LIDAR system and method for focusing on a range of interest

Abstract

A LIDAR system and method for focusing on a region of interest is disclosed. Discussed herein is a LiDAR system that focuses on one or more regions of interest within a field of view.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number 201980052559.X, application date June 12, 2019, and titled “LIDAR system and method for focusing on a range of interest”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Application No. 62 / 685,333, filed on June 15, 2018, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates generally to laser scanning and, more particularly, to using a laser scanning system to focus on one or more ranges of interest within a field of view. Background Art

[0005] There are systems that enable vehicles to be driven semi-autonomously or fully autonomously. Such systems can use one or more ranging, mapping or object detection systems to provide sensory input to assist semi-autonomous or fully autonomous vehicle control. For example, a light detection and ranging (LiDAR) system can provide the sensory input required for semi-autonomous or fully autonomous vehicles. The LiDAR system uses light pulses to create an image or point cloud of the external environment. Some typical LiDAR systems include a light source, a pulse steering system, and a photodetector. The light source generates a light pulse that is directed in a specific direction by the pulse steering system when transmitted from the LiDAR system. When the transmitted light pulse is scattered by an object, some of the scattered light is returned to the LiDAR system as a return pulse. The photodetector detects the return pulse. Using the time and speed of light taken to detect the return pulse after the light pulse is transmitted, the LiDAR system can determine the distance to the object along the path of the transmitted light pulse. The pulse steering system can direct the light pulse along different paths to allow the LiDAR system to scan the surrounding environment and generate an image or point cloud. The LiDAR system can also use technologies other than time of flight and scanning to measure the surrounding environment. Summary of the invention

[0006] Embodiments discussed herein relate to using LiDAR systems and methods to focus on one or more regions of interest within a field of view. The regions of interest may occupy a specific portion of the field of view that requires additional data or scan resolution compared to regions of no interest. The LiDAR systems and methods discussed herein are capable of adjusting one or more factors within each field of view scan sequence to increase data collection from one or more regions of interest during each scan.

[0007] A further understanding of the nature and advantages of the embodiments discussed herein may be realized by reference to the remainder of the specification and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figures 1 to 3 An exemplary LiDAR system that uses pulse signals to measure distances to points in the external environment is illustrated.

[0009] Figure 4 Depicts a logical block diagram of an exemplary LiDAR system.

[0010] Figure 5 Depicting the light source of an exemplary LiDAR system.

[0011] Figure 6 Depicting a light detector of an exemplary LiDAR system.

[0012] Figure 7 An embodiment of a signal steering system using a single light source and detector is depicted.

[0013] Figure 8 An embodiment of a signal steering system using two light sources and two detectors is depicted.

[0014] Fig. 9 Depicted by Figure 8 An embodiment generates a portion of a scan pattern.

[0015] Fig.10 A portion of a scan pattern according to another embodiment is depicted.

[0016] Fig.11 A portion of a scan pattern according to yet another embodiment is depicted.

[0017] Fig.12 An illustrative field of view of a LiDAR system is shown according to an embodiment.

[0018] Fig.13 An illustrative block diagram of a LiDAR system according to an embodiment is shown.

[0019] Fig.14 An exemplary fiber tip arrangement is shown in accordance with an embodiment.

[0020] Fig.15A and Fig. 15B Several mirror alignment arrangements are shown that can be used for both ROI and non-ROI embodiments.

[0021] Fig. 15C Illustrative multiple collimator arrangements are shown that may be used for ROI and non-ROI embodiments.

[0022] Fig.15DAn exemplary collimator and lens arrangement according to an embodiment is shown.

[0023] Fig.16 Exemplary scanning resolutions using multiple fiber tips, multiple mirror alignment arrangements, or multiple collimator arrangements are shown according to embodiments.

[0024] Fig.17A Another illustrative diagram showing vertical resolution using multiple fiber tips or multiple mirror alignment arrangements according to embodiments.

[0025] Fig. 17B Shown according to various embodiments Fig.17A An illustrative close-up view of a sparse region within and Fig. 17C Shown according to various embodiments Fig.17A An illustrative close-up view of a dense area within.

[0026] Fig.18 An illustrative FOV is shown with laser pulses of variable size in accordance with an embodiment.

[0027] FIG. 19A to FIG. 19J An illustrative mirror is shown in accordance with various embodiments.

[0028] Fig. 20 Describing and Figure 8 An alternative system similar to the one depicted in .

[0029] Fig.21 Describe and Figure 8 An alternative system similar to the one depicted in .

[0030] Fig. 22 Illustrative polygons are shown according to an embodiment.

[0031] Fig.23 Describe the use according to the embodiment Fig. 22 The point map of the polygon.

[0032] Fig.24 An illustrative block diagram of a LiDAR system according to an embodiment is shown.

[0033] Fig.25A and Fig.25B Different resolutions of data points captured from an object are shown.

[0034] Fig.26A An exemplary optimized angular resolution in a vertical FOV relative to the ground is shown according to an embodiment.

[0035] Fig.26B An illustrative graph showing angular vertical resolution that varies continuously with vertical angle in FOV according to an embodiment.

[0036] Fig. 27 An illustrative graph showing angular vertical resolution as a function of vertical angle in a FOV according to an embodiment.

[0037] Figures 28 to 30 Different illustrative processes for processing a ROI according to various embodiments are shown. DETAILED DESCRIPTION

[0038] Illustrative embodiments are now described more fully hereinafter with reference to the accompanying drawings, in which representative examples are shown. In fact, the disclosed LiDAR systems and methods may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like reference numerals refer to like elements throughout the text.

[0039] In the following detailed description, for the purpose of illustration, many specific details are set forth to provide a thorough understanding of various embodiments. Those skilled in the art will recognize that these various embodiments are merely illustrative and are not intended to be limited in any way. For those skilled in the art who benefit from this disclosure, other embodiments will be easily conceived.

[0040] In addition, for the sake of clarity, all conventional features of the embodiments described herein are not shown or described. It will be readily appreciated by those skilled in the art that in the development of any such actual embodiment, many embodiment-specific decisions may be required to achieve specific design goals. These design goals may vary from one embodiment to another and from one developer to another. In addition, it will be appreciated that such development work may be complex and time-consuming, but this may be a routine engineering task for those skilled in the art who benefit from the present disclosure.

[0041] Some light detection and ranging (LiDAR) systems use a single light source to generate one or more light signals of a single wavelength that scan the surrounding environment. The signal is scanned using a steering system that directs the pulses in one or two dimensions to cover an area of ​​the field of view or surrounding environment (the scanning area). When these systems use mechanical components to direct the pulses, the system complexity increases because more moving parts are required.

[0042] For example, some embodiments of the present technology use one or more light sources that generate light signals of different wavelengths and / or along different optical paths. These light sources provide signals to the signal steering system at different angles so that the scanning areas for the light signals are different (e.g., if two light sources are used to create two light signals, the scanning areas associated with each light source are different). This allows the signal to be tuned to the appropriate transmission power with the possibility of overlapping scanning areas covering scans of different distances. (e.g., when using pulsed light signals) longer distances can be scanned with signals having higher power and / or lower repetition rates. (e.g., when using pulsed light signals) shorter distances can be scanned with signals having lower power and / or high repetition rates to increase point density.

[0043] As another example, some embodiments of the present technology use a signal steering system with one or more dispersion elements (e.g., gratings, optical combs, prisms, etc.) to direct pulsed signals based on the wavelength of the pulses. The dispersion elements can make fine adjustments to the optical path of the pulses, which may be difficult or impossible with a mechanical system. In addition, the use of one or more dispersion elements allows the signal steering system to use fewer mechanical components to achieve the desired scanning capabilities. This results in a simpler, more efficient (e.g., lower power) design that may be more reliable (due to fewer moving components).

[0044] Some LiDAR systems use the time of flight of a light signal (e.g., a light pulse) to determine the distance to an object in the light path. Figure 1 , an exemplary LiDAR system 100 includes a laser light source (e.g., a fiber laser), a steering system (e.g., a system of one or more moving mirrors), and a light detector (e.g., a photon detector having one or more optical devices). The LiDAR system 100 transmits light pulses 102 along a path 104 determined by the steering system of the LiDAR system 100. In the depicted example, the light pulses 102 generated by the laser light source are short pulses of laser light. In addition, the signal steering system of the LiDAR system 100 is a pulsed signal steering system. However, it should be recognized that the LiDAR system can operate by generating, transmitting, and detecting non-pulsed light signals, and can be used to derive the range to objects in the surrounding environment using techniques other than time of flight. For example, some LiDAR systems use frequency modulated continuous waves (i.e., "FMCW"). It should also be recognized that any of the techniques described herein with respect to time-of-flight-based systems using pulses can also be applied to LiDAR systems that do not use one or both of these techniques.

