CN116626696A - Frequency modulation continuous wave laser range unit - Google Patents

Frequency modulation continuous wave laser range unit Download PDF

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Publication number
CN116626696A
CN116626696A CN202310896482.2A CN202310896482A CN116626696A CN 116626696 A CN116626696 A CN 116626696A CN 202310896482 A CN202310896482 A CN 202310896482A CN 116626696 A CN116626696 A CN 116626696A
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CN
China
Prior art keywords
laser
detection
continuous wave
light source
signal
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Pending
Application number
CN202310896482.2A
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Chinese (zh)
Inventor
张邦宏
杨春林
王俊
王冠
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Beijing Moore Core Optical Semiconductor Technology Co ltd
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Beijing Moore Core Optical Semiconductor Technology Co ltd
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Priority to CN202310896482.2A priority Critical patent/CN116626696A/en
Publication of CN116626696A publication Critical patent/CN116626696A/en
Pending legal-status Critical Current

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Classifications

    • 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
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S17/34—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C15/00—Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
    • G01C15/002—Active optical surveying means
    • G01C15/004—Reference lines, planes or sectors
    • 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
    • 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
    • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • G01S7/4812—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver transmitted and received beams following a coaxial path
    • 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
    • G01S7/491—Details of non-pulse systems
    • G01S7/4911—Transmitters
    • 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
    • G01S7/491—Details of non-pulse systems
    • G01S7/4912—Receivers
    • G01S7/4915—Time delay measurement, e.g. operational details for pixel components; Phase measurement
    • 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

Abstract

The application provides a frequency modulation continuous wave laser ranging device, which comprises: a first light source configured to generate invisible detection laser light, the detection laser light being periodically modulated in a preset mode; a second light source configured to generate a visible indication laser for determining a position of the target object and indicating an outgoing path of the detection laser; and the laser transceiver receives the detection laser and the indication laser, the detection laser and the indication laser are output from the laser transceiver in a coaxial beam combining way, and the frequency modulation continuous wave laser ranging device detects the distance of the target object based on the detection laser. According to the application, the invisible detection laser is provided with the visible indication laser, so that the detection laser and the indication laser are coaxially output from the laser receiving and transmitting device, the incidence of the detection laser on the target object is ensured, and the distance of the target object is detected based on the detection laser.

Description

Frequency modulation continuous wave laser range unit
Technical Field
The application relates to the technical field of laser ranging, in particular to a frequency modulation continuous wave laser ranging device.
Background
The laser ranging technique has been widely used in the fields of obstacle detection, distance detection, etc., such as the field of automatic driving, the field of obstacle avoidance of intelligent robots, etc., and the laser ranging device calculates the distance from the laser ranging device to an environmental object by transmitting laser pulses and receiving laser pulse echoes reflected back from the surrounding object, and according to the time delay between the transmitted pulses and the received reflected pulses.
However, the existing laser ranging device has trouble in solving the aim of a target object, and particularly when the exact target object is to be measured, because invisible laser is used in the measurement of the laser ranging device, the target is aimed by naked eyes for re-measurement, and the measurement laser is difficult to aim at the target object, so that the trouble is brought to the measurement.
Disclosure of Invention
The application provides a frequency modulation continuous wave laser ranging device, comprising:
a first light source configured to generate invisible detection laser light, the detection laser light being periodically modulated in a preset mode;
a second light source configured to generate a visible indication laser for determining a position of the target object and indicating an outgoing path of the detection laser; and
a laser transceiver for receiving the detection laser and the indication laser, wherein the detection laser and the indication laser are coaxially combined and output from the laser transceiver,
the frequency modulation continuous wave laser ranging device detects the distance of the target object based on the detection laser.
In some embodiments, the laser transceiving apparatus comprises:
the first beam splitter is configured to split the received detection laser into a detection sub-beam and a local oscillation beam;
the optical path multiplexer at least comprises three ports, wherein a first port receives the detection sub-beam and then outputs the detection sub-beam through a second port, and the second port receives a return detection beam formed based on the detection sub-beam and transmits the return detection beam to a third port; and
and the mixer is configured to receive the local oscillation beam and the return detection beam to form a mixed beam.
