WO2019237911A1 - 光发射模块、光发射单元、光信号检测模块、光学系统和激光雷达系统 - Google Patents

光发射模块、光发射单元、光信号检测模块、光学系统和激光雷达系统 Download PDF

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Publication number
WO2019237911A1
WO2019237911A1 PCT/CN2019/088567 CN2019088567W WO2019237911A1 WO 2019237911 A1 WO2019237911 A1 WO 2019237911A1 CN 2019088567 W CN2019088567 W CN 2019088567W WO 2019237911 A1 WO2019237911 A1 WO 2019237911A1
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Prior art keywords
signal
frequency
unit
laser beam
optical
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PCT/CN2019/088567
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English (en)
French (fr)
Inventor
胡小波
刘孙光
刘颖
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深圳市镭神智能系统有限公司
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Priority to CN201980006896.5A priority Critical patent/CN111527417B/zh
Priority to US16/972,686 priority patent/US11726180B2/en
Publication of WO2019237911A1 publication Critical patent/WO2019237911A1/zh

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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
    • G01S17/08—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
    • G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S17/36—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated with phase comparison between the received signal and the contemporaneously transmitted signal
    • 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
    • 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
    • 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
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
    • 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
    • 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
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out
    • 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
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497—Means for monitoring or calibrating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
    • H01S5/0085—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping for modulating the output, i.e. the laser beam is modulated outside the laser cavity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/0225—Out-coupling of light
    • H01S5/02253—Out-coupling of light using lenses
    • 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
    • G01S7/4813—Housing arrangements

Definitions

  • the embodiments of the present application relate to the field of laser ranging technology, for example, to a light emitting module, a light emitting unit, a light signal detecting module, an optical system, and a lidar system.
  • a laser radar system is a radar system that emits a laser beam (detection light signal) to detect a target's position, velocity, and other characteristic quantities.
  • the lidar system can detect the relevant information of the target object, such as the target's orientation, distance, height, speed, attitude, and even shape parameters, so as to detect, track and identify the target object.
  • Lidar systems are essential core sensors in the fields of automotive autopilot, robot positioning and navigation, space environment mapping, and security. In practical applications, according to different principles, lidar systems can be divided into: triangle-based lidar systems, time-based pulsed lidar systems, and phase-based lidar systems.
  • the phase method lidar system implements the correction by loading a sinusoidal modulation signal of a certain frequency onto a laser, and using the distance information contained in the phase difference between the transmitted signal (probe optical signal) and the received signal (echo signal). The measurement of the distance of the measured target object.
  • the higher the frequency of the detection optical signal the higher the detection accuracy, the smaller the detection range, the lower the frequency of the detection optical signal, the lower the detection accuracy, and the larger the detection range.
  • distance measurement of a target object with high detection accuracy and a large detection range cannot be achieved.
  • the present application provides a light emitting module, a light emitting unit, a light signal detecting module, an optical system, and a lidar system, which realize distance measurement of a target object with high detection accuracy and a large detection range.
  • an embodiment of the present application provides a light emitting module, where the light emitting module includes:
  • a high-frequency modulation signal output unit configured to output a preset high-frequency modulation signal of at least two different frequencies
  • a laser emitting unit connected to the high-frequency modulation signal output unit and configured to emit laser beams of at least two different frequencies respectively modulated by the at least two high-frequency modulation signals of different frequencies;
  • the reference signal transmitting unit is connected to the high-frequency modulation signal output unit and is configured to transmit at least two reference signals of different frequencies that are respectively modulated by the at least two high-frequency modulation signals of different frequencies.
  • an embodiment of the present application provides a light emitting unit, including: a light source subunit, a high frequency modulation subunit, and a difference frequency subunit;
  • the light source subunit is configured to emit an initial light beam
  • the high-frequency modulation subunit is configured to perform frequency modulation on the initial light beam by using an optical mixing technique to emit at least two high-frequency transmission signals with different frequencies;
  • the difference frequency subunit is configured to perform difference frequency processing on any two high-frequency transmission signals of different frequencies, and emit at least one low-frequency transmission signal;
  • At least one of the high-frequency transmission signals and at least one of the low-frequency transmission signals are detected by the light transmission unit as detection light signals.
  • an embodiment of the present application provides an optical signal detection module.
  • the optical signal detection module includes a signal receiving unit and a signal processing unit, and the signal receiving unit is electrically connected to the signal processing unit.
  • the signal receiving unit is configured to receive a first reference signal, a second reference signal, a first high-frequency echo signal, and a second high-frequency echo signal; wherein the first reference signal is a first high-frequency modulated signal A modulated reference signal, the second reference signal is a reference signal modulated by a second high-frequency modulation signal; the first high-frequency echo signal is a laser beam after the first laser beam is reflected by the target object, so The second high-frequency echo signal is a laser beam after the second laser beam is reflected by the target object; the first laser beam is a laser beam modulated by the first high-frequency modulation signal, and the second The laser beam is a laser beam modulated by the second high-frequency modulation signal; the frequency of the first high-frequency modulation signal is greater than the frequency of the second high-frequency modulation signal;
  • the signal processing unit is configured to: obtain a first reference distance value of the target object according to a first phase difference between the first reference signal and the first high-frequency echo signal; and according to the first phase And a second phase difference to obtain a second reference distance value of the target object, and determine a measurement distance value of the target object according to the first reference distance value and the second reference distance value; wherein the first The two phase differences are phase differences between the second reference signal and the second high-frequency echo signal.
  • an embodiment of the present application provides an optical system, which includes the light transmitting module provided in the first aspect and a signal receiving unit in the optical signal detection module provided in the second aspect.
  • an embodiment of the present application further provides a lidar system.
  • the lidar system includes a light emitting module provided in the first aspect and a light signal detection module provided in the second aspect.
  • FIG. 1 is a schematic structural diagram of a light emitting module according to an embodiment of the present application.
  • FIG. 2 is a schematic diagram of a working principle of a frequency synthesizer provided by an embodiment of the present application
  • FIG. 3 is a schematic structural diagram of a laser emitting unit according to an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a light emitting unit according to an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of an optical signal detection module according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a principle of a differential frequency phase detection technology according to an embodiment of the present application.
  • FIG. 7 is a schematic flowchart of a digital phase detection technology provided by an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a laser emitting unit and a signal receiving unit according to an embodiment of the present application
  • FIG. 9 is a structural block diagram of an optical system according to an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a hardware principle of a laser radar provided by an embodiment of the present application.
  • FIG. 12 is a dual-emitting single-receiving optical system provided by an embodiment of the present application.
  • FIG. 14 is a single-emitting single-receiving optical system provided by an embodiment of the present application.
  • 15 is a schematic cross-sectional structure diagram of a motor-driven belt-driven, slip-ring powered lidar system according to an embodiment of the present application;
  • 16 is a schematic cross-sectional structure diagram of an electromagnetic induction power supply and wireless communication laser radar system according to an embodiment of the present application;
  • FIG. 17 is a schematic cross-sectional structure diagram of a lidar system of a wireless power supply and optical communication system according to an embodiment of the present application.
  • FIG. 18 is a schematic flowchart of a laser radar system according to an embodiment of the present application.
  • FIG. 19 is a schematic flowchart of an algorithm of a laser radar system according to an embodiment of the present application.
  • optical emission module and the optical signal detection module provided in the embodiments of the present application can be applied to a lidar system.
  • the optical emission module and the optical signal detection module will be described below in combination with application scenarios.
  • FIG. 1 is a schematic structural diagram of a light emitting module according to an embodiment.
  • the optical transmission module includes a high-frequency modulation signal output unit 10, a laser transmission unit 20, and a reference signal transmission unit 30.
  • the high-frequency modulation signal output unit 10 is configured to output preset high-frequency modulation signals of at least two different frequencies;
  • the laser emitting unit 20 is connected to the high-frequency modulation signal output unit 10 and is configured to transmit respectively A laser beam of at least two different frequencies modulated by at least two high-frequency modulation signals of different frequencies;
  • the reference signal transmitting unit 30 is connected to the high-frequency modulation signal output unit 10 and is set to emit light beams respectively A reference signal of at least two different frequencies after being modulated by the high-frequency modulation signal.
  • each high-frequency modulation signal is a main oscillator signal; the high-frequency modulation signal output unit 10 is further configured to output at least two local oscillator signals with different frequencies, where at least two local oscillator signals and at least two The main oscillation signals correspond one-to-one, and each local oscillation signal is different from the corresponding main oscillation signal by a preset frequency.
  • the high-frequency modulation signal output unit 10 includes at least two phase-locked loops, and each phase-locked loop is configured to output a main oscillation signal and a local oscillation signal corresponding to the main oscillation signal.
  • the absolute value of the difference between the frequencies of the different main oscillation signals is within a preset frequency range.
  • the preset frequency range is 0MHz-50MHz.
  • the at least two reference signals of different frequencies are at least two reference laser beams of different frequencies or at least two reference electrical signals of different frequencies.
  • the at least two reference signals of different frequencies are at least two reference laser beams of different frequencies
  • the at least two reference signals may be transmitted by a laser emitting unit.
  • the high-frequency modulation signal output unit 10 includes three phase-locked loops. Each phase-locked loop can output a group of high-frequency modulation signals, so the three phase-locked loops can output three groups of different frequencies. High-frequency modulated signals.
  • Phase-locked loop is a feedback control circuit, referred to as phase-locked loop (PLL, Phase-Locked Loop).
  • a group of high-frequency modulation signals includes a main oscillation signal and a local oscillation signal corresponding to the main oscillation signal.
  • DDS Direct Digital Synthesizer
  • FIG. 2 is a schematic diagram of a working principle of a DDS provided by an embodiment.
  • the DDS includes a phase accumulator 111, a sine lookup table 112, a digital to analog converter (DAC) 113, and a low pass filter (LTP) 114.
  • clock signals fc are input respectively.
  • the frequency control word K is input to the phase accumulator 111.
  • the phase accumulator 111 is the core of the DDS.
  • the phase accumulator 111 is composed of an N-bit binary adder and an N-bit register sampled by the clock signal fc, and is used to linearly accumulate the frequency control word K (decimal).
  • the phase accumulator 111 is configured to implement phase accumulation and store the accumulation result. When the phase accumulator 111 accumulates a full amount, an overflow occurs, which completes a cycle of action. This cycle is a frequency cycle of the DDS system synthesis signal, and the overflow frequency of the phase accumulator 111 is the output signal frequency.
  • the sine lookup table 112 is a programmable read-only memory that stores the sampled and encoded value of a periodic sine signal with phase as the address, and contains the digital amplitude information of a periodic sine wave. Each address corresponds to 0 to 2 ⁇ in the sine wave. One phase point of the range (phases from 0 to 2 ⁇ are equally divided into M parts).
  • the function of the digital-to-analog converter 113 is to convert a digital signal into an analog signal.
  • a sequence of sine amplitude values is converted into a sine wave.
  • the higher the resolution of the digital-to-analog converter 113 the better the continuity of the output sine wave.
  • the output sine wave is a trapezoidal waveform.
  • the filter 114 the low-pass filter may also be a band-pass filter
  • the frequency of the output analog waveform fout can be changed by changing the clock signal fc, the number of bits N of the phase accumulator 111 or the number of bits M of the sine lookup table 112.
  • the laser emitting unit 20 may include a laser, and the laser is configured to emit a laser beam with better collimation and energy concentration.
  • the laser may be a semiconductor laser, a fiber laser, a gas laser, or a solid-state laser.
  • the wavelength of the laser beam emitted by the laser may be 635 nanometers (nm), 650 nm, 780 nm, 792 nm, or 850 nm.
  • the laser emitting unit 20 includes a laser diode, such as a low-power continuous laser diode in the infrared band.
  • the low power here refers to the power of the milliwatt level.
  • Low power on the one hand, can avoid the heat generated by the laser emitting unit 20 from affecting the performance of the electrical components in the light emitting module and peripheral circuits.
  • the laser generated by the low-power laser diode is a type of safety laser.
  • the human body, especially the human eye, is harmless; on the other hand, it can reduce costs.
  • FIG. 3 is a schematic structural diagram of a laser emitting unit according to an embodiment.
  • the laser emitting unit 20 includes a laser diode 201 and a collimating lens 202.
  • the laser diode 201 and the collimating lens 202 are sequentially arranged along a propagation direction of the light beam; the collimating lens 202 is configured to perform a laser beam emitted from the laser diode 201 Collimation.
  • the energy of the laser beam collimated by the collimating lens 202 is more concentrated, so that the emitted laser spot is very small.
  • FIG. 3 only exemplarily shows that the laser emitting unit 20 includes a collimating lens 202.
  • a collimating lens 202 may be provided between any two optical elements in the beam propagation path to reduce the divergence angle of the beam, or a collimating element is provided directly inside the laser diode 201, which is not described here. Strict restrictions.
  • the collimating lens 202 may be a spherical lens.
  • the specific frequency values of the three sets of high-frequency modulation signals are merely exemplary descriptions, and are not limited; at the same time, the number of groups of high-frequency modulation signals output by the high-frequency modulation signal output unit 10 is only an example. The description is not limitative, for example, it can also output two or more sets of high-frequency modulation signals. In other embodiments, the selection of the frequency value of the high-frequency modulation signal can be set according to the actual requirements of the laser radar system for the light transmitting module, which is not strictly limited here.
  • the optical transmission module provided in the embodiment of the present application outputs a preset high-frequency modulation signal of at least two different frequencies through the high-frequency modulation signal output unit 10, and loads the high-frequency modulation signal to the laser transmission unit so that the laser transmission unit emits at least two different types.
  • Frequency laser beam using two or more laser beams with different frequencies to detect the same distance, can ensure the measurement accuracy and ensure the measurement range.
  • the optical transmission module provided by the foregoing embodiment emits a laser beam modulated by a high-frequency modulation signal as a detection optical signal, or the optical transmission module emits a laser beam modulated by a high-frequency modulation signal as a detection optical signal and a reference optical signal.
  • the light signal is reflected by the target object to form an echo signal related to the distance of the target object.
  • phase method lidar system electrical components are used to modulate the frequency of the transmitted signal.
  • the modulation speed of the transmitted signal is slow, and the electromagnetic interference is serious, resulting in the slow detection speed of the existing phase method lidar system.
  • FIG. 4 is a schematic structural diagram of a light emitting unit according to an embodiment of the present disclosure.
  • the light emitting unit includes: a light source sub-unit 11, a high-frequency modulation sub-unit 12, and a difference frequency sub-unit 13; the light source sub-unit 11 is configured to emit an initial light beam; and the high-frequency modulation sub-unit 12 is configured to be mixed by light
  • the technology performs frequency modulation on the initial beam, and emits at least two different frequencies of high-frequency emission signals fg1 to fgm (where m is an integer greater than or equal to 2); the difference frequency sub-unit 13 is set to set any two different frequencies of high frequency.
  • the frequency transmission signal is subjected to differential frequency processing, and at least one low-frequency transmission signal fdi is issued (where i is an integer greater than or equal to 1); wherein, at least one high-frequency transmission signal fgj (where 1 ⁇ j ⁇ m) and at least A low-frequency emission signal fdi is used as a detection light signal and is emitted by a light emission unit.
  • the light source sub-unit 11 may include a laser configured to emit a laser beam with better collimation and energy concentration.
  • the laser may be a semiconductor laser, a fiber laser, a gas laser, or a solid-state laser.
  • the value of m is 4 and the value of i is up to 6.
  • the detection light signal emitted by the light transmitting unit includes at least one of the above-mentioned four types of high-frequency transmission signals and at least one of the above-mentioned six types of low-frequency transmission signals.
  • the detection optical signal may include a high-frequency transmission signal of 194 MHz and a low-frequency transmission signal of 4 MHz; alternatively, the detection optical signal may include high-frequency transmission signals of 194 MHz and 185 MHz, and low-frequency transmission signals of 4 MHz and 15 MHz.
