Method and system for optimizing coherent LIDAR scanning

Abstract

The present invention relates to a method and system for optimizing scanning of coherent LIDAR. An apparatus includes a motor, a first scanner, and a second scanner. The first scanner is coupled to the motor, and the motor is configured to rotate the first scanner around a rotation axis at a first angular velocity to deflect a first light beam incident on the first scanner in a third plane into a first plane different from the third plane. The second scanner is coupled to the motor, and the motor is configured to rotate the second scanner around the rotation axis at a second angular velocity different from the first angular velocity to deflect a second light beam incident on the second scanner in a third plane into a second plane different from the third plane.

Description

[0001] This application is a divisional application of an application which entered the Chinese national phase on March 25, 2021, with PCT application number PCT / US2019 / 054146, international application date October 1, 2019, Chinese application number 201980063047.3, and invention name “Method and system for optimizing coherent LIDAR scanning”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 739,915, filed on October 2, 2018, the entire disclosure of which is incorporated herein by reference. Background Art

[0004] Optical distance detection using lasers for light detection and ranging, often denoted by the mnemonic LIDAR, and sometimes also called laser RADAR, is used for a variety of applications from altimetry to imaging to collision avoidance. LIDAR provides finer-scale distance resolution with smaller beam sizes than conventional microwave ranging systems such as radio wave detection and ranging (RADAR). Summary of the invention

[0005] At least one aspect relates to an apparatus. The apparatus includes a motor, a first scanner, and a second scanner. The first scanner is coupled to the motor, and the motor is configured to rotate the first scanner around a rotation axis at a first angular velocity to deflect a first light beam incident on the first scanner in a third plane into a first plane different from the third plane. The second scanner is coupled to the motor, and the motor is configured to rotate the second scanner around the rotation axis at a second angular velocity different from the first angular velocity to deflect a second light beam incident in the third plane into a second plane different from the third plane.

[0006] In some embodiments, the first scanner is a first polygon scanner and the second scanner is a second polygon scanner.

[0007] In some embodiments, the first scanner is configured to deflect the first light beam from a first angle in a first plane to a second angle in the first plane that is less than or equal to sixty degrees from the first angle in the first plane. The second scanner can be configured to deflect the second light beam from a first angle in a second plane to a second angle in the second plane that is less than or equal to sixty degrees from the first angle in the second plane.

[0008] In some embodiments, the first scanner is configured to rotate in a different direction than the second scanner.

[0009] In some embodiments, the first scanner is configured to scan a first region and the second scanner is configured to scan a second region. The first region may be below the second region relative to the third plane.

[0010] In some embodiments, the apparatus includes a third scanner configured to adjust the direction of the first light beam from the first scanner to the second scanner.

[0011] In some embodiments, the motor includes a drive shaft and planetary bearings, which are mounted to the first scanner through a recess of the first scanner for receiving the drive shaft and planetary bearings. The device may include a plurality of planetary transmission gears, a driver sun gear, and a ring gear. The plurality of planetary transmission gears and the driver sun gear are positioned within the ring gear. The second scanner is mounted to the first scanner through the plurality of planetary transmission gears and the driver sun gear. At least one parameter of at least one of the plurality of transmission gears, the driver sun gear, or the ring can be selected to configure the ratio of the magnitude of the rotational speed of the first scanner to the magnitude of the rotational speed of the second scanner to be greater than 1.

[0012] In some embodiments, the first scanner is configured to scan the first light beam during a first time period, and the second scanner is configured to scan the second light beam during a second time period after the first time period.

[0013] In some embodiments, the rotation speed of the first angular velocity is in a range of about 1000 revolutions per minute (rpm) to about 5000 rpm, and the rotation speed of the second angular velocity is in a range of about 200 rpm to about 1000 rpm.

[0014] In some embodiments, the motor includes a first motor configured to rotate the first scanner and a second motor configured to rotate the second scanner.

[0015] In some embodiments, the apparatus is mounted to an autonomous vehicle. The apparatus may include a waveguide configured to receive at least one return beam corresponding to at least one of the first beam or the second beam and provide a signal corresponding to the at least one return beam to a vehicle controller. The vehicle controller may be configured to control at least one of a direction or a speed of the vehicle in response to the signal corresponding to the at least one return beam.

[0016] In some embodiments, the apparatus includes a laser source, at least one waveguide, and at least one collimator. The at least one waveguide may be configured to receive a third light beam from the laser source and emit a light beam at the tip of the at least one waveguide. The at least one collimator may be configured to collimate the third light beam from each corresponding at least one waveguide into a third plane. In some embodiments, the at least one waveguide includes a first waveguide and a second waveguide. The at least one collimator may include a first collimator and a second collimator, the first collimator being configured to collimate the third light beam from the first waveguide to be incident on the first scanner, and the second collimator being configured to collimate the third light beam from the second waveguide to be incident on the second scanner.

[0017] In some embodiments, the apparatus includes one or more processors configured to control rotation of the first scanner and the second scanner using a motor to improve detection of the environment around the vehicle based on a tradeoff between integration time of distance and at least one of velocity accuracy, sampling rate, or a pattern of sampling different angles.

[0018] In some embodiments, the apparatus includes one or more processors configured to cause the first scanner to scan a first scanning area and cause the second scanner to scan a second scanning area overlapping the first scanning area.

[0019] At least one aspect relates to a system. The system includes a laser source, at least one waveguide, at least one collimator, a motor, a first scanner, and a second scanner. The at least one waveguide is configured to receive a third light beam from the laser source and emit the third light beam at the tip of the at least one waveguide. The at least one collimator is configured to collimate the third light beam from each corresponding at least one waveguide into a third plane. The first scanner is coupled to the motor, and the motor is configured to rotate the first scanner to deflect a first light beam corresponding to the third light beam into a first plane different from the third plane. The second scanner is coupled to the motor, and the motor is configured to rotate the second scanner to deflect a second light beam corresponding to the third light beam into a second plane different from the third plane.

[0020] Those skilled in the art will appreciate that the summary of the invention is illustrative only and is not intended to be limiting in any way. According to various embodiments, any feature described herein may be used with any other feature, and any subset of these features may be used in combination. Other aspects, inventive features, and advantages of the apparatus and / or process described herein are limited only by the claims and will become apparent in the detailed description set forth herein and in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals indicate similar elements, and in which:

[0022] Figure 1A is a schematic diagram for illustrating an example transmitted signal of a series of binary digits and a returned optical signal for distance measurement according to an embodiment;

[0023] Figure 1B is a schematic diagram for illustrating an example spectrum of a reference signal and an example spectrum of a Doppler shifted return signal according to an embodiment;

[0024] Figure 1C is a schematic diagram for illustrating an example cross-spectrum of a phase component of a Doppler shifted return signal according to an embodiment.

[0025] Figure 1D is a set of graphs illustrating example optical chirp distance measurements according to an embodiment;

[0026] Figure 1E is a graph using a symmetrical LO signal according to an embodiment, and shows the return signal in this frequency-time graph with a dashed line when there is no Doppler shift.

[0027] Figure 1F is similar to Figure 1E Graph of using a symmetrical LO signal, and showing in dashed line the return signal in this frequency time diagram when there is a non-zero Doppler shift;

[0028] Figure 2A is a block diagram illustrating example components of a high-resolution (high-resolution) LIDAR system according to an embodiment;

[0029] Figure 2B is a block diagram illustrating a sawtooth scan pattern for a high resolution Doppler system used in some embodiments;

[0030] Figure 2C is an image showing an example velocity point cloud generated by a high-resolution Doppler LIDAR system, according to an embodiment;

[0031] Figure 2D is a block diagram illustrating example components of a high-resolution (high-resolution) LIDAR system according to an embodiment;

[0032] Figure 2E is a block diagram illustrating a side view of example components of a high-resolution (high-resolution) LIDAR system according to an embodiment;

[0033] Figure 2F is used to illustrate the embodiment Figure 2EA block diagram of a top view of example components of a high-resolution (high-resolution) LIDAR system;

[0034] Figure 2G is a block diagram illustrating a side view of example components of a high-resolution (high-resolution) LIDAR system according to an embodiment;

[0035] Figure 2H is used to illustrate the embodiment Figure 2G A block diagram of a top view of example components of a high-resolution (high-resolution) LIDAR system;

[0036] Fig.2I is used to illustrate the embodiment Figure 2E a schematic diagram of an exploded view of the scanning optics of the system;

[0037] Figure 2J is used to illustrate the Figure 2E A schematic diagram of a side view of multiple light beams scanned in multiple scanning areas of a system;

[0038] Figure 2K It is used to show the intersection along the 2K-2K line. Figure 2J A schematic diagram of a cross-sectional view of multiple scanning areas;

[0039] Figure 3A is a block diagram illustrating an example system including at least one high-resolution LIDAR system mounted on a vehicle, according to an embodiment;

[0040] Figure 3B is a block diagram illustrating an example system including at least one high-resolution LIDAR system mounted on a vehicle, according to an embodiment;

[0041] Figure 4A is a diagram for illustrating the case where no scanning is performed according to an embodiment. Figure 2D An exemplary signal-to-noise ratio (SNR) of a transmitted signal in a system of FIG. 1 versus target distance is shown;

[0042] Figure 4B is a method for showing the indication drive in the far field according to an embodiment Figure 4A An example graph of the shape of the SNR curve and the curve of the 1 / r square loss;

[0043] Figure 4C is a diagram for illustrating the case where no scanning is performed according to an embodiment. Figure 2D An example graph of collimated beam diameter versus distance for a transmitted signal in a system of FIG.

[0044] Figure 4D is a diagram for illustrating the case where no scanning is performed according to an embodiment. Figure 2D An example graph of SNR associated with collection efficiency versus distance for a transmitted signal in a system of FIG. 1 ;

[0045] Figure 4E is a diagram for illustrating the Figure 2D Examples of beam walk-off for various target distances and scan speeds in the system;

[0046] Figure 4F is a diagram for illustrating the Figure 2D An example graph of coupling efficiency versus target distance for various scan rates in a system of FIG.

[0047] Figure 4G is a diagram for illustrating the Figure 2D An example graph of SNR versus target distance for various scan rates in a system of FIG. 1 ;

[0048] Figure 4H is a diagram for illustrating the Figure 2D An example graph of SNR versus target distance for various integration times in a system of FIG.

[0049] Fig. 4I is used to illustrate the Figure 2D An example graph of measurement rate versus target distance in a system of FIG. 1 ;

[0050] Figure 5 is a flow chart illustrating an example method for optimizing a scan pattern of a LIDAR system on an autonomous vehicle, according to an embodiment;

[0051] Figure 6 is a flow chart illustrating an example method of a LIDAR system operating on an autonomous vehicle, according to an embodiment;

[0052] Figure 7 is a block diagram illustrating a computer system upon which embodiments of the present invention may be implemented; and

[0053] Figure 8 A chip set is shown upon which embodiments of the invention may be implemented. DETAILED DESCRIPTION

[0054] A method, apparatus, system, and computer-readable medium for scanning LIDAR to support vehicle operations are described. Some embodiments are described below in the context of a single front-mounted high-resolution Doppler LIDAR system on a personal automobile; however, the embodiments are not limited to this context. In other embodiments, one or more systems of the same type or other high-resolution LIDARs with or without a Doppler component, with overlapping or non-overlapping fields of view, or one or more such systems mounted on a piloted or autonomous, small or larger, land, sea, or air vehicle are employed.

[0055] Sampling and processing to provide distance accuracy and target velocity accuracy involves integrating one or more laser signals of various durations in a time interval called an integration time. Covering the scene in a timely manner involves repeatedly taking measurements (involving one or more signals typically on the order of one to tens of microseconds) of sufficient accuracy, typically sufficient to sample various angles around the autonomous vehicle (typically on the order of thousands) to understand the environment around the vehicle before the vehicle enters the space in front of the vehicle too far (distances on the order of one to tens of meters, typically covered in a specific time on the order of one to a few seconds). The number of different angles that can be covered in a specific time (typically called a cycle or sampling time) depends on the sampling rate. In order to improve the detection of the environment around the vehicle, one or more scanner rotations can be controlled based on parameters including at least one of the integration time for distance, velocity accuracy, sampling rate, or a pattern for sampling different angles. In particular, one or more LIDAR beams can be used to trade off between integration time for distance and velocity accuracy, sampling rate, and a pattern for sampling different angles to effectively determine the environment near the autonomous vehicle as the autonomous vehicle moves through the environment. Optical detection of distance can be achieved using several different techniques, including direct ranging based on the round-trip travel time of an optical pulse to an object, chirp detection based on the frequency difference between the transmitted chirped optical signal and the return signal scattered from the object, and phase coded detection based on a sequence of single frequency phase changes that can be distinguished from natural signals.

[0056] A method may include generating a light beam emitted from a tip of a waveguide using a LIDAR system including a laser source and a waveguide. The method also includes shaping the light beam in a third plane incident on one of a first polygon scanner and a second polygon scanner of the LIDAR system using a collimator. The method also includes adjusting the direction of the light beam in a first plane different from the third plane from a first angle to a second angle in the first plane based on the rotation of the first polygon scanner around a rotation axis at a first angular velocity using the first polygon scanner. The method also includes receiving a plurality of first return light beams at the tip of the waveguide based on adjusting the light beam in the first plane to include a first scan area of ​​a target located at a first distance. The method also includes adjusting the direction of the light beam in a second plane different from the third plane from a first angle to a second angle in the second plane based on the rotation of the second polygon scanner around a rotation axis at a second angular velocity different from the first angular velocity using the second polygon scanner. The method also includes receiving a plurality of second return light beams at the tip of the waveguide based on adjusting the light beam in the second plane to include a second scan area of ​​a target located at a second distance different from the first distance.