[0045] Reference again Figure 1(a time-of-flight LiDAR system using light pulses), when the light pulse 102 reaches the object 106, the light pulse 102 is scattered and the returning light pulse 108 will be reflected back to the system 100 along a path 110. The time from when the transmitted light pulse 102 leaves the LiDAR system 100 to when the returning light pulse 108 arrives at the LiDAR system 100 can be measured (e.g., by a processor or other electronic device within the LiDAR system). This time of flight combined with knowledge of the speed of light can be used to determine the range / distance from the LiDAR system 100 to the point on the object 106 where the light pulse 102 was scattered.

[0046] like Figure 2 As depicted in , by directing many light pulses, the LiDAR system 100 scans the external environment (e.g., by directing light pulses 102, 202, 206, 210 along paths 104, 204, 208, 212, respectively). Figure 3 As depicted in FIG, the LiDAR system 100 receives returning light pulses 108, 302, 306 (corresponding to transmitted light pulses 102, 202, 210, respectively) after objects 106 and 214 scatter the transmitted light pulses and reflect the pulses back along paths 110, 304, 308, respectively. Based on the direction of the transmitted light pulses (determined by the LiDAR system 100) and the calculated range from the LiDAR system 100 to the point on the object where the light pulses were scattered (e.g., a point on objects 106 and 214), the surrounding environment within the detection range (e.g., including the field of view between paths 104 and 212) can be accurately mapped (e.g., a point cloud or image can be created).

[0047] If a corresponding light pulse is not received for a particular transmitted light pulse, then it may be determined that there are no objects within a particular range of the LiDAR system 100 (e.g., the maximum scanning distance of the LiDAR system 100) that may scatter a sufficient amount of signal for the LiDAR light pulse. Figure 2 In the example, since the light pulse 206 does not generate a scattering event along its transmission path 208 within the predetermined detection range, (e.g. Figure 3 208 . The light pulse 206 (depicted in FIG. 20 ) will not have a corresponding returned light pulse. The LiDAR system 100 (or an external system in communication with the LiDAR system 100 ) may interpret this as the absence of an object along the path 208 within the detection range of the LiDAR system 100 .

[0048] exist Figure 2 In the embodiment, the transmitted light pulses 102, 202, 206, 210 may be transmitted in any order, serially, in parallel, or based on other timing relative to each other. Figure 2A one-dimensional array of transmitted light pulses is depicted, but the LiDAR system 100 may also optionally direct similar arrays of transmitted light pulses along other planes, so that a two-dimensional array of light pulses is transmitted. This two-dimensional array may be transmitted point by point, line by line, all at once, or in some other manner. A point cloud or image from a one-dimensional array (e.g., a single horizontal line) will produce two-dimensional information (e.g., (1) horizontal transmission direction and (2) range to an object). A point cloud or image from a two-dimensional array will have three-dimensional information (e.g., (1) horizontal transmission direction, (2) vertical transmission direction, and (3) range to an object).

[0049] The density of points in the point cloud or image from the LiDAR system 100 is equal to the number of pulses divided by the field of view. Assuming the field of view is fixed, in order to increase the density of points generated by a set of transmit-receive optical devices, the LiDAR system should excite pulses more frequently, in other words, a light source with a higher repetition rate is required. However, by sending pulses more frequently, the maximum distance that the LiDAR system can detect may be more limited. For example, if a returned signal from a distant object is received after the system transmits the next pulse, then if the system cannot correctly associate the returned signal with the transmitted signal, the returned signals may be detected in an order different from the order in which the corresponding signals were transmitted and mixed together. For illustration, consider an exemplary LiDAR system that can transmit laser pulses at a repetition rate between 500kHz and 1MHz. Based on the time it takes for the pulses to return to the LiDAR system, and to avoid mixing the returned pulses with the continuous pulses in conventional LiDAR designs, the maximum distance that the LiDAR system can detect can be 300 meters and 150 meters for 500kHz and 1MHz, respectively. The point density of a LiDAR system with a 500kHz repetition rate is half that of 1MHz. Thus, this example demonstrates that increasing the repetition rate from 500kHz to 1Mhz (and thus increasing the point density of the system) will significantly reduce the detection range of the system if the system cannot properly correlate returned signals that arrive out of order.

[0050] Figure 4A logical block diagram of a LiDAR system 100 is depicted, which includes a light source 402, a signal steering system 404, a light detector 406, and a controller 408. These components are coupled together using communication paths 410, 412, 414, 416, and 418. These communication paths represent communications (bidirectional or unidirectional) between various LiDAR system components, but not necessarily the physical components themselves. Although the communication paths can be implemented through one or more wires, buses, or optical fibers, the communication paths can also be wireless channels or open-air optical paths such that there is no physical communication medium. For example, in an exemplary LiDAR system, communication path 410 is one or more optical fibers, communication path 412 represents an optical path, and communication paths 414, 416, 418, and 420 are all one or more wires that carry electrical signals. Communication paths can also include more than one of the above types of communication media (e.g., they can include optical fibers and optical paths, or one or more optical fibers and one or more electrical wires).

[0051] The LiDAR system 100 may also include Figure 4 Other components not depicted in the drawings may include a power bus, power supplies, LED indicators, switches, etc. In addition, there may be other connections between components, such as a direct connection between the light source 402 and the light detector 406 so that the light detector 406 can accurately measure the time from when the light source 402 transmits a light pulse until the light detector 406 detects a returning light pulse.

[0052] Figure 5 A logical block diagram of one example of a fiber laser based light source 402 is depicted, but any number of light sources with varying architectures may be used as part of a LiDAR system. The light source 402 uses a seed 502 to generate initial light pulses of one or more wavelengths (e.g., 1550 nm), which are provided to a wavelength division multiplexer (WDM) 504 via an optical fiber 503. A pump 506 also provides laser power (of a different wavelength, such as 980 nm) to the WDM 504 via an optical fiber 505. The output of the WDM 504 is provided to a preamplifier 508 (which includes one or more amplifiers) via an optical fiber 507, which provides its output to a combiner 510 via an optical fiber 509. The combiner 510 also obtains laser power from a pump 512 via an optical fiber 511 and provides the pulses to a boost amplifier 514 via an optical fiber 513, which produces output light pulses on the optical fiber 410. The output light pulses are then fed to the steering system 404. In some variations, the light source 402 can generate pulses of different amplitudes based on the fiber gain curve of the optical fiber used in the source. The communication path 416 couples the light source 402 to the controller 408 ( Figure 4), so that the components of the light source 402 can be controlled by the controller 408 or communicate with the controller 408. Alternatively, the light source 402 can include its own controller. Instead of the controller 408 communicating directly with the components of the light source 402, a dedicated light source controller communicates with the controller 408 and controls the components of the light source 402 and / or communicates with the components of the light source 402. The light source 402 also includes other components not shown, such as one or more power connectors, a power supply, and / or a power cord.

[0053] Some other light sources include one or more laser diodes, short cavity fiber lasers, solid state lasers, and / or tunable external cavity diode lasers configured to generate one or more optical signals of different wavelengths. In some examples, the light source uses an amplifier (e.g., a preamplifier or a boost amplifier) ​​including a doped fiber amplifier, a solid state bulk amplifier, and / or a semiconductor optical amplifier configured to receive and amplify the optical signal.

[0054] return Figure 4 , the signal steering system 404 includes any number of components for steering the light signal generated by the light source 402. In some examples, the signal steering system 404 may include one or more optical redirection elements (e.g., mirrors or lenses) that steer the light pulses along the transmission path to scan the external environment (e.g., by rotation, vibration, or guidance). For example, these optical redirection elements may include MEMS mirrors, rotating polygon mirrors, or fixed mirrors to steer the transmitted pulse signals to different directions. The signal steering system 404 optionally also includes other optical components such as dispersive optical devices (e.g., diffuse lenses, prisms, or gratings) to further extend the coverage of the transmitted signal so as to increase the transmission area (i.e., field of view) of the LiDAR system 100. An example signal steering system is described in U.S. Patent Application Publication No. 2018 / 0188355 entitled “2DScanning High Precision LiDAR Using Combination of Rotating Concave Mirrorand Beam Steering Devices”, the contents of which are incorporated herein by reference in their entirety for all purposes. In some examples, the signal steering system 404 does not include any active optical components (e.g., it does not include any amplifiers). In some other examples, one or more components from the light source 402 (such as a boost amplifier) ​​can be included in the signal steering system 404. In some cases, the signal steering system 404 can be considered a LiDAR front end or a LiDAR scanner.

