WO2020142941A1 - 一种光发射方法、装置及扫描系统 - Google Patents

一种光发射方法、装置及扫描系统 Download PDF

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Publication number
WO2020142941A1
WO2020142941A1 PCT/CN2019/071024 CN2019071024W WO2020142941A1 WO 2020142941 A1 WO2020142941 A1 WO 2020142941A1 CN 2019071024 W CN2019071024 W CN 2019071024W WO 2020142941 A1 WO2020142941 A1 WO 2020142941A1
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Prior art keywords
pulse sequence
optical pulse
exit
light
optical
Prior art date
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Ceased
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PCT/CN2019/071024
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English (en)
French (fr)
Inventor
颜悦
董帅
龙承辉
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SZ DJI Technology Co Ltd
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SZ DJI Technology Co Ltd
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Filing date
Publication date
Application filed by SZ DJI Technology Co Ltd filed Critical SZ DJI Technology Co Ltd
Priority to CN201980005456.8A priority Critical patent/CN111670384A/zh
Priority to PCT/CN2019/071024 priority patent/WO2020142941A1/zh
Publication of WO2020142941A1 publication Critical patent/WO2020142941A1/zh
Priority to US17/372,023 priority patent/US20210333370A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • 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
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • 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
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G01S17/26—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
    • 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
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse 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
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/484—Transmitters

Definitions

  • the invention relates to the technical field of optical pulses, in particular to a control method of pulse frequency.
  • Lidar is a perception system for the outside world, which can obtain the spatial distance information in the direction of emission.
  • the principle is to actively emit a laser pulse signal to the outside, detect the reflected pulse signal, and judge the distance of the measured object according to the time difference between transmission and reception.
  • the wavelength of the laser light source is in the sensitive spectrum of the human eye. When the laser light pulse signal exceeds the safety regulations when the human eye stays, it will hurt the human eye, and the inappropriate scanning speed of the scanning system will cause the optical pulse to stay in the human eye for too long. Will cause damage to human eyes or can not obtain a higher scanning density.
  • Embodiments of the present invention provide a light emission method, device, and scanning system to solve the problem that human eye safety cannot be guaranteed during the scanning process.
  • an embodiment of the present invention provides a light emission method.
  • the method includes at least:
  • the exit frequency and/or exit power of the light pulse sequence is controlled according to the scanning speed of the light pulse sequence.
  • an embodiment of the present invention provides a light emitting device, the device including:
  • Optical pulse generation unit used to emit optical pulse sequence
  • At least one optical element for changing the propagation direction of the light pulse sequence to scan the surrounding environment
  • the control unit is configured to control the output frequency and/or output power of the optical pulse sequence according to the scanning speed of the optical pulse sequence.
  • an embodiment of the present invention provides a laser scanning system, the system including the light emitting device according to the second aspect.
  • the light emission method, device and scanning system of the embodiments of the present invention can adjust the frequency and/or power of the light pulse according to the scanning speed, so that a high scanning point cloud density can be obtained under the premise of satisfying human eye laser safety.
  • FIG. 1 is a schematic flowchart of a light emission method according to an embodiment of the present invention
  • FIG. 2 is a schematic structural block diagram of a distance measuring device according to an embodiment of the present invention.
  • FIG. 3 is a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.
  • the human eye has different transmittance and absorption characteristics for different wavelengths of light radiation.
  • the 400-1400nm band has a high crystal transmittance and belongs to the retinal damage area of the human eye.
  • the laser scanning system can generate visible or invisible high-intensity, high-direction light pulse sequences with wavelengths in the range of 400-1000nm, and extremely low light pulse energy irradiation can cause damage to the human eye.
  • FIG. 1 is a schematic flowchart of a light emission method according to an embodiment of the present invention. As shown in FIG. 1, the method 100 includes:
  • step S110 the outgoing light pulse sequence
  • Step S120 changing the propagation direction of the light pulse sequence to scan the surrounding environment
  • Step 130 Control the output frequency and/or output power of the optical pulse sequence according to the scanning speed of the optical pulse sequence.
  • the scanning speed of the optical pulse sequence determines the residence time of the optical pulse in the human eye, and the exit frequency and/or output power of the optical pulse sequence determines the number of laser pulses staying in the human eye.
  • the output frequency and/or output power of the light pulse sequence can be increased within a reasonable range to obtain a higher scanning point cloud density and improve the scanning accuracy; while the light pulse
  • the output frequency and/or output power of the optical pulse sequence can be reduced within a reasonable range to ensure human eye safety.
  • the method further includes:
  • the output frequency and/or the output power of the optical pulse sequence is changed according to the change in the scanning speed of the optical pulse sequence.
  • the output frequency and/or the output power of the optical pulse sequence can be adjusted according to the change of the scanning speed of the optical pulse sequence to take into account human eye safety and Scanned point cloud density.
  • the scanning speed of the optical pulse sequence becomes faster, the dwell time of the laser in the human eye becomes shorter, then the output frequency and/or output power of the optical pulse sequence can be increased within a certain range to ensure the safety of the human eye of the laser Realize the improvement of point cloud density.
  • the scanning speed of the optical pulse sequence becomes slower, the residence time of the laser in the human eye becomes longer. At this time, the emission frequency and/or the output power of the optical pulse sequence can be reduced within a certain change range, so as to achieve laser eye safety.
  • the output frequency and/or the output power of the optical pulse sequence varies according to the scanning system.
  • the output frequency and/or the output power of the optical pulse sequence may be linearly changed or non-linearly changed, such as stepwise change or exponential change.
  • the changing the output frequency and/or output power of the optical pulse sequence includes:
  • the changing the output frequency and/or output power of the optical pulse sequence includes:
  • the frequency and/or power of the laser pulse emitted by the radar is reduced.
  • the output frequency and/or output power of the optical pulse sequence varies stepwise with the scanning speed of the optical pulse sequence. Because the scanning speed of the optical pulse sequence within a certain range makes the time of the optical pulse staying in the human eye not much different, the scanning speed of the optical pulse sequence can be divided into multiple stages, and the corresponding optical pulse sequence between each stage The exit frequency and/or exit power are different, and the exit frequency and/or exit power of the corresponding optical pulse sequence within each stage are the same; this can reduce the control difficulty, improve stability, and avoid the exit frequency and/or exit of the optical pulse sequence Or the output power frequently changes, which affects the stability of scanning.
  • controlling the exit frequency and/or exit power of the optical pulse sequence includes:
  • the numerical value in the first range is greater than the numerical value in the second range, and the first exit frequency and/or exit power is greater than the second exit frequency and/or exit power.
