Patent Description:
LiDAR systems (Light Detection and Ranging systems, also referred to as LIDAR or Lidar systems) are widely used in self-driving (autonomous) vehicles. LiDAR systems allow measurement of distances between the system and surrounding objects by irradiating the surroundings with light and collecting light reflected from one or more objects in the surroundings.

In a typical time of flight (ToF) LiDAR system, a light source emits a plurality of pulsed narrow laser beams across a field of view. Light reflected and/or scattered from an object in the field of view is received by a detection unit of the LiDAR system to determine a position of the object. For ToF systems, time between (i) emission of the light beam and (ii) detection of the scattered light beam is measured to determine the distance to the object.

The reflected beams received by the LiDAR are processed to generate data points using a central computer, each pulse of the beam mapping to one data point in a point cloud representing the surrounding environment as a 3D map. As the 3D map is more or less detailed and accurate depending on the density or refresh rate of the point cloud, generally speaking, the greater the sampling rate over the field of view, the more detailed and accurate is the 3D map.

The frequency of pulses emitted by the LiDAR system, and thus the number of points, is however generally limited by several factors. For some LiDAR laser sources, for example, there can be a limit to the emission frequency (maximum pulse frequency) beyond which the laser source can experience a power slump. In such a case, the light pulses emitted by the laser have less power and therefore the received reflected light correspondingly have lower power. For objects that reflect weakly, for example, lower power laser pulses may not be sufficient to have an adequate signal to create the 3D map. <CIT>, discloses a system and method including scanning a light detection and ranging (LIDAR) device through a range of orientations corresponding to a scanning zone while emitting light pulses from the LIDAR device. The method also includes receiving returning light pulses corresponding to the light pulses emitted from the LIDAR device and determining initial point cloud data based on time delays between emitting the light pulses and receiving the corresponding returning light pulses and the orientations of the LIDAR device. The method includes identifying, based on the initial point cloud data, a reflective feature in the scanning zone and determining an enhancement region and an enhanced angular resolution for a subsequent scan to provide a higher spatial resolution in at least a portion of subsequent point cloud data from the subsequent scan corresponding to the reflective feature. <CIT>, discloses a laser system including a seed laser configured to produce a sequence of seed light pulses, wherein the sequence of seed light pulses are produced with variable time intervals in a sweep cycle; a pump laser configured to produce pump light having variable amplitude in the sweep cycle; and a control unit configured to generate a command to the pump laser to synchronize the pump light with the sequence of seed light pulses. <CIT>, discloses methods and systems for performing three-dimensional LIDAR measurements with different illumination intensity patterns. Repetitive sequences of measurement pulses each having different illumination intensity patterns are emitted from a LIDAR system. One or more pulses of each repetitive sequence have a different illumination intensity than another pulse within the sequence. The illumination intensity patterns are varied to reduce total energy consumption and heat generated by the LIDAR system. In some examples, the illumination intensity pattern is varied based on the orientation of the LIDAR device. In some examples, the illumination intensity pattern is varied based on the distance between a detected object and the LIDAR device.

Therefore, there is a need for systems and methods which avoid, reduce or overcome the limitations of the prior art.

The inventors of the present technology have recognized certain solutions for avoiding, reducing, and/or overcoming at least come limitations of the prior art.

In accordance with a broad aspect of the present technology, there is proposed a time-of-flight LiDAR system with several scanning modes for optimizing scanning frequency or density of the objects producing strong signals. According to non-limiting embodiments or implementations of the present technology, the LiDAR system includes a light source composed of a laser source coupled to a fiber amplifier. In some cases, the fiber amplifier is a doped fiber amplifier, and in some cases an erbium doped fiber amplifier (EDFA). For the case of a LiDAR system implementing the EDFA, for example, pulses emitted by the laser source are amplified by excited erbium ions in the fiber core. After the resulting laser beam pulse is emitted from the LiDAR system, some time is required to re-charge the light source, the time being determined by a population inversion rate in the doped fiber amplifier. As such, at a pulse frequency (i.e. the rate at which the pulses are emitted) that is faster than the recharge (population inversion) rate, the pulses emitted from the light source experience a power slump due to incomplete recharge of the amplifier.

In accordance to the non-limiting embodiments of the present technology, the signal-to-noise ratio (SNR) is determined, for one or more regions of the field of view of the system, and compared to a pre-determined signal-to-noise threshold in order to control the LiDAR system in one of a plurality of scanning modes. For regions of the field of view that have SNRs above the threshold, the pulse frequency of an output beam can be increased in order to produce a more spatially detailed (or more quickly refreshed) 3D map of that region. By the present technology, the pulse frequency can be increased beyond the population inversion rate of the doped fiber amplifier when the SNR is above the threshold. As such, the identified region is more frequently sampled, albeit with a lower power light pulse due to the emission before the amplifier has completed population inversion. As the lower power light pulse is directed only to regions with sufficiently high SNR at the original power, these regions are expected to still produce adequate signal quality at the lower power. Correspondingly, regions with signal-to-noise ratios not surpassing the threshold are not sampled at the faster rate in order to avoid inadequate reflected signal strength due to the light pulse power slump. In this way, spatial detail and signal strength can be balanced. The object of the invention is solved by a method for controlling an optical system according to claim <NUM> and a LIDAR system of claim <NUM>. Preferred embodiments are present in dependent claims.

In the context of the present specification, the term "light source" broadly refers to any device configured to emit radiation such as a radiation signal in the form of a beam, for example, without limitation, a light beam including radiation of one or more respective wavelengths within the electromagnetic spectrum. In one example, the light source can be a "laser source". Thus, the light source could include a laser such as a solid-state laser, laser diode, a high-power laser, or an alternative light source such as, a light emitting diode (LED)-based light source. Some (non-limiting) examples of the laser source include: a Fabry-Perot laser diode, a quantum well laser, a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, a fiber-laser, or a vertical-cavity surface-emitting laser (VCSEL). In addition, the laser source may emit light beams in differing formats, such as light pulses, continuous wave (CW), quasi-CW, and so on. In some non-limiting examples, the laser source may include a laser diode configured to emit light at a wavelength between about <NUM> and <NUM>. Alternatively, the light source may include a laser diode configured to emit light beams at a wavelength between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, or in between any other suitable range. Unless indicated otherwise, the term "about" with regard to a numeric value is defined as a variance of up to <NUM>% with respect to the stated value.

In the context of the present specification, an "output beam" may also be referred to as a radiation beam, such as a light beam, that is generated by the radiation source and is directed downrange towards a region of interest. The output beam may have one or more parameters such as: beam duration, beam angular dispersion, wavelength, instantaneous power, photon density at different distances from light source, average power, beam power intensity, beam width, beam repetition rate, beam sequence, pulse duty cycle, wavelength, or phase etc. The output beam may be unpolarized or randomly polarized, may have no specific or fixed polarization (e.g., the polarization may vary with time), or may have a particular polarization (e.g., linear polarization, elliptical polarization, or circular polarization).

In the context of the present specification, an "input beam" is radiation or light entering the system, generally after having been reflected from one or more objects in the ROI. The "input beam" may also be referred to as a radiation beam or light beam. By reflected is meant that at least a portion of the output beam incident on one or more objects in the ROI, bounces off the one or more objects. The input beam may have one or more parameters such as: time-of-flight (i.e., time from emission until detection), instantaneous power (e.g., power signature), average power across entire return pulse, and photon distribution/signal over return pulse period etc. Depending on the particular usage, some radiation or light collected in the input beam could be from sources other than a reflected output beam. For instance, at least some portion of the input beam could include light-noise from the surrounding environment (including scattered sunlight) or other light sources exterior to the present system.

