阅读说明：本技术 用于实时lidar距离校准的系统和方法 (System and method for real-time LIDAR distance calibration ) 是由 S.奥斯伯恩 B.加森德 P-Y.德罗兹 L.沃赫特 I.伊尔达切 于 2020-03-04 设计创作，主要内容包括：本公开涉及光检测和测距(LIDAR)设备及其使用的相关方法。示例LIDAR设备包括发送器,发送器被配置为经由发送光路将一个或多个光脉冲发送到LIDAR设备的环境中。LIDAR设备还包括检测器,检测器被配置为检测一个或多个发送光脉冲的第一部分和一个或多个发送光脉冲的第二部分,使得检测器经由LIDAR设备内的内部光路在第一时间处接收一个或多个发送光脉冲的第一部分以及经由LIDAR设备的环境中的一个或多个对象的反射在第二时间处接收一个或多个发送光脉冲的第二部分。第二时间在第一时间之后发生。(The present disclosure relates to light detection and ranging (LIDAR) devices and related methods of use thereof. An example LIDAR device includes a transmitter configured to transmit one or more pulses of light into an environment of the LIDAR device via a transmit optical path. The LIDAR device also includes a detector configured to detect a first portion of the one or more transmitted light pulses and a second portion of the one or more transmitted light pulses, such that the detector receives the first portion of the one or more transmitted light pulses at a first time via an internal optical path within the LIDAR device and receives the second portion of the one or more transmitted light pulses at a second time via reflection by one or more objects in the environment of the LIDAR device. The second time occurs after the first time.)

1. A light detection and ranging (LIDAR) device, comprising:

a transmitter configured to transmit one or more pulses of light into an environment of the LIDAR device via a transmit optical path;

a detector configured to detect a first portion of the one or more transmitted light pulses and a second portion of the one or more transmitted light pulses such that the detector receives the first portion of the one or more transmitted light pulses at a first time via an internal optical path within the LIDAR device and receives the second portion of the one or more transmitted light pulses at a second time via reflection by one or more objects in the environment of the LIDAR device, wherein the second time occurs after the first time; and

a controller, wherein the controller is configured to determine a distance to at least one of the objects based in part on a difference between the second time and the first time.

2. The LIDAR device of claim 1, further comprising a light pipe within the LIDAR device, wherein the internal light path comprises a light path extending through the light pipe.

3. The LIDAR device of claim 2, wherein the light pipe is configured to receive a predetermined percentage of photons in one or more transmitted light pulses.

4. The LIDAR device of claim 3, wherein the predetermined percentage is less than ten percent.

5. The LIDAR device of claim 1, wherein the internal light path comprises a reflection by one or more components of the LIDAR device.

6. The LIDAR device of claim 1, further comprising:

a transparent structure, wherein the transmit light path passes through the transparent structure, wherein the internal light path comprises a reflection by the transparent structure.

7. The LIDAR device of claim 6, wherein the transparent structure is a dome configured to be mounted on a vehicle.

8. The LIDAR device of claim 6, wherein the transparent structure comprises an optical window.

9. The LIDAR device of claim 1, further comprising:

a mirror within the LIDAR device, wherein the transmit optical path comprises a reflection by the mirror, wherein the internal optical path comprises a reflection by the mirror.

10. The LIDAR device of claim 1, further comprising:

a light guide configured to guide light from an input end to an output end by total internal reflection or a reflective coating, wherein the transmission light path comprises a first light path extending from the input end of the light guide to the output end of the light guide, wherein the internal light path comprises the first light path and further comprises a second light path extending from the output end of the light guide to a detector.

11. The LIDAR device of claim 10, wherein the output end of the light guide comprises a mirror.

12. A method, comprising:

causing a transmitter of the LIDAR device to transmit a first light pulse into an environment of the LIDAR device via a transmit light path;

receiving, by a detector of the LIDAR device, a first portion of the first light pulse at a first time via an internal light path within the LIDAR device and a second portion of the first light pulse at a second time via reflection of one or more objects in an environment of the LIDAR device; and

determining a distance to at least one of the objects based in part on a difference between the second time and the first time.

13. The method of claim 12, further comprising:

a zero time is determined based on the first time.

14. The method of claim 12, further comprising:

causing the transmitter to transmit a subsequent plurality of light pulses via a transmit light path, wherein each subsequent pulse is excited according to a predetermined light pulse schedule;

receiving, by the detector, a subsequent reflected light pulse at a subsequent time via reflection by one or more objects in the environment of the LIDAR device; and

determining a distance to the respective object based on the respective subsequent time, the predetermined light pulse schedule and the first time.

15. A method, comprising:

positioning a mirror relative to a transmitter of a LIDAR device, wherein the transmitter is configured to transmit at least one light pulse;

causing the transmitter to transmit a first light pulse to interact with a mirror, wherein positioning of the mirror is performed such that the first light pulse is directed to an internal light path within the LIDAR device;

receiving, by a detector of the LIDAR device, a first light pulse at a first time via an internal light path; and

the zero time is determined based in part on the first time.

16. The method of claim 15, further comprising:

repositioning the mirror so as to direct a subsequent light pulse into an environment of the LIDAR device via a transmit light path;

causing the transmitter to transmit a subsequent plurality of light pulses via a transmit optical path;

receiving, by the detector, a subsequent reflected light pulse at a subsequent time via reflection by one or more objects in the environment of the LIDAR device; and

determining a distance to at least one of the objects based on a difference of the respective subsequent time and the zero time.

17. The method of claim 16, wherein the subsequent light pulse is excited according to a predetermined light pulse schedule, and wherein the distance to the object is determined further based on the predetermined light pulse schedule.

18. The method of claim 15, wherein the mirror comprises a rotatable mirror.

19. The method of claim 18, wherein the rotatable mirror comprises a triangular or rectangular prism shape, wherein the rotatable mirror comprises three or four reflective surfaces.

20. The method of claim 19, wherein positioning and repositioning the mirror comprises causing a motor to rotate the rotatable mirror about an axis of rotation to adjust respective angles of the three or four reflective surfaces.

