Patent Description:
Light detectors, such as photodiodes, single photon avalanche diodes (SPADs), or other types of avalanche photodiodes (APDs), can be used to detect light that is imparted on their surfaces (e.g., by outputting an electrical signal, such as a voltage or a current, that indicates an intensity of the light). Many types of such devices are fabricated out of semiconducting materials, such as silicon. In order to detect light over a large geometric area, multiple light detectors can be arranged as an array. These arrays are sometimes referred to as silicon photomultipliers (SiPMs) or multi-pixel photon counters (MPPCs).

Light detectors can be employed in a variety of systems, such as cameras, scanners, imagers, and motion sensors, among other examples. Some active sensing systems, such as light detection and ranging (LIDAR) systems, 3D scanners, computing tomography (CT) scanners, laser scanners, and infrared (IR) scanners, among other examples, may operate by emitting light and then detecting reflections (or other scattered portions) of the emitted light. For example, a LIDAR system can determine distances to environmental features while scanning through a scene to assemble a "point cloud" indicative of reflective surfaces in the environment. Individual points in the point cloud can be determined, for example, by transmitting a laser pulse and detecting a returning pulse, if any, reflected from an object in the environment, and then determining a distance to the object according to a time delay between the transmission of the pulse and the reception of the reflected pulse. <CIT> presents a waveguide with embedded mirrors including an in-coupling region for receiving input light into the waveguide and an out-coupling region for emitting output light from the waveguide. The mirrors include a plurality of in-coupling mirrors disposed within the in-coupling region of the waveguide and orientated to reflect the input light down the waveguide towards the out-coupling region as guided light. The mirrors further include a plurality of out-coupling mirrors disposed within the out-coupling region of the waveguide and orientated to reflect the guided light out of the waveguide as the output light. United States Patent Application Publication No. <CIT> presents a light guide which includes a body having an elongate shape and a plurality of light-reflecting faces and light-emitting faces extending along the body. The light-reflecting faces extend in a stepped fashion along the body in the direction of a longitudinal axis of the light guide and are configured to reflect light rays by the principle of total internal reflection. Each light-emitting face is disposed along the body opposite a corresponding light-reflecting face. Each light-emitting face is configured to emit light reflected by the corresponding light-reflecting face. The light-emitting faces are also disposed on the body in a stepped fashion. Steps of the light-emitting faces correspond to steps of the light-reflecting faces. In another aspect, the light-reflecting faces are separated by stepped-down faces. The stepped-down faces are oriented at a stepped-down angle in the range of about <NUM> and <NUM> degrees with respect to the longitudinal axis of the light guide. United States Patent Application Publication No. <CIT> relates to a waveguide diffuser for light detection using an aperture.

In one example, according to independent claim <NUM>, a light detection and ranging (LIDAR) device comprises a plurality of mirrors including a first mirror and a second mirror. The LIDAR device transmits a plurality of light beams to illuminate a scene. The plurality of transmitted light beams includes a first transmitted light beam and a second transmitted light beam. The plurality of transmitted light beams is arranged spatially based on a physical arrangement of the plurality of mirrors. The LIDAR device also comprises a light emitter and a waveguide. The waveguide is configured to guide emitted light from the light emitter toward the plurality of mirrors. The first mirror is configured to reflect a first portion of the light toward an output side of the waveguide as the first transmitted light beam. The second mirror reflects a second portion of the light toward the output side of the waveguide as the second transmitted light beam.

In another example, there is provided a method according to independent claim <NUM>.

One example system includes a lens. The lens may be used to focus light from a scene. However, the lens may also focus background light not intended to be observed by the system (e.g., sunlight). In order to selectively filter the light (e.g., separate background light from light corresponding to information within the scene), an opaque material (e.g., selectively etched metal, a glass substrate partially covered by a mask, etc.) may be placed behind the lens. The opaque material could be shaped as a slab, a sheet, or various other shapes in a variety of embodiments. Within the opaque material, an aperture may be defined. With this arrangement, a portion of, or the entirety of, the light focused by the lens could be selected for transmission through the aperture.

In the direction of propagation of the light transmitted through the aperture, the system may include at least one light detector (e.g., array of SPADs, etc.) arranged to detect at least a portion of the focused light transmitted through the aperture.

The system may also include a light source that emits light, and a waveguide that receives the emitted light at an input end of the waveguide. The waveguide guides the emitted light from the input end to an output end of the waveguide opposite the input end. The waveguide has a given side that extends from the input end to the output end. At or near the output end, the waveguide transmits at least a portion of the emitted light out of the given side and toward the lens. In general, the output end may be aligned with a path of the focused light propagating from the lens to the light detector. In one embodiment, the emitted light transmitted out of the waveguide may propagate through the same aperture through which the focused light from the lens is transmitted toward the light detector.

To facilitate transmitting the guided light out of the waveguide (and through the given side), in some examples, the system may include an output mirror disposed along a propagation path of the guided light propagating inside the waveguide (e.g., at or near the output end). The output mirror may be tilted toward the given side of the waveguide. As such, the output mirror may reflect the guided light (or a portion thereof) toward a particular region of the given side. For example, the particular region may be aligned with the path of the focused light transmitted through the aperture.