  • the specific frequency values of the above-mentioned high-frequency transmission signals and low-frequency transmission signals are merely exemplary descriptions, and are not limited; at the same time, the selection of the frequency values of the detection optical signals is only exemplary descriptions, rather than limited.
  • the frequency values of the high-frequency transmission signal and the low-frequency transmission signal, and the selection of the frequency value of the detection light signal can be set according to the actual requirements of the light-emitting unit of the laser radar system.
  • the optical transmitting unit provided in the embodiment of the present disclosure modulates the initial light beam through the optical mixing technology through the high-frequency modulation sub-unit 12. Compared with the use of electrical components to modulate the initial light beam, the modulation speed is faster, and the high-frequency transmission is performed. The frequency of the signal is high. When the light emitting unit is applied to a lidar system, the detection accuracy of the lidar system can be improved.
  • the difference frequency subunit 13 obtains a low-frequency transmission signal through difference-frequency processing. Compared to directly obtaining the difference-frequency transmission signal by modulating the initial beam, there is no need to modulate a new low-frequency transmission signal according to a complete modulation process, thereby saving configuration.
  • the modulation speed of the low-frequency transmission signal is also faster. Therefore, the light emitting unit provided in the embodiment of the present disclosure accelerates the modulation speed of the detection optical signal, thereby increasing the transmission speed of the detection optical signal, thereby improving the detection speed of the lidar system.
  • the light transmitting unit sends at least one high-frequency transmitting signal and at least one low-frequency transmitting signal as detection light signals, that is, it emits at least two types of transmission signals with different frequencies as detection light signals (also known as multi-scale measuring technology,
  • the detection light signal of each frequency corresponds to a measuring ruler, wherein the high-frequency transmission signal corresponds to a fine ruler, the low-frequency transmission signal corresponds to a thick ruler, and the intermediate-frequency transmission signal corresponds to a medium ruler.
  • the higher the frequency of the detection optical signal the higher the detection accuracy of the lidar system, and the lower the frequency of the detection optical signal, the farther the detection distance of the laser radar system can be.
  • the optical transmitting unit uses a high-frequency transmission signal to ensure the detection accuracy of the lidar system, and a low-frequency transmission signal to ensure the detection range of the lidar system.
  • the data of the detection results of the high-frequency transmission signal and the low-frequency transmission signal are performed. Fusion, you can get a larger range and higher accuracy distance value.
  • this lidar system also has the characteristics of higher stability, longer detection distance and higher accuracy when measuring with traditional multi-scale measuring technology, which can ignore the influence of frequency shift in the entire system. .
  • the high-frequency modulation sub-unit 12 includes a frequency synthesizer; the frequency synthesizer is configured to load a preset at least two different high-frequency values onto the initial light beam emitted by the light source sub-unit through a direct digital frequency synthesis technique. To form at least two high-frequency transmission signals of different frequencies.
  • Direct Digital Frequency Synthesis is called third-generation frequency synthesis technology, which refers to a technology that generates a series of digital signals and converts them to analog signals through a digital-to-analog converter. That is, a new frequency synthesis technology that directly synthesizes the required waveform from the concept of "phase".
  • the light source sub-unit includes a low-power continuous laser diode.
  • the power of the light source sub-unit is low, on the one hand, it can prevent the light source sub-unit from generating more heat, which affects the performance of the electrical components in the light emitting unit and in the peripheral circuits; on the other hand, it can reduce the cost.
  • the light source sub-unit 11 further includes a collimating lens, and the low-power continuous laser diode and the collimating lens are sequentially arranged along the propagation direction of the light beam; the collimating lens is configured to collimate the initial light beam emitted by the low-power continuous laser diode. straight.
  • FIG. 5 is a schematic structural diagram of an optical signal detection module according to an embodiment of the present application.
  • the optical signal detection module includes a signal receiving unit 40 and a signal processing unit 50.
  • the at least two high-frequency modulation signals of different frequencies include a first high-frequency modulation signal and a second high-frequency modulation signal.
  • the first reference distance and the second reference distance may be fused to obtain the measurement distance of the target object, for example, the sum of the first reference distance and the second reference distance is used as the measurement distance of the target object.
  • the signal receiving unit 40 is connected to the laser emitting unit 20 and the reference signal emitting unit 30 in the light emitting module of the above embodiment, and the first high-frequency modulation signal is at least two outputs from the high-frequency modulation signal output unit 10.
  • the highest-frequency high-frequency modulation signal, and the second high-frequency modulation signal is the highest-frequency high-frequency modulation signal of at least two different-frequency high-frequency modulation signals output by the high-frequency modulation signal output unit 10.
  • the number of the second high-frequency modulation signals may be one or more, and the first reference signal is a signal transmitted by the reference signal transmitting unit 30 and modulated by the first high-frequency modulation signal.
  • the second reference signal is a signal modulated by the second high-frequency modulation signal emitted by the reference signal transmitting unit 30, and the first laser beam is a laser beam modulated by the first high-frequency modulation signal emitted by the laser transmitting unit 20, the first The two laser beams are laser beams emitted by the laser emitting unit 20 and modulated by the second high-frequency modulation signal.
  • the number of the second laser beam and the second reference signal are multiple, and multiple multiple Two high-frequency echo signals, and a second between each of the plurality of second high-frequency echo signals and a second reference signal corresponding to the second high-frequency echo signal can be obtained separately Phase difference, to obtain a second reference distance value according to a plurality of second phase differences and a first phase difference, for example, respectively according to a third phase between each second phase difference and the first phase difference in the plurality of second phase differences
  • the difference is obtained by obtaining a plurality of second reference distance values, and determining a measurement distance value of the target object according to the first reference distance value and the plurality of second reference distance values.
  • the first reference signal and the second reference signal are the first reference laser beam and the second reference laser beam, respectively, or the first reference electrical signal or the second reference electrical signal, respectively.
  • the signal receiving unit 40 is further configured to: receive the first local oscillator signal; convert the first high-frequency echo signal into a corresponding electrical signal, and convert the electrical signal corresponding to the first high-frequency echo signal to the first Mixing a local oscillator signal to obtain a first differential frequency measurement signal; converting the first reference laser beam into a corresponding electric signal and mixing the electric signal corresponding to the first reference laser beam with the first local oscillator signal, or The first reference electrical signal is mixed with the first local oscillator signal to obtain a first differential frequency reference signal; the second local oscillator signal is received, the second high-frequency echo signal is converted into a corresponding electric signal, and the second high-frequency signal is converted.
  • the electric signal corresponding to the echo signal is mixed with the second local oscillator signal to obtain a second differential frequency measurement signal;
  • the second reference laser beam is converted into a corresponding electric signal and the electric signal corresponding to the second reference laser beam is
  • Two local oscillator signals are mixed, or a second reference electrical signal is mixed with a second local oscillator signal to obtain a second differential frequency reference signal; wherein the first high-frequency modulation signal is a first main oscillator signal, and the second High frequency modulation No. is the second main oscillator signal.
  • the frequency of the first main oscillator signal and the first local oscillator signal differs by a preset frequency, and the frequency of the second main oscillator signal and the second local oscillator signal differs by a preset frequency; the signal processing unit 50 is set To obtain the first reference distance value of the target object according to the first phase difference between the first reference signal and the first high-frequency echo signal by comparing the first difference frequency measurement signal with the first difference frequency reference signal A first phase difference is obtained, and a first reference distance value of the target object is obtained according to the first phase difference.
  • the signal processing unit 50 is configured to obtain a second reference distance value of the target object according to the first phase difference and the second phase difference in the following manner. : Comparing the second difference frequency measurement signal with the second difference frequency reference signal to obtain a second phase difference; calculating a third phase difference between the second phase difference and the first phase difference; obtaining a target object based on the third phase difference The second reference distance value.
  • the first local oscillator signal is a local oscillator signal corresponding to the first main oscillator signal output by the modulation signal output unit 10
  • the second local oscillator signal is a local oscillator signal corresponding to the second main oscillation signal output by the modulation signal output unit 10.
  • the local oscillator signal is a local oscillator signal corresponding to the first main oscillator signal output by the modulation signal output unit 10
  • the signal receiving unit 40 is configured to receive a high-frequency echo signal reflected by the target object, convert the high-frequency echo signal into a high-frequency electrical signal, and then convert the high-frequency electrical signal into a low-frequency electrical signal;
  • the processing unit 50 is configured to convert a low-frequency analog electrical signal into a low-frequency digital signal and obtain phase information by using a correlation algorithm, thereby obtaining a distance value of the target object.
  • the signal receiving unit 40 actually adopts a phase difference frequency detection technology.
  • the phase difference frequency detection technology refers to a technology that converts a high frequency signal into a low frequency signal while maintaining phase information, and then uses the low frequency signal for phase detection.
  • FIG. 6 is a schematic diagram of a differential frequency phase detection technology according to an embodiment.
  • the high-frequency modulation signal output unit in the optical transmission module is equivalent to a high-frequency signal source.
  • Each group of high-frequency modulation signals output by the high-frequency signal source includes a main oscillation signal and a fixed difference from the main oscillation signal.
  • a local oscillator signal with a frequency (such as 1MHZ).
  • the first phase difference in the foregoing embodiment is taken as an example.
  • the first main oscillation signal is loaded on the laser beam and emitted to reach the target object, and the target object reflects the laser beam to the signal receiving unit of the optical signal detection module.
  • the signal receiving unit receives the first high-frequency echo signal obtained by the laser beam reflected by the target object, converts the first high-frequency echo signal into a high-frequency electrical signal, and performs the high-frequency electrical signal and the first local oscillator signal. Mixing to obtain a first low frequency measurement signal of low frequency.
  • the signal processing unit in the optical signal detection module is configured to obtain a first phase difference by comparing the first difference frequency measurement signal with a first difference frequency reference signal, and then obtain a first reference distance of the target object through the first phase difference. value.
  • the first difference frequency reference signal is an electric signal corresponding to the laser beam modulated by the first main oscillation signal or is obtained by mixing the electric signal modulated by the first main oscillation signal with the first local oscillation signal. of.
  • the principle of obtaining the second phase difference is the same as the principle of obtaining the first phase difference, and details are not described herein again.
  • a third phase difference between the second phase difference and the first phase difference can be calculated, and then a second reference distance of the target object is obtained, and the target is obtained according to the first reference distance and the second reference distance. The measured distance of the object.
  • the signal processing unit 40 may be further configured to obtain the third reference distance value of the target object according to the second phase difference, and The third reference distance value and the first reference distance value calculate a fourth reference distance value, and replace the first reference distance value with the fourth reference distance value.
  • an average value of the third reference distance value and the first reference distance value may be used as the fourth reference distance value, or the fourth reference distance value may be determined by looking up a table or the like.
  • the phase difference between the differential frequency measurement signal and the high-frequency echo signal is the phase of the local oscillator signal
  • the phase difference between the main oscillator signal and the differential frequency reference signal is also the phase of the local oscillator signal.
  • the phase difference of the difference frequency reference signal is equal to the phase difference between the high frequency echo signal and the main oscillation signal, that is, because the phase information remains unchanged, the high frequency signal can be converted to low frequency signal processing, and the low frequency signal is used for phase detection, which reduces the The requirement of the analog-to-digital conversion chip is to reduce the bandwidth of the post-processing circuit.
  • the phase detection accuracy is higher, which is conducive to improving the phase detection accuracy, that is, to improve the optical signal detection module for high-frequency echo signals. Processing accuracy.
  • the differential frequency phase detection technology reduces the frequency of the signal to be measured, thereby broadening the period of the signal to be measured, and because the low-frequency signal processing technology is more mature than the high-frequency signal processing technology. Therefore, converting high-frequency signals to low-frequency signal processing can improve phase measurement resolution and thereby improve phase detection accuracy.
  • the complete process of emitting and detecting the optical signal shown in FIG. 6 is: a main vibration signal generated by a high-frequency signal source With local signal Both are high-frequency signals, but with different phases and frequencies, and the difference frequency is a low-frequency signal.
  • Main vibration signal Loaded on the laser beam and emitted to the target object, reflected by the target object to form a high-frequency echo signal Received by the signal receiving unit.
  • This high-frequency echo signal And main signal The frequency is the same, the phase changes, and the amount of phase change is related to the distance of the target object.
  • the signal processing path for generating the difference frequency reference signal is: the main oscillation signal With local signal After mixing, and then passing through the low-pass filter LPF, a low-frequency difference frequency reference signal is generated
  • the signal processing unit compares the low-frequency difference frequency measurement signals Difference frequency reference signal with low frequency
  • the phase information of the difference frequency measurement signal and the difference frequency reference signal are detected and the phase difference is calculated.
  • the phase difference value and the high frequency main oscillation signal With high-frequency echo signals The phase difference is the same. Therefore, the phase difference information carried by the high-frequency signal can be obtained by subsequently processing the low-frequency signal, thereby finally obtaining the measurement distance value of the target object.
  • the signal processing unit uses digital phase detection to detect phase information.
  • the digital phase detection method is a method of digitizing a signal to be detected and then identifying phase information of the signal.
  • FIG. 7 is a schematic flowchart of a digital phase detection method provided by an embodiment of the present application. Referring to FIG. 7, the flow of the digital phase detection method includes: converting an analog signal x (t) to be detected into a digital signal x (n) (where n is a positive integer) through analog-to-digital conversion, and then passing through a correlation algorithm. Get phase information.
  • the core processing unit of the digital phase detection method may be a computer or a microprocessor.
  • the above-mentioned digital phase detection method does not depend on the circuit, and the entire phase detection process is completely digitized, avoiding the influence of electromagnetic interference existing in the circuit on the phase detection result, so it has good anti-interference ability, and further has high phase detection accuracy. At the same time, the operation speed is fast and the volume is small. Applying the digital phase detection method to the lidar system can improve the speed and accuracy (also called resolution) of the lidar system's measuring distance.
  • the “high frequency” mentioned in the above embodiment refers to a frequency with a unit level of 100 MHz (for example, 100MHZ or more), and the “low frequency” mentioned in this application refers to a frequency with a unit level of MHz (for example, 1MHZ). ⁇ 10MHZ).
  • the signal receiving unit 40 includes a photodetector.
  • This setting is equivalent to using the photodetector as a component to realize the three functions of receiving, converting, and mixing the first reference signal, the second reference signal, the first high-frequency echo signal, and the second high-frequency echo signal. Therefore, the number of components in the optical signal detection module is reduced, the structure of the optical signal detection module is simplified, and the volume of the optical signal detection module is reduced.
  • the application of photodetectors in lidar systems is conducive to the miniaturization design of lidar systems.
  • the above-mentioned photodetector is only a design manner for the signal receiving unit, and is not limited.
  • the functions of receiving, converting, and mixing may also be implemented by two or three components. At this time, the functions implemented by multiple components are relatively independent. When an abnormal signal is detected, it can be quickly checked and the cost of replacing components is low.
  • FIG. 8 is a schematic optical structure of a laser emitting unit and a signal receiving unit according to an embodiment.
  • the signal receiving unit 40 may further include a receiving lens 213 and a filter 214, and the receiving lens 213, the filter 214, and the photodetector 211 are sequentially arranged along the propagation direction of the light beam; the receiving lens 213 is set to set the first height The frequency echo signal and the second high frequency echo signal are focused to the photodetector 211; the filter 214 is configured to pass the first high frequency echo signal and the second high frequency echo signal to filter out interference signals of other wavelengths, That is, the interference signal will not be detected by the photodetector 211, thereby improving the signal-to-noise ratio of the optical signal detection module. Applying the filter 214 to a lidar system can increase the detection range of the system under strong light.
  • the echo signal generated by the reflection of the target object usually diverges. Focusing the divergent echo signal to the photodetector 211 through the receiving lens 213 can enhance the echo signal received by the photodetector. Strength of.
  • a side of the receiving lens 213 near the laser emitting unit 20 further includes a short-distance light path compensating mirror 2131 attached to the light-emitting surface side of the receiving lens 213.