[0055] Some embodiments of the signal steering system include one or more optical redirection elements (e.g., mirrors or lenses) that redirect the returned light signal along the receive path (e.g., by rotation, vibration, or steering) to direct the returned light signal to the photodetector. The optical redirection elements that direct the light signal along the transmit and receive paths can be the same component (e.g., shared), separate components (e.g., dedicated), and / or a combination of shared and separate components. This means that in some cases, while the transmit and receive paths may partially overlap (or in some cases, substantially overlap), they are distinct.

[0056] Figure 6 The light detector 406 ( Figure 4 ) is a logical block diagram of one possible arrangement of components in the optical device 406. The optical detector 406 includes an optical device 604 (e.g., a system of one or more optical lenses) and a detector 602 (e.g., a charge coupled device (CCD), a photodiode, an avalanche photodiode, a photomultiplier vacuum tube, an image sensor, etc.), and the optical detector 406 is connected to the controller 408 ( Figure 4 ). Optics 604 may include one or more optoelectronic lenses to receive, focus, and direct the return signal. Photodetector 406 may include filters to selectively pass light of specific wavelengths. Photodetector 406 may also include a timing circuit that measures the time from the transmission pulse to the detection of the corresponding return pulse. This data may then be transmitted to controller 408 via communications line 418 ( Figure 4 ) or other device. Light detector 406 may also receive information about when light source 402 transmits light pulses via communication line 418 or other communication line not shown (e.g., an optical fiber from light source 402 that samples the transmitted light pulses). Alternatively, light detector 406 may provide a signal via communication line 418 indicating when a returning light pulse is detected. Other pulse data such as power, pulse shape, and / or wavelength may also be transmitted.

[0057] Back to Figure 4, controller 408 includes components for controlling LiDAR system 100 and communicating with external devices using the system. For example, controller 408 optionally includes one or more processors, memories, communication interfaces, sensors, storage devices, clocks, ASICs, FPGAs, and / or other devices that control light source 402, signal steering system 404, and / or light detector 406. In some examples, controller 408 controls the power, rate, timing, and / or other properties of the light signal generated by light source 402; controls the speed, transmission direction, and / or other parameters of light steering system 404; and / or controls the sensitivity and / or other parameters of light detector 406.

[0058] The controller 408 is optionally also configured to process data received from these components. In some examples, the controller determines the time taken from transmitting a light pulse until a corresponding returned light pulse is received; determines when a returned light pulse is not received for a transmitted light pulse; determines the transmission direction (e.g., horizontal and / or vertical information) of the transmitted / returned light pulse; determines an estimated range in a particular direction; and / or determines any other type of data related to the LiDAR system 100.

[0059] Figure 7 Depicted are signal steering systems (e.g., Figure 4 The polygon 702 has ten reflective sides (in Figure 7 702A-702E are visible in the figure, but can have any number of reflective sides. For example, other examples of polygon 702 have 6, 8, or 20 sides. Polygon 702 rotates around axis 703 based on a drive motor (not shown) to scan (e.g., via output 706, which is connected to a light source such as light source 402 described above) a signal delivered from a light source along a direction perpendicular to or at a non-zero angle to the rotation axis 703.

[0060] Mirror galvanometer 704 is positioned next to polygon 702 so that one or more signals emitted from light source output 706 (e.g., a fiber optic tip) are reflected from mirror galvanometer 704 and onto rotating polygon 702. Mirror galvanometer 704 is tilted so as to scan one or more signals from output 706 in a direction different from the direction in which polygon 702 scans the signals (e.g., edges 704A and 704B are tilted about an axis toward and away from polygon 702 so as to scan pulses along a path parallel to or at an angle to the axis of rotation of polygon 702). In some examples, polygon 702 is responsible for scanning one or more signals in the horizontal direction of the LiDAR system, and mirror galvanometer 704 is responsible for scanning one or more signals in the vertical direction. In some other examples, polygon 702 and mirror galvanometer 704 are configured in opposite manners. Although Figure 7 The example in uses a mirror galvanometer, but other components can be used instead. For example, a grating (with different wavelength pulses) or one or more rotating mirrors can be used. The solid black line shows an example signal path through the signal steering system.

[0061] Light returning from signal scattering (e.g., when light strikes an object) within region 708 (indicated by the dashed line) returns to rotating polygon 702, reflects back to mirror galvanometer 704, and is focused by lens 710 onto detector 712. Although lens 710 is depicted as a single lens, in some variations it is a system of one or more optical devices.

[0062] In addition to adding a second light source, Figure 8 Depicted with Figure 7, the second light source provides one or more signals from output 714. The light source for output 714 can be the same or different from the light source for output 706, and the light transmitted by output 714 can have the same or different wavelength as the light transmitted by output 706. Using multiple light outputs can increase the point density of the point diagram without sacrificing the maximum clear detection range of the system. For example, light output 714 can be positioned to transmit light at a different angle than output 706. Because the angle is different, the light transmitted from light source 706 is directed to a different area than the light transmitted from output 714. The dotted line shows an example pulse path of a pulse emitted from output 714. Therefore, one or more objects located in two different areas within the area can scatter light and return light to the LiDAR system. For example, area 716 (dashed / dotted line) indicates the area from which the return signal from the scattered signal returns to the LiDAR system. The returned light is reflected by polygon 702 and mirror galvanometer 704 and focused by lens 710 on detectors 712 and 718. Detectors 712 and 718 can each be configured to receive returned light from one of outputs 706 and 714, and this configuration can be achieved by precisely controlling the positions of detectors 712 and 718 and the wavelength(s) of the transmitted light. Note that the same lens (or optical system) can be used for both detectors 712 and 718. The offset between outputs 706 and 714 means that the light returned to the LiDAR system will have a similar offset. By appropriately positioning detectors 712 and 718 based on the relative positioning of the respective light source outputs of detectors 712 and 718 (e.g., the respective positions of outputs 706 and 714), and optionally, by appropriately controlling the wavelength(s) of the transmitted light, the returned light will be appropriately focused on the correct detector, and each received light can be a point in the spot diagram. Therefore, a system with two outputs can maintain the same pulse repetition rate and produce twice the number of points or reduce the pulse repetition rate by half and still produce the same number of points compared to a system with only one output 706. As a non-limiting example, a system with two optical outputs can reduce the pulse repetition frequency from 1 MHz to 500 KHz, thereby increasing its maximum unambiguous detection range from 150 meters to 300 meters without sacrificing the point density of the resulting spot map. Pulse repetition rates between 200 and 2 MHz are contemplated and disclosed.

[0063] Fig. 9 The spot diagram from the first design is depicted. This design has two channels (e.g., two light source outputs and two light detectors) placed in a way that the outgoing beams have an angle of 8 degrees vertically. The scanned pattern has a vertical overlap. The range of the scan is +-56 degrees horizontally and +12 degrees to -20 degrees vertically.

[0064] Fig.10 The spot diagram from the second design is depicted. This design has two channels (e.g., two light source outputs and two light detectors) placed in a way that the outgoing beam has an angle of 6 degrees. The scanned pattern has a horizontal overlap (+-45 degrees). The range of the scan is +-67 degrees horizontally and +12 degrees to -20 degrees vertically.

[0065] The outgoing beams of the two channels do not have to be at a specific angle (e.g. Fig.10 The horizontal range can be extended by 6 degrees (in 100 degrees) apart from the existing beams. Horizontal displacement of the existing beams can be used to extend the horizontal range. For example, the two outgoing beams can be pointed at the same angle, but offset relative to each other in the same plane. Due to these different positions, each channel is reflected by a different part of the polygon and therefore covers a different horizontal range. By combining the two channels, the total horizontal range is increased.

[0066] Fig.11 The point diagram from the third design is depicted. This design has three channels (e.g., three light source outputs and three light detectors) to increase the point density. About 2.88 million points per second can be obtained by using 3 fiber tips and 3 detectors. The resolution can be further reduced to 0.07 degrees for both directions. The speed of the polygon can be reduced to 6000rpm.

[0067] Fig.12 An exemplary field of view (FOV) 1200 of a LiDAR system according to an embodiment is shown. As shown, FOV 1200 is a two-dimensional space defined by an X dimension and a Y dimension. Although the LiDAR system can collect data points from the entire FOV 1200, certain regions of interest (ROIs) may have a higher priority than other regions within FOV 1200 (e.g., such as undesirable regions that occupy all of the space within FOV 1200 that is not an ROI). Fig.12Five different exemplary ROIs 1210-1214 are shown to illustrate different areas within the FOV 1200 that require more data points than other areas within the FOV 1200. For example, ROI 1210 occupies an entire band of fixed y-axis height across the x-axis of the FOV 1200. ROIs 1211 and 1212 illustrate localized ROIs below ROI 1210, and ROIs 1213 and 1214 illustrate localized ROIs above ROI 1210. It should be understood that there may be any number of ROIs, and that the ROIs may occupy any portion of the FOV 1200. The embodiments discussed herein enable additional data points to be collected in the ROIs in a manner that does not interrupt the operation of the LiDAR system. That is, the LiDAR scanning system may scan the entire FOV 1200 during each scanning cycle while controlling one or more parameters to obtain additional data points (or increase resolution) from the ROIs 1211-1214.