With this arrangement, the system may direct the emitted light in a transmit path that extends through the aperture and the lens (toward the scene); and the system may focus returning reflections of the emitted light in a receive path that extends through the same lens and the same aperture. Thus, in this example, the transmit and receive paths may be spatially co-aligned (e.g., because both paths are defined using the same aperture and the same lens).

By spatially aligning the transmit path with the receive path, the example system may reduce (or prevent) optical scanning distortions associated with parallax. For instance, if the transmit and receive paths were instead spatially offset relative to one another (e.g., mismatch between the respective pointing or viewing directions, etc.), a scanned representation of the scene could be affected by optical distortions such as parallax.

Other aspects, features, implementations, configurations, arrangements, and advantages are possible.

<FIG>, which is retained as an example useful for understanding the invention, is an illustration of a system <NUM> that includes an aperture. As shown, system <NUM> includes an array <NUM> of light detectors (exemplified by detectors <NUM> and <NUM>), an aperture 120a defined within an opaque material <NUM>, and a lens <NUM>. System <NUM> may measure light <NUM> reflected or scattered by an object <NUM> within a scene. In some instances, light <NUM> may also include light propagating directly from background sources (not shown) toward lens <NUM>. In some examples, system <NUM> may be included in a light detection and ranging (LIDAR) device. In one example, the LIDAR device may be used for navigation of an autonomous vehicle. In some instances, system <NUM>, or portions thereof, may be contained within an area that is unexposed to external light other than through lens <NUM>. This may reduce an amount of ambient light (which may affect measurements) reaching the detectors in array <NUM>.

Array <NUM> includes an arrangement of light detectors, exemplified by detectors <NUM> and <NUM>. In various instances, array <NUM> may have different shapes. As shown, array <NUM> has a rectangular shape. However, in other instances, array <NUM> may be circular or may have a different shape. The size of array <NUM> may be selected according to an expected cross-sectional area of light <NUM> diverging from aperture 120a. For example, the size of array <NUM> may be based on the distance between array <NUM> and aperture 120a, the distance between aperture 120a and lens <NUM>, dimensions of aperture 120a, optical characteristics of lens <NUM>, among other factors. In some instances, array <NUM> may be movable. For example, the location of array <NUM> may be adjustable so as to be closer to, or further from, aperture 120a. To that end, for instance, array <NUM> could be mounted on an electrical stage capable of translating in one, two, or three dimensions.

Further, in some implementations, array <NUM> may provide one or more outputs to a computing device or logic circuitry. For example, a microprocessor-equipped computing device may receive electrical signals from array <NUM> which indicate an intensity of light <NUM> incident on array <NUM>. The computing device may then use the electrical signals to determine information about object <NUM> (e.g., distance between object <NUM> and system <NUM>, etc.). In some instances, some or all of the light detectors within array <NUM> may be interconnected with one another in parallel. To that end, for example, array <NUM> may be a SiPM or an MPPC, depending on the particular arrangement and type of the light detectors within array <NUM>. By connecting the light detectors in a parallel circuit configuration, for instance, the outputs from the light detectors can be combined to effectively increase a detection area in which a photon in light <NUM> can be detected (e.g., shaded region of array <NUM> shown in <FIG>).

Light detectors <NUM>, <NUM>, etc., may include various types of light detectors. In one example, detectors <NUM>, <NUM>, etc., include SPADs. SPADs may employ avalanche breakdown within a reverse biased p-n junction (i.e., diode) to increase an output current for a given incident illumination on the SPAD. Further, SPADs may be able to generate multiple electron-hole pairs for a single incident photon. In another example, light detectors <NUM>, <NUM>, etc., may include linear-mode avalanche photodiodes (APDs). In some instances, APDs or SPADs may be biased above an avalanche breakdown voltage. Such a biasing condition may create a positive feedback loop having a loop gain that is greater than one. Further, SPADs biased above the threshold avalanche breakdown voltage may be single photon sensitive. In other examples, light detectors <NUM>, <NUM>, etc., may include photoresistors, charge-coupled devices (CCDs), photovoltaic cells, and/or any other type of light detector.

In some implementations, array <NUM> may include more than one type of light detector across the array. For example, array <NUM> can be configured to detect multiple predefined wavelengths of light <NUM>. To that end, for instance, array <NUM> may comprise some SPADs that are sensitive to one range of wavelengths and other SPADs that are sensitive to a different range of wavelengths. In some instances, light detectors <NUM> may be sensitive to wavelengths between <NUM> and <NUM> (visible and/or infrared wavelengths). Further, light detectors <NUM> may have various sizes and shapes within a given implementation or across various implementations. In some instances, light detectors <NUM>, <NUM>, etc., may include SPADs that have package sizes that are <NUM>%,. <NUM>%, or. <NUM>% of the area of array <NUM>.

Opaque material <NUM> (e.g., mask, etc.) may block a portion of light <NUM> from the scene (e.g., background light) that is focused by the lens <NUM> from being transmitted to array <NUM>. For example, opaque material <NUM> may be configured to block certain background light that could adversely affect the accuracy of a measurement performed by array <NUM>. Alternatively or additionally, opaque material <NUM> may block light in the wavelength range detectable by detectors <NUM>, <NUM>, etc. In one example, opaque material <NUM> may block transmission by absorbing a portion of incident light. In another example, opaque material <NUM> may block transmission by reflecting a portion of incident light. A non-exhaustive list of example implementations of opaque material <NUM> includes an etched metal, a polymer substrate, a biaxially-oriented polyethylene terephthalate (BoPET) sheet, or a glass overlaid with an opaque mask, among other possibilities. In some examples, opaque material <NUM>, and therefore aperture 120a, may be positioned at or near a focal plane of lens <NUM>.