  • the short-distance light path compensating mirror 2131 is set to target objects at a short distance
  • the echo signal generated by the reflection is focused on the photodetector 211, thereby reducing the blind zone caused by the non-coaxial system.
  • the blind zone of the lidar can be reduced below 20 cm.
  • the signal processing unit 50 includes an operational amplifier, an analog-to-digital converter, and a field programmable gate array; the input end of the operational amplifier is electrically connected to the signal receiving unit, the output end of the operational amplifier and the input end of the analog-to-digital converter. Electrically connected, the output of the analog-to-digital converter is electrically connected to the field programmable gate array; the operational amplifier is set to transmit the first differential frequency measurement signal, the first differential frequency reference signal, and the second differential frequency measurement signal, respectively, transmitted by the signal receiving unit.
  • the analog-to-digital converter is configured to respectively amplify the first difference frequency measurement signal, the first difference frequency reference signal, the second difference frequency measurement signal, and the second difference frequency reference signal amplified by the operational amplifier. Converting the analog signal into a digital signal; the field programmable gate array is configured to compare the digital signal corresponding to the first differential frequency measurement signal with the digital signal corresponding to the first differential frequency reference signal to obtain a first phase difference, and Calculate a first reference distance value of the target object according to the first phase difference; compare the digital signal corresponding to the second difference frequency measurement signal with the second Compare digital signals corresponding to frequency reference signals to obtain a second phase difference; calculate a third phase difference between the second phase difference and the first phase difference, and calculate a second reference distance value of the target object according to the third phase difference; A measurement distance value of the target object is determined according to the first reference distance value and the second reference distance value.
  • the optical signal detection module further includes: a power supply unit, a microprocessor unit, and a high-voltage adjustment unit; the power receiving end of the signal processing unit and the power receiving end of the microprocessor unit are electrically connected to the power supply unit, respectively.
  • the first control end of the microprocessor unit is electrically connected to the signal processing unit, and the second control end of the microprocessor unit is electrically connected to the signal receiving unit through a high voltage adjustment unit;
  • the power supply unit is provided to the signal processing unit and the microprocessor unit.
  • Power supply; the microprocessor unit is configured to perform control processing on the signal processing unit, and is further configured to adjust the voltage applied to the signal receiving unit through a high voltage adjusting unit so that the signal receiving unit receives echo signals of different strengths.
  • the optical signal detection module further includes a temperature detection unit, a high voltage detection unit, and a standard voltage detection unit.
  • the output of the temperature detection unit, the output of the high voltage detection unit, and the output of the standard voltage detection unit are respectively The input end of the processor unit is electrically connected; the temperature detection unit is set to detect the temperature value of the signal receiving unit, the high voltage detection unit is set to detect the high voltage value of the signal receiving unit, and the standard voltage detection unit is set to the standard voltage value of the detection signal receiving unit;
  • the microprocessor unit is further configured to adjust a voltage output by the high-voltage regulating unit according to a temperature value, a high-voltage value, or a standard voltage value.
  • FIG. 9 is a structural block diagram of an optical system according to an embodiment.
  • the optical system provided in this embodiment may include a light transmitting module 60 provided in any of the foregoing embodiments and a signal receiving unit 70 provided in any of the foregoing embodiments.
  • the signal receiving unit 70 is connected to the light transmitting module 60.
  • the layout of the optical path between the light transmitting module 60 and the signal receiving unit 70 includes: a coaxial system, a dual transmitting single receiving system, a single transmitting single receiving system, or a dual transmitting dual receiving system.
  • the present application also provides a laser radar, which includes a light transmitting module and a light signal detecting module provided in any of the foregoing embodiments. Therefore, the laser radar provided by the embodiment of the present application has the beneficial effects of the above-mentioned light transmitting module and also the beneficial effects of the above-mentioned optical signal detection module. For the beneficial effects not shown here in detail, reference may be made to the content of the light emitting module and the light signal detecting module in the foregoing embodiments, and details are not described herein again.
  • FIG. 10 is a schematic diagram of a hardware principle of a laser radar provided by an embodiment. The principle of laser light emission and detection is described below in conjunction with the hardware structure of the laser radar.
  • the laser radar light transmitting module includes three phase-locked loops, and the three phase-locked loops switch frequencies through a switch.
  • the high-frequency modulation signal output by each phase-locked loop includes a main oscillation signal and a local oscillation signal.
  • the first main oscillation signal and the first local oscillation signal, and the second main oscillation signal and the second local oscillation signal are respectively output through two phase-locked loops as an example.
  • a phase-locked loop is selected through a switch to output a first main oscillation signal and a first local oscillation signal.
  • the first main oscillation signal is selectively loaded on the first laser diode or the second laser diode after being amplified by the amplifier circuit 1. After the first main oscillation signal is loaded on the first laser diode, a first laser beam that is frequency-modulated corresponding to the first main oscillation signal is emitted. After the first laser beam reaches the target object through the external optical path, it is reflected back and emitted The laser beam is the first high-frequency echo signal. Since the emitted laser beam is modulated by a high-frequency modulation signal, the echo signal also belongs to a high-frequency signal.
  • the optical signal detection module of the lidar includes a photodetector. After detecting the first high-frequency echo signal, the photodetector first converts the first high-frequency echo signal into a high-frequency electrical signal.
  • the high-frequency electrical signal is an electrical signal that is demodulated after the first laser beam modulated by the first main oscillation signal travels back and forth to the target object. There is a delayed phase difference between the first laser beam and the first main oscillation signal. Mixing the first high-frequency electrical signal with the first local oscillator signal to obtain a low-frequency electrical signal (that is, the first differential frequency measurement signal in the above embodiment).
  • the low-frequency electrical signal is amplified by an amplifier circuit 3 and converted by an analog-to-digital converter, and a low-frequency digital electrical signal (represented by eD) is output to a Field-Programmable Gate Array (FPGA).
  • FPGA Field-Programmable Gate Array
  • the first main oscillation signal may be switched and loaded to a second laser diode, and a modulated first reference laser beam is emitted and reaches an photodetector through an internal optical path.
  • the first reference laser beam passes through the The photoelectric conversion of the photodetector is then mixed with the amplified first local oscillator signal to obtain a low-frequency first difference frequency reference signal.
  • the low-frequency first difference frequency reference signal is also amplified and analog-to-digital converted.
  • a low-frequency reference digital electrical signal (represented by e0) is obtained as a phase comparison. Since e0 does not pass through the outer optical path, there is no phase delay in e0 like eD. Therefore, the field programmable gate array performs phase comparison between eD and e0 to obtain a first phase difference for obtaining a first reference distance value of the target object, and then obtains a first reference distance value.
  • the field programmable gate array can obtain a second phase difference, and then calculate a third phase difference between the second phase difference and the first phase difference, and obtain a second reference distance value according to the third phase difference, and then according to the first The reference distance value and the second reference distance value obtain a measured distance value of the target object.
  • a switching switch configured to select a phase-locked loop is controlled by the field programmable gate array.
  • Three phase-locked loops can output three different sets of high-frequency modulation signals, and three sets of high-frequency modulation signals.
  • the frequency values are relatively concentrated, that is, the difference between the frequency values of each two groups is small.
  • a unified high-frequency processing circuit can be used, which makes the hardware circuit design simple.
  • the group with the highest frequency value exemplarily, the frequency of the main oscillator signal is 193MHZ and the frequency of the local oscillator signal is 192HZ
  • the group with the highest frequency value exemplarily, the frequency of the main oscillator signal is 193MHZ and the frequency of the local oscillator signal is 192HZ
  • the other two groups (exemplarily, the main oscillator signal frequency is 187MHZ, the local oscillator signal frequency is 186MHZ and the main oscillator signal frequency is 167MHZ, and the local oscillator signal frequency is 166MHZ) are used as auxiliary rulers.
  • the difference frequency (for example, the difference frequency may be 20MHZ and 6MHZ, respectively) can be used as the medium and thick scales of the extended range to ensure the measurement range of the system. It can be understood that if only two phase-locked loops are set, the group with a high frequency value serves as a fine ruler, and the other group serves as an auxiliary ruler. The difference between the fine ruler and the auxiliary ruler can be used as a coarse ruler for extended range.
  • the configuration time of the low-frequency scale is reduced, so the detection speed of the lidar is improved.
  • the frequency of the modulated detection optical signal is relatively concentrated, it is convenient for the circuit to process signals of similar frequencies, so that it is not necessary to separately design circuits for high-frequency signals and low-frequency signals, so the circuit design is difficult and the circuit structure is simple.
  • the amplifier circuit 3 is an operational amplifier that amplifies weak signals, thereby improving the signal-to-noise ratio of the signals.
  • the operational amplifier may adopt a multi-stage amplification circuit.
  • the first stage is a current mode signal and the voltage mode signal processing, and the latter stages use low noise, high speed, and high precision signal amplification processing.
  • the input end of the operational amplifier is electrically connected to the output end of the photodetector, the output end of the operational amplifier is electrically connected to the input end of the analog-to-digital converter, and the output end of the analog-to-digital converter is electrically connected to the field programmable gate array. .
  • the analog-to-digital converter 222 is configured to quickly acquire signals
  • the field programmable gate array is configured to perform high-speed phase frequency calculations on the signals collected by the analog-to-digital converter (for example, a smoothing filter may be integrated on the FPGA).
  • a smoothing filter may be integrated on the FPGA.
  • Sub-units and 260-point fast Fourier transform sub-units so that the lidar measurement speed is fast, the anti-interference ability is high, and the precision is high.
  • the field programmable gate array can discard unstable data and only collect stable data for processing, which results in good data consistency and high data stability.
  • the analog-to-digital converter set for high-speed signal acquisition and the FPGA set for high-speed phase calculation used by lidar can adopt professional tape-out technology, so that the product has higher integration, smaller area, reliability and stability Higher, thus lower cost and easy miniaturization.
  • the Boundary Scan test technology of the Joint Test Working Group (JTAP) can reduce the test cost, shorten the test time, and shorten the time to market.
  • the lidar further includes a power supply unit, a microprocessor (Microcontroller Unit, MCU), and a high-voltage regulating unit;
  • the power supply unit is electrically connected to the microprocessor, FPGA, first laser diode, and second laser diode to realize power supply
  • the first control end of the microprocessor is electrically connected to the FGPA to achieve a variety of data interaction and program control
  • the second control end of the microprocessor is electrically connected to the photodetector through a high voltage adjustment unit to realize the voltage of the photodetector. Adjust so that the photodetector can amplify a variety of different reflected echo signals.
  • the power supply unit can convert the external power supply to the voltage required by the multiple component parts of the module according to the requirements of the module and power the multiple component parts separately.
  • the microprocessor can control the power supply unit to achieve independent power supply for multiple components in the laser radar.
  • the high voltage adjustment unit can adjust the magnitude of the high voltage (HV) applied to the photodetector by means of Pulse Width Modulation (PWM).
  • PWM Pulse Width Modulation
  • the lidar further includes a temperature detection unit (AD_NTC), a high voltage detection unit (AD_HV), and a standard voltage detection unit (AD_VBAS).
  • the output end is respectively electrically connected to the input end of the microprocessor; the temperature detection unit is set to detect the temperature value of the photodetector, the high voltage detection unit is set to detect the high voltage value of the photodetector, and the standard voltage detection unit is set to detect the photodetector's Standard voltage value; the microprocessor is also set to adjust the output voltage according to the temperature value and various feedback signals.
  • a temperature detection unit, a high voltage detection unit, and a standard voltage detection unit are designed to monitor the use environment of the photodetector, and according to the environmental information (including temperature value and high voltage value) And the standard voltage value) adjusts the voltage value applied to the photodetector.
  • the optical signal detection module is applicable to a variety of different environments.
  • a constant current and constant voltage and constant power driving circuit (not shown in FIG. 10) is also used to provide a stable power supply system for the laser emitting unit (including the first laser diode and the second laser diode).
  • the voltage feedback of the emitting unit stabilizes the working point of the laser emitting unit.
  • switching is performed by a high-speed switch, which greatly improves the frequency switching time.
  • SW high-speed switch
  • the optical path system layout of the lidar includes a coaxial system, a dual-transmit single-receive system, a single-transmit single-receive system, or a dual-transmit dual-receive system.
  • both the coaxial system and the single-transmit-single-receive system can use relatively few components, so the cost is low; at the same time, the structure is compact and the volume is small.
  • the reference beam (the beam corresponding to the reference optical signal) and the detection beam (the beam corresponding to the detection optical signal) do not overlap, and the optical signal has high stability.
  • FIG. 11 is a coaxial optical system provided by an embodiment of the present application.
  • the detection light signal emitted by the laser emitting unit 31 is sequentially irradiated onto the surface of the target object 32 through the small hole 34Q in the middle of the reflector 34 and the middle portion of the lens 33, and is reflected by the target object 32 to form an echo signal.
  • the echo signal is focused by the lens 33 and then reflected by the reflecting mirror 34 to be focused on the surface of the photodetector 35 and received by the photodetector 35.
  • FIG. 12 is a dual-emitting single-receiving optical system provided by an embodiment of the present application.
  • the laser emitting unit includes an outer light source 311 and an inner light source 322.
  • the detection light signal emitted by the external light source 311 irradiates the surface of the target object 32, is reflected by the target object 32, and forms an echo signal.
  • the echo signal is focused on the surface of the photodetector 35 through the lens 33 and received by the photodetector 35.
  • the light signal emitted by the internal light source 312 also irradiates the surface of the photodetector 35 and is received by the photodetector 35.
  • the external light source 311 and the internal light source 312 may be included in the same laser emitting unit.
  • the frequency of the detection optical signal (exemplified as 193 MHz) emitted by the external light source 311 and the frequency of the reference optical signal (exemplified as 192 MHz) emitted by the internal light source 312 are different from each other by a fixed value (1 MHz), thereby realizing differential frequency phase detection.
  • the embodiment shown in FIG. 10 includes a dual-emitting single-receiving optical system.
  • FIG. 13 is a dual-emitting dual-receiving optical system provided by an embodiment of the present application.
  • the laser emitting unit includes an external light source 311 and an internal light source 312, and the signal receiving unit includes a first photodetector 351 and a second photodetector 352.
  • the detection light signal emitted by the external light source 311 irradiates the surface of the target object 32, is reflected by the target object 32, and forms an echo signal.
  • the echo signal is focused on the surface of the first photodetector 351 through the lens 33 and received by the first photodetector 351.
  • the light signal emitted by the internal light source 312 directly irradiates the surface of the second photodetector 352 and is received by the second photodetector 352.
  • the optical path and circuit for obtaining the echo signal and the optical path and circuit for obtaining the difference frequency reference signal are independent, and they do not affect each other.
  • the optical signal is more stable and the stability of the electrical signal is higher.
  • FIG. 14 is a single-emitting single-receiving optical system provided by an embodiment of the present application.
  • the frequency-modulated electrical signal 36 is used to control the laser emitting unit 31 to emit a detection light signal.
  • the detection light signal is irradiated to the surface of the target object 32 and is reflected by the target object 32 to form an echo signal.
  • the echo signal is focused on the surface of the photodetector 35 through the lens 33 and received by the photodetector 35.
  • the photodetector 35 receives a frequency-modulated electrical signal 36. Therefore, the process of converting the modulated electrical signal into a reference optical signal and then converting it into a reference electrical signal is omitted, thereby saving time for signal processing and increasing the speed of signal processing.
  • the laser radar further includes an angle detection unit, and the angle detection unit is electrically connected to the signal processing unit in the optical signal detection module; the angle detection unit is configured to detect the angle value of the rotation of the laser radar; and the signal processing unit is further configured to The amount of change in the distance value is related to the amount of change in the angle value.
