CN114415192B

CN114415192B - Laser radar system and calibration method thereof

Info

Publication number: CN114415192B
Application number: CN202210309936.7A
Authority: CN
Inventors: 解华彪; 刘佳尧; 夏冰冰; 石拓
Original assignee: Zvision Technologies Co Ltd
Current assignee: Zvision Technologies Co Ltd
Priority date: 2022-03-28
Filing date: 2022-03-28
Publication date: 2022-07-05
Anticipated expiration: 2042-03-28
Also published as: WO2023185757A1; CN114415192A

Abstract

The present disclosure relates to a laser radar system and a calibration method thereof. The present disclosure provides a method for calibrating a lidar system, as well as a lidar system, a vehicle, an electronic device, and corresponding media and program products for performing the method. The lidar system includes a fiber laser. The method includes instructing, by one or more processors, a fiber laser of the lidar system to emit one or more calibration beams during a light emission zone of a calibration period. The method also includes instructing, by the one or more processors, the lidar system to detect the stray light signal during a light detection zone of the calibration period subsequent to the light emission zone. Stray light signals may include ambient light noise or pulsed light from other lidar systems. The method also includes adjusting, by the one or more processors, a configuration of the lidar system during a subsequent operating period based on the detected stray light signal.

Description

Laser radar system and calibration method thereof

Technical Field

The present disclosure relates to lidar systems, and more particularly to methods for calibrating lidar systems, lidar systems that perform the methods, vehicles, electronic devices, media, and program products.

Background

LiDAR systems, also known as laser detection and ranging (LiDAR or LADAR) systems, measure information of position, velocity, etc. of a target object by emitting a laser beam toward the target object and receiving a beam reflected from the target object. In addition to the desired reflected light from the target object, there is often stray light from other objects in the field of view (FOV) in the light detected by the lidar system through the light receiver, including ambient light such as intense sunlight, other vehicle lights, or beams from other lidar systems. When the lidar system is applied to a high-speed, long-distance (e.g., several hundred meters) scene (e.g., equipped with a vehicle with an Advanced Driving Assistance System (ADAS) or an autonomous driving function), the power of reflected light reaching the light receiver from a target object may be small in itself. When stray light is strong, the signal-to-noise ratio (SNR) of an output signal of the optical receiver is greatly deteriorated, measurement accuracy is reduced, and difficulty is brought to the use of a laser radar system.

Therefore, it is necessary to measure stray light from other objects in the field of view in order to adjust or optimize the measurement of the target object by the lidar system.

Disclosure of Invention

To address at least some of the above-identified deficiencies of current lidar systems, the present disclosure provides a method for calibrating a lidar system, and a lidar system, a vehicle, an electronic device, and corresponding media and program products that implement the method, that can improve the measurement of stray light during calibration, resulting in better calibration.

One aspect of the present disclosure relates to a method for calibrating a lidar system. The lidar system includes a fiber laser. The method includes instructing, by one or more processors, a fiber laser of the lidar system to emit one or more calibration beams during a light emission zone of a calibration period. The method also includes instructing, by the one or more processors, the lidar system to detect the stray light signal during a light detection zone of the calibration period subsequent to the light emission zone. Stray light signals may include ambient light noise or pulsed light from other lidar systems. The method also includes adjusting, by the one or more processors, a configuration of the lidar system during a subsequent operating period based on the detected stray light signal.

In some embodiments, the light detection zone is separated from the light emission zone by a quiet zone. The length of the silent zone is associated with the time at which the emitted one or more calibration beams are reflected back to the lidar system from the outside. The method also includes instructing, by the one or more processors, the lidar system to not detect the stray light signal during the quiet zone of the calibration period.

In some embodiments, the calibration period is set during a retrace period of the lidar system during which the scanner of the lidar system returns from an end of scan to a start of scan.

In some embodiments, the lidar system is a non-coaxial optical transceiver system.

In some embodiments, the calibration period is set during at least a portion of a scan period of the lidar system during which a scanner of the lidar system travels from a scan start point to a scan end point.

In some embodiments, instructing the lidar system to detect the stray light signal includes: the method further includes dividing at least a portion of the plurality of receive units of the lidar system into a plurality of receive unit subsets, and causing the lidar system to detect the stray light signal using the plurality of receive unit subsets in sequence during the light detection region during the calibration period.

In some embodiments, instructing the lidar system to detect the stray light signal includes: determining a first time from emission of the one or more calibration beams to Amplified Spontaneous Emission (ASE) optical noise increase of the fiber laser to reach an optical noise threshold based on the emitted one or more calibration beams; and upon or before expiration of the first time, instructing the lidar system to cease detecting the stray light signal.

In some embodiments, during the calibration period, the pump source of the fiber laser is turned on.

In some embodiments, adjusting the configuration of the lidar system during a subsequent operating period based on the detected stray light signal includes: based on determining that the stray light signal includes ambient light noise and determining that the receiving unit is disturbed, adjusting a configuration of the lidar system during a subsequent operating period, including at least one of: adjusting the transmitting power of a laser corresponding to an echo signal of the interfered receiving unit reflected by the scanning beam, adjusting the sensitivity of the interfered receiving unit and the relevant receiving circuit thereof, and adjusting the gain of the interfered receiving unit and the relevant receiving circuit thereof.

In some embodiments, adjusting the configuration of the lidar system during a subsequent operating period based on the detected stray light signal includes: determining that the stray light signal includes pulsed light from the other lidar system and that the receiving unit is interfered based on the detected stray light signal, and adjusting a configuration of the lidar system during a subsequent operating period based on determining that the stray light signal includes pulsed light from the other lidar system and that the receiving unit is interfered, including: the lidar system is operated at the anti-crosstalk operating parameter during a subsequent operating period.

Another aspect of the present disclosure relates to a lidar system. The lidar system includes a light source, a scanner, a light receiver, and a controller. The light source is configured to emit light. The light source comprises a fiber laser. The scanner is configured to direct light to scan a target object. The light receiver is configured to detect light reflected by the target object. A controller is communicatively coupled with the light source, the scanner, and the light receiver. The controller is configured to perform the method for calibrating a lidar system as previously described.

Another aspect of the present disclosure relates to a vehicle. The vehicle includes a lidar system and a vehicle controller. The lidar system includes a fiber laser. The vehicle controller is communicatively coupled with the lidar system. The vehicle controller is configured to perform the method for calibrating a lidar system as previously described.

Another aspect of the disclosure relates to an electronic device. The electronic device includes a processor and a memory. The memory is communicatively coupled to the processor and stores computer readable instructions. The computer readable instructions, when executed by the processor, cause the electronic device to perform the method for calibrating a lidar system as previously described.