  • the method further includes:
  • the power component of the optical pulse generating unit that emits the optical pulse sequence fails and the rotational speed of the power component is below a certain lower threshold, the output frequency and/or output power of the optical pulse sequence still cannot be satisfied Human eye laser safety requirements, because the factor that restricts laser safety at this time is the energy of the single pulse of the lidar, you can take the strategy of directly letting the laser stop emitting to meet the human eye laser safety requirements.
  • the lower limit threshold has different values according to different scanning systems.
  • the changing the propagation direction of the optical pulse sequence includes: changing the propagation direction of the optical pulse sequence by at least one moving optical element.
  • the changing the propagation direction of the light pulse sequence includes: changing the propagation direction of the light pulse sequence by at least one rotating light refraction element, wherein the light refraction element has opposite, non-parallel light exit surfaces And into the light.
  • the at least one optical element for example, a lens, a mirror, a prism, a grating, an optical phased array (Optical Phased Array), or any combination of the above optical elements.
  • the method further comprises: determining the scanning speed of the light pulse sequence according to the moving speed of the at least one moving optical element.
  • the movement speed of the optical element is positively correlated with the scanning speed of the optical pulse sequence.
  • the method further includes: prompting the user when the scanning speed of the light pulse sequence is lower than a predetermined minimum rotation speed.
  • the scanning speed of the optical pulse sequence when the scanning speed of the optical pulse sequence is lower than the predetermined minimum rotation speed, it indicates that the scanning process is abnormal, and the user may be prompted to have an abnormality in the scanning process, which is convenient for the user to troubleshoot in time.
  • the method further includes:
  • the position of the object is determined according to the received light pulse signal.
  • a light emission method includes:
  • the light pulse sequence passes through at least one optical element and changes the propagation direction of the light pulse sequence to scan the surrounding environment;
  • Detecting the scanning speed of the optical pulse sequence if the scanning speed of the optical pulse sequence is within a predetermined range, detecting a change in the scanning speed of the optical pulse sequence;
  • the scanning speed of the optical pulse sequence changes from the first range to the second range, the speed of the first range is less than the speed of the second range; then control the output frequency and/or output power of the optical pulse sequence from The first exit frequency and/or exit power is increased to the second exit frequency and/or exit power; wherein the speeds in the first range are all less than the speeds in the second range, indicating that the scanning speed of the optical pulse sequence increases, the light
  • the output frequency and/or output power of the optical pulse sequence can be increased to obtain a greater point cloud density
  • the power component of the light pulse generating unit that drives the light pulse sequence fails, and the light pulse sequence can be stopped immediately. In order to avoid the problem of eye damage caused by too low speed.
  • an embodiment of the present invention provides a light emitting device, the device including:
  • Optical pulse generation unit used to emit optical pulse sequence
  • At least one optical element for changing the propagation direction of the light pulse sequence to scan the surrounding environment
  • the control unit is configured to control the output frequency and/or output power of the optical pulse sequence according to the scanning speed of the optical pulse sequence.
  • At least one optical element includes at least one rotating light refracting element, the light refracting element having opposite, non-parallel light exit surfaces and light incident surfaces.
  • control unit also determines the scanning speed of the light pulse sequence according to the moving speed of the at least one moving optical element.
  • the light emitting device further includes:
  • a detection unit configured to detect the movement speed of the optical element
  • the control unit is also used to determine whether the speed of rotation of the optical element is within a predetermined range, if the speed of movement of the optical element is within the predetermined range, then calculate the change in the speed of movement of the optical element, and according to the optical The change in the movement speed of the element controls the exit frequency and/or exit power of the optical pulse sequence.
  • control unit is also used to:
  • the output frequency and/or the output power of the optical pulse sequence at the first moment is controlled to be less than the second moment The output frequency and/or output power of the optical pulse sequence.
  • control unit is further configured to control the exit frequency and/or exit power of the optical pulse sequence to change stepwise with the movement speed of the optical element.
  • control unit is further configured to: when the movement speed of the optical element is lower than a predetermined minimum rotation speed, control the optical pulse generation unit to stop emitting the optical pulse sequence.
  • the light emitting device further includes:
  • the prompting unit is used for sending out a prompting signal when the movement speed of the optical element is lower than a predetermined minimum rotation speed.
  • the light emitting device further includes:
  • the receiving unit is used to receive the light pulse signal reflected by the object
  • the control unit is also used to determine the position of the object according to the received light pulse signal.
  • an embodiment of the present invention provides a laser scanning system, the system including the light emitting device according to the second aspect.
  • the light emission method, device and scanning system may be applied to a distance measuring device, and the distance measuring device may be an electronic device such as a laser radar or a laser distance measuring device.
  • the distance measuring device is used to sense external environment information, for example, distance information, azimuth information, reflection intensity information, speed information, etc. of the environmental target.
  • the distance measuring device can detect the distance between the detecting object and the distance measuring device by measuring the time of light propagation between the distance measuring device and the detection object, that is, Time-of-Flight (TOF).
  • TOF Time-of-Flight
  • the distance measuring device may also detect the distance between the detected object and the distance measuring device through other techniques, such as a distance measuring method based on phase shift measurement, or a distance measuring method based on frequency shift measurement. There are no restrictions.
  • the distance measuring device 200 may include a transmitting circuit 210, a receiving circuit 220, a sampling circuit 230 and an arithmetic circuit 240.
  • the transmission circuit 210 may transmit a sequence of light pulses (for example, a sequence of laser pulses).
  • the receiving circuit 220 can receive the optical pulse sequence reflected by the detected object, and photoelectrically convert the optical pulse sequence to obtain an electrical signal, which can be output to the sampling circuit 230 after processing the electrical signal.
  • the sampling circuit 230 may sample the electrical signal to obtain the sampling result.
  • the arithmetic circuit 240 may determine the distance between the distance measuring device 200 and the detected object based on the sampling result of the sampling circuit 230.
  • the distance measuring device 200 may further include a control circuit 250, which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • a control circuit 250 which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • the distance measuring device shown in FIG. 2 includes a transmitting circuit, a receiving circuit, a sampling circuit, and an arithmetic circuit for emitting a beam of light for detection
  • the embodiments of the present application are not limited thereto, and the transmitting circuit
  • the number of any one of the receiving circuit, the sampling circuit, and the arithmetic circuit may also be at least two, for emitting at least two light beams in the same direction or respectively in different directions; wherein, the at least two light paths may be simultaneously
  • the shot may be shot at different times.
  • the light-emitting chips in the at least two emission circuits are packaged in the same module.
  • each emitting circuit includes a laser emitting chip, and the die in the laser emitting chips in the at least two emitting circuits are packaged together and housed in the same packaging space.