  • the light emitting module can be rotated within a range of 360 degrees, and the angle detection unit is set to detect the rotation angle of the light emitting module, so that the lidar can achieve two-dimensional horizontal 360 degrees within a range of 0.01 meters (m) to 100 meters. Scan and detect to obtain two-dimensional position information of the surrounding environment.
  • the scanning frequency of the lidar is 3 Hz (Hz) to 10 Hz, and the exemplary embodiment can be understood as that the light emitting module can rotate 360 degrees 3 times to 10 times per second; if the optical system in the lidar For a coaxial system, the optical signal detection module and the light transmitting module rotate synchronously.
  • the detection frequency of the laser radar is 8kHz-20kHz, which can detect 8k-20k distance values per second.
  • the angular resolution of the lidar system is 0.18 ° -1 °, that is, the smallest angle value that can be resolved by the angle detection unit is 0.18 ° -1 °.
  • the detection accuracy of lidar can reach millimeter level, so this lidar can be widely used in laser scanning systems, monitoring systems, space mapping (space modeling), collision avoidance, robotics, environmental detection and military reconnaissance.
  • the Lidar rotation transmission method includes a brushed motor, a brushless motor, or wireless power supply.
  • the lidar further includes a communication unit; the communication unit is electrically connected to the signal processing unit in the optical signal detection module; the communication unit is configured to set the distance value, the angle value, and the change amount of the distance value obtained by the signal processing unit with At least one of the correlations between the changes in the angle value is transmitted to a feedback signal receiving unit.
  • the feedback signal receiving unit may be a light transmitting module, and the light transmitting module adjusts the intensity of the detection light signal sent by the received information to be suitable for different detection environments.
  • the feedback signal receiving unit may also be a microcontroller, and the microcontroller is configured to further process the detected data, so as to implement monitoring of the surrounding environment or automation control.
  • the communication mode of the communication unit may include: optical communication, Bluetooth communication, or WIFI communication.
  • data transmission through wireless transmission can reduce the number of external interfaces of the lidar, which simplifies the structure of the lidar on the one hand; on the other hand, it can make the lidar's application range wider, and the example can be applied to humidity Or water environment.
  • FIG. 15 is a schematic cross-sectional structure diagram of a motor-driven belt-driven, slip-ring powered lidar provided by an embodiment of the present application.
  • the laser radar includes a motor 411, a belt 412, an angle detection unit 413, a photodetector 414, a receiving lens 415, a bearing 416, and a slip ring 417.
  • the motor 411 drives the rotation module (including the photodetector 414 and the receiving lens 415, and also includes a light emitting module not shown in FIG. 15) through the belt 412 to rotate.
  • the angle detection unit 413 may be a photoelectric converter for positioning the position of a code disc (not shown in FIG. 15), thereby detecting the rotation angle of the rotation module.
  • the echo signal reflected by the target object passes through the receiving lens 415 and is focused on the surface of the photodetector 414 and is received by the photodetector 414.
  • the slip ring 417 is used to power the rotation module and transmit data
  • FIG. 16 is a schematic cross-sectional structure diagram of an electromagnetic induction power supply and wireless communication laser radar provided by an embodiment of the present application.
  • the lidar includes a laser emitting unit 421, a collimating lens 422, a light shielding tube 423, a light transmitting cover 424, a receiving lens 425, a photodetector 426, a signal transmission coupling coil 4271, an electric transmission coupling coil 4272, and a bearing 428 , Motor 429, and motor control 420.
  • the laser emitting unit 421 may be a laser.
  • the light beam emitted by the laser emitting unit 421 passes through the collimating lens 422 to form a detection light signal, and is emitted after the light transmitting cover 424, and is irradiated on the surface of the target object to form an echo signal; the echo signal passes through the light transmitting cover 424 and the receiving lens 425 After focusing on the photodetector 426.
  • the light-shielding tube 423 is used to isolate the detection optical signal and the echo signal, so that the two optical signals do not interfere with each other, thereby improving detection accuracy.
  • the motor 429 is driven by the motor control 420 to rotate the rotary module.
  • the electric transmission coil 4272 implements power supply by electromagnetic induction, and the signal transmission coupling coil 4271 implements data transmission by wireless communication.
  • FIG. 17 is a schematic cross-sectional structure diagram of a lidar of a wireless power supply and optical communication system provided by an embodiment of the present application.
  • the lidar includes a light transmitting module 431, a first wireless signal transmission module 432, a bearing 433, a wireless power transmission module 434, a second wireless signal transmission module 435, a motor control 436, a light signal detection module 437, and an angle detection Unit 438 and motor 439.
  • This lidar uses wireless power.
  • the first wireless signal transmission module 432 and the second wireless signal transmission module 435 work together to implement data transmission by means of optical communication. Except for the power supply mode and the communication mode, for other working processes, reference may be made to the description of FIG. 15 and FIG. 16, and details are not described herein again.
  • FIG. 15 to FIG. 17 only exemplarily show the structures of three different types of laser radars, but are not limited to the embodiments of the present application.
  • a transmission method, a communication method, and a relative position relationship between a plurality of components may be selected according to actual needs.
  • FIG. 18 is a schematic diagram of a working procedure of a laser radar provided by an embodiment of the present application.
  • a working procedure of the lidar includes the following steps.
  • Step S5110 The motor is powered on and rotated.
  • the rotation of the motor can drive the rotation module (mainly including the light emitting module and the light signal detection module) to rotate, so that the lidar can realize scanning detection within a 360-degree range.
  • Step S5120 Transmit a detection light signal.
  • the detection light signal may be an infrared laser beam modulated by a high-frequency modulation signal.
  • the detection light signal is emitted by the laser emitting unit.
  • Step S5130 Receive an echo signal.
  • the echo signal is a reflected light signal formed after the detection light signal emitted by the light transmitting module is reflected by the target object.
  • the echo signal is received by a signal receiving unit in the optical signal detection module.
  • Step S5140 Calculate the distance according to the phase difference.
  • the phase difference between the detection light signal and the echo signal is related to the distance of the target object.
  • the optical signal detection module provided in the foregoing implementation manner can implement high-speed data calculation, thereby enabling rapid processing of optical signals, and thereby quickly obtaining a detection distance.
  • Step S5150 Upload the data.
  • This step may include feeding back the data obtained in step S5140 to the optical transmitting module performing step S5120 and the optical signal detecting module performing step S5130.
  • a closed-loop self-feedback adjustment system is formed, and the intensity of the detection optical signal and the echo signal is adjusted to make the detection result more accurate.
  • this step may also include uploading the data obtained in step S5140 to a feedback signal receiving unit, that is, performing step S5160.
  • Step S5160 the data is output.