In some embodiments, the laser transceiver device further comprises:
and the combiner is arranged on one side of the optical path multiplexer, far away from the first beam splitter, is respectively connected with the second light source and the second port of the optical path multiplexer, and is configured to combine the probe sub-beam and the indication laser beam and then output the combined beam.
In some embodiments, the laser transceiver device further comprises:
and the combiner is arranged at one side of the first beam splitter, far away from the optical path multiplexer, is respectively connected with the second light source and the first light source, and is configured to combine the detection laser and the indication laser and then output the combined detection laser and the indication laser to the first beam splitter.
In some embodiments, the frequency modulated continuous wave laser ranging device further comprises:
and the lens assembly is arranged between the laser receiving and transmitting device and the target object, and is configured to collimate the laser after beam combination and couple the returned detection beam into the laser valve receiving device.
In some embodiments, the frequency modulated continuous wave laser ranging device further comprises:
the balance detector is arranged at one side of the laser transceiver and is configured to receive the mixed light beam to generate a detection electric signal and output the detection electric signal; and
and the acquisition processing device is electrically connected with the balance detector, receives the detection electric signal from the balance detector, processes the detection electric signal and determines the distance of the target object.
In some embodiments, the frequency modulated continuous wave laser ranging device further comprises:
and the amplifier is arranged between the balance detector and the acquisition processing device and is configured to amplify the detection electric signal from the balance detector and transmit the amplified detection electric signal to the acquisition processing device.
In some embodiments, the electrical detection signal is an analog signal,
the acquisition processing device comprises:
the analog-to-digital conversion module is used for receiving the analog signals and converting the analog signals into digital signals; and
and the signal processing module is electrically connected with the analog-to-digital conversion module, receives the digital signal from the analog-to-digital conversion module and processes the digital signal to determine the distance of the detected object.
In some embodiments, the laser transceiver is a laser transceiver chip, the optical multiplexer is a 2×2 coupler or a polarizing beam splitter, and the first beam splitter, the optical multiplexer, the mixer, and the combiner are integrated on the laser transceiver chip.
In some embodiments, at least one of the first light source and the second light source is a solid state laser or a semiconductor laser.
The embodiment of the application has the following technical effects:
according to the frequency modulation continuous wave laser ranging device provided by the embodiment of the application, the invisible detection laser is provided with the visible indication laser, so that the detection laser and the indication laser are coaxially output from the laser receiving and transmitting device, the light-emitting path of the detection laser is accurately indicated by the visible indication laser, the incidence of the detection laser on a target object is ensured, and the distance of the target object is detected based on the detection laser.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application. It is evident that the drawings in the following description are only some embodiments of the present application and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art. In the drawings:
FIG. 1 is a schematic diagram of laser modulation waveforms according to some embodiments of the present application;
FIG. 2 is a schematic diagram of a frequency modulated continuous wave laser ranging apparatus according to some embodiments of the present application;
FIG. 3 is a schematic diagram of a frequency modulated continuous wave laser ranging apparatus according to further embodiments of the present application;
fig. 4 is a schematic diagram of a fm continuous wave laser ranging device according to other embodiments of the application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plurality" generally includes at least two.
It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
It should be understood that although the terms first, second, third, etc. may be used in embodiments of the present application, these should not be limited to these terms. These terms are only used to distinguish one from another. For example, a first may also be referred to as a second, and similarly, a second may also be referred to as a first, without departing from the scope of embodiments of the application.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product or apparatus. Without further limitation, an element defined by the phrase "comprising" does not exclude the presence of other like elements in a commodity or device comprising such element.
In the related art, in order to enable the laser ranging device to accurately detect the target object, especially for the approximate direction of the target object to be measured which is known clearly, when the distance of the target object needs to be measured, the accurate position of the target object needs to be aimed, so that the detection laser can accurately strike the target object.