  • the distance measuring device 200 may further include a scanning module 260 for changing the propagation direction of at least one laser pulse sequence emitted from the transmitting circuit.
  • the module including the transmitting circuit 210, the receiving circuit 220, the sampling circuit 230, and the arithmetic circuit 240, or the module including the transmitting circuit 210, the receiving circuit 220, the sampling circuit 230, the arithmetic circuit 240, and the control circuit 250 may be called a measurement A distance module, the distance measuring module may be independent of other modules, for example, the scanning module 260.
  • a coaxial optical path may be used in the distance measuring device, that is, the light beam emitted by the distance measuring device and the reflected light beam share at least part of the optical path in the distance measuring device.
  • the distance measuring device may also adopt an off-axis optical path, that is, the light beam emitted from the distance measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance measuring device.
  • FIG. 3 shows a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.
  • the distance measuring device 300 includes a distance measuring module 310.
  • the distance measuring module 310 includes a transmitter 303 (which may include the above-mentioned transmitting circuit), a collimating element 304, and a detector 305 (which may include the above-mentioned receiving circuit, sampling circuit, and arithmetic circuit) and Optical path changing element 306.
  • the ranging module 310 is used to emit a light beam, and receive back light, and convert the back light into an electrical signal.
  • the transmitter 303 may be used to transmit a sequence of optical pulses.
  • the transmitter 303 may emit a sequence of laser pulses.
  • the laser beam emitted by the transmitter 303 is a narrow-bandwidth beam with a wavelength outside the visible light range.
  • the collimating element 304 is disposed on the exit optical path of the emitter, and is used to collimate the light beam emitted from the emitter 303, and collimate the light beam emitted from the emitter 303 into parallel light to the scanning module.
  • the collimating element is also used to converge at least a part of the return light reflected by the detection object.
  • the collimating element 304 may be a collimating lens or other element capable of collimating the light beam.
  • the optical path changing element 306 is used to combine the transmitting optical path and the receiving optical path in the distance measuring device before the collimating element 304, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path More compact.
  • the emitter 303 and the detector 305 may respectively use respective collimating elements, and the optical path changing element 306 is disposed on the optical path behind the collimating element.
  • the light path changing element can use a small area mirror to The transmitting optical path and the receiving optical path are combined.
  • the light path changing element may also use a reflector with a through hole, where the through hole is used to transmit the outgoing light of the emitter 303, and the reflector is used to reflect the return light to the detector 305. In this way, it is possible to reduce the blocking of the return light by the support of the small mirror in the case of using the small mirror.
  • the optical path changing element is offset from the optical axis of the collimating element 304. In some other implementations, the optical path changing element may also be located on the optical axis of the collimating element 304.
  • the distance measuring device 300 further includes a scanning module 302.
  • the scanning module 302 is placed on the exit optical path of the distance measuring module 310.
  • the scanning module 302 is used to change the transmission direction of the collimated light beam 319 emitted through the collimating element 304 and project it to the external environment, and project the return light to the collimating element 304 .
  • the returned light is converged on the detector 305 via the collimating element 304.
  • the scanning module 302 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the light beam.
  • the scanning module 302 includes a lens, a mirror, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array (Optical Phased Array), or any combination of the above optical elements.
  • at least part of the optical element is moving, for example, the at least part of the optical element is driven to move by a driving module, and the moving optical element can reflect, refract or diffract the light beam to different directions at different times.
  • multiple optical elements of the scanning module 302 may rotate or vibrate about a common axis 309, and each rotating or vibrating optical element is used to continuously change the direction of propagation of the incident light beam.
  • the multiple optical elements of the scanning module 302 may rotate at different rotation speeds, or vibrate at different speeds.
  • at least part of the optical elements of the scanning module 302 can rotate at substantially the same rotational speed.
  • the multiple optical elements of the scanning module may also rotate around different axes.
  • the multiple optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which is not limited herein.
  • the scanning module 302 includes a first optical element 314 and a drive 316 connected to the first optical element 314.
  • the drive 316 is used to drive the first optical element 314 to rotate about a rotation axis 309 to change the first optical element 314 Collimate the direction of beam 319.
  • the first optical element 314 projects the collimated light beam 319 to different directions.
  • the angle between the direction of the collimated light beam 319 after the first optical element changes and the rotation axis 309 changes as the first optical element 314 rotates.
  • the first optical element 314 includes a pair of opposing non-parallel surfaces through which the collimated light beam 319 passes.
  • the first optical element 314 includes a prism whose thickness varies along at least one radial direction.
  • the first optical element 314 includes a wedge angle prism, which aligns the collimated light beam 319 for refraction.
  • the scanning module 302 further includes a second optical element 315 that rotates about a rotation axis 303.
  • the rotation speed of the second optical element 315 is different from the rotation speed of the first optical element 314.
  • the second optical element 315 is used to change the direction of the light beam projected by the first optical element 314.
  • the second optical element 315 is connected to another driver 317, and the driver 317 drives the second optical element 315 to rotate.
  • the first optical element 314 and the second optical element 315 may be driven by the same or different drivers, so that the rotation speed and/or rotation of the first optical element 314 and the second optical element 315 are different, thereby projecting the collimated light beam 319 to the outside space Different directions can scan a larger spatial range.
  • the controller 318 controls the drivers 316 and 317 to drive the first optical element 314 and the second optical element 315, respectively.
  • the rotation speeds of the first optical element 314 and the second optical element 315 may be determined according to the area and pattern expected to be scanned in practical applications.
  • Drives 316 and 317 may include motors or other drives.
  • the second optical element 315 includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 315 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 315 includes a wedge angle prism.
  • the scanning module 302 further includes a third optical element (not shown) and a driver for driving the third optical element to move.
  • the third optical element includes a pair of opposed non-parallel surfaces through which the light beam passes.
  • the third optical element includes a prism whose thickness varies along at least one radial direction.
  • the third optical element includes a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or turns.
  • each optical element in the scanning module 302 can project the light into different directions, such as the directions of the light 311 and 313, so as to scan the space around the distance measuring device 300.
  • the light 311 projected by the scanning module 302 hits the object 301 to be detected, a part of the light object 301 is reflected to the distance measuring device 300 in the direction opposite to the projected light 311.
  • the returned light 312 reflected by the detected object 301 passes through the scanning module 302 and enters the collimating element 304.
  • the detector 305 is placed on the same side of the collimating element 304 as the emitter 303.
  • the detector 305 is used to convert at least part of the returned light passing through the collimating element 304 into an electrical signal.
  • each optical element is coated with an antireflection coating.
  • the thickness of the antireflection film is equal to or close to the wavelength of the light beam emitted by the emitter 103, which can increase the intensity of the transmitted light beam.