  • the two-dimensional detection point cloud image data can be displayed, and the output data can also be used as a control instruction to realize automatic control.
  • FIG. 19 is a schematic flowchart of a laser radar algorithm according to an embodiment of the present application.
  • the working procedure of the lidar includes the following steps.
  • Step S5200 Start measurement.
  • remote control can be performed by pressing the start button in the lidar, clicking the start button on the lidar's screen, or by wireless transmission.
  • Step S5210 Frequency configuration.
  • this step is performed by a light transmitting module, and a high frequency modulated signal outputted by a high frequency modulated signal output unit is loaded into a laser emitting unit to modulate a detection optical signal having a frequency that meets a requirement.
  • Step S5220 temperature, high voltage, and Bias point detection.
  • This step is performed by the optical signal detection module.
  • the optical signal detection module By detecting the application environment of the lidar, for example, the application environment parameters of the signal receiving unit, and subsequently adjusting the voltage applied to the signal receiving unit, that is, performing step S5230, which can improve different uses. The accuracy of the detection results under the environment, so that the lidar can be applied to more test environments.
  • step S5200 and before step S5220, in order to realize lidar rotation the following three steps may be included.
  • Step S5310 Start the radar motor.
  • the rotation of the motor can rotate the light transmitting module and the signal receiving unit (or the entire optical signal detection module) in the laser radar system.
  • Step S5320 Control the rotation speed.
  • the rotation speed can be adjusted to a preset range according to the density of the detection points in each 360-degree range or the actual needs of the detection range.
  • a higher rotation speed may be used; when the requirement for the density of detection points in each 360-degree range is higher, a lower rotation speed may be used.
  • control of the rotation speed may be implemented by adjusting a knob for controlling the rotation speed or entering a required rotation speed value.
  • Step S5330 Measure the code wheel signal.
  • This step is performed by the angle detection unit. By performing this step, it is possible to detect the rotation angle and monitor the rotation speed.
  • step S5230 is performed.
  • Step S5230 High voltage adjustment.
  • step S5230 the receiving unit is in a working state suitable for the use environment. At this time, it starts to send and receive signals, including the following steps.
  • Step S5410 frequency selection 1.
  • the choice of frequency can be realized by selecting the phase-locked loop by the FPGA control switch.
  • Step S5420 Switch to the internal light path.
  • the switching of the inner optical path and the outer optical path can also be realized by a switch.
  • Step S5430 Collect internal light path signals.
  • step S5440 the signal is processed to calculate the internal optical path phase.
  • Step S5450 Switch to the external light path.
  • Step S5460 Collect external light path signals.
  • Step S5470 Signal processing, calculating the phase of the external optical path.
  • Step S5480 Calculate the phase difference 1.
  • Step S5490 Calculate the distance measured by the ruler 1.
  • the distance measured by one ruler is not accurate enough and requires the cooperation of multiple rulers. Therefore, it also includes the detection of the distance of the target object by at least one detection light signal with a frequency different from step S5410, including the following: step.
  • Step S5510 frequency selection 2.
  • the phase-locked loop can be selected by the FPGA control switch to achieve frequency selection.
  • Step S5520 Switch to the internal light path.
  • Step S5530 Collect internal light path signals.
  • step S5540 the signal processing is performed to calculate the internal optical path phase.
  • Step S5550 Switch to the external light path.
  • Step S5560 Collect external light path signals.
  • Step S5570 signal processing, and calculating the phase of the external optical path.
  • Step S5580 Calculate the phase difference 2.
  • Step S5590 Calculate the distance measured by the ruler 2.
  • step S5610 is performed.
  • Step S5610 the measuring rule is connected.
  • connection of the ruler refers to combining the distance measured by the aforementioned ruler 1 with the distance measured by the ruler 2 and, on the other hand, the difference between the ruler 1 and the ruler 2 to calculate a new Distance value.
  • the distance calculated by the coarse ruler is 100m
  • the ruler 2 is a fine ruler
  • the distance measured by the fine ruler is 0.8m.
  • the resulting distance was 100.8 m.
  • Step S5620 Calculate the final distance.
  • the distance obtained in step S5610 is usually a relative distance value and a distance error value. There is a one-to-one correspondence between the relative distance value and the absolute distance value. Therefore, the absolute distance value can be obtained by looking up the table. Value as the final distance.
  • Step S5630 End the measurement.
  • the measurement can be ended by means of buttons, keys or remote control; or the measurement can be automatically ended after setting a threshold range set by the lidar detection.
  • the lidar can be in standby or powered off.

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Abstract

一种光发射模块、光信号检测单元、光学系统和激光雷达系统。光发射模块包括：高频调制信号输出单元（10），设置为输出预设的至少两个不同频率的高频调制信号；激光发射单元（20），与高频调制信号输出单元（10）连接，设置为发射分别经至少两个不同频率的高频调制信号调制后的至少两个不同频率的激光光束；参考信号发射单元（30），与高频调制信号输出单元（10）连接，设置为发射分别经至少两个不同频率的高频调制信号调制后的至少两个不同频率的参考信号。

Description

光发射模块、光发射单元、光信号检测模块、光学系统和激光雷达系统
本申请要求在2018年06月11日提交中国专利局、申请号为201810595306.4的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及激光测距技术领域，例如涉及一种光发射模块、光发射单元、光信号检测模块、光学系统和激光雷达系统。
背景技术
激光雷达系统，是以发射激光光束(探测光信号)探测目标的位置、速度等特征量的雷达系统。激光雷达系统可探测目标物体的有关信息，如目标物体的方位、距离、高度、速度、姿态、甚至形状等参数，从而对目标物体进行探测、跟踪和识别。激光雷达系统是汽车自动驾驶、机器人定位导航、空间环境测绘和安保安防等领域必不可少的核心传感器。在实际应用中，按照原理不同，激光雷达系统可分为：三角法激光雷达系统，基于时间飞行的脉冲法激光雷达系统，相位法激光雷达系统。其中，相位法激光雷达系统是通过将一定频率的正弦调制信号加载到激光器上，利用发射信号(探测光信号)和接收信号(回波信号)之间的相位差所含有的距离信息来实现对被测目标物体的距离的测量。
但是，探测光信号的频率越高，探测精度越高，探测量程越小，探测光信号的频率越低，探测精度越低，探测量程越大。相关技术中无法实现对目标物体进行高探测精度，大探测量程的距离测量。
发明内容
本申请提供一种光发射模块、光发射单元、光信号检测模块、光学系统和激光雷达系统，实现对目标物体的进行高探测精度，大探测量程的距离测量。
第一方面，本申请实施例提出一种光发射模块，该光发射模块包括：
高频调制信号输出单元，设置为输出预设的至少两个不同频率的高频调制信号；
激光发射单元，与所述高频调制信号输出单元连接，设置为发射分别经所述至少两个不同频率的高频调制信号调制后的至少两个不同频率的激光光束；
参考信号发射单元，与所述高频调制信号输出单元连接，设置为发射分别经所述至少两个不同频率的高频调制信号调制后的至少两个不同频率的参考信 号。
第二方面，本申请实施例提供一种光发射单元，包括：光源子单元、高频调制子单元和差频子单元；
所述光源子单元设置为发出初始光束；
所述高频调制子单元设置为通过光混频技术对所述初始光束进行频率调制，发出至少两种不同频率的高频发射信号；
所述差频子单元设置为将任意两种不同频率的高频发射信号进行差频处理，发出至少一种低频发射信号；
其中，至少一种所述高频发射信号和至少一种所述低频发射信号作为探测光信号，由所述光发射单元发出。
第三方面，本申请实施例提供一种光信号检测模块，该光信号检测模块包括：信号接收单元和信号处理单元，所述信号接收单元与所述信号处理单元电连接；
所述信号接收单元设置为接收第一参考信号、第二参考信号、第一高频回波信号和第二高频回波信号；其中，所述第一参考信号为经第一高频调制信号调制后的参考信号，所述第二参考信号为经第二高频调制信号调制后的参考信号；所述第一高频回波信号为第一激光光束被目标物体反射后的激光光束，所述第二高频回波信号为第二激光光束被所述目标物体反射后的激光光束；所述第一激光光束为经所述第一高频调制信号调制后的激光光束，所述第二激光光束为经所述第二高频调制信号调制后的激光光束；所述第一高频调制信号的频率大于所述第二高频调制信号的频率；
所述信号处理单元设置为：根据所述第一参考信号与所述第一高频回波信号之间的第一相位差获取所述目标物体的第一参考距离值；根据所述第一相位差与第二相位差获取所述目标物体的第二参考距离值，并根据所述第一参考距离值和所述第二参考距离值确定所述目标物体的测量距离值；其中，所述第二相位差为所述第二参考信号与所述第二高频回波信号之间的相位差。第四方面，本申请实施例提供了一种光学系统，该光学系统包括第一方面提供的光发射模块，也包括第二方面提供的光信号检测模块中的信号接收单元。
第五方面，本申请实施例还提供了一种激光雷达系统，该激光雷达系统包括第一方面提供的光发射模块，也包括第二方面提供的光信号检测模块。
本申请实施例提供的光发射模块通过高频调制信号输出单元输出预设至少两个不同频率的高频调制信号，并加载到激光发射单元上以使激光发射单元发射出至少两个不同频率的激光光束，采用两个以上不同频率的激光光束去探测 同一距离，可以在保证测量精度的同时保证测量范围。
附图说明
图1是本申请实施例提供的一种光发射模块的结构示意图；
图2是本申请实施例提供的一种频率合成器的工作原理示意图；
图3是本申请实施例提供的一种激光发射单元的结构示意图；
图4是本申请实施例提供的一种光发射单元的结构示意图；
图5是本申请实施例提供的一种光信号检测模块的结构示意图；
图6是本申请实施例提供的一种差频鉴相技术原理示意图；
图7是本申请实施例提供的一种数字鉴相技术的流程示意图；
图8是本申请实施例提供的一种激光发射单元和信号接收单元的结构示意图；
图9是本申请实施例提供的一种光学系统的结构框图；
图10是本申请实施例提供的一种激光雷达的硬件原理示意图；
图11是本申请实施例提供的一种同轴光学系统；
图12是本申请实施例提供的一种双发射单收光学系统；
图13是本申请实施例提供的一种双发射双收光学系统；
图14是本申请实施例提供的一种单发射单收光学系统；
图15是本申请实施例提供的一种电机皮带传动、滑环供电的激光雷达系统的剖面结构示意图；
图16是本申请实施例提供的一种电磁感应供电、无线通信的激光雷达系统的剖面结构示意图；
图17是本申请实施例提供的一种无线供电、光通信系统的激光雷达系统的剖面结构示意图；
图18是本申请实施例提供的一种激光雷达系统的工作流程示意图；
图19是本申请实施例提供的一种激光雷达系统的算法流程示意图。
具体实施方式
下面结合附图和实施例对本申请进行说明。可以理解的是，此处所描述的 具体实施例仅仅用于解释本申请，而非对本申请的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与本申请相关的部分而非全部结构。
本申请实施例提供的光发射模块和光信号检测模块可应用于激光雷达系统，下文中将结合应用场景对光发射模块和光信号检测模块进行说明。
图1是一实施例提供的一种光发射模块的结构示意图。参见图1，该光发射模块包括：高频调制信号输出单元10、激光发射单元20和参考信号发射单元30。
在一实施例中，高频调制信号输出单元10，设置为输出预设的至少两个不同频率的高频调制信号；激光发射单元20，与高频调制信号输出单元10连接，设置为发射分别经至少两个不同频率的高频调制信号调制后的至少两个不同频率的激光光束；参考信号发射单元30，与高频调制信号输出单元10连接，设置为发射分别经至少两个不同频率的高频调制信号调制后的至少两个不同频率的参考信号。