Background

Conventional light detection and ranging (LIDAR) systems may utilize a light emitting transmitter (e.g., a laser diode) to emit light pulses into the environment. Emitted light pulses that interact with (e.g., reflect from) objects in the environment may be received by a receiver (e.g., photodetector) of the LIDAR system. Distance information about objects in the environment may be determined based on a time difference between an initial time of transmitting the light pulse and a subsequent time of receiving the reflected light pulse.

Disclosure of Invention

The present disclosure relates generally to certain aspects of optical systems (e.g., LIDAR systems) and their transmitter and receiver subsystems.

In a first aspect, a light detection and ranging (LIDAR) device is provided. The LIDAR device includes a transmitter configured to transmit light pulses into an environment of the LIDAR device via a transmit light path. The LIDAR device also includes a detector configured to detect a first portion of the transmitted light pulse and a second portion of the transmitted light pulse, such that the detector receives the first portion of the transmitted light pulse at a first time via an internal optical path within the LIDAR device and receives the second portion of the transmitted light pulse at a second time via reflection of an object in the environment of the LIDAR device. The second time occurs after the first time. The LIDAR device also includes a controller configured to determine a distance to the object based on a difference between the second time and the first time.

In a second aspect, a method is provided. The method includes causing a transmitter of the LIDAR device to transmit a first light pulse into an environment of the LIDAR device via a transmit light path. The method also includes receiving, by a detector of the LIDAR device, a first portion of the first light pulse at a first time via an internal light path within the LIDAR device, and receiving a second portion of the first light pulse at a second time via reflection of an object in an environment of the LIDAR device. Still further, the method further includes determining a distance to the object based on a difference between the second time and the first time.

In a third aspect, a method is provided. The method includes positioning a mirror relative to a transmitter of the LIDAR device. The transmitter is configured to transmit at least one light pulse. The method also includes causing the transmitter to transmit a first light pulse to interact with the mirror. The positioning of the mirror is performed such that the first light pulse is directed to an internal light path within the LIDAR device. The method also includes receiving, by a detector of the LIDAR device, a first light pulse at a first time via an internal light path. The method also includes determining a zero time based on the first time.

Other aspects, embodiments, and implementations will become apparent to those of ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings where appropriate.

Drawings

Fig. 1 shows an optical system according to an example embodiment.

Fig. 2A illustrates a transceiver according to an example embodiment.

Fig. 2B illustrates a transceiver according to an example embodiment.

Fig. 2C shows a transceiver according to an example embodiment.

Fig. 3A shows a side view of an optical system according to an example embodiment.

Fig. 3B shows a side view of an optical system according to an example embodiment.

Fig. 4 shows an optical system according to an example embodiment.

Fig. 5A shows a carrier according to an example embodiment.

Fig. 5B shows a carrier according to an example embodiment.

Fig. 5C shows a carrier according to an example embodiment.

Fig. 5D shows a carrier according to an example embodiment.

Fig. 5E shows a carrier according to an example embodiment.

Fig. 6 shows a method according to an example embodiment.

Fig. 7 shows a method according to an example embodiment.

Detailed Description

Example methods, devices, and systems are described herein. It should be understood that the words "example" and "exemplary" are used herein to mean "serving as an example, instance, or illustration. Any embodiment or feature described herein as "exemplary" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or features. Other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented herein.

Accordingly, the example embodiments described herein are not meant to be limiting. As generally described herein and illustrated in the figures, the various aspects of the present disclosure may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.

Furthermore, the features shown in each of the figures may be used in combination with each other, unless the context indicates otherwise. Thus, the drawings are to be generally regarded as constituting aspects of one or more overall embodiments, and it is to be understood that not all illustrated features are essential to each embodiment.

Summary of the invention

The LIDAR system may obtain spatial distance information about the environment by measuring a round trip time between a first time (e.g., a time at which a light pulse is emitted) and a second time (e.g., a time at which the light pulse is received after interacting with the environment). However, establishing an absolute time reference for a first time (e.g., the time at which a light pulse is emitted from the LIDAR) may be challenging because of the time-varying delays (e.g., limited RC response times) that may be difficult to control or poorly controlled electronic and/or data processing components. For example, a delay may be introduced between the time the controller indicates laser diode firing (fire) and the time the light pulse is actually emitted from the laser diode. Therefore, to ensure accurate and repeatable distance determination in a LIDAR system, it is desirable to establish a "well-known" first time (e.g., time zero) when a light pulse is transmitted.

In some embodiments, optical feedback, such as internal system reflections, may be advantageously utilized to determine the actual excitation time of the light pulse. That is, at the time of the excitation light pulse, some portion of the light may be reflected, routed, or otherwise received by the LIDAR receiver. This portion of the light is received almost instantaneously after being emitted from the laser diode. As such, a "time zero" may be determined based on the initial signal from the receiver. Thereafter, after the remaining portion of the light pulse interacts with the environment, a second time may be defined by a subsequent signal from the receiver, the second time indicating a round trip time required for the light to travel outward toward the environment and back to the LIDAR system. In such a case, the first time (e.g., time zero) may be subtracted from the second time to obtain a time delay from transmission to reception of the signal representing a true (or at least more accurate) round trip time.

In some embodiments, the LIDAR system may include a light pipe configured to "extract" a small amount of light (e.g., 0.001% -5% of the photons of the light pulse) from the light pulse and route (e.g., divert) them toward a receiver. The light pipe length may be relatively short (e.g., 0.1-10 centimeters) relative to the distance to a given object in the environment (e.g., 1-100 meters). Thus, the light from the light pipe may represent a near-ideal temporal zero reference.

In other embodiments, the LIDAR system may include a dome or window structure. In such a case, at least a portion of the light pulse may be reflected (directly or indirectly) from the inner surface of the dome or window. These reflections can be exploited to find a time zero reference.

It will be understood that LIDAR systems having other arrangements and/or components are possible and contemplated. For example, a LIDAR system may include one or more light emitter devices configured to emit light toward an environment of the LIDAR system via one or more optical elements. In some embodiments, the optical element may include a Fast Axis Collimation (FAC) lens and/or a shared lens. In some embodiments, the shared lens may be configured to direct light to the environment and focus incident light onto one or more photodetectors of the LIDAR system. In some embodiments, the optical element may additionally or alternatively comprise a planar waveguide structure and/or a light guide manifold.