  • a filter layer is plated on the surface of an element on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path to transmit at least the wavelength band of the beam emitted by the transmitter, Reflect other bands to reduce the noise caused by ambient light to the receiver.
  • the transmitter 303 may include a laser diode through which laser pulses in the order of nanoseconds are emitted.
  • the laser pulse receiving time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this way, the distance measuring device 300 can use the pulse reception time information and the pulse emission time information to calculate the TOF, thereby determining the distance between the detected object 301 and the distance measuring device 300.
  • the distance and orientation detected by the distance measuring device 300 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like.
  • the distance measuring device of the embodiment of the present invention may be applied to a mobile platform, and the distance measuring device may be installed on the platform body of the mobile platform.
  • a mobile platform with a distance measuring device can measure the external environment, for example, measuring the distance between the mobile platform and obstacles for obstacle avoidance and other purposes, and performing two-dimensional or three-dimensional mapping on the external environment.
  • the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera.
  • the distance measuring device is applied to an unmanned aerial vehicle, the platform body is the fuselage of the unmanned aerial vehicle.
  • the platform body When the distance measuring device is applied to an automobile, the platform body is the body of the automobile.
  • the car may be a self-driving car or a semi-automatic car, and no restriction is made here.
  • the platform body When the distance measuring device is applied to a remote control car, the platform body is the body of the remote control car.
  • the platform body When the distance measuring device is applied to a robot, the platform body is a robot.
  • the distance measuring device is applied to a camera, the platform body is the camera itself.
  • the present invention provides the above-mentioned light emission method, device and scanning system, and adjusts the frequency and/or power of the light pulse according to the scanning speed, so that a higher scanning point cloud density can be obtained under the premise of satisfying human eye laser safety.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

一种光发射方法、装置及扫描系统，光发射方法包括：出射光脉冲序列（S110）；改变光脉冲序列的传播方向，以对周围环境进行扫描（S120）；根据光脉冲序列的扫描速度控制光脉冲序列的出射频率和/或出射功率（S130）。使得在满足人眼激光安全的前提下，能够获得较高的扫描点云密度。

Description

一种光发射方法、装置及扫描系统 技术领域
本发明涉及光脉冲技术领域，尤其涉及脉冲频率的控制方法。
背景技术
激光雷达是对外界的感知系统，可以获知发射方向上的空间距离信息。其原理为主动对外发射激光脉冲信号，探测到反射回来的脉冲信号，根据发射与接收之间的时间差，判断被测物体的距离。激光光源波长处于人眼的敏感光谱段，激光的光脉冲信号在人眼停留时超过安全规定时会伤害人眼，而扫描系统的扫描速度不合适就导致光脉冲在人眼的停留时间过长会对人眼造成伤害或不能获得较高的扫描密度。
发明内容
本发明实施例提供一种光发射方法、装置及扫描系统，以解决扫描过程中无法保证人眼安全的问题。
第一方面，本发明实施例提供了一种光发射方法，所述方法至少包括：
出射光脉冲序列；
改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
第二方面，本发明实施例提供了一种光发射装置，所述装置包括：
光脉冲产生单元，用于出射光脉冲序列；