在一实施例中，每个高频调制信号为一个主振信号；高频调制信号输出单元10还设置为输出至少两个不同频率的本振信号，其中至少两个本振信号与至少两个主振信号一一对应，且每个本振信号与对应的主振信号相差预设频率。
在一实施例中，高频调制信号输出单元10包括至少两个锁相环，每个锁相环设置为输出一个主振信号和与所述主振信号对应的本振信号。
在一实施例中，不同的主振信号的频率的差值的绝对值在预设频率范围内。例如预设频率范围为0MHz-50MHz。
在一实施例中，至少两个不同频率的参考信号为至少两个不同频率的参考激光光束或者为至少两个不同频率的参考电信号。
在一实施例中，在至少两个不同频率的参考信号为至少两个不同频率的参考激光光束的情况下，至少两个参考信号可通过激光发射单元发射。
在一实施例中，高频调制信号输出单元10包括三个锁相环路，每一个锁相环路可输出一组高频调制信号，因此三个锁相环路可输出三组不同频率的高频调制信号。锁相环路是一种反馈控制电路，简称锁相环(PLL，Phase-Locked Loop)。
本实施例中，一组高频调制信号包括一个主振信号和与该主振信号对应的本振信号。
可以理解，在其他实施例中，高频调制信号输出单元10中也可以采用直接数字式频率合成器(DDS，Direct Digital Synthesizer)代替锁相环路。
示例性的，图2是一实施例提供的一种DDS的工作原理示意图。参照图2， DDS包括相位累加器111、正弦查询表112、数模转换器(Digital to analog converter，DAC)113和低通滤波器(low pass filter，LTP)114，同时，时钟信号fc分别输入到相位累加器111和正弦查询表112，频率控制字K输入到相位累加器111。
其中，相位累加器111是DDS的核心。相位累加器111由一个N比特的二进制加法器和一个由时钟信号fc取样的N比特寄存器构成，作用是对频率控制字K(十进制)进行线性累加。相位累加器111用于实现相位的累加并存储累加结果。当相位累加器111累加满量时就会产生一次溢出，完成一个周期的动作，这个周期就是DDS系统合成信号的一个频率周期，相位累加器111的溢出频率就是输出的信号频率。
正弦查询表112是一个可编程只读存储器，存储的是以相位为地址的一个周期正弦信号的采样编码值，包含一个周期正弦波的数字幅度信息，每个地址对应于正弦波中0～2π范围的一个相位点(0～2π的相位被等分为M份)。
数模转换器113的作用是将数字信号转换为模拟信号。在一实施例中，将正弦幅值序列转换为正弦波。并且，数模转换器113的分辨率越高，输出的正弦波的连续性越好；当数模转换器113的分辨率较低时，输出的正弦波为梯形波形，此梯形波形经过低通滤波器114(低通滤波器也可以为带通滤波器)滤波后，成为质量(这里主要指波形的连续性)符合需要的模拟波形fout。这里通过改变时钟信号fc、相位累加器111的位数N或者正弦查询表112的位数M均可改变输出的模拟波形fout的频率。
在一实施例中，激光发射单元20可以包括激光器，激光器设置为发出准直性较好、能量集中的激光光束。示例性的，激光器可为半导体激光器、光纤激光器、气体激光器或固体激光器。
在一实施例中，所述激光器发射出的激光光束的波长可以是635纳米(nm)、650nm、780nm、792nm或850nm。
在一实施例中，激光发射单元20包括激光二极管，例如红外波段的低功率连续激光二极管。
其中，这里的低功率是指毫瓦级别的功率。功率较低，一方面可避免激光发射单元20产生较多的热量对光发射模块中以及周边电路中的电学元件的性能的影响，同时，低功率激光二极管产生的激光为一类安全激光，对人体，特别是人眼无伤害；另一方面可降低成本。
图3是一实施例提供的激光发射单元的结构示意图。参照图3，该激光发射单元20包括激光二极管201、准直透镜202，激光二极管201与准直透镜202 沿光束的传播方向依次排列；准直透镜202设置为对激光二极管201发出的激光光束进行准直。经准直透镜202准直后的激光光束能量更集中，使得发射出的激光光斑非常小。
需要说明的是，图3中仅示例性的示出了激光发射单元20包括准直透镜202。在其他实施方式中，还可以在光束传播路径中的任意两个光学元件之间设置准直透镜202，以减小光束的发散角度，或者直接在激光二极管201内部设有准直元件，这里不作严格限制。在一个实施例中，准直透镜202可采用球面镜片。
示例性的，高频调制信号输出单元10输出预设的三组不同频率的高频调制信号的频率值为：主振信号fg1＝193MHz，本振信号fg1’＝192MHz；主振信号fg2＝187MHz，本振信号fg2’＝186MHz；主振信号fg3＝167MHz，本振信号fg3’＝166MHz，每一组高频调制信号中的主振信号加载到激光发射单元20后都可使得激光发射单元20发射出对应频率的激光光束。
需要说明的是，上述三组高频调制信号的具体频率值仅为示例性的说明，而并非限定；同时，上述高频调制信号输出单元10输出的高频调制信号的组数也仅为示例性的说明，而非限定，比如也可以输出为两组或者四组以上高频调制信号。在其他实施方式中，高频调制信号的频率值的选取可根据激光雷达系统对光发射模块的实际需求设定，这里不作严格限定。
本申请实施例提供的光发射模块，通过高频调制信号输出单元10输出预设至少两个不同频率的高频调制信号，并加载到激光发射单元上以使激光发射单元发射出至少两种不同频率的激光光束，采用两种以上不同频率的激光光束去探测同一距离，可以在保证测量精度的同时还保证了测量范围。
上述实施方式提供的光发射模块发出经高频调制信号调制后的激光光束作为探测光信号或者光发射模块发出经高频调制信号调制后的激光光束分别作为探测光信号和参考光信号，其中探测光信号被目标物体反射，形成与目标物体的距离远近相关的回波信号。
相关技术中的相位法激光雷达系统中，利用电学元件对发射信号的频率进行调制，发射信号的调制速度慢，电磁干扰严重，导致现有相位法激光雷达系统探测速度较慢。
图4是本公开实施例提供的一种光发射单元的结构示意图。参见图4，该光发射单元包括：光源子单元11、高频调制子单元12和差频子单元13；光源子单元11设置为发出初始光束；高频调制子单元12设置为通过光混频技术对初始光束进行频率调制，发出至少两种不同频率的高频发射信号fg1～fgm(其中，m为大于或等于2的整数)；差频子单元13设置为将任意两种不同频率的高频 发射信号进行差频处理，发出至少一种低频发射信号fdi(其中，i为大于或等于1的整数)；其中，至少一种高频发射信号fgj(其中，1≤j≤m)和至少一种低频发射信号fdi作为探测光信号，由光发射单元发出。
在一实施例中，光源子单元11可以包括激光器，设置为发出准直性较好、能量集中的激光光束。示例性的，激光器可为半导体激光器、光纤激光器、气体激光器或固体激光器。
示例性的，高频调制子单元12对初始光束进行调制得到的高频发射信号的频率可分别为fg1＝194MHz、fg2＝190MHz、fg3＝185MHz和fg4＝179MHz，差频子单元12对fg1、fg2、fg3和fg4中的任意两个信号进行差频处理，得到的低频发射信号可分别为fd1＝4MHz、fd2＝5MHz、fd3＝6MHz、fd4＝9MHz、fd5＝11MHz和fd6＝15MHz，此时，m的取值为4，i的取值最大为6。由光发射单元发出的探测光信号包括上述4种高频发射信号中的至少一种和上述6种低频发射信号中的至少一种。
示例性的，探测光信号可包括194MHz的高频发射信号和4MHz的低频发射信号；或者，探测光信号可包括194MHz和185MHz的高频发射信号，以及4MHz和15MHz的低频发射信号。
需要说明的是，上述高频发射信号和低频发射信号的具体频率值仅为示例性的说明，而并非限定；同时，上述探测光信号对频率值的选取也仅为示例性的说明，而非限定。在其他实施方式中，高频发射信号和低频发射信号的频率值以及探测光信号对频率值的选取可根据激光雷达系统对光发射单元的实际需求设定。
本公开实施例提供的光发射单元，通过高频调制子单元12通过光混频技术对初始光束进行调制，相较于利用电学元件对初始光束进行调制而言，调制速度快，且高频发射信号的频率较高，将该光发射单元应用于激光雷达系统时，可提高激光雷达系统的探测精度。差频子单元13通过差频处理得到低频发射信号，相对于直接对初始光束进行调制得到差频发射信号而言，不需要再按照完整的调制过程调制一个新的低频发射信号，从而节省了配置时间，从而低频发射信号的调制速度也较快。因此，本公开实施例提供的光发射单元加快了探测光信号的调制速度，从而提高了探测光信号的发射速度，由此提高了激光雷达系统的探测速度。
同时，该光发射单元发出至少一种高频发射信号和至少一种低频发射信号作为探测光信号，即发出至少两种频率不同的发射信号作为探测光信号(也称为多测尺测量技术，每一种频率的探测光信号对应一把测尺，其中，高频发射信号对应精尺，低频发射信号对应粗尺，还包括中频发射信号对应的中尺)。 其中，探测光信号的频率越高，激光雷达系统的探测精度越高，探测光信号的频率越低，激光雷达系统可探测的距离越远。因此，本实施例提供的光发射单元，利用高频发射信号保证激光雷达系统的探测精度、利用低频发射信号保证激光雷达系统的探测范围，将高频发射信号与低频发射信号探测的结果进行数据融合，即可得到较大量程及较高精度的距离值。同时，此激光雷达系统也具有利用传统的多测尺测量技术进行测量时，可以在整个系统中忽略频移的影响，从而具有的稳定性较高、可探测距离较远以及精度较高的特点。
此外，利用光混频技术获得高频发射信号，利用差频技术获得低频发射信号，避免了利用电学元件对光束进行调制时，探测光信号容易受电磁信号干扰的问题。因此，探测光信号的稳定性较高。
在一实施例中，高频调制子单元12包括频率合成器；频率合成器设置为通过直接数字频率合成技术将预设的至少两个不同的高频率值加载到光源子单元发出的初始光束上，以形成至少两种不同频率的高频发射信号。
在一实施例中，直接数字频率合成技术(Direct Digital Frequency Synthesis，简称DDS或DDFS)被称为第三代频率合成技术，是指产生系列数字信号并经数模转换器转换为模拟信号的技术，即从“相位”的概念出发直接合成所需要的波形的一种新的频率合成技术。
在一实施例中，光源子单元包括低功率连续激光二极管。
其中，光源子单元的功率较低，一方面可避免光源子单元产生较多的热量，对光发射单元中以及周边电路中的电学元件的性能的影响；另一方面可降低成本。
在一实施例中，光源子单元11还包括准直透镜，低功率连续激光二极管与准直透镜沿光束的传播方向依次排列；准直透镜设置为对低功率连续激光二极管发出的初始光束进行准直。
本申请实施例还提供了一种用于检测回波信号的光信号检测模块。图5是本申请实施例提供的一种光信号检测模块的结构示意图。参见图5，该光信号检测模块包括：信号接收单元40和信号处理单元50。
在一实施例中，至少两个不同频率的高频调制信号包括第一高频调制信号和第二高频调制信号，信号接收单元40设置为接收第一参考信号、第二参考信号、第一高频回波信号和第二高频回波信号；其中，第一参考信号为经第一高频调制信号调制后的参考信号，第二参考信号为经第二高频调制信号调制后的参考信号；第一高频回波信号为第一激光光束被目标物体反射后的激光光束，第二高频回波信号为第二激光光束被目标物体反射后的激光光束；第一激光光 束为经第一高频调制信号调制后的激光光束，第二激光光束为经第二高频调制信号调制后的激光光束；第一高频调制信号的频率大于第二高频调制信号的频率；信号处理单元50设置为：根据第一参考信号与第一高频回波信号之间的第一相位差获取目标物体的第一参考距离值；根据述第一相位差与第二相位差获取目标物体的第二参考距离值，并根据第一参考距离值和所述第二参考距离值确定所述目标物体的测量距离值；其中，第二相位差为第二参考信号与第二高频回波信号之间的相位差。
示例性的，可将第一参考距离和第二参考距离进行融合处理，得到目标物体的测量距离，例如将第一参考距离和第二参考距离的和作为目标物体的测量距离。
在一实施例中，信号接收单元40与上述实施例的光发射模块中的激光发射单元20和参考信号发射单元30连接，第一高频调制信号为高频调制信号输出单元10输出的至少两个不同频率的高频调制信号中频率最高的高频调制信号，第二高频调制信号为高频调制信号输出单元10输出的至少两个不同频率的高频调制信号中除频率最高的高频调制信号之外的所有高频调制信号，第二高频调制信号的个数可为一个或多个，第一参考信号为参考信号发射单元30发射的经第一高频调制信号调制后的信号，第二参考信号为参考信号发射单元30发射的经第二高频调制信号调制后的信号，第一激光光束为激光发射单元20发射的经第一高频调制信号调制后的激光光束，第二激光光束为激光发射单元20发射的经第二高频调制信号调制后的激光光束。
在一实施例中，在第二高频调制信号为多个的情况下，第二激光光束和第二参考信号的个数均为多个，通过多个第二激光光束可分别获取多个第二高频回波信号，进而可分别获取多个第二高频回波信号中每个第二高频回波信号与该第二高频回波信号对应的第二参考信号之间的第二相位差，根据多个第二相位差与一个第一相位差获取第二参考距离值，例如分别根据多个第二相位差中每个第二相位差与第一相位差之间的第三相位差，获取多个第二参考距离值，根据第一参考距离值和多个第二参考距离值确定目标物体的测量距离值。
在一实施例中，第一参考信号和第二参考信号分别为第一参考激光光束和第二参考激光光束，或者分别为第一参考电信号或者第二参考电信号。
在一实施例中，信号接收单元40还设置为：接收第一本振信号；将第一高频回波信号转换为对应的电信号，将第一高频回波信号对应的电信号与第一本振信号进行混频，得到第一差频测量信号；将第一参考激光光束转换为对应的电信号并将第一参考激光光束对应的电信号与第一本振信号进行混频，或者第一参考电信号与第一本振信号进行混频，得到第一差频参考信号；接收第二本振信号，将第二高频回波信号转换为对应的电信号，将第二高频回波信号对应 的电信号与第二本振信号进行混频，得到第二差频测量信号；将第二参考激光光束转换为对应的电信号并将第二参考激光光束对应的电信号与第二本振信号进行混频，或者将第二参考电信号与第二本振信号进行混频，得到第二差频参考信号；其中，第一高频调制信号为第一主振信号，第二高频调制信号为第二主振信号，第一主振信号与第一本振信号的频率相差预设频率，第二主振信号与第二本振信号的频率相差预设频率；信号处理单元50是设置为通过如下方式根据第一参考信号与第一高频回波信号之间的第一相位差获取目标物体的第一参考距离值：将第一差频测量信号与第一差频参考信号进行比较得到第一相位差，根据第一相位差获取目标物体的第一参考距离值；信号处理单元50是设置为通过如下方式根据第一相位差与第二相位差获取目标物体的第二参考距离值：将第二差频测量信号与第二差频参考信号进行比较，得到第二相位差；计算第二相位差与第一相位差之间的第三相位差；根据第三相位差获取目标物体的第二参考距离值。
本实施例中，第一本振信号为调制信号输出单元10输出的与第一主振信号对应的本振信号，第二本振信号为调制信号输出单元10输出的与第二主振信号对应的本振信号。
本实施例中，信号接收单元40设置为接收被目标物体反射的高频回波信号，并将高频回波信号转换为高频电信号，再将高频电信号转换成低频电信号；信号处理单元50设置为将低频模拟电信号转换为低频数字信号再利用相关算法得到相位信息，进而获取目标物体的距离值。
其中，上述信号接收单元40在将高频电信号转换成低频电信号的过程中实际上采用了差频鉴相技术。差频鉴相技术就是指将高频信号转换为低频信号而保持相位信息不变，再利用低频信号进行相位检测的技术。
图6是一实施例提供的差频鉴相技术原理示意图。参照图6，光发射模块中的高频调制信号输出单元相当于一个高频信号源，高频信号源输出的每一组高频调制信号都包括一个主振信号及一个与主振信号相差固定频率(比如1MHZ)的本振信号。本实施例以获取上述实施例中的第一相位差为例，第一主振信号加载到激光光束上并发射出去到达目标物体，目标物体再将激光光束反射到光信号检测模块的信号接收单元，信号接收单元接收激光光束被目标物体反射得到的第一高频回波信号，并将第一高频回波信号转换为高频电信号，又将高频电信号与第一本振信号进行混频，得到低频的第一差频测量信号。
光信号检测模块中的信号处理单元设置为通过将所述第一差频测量信号与第一差频参考信号进行比较得到第一相位差，进而通过第一相位差获取目标物体的第一参考距离值。其中所述第一差频参考信号是通过所述第一主振信号调 制后的激光光束对应的电信号或者是通过第一主振信号调制后的电信号与第一本振信号进行混频得到的。
本实施例中，第二相位差的获取原理与第一相位差的获取原理相同，此处不再赘述。获取第二相位差后，便可计算第二相位差与第一相位差之间的第三相位差，进而获取目标物体的第二参考距离，根据第一参考距离和第二参考距离，获取目标物体的测量距离。
在一实施例中，在根据第一参考距离和第二参考距离确定目标物体的测量距离之前，信号处理单元40还可设置为根据第二相位差获取目标物体的第三参考距离值，根据第三参考距离值和第一参考距离值计算第四参考距离值，并将第一参考距离值替换为第四参考距离值。
在一实施例中，可将第三参考距离值和第一参考距离值的平均值作为第四参考距离值，或者通过查表等方式确定第四参考距离值。
本实施例中，差频测量信号与高频回波信号的相位相差是本振信号的相位，主振信号与差频参考信号的相位差也是本振信号的相位，由此差频测量信号与差频参考信号的相位差等于高频回波信号与主振信号的相位差，即由于相位信息保持不变，可将高频信号转换为低频信号处理，利用低频信号进行相位检测，降低了对模数转换芯片的要求，即减小了后级处理电路的带宽，由于带宽越窄，鉴相精度越高，因此有利于提高鉴相精度，即提高光信号检测模块对高频回波信号的处理精度。另一方面，由于频率和周期的倒数关系，差频鉴相技术降低了待测信号的频率，从而展宽了待测信号的周期，同时由于低频信号处理技术相较于高频信号处理技术更成熟，所以将高频信号转换为低频信号处理，可提高测相分辨率，从而提高鉴相精度。
示例性的，图6示出的光信号发出与检测的完整过程为：高频信号源产生的主振信号
Figure PCTCN2019088567-appb-000001
与本振信号
Figure PCTCN2019088567-appb-000002
二者均为高频信号，但相位不同、频率也不同，且差频为低频信号。主振信号
Figure PCTCN2019088567-appb-000003
加载到激光光束上发射到目标物体，被目标物体反射，形成高频回波信号
Figure PCTCN2019088567-appb-000004
被信号接收单元接收。此高频回波信号
Figure PCTCN2019088567-appb-000005
与主振信号
Figure PCTCN2019088567-appb-000006
频率相同，相位发生变化，且相位的变化量与目标物体的距离相关。此高频回波信号
Figure PCTCN2019088567-appb-000007
与本振信号
Figure PCTCN2019088567-appb-000008
进行混频，再经过低通滤波器(Low Pass Filter，LPF)后，产生低频的差频测量信号
Figure PCTCN2019088567-appb-000009
产生差频参考信号的信号处理路径为：主振信号
Figure PCTCN2019088567-appb-000010
与本振信号
Figure PCTCN2019088567-appb-000011
进行混频，然后经过低通滤波器LPF后，产生低频的差频参考信号
Figure PCTCN2019088567-appb-000012
然后，信号处理单元比较低频的差频测量信号
Figure PCTCN2019088567-appb-000013
与低频的差频参考信号
