System for testing an environment for frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR) systems

Abstract

A system for emulating a wireless environment for testing a unit under test (UUT) of a light detection and ranging (LiDAR) unit. The system can include a lens system to receive light from the LiDAR UUT and a plurality of optical processing chains. The system can generate light into free space based on the light signals processed by each chain. The system can optically process the received light to maintain coherence with the light received from the LiDAR unit under test and can process all points in a LiDAR image simultaneously. The system can operate to emulate an over-the-air environment of a time-of-flight LiDAR UUT, a frequency modulated continuous wave (FMCW) LiDAR UUT, and / or a flash LiDAR UUT.

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 023,984, filed May 13, 2020, entitled “System for Emulating an Environment for Testing a Light Detection and Ranging LiDAR System,” inventors Marcus daSilva, Amarpal Khanna, Jason Marks, and Douglas Farrell, which is incorporated herein by reference in its entirety as if fully and completely set forth herein. Technical Field

[0003] This disclosure relates to the field of testing, and more particularly to a system for simulating an over-the-air environment used to test a LiDAR (Light Detection and Ranging) system. Background Technology

[0004] Light detection and ranging (LiDAR) is a method of detecting objects, targets, or even entire scenes by shining light onto a target and processing the reflected light. LiDAR is similar in principle to radar. The difference is that LiDAR uses light with wavelengths outside the radio or microwave bands to detect targets. Infrared light is typically used, but other frequencies can also be used. The smaller wavelengths give LiDAR better spatial resolution, allowing it to represent an entire scene as a point cloud. Unlike photographic images that map intensity and color to two dimensions, each point in a LiDAR point cloud can additionally have an associated distance and / or velocity.

[0005] A typical LiDAR unit uses lasers to emit light. These emissions are scanned within the field of view and reflected by any objects in their path. The reflected light is received and processed by the LiDAR unit. Measurements of the received light (amplitude, delay, Doppler shift, etc.) and the scan angle (φ, θ) are aggregated to create a physical description of objects in the LiDAR field of view. This method can represent a scene as a point cloud, such as... Figure 1 As shown in the diagram. Each point in the cloud can have the following properties:

[0006] • Horizontal angle or azimuth angle (usually represented by φ)

[0007] • Vertical angle or elevation angle (usually represented by θ)

[0008] • Distance to the LiDAR unit. This is typically done by measuring the time required for light to travel to and from the object and back.

[0009] • The velocity relative to the LiDAR cell. This can be measured in two ways:

[0010] ο Doppler shift of reflected light.

[0011] ο Calculate the changes in distance detected in continuous distance measurements.

[0012] • Reflectivity. This is the proportion of incident light reflected by an object, sometimes referred to as "intensity".

[0013] Developers and manufacturers of LiDAR units, as well as manufacturers of the vehicles (cars, airplanes, etc.) that will install them, frequently need to test LiDAR under a variety of conditions. Currently, as of 2020, developers and manufacturers are taking either one of the following approaches: 1) testing in an outdoor environment, or 2) building a physical model of a real-world environment over a large area. While this provides a well-defined testing environment, it is large, expensive, difficult to automate, and not scalable.

[0014] Therefore, improvements in this area are expected. Summary of the Invention

[0015] This document presents embodiments of systems and methods for performing LiDAR testing and target simulation. More specifically, the embodiments relate to systems for simulating an airborne environment for testing and / or calibrating a unit under test (LiDAR) for optical detection and ranging (LiDAR). The system may include an input lens system configured to receive light from the LiDAR unit under test (UUT), multiple optical processing chains coupled to the lens system, and an output lens system coupled to each optical processing chain. In some embodiments, a single lens system may serve as both the input and output lens systems. The output lens systems are configured to generate light into free space and / or return it to the LiDAR UUT based on the optical signals processed by each optical processing chain.

[0016] Each optical processing chain may include at least one optical fiber coupled to an input lens system and configured to provide an optical signal corresponding to the received light. Each chain may also include a frequency shift simulator coupled to multiple optical fibers, configured to generate a frequency shift in the received optical signal. The frequency shift simulator may include an optical IQ modulator or an optical phase-locked loop. In some embodiments, the frequency shift simulator may use different frequency shifts for up-slope and down-slope to simulate distance and Doppler frequency shifts. Each chain may also include a selectable optical delay device coupled to a frequency shift estimator and configured to selectively delay the optical signal to simulate the round-trip delay of reflected light. Finally, each chain may include at least one optical attenuator / amplifier configured to selectively control (attenuate or amplify) the amplitude of the optical signal to simulate different levels of reflectivity and path loss.

[0017] The system can be configured to optically process the received light to maintain coherence with the light received from the LiDAR unit under test. In some embodiments, the system can process all points in the LiDAR image simultaneously.

[0018] The system may also include a LiDAR image generator coupled to a frequency-shift simulator, a selectable optical delay, and an optical attenuator / amplifier, which may be user-programmable to control the operation of these devices. For example, the LiDAR image generator may be configured to provide frequency-shift values ​​to the frequency-shift simulator for use when creating a frequency offset in the received optical signal. The LiDAR image generator may also be configured to provide delay values ​​to the selectable optical delay for use in delaying the optical signal to simulate the round-trip time of reflected light. Finally, the LiDAR image generator may be configured to provide amplitude values ​​to the optical attenuator / amplifier to control the amplitude of the optical signal to simulate different levels of path loss from free space, polarization variation and reflectivity, spectral components of reflection, and / or diffuse reflection components of reflection. The LiDAR image generator may be configured to provide frequency-shift, delay, and / or amplitude values ​​for each point in the point cloud generated by the system. The set of values ​​provided by the LiDAR image generator may correspond to a specific test environment. In other words, this set of values ​​can be pre-calculated to simulate a specific scenario used to test the LiDAR UUT.

[0019] The embodiments may also relate to a system for simulating an airborne environment used to test a LiDAR UUT. The system may include an input lens system configured to receive light from the UUT. The system may also include an input beam splitter coupled to the input lens system and configured to receive optical signals and provide a portion of the optical signals to one or both of a first optical processing path and a second optical processing path. The system may also include at least one optical shutter array coupled to the first and second optical processing paths.

[0020] The first optical processing path may include a photodetector array for determining the angle of a laser pulse at a specific moment, wherein the position of the received light on the photodetector array is used to open the corresponding element in the optical shutter array. The position of the received light on the photodetector array may correspond to vertical and horizontal scan angles (φ, θ), where the vertical and horizontal scan angles are used to open the corresponding element in the optical shutter array. Alternatively, a single lens system may be used to receive light from the LiDAR UUT and output the processed light back to the LiDAR UUT. In one embodiment, each photodetector in the photodetector array has a one-to-one mapping to a corresponding shutter in the optical shutter array. Alternatively, each of multiple groups of multiple photodetectors in the photodetector array may have a many-to-one or one-to-many mapping to a corresponding shutter in the optical shutter array.

[0021] The second optical processing path may include an amplitude controller for controlling the amplitude of the optical signal to simulate different levels of path loss from free space, polarization variation and reflectivity, spectral components of reflection, and / or diffuse reflection components of reflection. The second path may also include a LiDAR image generator coupled to control the amplitude controller. The second optical processing path may be configured to provide a decay signal to the optical shutter array to exit through one or more opening elements in the optical shutter array.

[0022] In some embodiments, the second optical processing path further includes a frequency shifter coupled to a selectable optical delay element. The frequency shifter is configured to generate a frequency offset in the received optical signal. Thus, in this embodiment, the second optical processing path can provide a frequency-shifted and attenuated signal to the system output. For example, the system may include an optical shutter array and may provide a processed signal to exit through one or more opening elements in the optical shutter array. Alternatively, the system may utilize a lens system to receive light from the LiDAR UUT and output the processed light back to the LiDAR UUT. The frequency shifter may include an optical IQ modulator or an optical phase-locked loop.

[0023] In some embodiments, the second optical processing path may further include a selectable optical delay element coupled to the frequency shifter. This selectable optical delay element can be configured to selectively delay the optical signal to simulate the round-trip delay of reflected light. In this embodiment, the second optical processing path can be configured to provide a delayed and attenuated signal to at least one optical shutter array to exit through one or more opening elements in the optical shutter array. Alternatively, the system can utilize a lens system to receive light from the LiDAR UUT and output the delayed and attenuated signal back to the LiDAR UUT.

[0024] Other aspects of the invention will become apparent with reference to the accompanying drawings and the detailed description that follows. Attached Figure Description

[0025] A better understanding of the invention can be obtained by considering the following detailed description of preferred embodiments in conjunction with the accompanying drawings, in which:

[0026] Figure 1 Pulse time-of-flight (ToF) LiDAR operation according to some embodiments is illustrated;

[0027] Figure 2 This is a block diagram of a frequency modulated continuous wave (FMCW) LiDAR system according to some embodiments;

[0028] Figure 3 The diagram illustrates upper and lower linear frequency modulation (FM) ramps according to some embodiments;

[0029] Figure 4A Single-flash LiDAR operation according to some embodiments is illustrated;

[0030] Figure 4B Multi-flash LiDAR operation according to some embodiments is illustrated;

[0031] Figure 5 The diagram illustrates a block diagram of a ToF LiDAR target simulator according to some embodiments;

[0032] Figure 6 The illustration shows a LiDAR scene simulator that can be used for ToF, FMCW and flash LiDAR according to some embodiments;

[0033] Figure 7 The diagram illustrates a block diagram of a system for creating an optical frequency shift according to some embodiments;

[0034] Figure 8AThis is a block diagram of a LiDAR scene simulator for ToF and FMCW LiDAR, including an optical shutter array, according to some embodiments.

[0035] Figure 8B This is a block diagram of a LiDAR scene simulator for ToF and FMCW LiDAR, including an input / output lens system, according to some embodiments.