至少一个光学元件，用于改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
控制单元，用于根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
第三方面，本发明实施例提供了一种激光扫描系统，所述系统包括如第二方面所述的光发射装置。
本发明实施例的光发射方法、装置及扫描系统，通过根据扫描转速调整光脉冲的频率和/或功率，使得在满足人眼激光安全的前提下，能够获得较高的扫描点云密度。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例提供的一种光发射方法的示意性流程图；
图2是本发明实施例的测距装置的示意性结构框图；
图3是本发明的测距装置采用同轴光路的一种实施例的示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例的技术方中案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
人眼对不同波长的光辐射具有不同的透过率与吸收特性，一般来说400-1400nm的波段，晶体透过率较高，属于人眼的视网膜损害区。而激光扫描系统中可以产生可见或不可见的高强度、高方向性的光脉冲序列，波长在400-1000nm范围内，极低的光脉冲能量照射即可引起人眼的损伤。
基于上述考虑，本发明实施例提供了一种光发射方法。参见图1，图1是本发明实施例提供的一种光发射方法的示意性流程图。如图1所示，所述方法100包括：
步骤S110中，出射光脉冲序列；
步骤S120，改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
步骤130，根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
其中，光脉冲序列的扫描速度决定了光脉冲在人眼的停留时间，而光脉冲序列的出射频率和/或出射功率决定了激光脉冲在人眼停留的数量。当光脉冲在人眼停留的时间较短时，可以在合理范围内提高光脉冲序列的出射频率和/或出射功率，以获得较高的扫描点云密度，提高扫描的精度；而当光脉冲在人眼停留的时间较长时，可以在合理范围内减小光脉冲序列的出射频率和/或出射功率，以保证人眼的安全。
可选地，所述方法还包括：
检测所述光脉冲序列的扫描速度；
在所述光脉冲序列的扫描速度处于预定范围时，根据所述光脉冲序列的扫描速度的变化，改变所述光脉冲序列的出射频率和/或出射功率。
其中，当检测光脉冲序列的扫描速度处于预定的范围，说明扫描过程正常，可以根据光脉冲序列的扫描速度的变化来调节光脉冲序列的出射频率和/或出射功率，以兼顾人眼安全以及扫描的点云密度。当光脉冲序列的扫描速度变快时，激光在人眼的停留时间变短，那么光脉冲序列的出射频率和/或出射功率可在一定变化范围内提高，以在保证激光人眼安全的前提下实现提升点云密度。当光脉冲序列的扫描速度变慢时，激光在人眼的停留时间会变长，此时光脉冲序列的出射频率和/或出射功率可在一定变化范围内降低，使其达到激光人眼安全。
需要说明的是，所述光脉冲序列的出射频率和/或出射功率的变化范围根据扫描系统的不同而不同。
根据光脉冲序列的扫描速度的变化，所述光脉冲序列的出射频率和/或出射功率可以是线性变化，也可以是非线性变化，如阶梯性变化或指数变化等。
可选地，所述改变所述光脉冲序列的出射频率和/或出射功率包括：
控制所述光脉冲序列在第一时刻的出射频率和/或出射功率小于在第二时 刻的出射频率和/或出射功率，其中，所述光脉冲序列在所述第一时刻的扫描速度小于在所述第二时刻的扫描速度。
可选地，所述改变所述光脉冲序列的出射频率和/或出射功率包括：
当所述光脉冲序列的扫描速度增加时，增加所述雷达发射的激光脉冲频率和/或功率；和/或，
当所述光脉冲序列的扫描速度减小时，减小所述雷达发射的激光脉冲频率和/或功率。
可选地，所述光脉冲序列的出射频率和/或出射功率随着所述光脉冲序列的扫描速度阶梯性变化。因为在一定范围内光脉冲序列的扫描速度，使得光脉冲在人眼停留的时间相差不大，可以将光脉冲序列的扫描速度分为多个阶段，每个阶段之间对应的光脉冲序列的出射频率和/或出射功率不同，每个阶段内部对应的光脉冲序列的出射频率和/或出射功率相同；这样可以减小控制难度，提高稳定性，避免所述光脉冲序列的出射频率和/或出射功率频繁变动，影响扫描的稳定性。
在一些实施例中，所述控制所述光脉冲序列的出射频率和/或出射功率包括：
当所述光脉冲序列的扫描速度位于第一范围内时，控制所述光脉冲序列的出射频率和/或出射功率为第一出射频率和/或出射功率；
当所述光脉冲序列的扫描速度位于第二范围内时，控制所述光脉冲序列的出射频率和/或出射功率为第二出射频率和/或出射功率；
其中，所述第一范围中的数值大于所述第二范围中的数值，且所述第一出射频率和/或出射功率大于所述第二出射频率和/或出射功率。
可选地，所述方法还包括：
当所述光脉冲序列的扫描速度低于预定的最低转速时，则停止发射光脉冲序列。
如果当因为某些因素，带动发射光脉冲序列的光脉冲产生单元的动力部件出现故障使得动力部件的转速低于某一个下限阈值时，降低光脉冲序列的出射频率和/或出射功率依然无法满足人眼激光安全要求，因为此时限制激光安全 的因素为激光雷达单个脉冲的能量，可以采取直接让激光停止发光的策略来满足人眼激光安全要求。
需要说明的是，所述下限阈值根据不同扫描系统则有不同的数值。
可选地，所述改变所述光脉冲序列的传播方向包括：通过至少一个运动的光学元件改变所述光脉冲序列的传播方向。
可选地，所述改变所述光脉冲序列的传播方向包括：通过至少一个旋转的光折射元件改变所述光脉冲序列的传播方向，其中所述光折射元件具有相对的、不平行的出光面和入光面。
其中，所述至少一个光学元件，例如，透镜、反射镜、棱镜、光栅、光学相控阵(Optical Phased Array)或上述光学元件的任意组合。
可选地，所述方法还包括：根据所述至少一个运动的光学元件的运动速度确定所述光脉冲序列的扫描速度。
由于光脉冲序列通过所述光学元件改变传播方向后出射，而光学元件的转动将所述光脉冲序列发射至各个方向，所以光学元件的运动速度与所述光脉冲序列的扫描速度成正相关。
可选地，所述方法还包括：当所述光脉冲序列的扫描速度低于预定的最低转速时，提示用户。
其中，当光脉冲序列的扫描速度低于预定的最低转速时，说明扫描过程异常，可以提示用户所述扫描过程发生异常，便于用户及时排除故障。
可选地，所述方法还包括：
接收经物体反射回的光脉冲信号；
根据所述接收的光脉冲信号确定所述物体的位置。
在一个实施例中，一种光发射方法包括：
出射光脉冲序列；
所述光脉冲序列经过至少一个光学元件，并改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
检测所述光脉冲序列的扫描速度；如果所述光脉冲序列的扫描速度处于预 定范围则检测所述光脉冲序列的扫描速度的变化；
如果所述光脉冲序列的扫描速度从第一范围变化至第二范围，所述第一范围的速度均小于第二范围的速度；则控制所述光脉冲序列的出射频率和/或出射功率从第一出射频率和/或出射功率增加至第二出射频率和/或出射功率；其中，所述第一范围的速度均小于第二范围的速度，说明所述光脉冲序列的扫描速度增加，光脉冲停留在人眼的时间变短，人眼相对比较安全，这时可以提高所述光脉冲序列的出射频率和/或出射功率，获取更大的点云密度；
