, which is local oscillation light. The pulsed optical signal is input from port 1 of the circulator and output from port 2, and still is slow axis light. When it passes through the telescope, a small portion of it is reflected back into the circulator port 2, also slow axis light, due to the weak reflection at the end face, and exits from port 3, forming internally reflected light, also slow axis light. In addition, most pulse light signals (P polarized light) enter a 1/4 zero-order wave plate after passing through the telescope and become circularly polarized light, after being reflected by a detection object in a near distance, the pulse light signals reversely pass through the 1/4 zero-order wave plate again, the polarization state becomes S polarized light, then the S polarized light continuously passes through the telescope and enters the circulator port 2 to be fast axis light, and finally the fast axis light is output through the circulator port 3 to form signal return light.
Therefore, when the local oscillation light is fast axis light, the internal reflection light is slow axis light, the detection return light is fast axis light, the local oscillation light only forms beat frequency signals with the detection return light, and any signals are not formed with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
Example 5:
as shown in fig. 6, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises two identical polarization state changers, namely a first polarization state changer and a second polarization state changer;
in one application scenario, as shown in fig. 7, the polarization state changer is configured to rotate the polarization state by 90 degrees in its entirety after passing the optical signal forward and backward once each.
The first polarization state changer is arranged in a light path between the receiving and transmitting end of the circulator and the telescope, and when pulse light emitted by the receiving and transmitting end passes through the first polarization state changer, the polarization state of the signal is rotated by 45 degrees; after the signal reflected by the end face of the telescope passes through the first polarization state changer, the polarization state of the signal continues to rotate 45 degrees; the polarization state of the reflected signal of the telescope end face returned to the circulator is 90 degrees different from the polarization state of the signal output by the continuous light source;
the second polarization state changer is arranged in an emergent light path of the telescope, when pulse light emitted by the telescope passes through the second polarization state changer, the polarization state of the signal is rotated 45 degrees, when the echo signal passes through the second polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction, and when the echo signal passes through the first polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction; the polarization state of the echo signal returned to the circulator is the same as the polarization state of the local oscillation.
Specifically, the polarization-maintaining pulse light source is composed of the continuous light source, the coupler, the pulse generator and the amplifier. The rest part is a circulator, and the two polarization state changers and the telescope are formed.
The polarization maintaining pulse light source generates pulse light signal, which is slow axis light, and also generates continuous light signal, which is slow axis light, and which is local oscillation light. The pulsed optical signal is input from port 1 of the circulator and output from port 2, and still is slow axis light. When the light passes through the telescope, the polarization state of the light after passing through the first polarization state changer changes, and then, a small part of the light is reflected back to the polarization state after passing through the first polarization state changer to be S-polarized light due to weak reflection of the end face, and then, the light returns to the port 2 of the circulator to be fast-axis light, and the fast-axis light is emitted from the port 3 to form internal reflection light which is also fast-axis light. In addition, most pulse light signals enter the second polarization state changer after passing through the telescope, the polarization state is S polarized light, after being reflected by a detection object in a short distance, the pulse light signals reversely pass through the second polarization state changer again, the polarization state is changed, after continuing to pass through the telescope and then pass through the first polarization state changer, the pulse light signals enter the circulator port 2, the pulse light signals are slow axis light at the moment, and finally, the pulse light signals are output through the circulator port 3 to form signal return light which is slow axis light.
Thus, when the local oscillation light is slow axis light, the internal reflection light is fast axis light, the signal return light is slow axis light, the local oscillation light only forms beat frequency signals with the signal return light, and any signals are not formed with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
Example 6:
as shown in fig. 7, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises two identical polarization state changers, namely a first polarization state changer and a second polarization state changer.
The polarization state changer is a 45-degree Faraday rotator. I.e. the first polarization state changer and the second polarization state changer are both 45 degrees faraday rotator.
As shown in the figure, the polarization-maintaining pulse light source is composed of the continuous light source, a coupler, a pulse generator and an amplifier. The polarization state rotator is a 45 degree angle faraday rotator. The rest parts are a circulator and a telescope.