Aperture 120a provides a port within opaque material <NUM> through which light <NUM> (or a portion thereof) may be transmitted. Aperture 120a may be defined within opaque material <NUM> in a variety of ways. In one example, opaque material <NUM> (e.g., metal, etc.) may be etched to define aperture 120a. In another example, opaque material <NUM> may be configured as a glass substrate overlaid with a mask, and the mask may include a gap that defines aperture 120a (e.g., via photolithography, etc.). In various implementations, aperture 120a may be partially or wholly transparent, at least to wavelengths of light that are detectable by light detectors <NUM>, <NUM>, etc. For example, where opaque material <NUM> is a glass substrate overlaid with a mask, aperture 120a may be defined as a portion of the glass substrate not covered by the mask, such that aperture 120a is not completely hollow but rather made of glass. Thus, in some instances, aperture 120a may be nearly, but not entirely, transparent to one or more wavelengths of light <NUM> (e.g., glass substrates are typically not <NUM>% transparent). Alternatively, in some instances, aperture 120a may be formed as a hollow region of opaque material <NUM>.

In some examples, aperture 120a (in conjunction with opaque material <NUM>) may be configured to spatially filter light <NUM> from the scene at the focal plane. To that end, for example, light <NUM> may be focused onto a focal plane along a surface of opaque material <NUM>, and aperture 120a may allow only a portion of the focused light to be transmitted to array <NUM>. As such, aperture 120a may behave as an optical pinhole. In one example, aperture 120a may have a cross-sectional area of between. <NUM><NUM> and. <NUM><NUM> (e.g.,. <NUM><NUM>). In other examples, aperture 120a may have a different cross-sectional area depending on various factors such as optical characteristics of lens <NUM>, distance to array <NUM>, noise rejection characteristics of the light detectors in array <NUM>, etc..

Thus, although the term "aperture" as used above with respect to aperture 120a may describe a recess or hole in an opaque material through which light may be transmitted, it is noted that the term "aperture" may include a broad array of optical features. In one example, as used throughout the description and claims, the term "aperture" may additionally encompass transparent or translucent structures defined within an opaque material through which light can be at least partially transmitted. In another example, the term "aperture" may describe a structure that otherwise selectively limits the passage of light (e.g., through reflection or refraction), such as a mirror surrounded by an opaque material. In one example, mirror arrays surrounded by an opaque material may be arranged to reflect light in a certain direction, thereby defining a reflective portion, which may be referred to as an "aperture".

Although aperture 120a is shown to have a rectangular shape, it is noted that aperture 120a can have a different shape, such as a round shape, circular shape, elliptical shape, among others. In some examples, aperture 120a can alternatively have an irregular shape specifically designed to account for optical aberrations within system <NUM>. For example, a keyhole shaped aperture may assist in accounting for parallax occurring between an emitter (e.g., light source that emits light <NUM>) and a receiver (e.g., lens <NUM> and array <NUM>). The parallax may occur if the emitter and the receiver are not located at the same position, for example. Other irregular aperture shapes are also possible, such as specifically shaped apertures that correspond with particular objects expected to be within a particular scene or irregular apertures that select specific polarizations of light <NUM> (e.g., horizontal or vertical polarizations).

Lens <NUM> may focus light <NUM> from the scene onto the focal plane where aperture 120a is positioned. With this arrangement, the light intensity collected from the scene, at lens <NUM>, may be focused to have a reduced cross-sectional area over which light <NUM> is projected (i.e., increasing the spatial power density of light <NUM>). For example, lens <NUM> may include a converging lens, a biconvex lens, and/or a spherical lens, among other examples. Alternatively, lens <NUM> can be implemented as a consecutive set of lenses positioned one after another (e.g., a biconvex lens that focuses light in a first direction and an additional biconvex lens that focuses light in a second direction). Other types of lenses and/or lens arrangements are also possible. In addition, system <NUM> may include other optical elements (e.g., mirrors, etc.) positioned near lens <NUM> to aid in focusing light <NUM> incident on lens <NUM> onto opaque material <NUM>.

Object <NUM> may be any object positioned within a scene surrounding system <NUM>. In implementations where system <NUM> is included in a LIDAR device, object <NUM> may be illuminated by a LIDAR transmitter that emits light (a portion of which may return as light <NUM>). In examples where the LIDAR device is used for navigation of an autonomous vehicle, object <NUM> may be or include pedestrians, other vehicles, obstacles (e.g., trees, debris, etc.), or road signs, among other types of objects.

As noted above, light <NUM> may be reflected or scattered by object <NUM>, focused by lens <NUM>, transmitted through aperture 120a in opaque material <NUM>, and measured by light detectors in array <NUM>. This sequence may occur (e.g., in a LIDAR device) to determine information about object <NUM>. In some instances, light <NUM> measured by array <NUM> may additionally or alternatively include light reflected or scattered off multiple objects, transmitted by a transmitter of another LIDAR device, ambient light, sunlight, among other possibilities.