如果检测到光脉冲序列的扫描速度低于预定的最低转速时，则说明在扫描过程中，带动发射光脉冲序列的光脉冲产生单元的动力部件出现故障，可以立刻停止出射所述光脉冲序列，以避免转速过低造成人眼伤害的问题。
第二方面，本发明实施例提供了一种光发射装置，所述装置包括：
光脉冲产生单元，用于出射光脉冲序列；
至少一个光学元件，用于改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
控制单元，用于根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
可选地，至少一个光学元件包括至少一个旋转的光折射元件，所述光折射元件具有相对的、不平行的出光面和入光面。
可选地，所述控制单元，还根据所述至少一个运动的光学元件的运动速度确定所述光脉冲序列的扫描速度。
可选地，所述光发射装置还包括：
检测单元，用于检测所述光学元件的运动速度；
所述控制单元还用于判断所述光学元件的运动速度转速是否处于预定范围，如果所述光学元件的运动速度处于预定范围，则计算所述光学元件的运动速度的变化，并根据所述光学元件的运动速度的变化，控制所述光脉冲序列的出射频率和/或出射功率。
可选地，所述控制单元还用于：
当第一时刻的所述光学元件的第一运动速度小于第二时刻的所述光学元 件的第二运动速度时，控制第一时刻的光脉冲序列的出射频率和/或出射功率小于第二时刻的光脉冲序列的出射频率和/或出射功率。
可选地，所述控制装单元还用于：控制所述光脉冲序列的出射频率和/或出射功率随着所述光学元件的运动速度阶梯性变化。
可选地，所述控制单元还用于：当所述所述光学元件的运动速度低于预定的最低转速时，控制所述光脉冲产生单元停止发射光脉冲序列。
可选地，所述光发射装置还包括：
提示单元，用于当所述所述光学元件的运动速度低于预定的最低转速时发出提示信号。
可选地，所述光发射装置还包括：
接收单元，用于接收经物体反射回的光脉冲信号；
所述控制单元还用于根据所述接收的光脉冲信号确定所述物体的位置。
第三方面，本发明实施例提供了一种激光扫描系统，所述系统包括如第二方面所述的光发射装置。
本发明各个实施例提供的光发射方法、装置及扫描系统可以应用于测距装置，该测距装置可以是激光雷达、激光测距设备等电子设备。在一种实施例中，测距装置用于感测外部环境信息，例如，环境目标的距离信息、方位信息、反射强度信息、速度信息等。一种实现方式中，测距装置可以通过测量测距装置和探测物之间光传播的时间，即光飞行时间(Time-of-Flight，TOF)，来探测探测物到测距装置的距离。或者，测距装置也可以通过其他技术来探测探测物到测距装置的距离，例如基于相位移动(phase shift)测量的测距方法，或者基于频率移动(frequency shift)测量的测距方法，在此不做限制。
为了便于理解，以下将结合图2所示的测距装置200对测距的工作流程进行举例描述。
如图2所示，测距装置200可以包括发射电路210、接收电路220、采样电路230和运算电路240。
发射电路210可以发射光脉冲序列(例如激光脉冲序列)。接收电路220 可以接收经过被探测物反射的光脉冲序列，并对该光脉冲序列进行光电转换，以得到电信号，再对电信号进行处理之后可以输出给采样电路230。采样电路230可以对电信号进行采样，以获取采样结果。运算电路240可以基于采样电路230的采样结果，以确定测距装置200与被探测物之间的距离。
可选地，该测距装置200还可以包括控制电路250，该控制电路250可以实现对其他电路的控制，例如，可以控制各个电路的工作时间和/或对各个电路进行参数设置等。
应理解，虽然图2示出的测距装置中包括一个发射电路、一个接收电路、一个采样电路和一个运算电路，用于出射一路光束进行探测，但是本申请实施例并不限于此，发射电路、接收电路、采样电路、运算电路中的任一种电路的数量也可以是至少两个，用于沿相同方向或分别沿不同方向出射至少两路光束；其中，该至少两束光路可以是同时出射，也可以是分别在不同时刻出射。一个示例中，该至少两个发射电路中的发光芯片封装在同一个模块中。例如，每个发射电路包括一个激光发射芯片，该至少两个发射电路中的激光发射芯片中的die封装到一起，容置在同一个封装空间中。
一些实现方式中，除了图2所示的电路，测距装置200还可以包括扫描模块260，用于将发射电路出射的至少一路激光脉冲序列改变传播方向出射。
其中，可以将包括发射电路210、接收电路220、采样电路230和运算电路240的模块，或者，包括发射电路210、接收电路220、采样电路230、运算电路240和控制电路250的模块称为测距模块，该测距模块可以独立于其他模块，例如，扫描模块260。
测距装置中可以采用同轴光路，也即测距装置出射的光束和经反射回来的光束在测距装置内共用至少部分光路。例如，发射电路出射的至少一路激光脉冲序列经扫描模块改变传播方向出射后，经探测物反射回来的激光脉冲序列经过扫描模块后入射至接收电路。或者，测距装置也可以采用异轴光路，也即测距装置出射的光束和经反射回来的光束在测距装置内分别沿不同的光路传输。图3示出了本发明的测距装置采用同轴光路的一种实施例的示意图。
测距装置300包括测距模块310，测距模块310包括发射器303(可以包括上述的发射电路)、准直元件304、探测器305(可以包括上述的接收电路、采样电路和运算电路)和光路改变元件306。测距模块310用于发射光束，且 接收回光，将回光转换为电信号。其中，发射器303可以用于发射光脉冲序列。在一个实施例中，发射器303可以发射激光脉冲序列。可选的，发射器303发射出的激光束为波长在可见光范围之外的窄带宽光束。准直元件304设置于发射器的出射光路上，用于准直从发射器303发出的光束，将发射器303发出的光束准直为平行光出射至扫描模块。准直元件还用于会聚经探测物反射的回光的至少一部分。该准直元件304可以是准直透镜或者是其他能够准直光束的元件。
在图3所示实施例中，通过光路改变元件306来将测距装置内的发射光路和接收光路在准直元件304之前合并，使得发射光路和接收光路可以共用同一个准直元件，使得光路更加紧凑。在其他的一些实现方式中，也可以是发射器303和探测器305分别使用各自的准直元件，将光路改变元件306设置在准直元件之后的光路上。
在图3所示实施例中，由于发射器303出射的光束的光束孔径较小，测距装置所接收到的回光的光束孔径较大，所以光路改变元件可以采用小面积的反射镜来将发射光路和接收光路合并。在其他的一些实现方式中，光路改变元件也可以采用带通孔的反射镜，其中该通孔用于透射发射器303的出射光，反射镜用于将回光反射至探测器305。这样可以减小采用小反射镜的情况中小反射镜的支架会对回光的遮挡。
在图3所示实施例中，光路改变元件偏离了准直元件304的光轴。在其他的一些实现方式中，光路改变元件也可以位于准直元件304的光轴上。
测距装置300还包括扫描模块302。扫描模块302放置于测距模块310的出射光路上，扫描模块302用于改变经准直元件304出射的准直光束319的传输方向并投射至外界环境，并将回光投射至准直元件304。回光经准直元件304汇聚到探测器305上。