[0036] Figure 9A The illustration shows a one-to-one mapping between a photodetector array and an optical shutter array according to some embodiments;

[0037] Figure 9B The illustration shows a four-to-one mapping between a photodetector array and an optical shutter array according to some embodiments;

[0038] Figure 10 The illustration depicts the use of frequency shift to simulate delay and Doppler frequency shift in an FMCW LiDAR according to some embodiments;

[0039] Figure 11 The illustration shows a schematic diagram of a flash LiDAR scene simulator according to some embodiments;

[0040] Figure 12 The illustration depicts a method for simulating a flash LiDAR aerial scene using a 2D matrix sequence, according to some embodiments.

[0041] Figure 13 The illustration depicts a method for generating a simulated scene for a flash LiDAR using dedicated timing elements, according to some embodiments.

[0042] Figure 14 This is a flowchart illustrating a method for simulating an airborne environment for testing ToF and / or FMCWLiDAR UUT according to various embodiments; and

[0043] Figure 15 This is a flowchart illustrating a method for simulating an aerial environment for a flash LiDAR UUT according to some embodiments.

[0044] While the invention is readily adaptable to various modifications and alternatives, specific embodiments thereof are illustrated by way of example in the accompanying drawings and described in detail herein. However, it should be understood that the drawings and their detailed description are not intended to limit the invention to the specific forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Detailed Implementation

[0045] the term

[0046] The following is a glossary of terms that may appear in this disclosure:

[0047] Memory media—any of various types of nontransitory memory devices or storage devices. The term "memory media" is intended to include mounting media such as CD-ROMs, floppy disks, or tape drives; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory; magnetic media such as hard disk drives or optical storage devices; registers or other similar types of memory elements, etc. Memory media may also include other types of nontransitory memory or combinations thereof. Furthermore, memory media may reside in a first computer system executing a program, or may reside in a second, different computer system connected to the first computer system via a network (such as the Internet). In the latter case, the second computer system may provide program instructions to the first computer system for execution. The term "memory media" may include two or more memory media residing in different locations, for example, in different computer systems connected via a network. Memory media may store program instructions (e.g., implemented as a computer program) that can be executed by one or more processors.

[0048] Computer system (or computer) – any of various types of computing or processing systems, including personal computer systems (PCs), mainframe computer systems, workstations, networked appliances, internet-connected appliances, personal digital assistants (PDAs), television systems, grid computing systems, or other devices or combinations thereof. In general, the term “computer system” can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions in a memory medium.

[0049] Processing element (or processor) – refers to various elements or combinations of elements capable of performing functions in a device (e.g., user equipment equipment or cellular network equipment). Processing elements may include, for example: a processor and associated memory, a portion or circuitry of a separate processor core, an entire processor core, a processor array, circuitry such as an ASIC (Application-Specific Integrated Circuit), programmable hardware elements such as a Field-Programmable Gate Array (FPGA), and any combination thereof.

[0050] "Configured as"—Various components can be described as being "configured as" to perform one or more tasks. In this context, "configured as" is a broad reference, generally meaning "having" a "structure" that performs one or more tasks during operation. Thus, even when the component is not currently performing a task, it can be configured to perform that task (e.g., a set of electrical conductors can be configured to electrically connect one module to another, even if the two modules are not connected). In some contexts, "configured as" can be a broad reference to a structure, generally meaning a "circuit system" that performs one or more tasks during operation. Thus, even when the component is not currently powered on, it can be configured to perform a task. Generally, the circuit system forming the structure corresponding to "configured as" can include hardware circuitry.

[0051] For ease of description, various components may be described as performing one or more tasks. Such descriptions should be interpreted as including the phrase "configured to". References to components configured to perform one or more tasks are explicitly intended not to invoke the interpretation of that component in paragraph 6 of §112 of 35 U.S.SC.

[0052] The embodiments described herein relate to systems and methods for simulating optical environments observed by LiDAR. More specifically, the embodiments described herein can provide developers and manufacturers of LiDAR cells with small, easily replicable, and computer-controlled components that can simulate optical environments observed by LiDAR.

[0053] In 2020, there were three main types of commercially available or under development LiDAR. Each has its own simulation challenges: 1) Pulse Time-of-Flight LiDAR (ToF); 2) LiDAR using a series of linear FM chirps or frequency-modulated continuous waves (FMCW); and 3) Flash LiDAR. The embodiments in this paper present systems and methods for simulating the optical environments of one or more of these types of LiDAR, or potentially for other types of LiDAR that may be developed in the future.

[0054] Figure 1 –ToF LiDAR block diagram

[0055] Figure 1 A simplified schematic diagram of ToF LiDAR is shown. ToF LiDAR uses the following basic functional blocks to render a scene:

[0056] 1) Pulsed Laser: ToF LiDAR emits short, high-amplitude laser pulses. The amplitude can be high so that the receiver can capture the pulse reflected from a distance. This requirement for very strong light pulses is one of the drawbacks of ToF LiDAR.

[0057] 2) Scanner: Laser pulses pass through a scanner that alters the angle at which light propagates in the field of view. Continuous laser pulses scan the scene, thus covering the field of view. Some LiDAR systems use a single laser with a two-dimensional raster scanner, while others may use a vertical array of lasers performing horizontal scans (i.e., each laser scan is in one dimension). Scanners can be mechanical, have rotating mirrors, and / or they can be implemented using solid-state laser arrays, MEMS devices, or optical phase arrays, etc.

[0058] 3) The target object in the field of view. The laser pulse is reflected from the target object. The material, roughness, and angle of the reflecting surface determine the reflectivity, or the proportion of reflected light power. The LiDAR unit receives the signal attenuated by path loss in free space, polarization changes, and reflectivity, the spectral components of the reflected light, and / or the diffuse reflection components. This path loss can be determined by distance and any attenuation (such as dust, fog, etc.). The reflections received by the LiDAR will have a time delay. This delay is the round-trip time of light from the LiDAR unit to the target and back. The rate can be calculated from the change of this distance over time for a continuous laser pulse. ToF LiDAR does not measure Doppler shift. The LiDAR unit has information about the angle (φ, θ) of the emitted light set from the scanner. The LiDAR uses this angle information to reconstruct the scene in its field of view.

[0059] 4) Point Cloud. The scene is rendered as an array of points, each point having the following attributes: i) the horizontal and vertical angles (φ, θ) of the illuminated point relative to the LiDAR; ii) the reflectivity at the LiDAR illuminated point; iii) the distance between the illuminated point and the LiDAR; and / or 4) the relative velocity at the LiDAR illuminated point. It should be noted that in ToF LiDAR, velocity is only measured indirectly. As of April 2020, commercially available or under development ToF LiDARs can render scenes as point clouds with 1,000 to 100,000 points.

[0060] Figure 2 FMCW LiDAR

[0061] Figure 2 A simplified schematic diagram of an FMCW LiDAR system is shown. FMCW LiDAR uses linear FM modulation of the laser and synchronous processing of the receiver. Not only are FMCW LiDARs more resistant to interference than ToF LiDARs, they also require significantly less peak optical power to achieve the same range and sensitivity. FMCW LiDARs typically operate at eye-safe wavelengths because the laser is always on during operation.

[0062] FMCW LiDAR can use the following basic functional blocks to render scenes:

[0063] 1) FM Modulated Laser Sources. Lasers in FMCW LiDARs also generate optical pulses. However, compared to ToF LiDARs, these pulses have longer durations and lower amplitudes, and they are FM modulated using either a linear ramp or a frequency scan. Many FMCW LiDARs use a combination of linear rising and falling ramps in their frequency scans. Linear frequency scanning offers several signal processing advantages over ToF LiDARs, as detailed below.

[0064] 2) Linear Frequency Scan Processing. Linear frequency scanning refers to the actual frequency of the laser changing linearly with time. The laser is reflected by the target object and experiences a round-trip time delay. This time delay means that the frequency of the received signal is the same as the frequency transmitted earlier before the time delay. The received signal is mixed with the transmitted signal, and the resulting baseband signal is processed electronically. Upscanning refers to receiving a frequency lower than the transmitted frequency for a stationary object. Downscanning refers to receiving a frequency higher than the transmitted frequency for a stationary object. If the target object moves relative to the LiDAR cell, the received signal will also experience a frequency shift due to the Doppler effect, which is independent of the scan direction. The effects of transit delay and Doppler shift can be separated by processing upscanning and downscanning together. The frequency shift in upscanning includes the Doppler effect minus the delay effect. The frequency shift in downscanning includes the Doppler effect plus the delay effect.

[0065]

[0066]

[0067] Therefore, the effect of Doppler frequency shift can be separated from the effect of round-trip time delay, allowing the FMCW LiDAR system to calculate the velocity of reflection points in the scene and the distance to the reflection points.

[0068] Figure 3 Up-down linear FM ramp

[0069] Figure 3 The diagram illustrates the relationship between transmit (TX) and receive (RX) frequencies and time for a real LiDAR signal. The frequency can be modulated using linear ramps. Each chirped ramp (i.e., the rising and falling ramps) can have a duration longer than the maximum round-trip delay. The received signal can be a delayed version of the transmitted signal. In the rising ramp, the delay causes the RX frequency to be lower than the TX frequency. In the falling ramp, the delay causes the RX frequency to be higher than the TX frequency. Velocity can also cause frequency shifts due to the Doppler effect. For example, the frequency shift increases as the target approaches and decreases as the target retreats.

[0070] Both transit time and the Doppler effect can cause frequency shifts. This frequency shift is recovered when the received light pulse mixes with the emitted light pulse.

[0071] Upper chirp: Δf up =Δ Doppler -Δ transit

[0072] Down chirp: Δf down =Δ Doppler +Δ transit

[0073]

[0074]

[0075] As light travels to the target and returns, there may be a dead time at the beginning of each ascending or descending slope.

