Patent Application
20240230898
This disclosure relates generally to light ranging and detection and, more particularly, to a laser device having multiple seed lasers for providing light to a LiDAR system.
Light detection and ranging (LiDAR) systems use light pulses to create an image or point cloud of the external environment. Some typical LiDAR systems include a light source, a light transmitter, a light steering system, and a light detector. The light source generates a light beam that is directed by the light steering system in particular directions when being transmitted from the LiDAR system. When a transmitted light beam is scattered by an object, a portion of the scattered light returns to the LiDAR system as a return light pulse. The light detector detects the return light pulse. Using the difference between the time that the return light pulse is detected and the time that a corresponding light pulse in the light beam is transmitted, the LiDAR system can determine the distance to the object using the speed of light. The light steering system can direct light beams along different paths to allow the LiDAR system to scan the surrounding environment and produce images or point clouds. LiDAR systems can also use techniques other than time-of-flight and scanning to measure the surrounding environment.
Systems and methods described in this disclosure provide a multiple-seed laser device for providing light to a LiDAR system. A typical pulsed fiber laser source includes a single wavelength seed laser. However, for many LiDAR applications, it is beneficial to have two scanners with two different wavelengths, e.g., one to cover the overall field-of-view (FOV) and the other to cover a smaller region-of-interest (ROI). Instead of having two separate laser sources, the embodiments herein allow for multiple (two or more) seed lasers to share common amplifier sections. This solution saves space and cost and also supports flexible device configurations.
In one embodiment, a laser device for providing light to a light ranging and detection (LiDAR) system is provided. The device comprises a plurality of seed lasers configured to provide multiple seed light beams, at least two of the seed light beams having different wavelengths. A first light coupling unit is optically coupled to the plurality of seed lasers and configured to receive the multiple seed light beams. An amplifier is optically coupled to the first light coupling unit to receive the multiple seed light beams, and a power pump is configured to provide pump power to the amplifier, where the amplifier amplifies the multiple seed light beams using the pump power to obtain amplified light beams. A second light coupling unit is configured to demultiplex the amplified light beams to obtain a plurality of output light beams, at least two of the output light beams having wavelengths corresponding to the wavelengths of the at least two seed light beams.
In one embodiment, a method of providing laser light to a light ranging and detection (LiDAR) system is provided. The method comprises receiving, from a plurality of seed lasers at a first light coupling unit, multiple seed light beams, at least two of the seed light beams having different wavelengths; generating, by a power pump, pump laser light to provide pump power; amplifying, by an amplifier optically coupled to the first light coupling unit and the power pump, the multiple seed light beams using the pump power to obtain amplified light beams; and demultiplexing, by a second light coupling unit optically coupled to the amplifier, the amplified light beams to obtain a plurality of output light beams, at least two of the output light beams having wavelengths corresponding to the wavelengths of the at least two seed light beams.
The present application can be best understood by reference to the figures described below taken in conjunction with the accompanying drawing figures, in which like parts may be referred to by like numerals.
To provide a more thorough understanding of the present invention, the following description sets forth numerous specific details, such as specific configurations, parameters, examples, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention but is intended to provide a better description of the exemplary embodiments.
Throughout the Specification and Claims, the Following Terms Take the Meanings Explicitly Associated Herein, Unless the Context Clearly Dictates Otherwise:
The phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment, though it may. Thus, as described below, various embodiments of the disclosure may be readily combined, without departing from the scope or spirit of the invention.
As used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and/or,” unless the context clearly dictates otherwise.
The term “based on” is not exclusive and allows for being based on additional factors not described unless the context clearly dictates otherwise.
As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. Within the context of a networked environment where two or more components or devices are able to exchange data, the terms “coupled to” and “coupled with” are also used to mean “communicatively coupled with”, possibly via one or more intermediary devices.
Although the following description uses terms “first,” “second,” etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another. For example, a first seed laser could be termed a second seed laser and, similarly, a second seed laser could be termed a first seed laser, without departing from the scope of the various described examples. The first seed laser and the second seed laser can both be seed lasers and, in some cases, can be separate and different seed lasers.
In addition, throughout the specification, the meaning of “a”, “an”, and “the” includes plural references, and the meaning of “in” includes “in” and “on”.
Although some of the various embodiments presented herein constitute a single combination of inventive elements, it should be appreciated that the inventive subject matter is considered to include all possible combinations of the disclosed elements. As such, if one embodiment comprises elements A, B, and C, and another embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly discussed herein. Further, the transitional term “comprising” means to have as parts or members, or to be those parts or members. As used herein, the transitional term “comprising” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.
Throughout the following disclosure, numerous references may be made regarding servers, services, interfaces, engines, modules, clients, peers, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor (e.g., ASIC, FPGA, PLD, DSP, x86, ARM, RISC-V, ColdFire, GPU, multi-core processors, etc.) configured to execute software instructions stored on a computer readable tangible, non-transitory medium (e.g., hard drive, solid state drive, RAM, flash, ROM, etc.). For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions. One should further appreciate the disclosed computer-based algorithms, processes, methods, or other types of instruction sets can be embodied as a computer program product comprising a non-transitory, tangible computer readable medium storing the instructions that cause a processor to execute the disclosed steps. The various servers, systems, databases, or interfaces can exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges can be conducted over a packet-switched network, a circuit-switched network, the Internet, LAN, WAN, VPN, or other type of network.
As used in the description herein and throughout the claims that follow, when a system, engine, server, device, module, or other computing element is described as being configured to perform or execute functions on data in a memory, the meaning of “configured to” or “programmed to” is defined as one or more processors or cores of the computing element being programmed by a set of software instructions stored in the memory of the computing element to execute the set of functions on target data or data objects stored in the memory.
It should be noted that any language directed to a computer should be read to include any suitable combination of computing devices or network platforms, including servers, interfaces, systems, databases, agents, peers, engines, controllers, modules, or other types of computing devices operating individually or collectively. One should appreciate the computing devices comprise a processor configured to execute software instructions stored on a tangible, non-transitory computer readable storage medium (e.g., hard drive, FPGA, PLA, solid state drive, RAM, flash, ROM, etc.). The software instructions configure or program the computing device to provide the roles, responsibilities, or other functionality as discussed below with respect to the disclosed apparatus. Further, the disclosed technologies can be embodied as a computer program product that includes a non-transitory computer readable medium storing the software instructions that causes a processor to execute the disclosed steps associated with implementations of computer-based algorithms, processes, methods, or other instructions. In some embodiments, the various servers, systems, databases, or interfaces exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges among devices can be conducted over a packet-switched network, the Internet, LAN, WAN, VPN, or other type of packet switched network; a circuit switched network; cell switched network; or other type of network.