在一个实施例中，扫描模块302可以包括至少一个光学元件，用于改变光束的传播路径，其中，该光学元件可以通过对光束进行反射、折射、衍射等等方式来改变光束传播路径。例如，扫描模块302包括透镜、反射镜、棱镜、振镜、光栅、液晶、光学相控阵(Optical Phased Array)或上述光学元件的任意组合。一个示例中，至少部分光学元件是运动的，例如通过驱动模块来驱动该至少部分光学元件进行运动，该运动的光学元件可以在不同时刻将光束反射、 折射或衍射至不同的方向。在一些实施例中，扫描模块302的多个光学元件可以绕共同的轴309旋转或振动，每个旋转或振动的光学元件用于不断改变入射光束的传播方向。在一个实施例中，扫描模块302的多个光学元件可以以不同的转速旋转，或以不同的速度振动。在另一个实施例中，扫描模块302的至少部分光学元件可以以基本相同的转速旋转。在一些实施例中，扫描模块的多个光学元件也可以是绕不同的轴旋转。在一些实施例中，扫描模块的多个光学元件也可以是以相同的方向旋转，或以不同的方向旋转；或者沿相同的方向振动，或者沿不同的方向振动，在此不作限制。
在一个实施例中，扫描模块302包括第一光学元件314和与第一光学元件314连接的驱动器316，驱动器316用于驱动第一光学元件314绕转动轴309转动，使第一光学元件314改变准直光束319的方向。第一光学元件314将准直光束319投射至不同的方向。在一个实施例中，准直光束319经第一光学元件改变后的方向与转动轴309的夹角随着第一光学元件314的转动而变化。在一个实施例中，第一光学元件314包括相对的非平行的一对表面，准直光束319穿过该对表面。在一个实施例中，第一光学元件314包括厚度沿至少一个径向变化的棱镜。在一个实施例中，第一光学元件314包括楔角棱镜，对准直光束319进行折射。
在一个实施例中，扫描模块302还包括第二光学元件315，第二光学元件315绕转动轴303转动，第二光学元件315的转动速度与第一光学元件314的转动速度不同。第二光学元件315用于改变第一光学元件314投射的光束的方向。在一个实施例中，第二光学元件315与另一驱动器317连接，驱动器317驱动第二光学元件315转动。第一光学元件314和第二光学元件315可以由相同或不同的驱动器驱动，使第一光学元件314和第二光学元件315的转速和/或转向不同，从而将准直光束319投射至外界空间不同的方向，可以扫描较大的空间范围。在一个实施例中，控制器318控制驱动器316和317，分别驱动第一光学元件314和第二光学元件315。第一光学元件314和第二光学元件315的转速可以根据实际应用中预期扫描的区域和样式确定。驱动器316和317可以包括电机或其他驱动器。
在一个实施例中，第二光学元件315包括相对的非平行的一对表面，光束穿过该对表面。在一个实施例中，第二光学元件315包括厚度沿至少一个径向 变化的棱镜。在一个实施例中，第二光学元件315包括楔角棱镜。
一个实施例中，扫描模块302还包括第三光学元件(图未示)和用于驱动第三光学元件运动的驱动器。可选地，该第三光学元件包括相对的非平行的一对表面，光束穿过该对表面。在一个实施例中，第三光学元件包括厚度沿至少一个径向变化的棱镜。在一个实施例中，第三光学元件包括楔角棱镜。第一、第二和第三光学元件中的至少两个光学元件以不同的转速和/或转向转动。
扫描模块302中的各光学元件旋转可以将光投射至不同的方向，例如光311和313的方向，如此对测距装置300周围的空间进行扫描。当扫描模块302投射出的光311打到被探测物301时，一部分光被探测物301沿与投射的光311相反的方向反射至测距装置300。被探测物301反射的回光312经过扫描模块302后入射至准直元件304。
探测器305与发射器303放置于准直元件304的同一侧，探测器305用于将穿过准直元件304的至少部分回光转换为电信号。
一个实施例中，各光学元件上镀有增透膜。可选的，增透膜的厚度与发射器103发射出的光束的波长相等或接近，能够增加透射光束的强度。
一个实施例中，测距装置中位于光束传播路径上的一个元件表面上镀有滤光层，或者在光束传播路径上设置有滤光器，用于至少透射发射器所出射的光束所在波段，反射其他波段，以减少环境光给接收器带来的噪音。
在一些实施例中，发射器303可以包括激光二极管，通过激光二极管发射纳秒级别的激光脉冲。进一步地，可以确定激光脉冲接收时间，例如，通过探测电信号脉冲的上升沿时间和/或下降沿时间确定激光脉冲接收时间。如此，测距装置300可以利用脉冲接收时间信息和脉冲发出时间信息计算TOF，从而确定被探测物301到测距装置300的距离。
测距装置300探测到的距离和方位可以用于遥感、避障、测绘、建模、导航等。在一种实施例中，本发明实施例的测距装置可应用于移动平台，测距装置可安装在移动平台的平台本体。具有测距装置的移动平台可对外部环境进行测量，例如，测量移动平台与障碍物的距离用于避障等用途，和对外部环境进行二维或三维的测绘。在某些实施例中，移动平台包括无人飞行器、汽车、遥控车、机器人、相机中的至少一种。当测距装置应用于无人飞行器时，平台本体为无人飞行器的机身。当测距装置应用于汽车时，平台本体为汽车的车身。 该汽车可以是自动驾驶汽车或者半自动驾驶汽车，在此不做限制。当测距装置应用于遥控车时，平台本体为遥控车的车身。当测距装置应用于机器人时，平台本体为机器人。当测距装置应用于相机时，平台本体为相机本身。
本发明通过提供上述光发射方法、装置和扫描系统，通过根据扫描转速调整光脉冲的频率和/或功率，使得在满足人眼激光安全的前提下，能够获得较高的扫描点云密度。
本发明实施例中所使用的技术术语仅用于说明特定实施例而并不旨在限定本发明。在本文中，单数形式“一”、“该”及“所述”用于同时包括复数形式，除非上下文中明确另行说明。进一步地，在说明书中所使用的用于“包括”和/或“包含”是指存在所述特征、整体、步骤、操作、元件和/或构件，但是并不排除存在或增加一个或多个其它特征、整体、步骤、操作、元件和/或构件。
在所附权利要求中对应结构、材料、动作以及所有装置或者步骤以及功能元件的等同形式(如果存在的话)旨在包括结合其他明确要求的元件用于执行该功能的任何结构、材料或动作。本发明的描述出于实施例和描述的目的被给出，但并不旨在是穷举的或者将被发明限制在所公开的形式。在不偏离本发明的范围和精神的情况下，多种修改和变形对于本领域的一般技术人员而言是显而易见的。本发明中所描述的实施例能够更好地揭示本发明的原理与实际应用，并使本领域的一般技术人员可了解本发明。
本发明中所描述的流程图仅仅为一个实施例，在不偏离本发明的精神的情况下对此图示或者本发明中的步骤可以有多种修改变化。比如，可以不同次序的执行这些步骤，或者可以增加、删除或者修改某些步骤。本领域的一般技术人员可以理解实现上述实施例的全部或部分流程，并依本发明权利要求所作的等同变化，仍属于发明所涵盖的范围。

Claims (28)

  1. 一种光发射方法，其特征在于，所述方法包括：
    出射光脉冲序列；
    改变所述光脉冲序列的传播方向，以对周围环境进行扫描；
    根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
  2. 如权利要求1所述的方法，其特征在于，所述方法还包括：
    检测所述光脉冲序列的扫描速度；
    在所述光脉冲序列的扫描速度转速处于预定范围时，根据所述光脉冲序列的扫描速度的变化，改变所述光脉冲序列的出射频率和/或出射功率。