[0057] A method may include receiving first data on a processor, the first data indicating a first signal-to-noise ratio (SNR) value of a signal reflected by a target and detected by a LIDAR system based on a value of a distance to the target, wherein the first SNR value is for a corresponding value of a scan rate of the LIDAR system. The first data also indicates a second signal-to-noise ratio (SNR) value of the signal based on a value of the distance to the target, wherein the second SNR value is for a corresponding value of an integration time of the LIDAR system. The first data also indicates a first angle and a second angle for defining an angular range of a scan pattern. The method also includes receiving second data on the processor, the second data indicating a first maximum design range of the target at each angle in the angular range of a first scan area and a second maximum design range of the target at each angle in an angle of a second scan area different from the first scan area. The method also includes determining, on the processor, for each angle in the angular range of the first scan area, a first maximum scan rate of the LIDAR system based on a maximum value of those scan rates, wherein the first SNR value based on the first maximum design range is greater than a minimum SNR threshold. The method also includes determining, on the processor, a second maximum scan rate of the LIDAR system based on a maximum of those scan rates for each angle in the angular range of the second scan area, wherein the first SNR value based on the second maximum design range is greater than the minimum SNR threshold. The method also includes determining, on the processor, a first minimum integration time of the LIDAR system based on a minimum of those integration times for each angle in the angular range of the first scan area, wherein the second SNR value based on the first maximum design range is greater than the minimum SNR threshold. The method also includes determining, on the processor, a second minimum integration time of the LIDAR system based on a minimum of those integration times for each angle in the angular range of the second scan area, wherein the second SNR value based on the second maximum design range is greater than the minimum SNR threshold. The method also includes defining, using the processor, a scan pattern for the first scan area of ​​the LIDAR system based on the first maximum scan rate and the first minimum integration time at each angle in the angular range of the first scan area. The method also includes defining, using the processor, a scan pattern for the second scan area of ​​the LIDAR system based on the second maximum scan rate and the second minimum integration time at each angle in the angular range of the first scan area. The method also includes operating the LIDAR system according to the scan patterns for the first scan area and the second scan area.

[0058] 1. Phase Encoding Detection Overview

[0059] Using an optical phase coded signal for measuring distance, the transmitted signal is in phase with the carrier (phase = 0) for a portion of the transmitted signal, and then changes one or more phase changes represented by the symbol Δφ (so phase = Δφ) in a short time interval, repeatedly switching back and forth between two or more phase values ​​on the transmitted signal. The shortest interval of constant phase is a parameter of the encoding, called the pulse duration τ, and is usually the duration of a few cycles of the lowest frequency in the band. The reciprocal 1 / τ is the baud rate, where each baud indicates a symbol. The number N of such constant phase pulses during the time of the transmitted signal is the number of symbols N, and represents the length of the encoding. In binary encoding, there are two phase values, and the phase of the shortest interval can be considered to be 0 for one value and 1 for the other value, so the symbol is one bit, and the baud rate is also called the bit rate. In polyphase encoding, there are multiple phase values. For example, 4 phase values ​​such as Δφ*{0, 1, 2, and 3}, where for Δφ=π / 2 (90 degrees), they are equal to {0, π / 2, π, and 3π / 2}, respectively; and therefore, the 4 phase values ​​can represent 0, 1, 2, 3, respectively. In this example, each symbol is two bits, and the bit rate is twice the baud rate.

[0060] Phase shift keying (PSK) refers to a digital modulation scheme that transmits data by changing (modulating) the phase of a reference signal (carrier). Modulation is applied by changing the sine and cosine inputs at precise times. At radio frequency (RF), PSK is widely used in wireless local area networks (LANs), RF identification (RFID), and Bluetooth communications. Alternatively, instead of operating relative to a constant reference wave, the transmission can be operated relative to itself. The phase changes of a single transmitted waveform can be considered as symbols. In this system, the demodulator determines the change in the phase of the received signal, rather than the phase (relative to the reference wave) itself. Since this scheme depends on the difference between consecutive phases, it is called differential phase shift keying (DPSK). DPSK is much simpler to implement in communication applications than ordinary PSK because the demodulator does not need to have a copy of the reference signal to determine the exact phase of the received signal (hence, it is a non-coherent scheme).

[0061] To achieve acceptable range accuracy and detection sensitivity, direct long-range LIDAR systems can use short-pulse lasers with low pulse repetition rates and very high pulse peak powers. High pulse powers can cause rapid degradation of optical components. Chirped and phase-coded LIDAR systems can use long optical pulses with relatively low peak optical powers. In this configuration, range accuracy can increase with the length and bandwidth of the chirp bandwidth or phase code rather than the pulse duration, and thus excellent range accuracy can still be achieved.

[0062] Useful optical bandwidths have been achieved using broadband radio frequency (RF) electrical signals to modulate an optical carrier. With respect to LIDAR, using the same modulated optical carrier as a reference signal combined with the return signal at the optical detector can produce a relatively low beat frequency in the RF band in the resulting electrical signal that is proportional to the frequency difference or phase difference between the reference optical signal and the return optical signal. This beat frequency detection of the frequency difference at the detector is called heterodyne detection, which can use readily available and inexpensive RF components.

[0063] A high resolution range Doppler LIDAR system may use an arrangement of optical components and coherent processing to detect the Doppler shift in the return signal to provide an improved range and relative signed velocity on the vector between the LIDAR system and each external object.

[0064] In some cases, these improvements provide distance in a pencil-shaped thin laser beam of appropriate frequency or phase content with or without target velocity. As such a beam is swept across a scene, information about the position and velocity of surrounding objects can be obtained. The information can be used in control systems for autonomous vehicles, such as self-driving cars or driver-assisted cars.

[0065] For optical ranging applications, coherent PSK can be used since the transmitter and receiver are in the same device. The carrier frequency is the optical frequency fc, and the RF fo is modulated onto the optical carrier. The number of symbols N and the duration τ are selected to achieve the desired distance accuracy and resolution. The pattern of symbols is selected to separate from the coded signal and other source areas of noise. Therefore, a strong correlation between the transmitted signal and the returned signal can be a strong indication of the reflected or backscattered signal. The transmitted signal consists of one or more blocks of symbols, where each block is long enough to provide a strong correlation with the reflected or backscattered echo even in the presence of noise. The transmitted signal can consist of M blocks of N symbols per block, where M and N are non-negative integers.

[0066] Figure 1A 1 is a schematic diagram 120 showing an exemplary transmit signal as a series of binary digits and a return optical signal for distance measurement according to an embodiment. Horizontal axis 122 represents time in arbitrary units after a start time at zero. Vertical axis 124a represents the amplitude of the optical transmit signal at frequency fc+fo in arbitrary units relative to zero. Vertical axis 124b represents the amplitude of the optical return signal at frequency fc+fo in arbitrary units relative to zero and is offset from axis 124a to separate the traces. Trace 125 represents the transmit signal of M*N binary symbols, with Figure 1AThe phase changes shown are to produce codes starting with 00011010 and followed by ellipses. Trace 126 represents an idealized (noise-free) return signal scattered from an object that is not moving (and therefore, the return is not Doppler shifted). The amplitude is reduced, but the code 00011010 is recognizable. Trace 127 represents an idealized (noise-free) return signal that is scattered from an object that is moving and is therefore Doppler shifted. The return is not at the proper optical frequency fc+fo and is not well detected in the expected frequency band, so the amplitude is reduced.

[0067] By the Doppler effect given by equation 1, the observed frequency f' of the return is different from the correct frequency f = fc + fo of the return.

[0068]

[0069] where c is the speed of light in the medium, v 0 is the observer's velocity, v s is the velocity of the source along the vector connecting the source to the receiver. Note that if the observer and source move in the same direction with the same velocity on the vector between them, then the two frequencies are the same. The difference between the two frequencies Δf = f'-f is the Doppler shift Δf D , which will cause problems for distance measurement, and by

[0070] Formula 2 gives.

[0071]

[0072] Note that the magnitude of the error increases with the signal frequency f. Also note that for a fixed LIDAR system (v 0 = 0), for an object moving at 10 meters per second (v s =10), and the frequency of visible light is about 500THz, then the error is 16MHz (MHz, 1MHz=10 6 In various embodiments described below, Doppler shift errors are detected and used to process data for range calculations.

[0073] In phase coded ranging, the arrival of a phase coded reflection can be detected in the return by cross-correlating the transmitted signal or other reference signal with the return signal, which can be achieved by cross-correlating the code of the RF signal with the electrical signal from the optical detector using heterodyne detection and thus mixing down back into the RF band. The cross-correlation for any one lag can be calculated by convolving the two traces (e.g., by multiplying the corresponding values ​​in the two traces and summing all the points in the traces), and then repeating for each time lag. The cross-correlation can be achieved by multiplication of the Fourier transform of each of the two traces, followed by an inverse Fourier transform. Forward and inverse fast Fourier transforms (FFTs) can be efficiently implemented in hardware and software.

[0074] Note that the cross-correlation calculations can be performed using either analog or digital electrical signals after the return amplitude and phase are detected at the optical detector. In order to shift the signal at the optical detector to the RF frequency range where it can be easily digitized, the optical return signal is optically mixed with a reference signal before impinging on the detector. A phase-encoded replica of the transmitted optical signal can be used as the reference signal, but it is also possible and usually preferred to use a continuous wave carrier frequency optical signal output by the laser as the reference signal and acquire both the amplitude and phase of the electrical signal output by the detector.

[0075] For an idealized (noise-free) return signal that is reflected from an object that is not moving (and therefore returns without Doppler shift), the peak occurs at time Δt after the start of the transmit signal. This indicates that the return signal includes a version of the transmitted phase code that began at time Δt. The range R of the reflecting (or backscattering) object is calculated from the two-way travel time delay based on the speed of light c in the medium, as given by Equation 3.

[0076] R = c*Δt / 2 (3)

[0077] For an idealized (noise-free) return signal scattered from a moving object (and thus returned Doppler-shifted), the return signal does not include phase encoding in the proper frequency bin, the correlation remains low for all time lags, and the peak is not easily detected, and is typically undetectable in the presence of noise. Therefore, Δt is not easily determined, and the range R is not easily generated.

[0078] The Doppler shift can be determined in the electronic processing of the return signal and can be used to correct the cross-correlation calculation. Thus, the peak can be found more easily and the distance can be determined more easily. Figure 1B1 is a schematic diagram 140 showing an example spectrum of a transmitted signal and an example spectrum of a Doppler shifted complex return signal according to an embodiment. Horizontal axis 142 represents the RF frequency offset from the optical carrier fc in arbitrary units. Vertical axis 144a represents the magnitude (also called spectral density) of a particular narrow frequency bin in arbitrary units relative to zero. Vertical axis 144b represents the spectral density in arbitrary units relative to zero and is offset from axis 144a to separate the traces. Trace 145 represents the transmitted signal; and, peaks occur at the appropriate RF f 0 Trace 146 represents an idealized (noise-free) complex return signal that is backscattered from an object moving toward the LIDAR system and is therefore Doppler shifted to a higher frequency (called a blue shift). 0 There is no peak at Δf D Blue shift to frequency shifted frequency f S In practice, the complex return representing both the in-phase and quadrature (I / Q) components of the return is used to determine the D The peak value at , therefore, the direction of the Doppler shift and the direction of motion of the target on the vector between the sensor and the object can be detected from a single return.

[0079] In some Doppler compensation embodiments, instead of Figure 1B Δf is obtained by taking the frequency spectra of both the transmitted signal and the returned signal and searching for a peak in each signal and then subtracting the frequency of the corresponding peak. D Instead, it is more efficient to obtain the cross-spectrum of the in-phase and quadrature components of the down-mixed return signal in the RF band. Figure 1C 1 is a diagram 150 showing an example cross-spectrum according to an embodiment. Horizontal axis 152 represents the frequency shift relative to a reference spectrum in arbitrary units; and vertical axis 154 represents the magnitude of the cross-spectrum in arbitrary units relative to zero. Trace 155 represents the cross-spectrum with an idealized (noise-free) return signal from an object ( Figure 1B The blue shift Δf D1 =Δf D ) and a second object moving away from the LIDAR system (redshift Δf D2 ) is generated. When one of the components is blue-shifted by Δf D1 When , the peak 156a appears; and when one of the components is redshifted by Δf D2 When Δf is 0, another peak 156b appears. The Doppler shift is thus determined. These shifts can be used to determine the signed closing velocity of objects near the LIDAR, for example for collision avoidance applications. However, if no I / Q processing is performed, the peaks may appear at + / -Δf D1 Both and + / -Δf D2At both locations, the sign of the Doppler shift and the direction of movement may be ambiguous.

[0080] The Doppler shift detected in the cross spectrum can be used to correct the cross correlation so that the peak 135 is apparent in the Doppler compensated Doppler shift return at lag Δt, and the range R can be determined. In some embodiments, simultaneous I / Q processing can be performed. In some embodiments, serial I / Q processing can be used to determine the sign of the Doppler return. In some embodiments, errors due to Doppler shift can be tolerated or ignored; and no Doppler correction is applied to the range measurement.

[0081] 2. Overview of Chirp Detection

[0082] Figure 1D is a set of graphs showing example optical chirp distance measurements according to an embodiment. The horizontal axis 102 is the same for all four graphs and is in milliseconds (ms, 1 ms = 10 -3 100 represents the power of a light beam used as a transmitted optical signal. Vertical axis 104 in graph 100 represents the power of the transmitted signal in arbitrary units. Trace 106 represents that the power is on for a finite pulse duration τ starting at time 0. Graph 110 represents the frequency of the transmitted signal. Vertical axis 114 represents the frequency of the transmission in arbitrary units. Trace 116 represents the frequency of the pulse from f to f over the duration τ of the pulse. 1 Increase to f 2 , and thus has a bandwidth B = f 2 -f 1 The rate of change of frequency is (f 2 -f 1 ) / τ.

[0083] The return signal is depicted in a graph 160 having a horizontal axis 102 representing time and a vertical axis 114 representing frequency, as in graph 110. The chirp of graph 110 (e.g., trace 116) is also plotted as a dashed line on graph 160. The first return signal is given by trace 166a, which may represent the transmitted reference signal with reduced intensity (not shown) and delayed by ΔT. When the return signal is received from an external object after covering a distance of 2R, where R is the distance to the target, the return signal starting at the delay time Δt may be given by 2R / c, where c is the speed of light in the medium (approximately 3x 10) related according to equation 3 above. 8 meters per second, m / s). During this time, the frequency has changed by an amount that depends on the distance, called f R , and is given by the rate of change of frequency multiplied by the delay time. This is given by Equation 4a.