In the context of the present specification, the term "surroundings" of a given vehicle refers to an area or a volume around the given vehicle including a portion of a current environment thereof accessible for scanning using one or more sensors mounted on the given vehicle, for example, for generating a 3D map of the such surroundings or detecting objects therein.

In the context of the present specification, a "Region of Interest" may broadly include a portion of the observable environment of a LiDAR system in which the one or more objects may be detected. It is noted that the region of interest of the LiDAR system may be affected by various conditions such as but not limited to: an orientation of the LiDAR system (e.g. direction of an optical axis of the LiDAR system); a position of the LiDAR system with respect to the environment (e.g. distance above ground and adjacent topography and obstacles); operational parameters of the LiDAR system (e.g. emission power, computational settings, defined angles of operation), etc. The ROI of LIDAR system may be defined, for example, by a plane angle or a solid angle. In one example, the ROI may also be defined within a certain distance range (e.g. up to <NUM> or so).

In the context of the present specification, a "server" is a computer program that is running on appropriate hardware and is capable of receiving requests (e.g. from electronic devices) over a network, and carrying out those requests, or causing those requests to be carried out. The hardware may be implemented as one physical computer or one physical computer system, but neither is required to be the case with respect to the present technology. In the present context, the use of the expression a "server" is not intended to mean that every task (e.g. received instructions or requests) or any particular task will have been received, carried out, or caused to be carried out, by the same server (i.e. the same software and/or hardware); it is intended to mean that any number of software elements or hardware devices may be involved in receiving/sending, carrying out or causing to be carried out any task or request, or the consequences of any task or request; and all of this software and hardware may be one server or multiple servers, both of which are included within the expression "at least one server".

In the context of the present specification, "electronic device" is any computer hardware that is capable of running software appropriate to the relevant task at hand. In the context of the present specification, the term "electronic device" implies that a device can function as a server for other electronic devices, however it is not required to be the case with respect to the present technology. Thus, some (non-limiting) examples of electronic devices include self-driving unit, personal computers (desktops, laptops, netbooks, etc.), smart phones, and tablets, as well as network equipment such as routers, switches, and gateways. It should be understood that in the present context the fact that the device functions as an electronic device does not mean that it cannot function as a server for other electronic devices.

In the context of the present specification, the expression "information" includes information of any nature or kind whatsoever capable of being stored in a database. Thus information includes, but is not limited to visual works (e.g. maps), audiovisual works (e.g. images, movies, sound records, presentations etc.), data (e.g. location data, weather data, traffic data, numerical data, etc.), text (e.g. opinions, comments, questions, messages, etc.), documents, spreadsheets, etc..

In the context of the present specification, the words "first", "second", "third", etc. have been used as adjectives only for the purpose of allowing for distinction between the nouns that they modify from one another, and not for the purpose of describing any particular relationship between those nouns. Further, as is discussed herein in other contexts, reference to a "first" element and a "second" element does not preclude the two elements from being the same actual real-world element.

Implementations of the present technology each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above- mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein.

The examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the present technology and not to limit its scope to such specifically recited examples and conditions. It will be appreciated that those skilled in the art may devise various arrangements which, although not explicitly described or shown herein, nonetheless embody the principles of the present technology and are included within its scope.

The functions of the various elements shown in the figures, including any functional block labeled as a "processor", may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage.

Referring initially to <FIG>, there is depicted a schematic diagram of a computer system <NUM> suitable for use with some implementations of the present technology. The computer system <NUM> includes various hardware components including one or more single or multi-core processors collectively represented by a processor <NUM>, a solid-state drive <NUM>, and a memory <NUM>, which may be a random-access memory or any other type of memory.

Communication between the various components of the computer system <NUM> may be enabled by one or more internal and/or external buses (not shown) (e.g. a PCI bus, universal serial bus, IEEE <NUM> "Firewire" bus, SCSI bus, Serial-ATA bus, etc.), to which the various hardware components are electronically coupled. According to embodiments of the present technology, the solid-state drive <NUM> stores program instructions suitable for being loaded into the memory <NUM> and executed by the processor <NUM> for determining a presence of an object. For example, the program instructions may be part of a vehicle control application executable by the processor <NUM>. It is noted that the computer system <NUM> may have additional and/or optional components (not depicted), such as network communication modules, localization modules, and the like.

With reference to <FIG>, there is depicted a networked computing environment <NUM> suitable for use with some non-limiting embodiments of the present technology. The networked computing environment <NUM> includes an electronic device <NUM> associated with a vehicle <NUM> and/or associated with a user (not depicted) who is associated with the vehicle <NUM> (such as an operator of the vehicle <NUM>). The networked computing environment <NUM> also includes a server <NUM> in communication with the electronic device <NUM> via a communication network <NUM> (e.g. the Internet or the like, as will be described in greater detail herein below).

In some non-limiting embodiments of the present technology, the networked computing environment <NUM> could include a GPS satellite (not depicted) transmitting and/or receiving a GPS signal to/from the electronic device <NUM>. It will be understood that the present technology is not limited to GPS and may employ a positioning technology other than GPS. It should be noted that the GPS satellite can be omitted altogether.

The vehicle <NUM>, to which the electronic device <NUM> is associated, could be any transportation vehicle, for leisure or otherwise, such as a private or commercial car, truck, motorbike or the like. Although the vehicle <NUM> is depicted as being a land vehicle, this may not be the case in each and every non-limiting embodiment of the present technology. For example, in certain non-limiting embodiments of the present technology, the vehicle <NUM> may be a watercraft, such as a boat, or an aircraft, such as a flying drone.

The vehicle <NUM> may be user operated or a driver-less vehicle. In some non-limiting embodiments of the present technology, it is contemplated that the vehicle <NUM> could be implemented as a Self-Driving Car (SDC). It should be noted that specific parameters of the vehicle <NUM> are not limiting, these specific parameters including for example: vehicle manufacturer, vehicle model, vehicle year of manufacture, vehicle weight, vehicle dimensions, vehicle weight distribution, vehicle surface area, vehicle height, drive train type (e.g. 2x or 4x), tire type, brake system, fuel system, mileage, vehicle identification number, and engine size.

According to the present technology, the implementation of the electronic device <NUM> is not particularly limited. For example, the electronic device <NUM> could be implemented as a vehicle engine control unit, a vehicle CPU, a vehicle navigation device (e.g. TomTom™, Garmin™), a tablet, a personal computer built into the vehicle <NUM>, and the like. Thus, it should be noted that the electronic device <NUM> may or may not be permanently associated with the vehicle <NUM>. Additionally or alternatively, the electronic device <NUM> could be implemented in a wireless communication device such as a mobile telephone (e.g. a smart-phone or a radio-phone). In certain embodiments, the electronic device <NUM> has a display <NUM>.

The electronic device <NUM> could include some or all of the components of the computer system <NUM> depicted in <FIG>, depending on the particular embodiment. In certain embodiments, the electronic device <NUM> is an on-board computer device and includes the processor <NUM>, the solid-state drive <NUM> and the memory <NUM>. In other words, the electronic device <NUM> includes hardware and/or software and/or firmware, or a combination thereof, for processing data as will be described in greater detail below.