In some examples, the wavelength(s) of light <NUM> used to analyze object <NUM> may be selected based on the types of objects expected to be within a scene and their expected distance from lens <NUM>. For example, if an object expected to be within the scene absorbs all incoming light of <NUM> wavelength, a wavelength other than <NUM> may be selected to illuminate object <NUM> and to be analyzed by system <NUM>. The wavelength of light <NUM> (e.g., if transmitted by a transmitter of a LIDAR device) may be associated with a source that generates light <NUM> (or a portion thereof). For example, if the light is generated by a laser diode, light <NUM> may comprise light within a wavelength range that includes <NUM> (or other infrared and/or visible wavelength). Thus, various types of light sources are possible for generating light <NUM> (e.g., an optical fiber amplifier, various types of lasers, a broadband source with a filter, etc.).

As shown, light <NUM> diverges as it propagates away from aperture 120a. Due to the divergence, a detection area at array <NUM> (e.g., shown as shaded area illuminated by light <NUM>) may be larger than a cross-sectional area of aperture 120a. An increased detection area (e.g., measured in m<NUM>) for a given light power (e.g., measured in W) may lead to a reduced light intensity (e.g., measured in <MAT>) incident on array <NUM>.

The reduction in light intensity may be particularly beneficial in instances where array <NUM> includes SPADs or other light detectors having high sensitivities. For example, SPADs derive their sensitivity from a large reverse-bias voltage that produces avalanche breakdown within a semiconductor. This avalanche breakdown can be triggered by the absorption of a single photon, for example. Once a SPAD absorbs a single photon and the avalanche breakdown begins, the SPAD cannot detect additional photons until the SPAD is quenched (e.g., by restoring the reverse-bias voltage). The time until the SPAD is quenched may be referred to as the recovery time. If additional photons are arriving at time intervals approaching the recovery time (e.g., within a factor of ten), the SPAD may begin to saturate, and the measurements by the SPAD may thus become less reliable. By reducing the light power incident on any individual light detector (e.g., SPAD) within array <NUM>, the light detectors (e.g., SPADs) in array <NUM> may remain unsaturated. As a result, the light measurements by each individual SPAD may have an increased accuracy.

<FIG> is another illustration of system <NUM>. As shown, system <NUM> also includes a light filter <NUM> and a light emitter <NUM>. Filter <NUM> may include any optical filter configured to selectively transmit light within a predefined wavelength range. For example, filter <NUM> can be configured to selectively transmit light within a visible wavelength range, an infrared wavelength range, or any other wavelength range of the light signal emitted by emitter <NUM>. For example, optical filter <NUM> may be configured to attenuate light of particular wavelengths or divert light of particular wavelengths away from the array <NUM>. For instance, optical filter <NUM> may attenuate or divert wavelengths of light <NUM> that are outside of the wavelength range emitted by emitter <NUM>. Therefore, optical filter <NUM> may, at least partially, reduce ambient light or background light from adversely affecting measurements by array <NUM>.

In various examples, optical filter <NUM> may be located in various positions relative to array <NUM>. As shown, optical filter <NUM> is located between lens <NUM> and opaque material <NUM>. However, optical filter <NUM> may alternatively be located between lens <NUM> and object <NUM>, between opaque material <NUM> and array <NUM>, combined with array <NUM> (e.g., array <NUM> may have a surface screen that optical filter <NUM>, or each of the light detectors in array <NUM> may individually be covered by a separate optical filter, etc.), combined with aperture 120a (e.g., aperture 120a may be transparent only to a particular wavelength range, etc.), or combined with lens <NUM> (e.g., surface screen disposed on lens <NUM>, material of lens <NUM> transparent only to a particular wavelength range, etc.), among other possibilities.

As shown in <FIG>, light emitter <NUM> emits a light signal to be measured by array <NUM>. Emitter <NUM> may include a laser diode, fiber laser, a light-emitting diode, a laser bar, a nanostack diode bar, a filament, a LIDAR transmitter, or any other light source. As shown, emitter <NUM> may emit light which is reflected by object <NUM> in the scene and ultimately measured (at least a portion thereof) by array <NUM>. In some examples, emitter <NUM> may be implemented as a pulsed laser (as opposed to a continuous wave laser), allowing for increased peak power while maintaining an equivalent continuous power output.

<FIG>, which is retained as an example useful for understanding the invention, is a simplified block diagram of a LIDAR device <NUM>. In some examples, LIDAR device <NUM> can be mounted to a vehicle and employed to map a surrounding environment (e.g., the scene including object <NUM>, etc.) of the vehicle. As shown, LIDAR device <NUM> includes a laser emitter <NUM> that may be similar to emitter <NUM>, a system <NUM> that may be similar to system <NUM>, a controller <NUM>, a rotating platform <NUM>, and one or more actuators <NUM>.

System <NUM> includes an array <NUM> of light detectors, an opaque material <NUM>, and a lens <NUM>, which can be similar, respectively, to array <NUM>, opaque material <NUM>, and lens <NUM>. It is noted that LIDAR device <NUM> may alternatively include more or fewer components than those shown. For example, LIDAR device <NUM> may include an optical filter (e.g., filter <NUM>). Thus, system <NUM> can be implemented similarly to system <NUM> and/or any other system herein.