Another aspect of the disclosure relates to a computer-readable storage medium having stored thereon computer-readable instructions that, when executed by a processor of an electronic device, cause the electronic device to perform the method for calibrating a lidar system as previously described.

Another aspect of the disclosure relates to a computer program product comprising computer readable instructions which, when executed by a processor of an electronic device, implement the method for calibrating a lidar system as previously described.

Drawings

The above and other objects and advantages of the present disclosure will be further described with reference to the accompanying drawings in conjunction with the specific embodiments. In the drawings, identical or corresponding features or components will be indicated by identical or corresponding reference numerals.

Fig. 1 shows a schematic composition diagram of a lidar system according to an embodiment of the disclosure.

Fig. 2a shows an example of distribution of laser light emitting points when the laser radar system performs field of view scanning according to an embodiment of the present disclosure.

Fig. 2b shows an example of a receive field of view of a lidar system according to an embodiment of the disclosure.

Fig. 2c shows a structural example of an optical receiver of the lidar system according to an embodiment of the present disclosure.

Fig. 2d illustrates an example of a laser light emission point and receive field of view correspondence for a lidar system according to an embodiment of the disclosure.

Fig. 3 shows a schematic diagram of a lidar system in the presence of stray light in the receive field of view.

Fig. 4 illustrates an exemplary operating mode of a lidar system during normal light emission during operation and its Amplified Spontaneous Emission (ASE) optical noise conditions, according to an embodiment of the disclosure.

Figure 5 shows the operating mode of the lidar system when it is not emitting light during the calibration period and its ASE optical noise.

Figure 6 illustrates an exemplary operating mode of a lidar system when emitting a calibration beam during a calibration period and its ASE optical noise situation according to an embodiment of the disclosure.

Figure 7 shows a schematic of the operational mode of a lidar system during a calibration period and its ASE optical noise situation according to an embodiment of the disclosure.

Fig. 8 shows a flow diagram of a method for calibrating a lidar system, according to an embodiment of the disclosure.

Fig. 9a and 9b respectively show a scanning line schematic diagram and a laser light-emitting point cloud schematic diagram when the laser radar system performs row-column raster scanning.

Fig. 10 illustrates different time configurations of a lidar system for a calibration period according to embodiments of the disclosure.

Fig. 11 shows a schematic composition diagram of a vehicle incorporating a lidar system according to an embodiment of the disclosure.

Fig. 12 shows a configuration block diagram of an electronic apparatus according to an embodiment of the present disclosure.

Detailed Description

The following detailed description is made with reference to the accompanying drawings and is provided to assist in a comprehensive understanding of various exemplary embodiments of the disclosure. The following description includes various details to aid understanding, but these details are to be regarded as examples only and are not intended to limit the disclosure, which is defined by the appended claims and their equivalents. The words and phrases used in the following description are used only to provide a clear and consistent understanding of the disclosure. In addition, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness. Those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the disclosure.

As previously mentioned, in calibrating a lidar system, stray light from other objects in the field of view needs to be measured. To accurately measure stray light, some existing methods require that the lidar system not emit light during calibration. However, the inventors of the present disclosure have recognized that these methods may present problems for lidar systems that employ fiber lasers.

The general working principle of fiber lasers is as follows: the pumping source provides pumping light, the pumping light makes the gain medium reach the population inversion after getting into the optic fibre as the gain medium, and the resonant cavity provides forward optical feedback for the photon of arousing, forms laser signal output when the gain is higher than the loss in the resonant cavity. The pump source may be a semiconductor laser.

In order not to occupy the normal operating time of the lidar system, the calibration period duration of the lidar system is typically relatively short. In the switching from the working period of normal light emission to the calibration period and then back to the working period, if the laser radar system is not to emit light in the calibration period, the laser needs to be quickly turned off and turned on again after a short time interval. For the fiber laser, the time for switching on and off the pump source is usually long, and the pump source is difficult to turn on again after being turned off within a short time interval. As a result, the fiber laser will be in a situation where the pump source is on and the enable signal triggering the laser to emit light is turned off, i.e., the pump source of the fiber laser is on but not emitting light. As the time during which the fiber laser is not emitting light accumulates, the fiber laser may generate Amplified Spontaneous Emission (ASE) optical noise, and the ASE optical noise may become stronger. ASE optical noise is a broadband light source that affects the measurement of stray light from other subjects during calibration. That is, the inventors of the present disclosure recognized that turning off the laser emission during the calibration period is not preferable for fiber lasers, as non-emission may not achieve a better stray light measurement effect instead.

Based on this, a method of calibrating a lidar system set forth in the present disclosure includes instructing the lidar system to emit a calibration beam during a calibration period. The emission of the calibration beam consumes the reversal particles in the optical fiber gain medium, the increase of ASE optical noise can be inhibited within a period of time, further, a period of time after the emission of the calibration beam can be utilized to detect a stray light signal, and the configuration of the laser radar system during the subsequent normal light emitting working period is adjusted based on the monitored stray light signal. The calibration method is particularly applicable to laser radar systems comprising fibre lasers.

Fig. 1 illustrates an exemplary lidar system 100 to which the techniques of this disclosure may be applied. Lidar system 100 may include a light source 102, a scanner 104, a light receiver 106, and a controller 108. The light source 102 emits an emission light beam for scanning the target object 120. The light source 102 may be a laser, for example a solid state laser such as a Vertical Cavity Surface Emitting Laser (VCSEL) or an external cavity semiconductor laser (ECDL), a laser diode, a fiber laser. Light source 102 may also include an LED. The light source 102 may emit light beams of different forms, including pulsed light, continuous light (CW), and quasi-continuous light. The operating wavelength of the light source may be 650nm to 1150nm, 800nm to 1000nm, 850nm to 950nm, or 1300nm to 1600 nm. In one or more embodiments, the light source 102 can also include an optical assembly optically coupled to the light source 102 for collimating or focusing the light beam emitted by the light source 102. In one or more embodiments, the light source 102 includes at least one fiber laser. Each emitted light beam emitted by the light source 102 may be a continuous light for a certain duration or may be one or more light pulses.

The scanner 104 is used to deflect the direction of the emitted beam from the light source 102 to scan the target object 120, enabling a wider field of emission or scanning view. The scanner 104 may include any number of optical mirrors driven by any number of drivers. For example, the scanner 104 may include a plane mirror, a prism, a mechanical galvanometer, a polarization grating, an Optical Phased Array (OPA), a micro-electromechanical system (MEMS) galvanometer. For MEMS galvanometers, the mirror surface rotates or translates in one or two dimensions under electrostatic/piezoelectric/electromagnetic actuation. Driven by the driver, the scanner 104 directs a light beam from a light source to various locations within the field of view to effect scanning of a target object 120 within the field of view.