In an alternative example, a LIDAR having a rotating mirror (e.g., a three-sided or four-sided reflective prism) may direct light pulses in a scanning manner to the environment. In such a case, at least a portion of the light from the light pulse may be reflected from the rotating mirror back to the receiver. For example, when a light pulse interacts with the surface of the rotating mirror, a portion of the photons may be reflected back to the receiver (either directly or by stray light reflection). Additionally or alternatively, at least some of the photons may be directed back to the receiver when the reflective surface of the rotating mirror is perpendicular to the emission axis of the laser diode. In such a case, a temporal zero reference may be obtained based on the portion of light received by the receiver.

In some embodiments, the LIDAR may include a plurality of light emitters configured to emit light pulses into a plurality of light guiding channels in the light guiding manifold. The waveguide channels in the light guide manifold may be configured to route the light pulses to the plurality of output mirrors by total internal reflection. The output mirror is configured to direct the respective light pulses out of the plane of the light guide manifold (and out of the light guide) and towards the environment of the LIDAR. In such cases, some light from the light pulses may "spill" into the light guide manifold. Such light may be received by one or more detectors in the receive path. For example, one or more detectors may be optically coupled to a light guide manifold. In such an example, the portion of light from the light pulse may be used to determine a temporal zero reference.

Moreover, in some embodiments, such LIDAR systems may emit light pulses from multiple light emitters simultaneously or in very rapid succession (e.g., exciting within nanoseconds of each other) based on various excitation schedules. To help disambiguate the portion of light used for a given temporal zero reference, in some excitation schedules, a single channel may be excited at a time that is independent of the other channels. That is, the laser diodes may be excited at different times in time in order to distinguish between light received from different transmit channels, thereby allowing a zero time reference to be established from a particular transmitter to a particular receiver. For example, discrete light emitters corresponding to a single transmitter channel may be activated every few normal activation periods, at predetermined times, or at different times as desired.

Example optical systems

Fig. 1 shows an optical system 100 according to an example embodiment. The optical system 100 may include a light detection and ranging (LIDAR) device. The optical system 100 comprises a transmitter 110, the transmitter 110 being configured to transmit light pulses into the environment of the LIDAR device via a transmit light path 114. The light pulses may be emitted by the light emitter device 120. The light emitter device 120 may be configured to emit emitted light (e.g., pulses of infrared light). In some embodiments, the light emitter device 120 may include a laser diode (which may be comprised of a plurality of laser diode bars).

The optical system 100 also includes a receiver 160. In various embodiments, optical system 100 may include a transmit lens 112 and a receive lens 164 disposed along transmit optical path 114 and receive optical path 166, respectively. The receiver 160 includes a detector 162, the detector 162 configured to detect a first portion of the transmitted light pulse and a second portion of the transmitted light pulse, such that the detector 162 receives the first portion of the transmitted light pulse at a first time via the internal optical path 130 within the optical system 100 and receives the second portion of the transmitted light pulse at a second time via reflection by an object in the environment of the optical system 100. The second time occurs after the first time. For example, the second time may be 33 nanoseconds after the first time. In such a case, based on the speed of light, it may be determined that the second portion of the transmitted light pulse traveled 10 meters more than the first portion of the transmitted light pulse. Thus, it can be determined that the object is about 5 meters from the optical system along the transmit optical path 114 that transmits the light pulses.

In some embodiments, the detector 162 may include at least one of: silicon photomultiplier (SiPM) devices, single photon avalanche photodiodes (SPADs), Avalanche Photodiodes (APDs), or multi-pixel photon counters (MPPCs). It will be understood that other types of photodetector devices are possible and contemplated.

The optical system 100 also includes a controller 150. The controller 150 includes at least one of a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC). Additionally or alternatively, the controller 150 may include one or more processors 152 and memory 154. The one or more processors 152 may include a general-purpose processor or a special-purpose processor (e.g., a digital signal processor, etc.). The one or more processors 152 may be configured to execute computer-readable program instructions stored in the memory 154. As such, the one or more processors 152 may execute program instructions to provide at least some of the functions and operations described herein.

Memory 154 may include, or take the form of, one or more computer-readable storage media that may be read by or accessed by one or more processors 152. The one or more computer-readable storage media may include volatile and/or nonvolatile storage components (such as optical, magnetic, organic, or other types of memory or disk storage) that may be integrated in whole or in part with at least one of the one or more processors 152. In some embodiments, memory 154 may be implemented using a single physical device (e.g., one optical, magnetic, organic, or other memory or disk storage unit), while in other embodiments memory 154 may be implemented using two or more physical devices.

As previously described, memory 154 may include computer-readable program instructions related to the operation of optical system 100. As such, memory 154 may include program instructions to perform or facilitate some or all of the functions described herein. The controller 150 is configured to perform operations. In some embodiments, the controller 150 may perform operations by the processor 152 executing instructions stored in the memory 154.

The operations may include operating various elements of the optical system 100 to obtain distance information about the environment of the optical system 100. For example, the controller 150 may be configured to determine a distance to an object in the environment of the optical system 100 based on a difference between the second time and the first time. The controller 150 may also be configured to perform other operations, such as those operations related to the methods 600 and 700 as shown and described with respect to fig. 6 and 7. For example, the controller 150 may be configured to add or subtract a constant offset time. The constant offset time may correspond to an offset distance calculated by subtracting a difference between the second time and the first time from a total transmission time of the round trip object. In some embodiments, the offset distance may correspond to the time that the light travels along the distance of the internal light path 130. Other constant offset times are possible and contemplated.

In some embodiments, optical system 100 may include a light pipe 140 within optical system 100. In such a case, internal light path 130 may include a light path extending through light pipe 140. Light pipe 140 may include, for example, an opening between the transmitter 110 portion and the receiver 160 portion of optical system 100. Such an opening may allow a portion of the transmitted light pulse to "short-cut" through the opening for receipt by the detector 162 prior to receiving light from the reflected light pulse.

In some embodiments, light pipe 140 is configured to receive a predetermined percentage of photons in the transmitted light pulse. For example, the light pipe 140 may be positioned, sized, or otherwise selected to receive 0.00001%, 0.1%, 1%, 10%, or another predetermined percentage of photons in the transmitted light pulse. Additionally or alternatively, the predetermined percentage may be less than one or ten percent of the photons of the transmitted light pulse. Other predetermined percentages of transmitted light pulses are possible and are contemplated within the context of the present disclosure.