[0068] Fig.13 An illustrative block diagram of a LiDAR system 1300 according to an embodiment is shown. The LiDAR system 1300 may include a laser subsystem 1310, a receiver system 1320, a laser controller 1330, a region of interest controller 1340, a polygon structure 1350, a polygon controller 1355, a mirror 1360, and a mirror controller 1365. The LiDAR system 1300 may be contained within one or more housings. In multiple housing embodiments, at least one of the housings may be a temperature controlled environment in which selected portions of the LiDAR system 1300 (e.g., laser controller 1330, laser source 1312, controller 1340) are contained.

[0069] The laser subsystem 1310 can be operated to direct light energy to the mirror 1360, which redirects the light energy to the polygonal structure 1350. The mirror 1360 can also be operated to redirect the light energy received from the polygonal structure 1350 to the receiver system 1320. The mirror 1360 can be moved under the control of the mirror controller 1365, which can control the speed and direction of the mirror movement. As the mirror 1360 moves, it causes the light transmitted by the laser subsystem 1310 to engage with different parts of the polygonal structure 1350. The polygonal structure 1350 moves under the control of the polygon controller 1355 and is operable to direct the light energy received from the mirror 1360 according to the field of view parameters of the LiDAR system 1300. That is, if the LiDAR system 1300 has a field of view with a range of z, a lateral angle of x, and a vertical angle of y, then the range z may be controlled by the power of the laser source 1312, the vertical angle y may be controlled by the movement of the mirror 1360, and the lateral angle x may be controlled by the polygonal structure 1350. It should be appreciated that in the alternative, the vertical angle may be controlled by the polygonal structure 1350 and the lateral angle may be controlled by the mirror 1360. Light energy reflected from objects in the field of view and returned to the polygonal structure 1350 is directed back to the mirror 1360, which redirects the light energy back to the receiver system 1320.

[0070] As defined herein, frame rate may refer to the time taken by the scanning system 1302 to complete a complete scan of the FOV. For each frame, the scanning system 1302 may obtain data points from each of the multiple rows (or columns) defined by the FOV. Each row may correspond to a vertical angle within the vertical range of the FOV. The vertical angle may be controlled by the mirror 1360. As the mirror 1360 moves, the vertical angle changes, thereby enabling the scanning system 1302 to obtain data points from multiple rows within the FOV. Vertical angular resolution refers to the spacing between adjacent rows of data points. An increase in vertical angular resolution corresponds to a denser spacing between adjacent rows, and this increase may be achieved by reducing the increment of the vertical angle between adjacent vertical angles. The increment between adjacent vertical angles may be reduced by slowing down the movement of the mirror 1360. That is, as the mirror moves slower, the change in the vertical angle increment decreases. The reduction in vertical angular resolution corresponds to a sparser spacing between adjacent rows, and this reduction may be achieved by increasing the vertical angle increment. The increment between adjacent vertical angles may be increased by speeding up the movement of the mirror 1360. That is, as the mirror moves faster, the change in vertical angle increment increases.

[0071] The number of data points obtained within any row can depend on the horizontal angle within the horizontal range of the FOV. The horizontal range can be controlled by polygon 1350, and the horizontal angle resolution can be controlled by the time interval between consecutive laser pulses. The time interval is sometimes related to the repetition rate. A smaller time interval can result in increased horizontal angle resolution, and a larger time interval can result in reduced horizontal angle resolution.

[0072] The vertical and horizontal angles and vertical and horizontal angle resolutions mentioned above are made with reference to a system in which the mirror 1360 controls the vertical angle. It should be understood that the mirror 1360 can be reused to control the horizontal angle and in different Fig.13 used in the system shown.

[0073] The laser subsystem 1310 may include a laser source 1312 and fiber tips 1314-1316. As indicated by the "n" label of the fiber tip 1316, any number of fiber tips may be used. As shown, each of the fiber tips 1314-1316 may be associated with a laser source 1312. The laser source 1312 may be a fiber laser or a diode laser. The fiber tips 1314-1316 may be aligned in a fixed orientation so that light exiting each tip illuminates the mirror 1360 at a specific location. The actual orientation may depend on several factors, including, for example, frame rate, mirror movement and speed, polygon speed, ROI, repetition rate, etc. Additional discussion of the fiber tips and their characteristics for obtaining additional data points in the ROI is discussed in more detail below.

[0074] Receiver system 1320 may include various components, such as optics, detectors, control circuits, and other circuits. The optics may include a light-transmitting optic that collects the laser light returning from mirror 1360. The detector may generate a current or voltage signal when exposed to light energy through the optics. The detector may be, for example, an avalanche photodiode. The output of the detector may be processed by a control circuit and delivered to a control system (not shown) to enable processing of the return pulses.

[0075] The laser controller 1330 may be operated to control the laser source 1312. In particular, the laser controller 1330 may control the power of the laser source 1312, may control the repetition rate or time interval of the light pulses emitted by the laser source 1312 (via the time interval adjustment module 1332), and may control the pulse duration of the laser source 1312. The time interval adjustment module 1332 may be operated to control and / or adjust the repetition rate / time interval of the transmitter pulses of the laser 1310. The time interval adjustment circuit 1332 may change the repetition rate / time interval for different regions within the FOV. For example, the repetition rate may be increased for the ROI, but the repetition rate may be decreased for regions of the FOV that are not of interest. As another example, the time interval may be decreased for the ROI, and the time interval may be increased for regions of the FOV that are not of interest.

[0076] The region of interest controller 1340 can be operated to control the LiDAR system 1300 to obtain additional data points for the ROI. That is, when the LiDAR system 1300 is scanning the ROI, the ROI controller 1340 can cause the system 1300 to operate in a different manner than when the system 1300 is not scanning the ROI. The ROI controller 1340 can control the operation of the laser controller 1330, the polygon controller 1355, and the mirror controller 1365 to change the amount of data obtained by the system 1300. The ROI controller 1340 can receive several inputs indicating how it should control the scanning subsystem 1302. The inputs can include, for example, a frame rate 1342, a sparse area 1343, a dense area 1344, a distance range, or any other suitable input. The frame rate 1342 can specify the frequency at which the scanning subsystem 1302 completes a FOV scan. The sparse and dense areas 1343 and 1344 can provide a specific location of the ROI. For example, dense region 1344 may correspond to a ROI, and sparse region 1343 may correspond to an area within the FOV that is not a ROI. Fiber tip angle 1345 may be used as a design constraint within which scanning subsystem 1302 operates to optimally perform scanning.

[0077] The polygonal structure 1350 can be made of a metal such as aluminum, plastic, or other material that can have a polished or mirrored surface. The polygonal structure 1350 can be selectively masked according to the field of view of the scanning subsystem 1302 to control the lateral dispersion of the projected light energy. The polygonal structure 1350 can include multiple facets to accommodate a desired horizontal field of view (FOV). The facets can be parallel or non-parallel to their axis of symmetry. The polygonal structure 1350 is operable to rotate around an axis in a first direction at a substantially constant speed. The shape of the polygonal structure 1350 can be trimmed (e.g., cutting off sharp corners or tips to reduce overall weight or desired geometric envelope, chamfering sharp edges to reduce air resistance) to obtain better operating performance.

[0078] Mirror 1360 can be a single plane or multi-plane mirror that oscillates back and forth to redirect the light energy emitted by laser source 1312 to polygon 1350. A single plane mirror can provide a higher resolution at the top and bottom of the vertical field of view than in the middle, while a multi-plane mirror can provide a higher resolution at the middle of the vertical field of view than at the top and bottom. Mirror 1360 can be a galvanometer. Changing the oscillation speed within the oscillation period can enable scanning subsystem 1302 to acquire sparse or dense data points within the FOV. For example, if dense data points are required (for a particular ROI), the movement speed can be reduced, and if sparse data points are required (for non-ROI), the movement speed can be increased.