After the beam is reflected from target object 120, a portion of the reflected light returns to laser radar system 100 and is received by light receiver 106. The light receiver 106 receives and detects a portion of the reflected light from the target object 120 and generates a corresponding electrical signal. The optical receiver may include a receiving unit and associated receiving circuitry. Each receiving circuit may be for processing an output electrical signal of a respective receiving unit. The receiving unit includes various forms of photodetectors or one-or two-dimensional arrays of photodetectors, and accordingly, the receiving circuit may be a circuit or an array of circuits. The photodetector measures the power, phase or time characteristics of the reflected light and generates a corresponding current output. The photodetector may be an avalanche diode (APD), a Single Photon Avalanche Diode (SPAD), a PN type photodiode, or a PIN type photodiode.

The controller 108 is communicatively coupled to one or more of the light source 102, the scanner 104, and the light receiver 106. The controller 108 may control whether and when the light source 102 emits a light beam. The controller 108 may control the scanner 104 to scan the beam to a particular location. The controller 108 may process and analyze the electrical signals output by the optical receivers to ultimately determine the position, velocity, etc., characteristics of the target object 120. The controller 108 may include an Integrated Circuit (IC), an Application Specific Integrated Circuit (ASIC), a microchip, a microcontroller, a central processing unit, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), or other circuitry suitable for executing instructions or implementing logical operations. The instructions executed by the controller 108 may be preloaded into an integrated or separate memory (not shown). The memory may store configuration data or commands for the light source 102, the scanner 104, or the light receiver 106. The memory may also store the electrical signal output from the optical receiver 106 or an analysis result based on the output electrical signal. For example, the memory may store information relating to stray light signals detected during the calibration period for use during subsequent operating periods. The memory may include Random Access Memory (RAM), Read Only Memory (ROM), a hard disk, an optical disk, a magnetic disk, flash memory or other volatile or non-volatile memory, etc. The controller 108 may include single or multiple processing circuits. In the case of multiple processing circuits, the processing circuits may have the same or different configurations, interacting or cooperating with each other electrically, magnetically, optically, acoustically, mechanically, etc.

In one or more embodiments, lidar system 100 may also include a transmit lens 110. The transmit lens 110 may be used to expand the light beam emitted by the light source 102 and steered by the scanner 104. The emission lens 110 may include a Diffractive Optical Element (DOE) for shaping, separating, or diffusing the light beam. The emission lens 110 may be present alone or may be integrated into other components (e.g., the scanner 104 or the light source 102). The position of the emission lens 110 in the emission optical path from the light source to the target object is not limited to that shown in fig. 1, but may be changed to other positions. For example, the emission lens may be disposed between the light source 102 and the scanner 104 such that the light beam emitted by the light source 102 is first expanded by the emission lens and then deflected by the scanner.

In one or more embodiments, lidar system 100 may also include a receive lens 112. The receive lens 112 is located before the light receiver 106 on a receive path of the emitted light from the target object 120 to the light receiver 106. The receive lens 112 may comprise an imaging system lens such that the focus of the reflected beam is in front of or behind or just above the detection surface of the photodetector or photodetector array. In some cases, instead of being present as a separate component, the receive lens 112 may also be integrated into the optical receiver 106.

In one or more embodiments, lidar system 100 may also include a housing 114 to enclose one or more of the aforementioned components therein for protection. In some embodiments, the housing 114 is an opaque material, and the housing 114 may be provided with a transparent region or window 116 to allow the transmission or reflection of the light beam to pass therethrough. In other embodiments, the housing 114 itself is a transparent material, thereby allowing the emitted or reflected light beams to pass from any location.

In some embodiments, lidar system 100 may include a coaxial optical transceiver system. The coaxial optical transceiving system means that a transmission path from the light source 102 to the target object 120 at least partially overlaps with a reception path from the target object 120 to the light receiver 106. For example, unlike that shown in FIG. 1, the reflected beam may travel back through the scanner 104 to the optical receiver 106. For the coaxial optical transceiver system, not only the emergent angle of the emitted light beam changes with the deflection of the scanner, but also the receiving angle of the light that can be received by the optical receiver synchronously changes with the deflection of the scanner, i.e., the receiving field of view always remains equivalent to the scanning range of the emitted light beam.

In other embodiments, lidar system 100 may include a non-coaxial optical transceiver system. The non-coaxial optical transceiving system means that there is no overlapping portion of a transmission path from the light source 102 to the target object 120 and a reception path from the target object 120 to the light receiver 106. For example, as shown in FIG. 1, the reflected beam no longer reaches the optical receiver 106 via the scanner 104. For non-coaxial optical transceiver systems, although the exit angle of the emitted beam varies with the scanner deflection, the total receive field of view of the optical receiver is fixed and does not vary with the scanner deflection.

The lidar system may control a scanner to direct the emitted light beam in accordance with a predetermined scan pattern. Typically, the scanner scans in space in a closed scanning pattern, and the scanning is repeated periodically. Common scanning patterns include row-column grating, lissajous figures, spiral figures, and the like. Fig. 2a shows an example of a laser spot cloud when the lidar system scans in a row-column raster-like scanning pattern. Each pixel point 204 in the cloud represents a location in the emission field of view (or scan field of view) where the scanner directs the emission beam. The collection of all pixel points 204 constitutes the transmit field of view 202 of the lidar system. The emission field of view 202 may have various shapes depending on the predetermined scan pattern, and is not limited to the rectangular shape shown in FIG. 2 a. Each pixel 204 may be associated with one or more emission beams or one or more measurements.

Fig. 2b shows an example of a receive field of view distribution for a lidar system that includes a non-coaxial optical transceiver system. In this example, the optical receiver of the lidar system is made up of a plurality of receive sub-modules, each of which includes one or more receive units and their respective receive circuits. Each receiving sub-module is capable of receiving reflected light over a relatively small range. For example, each rectangle 208 in fig. 2b represents the range of reflected light that a respective one of the receiving sub-modules of the lidar system is capable of receiving, also referred to as the receive field of view of the respective receiving sub-module. The collection of the receive fields of view of all the receive sub-modules constitutes the total receive field of view 206 of the optical receiver.