[0076] The scanner can operate as follows. Laser pulses can pass through the scanner, which can change the angle at which light propagates in the field of view. Continuous laser pulses can be scanned across the scene to cover the field of view. Some LiDARs can use a single laser with a 2D scanner, while others can use a vertical laser array (or a horizontal laser array for vertical scanning) for horizontal scanning. The scanner can be mechanical, with rotating mirrors, or solid-state. Target objects in the field of view can affect the system as follows: Laser pulses are reflected from the target object, where the material, roughness, and / or angle of the reflecting surface determine the reflectivity, or the proportion of light reflected. The LiDAR unit can receive signals attenuated by path loss from free space, polarization changes, and reflectivity, the spectral components of the reflected light, and / or the diffuse components of the reflected light. This path loss can be determined by distance and any attenuation (such as dust, fog, etc.). Reflections received by the LiDAR will have a time delay. This delay is the round-trip time of light from the LiDAR unit to the target and back. The time delay can itself manifest as a frequency shift of the RX frequency relative to the TX frequency. This frequency shift is negative for upward scanning and positive for downward scanning. Reflection can also exhibit a Doppler shift proportional to the rate difference between the LiDAR unit and the target object. This Doppler shift can be independent of the scanning direction. The LiDAR unit possesses information about the angle (φ, θ) at which the emitted light is set from the scanner. The LiDAR uses this angular information to reconstruct the scene within its field of view.

[0077] A synchronous receiver can operate as follows. The LiDAR receiver combines the reflected pulses and the emitted pulses. The result is a signal that can be used to determine the frequency difference between the emitted and received light at a given moment. This low-frequency signal (typically in the MHz range) is processed using conventional RF signal processing techniques. The ability to electronically process the received signal with a much lower bandwidth significantly improves the achievable signal-to-noise ratio (SNR). This allows for imaging of distant objects with much lower emitted laser power compared to what is required for ToF LiDAR. The relative velocity of the target object can be measured directly via the Doppler frequency shift.

[0078] Point cloud. A scene can be rendered as an array of points, each point having the following properties: 1) horizontal and vertical angles (φ, θ); 2) reflectivity at the LiDAR-illuminated point; 3) distance between the illuminated point and the LiDAR; and 4) relative velocity at the LiDAR-illuminated point.

[0079] As of April 2020, the FMCW LiDAR, under development, could render scenes as clouds with 1,000 to 100,000 points.

[0080] Flash LiDAR

[0081] Flash LiDAR is a specific type of LiDAR, not the scanned pulse time-of-flight (“ToF”) or frequency modulated continuous wave (“FMCW”) LiDAR types. Flash LiDAR devices are currently commercially available, and the technology is constantly improving. Some embodiments described herein address the challenges of testing flash LiDAR devices by allowing LiDAR devices to be coupled to systems simulating 3D world environments. This process works by combining optical and electronic techniques to simulate the responses that a flash LiDAR would receive in driving or other man-made scenarios. The responses received by the LiDAR then create a “point cloud,” which is the standard output of the flash LiDAR device and is substantially similar to the point cloud that would be created in real driving or other scenarios. Because the flash LiDAR optical output is not physically connected to the simulation system, the simulation will be optically “in the air” or in free space. This approach will enable the testing of flash LiDAR in a cost-effective, efficient, and highly repeatable manner.

[0082] Figure 4AThe diagram illustrates a simplified schematic of a flash LiDAR device with a single laser source. As the name suggests, flash LiDAR behaves much like a familiar flash camera. The entire scene is filled with light. Flash LiDAR differs from other LiDARs in the following ways. First, there is typically no scanner associated with the emitted light pulse. For single-laser flash LiDAR, light from a single laser pulse is propagated across the entire field of view through a lens system or diffuser. For some flash LiDAR devices, a scanning system may be used, but they still differ from ToF and FMCW scanning systems in that they "flash" a subsection of the field of view at a time, and this subsection moves over time. The flash is a reflection of light from the target object. Unlike the point-by-point illumination of other types of LiDAR, the entire scene (or a subsection of the scene) is illuminated together by flashing short laser pulses and propagating the light using a diffuser. Second, the reflected light is captured by lenses and projected onto the imager, much like an electronic camera. Third, the imager, composed of thousands of pixels, processes each pixel using ToF, FMCW, or other techniques to render the image.

[0083] Figure 4B A simplified schematic diagram of a multi-beam flash LiDAR is shown. Multi-beam flash LiDAR is similar to single-beam flash LiDAR, but differs in that it uses more than one laser at its emitter (e.g., a laser array). Each laser in the array illuminates a small portion of the target area, and the firing of the lasers is individually controlled. In some embodiments, several lasers can be fired simultaneously, and a complete image is established once all lasers are fired. In some embodiments, higher frequencies can be used to fire in areas considered more important, resulting in foveated firing. Advantageously, multi-beam flash LiDAR can alleviate the range limitations of flash LiDAR because it reduces the power required by the lasers, as each laser illuminates a small area.

[0084] Some embodiments described herein depict an aerial environment simulator system for operation with single-beam and / or multi-beam flash LiDAR devices.

[0085] LiDAR scenario simulation challenge

[0086] The job of a LiDAR scene simulator is to create a simulated aerial environment that is indistinguishable from the actual scene for the LiDAR under test (LUT). Furthermore, it is desirable for the scene simulator to be small, inexpensive, and programmable, allowing for the simulation of many moving objects, attenuation (sunlight, dust, snow, other LiDAR elements, etc.), and environmental factors. Some properties of a LiDAR simulator include:

[0087] 1) Field of View (FOV): This refers to the horizontal and vertical (φ, θ) angles at which the LiDAR creates the image. The symbol φ represents the horizontal angle range, which can be 30 to 360 degrees for automotive LiDAR applications. The symbol θ represents the vertical angle, which can vary within a range, for example, from -10 to +80 degrees, or from 10 to 90 degrees for automotive LiDAR applications. Simulators can create scenes that cover all or part of the FOV.

[0088] 2) Angular resolution, which is the smallest angle that LiDAR can detect. As an example, the vertical and horizontal angular resolution can be on the order of 0.1 degrees.

[0089] 3) Number of points in a point cloud. Automotive LiDAR typically depicts scenes with 1,000 to over 1,000,000 points, but other numbers of points are also possible.

[0090] 4) Minimum / maximum distance. Automotive LiDAR can operate at distances ranging from 1m to approximately 300m, and other possibilities.

[0091] Simulates the minimum / maximum speed of an object. Automotive LiDAR can measure speeds ranging from 0 to 500 km / h.

[0092] 5) Interference generation, such as noise, dust, rain, sunlight, and other LiDAR components.

[0093] 6) Scene Dynamics. The ability to change the scene frame by frame. LiDAR's frame rate can range from 10 to 100 frames per second.

[0094] 7) LiDAR Types. The phrase "LiDAR Types" refers to the types of LiDAR the system can emulate. Currently, commercial simulators exist for ToF LiDAR. FMCW and Flash LiDAR are currently under development in 2021. The industry needs a programmable simulator for use with FMCW LiDAR.

[0095] 8) Simulator Size. Automotive LiDAR is designed to see a wide field of view at distances up to 300 meters. Other LiDAR applications may require even greater distances. Ideally, the simulator should occupy only a small portion of that space, allowing it to be placed on a workbench, in a factory workshop, or on a production line.

[0096] 9) Point Cloud Simulation. LiDAR can render scenes with 1,000 to 100,000 points. Each point in the point cloud has azimuth and elevation angles, reflectivity, distance, and Doppler shift. Scanning LiDAR can utilize the sequential nature of scanning to share electronic and optical processing elements in a time-sharing manner.

[0097] 10) Flash LiDAR simultaneously illuminates all points in the scene. Optical processing is performed in parallel. Like camera imagers, the imager in a flash LiDAR receiver may use scanning processing internally. Unlike TOF and FMCW systems that use laser scanning for transmission, the scanner's status cannot be determined by observing external laser patterns. If available, this knowledge of internal scanning could be used to share optical and electrical signal processing components within a simulator.

[0098] Currently available commercial automotive LiDAR simulators are designed for scanned pulse ToF LiDAR and cannot be used with flash or FMCW types. These simulators use... Figure 5 The methods shown work. The embodiments herein improve upon these LiDAR simulators by providing systems and methods for LiDAR simulation that can be used with FMCW and / or flash LiDAR systems.

[0099] Figure 5 Block diagram of a scanned ToF LiDAR target simulator

[0100] Figure 5 This is a block diagram description of a prior art ToF target simulator. A photodetector array, combined with a lens or mirror system, is used to detect light pulses from a LiDAR UUT. Each position on the photodetector array (i.e., each pixel) corresponds to a different vertical and horizontal scan angle (φ, θ). An alternative approach is to ignore the emitted laser and use signals from the LiDAR unit to determine the scanner's state and the timing of the laser pulses. Each photodetector in the photodetector array is connected to a pulse generator. The rising edge of the photodetector triggers a pulse. The image processor is programmed to assign amplitude and delay values ​​to each pixel. The delay and amplitude values ​​are fed to a delay generator and an amplitude controller. Pulses with scaled delay and amplitude are fed to a laser diode array. These generate scaled and delayed light pulses. The laser diode array can have a one-to-one correspondence with the photodetector array. The number of laser diodes does not need to have a one-to-one correspondence with the photodetector array. The UUT knows the angle at which the original pulse was sent and may not require a full-resolution laser diode array to reconstruct the scene. Figure 5 The key difference between the LiDAR simulator shown and some of the embodiments described herein is that... Figure 5 The simulator in the LiDAR UUT creates new optical pulses in response to receiving optical pulses from the LiDAR UUT, and the LiDAR simulator based on some embodiments described herein modulates the received optical pulses and returns them to the LiDAR UUT.

[0101] Simulation System Implementation Examples

[0102] The novel simulator described herein can have various embodiments. In some embodiments, the simulator described herein can provide LiDAR scene simulation for more than one type of LiDAR, including all three of ToF, FMCW, and Flash. While feasible, this approach may be overly complex and expensive for practical implementations using currently available technologies. Technological advancements may make this approach feasible in the future. The second embodiment may be a less complex concept for LiDAR scene simulation that can be used for both ToF and FMCW LiDAR. Other embodiments may be versions that can be used only for one of ToF LiDAR, FMCW LiDAR, or Flash LiDAR.

[0103] The following description begins with the most general, complex, and expensive implementation. Simplifications that may be possible due to the characteristics of ToF and FMCW LiDAR will be described further below.