In some non-limiting embodiments of the present technology, the communication network <NUM> is the Internet. In alternative non-limiting embodiments of the present technology, the communication network <NUM> can be implemented as any suitable local area network (LAN), wide area network (WAN), a private communication network or the like. It should be expressly understood that implementations for the communication network <NUM> are for illustration purposes only. A communication link (not separately numbered) is provided between the electronic device <NUM> and the communication network <NUM>, the implementation of which will depend, inter alia, on how the electronic device <NUM> is implemented. Merely as an example and not as a limitation, in those non-limiting embodiments of the present technology where the electronic device <NUM> is implemented as a wireless communication device such as a smartphone or a navigation device, the communication link can be implemented as a wireless communication link. Examples of wireless communication links may include, but are not limited to, a <NUM> communication network link, a <NUM> communication network link, and the like. The communication network <NUM> may also use a wireless connection with the server <NUM>.

In some embodiments of the present technology, the server <NUM> is implemented as a computer server and could include some or all of the components of the computer system <NUM> of <FIG>. In one non-limiting example, the server <NUM> is implemented as a Dell™ PowerEdge™ Server running the Microsoft™ Windows Server™ operating system, but can also be implemented in any other suitable hardware, software, and/or firmware, or a combination thereof. In the depicted non-limiting embodiments of the present technology, the server <NUM> is a single server. In alternative non-limiting embodiments of the present technology, the functionality of the server <NUM> may be distributed and may be implemented via multiple servers (not shown).

In some non-limiting embodiments of the present technology, the processor <NUM> of the electronic device <NUM> could be in communication with the server <NUM> to receive one or more updates. Such updates could include, but are not limited to, software updates, map updates, routes updates, weather updates, and the like. In some non-limiting embodiments of the present technology, the processor <NUM> can also be configured to transmit to the server <NUM> certain operational data, such as routes travelled, traffic data, performance data, and the like. Some or all such data transmitted between the vehicle <NUM> and the server <NUM> may be encrypted and/or anonymized.

It should be noted that a variety of sensors and systems may be used by the electronic device <NUM> for gathering information about surroundings <NUM> of the vehicle <NUM>. As seen in <FIG>, the vehicle <NUM> may be equipped with a plurality of sensor systems <NUM>. It should be noted that different sensor systems from the plurality of sensor systems <NUM> may be used for gathering different types of data regarding the surroundings <NUM> of the vehicle <NUM>.

In one example, the plurality of sensor systems <NUM> may include various optical systems including, inter alia, one or more camera-type sensor systems that are mounted to the vehicle <NUM> and communicatively coupled to the processor <NUM> of the electronic device <NUM>. Broadly speaking, the one or more camera-type sensor systems may be configured to gather image data about various portions of the surroundings <NUM> of the vehicle <NUM>. In some cases, the image data provided by the one or more camera-type sensor systems could be used by the electronic device <NUM> for performing object detection procedures. For example, the electronic device <NUM> could be configured to feed the image data provided by the one or more camera-type sensor systems to an Object Detection Neural Network (ODNN) that has been trained to localize and classify potential objects in the surroundings <NUM> of the vehicle <NUM>.

In another example, the plurality of sensor systems <NUM> could include one or more radar-type sensor systems that are mounted to the vehicle <NUM> and communicatively coupled to the processor <NUM>. Broadly speaking, the one or more radar-type sensor systems may be configured to make use of radio waves to gather data about various portions of the surroundings <NUM> of the vehicle <NUM>. For example, the one or more radar-type sensor systems may be configured to gather radar data about potential objects in the surroundings <NUM> of the vehicle <NUM>, such data potentially being representative of a distance of objects from the radar-type sensor system, orientation of objects, velocity and/or speed of objects, and the like.

It should be noted that the plurality of sensor systems <NUM> could include additional types of sensor systems to those non-exhaustively described above and without departing from the scope of the present technology.

According to the present technology and as is illustrated in <FIG>, the vehicle <NUM> is equipped with at least one Light Detection and Ranging (LiDAR) system, such as a LiDAR system <NUM>, for gathering information about surroundings <NUM> of the vehicle <NUM>. While only described herein in the context of being attached to the vehicle <NUM>, it is also contemplated that the LiDAR system <NUM> could be a stand alone operation or connected to another system.

Depending on the embodiment, the vehicle <NUM> could include more or fewer LiDAR systems <NUM> than illustrated. Depending on the particular embodiment, choice of inclusion of particular ones of the plurality of sensor systems <NUM> could depend on the particular embodiment of the LiDAR system <NUM>. The LiDAR system <NUM> could be mounted, or retrofitted, to the vehicle <NUM> in a variety of locations and/or in a variety of configurations.

For example, depending on the implementation of the vehicle <NUM> and the LiDAR system <NUM>, the LiDAR system <NUM> could be mounted on an interior, upper portion of a windshield of the vehicle <NUM>. Nevertheless, as illustrated in <FIG>, other locations for mounting the LiDAR system <NUM> are within the scope of the present disclosure, including on a back window, side windows, front hood, rooftop, front grill, front bumper or the side of the vehicle <NUM>. In some cases, the LiDAR system <NUM> can even be mounted in a dedicated enclosure mounted on the top of the vehicle <NUM>.

In some non-limiting embodiments, such as that of <FIG>, a given one of the plurality of LiDAR systems <NUM> is mounted to the rooftop of the vehicle <NUM> in a rotatable configuration. For example, the LiDAR system <NUM> mounted to the vehicle <NUM> in a rotatable configuration could include at least some components that are rotatable <NUM> degrees about an axis of rotation of the given LiDAR system <NUM>. When mounted in rotatable configurations, the given LiDAR system <NUM> could gather data about most of the portions of the surroundings <NUM> of the vehicle <NUM>.

In some non-limiting embodiments of the present technology, such as that of <FIG>, the LiDAR systems <NUM> is mounted to the side, or the front grill, for example, in a non-rotatable configuration. For example, the LiDAR system <NUM> mounted to the vehicle <NUM> in a non-rotatable configuration could include at least some components that are not rotatable <NUM> degrees and are configured to gather data about pre-determined portions of the surroundings <NUM> of the vehicle <NUM>.

Irrespective of the specific location and/or the specific configuration of the LiDAR system <NUM>, it is configured to capture data about the surroundings <NUM> of the vehicle <NUM> used, for example, for building a multi-dimensional map of objects in the surroundings <NUM> of the vehicle <NUM>. Details relating to the configuration of the LiDAR systems <NUM> to capture the data about the surroundings <NUM> of the vehicle <NUM> will now be described.

With reference to <FIG>, there is depicted a schematic diagram of one particular embodiment of the LiDAR system <NUM> implemented in accordance with certain non-limiting embodiments of the present technology.

Broadly speaking, the LiDAR system <NUM> includes a variety of internal components including, but not limited to: (i) a light source <NUM> (also referred to as a "radiation source"), (ii) a beam splitting element <NUM>, (iii) a scanner unit <NUM> (also referred to as a "scanner assembly"), (iv) a receiving unit <NUM> (also referred to herein as a "detection system", "receiving assembly", or a "detector"), and (v) a controller <NUM>. It is contemplated that in addition to the components non-exhaustively listed above, the LiDAR system <NUM> could include a variety of sensors (such as, for example, a temperature sensor, a moisture sensor, etc.) which are omitted from <FIG> for sake of clarity.