In typical configurations, motor vehicle 100 comprises one or more LiDAR systems 110 and 120A-F. Each of LiDAR systems 110 and 120A-F can be a scanning-based LiDAR system and/or a non-scanning LiDAR system (e.g., a flash LiDAR). A scanning-based LiDAR system scans one or more light beams in one or more directions (e.g., horizontal and vertical directions) to detect objects in a field-of-view (FOV). A non-scanning based LiDAR system transmits laser light to illuminate an FOV without scanning. For example, a flash LiDAR is a type of non-scanning based LiDAR system. A flash LiDAR can transmit laser light to simultaneously illuminate an FOV using a single light pulse or light shot.
A LiDAR system is often an essential sensor of a vehicle that is at least partially automated. In one embodiment, as shown in
LiDAR system(s) 210 can include one or more of short-range LiDAR sensors, medium-range LiDAR sensors, and long-range LiDAR sensors. A short-range LiDAR sensor measures objects located up to about 20-40 meters from the LiDAR sensor. Short-range LiDAR sensors can be used for, e.g., monitoring nearby moving objects (e.g., pedestrians crossing street in a school zone), parking assistance applications, or the like. A medium-range LiDAR sensor measures objects located up to about 100-150 meters from the LiDAR sensor. Medium-range LiDAR sensors can be used for, e.g., monitoring road intersections, assistance for merging onto or leaving a freeway, or the like. A long-range LiDAR sensor measures objects located up to about 150-300 meters. Long-range LiDAR sensors are typically used when a vehicle is travelling at high speed (e.g., on a freeway), such that the vehicle's control systems may only have a few seconds (e.g., 6-8 seconds) to respond to any situations detected by the LiDAR sensor. As shown in
With reference still to
Other vehicle onboard sensor(s) 230 can also include radar sensor(s) 234. Radar sensor(s) 234 use radio waves to determine the range, angle, and velocity of objects. Radar sensor(s) 234 produce electromagnetic waves in the radio or microwave spectrum. The electromagnetic waves reflect off an object and some of the reflected waves return to the radar sensor, thereby providing information about the object's position and velocity. Radar sensor(s) 234 can include one or more of short-range radar(s), medium-range radar(s), and long-range radar(s). A short-range radar measures objects located at about 0.1-30 meters from the radar. A short-range radar is useful in detecting objects located nearby the vehicle, such as other vehicles, buildings, walls, pedestrians, bicyclists, etc. A short-range radar can be used to detect a blind spot, assist in lane changing, provide rear-end collision warning, assist in parking, provide emergency braking, or the like. A medium-range radar measures objects located at about 30-80 meters from the radar. A long-range radar measures objects located at about 80-200 meters. Medium- and/or long-range radars can be useful in, for example, traffic following, adaptive cruise control, and/or highway automatic braking. Sensor data generated by radar sensor(s) 234 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations.
Other vehicle onboard sensor(s) 230 can also include ultrasonic sensor(s) 236. Ultrasonic sensor(s) 236 use acoustic waves or pulses to measure object located external to a vehicle. The acoustic waves generated by ultrasonic sensor(s) 236 are transmitted to the surrounding environment. At least some of the transmitted waves are reflected off an object and return to the ultrasonic sensor(s) 236. Based on the return signals, a distance of the object can be calculated. Ultrasonic sensor(s) 236 can be useful in, for example, check blind spot, identify parking spots, provide lane changing assistance into traffic, or the like. Sensor data generated by ultrasonic sensor(s) 236 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations.
In some embodiments, one or more other sensor(s) 238 may be attached in a vehicle and may also generate sensor data. Other sensor(s) 238 may include, for example, global positioning systems (GPS), inertial measurement units (IMU), or the like. Sensor data generated by other sensor(s) 238 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. It is understood that communication path 233 may include one or more communication links to transfer data between the various sensor(s) 230 and vehicle perception and planning system 220.
In some embodiments, as shown in
With reference still to
Sharing sensor data facilitates a better perception of the environment external to the vehicles. For instance, a first vehicle may not sense a pedestrian that is a behind a second vehicle but is approaching the first vehicle. The second vehicle may share the sensor data related to this pedestrian with the first vehicle such that the first vehicle can have additional reaction time to avoid collision with the pedestrian. In some embodiments, similar to data generated by sensor(s) 230, data generated by sensors onboard other vehicle(s) 250 may be correlated or fused with sensor data generated by LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220.
In some embodiments, intelligent infrastructure system(s) 240 are used to provide sensor data separately or together with LiDAR system(s) 210. Certain infrastructures may be configured to communicate with a vehicle to convey information and vice versa.
Communications between a vehicle and infrastructures are generally referred to as V2I (vehicle to infrastructure) communications. For example, intelligent infrastructure system(s) 240 may include an intelligent traffic light that can convey its status to an approaching vehicle in a message such as “changing to yellow in 5 seconds.” Intelligent infrastructure system(s) 240 may also include its own LiDAR system mounted near an intersection such that it can convey traffic monitoring information to a vehicle. For example, a left-turning vehicle at an intersection may not have sufficient sensing capabilities because some of its own sensors may be blocked by traffics in the opposite direction. In such a situation, sensors of intelligent infrastructure system(s) 240 can provide useful, and sometimes vital, data to the left-turning vehicle. Such data may include, for example, traffic conditions, information of objects in the direction the vehicle is turning to, traffic light status and predictions, or the like. These sensor data generated by intelligent infrastructure system(s) 240 can be provided to vehicle perception and planning system 220 and/or vehicle onboard LiDAR system(s) 210, via communication paths 243 and/or 241, respectively. Communication paths 243 and/or 241 can include any wired or wireless communication links that can transfer data. For example, sensor data from intelligent infrastructure system(s) 240 may be transmitted to LiDAR system(s) 210 and correlated or fused with sensor data generated by LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220. V2V and V2I communications described above are examples of vehicle-to-X (V2X) communications, where the “X” represents any other devices, systems, sensors, infrastructure, or the like that can share data with a vehicle.