[0104] Figure 6 –Parallel Point Cloud Simulator–LiDAR Scene Simulator

[0105] Figure 6 This is a conceptual block diagram of a LiDAR target simulator that is independent of LiDAR type. In other words, Figure 6 The illustration shows a parallel point cloud simulator—a LiDAR scene simulator—that can work for Time-of-Flight (ToF), FMCW, and flash LiDAR UUTs. This simulator embodiment can process all points in a LiDAR image simultaneously. The simulator embodiment can also perform optical processing on the laser to maintain coherence with the original signal emitted by the LiDAR UUT. This coherence may be useful for FMCW processing.

[0106] The following provides a block description for the parallel point cloud simulator:

[0107] The input optical processing block may contain a lens array capable of guiding each point in the LiDAR cloud to a corresponding optical fiber, with each fiber connected to an optical processing chain. A mapping exists between the optical fibers and processing chains and each point in the cloud. Some embodiments may employ direct mapping, where rendering a LiDAR scene with 1000 points would require 1000 optical processing chains, one for each point. Other embodiments may employ indirect mapping, where multiple points can be mapped to each optical processing chain.

[0108] Each optical processing chain may contain a frequency shift simulator, also known as a Doppler frequency shift simulator. The Doppler frequency shift simulator generates a frequency shift in the light transmitted through the optical fiber. This can be accomplished in several ways, such as... Figure 7 As shown in the block diagram.

[0109] Optical in-phase quadrature (IQ) modulator. An IQ modulator can be used to shift the frequency of an incoming signal. Optical IQ modulators have an optical bandwidth in the 10 GHz range and an optical local oscillator (LO) input at the optical wavelength used in LiDAR. An RF signal generator can be used to generate sine and cosine waves of the same frequency. The cosine wave is fed to the I input of the IQ modulator, and the sine wave is fed to the Q input, such that I = Cos(ωt) and Q = -sin(ωt). The optical signal at the output of the IQ modulator will be shifted by an angular frequency ω. The frequency ω can be selected to correspond to the Doppler frequency shift of the simulated point. An alternative to optical IQ modulators is to use an optical phase-locked loop (PLL) to provide the frequency shift, such as... Figure 7 As shown. More specifically, Figure 7 The diagram illustrates methods for generating optical frequency shifts, including optical IQ modulators or optical PLLs. It should be noted that ToF LiDAR cannot detect Doppler frequency shifts, and this block may not be used in ToF LiDAR simulators.

[0110] Each optical processing chain can also include selectable optical delays. These selectable optical delays can be operated to delay optical pulses to simulate the round-trip delay of reflected laser light. This can be implemented as switchable segments of binary weighted delays. Time segments such as 2, 4, 8, 16, 32, 64, 128, 256, and 512 ns can simulate round-trip delays corresponding to, for example, 30 cm to 76.8 m. The delays are typically implemented using fiber of selectable length.

[0111] Each optical processing chain may also include optical attenuators and amplifiers: these provide a means of controlling the amplitude of the optical signal to simulate different levels of path loss from free space, polarization variations, and reflectivity, spectral components of reflection, and / or diffuse reflection components of reflection. Light passing through each fiber can be selectively attenuated or amplified to ensure that the intensity of light received by the LiDAR corresponds to the reflectivity and path loss at the location on the simulated object.

[0112] This method offers numerous advantages, such as its applicability to all types of LiDAR, independent of scanning, modulation, or imaging methods. Furthermore, it truly simulates the behavior of real-world objects. Disadvantages include complexity, size, and power consumption, which may make it impractical for larger point clouds with numerous points. Additionally, the method can utilize RF generators, IQ modulators, and optional optical delays for each point in the cloud. These are both expensive and cumbersome, as clouds can have up to 100,000 points, thus the current cost could reach tens of millions of dollars. It should be noted that technological advancements (photonic ICs, multi-channel parallel fibers, etc.) may make this more economically feasible in the future.

[0113] Figures 8A-8B Simulator system for pulse ToF and FMCW LiDAR.

[0114] Figure 8A and Figure 8B The illustration shows two LiDAR scene simulators that can be used for FMCW and ToF LiDAR UUT according to some embodiments. More specifically, Figure 8A The illustration shows a point cloud simulator for a scanning pulse system, such as a LiDAR scene simulator for ToF LiDAR and FMCW LiDAR. This system utilizes the fact that the laser is scanned and the laser pulses do not arrive at all points in the point cloud simultaneously. This allows expensive optical and electronic signal processing blocks to be shared in a time-division manner. The light pulses from the LiDAR under test are optically processed to maintain the coherence required for FMCW LiDAR.

[0115] Figure 8A The diagram illustrates a schematic block diagram of a LiDAR scene simulator capable of performing FMCW and ToF LiDAR scene simulations. The system may include an input light splitter block 802, which acquires a portion of the incoming light signal and splits it into two paths. Path 1 is fed to a photodetector array to determine the angle (φ, θ) of the laser pulse at a specific moment. Path 2 is fed to a lens system 804, which focuses all the light into a small number of optical fibers, each of which is fed to an optical processing chain. A LiDAR with a single laser and two-dimensional scanning can use a single optical processing chain. A LiDAR with multiple lasers and one-dimensional scanning can use one optical processing chain for each laser in the LiDAR under test. For example, a LiDAR with 16 vertically stacked lasers can use 16 optical processing chains.

[0116] In path 1, a photodetector array, combined with a lens or mirror system, is used to detect light pulses from the LiDAR UUT. The positions on the photodetector array (pixels) correspond to the vertical and horizontal scan angles (φ, θ). This information is used to open the corresponding elements in the optical shutter array 806, such as... Figure 9A and 9B As shown in the diagram. The photodetector array and optical shutter array can have, for example... Figure 9A The one-to-one mapping shown or as Figure 9B The different mapping schemes are shown. A photodetector array determines which of its detectors receives the light pulse. A mapping exists from the photodetector array to the optical shutter array. This can be, for example... Figure 9A The one-to-one mapping in the model can be used, or other possible mapping schemes can be used, such as Figure 9B As shown, it illustrates a 1:4 mapping. Figure 9BAs shown, the proportion of light in each of the four elements in the upper left quadrant of the photodetector array can be used to identify the center of the laser spot in the optical shutter array. Other mappings are also possible. Each photodetector in the array has a corresponding pulse generator. The rising edge of the photodetector triggers a pulse. This pulse can be fed as a timing reference to the LiDAR image generator.

[0117] Path 2 may include an optical processing chain. As shown, optical pulses from the optical signal splitter are fed into an optical processing chain including a frequency shifter, a selectable optical delay, an amplitude controller, and a LiDAR image generator. The LiDAR image generator can be programmed to assign amplitude, Doppler shift, and delay values ​​to each point in the point cloud. The delay value of one or more points active at each scan position is fed into the selectable optical delay. The Doppler shift of one or more points active at each scan position is fed into an RF signal generator that feeds an optical IQ modulator. The IQ modulator can create an offset in the optical frequency equal to the desired Doppler shift. An optical PLL can also be used to generate the frequency offset. The amplitude value of one or more points active at each scan position is fed into a selectable gain / attenuation stage. The optical signal from each optical processing chain is fed into a lens system that illuminates the optical shutter array 806.

[0118] Delayed, Doppler-shifted, and attenuated signals exit through opening elements in the optical shutter array. There is a mapping between the photodetector array and the optical shutter array. The optical shutter array can be reflective (mirrors) or transmissive (lenses).

[0119] Figure 8B The diagram illustrates some aspects of... Figure 8A The system shown operates similarly to a LiDAR scene simulator system. However, in Figure 8B In the system shown, the lens system 854 is used both to receive light from the LiDAR UUT and to output the processed light back to the LiDAR UUT (instead of...). Figure 8A (As in [the text], using a separate optical shutter array or MEMS mirror array for output). Figure 8B As shown, specialized devices such as the off-axis parabolic mirror 852 can be used to guide light from the LiDAR UUT onto the lens system 854. The lens system 854 focuses different light spots received from the LiDAR UUT onto different optical fibers (or optical circulators) 855. A beam splitter is also used to split the received light into path 1 and path 2, as shown. Figure 8AAs shown in the diagram, light on path 2 is fed to the scanning detection system 874. Scanning information can (optionally) be received from the LiDAR UUT. The received light and / or scanning information are then used by the amplitude controller 870 and the optical attenuator 866, optical amplifier 868, LiDAR image generator 864, and / or RF signal generator 862 to determine the parameters of the optical modulator 858 and the selectable optical delay 860 to modify the light on path 1 to simulate an aerial environment. After the received light is processed by the optical modulator 858 and the selectable optical delay 860 in each fiber, the processed light is returned to the fiber to be transmitted back to the LiDAR UUT through the lens system.

[0120] Another embodiment relates to a point cloud simulator for a pulsed ToF LiDAR system used for scanning. The pulsed ToF system does not directly respond to Doppler frequency shift. Figures 8A-8B In such systems, frequency shifter blocks may be unnecessary and can be removed. LiDAR image generator blocks can be flexible and accurate enough to change latency point-by-point and frame-by-frame in a way that accurately reflects the desired target rate.

[0121] Another embodiment relates to a point cloud simulator for an FMCW LiDAR system used for scanning. The FMCW LiDAR experiences both path delay and Doppler frequency shift as a frequency shift. In some embodiments, it can be obtained from... Figures 8A-8B The optional delay device is removed from the diagram, and both path delay and Doppler shift can be simulated by an IQ tuner. This can be operated in the following dual-slope FMCW LiDAR system. Figure 7 The RF signal generator in the model can be designed to rapidly change the frequency as the FMCW slope changes from positive to negative, such as... Figure 10 As shown in the diagram. During the upslope period, the RF signal generator can be programmed to generate a frequency with a Doppler component minus a delay component. During the downslope period, the RF signal generator can be programmed to generate a frequency with a Doppler component plus a delay component. Switching transients may exist in the signal generator. As long as such transients occur during the short period of time during which the LiDAR switches from upslope processing to downslope processing, they are ignored. This dwell time can be at least the round-trip delay of the light pulse and can be approximately 6 ns per meter of distance. This dwell time allows for frequency changes.