Figure PCTCN2019088567-appb-000014
分别检测出差频测量信号与差频参考信号的相位信息并 计算出相位差，该相位差值与高频的主振信号
Figure PCTCN2019088567-appb-000015
与高频回波信号
Figure PCTCN2019088567-appb-000016
的相位差相同。由此，后续通过处理低频信号即可得到高频信号所携带的相位差信息，从而最终获得目标物体的测量距离值。
在一个实施例中，信号处理单元采用了数字鉴相法检测相位信息。数字鉴相法就是将待检测的信号数字化后再鉴别出该信号的相位信息的方法。示例性的，图7是本申请实施例提供的一种数字鉴相法的流程示意图。参照图7，该数字鉴相法的流程包括：将待检测的模拟量信号x(t)经过模数转换化为数字量信号x(n)(其中，n为正整数)，再经过相关算法得到相位信息。在一实施例中，数字鉴相法的核心处理单元可为计算机或微处理器。上述数字鉴相法不依赖于电路，整个鉴相过程完全数字化，避免了电路中存在的电磁干扰对鉴相结果的影响，因而具有很好的抗干扰能力，进而具有较高的鉴相精度。同时，运算速度快，体积小。将数字鉴相法应用于激光雷达系统中，可提高激光雷达系统的测量距离的速度和精度(也可称为分辨率)。
需要说明的是，上述实施例中提及的“高频”是指单位级别为百MHz的频率(比如100MHZ以上)，本申请提及的“低频”是指单位级别为MHz的频率(比如1MHZ～10MHZ)。
在一实施例中，信号接收单元40包括光电探测器。
如此设置，相当于利用光电探测器这一个元件可实现第一参考信号、第二参考信号、第一高频回波信号以及第二高频回波信号的接收、转换与混频三种功能，从而减少了光信号检测模块中元件的数量，简化了光信号检测模块的结构，缩小了光信号检测模块的体积。将光电探测器应用于激光雷达系统中，有利于激光雷达系统的小型化设计。
需要说明的是，上述光电探测器仅为对信号接收单元的一种设计方式，而非限定。在其他实施方式中，还可以将上述接收、转换与混频的功能由两个或三个元件实现。此时，多个元件实现的功能相对独立，当出现信号检测异常时，可快速进行排查，且更换元件的成本较低。
图8是一实施例提供的一种激光发射单元和信号接收单元的光学结构示意。参照图8，信号接收单元40还可以包括接收透镜213和滤光片214，接收透镜213、滤光片214和光电探测器211沿光束的传播方向依次排列；接收透镜213设置为将第一高频回波信号和第二高频回波信号聚焦到光电探测器211；滤光片214设置为通过第一高频回波信号和第二高频回波信号，滤除其他波长的干扰信号，即干扰信号不会被光电探测器211检测到，从而提高了光信号检测模块的信噪比。将滤光片214应用到激光雷达系统中，可增加系统在强光下的探测距离。
其中，由于目标物体表面存在散射，由目标物体反射产生的回波信号通常会发散，通过接收透镜213将发散的回波信号聚焦到光电探测器211，可增强被光电探测器接收的回波信号的强度。
在一实施例中，在接收透镜213靠近激光发射单元20一侧还包括附着在接收透镜213出光面一侧的近距离光路补偿镜2131，此近距离光路补偿镜2131设置为将近距离的目标物体反射产生的回波信号聚焦至光电探测器211，从而减小非同轴系统带来的盲区。示例性的，应用于非同轴系统的激光雷达中，激光雷达的盲区可降低至20cm以下。
在一实施例中，信号处理单元50包括运算放大器、模数转换器和现场可编程门阵列；运算放大器的输入端与信号接收单元电连接，运算放大器的输出端与模数转换器的输入端电连接，模数转换器的输出端与现场可编程门阵列电连接；运算放大器设置为分别将信号接收单元传输的第一差频测量信号、第一差频参考信号、第二差频测量信号以及第二差频参考信号放大；模数转换器设置为分别将经运算放大器放大后的第一差频测量信号、第一差频参考信号、第二差频测量信号以及第二差频参考信号由模拟量信号转换为数字量信号；现场可编程门阵列设置为将第一差频测量信号对应的数字量信号与第一差频参考信号对应的数字量信号进行比较得到第一相位差，并根据第一相位差计算目标物体的第一参考距离值；将第二差频测量信号对应的数字量信号与第二差频参考信号对应的数字量信号进行比较，得到第二相位差；计算第二相位差与第一相位差之间的第三相位差，根据第三相位差计算目标物体的第二参考距离值；根据第一参考距离值和第二参考距离值确定目标物体的测量距离值。
在一实施例中，光信号检测模块，还包括：供电单元、微处理器单元和高压调节单元；信号处理单元的受电端和所述微处理器单元的受电端分别与供电单元电连接，微处理器单元的第一控制端与信号处理单元电连接，微处理器单元的第二控制端通过高压调节单元与信号接收单元电连接；供电单元设置为向信号处理单元和微处理器单元供电；微处理器单元设置为对信号处理单元进行控制处理，还设置为通过高压调节单元对施加到所述信号接收单元的电压进行调节，以使信号接收单元接收强度不同的回波信号。
在一实施例中，光信号检测模块，还包括温度探测单元、高压探测单元和标准电压探测单元，温度探测单元的输出端、高压探测单元的输出端和标准电压探测单元的输出端分别与微处理器单元的输入端电连接；温度探测单元设置为探测信号接收单元的温度值，高压探测单元设置为探测信号接收单元的高压值，标准电压探测单元设置为探测信号接收单元的标准电压值；微处理器单元还设置为根据温度值、高压值或标准电压值对所述高压调节单元输出的电压进 行调节。
图9一实施例提供的光学系统的结构框图。参见图9，本实施例提供的光学系统可包括上述实施例任意实施例提供的光发射模块60以及上述实施例任意实施例提供的信号接收单元70，信号接收单元70与光发射模块60连接。
本实施例中光发射模块60和信号接收单元70的原理与上述实施例相同，此处不再赘述。
在一实施例中，光发射模块60与信号接收单元70之间的光路布局包括：同轴系统、双发射单接收系统、单发射单接收系统或双发射双接收系统。
本申请还提供一种激光雷达，所述激光雷达包括上述任意实施例中提供的光发射模块和光信号检测模块。因此，本申请实施例提供的激光雷达具有上述光发射模块的有益效果，也具有上述光信号检测模块的有益效果。此处未详尽示出的有益效果可参照上述实施例中光发射模块和光信号检测模块的内容，在此不再赘述。
图10是一实施例提供的一种激光雷达的硬件原理示意图。以下结合激光雷达的硬件结构说明激光雷达光发射和检测的原理。参照图10，所述激光雷达的光发射模块包括三个锁相环路，三个锁相环路通过一个切换开关进行频率的切换。每一个锁相环路输出的高频调制信号都包括主振信号和本振信号。本实施例中，以通过两个锁相环路分别输出第一主振信号和第一本振信号，以及第二主振信号和第二本振信号为例。首先通过切换开关选择一个锁相环路输出第一主振信号和第一本振信号。其中第一主振信号经放大电路1放大后可选择性地加载在第一激光二极管或者第二激光二极管上。所述第一主振信号加载在第一激光二极管上后发射出对应第一主振信号频率调制的第一激光光束，第一激光光束经外光路到达目标物体后会被反射回来，发射回来的激光光束也就是第一高频回波信号。因发射的激光光束是经高频调制信号调制的，所以回波信号也属于高频信号。
所述激光雷达的光信号检测模块包括光电探测器，所述光电探测器在检测到所述第一高频回波信号后，首先会将第一高频回波信号转换为高频电信号，所述高频电信号就是被第一主振信号调制的第一激光光束往返于目标物体后经过解调的电信号，它和第一主振信号之间有一个延迟的相位差。将所述第一高频电信号与所述第一本振信号进行混频便得到低频电信号(即上述实施例中的第一差频测量信号)。将所述低频电信号经过放大电路3放大和模数转换器转换，输出一个低频数字电信号(用eD表示)到现场可编程门阵列(Field－Programmable Gate Array，FPGA)。
为了进行比相，所述第一主振信号可以切换加载到第二激光二极管，发射出调制后的第一参考激光光束并通过内光路到达光电探测器，所述第一参考激光光束经所述光电探测器的光电转换，然后再与放大后的第一本振信号进行混频处理得到一个低频的第一差频参考信号，所述低频的第一差频参考信号同样经过放大、模数转换得到一个作为比相的低频参考数字电信号(用e0表示)。由于e0没有经过外光路的往返路程，所以e0不存在像eD中产生的相位延迟。因此，现场可编程门阵列将eD和e0进行相位比较，即可得到用于求取目标物体第一参考距离值的第一相位差，进而得到第一参考距离值。
通过切换开关，选择另一锁相环路，输出第二主振信号和第二本振信号，第二主振信号。同理，现场可编程门阵列可得到第二相位差，进而计算第二相位差与第一相位差之间的第三相位差，根据第三相位差得到第二参考距离值，进而根据第一参考距离值和第二参考距离值获取目标物体的测量距离值。
在本实施例中，设置为选择锁相环路的切换开关由所述现场可编程门阵列控制，三个锁相环路可以输出三组不同的高频调制信号，而且三组高频调制信号的频率值比较集中，即每两组频率值相差较小，这样可以采用统一的高频处理电路，使得硬件电路设计简单。其中，频率值最高的那组(示例性地，主振信号频率为193MHZ、本振信号频率为192HZ)作为一把精尺，可以保证系统的测量精度。其他两组(示例性地，主振信号频率为187MHZ、本振信号频率为186MHZ及主振信号频率为167MHZ、本振信号频率为166MHZ)作为辅助尺，利用精尺与两个辅助尺相互之间的差频(示例性地，差频可分别为20MHZ和6MHZ)可作为扩展量程的中尺和粗尺，以保证系统的测量量程。可以理解，如果只设置两个锁相环路，则频率值高的那组作为一把精尺，另一组作为辅助尺，利用精尺与辅助尺的差频可作为扩展量程的粗尺。
这样一方面，在保证了高精度大量程的同时减少了低频测尺的配置时间，因此提高了激光雷达的探测速度。另一方面，由于调制探测光信号的频率比较集中，从而方便电路对相近频率的信号进行处理，从而无需针对高频信号和低频信号分别设计电路，因此电路设计难度较低，电路结构简单。
在一个实施例中，放大电路3为放大微弱信号的运算放大器，从而提高信号的信噪比。示例性的，所述运算放大器可采用多级放大电路，前级是电流模式信号与电压模式信号处理，后几级采用低噪声、高速、高精度信号放大处理。
所述运算放大器的输入端与光电探测器的输出端电连接，所述运算放大器的输出端与模数转换器的输入端电连接，模数转换器的输出端与现场可编程门阵列电连接。
在一实施例中，模数转换器222设置为快速采集信号，现场可编程门阵列 设置为对模数转换器采集的信号进行高速相位频率的计算(示例性的，FPGA上可集成平滑滤波器子单元和260点的快速傅里叶变换子单元)，由此，使得激光雷达测量速度较快、抗干扰能力强、精度高。同时，现场可编程门阵列可舍弃不稳定的数据，只采集稳定的数据进行处理，从而数据一致性好、数据稳定性高。
此外，激光雷达使用的设置为高速信号采集的模数转换器和设置为高速相位计算的FPGA，可采用专业流片技术，从而使产品的集成度较高、面积较小、可靠性和稳定性较高，从而成本较低且易于实现微型化。同时，采用联合测试工作组(Joint Test Action Group，JTAP)的边界扫描测试技术，可减低测试成本、缩短测试时间，从而缩短产品的面世的时间。
继续参见图10，激光雷达还包括供电单元、微处理器(Microcontroller Unit，MCU)和高压调节单元；供电单元和微处理器、FPGA、第一激光二极管、第二激光二极管等电连接以实现供电，微处理器的第一控制端与FGPA电连接以实现多种数据交互和程序控制，微处理器的第二控制端通过高压调节单元与光电探测器电连接以实现对光电探测器的电压进行调节，从而让光电探测器可以放大多种不同的反射回来的回波信号。
在一实施例中，供电单元可将外部供电按照模块要求，转换为模块的多个组成部分所需要的电压并对多个组成部分分别进行供电。并且，微处理器可对供电单元进行控制，实现激光雷达中多个组成部分独立供电。
在一实施例中，高压调节单元可通过脉冲宽度调制(Pulse Width Modulation，PWM)的方式调节施加到光电探测器的高压(High voltage，HV)的大小。
示例性的，脉冲宽度调制高压过程中，占空比越大，电压值越高。
继续参见图10，激光雷达还包括温度探测单元(AD_NTC)、高压探测单元(AD_HV)和标准电压探测单元(AD_VBAS)，温度探测单元的输出端、高压探测单元的输出端和标准电压探测单元的输出端分别与微处理器的输入端电连接；温度探测单元设置为探测光电探测器的温度值，高压探测单元设置为探测光电探测器的高压值，标准电压探测单元设置为探测光电探测器的标准电压值；微处理器还设置为根据温度值、和多种反馈的信号对输出的电压进行调节。
本实施例中，为使激光雷达可适用于不同的环境，设计温度探测单元、高压探测单元以及标准电压探测单元对光电探测器的使用环境进行监测，并根据环境信息(包括温度值、高压值以及标准电压值)对施加到光电探测器的电压值进行调节。
示例性的，根据温度对光电探测器的影响，通过电压差值补偿温度变化导致的光电探测器接收到的回波信号的变化。示例性的，根据目标物体的表面发射产生的回波信号的强弱不同，通过电压差补偿回波信号强度变化导致的光电探测器接收到的回波信号的变化。从而，使得光信号检测模块可适用于多种不同的环境。
在本实施例中，还采用恒流恒压恒功率驱动电路(图10中未示出)为激光发射单元(包括第一激光二极管和第二激光二极管)提供稳定的供电系统，同时，通过激光发射单元自身电压反馈，稳定激光发射单元的工作点。
在一实施例中，通过高速切换开关进行切换，大大提高了频率切换的时间。将高速切换开关(SW)应用于激光雷达，可有效提高测量精度。
在一实施例中，激光雷达的光路系统布局包括：同轴系统、双发射单收系统、单发射单收系统或双发射双收系统。
其中，同轴系统和单发射单接收系统均可利用相对较少的元件，从而成本较低；同时，结构紧凑，从而体积较小。双发射单接收系统和双发射双接收系统中参考光束(参考光信号对应的光束)与探测光束(探测光信号对应的光束)不交叠，光信号稳定性较高。
示例性的，图11是本申请一实施例提供的一种同轴光学系统。参照图11，激光发射单元31发出的探测光信号依次经过反射镜34中间的小孔34Q和透镜33的中间部分照射到目标物体32的表面，被目标物体32反射，形成回波信号。该回波信号经透镜33聚焦，再经过反射镜34反射后在光电探测器35的表面聚焦，被光电探测器35接收。
需要说明的是，虽然有少量的回波信号会穿过反射镜34中间的小孔34Q到达光发射单元31一侧，但是由于回波信号的强度相对于探测光信号的强度而言极小，因此，回波信号对探测光信号的影响可忽略。
示例性的，图12是本申请一实施例提供的一种双发射单收光学系统。参照图10，激光发射单元包括外光源311和内光源322。外光源311发出的探测光信号照射到目标物体32的表面，被目标物体32反射，形成回波信号。该回波信号经透镜33聚焦至光电探测器35的表面，被光电探测器35接收。内光源312发出的光信号也照射到光电探测器35的表面，被光电探测器35接收。
需要说明的是，外光源311和内光源312可包括于同一个激光发射单元中。外光源311发出的探测光信号的频率(示例性的为193MHz)与内光源312发出的参考光信号的频率(示例性的为192MHz)相差固定值(1MHZ)，从而实现差频鉴相。其中前面图10所示的实施例中就包括了双发射单收光学系统。
示例性的，图13是本申请一实施例提供的一种双发射双收光学系统。参照图13，激光发射单元包括外光源311和内光源312，信号接收单元包括第一光电探测器351和第二光电探测器352。外光源311发出的探测光信号照射到目标物体32的表面，被目标物体32反射，形成回波信号。该回波信号经透镜33聚焦至第一光电探测器351的表面，被第一光电探测器351接收。内光源312发出的光信号直接照射到第二光电探测器352的表面，被第二光电探测器352接收。
需要说明的是，外光源311和内光源312可参考图12的说明。第一光电探测器351和第二光电探测器352完全相同。从而，获得回波信号的光路和电路与获得差频参考信号的光路和电路各自独自，二者之间不相互影响，光信号更稳定的同时电信号的稳定性也较高。
示例性的，图14是本申请一实施例提供的一种单发射单收光学系统。参照图14，通过频率调制的电信号36控制激光发射单元31发出探测光信号，探测光信号照射到目标物体32的表面，被目标物体32反射，形成回波信号。该回波信号经透镜33聚焦至光电探测器35的表面，被光电探测器35接收。同时光电探测器35接收被频率调制的电信号36。由此，省略了将调制的电信号转换为参考光信号后再转换为参考电信号的过程，从而节省了信号处理的时间，提高了信号处理的速度。
在一实施例中，激光雷达还包括角度探测单元，角度探测单元与光信号检测模块中的信号处理单元电连接；角度探测单元设置为探测激光雷达旋转的角度值；信号处理单元还设置为将距离值的变化量与角度值的变化量相关联。
在一实施例中，光发射模块可在360度范围内转动，角度探测单元设置为探测光发射模块转动的角度，从而激光雷达可以实现0.01米(m)-100m范围内水平360度的二维扫描探测，从而得到周围环境的二维位置信息。在一实施例中，激光雷达的扫描频率为3赫兹(Hz)-10Hz，示例性的可理解为光发射模块每秒内可实现360度旋转3次-10次；若激光雷达中的光学系统为同轴系统，则光信号检测模块与光发射模块同步旋转。激光雷达的探测频率为8kHz-20kHz，即每秒内可探测8k-20k个距离值。激光雷达系统的角分辨率为0.18°-1°，即角度探测单元可分辨的最小的角度值为0.18°-1°。同时，激光雷达的探测精度可高达毫米级，从而此激光雷达可广泛应用于激光扫描系统、监控系统、空间测绘(空间建模)、防碰撞、机器人、环境探测以及军事侦察等领域。
在一实施例中，激光雷达旋转的传动方式包括：有刷电机、无刷电机或无线供电。
在一实施例中，激光雷达还包括通信单元；通信单元与光信号检测模块中 的信号处理单元电连接；通信单元设置为将信号处理单元得到的距离值、角度值以及距离值的变化量与角度值的变化量的关联关系中的至少一种传输给一反馈信号接收单元。
在一实施例中，反馈信号接收单元可为光发射模块，光发射模块通过接收到的上述信息对发出的探测光信号的强度进行调节，以适用于不同的探测环境。
在一实施例中，反馈信号接收单元还可为微控制器，微控制器设置为对探测到的数据进行进一步处理，从而实现周边环境的监控或者实现自动化控制。
在一实施例中，通信单元的通信方式可包括：光通信、蓝牙通信或WIFI通信。
如此设置，通过无线传输的方式进行数据传输，可减少激光雷达的外部接口数量，一方面简化了激光雷达的结构；另一方面可使激光雷达的适用范围更广，示例性的可适用于潮湿或有水的环境。
示例性的，图15是本申请一实施例提供的一种电机皮带传动、滑环供电的激光雷达的剖面结构示意图。参照图15，该激光雷达包括马达411、皮带412、角度探测单元413、光电探测器414、接收透镜415、轴承416和滑环417。其中，马达411通过皮带412带动旋转模组(包括光电探测器414和接收透镜415，还包括图15中未示出的光发射模块)转动。角度探测单元413可为光电转换器，用于定位码盘(图15中未示出)的位置，从而探测旋转模组转动的角度。由目标物体反射的回波信号通过接收透镜415后聚焦到光电探测器414的表面，被光电探测器414接收。滑环417用于给旋转模组供电并进行数据的传输。
示例性的，图16是本申请一实施例提供的一种电磁感应供电、无线通信的激光雷达的剖面结构示意图。参照图16，该激光雷达包括激光发射单元421、准直透镜422、遮光筒423、透光罩424、接收透镜425、光电探测器426、信号传输耦合线圈4271、电传输耦合线圈4272、轴承428、马达429以及马达控制420。示例性的，激光发射单元421可为激光器。由激光发射单元421发出的光束经过准直透镜422形成探测光信号、并透光罩424后发出，并照射到目标物体表面，形成回波信号；回波信号经过透光罩424和接收透镜425后聚焦到光电探测器426。遮光筒423用于隔离探测光信号与回波信号，使两路光信号之间不相互干扰，从而提高探测准确性。马达429在马达控制420的驱动下使旋转模组实现旋转。电传输线圈4272通过电磁感应方式实现供电，信号传输耦合线圈4271通过无线通信方式实现数据传输。