[0084] fR =(f 2 -f 1 ) / τ*2R / c=2BR / cτ (4a)

[0085] In a time-domain mixing operation known as dechirping, f can be measured by the frequency difference between the transmitted signal 116 and the returned signal 166a. R The distance R is therefore given by Equation 4b.

[0086] R = f Rc τ / 2B (4b)

[0087] If the return signal arrives after the pulse is completely transmitted, that is, if 2R / c is greater than τ, then equations 4a and 4b are invalid. In this case, the reference signal can be delayed by a known or fixed amount to ensure that the return signal overlaps the reference signal. The fixed or known delay time of the reference signal can be multiplied by the speed of light, c, to give an additional distance that is added to the distance calculated by equation 4b. Although the absolute distance may be off due to the uncertainty of the speed of light in the medium, this is a close to constant error, and the relative distance based on the frequency difference is still very accurate.

[0088] In some cases, the point illuminated by the transmitted light beam (pencil beam cross section) encounters two or more different scatterers at different distances, such as in front of and behind a semi-transparent object, or nearer and farther parts of an object at different distances from the LIDAR, or two separated objects within the illuminated point. In this case, a second signal of reduced intensity and different delay will also be received, as shown by trace 166b on graph 160. This will have a different measurement value f R , which gives different distances by using Equation 4b. In some cases, multiple additional return signals are received.

[0089] The graph 170 depicts the difference frequency f between the first return signal 166a and the reference chirp 116. R .like Figure 1D As in all other aligned graphs in FIG. 1 , horizontal axis 102 represents time and vertical axis 164 represents frequency difference over a large spread ratio. Trace 176 depicts the constant frequency f measured in response to the transmitted chirp. R , which represents a specific distance as given by Equation 4b. The second return signal 166b, if present, will produce a different, larger f during the dechirp period. R value (not shown); and thus a larger distance is produced by using equation 4b.

[0090] Dechirping can be performed by directing both the reference optical signal and the return optical signal to the same optical detector. The electrical output of the detector can be controlled by a beat frequency that is equal to or otherwise dependent on the frequency difference of the two signals focused on the detector. The Fourier transform of this electrical output signal will produce a peak at the beat frequency. The beat frequency is in megahertz (MHz, 1 MHz = 10 6 Hertz = l0 6 cycles per second) in the radio frequency (RF) range, rather than in the terahertz (THz, 1THz = 10 12 The return signal can be mixed with a continuous wave (CW) tone as a local oscillator (as opposed to a chirp as a local oscillator). This results in a detection signal that is itself a chirp (or whatever waveform is transmitted). In this case, although the digitizer bandwidth requirements may generally be higher, the detection signal can undergo matched filtering in the digital domain. Otherwise, the positive aspects of coherent detection are retained.

[0091] In some embodiments, the LIDAR system is altered to produce both up-chirps and down-chirs simultaneously. This approach can eliminate variability introduced by object velocity differences, or changes in LIDAR position relative to an object that actually does change the distance, or transient scatterers in the beam, etc., or some combination. The approach can ensure that the Doppler shift and distance measured on the up-chirp and down-chirp are actually the same and can be most usefully combined. The Doppler scheme can ensure that pairs of asymmetrically shifted returns are captured in parallel in frequency space for high probability of correct compensation.

[0092] Figure 1E is a graph using a symmetrical LO signal according to an embodiment, and shows the return signal in this frequency time graph when there is no Doppler shift as a dashed line. The horizontal axis represents the return signal at 10 -5 The vertical axis represents the time relative to the carrier frequency f. c or the frequency of the optical transmission signal of the reference signal, in GHz (10 9 Hz). During the pulse duration, a beam is generated that includes two optical frequencies at any time. One frequency is from f 1 Increase to f 2 (e.g. 1 to 2 GHz above the optical carrier), while another frequency is simultaneously 4 Reduce to f 3 (e.g. 1 to 2 GHz below the optical carrier). Two frequency bands (e.g. from f 1 to f2 Band 1, and from f 3 to f 4 The frequency bands 2) do not overlap, so that both the transmitted and returned signals can be optically separated by a high-pass or low-pass filter or some combination, where the passband starts at the pass frequency f P For example, 1 <f 2 <f P <f 3 <f 4 As shown, a higher frequency may provide an up-chirp, and a lower frequency may provide a down-chirp. In some embodiments, a higher frequency produces a down-chirp, and a lower frequency produces an up-chirp.

[0093] In some embodiments, two different laser sources are used to generate two different optical frequencies in each beam at each time. In some embodiments, a single optical carrier is modulated by a single RF chirp to generate symmetrical sidebands that act as simultaneous up- and down-chirps. In some embodiments, a double-sideband Mach-Zehnder intensity modulator is used, which generally does not leave much energy in the carrier frequency; instead, almost all of the energy goes into the sidebands.

[0094] Due to the sideband symmetry, the bandwidth of the two optical chirps can be the same if sidebands of the same order are used. In some embodiments, other sidebands are used, for example, two second order sidebands are used, or a first order sideband and a non-overlapping second sideband is used, or some other combination.

[0095] When selecting transmit (TX) and local oscillator (LO) chirp waveforms, it may be advantageous to ensure that the system's frequency shift band makes maximum use of the available digitizer bandwidth. Typically, this can be achieved by shifting either the up-chirp or the down-chirp to have a range frequency beat frequency close to zero.

[0096] Figure 1F is similar to Figure 1E , using a symmetrical LO signal, and the return signal when there is a non-zero Doppler shift is shown in dashed lines in this frequency-time diagram. In the case of a chirped waveform, time-separated I / Q processing (also known as time domain multiplexing) can be used to overcome the hardware requirements of other methods. In that case, the AOM can be used to eliminate the range-Doppler ambiguity for the real-valued signal. In some embodiments, a scoring system can be used to pair up-chirp and down-chirp returns. In some embodiments, I / Q processing can be used to determine the sign of the Doppler chirp.

[0097] 3. Overview of Optical Inspection Hardware

[0098] Figure 2Ais a block diagram illustrating example components of a high resolution range LIDAR system 200 according to an embodiment. Optical signals are represented by arrows. Electronic wired or wireless connections are represented by segmented lines without arrows. A laser source 212 emits a light beam (e.g., a carrier) 201, which is phase or frequency modulated in a modulator 282a before or after a beam splitter 216 to produce a phase-encoded or chirped optical signal 203 having a duration D. The beam splitter 216 separates the modulated (or, as shown, unmodulated) optical signal for use in a reference path 220. A target beam 205, also referred to herein as a transmitted signal, can be produced having most of the energy of the beam 201. A modulated or unmodulated reference beam 207a can also be produced, which can have very little energy, but is sufficient to produce good mixing with return light 291 scattered from an object (not shown). As Figure 2A As shown, the reference beam 207a is separately modulated in the modulator 282b. The reference beam 207a passes through the reference path 220 and is directed to one or more detectors as the reference beam 207b. In some embodiments, the reference path 220 introduces a known delay that is sufficient to cause the reference beam 207b to arrive at the detector array 230 along with scattered light from objects outside the LIDAR within the range of distances of interest. In some embodiments, the reference beam 207b is referred to as a local oscillator (LO) signal, for example as if the reference beam 207b is locally generated from another oscillator. In various embodiments, ranging from less flexible to more flexible schemes, the reference can be made to arrive with the scattered or reflected field by: 1) placing a mirror in the scene to reflect a portion of the transmitted beam back to the detector array so that the path length is well matched; 2) using fiber optic delays to closely match the path length and using optical devices near the detector array to propagate the reference beam, such as Figure 2A , with or without path length adjustment to compensate for observed or expected phase or frequency differences for a particular distance; or, 3) using a frequency shifting device (acoustic-optic modulator) or a time delay of the local oscillator waveform modulation (e.g., in modulator 282b) to produce additional modulation to compensate for path length mismatch; or some combination. In some embodiments, the object is close enough and the transmission duration is long enough that the return overlaps the reference signal sufficiently without delay.

[0099] The transmit signal is then transmitted to illuminate the area of ​​interest, for example, through some scanning optical devices 218. The detector array can be a single paired or unpaired detector, or a 1-dimensional (1D) or 2-dimensional (2D) array of paired or unpaired detectors arranged in a plane approximately perpendicular to the return beam 291 from the object. The reference beam 207b and the return beam 291 can be combined in zero or more optical mixers 284 to produce an optical signal with characteristics to be appropriately detected. The acquisition system 240 can record the frequency, phase or amplitude of the interference pattern for each detector multiple times during the signal duration D, or some combination. The number of time samples processed per signal duration or integration time can affect the down-range extent. The number or integration time can be a practical consideration selected based on the number of symbols per signal, the signal repetition rate, and the available camera frame rate. The frame rate is the sampling bandwidth, commonly referred to as the "digitizer frequency". The only fundamental limitation on the distance range is the coherence length of the laser and the length of the chirp or unique phase code before it repeats (for clear ranging). The reason this feature is enabled is that any digital record of the returned heterodyne signal or bits can be compared or cross-correlated with any portion of the transmitted bits from the previous transmission history.

[0100] The acquired data is available to the processing system 250, for example, as described below with reference to Figure 7 The computer system described below, or Figure 8 The scanner control module 270 provides scanning signals to drive the scanning optical device 218. The scanner control module 270 may include instructions for executing the same Figure 5 Flowcharts related to method 500 and / or Figure 6 One or more steps of method 600 associated with the flowchart of the processing system 250. A signed Doppler compensation module (not shown) in the processing system 250 can determine the sign and magnitude of the Doppler shift and the correction range based thereon and any other corrections. The processing system 250 may also include a modulation signal module (not shown) to send one or more electrical signals for driving the modulators 282a, 282b and / or the polygon scanners 244a, 244b and / or the scanner 241. In some embodiments, the processing system also includes a vehicle control module 272 to control a vehicle on which the system 200, 200', 200" is installed.

[0101] Optical coupling for flooding or focusing on a target or focusing across a pupil plane is not depicted. As used herein, an optical coupler is any component, either alone or in some combination, used to affect the propagation of light within a spatial coordinate to direct light from one component to another, such as vacuum, air, glass, crystal, mirror, lens, optical circulator, beam splitter, phase plate, polarizer, optical fiber, optical mixer, etc.

[0102] Figure 2A Also shown are example components for a simultaneous up-chirp and down-chirp LIDAR system according to one embodiment. Figure 2A As shown, the modulator 282a can be a frequency shifter added to the optical path of the transmitted light beam 205. In some embodiments, the frequency shifter is added to the optical path of the return light beam 291 or the reference path 220. Since the device used as a modulator (such as an acousto-optic modulator AOM) has some associated losses, and it is disadvantageous to place lossy components on the receiving side or after the optical amplifier, a frequency shifter can be added as a modulator 282b on the local oscillator (LO, also called the reference path) side or on the transmitting side (before the optical amplifier). The optical frequency shifter can shift the frequency of the transmitted signal (or the return signal) by a known amount Δfs relative to the frequency of the reference signal, so that the beat frequencies of the up-chirp and the down-chirp occur in different frequency bands, which can be picked up in the analysis of the electrical signal output by the optical detector 230, for example by the FFT component in the processing system 250. For example, if the distance effect causing the blue shift is f B , then the beat frequency of the up-chirp will increase by an offset and occur at f B +Δfs, and the beat frequency of the down-chirp will be reduced by the offset to f B -Δfs. Therefore, the up-chirp will be in a higher frequency band than the down-chirp, thereby separating them. If Δfs is greater than any expected Doppler effect, there will be no ambiguity within the distance associated with the up-chirp and down-chirp. Then, the measured beat frequency can be corrected with the correct symbol value of the known Δfs to obtain the appropriate up-chirp and down-chirp ranges. In some embodiments, the RF signal coming out of the balanced detector is directly digitized, where the frequency bands are separated via FFT. In some embodiments, the RF signal coming out of the balanced detector is pre-processed with an analog RF electronic device to separate a low frequency band (corresponding to one of the up-chirp or down-chirp) and a high frequency band (corresponding to the opposite chirp), the low frequency band can be directly digitized, and the high frequency band can be electronically down-mixed to the baseband and then digitized. Various such embodiments provide a path for matching the frequency band of the detected signal with the available digitizer resources. In some embodiments, modulator 282A is excluded (e.g., direct ranging).

[0103] Figure 2Bis a block diagram showing a sawtooth scan pattern for a high resolution Doppler system. The scan sweeps over a range of azimuth (horizontally) and tilt angles (vertically above and below horizontal at zero tilt). Various scan patterns can be used, including adaptive scanning. Figure 2C is an image showing an example velocity point cloud produced by a high-resolution Doppler LIDAR system.

[0104] Figure 2D is a block diagram showing example components of a high-resolution (high-resolution) LIDAR system 200'. System 200' may be similar to system 200, except for the features discussed herein. System 200' may be a coherent LIDAR system built with a monostatic transceiver. System 200' may include a source 212 that transmits a carrier 201 on a transmission path 222 along a single-mode optical waveguide 225, passes through a circulator 226 and exits a tip 217 of the single-mode optical waveguide 225 located in the focal plane of a collimating optic 229. The tip 217 may be positioned within a threshold distance (e.g., approximately 100 μm) of the focal plane of the collimating optic 229 or within a range of approximately 0.1% to approximately 0.5% of the focal length of the collimating optic 229. The collimating optic 229 may include one or more of a doublet, an aspheric, or a multi-element design. Carrier 201 exiting optical waveguide tip 217 may be shaped by optics 229 into a collimated target beam 205 ′, which is scanned by scanning optics 218 over a range of angles 227 .