[0079] Fig.14 An exemplary fiber tip arrangement according to an embodiment is shown. Four fiber tips 1401-1404 are shown to be oriented relative to each other so that the same angle α exists between adjacent fiber tips. Multiple fiber tips can be used (as opposed to only one fiber tip) to achieve high data collection. When the ROI is scanned, the mirror movement speed is adjusted to the ROI speed (e.g., a speed slower than the sparse or non-ROI speed), and the combination of the additional fiber tips and the reduced relative mirror movement speed produces denser data capture. Moreover, when the non-ROI is scanned, the mirror movement speed is operated at the non-ROI speed (e.g., a speed faster than the ROI speed), and the presence of multiple fiber tips ensures that sufficient data collection is achieved. Angle α can be selected based on the properties (e.g., size) of the light energy emitted by each fiber tip, the speed and movement characteristics of the mirror (e.g., mirror 1360) for both the ROI and the non-ROI, and the speed of the polygon (e.g., polygonal structure 1350). The angles between each tip can be the same, or they can be different.

[0080] In some embodiments, all four fiber tips can be associated with the same laser source. Thus, if the laser source is turned off, no fiber tip will emit light energy. In another embodiment, each fiber tip can be associated with its own corresponding laser source. This embodiment provides a high degree of on / off control of each fiber tip. In yet another embodiment, a subset of fiber tips can be associated with the same laser source. For example, fiber tips FT1 and FT3 can share a first common laser source, and fiber tips FT2 and FT4 can share a second common laser source. This embodiment provides a balance between full on / off control or no on / off control and individual on / off control.

[0081] Fig.15A A multiple mirror alignment arrangement (MMAA) 1500 is shown that can be used for both ROI and non-ROI embodiments. MMAA 1500 is a method of using multiple fiber optic tips (such as Fig.14 ). As shown, MMAA 1500 shows collimator 1510, partial reflectors 1521-1523, and reflector 1524. Light energy originating from a laser source (not shown) is sent to collimator 1510, which directs the light energy to partial reflector 1521. Partial reflector 1521 allows a portion of the light energy to pass (shown as exit path 1531), and the remaining light energy is redirected to partial reflector 1522. Partial reflector 1522 allows a portion of the light energy to pass through and reach partial reflector 1523. Partial reflector 1522 redirects the light energy along exit path 1532. Partial reflector allows a portion of the light energy to pass through and reach partial reflector 1524. Partial reflector 1523 redirects the light energy along exit path 1533. Reflector 1524 can redirect all or at least a portion of all the remaining light energy along exit path 1534.

[0082] The angle between adjacent exit paths can be selected to achieve the desired resolution of the ROI and non-ROI. For example, the angle between adjacent exit paths can be Fig.14 In some embodiments, the angle between adjacent exit paths may be fixed. In other embodiments, the angle between adjacent exit paths may be variable. Variable angle adjustment may be used to provide different resolutions as required. For example, if a LiDAR system is used in a vehicle, the angle may be set to a first configuration when the vehicle is operating in a first mode (e.g., traveling at highway speeds or being driven by a first driver), and the angle may be set to a second configuration when the vehicle is operating in a second mode (e.g., traveling at city speeds or being driven by a second driver).

[0083] Fig. 15BAnother multiple mirror alignment arrangement (MMAA) 1501 that can be used for ROI and non-ROI embodiments is shown. MMAA 1501 is an alternative to MMAA 1500. As shown, MMAA 1501 shows a collimator 1512, partial reflectors 1525-1527, a reflector 1528, and an exit path 1535-1538. MMAA 1501 is similar to MMAA 1500 except for the positioning of collimator 1512. As shown, collimator 1512 is positioned above mirror 1525. If desired, collimator 1512 can be positioned below mirror 1528. As a further alternative, collimator 1512 can be aimed at a different mirror (such as mirror 1526 or mirror 1527), and such a mirror can redirect light energy as needed to achieve the desired result.

[0084] Fig. 15C An exemplary multiple collimator arrangement 1550 that can be used for ROI and non-ROI embodiments is shown. Arrangement 1550 may include collimators 1561-1563. Each of collimators 1561-1563 may be associated with its own laser source. Associating each collimator with its own laser source enables selective switching on and off of the light energy emitted from each collimator. For sparse areas, one or more laser sources may be turned off (to save power), and for dense areas, all laser sources may be turned on to maximize resolution. Each of collimators 1561-1563 may be fixed in a specific orientation to achieve a desired α angle between each collimator. If desired, each of collimators 1561-1563 may be movable to dynamically adjust the α angle between each collimator.

[0085] Fig.15D An exemplary collimator and lens arrangement 1570 is shown that can be used to control the divergence of a beam of an existing collimator 1571 according to an embodiment. The lens 1572 can be moved toward and away from the collimator 1571 to adjust the divergence of the beam. When the beam is projected by the scanning system, the arrangement 1570 can be used to adjust the size of the beam. For the ROI area, it may be desirable to have a relatively narrow beam. In order to produce a relatively narrow beam, the lens 1572 can be positioned at a narrow beam distance from the collimator 1571. For non-ROI areas, it may be desirable to have a relatively wide beam. In order to produce a relatively wide beam, the lens 1572 can be positioned at a wide beam distance from the collimator 1571.

[0086] Fig.16Illustrative scanning resolutions using multiple fiber tips, multiple mirror alignment arrangements, or multiple collimator arrangements are shown according to embodiments. Illustrative vertical resolution lines from the fiber tips (FT1-FT4) are shown. As shown, the resolution lines are grouped according to sparse resolution and dense resolution. In sparse areas, the scanning system moves the mirror at a relatively faster speed than in dense areas, and in dense areas, the scanning system moves the mirror at a relatively slower speed than in sparse areas. (As FT 1 -FT 4 The spacing between adjacent scan lines is substantially equidistant (as shown in a repeating pattern of ). Such equidistant spacing can be made possible by coordinating the alignment of the fiber tips with the frame rate, mirror speed, polygon speed, and any other suitable factors. In contrast, if the alignment of the fiber tips is not properly coordinated, then equidistant spacing may not be possible, resulting in an undesirable scan pattern. In dense areas, each fiber tip can provide multiple resolution lines. For example, as shown, FT1 provides four resolution lines before FT2 provides its four resolution lines. Thus, each fiber tip provides four resolution lines before transitioning to the next fiber tip. It should be understood that the number of resolution lines provided by each fiber tip depends on a number of factors, including, for example, the mirror speed, the polygon speed, and the angle between the fiber tips. The resolution lines between the fiber tips can be staggered at the transition between sparse areas and dense areas. For example, (as shown in a repeating pattern of ). Fig.17A ) at least one resolution line from one or more of the fiber tips FT2-FT4 may be interleaved among the four resolution lines associated with FT1.

[0087] The angle (e.g., α) between the fiber tips can be selected to be substantially equidistant from each other based on the desired angular resolution of the ROI, the polygon velocity, the mirror velocity, and the spacing requirements between the resolution lines in (one or more) sparse regions. At least two different mirror speeds are used to provide dense resolution and sparse resolution, and if the angle between the fiber tips is not properly aligned, then the difference in mirror speed may cause the resolution lines to be unequally spaced. For example, assume the angle for the dense region is θ. θ can represent the total number of degrees within the FOV that are part of the ROI and for which dense resolution is required. If the mirror velocity is constant throughout the frame, then the angle α between the fiber tips can be approximated as θ / n, where n is the number of fiber tips. This α is referred to as the angle with constant velocity. csThe target angle for the fiber tips can be expressed, but additional calculations are required to take into account that the mirrors operate at different speeds, and therefore α cannot be set exactly to θ / n. Sparse regions must be taken into account. In sparse regions, the desired angle between adjacent resolution lines is assumed to be φ. For example, φ may exist between FT1 and FT2, between FT2 and FT3, between FT3 and FT4, and between FT4 and FT1 in the sparse region. To achieve φ between different fiber tips, the angle between the fiber tips can be calculated by the following equation:

[0088] α=α vs =φ*n*2–φ

[0089] where α vs is the angle of the variable speed mirror, φ is the angle between adjacent resolution lines in the sparse region, n is the number of fiber tips, and the number 2 is a scaling factor to account for overlapping resolution lines. The variables φ, n, mirror speed, and polygon speed are chosen so that α vs With α cs The variables are selected so that α vs With α cs Being identical or nearly identical enables the scanning system to achieve a desired scanning density for both ROI and non-ROI areas within the FOV of each frame.

[0090] Fig.17A Another illustrative diagram of vertical resolution using multiple fiber tips or multiple mirror alignment arrangements according to an embodiment is shown. Sparse areas and dense areas are shown. Four fiber tips FT1-4 are used. In the sparse areas, the resolution lines for each fiber tip are evenly spaced. In the dense areas, the vertical resolution lines are substantially denser than the vertical resolution lines in the sparse areas. In the dense areas, the vertical resolution lines are primarily grouped for each fiber tip, however, staggered resolution lines from other fiber tips may be present within a particular group.