Device <NUM> may operate emitter <NUM> to emit light <NUM> toward a scene that includes object <NUM>, similarly to, respectively, emitter <NUM>, light <NUM>, and object <NUM> of device <NUM>. To that end, in some implementations, emitter <NUM> (and/or one or more other components of device <NUM>) can be configured as a LIDAR transmitter of LIDAR device <NUM>. Device <NUM> may then detect reflections of light <NUM> returning from the scene to determine information about object <NUM>. To that end, in some implementations, array <NUM> (and/or one or more other components of system <NUM>) can be configured as a LIDAR receiver of LIDAR device <NUM>.

Controller <NUM> may be configured to control one or more components of LIDAR device <NUM> and to analyze signals received from the one or more components. To that end, controller <NUM> may include one or more processors (e.g., a microprocessor, etc.) that execute instructions stored in a memory (not shown) of device <NUM> to operate device <NUM>. Additionally or alternatively, controller <NUM> may include digital or analog circuitry wired to perform one or more of the various functions described herein.

Rotating platform <NUM> may be configured to rotate about an axis to adjust a pointing direction of LIDAR <NUM> (e.g., direction of emitted light <NUM> relative to the environment, etc.). To that end, rotating platform <NUM> can be formed from any solid material suitable for supporting one or more components of LIDAR <NUM>. For example, system <NUM> (and/or emitter <NUM>) may be supported (directly or indirectly) by rotating platform <NUM> such that each of these components moves relative to the environment while remaining in a particular relative arrangement in response to rotation of rotating platform <NUM>. In particular, the mounted components could be rotated (simultaneously) about an axis so that LIDAR <NUM> may adjust its pointing direction while scanning the surrounding environment. In this manner, a pointing direction of LIDAR <NUM> can be adjusted horizontally by actuating rotating platform <NUM> to different directions about the axis of rotation. In one example, LIDAR <NUM> can be mounted on a vehicle, and rotating platform <NUM> can be rotated to scan regions of the surrounding environment at various directions from the vehicle.

In order to rotate platform <NUM> in this manner, one or more actuators <NUM> may actuate rotating platform <NUM>. To that end, actuators <NUM> may include motors, pneumatic actuators, hydraulic pistons, and/or piezoelectric actuators, among other possibilities.

With this arrangement, controller <NUM> could operate actuator(s) <NUM> to rotate rotating platform <NUM> in various ways so as to obtain information about the environment. In one example, rotating platform <NUM> could be rotated in either direction about an axis. In another example, rotating platform <NUM> may carry out complete revolutions about the axis such that LIDAR <NUM> scans a <NUM>° field-of-view (FOV) of the environment. In yet another example, rotating platform <NUM> can be rotated within a particular range (e.g., by repeatedly rotating from a first angular position about the axis to a second angular position and back to the first angular position, etc.) to scan a narrower FOV of the environment. Other examples are possible.

Moreover, rotating platform <NUM> could be rotated at various frequencies so as to cause LIDAR <NUM> to scan the environment at various refresh rates. In one example, LIDAR <NUM> may be configured to have a refresh rate of <NUM>. For example, where LIDAR <NUM> is configured to scan a <NUM>° FOV, actuator(s) <NUM> may rotate platform <NUM> for ten complete rotations per second.

<FIG> illustrates a perspective view of LIDAR device <NUM>. As shown, device <NUM> also includes a transmitter lens <NUM> that directs emitted light from emitter <NUM> toward the environment of device <NUM>. To that end, <FIG> illustrates an example implementation of device <NUM> where emitter <NUM> and system <NUM> each have separate respective optical lenses <NUM> and <NUM>. However, in other examples, device <NUM> can be alternatively configured to have a single shared lens for both emitter <NUM> and system <NUM>. By using a shared lens to both direct the emitted light and receive the incident light (e.g., light <NUM>), advantages with respect to size, cost, and/or complexity can be provided. For example, with a shared lens arrangement, device <NUM> can reduce and/or prevent parallax associated with transmitting light <NUM> (by emitter <NUM>) from a different viewpoint than a viewpoint from which light <NUM> is received (by system <NUM>).

As shown in <FIG>, light beams emitted by emitter <NUM> propagate from lens <NUM> toward an environment of LIDAR <NUM>, and then return (e.g., after reflecting off one or more objects in the environment) as reflected light <NUM>. LIDAR <NUM> may then receive reflected light <NUM> (e.g., through lens <NUM>) and provide data pertaining to the one or more objects (e.g., distance between the one or more objects and the LIDAR <NUM>, etc.).

Further, as shown in <FIG>, rotating platform <NUM> mounts system <NUM> and emitter <NUM> in the particular relative arrangement shown. By way of example, if rotating platform <NUM> rotates about axis <NUM>, the pointing directions of system <NUM> and emitter <NUM> may simultaneously change according to the particular relative arrangement shown. Through this process, LIDAR <NUM> can scan different regions of the surrounding environment according to different rotational positions of LIDAR <NUM> about axis <NUM>. For instance, device <NUM> (and/or another computing system) can determine a three-dimensional map of a <NUM>° (or less) view of the environment of device <NUM> by processing data associated with different pointing directions of LIDAR <NUM> as the LIDAR rotates about axis <NUM>.