The polarization maintaining pulse light source generates pulse light signal, which is slow axis light, and also generates continuous light signal, which is slow axis light, and which is local oscillation light. The pulsed optical signal is input from port 1 of the circulator and output from port 2, and still is slow axis light. The polarization state of the light passing through the first 45-degree Faraday rotary plate is changed into an oblique polarization state, and then the light passes through the telescope, wherein a small part of the light is reflected and reversely passes through the 45-degree Faraday rotary plate, the polarization state of the light passing through the first 45-degree Faraday rotary plate is S-polarized light, and then the light returns to the port 2 of the circulator, so that the light is fast-axis light and is emitted from the port 3 to form internal reflection light, and the internal reflection light is also fast-axis light. In addition, most pulse light signals enter a second 45-degree Faraday rotation sheet after passing through the telescope, the polarization state is S polarized light, after being reflected by a detection object in a short distance, the pulse light signals reversely pass through a second polarization state changer again, the polarization state is oblique polarized state, then the pulse light signals continue to pass through the telescope and pass through the first 45-degree Faraday rotation sheet, the polarization state is P polarized light, the P polarized light enters a circulator port 2, the slow axis light is formed at the moment, and finally, the signal return light is formed by outputting through a circulator port 3 and is the slow axis light.
Thus, when the local oscillation light is slow axis light, the internal reflection light is fast axis light, the signal return light is slow axis light, the local oscillation light only forms beat frequency signals with the signal return light, and any signals are not formed with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
Example 7:
as shown in fig. 8, the present invention provides a non-blind area coherent laser radar, comprising: continuous light source, coupler, pulse generator, amplifier, circulator, telescope and polarization modulator.
The continuous light source, the coupler, the pulse generator and the amplifier form a polarization-maintaining continuous light source, which is the same as that in embodiment 1 and will not be described again.
The polarization modulation device comprises two identical polarization state changers, namely a first polarization state changer and a second polarization state changer.
The polarization state changer is a 1/4 wave plate. I.e. the first polarization state modifier and the second polarization state modifier are each 1/4 wave plates.
As shown in the figure, the polarization-maintaining pulse light source is composed of the continuous light source, a coupler, a pulse generator and an amplifier. The polarization state rotator is a 1/4 zero order slide. The rest parts are a circulator and a telescope.
The polarization maintaining pulse light source generates pulse light signal, which is slow axis light, and also generates continuous light signal, which is slow axis light, and which is local oscillation light. The pulsed optical signal is input from port 1 of the circulator and output from port 2, and still is slow axis light. The polarization state of the light passing through the first polarization state changer becomes circular polarized light, and then when the light passes through the telescope, a small part of the light is reflected back to the polarization state of the light passing through the first polarization state changer, and then the light returns to the port 2 of the circulator to be fast axis light, and the light is emitted from the port 3 to form internal reflection light which is fast axis light. In addition, most pulse light signals enter the second polarization state changer after passing through the telescope, the polarization state is S polarized light, after being reflected by a detection object in a short distance, the pulse light signals reversely pass through the second polarization state changer again, the polarization state is circularly polarized light, then the pulse light signals continue to pass through the telescope and then pass through the first polarization state changer, the pulse light signals enter the circulator port 2, the pulse light signals are slow axis light at the moment, and finally, the pulse light signals are output through the circulator port 3 to form signal return light which is slow axis light.
Thus, when the local oscillation light is slow axis light, the internal reflection light is fast axis light, the signal return light is slow axis light, the local oscillation light only forms beat frequency signals with the signal return light, and any signals are not formed with the internal reflection light. Therefore, the end reflection of the telescope can be filtered, and the dead zone is thoroughly eliminated.
The invention eliminates the influence of the internal reflection light by changing the polarization states of the local oscillation light, the internal reflection light and the signal return light, and changes two of the internal reflection light by different modes so that the polarization states of the internal reflection light and the polarization states of the local oscillation light and the signal return light are perpendicular, thereby avoiding beat signals.