In certain non-limiting embodiments of the present technology, one or more of the internal components of the LiDAR system <NUM> are disposed in a common housing <NUM> as depicted in <FIG>. In some embodiments of the present technology, the controller <NUM> could be located outside of the common housing <NUM> and communicatively connected to the components therein.

Generally speaking, the LiDAR system <NUM> operates as follows: the light source <NUM> of the LiDAR system <NUM> emits pulses of light, forming an output beam <NUM>; the scanner unit <NUM> scans the output beam <NUM> across the surroundings <NUM> of the vehicle <NUM> for locating/capturing data of a priori unknown objects (such as an object <NUM>) therein, for example, for generating a multi-dimensional map of the surroundings <NUM> where objects (including the object <NUM>) are represented in a form of one or more data points. The light source <NUM> and the scanner unit <NUM> will be described in more detail below.

As certain non-limiting examples, the object <NUM> may include all or a portion of a person, vehicle, motorcycle, truck, train, bicycle, wheelchair, pushchair, pedestrian, animal, road sign, traffic light, lane marking, road-surface marking, parking space, pylon, guard rail, traffic barrier, pothole, railroad crossing, obstacle in or near a road, curb, stopped vehicle on or beside a road, utility pole, house, building, trash can, mailbox, tree, any other suitable object, or any suitable combination of all or part of two or more objects.

Further, let it be assumed that the object <NUM> is located at a distance <NUM> from the LiDAR system <NUM>. Once the output beam <NUM> reaches the object <NUM>, the object <NUM> generally reflects at least a portion of light from the output beam <NUM>, and some of the reflected light beams may return back towards the LiDAR system <NUM>, to be received in the form of an input beam <NUM>. By reflecting, it is meant that at least a portion of light beam from the output beam <NUM> bounces off the object <NUM>. A portion of the light beam from the output beam <NUM> may be absorbed or scattered by the object <NUM>.

Accordingly, the input beam <NUM> is captured and detected by the LiDAR system <NUM> via the receiving unit <NUM>. In response, the receiving unit <NUM> is then configured to generate one or more representative data signals. For example, the receiving unit <NUM> may generate an output electrical signal (not depicted) that is representative of the input beam <NUM>. The receiving unit <NUM> may also provide the so-generated electrical signal to the controller <NUM> for further processing. Finally, by measuring a time between emitting the output beam <NUM> and receiving the input beam <NUM> the distance <NUM> to the object <NUM> is calculated by the controller <NUM>.

As will be described in more detail below, the beam splitting element <NUM> is utilized for directing the output beam <NUM> from the light source <NUM> to the scanner unit <NUM> and for directing the input beam <NUM> from the scanner unit to the receiving unit <NUM>.

Use and implementations of these components of the LiDAR system <NUM>, in accordance with certain non-limiting embodiments of the present technology, will be described immediately below.

The light source <NUM> is communicatively coupled to the controller <NUM> and is configured to emit light having a given operating wavelength. To that end, in certain non-limiting embodiments of the present technology, the light source <NUM> could include at least one laser preconfigured for operation at the given operating wavelength. The given operating wavelength of the light source <NUM> may be in the infrared, visible, and/or ultraviolet portions of the electromagnetic spectrum. For example, the light source <NUM> may include at least one laser with an operating wavelength between about <NUM> and <NUM>. Alternatively, the light source <NUM> may include a laser diode configured to emit light at a wavelength between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>.

The light source <NUM> of the LiDAR system <NUM> is generally an eye-safe laser, or put another way, the LiDAR system <NUM> may be classified as an eye-safe laser system or laser product. Broadly speaking, an eye-safe laser, laser system, or laser product may be a system with some or all of: an emission wavelength, average power, peak power, peak intensity, pulse energy, beam size, beam divergence, exposure time, or scanned output beam such that emitted light from this system presents little or no possibility of causing damage to a person's eyes.

According to certain non-limiting embodiments of the present technology, the operating wavelength of the light source <NUM> may lie within portions of the electromagnetic spectrum that correspond to light produced by the Sun. Therefore, in some cases, sunlight may act as background noise, which can obscure the light signal detected by the LiDAR system <NUM>. This solar background noise can result in false-positive detections and/or may otherwise corrupt measurements of the LiDAR system <NUM>.

According to the present technology, the light source <NUM> includes a pulsed laser <NUM> configured to produce, emit, or radiate pulses of light with a certain pulse duration. For example, in some non-limiting embodiments of the present technology, the light source <NUM> may be configured to emit pulses with a pulse duration (e.g., pulse width) ranging from <NUM> ps to <NUM> ns. In other non-limiting embodiments of the present technology, the light source <NUM> may be configured to emit pulses at a pulse repetition frequency of approximately <NUM> to <NUM> or a pulse period (e.g., a time between consecutive pulses) of approximately <NUM> ns to <NUM>. Overall, however, the light source <NUM> can generate the output beam <NUM> with any suitable average optical power, depending on specifics of the particular implementations.

In some non-limiting embodiments of the present technology, the light source <NUM> could include one or more laser diodes, including but not limited to: Fabry-Perot laser diode, a quantum well laser, a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, or a vertical-cavity surface-emitting laser (VCSEL). Just as examples, a given laser diode operating in the light source <NUM> may be an aluminum-gallium-arsenide (AlGaAs) laser diode, an indium-gallium-arsenide (InGaAs) laser diode, or an indium-gallium-arsenide-phosphide (InGaAsP) laser diode, or any other suitable laser diode. It is also contemplated that the light source <NUM> may include one or more laser diodes that are current-modulated to produce optical pulses.

According to the present technology, the light source <NUM> of the LiDAR system <NUM> further includes an amplifier <NUM>, specifically a doped fiber amplifier <NUM> in the illustrated example herein, also illustrated in <FIG>. In some non-limiting embodiments, the fiber amplifier <NUM> could be an erbium-doped fiber amplifier, which includes erbium ions in a fiber core section. The pulsed laser <NUM> is coupled to the fiber amplifier <NUM>, such that light pulses emitted by the pulsed laser <NUM> are received and amplified by the fiber amplifier <NUM>.

In some non-limiting embodiments of the present technology, the fiber amplifier <NUM> is a doped fiber amplifier <NUM>, and in some cases an erbium doped fiber amplifier (EDFA) <NUM>. For implementations or embodiments of the LiDAR system <NUM> implementing the EDFA <NUM>, pulses emitted by the pulsed laser <NUM> are amplified by excited erbium ions in the fiber core of the EDFA <NUM>. After the resulting laser beam pulse is emitted from the light source <NUM>, some time is required to recharge the light source, also referred to as a recharge rate or a recharge frequency, in order to have a maximum amplification of the pulse. The recharge rate is determined by a population inversion rate of the doped fiber amplifier <NUM>. As will be described in more detail below. when the pulse frequency (i.e. the rate at which the pulses are emitted) of the pulsed laser <NUM> is faster than the recharge (population inversion) rate, the pulses emitted from the light source <NUM> experience a power slump due to incomplete recharge of the EDFA/amplifier <NUM>.