In some examples, axis <NUM> may be substantially vertical. In these examples, the pointing direction of device <NUM> can be adjusted horizontally by rotating system <NUM> (and emitter <NUM>) about axis <NUM>.

In some examples, system <NUM> (and emitter <NUM>) can be tilted (relative to axis <NUM>) to adjust the vertical extents of the FOV of LIDAR <NUM>. By way of example, LIDAR device <NUM> can be mounted on top of a vehicle. In this example, system <NUM> (and emitter <NUM>) can be tilted (e.g., toward the vehicle) to collect more data points from regions of the environment that are closer to a driving surface on which the vehicle is located than data points from regions of the environment that are above the vehicle. Other mounting positions, tilting configurations, and/or applications of LIDAR device <NUM> are possible as well (e.g., on a different side of the vehicle, on a robotic device, or on any other mounting surface).

It is noted that the shapes, positions, and sizes of the various components of device <NUM> can vary, and are illustrated as shown in <FIG> only for the sake of example.

Returning now to <FIG>, in some implementations, controller <NUM> may use timing information associated with a signal measured by array <NUM> to determine a location (e.g., distance from LIDAR device <NUM>) of object <NUM>. For example, in implementations where emitter <NUM> is a pulsed laser, controller <NUM> can monitor timings of output light pulses and compare those timings with timings of signal pulses measured by array <NUM>. For instance, controller <NUM> can estimate a distance between device <NUM> and object <NUM> based on the speed of light and the time of travel of the light pulse (which can be calculated by comparing the timings). In one implementation, during the rotation of platform <NUM>, emitter <NUM> may emit light pulses (e.g., light <NUM>), and system <NUM> may detect reflections of the emitted light pulses. Device <NUM> (or another computer system that processes data from device <NUM>) can then generate a three-dimensional (3D) representation of the scanned environment based on a comparison of one or more characteristics (e.g., timing, pulse length, light intensity, etc.) of the emitted light pulses and the detected reflections thereof.

In some implementations, controller <NUM> may be configured to account for parallax (e.g., due to laser emitter <NUM> and lens <NUM> not being located at the same location in space). By accounting for the parallax, controller <NUM> can improve accuracy of the comparison between the timing of the output light pulses and the timing of the signal pulses measured by the array <NUM>.

In some implementations, controller <NUM> could modulate light <NUM> emitted by emitter <NUM>. For example, controller <NUM> could change the projection (e.g., pointing) direction of emitter <NUM> (e.g., by actuating a mechanical stage, such as platform <NUM> for instance, that mounts emitter <NUM>). As another example, controller <NUM> could modulate the timing, the power, or the wavelength of light <NUM> emitted by emitter <NUM>. In some implementations, controller <NUM> may also control other operational aspects of device <NUM>, such as adding or removing filters (e.g., filter <NUM>) along a path of propagation of light <NUM>, adjusting relative positions of various components of device <NUM> (e.g., array <NUM>, opaque material <NUM> (and an aperture therein), lens <NUM>, etc.), among other possibilities.

In some implementations, controller <NUM> could also adjust an aperture (not shown) within material <NUM>. In some examples, the aperture may be selectable from a number of apertures defined within the opaque material. In some examples, a MEMS mirror could be located between lens <NUM> and opaque material <NUM> and may be adjustable by controller <NUM> to direct the focused light from lens <NUM> to one of the multiple apertures. In some examples, the various apertures may have different shapes and/or sizes. In some examples, an aperture may be defined by an iris (or other type of diaphragm). The iris may be expanded or contracted by controller <NUM>, for example, to control the size or shape of the aperture.

Thus, in some examples, LIDAR device <NUM> can modify a configuration of system <NUM> to obtain additional or different information about object <NUM> and/or the scene. In one example, controller <NUM> may select a larger aperture in response to a determination that background noise received by system <NUM> from the scene is currently relatively low (e.g., during night-time). The larger aperture, for instance, may allow system <NUM> to detect a portion of light <NUM> that would otherwise be focused by lens <NUM> outside the aperture. In another example, controller <NUM> may select a different aperture position to intercept a portion of light <NUM> arriving at lens <NUM> from a particular receive path or viewing angle. In yet another example, controller <NUM> could adjust the distance between an aperture and light detector array <NUM>. By doing so, for instance, the cross-sectional area of a detection region in array <NUM> (i.e., cross-sectional area of light <NUM> at array <NUM>) can be adjusted as well. For example, in <FIG>, the detection region of array <NUM> is indicated by shading on array <NUM>.

However, in some scenarios, the extent to which the configuration of system <NUM> can be modified may depend on various factors such as a size of LIDAR device <NUM> or system <NUM>, among other factors. For example, referring back to <FIG>, a size of array <NUM> may depend on an extent of divergence of light <NUM> from a location of aperture 120a to a location of array <NUM>. Thus, for instance, the maximum vertical and horizontal extents of array <NUM> may depend on the physical space available for accommodating system <NUM> within a LIDAR device. Similarly, for instance, an available range of values for the distance between array <NUM> and aperture 120a may also be limited by physical limitations of a LIDAR device where system <NUM> is employed. Accordingly, example implementations are described herein for space-efficient systems that provide an increased detection area in which light detectors can intercept light from the scene and reduce background noise.