The rotation polarization mode is various and is within the scope of protection as long as it meets the definition of a polarization rotator and a polarization changer
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (8)
1. A non-blind area coherent lidar comprising: the device comprises a continuous light source, a coupler, a pulse generator, an amplifier, a circulator, a telescope and a polarization modulation device;
the continuous light source is used for outputting continuous polarized light;
the coupler is used for dividing signals output by the continuous light source into two paths, wherein one path is used as pulse light and outputs the pulse light to the pulse generator, and the other path is used as local oscillation light and outputs the pulse light;
the pulse generator is used for converting the output continuous light into pulse light;
the circulator comprises an input end, a receiving and transmitting end and an output end, wherein the input end is used for receiving a pulse signal output by the pulse generator, the receiving and transmitting end is used for outputting the input signal to the telescope and receiving an echo signal returned from the telescope, and the output end is used for outputting the echo signal received by the receiving and transmitting end;
the polarization modulation device is used for adjusting the polarization state of signals in the optical path, so that the polarization states of echo signals output by the local oscillation light and the circulator are the same, and the polarization state of a reflected signal of the telescope end surface which does not enter the telescope is different from the local oscillation light, and the reflected signal is reflected only from the telescope end surface;
and the continuous light source, the coupler, the pulse generator and the circulator are all connected by adopting polarization maintaining optical fibers.
2. The non-blind spot coherent lidar of claim 1, wherein the polarization modulation device comprises a polarization rotator and a polarization changer;
the polarization state rotator is connected with one output end of the coupler and is used for rotating the polarization state of local oscillation light output by the coupler by 90 degrees; the polarization state rotator is formed by vertically and continuously forming cat eyes of two polarization-maintaining optical fibers;
the polarization state changer is arranged in the emergent light path of the telescope, when the pulse light emitted by the telescope passes through the polarization state changer, the polarization state of the signal is rotated 45 degrees, and when the echo signal passes through the polarization state changer again, the polarization state of the signal is continuously rotated 45 degrees in the same direction; the polarization state of the echo signal output by the circulator is different from the polarization state of the pulse light input by the circulator by 90 degrees; the polarization state of the reflected signal of the telescope end face is the same as that of the signal output by the continuous light source.
3. The non-blind spot coherent lidar of claim 1, wherein the polarization modulation device comprises two identical polarization state changers, a first polarization state changer and a second polarization state changer, respectively;
the first polarization state changer is arranged in a light path between the receiving and transmitting end of the circulator and the telescope, and when pulse light emitted by the receiving and transmitting end passes through the first polarization state changer, the polarization state of the signal is rotated by 45 degrees; after the signal reflected by the end face of the telescope passes through the first polarization state changer, the polarization state of the signal continues to rotate 45 degrees; the polarization state of the reflected signal of the telescope end face returned to the circulator is 90 degrees different from the polarization state of the signal output by the continuous light source;
the second polarization state changer is arranged in an emergent light path of the telescope, when pulse light emitted by the telescope passes through the second polarization state changer, the polarization state of the signal is rotated 45 degrees, when the echo signal passes through the second polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction, and when the echo signal passes through the first polarization state changer again, the polarization state of the signal is rotated 45 degrees continuously in the same direction; the polarization state of the echo signal returned to the circulator is the same as the polarization state of the local oscillation.
4. The non-blind spot coherent lidar of claim 1, wherein the polarization state changer is configured to rotate the polarization state by 90 degrees as a whole after passing the optical signal forward and backward once each.
5. The non-blind spot coherent lidar of claim 1, wherein the polarization state changer is a 45 degree faraday rotator.
6. The non-blind spot coherent lidar of claim 1, wherein the polarization state changer is a 1/4 wave plate.
7. The non-blind spot coherent lidar of claim 6, wherein the polarization state changer is a 1/4 zero-order waveplate.
8. The non-blind spot coherent lidar of claim 4, further comprising a balance detector for balanced detection of local oscillator light and echo signals.