[0122] Flash LiDAR Scene Simulation

[0123] In some embodiments, the LiDAR scene simulator system is specifically described for both flash LiDAR, single-beam flash LiDAR, and multi-beam flash LiDAR. These methods allow for LiDAR testing, simulation, and calibration for the entire field of view and / or subsets of the LiDAR's field of view. These methods can operate in real-time at the same frame rate as flash LiDAR sensors, enabling data playback and hardware-in-the-loop (“HiL”) test types.

[0124] Figure 11 The diagram illustrates a method for simulating LiDAR scenarios of single-beam and multi-beam flash LiDAR types. The method shown can simultaneously simulate the entire field of view of a LiDAR system. This method utilizes an optical detector placed in front of the flash LiDAR device. When the LiDAR device “flashes” its output light, the detector sends an instruction to the simulator system's processor. For single-beam flash LiDAR, only one optical detector is used to detect the LiDAR flash. For multi-beam flash LiDAR, multiple optical detectors can be used, one for each beam of the LiDAR device. For any future LiDAR developments that may use scanning or multi-beam flash LiDARs with one or more beams, a dedicated detector can be used to detect which pixels are illuminated.

[0125] The software allows the creation of synthetic point clouds, which serve as the basis for generating data back to the LiDAR device once one or more LiDAR flashes occur. This synthetic point cloud can include the extent and intensity of each point in the cloud. These extent and intensity values ​​are converted into timing and light intensity values, which can then be sent back to the simulator for transmission to the LiDAR device when one or more LiDAR flashes occur.

[0126] There are two proposed methods that can accurately generate point clouds back to the LiDAR system, such as Figure 12 and Figure 13 As shown in the figure, and described below.

[0127] Figure 12A method for generating simulated flash point clouds is illustrated. This method creates a clock with a data rate corresponding to a specific distance resolution. For example, a 1 GHz clock corresponds to a 15 cm distance resolution (e.g., light travels approximately 30 cm through air in 1 nanosecond, a round trip distance, which corresponds to a 15 cm unidirectional distance resolution). The clock divides the point cloud into 15 cm "temporal and spatial slices" and updates the 2D array with the intensity values ​​for each specific instance in time and space. It then populates the next 2D array after one clock cycle with the next temporal and spatial slices. In other words, the point cloud software generates a series of matrices, each describing an array of light intensity to be transmitted back to the LiDAR device at a specific moment. Each matrix encodes the light intensity of the simulated scene at a specific simulated distance from the LiDAR device. For a 1 GHz clock, the matrix would instruct the 2D LED array to transmit light back to the LiDAR device with a 1 nanosecond delay between transmissions, and this delay would simulate the increasingly larger round-trip delay of subsequent LED transmissions. This constructs a 3D intensity array with a small distance resolution (15 cm for a 1 GHz clock). It should be noted that the array typically has a large number of empty elements because very little light returns compared to the distance and temporal resolution the array creates. The system outputs the array in response to receiving detections from the optical detectors. The timing of the output array is calibrated so that the round-trip distance between the LiDAR device's output and input is the same as it is expected in the "real world," meaning there exists a minimum distance that the system can simulate.

[0128] The optical output of the simulator system is transmitted via densely packaged 2D LEDs or optical diodes, similar to an OLED screen. Each element of the optical array can be driven at the same clock rate as previously selected. The 2D LED array can operate in the appropriate spectrum for a particular LiDAR sensor, such as 905 nm. Each element of the 2D LED array has variable amplitude control, and the amplitude of each pixel in each successive output is determined by the corresponding value of the 2D matrix element received from the point cloud software. These embodiments can utilize a large amount of memory space and rather complex electrical designs, but advantageously leverage relatively simple optical designs.

[0129] Figure 13 The illustration depicts alternative methods for generating simulated scenes for flash LiDAR, according to some embodiments. This is similar to combining... Figure 12 The described method uses the software output of the simulation software as a series of delays and intensities. The difference lies in that each element of the 2D LED optical array has its own dedicated timing element, instead of using a global 1GHz clock. Advantageously, this eliminates the need to create an array with mostly empty elements. Furthermore, Figure 13The system shown can effectively operate using a slower (and cheaper) 100MHz clock, instead of Figure 12 The system shown operates using a 1GHz clock. Instead, each pixel has a dedicated module that transmits instructions to the corresponding pixel to output light of a specified intensity. However, Figure 13 The embodiments described herein utilize ratio Figure 12 The embodiments described herein have greater electrical and optical complexity because each optical element of the 2D array uses a delay generator and an optical amplifier.

[0130] Figure 14 –ToF / FMCW LiDAR Environment Simulation Flowchart

[0131] Figure 14 This is a flowchart illustrating a method for simulating an airborne environment for testing ToF and / or FMCW LiDAR UUTs using a simulator system, according to various embodiments. The simulator system may include a lens system and multiple optical processing chains. The simulator system may also include a processor coupled to a non-transitory memory medium, wherein the processor is configured to direct the operation of the simulator system. In some embodiments, the described methods and systems may be specifically tailored to operate with a ToF LiDAR UUT. Alternatively, the described methods and systems may be specifically tailored to operate with an FMCW LiDAR UUT, or they may be adapted such that a single simulator system can operate with both ToF and FMCW LiDAR UUTs.

[0132] Figure 14 The various aspects of the method can be implemented by a simulator system (e.g., those systems shown and described in the figures above), or more generally, by combining, as needed, any of the computer circuit systems, systems, devices, elements, or components shown in the figures above. For example, the processor (and / or other hardware) of such a device can be configured to cause the device to perform any combination of the illustrated method elements and / or other method elements.

[0133] It should be noted that, although Figure 14 At least some elements of the method are described in a manner relating to the use of techniques and / or features associated with a particular LiDAR method, but such description is not intended to limit this disclosure, and may be used as needed. Figure 14 Various aspects of the method can be used in any suitable LiDAR system. In various embodiments, some elements of the illustrated method may be executed concurrently in a different order than shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be executed as needed. As shown in the figure, Figure 14 The method can be operated as follows.

[0134] At 1402, multiple optical processing chains receive multiple laser pulses from one or more lasers of the LiDAR UUT. Each optical processing chain includes an optical fiber configured to receive a different subset of the multiple laser pulses. In some embodiments, each different subset of the multiple laser pulses includes laser pulses from different lasers of the LiDAR UUT, and each laser of the LiDAR UUT scans a different portion of the LiDAR UUT's field of view. In some embodiments, each of the multiple lasers scans a single field line of the LiDAR UUT, and a lens system is configured to focus the light received along each line to a corresponding point. For example, each laser may scan horizontally along the line, and the lens system may focus each line to a point for reception by the corresponding optical fiber. Thus, each optical fiber can receive a non-intersecting set of laser pulses from the corresponding laser of the LiDAR UUT.

[0135] At 1404, the received laser pulse is modulated by each of a plurality of optical processing chains. Modulation of the received laser pulse may include implementing one or more of in-phase quadrature (IQ) frequency modulation, optical time delay, and / or optical amplitude modulation. IQ frequency modulation may involve frequency shifting or translation of the received laser pulse. Implementing IQ frequency conversion may be used to simulate the Doppler frequency shift and / or time delay of the FMCW LiDAR UUT. Implementing optical time delay may be used to simulate the time of flight of objects in a simulated aerial environment of the ToF LiDARUUT. Implementing optical amplitude modulation may include selectively attenuating and / or amplifying the received laser pulse to simulate reflectivity and path loss at the simulated location in the aerial environment. The optical amplitude modulator may include separate optical attenuator and amplifier devices, or they may be combined into a single attenuator / amplifier device for each optical chain. Modulation of the received laser pulse is performed to simulate the aerial environment. Modulation of the received laser pulse may be performed optically to maintain coherence between the received laser pulse and the modulated laser pulse transmitted back to the LiDAR UUT. Multiple optical processing chains can concurrently modulate the laser pulses they each receive.

[0136] In some embodiments, the simulator system is customized specifically for operation with a ToF LiDAR UUT. In these embodiments, the optical processing chain may include an optical time delay unit and an optical amplitude modulator, but they may exclude an IQ frequency modulator because ToF LiDAR does not use frequency shift information. Alternatively, in other embodiments, the simulator system may be customized specifically for operation with an FMCW LiDAR UUT. In these embodiments, the optical processing chain may include an IQ frequency modulator and an optical amplitude modulator, but they may exclude an optical time delay unit. For these embodiments, an IQ frequency converter can be used to simulate Doppler frequency shift and time delay, eliminating the need for a separate time delay device. For example, for FMCW LiDAR, multiple laser pulses each include a linear frequency upscan and a subsequent linear frequency downscan. Implementing IQ frequency modulation may involve shifting the linear frequency upscan in the same direction as the linear frequency downscan to simulate Doppler frequency shift in an airborne environment, and shifting the linear frequency upscan in the opposite direction as a linear frequency downscan to simulate time delay in an airborne environment.

[0137] Alternatively, in some embodiments, the simulator system may include all three in each optical processing chain: an IQ frequency modulator, an optical time delay unit, and an optical amplitude modulator. In these embodiments, the simulator system can be programmed to simulate the airborne environment of both the ToF LiDAR UUT and the FMCW LiDAR UUT. For example, the simulator system may not activate the IQ frequency modulator when simulating the ToF LiDAR UUT, and may not activate the optical time delay unit when simulating the FMCW LiDAR UUT.

[0138] In some embodiments, the simulator system receives frequency modulation (FM), time delay, and / or amplitude modulation (AM) values ​​from a LiDAR image generator for each point in a point cloud of an aerial environment. The LiDAR image generator may be a processor-executable software program stored on a non-transitory memory medium. The LiDAR image generator may be user-programmable to generate time delay and AM values ​​corresponding to different aerial environments. In these embodiments, IQ frequency modulation, optical time delay, and / or optical amplitude modulation are implemented based on the FM, time delay, and / or AM values, respectively.

[0139] At position 1406, the modulated laser pulse is transmitted to the LiDAR UUT. The modulated laser pulses can be transmitted to the LiDAR UUT via the same lens system used to receive laser pulses from the LiDAR UUT, or they can be transmitted via separate dedicated output lens systems. For example, each fiber can be configured to transmit the modulated laser back through the lens system for reception by the LiDAR UUT. The LiDAR UUT can then reconstruct the LiDAR image based on the received modulated laser.