It should be noted that, according to the present technology, pulse length, the time during which the laser emits, will generally not be modified although this may not be the case for every embodiment. The present technology addresses control of the pulse frequency (also known as the pulse rate or emitting rate), which is determined based on the time between emission of pulses (<NUM>/time between pulses). According to at least some non-limiting embodiments of the present technology, the time between pulses can be in the range from <NUM> ns to <NUM>. It should also be noted that pulse frequency and pulse length are not necessarily correlated, beyond a limit that pulse length be necessarily less than the time between pulses in order for the light source <NUM> to form separated pulses.

In some non-limiting embodiments of the present technology, the light source <NUM> is generally configured to emit the output beam <NUM> as a collimated optical beam, but it is contemplated that the beam produced could have any suitable beam divergence for a given application. Broadly speaking, divergence of the output beam <NUM> is an angular measure of an increase in beam cross-section size (e.g., a beam radius or beam diameter) as the output beam <NUM> travels away from the light source <NUM> or the LiDAR system <NUM>. In some non-limiting embodiments of the present technology, the output beam <NUM> may have a substantially circular cross-section.

It is also contemplated that the output beam <NUM> emitted by light source <NUM> could be unpolarized or randomly polarized, could have no specific or fixed polarization (e.g., the polarization may vary with time), or could have a particular polarization (e.g., the output beam <NUM> may be linearly polarized, elliptically polarized, or circularly polarized).

In at least some non-limiting embodiments of the present technology, the output beam <NUM> and the input beam <NUM> may be substantially coaxial. In other words, the output beam <NUM> and input beam <NUM> may at least partially overlap or share a common propagation axis, so that the input beam <NUM> and the output beam <NUM> travel along substantially the same optical path (albeit in opposite directions). Nevertheless, in other non-limiting embodiments of the present technology, the output beam <NUM> and the input beam <NUM> may not be coaxial, or in other words, may not overlap or share a common propagation axis inside the LiDAR system <NUM>, without departing from the scope of the present technology.

It should be noted that in at least some non-limiting embodiments of the present technology, the light source <NUM> could be rotatable, such as by <NUM> degrees or less, about the axis of rotation (not depicted) of the LiDAR system <NUM> when the LiDAR system <NUM> is implemented in a rotatable configuration. However, in other embodiments, the light source <NUM> may be stationary even when the LiDAR system <NUM> is implemented in a rotatable configuration, without departing from the scope of the present technology.

With continued reference to <FIG>, there is further provided the beam splitting element <NUM> disposed in the housing <NUM>. For example, as previously mentioned, the beam splitting element <NUM> is configured to direct the output beam <NUM> from the light source <NUM> towards the scanner unit <NUM>. The beam splitting element <NUM> is also arranged and configured to direct the input beam <NUM> reflected off the object <NUM> to the receiving unit <NUM> for further processing thereof by the controller <NUM>.

However, in accordance with other non-limiting embodiments of the present technology, the beam splitting element <NUM> may be configured to split the output beam <NUM> into at least two components of lesser intensity including a scanning beam (not separately depicted) used for scanning the surroundings <NUM> of the LiDAR system <NUM>, and a reference beam (not separately depicted), which is further directed to the receiving unit <NUM>.

In other words, in these embodiments, the beam splitting element <NUM> can be said to be configured to divide intensity (optical power) of the output beam <NUM> between the scanning beam and the reference beam. In some non-limiting embodiments of the present technology, the beam splitting element <NUM> may be configured to divide the intensity of the output beam <NUM> between the scanning beam and the reference beam equally. However, in other non-limiting embodiments of the present technology, the beam splitting element <NUM> may be configured to divide the intensity of the output beam <NUM> at any predetermined splitting ratio. For example, the beam splitting element <NUM> may be configured to use up to <NUM>% of the intensity of the output beam <NUM> for forming the scanning beam, and the remainder of up to <NUM>% of the intensity of the output beam <NUM> - for forming the reference beam. In yet other non-limited embodiments of the present technology, the beam splitting element <NUM> may be configured to vary the splitting ratio for forming the scanning beam (for example, from <NUM>% to <NUM>% of the intensity of the output beam <NUM>).

It should further be noted that some portion (for example, up to <NUM>%) of the intensity of the output beam <NUM> may be absorbed by a material of the beam splitting element <NUM>, which depends on a particular configuration thereof.

Depending on the implementation of the LiDAR system <NUM>, the beam splitting element <NUM> could be provided in a variety of forms, including but not limited to: a glass prism-based beam splitter component, a half-silver mirror-based beam splitter component, a dichroic mirror prism-based beam splitter component, a fiber-optic-based beam splitter component, and the like.

Thus, according to the non-limiting embodiments of the present technology, a non-exhaustive list of adjustable parameters associated with the beam splitting element <NUM>, based on a specific application thereof, may include, for example, an operating wavelength range, which may vary from a finite number of wavelengths to a broader light spectrum (from <NUM> to <NUM>, as an example); an income incidence angle; polarizing/non-polarizing, and the like.

In a specific non-limiting example, the beam splitting element <NUM> can be implemented as a fiber-optic-based beam splitter component that may be of a type available from OZ Optics Ltd. of <NUM> Westbrook Rd Ottawa, Ontario K0A 1L0 Canada. It should be expressly understood that the beam splitting element <NUM> can be implemented in any other suitable equipment.

As is schematically depicted in <FIG>, the LiDAR system <NUM> forms a plurality of internal beam paths <NUM> along which the output beam <NUM> (generated by the light source <NUM>) and the input beam <NUM> (received from the surroundings <NUM>). Specifically, light propagates along the internal beam paths <NUM> as follows: the light from the light source <NUM> passes through the beam splitting element <NUM>, to the scanner unit <NUM> and, in turn, the scanner unit <NUM> directs the output beam <NUM> outward towards the surroundings <NUM>.

Similarly, the input beam <NUM> follows the plurality of internal beam paths <NUM> to the receiving unit <NUM>. Specifically, the input beam <NUM> is directed by the scanner unit <NUM> into the LiDAR system <NUM> through the beam splitting element <NUM>, toward the receiving unit <NUM>. In some implementations, the LiDAR system <NUM> could be arranged with beam paths that direct the input beam <NUM> directly from the surroundings <NUM> to the receiving unit <NUM> (without the input beam <NUM> passing through the scanner unit <NUM>).

It should be noted that, in various non-limiting embodiments of the present technology, the plurality of internal beam paths <NUM> may include a variety of optical components. For example, the LiDAR system <NUM> may include one or more optical components configured to condition, shape, filter, modify, steer, or direct the output beam <NUM> and/or the input beam <NUM>. For example, the LiDAR system <NUM> may include one or more lenses, mirrors, filters (e.g., band pass or interference filters), optical fibers, circulators, beam splitters, polarizers, polarizing beam splitters, wave plates (e.g., half-wave or quarter-wave plates), diffractive elements, microelectromechanical (MEM) elements, collimating elements, or holographic elements.

It is contemplated that in at least some non-limiting embodiments of the present technology, the given internal beam path and the other internal beam path from the plurality of internal beam paths <NUM> may share at least some common optical components, however, this might not be the case in each and every embodiment of the present technology.