[0091] Fig. 17B It shows the various embodiments Fig.17A illustrative close-up view of a sparse region within, and Fig. 17C It shows various embodiments Fig.17A An illustrative close-up view of a dense region within. Note that Fig. 17B The ratio of the scale factor Fig. 17C The scaling factor in is small. Therefore, Fig. 17B The resolution lines for multiple fiber tips are shown, and Fig. 17C Multiple resolution lines are shown for only one fiber tip.

[0092] The dynamic resolution discussed above is in the context of dynamic vertical resolution. If desired, the laser subsystem (e.g., fiber tip, multiple mirror alignment arrangement, or multiple collimator arrangement) can be oriented in the horizontal direction (opposite to the vertical direction described above) to provide dynamic horizontal resolution.

[0093] Assuming that changes in speed for mirror movement are used to control vertical resolution, the repetition rate or time interval can be changed to dynamically control horizontal resolution. This provides a dual-axis dynamic resolution control that can be synchronized by a controller (e.g., ROI controller 1340) to provide increased resolution for ROIs and reduced resolution for non-ROIs for both vertical and horizontal orientations. For example, when a scan cycle encounters an ROI, the mirror movement speed is reduced and the time interval between successive light pulses is reduced (thereby increasing the repetition rate). When a scan cycle encounters a non-ROI, the mirror movement speed is increased and the time interval between successive light pulses is increased (thereby reducing the repetition rate).

[0094] In some embodiments, the laser source(s) may be selectively turned on and off to provide a vertical dynamic range (assuming the laser subsystem is so oriented). This may eliminate the need to adjust the mirror speed to achieve dynamic vertical resolution. However, if desired, the laser source(s) may be selectively turned on and off in conjunction with changes in the mirror movement speed.

[0095] Fig.18 An illustrative FOV 1800 of laser pulses with variable sizes according to an embodiment is shown. As shown, FOV 1800 includes two sparse areas and one dense area. Both the sparse area and the dense area show illustrative light pulses in the form of circles of different sizes. The sparse size of the circle is larger than the dense size of the circle. When the scanning system projects light into the sparse area, the mirror speed can move at the sparse speed, and the repetition rate can be set to the sparse area repetition rate. On the contrary, when the scanning system projects light into the dense area, the mirror speed can move at the dense speed and the repetition rate can be set to the dense area repetition rate. The sparse speed is faster than the dense speed and the sparse area repetition rate is slower than the dense area repetition rate. Therefore, compared with in the sparse area, fewer light pulses are sent to the sparse area. If the circle size of the light pulse projected into the sparse area is the same as the circle size in the dense area, there may be insufficient filling (underfilling). When there is too much space between adjacent light pulse circles, insufficient filling may occur. Therefore, in order to minimize insufficient filling, it is desirable to project light pulses of appropriate size for both the sparse area and the dense area.

[0096] Control of the divergence of light pulses can be achieved using a curved mirror with an integrated flat portion. Such a curved mirror can be used as mirror 1360. Fig.19AAn exemplary mirror 1900 is shown arranged to include a curved mirror portion 1902, a flat portion 1904, and a curved mirror portion 1906. The flat portion 1904 is placed between the curved mirror portions 1902 and 1906. The curved mirror portions 1902 and 1906 generate a convergence of light pulses to produce a relatively large size circle (for a sparse area). The flat portion 1904 may not change the size of the light pulses interacting with it, and is used to project light into a dense area.

[0097] Fig.19B Another exemplary mirror 1950 is shown according to an embodiment. Mirror 1950 may include curved mirror portions 1952 and 1956 and a flat portion 1954. In some embodiments, flat portion 1954 may be a prism (e.g., similar to Fig.21 prism shown in the mirror).

[0098] Fig.19C Another exemplary mirror 1960 is shown according to an embodiment, which includes a concave continuously curved portion 1961 between two planar portions 1962 and 1963. The laser beam(s) are directed to portion 1961, and any returning pulses can be reflected by planar portions 1962 and 1963. Fig.19D Yet another exemplary mirror 1970 is shown that includes a concave, gradually curved portion 1971 between two planar portions 1972 and 1973 in accordance with an embodiment. The laser beam(s) are directed to portion 1971, and any returning pulses may be reflected by planar portions 1972 and 1973. Fig.19E Yet another exemplary mirror 1980 is shown comprising a convex continuously curved portion 1981 between two planar portions 1982 and 1983 in accordance with an embodiment. The laser beam(s) are directed to portion 1981 and any returning pulses may be reflected by planar portions 1982 and 1983. Fig.19F Another exemplary mirror 1990 is shown comprising a convex gradually curved portion 1961 between two planar portions 1962 and 1963 in accordance with an embodiment. The laser beam(s) are directed to portion 1991 and any returning pulses may be reflected by planar portions 1992 and 1993.

[0099] Figure 19GAnother exemplary mirror 1965 is shown according to an embodiment, which includes a concave portion 1966 between two planar portions 1967 and 1968. Concave portion 1966 has a flat portion positioned between two curved portions. The curved portion is convex relative to the incoming laser beam. The laser beam(s) are directed to portion 1966, and any return pulses can be reflected by planar portions 1967 and 1968. Fig.19H Yet another exemplary mirror 1975 is shown according to an embodiment, which includes a concave curved portion 1976 between two planar portions 1977 and 1978. The concave portion 1976 has a flat portion positioned between the two curved portions. The curved portion is concave relative to the incoming laser beam. The laser beam(s) are directed to portion 1976, and any return pulses can be reflected by the planar portions 1977 and 1978. Fig.19I Yet another exemplary mirror 1985 according to an embodiment is shown, which includes a convex portion 1986 between two planar portions 1987 and 1988. The convex portion 1986 has a flat portion positioned between two curved portions. The curved portion is convex relative to the incoming laser beam. The laser beam (s) is directed to portion 1986, and any return pulses can be reflected by the planar portions 1987 and 1988. Fig.19J Another exemplary mirror 1995 according to an embodiment is shown, which includes a convex portion 1996 between two planar portions 1997 and 1998. The convex portion 1996 has a flat portion positioned between two curved portions. The curved portion is concave relative to the incoming laser beam. The laser beam(s) are directed to portion 1996, and any return pulses can be reflected by the planar portions 1997 and 1998.

[0100] Except that mirror 704 includes prism 2020 and light sources 706 and 708 are moved out of the scanning area for detectors 708 and 712, Fig. 20 Depicted with Figure 8 Placing light sources 706 and 708 outside the return path for detectors 708 and 712 reduces or eliminates any interference that may occur. It should be understood that the size of prism 2020 is shown at an exaggerated size for illustrative purposes, and the size of the prism is preferably minimized to reduce its impact on the return path.

[0101] Except that mirror 704 is replaced with curved mirror 2104 (e.g., similar to curved mirror 1950), Fig.21 Depicted with Fig. 20The curved mirror 2104 may include a flat portion 2105, which may be a prism, and curved mirror portions 2106 and 2107. The curved mirror 2104 may be used to perform (as described above in conjunction with Fig.18 The lens 710 performs the dual task of generating laser pulses of different sizes and acting as a focusing lens 710. Fig.21 In the illustrated embodiment, the lens 710 may be omitted.

[0102] Discussed above Figures 9 to 11 Each shows a curve of data points acquired in their respective fields of view. This can be done by using a Fig. 22 The polygon with trapezoidal cross section shown in flattens the curve. Fig. 22 An exemplary polygon 2200 is shown rotated about an axis of rotation 2202. Note that because the light source illuminates the polygon 2200 before interacting with the mirror 2230, Fig. 22 The order in which light travels is Fig.13 It should be appreciated that the light source may illuminate mirror 2230 prior to interacting with polygon 2200. Fig. 22 Also shown are an exemplary mirror 2230 and an exemplary optical path 2246. Polygon 2200 can have a trapezoidal cross-section, wherein facet 2210 is not parallel to facet 2212, but top surface 2220 and bottom surface 2222 can be parallel to each other. Rotation axis 2202 is not consistent with gravity (gravity axis is shown as vertically downward). That is, if rotation axis 2202 is consistent with gravity, then it will be parallel to the gravity line. If desired, rotation axis 2202 can be consistent with gravity. Rotation axis 2202 can be angled relative to gravity so that light reflected from polygon 2200 can be directed in a useful direction (e.g., toward a road opposite to the sky).

[0103] Fig.23 Describes the use Fig. 22 The point diagram of polygon 2200 includes two channels (eg, two light source outputs and two light detectors). The scanned pattern has vertical overlap and no curves in the vertical direction.