[0105] In some embodiments, the carrier 201 is phase or frequency modulated in a modulator 282a upstream of the collimating optical device 229. In some embodiments, the modulator 282 is not included. The return beam 291 from the object can be guided by the scanning optical device 218 and focused on the tip 217 by the collimating optical device 229 so that the return beam 291 is received by the single-mode optical waveguide tip 217. The circulator 226 can then redirect the return beam 291 into the single-mode optical waveguide along the receiving path 224 and return to the optical mixer 284, where the return beam 291 is combined with the reference beam 207b, which is guided through the single-mode optical waveguide along the local oscillator path 220. The system 200' can operate under the following principle: the maximum spatial mode overlap of the return beam 291 with the reference signal 207b will maximize the heterodyne mixing (optical interference) efficiency between the return signal 291 and the reference beam 207b. This arrangement is advantageous because it can help avoid the challenging alignment process associated with a bistatic LIDAR system.

[0106] Figure 2E is a block diagram illustrating a side view of example components of a high-resolution (high-resolution) LIDAR system 200 ″. Figure 2F It is used to show Figure 2E 2 is a block diagram of a top view of example components of a high-resolution (high-resolution) LIDAR system 200" of FIG. 2. System 200" may be similar to system 200' except for the features discussed herein. Scanning optics 218 of system 200" include a first polygon scanner 244a coupled to at least one motor (e.g., Figure 2J The scanning optical device 218 may include a second polygon scanner 244b, which is coupled to at least one motor and is configured to rotate around the rotation axis 243 at a second angular velocity 249b. Although two polygon scanners 244a, 244b are depicted, more than two polygon scanners may be featured in the scanning optical device 218. The at least one motor may include a first motor for rotating the first polygon scanner 244a and a second motor for rotating the second polygon scanner 244b. The first angular velocity 249a at which the first polygon scanner 244a rotates may be a first fixed rotational velocity. The second angular velocity 249b at which the second polygon scanner 244b rotates may be a second fixed rotational velocity. The second fixed rotational velocity may be different from (e.g., less than) the first fixed rotational velocity. The first fixed rotation speed of the first angular velocity 249a may be in a range from about 1000 revolutions per minute (rpm) to about 5000 rpm, and the second fixed rotation speed of the second angular velocity 249b may be in a range from about 200 rpm to about 1000 rpm. The first polygon scanner 244a and the second polygon scanner 244b may rotate in different directions, such as opposite directions (e.g., clockwise and counterclockwise); for example, the first angular velocity 249a and the second angular velocity 249b may have different directions (e.g., clockwise and counterclockwise). The scanners 244a, 244b may not be limited to Figure 2E-2F The polygon scanner shown in , and may include any type of polygon scanner (e.g., prismatic, pyramidal, stepped geometries, etc.).

[0107] In an exemplary embodiment, each polygon scanner 244a, 244b has one or more of the following characteristics: Sensors, having a Copal rotating mirror having an inscribed diameter of about 2 inches or in the range of about 1 inch to about 3 inches, each mirror about 0.5 inches high or in the range of about 0.25 inches to about 0.75 inches, having an overall height of about 2.5 inches or in the range of about 2 inches to about 3 inches, powered by a three-phase brushless DC (BLDC) motor with encoder pole pair switching, having a rotation speed in the range of about 1000 revolutions per minute (rpm) to about 5000 rpm, having a ratio of about 5:1, and a distance from the collimator 229 of about 1.5 inches or in the range of about 1 inch to about 2 inches. In some embodiments, the scanning optical device 218 of the system 200" uses an optical device other than the polygon scanner 244a, 244b.

[0108] In some embodiments, one or more parameters of the polygon scanners 244a, 244b are different from each other. The mass of the second polygon scanner 244b can be greater than the mass of the first polygon scanner 244a. The outer diameters of the polygon scanners 244a, 244b can be approximately equal, but the first polygon scanner 244a can have a larger aperture (e.g., a larger inner diameter) through which the rotation axis 243 is received, so that the mass of the first polygon scanner 244a is less than that of the second polygon scanner 244b. The ratio of the mass of the second polygon scanner 244b to the mass of the first polygon scanner 244a can be approximately equal to the ratio of the rotation speed of the first angular velocity 249A to the rotation speed of the second angular velocity 249b. This advantageously ensures that there is no net angular momentum between the polygon scanners 244a, 244b due to inertia changes during rotation, which can promote the stability of the system 200" during operation. The angular momentum and moment of inertia of each polygon scanner 244a, 244b are provided by the following formula:

[0109]

[0110] I=mr 2 (5b)

[0111] Wherein L is the angular momentum of each polygon scanner 244a, 244b; I is the moment of inertia of each polygon scanner 244a, 244b; ω is the angular velocity 249a, 249b; m is the mass of each polygon scanner 244a, 244b, and r is the radial distance of the mass m from the rotation axis 243. In one embodiment, the first rotational speed of the first angular velocity 249a is greater than the second rotational speed of the second angular velocity 249b, and the ratio of the first rotational speed to the second rotational speed is in the range from about 3 to about 10, in which embodiment, based on the same ratio of the first rotational speed to the second rotational speed, the mass of the second polygon scanner 244b is greater than the mass of the first polygon scanner 244a. Therefore, although the moment of inertia I of the second polygon scanner 244b is greater than the moment of inertia of the first polygon scanner 244a according to Equation 5b, the magnitude of the angular velocity (e.g., rotational speed) of the first polygon scanner 244a is greater than that of the second polygon scanner 244b by an equal amount, and therefore, according to Equation 5a, the angular momentum L of the polygon scanners 244a, 244b is approximately equal in magnitude, and because the angular velocities 249a, 249b are opposite in direction, the angular momentum L is opposite in sign. This advantageously ensures that there is no net angular momentum or the net angular momentum is negligible between the polygon scanners 244a, 244b during operation of the system 200".

[0112] The system 200" may include a scanner 241 (e.g., polygon scanners 244a, 244b) positioned between the collimator 229 and the scanning optics 218, which is configured to scan the third plane 234 (e.g., Figure 2E The scanner 241 can adjust the direction of the collimated beam 205' between the first polygon scanner 244a and the second polygon scanner 244b. The scanner 241 can adjust the beam 205' to a scanning beam 233 between the faces 245a, 245b of the first polygon scanner 244a and the faces 245a, 245b of the second polygon scanner 244b. The scanner 241 can continuously move the scanning beam 233 between the faces 245 of the first polygon scanner 244a and the faces 245 of the second polygon scanner 244b using a triangular waveform (e.g., five times per second).

[0113] When the scanner 241 directs the scanning beam 233 onto the faces 245a, 245b of the first polygonal scanner 244a, the faces 245a, 245b may deflect the beam 233' to a plane different from the third plane 234 (eg, Figure 2E A first plane 235 (e.g. Figure 2F plane), and in a third plane, the light beam 233 is incident on the first polygon scanner 244a. Figure 2JA first plane 235 is depicted that is used to define a lower scanning area 264 in which the light beam 233' is scanned from a first angle to a second angle. In one embodiment, the first plane 235 forms an angle of approximately 85 degrees or 105 degrees with the rotation axis 243, or forms an angle in a range from approximately 45 degrees to approximately 150 degrees, or in a range from approximately 30 degrees to approximately 150 degrees. In one embodiment, the second plane 237 forms an angle of approximately 90 degrees with the rotation axis 243, or in a range from approximately 60 degrees to approximately 120 degrees, or in a range from approximately 40 degrees to approximately 150 degrees. In one embodiment, based on the rotation of the first polygon scanner 244a about the rotation axis 243, the scanning light beam 233' is scanned by the faces 245a, 245b of the first polygon scanner 244a in the first plane 235 (e.g., Figure 2F The first plane 235 (e.g. Figure 2F The first polygon scanner 244a may be a plane of the first polygon scanner 244a) that is substantially orthogonal to the third plane 234. For the purposes of this specification, orthogonal means a relative orientation defined by an angle within a range of 90±20 degrees. The scanner 241 may adjust the direction of the scanning beam 233 slowly enough at a fixed scanning speed so that during the time period when the scanning beam 233 is directed onto the first polygon scanner 244a, the scanning beam 233' is deflected from the first angle to the second angle within the first plane 235 by a threshold number (e.g., once). The scanner 241 may adjust the direction of the scanning beam 233 to the faces 245a, 245b of the first polygon scanner 244a at a scanning speed and maintain the position of the scanning beam 233 for a minimum time period so that the scanning beam 233' is deflected from the first angle to the second angle within the first plane 235 by a threshold number (e.g., once).

[0114] In one embodiment, when the scanner 241 directs the scanned beam 233 from the first polygon scanner 244a onto the faces 245a, 245b of the second polygon scanner 244b, the faces 245a, 245b deflect the beam 233' to a plane aligned with the third plane 234 (eg, Figure 2E In a second plane 237 different from the plane of the first plane 235, wherein the light beam 233 is incident on the second polygon scanner 244b and is different from the first plane 235. Figure 2J A second plane 237 is depicted, which defines a scan area 261 (see Figure 2K) of the upper scanning area 262, in which the light beam 233' is scanned from a first angle to a second angle. In some embodiments, the upper scanning area 262 and the lower scanning area 264 of the scanning area 261 have an overlapping area 263. In some embodiments, the upper scanning area 262 and the lower scanning area 264 do not overlap, so there is no overlapping area 263. In one embodiment, the second plane 237 forms an angle of approximately 90 degrees with the rotation axis 243. In one embodiment, based on the rotation of the second polygon scanner 244b around the rotation axis 243, the scanning light beam 233' is scanned by the surfaces 245a, 245b of the second polygon scanner 244b in the second plane 237 (for example Figure 2F The direction of the second angular velocity 249b may be opposite to the direction of the first angular velocity 249a, so that the light beam 233' is reversely scanned in the second plane 237 in the opposite direction (e.g., from the second angle to the first angle) compared to the light beam 233' being scanned in the first plane 235 (e.g., from the first angle to the second angle). The second plane 237 (e.g., Figure 2F The first plane 237 may be substantially orthogonal to the third plane 234. The scanner 241 may adjust the direction of the scanning beam 233 at a fixed scanning speed sufficiently slowly so that the scanning beam 233' is deflected from the first angle to the second angle by a threshold number (e.g., once) in the second plane 237 during a time period when the scanning beam 233 is directed onto the second polygon scanner 244b. The scanner 241 may adjust the direction of the scanning beam 233 to the faces 245a, 245b of the second polygon scanner 244b at the scanning speed and maintain the position of the scanning beam 233 for a minimum time period so that the scanning beam 233' is deflected from the first angle to the second angle by a threshold number (e.g., once) in the second plane 237.

[0115] Fig.2I It is used to show Figure 2ESchematic diagram of an exploded view of an example of a scanning optical device 218 of the system 200. In one embodiment, the scanning optical device 218 includes a first polygon scanner 244a and a second polygon scanner 244b. The first polygon scanner 244a can be coupled to the motor 257, and the second polygon scanner 244b can be coupled to the motor 257 through the first polygon scanner 244a. The first polygon scanner 244a can be rotatably mounted to the drive shaft 258 and the planetary bearings 259 of the motor 257. The first polygon scanner 244a may include a recess (not shown) to receive the drive shaft 258 and the planetary bearings 259. The second polygon scanner 244b can utilize a first polygon scanner 244a positioned within the ring gear 252. The planetary drive gear 254 and the driver sun gear 256 are rotatably mounted to the first polygon scanner 244a. The ring gear 252 can be received in a cavity (not shown) on the lower surface of the second polygon scanner 244b. One or more parameters (e.g., diameter, number, etc.) of the gears 254, 256 and / or the ring gear 252 can be selected to adjust the ratio of the magnitude of the rotational speed of the first angular velocity 249a of the first polygon scanner 244a to the magnitude of the rotational speed of the second angular velocity 249b of the second polygon scanner 244b. For example, the ratio can be in the range of from about 3 to about 10, or in the range of from about 2 to about 20. The motor 257 can be manufactured by Nidec Corporation of Torrance, California. Electronics Company. The transmission (such as gears 254, 256 and ring gear 252) can be made of Gears are provided including a S1E05ZM05S072 internal ring gear coupled with a selection from the ground metric spur gear provision.

[0116] although Fig.2I The motor 257 in the embodiment moves both polygon scanners 244a and 244b simultaneously (e.g., in opposite directions), such as Figure 2E-2F As shown, the light beam 233 can be guided by the scanner 241 to only one polygon scanner 244a, 244b at a time, so that the light beam 233' scans the lower scanning area 264 through the first plane 235 in a first time period, and then scans the upper scanning area 262 through the second plane 237 in a second time period after the first time period.

[0117] Figure 2G is a block diagram illustrating a side view of example components of a high-resolution (high-resolution) LIDAR system 200 ″ according to an embodiment. Figure 2H is a diagram showing a method according to an embodiment of the present invention. Figure 2G A block diagram of a top view of example components of a high-resolution (high-resolution) LIDAR system 200 is provided. Figure 2G-2H The system 200" may be similar to reference Figure 2E-2F described herein, except for the features discussed here. Figure 2E-2F Unlike the embodiment of the present invention, a single waveguide 225 and a single collimator 229 provide a single collimated beam 205' scanned by a scanner 241 between a first polygon scanner 244a and a second polygon scanner 244b, Figure 2G-2H The system 200" includes a pair of waveguides 225a, 225b and a pair of collimators 229a, 229b that provide a collimated beam 205' to first and second polygon scanners 244a, 244b, respectively. In one embodiment, Figure 2G-2H The system 200" does not include the scanner 241. The light beam 201 from the laser source 212 can be separated by a beam splitter (not shown) into two light beams 201 directed into waveguides 225a, 225b. The system 200" may include two circulators 226 and two receiving waveguides in the receiving path 224 to accommodate separated return light beams 291 from the corresponding polygon scanners 244a, 244b received at the tips of the corresponding waveguides 225a, 225b. Figure 2G-2H The system 200" may include two laser sources 212, and each waveguide 225a, 225b may receive a corresponding light beam 201 from one of the laser sources 212. The system 200" may also include two circulators 226 and two receiving waveguides to process separate return light beams 291 from the polygon scanners 244a, 244b. Figure 2G-2H The system 200" can accommodate simultaneous scanning of the light beam 233' in the first and second planes 235, 237, and therefore accommodate simultaneous scanning in the upper scanning area and the lower scanning area 262, 264 (for example, in opposite directions), because the system 200" includes two processing channels to accommodate simultaneous return beams 291 from the polygon scanners 244a, 244b.