Generally speaking, the scanner unit <NUM> steers the output beam <NUM> in one or more directions downrange towards the surroundings <NUM>. The scanner unit <NUM> is communicatively coupled to the controller <NUM>. As such, the controller <NUM> is configured to control the scanner unit <NUM> so as to guide the output beam <NUM> in a desired direction downrange and/or along a predetermined scan pattern. Broadly speaking, in the context of the present specification "scan pattern" may refer to a pattern or path along which the output beam <NUM> is directed by the scanner unit <NUM> during operation.

In certain non-limiting embodiments of the present technology, the controller <NUM> is configured to cause the scanner unit <NUM> to scan the output beam <NUM> over a variety of horizontal angular ranges and/or vertical angular ranges; the total angular extent over which the scanner unit <NUM> scans the output beam <NUM> is referred to herein as the field of view (FoV). It is contemplated that the particular arrangement, orientation, and/or angular ranges could depend on the particular implementation of the LiDAR system <NUM>. The field of view generally includes a plurality of regions of interest (ROIs), defined as portions of the FoV which may contain, for instance, objects of interest. In some implementations, the scanner unit <NUM> can be configured to further investigate a selected region of interest (ROI) <NUM>. The ROI <NUM> of the LiDAR system <NUM> may refer to an area, a volume, a region, an angular range, and/or portion(s) of the surroundings <NUM> about which the LiDAR system <NUM> may be configured to scan and/or can capture data.

It should be noted that a location of the object <NUM> in the surroundings <NUM> of the vehicle <NUM> may be overlapped, encompassed, or enclosed at least partially within the ROI <NUM> of the LiDAR system <NUM>.

It should be noted that, according to certain non-limiting embodiments of the present technology, the scanner unit <NUM> may be configured to scan the output beam <NUM> horizontally and/or vertically, and as such, the ROI <NUM> of the LiDAR system <NUM> may have a horizontal direction and a vertical direction. For example, the ROI <NUM> may be defined by <NUM> degrees in the horizontal direction, and by <NUM> degrees in the vertical direction. In some implementations, different scanning axes could have different orientations.

By the present technology, for scanning the output beam <NUM> over the ROI <NUM>, the scanner unit <NUM> includes a pair of mirrors (not separately depicted), each one of which is independently coupled with a respective galvanometer (not separately depicted) providing control thereto. Accordingly, the controller <NUM> causes, via the respective galvanometers, rotation of each of the pair of mirrors about a respective one of mutually perpendicular axes associated therewith, thereby scanning the ROI <NUM> according to the predetermined scan pattern.

In certain non-limiting embodiments of the present technology, the scanner unit <NUM> may further include a variety of other optical components and/or mechanical-type components for performing the scanning of the output beam <NUM>. For example, the scanner unit <NUM> may include one or more mirrors, prisms, lenses, MEM components, piezoelectric components, optical fibers, splitters, diffractive elements, collimating elements, and the like. It should be noted that the scanner unit <NUM> may also include one or more additional actuators (not separately depicted) driving at least some of the other optical components to rotate, tilt, pivot, or move in an angular manner about one or more axes, for example.

The LiDAR system <NUM> may thus make use of the predetermined scan pattern to generate a point cloud substantially covering the ROI <NUM> of the LiDAR system <NUM>. As will be described in greater detail herein further below, this point cloud of the LiDAR system <NUM> may be used to render a multi-dimensional map of objects in the surroundings <NUM> of the vehicle <NUM>.

As will become apparent from the description provided herein below, in certain non-limiting embodiments of the present technology, the predetermined scan pattern for scanning the ROI <NUM> may be associated with a respective scanning frequency.

According to certain non-limiting embodiments of the present technology, the receiving unit <NUM> is communicatively coupled to the controller <NUM> and may be implemented in a variety of ways. According to the present technology, the receiving unit <NUM> includes a sensor <NUM>, such as a photodetector, but could include (but is not limited to) a photoreceiver, optical receiver, optical sensor, detector, optical detector, optical fibers, and the like. As mentioned above, in some non-limiting embodiments of the present technology, the receiving unit <NUM> may be configured to acquire or detects at least a portion of the input beam <NUM> and produces an electrical signal that corresponds to the input beam <NUM>. For example, if the input beam <NUM> includes an optical pulse, the receiving unit <NUM> may produce an electrical current or voltage pulse that corresponds to the optical pulse detected by the receiving unit <NUM>.

It is contemplated that, in various non-limiting embodiments of the present technology, the receiving unit <NUM> may be implemented with one or more avalanche photodiodes (APDs), one or more single-photon avalanche diodes (SPADs), one or more PN photodiodes (e.g., a photodiode structure formed by a p-type semiconductor and a n-type semiconductor), one or more PIN photodiodes (e.g., a photodiode structure formed by an undoped intrinsic semiconductor region located between p-type and n-type regions), and the like.

In some non-limiting embodiments, the receiving unit <NUM> may also include circuitry that performs signal amplification, sampling, filtering, signal conditioning, analog-to-digital conversion, time-to-digital conversion, pulse detection, threshold detection, rising-edge detection, falling-edge detection, and the like. For example, the receiving unit <NUM> may include electronic components configured to convert a received photocurrent (e.g., a current produced by an APD in response to a received optical signal) into a voltage signal. The receiving unit <NUM> may also include additional circuitry for producing an analog or digital output signal that corresponds to one or more characteristics (e.g., rising edge, falling edge, amplitude, duration, and the like) of a received optical pulse.

Depending on the implementation, the controller <NUM> may include one or more processors, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and/or other suitable circuitry. The controller <NUM> may also include non-transitory computer-readable memory to store instructions executable by the controller <NUM> as well as data which the controller <NUM> may produce based on the signals acquired from other internal components of the LiDAR system <NUM> and/or may provide signals to the other internal components of the LiDAR system <NUM>. The memory can include volatile (e.g., RAM) and/or non-volatile (e.g., flash memory, a hard disk) components. The controller <NUM> may be configured to generate data during operation and store it in the memory. For example, this data generated by the controller <NUM> may be indicative of the data points in the point cloud of the LiDAR system <NUM>.

It is contemplated that, in at least some non-limiting embodiments of the present technology, the controller <NUM> could be implemented in a manner similar to that of implementing the electronic device <NUM> and/or the computer system <NUM>, without departing from the scope of the present technology. In addition to collecting data from the receiving unit <NUM>, the controller <NUM> could also be configured to provide control signals to, and potentially receive diagnostics data from, the light source <NUM> and the scanner unit <NUM>.

As previously stated, the controller <NUM> is communicatively coupled to the light source <NUM>, the scanner unit <NUM>, and the receiving unit <NUM>. In some non-limiting embodiments of the present technology, the controller <NUM> may be configured to receive electrical trigger pulses from the light source <NUM>, where each electrical trigger pulse corresponds to the emission of an optical pulse by the light source <NUM>. The controller <NUM> may further provide instructions, a control signal, and/or a trigger signal to the light source <NUM> indicating when the light source <NUM> is to produce optical pulses indicative, for example, of the output beam <NUM>.

Just as an example, the controller <NUM> may be configured to send an electrical trigger signal that includes electrical pulses, so that the light source <NUM> emits an optical pulse, representable by the output beam <NUM>, in response to each electrical pulse of the electrical trigger signal. It is also contemplated that the controller <NUM> may cause the light source <NUM> to adjust one or more characteristics of output beam <NUM> produced by the light source <NUM> such as, but not limited to: frequency, period, duration, pulse energy, peak power, average power, and wavelength of the optical pulses.