In various example embodiments, the internal optical path 130 may include a reflection of a portion of the transmitted light pulse by one or more components of the optical system 100.

Additionally or alternatively, the optical system 100 may include a transparent structure 180. For example, the transparent structure 180 may include an optical window 182 and/or a dome 184, the dome 184 configured to be mounted on a carrier (e.g., carrier 500 as shown and described with respect to fig. 5A-5E). In such a case, transmit optical path 114 passes through transparent structure 180, and internal optical path 130 includes reflection of at least a portion of the transmit light pulse by transparent structure 180.

In some embodiments, optical system 100 may include a mirror 170. In such a case, the transmit optical path 114 includes reflection by the mirror 170. Further, in such a case, the internal optical path 130 includes reflection of at least a portion of the transmitted light pulse by the mirror 170.

In some examples, the optical system 100 may include a light guide 142 configured to guide light from an input end to an output end by total internal reflection. In such a case, the transmit optical path 114 includes a first optical path that extends from the input end of the light guide 142 to the output end of the light guide 142. The internal optical path 130 comprises a first optical path and further comprises a second optical path extending from the input end of the light guide 142 to the output end of the light guide 142 and further to the detector 162.

In embodiments including light guide 142, the output end of light guide 142 may include a mirror 170.

Fig. 2A, 2B, and 2C illustrate a transceiver 200, a transceiver 220, and a transceiver 230 according to example embodiments. Transceiver 200, transceiver 220, and/or transceiver 230 may include similar elements as optical system 100 shown and described with respect to fig. 1. Transceiver 200, transceiver 220, and/or transceiver 230 may include a transmitter portion and/or a receiver portion of a LIDAR system.

Referring to fig. 2A, the transceiver 200 may include a housing 210. The transceiver 200 may also include a transmitter 110 and a corresponding light emitter device 120 coupled to the housing 210. In some embodiments, the transmitter 110 may include a Fast Axis Collimation (FAC) lens 122 that may be optically coupled to the light emitter device 120. The transmitter may be configured to emit a pulse of light along a transmit optical path 114. Such light pulses may be transmitted into the environment of transceiver 200 through transmit lens 112.

In some embodiments, the FAC lens 122 may comprise a cylindrical lens. However, other optical elements (e.g., molded lenses) are possible and contemplated within the context of the present disclosure.

The transceiver 200 also includes a receiver 160. The receiver 160 includes a detector 162 optically coupled to a receive lens 164. As described elsewhere herein, the detector 162 may be a SiPM or another type of photodetector or photodetector array. The receiver 160 may be configured to receive light from the environment of the system along a receive optical path 166.

In some embodiments, the housing 210 may include an opening 202 disposed between the receiver 160 and the transmitter 110. The opening 202 may be located, shaped, sized, and/or otherwise configured to transmit a portion of the light emitted by the light emitter device 120 along the internal light path 130 toward the receiver 160 and the detector 162.

Fig. 2B shows a transceiver 220 according to an example embodiment. The transceiver 220 may be similar in some respects to the transceiver 220 shown and described with reference to fig. 2A. However, the transceiver 220 may additionally or alternatively include a light pipe 140 along at least a portion of the internal light path 130. The light pipe 140 may include an optical fiber, a light guide, or another structure configured to route light from a first location (e.g., the transmit light path 114) to a second location (e.g., the receive light path 166).

While fig. 2B illustrates the light pipe 140 as providing a substantially vertical path from the transmitter 110 to the receive light path 166, it will be understood that the light pipe 140 may be curved and/or include one or more branches.

In some embodiments, light pipe 140 may extend beyond the leakage path to specifically capture some light. In other embodiments, light pipe 140 may include one or more facets (facets) configured to collect light from transmit light path 114 and/or provide light to receiver 160. It should be understood that other optical configurations are possible and contemplated. In some embodiments, the light pipe 140 may not fill the entire opening 202 between the transmitter and receiver portions of the system. In such cases, light pipe 140 may be configured to utilize total internal reflection.

Fig. 2C shows a transceiver 230 according to an example embodiment. The transceiver 230 may be similar to the transceiver 200 and the transceiver 220 as shown and described with respect to fig. 2A and 2B. In some embodiments, transceiver 230 may include light pipe 140, and light pipe 140 may direct at least a portion of the light emitted along transmit light path 114 toward receive light path 166. For example, the optical fiber may be optically coupled between the transmit lens 112 and the receive lens 164. In other embodiments, the transmit lens 112 and the receive lens 164 may be physically connected and may be molded from the same material. Other ways of optically coupling the transmit lens 112 and the receive lens 164 are possible and contemplated.

In such a case, the light pulses emitted from the light emitter device 120 along the transmit light path 114 may interact with the transmit lens 112 and may be partially directed to the receive lens 164 via the light pipe 140. A portion of the light coupled into the receive lens 164 may be transferred to the detector 162. A portion of such light may range, for example, between parts per million (0.000001) to parts per trillion (0.000000000001). For example, between 0.00001% and 5% of the photons of a given light pulse may be diverted to detector 162 by light pipe 140. Other portions of light are possible and are contemplated within the context of the present disclosure.

Fig. 3A and 3B show side views of an optical system 300 according to an example embodiment. The optical system 300 may be similar to the optical system 100 shown and described with reference to fig. 1. For example, the optical system 300 may include a transmitter 110 and a receiver 160 that may be mounted to a rotatable stage 310. Rotatable table 310 may be configured to rotate about axis of rotation 302. In some embodiments, rotatable table 310 may be actuated by a stepper motor or another apparatus configured to mechanically rotate rotatable table 310.

In some embodiments, the optical system 300 may include a rotatable mirror 170. The rotatable mirror 170 may be shaped as a triangular prism or a rectangular prism, and may be configured to rotate about the rotation axis 304. The rotatable mirror 170 may include a plurality of reflective surfaces 172a, 172b, and 172 c.