The embodiment of the application provides a frequency modulation continuous wave laser ranging device, which comprises: a first light source configured to generate invisible detection laser light, the detection laser light being periodically modulated in a preset mode; a second light source configured to generate a visible indication laser for determining a position of the target object and indicating an outgoing path of the detection laser; and the laser receiving and transmitting device is used for receiving the detection laser and the indication laser, the detection laser and the indication laser are output from the laser receiving and transmitting device in a coaxial beam combination way, and the frequency modulation continuous wave laser ranging device is used for detecting the distance of the target object based on the detection laser.
According to the frequency modulation continuous wave laser ranging device provided by the embodiment of the application, the invisible detection laser is provided with the visible indication laser, so that the detection laser and the indication laser are coaxially output from the laser receiving and transmitting device, the light-emitting path of the detection laser is accurately indicated by the visible indication laser, the incidence of the detection laser on a target object is ensured, and the distance of the target object is detected based on the detection laser, so that the debugging complexity of an optical element is reduced.
Alternative embodiments of the present application will be described in detail below with reference to the accompanying drawings.
The embodiment of the application provides a frequency modulation continuous wave laser ranging device. The frequency modulation continuous wave laser ranging device may be a Frequency Modulation Continuous Wave (FMCW) laser radar, where FMCW (Frequency Modulated Continuous Wave) frequency modulation continuous wave, that is, detection laser emitted by a laser light source is modulated to form modulated laser with a periodic rule, for example, modulated into a triangular wave, a sawtooth wave, or the like. The frequency of the modulated emitted light may vary with time, for example, the triangular wave modulation shown in fig. 1, and the implementation represents the emitted signal under the triangular wave modulation, and the dashed line represents the echo signal. The frequency modulated light may include a first half period in which the light frequency increases with time and a second half period in which the light frequency decreases with time. The frequency modulation continuous wave laser ranging device emits the modulated laser, reflects the modulated laser from the surface of the object after a period of time, and receives the modulated laser from the frequency modulation continuous wave laser ranging device.
When the target object is far away from the FMCW lidar, the transmitted signal (solid line), the echo signal (broken line) and the measured beat signal under triangular wave modulation are shown in FIG. 1, and it can be seen that the rising interval beat signal f measured by the balanced detector bu And falling interval beat signal f bd All positive values; at the same time, for the measured rising interval beat signal f bu The research shows that: as shown in FIG. 1, when the target object is relatively close to the FMCW laser radar and the moving speed V of the target object relative to the FMCW laser radar is faster and faster, the rising interval beat signal f is due to the Doppler effect bu Will continuously decrease until0, when the velocity V is faster, the rising interval beat signal f bu And is larger than 0 and becomes larger gradually. The speed and distance of the target object relative to the lidar can be calculated using the following formula,
wherein c is the speed of light (constant), t s Is half of the period of the frequency-modulated wave, f DEV Frequency sweep bandwidth for frequency modulated wave, f bu For the beat signal of the rising interval, f bd For the falling interval beat signal, D is the distance of the target object relative to the laser radar, and V is the speed of the target object relative to the laser radar.
As shown in fig. 2, an embodiment of the present application provides a frequency-modulated continuous wave laser ranging device, where the frequency-modulated continuous wave laser ranging device includes a first light source 101 and a second light source 102, where the first light source 101 is configured to output invisible detection laser, and the detection laser is periodically modulated in a preset mode, for example, modulated into a triangular wave, a sawtooth wave, and the like, and as shown in fig. 1, the triangular wave is shown.
The second light source 102 is configured to generate a visible indication laser, where the visible indication laser is used to determine the position of the target object, and forms a macroscopic light spot after striking the target object, so as to determine whether the target is an object to be detected, where the invisible detection laser is, for example, a laser in a near infrared or far infrared band, and the visible light is, for example, red light, green light, or blue light.
In some embodiments, the invisible detection light is, for example, infrared light with a wavelength of 1064nm, the visible indication laser is, for example, green light with a wavelength of 532nm, and the human eye is most sensitive to the green light of the visible light, which is beneficial for observation. In some embodiments, at least one of the first light source 101 and the second light source employs a solid state laser or a semiconductor laser or the like.