By the present technology, the controller <NUM> is configured to determine a "time-of-flight" value for an optical pulse in order to determine the distance between the LiDAR system <NUM> and one or more objects in the field of view, as will be described further below. The time of flight is based on timing information associated with (i) a first moment in time when a given optical pulse (for example, of the output beam <NUM>) was emitted by the light source <NUM>, and (ii) a second moment in time when a portion of the given optical pulse (for example, from the input beam <NUM>) was detected or received by the receiving unit <NUM>. In some non-limiting embodiments of the present technology, the first moment may be indicative of a moment in time when the controller <NUM> emits a respective electrical pulse associated with the given optical pulse; and the second moment in time may be indicative of a moment in time when the controller <NUM> receives, from the receiving unit <NUM>, an electrical signal generated in response to receiving the portion of the given optical pulse from the input beam <NUM>.

In other non-limiting embodiments of the present technology, where the beam splitting element <NUM> is configured to split the output beam <NUM> into the scanning beam (not depicted) and the reference beam (not depicted), the first moment in time may be a moment in time of receiving, from the receiving unit <NUM>, a first electrical signal generated in response to receiving a portion of the reference beam. Accordingly, in these embodiments, the second moment in time may be determined as the moment in time of receiving, by the controller <NUM> from the receiving unit <NUM>, a second electrical signal generated in response to receiving an other portion of the given optical pulse from the input beam <NUM>.

By the present technology, the controller <NUM> is configured to determine, based on the first moment in time and the second moment in time, a time-of-flight value and/or a phase modulation value for the emitted pulse of the output beam <NUM>. The time-of-light value T, in a sense, a "round-trip" time for the emitted pulse to travel from the LiDAR system <NUM> to the object <NUM> and back to the LiDAR system <NUM>. The controller <NUM> is thus broadly configured to determine the distance <NUM> in accordance with the following equation: <MAT> wherein D is the distance <NUM>, T is the time-of-flight value, and c is the speed of light (approximately <NUM>×<NUM><NUM> m/s).

As previously alluded to, the LiDAR system <NUM> may be used to determine the distance <NUM> to one or more other potential objects located in the surroundings <NUM>. By scanning the output beam <NUM> across the ROI <NUM> of the LiDAR system <NUM> in accordance with the predetermined scan pattern, the controller <NUM> is configured to map distances (similar to the distance <NUM>) to respective data points within the ROI <NUM> of the LiDAR system <NUM>. As a result, the controller <NUM> is generally configured to render these data points captured in succession (e.g., the point cloud) in a form of a multi-dimensional map. In some implementations, data related to the determined time of flight and/or distances to objects could be rendered in different informational formats.

As an example, this multi-dimensional map may be used by the electronic device <NUM> for detecting, or otherwise identifying, objects or determining a shape or distance of potential objects within the ROI <NUM> of the LiDAR system <NUM>. It is contemplated that the LiDAR system <NUM> may be configured to repeatedly/iteratively capture and/or generate point clouds at any suitable rate for a given application.

With reference to <FIG>, a flowchart of a method <NUM> for controlling the LiDAR system <NUM>, the method <NUM> will now be described in more detail according to non-limiting embodiments of the present technology.

In some non-limiting embodiments of the present technology, the method <NUM> may be implemented by the controller <NUM> communicatively connected to the LiDAR system <NUM>. As previously discussed that in at least some non-limiting embodiments of the present technology, the controller <NUM> may include one or more processors and may be implemented in a similar manner to the electronic device <NUM> and/or the computer system <NUM>, without departing from the scope of the present technology. The method <NUM> begins at step <NUM>.

At step <NUM>, the controller <NUM> provides instructions, a control signal, and/or a trigger signal to the light source <NUM> indicating when the light source <NUM> is to emit pulses of light towards the scanner unit <NUM>, at a first pulse frequency. As is mentioned briefly above, the pulse frequency is the rate or frequency at which pulses are emitted from the light source <NUM>.

The first pulse frequency, when the method <NUM> begins, is generally uniform across the field of view and below (slower) than the recharge rate of the fiber amplifier <NUM>. In this way, each sampling pulse has the full amplification desired or available from the fiber amplifier <NUM>. In some non-limiting implementations, it is contemplated that portions of the field of view may be sampled at different rates for reasons outside the scope of the current technology. For simplicity of explanation, the method <NUM> is described herein with the assumption that no other methods of operation are simultaneously being used to control the LiDAR system <NUM>, although it is contemplated that the present method <NUM> could be run in addition to and/or concurrently with other methods of operation.

In one or more steps associated with the method <NUM>, the controller <NUM> may be configured to cause the light source <NUM> to begin to emit the output beam <NUM> towards the scanner unit <NUM> in certain conditions. Such conditions may include but are not limited to: upon operating the vehicle <NUM> in self-driving mode, when the vehicle <NUM> is in motion irrespective of the driving mode, when the vehicle <NUM> is stationary, when the vehicle <NUM> is initially turned on, or based on a manual operation performed by a user (not depicted) operating the vehicle <NUM> etc..

At step <NUM>, the controller <NUM> provides instructions, a control signal, and/or a trigger signal to the cause the scanner unit <NUM> to direct the pulses of light, of the output beam <NUM>, out from the LiDAR system <NUM>. Depending on the specific implementation, pulses are scanned over portions or the entirety of the field of view of the LiDAR system <NUM> to create 3D maps of the surroundings falling within the field of view.

At step <NUM>, reflected light from the field of view of the LiDAR system <NUM> is sensed by the sensor <NUM> of the receiving unit <NUM>. The controller <NUM> then receives a signal and/or information corresponding to one or more reflected light signals, sensed by the sensor <NUM>. As is described above, the input beam <NUM> enters the LiDAR system <NUM> from the field of view and is directed by components of the LiDAR system <NUM> to the sensor <NUM> and the receiving unit <NUM>.

In at least some non-limiting embodiments of the present technology, the sensing at step <NUM> could include sensing a plurality of reflected light signals reflected from one or more regions of interest of the field of view.

At step <NUM>, the controller <NUM> determines, or calculates, a signal-to-noise ratio of the reflected signal received by the sensor <NUM> of the receiving unit <NUM>. The signal-to-noise ratio (SNR) is calculated by dividing a determined signal power by a background noise power level. Depending on the embodiment, the background noise level can be determined in various ways. According to one non-limiting embodiment, the background noise level can be determined by sensing or measuring a signal magnitude from the sensor <NUM> when there is no input beam <NUM> reaching the sensor <NUM>. In at least some non-limiting embodiments, the background noise level can be determined by including a shutter in front of the sensor <NUM> for periodically blocking the input beam <NUM>, and measuring the "signal" at the sensor <NUM> when the shutter is blocking the input beam <NUM>. Depending on the implementation, the background noise level could be determined sporadically or at a regular frequency.

In at least some non-limiting embodiments of the present technology, the controller <NUM> could determine the SNR of a portion of the reflected signal received by the sensor <NUM> corresponding to a region of interest (ROI) within the field of view. Depending on the embodiment or implementation, individual SNR values for one or more ROIs could be determined by the controller <NUM>, either simultaneously and/or sequentially. For instance, different SNR values for different portions of the field of view could be determined for a signal scan. In another non-limiting example, the controller <NUM> could determine the SNR of different portions of the field of view in different scans of the field of view.