With reference still to
In other examples, sensor data generated by other vehicle onboard sensor(s) 230 may have a lower resolution (e.g., radar sensor data) and thus may need to be correlated and confirmed by LiDAR system(s) 210, which usually has a higher resolution. For example, a sewage cover (also referred to as a manhole cover) may be detected by radar sensor 234 as an object towards which a vehicle is approaching. Due to the low-resolution nature of radar sensor 234, vehicle perception and planning system 220 may not be able to determine whether the object is an obstacle that the vehicle needs to avoid. High-resolution sensor data generated by LiDAR system(s) 210 thus can be used to correlated and confirm that the object is a sewage cover and causes no harm to the vehicle.
Vehicle perception and planning system 220 further comprises an object classifier 223. Using raw sensor data and/or correlated/fused data provided by sensor fusion sub-system 222, object classifier 223 can detect and classify the objects and estimate the positions of the objects. In some embodiments, object classifier 233 can use machine-learning based techniques to detect and classify objects. Examples of the machine-learning based techniques include utilizing algorithms such as region-based convolutional neural networks (R-CNN), Fast R-CNN, Faster R-CNN, histogram of oriented gradients (HOG), region-based fully convolutional network (R-FCN), single shot detector (SSD), spatial pyramid pooling (SPP-net), and/or You Only Look Once (Yolo).
Vehicle perception and planning system 220 further comprises a road detection sub-system 224. Road detection sub-system 224 localizes the road and identifies objects and/or markings on the road. For example, based on raw or fused sensor data provided by radar sensor(s) 234, camera(s) 232, and/or LiDAR system(s) 210, road detection sub-system 224 can build a 3D model of the road based on machine-learning techniques (e.g., pattern recognition algorithms for identifying lanes). Using the 3D model of the road, road detection sub-system 224 can identify objects (e.g., obstacles or debris on the road) and/or markings on the road (e.g., lane lines, turning marks, crosswalk marks, or the like).
Vehicle perception and planning system 220 further comprises a localization and vehicle posture sub-system 225. Based on raw or fused sensor data, localization and vehicle posture sub-system 225 can determine position of the vehicle and the vehicle's posture. For example, using sensor data from LiDAR system(s) 210, camera(s) 232, and/or GPS data, localization and vehicle posture sub-system 225 can determine an accurate position of the vehicle on the road and the vehicle's six degrees of freedom (e.g., whether the vehicle is moving forward or backward, up or down, and left or right). In some embodiments, high-definition (HD) maps are used for vehicle localization. HD maps can provide highly detailed, three-dimensional, computerized maps that pinpoint a vehicle's location. For instance, using the HD maps, localization and vehicle posture sub-system 225 can determine precisely the vehicle's current position (e.g., which lane of the road the vehicle is currently in, how close it is to a curb or a sidewalk) and predict vehicle's future positions.
Vehicle perception and planning system 220 further comprises obstacle predictor 226. Objects identified by object classifier 223 can be stationary (e.g., a light pole, a road sign) or dynamic (e.g., a moving pedestrian, bicycle, another car). For moving objects, predicting their moving path or future positions can be important to avoid collision. Obstacle predictor 226 can predict an obstacle trajectory and/or warn the driver or the vehicle planning sub-system 228 about a potential collision. For example, if there is a high likelihood that the obstacle's trajectory intersects with the vehicle's current moving path, obstacle predictor 226 can generate such a warning. Obstacle predictor 226 can use a variety of techniques for making such a prediction. Such techniques include, for example, constant velocity or acceleration models, constant turn rate and velocity/acceleration models, Kalman Filter and Extended Kalman Filter based models, recurrent neural network (RNN) based models, long short-term memory (LSTM) neural network-based models, encoder-decoder RNN models, or the like.
With reference still to
Vehicle control system 280 controls the vehicle's steering mechanism, throttle, brake, etc., to operate the vehicle according to the planned route and movement. Vehicle perception and planning system 220 may further comprise a user interface 260, which provides a user (e.g., a driver) access to vehicle control system 280 to, for example, override or take over control of the vehicle when necessary. User interface 260 can communicate with vehicle perception and planning system 220, for example, to obtain and display raw or fused sensor data, identified objects, vehicle's location/posture, etc. These displayed data can help a user to better operate the vehicle. User interface 260 can communicate with vehicle perception and planning system 220 and/or vehicle control system 280 via communication paths 221 and 261 respectively, which include any wired or wireless communication links that can transfer data. It is understood that the various systems, sensors, communication links, and interfaces in
LiDAR system 300 can also include other components not depicted in
Laser source 310 outputs laser light for illuminating objects in a field of view (FOV). Laser source 310 can be, for example, a semiconductor-based laser (e.g., a diode laser) and/or a fiber-based laser. A semiconductor-based laser can be, for example, an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), or the like. A fiber-based laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and/or holmium. In some embodiments, a fiber laser is based on double-clad fibers, in which the gain medium forms the core of the fiber surrounded by two layers of cladding. The double-clad fiber allows the core to be pumped with a high-power beam, thereby enabling the laser source to be a high-power fiber laser source.
In some embodiments, laser source 310 comprises a master oscillator (also referred to as a seed laser) and power amplifier (MOPA). The power amplifier amplifies the output power of the seed laser. The power amplifier can be a fiber amplifier, a bulk amplifier, or a semiconductor optical amplifier. The seed laser can be a diode laser (e.g., a Fabry-Perot cavity laser, a distributed feedback laser), a solid-state bulk laser, or a tunable external-cavity diode laser. In some embodiments, laser source 310 can be an optically pumped microchip laser. Microchip lasers are alignment-free monolithic solid-state lasers where the laser crystal is directly contacted with the end mirrors of the laser resonator. A microchip laser is typically pumped with a laser diode (directly or using a fiber) to obtain the desired output power. A microchip laser can be based on neodymium-doped yttrium aluminum garnet (Y3Al5O12) laser crystals (i.e., Nd:YAG), or neodymium-doped vanadate (i.e., ND:YVO4) laser crystals.