[0140] Figure 15 –Flowchart of the Flash LiDAR Environment Simulator

[0141] Figure 15 This is a flowchart illustrating a method for simulating an aerial environment for a flash LiDAR UUT according to some embodiments. The simulator system may include a processor coupled to a non-transitory memory medium, wherein the processor is configured to direct the operation of the simulator system. The simulator system may also include one or more optical detectors and a 2D diode array or another type of 2D light-emitting array. While the embodiments herein describe simulator systems utilizing diode or LED arrays, it is understood that any other type of 2D light-emitting array may also be used and is within the scope of some embodiments. In some embodiments, the described methods and systems may be specifically tailored to operate with a flash LiDAR UUT.

[0142] Figure 15 The various aspects of the method can be implemented by a simulator system (e.g., those systems shown and described in the figures herein), or more generally, by combining as needed any of the computer circuit systems, systems, devices, elements, or components shown in the figures above. For example, the processor (and / or other hardware) of such a device can be configured to cause the device to perform any combination of the illustrated method elements and / or other method elements.

[0143] It should be noted that, although Figure 15 At least some elements of the method are described in a manner relating to the use of techniques and / or features associated with a particular LiDAR method, but such description is not intended to limit this disclosure, and may be used as needed. Figure 15 Various aspects of the method can be used in any suitable LiDAR system. In various embodiments, some elements of the illustrated method may be executed concurrently in a different order than shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be executed as needed. As shown in the figure, Figure 15 The method can be operated as follows.

[0144] At 1506, one or more optical detectors receive light from the flash LiDAR UUT.

[0145] In some embodiments, the flash LiDAR UUT is a multi-flash LiDAR device including multiple lasers that generate multiple corresponding flashes, wherein each laser flashes in a different sub-region of the field of view (FoV) of the flash LiDAR UUT. In these embodiments, the simulator system may include multiple optical detectors, wherein each of the multiple optical detectors is configured to receive flashes from different lasers of the multi-flash LiDAR UUT.

[0146] At 1502, a processor coupled to a non-transitory computer-readable storage medium generates point cloud information. The point cloud information can be generated based on an image of the scene to be simulated or on a video containing a sequence of frames of the scene to be simulated. An image or image sequence can be converted into point cloud information, which includes distance, reflectivity, and / or rate values ​​for each of a plurality of angular locations (i.e., a set of angles (φ, θ) spanning the field of view of the image at a specific resolution).

[0147] At position 1504, the point cloud information is converted into delay and amplitude values ​​for each point in the 2D array. In some embodiments, such as Figure 12 As shown, the delay and amplitude values ​​are encoded as multiple matrices corresponding to a simulated airborne environment, where each of the multiple matrices corresponds to a different simulated time delay, and each entry in each of the multiple matrices specifies the amplitude of a pixel in a two-dimensional (2D) light-emitting diode (LED) array. For example, each matrix could represent an intensity map of the pixels of the 2D LED array. Alternatively, in other embodiments, the delay and amplitude values ​​are encoded as a simulated flash point cloud specifying the intensity and / or delay of each pixel in the 2D LED array, such as... Figure 13 As shown in the image.

[0148] In some embodiments, a non-transitory computer-readable storage medium stores point cloud information thereon, which is generated in user-programmable software for configuring a simulated aerial environment. The simulated aerial environment can specify the position (e.g., x, y, and z coordinates) and reflectivity for each point in the point cloud, and the generation of the point cloud information can be performed by point cloud software based on the position and reflectivity of each point in the point cloud.

[0149] In some embodiments, software can be executed to determine the appropriate delay and amplitude values ​​for each point in the field of view corresponding to the point cloud information of the simulated aerial environment. In some embodiments, the delay and amplitude values ​​are stored as a series of 2D matrices, where entries in the matrices correspond to the amplitude of light at different points in the field of view, and different matrices each correspond to different time delays. In these embodiments, as described below, a series of matrices can be sequentially provided to a 2D emitting array so that the emitting array emits light sequentially according to the amplitude values ​​and time delays.

[0150] Alternatively, the delay and amplitude values ​​can be organized according to their individual pixels; that is, each pixel can have a corresponding delay and amplitude value, and these can be provided to a separate timing element for each pixel so that the pixel emits light according to its respective delay and amplitude value. These embodiments have the advantage of using a smaller data footprint for the delay and amplitude values ​​compared to embodiments using a sequence matrix as described above. For example, representing the delay and amplitude values ​​as a series of matrices typically introduces a large number of empty entries. However, the advantage of the sequence matrix representation is that a single timing element is used for the 2D diode array, rather than assigning a separate timing element to each pixel.

[0151] At position 1508, the delay and amplitude values ​​are received by the simulator system. The simulator system can provide signals to the 2D diode array to cause the array to emit light according to the delay and amplitude values. The 2D diode array can be a light-emitting diode (LED) array or other types of light-emitting arrays for controllably emitting multiple beams. For a simulator system configured to simulate a multi-flash LiDARUUT environment, a portion of the converted point cloud information can be provided separately to the 2D diode array in response to each of the multiple flashes received. For example, each received flash can trigger the processor to provide point cloud information corresponding to a sub-region of the FoV illuminated by the received flash.

[0152] In some embodiments, providing point cloud information includes the processor sequentially providing matrices from a plurality of matrices to a 2D diode array. In some embodiments, the matrices from the plurality of matrices are periodically provided to the 2D diode array at a predetermined period, wherein the 2D diode array emits light toward the flash LiDAR UUT at the predetermined period, and wherein the predetermined period corresponds to the depth resolution of the simulated aerial environment (e.g., see...). Figure 12 Each matrix received by the 2D diode array can trigger the diode array to emit light according to the intensity specified by the matrix, as described below.

[0153] Alternatively, in some embodiments, the processor is coupled to multiple timing elements, and each timing element is coupled to a pixel of a 2D diode array. In these embodiments, the processor may send intensity and timing information of a specific pixel coupled to the corresponding timing element to each timing element (e.g., see...). Figure 13 Then, the timing element can transmit intensity information to its coupled pixel based on the timing information. For example, each timing element can individually instruct its coupled pixel to emit a pulse sequence based on the intensity and timing information.

[0154] In some embodiments, the timing for providing point cloud information to the 2D diode array is selected to simulate the round-trip time of the simulated aerial environment.

[0155] In some embodiments, a synchronization clock can be used to synchronize one or more optical devices that receive light from a flashing LiDAR UUT with a processor that provides matrices from a plurality of matrices to a 2D diode array.

[0156] At 1510, in response to receiving delay and amplitude values, the 2D diode array emits a series of light pulses to the flash LiDAR UUT via a lens system. For example, when the point cloud information is a series of matrices, each matrix can trigger the 2D diode array to emit light according to the intensity pattern indicated by the matrix. The 2D diode array can receive the matrix sequence and emit light sequentially according to the indicated pattern. Alternatively, the delay and amplitude values ​​can be directly provided to multiple timing elements, each coupled to a different pixel of the 2D diode array, and the timing elements can use the delay and amplitude values ​​corresponding to their respective pixels to cause the pixels to emit light according to the delay and amplitude values. In response to receiving light from the flash LiDAR UUT, the light emitted by the 2D diode array simulates the light emitted by the simulated aerial environment. The flash LiDAR can use the light received from the 2D diode array to generate LiDAR images for testing or other purposes.

[0157] Additional Examples

[0158] The following are examples of additional aspects of the embodiments described:

[0159] Figure 6 The diagram illustrates a parallel point cloud simulator, versatile enough to work with all LiDAR types, including TOF, FMCW, and Flash. This parallel point cloud simulator can include high integration; while expensive, it may become more economical in the future.

[0160] Figures 8A-8B The point cloud simulator of the scanning pulse system shown can be used for both FMCW and TOF. This point cloud simulator can utilize an optical shutter array. Other advantages of this system include coupling a photodetector array to an optical shutter array that maps the photodetector array to the optical shutter in various ways.

[0161] Optical IQ modulators can be derived from Figures 8A-8B Removed from the parallel point cloud simulator shown, so that it can be used exclusively for the TOFLiDAR system.

[0162] In various embodiments, optical IQ modulators and / or electro-optical PLLs (EOPLLs) can be used for frequency shifting.

[0163] Different frequency shifts can be used to adjust the upslope and downslope of a linear frequency shift pulse to simulate both distance and Doppler frequency shifts. This allows for the manipulation of both linear and Doppler frequency shifts. Figures 8A-8B The delay generator was removed from the parallel point cloud simulator shown to reduce the cost of scene simulation for the FMCWLiDAR system.

[0164] One embodiment relates to a method for generating point clouds. The method for generating point clouds can receive a scene description in the form of a list of points and descriptors, photographs, video files, and / or mathematical formulas, and can generate information about the point cloud. The point cloud information may include: the vertical angle, horizontal angle, distance, velocity, and reflectivity of each point in the point cloud. The method for generating point clouds allows the introduction of LiDAR attenuation, such as dust, snow, rain, sunlight, light from other LiDAR sources, etc.

[0165] Another embodiment relates to a method for converting a point cloud into an array of vertical and horizontal angles, distances, reflectivities, and Doppler shifts. The method for converting a point cloud into LiDAR parameters may include: 1) representing velocity as an appropriate Doppler shift of the wavelength of light used; 2) representing distance as an appropriate delay; 3) representing reflectivity as an appropriate gain or attenuation for any given distance; and 4) representing vertical and horizontal angles as positions on a grid of light emitters or shutters.

[0166] Therefore, these embodiments can be operated to convert elements of a scene into hardware parameters that can be used to simulate the scene. These hardware parameters can then be used in the LiDAR simulator described herein to simulate the scene.