Fig. 2c shows a schematic diagram of the components of an optical receiver to provide the receive field of view lidar system of fig. 2 b. The optical receiver includes one or more receiving units 210 and corresponding one or more receiving circuits 214. The receiving units 210 are connected to respective receiving circuits 214 by electrical connections 212. For example, the receive field of view 208 in fig. 2b corresponds to the receive submodule comprised of the receive unit 216 and the corresponding receive circuitry 218 in fig. 2 c.

Fig. 2d shows an example of the correspondence between the lasing and receive fields of view for a lidar system with the scanned laser point cloud of fig. 2a and the receive field of view of fig. 2b in normal operation. In normal operation, the emission beam is directed to different positions in the emission field of view along with the deflection action of the scanner, and the controller instructs the receiving sub-module corresponding to the position in the receiving field of view in the optical receiver to be started to receive the reflection beam, so as to finish measurement. For example, pixel 218 may correspond to pixel 204 in fig. 2a and receive field of view 220 may correspond to receive field of view 208 in fig. 2 b. When the lidar system generates the emission beam pointing to the pixel point 218, the receiving sub-module corresponding to the receiving field 220 needs to be turned on, i.e. the receiving sub-module including the receiving unit 216 and the receiving circuit 218 in fig. 2c can be turned on. The receiving sub-modules of the optical receiver other than the receiving sub-module corresponding to the receiving field of view 220 may be turned off or hibernated.

It should be appreciated that the transmit field of view, receive field of view, and corresponding receive sub-module distributions shown in fig. 2 a-2 d are merely illustrative. The lidar system according to the present disclosure may have different scanning patterns, transmission fields of view, distribution of reception fields of view, shapes, numbers and distributions of reception sub-modules, and correspondence of transmission fields of view to reception fields of view.

Although dividing the receiving field of view into a plurality of smaller fields of view corresponding to the receiving sub-modules and opening the corresponding smaller fields of view according to the positions of the scanning point clouds can reduce noise and improve the signal-to-noise ratio to a certain extent, if stronger fixed or dynamic stray light exists in the range of the whole receiving field of view, the stray light still interferes with the measurement of the corresponding receiving sub-modules with which the field of view overlaps. Sources of stray light may be ambient light noise, including but not limited to: strong sunlight, road lights, lamp lights from other vehicles, or continuous light from other lidar systems. The source of stray light may also be pulsed light from other lidar systems. FIG. 3 illustrates an example of a lidar system receiving stray light in a field of view. The receive field of view 300 and the rectangular area 302 may correspond to the receive field of view 206 and the rectangular area 208 in fig. 2 b. Sunlight 304 and pulsed light 306 from other lidar systems are detected in the receive field of view 300. Although the receiving sub-modules corresponding to the rectangular area 302 are not affected by the sunlight 304 and the pulsed light 306, the receiving sub-modules corresponding to the rectangular area overlapping the position of the sunlight 304 or the pulsed light 306 are interfered, and the measurement accuracy is reduced. It is therefore necessary to measure stray light in the receive field of view and adjust the configuration of the lidar system or the respective receive sub-module in accordance with the measurement results to reduce or eliminate the interference effects from the stray light. This process is referred to as calibration of the lidar system.

The following discussion, in conjunction with fig. 4-5, describes that for a lidar system that includes a fiber laser, not emitting light during the calibration period does not facilitate improved measurements during the calibration process.

Fig. 4 illustrates an exemplary mode of operation of a lidar system when emitting light normally according to an embodiment of the disclosure. Normal illumination refers to the laser radar system emitting a beam to scan a target object and measuring the reflected beam (or called echo signal). During each operating period, the lidar system emits a scanning beam, selects the corresponding receiving sub-module, and detects the echo signal. After detecting the echo signal, the lidar system may calculate a distance of the target object according to the time of flight, calculate an object reflectivity according to the intensity and distance of the echo signal, and simultaneously calculate a spatial position of the target object according to a deflection position/deflection angle of the scanner when emitting the scanning beam, thereby obtaining a three-dimensional measurement result of the target object.

The length or period of the duty cycle may be constant or variable. In the example of fig. 4, the length of the on period, or light emission interval referred to as the scanning beam, is constant, denoted as time T1. Depending on the particular design of the lidar system, T1 is typically a few hundred nanoseconds to a few microseconds. The scanning beam emitted during each operating period may be a continuous light for a certain duration or may be one or more light pulses. The scanning beams emitted during different periods of operation may be the same or different. As shown in fig. 2a to 2d, the lidar system may emit scanning beams in a predetermined scanning pattern on a duty cycle by duty cycle basis and activate corresponding receiving sub-modules in the receiving field of view that cover the point cloud locations of the scanning beams to receive and detect the echo signals. During each period of operation, since the emission of the scanning beam consumes a certain number of inversion particles, ASE optical noise can be suppressed for a certain length of time. After the time length is exceeded, the ASE optical noise gradually increases until the ASE optical noise is suppressed again after the scanning beam of the next operation period is emitted. In general, the length of the working period may be set to be relatively short enough to complete the reception and detection of the corresponding receiving sub-module, so that the ASE optical noise has not accumulated to a large amount.

In addition, in order to detect the echo signal in time, the corresponding receiving sub-module can be configured to start receiving and detecting in a short time after the scanning beam is emitted, and at this time, the ASE optical noise does not start to accumulate or the accumulated amount is still small. Thus, the reception and detection of the echo signals during operation is substantially unaffected or less affected by the ASE optical noise.

Fig. 5 shows an exemplary mode of operation of the lidar system when the calibration period is not on. Before the calibration period is initiated, the lidar system may be operated in an on-period, as described in connection with fig. 4. At the end of the operating period, ASE optical noise gradually increases. Unlike the on-period, at the beginning of the calibration period, the lidar system does not emit light and therefore cannot consume the number of inversion particles that cause ASE optical noise to be generated. Also, for a fiber laser, although it can be made non-emitting by quickly turning off the enable control signal, its pump source is likely not to be turned off quickly with the start of the calibration period, resulting in a continuous increase in the number of inversion particles, ASE optical noise further accumulates and reaches a stable maximum over time. The time for ASE optical noise to reach a stable maximum from the appearance is typically several hundred microseconds, depending on the internal design of the fiber laser. In this process, if one or more receiving sub-modules are still configured to receive and detect the stray light sequentially or simultaneously, when the ASE optical noise increases to a certain optical noise threshold, the interference of the ASE optical noise on the stray light measurement result cannot be ignored, so that the measurement accuracy is reduced. Thus, the inventors of the present disclosure have recognized that for fiber lasers, not emitting light during the calibration period may not be the best solution, taking into account ASE optical noise.