In some scenarios, a scanned representation of object <NUM> (e.g., computed using controller <NUM>, or using an external computer that receives data from LIDAR <NUM>, etc.) may be susceptible to parallax associated with a spatial offset between the transmit path of light <NUM> (e.g., emitted by emitter <NUM> via lens <NUM> of <FIG>) and the receive path of reflected light <NUM> incident on lens <NUM>. Accordingly, example implementations are described herein for reducing and/or mitigating the effects of such parallax. In one example, device <NUM> may alternatively incorporate emitter <NUM> within system <NUM> to co-align the LIDAR transmit and receive paths of LIDAR <NUM> (e.g., by causing both paths to extend through the same lens <NUM> and a same aperture in opaque material <NUM>).

It is noted that the various functional blocks shown for the components of device <NUM> can be redistributed, rearranged, combined, and/or separated in various ways different than the arrangement shown.

<FIG> is an illustration of a system <NUM> that includes a waveguide <NUM>, according to example embodiments. In some implementations, system <NUM> can be included in device <NUM> instead of or in addition to transmitter <NUM> and system <NUM>. As shown, system <NUM> may measure light <NUM> reflected by an object <NUM> within a scene similarly to, respectively, system <NUM>, light <NUM>, and object <NUM>. Further, as shown, system <NUM> includes a light detector array <NUM>, an opaque material <NUM>, an aperture 320a, a lens <NUM>, and a light source <NUM>, which may be similar, respectively, to array <NUM>, material <NUM>, aperture 120a, lens <NUM>, and emitter <NUM>. For the sake of example, aperture 320a is shown to have a different shape (elliptical) than a shape of aperture 120a (rectangular). Other aperture shapes are possible.

As shown, system <NUM> also includes waveguide <NUM> (e.g., optical waveguide, etc.). To that end, waveguide <NUM> can be formed from a glass substrate (e.g., glass plate, etc.), a photoresist material (e.g., SU-<NUM>, etc.), or any other material at least partially transparent to one or more wavelengths of emitted light <NUM>.

As shown, system <NUM> also includes an input mirror <NUM> and an output mirror <NUM>. Mirrors <NUM>, <NUM> may be formed from any reflective material that has reflectivity characteristics suitable for reflecting (at least partially) wavelengths of light <NUM>. To that end, a non-exhaustive list of example reflective materials includes gold, aluminum, other metal or metal oxide, synthetic polymers, hybrid pigments (e.g., fibrous clays and dyes, etc.), among other examples.

In the example shown, waveguide <NUM> is positioned between opaque material <NUM> and array <NUM>. However, in other examples, opaque material <NUM> can be instead positioned between waveguide <NUM> and array <NUM>.

As shown, waveguide <NUM> may be arranged such that a portion of waveguide <NUM> extends into a propagation path of focused light <NUM>, and another portion of waveguide <NUM> extends outside the propagation path of focused light <NUM>. As a result, a first portion of focused light <NUM> may be projected onto waveguide <NUM> (as illustrated by the shaded region on the surface of waveguide <NUM>).

<FIG> illustrates a cross-section view of system <NUM>. As best shown in <FIG>, a second portion of focused light <NUM> may propagate from lens <NUM> to array <NUM> without propagating through waveguide <NUM>.

In some instances, at least part of the first portion of focused light <NUM> (projected onto waveguide <NUM>) may propagate through transparent regions of waveguide <NUM> (e.g., from side 350c to side 350d and then out of waveguide <NUM> toward array <NUM>, without being intercepted by mirror <NUM>. However, in some instances, the first portion of focused light <NUM> may be at least partially intercepted by mirror <NUM> and then reflected away from array <NUM> (e.g., guided inside waveguide <NUM>, etc.).

To mitigate this, in some examples, mirror <NUM> can be configured to have a small size relative to aperture 320a and/or relative to a projection area of focused light <NUM> at the location of mirror <NUM>. In these examples, a larger portion of focused light <NUM> may propagate adjacent to mirror <NUM> (and/or waveguide <NUM>) to continue propagating toward array <NUM>.

Alternatively or additionally, in some examples, mirror <NUM> can be formed from a partially or selectively reflective material (e.g., half mirror, dichroic mirror, polarizing beam splitter, etc.) that transmits at least a portion of focused light <NUM> incident thereon through mirror <NUM> for propagation toward array <NUM>. Thus, in these examples as well, a larger amount of focused light <NUM> may eventually reach array <NUM>.

In some examples, input mirror <NUM> may be configured to direct emitted light <NUM> (intercepted by mirror <NUM> from emitter <NUM>) into waveguide <NUM>. Waveguide <NUM> then guides light <NUM> inside waveguide <NUM> toward output mirror <NUM>. Output mirror <NUM> may then reflect guided light <NUM> out of waveguide <NUM> and toward aperture 320a.