[0118] 4. Single-base coherent LIDAR system parameters

[0119] In one embodiment, the monostatic coherent LIDAR performance of the system 200', 200" is modeled by including the system parameters in a so-called "link budget". The link budget estimates the expected value of the signal-to-noise ratio (SNR) for various system and target parameters. On the system side, the link budget may include one or more of output optical power, integration time, detector characteristics, insertion losses in the waveguide connection, mode overlap between the imaged light spot and the monostatic collection waveguide, and optical transceiver characteristics. On the target side, the link budget may include one or more of atmospheric characteristics, target reflectivity, and target distance.

[0120] Figure 4A is a diagram showing a method according to an embodiment of the present invention. Figure 2DSystem 200' or Figure 2E-2H An example signal-to-noise ratio (SNR) plot of the return beam 291 in the system 200" without scanning versus target distance. In other embodiments, Figure 4A Describes Figure 2A 20. An example of SNR of a return beam 291 versus target distance in a system 200 of FIG. 40. The horizontal axis 402 is the target distance in meters (m). The vertical axis 404 is the SNR in decibels (dB). Curve 410 depicts the SNR versus distance values ​​separated into a near field 406 and a far field 408, wherein there is a transition from the near field 406 having a relatively flat slope of the curve 410 to the far field 408 having a negative slope of the curve 410 (e.g., approximately -20 dB / 10 m). The reduction in SNR in the far field 408 is dominated by "r-squared" losses because the scattering atmosphere through which the return beam 291 passes grows with the square of the distance to the target, while the surface area of ​​the optical waveguide tip 217 used to collect the return beam 291 is fixed. Figure 4B is a graph showing an example of a curve 411 representing 1 / r squared losses driving the shape of SNR curve 410 in far field 408, according to an embodiment. Horizontal axis 402 is range in meters (m), and vertical axis 407 is unitless power loss.

[0121] In the near field 406 , the primary driver of the SNR is the diameter of the collimated return beam 291 before being focused onto the tip 217 by the collimating optics 229 . Figure 4C is a diagram showing the case where no scanning is performed according to an embodiment. Figure 2D System 200' or Figure 2E-2H 200" versus range. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 405 is the diameter of the return beam 291 in meters (m). In one embodiment, curve 414 depicts the diameter of the collimated return beam 291 incident on the collimating optical device 229 before the return beam 291 is focused onto the tip 217 of the optical waveguide. Curve 414 shows that the diameter of the collimated return beam 291 incident on the collimating optical device 229 increases as the target distance increases.

[0122] In one embodiment, in the near field 406, as the diameter of the collimated return beam 291 increases at greater target distances, the diameter of the return beam 291 focused by the collimating optics 229 at the tip 217 decreases. Figure 4D is a diagram according to an embodiment showing that in the absence of scanning Figure 2D or Figure 2E-2HFIG. 4 is a graph of an example of an SNR associated with the collection efficiency of the return beam 291 at the tip 217 relative to the distance of the transmitted signal in a system of FIG. 406. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 404 is the SNR in decibels (dB). Curve 416 depicts the near-field SNR of the return beam 291 focused by the collimating optics 229 at the tip 217 based on the target distance. At close distances within the near-field 406, the image 418a of the return beam 291 focused by the collimating optics 229 at the tip 217 is substantially larger than the core size of the single-mode optical fiber tip 217. Therefore, the SNR associated with the collection efficiency is relatively low. At longer distances within the near-field 406, the image 418b of the return beam 291 focused by the collimating optics 229 at the tip 217 is much smaller than the image 418a, and thus the SNR attributable to the collection efficiency increases at longer distances. In one embodiment, curve 416 shows that the SNR in the near field 406 has a positive slope (e.g., +20 dB per 10 meters) based on the improved collection efficiency of the focused return beam 291 at longer distances. In one embodiment, this positive slope in the near field SNR offsets Figure 4B The negative slope in the near-field SNR discussed in , which is attributable to the “r-squared” losses, and thus results in a relatively flat region of the SNR curve 410 in the near-field 406. Figure 4D The positive slope in the SNR curve 416 in does not extend into the far field 408, and therefore Figure 4B The “r-squared” loss dominates the far-field 408 SNR, as shown in the SNR curve 410 in the far-field 408 .

[0123] Although about Figures 4A-4D The discussion predicts the SNR of the return beam 291 according to the target distance, but Figures 4A-4D The predicted SNR in does not fully characterize the performance of the scanning monostatic coherent LIDAR system 200', 200" because it does not take into account the scanning rate of the scanning optics 218. In one embodiment, due to the round-trip delay of the return beam 291, the received pattern of the return beam 291 will be laterally offset or "walk away" from the transmitted pattern of the transmit beam 205' as the beam is being scanned by the scanning optics 218. Figure 4E According to the embodiment, Figure 2D System 200' or Figure 2E-2H 2. An example of beam walk-off for various target distances and scan speeds (e.g., a fixed scan speed of polygon scanners 244a, 244b) in system 200. The horizontal axis 402 is the target distance, and the vertical axis 422 is the scan speed of the beam using the scanning optics 218. Figure 4EAs shown, when the beam is not scanned (bottom row), there is no beam walk-off because the image 418a of the focused return beam 291 is centered on the fiber tip 217, indicating no beam walk-off at short target distances, and the image 418b of the focused return beam 291 is also centered on the fiber tip 217, indicating no beam walk-off at long target distances. When the beam is scanned at a moderate scan speed ( Figure 4E ), a moderate beam walk-off 419a is observed between the image 418a of the focused return beam 291 and the fiber tip 217, and a larger beam walk-off 419b is observed between the image 418b of the focused return beam 291 and the fiber tip 217. When the beam is scanned at a high scan speed ( Figure 4E ), a beam walk-off 421a is observed at short distances that exceeds the beam walk-off 419a at medium scan speeds, and a beam walk-off 421b is observed at large distances that exceeds the beam walk-off 419b at medium scan speeds. Thus, beam walk-off increases with increasing target distance and scan speed. In one embodiment, the increasing target distance includes a time delay in which the images 418a, 418b move away from the tip 217 of the fiber core. Thus, a model of mode overlap appropriately accounts for this walk-off. In one embodiment, such a model should limit the beam walk-off 419 based on the diameter of the image 418 (e.g., no greater than half the diameter of the image 418).

[0124] Figure 4F is a diagram showing a method according to an embodiment of the present invention. Figure 2D System 200' or Figure 2E-2H 200" versus target distance for various scan rates. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 430 is the unitless coupling efficiency. In one embodiment, the coupling efficiency is inversely proportional to the beam walk-off 419. The first curve 432a depicts the coupling efficiency of the focused return beam 291 into the fiber tip 217 for various target distances based on no scanning of the beam. Over a wide range of target distances, the coupling efficiency remains relatively high and constant. The second curve 432b depicts the coupling efficiency of the focused return beam 291 into the fiber tip 217 for a medium scan rate of the beam. , the coupling efficiency of the focused return beam 291 into the optical fiber tip 217 for various target distances. In one embodiment, the coupling efficiency at a medium scan rate reaches a peak at a medium target distance (e.g., about 120m) and then decreases as the target distance increases. A third curve 432c depicts the coupling efficiency of the focused return beam 291 into the optical fiber tip 217 for various target distances based on a high scan rate of the beam. In one embodiment, the coupling efficiency at a high scan rate reaches a peak at a low target distance (e.g., about 80m) and then decreases as the target distance increases.

[0125] based on Figure 4F As shown in the curve in, scanning too fast may eventually make it impossible to see beyond a certain target distance. In this case, the image 418b of the focused return beam 291 is not coupled into the optical fiber tip 217, but completely walks away from the receiver mode of the tip 217. Figure 4G is a diagram showing a method for Figure 2D System 200' or Figure 2E-2H 2 is a graph of an example of SNR versus target distance for various scan rates in a system 200 of FIG. 4. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 404 is the SNR in decibels (dB). A first curve 440a depicts the SNR of the focused return beam 291 at the fiber tip 217 based on the target distance, where the beam is not scanned. A second curve 440b depicts the SNR of the focused return beam 291 at the fiber tip 217 based on the target distance, where the beam is scanned at a medium scan rate. In an example embodiment, the medium scan rate is approximately 2500 degrees per second (deg / s) or between approximately 1000 deg / s and 2500 deg / s. The mid-scan rate and the high-scan rate are in the range of about 4000 degrees / second or in the range of about 500 degrees / second to about 5000 degrees / second. The third curve 440c depicts the SNR of the focused return beam 291 at the fiber tip 217 based on the target distance, where the beam is scanned at a high scan rate. In an exemplary embodiment, the high scan rate is about 5500 degrees / second, or in the range of about 4000 degrees / second to about 7000 degrees / second, or in the range of about 3000 degrees / second to about 8000 degrees / second. In one embodiment, the mid-scan rate and the high scan rate are based on the beam size and the target of the system. In one embodiment, the mid-scan rate and the high scan rate are based on Fig.2I The drive structure of the scanning optical device 218 in the embodiment of the present invention is as follows: for example, the polygon scanner 244a rotates at a high scanning rate and the polygon scanner 244b rotates at a medium scanning rate, wherein the ratio of the high scanning rate to the medium scanning rate is based on Fig.2I In an exemplary embodiment, the above ranges of values ​​for the medium scan rate and the high scan rate are based on a collimated light beam having a diameter of approximately 1 centimeter (cm) for scanning images to a maximum target distance of approximately 200 meters (m).

[0126] In addition to the scan rate of the beam, the SNR of the return beam 291 is also affected by the integration time during which the acquisition system 240 and / or the processing system 250 samples and processes the return beam 291. In some embodiments, the beam is scanned between discrete angles, and at the discrete angles in the angular range 227, the beam is held stationary or nearly stationary for a corresponding integration time at each discrete angle. The SNR of the return beam 291 is affected by the value of the integration time and the target distance. As before, the cross-sectional area of ​​the beam increases with target distance, resulting in increased atmospheric scattering, and thus the intensity of the return beam 291 decreases with increasing distance. Therefore, for the return beam 291 from a longer target distance, a longer integration time is required to achieve the same SNR.

[0127] Figure 4H is a diagram showing a method according to an embodiment of the present invention. Figure 2D System 200' or Figure 2E-2H Graphs of examples of SNR versus target distance for various integration times in system 200'. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 404 is the SNR in decibels (dB). The first curve 450a describes the SNR value of the return beam 291 at the target distance, where the system 200', 200" is set to a first integration time (e.g., 3.2μs). The second curve 450b describes the SNR value of the return beam 291 at the target distance, where the system 200', 200" is set to a second integration time (e.g., 1.6μs). The third curve 450c describes the SNR value of the return beam 291 at the target distance, where the system 200', 200" is set to a third integration time (e.g., 800ns). A fourth curve 450d depicts SNR values ​​for the return beam 291 at a target distance, where the system 200', 200" is set to a fourth integration time (e.g., 400ns). Curve 450 shows that, for a fixed target distance, the SNR increases as the integration time increases. Curve 450 also shows that, for a fixed integration time, the SNR of the return beam 291 decreases as the distance increases for the reasons discussed previously. In one embodiment, the LIDAR system 200" selects a fixed integration time (e.g., 1.6 μs) for scanning at the range of angles 227 and the resulting target distances such that the SNR associated with the fixed integration time exceeds the SNR threshold 452 at the target distance. In some embodiments, the system 200" uses the target distance at each angle to minimize the integration time at each angle within the range of angles 227 in order to minimize the integration time over the range of angles 227. Fig. 4I is a diagram showing a method according to an embodiment of the present invention. Figure 2D System 200' or Figure 2E-2H2 is a graph of an example of measurement rate versus target distance in a system 200. The horizontal axis 402 is the target distance in meters (m), and the vertical axis 474 is the number of allowable measurements per unit time in units of the number of allowable measurements per second. Curve 476 shows the number of allowable measurements per second at each target distance. In one embodiment, curve 476 represents the inverse of the integration time, such as the number of return beams 291 that can be detected at each target distance per second, while the integration time represents the time spent processing the return beams 291 at each target distance. Curve 478 is also provided and is a good target for the number of allowable measurements per second at each target distance. Curve 478 is based on powers of 2 intervals for a given ADC (analog to digital conversion) rate. Curve 478 represents a good target for the number of allowable measurements per second because a fast Fourier transform of a signal of such length is more efficient when the number of digitized samples is a power of 2.

[0128] 5. Vehicle Control Overview

[0129] In some embodiments, the vehicle is controlled based at least in part on data received from a high-resolution Doppler LIDAR system mounted on the vehicle.

[0130] Figure 3A is a block diagram illustrating an example system 301 including at least one high resolution Doppler LIDAR system 320 mounted on a vehicle 310 according to an embodiment. The LIDAR system 320 may incorporate features of the LIDAR systems 200, 200', 200". The vehicle has a center of mass represented by asterisk 311 and is traveling in a forward direction given by arrow 313. In some embodiments, the vehicle 310 includes components, such as a steering or braking system (not shown), that operate in response to signals from a processor, such as the vehicle control module 272 of the processing system 250. In some embodiments, the vehicle has an onboard processor 314, such as Figure 8 In some embodiments, the onboard processor 314 communicates with the remote processor by wire or wirelessly, such as Figure 7 In one embodiment, the processing system 250 of the LIDAR system is communicatively coupled to the onboard processor 314, or the processing system 250 of the LIDAR system is used to perform the operations of the onboard processor 314, so that the vehicle control module 272 causes the processing system 250 to send one or more signals to the steering or braking system of the vehicle to control the direction and speed of the vehicle. The high-resolution Doppler LIDAR uses a scanning beam 322 that scans from one side to the other, represented by the future beam 323, across the azimuth field of view 324 and across the vertical angle ( Figure 3B) to illuminate a spot around vehicle 310. In some embodiments, the field of view is 360 degrees in azimuth. In some embodiments, the oblique field of view is from about +10 degrees to about -10 degrees or a subset thereof. In one embodiment, field of view 324 includes upper scanning area 262 and lower scanning area 264. In this embodiment, scanning beam 322 is in a manner similar to Figure 2E-2F or Figure 2G-2H The scanning beam 322 is scanned in a similar manner to the beam 233' in the system 200", for example, the scanning beam 322 is scanned by the second polygon scanner 244b on the field of view 324 in the upper scanning area 262, and the scanning beam 322 is also scanned by the first polygon scanner 244a on the field of view 324 in the lower scanning area 264. In the exemplary embodiment, for example FIG. 2E to FIG. 2F In the system 200 ”, the scanning beam 322 scans the upper scanning area 262 and the lower scanning area 264 in separate time periods. In another exemplary embodiment, for example Figure 2G-2H In the system, the scanning beam 322 is scanned simultaneously on the upper scanning area 262 and the lower scanning area 264. In another exemplary embodiment, the scanning beam 322 is scanned in opposite directions (reverse scanning) on ​​the upper scanning area 262 and the lower scanning area 264.