[0167] Another embodiment relates to a combined system configured to perform LiDAR scene simulation and laser measurements. For example, the system described herein may also include a delay line discriminator, an optical phase-locked loop (PLL), an optical demodulator, etc., to measure chirp linearity. Another embodiment relates to a method for measuring laser linewidth (an optical equivalent of jitter or phase noise), optical power measurement, or pulse width measurement, and other possibilities. Examples of this method include using an optical PLL, a delay line discriminator, and a spectral analyzer. In these embodiments, the same simulator system used to simulate an aerial environment may also be configured to perform these measurements on light received from a LiDAR system. In other words, a single system can be configured to perform both LiDAR scene simulation and LiDAR optical measurements. Some components of the system may be shared and used for both scene simulation and optical measurements; these components include lens systems, optical fibers, and / or one or more interfaces for powering, controlling, and receiving data from the LiDAR unit. The system may also include additional components for performing optical measurements. Chirp linearity and laser linewidth can be used to evaluate whether the received light is a suitable candidate for the LiDAR simulation described in this paper.

[0168] In some embodiments, a system for simulating an aerial environment for testing a LiDAR (Light Detection and Ranging) unit under test is described. The system includes a lens system configured to receive light from the LiDAR unit under test, and multiple optical processing chains coupled to the lens system. Each optical processing chain includes at least one optical fiber coupled to the input lens system and configured to provide an optical signal corresponding to the received light; a frequency shift simulator coupled to the multiple optical fibers, wherein the frequency shift simulator is configured to generate a frequency shift in the received optical signal; a selectable optical delay device coupled to the frequency shift estimator and configured to selectively delay the optical signal to simulate round-trip delay of reflected light; and / or at least one optical attenuator / amplifier configured to control the amplitude of the optical signal to simulate different levels of path loss, polarization variation and reflectivity from free space, spectral components of reflection, and / or diffuse components of reflection. Each optical processing chain is configured to output the processed optical signal through the lens system to the LiDAR unit under test. Alternatively, in some embodiments, each optical processing chain is configured to output a processed optical signal to the LiDAR UUT via an output lens system (different from the lens system used to receive light from the LiDAR UUT) coupled to the output lens system of each optical processing chain in the optical processing chain, and is configured to generate light in free space based on the optical signal processed by each optical processing chain.

[0169] In various embodiments, the frequency shift simulator includes an optical IQ modulator or an optical phase-locked loop.

[0170] In some embodiments, in each optical processing chain, at least one optical attenuator / amplifier is configured to selectively attenuate or amplify the optical signal so that the light intensity output by the system corresponds to the reflectivity and path loss at the location of the simulated object.

[0171] In some embodiments, the system is configured to optically process the received light to maintain coherence with the light received from the LiDAR unit under test.

[0172] In some embodiments, the system is configured to process all points in a LiDAR image simultaneously.

[0173] In some embodiments, the system further includes a LiDAR image generator coupled to a frequency-shift simulator, a selectable optical delay, and at least one optical attenuator / amplifier. The LiDAR image generator is user-programmable to control the operation of the frequency-shift simulator, the selectable optical delay, and at least one optical attenuator / amplifier.

[0174] In some embodiments, the LiDAR image generator is configured to provide frequency shift values ​​to the frequency shift simulator for use by the frequency shift simulator when creating a frequency offset in the received optical signal.

[0175] In some embodiments, the LiDAR image generator is configured to provide a delay value to a selectable optical delayer for use in delaying an optical signal to simulate the round-trip delay of reflected light.

[0176] In some embodiments, the LiDAR image generator is configured to provide an amplitude value to at least one optical attenuator / amplifier for use by the optical attenuator / amplifier to control the amplitude of the optical signal to simulate different levels of path loss from free space, polarization variation and reflectivity, spectral components of reflection and / or diffuse reflection components of reflection.

[0177] In some embodiments, the LiDAR image generator is configured to provide frequency shift, delay, and amplitude values ​​for each point in the point cloud generated by the system.

[0178] In some embodiments, the frequency shift simulator is configured to use different frequency shifts for the upslope and downslope to simulate both distance and Doppler frequency shift.

[0179] In some embodiments, a system for simulating an aerial environment used for testing a LiDAR UUT is described. The system includes: an input lens system configured to receive light from the LiDAR UUT; an input beam splitter coupled to the input lens system and configured to receive an optical signal and provide a portion of the optical signal to a first optical processing path and a second optical processing path; and at least one optical shutter array coupled to the first and second optical processing paths. Alternatively, in some embodiments, the optical shutter array is removed and the lens system is used to receive light from the LiDAR UUT and output processed light back to the LiDAR UUT. The first optical processing path includes a photodetector array for determining the angle of a laser pulse at a specific moment, wherein the position of the light received on the photodetector array is used to open a corresponding element in the optical shutter array. The second optical processing path includes an amplitude controller configured to control the amplitude of the optical signal to simulate different levels of reflectivity and path loss, and a LiDAR image generator coupled to the amplitude controller. The second optical processing path is configured to provide an attenuation signal to at least one optical shutter array or lens system to exit through one or more opening elements in the optical shutter array or through the lens system.

[0180] In some embodiments, the position of the received light on the photodetector array corresponds to the vertical and horizontal scan angles (φ, θ), where the vertical and horizontal scan angles are used to open the corresponding elements in the optical shutter array.

[0181] In some embodiments, the second optical processing path further includes a frequency shifter coupled to a selectable optical delay element, wherein the frequency shifter is configured to generate a frequency shift in the received optical signal. In some embodiments, the second optical processing path is configured to provide a frequency-shifted and attenuated signal to at least one optical shutter array or lens system for exiting through one or more opening elements in the lens system or optical shutter array.

[0182] In some embodiments, the second optical processing path further includes a selectable optical delay element coupled to the frequency shifter, wherein the selectable optical delay element is configured to selectively delay the optical signal to simulate the round-trip delay of reflected light. The second optical processing path is configured to provide a delayed and attenuated signal to at least one optical shutter array or lens system to exit through one or more opening elements in the lens system or optical shutter array.

[0183] In some embodiments, the second optical processing path further includes a frequency shifter coupled to an optional optical delay element, wherein the frequency shifter is configured to generate a frequency shift in the received optical signal; the optional optical delay element is coupled to the frequency shifter, wherein the optional optical delay element is configured to selectively delay the optical signal to simulate the round-trip delay of reflected light. The second optical processing path is configured to provide a delayed, frequency-shifted, and attenuated signal to at least one optical shutter array or lens system to exit through one or more opening elements in the lens system or optical shutter array.

[0184] In some embodiments, each photodetector in the photodetector array has a one-to-one mapping to a corresponding shutter in the optical shutter array.

[0185] In some embodiments, each of the multiple photodetectors in the photodetector array has a many-to-one mapping to a corresponding shutter in the optical shutter array.

[0186] In some embodiments, a system for simulating an aerial environment used for testing a LiDAR UUT is described. The system includes: an input lens system configured to receive light from the LiDAR UUT; an input beam splitter coupled to the input lens system and configured to receive an optical signal and provide a portion of the optical signal to a first optical processing path and a second optical processing path; and at least one optical shutter array coupled to the first and second optical processing paths. The first optical processing path includes a photodetector array for determining the angle (φ, θ) of a laser pulse at a specific moment, wherein the position of the light received on the photodetector array is used to open a corresponding element in the optical shutter array. The second optical processing path includes: a selectable optical delay element coupled to a frequency shifter and configured to selectively delay the optical signal to simulate the round-trip delay of reflected light; an amplitude controller coupled to the selectable optical delay element to control the amplitude of the optical signal to simulate different levels of reflectivity and path loss; and a LiDAR image generator coupled to the selectable optical delay element and the amplitude controller. The second optical processing path is configured to provide a delayed, Doppler-shifted, and attenuated signal to at least one optical shutter array for exiting through one or more opening elements in the optical shutter array.

[0187] In some embodiments, a method for converting a scene description into LiDAR parameters is described. The method includes receiving a scene description in the form of two or more of points and descriptors, photographs, video files, and / or mathematical formulas; and generating point cloud information based on the received description. The point cloud information includes vertical angle, horizontal angle, distance, velocity, and reflectivity. The method of generating the point cloud allows LiDAR attenuation to be incorporated into the simulation. The method also includes converting the point cloud into LiDAR parameters, wherein the LiDAR parameters include an array of vertical and horizontal angles, distance, reflectivity, and Doppler shift.

[0188] In some embodiments, a method for converting a point cloud into LiDAR parameters may include: 1) representing the velocity as an appropriate Doppler shift of the wavelength of light used; 2) representing the distance as an appropriate delay; 3) representing the reflectivity as an appropriate gain or attenuation for any given distance; and 4) representing the vertical and horizontal angles as positions on a grid of light emitters or shutters.

[0189] The following numbered paragraphs describe other embodiments.

[0190] In some embodiments, a method for simulating an airborne environment for testing a LiDAR (LiDAR) unit under test (UUT) is described, the method comprising: receiving multiple laser pulses from one or more lasers of the LiDAR UUT by a plurality of optical processing chains, wherein each optical processing chain includes an optical fiber configured to receive a different subset of the multiple laser pulses; for each optical processing chain, modulating the received laser pulses by performing optical time delay and optical amplitude modulation; and transmitting the modulated laser pulses to the LiDAR UUT.

[0191] In some embodiments, the received laser pulses are modulated to simulate an aerial environment.

[0192] In some embodiments, the LiDAR UUT includes a Time-of-Flight (ToF) LiDAR UUT.

[0193] In some embodiments, an optical time delay is implemented to simulate the flight time of an object in the simulated aerial environment.

[0194] In some embodiments, each different subset of the multiple laser pulses includes laser pulses from different lasers of the LiDAR UUT, and each laser of the LiDAR UUT scans a different portion of the LiDAR UUT's field of view.

[0195] In some embodiments, optical amplitude modulation includes selectively attenuating and / or amplifying the received laser pulse to simulate reflectivity and path loss at a simulated location in an aerial environment.

[0196] In some embodiments, the received laser pulses are optically modulated to maintain coherence between the received laser pulses and the modulated laser pulses.

[0197] In some embodiments, multiple optical processing chains concurrently modulate the laser pulses they each receive.

[0198] In some embodiments, the method further includes receiving frequency modulation (FM) and amplitude modulation (AM) values ​​from a LiDAR image generator for each point in a point cloud of an aerial environment, wherein the implementation of optical time delay and optical amplitude modulation is performed based on the FM and AM values.