[0104] Fig.24 An illustrative block diagram of a LiDAR system 2400 according to an embodiment is shown. The LiDAR system 2400 is similar to Fig.24System 1300 is similar to system 1300, but includes additional components to expand the field of view. System 1300 can provide a 120-degree horizontal field of view, while system 2400 can provide a 360-degree horizontal field of view. System 2400 can include a first subsystem 2410, a second subsystem 2420, a third subsystem 2430, a polygon 2440, a polygon controller 2444, and a ROI controller 2450. Each of the first, second, and third subsystems 2410, 2420, and 2430 can share polygon 2440 and be controlled by the same ROI controller 2450. If desired, each of the subsystems 2410, 2420, and 2430 can be independently controlled by their own corresponding ROI controller. The ROI controller can be similar to Fig.13 ROI controller 1340. Each of systems 2410, 2420, and 2430 may include a laser controller (e.g., similar to laser controller 1330), a laser subsystem (e.g., similar to laser subsystem 1310), a receiver system (not shown), a mirror (e.g., similar to mirror 1360), and a mirror controller (e.g., similar to mirror controller 1365). LiDAR system 2400 may be contained within one or more housings. Any of the embodiments discussed herein (e.g., Figures 1 to 23 ) can be used in system 2400.

[0105] exist Fig.24 In the illustrated embodiment, each of subsystems 2410, 2420, and 2430 can be responsible for observing a different portion of the 360-degree field of view (e.g., a specific 120-degree portion). The observed portions of each subsystem may or may not overlap. Each subsystem can be independently controlled to focus on the (one or more) ROIs in their respective FOVs. In other embodiments, four subsystems (as opposed to three subsystems) can be used, each of which can be responsible for observing a 90-degree portion of the 360-degree field of view. The observed portions of all four subsystems may or may not overlap. In other embodiments, five or more subsystems can be used.

[0106] As described above, the LiDAR system can control the vertical and horizontal angular resolution of the light beams projected by the scanning system. The angular resolution determines how many points can be observed from an object at a certain distance. To reiterate, the vertical angular resolution is defined by the vertical angle between adjacent beam projections. As the vertical angle decreases, the separation between adjacent beams decreases, resulting in more data points (or increased angular resolution). As the angle between adjacent beams increases, the separation between adjacent beams increases, resulting in fewer data points (or decreased angular resolution). It may be desirable to acquire more data points for relatively distant objects than for relatively close objects. For example, see Fig.25A ,Should Fig.25A A near object 2505 and a far object 2510 are shown along with illustrative data points captured from both objects. Fig.25A The vertical angular resolution in is constant across the entire vertical FOV. Near object data points 2507 correspond to data points obtained from near object 2505, and far object data points 2512 correspond to data points obtained from far object 2510. As shown, the data points collected for far object 2510 are relatively sparse compared to the data points collected for near object 2505.

[0107] Fig.25B An illustrative scenario is shown where the angular resolution is variable across the vertical FOV. In particular, for regions 2560 and 2562, the vertical angle increment is α, and for region 2570, the vertical angle increment is β, where β is less than α. Far object data point 2552 corresponds to far object 2550. Compared to FIG. 25 , when the angular resolution is increased so that the density of the beams and the corresponding number of collected data points increases, the number of data points collected from the far object is greater. It should be understood that although Fig.25A and Fig.25B Angular resolution is shown in the vertical FOV, but angular resolution may also occur in the horizontal FOV. The total number of data points that can be acquired is constrained by the design constraints of the LiDAR system. Therefore, it is desirable to optimize the angular resolution of a given LiDAR system for one or more ROIs.

[0108] A LiDAR system generally does not have a priori knowledge of the object(s) it is attempting to detect, but certain assumptions can be made, and based on these assumptions, the angular resolution can be customized for different parts of the FOV. For example, the angular resolution can be customized for (one or more) ROIs and / or assumption exceptions. In a vehicle context, the center FOV may have the highest likelihood of containing relevant objects in the distance. For example, in a vertical context, the focus is on the ground below the center FOV, while the focus is on the sky above the center FOV. Therefore, the center vertical FOV is more desirable for improved angular resolution. In a horizontal FOV context, left and right focusing is generally irrelevant at large distances. There may be exceptions to the improved angular resolution focusing primarily on the center FOV. Such exceptions may occur when the vehicle is turning, driving on a curved road, driving on a hill or downhill, or any other suitable situation where the center FOV is not the ideal ROI.

[0109] Fig.26A An exemplary optimized angular resolution in a vertical FOV relative to the ground is shown in accordance with an embodiment. Fig.26B An exemplary graph of angular vertical resolution as a function of vertical angle in the FOV is shown in accordance with an embodiment. Fig.26BAs shown in , the angular vertical resolution is variable between vertical angles of -25 degrees and -5 degrees, constant between vertical angles of -5 degrees and 3 degrees, and variable between vertical angles of 3 degrees and 19 degrees. Fig.26A As shown in , the variation of the angular resolution between -25 degrees and -5 degrees makes the ground distance between each adjacent light beam substantially constant. By continuously varying the angular resolution, a constant distance between adjacent light pulses is possible. As discussed above, the angular resolution can be controlled by varying the movement speed of the mirror (e.g., mirror 1360). Fig.26A and Fig.26B As shown, the incremental angle between adjacent light pulses increases in proportion to their relative angle away from the zero vertical angle. For example, at -25 degrees, the incremental angle within the central region (e.g., shown as -5 degrees to 3 degrees) is constant and represents the minimum angular difference between adjacent light pulses throughout the vertical FOV. The angular resolution for vertical angles above 3 degrees can be continuously varied in the same manner as the angular resolution for vertical angles below -5 degrees. It should be appreciated that Fig.26B The numbers used in are merely exemplary, and the ranges of constant angle values ​​and variable angle values ​​may vary from those shown and described.

[0110] Fig. 27 An illustrative graph of gradually changing angular vertical resolution with vertical angle in a FOV is shown according to an embodiment. For comparison purposes, a gradually changing vertical resolution line 2710 and a continuous vertical resolution line 2720 are shown. The gradually changing vertical resolution line 2710 shows that the vertical resolution remains fixed for a fixed vertical angle range in the FOV before changing to a different vertical resolution. The gradually changing vertical resolution line 2710 may be easier to implement than the continuous vertical resolution line 2720.

[0111] You can use the above combination Figures 1 to 24 The described embodiments or any other system capable of adjusting the angular resolution can be used to implement variable angular resolution and constant angular resolution. For example, the mirror speed can be variably adjusted to produce Fig.26B and Fig. 27 Angular resolution angle.

[0112] Fig.28An illustrative process 2800 for processing a ROI according to an embodiment is shown. Process 2800 can be implemented in a system such as system 1300 as described above. Starting from step 2810, at least one range of interest (ROI) region within a field of view (FOV) of a LiDAR scanning system can be received, wherein any portion within the FOV that is not within the at least one ROI region is a non-ROI region or a non-interested region. For example, a controller such as ROI controller 1340 can receive an indication of a ROI. As a specific example, dense areas and sparse areas within the FOV can be provided or programmed to the ROI controller to specify ROIs and non-ROIs. The LiDAR scanning system directs light pulses to the FOV in a controlled manner by scanning across each horizontal line according to the horizontal boundaries of the FOV of multiple lines including the vertical boundaries of the FOV.

[0113] When the LiDAR scanning system is aimed at the non-ROI area, the LiDAR scanning system may be operated at a first vertical scan rate and a first laser pulse interval (as indicated in step 2820). When the LiDAR scanning system is aimed at the ROI area, the scanning system may be operated at a second vertical scan rate and a second laser pulse interval (as indicated in step 2830). The second laser pulse interval may be slower than the first laser pulse interval.

[0114] It should be understood that Fig.28 The steps shown in are merely illustrative, and additional steps may be added or existing steps may be omitted.

[0115] Fig.29 An illustrative process 2900 for processing an ROI according to an embodiment is shown. Beginning at step 2910, a plurality of light beams may be emitted toward a scanning system that controls where the plurality of light beams are directed within a field of view (FOV). For example, two or more light beams may be directed to the FOV. Each of the plurality of light beams is aligned at a fixed angle relative to one another. At step 2920, when the scanning system is aimed at a region of interest (ROI) within the FOV, the plurality of light beams may produce a dense resolution. For example, a dense region within Fig.16 and Fig.17A At step 2930, when the scanning system is aimed at a region of non-interest (RONI) within the FOV, multiple beams can be generated (eg, Fig.16 and 17A ) sparse resolution shown in .