The frequency modulation continuous wave laser ranging device further comprises a laser transceiver 20, and the laser transceiver 20 receives the detection laser and the indication laser. The detection laser and the indication laser are coaxially output from the laser receiving and transmitting device, the indication laser indicates the light emitting path of the detection laser, the incidence of the detection laser on the target object is ensured, and the distance of the target object is detected based on the detection laser. By coaxially outputting the detection laser and the indication laser from the laser receiving and transmitting device, the emergent path of the detection laser is accurately indicated, so that the detection laser can accurately detect the distance of the target object based on the position of the target object determined by the indication laser, and the complexity of debugging the optical element is reduced.
In some embodiments, as shown in fig. 2, for example, the first light source 101 and the second light source 102 may both use semiconductor light sources, so as to reduce the overall size of the fm continuous wave laser ranging device and improve the stability of the optical path.
In some embodiments, as shown in fig. 2, the laser transceiver device 20 includes: the first beam splitter 201 receives the probe beam emitted from the first light source 101. The first beam splitter 201 is configured to split the received probe laser light into a probe sub-beam and a local oscillator beam, and the first beam splitter 201 employs a coupler of 1×2 or 2×2 interface.
Alternatively, the power distribution ratio of the local oscillation beam to the probe sub-beam may be fixed, for example, the power distribution ratio of the local oscillation beam to the probe sub-beam is 3:7, and the power distribution ratio of the local oscillation beam to the probe sub-beam may also be adjustable.
In some embodiments, the first beam splitter 201 includes any of the following alternative applications: directional couplers, asymmetric multimode interferometers, Y-beam splitters, adiabatic beam splitters, thermo-optic switches or electro-optic switches. The selection of any device can be applied according to the power, wavelength and other factors of the laser transmission signals distributed by the optical distribution network, and will not be described in detail.
The laser transceiver 20 further includes an optical multiplexer 202, where the optical multiplexer 202 includes at least three ports, the first port is an input port, the first port receives the probe sub-beam from the first beam splitter 201 and outputs the probe sub-beam through the second port, the second port may be an input port and an output port, a return probe beam formed by reflecting the probe sub-beam by the target object is received by the second port of the optical multiplexer 202, and the return probe beam is transmitted to a third port of the optical multiplexer 202, where the third port is an output port.
The laser transceiver 20 further includes a mixer 204, the mixer 204 being configured to receive the local oscillator beam and the return probe beam to form a mixed beam for subsequent probing.
In some embodiments, the laser transceiver is a laser transceiver chip, the optical multiplexer 202 is a 2×2 coupler or a polarization beam splitter, the probe sub-beam is polarized light, the first beam splitter 201, the optical multiplexer 202 and the mixer 204 are integrated in the laser transceiver chip, and the performance of the laser ranging device is more stable and the volume is more compact.
As described above, the optical multiplexer 202 is, for example, a polarization beam splitter, and includes at least three ports, where the first port of the optical multiplexer 202 receives the probe sub-beam and transmits the probe sub-beam to the second port, and the second port of the optical multiplexer 202 receives the return probe beam formed by reflecting the probe sub-beam by the target object 40 and transmits the return probe beam to the third port, where the optical properties of the probe sub-beam are different from those of the return probe beam, so that the optical multiplexer 202 can transmit only the probe sub-beam having the mode one, for example, the polarized light having the TE mode, from the first port of the optical multiplexer 202 to the second port of the optical multiplexer 202, and the optical multiplexer 202 can transmit only the return probe beam having the mode two, for example, the polarized light having the TM mode, from the second port of the optical multiplexer 202 to the third port of the optical multiplexer 202, and cannot transmit to the first port of the optical multiplexer 202.
In some embodiments, the laser transceiver is in a non-integrated chip structure, the optical multiplexer 202 may use a circulator, the probe sub-beam is unpolarized light, and the unpolarized light is used for detection, thereby reducing the requirements on the performance of the light source and each device.