[0131] In some embodiments, the vehicle includes auxiliary sensors (not shown), such as a GPS sensor, an odometer, a tachometer, a temperature sensor, a vacuum sensor, a voltage or current sensor. In some embodiments, a gyroscope 330 is included to provide rotation information.

[0132] Figure 3B is a block diagram illustrating an example system 301' including at least one high resolution LIDAR system 320 mounted on a vehicle 310 according to an embodiment. The LIDAR system 320 may incorporate features of the system 200 or the system 200'. The vehicle 310 may be moving on a surface 349 (e.g., a road) in a forward direction based on arrow 313. In one embodiment, a first plane 235 is depicted as defining a lower scanning area 264, wherein a light beam 233' is scanned by a polygon scanner 244a from a first angle to a second angle. Additionally, a second plane 237 is depicted as defining an upper scanning area 262, wherein the light beam 233' is scanned by a polygon scanner 244b from a first angle to a second angle. In one embodiment, the system 200" may be used to scan the light beam 233' on the first plane 235' that intersects the upper limit 347. In this example embodiment, the scanning optics 218 are arranged with Figure 2J, such that the first polygon scanner 244a is located above the second polygon scanner 244b, and the first polygon scanner 244 scans the light beam on the first plane 235'. In one embodiment, the first planes 235, 235' are not aligned with the surface 349 and the upper limit 347, but are oriented within an angular range (e.g., within ±10 degrees of arrow 313 and / or within ±10 degrees of the second plane 237).

[0133] When designing the system 301', a predetermined maximum design range for the beam at each plane 235, 237 may be determined, and the predetermined maximum design range may represent the maximum expected target distance at each plane 235, 237. In one embodiment, the predetermined maximum design range is a fixed value or a fixed range of values ​​for each plane 235, 237. In one embodiment, the first plane 235 is oriented toward the surface 349 and intersects the surface 349 within a certain maximum design range from the vehicle 310. Therefore, for the first plane 235, the system 320 does not consider targets located outside the surface 349. In an exemplary embodiment, the first plane 235 forms an angle of about -15 degrees or in a range from about -25 degrees to about -10 degrees relative to the arrow 313, and the maximum design range is about 4 meters (m) or in a range from about 1m to about 10m or in a range from about 2m to about 6m. Therefore, for the first plane 235', the system 320 does not consider targets located above the upper limit 347. In an exemplary embodiment, the upper limit 347 is at a height of about 12 m or in a range of about 8 m to about 15 m from the surface 349 (e.g., which defines a height of 0 m), the first plane 235' forms an angle of about 15 degrees or in a range of about 10 degrees to about 20 degrees relative to the arrow 313, and the maximum design range is about 7 m or in a range from about 4 m to about 10 m or in a range from about 1 m to about 15 m.

[0134] In one embodiment, second plane 237 is oriented substantially parallel to arrow 313 and intersects target 343 located at a maximum designed range from vehicle 310. In one example embodiment, Figure 3B Not drawn to scale, and target 343 is positioned at a greater distance from vehicle 310 than depicted. For purposes of this specification, "substantially parallel" means within about ±10 degrees or within about ±15 degrees of arrow 313. In an example embodiment, the maximum design range of target 343 in second plane 237 is about 200 m, or within a range of about 150 m to about 300 m, or within a range of about 100 m to about 500 m.

[0135] 6. Method for optimizing scanning patterns in coherent LIDAR systems

[0136] Figure 5 is a flow chart illustrating an example method 500 for optimizing a scanning pattern of a LIDAR system on an autonomous vehicle. Figure 5 and 6 The steps are described as overall steps in a specific order, but one or more steps or parts thereof may be performed in a different order, or overlapped in time, serially or in parallel, or omitted, or one or more additional steps are added, or the method is changed in some combination to perform one or more steps or parts thereof.

[0137] In step 501, data is received on a processor, the data indicating a first SNR value of a signal reflected by a target and detected by a LIDAR system based on a value of a distance to the target, wherein the first SNR value is a corresponding value for a scanning rate of the LIDAR system. In one embodiment, in step 501, the data is a first SNR value of a focused return beam 291 at the optical fiber tip 217 in the system 200″. In one embodiment, the data includes values ​​of curve 440a and / or curve 440b and / or curve 440c for representing SNR values ​​of the return beam 291, wherein each curve 440 is a corresponding value for a scanning rate of the beam. In some embodiments, the data is not limited to curves 440a, 440b, 440c, and includes ratios. Figure 4G , wherein each SNR curve is based on a corresponding value of the scan rate. In some embodiments, the data includes SNR values ​​that can be used to form a curve at the target distance for each corresponding value of the scan rate. In an example embodiment, in step 501, the data is stored in a memory of the processing system 250, and each set of first SNR values ​​is stored together with an associated value of the scan rate of the LIDAR system. In one embodiment, in step 501, the first SNR value is obtained within a range from about 0 meters to about 500 meters (e.g., a motor vehicle) or within a range from about 0 meters to about 1000 meters (e.g., an air vehicle), and for a scan rate value within a range from about 2000 degrees / second to about 6000 degrees / second or from about 1000 degrees / second to about 7000 degrees / second. In some embodiments, the first SNR value is predetermined and received by the processor in step 501. In other embodiments, the first SNR value is measured by the LIDAR system and then received by the processor in step 501. In one embodiment, data is uploaded to the memory 704 of the processing system 250 in step 501 by input using the input device 712 and / or over the network link 778 from the local area network 780 , the Internet 790 , or an external server 792 .

[0138] In step 503, data is received on the processor, the data representing a second SNR value of a signal reflected by the target and detected by the LIDAR system based on the value of the range to the target, wherein the second SNR value is for a corresponding value of an integration time of the LIDAR system. In one embodiment, in step 503, the data is a second SNR value of the focused return beam 291 in the system 200″ for a corresponding integration time at which the acquisition system 240 and / or the processing system 250 process the beam. In one embodiment, the data includes values ​​of curve 450a and / or curve 450b and / or curve 450c and / or curve 450d for representing the SNR value of the return beam 291, wherein each curve 450 is for a corresponding value of an integration time for the acquisition system 240 and / or the processing system 250 process the beam. In some embodiments, the data is not limited to curves 450a, 450b, 450c, 450d, and includes a ratio Figure 4H , wherein each SNR curve is based on a corresponding value of the integration time. In some embodiments, the data need not be a curve, but rather an SNR value for forming a curve at a target distance for each corresponding value of the integration time. In an example embodiment, in step 503, the data is stored in a memory of the processing system 250, and each set of second SNR values ​​is stored together with an associated value of the integration time of the LIDAR system. In one embodiment, in step 503, the second SNR value is obtained within a range from about 0 meters to about 500 meters (e.g., a motor vehicle) or within a range from about 0 meters to about 1000 meters (e.g., an air vehicle) and for an integration time value from about 100 nanoseconds (ns) to about 5 microseconds (ps). In some embodiments, the second SNR value is predetermined and received by the processor in step 503. In some embodiments, the second SNR value is measured by the LIDAR system and then received by the processor in step 503. In one embodiment, data is input using input device 712 and / or uploaded over network link 778 to memory 704 of processing system 250 from local area network 780 , Internet 790 , or external server 792 in step 503 .

[0139] In step 505, data is received on the processor representing a first angle and a second angle for defining an angle range 324. In one embodiment, in step 505, the first angle and the second angle define an angle range 324 of a lower scanning area 264 defined by the first plane 235 (e.g., where the first and second angles are measured relative to arrow 313). In another embodiment, in step 505, the first angle and the second angle define an angle range 324 of an upper scanning area 262 defined by the second plane 237. In one embodiment, the first angle and the second angle are symmetrical about arrow 313, for example, the first angle and the second angle are equal and opposite to each other. In one embodiment, the first angle and the second angle are approximately ±60 degrees relative to arrow 313, for example, ±60 degrees relative to arrow 313, defining the angle range 324. In some embodiments, the first angle and the second angle are approximately ±30 degrees, approximately ±40 degrees, and approximately ±50 degrees relative to arrow 313. In one embodiment, steps 501 , 503 and 505 are performed simultaneously in one step, wherein the data in steps 501 , 503 and 505 are received at the processor in one simultaneous step.

[0140] In step 507, data is received on the processor, the data representing the maximum design range of the target along each plane 235, 237 used to define the upper scan area 262 and the lower scan area 264. In an embodiment, the maximum design range received in step 507 is a fixed value or a fixed range of values ​​for each plane 235, 237 used to define the upper scan area 262 and the lower scan area 264. In one embodiment, in step 507, the maximum design range of the first plane 235 is in the range of about 1m to about 15m or in the range of about 4m to about 10m, and in some embodiments, in step 507, the maximum design range of the second plane 237 is in the range of about 150m to about 300m or in the range of about 100m to about 400m.

[0141] In an example embodiment, the data in step 507 is input using an input device 712 (e.g., a mouse or pointing device 716) and / or uploaded to the processing system 250 over a network link 778. In some embodiments, the maximum design range is pre-determined and received during step 507. In some embodiments, the system 200, 200', 200" is used to measure the maximum design range at each plane 235, 237, and the maximum design range at each plane 235, 237 is then received by the processing system 250 in step 507.

[0142] In step 509, a maximum scan rate for the LIDAR system is determined at the first plane 235 such that the SNR of the LIDAR system is greater than a minimum SNR threshold. At the first plane 235, a maximum design range for that plane is first determined based on the data received in step 507. Then, the first SNR values ​​received in step 501 for the maximum design range at the plane 235 are determined, and it is further determined which of these first SNR values ​​exceed the minimum SNR threshold. In one embodiment, the values ​​of the curves 440a, 440b, 440c are determined for the maximum design range (e.g., about 120m), and it is also determined that the values ​​of the curves 440a, 440b exceed the minimum SNR threshold 442. Of those first SNR values ​​that exceed the minimum SNR threshold, the first SNR value with the maximum scan rate is selected, and the maximum scan rate for the plane 235 is determined in step 509. In the above embodiment, among the values ​​of the minimum SNR threshold 442 of the curves 440a, 440b that exceed the maximum design range (e.g., about 120 m), the value of the curve 440b is selected as the maximum scan rate, and the maximum scan rate (e.g., the medium scan rate associated with the curve 440b) is determined in step 509 for the plane 235. In step 511, step 509 is repeated, but the maximum scan rate is determined for the second plane 237.

[0143] In one embodiment, Figure 4G It is described that the maximum scanning rate determined in step 509 for the first plane 235 having a smaller maximum design range (e.g., the fast scanning rate based on curve 440c) is greater than the maximum scanning rate determined in step 511 for the second plane 237 having a larger maximum design range (e.g., the medium scanning rate based on curve 440b). Therefore, the rotation speed of the first polygon scanner 244a (e.g., scanning the light beam 233' along the lower scanning area 264 in the first plane 235) is set to be greater than the rotation speed of the second polygon scanner 244b (e.g., scanning the light beam 233' along the upper scanning area 262 in the second plane 237). In the exemplary embodiment, the scanning optical device 218 ( Fig.2I ) is arranged so that the ratio of the rotation speed of the first polygon scanner 244a to the rotation speed of the second polygon scanner 244b has an appropriate value based on steps 509 and 511. In one embodiment, the step of determining the maximum scanning rate in steps 509 and 511 ensures that the beam walk-off 419 ( Figure 4E ) is less than the ratio of the diameter of the image 418 of the return beam 291 on the tip 217. In an example embodiment, the ratio is about 0.5 or in the range of about 0.3 to about 0.7.

[0144] In step 513, a minimum integration time for the LIDAR system is determined at the first plane 235 so that the SNR of the LIDAR system is greater than a minimum SNR threshold. At the first plane 235, the maximum design range for the plane is first determined based on the data received in step 507. The second SNR values ​​received in step 503 are then determined for the maximum design range at the plane 235, and it is further determined which of these second SNR values ​​exceed the minimum SNR threshold. In one embodiment, the values ​​of the curves 450a, 450b, 450c, 450d are determined for the maximum design range (e.g., approximately 120m), and it is further determined that the values ​​of the curves 450a, 450b, 450c exceed the minimum SNR threshold 452. Among those second SNR values ​​that exceed the minimum SNR threshold, the second SNR value with the minimum integration time is selected, and the minimum integration time is determined for the plane 235 in step 513. In the above embodiment, among the values ​​of curves 450a, 450b, 450c that exceed the minimum SNR threshold 452 at the maximum design range (e.g., about 120m), the curve 450c value having the minimum integration time is selected and the minimum integration time (e.g., about 800ns) is determined for plane 235 in step 511. Step 515 involves repeating step 513 to determine the minimum integration time for the second plane 237.

[0145] In step 517, the scanning pattern of the lower scanning area 264 in the LIDAR system is defined based on the maximum scanning rate from step 509 and the minimum integration time from step 513. In one embodiment, the maximum scanning rate and the minimum integration time are fixed on the lower scanning area 264. In an example embodiment, the scanning pattern is stored in a memory (e.g., memory 704) of the processing system 250. In step 519, the scanning pattern of the upper scanning area 262 is defined based on the maximum scanning rate from step 511 and the minimum integration time from step 515.