Additionally or alternatively, optical system 300 may include optical window 180a and optical window 180 b. The reflective surfaces 172a-172c may be configured to reflect light pulses emitted by the optical system 100 along the transmit optical path 114. For example, the light pulse may be reflected into the environment of optical system 300 through optical window 180a and optical window 180 b. In addition, reflected light pulses from the environment may be reflected from the reflective surfaces 172a-172c along the receive optical path 166.

In this manner, the optical system 400 may be configured to transmit light pulses into a 360 degree region of the environment (e.g., about the z-axis) and receive reflected light pulses from the 360 degree region of the environment. Accordingly, optical system 400 may be configured to determine distance information based on a time-of-flight (time-of-flight) of the corresponding reflected light pulse.

Referring to fig. 3A, the rotatable mirror 170 may be rotated at an angle to reflect light along a primary reflection path 306 corresponding to a primary elevation angle 307. In some embodiments, at least a portion of the light emitted along the primary reflection path 306 may be reflected by the optical window 180a to reflect a portion of the light along the secondary reflection path 308. At least some of the portion of the light along the secondary reflected path 308 may be received by the receiver 160 (e.g., by the detector 162). Fig. 3A shows only one possible configuration of the rotatable mirror 170, however other multi-path reflections of light back to the detector 162 are possible and contemplated.

Referring to fig. 3B, in some embodiments, the rotatable mirror 170 may rotate so as to reflect light directly back to the receiver 160. The rotatable mirror 170 may be positioned such that a reflective surface (e.g., reflective surface 172b) reflects at least a portion of the light toward the receiver 160 and detector 162. That is, the reflective surface 172b can be positioned such that it is substantially perpendicular (e.g., orthogonal) with respect to the transmit optical path 114. In some embodiments, the rotatable mirror 170 mayTo rotate so as to reflect light toward light pipe 140. The portion of the light reflected back to the receiver 160 (by direct reflection from the reflective surface 172b and/or via the light pipe 140) may be detected by the detector 162. The corresponding signal may be used as the first time t₁. Similar to transceiver 200, the first time may be utilized to determine the transmission path length based on the subsequent pulse time.

Fig. 4 shows a cross-sectional view of an optical system 400 according to an example embodiment. Fig. 4 may include elements similar or identical to those of optical system 100 shown and described with reference to fig. 1.

For example, in some embodiments, the optical system 100 may include the light emitter device 120, the detectors 162a-162d, and the optical window 182. Optical system 400 may include a spacing structure 420 having a first surface 422 and a second surface 424. Spacer structure 420 may also include lumens 426a-426d extending through spacer structure 420.

One or more light emitter devices 120 may be coupled to the second surface 424 of the spacing structure 420. The light emitter devices 120 may each include one or more light emitting areas. As shown in fig. 4, second surface 424 may include an upper portion 424a and a lower portion 424 b. For example, upper portion 424a may define a first plane and lower portion 424b may define a second plane. Thus, in some embodiments, second surface 424 may include a "step down" to upper portion 424a of lower portion 424 b.

In some embodiments, the detectors 162a-162d may be disposed within the cavities 426a-426 d. For example, as shown, each chamber may include one detector device. Alternatively, multiple detector devices and/or detector arrays may be provided in a single chamber. The detectors 162a-162d may be configured to detect light emitted by one or more light emitter devices 120 after interaction with the external environment.

As additionally shown in fig. 4, intermediate cover 450 may be coupled to second surface 424 (e.g., lower surface 424b) of spacing structure 420. In an embodiment, the intermediate cover 450 may include a plurality of apertures 452a-452d that may be aligned with the cavities 426a-426d, respectively. In some embodiments, the holes 452a-452d may have a diameter of 150 microns. However, other apertures are possible and contemplated.

In some embodiments, the plurality of holes 452a-452d may include holes drilled or lithographically etched through a material that is substantially opaque to light emitted by the light emitter device 120. In other embodiments, the plurality of apertures 452a-452d may include optical windows that are substantially transparent to light emitted by the light emitter device 120.

Although FIG. 4 illustrates the intermediate cover 450 as including the plurality of apertures 452a-452d, it will be understood that in some embodiments, the plurality of apertures 452a-452d may be formed in the spacing structure 420. For example, the spacing structure 420 may include one or more holes that form the plurality of apertures 452a-452 d. In an exemplary embodiment, a plurality of apertures 452a-452d may be formed between the upper portion 424a and the lower portion 424b of the spacing structure 420.

Fig. 4 also shows optical window 182 including mounting surface 462. In some embodiments, optical window 182 may be substantially transparent to light emitted by light emitter device 120. The at least one FAC lens 122 may be coupled to a mounting surface 462 of the optical window 182. Further, at least one light guide 142 is coupled to the mounting surface 462 of the optical window 182. In an embodiment, the at least one light guide 142 may include reflective surfaces 467a-467d (e.g., mirror-like facets).

In some examples, the spacer 470 may be disposed between the upper portion 424a of the spacing structure 420 and the mounting surface 462 of the optical window 182. The spacer 470 may be selected such that the light emitter device 120 is disposed at a predetermined or desired location relative to the at least one FAC lens 122 and/or the at least one light guide 142. For example, the spacer 470 may be selected such that light emitted from the light emitter device 120 is efficiently collected by the at least one FAC lens 122 and efficiently coupled into the at least one light guide 142.

Although fig. 2 shows the shim 470 as being located near the side of the optical system 400, it will be understood that the shim 470 may be located elsewhere. For example, the spacer 470 may be disposed between the intermediate cover 450 and the mounting surface 462 of the optical window 182. Additionally or alternatively, the spacer 470 may be present in other areas of the optical system 100, for example, to provide a baffle (e.g., to prevent stray light from propagating).

The optical system 400 may additionally include a circuit board 490, the circuit board 490 may be physically coupled to the first substrate 410 by a controlled-collapsed solder ball(s) 480. Other ways of physically and/or electrically connecting the first substrate 410 to the circuit board 490 are possible and contemplated, such as, but not limited to, conventional solder balls, Ball Grid Arrays (BGAs), Land Grid Arrays (LGAs), conductive pastes, and other types of physical and electrical sockets.