示例性的，图17是本申请实施例提供的一种无线供电、光通信系统的激光雷达的剖面结构示意图。参照图17，该激光雷达包括光发射模块431、第一无 线信号传输模块432、轴承433、无线传电模块434、第二无线信号传输模块435、马达控制436、光信号检测模块437、角度探测单元438以及马达439。此激光雷达采用无线供电方式。第一无线信号传输模块432和第二无线信号传输模块435协同工作，通过光通信的方式实现数据传输。除供电方式与通信方式之外，其他的工作过程可参照对图15与图16的说明，在此不再赘述。
需要说明的是，图15-图17仅示例性的示出了三种不同的激光雷达的结构，但并非对本申请实施例的限定。在其他实施方式中，基于本申请实施例提出的上述基本原理，可根据实际需求选择传动方式、通信方式以及设置多个组成部分之间的相对位置关系。
示例性的，图18是本申请实施例提供的一种激光雷达的工作流程示意图。参照图18，该激光雷达的工作流程包括如下步骤。
步骤S5110、电机上电旋转。
其中，电机(马达)旋转可带动旋转模组(主要包括光发射模块和光信号检测模块)转动，从而激光雷达可实现360度范围内扫描探测。
步骤S5120、发射探测光信号。
其中，探测光信号可为经高频调制信号调制的红外激光光束。探测光信号由激光发射单元发出。
步骤S5130、接收回波信号。
其中，回波信号是光发射模块发出的探测光信号被目标物体反射后，形成的反射光信号。回波信号由光信号检测模块中的信号接收单元接收。
步骤S5140、根据相位差计算距离。
其中，探测光信号与回波信号之间的相位差与目标物体的距离相关。
示例性的，利用相位法测距的公式为：
Figure PCTCN2019088567-appb-000017
其中，D是待探测的距离，c是光速，
Figure PCTCN2019088567-appb-000018
是探测到的相位差，f是探测光信号的调制频率。由此，只要检测到探测光信号与回波信号之间的相位差，即可计算得出待探测的距离。通过上述实施方式提供的光信号检测模块可实现高速数据计算，从而可实现光信号的快速处理，从而快速获得待探测距离。
步骤S5150、上传数据。
其中，此步骤可包括将步骤S5140获得的数据反馈给执行步骤S5120的光发射模块和执行步骤S5130的光信号检测模块。从而形成闭环的自反馈调节系 统，实现对探测光信号和回波信号的强度的调节，使探测结果更准确。
同时，此步骤还可包括将步骤S5140获得的数据上传到一返馈信号接收单元，即执行步骤S5160。
步骤S5160、数据输出。
其中，此步骤可实现二维探测点云图数据的显示，还可以将输出的数据作为控制指令，实现自动化控制。
示例性的，图19是本申请实施例提供的一种激光雷达的算法流程示意图。参照图19，该激光雷达的工作流程包括如下步骤。
步骤S5200、开始测量。
其中，实现此步骤可按下激光雷达中的开始按钮、点击激光雷达的屏幕上的开始按键或者通过无线传输的方式进行远程控制。
步骤S5210、频率配置。
其中，此步骤由光发射模块执行，通过高频调制信号输出单元输出的高频调制信号加载到激光发射单元以调制出频率符合需求的探测光信号。
步骤S5220、温度、高压、偏置(Bias)点检测。
其中，此步骤由光信号检测模块执行，通过检测激光雷达的应用环境，例如是信号接收单元的应用环境参数，后续对施加到信号接收单元的电压进行调节，即执行步骤S5230，可提高不同使用环境下的探测结果的准确性，从而可使激光雷达可应用于较多的测试环境。
在步骤S5200之后，在步骤S5220之前，为实现激光雷达旋转，可包括以下三个步骤。
步骤S5310、启动雷达电机。
其中，电机旋转可带动激光雷达系统中的光发射模块和信号接收单元(或者光信号检测模块整体)旋转。
步骤S5320、控制转速。
其中，可根据每360度范围内探测点的密度或探测范围的实际需求，将转速调节至预设范围。
示例性的，对每360度范围内探测点的密度的要求较低时，可使用较高的转速；对每360度范围内探测点的密度的要求较高时，可使用较低的转速。
示例性的，对转速的控制可用过调节控制转速的旋钮或者输入所需的转速值来实现。
步骤S5330、测量码盘信号。
其中，此步骤由角度探测单元执行。通过执行此步骤可实现对旋转角度的探测以及对转速的监测。
在步骤S5220之后，执行步骤S5230。
步骤S5230、高压调节。
其中，此步骤可通过脉宽调制来实现。步骤S5230完成后，接收单元处于适用于使用环境的工作状态，此时开始收发信号，包括如下步骤。
步骤S5410、频率选择1。其中频率的选择可以通过FPGA控制切换开关选择锁相环路来实现。
步骤S5420、切换到内光路。其中，内光路和外光路的切换也可以由切换开关来实现。
步骤S5430、采集内光路信号。
步骤S5440、信号处理，计算内光路相位。
步骤S5450、切换到外光路。
步骤S5460、采集外光路信号。
步骤S5470、信号处理，计算外光路相位。
步骤S5480、计算相位差1。
步骤S5490、计算测尺1测量的距离。
通常，由于相位法测距，一个测尺测量的距离不够精确，需多个测尺配合，因此，还包括至少一个不同于步骤S5410的频率的探测光信号对目标物体的距离的探测，包括以下步骤。
步骤S5510、频率选择2。同样可以通过FPGA控制切换开关选择锁相环路来实现频率的选择。
步骤S5520、切换到内光路。
步骤S5530、采集内光路信号。
步骤S5540、信号处理，计算内光路相位。
步骤S5550、切换到外光路。
步骤S5560、采集外光路信号。
步骤S5570、信号处理，计算外光路相位。
步骤S5580、计算相位差2。
步骤S5590、计算测尺2测量的距离。
基于上述步骤S5490中测尺1测量的距离与上述步骤S5590中测尺2测量的距离，执行步骤S5610。
步骤S5610、测尺衔接。
其中，测尺衔接一方面是指将上述测尺1测得的距离与测尺2测得的距离结合，另一方面还指将测尺1和测尺2做差频，计算出一个新的距离值。
示例性的，测尺1和测尺2通过软件算法作差频作为粗尺，通过粗尺计算的距离为100m，测尺2为精尺，通过精尺测得的距离为0.8m，则衔接所得的距离为100.8m。
需要说明的是，上述距离的具体数值仅为示例性的说明，并非限定。
步骤S5620、计算最终距离。
其中，步骤S5610得到的距离通常为距离相对值，及存在距离误差值，该距离相对值与距离绝对值之间具有一一对应的关系，从而，通过查表可获取距离绝对值，该距离绝对值作为最终距离。
步骤S5630、结束测量。
示例性的，与步骤S5200相对应，可通过按钮、按键或远程控制的方式结束测量；或者可设定激光雷达探测设定的阈值范围后自动结束测量。结束测量时，激光雷达可处于待机状态或断电状态。
需要说明的是，图18示出的激光雷达系统的工作流程和图19示出的激光雷达的算法流程均基于本申请实施例提供的激光雷达执行，其中多个步骤中未详尽说明之处，可参照上述实施方式中激光雷达的多个组成部分的工作原理来理解，在此不再赘述。

Claims (30)

  1. 一种光发射模块，包括：
    高频调制信号输出单元，设置为输出预设的至少两个不同频率的高频调制信号；
    激光发射单元，与所述高频调制信号输出单元连接，设置为发射分别经所述至少两个不同频率的高频调制信号调制后的至少两个不同频率的激光光束；
    参考信号发射单元，与所述高频调制信号输出单元连接，设置为发射分别经所述至少两个不同频率的高频调制信号调制后的至少两个不同频率的参考信号。
  2. 根据权利要求1所述的光发射模块，其中，每个高频调制信号为一个主振信号；
    所述高频调制信号输出单元还设置为输出至少两个不同频率的本振信号至信号接收单元，其中至少两个本振信号与至少两个主振信号一一对应，且每个本振信号与对应的主振信号相差预设频率。
  3. 根据权利要求2所述的光发射模块，其中，所述高频调制信号输出单元包括至少两个锁相环，每个锁相环设置为输出一个主振信号和与所述主振信号对应的本振信号。
  4. 根据权利要求1所述的光发射模块，其中，所述激光发射单元包括激光二极管。
  5. 根据权利要求4所述的光发射模块，其中，所述激光发射单元还包括准直透镜，所述激光二极管与所述准直透镜沿光束的传播方向依次排列，所述准直透镜设置为对所述激光二极管发出的激光光束进行准直。
  6. 根据权利要求2或3所述的光发射模块，其中，不同的主振信号的频率的差值在预设频率范围内。
  7. 根据权利要求1-6任一项所述的光发射模块，其中，所述至少两个不同频率的参考信号为至少两个不同频率的参考激光光束或者为至少两个不同频率的参考电信号。
  8. 一种光发射单元，包括光源子单元、高频调制子单元和差频子单元；
    所述光源子单元设置为发出初始光束；
    所述高频调制子单元设置为通过光混频技术对所述初始光束进行频率调制，发出至少两种不同频率的高频发射信号；
    所述差频子单元设置为将任意两种不同频率的高频发射信号进行差频处理， 发出至少一种低频发射信号；
    其中，至少一种所述高频发射信号和至少一种所述低频发射信号作为探测光信号，由所述光发射单元发出。
  9. 根据权利要求8所述的光发射单元，其中，所述高频调制子单元包括频率合成器；
    所述频率合成器设置为通过直接数字频率合成技术将预设的至少两个不同的高频率值加载到所述光源子单元发出的初始光束上，以形成至少两种不同频率的高频发射信号。
  10. 根据权利要求8或9所述的光发射单元，其中，所述光源子单元包括低功率连续激光二极管。
  11. 根据权利要求10所述的光发射单元，其中，所述光源子单元还包括准直透镜，所述低功率连续激光二极管与所述准直透镜沿光束的传播方向依次排列；
    所述准直透镜设置为对所述低功率连续激光二极管发出的初始光束进行准直。
  12. 一种光信号检测模块，包括信号接收单元和信号处理单元，所述信号接收单元与所述信号处理单元电连接；
    所述信号接收单元设置为接收第一参考信号、第二参考信号、第一高频回波信号和第二高频回波信号；其中，所述第一参考信号为经第一高频调制信号调制后的参考信号，所述第二参考信号为经第二高频调制信号调制后的参考信号；所述第一高频回波信号为第一激光光束被目标物体反射后的激光光束，所述第二高频回波信号为第二激光光束被所述目标物体反射后的激光光束；所述第一激光光束为经所述第一高频调制信号调制后的激光光束，所述第二激光光束为经所述第二高频调制信号调制后的激光光束；所述第一高频调制信号的频率大于所述第二高频调制信号的频率；
    所述信号处理单元设置为：根据所述第一参考信号与所述第一高频回波信号之间的第一相位差获取所述目标物体的第一参考距离值；根据所述第一相位差与第二相位差获取所述目标物体的第二参考距离值，并根据所述第一参考距离值和所述第二参考距离值确定所述目标物体的测量距离值；其中，所述第二相位差为所述第二参考信号与所述第二高频回波信号之间的相位差。
  13. 根据权利要求12所述的光信号检测模块，其中，所述第一参考信号和所述第二参考信号分别为第一参考激光光束和第二参考激光光束，或者分别为第一参考电信号或者第二参考电信号。
  14. 根据权利要求13所述的光信号检测模块，其中，所述信号接收单元还设置为：接收第一本振信号；将所述第一高频回波信号转换为对应的电信号，将所述第一高频回波信号对应的电信号与所述第一本振信号进行混频，得到第一差频测量信号；将所述第一参考激光光束转换为对应的电信号并将所述第一参考激光光束对应的电信号与所述第一本振信号进行混频，或者将所述第一参考电信号与所述第一本振信号进行混频，得到第一差频参考信号；接收第二本振信号；将所述第二高频回波信号转换为对应的电信号，将所述第二高频回波信号对应的电信号与所述第二本振信号进行混频，得到第二差频测量信号；将所述第二参考激光光束转换为对应的电信号并将所述第二参考激光光束对应的电信号与所述第二本振信号进行混频，或者将所述第二参考电信号与所述第二本振信号进行混频，得到第二差频参考信号；其中，所述第一高频调制信号为第一主振信号，所述第二高频调制信号为第二主振信号，所述第一主振信号与所述第一本振信号的频率相差预设频率，所述第二主振信号与所述第二本振信号的频率相差所述预设频率；
    所述信号处理单元是设置为通过如下方式根据所述第一参考信号与所述第一高频回波信号之间的第一相位差获取所述目标物体的第一参考距离值：将所述第一差频测量信号与所述第一差频参考信号进行比较得到第一相位差，根据所述第一相位差获取所述目标物体的第一参考距离值；
    所述信号处理单元是设置为通过如下方式根据所述第一相位差与第二相位差获取所述目标物体的第二参考距离值：将所述第二差频测量信号与所述第二差频参考信号进行比较，得到第二相位差；计算所述第二相位差与所述第一相位差之间的第三相位差；根据所述第三相位差获取所述目标物体的第二参考距离值。
  15. 根据权利要求12、13或14所述的光信号检测模块，其中，所述信号接收单元包括光电探测器。
  16. 根据权利要求15所述的光信号检测模块，其中，所述信号接收单元还包括接收透镜和滤光片，所述接收透镜、所述滤光片和所述光电探测器沿光束的传播方向依次排列；
    所述接收透镜设置为将所述第一高频回波信号和所述第二高频回波信号聚焦到所述光电探测器；
    所述滤光片设置为通过所述所述第一高频回波信号和所述第二高频回波信号，滤除其他波长的干扰信号。
  17. 根据权利要求14所述的光信号检测模块，其中，所述信号处理单元包 括运算放大器、模数转换器和现场可编程门阵列；
    所述运算放大器的输入端与所述信号接收单元电连接，所述运算放大器的输出端与所述模数转换器的输入端电连接，所述模数转换器的输出端与所述现场可编程门阵列电连接；
    所述运算放大器设置为分别将所述信号接收单元传输的所述第一差频测量信号、所述第一差频参考信号、所述第二差频测量信号以及所述第二差频参考信号放大；
    所述模数转换器设置为分别将经所述运算放大器放大后的所述第一差频测量信号、所述第一差频参考信号、所述第二差频测量信号以及所述第二差频参考信号由模拟量信号转换为数字量信号；
    所述现场可编程门阵列设置为将所述第一差频测量信号对应的数字量信号与所述第一差频参考信号对应的数字量信号进行比较得到第一相位差，并根据所述第一相位差计算所述目标物体的第一参考距离值；将所述第二差频测量信号对应的数字量信号与所述第二差频参考信号对应的数字量信号进行比较，得到第二相位差；计算所述第二相位差与所述第一相位差之间的第三相位差，根据所述第三相位差计算所述目标物体的第二参考距离值；根据所述第一参考距离值和所述第二参考距离值确定所述目标物体的测量距离值。
  18. 根据权利要求12-17任一项所述的光信号检测模块，还包括：供电单元、微处理器单元和高压调节单元；
    所述信号处理单元的受电端和所述微处理器单元的受电端分别与所述供电单元电连接，所述微处理器单元的第一控制端与所述信号处理单元电连接，所述微处理器单元的第二控制端通过所述高压调节单元与所述信号接收单元电连接；
    所述供电单元设置为向所述信号处理单元和所述微处理器单元供电；
    所述微处理器单元设置为对所述信号处理单元进行控制处理，还设置为通过所述高压调节单元对施加到所述信号接收单元的电压进行调节，以使所述信号接收单元接收强度不同的回波信号。
  19. 根据权利要求18所述的光信号检测模块，还包括温度探测单元、高压探测单元和标准电压探测单元，所述温度探测单元的输出端、所述高压探测单元的输出端和所述标准电压探测单元的输出端分别与所述微处理器单元的输入端电连接；
    所述温度探测单元设置为探测所述信号接收单元的温度值，所述高压探测单元设置为探测所述信号接收单元的高压值，所述标准电压探测单元设置为探 测所述信号接收单元的标准电压值；
    所述微处理器单元还设置为根据所述温度值、所述高压值或所述标准电压值对所述高压调节单元输出的电压进行调节。
  20. 一种光学系统，包括：权利要求1-7任一项所述的光发射模块，以及与所述光发射模块连接的信号接收单元；
    所述信号接收单元设置为接收第一参考信号、第二参考信号、第一高频回波信号和第二高频回波信号；其中，所述第一参考激信号为所述光发射模块发射的经第一高频调制信号调制的参考信号，所述第二参考信号为所述光发射模块发射的经第二高频调制信号调制后的参考信号；所述第一高频回波信号为所述第一激光光束被目标物体反射后的激光光束，所述第二高频回波信号为第二激光光束被所述目标物体反射后的激光光束；所述第一激光光束为所述光发射模块发射的经所述第一高频调制信号调制后的激光光束，所述第二激光光束为所述光发射模块发射的经所述第二高频调制信号调制后的激光光束；所述第一高频调制信号的频率大于所述第二高频调制信号的频率。
  21. 根据权利要求20所述的光学系统，其中，所述第一参考信号和所述第二参考信号分别为第一参考激光光束和第二参考激光光束，或者分别为第一参考电信号或者第二参考电信号。
  22. 根据权利要求21所述的光学系统，其中，所述信号接收单元还设置为：接收所述光发射模块发射的第一本振信号；将所述第一高频回波信号转换为对应的电信号，将所述第一高频回波信号对应的电信号与所述第一本振信号进行混频，得到第一差频测量信号；将所述第一参考激光光束转换为对应的电信号并将所述第一参考激光光束对应的电信号与所述第一本振信号进行混频，或者将所述第一参考电信号与所述第一本振信号进行混频，得到第一差频参考信号；接收所述光发射模块发射的第二本振信号，将所述第二高频回波信号转换为对应的电信号，将所述第二高频回波信号对应的电信号与所述第二本振信号进行混频，得到第二差频测量信号；将所述第二参考激光光束转换为对应的电信号并将所述第二参考激光光束对应的电信号与所述第二本振信号进行混频，或者将所述第二参考电信号与所述第二本振信号进行混频，得到第二差频参考信号；其中，所述第一高频调制信号为第一主振信号，所述第二高频调制信号为第二主振信号，所述第一主振信号与所述第一本振信号的频率相差预设频率，所述第二主振信号与所述第二本振信号的频率相差所述预设频率。
  23. 根据权利要求22所述的光学系统，其中，所述信号接收单元包括光电探测器。
  24. 根据权利要求23所述的光信号检测模块，其中，所述信号接收单元还包括接收透镜和滤光片，所述接收透镜、所述滤光片和所述光电探测器沿光束的传播方向依次排列；
    所述接收透镜设置为将所述第一高频回波信号和所述第二高频回波信号聚焦到所述光电探测器；
    所述滤光片设置为通过所述第一高频回波信号和所述第二高频回波信号，滤除其他波长的干扰信号。
  25. 根据权利要求22、23或24所述的光学系统，其中，所述光发射模块与所述信号接收单元之间的光路布局包括：同轴系统、双发射单接收系统、单发射单接收系统或双发射双接收系统。
  26. 一种激光雷达系统，包括权利要求1-7任一项所述的光发射模块，以及权利要求12-19任一项所述的光信号检测模块。
  27. 根据权利要求26所述的激光雷达系统，还包括角度探测单元，所述角度探测单元与所述信号处理单元电连接；
    所述角度探测单元设置为探测所述激光雷达系统旋转的角度值；
    所述信号处理单元还设置为将目标物体的测量距离值的变化量与所述角度值的变化量相关联。
  28. 根据权利要求27所述的激光雷达系统，其中，所述激光雷达系统旋转的传动方式包括：有刷电机、无刷电机或无线供电。
  29. 根据权利要求26或27所述的激光雷达系统，还包括通信单元；
    所述通信单元与所述信号处理单元电连接；
    所述通信单元设置为将信号处理单元得到的所述测量距离值、所述角度值以及所述测量距离值的变化量与所述角度值的变化量的关联关系中的至少一种传输给一反馈信号接收单元。
  30. 根据权利要求26所述的激光雷达系统，其中，所述通信单元的通信方式可包括：光通信、蓝牙通信或无线保真WIFI通信。
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