In view of this, embodiments of the present disclosure propose to emit one or more calibration light beams during a calibration period to suppress ASE optical noise, and to measure stray light using a period of time during which ASE optical noise is suppressed. Some aspects of embodiments of the present disclosure are described below in conjunction with fig. 6 and 7.

As shown in fig. 7, a calibration period according to an embodiment of the present disclosure includes a light emitting area and a light detecting area in chronological order. The light emission zone may be a time period for which a fiber laser for a lidar system emits one or more calibration beams. The light detection region may be a time period for a light receiver of the lidar system to detect stray light signals. The light emitting region and light detecting region may be located anywhere within the calibration period, as long as the light emitting region is maintained before the light detecting region. The light emitting region may or may not be contiguous with the light detecting region. The pump source of the fiber laser is on during the calibration period, resulting in the possibility of accumulating ASE optical noise. However, due to the emission of one or more calibration beams, ASE light noise is suppressed for a period of time and then gradually increases. The length of the time period from the emission of one or more calibration beams to the gradual increase of the ASE optical noise to the optical noise threshold is denoted as T_maxThen T is_maxMay be a time length limit value of the light detection zone. The optical noise threshold may be predetermined based on the design of the lidar system and the particular scenario in which it is used (e.g., emitted beam power, receiver sensitivity, range, etc.). The lidar system may determine T from the emitted one or more calibration beams (e.g., from their intensity, time interval, number, etc.)_max. At the time of reaching T_maxAt or before the time, the laser radar system is controlled to terminate the light detection zone, i.e. to stop detecting stray light signals. Therefore, the stray light signal detection is hardly or rarely influenced by ASE optical noise, the calibration measurement accuracy is improved, and the calibration effect is improved.

Fig. 6 illustrates a specific example of a lidar system operating in the calibration period configuration of fig. 7, according to an embodiment of the disclosure. As shown in fig. 6, the fiber laser of the lidar system emits n calibration beams (corresponding to the light emitting region of fig. 7) in the light emitting region of the calibration period, where n is an integer greater than or equal to one. The n calibration beams are distributed at regular time intervals. The time interval between two consecutive alignment beams is T3. Each calibration beam may be a continuous light for a certain duration or may be one or more light pulses. The respective calibration beams may be the same or different. The larger n, the smaller T3, the longer the ASE optical noise suppression time after calibration beam emission, but after some degree no further improvement. Therefore, the optimal values of n and T3 can be selected depending on the fiber pulse laser and system specifics. In some embodiments, T3 is less than the time interval during which the laser radar system emits a scanning beam during normal lighting (i.e., time T1 in FIG. 4).

After the calibration light is emitted, the optical receiver of the laser radar system performs measurement of the stray light signal in the light detection region (corresponding to the light detection region of fig. 7). The length of time of the light detection zone may be from the end of the emission of the calibration light beam to the end of the current calibration period, denoted as T2. T2 may be less than T_max. In some embodiments, T2 may be greater than T1. In the case where the optical receiver includes a plurality of receiving sub-modules, the lidar system may use all of the receiving sub-modules for calibration measurements, or may only need to use at least some of the plurality of receiving sub-modules for calibration measurements. For example, with a priori knowledge of the stray light signal of the lidar system, such as the location of some strong ambient light source may be known in advance, then instead of using all receiving sub-modules for reception and detection, only the receiving sub-module associated with the stray light signal may be used.

In some embodiments, the lidar system may use all required receive sub-modules at once to make calibration measurements at the same time. This is possible when the parallel data processing capability of the optical receiver of the lidar system is strong. In this way, the calibration measurement can be done quickly in a short time, the period of time required for ASE optical noise to be suppressed can be short, and accordingly, the number of calibration beams required can be smaller, and the interval can be larger. In some cases, only one light pulse may even be required as a calibration beam. At this time, the calibration beam may be the same as the scanning beam during the normal light emitting operation. The calibration period and the working period differ only in the object and manner in which the light receiver performs reception detection. During operation, the optical receiver detects the echoes of the scanning beam and, typically, only the corresponding receiving sub-module is turned on depending on the orientation of the scanning beam. During the calibration period, the stray light signal is detected by the light receiver instead of the echo of the calibration light beam, and all receiving sub-modules can be turned on at one time for detection.

In other embodiments, the receiving sub-modules required by the lidar system may be divided into a plurality of sub-receiving sub-module groups, and the light detection region may be divided into a plurality of detection periods, and the plurality of sub-receiving sub-module groups may be sequentially used in each detection period to detect the stray light signal. The division of the plurality of receive sub-modules into a plurality of sub-groups of receive sub-modules may depend on the parallel data processing capabilities of the optical receivers of the lidar system. More specifically, the number of receiving sub-modules in each sub-group of receiving sub-modules may be determined according to the parallel data processing capability of the optical receiver. In some cases, each subset of receive sub-modules may include only one receive sub-module. In other cases, each sub-group of receive sub-modules may be divided into one or more rows, one or more columns, or other divisions, according to the array of receive elements.

On the other hand, the number of the plurality of detection periods set in the light detection region for one calibration period is also limited by the time length limit value T of the light detection region_max. When the number of the sub-groups of the receiving sub-modules is so large that the sum of a plurality of detection periods of the light detection region for sequentially using the sub-groups of the receiving sub-modules for reception detection exceeds the time length limit value T of the light detection region_maxTwo or more calibration periods may be provided, with reception detections for a plurality of subsets of reception sub-modules distributed within the two or more calibration periods. For example, in the example of fig. 6, each sub-group of receive sub-modules comprises one row of the array of receive cells, and it is assumed that for detecting stray light signals, it is necessary toUsing four rows of the array of receiving elements, a total of four detection periods T0 need to be scheduled. And according to T during a calibration period_maxOnly two detection periods T0 are allowed to be scheduled at most. Thus, two calibration periods may be used to complete one calibration measurement. The two calibration periods may or may not be contiguous in time. The emitted calibration light beams may be the same or different during different calibration periods.

In some embodiments, the light emission area and the light detection area of the calibration period may be separated by a quiet zone. The silent region is a period of time during which the optical receiver does not detect the stray light signal. The length of the silent zone is associated with the time required for the emitted one or more calibration light beams to reflect from the outside back to the light receiver. For example, in fig. 6, the silence region is represented by T4. Instead of using T2 as the photodetection region, only T5 was used as the photodetection region in this case. In this way, the light detection region avoids both interference of echoes of the calibration light beam and the possibility of ASE optical noise accumulating beyond the optical noise threshold. The stray light signal measured in such a light detection area has a higher accuracy.