In some embodiments, the reflective surfaces 467a-467d can be configured to direct light primarily in the + z direction to the environment of the optical system 400. Additionally or alternatively, at least a portion of the reflective surfaces 467a-467d can be configured to direct at least a portion of the emitted light in the-z direction (e.g., toward the respective detectors 162a-162 d). In other words, a first portion of each light pulse may be provided directly to the detectors 162a-162d, while a second portion of each light pulse may be directed to the environment of the optical system 400. In such a case, the first time t may be determined based on the arrival times of the first portion of light at the detectors 162a-162d₁. Further, the second time t may be determined based on the arrival times of the reflected portions of the second portion of light at the detectors 162a-162d₂. It will be appreciated that in some embodiments, stray light (e.g., due to direct or diffuse reflection within the optical system 400) may be utilized to determine the first time t₁。

Other ways of determining the zero time and/or receiving the time reference signal are contemplated within the context of the present disclosure. For example, the zero-point time t may be determined based on direct and/or multi-path reflections of the light pulses from the reflective surfaces 467a-467d, the light guide 142, the optical window 182, and/or other portions of the optical system 400₀Or another time reference signal.

Third, example Carrier

Fig. 5A, 5B, 5C, 5D and 5E illustrate a carrier 500 according to an example embodiment. The vehicle 500 may be a semi-autonomous vehicle or a fully autonomous vehicle. While fig. 5A-5E show the vehicle 500 as an automobile (e.g., a passenger van), it will be understood that the vehicle 500 may include another type of autonomous vehicle, robot, or drone that may navigate in its environment using sensors and other information about its environment.

The vehicle 500 may include one or more sensor systems 502, 504, 506, 508, and 510. In an example embodiment, one or more of the sensor systems 502, 504, 506, 508, and 510 may include the optical system 100 as shown and described with respect to fig. 1. For example, in such cases, sensor systems 502, 504, 506, 508, and 510 may include a LIDAR sensor having a plurality of light emitter devices arranged within an angular range relative to a given plane (e.g., an x-y plane).

One or more of the sensor systems 502, 504, 506, 508, and 510 may be configured to rotate about an axis (e.g., z-axis) perpendicular to a given plane in order to illuminate the environment around the vehicle 500 with pulses of light. Based on detecting various aspects of the reflected light pulse (e.g., elapsed time of flight, polarization, intensity, etc.), information about the environment may be determined.

In an example embodiment, the sensor systems 502, 504, 506, 508, and 510 may be configured to provide respective point cloud information that may be related to physical objects within the environment of the vehicle 500. While the vehicle 500 and the sensor systems 502, 504, 506, 508, and 510 are shown as including certain features, it will be understood that other types of sensor systems are contemplated within the scope of the present disclosure.

Example embodiments may include a system having a plurality of light emitter devices. The system may include a transmit block of the LIDAR device. For example, the system may be or may be part of a LIDAR device of a vehicle (e.g., a car, truck, motorcycle, golf cart, flying vehicle, boat, etc.). Each of the plurality of light emitter devices is configured to emit light pulses along a respective light beam elevation angle. The respective beam elevation angles may be based on a reference angle or reference plane, as described elsewhere herein. In some embodiments, the reference plane may be based on the axis of motion of the vehicle 500.

Although LIDAR systems having multiple light emitter devices are described and illustrated herein, LIDAR systems having fewer light emitter devices (e.g., a single light emitter device) are also contemplated. For example, light pulses emitted by a laser diode may be controllably directed around the environment of the system. The emission angle of the light pulses may be adjusted by a scanning device, such as, for example, a mechanical scanning mirror and/or a rotary motor. For example, the scanning device may rotate in a reciprocating motion about a given axis and/or rotate about a vertical axis. In another embodiment, the light emitter device may emit the light pulses towards a spin prism mirror, which may cause the light pulses to be emitted into the environment based on the angle of the prism mirror as it interacts with each light pulse. Additionally or alternatively, scanning optics and/or other types of electro-optic mechanical devices may scan the light pulses around the environment.

In some embodiments, a single light emitter device may emit light pulses according to a variable firing schedule and/or emit light pulses with variable power per shot, as described herein. That is, the transmit power and/or timing of each laser pulse or shot may be based on the respective elevation angle of the shot. Further, the variable shot schedule may be based on providing a desired vertical separation at a given distance from the LIDAR system or at a given distance from a surface of a given vehicle (e.g., front bumper) supporting the LIDAR system. As an example, when the light pulses from the light emitter device are directed downwards, the power per shot may be reduced due to the shorter expected maximum distance to the target. Conversely, light pulses emitted by the light emitter device at an elevation angle above the reference plane may have a relatively high power per shot in order to provide sufficient signal-to-noise ratio to adequately detect pulses traveling longer distances.

In some embodiments, each shot power/energy may be controlled for each shot in a dynamic manner. In other embodiments, the power/energy per shot may be controlled for a continuous set of several pulses (e.g., 10 light pulses). That is, the characteristics of the optical pulse train may be varied on a per pulse basis and/or on a per-pulse basis.

While fig. 5 shows various LIDAR sensors attached to carrier 500, it will be understood that carrier 500 may incorporate other types of sensors, such as multiple optical systems, as described herein. Additionally or alternatively, it will be appreciated that in some embodiments, one possible source of calibration light pulses may include light reflected from a surface at a known distance from the LIDAR system. As an example, light pulses reflected off a side mirror or another surface of the vehicle 500 may be utilized to determine t₁Or another time reference, in order to more accurately calculate the distance of light pulses reflected back to the LIDAR system from elsewhere within the environment of vehicle 500.

Example method

Fig. 6 shows a method 600 according to an example embodiment. It will be appreciated that the method 600 may include fewer or more steps or blocks than explicitly shown or otherwise disclosed herein. Further, the respective steps or blocks of the method 600 may be performed in any order and each step or block may be performed one or more times. In some embodiments, some or all of the blocks or steps of the method 600 may be performed by the controller 150 and/or other elements of the optical system 100 as shown and described with respect to fig. 1. Additionally or alternatively, method 600 may be performed with transceiver 200, transceiver 220, and/or transceiver 230 as shown and described with reference to fig. 2A, 2B, and 2C.

Block 602 includes causing a transmitter of the LIDAR device (e.g., transmitter 110) to transmit a first light pulse into an environment of the LIDAR device via a transmit optical path. The first light pulse may be, for example, at an initial trigger time t₀Infrared light pulses emitted from a laser diode. Light pulses having other wavelengths are also possible and contemplated.