In some variations, fiber-based laser source 400 can be controlled (e.g., by control circuitry 350) to produce pulses of different amplitudes based on the fiber gain profile of the fiber used in fiber-based laser source 400. Communication path 312 couples fiber-based laser source 400 to control circuitry 350 (shown in
Referencing
It is understood that the above descriptions provide non-limiting examples of a laser source 310. Laser source 310 can be configured to include many other types of light sources (e.g., laser diodes, short-cavity fiber lasers, solid-state lasers, and/or tunable external cavity diode lasers) that are configured to generate one or more light signals at various wavelengths. In some examples, light source 310 comprises amplifiers (e.g., pre-amplifiers and/or booster amplifiers), which can be a doped optical fiber amplifier, a solid-state bulk amplifier, and/or a semiconductor optical amplifier. The amplifiers are configured to receive and amplify light signals with desired gains.
With reference back to
Laser beams provided by laser source 310 may diverge as they travel to transmitter 320. Therefore, transmitter 320 often comprises a collimating lens configured to collect the diverging laser beams and produce more parallel optical beams with reduced or minimum divergence. The collimated optical beams can then be further directed through various optics such as mirrors and lens. A collimating lens may be, for example, a single plano-convex lens or a lens group. The collimating lens can be configured to achieve any desired properties such as the beam diameter, divergence, numerical aperture, focal length, or the like. A beam propagation ratio or beam quality factor (also referred to as the M2 factor) is used for measurement of laser beam quality. In many LiDAR applications, it is important to have good laser beam quality in the generated transmitting laser beam. The M2 factor represents a degree of variation of a beam from an ideal Gaussian beam. Thus, the M2 factor reflects how well a collimated laser beam can be focused on a small spot, or how well a divergent laser beam can be collimated. Therefore, laser source 310 and/or transmitter 320 can be configured to meet, for example, a scan resolution requirement while maintaining the desired M2 factor.
One or more of the light beams provided by transmitter 320 are scanned by steering mechanism 340 to a FOV. Steering mechanism 340 scans light beams in multiple dimensions (e.g., in both the horizontal and vertical dimension) to facilitate LiDAR system 300 to map the environment by generating a 3D point cloud. Steering mechanism 340 will be described in more detail below. The laser light scanned to an FOV may be scattered or reflected by an object in the FOV. At least a portion of the scattered or reflected light returns to LiDAR system 300.
A light detector detects the return light focused by the optical receiver and generates current and/or voltage signals proportional to the incident intensity of the return light. Based on such current and/or voltage signals, the depth information of the object in the FOV can be derived. One exemplary method for deriving such depth information is based on the direct TOF (time of flight), which is described in more detail below. A light detector may be characterized by its detection sensitivity, quantum efficiency, detector bandwidth, linearity, signal to noise ratio (SNR), overload resistance, interference immunity, etc. Based on the applications, the light detector can be configured or customized to have any desired characteristics. For example, optical receiver and light detector 330 can be configured such that the light detector has a large dynamic range while having a good linearity. The light detector linearity indicates the detector's capability of maintaining linear relationship between input optical signal power and the detector's output. A detector having good linearity can maintain a linear relationship over a large dynamic input optical signal range.
To achieve desired detector characteristics, configurations or customizations can be made to the light detector's structure and/or the detector's material system. Various detector structure can be used for a light detector. For example, a light detector structure can be a PIN based structure, which has a undoped intrinsic semiconductor region (i.e., an “i” region) between a p-type semiconductor and an n-type semiconductor region. Other light detector structures comprise, for example, an avalanche photodiode (APD) based structure, a photomultiplier tube (PMT) based structure, a silicon photomultiplier (SiPM) based structure, a single-photon avalanche diode (SPAD) based structure, and/or quantum wires. For material systems used in a light detector, Si, InGaAs, and/or Si/Ge based materials can be used. It is understood that many other detector structures and/or material systems can be used in optical receiver and light detector 330.
A light detector (e.g., an APD based detector) may have an internal gain such that the input signal is amplified when generating an output signal. However, noise may also be amplified due to the light detector's internal gain. Common types of noise include signal shot noise, dark current shot noise, thermal noise, and amplifier noise (TIA). In some embodiments, optical receiver and light detector 330 may include a pre-amplifier that is a low noise amplifier (LNA). In some embodiments, the pre-amplifier may also include a TIA-transimpedance amplifier, which converts a current signal to a voltage signal. For a linear detector system, input equivalent noise or noise equivalent power (NEP) measures how sensitive the light detector is to weak signals. Therefore, they can be used as indicators of the overall system performance. For example, the NEP of a light detector specifies the power of the weakest signal that can be detected and therefore it in turn specifies the maximum range of a LiDAR system. It is understood that various light detector optimization techniques can be used to meet the requirement of LiDAR system 300. Such optimization techniques may include selecting different detector structures, materials, and/or implement signal processing techniques (e.g., filtering, noise reduction, amplification, or the like). For example, in addition to or instead of using direct detection of return signals (e.g., by using TOF), coherent detection can also be used for a light detector. Coherent detection allows for detecting amplitude and phase information of the received light by interfering the received light with a local oscillator. Coherent detection can improve detection sensitivity and noise immunity.
Steering mechanism 340 can be used with the transceiver (e.g., transmitter 320 and optical receiver and light detector 330) to scan the FOV for generating an image or a 3D point cloud. As an example, to implement steering mechanism 340, a two-dimensional mechanical scanner can be used with a single-point or several single-point transceivers. A single-point transceiver transmits a single light beam or a small number of light beams (e.g., 2-8 beams) to the steering mechanism. A two-dimensional mechanical steering mechanism comprises, for example, polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s), or a combination thereof. In some embodiments, steering mechanism 340 may include non-mechanical steering mechanism(s) such as solid-state steering mechanism(s). For example, steering mechanism 340 can be based on tuning wavelength of the laser light combined with refraction effect, and/or based on reconfigurable grating/phase array. In some embodiments, steering mechanism 340 can use a single scanning device to achieve two-dimensional scanning or two devices combined to realize two-dimensional scanning.