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Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201097026Y (en) * | 2007-06-15 | 2008-08-06 | 福州高意光学有限公司 | A polarization related separator for free space |
| CN101487738A (en) * | 2008-02-04 | 2009-07-22 | 北京高光科技有限公司 | Method and apparatus for measuring optical spectral property based on polarization analysis |
| JP2012207934A (en) * | 2011-03-29 | 2012-10-25 | Mitsubishi Electric Corp | Doppler lidar device |
| CN103185970A (en) * | 2011-12-29 | 2013-07-03 | 林先锋 | Method and device for translating polarization light, controlling optical signals and selecting light route of wavelengths |
| CN105158770A (en) * | 2015-10-10 | 2015-12-16 | 中国科学技术大学 | Coherent wind measurement laser radar system with adjustable range resolution |
| CN106199559A (en) * | 2016-06-30 | 2016-12-07 | 中国科学技术大学 | Atmospheric sounding wind speed and the coherent laser radar of depolarization ratio while of a kind of |
| CN109459761A (en) * | 2018-12-20 | 2019-03-12 | 南京牧镭激光科技有限公司 | A kind of laser radar |
| CN111007526A (en) * | 2020-01-15 | 2020-04-14 | 安徽大学 | System and method for suppressing optical noise of continuous wave all-fiber coherent Doppler laser speed measurement radar |
| CN112346082A (en) * | 2020-11-30 | 2021-02-09 | 北京理工大学珠海学院 | Coherent Doppler wind lidar, method and storage medium |
| CN114019534A (en) * | 2021-11-22 | 2022-02-08 | 上海科乃特激光科技有限公司 | Wind measuring radar |
| CN114063113A (en) * | 2021-12-22 | 2022-02-18 | 深圳大舜激光技术有限公司 | All-fiber non-blind area polarization laser radar system and atmospheric parameter detection method |
| CN115084989A (en) * | 2022-07-01 | 2022-09-20 | 杭州奥创光子技术有限公司 | Solid laser amplifier and femtosecond pulse laser device |
| CN115184960A (en) * | 2022-06-15 | 2022-10-14 | 南京牧镭激光科技有限公司 | Pulse type coherent wind lidar based on non-polarization-maintaining light path |
| CN217639632U (en) * | 2022-06-10 | 2022-10-21 | 苏州旭创科技有限公司 | Circulator and optical module |
-
2023
- 2023-03-13 CN CN202310233574.2A patent/CN116068584A/en active Pending
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201097026Y (en) * | 2007-06-15 | 2008-08-06 | 福州高意光学有限公司 | A polarization related separator for free space |
| CN101487738A (en) * | 2008-02-04 | 2009-07-22 | 北京高光科技有限公司 | Method and apparatus for measuring optical spectral property based on polarization analysis |
| JP2012207934A (en) * | 2011-03-29 | 2012-10-25 | Mitsubishi Electric Corp | Doppler lidar device |
| CN103185970A (en) * | 2011-12-29 | 2013-07-03 | 林先锋 | Method and device for translating polarization light, controlling optical signals and selecting light route of wavelengths |
| CN105158770A (en) * | 2015-10-10 | 2015-12-16 | 中国科学技术大学 | Coherent wind measurement laser radar system with adjustable range resolution |
| CN106199559A (en) * | 2016-06-30 | 2016-12-07 | 中国科学技术大学 | Atmospheric sounding wind speed and the coherent laser radar of depolarization ratio while of a kind of |
| CN109459761A (en) * | 2018-12-20 | 2019-03-12 | 南京牧镭激光科技有限公司 | A kind of laser radar |
| CN111007526A (en) * | 2020-01-15 | 2020-04-14 | 安徽大学 | System and method for suppressing optical noise of continuous wave all-fiber coherent Doppler laser speed measurement radar |
| CN112346082A (en) * | 2020-11-30 | 2021-02-09 | 北京理工大学珠海学院 | Coherent Doppler wind lidar, method and storage medium |
| CN114019534A (en) * | 2021-11-22 | 2022-02-08 | 上海科乃特激光科技有限公司 | Wind measuring radar |
| CN114063113A (en) * | 2021-12-22 | 2022-02-18 | 深圳大舜激光技术有限公司 | All-fiber non-blind area polarization laser radar system and atmospheric parameter detection method |
| CN217639632U (en) * | 2022-06-10 | 2022-10-21 | 苏州旭创科技有限公司 | Circulator and optical module |
| CN115184960A (en) * | 2022-06-15 | 2022-10-14 | 南京牧镭激光科技有限公司 | Pulse type coherent wind lidar based on non-polarization-maintaining light path |
| CN115084989A (en) * | 2022-07-01 | 2022-09-20 | 杭州奥创光子技术有限公司 | Solid laser amplifier and femtosecond pulse laser device |
Non-Patent Citations (1)
| Title |
|---|
| 唐政: "连续波激光相干多普勒测风雷达关键技术研究", 《中国优秀硕士学位论文全文数据库 信息科技辑》, no. 3, pages 18 - 38 * |
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