In some embodiments, as shown in fig. 2, the laser transceiver 20 further includes a combiner 203, where the combiner 203 is disposed at an output end of the laser transceiver 20, and the combiner 203 is connected to the second light source 102 and the second port of the optical path multiplexer 202, and the combiner 203 is configured to combine and output the probe sub-beam and the indication laser beam. The probe sub-beam and the indication laser are coaxially output from the laser transceiver 20 after being combined by the combiner 203, so that the indication laser indicated position is recorded as the target position, and the distance between the probe laser and the target object can be accurately detected based on the position of the target object determined by the indication laser, and compared with the optical path design adopting parallel emergent probe beams and indication beams in the related art, the complexity of debugging an optical element is greatly reduced. In some embodiments, when the laser transceiver 20 is a laser transceiver chip, the combiner may also be integrated on the laser transceiver chip.
In some embodiments, as shown in fig. 2, a mixer 204 in the laser transceiver 20 is optically connected to the first beam splitter 201, and receives the local oscillation beam; a mixer 204 is optically connected to the third port of the optical multiplexer 202 for receiving the return probe beam, the mixer 204 performing a beat operation on the return probe beam and the local oscillator beam to output a mixed beam, also referred to as a beat beam, which may be a directional coupler or a multimode interferometer.
In some embodiments, the fm continuous wave laser ranging device further includes a balance detector 50, where the balance detector 50 is disposed on one side of the laser transceiver 20, and the balance detector 50 receives and detects the mixed beam, generates a detection electric signal, and outputs the detection electric signal.
In some embodiments, as shown in fig. 3, the fm continuous wave laser ranging apparatus further includes an acquisition and processing device 70, where the acquisition and processing device 70 receives the detected electrical signal from the balance detector 50, and acquires and processes the detected electrical signal to determine the distance of the detected object.
In some embodiments, as shown in fig. 1, the acquisition processing device 70 includes an analog-to-digital conversion module 71 and a signal processing module 72, where the analog-to-digital conversion module 71 is, for example, an analog-to-digital converter, which receives the detected electrical signal from the balance detector 50, and the detected electrical signal is an analog signal, and the analog-to-digital conversion module 71 converts the detected electrical signal that is the analog signal into a digital signal, and the signal processing module 72 is connected to the analog-to-digital conversion module 71, receives the digital signal from the analog-to-digital conversion module 71, and processes the digital signal to determine the distance of the detected object. In some embodiments, the signal processing module 72 is, for example, a Field Programmable Gate Array (FPGA), digital Signal Processing (DSP), or the like.
In some embodiments, an amplifier 60 is disposed between the balance detector 50 and the acquisition and processing device 70, and is used for amplifying the detection electric signal output by the balance detector 50 and transmitting the detection electric signal to the acquisition and processing device 70.
In some embodiments, the laser transceiver further includes a lens assembly 30, where the lens assembly 30 is disposed between the laser transceiver 20 and the target object 40, and is configured to collimate the laser beam emitted from the laser transceiver and combined by the probe sub-beam and the indication laser beam, and generate a reflected laser beam after the combined laser beam irradiates the target object 40, the reflected laser beam includes a return probe beam, and the lens assembly 30 may further couple the reflected laser beam including the return probe beam into the laser transceiver 20. Because the invisible detection laser and the visible indication laser are transmitted coaxially, the requirement on adjustment of the lens assembly is reduced, and the laser ranging device is easier to compare with a target object.
As shown in fig. 2, the detection principle of the fm continuous wave laser ranging device is as follows: the first light source 101 emits invisible detection laser, the detection laser is split into a detection sub-beam and a local oscillation beam by the first beam splitter 201, the detection sub-beam is combined with the visible indication laser emitted by the second light source 102 in the combiner 203 after passing through the optical path multiplexer 202, the combined laser is collimated by the lens component 30 and is incident on the target object 40 to generate reflected laser, the reflected laser also comprises visible laser and invisible laser, the invisible laser is formed by reflecting the detection sub-beam on the target object 40, and the reflected laser comprises returned detection beam. The visible laser light is reflected by the indicating laser light on the target object 40. The reflected laser is coupled into the laser transceiver 20 through the lens assembly 30, and is split into a return probe beam and a visible laser through the combiner 203, the return probe beam enters the optical multiplexer from the second port of the optical multiplexer 202, the return probe beam is output from the third port of the optical multiplexer 202, the return probe beam and the local oscillator beam enter the mixer 204 to perform mixing to generate mixed laser, and the balance detector 50 receives and detects the mixed laser to generate a detection electric signal. The acquisition and processing device 70 receives the detection electric signal from the balance detector 50, acquires and processes the detection electric signal, and determines the distance of the detected object.