As another example, to implement steering mechanism 340, a one-dimensional mechanical scanner can be used with an array or a large number of single-point transceivers. Specifically, the transceiver array can be mounted on a rotating platform to achieve 360-degree horizontal field of view. Alternatively, a static transceiver array can be combined with the one-dimensional mechanical scanner. A one-dimensional mechanical scanner comprises polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s) for obtaining a forward-looking horizontal field of view. Steering mechanisms using mechanical scanners can provide robustness and reliability in high volume production for automotive applications.
As another example, to implement steering mechanism 340, a two-dimensional transceiver can be used to generate a scan image or a 3D point cloud directly. In some embodiments, a stitching or micro shift method can be used to improve the resolution of the scan image or the field of view being scanned. For example, using a two-dimensional transceiver, signals generated at one direction (e.g., the horizontal direction) and signals generated at the other direction (e.g., the vertical direction) may be integrated, interleaved, and/or matched to generate a higher or full resolution image or 3D point cloud representing the scanned FOV.
Some implementations of steering mechanism 340 comprise one or more optical redirection elements (e.g., mirrors or lens) that steer return light signals (e.g., by rotating, vibrating, or directing) along a receive path to direct the return light signals to optical receiver and light detector 330. The optical redirection elements that direct light signals along the transmitting and receiving paths may be the same components (e.g., shared), separate components (e.g., dedicated), and/or a combination of shared and separate components. This means that in some cases the transmitting and receiving paths are different although they may partially overlap (or in some cases, substantially overlap).
With reference still to
Control circuitry 350 can also be configured and/or programmed to perform signal processing to the raw data generated by optical receiver and light detector 330 to derive distance and reflectance information, and perform data packaging and communication to vehicle perception and planning system 220 (shown in
LiDAR system 300 can be disposed in a vehicle, which may operate in many different environments including hot or cold weather, rough road conditions that may cause intense vibration, high or low humidifies, dusty areas, etc. Therefore, in some embodiments, optical and/or electronic components of LiDAR system 300 (e.g., optics in transmitter 320, optical receiver and light detector 330, and steering mechanism 340) are disposed or configured in such a manner to maintain long term mechanical and optical stability. For example, components in LiDAR system 300 may be secured and sealed such that they can operate under all conditions a vehicle may encounter. As an example, an anti-moisture coating and/or hermetic sealing may be applied to optical components of transmitter 320, optical receiver and light detector 330, and steering mechanism 340 (and other components that are susceptible to moisture). As another example, housing(s), enclosure(s), and/or window can be used in LiDAR system 300 for providing desired characteristics such as hardness, ingress protection (IP) rating, self-cleaning capability, resistance to chemical and resistance to impact, or the like. In addition, efficient and economical methodologies for assembling LiDAR system 300 may be used to meet the LiDAR operating requirements while keeping the cost low.
It is understood by a person of ordinary skill in the art that
The components shown in
As described above, some LiDAR systems use the time-of-flight (TOF) of light signals (e.g., light pulses) to determine the distance to objects in a light path. For example, with reference to
Referring back to
By directing many light pulses, as depicted in
If a corresponding light pulse is not received for a particular transmitted light pulse, then it may be determined that there are no objects within a detectable range of LiDAR system 500 (e.g., an object is beyond the maximum scanning distance of LiDAR system 500). For example, in
In
The density of a point cloud refers to the number of measurements (data points) per area performed by the LiDAR system. A point cloud density relates to the LiDAR scanning resolution. Typically, a larger point cloud density, and therefore a higher resolution, is desired at least for the region of interest (ROI). The density of points in a point cloud or image generated by a LiDAR system is equal to the number of pulses divided by the field of view. In some embodiments, the field of view can be fixed. Therefore, to increase the density of points generated by one set of transmission-receiving optics (or transceiver optics), the LiDAR system may need to generate a pulse more frequently. In other words, a light source with a higher pulse repetition rate (PRR) is needed. On the other hand, by generating and transmitting pulses more frequently, the farthest distance that the LiDAR system can detect may be limited. For example, if a return signal from a distant object is received after the system transmits the next pulse, the return signals may be detected in a different order than the order in which the corresponding signals are transmitted, thereby causing ambiguity if the system cannot correctly correlate the return signals with the transmitted signals.
To illustrate, consider an exemplary LiDAR system that can transmit laser pulses with a repetition rate between 500 kHz and 1 MHz. Based on the time it takes for a pulse to return to the LiDAR system and to avoid mix-up of return pulses from consecutive pulses in a conventional LiDAR design, the farthest distance the LiDAR system can detect may be 300 meters and 150 meters for 500 kHz and 1 MHz, respectively. The density of points of a LiDAR system with 500 kHz repetition rate is half of that with 1 MHz. Thus, this example demonstrates that, if the system cannot correctly correlate return signals that arrive out of order, increasing the repetition rate from 500 kHz to 1 MHz (and thus improving the density of points of the system) may reduce the detection range of the system. Various techniques are used to mitigate the tradeoff between higher PRR and limited detection range. For example, multiple wavelengths can be used for detecting objects in different ranges. Optical and/or signal processing techniques are also used to correlate between transmitted and return light signals.
Various systems, apparatus, and methods described herein may be implemented using digital circuitry, or using one or more computers using well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include, or be coupled to, one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, etc.
Various systems, apparatus, and methods described herein may be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computers are located remotely from the server computers and interact via a network. The client-server relationship may be defined and controlled by computer programs running on the respective client and server computers. Examples of client computers can include desktop computers, workstations, portable computers, cellular smartphones, tablets, or other types of computing devices.
Various systems, apparatus, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, e.g., in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method processes and steps described herein, including one or more of the steps of
A high-level block diagram of an exemplary apparatus that may be used to implement systems, apparatus and methods described herein is illustrated in
Processor 610 may include both general and special purpose microprocessors and may be the sole processor or one of multiple processors of apparatus 600. Processor 610 may comprise one or more central processing units (CPUs), and one or more graphics processing units (GPUs), which, for example, may work separately from and/or multi-task with one or more CPUs to accelerate processing, e.g., for various image processing applications described herein. Processor 610, persistent storage device 620, and/or main memory device 630 may include, be supplemented by, or incorporated in, one or more application-specific integrated circuits (ASICs) and/or one or more field programmable gate arrays (FPGAs).
Persistent storage device 620 and main memory device 630 each comprise a tangible non-transitory computer readable storage medium. Persistent storage device 620, and main memory device 630, may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices.