[0146] In step 521, the LIDAR system operates according to the scanning pattern determined in steps 517 and 519. In one embodiment, in step 519, the beam of the LIDAR system is scanned in the field of view 324 over the lower scanning area 264 and the upper scanning area 262. In some embodiments, step 521 involves using Figure 2E-2F The system 200" and scanning the light beam 233' on the lower scanning area 264, followed by scanning on the upper scanning area 262 when the scanner 241 moves the light beam 233 from the first polygon scanner 244a to the second polygon scanner 244b. In another embodiment, step 521 involves using Figure 2G-2HThe system 200" is used to scan the light beam 233' on the lower scanning area 264 and the upper scanning area 262 at the same time. In one embodiment, in step 521, since the light beam 233' is scanned in opposite directions, the light beam 233' is scanned in the upper scanning area 262 and the lower scanning area 264 in the opposite direction. This advantageously improves the net resultant torque caused by the change in inertia of the scanning optical device 218 during step 521 due to the counter-rotation of the scanners 244a, 244b. In one embodiment, in step 521, the light beam is scanned through the upper scanning area 262 and the lower scanning area 264 in one or more cycles, wherein the scanning rate of the light beam in each area 262, 264 is the maximum scanning rate in the scanning pattern of the area 262, 264 (e.g., planes 235, 237), and the integration time of the LIDAR system at each area 262, 264 is the minimum integration time of the area 262, 264 (e.g., planes 235, 237).

[0147] During or after step 521, the processor may operate the vehicle 310 based at least in part on the data collected by the LIDAR system during step 521. In one embodiment, the processing system 250 for the LIDAR system and / or the processor 314 of the vehicle 310 sends one or more signals to the steering and / or braking systems of the vehicle based on the data collected by the LIDAR system in step 521. In one example embodiment, the processing system 250 sends one or more signals to the steering or braking systems of the vehicle 310 in response to the LIDAR data to control the position of the vehicle 310. In some embodiments, the processing system 250 sends one or more signals to the processor 314 of the vehicle 310 based on the LIDAR data collected in step 521, and the processor 314 in turn sends one or more signals to the steering and braking systems of the vehicle 310.

[0148] Figure 6 6 is a flow chart illustrating an example method 600 for operating a LIDAR system 200" on an autonomous vehicle, according to an embodiment. In step 601, a light beam 201 is generated from a laser source 212. In one embodiment, in step 601, the light beam 201 is coupled into a transmission waveguide 225 and transmitted from a tip 217 of the waveguide 225. In some embodiments, in step 601, the light beam 201 is split using a beam splitter (not shown), and the split light beams are directed into and transmitted from the tips 217 of the waveguides 225a, 225b. In some embodiments, in step 601, two laser sources 212 are provided, and each laser source 212 generates a respective light beam 201 that is directed into a respective waveguide 225A, 225B.

[0149] In step 603, the light beam is shaped using the collimator 229 to form a collimated light beam 205'. In one embodiment, in step 603, the light beam is shaped using the collimator 229 to form a light beam oriented in the third plane 234 (eg, Figure 2E , 2G In some embodiments, in step 603, the separated light beams are emitted from the tips 217 of the waveguides 225a, 225b, and the corresponding collimators 229a, 229b collimate the light beams to be oriented in the third plane 234 (e.g., Figure 2G In one embodiment, in step 603, within the third plane 234, the collimated beam 205' is directed toward one of the polygon scanners 244a, 244b ( Figure 2E-2F ) or towards both polygon scanners 244a, 244b ( Figure 2G-2H ) direction.

[0150] In step 605, the direction of the collimated light beam 205' generated in step 603 is adjusted from a first angle in the first plane 235 to a second angle in the first plane 235 using the first polygon scanner 244a. In one embodiment, in step 605, the light beam 233' is scanned over the lower scanning area 264 based on the rotation of the first polygon scanner 244a about the rotation axis 243. In one embodiment, in step 605, the scanner 241 directs the light beam 233 onto the face 245 of the first polygon scanner 244a for a period of time sufficient to scan the light beam 233' from the first angle to the second angle using the first polygon scanner 244a. In an exemplary embodiment, for the system 301', step 605 involves scanning the light beam 233' from the first angle to the second angle on the first plane 235 oriented toward the surface 349.

[0151] In step 607, one or more return beams 291 are received at the waveguide tip 217 of the system 200″ based on the adjustment of the direction of the beam 233′ in the first plane 235 in step 605. In one embodiment, in step 607, the return beams 291 are processed by the system 200″ to determine the distance to the target on the lower scanning area 264. In an example embodiment, in step 607, the return beams 291 are reflected from the surface 349 (or a target on the surface 349) based on the adjustment of the direction of the scanning beam 233′ in the first plane 235.

[0152] In step 609, on the third plane 234 ( Figure 2EIn one embodiment, in step 609, the direction of the light beam 205' is adjusted from the first polygon scanner 244a to the second polygon scanner 244b in a plane of the first polygon scanner 244a. In one embodiment, in step 609, the direction of the light beam 205' is adjusted using the scanner 241 at a continuous scanning speed, and the continuous scanning speed is slow enough that steps 605 and 607 are performed when the light beam 205' is on the face 245 of the first polygon scanner 244a. In one embodiment, in step 609, the direction of the light beam 205' is adjusted using the scanner 241 between the scanners 244a, 244b at a non-zero scanning speed and remains fixed on each of the scanners 244a, 244b until steps 605, 607 (for scanner 244a) or steps 611, 613 (for scanner 244b) are performed. In some embodiments, after the separated light beams 205' are transmitted to the separated polygon scanners 244a, 244b (e.g. Figure 2G-2H ), step 609 is omitted.

[0153] In step 611, the direction of the collimated light beam 205' generated in step 603 is adjusted from a first angle in the second plane 237 to a second angle in the second plane 237 using the second polygon scanner 244a. In one embodiment, in step 611, the light beam 233' is scanned over the upper scan area 262 based on the rotation of the second polygon scanner 244b about the rotation axis 243. In one embodiment, in step 611, the scanner 241 directs the light beam 233 onto the face 245 of the second polygon scanner 244b for a period of time sufficient to scan the light beam 233' from the first angle to the second angle using the second polygon scanner 244b. In an exemplary embodiment, for the system 301', step 611 involves scanning the light beam 233' from a first angle to a second angle in the second plane 237, the second plane being oriented toward the target 343 on the surface 349 (e.g., at a maximum range of from about 150m to about 400m). In one embodiment, the adjustment direction of the light beam 233 ′ in the second plane 237 in step 611 is opposite to the adjustment direction of the light beam 233 ′ in the first plane 235 in step 605 .

[0154] In step 613, one or more return beams 291 are received at the waveguide tip 217 of the system 200″ based on the adjustment of the direction of the beam 233′ in the second plane 237 in step 611. In one embodiment, in step 613, the return beams 291 are processed by the system 200″ to determine the distance to the target on the upper scanning area 262. In an example embodiment, in step 613, the return beams 291 are reflected from the target 343 based on the adjustment of the direction of the scanning beam 233′ in the second plane 237.

[0155] In step 615, it is determined whether more sweeps of the light beam 233' in the first plane 235 and / or the second plane 237 are to be performed. In one embodiment, step 615 involves comparing the number of sweeps of the light beam 233' in the first plane 235 and / or the second plane 237 to a predetermined number of sweeps of the light beam 233' in the first plane and / or the second plane 237 (e.g., stored in the memory 704). If additional sweeps of the light beam 233' are to be performed, the method 600 returns to step 605. If additional sweeps of the light beam 233' are not to be performed, the method 600 ends. In one embodiment, during the steps of the method 600, the polygon scanners 244a, 244b rotate continuously at a fixed speed. In one embodiment, when the method 600 ends, the processing system 250 sends a signal to the polygon scanners 244a, 244b to stop the rotation of the scanners.

[0156] In one embodiment, the method 600 also includes determining a distance to a target in the first plane 235 and / or the second plane 237 based on the return beam data received in steps 607 and 611. Additionally, in one embodiment, the method 600 includes adjusting one or more systems of the vehicle 310 based on the distance to the target in the first plane 235 and the second plane 237. In an example embodiment, the method 600 includes adjusting one or more of a steering system and / or a braking system of the vehicle 310 based on the target distance data determined from the return beam data in steps 607 and 611.

[0157] 7. Overview of computing hardware

[0158] Figure 7 700 is a block diagram showing a computer system 700. The computer system 700 includes a communication mechanism such as a bus 710 for transmitting information between other internal and external components of the computer system 700. Information is represented as a physical signal of a measurable phenomenon, usually a voltage, but in other embodiments includes phenomena such as magnetic, electromagnetic, pressure, chemical, molecular atoms and quantum interactions. For example, north and south magnetic fields, or zero and non-zero voltages, represent two states (0, 1) of a binary digit (bit). Other phenomena can represent numbers of higher cardinality. The superposition of multiple simultaneous quantum states before measurement represents a quantum bit (qubit). A sequence of one or more numbers constitutes digital data for representing a number or code of a character. In some embodiments, information referred to as analog data is represented by a near continuum of measurable values ​​within a specific range. The computer system 700 or a portion thereof constitutes a device for performing one or more steps of one or more methods herein.

[0159] The binary digit sequence constitutes digital data for representing the digits or codes of characters. The bus 710 includes many parallel conductors of information so that the information is quickly transmitted among the devices coupled to the bus 710. One or more processors 702 for processing information are coupled to the bus 710. The processor 702 performs a set of operations on the information. The set of operations includes introducing information from the bus 710 and placing the information on the bus 710. The set of operations also typically includes comparing two or more information units, moving the position of the information unit, and combining two or more information units, such as by addition or multiplication. The series of operations performed by the processor 702 constitutes a computer instruction.

[0160] The computer system 700 also includes a memory 704 coupled to the bus 710. The memory 704, such as a random access memory (RAM) or other dynamic storage device, stores information including computer instructions. Dynamic memory allows information stored therein to be changed by the computer system 700. RAM allows a unit of information stored at a location called a memory address to be stored and retrieved independently of information at adjacent addresses. The memory 704 is also used by the processor 702 to store temporary values ​​during the execution of computer instructions. The computer system 700 also includes a read-only memory (ROM) 706 or other static storage device coupled to the bus 710 for storing static information, including instructions, that is not changed by the computer system 700. Also coupled to the bus 710 is a non-volatile (permanent) storage device 708, such as a magnetic or optical disk, for storing information, including instructions, that persists even when the computer system 700 is shut down or otherwise loses power.

[0161] Information (including instructions) is provided to the bus 710 for use by the processor from an external input device 712, such as a keyboard or sensor containing alphanumeric keys operated by a human user. The sensor detects conditions in its vicinity and converts these detections into signals compatible with those used to represent information in the computer system 700. Other external devices coupled to the bus 710, primarily for interaction with humans, include a display device 714 for presenting images, such as a cathode ray tube (CRT) or a liquid crystal display (LCD), and a pointing device 716, such as a mouse or trackball or cursor direction keys, which is used to control the position of a small cursor image presented on the display 714 and to issue commands associated with graphical elements presented on the display 714.

[0162] In the illustrated embodiment, special purpose hardware, such as an application specific integrated circuit (IC) 720, is coupled to bus 710. The special purpose hardware is configured to perform operations not performed by processor 702 quickly enough for special purposes. Examples of special purpose ICs include graphics accelerator cards for generating images for display 714, cryptographic boards for encrypting and decrypting messages sent over a network, voice recognition, and interfaces to special external devices such as robotic arms and medical scanning equipment for repeatedly performing certain complex sequences of operations that are more efficiently implemented in hardware.

[0163] The computer system 700 also includes one or more instances of a communication interface 770 coupled to the bus 710. The communication interface 770 provides a two-way communication coupling with various external devices that operate using their own processors, such as printers, scanners, and external disks. Typically, the coupling is performed with a network link 778 connected to a local network 780, and various external devices with their own processors are connected to the local network. For example, the communication interface 770 can be a parallel port or a serial port or a universal serial bus (USB) port on a personal computer. In some embodiments, the communication interface 770 is an integrated services digital network (ISDN) card or a digital subscriber line (DSL) card or a telephone modem that provides an information communication connection to a corresponding type of telephone line. In some embodiments, the communication interface 770 is a cable modem that converts signals on the bus 710 into signals for communication connection on a coaxial cable or into optical signals for communication connection on a fiber optic cable. As another example, the communication interface 770 can be a local area network (LAN) card to provide a data communication connection to a compatible LAN (e.g., Ethernet). A wireless link can also be implemented. Carrier waves, such as acoustic and electromagnetic waves, including radio waves, optical waves, and infrared waves, propagate through space without wires or cables. Signals include artificial variations in the amplitude, frequency, phase, polarization, or other physical properties of carrier waves. For wireless links, the communication interface 770 sends and receives electrical, acoustic or electromagnetic signals, including infrared and optical signals, that carry information data streams such as digital data.

[0164] The term computer-readable medium is used herein to refer to any medium that participates in providing information to the processor 702, including instructions for execution. Such media can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as storage device 708. Volatile media include, for example, dynamic memory 704. Transmission media include, for example, coaxial cables, copper wire, fiber optic cables, and waves that travel through space without wires or cables, such as sound waves and electromagnetic waves, including radio waves, light waves, and infrared waves. The term computer-readable storage medium is used herein to refer to any medium that participates in providing information to the processor 702, except for transmission media.

[0165] Common forms of computer-readable media include, for example, floppy disks, flexible disks, hard disks, magnetic tapes or any other magnetic media, compact disk ROMs (CD-ROMs), digital video disks (DVDs) or any other optical media, punch cards, paper tapes or any other physical media with patterns of holes, RAMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), FLASH-EPROMs or any other memory chips or cartridges, carrier waves or any other media from which a computer can read. The term non-transitory computer-readable storage media is used herein to refer to any medium that participates in providing information to the processor 702, other than carrier waves and other signals.

[0166] Logic encoded in one or more tangible media includes one or both of processor instructions on a computer-readable storage medium and dedicated hardware such as ASIC 720 .