[0116] It should be understood that Fig.29 The steps shown in are merely illustrative, and additional steps may be added or existing steps may be omitted.

[0117] Fig.30An illustrative process 3000 for processing an ROI according to an embodiment is shown. Beginning at step 3010, a LiDAR system can be used to scan a field of view (FOV). The LiDAR system controls the aiming of at least one light beam as it scans the FOV, and the FOV can be bounded by a first range of directivities (e.g., vertical angles) and a second range of directivities (e.g., horizontal angles). At step 3020, a range of interest (ROI) occupying a first portion of the first range of directivities is defined within the FOV. At step 3030, an angular resolution of at least one light beam can be adjusted while the LiDAR system scans the FOV, wherein when at least one light beam is aimed at the ROI, the angular resolution is constant throughout the first portion of the first range of directivities, and wherein, when at least one light beam is aimed at a region of non-interest (RONI), the angular resolution varies across the first range of directivities including the RONI.

[0118] It should be understood that Fig.30 The steps shown in are merely illustrative, and additional steps may be added or existing steps may be omitted.

[0119] It is believed that the disclosure set forth herein includes a plurality of different inventions with independent utility. Although each of these inventions has been disclosed in its preferred form, because many variations are possible, its specific embodiments as disclosed and illustrated herein should not be considered as limiting. Each example is limited to the embodiments disclosed in the aforementioned disclosure, but any one example does not necessarily include all features or combinations that may ultimately be claimed for protection. Wherein the description states "one" or "first" element or its equivalent, such a description includes one or more such elements, neither requiring nor excluding two or more such elements. In addition, the order indicators such as the first, second or third for the elements to be identified are used to distinguish between elements, and do not indicate the required number or limit number of these elements, and do not indicate the specific position or order of these elements, unless otherwise specifically stated.

[0120] Moreover, relative to Figures 1 to 30Any of the processes described and any other aspects of the present invention may be implemented by software, but may also be implemented by hardware, firmware, or any combination of software, hardware, and firmware. They may also be embodied as machine or computer readable code recorded on a machine or computer readable medium. A computer readable medium may be any data storage device that can store data or instructions that can be subsequently read by a computer system. Examples of computer readable media may include, but are not limited to, read-only memory, random access memory, flash memory, CD-ROM, DVD, magnetic tape, and optical data storage devices. Computer readable media may also be distributed on network-coupled computer systems so that computer readable codes are stored and executed in a distributed manner. For example, a computer readable medium may be transmitted from one electronic subsystem or device to another electronic subsystem or device using any suitable communication protocol. A computer readable medium may embody computer readable code, instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery medium. A modulated data signal may be a signal that sets or changes one or more of its characteristics in a manner that encodes information in the signal.

[0121] It should be understood that any or each module or state machine discussed herein can be set as a software construct, a firmware construct, one or more hardware components, or a combination thereof. For example, any one or more of a state machine or module can be described in the general context of a computer executable instruction (such as a program module) that can be executed by one or more computers or other devices. Typically, a program module can include one or more routines, programs, objects, components, and / or data structures that can perform one or more specific tasks or can implement one or more specific abstract data types. It should also be understood that the number, configuration, function, and interconnection of modules or state machines are merely illustrative, and the number, configuration, function, and interconnection of existing modules can be modified or omitted, additional modules can be added, and the interconnection of certain modules can be changed.

[0122] Although many changes and modifications of the present invention will undoubtedly become clear to those of ordinary skill in the art after reading the foregoing description, it should be understood that the specific embodiments shown and described by way of example are by no means intended to be considered limiting. Therefore, reference to details of the preferred embodiments is not intended to limit the scope thereof.

Claims

1. A light detection and ranging Li DAR system for use with a vehicle, include: a light source operable to transmit light energy; A polygonal structure to control a lateral angle of a field of view of the Li DAR system, wherein the polygonal structure has a trapezoidal cross-section; a movable mirror positioned to redirect light energy passing between the light source and the polygonal structure, the movable mirror operable to control the vertical field of view of the Li DAR system, and The Region of Interest (ROI) controller is configured as: adjusting the movement speed of the movable mirror so that the LiDAR system has a different vertical angle scanning resolution within the region of interest than outside the region of interest; wherein outside the region of interest, the movable mirror is configured such that a plurality of adjacent horizontal scan lines are from different beams of the plurality of beams, and Wherein within the region of interest, the movable mirror is configured such that at least two adjacent horizontal scan lines are from the same beam of the plurality of beams.

2. The LiDAR system of claim 1, wherein the movable mirror is a multi-plane mirror.

3. The LiDAR system of claim 2, wherein the multiplane mirror is operable to oscillate back and forth about an axis.

4. The LiDAR system of claim 2, wherein the multi-plane mirror comprises a first planar member and a second planar member, wherein the first planar member and the second planar member are coupled together at a transition point.

5. The LiDAR system of claim 4, wherein the first planar member and the second planar member are arranged so that their respective faces are not parallel to each other.

6. The LiDAR system of claim 2, wherein the multiplane mirror produces a relatively higher resolution in a middle portion of the vertical field of view compared to a top and bottom portion of the vertical field of view.

7. The LiDAR system of claim 1, wherein the movable mirror is a single plane mirror.

8. The LiDAR system of claim 7, wherein the single plane mirror produces a relatively higher resolution at the top and bottom of the vertical field of view compared to the middle portion of the vertical field of view.

9. The LiDAR system according to claim 1, further comprising: include: a first collimator, collimating light energy from the light source; as well as Light detector; as well as The second collimator focuses the light onto the photodetector.

10. The LiDAR system of claim 1, wherein the light source is a fiber optic light source.

11. The LiDAR system of claim 1 , wherein the light source is a semiconductor-based emitter light source.

12. The LiDAR system of claim 1, wherein the polygonal structure is operable to rotate about a rotation axis at a constant speed in a first direction.

13. The LiDAR system of claim 12, wherein the rotation axis coincides with an axis of symmetry of the polygonal structure.

14. The LiDAR system of claim 12, wherein the polygonal structure includes faces that are parallel or non-parallel to the rotation axis.

15. The LiDAR system of claim 12, wherein the polygonal structure is masked.

16. The LiDAR system of claim 12, wherein the polygonal structure is trimmed.

17. The LiDAR system of claim 12, wherein the polygonal structure has a first face, a second face, a top face, and a bottom face, wherein the first face is not parallel to the second face, and wherein the top face is parallel to the bottom face.

18. The LiDAR system of claim 12, wherein the axis of rotation is not aligned with gravity.

19. The LiDAR system of claim 1, wherein the movable mirror is a mirror galvanometer.

20. The LiDAR system of claim 1, wherein the light source is operable to transmit light pulses.

21. The LiDAR system of claim 1, wherein the polygonal structure and the movable mirror are located at different vertical heights.

22. The Li DAR system of any one of claims 1-21, wherein the rotation axis of the polygonal structure and the oscillation axis of the movable mirror are perpendicular to each other.

23. A light detection and ranging Li DAR system, include: a light source operable to transmit light energy; A polygonal structure to control a lateral angle of a field of view of a Li DAR system, wherein the polygonal structure has a trapezoidal cross-section, wherein the polygonal structure has a first face and a second face, wherein the first face is not parallel to the second face; a multi-plane mirror positioned to redirect light energy passing between the light source and the polygonal structure, the multi-plane mirror operable to control a vertical field of view of the Li DAR system; as well as The Region of Interest (ROI) controller is configured as: Adjusting the moving speed of the multiplane mirror so that the LiDAR system has a different vertical angle scanning resolution within the region of interest than outside the region of interest; wherein outside the region of interest, the multi-plane mirror is configured such that a plurality of adjacent horizontal scan lines are from different beams of the plurality of beams, and Wherein within the region of interest, the multi-plane mirror is configured such that at least two adjacent horizontal scanning lines come from the same beam of the multiple beams.

24. The LiDAR system of claim 23, wherein the polygonal structure further has a top surface and a bottom surface, wherein the top surface is parallel to the bottom surface.

25. The LiDAR system of claim 23, wherein the multiplane mirror is operable to oscillate back and forth about an axis.

26. The LiDAR system of claim 23, wherein the multi-plane mirror comprises a first planar member and a second planar member, wherein the first planar member and the second planar member are coupled together.

27. The LiDAR system of claim 23, wherein the multi-plane mirror comprises a first planar member, a second planar member, and a third planar member, wherein the first planar member, the second planar member, and the third planar member are coupled together.

28. The LiDAR system of claim 23, wherein the light source is operable to transmit light pulses.

29. The Li DAR system of any one of claims 23-28, wherein the polygonal structure and the multi-plane mirror are located at different vertical heights.

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