FIG. 8 is a flow chart of a method 800 for calibrating a lidar system. Method 800 may be performed in laser radar system 100 of fig. 1. Method 800 begins at block 802, where one or more processors may instruct a fiber laser of laser radar system 100 to emit one or more calibration beams during a light emission zone of a calibration period. The one or more processors may be implemented in controller 108 of laser radar system 100. The calibration beam refers to a beam emitted during a calibration period. The main function of the calibration beam is to suppress ASE optical noise of the fiber laser. The calibration beam may be the same or different in characteristics of number of pulses, duration, time interval, intensity, etc. from the scanning beam during normal light emitting operation.

At block 804, the one or more processors may instruct laser radar system 100 to detect the stray light signal during a light detection zone following the light emission zone of the calibration period. The stray light signal is different from the echo signal of the emitted one or more calibration beams. Stray light signals may include ambient light noise or pulsed light from other lidar systems. In some exemplary embodiments, optical receiver 106 of lidar system 100 may receive a total signal including an echo signal of the calibration beam and a stray light signal during the light detection region and extract the stray light signal from the total signal based on known information about the echo signal of the calibration beam. In other exemplary embodiments, the optical receiver 106 may avoid receiving the echo signal of the calibration beam and receive only the stray light signal, for example, a quiet zone may be provided in the manner of fig. 6.

The specific configuration and implementation of the light emitting region and the light detecting region have been described in detail with reference to fig. 6 and 7, and are not described herein again.

At block 806, the one or more processors may adjust a configuration of lidar system 100 during a subsequent operating period based on the detected stray light signal. The on-period may be a period of time during which laser radar system 100 emits a scanning beam to scan a target object and receives and detects an echo signal reflected back from the target object by the scanning beam. The processor may determine the type of stray light based on characteristics of the detected stray light signal. For example, if the electrical signal corresponding to the detected stray light is a direct current signal, the processor may determine that the stray light signal includes ambient light noise. Ambient light noise includes, but is not limited to: daylight, road lights, light from other vehicle lights, and continuous light from other lidar systems. For another example, if the electrical signal corresponding to the detected stray light is a pulse signal, the processor may determine that the stray light signal includes pulsed light from other lidar systems. In addition, the processor can also determine a disturbed receiving submodule including the disturbed receiving unit and its associated receiving circuit according to the position of the detected stray light signal in the receiving field of view.

After determining the type of stray light and the disturbed receive sub-module, the processor may purposely adjust the configuration of lidar system 100 during subsequent periods of operation. For ambient light noise, the adjustment measures may include one or more of:

adjusting the transmitting power of a laser corresponding to an echo signal of the interfered receiving sub-module reflected by the scanning beam;

adjusting the sensitivity of the interfered receiving submodule; and

the gain of the interfered receiving sub-module is adjusted.

For example, when the ambient light noise is large, the emission power of the corresponding laser may be increased or the sensitivity/gain of the associated receiving sub-module may be increased, so that the signal-to-noise ratio of the echo signal of the received scanning beam with respect to the ambient light noise is increased. When the ambient light noise is small, the emission power of the corresponding laser can be reduced or the sensitivity/gain of the relevant receiving sub-module can be reduced, so that the consumed power of the system can be saved.

Whereas for pulsed light from other lidar systems, the adjustment measure may include operating the lidar system at anti-crosstalk operating parameters during a subsequent operating period. The anti-crosstalk working parameters are mainly used for improving the capability of the optical receiver of the laser radar system for distinguishing echo signals of the scanning light beam of the optical receiver from pulse light from other laser radar systems. Specifically, operating with anti-crosstalk operating parameters includes adjusting a pulse repetition frequency, an operating wavelength, or an intensity distribution, etc. of a laser corresponding to the interfered receiving sub-module, thereby enabling distinction from pulsed light of other lidar systems.

The laser radar system controls the scanner to generate different deflection according to the preset scanning pattern. When the scanning end point is reached from the scanning start point, a period of time is needed to return the deflection position of the scanner to the scanning start point for the next scanning round, and the period of time is called a retrace period. Accordingly, the process of the deflection position of the scanner from the scanning start point to the scanning end point is referred to as a scanning period. The scan period and the retrace period together form one frame of a scan of the field of view of the laser radar system. Fig. 9a and 9b respectively show a scanning line schematic diagram and a corresponding laser light-emitting point cloud schematic diagram when the laser radar system performs row-column raster scanning. Generally, in order to return the scanner to the scanning start quickly, the number of deflection positions in the retrace period is small, and the number of corresponding point clouds is also small. As in fig. 9a, the dense curve 902 represents the scan period and the sparse curve 904 represents the retrace period. Due to the fact that the number of point clouds in the retrace period is small, measured data are difficult to utilize, and therefore resources of the laser radar system are actually in an idle state in the retrace period.

Fig. 10 illustrates different time configurations of a lidar system for a calibration period (e.g., the calibration period shown in fig. 7) according to embodiments of the disclosure. The calibration period according to embodiments of the present disclosure may be arranged anywhere within the scan period or retrace period of a frame.

In some exemplary embodiments, one or more calibration periods of the lidar system may be set within the scanning period. In some cases, the calibration period may be multiplexed overlapping with the working period. At this time, the scanning beam is used as the calibration beam. The lidar system may receive and detect the echo signal of the scanning/calibration beam for a relatively close period of time after the scanning/calibration beam is emitted, and measure the stray light signal for a period of time after the on/calibration period. In other cases, the calibration periods may occur interleaved with the working periods. For example, the laser radar system may perform a scheduling period and a calibration period for each pixel of the scanning pattern, respectively, emit a scanning beam to measure the target object during the scheduling period, and emit a calibration beam to detect the stray light signal during the calibration period. The mode can be suitable for a coaxial optical transceiving system and a non-coaxial optical transceiving system.

In other exemplary embodiments, one or more calibration periods of the lidar system may be set within the flyback period. Therefore, the resource idle of the laser radar system in the flyback period can be avoided. This approach may be suitable for coaxial optical transceiver systems, but is particularly suitable for non-coaxial optical transceiver systems. For non-coaxial optical transceiver systems, the transmit field of view is constantly changing during the retrace period, but the receive field of view is independent of the deflection position of the scanner, so that one or more receive sub-modules can be traversed to measure a greater range of stray light signals within the receive field of view. The calibration period may be arranged at any position of the flyback period. If the number of the receiving submodules needing to be traversed is large, the whole flyback period can be filled with the calibration period; if the number of receiving submodules is small, only a part of the retrace interval can be selected to arrange the calibration interval. As previously mentioned, the selection of the receiving sub-module for each calibration period may be one or more, depending on the parallel data processing capabilities of the receiving system or other design factors. Generally, the time length of the retrace interval is shorter than the time length of the scan interval. To traverse all required receive sub-modules, the turn-on time of each receive sub-module may be shorter than the turn-on time of the receive sub-module during the active period.