Input/output devices 690 may include peripherals, such as a printer, scanner, display screen, etc. For example, input/output devices 690 may include a display device such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor for displaying information to a user, a keyboard, and a pointing device such as a mouse or a trackball by which the user can provide input to apparatus 600.
Any or all of the functions of the systems and apparatuses discussed herein may be performed by processor 610, and/or incorporated in, an apparatus or a system such as LiDAR system 300. Further, LiDAR system 300 and/or apparatus 600 may utilize one or more neural networks or other deep-learning techniques performed by processor 610 or other systems or apparatuses discussed herein.
One skilled in the art will recognize that an implementation of an actual computer or computer system may have other structures and may contain other components as well, and that
LiDAR system 700 is a dual scanner LiDAR system comprising a first optical scanner and a second optical scanner. The first optical scanner comprises first polygon 702, transceiver 706, oscillating mirror 710 with a steering mechanism comprising corresponding motor 714, and detectors 718. The second optical scanner comprises second polygon 704, transceiver 708, oscillating mirror 712 with a steering mechanism comprising corresponding motor 716, and detector 720. A multiple seed laser device, as described in detail below, can be configured to provide a plurality of output light beams to the optical scanners of LiDAR system 700. For example, each of the plurality of output light beams from a multiple-seed laser device may be provided to a respective optical scanner of LiDAR system 700.
In one embodiment, the first optical scanner may further comprise a first oscillating mirror 710/corresponding motor 714 positioned lower than the first polygon mirror 702 in a vertical direction (i.e., on a different vertical plane) to direct a first output light beam to the first polygon mirror 702; where the second optical scanner further comprises a second oscillating mirror 712/corresponding motor 716 positioned generally on a same horizontal plane as the second polygon mirror 704 (i.e., positioned to the side of second polygon mirror 704) to direct a second output light beam to the second polygon mirror 704. In some embodiments, each of the plurality of output light beams may be provided to a respective transmitter channel of a plurality of transmitter channels, where the plurality of transmitter channels shares a single optical scanner of the LiDAR system 700.
In one embodiment, the first optical scanner of LiDAR system 700 comprises a first polygon mirror 702 and the second optical scanner of LiDAR system 700 comprises a second polygon mirror 704, where the width of a facet 724 of the first polygon mirror 702 is greater than the width of a facet 726 of the second polygon mirror 704, such that the scanning range of the horizontal direction of the first polygon mirror 702 is greater than that of the second polygon mirror 704. Likewise, the height of a facet 724 of the first polygon mirror 702 may be smaller than the height of a facet 726 of the second polygon mirror 714 such that the scanning range of the vertical direction of the first polygon mirror 702 is smaller than the scanning range of the vertical direction of the second polygon mirror 704. For example, the second polygon mirror 704 may be about twice as tall as the first polygon mirror 702 and about half as wide as the first polygon mirror 702.
Continuing to refer to
In various embodiments, LiDAR system 700 may comprise one or more additional windows; transceivers; detectors; optics, etc. In addition, LiDAR system 700 may comprise one or more bandpass filters (not shown). For example, each of the bandpass filters may be configured to filter out-of-bandwidth light for a corresponding scanner, thereby reducing optical interference between optical scanners. Further, LiDAR system 700 may comprise one or more processors (not shown) configured to process and merge output data provided by the one or more optical scanners to provide a unified point-cloud data output. For example, a vehicle comprising LiDAR system 700 make take an action based on the unified point-cloud data output.
Typically, a pulsed fiber laser source includes a single wavelength seed laser. Therefore, seed laser pre-amplifiers can be configured to provide a plurality of amplified output light beams to the optical scanners of LiDAR system 700. For example, each of the plurality of amplified output light beams from a plurality of seed laser pre-amplifiers may be provided to a respective optical scanner of LiDAR system 700.
The doped optical fiber 816 is optically coupled to optical isolator and traffic access point (TAP) unit 804 and photodetector 828. The optical isolator and TAP unit 804 includes an optical isolator that allows optical signal to travel only in one direction. For example, the optical isolator allows the amplified optical signals to travel from optical fiber 816 to other optical components 810 but not backward. Thus, the optical isolator prevents undesired feedback or reflection. The TAP is an access point that provides real-time monitoring of the optical signals. Photodetector 828 receives at least a portion of the amplified optical signals via optical fiber 818 and provides measurements of the output power of the amplified optical signals. The amplified optical signals pass through isolator and TAP unit 804 and are delivered to other optical components 810 (e.g., lens, mirrors, etc.).
While amplifier 800 can be acceptable for single seed laser source amplification, it is beneficial to have two or more scanners with two or more different wavelengths for various LiDAR applications, e.g., one scanner to cover an overall FOV and one or more other scanners to cover a smaller ROI region or regions. Typically, seed laser source amplification for such applications requires a costly solution with two or more separate laser sources having corresponding separate amplifier sections. However, instead of having two separate laser sources, multiple (two or more) seed lasers can share the same amplifier sections as described below. This solution can save space and cost in a multiple scanner LiDAR system and can also support flexible device configurations.
Seed lasers 902 and 904 may be any kind of laser with different wavelengths. For example, when the plurality of seed lasers comprise a first seed laser and a second seed laser, the first seed laser may be configured to provide a first seed light beam having a wavelength centered at a selected first wavelength (e.g., 1550 nm), and the second seed laser may be configured to provide a second seed light beam having a wavelength of centered at a selected second wavelength (e.g., 1535 nm), where the selected first wavelength and second wavelength are different wavelengths. Likewise, the pump laser can be any laser type having a wavelength that is lower than the seed laser output wavelengths. For example, when the first seed laser is configured to provide a first seed light beam centered at 1550 nm, and the second seed laser is configured to provide a second seed light beam having a wavelength of centered at 1535 nm, the wavelength of the pump laser 950 may be 940 nm. Further, the embodiments herein should not be construed as being limited to fiber lasers and fiber amplifiers. Other types of lasers and amplifiers (e.g., diode lasers and semiconductor optical amplifiers) can also be used. In addition, the embodiments can be realized with free-space optics and/or optical fibers.