Block 604 includes at a first time t, via an internal light path (e.g., internal light path 130) within a LIDAR device, by a detector (e.g., detector 162) of the LIDAR device_lReceiving a first portion of the first light pulse and via reflection of an object in the environment of the LIDAR device at a second time t₂A second portion of the first light pulse is received. In other words, a portion of the first light pulse may be reflected along the internal optical path,Routed or otherwise redirected to arrive at the detector at an earlier time than the remainder of the first light pulse. In some embodiments, the first portion of the first light pulse may be less than one-half nanosecond (e.g., 0.33 nanoseconds) or less than 50 picoseconds (e.g., 33 picoseconds) from its initial emission from the transmitter to the detector due to the short transmission path length of the internal light path (e.g., 10 centimeters, 1 centimeter, or less).

Block 606 includes determining a distance to the object based on a difference between the second time and the first time. By subtracting the first time from the second time, the transmission time to and from objects in the environment may be roughly estimated and/or determined. E.g. t for a first time₁50 picoseconds and a second time t₂33.38 nanoseconds, then t_{Difference (D)}T2-t1 ns 33.33 ns. Based on the speed of light (e.g. 3 x 10)⁸Meters/second), the total transmission distance may be about 10 meters. Thus, the object distance may be determined to be about half of the total transmission distance, i.e. 5 meters, taking into account the incoming and outgoing portions of the transmission distance.

In some embodiments, method 600 may further include determining a zero time (e.g., t) based on the first time₀). As an example, the zero point time may represent a time reference point to which one or more light pulse arrival times are compared to determine distance information. It will be appreciated that the zero time may represent a point of reference in time that may be modified (e.g., added or subtracted) by, for example, an additional constant offset time. The constant offset time may correspond to an offset distance calculated by subtracting a zero distance from the target distance. For example, the offset distance time may correspond to the time that the light travels along the internal path length distance or other type of adjusted distance.

In some embodiments, method 600 may additionally include causing the transmitter to transmit a subsequent plurality of light pulses via the transmit optical path. Each subsequent pulse is excited according to a predetermined light pulse schedule.

In such cases, the method 600 may further include receiving, by the detector, reflections of the object in the environment of the LIDAR device at the subsequent timesSubsequently reflecting the light pulse. Further, the method 600 may include determining a distance to the object based on the respective subsequent time, the predetermined light pulse schedule, and the first time. E.g. t₁Can be used as a time offset to be subtracted from a subsequent received pulse. In this way, t₁Only once, periodically, or occasionally. Further, the predetermined light pulse schedule may include a schedule for transmitting a plurality of light pulses each according to t₀After corresponding t_DelayAnd (4) transmitting. That is, for at t₀A certain time t later_DelayTo the subsequent light pulse emitted and at time t₃Where a reflected light pulse is received, the total transmission time may be represented by t_{Transmission of}＝t₃–t_Delay-t₁To calculate.

Fig. 7 shows a method 700 according to an example embodiment. It will be appreciated that the method 700 may include fewer or more steps or blocks than explicitly shown or otherwise disclosed herein. Further, the respective steps or blocks of the method 700 may be performed in any order and each step or block may be performed one or more times. In some embodiments, some or all of the blocks or steps of the method 700 may be performed by the controller 150 and/or other elements of the optical system 100 as shown and described with respect to fig. 1. Additionally or alternatively, method 700 may be performed with optical system 300 and/or optical system 400 as shown and described with reference to fig. 3A, 3B, and 4.

Block 702 includes positioning a mirror (e.g., mirror 170) relative to a transmitter (e.g., transmitter 110) of a LIDAR device. In such a case, the transmitter may be configured to transmit at least one light pulse. Referring to fig. 3A and 3B, positioning the mirror may include rotating the mirror 170 about the axis of rotation 304 to a desired position.

Block 704 includes causing the transmitter to transmit a first light pulse to interact with the mirror. The positioning of the mirror is performed such that the first light pulse is directed to an internal light path (e.g., internal light path 130) within the LIDAR device. As described elsewhere herein, the internal light path may include, for example, light pipe 140, light guide 142, mirror 170, optical window 182, and/or dome 184.

Block 706 includes at a first time t via an internal light path by a detector (e.g., detector 162) of a LIDAR device_lA first light pulse is received. As described with respect to optical system 300 and optical system 400, a first light pulse may be emitted toward the mirror and along the internal optical path to provide a temporal "reference pulse" from which subsequent pulse times may be calibrated, adjusted, and/or offset. In some embodiments, performing block 706 (e.g., obtaining light pulses via an internal optical path) may provide benefits in several respects. First, some angles of the rotatable mirror will not produce a reference pulse because substantially all of the light from a given light pulse may be diverted to the environment. Second, using a portion of the light pulse reflected back from outside the LIDAR device may cause objects in the scene that are very close to the device to cause a return that is "mixed" with the feedback pulse, making zero distance difficult or impossible to determine.

Block 708 includes determining a zero time (e.g., t) based on the first time₀). As an example, the zero point time may represent a time reference point to which one or more light pulse arrival times are compared to determine distance information.

In some embodiments, method 700 may additionally include repositioning the mirror to direct subsequent light pulses into the environment of the LIDAR device via the transmit optical path. In such a case, method 700 may include causing the transmitter to transmit a subsequent plurality of light pulses via the transmit optical path.

The method 700 may also include receiving, by the detector, a subsequent reflected light pulse at a subsequent time via reflection by an object in the environment of the LIDAR device.

Still further, the method 700 may include determining a distance to the object based on a difference between the respective subsequent time and the zero time. In some embodiments, subsequent light pulses may be excited according to a predetermined light pulse schedule. In such a case, the distance to the object may be further determined based on a predetermined light pulse schedule.

In an example embodiment, the mirror may be a rotatable mirror. For example, the rotatable mirror may have a triangular prism shape. In such a case, the rotatable mirror may have three reflective surfaces corresponding to each of the three facets of the triangular prism. In some embodiments, the rotatable mirror may have a rectangular prism shape. In such a case, the rotatable mirror may comprise four reflective surfaces corresponding to each of the four primary facets of the rectangular prism.