In other embodiments, as shown in fig. 3, in comparison with the embodiment shown in fig. 2, the combiner 203 is disposed at the input end of the laser transceiver 20, on the side of the first beam splitter 201 away from the optical multiplexer 202. The input end of the combiner 203 is connected to the second light source 102 and the first light source 101, respectively, and the combiner 203 is configured to combine the detection laser and the indication laser and output the combined detection laser and the combined indication laser to the first beam splitter 201. The laser light received by the first beam splitter 201 is a combined laser light of the detection laser light and the indication laser light. The first beam splitter 201 splits the received laser light into two output beams, each of which includes both visible and invisible light.
As shown in fig. 3, the detection principle of the fm continuous wave laser ranging device is as follows: the first light source 101 emits invisible detection laser, the detection laser in the combined laser is combined with the visible indication laser emitted by the second light source 102 in the combiner 203, the detection laser in the combined laser is split into a detection sub-beam and a local oscillation beam by the first beam splitter 201, the indication laser in the combined laser is split, the combined laser composed of the detection sub-beam and one path of split indication laser is output by the laser transceiver 20 by the optical path multiplexer 202, the combined laser is collimated by the lens component 30 and is incident on the target object 40 to generate reflected laser, the reflected laser also comprises visible laser and invisible laser, the invisible laser is formed by reflecting the detection sub-beam on the target object 40, and the reflected laser comprises a returned detection beam. The visible laser light is reflected by the indicating laser light on the target object 40. The reflected laser beam is coupled into the laser transceiver 20 after passing through the lens assembly 30, the return probe beam enters the optical multiplexer from the second port of the optical multiplexer 202, the return probe beam is output by the third port of the optical multiplexer 202, the return probe beam and the local oscillator beam enter the mixer 204 to perform mixing to generate mixed laser, and the balance detector 50 receives and detects the mixed laser to generate a detection electric signal. The acquisition and processing device 70 receives the detection electric signal from the balance detector 50, acquires and processes the detection electric signal, and determines the distance of the detected object.
Based on the embodiment of fig. 2, the present application further provides an embodiment, as shown in fig. 4, in which the same structure has the same technical effect, and the present application is not repeated, and in this embodiment, the laser ranging device further includes a beam splitter 120, a reference light path 90, a feedback circuit 100, and a driving device 110.
The first light source 101 is configured to emit chirped laser light, which is driven, for example, with a driving circuit that outputs a frequency-modulated driving signal, and the first light source 101 receives the frequency-modulated driving signal to emit the chirped laser light. The first light source 101 is, for example, a solid-state laser, a semiconductor laser, or the like, and specifically may be a distributed feedback laser (DFB), a Vertical Cavity Surface Emitting Laser (VCSEL), an external cavity laser, or the like. The beam splitter 120 receives the chirped laser and splits the chirped laser into a detection laser and a reference chirped laser, where the detection laser detects the target object 40 through the laser transceiver 20, and the reference chirped laser feedback-controls the first light source 101 through the reference light path 90 and the feedback circuit 100. The beam splitter 120 is, for example, a 1×2 beam splitter, and splits the chirped laser beam into two identical laser beams, that is, the probe laser and the reference chirped laser beams, with identical wavelength, phase and frequency modulation.
The reference optical path 90 receives the reference fm laser and delays the reference fm laser to output a reference beat signal, such as a frequency signal. The feedback circuit 100 receives the reference beat frequency signal and outputs a feedback signal, where the feedback signal is configured to adjust the output of the first light source 101 in real time, so as to ensure the frequency modulation linearity of the linear frequency sweep of the first light source and the beat frequency stability of the frequency modulation continuous wave laser ranging device.
The linear frequency modulation laser output by the first light source is monitored in real time through the reference light path channel, a feedback signal for adjusting the first light source in real time is determined through the feedback circuit, the feedback signal is configured to adjust the output of the first light source in real time, and the frequency modulation linearity of the linear frequency sweep of the first light source and the beat frequency stability of the frequency modulation continuous wave laser ranging device are guaranteed.