  3. 如权利要求2所述的方法，其特征在于，所述改变所述光脉冲序列的出射频率和/或出射功率包括：
    控制所述光脉冲序列在第一时刻的出射频率和/或出射功率小于在第二时刻的出射频率和/或出射功率，其中，所述光脉冲序列在所述第一时刻的扫描速度小于在所述第二时刻的扫描速度。
  4. 如权利要求3所述的方法，其特征在于，所述改变所述光脉冲序列的出射频率和/或出射功率包括：
    当所述光脉冲序列的扫描速度增加时，增加所述光脉冲序列的出射频率和/或出射功率；和/或，
    当所述光脉冲序列的扫描速度减小时，减小所述光脉冲序列的出射频率和/或出射功率。
  5. 如权利要求3所述的方法，其特征在于，所述控制所述光脉冲序列的出射频率和/或出射功率包括：
    当所述光脉冲序列的扫描速度位于第一范围内时，控制所述光脉冲序列的出射频率和/或出射功率为第一出射频率和/或出射功率；
    当所述光脉冲序列的扫描速度位于第二范围内时，控制所述光脉冲序列的 出射频率和/或出射功率为第二出射频率和/或出射功率；
    其中，所述第一范围中的数值大于所述第二范围中的数值，且所述第一出射频率和/或出射功率大于所述第二出射频率和/或出射功率。
  6. 如权利要求2所述的方法，其特征在于，所述方法还包括：
    当所述光脉冲序列的扫描速度低于预定的最低转速时，则停止发射光脉冲序列。
  7. 如权利要求1-6中任一项所述的方法，其特征在于，所述改变所述光脉冲序列的传播方向包括：通过至少一个运动的光学元件改变所述光脉冲序列的传播方向。
  8. 如权利要求1-6中任一项所述的方法，其特征在于，所述改变所述光脉冲序列的传播方向包括：通过至少一个旋转的光折射元件改变所述光脉冲序列的传播方向，其中所述光折射元件具有相对的、不平行的出光面和入光面。
  9. 如权利要求1-6中任一项所述的方法，其特征在于，所述方法还包括：根据所述至少一个运动的光学元件的运动速度确定所述光脉冲序列的扫描速度。
  10. 如权利要求2所述的方法，其特征在于，所述方法还包括：当所述光脉冲序列的扫描速度低于预定的最低转速时，提示用户。
  11. 如权利要求1所述的方法，其特征在于，所述方法还包括：
    接收经物体反射回的光脉冲信号；
    根据所述接收的光脉冲信号确定所述物体的位置。
  12. 一种光发射装置，其特征在于，所述装置包括：
    光脉冲产生单元，用于出射光脉冲序列；
    至少一个光学元件，用于改变所述光脉冲序列的传播方向，以对周围环境 进行扫描；
    控制单元，用于根据所述光脉冲序列的扫描速度控制所述光脉冲序列的出射频率和/或出射功率。
  13. 如权利要求12所述的光发射装置，其特征在于，所述光发射装置还包括：
    检测单元，用于检测所述光脉冲序列的扫描速度；
    所述控制单元还用于判断所述光脉冲序列的扫描速度是否处于预定范围，如果所述光脉冲序列的扫描速度处于预定范围，则计算所述光脉冲序列的扫描速度的变化，并根据所述光脉冲序列的扫描速度的变化，控制所述光脉冲序列的出射频率和/或出射功率。
  14. 如权利要求12所述的光发射装置，其特征在于，所述控制单元还用于：
    控制所述光脉冲序列在第一时刻的出射频率和/或出射功率小于在第二时刻的出射频率和/或出射功率，其中，所述光脉冲序列在所述第一时刻的扫描速度小于在所述第二时刻的扫描速度。
  15. 如权利要求12所述的光发射装置，其特征在于，所述控制单元还用于：
    当所述光脉冲序列的扫描速度增加时，增加所述光脉冲序列的出射频率和/或出射功率；和/或，
    当所述光脉冲序列的扫描速度减小时，减小所述光脉冲序列的出射频率和/或出射功率。
  16. 如权利要求12所述的光发射装置，其特征在于，所述控制单元还用于：
    当所述光脉冲序列的扫描速度位于第一范围内时，控制所述光脉冲序列的出射频率和/或出射功率为第一出射频率和/或出射功率；
    当所述光脉冲序列的扫描速度位于第二范围内时，控制所述光脉冲序列的 出射频率和/或出射功率为第二出射频率和/或出射功率；
    其中，所述第一范围中的数值大于所述第二范围中的数值，且所述第一出射频率和/或出射功率大于所述第二出射频率和/或出射功率。
  17. 如权利要求12所述的光发射装置，其特征在于，所述控制单元还用于：
    当所述光脉冲序列的扫描速度低于预定的最低转速时，则停止发射光脉冲序列。
  18. 如权利要求12-17中任意一项所述的光发射装置，其特征在于，所述改变所述光脉冲序列的传播方向包括：通过至少一个运动的光学元件改变所述光脉冲序列的传播方向。
  19. 如权利要求12-17中任意一项所述的光发射装置，其特征在于，所述改变所述光脉冲序列的传播方向包括：通过至少一个旋转的光折射元件改变所述光脉冲序列的传播方向，其中所述光折射元件具有相对的、不平行的出光面和入光面。
  20. 如权利要求13所述的光发射装置，其特征在于，所述检测单元还用于：根据所述至少一个运动的光学元件的运动速度确定所述光脉冲序列的扫描速度。
  21. 如权利要求12所述的光发射装置，其特征在于，所述光发射装置还包括：
    提示单元，用于当所述所述光学元件的运动速度低于预定的最低转速时发出提示信号。
  22. 如权利要求12所述的光发射装置，其特征在于，所述光发射装置还包括：
    接收单元，用于接收经物体反射回的光脉冲信号；
    所述控制单元还用于根据所述接收的光脉冲信号确定所述物体的位置。
  23. 一种测距装置，其特征在于，包括：
    如权利要求1至22任一项所述的光发射装置，用于依次出射激光脉冲信号；
    光电转换电路，用于接收所述光发射装置出射的激光脉冲信号经物体反射回的至少部分光信号，以及将接收到的光信号转成电信号；
    采样电路，用于对来自所述光电转换电路的电信号进行采样，获得采样结果；
    运算电路，用于根据所述采样结果计算所述物体与所述测距装置之间的距离。
  24. 根据权利要求23所述的测距装置，其特征在于，所述光发射装置的数量和所述光电转换电路的数量分别为至少2个；
    每个所述光电转换电路用于接收来自对应的光发射装置出射的激光脉冲信号经物体反射回的至少部分光信号，以及将接收到的光信号转成电信号。
  25. 根据权利要求23或24所述的测距装置，其特征在于，所述激光测距装置还包括扫描模块；
    所述扫描模块用于改变所述激光脉冲信号的传输方向后出射，经物体反射回的激光脉冲信号经过所述扫描模块后入射至所述光电转换电路。
  26. 根据权利要求25所述的测距装置，其特征在于，所述扫描模块包括驱动器和厚度不均匀的棱镜，所述驱动器用于带动所述棱镜转动，以将经过所述棱镜的激光脉冲信号改变至不同方向出射。
  27. 根据权利要求26所述的测距装置，其特征在于，所述扫描模块包括两个驱动器，以及两个并列设置的、厚度不均匀的棱镜，所述两个驱动器分别 用于驱动所述两个棱镜以相反的方向转动；
    来自所述激光发射装置的激光脉冲信号依次经过所述两个棱镜后改变传输方向出射。
  28. 根据权利要求26所述的测距装置，其特征在于，所述检测单元用于通过检测所述棱镜的转速来检测所述光脉冲序列的扫描速度。
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