At step <NUM>, the controller <NUM> determines a signal difference between a signal-to-noise threshold and the SNR. Having determined the SNR at step <NUM>, the controller then compares the determined SNR to a signal-to-noise threshold in order to determine the relative strength of the signal of the input beam <NUM>. In at least some non-limiting embodiments, determining the signal difference could include determining a magnitude and sign of a difference between the SNR and the threshold. In at least some non-limiting embodiments, could include determining if the SNR is greater than the threshold.

In at least some non-limiting embodiments, generally speaking, the signal-to-noise threshold is a minimum acceptable value of the SNR, below which noise begins to affect signal quality. In at least some non-limiting embodiments, the signal-to-noise threshold could be a minimum good signal value, at some values below such the SNR may still be sufficient for good data collection. In at least some non-limiting embodiments of the present technology, the signal-to-noise threshold is a pre-determined value stored to the controller <NUM>, although it may also be stored to the electronic device <NUM> and/or the computer system <NUM> without departing from the scope of the present technology. It is also contemplated that the threshold could be calculated by the controller <NUM> (or the electronic device <NUM> and/or the computer system <NUM>), depending on variables of the LiDAR system <NUM>, including but not limited to environmental and/or weather-related condition, environmental lighting levels, external illumination, required ranging capability (required current radiation range), current speed, and road conditions.

At step <NUM>, the controller <NUM> causes, based on the signal difference determined at step <NUM>, the light source <NUM> to emit pulses of light at a second pulse frequency different than the first pulse frequency.

In at least some non-limiting embodiments of the present technology, the controller <NUM> could direct the light source <NUM> to change the pulse frequency of the output beam <NUM> in response to any non-zero difference between the threshold and the SNR determined at step <NUM>. In at least some other non-limiting embodiments, the controller <NUM> could direct the light source <NUM> to change the pulse frequency of the output beam <NUM> when the difference between the threshold and the determined SNR is above a minimum difference value. As one non-limiting example, the light source <NUM> could change pulse frequency when the determined SNR is at least double the threshold SNR value.

In one or more non-limiting steps associated with the method <NUM>, the controller <NUM> may determine that the SNR is greater than the signal-to-noise threshold. In such a case, the pulse frequency of the light source <NUM> could be increased such that the second pulse frequency is greater (faster) than the first pulse frequency. In at least some non-limiting embodiments of the present technology, the second pulse frequency could be greater than the recharge rate of the light source <NUM>, specifically the recharge rate of the fiber amplifier <NUM>. As is mentioned briefly above, the power of the output beam <NUM> is generally reduced ("power slump") in cases where the pulse frequency of the output beam <NUM> is greater than the recharge rate of the amplifier <NUM>. By determining that the SNR is greater than the threshold in step <NUM>, however, the SNR has been determined to be sufficiently high such that power reduction of the output beam <NUM> should still result in a sufficient signal-to-noise ratio to produce the desired 3D map. In other words, the pulse rate of the output beam <NUM> can thus be increased to produce a more detailed 3D map, while maintaining at least a minimum signal-to-noise ratio. In this way, spatial detail (determined by the pulse rate) can be improved for all or portions of the field of view having sufficiently good signal quality to tolerate some reduction (without sacrificing a minimum signal quality).

In at least some non-limiting embodiments of the present technology, the method <NUM> further includes determining a second SNR while the light source <NUM> is producing the output beam <NUM> at the second pulse frequency, subsequent to previous SNR measurements. Methods of determining the second SNR could be the same or different than the specific ones used for determining the initial SNR, depending on the specific implementation.

In at least some such non-limiting embodiments, the method <NUM> could further include determining, by the controller <NUM>, that the second SNR is less than the signal-to-noise threshold. The controller <NUM> could then cause the light source <NUM> to emit pulses of light at a third pulse frequency, different than the second pulse frequency. As one non-limiting example, the third pulse frequency could be less than the second pulse frequency, such that the amplifier <NUM> would have a longer amount of time to allow greater recharging of the amplifier <NUM> to increase the power of the output beam <NUM>, to aid in returning the signal-to-noise ratio to a desired level. In some cases, the third pulse frequency is equal to the first pulse frequency, such that the output beam <NUM> is produced with the same pulse frequency as it did initially. In some other non-limiting embodiments, it is contemplated that the third pulse frequency could be greater than or less than the first frequency, depending on various factors in the LiDAR system <NUM> or the particular implementation.

In at least some non-limiting embodiments of the present technology, determining the SNR of the reflected light signal at step <NUM> includes determining one or more subzone signal-to-noise ratios (subzone SNRs) by the controller <NUM>. The subzone SNR corresponds to a signal-to-noise ratio of a portion of the reflected signal coming from a given ROI within the field of view of the LiDAR system <NUM>. In such an embodiment, the method <NUM> could include, at step <NUM>, determining the difference between the signal-to-noise threshold and one or more of the subzone SNRs. In at least some such non-limiting embodiments, the controller <NUM> could determine that a given subzone SNR is greater than the signal-to-noise threshold and cause the light source <NUM> to emit pulses of light at the second pulse frequency when scanning a given region of interest, for which the given subzone SNR was determined. In some cases, the controller <NUM> could determine that a plurality of subzone SNRs are greater than the threshold and cause the light source <NUM> to emit pulses of light at the second pulse frequency when scanning corresponding regions of interest. In at least some such non-limiting embodiments, it is also contemplated that the controller <NUM> could cause the light source <NUM> to emit pulses of light at different pulse frequencies when scanning different regions of interest, depending on the difference between each subzone SNR and the threshold.

In at least some non-limiting embodiments of the present technology, the method <NUM> could further include the controller <NUM> causing the light source <NUM> to return the pulse frequency to the first pulse frequency for one or more regions of interest, one or more subzones, and/or the entire field of view after a given period of time. In at least some non-limiting embodiments of the present technology, the method <NUM> could further include the light source <NUM> being caused to return to the first pulse frequency upon determination of decreased quality of the 3D map, according to methods outside the scope of the present technology.

It should be apparent to those skilled in the art that at least some embodiments of the present technology aim to expand a range of technical solutions for addressing a particular technical problem, namely improving spatial detail of a LiDAR system while limiting effects of signal quality.

Claim 1:
A method (<NUM>) for controlling an optical system, comprising:
causing, by a controller (<NUM>), a light source (<NUM>) composed of a laser source (<NUM>) coupled to a fiber amplifier (<NUM>) to emit pulses of light at a first pulse frequency;
directing, by a scanner unit (<NUM>) communicatively connected to the controller (<NUM>), the pulses of light out from the optical system;
sensing, by at least one sensor communicatively connected with the controller (<NUM>), a reflected light signal reflected from at least one object (<NUM>) in a field of view of the optical system;
determining, by the controller (<NUM>), a signal-to-noise ratio of the reflected light signal;
determining, by the controller (<NUM>), a signal difference between a signal-to-noise threshold and the signal-to-noise ratio, the signal-to-noise ratio being greater than the signal-to-noise threshold; and
causing, by the controller (<NUM>), based on the signal difference, the light source (<NUM>) to emit pulses of light at a second pulse frequency different than the first pulse frequency, the second pulse frequency being greater than the first pulse frequency, the second pulse frequency being greater than a recharge rate of the light source (<NUM>) determined by a population inversion rate of the fiber amplifier (<NUM>).