Additionally, positioning and repositioning the mirror may include causing a motor to rotate the rotatable mirror about an axis of rotation to adjust the respective angles of the three or four reflective surfaces.

The particular arrangements shown in the drawings should not be considered limiting. It should be understood that other embodiments may include more or less of each element shown in a given figure. In addition, some of the illustrated elements may be combined or omitted. Still further, the illustrative embodiments may include elements not shown in the figures.

The steps or blocks representing the processing of information may correspond to circuitry that may be configured to perform particular logical functions of the methods or techniques described herein. Alternatively or additionally, a step or block representing processing of information may correspond to a portion, segment, or module of program code (including associated data). The program code may include one or more instructions executable by a processor to implement specific logical functions or actions in a method or technique. The program code and/or related data may be stored on any type of computer-readable medium, such as a storage device including a diskette, hard drive, or other storage medium.

The computer-readable medium may also include non-transitory computer-readable media, such as computer-readable media for storing data for short periods of time (e.g., register memory, processor cache, and Random Access Memory (RAM)). The computer-readable medium may also include a non-transitory computer-readable medium for storing program code and/or data for a longer period of time. Thus, a computer-readable medium may include secondary or persistent long-term storage devices, such as Read Only Memory (ROM), optical or magnetic disks, compact disk read only memory (CD-ROM), for example. The computer readable medium may also be any other volatile or non-volatile storage system. The computer-readable medium may be considered a computer-readable storage medium, such as a tangible storage device.

While various examples and embodiments have been disclosed, other examples and embodiments will be apparent to those skilled in the art. The various disclosed examples and embodiments are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims.

This specification includes the following subject matter expressed in clauses 1-20: 1. a light detection and ranging (LIDAR) device, comprising: a transmitter configured to transmit one or more pulses of light into an environment of the LIDAR device via a transmit optical path; a detector configured to detect a first portion of the one or more transmitted light pulses and a second portion of the one or more transmitted light pulses such that the detector receives the first portion of the one or more transmitted light pulses at a first time via an internal optical path within the LIDAR device and receives the second portion of the one or more transmitted light pulses at a second time via reflection by one or more objects in the environment of the LIDAR device, wherein the second time occurs after the first time; and a controller, wherein the controller is configured to determine a distance to at least one of the objects based in part on a difference between the second time and the first time. 2. The LIDAR device of clause 1, further comprising a light pipe within the LIDAR device, wherein the internal light path comprises a light path extending through the light pipe. 3. The LIDAR device of clause 2, wherein the light pipe is configured to receive a predetermined percentage of photons in the one or more transmitted light pulses. 4. The LIDAR device of item 3, wherein the predetermined percentage is less than ten percent. 5. The LIDAR device of any of items 1-4, wherein the internal optical path comprises a reflection by one or more components of the LIDAR device. 6. The LIDAR device of any of clauses 1-5, further comprising: a transparent structure, wherein the transmission light path passes through the transparent structure, wherein the internal light path comprises a reflection by the transparent structure. 7. The LIDAR device of clause 6, wherein the transparent structure is a dome configured to be mounted on a carrier. 8. The LIDAR device of clauses 6 or 7, wherein the transparent structure comprises an optical window. 9. The LIDAR device of any of clauses 1-8, further comprising: a mirror within the LIDAR device, wherein the transmit optical path comprises reflection by the mirror, wherein the internal optical path comprises reflection by the mirror. 10. The LIDAR device of any of clauses 1-9, further comprising: a light guide configured to guide light from the input end to the output end by total internal reflection or a reflective coating, wherein the transmission light path comprises a first light path extending from the input end of the light guide to the output end of the light guide, wherein the internal light path comprises the first light path and further comprises a second light path extending from the output end of the light guide to the detector. 11. The LIDAR device of clause 10, wherein the output end of the light guide comprises a mirror. 12. A method, comprising: causing a transmitter of the LIDAR device to transmit a first light pulse into an environment of the LIDAR device via a transmit light path; receiving, by a detector of the LIDAR device, a first portion of the first light pulse at a first time via an internal light path within the LIDAR device, and a second portion of the first light pulse at a second time via reflection of one or more objects in an environment of the LIDAR device; and determining a distance to at least one of the objects based in part on a difference between the second time and the first time. 13. The method of clause 12, further comprising: a zero time is determined based on the first time. 14. The method of clause 12 or 13, further comprising: causing the transmitter to transmit a subsequent plurality of light pulses via the transmit optical path, wherein each subsequent pulse is excited according to a predetermined light pulse schedule; receiving, by a detector, a subsequent reflected light pulse at a subsequent time via reflection by one or more objects in the environment of the LIDAR device; and determining a distance to the respective object based on the respective subsequent time, the predetermined light pulse schedule and the first time. 15. A method, comprising: positioning a mirror relative to a transmitter of a LIDAR device, wherein the transmitter is configured to transmit at least one light pulse; causing a transmitter to transmit a first light pulse to interact with a mirror, wherein positioning of the mirror is performed such that the first light pulse is directed to an internal light path within the LIDAR device; receiving, by a detector of a LIDAR device, a first light pulse at a first time via an internal light path; and determining a zero time based in part on the first time. 16. The method of clause 15, further comprising: repositioning the mirror to direct a subsequent light pulse into an environment of the LIDAR device via the transmit light path; causing the transmitter to transmit a subsequent plurality of light pulses via the transmission optical path; receiving, by a detector, a subsequent reflected light pulse at a subsequent time via reflection by one or more objects in the environment of the LIDAR device; and determining a distance to at least one of the objects based on a difference of the respective subsequent time and the zero time. 17. The method of clause 16, wherein the subsequent light pulse is excited according to a predetermined light pulse schedule, and wherein the distance to the object is also determined based on the predetermined light pulse schedule. 18. The method of any of clauses 15-17, wherein the mirror comprises a rotatable mirror. 19. The method of clause 18, wherein the rotatable mirror comprises a triangular or rectangular prism shape, wherein the rotatable mirror comprises three or four reflective surfaces. 20. The method of clause 19, wherein positioning and repositioning the mirror comprises causing a motor to rotate a rotatable mirror about an axis of rotation to adjust the respective angles of the three or four reflective surfaces.