In some embodiments, the power ratio between the two frequencies of the two seed lasers can depend on a time delay between the two seed pulses entering the amplification medium (e.g., a time delay of about 100 nanoseconds). In such cases, it is possible to delay one of the seed pulses, so that they are interleaved in time. For example, the time delay between the two seed lasers can be optimized to reduce non-linear effects (e.g., wavelength drifting, spectral broadening, etc.) that might otherwise cause the first arriving seed pulse to deplete the gain. Further, the spectrum may be broadened if the output power intensity is too high (e.g., excess output power intensity caused by high seed power, high gain, high pump power, etc.), and a bandpass filter (not shown) may be included to start to cut off power in the event of an excessive output power intensity condition.
In an embodiment, jitter between the seed lasers may be controlled to be less than a threshold value (e.g., 100 pico seconds). For example, a polarization combiner (not shown) may be used for beam combining. The polarization combiner can have, e.g., less than 20 dB extinction on the other wavelength. Further, in some embodiments, polarization-maintaining fiber may be used in the laser device 900.
Seed lasers 902 and 904 may each include a master oscillator that can provide continuous wave laser light or pulsed laser light. For example, seed lasers 902 and 904 may comprise one or more pulsed seed lasers that can be configured to generate pulsed laser light having one or more wavelengths (e.g., 1535 nm and 1550 nm). For example, multiple-seed laser device 900 may comprise a first seed laser, e.g., seed laser 902, configured to emit light pulses at a first pulse repetition rate, and a second seed laser, e.g., seed laser 904, configured to emit light pulses at a second pulse repetition rate while the first seed laser is emitting light pulses at the first pulse repetition rate, the second pulse repetition rate being different from the first pulse repetition rate. For example, the first seed laser and the second seed laser may be synchronized such that when the second seed laser emits light pulses, the first seed laser does not emit light pulses. Further, the first seed laser may be controlled, e.g., by one or more laser emission controllers (not shown), to continuously emit light pulses at the first pulse repetition rate, and the second seed laser may be controlled, e.g., by the one or more laser emission controllers (not shown), to intermittently emit light pulses at the second pulse repetition rate during one or more time intervals. For example, the one or more time intervals may be determined based on requirements of scanning one or more regions of interest (ROI) in a LiDAR system. Thus, the laser device 900 can be operated under a dual output mode or a single output mode (e.g., by turning off one or more seed lasers). For example, when there is only one operational seed laser (wavelength) at a time, the pump power can be reduced. Likewise, when one or more seed lasers are switched off, the pump current can be reduced.
WDM 906 includes a multiplexer that multiplexes or combines multiple input optical signals and delivers the combined signals to a single optical fiber. The multiple input optical signals are carried by input laser light having different wavelengths. The input laser light having different wavelengths can be delivered by multiple input optical fibers. In some embodiments, WDM 906 can be used to tune the wavelengths of input optical signals and/or to provide temperature tuning of input optical signals.
In one embodiment, WDM 906 is optically coupled to first seed laser 902 and second seed laser 904 via optical paths 903 and 905, respectively. Optical paths 903 and 905 can include an optical fiber and/or one or more free-space optics (e.g., lens) for delivering the seed laser light from seed lasers 902 and 904 to WDM 906. In addition to being coupled to seed lasers 902 and 904, the output end of WDM 906 is optically coupled to a first end (e.g., the front end) of first power amplification stage 908 via optical path 907.
Referring back to the multiple-stage amplifier in
In the configuration shown in
In an embodiment, the power pump 950 may be configured to provide a first portion of the pump power to the first amplification stage 908 and a second portion of the pump power to the second amplification stage 918. For example, the power pump 950 may be controlled in an open loop manner according to desired pump current level. For example, open loop control circuitry may be used to control the pump current to enable fast switching (on and off) of the laser device output. In the two-stage amplifier shown in
In device 900, power amplification stages 908 and 918 each comprise a fiber-based amplification medium (e.g., gain fibers 912 and 922) such as a rare earth doped optical fiber. Such an optical fiber can be, for example, a fiber doped with at least one of Ytterbium (Yb), Erbium (Er), Thulium (Tm), or Neodymium (Nd). The fiber-based amplification media included in power amplification stages 908 and 918 may be the same or different. For example, each of amplification stages 908 and 918 may comprise a 1550 nm single mode Er-doped optical fiber. It is understood that power amplification stages 908 and 918 can include any type of doped medium to produce output light having any desired wavelengths (e.g., 1030 nm, 1064 nm, 1530 nm, 1550 nm, 2 μm, or the like). Further, the fiber-based amplification media used in the power amplification stages (e.g., stages 908 and 918) can comprise single mode fibers, large mode area (LMA) fibers, double-clad fibers, or the like.
The first amplification stage 908 comprises a first optical combiner 910 configured to combine the first portion of the pump power obtained via fiber-based delivering media 911A with the seed light beams obtained via optical path 907. For example, the light coupling unit 919 may be a polarization beam splitter, where one or more of the optical paths/fiber-based delivering media of device 900, e.g., optical paths/fiber-based delivering media 903, 905, 907, 909, 911A and 911B, 917, and 929A and 929B, further comprises polarization maintaining fiber. As shown in
The first amplification stage further comprises a first amplification medium. For example, the first amplification stage 908 may be a fiber-based amplifier having a first gain fiber 912 configured to amplify, using the first portion of the pump power, the multiplexed seed light beams to obtain first amplified light beams. Amplification can be obtained by stimulated emission of photons from dopant ions in the doped optical fiber used in power amplification stage 908. In particular, the portion of the pump power delivered by fiber-based delivering medium 911 excites ions into an upper energy level from where they can decay via stimulated emission of a photon at the desired signal wavelength back to a lower energy level. As a result, power amplification stage 908 is a first amplification stage that amplifies the seed laser light from the multiple seed lasers, e.g., seed lasers 902 and 904, either collectively or individually (e.g., in an alternating pulse configuration) and generates the first amplified laser light.
First power amplification stage 908 further comprises an optical isolator 914 optically coupled to the output of gain fiber 912. Optical isolator 914 can pass optical signals from its input to its output but not backward. Thus, optical isolator 914 prevents undesired feedback or reflection. As a result, the first amplified laser light generated by gain fiber 912 may only propagate forward, but not backward.