In some embodiments, the calibration period may be performed at a fixed period, e.g., set one or more times per frame or every multiple frames, without any event triggers.

The duty cycle according to embodiments of the present disclosure may be located within the scan period (as shown in fig. 10), but may also be located within the retrace period (not shown) in some cases.

In some embodiments, techniques for calibrating a lidar system according to embodiments of the present disclosure may be implemented in one or more processors internal to the lidar system, e.g., by controller 108. In other embodiments, the techniques for calibrating a lidar system according to embodiments of the disclosure may also be implemented in one or more processors of a vehicle device, such as by a vehicle controller, when the lidar system is installed in the vehicle device. Alternatively, the techniques for calibrating a lidar system according to embodiments of the disclosure may be cooperatively implemented by a vehicle controller and a controller of the lidar system.

Fig. 11 shows a schematic composition diagram of a vehicle 1100 incorporating a lidar system, according to an embodiment of the disclosure. Vehicle 1100 may include at least a lidar system 1102, a vehicle controller 1104, and a mobility system 1106. Lidar system 1102 may be implemented using lidar system 100 of fig. 1. Accordingly, the light source 1112, the scanner 1114, the light receiver 1116, and the controller 1118 correspond to the light source 102, the scanner 104, the light receiver 106, and the controller 108 of the laser radar system 100, respectively. Except that the vehicle controller 1104 may be communicatively coupled to the light source 1112, the scanner 1114, and the light receiver 1116 via a controller 1118. In other embodiments, the vehicle controller 1104 may also be communicatively coupled directly to the light source 1112, the scanner 1114, and the light receiver 1116. In some embodiments, lidar system 1102 may not include controller 1118. The techniques for calibrating a lidar system according to embodiments of the disclosure may be implemented independently by the vehicle controller 1104 or may be implemented in part by the vehicle controller 1104 and in part by the controller 1118 in cooperation. The mobility system 1106 may include a power subsystem, a braking subsystem, and a steering subsystem, among others. Vehicle controller 1104 may adjust maneuvering system 1106 based on the detection of lidar system 1102.

Furthermore, techniques for calibrating a lidar system according to embodiments of the disclosure may also be implemented in electronic devices in the form of computer-readable instructions.

Fig. 12 shows a configuration block diagram of an electronic apparatus 1200 according to an embodiment of the present disclosure. Electronic device 1200 may be used to perform a method of calibrating a lidar system, such as method 800, according to embodiments of the present disclosure. The electronic device 1200 may be any type of general purpose or special purpose computing device, such as a desktop computer, a laptop computer, a server, a mainframe computer, a cloud-based computer, a tablet computer, a wearable device, a vehicle electronics, and so forth. As shown in fig. 12, the electronic apparatus 1200 includes an Input/Output (I/O) interface 1201, a network interface 1202, a memory 1204, and a processor 1203.

I/O interface 1201 is a collection of components that may receive input from a user and/or provide output to the user. The I/O interface 1201 may include, but is not limited to, buttons, keyboards, keypads, LCD displays, LED displays, or other similar display devices, including display devices having touch screen capabilities to enable interaction between a user and an electronic device.

Communication interface 1202 may include various adapters and circuitry implemented in software and/or hardware to enable communication with a lidar system using wired or wireless protocols. The wired protocol is, for example, any one or more of a serial port protocol, a parallel port protocol, an ethernet protocol, a USB protocol, or other wired communication protocol. The wireless protocol is, for example, any IEEE 802.11 Wi-Fi protocol, cellular network communication protocol, or the like.

The memory 1204 comprises a single memory or one or more memories or storage locations including, but not limited to, Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Read Only Memory (ROM), EPROM, EEPROM, flash memory, logic blocks of an FPGA, a hard disk, or any other layer of a hierarchy of memories. The memory 1204 may be used for storing any type of instructions, software or algorithms, including instructions 1205 for controlling the general functions and operations of the electronic device 1200.

The processor 1203 controls the general operation of the electronic device 1200. The processor 1203 may include, but is not limited to, a CPU, hardware microprocessor, hardware processor, multi-core processor, single-core processor, microcontroller, Application Specific Integrated Circuit (ASIC), DSP, or other similar processing device capable of executing any type of instructions, algorithms, or software for controlling the operation and function of the electronic device 1200 according to embodiments described in this disclosure. The processor 1203 may be various implementations of digital circuitry, analog circuitry, or mixed signal (a combination of analog and digital) circuitry that perform functions in a computing system. The processor 1203 may include, for example, a system such as an Integrated Circuit (IC), a portion or circuitry of a single processor core, an entire processor core, a single processor, a programmable hardware device such as a Field Programmable Gate Array (FPGA), and/or multiple processors.

An internal bus 1206 may be used to establish communication between components of the electronic device 1200.

Electronics 1200 are communicatively coupled to the lidar system to be calibrated to control operation of the lidar system. For example, a calibration method according to the present disclosure may be stored on the memory 1204 of the electronic device 1200 in the form of computer readable instructions. The processor 1203 implements the calibration method by reading stored computer readable instructions.

Although the electronic device 1200 is described using specific components, in alternative embodiments, different components may be present in the electronic device 1200. For example, electronic device 1200 may include one or more additional processors, memories, network interfaces, and/or I/O interfaces. Additionally, one or more of the components may not be present in the electronic device 1200. Additionally, although separate components are shown in fig. 12, in some embodiments some or all of a given component may be integrated into one or more of the other components in the electronic device 1200.

The present disclosure may be implemented as any combination of apparatus, systems, integrated circuits, and computer programs or program products on non-transitory computer readable media.

It should be understood that computer-executable instructions in a computer-readable storage medium or program product according to embodiments of the present disclosure may be configured to perform operations corresponding to the above-described apparatus and method embodiments. Embodiments of the computer-readable storage medium or program product will be apparent to those skilled in the art when the above apparatus and method embodiments are referenced, and thus the description will not be repeated. Computer-readable storage media and program products for carrying or including the above-described computer-executable instructions also fall within the scope of the present disclosure. Such storage media may include, but is not limited to, floppy disks, optical disks, magneto-optical disks, memory cards, memory sticks, and the like.