In some embodiments, as shown in fig. 4, the reference optical path channel 90 includes a second beam splitter 91, a delay device 92, a reference mixer 93, and a reference detection device 94. The second beam splitter 91 receives the reference fm laser light and splits the beam into a first reference fm laser light and a second reference fm laser light. The second beam splitter 91 is, for example, a 1×2 beam splitter, and splits the reference fm laser beam into two identical reference fm laser beams, that is, the first reference fm laser beam and the second reference fm laser beam have identical wavelength, phase, and frequency.
The delay device 92 receives the first reference fm laser to transmit the first reference fm laser for a certain length and delay the first reference fm laser for a predetermined time. The reference mixer 93 receives the delayed first reference fm laser and the second reference fm laser, and mixes the delayed first reference fm laser and the second reference fm laser to output a feedback mixed beam. The reference detecting means 94 receives the feedback mixed beam and performs a beat frequency operation to output the reference beat frequency signal, and the reference detecting means 94 outputs the reference beat frequency signal as an electrical signal. The reference beat frequency signal is, for example, a frequency signal, and because the linearity of the chirped laser output by the frequency-modulated continuous wave laser ranging device is biased, noise exists in the actually obtained reference beat frequency signal compared with an ideal beat frequency signal, and the beat frequency stability of the frequency-modulated continuous wave laser ranging device is affected. In some embodiments, the reference mixer 93 is, for example, a 2x2 coupler, a 90 degree mixer, and the reference detection device 94 is, for example, a photodetector, etc.
In some embodiments, as shown in fig. 4, the feedback circuit 100 includes: a reference frequency source 101, a phase detector 102 and a negative feedback unit 103. The reference frequency source 101 is configured to output a reference frequency signal, where the reference frequency source 101 adopts a circuit structure, and the generated reference frequency signal may be a specific frequency signal that is accurate and constant, and the reference frequency signal is, for example, the ideal reference beat frequency signal, and has specific frequency and amplitude characteristics that are accurate and constant. The phase discriminator 102 receives the reference frequency signal and the reference beat frequency signal, performs phase discrimination operation on the reference frequency signal and the reference beat frequency signal, outputs a signal indicating a phase difference, and the negative feedback unit 103 outputs the feedback signal according to the phase difference signal. The phase demodulation operation can extract noise existing in the actually acquired reference beat signal, and further obtain a feedback signal according to the phase difference signal to adjust the output of the first light source 101 in real time.
In some embodiments, the reference frequency signal has a stable frequency f r I.e. the desired frequency, said delay means 92 comprising an optical fiber/waveguide having a predetermined length L, where "/" indicates and/or i.e. the delay means 92 may employ either an optical fiber, a waveguide, or both an optical fiber and a waveguide, said stable frequency f r The following formula is satisfied:
wherein t is c F is one half of the sweep measurement period c For swept bandwidth, L represents a predetermined length of the fiber or waveguide, C 0 Indicating the speed of light and n indicating the refractive index of the fiber or waveguide.
That is, after the length L of the optical fiber/waveguide serving as the delay means is determined, the frequency f is stabilized r I.e. to correspondingly determine, based on which the reference frequency source 101 is designed to output a stable frequency f that is stable r 。
In some embodiments, as shown in fig. 4, the fm continuous wave laser ranging device further includes a drive device 110. The driving device 110 is electrically connected to the first light source 101 and the feedback circuit 100, and is configured to receive the feedback signal and output a feedback driving signal to the first light source 101, so as to ensure the frequency modulation linearity of the linear sweep of the first light source and the beat frequency stability of the frequency modulation continuous wave laser ranging device.
In some embodiments, the driving device 110 includes a driving unit 111 and a superimposing unit 112, where the driving unit 111 generates a frequency modulation driving signal based on the frequency modulation amplitude and slope. The superimposing unit 112 receives the frequency modulation driving signal and the feedback signal, and superimposes the two signals to generate and output the feedback driving signal.