First power amplification stage 908 further comprises an amplified spontaneous emission (ASE) filter 916 optically coupled to the output of optical isolator 914. ASE filter 916 is configured to remove at least a portion of ASE noise in the first amplification stage. A second end (e.g., the backend) of the first power amplification stage 908, e.g., the output of ASE filter 916, is optically coupled to a first end (e.g., the front end) of second power amplification stage 918 via optical path 917 to deliver the first amplified laser light output of the first power amplification stage 908 to second power amplification stage 918.
The second amplification stage 918 comprises a second optical combiner 920 configured to combine the second portion of the pump power obtained via fiber-based delivering media 911B with the first amplified light beams obtained via optical path 917. For example, the second optical combiner 920 may be a polarization combiner, where one or more of the optical paths/fiber-based delivering media of device 900, e.g., optical paths/fiber-based delivering media 903, 905, 907, 909, 911A and 911B, 917, and 929A and 929B, further comprises polarization maintaining fiber.
The second amplification stage 918 further comprises a second amplification medium. For example, the second amplification stage 918 may be a fiber-based amplifier having a second gain fiber 922 configured to amplify, using the second portion of the pump power, the first amplified light beams to obtain second amplified light beams. As discussed above, second power amplification stage 918 uses a portion of the pump power provided by optical power pump 950, delivered via light coupling unit 919, to further amplify the first amplified laser light received from the first power amplification stage 908. In particular, a portion of the pump power provided by optical power pump 950 is absorbed by the doped optical fiber, e.g., gain fiber 922, of power amplification stage 918 to excite dopant ions. The decay of the excited ions from an upper energy level to a lower energy level generates a second amplified laser light having the desired signal wavelength (e.g., 1550 nm).
In some embodiments, the first portion of the pump power may be less than the second portion of the pump power. In one example, about 50-90% (e.g., 70%) of the pump power provided by the optical power pump 950 is used for the second stage amplification performed by power amplification stage 918. The remaining about 10-50% (e.g., 30%) of the pump power is delivered to the power amplification stage 908 and is used for the first stage amplification. Thus, the configuration of device 900 shown in
Furthermore, because device 900 has two amplification stages, each stage can have a smaller power gain than that of a single stage amplifier while still achieving the same output power. For example, as shown in Table 1 below, the first amplification stage of a two-stage amplification device may have an output power of about 1-3 mW, and the second amplification stage may have an output power of about 100 mW. Table 1 also shows that the maximum power gain of any one of the two amplification stages in device 900 is about 18-20 dB, compared to about 34 dB for the single-stage simplification device 800. In some embodiments, the first amplification stage 908 may have a higher power gain than that of the second amplification stage 918, or vice versa. An amplification stage having a smaller power gain facilitates reducing ASE and improves the signal-to-noise ratio of amplification device 900. It is understood that device 900 may be configured such that more or less of pump power can be delivered to the first power amplification stage (e.g., stage 908) and therefore, the output power of the first amplification stage and the second amplification stage may vary from those shown in Table 1.
In an embodiment, the second amplification stage 918 may further comprise at least one of an optical mode stripper 924 coupled to the output of gain fiber 922. The optical mode stripper is configured to remove at least a portion of residual pump light from the second amplified laser light.
In an embodiment, the second amplification stage 918 may further comprise second optical isolator 926, e.g., coupled to the output of optical mode stripper 924. Second optical isolator 926, optionally in combination with a second ASE filter (not shown), may be configured to remove at least a portion of ASE noise in the second amplification stage 918.
In an embodiment, device 900 further comprises a demultiplexing or distributing WDM or wavelength divisional demultiplexer (WDDM) 928 coupled to the output of the second amplification stage 918, e.g., the output of second optical isolator 926. For example, a WDDM can include a splitter to demultiplex or distribute the combined optical signals carried by a single optical fiber to multiple output optical signals. The multiple output optical signals are carried by output laser light having multiple wavelengths. These output laser light having multiple wavelengths can be carried by multiple output optical fibers. In device 900, WDDM 928 is configured to demultiplex the amplified light beams to obtain a plurality of output light beams, e.g., output light beams 930 and 932, to be delivered to other optical components (e.g., polygon mirror, collimation lens, or the like) corresponding to the first and second seed lasers 902 and 904 via optical paths 929A and 929B, respectively. Optical paths 929A and 929B may include optical fiber and/or free-space optical components. For example, the output light beams 930 and 932 may be provided to optical components of a LiDAR system, e.g., LiDAR system 700. For example, the output light beams may be provided to a respective optical scanner of the optical scanners of LiDAR system 700.
One skilled in the art will appreciate that other configurations of the power pump with respect to the one or more amplification stages are possible in keeping with the embodiments described herein. Moreover, different configurations of the power pump with respect to the amplification stages are described in more detail in U.S. patent application Ser. No. 17/724,251, the content of which is incorporated herein by reference in its entirety for all purposes.
In some embodiments, method 1000 further includes steps of (not shown) combining the seed laser light and pump laser light corresponding to the first portion of the pump power to generate combined light; and delivering the combined light to the first power amplification stage. As shown in
In some embodiments, method 1000 further includes steps of (not shown) delivering the first amplified laser light from a second end of the first amplification stage to a first end of a second power amplification stage; and delivering the pump laser light to a first end of the second power amplification stage, where the first end and the second end of the first power amplification stage are different ends of the first power amplification stage.
In some embodiments, method 1000 further includes steps of (not shown) combining the first amplified laser light and the pump laser light to generate combined light; and delivering the combined light to the second power amplification stage. As shown in
In some embodiments, method 1000 further includes steps of (not shown) delivering the first amplified laser light to a first end of the second power amplification stage; and delivering a second portion of the pump laser light corresponding to the second portion of the pump power to the first end of the second power amplification stage, where the first end and the second end of the first power amplification stage are different ends of the second power amplification stage.
The foregoing specification is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the invention disclosed herein is not to be determined from the specification, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention.
This application claims priority to U.S. Provisional Patent Application Ser. No. 63/418,936, filed Oct. 24, 2022, entitled “Laser Source with Multiple Seeds for Lidar” the content of which is hereby incorporated by reference in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 20240134044 A1 | Apr 2024 | US |
| Number | Date | Country | |
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| 63418936 | Oct 2022 | US |