[0199] In some embodiments, multiple laser pulses are received from the LiDAR UUT, and the modulated laser pulses are transmitted to the LiDAR UUT through a lens system.

[0200] In some embodiments, a system for simulating an aerial environment for testing a LiDAR (Light Detection and Ranging) Unit under Test (UUT) includes a lens system configured to receive light from the LiDAR UUT and multiple optical processing chains coupled to the lens system. Each optical processing chain includes an optical fiber coupled to the lens system and configured to receive laser pulses from the LiDAR UUT through the lens system; a selectable optical delay device configured to selectively delay the received laser pulses; and an optical amplitude modulator configured to modulate the amplitude of the received laser pulses. Each optical processing chain is configured to transmit selectively delayed and amplitude-modulated laser pulses to the LiDAR UUT.

[0201] In some embodiments, the system is also configured to perform one or more measurements on the light received from the LiDAR UUT, wherein the one or more measurements include one or more of the following: laser linewidth measurement, chirp linearity measurement, spectral analyzer measurement, optical power measurement, and pulse width measurement.

[0202] In some embodiments, the LiDAR UUT includes a Time-of-Flight (ToF) LiDAR UUT.

[0203] In some embodiments, each of the plurality of optical processing chains further includes an in-phase quadrature (IQ) frequency modulator configured to modulate the frequency of the received laser pulses, wherein the system is configured to simulate the air environment of a time-of-flight (ToF) LiDAR UUT or a frequency-modulated continuous wave (FMCW) LiDAR UUT, wherein an optical delay device is selected for simulating the air environment of the ToF LiDAR UUT, and wherein the IQ frequency modulator is used to simulate the air environment of the FMCW LiDAR UUT.

[0204] In some embodiments, each optical fiber receives a different subset of laser pulses received from different lasers among a plurality of lasers in the LiDAR UUT, and each of the plurality of lasers scans a different portion of the LiDAR UUT's field of view.

[0205] In some embodiments, each of the plurality of lasers scans a single line of the LiDAR UUT's field of view, and the lens system is configured to focus the light received along each line onto the corresponding point.

[0206] In some embodiments, modulating the amplitude of the received laser pulse includes selectively attenuating and / or amplifying the received laser pulse to simulate reflectivity and path loss at a simulated location in an aerial environment.

[0207] In some embodiments, selective delay of the received laser pulse and modulation of the amplitude of the received laser pulse are optically performed to maintain coherence between the received laser pulse and the modulated laser pulse.

[0208] In some embodiments, the system further includes a LiDAR image generator coupled to a plurality of optical processing chains, wherein the LiDAR image generator is configured to provide time delay and amplitude modulation values ​​to the plurality of optical processing chains for each point in a point cloud of an aerial environment, wherein the LiDAR image generator is user-programmable to generate time delay and amplitude modulation values ​​corresponding to different aerial environments, and wherein selectively delaying received laser pulses and modulating the amplitude of received laser pulses are performed based on the time delay and amplitude modulation values.

[0209] In some embodiments, frequency-shifted and amplitude-modulated laser pulses are transmitted to the LiDAR UUT via a lens system.

[0210] In some embodiments, a system for simulating an airborne environment for testing a Flash Detection and Ranging (LiDAR) Unit under Test (UUT) includes a processor coupled to a non-transitory computer-readable storage medium, one or more optical detectors, and a two-dimensional (2D) light-emitting array. The 2D light-emitting array may be a 2D light-emitting diode (LED) array. The system is configured to receive light from the flash LiDAR UUT via one or more optical detectors; generate multiple matrices corresponding to the simulated airborne environment by the processor, wherein each matrix of the multiple matrices corresponds to a different simulation time delay, wherein each entry in each of the multiple matrices specifies a pixel amplitude of the 2D light-emitting array; and, in response to the light received by the one or more optical detectors, sequentially provide matrices from the multiple matrices to the 2D light-emitting array, wherein each provided matrix causes the 2D light-emitting array to emit light toward the flash LiDAR UUT through a lens according to a specified amplitude.

[0211] In some embodiments, the light emitted by the 2D light-emitting array is simulated as light emitted by the simulated air environment in response to receiving light from the flashing LiDAR UUT.

[0212] In some embodiments, the flash LiDAR UUT includes a multi-flash LiDAR device, the light from the flash LiDAR UUT includes multiple flashes from different corresponding lasers of the multi-flash LiDAR device in different regions of the field of view of the flash LiDAR UUT, and one or more optical detectors include multiple optical detectors, wherein each of the multiple optical detectors is configured to receive different flashes among the multiple flashes.

[0213] In some embodiments, in response to receiving each of a plurality of flashes, the matrix of a plurality of matrices is sequentially provided to the 2D emitting array individually.

[0214] In some embodiments, a matrix of a plurality of matrices is periodically provided to a 2D emitting array at a predetermined period, wherein the 2D emitting array emits light toward the flash LiDAR UUT at a predetermined period, and wherein the predetermined period corresponds to the depth resolution of the simulated aerial environment.

[0215] In some embodiments, the system is also configured to perform one or more measurements on the light received from the LiDAR UUT, wherein the one or more measurements include one or more of the following: laser linewidth measurement, chirp linearity measurement, spectral analyzer measurement, optical power measurement, and pulse width measurement.

[0216] In some embodiments, the system further includes point cloud software stored on a non-transitory computer-readable storage medium, wherein the point cloud software is executable by a processor, wherein the point cloud software is user-programmable to configure a simulated aerial environment, wherein the simulated aerial environment includes the position and reflectivity of each point in the point cloud, and wherein the point cloud software is configured to generate a plurality of matrices based on the position and reflectivity of each point in the point cloud.

[0217] In some embodiments, the system further includes a synchronization clock configured to synchronize one or more optical devices receiving light from the flash LiDAR UUT with a processor that provides matrices from a plurality of matrices to a 2D light-emitting array.

[0218] In some embodiments, the system is also configured to select the timing for feeding the matrix to the 2D luminescent array to simulate the round-trip time of the simulated aerial environment.

[0219] While the embodiments described above have been described in considerable detail, many variations and modifications will become apparent to those skilled in the art once the foregoing disclosure is fully understood. The following claims are intended to be construed as encompassing all such variations and modifications.

Claims

1. A system for simulating an airborne environment for testing a LiDAR (LiDAR) unit under test (UUT), the system comprising: The lens system is configured to receive light from the LiDAR UUT; Multiple optical processing chains are coupled to the lens system, wherein each optical processing chain includes: An optical fiber is coupled to the lens system and configured to receive laser pulses from the LiDAR UUT through the lens system; An in-phase quadrature (IQ) frequency modulator is configured to modulate the frequency of the received laser pulse; An optical time delay unit is configured to time-delay a received laser pulse; and An optical amplitude modulator is configured to modulate the amplitude of the received laser pulse. Each optical processing chain is configured to transmit frequency-shifted, time-delayed, and amplitude-modulated laser pulses to the LiDARUUT, wherein the frequency-shifted, time-delayed, and amplitude-modulated laser pulses simulate the aerial environment.

2. The system of claim 1, wherein the system is further configured to: Perform one or more measurements on the light received from the LiDAR UUT, wherein the one or more measurements include one or more of the following: Laser linewidth measurement; Chirp linearity measurement; Spectrometer measurement; Optical power measurement; and Pulse width measurement.

3. The system as described in claim 1, The LiDAR UUT mentioned therein includes a Frequency Modulated Continuous Wave (FMCW) LiDAR UUT.

4. The system as described in claim 1, The received laser pulses consist of a linear frequency up-scan followed by a linear frequency down-scan. The frequencies of the received laser pulses modulated include: The linear frequency is shifted upward in the same direction as the downward sweep at the linear frequency to simulate the Doppler shift in the air environment.

5. The system as described in claim 1, Each optical fiber receives a different subset of laser pulses from different lasers among the multiple lasers in the LiDAR UUT. Each of the plurality of lasers scans a different portion of the field of view of the LiDAR UUT.

6. The system as described in claim 5, Each of the plurality of lasers scans a single line of the field of view of the LiDAR UUT, and The lens system is configured to focus light received along each line to a corresponding point.

7. The system as described in claim 1, The amplitude of the received laser pulse is modulated by selectively attenuating and / or amplifying the received laser pulse to simulate reflectivity and path loss at a simulated location in an aerial environment.

8. The system as described in claim 1, The received laser pulse is optically delayed and its frequency and amplitude are modulated to maintain coherence between the received laser pulse and the modulated laser pulse.

9. The system as described in claim 1, The plurality of optical processing chains concurrently modulate the laser pulses they each receive.

10. The system of claim 1, further comprising: A LiDAR image generator, coupled to the plurality of optical processing chains, wherein the LiDAR image generator is configured to provide frequency modulation, time delay, and amplitude modulation values ​​to the plurality of optical processing chains for each point in a point cloud of an aerial environment. The LiDAR image generator is user-programmable to generate frequency modulation (FM), time delay (TDM), and amplitude modulation (AM) values ​​corresponding to different aerial environments. The frequency and amplitude of the delayed and modulated laser pulses are determined based on the frequency modulation value, time delay value, and amplitude modulation value.

11. The system as described in claim 1, The frequency-shifted, time-delayed, and amplitude-modulated laser pulses are transmitted to the LiDAR UUT through the lens system.

12. A non-transitory computer-readable storage medium comprising program instructions that, when executed by a processor, direct the operation of a system as claimed in any one of claims 1-11.

13. A method for operating the system as claimed in any one of claims 1-11.

14. A method for simulating an aerial environment for testing a LiDAR (LiDAR) unit under test (UUT), the method comprising: Multiple laser pulses from one or more lasers of the LiDAR UUT are received by multiple optical processing chains, wherein each optical processing chain includes an optical fiber configured to receive a different subset of the multiple laser pulses; For each optical processing chain, the received laser pulse is modulated to simulate the aerial environment by implementing the following operations: In-phase quadrature (IQ) frequency modulation; and Optical amplitude modulation; as well as The modulated laser pulse is transmitted to the LiDAR UUT.

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