In addition, it should be understood that the series of processes and apparatuses described above may also be implemented by software and/or firmware. In the case of implementation by software and/or firmware, respective programs constituting the respective software are stored in a storage medium of the relevant device, and when the programs are executed, various functions can be performed.

For example, a plurality of functions included in one unit may be implemented by separate devices in the above embodiments. Alternatively, a plurality of functions implemented by a plurality of units in the above embodiments may be implemented by separate devices, respectively. In addition, one of the above functions may be implemented by a plurality of units. Such a configuration is included in the technical scope of the present disclosure.

In the present disclosure, the steps described in the flowcharts include not only the processing performed in time series in the described order but also the processing performed in parallel or individually without necessarily being performed in time series. Further, even in the steps processed in time series, the order may be changed as appropriate.

The terms "comprises," "comprising," or any other variation thereof, in the embodiments of the present disclosure are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The term "or" in this disclosure means an inclusive "or" rather than an exclusive "or". References to a "first" component do not necessarily require the provision of a "second" component. Furthermore, unless explicitly indicated otherwise, "first" or "second" components do not imply that the referenced components are limited to a particular order. The term "based on" means "based at least in part on".

Claims

1. A method for calibrating a lidar system comprising a fiber laser, the method comprising:

instructing, by one or more processors, a fiber laser of the lidar system to emit one or more calibration beams during a light emission zone of a calibration period;

instructing, by the one or more processors, the lidar system to detect a stray light signal during a light detection region of the calibration period after the light emission region, the stray light signal comprising ambient light noise or pulsed light from other lidar systems, wherein the light detection region terminates at or before a first time expires from an increase in Amplified Spontaneous Emission (ASE) light noise from emitting the one or more calibration light beams to the fiber laser to reach an optical noise threshold; and

adjusting, by the one or more processors, a configuration of the lidar system during a subsequent operating period based on the detected stray light signal.

2. The method of claim 1, wherein the light detection zone and the light emission zone are separated by a quiet zone, a length of the quiet zone being associated with a time at which the emitted one or more calibration beams are reflected back to the lidar system from the outside, the method further comprising:

instructing, by the one or more processors, the lidar system not to detect the stray light signal during a quiet zone of the calibration period.

3. The method of claim 1, wherein the calibration period is set during a flyback period of the lidar system during which a scanner of the lidar system returns from an end of scan to a start of scan.

4. The method of claim 3, wherein the lidar system is a non-coaxial optical transceiver system.

5. The method of claim 1, wherein the calibration period is provided within at least a portion of a scan period of the lidar system during which a scanner of the lidar system travels from a scan start point to a scan end point.

6. The method of claim 1, wherein instructing the lidar system to detect the stray light signal comprises:

dividing at least a portion of a plurality of receive units of a lidar system into a plurality of receive unit subgroups; and

and enabling the laser radar system to detect the stray light signal by using the plurality of receiving unit subgroups in sequence during the light detection area in the calibration period.

7. The method of claim 1, wherein instructing the lidar system to detect the stray light signal comprises:

determining the first time based on the emitted one or more calibration beams; and

upon or before the expiration of the first time, the lidar system is instructed to stop detecting the stray light signal.

8. The method of claim 1, wherein a pump source of the fiber laser is turned on during the calibration period.

9. The method of claim 1, wherein adjusting a configuration of the lidar system during a subsequent operating period based on the detected stray light signal comprises:

determining, based on the detected stray light signal, that the stray light signal includes ambient light noise and that the receiving unit is disturbed; and

based on determining that the stray light signal includes ambient light noise and determining that the receiving unit is disturbed, adjusting a configuration of the lidar system during a subsequent operating period, including at least one of:

adjusting the transmitting power of a laser corresponding to an echo signal of the interfered receiving unit reflected by the scanning beam;

adjusting the sensitivity of the interfered receiving unit and its associated receiving circuit; and

the gain of the interfered receiving unit and its associated receiving circuit is adjusted.

10. The method of claim 1, wherein adjusting the configuration of the lidar system during the subsequent operating period based on the detected stray light signal comprises:

determining, based on the detected stray light signal, that the stray light signal includes pulsed light from other lidar systems and that a disturbed receiving unit is determined; and

based on determining that the stray light signal includes pulsed light from other lidar systems and determining that a receiving unit is disturbed, adjusting a configuration of the lidar system during a subsequent operating period, comprising: the lidar system is caused to operate at anti-crosstalk operating parameters during a subsequent operating period.

11. A lidar system comprising:

a light source configured to emit light, the light source comprising a fiber laser;

a scanner configured to direct the light to scan a target object;

a light receiver configured to detect light reflected by the target object; and

a controller communicatively coupled with the light source, the scanner, and the light receiver, the controller configured to calibrate the lidar system, comprising:

instructing the fiber laser to emit one or more calibration beams during a light emission zone of a calibration period;

instructing a light receiver to detect a stray light signal during a light detection zone following the light emission zone of the calibration period, the stray light signal comprising ambient light noise or pulsed light from other lidar systems, wherein the light detection zone terminates at or before expiration of a first time from emission of the one or more calibration light beams to Amplified Spontaneous Emission (ASE) light noise of the fiber laser increasing to reach a light noise threshold; and

the configuration of the lidar system during a subsequent operating period is adjusted based on the detected stray light signal.

12. The lidar system of claim 11, wherein the light detection zone and the light emission zone are separated by a quiet zone, a length of the quiet zone being associated with a time at which the emitted one or more calibration beams are externally reflected back to the lidar system, the controller being further configured to:

during a quiet zone of the calibration period, the lidar system is instructed not to detect the stray light signal.

13. The lidar system of claim 11, wherein the calibration period is set within a retrace period of the lidar system during which a scanner of the lidar system returns from an end of scan to a start of scan.

14. The lidar system according to claim 13, wherein the lidar system is a non-coaxial optical transceiver system.

15. The lidar system of claim 11, wherein the calibration period is provided during at least a portion of a scan period of the lidar system during which a scanner of the lidar system travels from a scan start point to a scan end point.

16. A vehicle, comprising:

a laser radar system comprising a fiber laser; and

a vehicle controller communicatively coupled with the lidar system, the vehicle controller configured to perform the method for calibrating the lidar system of any of claims 1-10.

17. An electronic device, comprising:

a processor; and

a memory communicatively coupled to the processor and storing computer-readable instructions that, when executed by the processor, cause the electronic device to perform the method for calibrating a lidar system according to any of claims 1-10.

18. A computer-readable storage medium having computer-readable instructions stored thereon, which, when executed by a processor of an electronic device, cause the electronic device to perform the method of any of claims 1-10.