[0167] The network link 778 typically provides information communication through one or more networks to other devices that use or process the information. For example, the network link 778 can provide a connection to a host computer 782 or to equipment 784 operated by an Internet Service Provider (ISP) through a local network 780. The ISP equipment 784 in turn provides data communication services through the public global packet-switched communications network of networks now commonly referred to as the Internet 790. Computers called servers 792 connected to the Internet provide services in response to information received on the Internet. For example, the server 792 provides information representing video data for presentation on the display 714.

[0168] The computer system 700 can implement the various techniques described herein in response to the processor 702 executing one or more sequences of one or more instructions contained in the memory 704. Such instructions, also referred to as software and program code, can be read into the memory 704 from another computer-readable medium such as the storage device 708. Execution of the sequences of instructions contained in the memory 704 causes the processor 702 to perform the method steps described herein. In alternative embodiments, hardware such as an application specific integrated circuit 720 can be used in place of software or in combination with software to implement the present invention. Therefore, embodiments of the present invention are not limited to any specific combination of hardware and software.

[0169] Signals transmitted over network link 778 and other networks through communication interface 770 carry information to and from computer system 700. Computer system 700 can send and receive information including program code through network 780, 790, etc. through network link 778 and communication interface 770. In the example using Internet 790, server 792 sends program code for a specific application requested by a message sent from computer 700 through Internet 790, ISP equipment 784, local network 780 and communication interface 770. The received code can be executed by processor 702 when it is received, or can be stored in storage device 708 or other non-volatile storage device for later execution, or both. In this way, computer system 700 can obtain application program code in the form of signals on a carrier wave.

[0170] Various forms of computer readable media may be involved in carrying one or more instruction sequences or data or both to the processor 702 for execution. For example, the instructions and data may initially be carried on a disk of a remote computer such as the host 782. The remote computer loads the instructions and data into its dynamic memory and sends the instructions and data over a telephone line using a modem. The modem local to the computer system 700 receives the instructions and data on the telephone line and uses an infrared transmitter to convert the instructions and data into a signal on an infrared carrier used as a network link 778. An infrared detector used as a communication interface 770 receives the instructions and data carried in the infrared signal and places information representing the instructions and data on the bus 710. The bus 710 transmits the information to the memory 704, from which the processor 702 retrieves the instructions and executes the instructions using some data sent with the instructions. The instructions and data received in the memory 704 may optionally be stored on the storage device 708 before or after execution by the processor 702.

[0171] Figure 8A chip set 800 is shown on which an embodiment of the present invention may be implemented. The chip set 800 is programmed to perform one or more steps of the methods described herein and includes, for example, a processor and a processor associated with the chip 800 in one or more physical packages (eg, chips). Figure 7 The processor and memory components described herein are described. As an example, a physical package includes the arrangement of one or more materials, components, and / or wires on a structural assembly (e.g., a substrate) to provide one or more characteristics such as physical strength, dimensional preservation, and / or electrical interaction limitation. It is contemplated that in some embodiments, the chipset may be implemented in a single chip. Chipset 800, or a portion thereof, constitutes a means for performing one or more steps of the methods herein.

[0172] In one embodiment, the chipset 800 includes a communication mechanism such as a bus 801 for transferring information among the components of the chipset 800. The processor 803 has a connection to the bus 801 to execute instructions and process information stored in, for example, a memory 805. The processor 803 may include one or more processing cores, each of which is configured to execute independently. A multi-core processor enables multi-processing within a single physical package. Examples of multi-core processors include two, four, eight or more processing cores. Alternatively or additionally, the processor 803 may include one or more microprocessors configured in series via the bus 801 to enable independent execution of instructions, pipelines and multithreading. The processor 803 may also be accompanied by one or more dedicated components to perform certain processing functions and tasks, such as one or more digital signal processors (DSPs) 807 or one or more application specific integrated circuits (ASICs) 809. The DSP 807 is typically configured to process real-world signals (e.g., sound) in real time independently of the processor 803. Similarly, the ASIC 809 may be configured to perform specialized functions that are not easily performed by a general-purpose processor. Other specialized components to aid in performing the inventive functions described herein include one or more field programmable gate arrays (FPGA) (not shown), one or more controllers (not shown), or one or more other special-purpose computer chips.

[0173] The processor 803 and the accompanying components have connectivity to the memory 805 via the bus 801. The memory 805 includes both dynamic memory (e.g., RAM, disk, writable optical disk, etc.) and static memory (e.g., ROM, CD-ROM, etc.) for storing executable instructions, which, when executed, will perform one or more steps of the method herein. The memory 805 also stores data associated with the execution of one or more steps of the method herein or data generated by executing one or more steps of the method herein.

[0174] Now that some illustrative implementations have been described, it is apparent that the foregoing is illustrative rather than restrictive and has been presented by way of example. In particular, although many of the examples presented herein relate to specific combinations of method actions or system elements, those actions and those elements may be combined in other ways to achieve the same purpose. The actions, elements, and features discussed in conjunction with one embodiment are not intended to be excluded from other embodiments or similar roles in embodiments.

[0175] The words and terms used herein are for descriptive purposes and should not be considered limiting. The use of "comprising," "including," "having," "containing," "involving," "characterized by," "characterized by," and variations thereof herein is intended to encompass the items listed thereafter, their equivalents, and additional items, and alternative implementations consisting of the items listed thereafter. In one embodiment, the systems and methods described herein consist of one, or each combination of more than one, or all of the described elements, actions, or components.

[0176] Any reference to the implementation or element or action of the system and method mentioned in the singular form herein may also include the implementation containing multiple these elements, and any reference to any implementation or element or action in the plural form herein may also include the implementation containing only one element. Reference in the singular or plural form is not intended to limit the currently disclosed system or method, their parts, actions or elements to a single or multiple configuration. Reference to any action or element based on any information, action or element may include the implementation wherein the action or element is based at least in part on any information, action or element.

[0177] Any implementation disclosed herein may be combined with any other implementation or embodiment, and references to "an implementation," "some implementations," "an implementation," etc. are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in conjunction with an implementation may be included in at least one implementation or embodiment. Such terms as used herein do not necessarily all refer to the same implementation. Any implementation may be combined with any other implementation (inclusively or exclusively) in any manner consistent with the aspects and implementations disclosed herein.

[0178] Where a technical feature in the drawings, detailed description or any claims is followed by a reference numeral, the reference numeral has been included to increase the intelligibility of the drawings, detailed description and claims. Therefore, the presence or absence of a reference numeral has no limiting effect on the scope of any claim element.

[0179] Without departing from its characteristics, the systems and methods described herein may be implemented in other specific forms. Further descriptions of relative parallel, vertical, vertical or other positioning or orientation include deformation within + / -10% or + / -10 degrees of pure vertical, parallel or vertical positioning. Unless otherwise expressly indicated, reference to "approximately", "about", "substantially" or other degree terms include changes of + / -10% relative to a given measurement, unit or range. Coupled elements may be electrically, mechanically or physically coupled to each other directly or through intermediate elements. Therefore, the scope of the systems and methods described herein is indicated by the appended claims rather than the foregoing description, and changes within the equivalent meaning and scope of the claims are included therein.

[0180] The term "coupling" and its variations include two members being directly or indirectly connected to each other. Such a connection can be fixed (e.g., permanent or fixed) or movable (e.g., movable or releasable). Such a connection can be achieved by coupling the two members directly to each other or to each other, by coupling the two members to each other using a separate intermediate member or any additional intermediate member to which they are interconnected, or by coupling the two members to each other through an intermediate member that is integrally formed as a single entity with one of the two members. If "coupling" or its variations are modified by additional terms (e.g., direct coupling), the general definition of "coupling" provided above is modified by the plain language meaning of the additional terms (e.g., "direct coupling" refers to connecting two members without any separate intermediate member between the two members), resulting in a narrower definition than the general definition of "coupling" provided above. Such a coupling can be mechanical, electrical or fluid.

[0181] References to "or" may be interpreted as inclusive, such that any term described using "or" may indicate any of the described terms, singly, plurally, and all. References to "at least one of 'A' and 'B'" may include only 'A', only 'B', and both 'A' and 'B'. Such references used in conjunction with "including" or other open-ended terms may include additional items.

[0182] Modifications may be made to the described elements and actions (e.g., size, dimensions, structure, shape and proportion of various elements, values ​​of parameters, mounting arrangements, use of materials, colors, deformations in orientation) without substantially departing from the teachings and advantages of the subject matter disclosed herein. For example, an element shown as being integrally formed may be composed of multiple parts or elements, the position of elements may be reversed or otherwise changed, and the nature or number or position of discrete elements may be changed or varied. Other substitutions, modifications, changes, and omissions may also be made in the design, operating conditions, and arrangement of the disclosed elements and operations without departing from the scope of the present disclosure.

[0183] References to the positions of elements (e.g., "top," "bottom," "upper," "lower") herein are only used to describe the orientation of the various elements in the drawings. It should be noted that the orientation of the various elements may be different according to other exemplary embodiments, and such variations are intended to be encompassed by the present disclosure.

Claims

1. A light detection and ranging LIDAR system, comprising: a laser source configured to generate a laser beam; a preliminary scanner configured to scan the laser beam as a first beam along a first path and to scan the laser beam as a second beam along a second path, the first path and the second path extending in a beam plane; Electric motor; a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis extending in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along a first path from a first side of and toward the rotation axis, the first scanner configured to deflect the first beam through a first area in a first scanning plane at a first angle relative to the beam plane to detect objects in a first field near the LIDAR system; as well as a second scanner coupled to the motor, the motor configured to rotate the second scanner about the rotation axis in a second direction different from the first direction to deflect the second light beam onto the second scanner, the second scanner positioned to receive the second light beam along the second path from the first side of the rotation axis and toward the rotation axis, the second scanner configured to deflect the second light beam through a second region in a second scanning plane at a second angle relative to the beam plane to detect objects in a second field away from the LIDAR system relative to the first field, the first region being below the second region relative to the rotation axis, and the first region having a greater angular extent in the beam plane than the second region.

2. The LIDAR system according to claim 1, wherein: The first scanner is a first polygon scanner and the second scanner is a second polygon scanner.

3. The LIDAR system of claim 1, wherein: the first scanner being configured to deflect the first light beam from a first angle in the first scanning plane to a second angle in the first scanning plane that is less than or equal to sixty degrees from the first angle in the first scanning plane, the first scanning plane being located in a first scanning region; and The second scanner is configured to deflect the second light beam from a first angle in the second scanning plane to a second angle in the second scanning plane that is less than or equal to sixty degrees from the first angle in the second scanning plane, and the second scanning plane is located in a second scanning area that is adjacent to the first scanning area in height.

4. The LIDAR system according to claim 1, wherein: The first scanner is configured to rotate at a first rotational speed, the second scanner is configured to rotate at a second rotational speed, and the first rotational speed is greater than the second rotational speed.

5. The LIDAR system of claim 1, further comprising at least one collimator configured to provide the first beam to the first scanner and the second beam to the second scanner.

6. The LIDAR system of claim 1, wherein: The first scanner is a polygonal scanner having an inscribed diameter greater than or equal to 1 inch and less than or equal to 3 inches and a height greater than or equal to 2 inches and less than or equal to 3 inches.

7. An autonomous vehicle control system comprising: a laser source configured to generate a laser beam; Electric motor; a preliminary scanner configured to scan the laser beam as a first beam along a first path and to scan the laser beam as a second beam along a second path, the first path and the second path extending in a beam plane; a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis extending in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along a first path from a first side of and toward the rotation axis, the first scanner configured to deflect the first beam through a first area in a first scanning plane at a first angle relative to the beam plane to detect objects in a first field near the LIDAR system; a second scanner coupled to the motor, the motor configured to rotate the second scanner about the rotation axis in a second direction different from the first direction to deflect the second light beam onto the second scanner, the second scanner positioned to receive the second light beam along a second path from the first side of the rotation axis and toward the rotation axis, the second scanner configured to deflect the second light beam through a second region in a second scanning plane at a second angle relative to the beam plane to detect objects in a second field away from the LIDAR system relative to the first field, the first region being below the second region relative to the rotation axis, and the first region having a greater angular extent in the beam plane than the second region; as well as One or more processors configured to: receiving a return signal corresponding to at least one of the first light beam or the second light beam; as well as A control signal is sent to at least one of a steering system of an autonomous vehicle or a braking system of the autonomous vehicle based on the return signal to control at least one of a direction or a speed of the autonomous vehicle.

8. The autonomous vehicle control system of claim 7, wherein: The one or more processors are configured to determine at least one of a distance to an object or a velocity of an object in response to the return signal.

9. An autonomous vehicle comprising: LIDAR system, which includes: a laser source configured to generate a laser beam; a preliminary scanner configured to scan the laser beam as a first beam along a first path and to scan the laser beam as a second beam along a second path, the first path and the second path extending in a beam plane; Electric motor; a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis extending in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along a first path from a first side of and toward the rotation axis, the first scanner configured to deflect the first beam through a first area in a first scanning plane at a first angle relative to the beam plane to detect objects in a first field near the LIDAR system; and a second scanner coupled to the motor, the motor configured to rotate the second scanner about the rotation axis in a second direction different from the first direction to deflect the second light beam onto the second scanner, the second scanner positioned to receive the second light beam along a second path from the first side of the rotation axis and toward the rotation axis, the second scanner configured to deflect the second light beam through a second region in a second scanning plane at a second angle relative to the beam plane to detect objects in a second field away from the LIDAR system relative to the first field, the first region being below the second region relative to the rotation axis, and the first region having a greater angular extent in the beam plane than the second region; Steering system; Braking system; and A vehicle controller comprising one or more hardware processors configured to send a control signal based on a return signal corresponding to at least one of the first light beam or the second light beam to control at least one of the steering system or the braking system.

10. The autonomous vehicle of claim 9, wherein: The LIDAR system is mounted to the autonomous vehicle such that the second scanner is located above the first scanner.

11. The autonomous vehicle of claim 9, wherein: The LIDAR system is mounted to at least one of the front or top of the autonomous vehicle.

12. The autonomous vehicle of claim 9, wherein: The vehicle controller is configured to determine at least one of a distance to an object or a speed of an object in response to the return signal.

Images