The first light source is driven to output the linear frequency modulation laser through the frequency modulation driving signal, the linear frequency modulation laser output by the first light source is monitored in real time through the reference light path channel, the feedback signal for adjusting the first light source in real time is determined through the feedback circuit, the feedback signal is overlapped with the frequency modulation driving signal to generate the feedback driving signal, the feedback driving signal is used for adjusting the output of the first light source in real time, and the frequency modulation linearity of the linear frequency sweep of the first light source and the beat frequency stability of the frequency modulation continuous wave laser ranging device are guaranteed.
Finally, it should be noted that: in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A frequency modulated continuous wave laser ranging device, comprising:
a first light source configured to generate invisible detection laser light, the detection laser light being periodically modulated in a preset mode;
a second light source configured to generate a visible indication laser for determining a position of the target object and indicating an outgoing path of the detection laser; and
a laser transceiver for receiving the detection laser and the indication laser, wherein the detection laser and the indication laser are coaxially combined and output from the laser transceiver,
the frequency modulation continuous wave laser ranging device detects the distance of the target object based on the detection laser.
2. The fm continuous wave laser ranging device as claimed in claim 1, wherein the laser transceiver comprises:
the first beam splitter is configured to split the received detection laser into a detection sub-beam and a local oscillation beam;
the optical path multiplexer at least comprises three ports, wherein a first port receives the detection sub-beam and then outputs the detection sub-beam through a second port, and the second port receives a return detection beam formed based on the detection sub-beam and transmits the return detection beam to a third port; and
and the mixer is configured to receive the local oscillation beam and the return detection beam to form a mixed beam.
3. The fm continuous wave laser ranging device as claimed in claim 2, wherein the laser transceiver further comprises:
and the combiner is arranged on one side of the optical path multiplexer, far away from the first beam splitter, is respectively connected with the second light source and the second port of the optical path multiplexer, and is configured to combine the probe sub-beam and the indication laser beam and then output the combined beam.
4. The fm continuous wave laser ranging device as claimed in claim 2, wherein the laser transceiver further comprises:
and the combiner is arranged at one side of the first beam splitter, far away from the optical path multiplexer, is respectively connected with the second light source and the first light source, and is configured to combine the detection laser and the indication laser and then output the combined detection laser and the indication laser to the first beam splitter.
5. The fm continuous wave laser ranging device as claimed in claim 3 or 4, further comprising:
and the lens assembly is arranged between the laser receiving and transmitting device and the target object, and is configured to collimate the laser after beam combination and couple the returned detection beam into the laser valve receiving device.
6. The fm continuous wave laser ranging device as claimed in claim 3 or 4, further comprising:
the balance detector is arranged at one side of the laser transceiver and is configured to receive the mixed light beam to generate a detection electric signal and output the detection electric signal; and
and the acquisition processing device is electrically connected with the balance detector, receives the detection electric signal from the balance detector, processes the detection electric signal and determines the distance of the target object.
7. The fm continuous wave laser ranging device as claimed in claim 6, further comprising:
and the amplifier is arranged between the balance detector and the acquisition processing device and is configured to amplify the detection electric signal from the balance detector and transmit the amplified detection electric signal to the acquisition processing device.
8. The apparatus of claim 6, wherein the detected electrical signal is an analog signal,
the acquisition processing device comprises:
the analog-to-digital conversion module is used for receiving the analog signals and converting the analog signals into digital signals; and
and the signal processing module is electrically connected with the analog-to-digital conversion module, receives the digital signal from the analog-to-digital conversion module and processes the digital signal to determine the distance of the detected object.
9. The fm continuous wave laser ranging device of claim 3 or 4, wherein the laser transceiver is a laser transceiver chip, the optical multiplexer is a 2x2 coupler or a polarizing beam splitter, and the first beam splitter, optical multiplexer, mixer, and combiner are integrated on the laser transceiver chip.
10. The apparatus of claim 3 or 4, wherein,
at least one of the first light source and the second light source is a solid state laser or a semiconductor laser.
CN202310896482.2A 2023-07-20 2023-07-20 Frequency modulation continuous wave laser range unit Pending CN116626696A (en)

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