As best shown in <FIG> for example, input mirror <NUM> may be tilted at an offset angle <NUM> toward side 350c of waveguide <NUM>. For example, an angle between mirror <NUM> and side 350c may be less than an angle between mirror <NUM> and side 360d. In one implementation, offset or tilting angle <NUM> of mirror <NUM> is <NUM>°. However, other angles are possible. In the embodiment shown, input mirror <NUM> is disposed on side 350a of waveguide <NUM>. Thus, in this embodiment, emitted light <NUM> may propagate into waveguide <NUM> through side 350c and then out of side 350a toward mirror <NUM>. Mirror <NUM> may then reflect light <NUM> back into waveguide <NUM> through side 350a at a suitable angle of entry so that waveguide <NUM> can then guide light <NUM> toward side 350b. For example, waveguide <NUM> can be formed such that angle <NUM> between sides 350a and 350c is less than the angle between side 350a and side 350d (i.e., side 350a tilted toward side 350c). Input mirror <NUM> can then be deposited onto side 350a (e.g., via chemical vapor deposition, sputtering, mechanical coupling, or another process). However, in other embodiments, mirror <NUM> can be alternatively disposed inside waveguide <NUM> (e.g., between sides 350a and 350b), or may be physically separated from waveguide <NUM>.

As best shown in <FIG>, output mirror <NUM> may also be tilted toward side 350c of waveguide <NUM>. For example, an angle <NUM> between mirror <NUM> and side 350c may be less than an angle between mirror <NUM> and side 360d. In one implementation, offset or tilting angle <NUM> of mirror <NUM> is <NUM>°. However, other angles are possible. Thus, in some examples, input mirror <NUM> may be tilted in a first direction (e.g., clockwise in the view of <FIG>) toward side 350c, and output mirror <NUM> may be tilted in a second direction (e.g., opposite to the first direction) toward side 350c. Output mirror <NUM> can be physically implemented in various ways similarly to mirror <NUM> (e.g., disposed on tilted side 350b of waveguide <NUM>, etc.).

In some examples, waveguide <NUM> may be formed from a material that has a different index of refraction than that of materials surrounding waveguide <NUM>. Thus, waveguide <NUM> may guide at least a portion of light propagating inside the waveguide via internal reflection (e.g., total internal reflection, frustrated total internal reflection, etc.) at one or more edges, sides, walls, etc., of waveguide <NUM>. For instance, as shown in <FIG>, waveguide <NUM> may guide emitted light <NUM> (received from emitter <NUM>) toward side 350b via internal reflection at sides 350c, 350d, and/or other sides of waveguide <NUM>.

In the arrangement shown in <FIG> for instance, waveguide <NUM> may extend vertically (e.g., lengthwise) between sides 350a and 350b. In some examples, side 350c may correspond to an interface between a relatively high index of refraction medium (e.g., photoresist, epoxy, etc.) of waveguide <NUM> and a relatively lower index of refraction medium (e.g., air, vacuum, optical adhesive, glass, etc.) adjacent to side 350c. Thus, for instance, if guided light <NUM> propagates to side 350c at less than the critical angle (e.g., which may be based on a ratio of indexes of refractions of the adjacent materials at side 350c, etc.), then the guided light incident on side 350c (or a portion thereof) may be reflected back into waveguide <NUM>. Similarly, guided light incident on side 350d at less than the critical angle may also be reflected back into waveguide <NUM>. Thus, waveguide <NUM> may control divergence of guided light via internal reflection at sides 350c and 350d, for example. Similarly, waveguide <NUM> may extend through the page in the illustration of <FIG> between two opposite sides of waveguide <NUM> to control divergence of guided light <NUM>. In some implementations, to facilitate controlling the divergence of light <NUM>, sides 350c may be configured to be substantially parallel to side 350d.

Through this process, at least a portion of emitted light <NUM> (reflected by input mirror <NUM> into waveguide <NUM>) may reach tilted side 350b. Output mirror <NUM> (e.g., disposed on side 350b) may then reflect the at least portion of guided light <NUM> toward side 350c and out of waveguide <NUM>. For example, offset or tilting angle <NUM> can be selected such that reflected light <NUM> from input mirror <NUM> propagates into waveguide <NUM> in a particular direction so that light <NUM> reaches side 350c (or 350d) at less than the critical angle. As a result, input light <NUM> can be guided inside waveguide <NUM> toward side 350b by reflecting off sides 350c, 350d, etc. Similarly, offset or tilting angle <NUM> of output mirror <NUM> can be selected such that light <NUM> reflected by mirror <NUM> propagates toward a particular region of side 350c at greater than the critical angle. As a result, light <NUM> (reflected by output mirror <NUM>) may be (at least partially) transmitted through side 350c rather than reflected (e.g., via total internal reflection etc.) back into waveguide <NUM>. Further, mirror <NUM> can be oriented to reflect guided light <NUM> incident thereon toward aperture 320a. As shown in <FIG> for example, aperture 320a could be located adjacent to the particular region of side 350c, and may thus transmit light <NUM> toward lens <NUM>. Lens <NUM> may then direct light <NUM> toward a scene.

Emitted light <NUM> may then reflect off one or more objects (e.g., object <NUM>) in the scene, and return to lens <NUM> (e.g., as part of light <NUM> from the scene). Lens <NUM> may then focus light <NUM> (including the reflections of the emitted light beams) through aperture 320a and toward array <NUM>.

With this arrangement, system <NUM> may emit light <NUM> from a substantially same physical location (e.g., aperture 320a) from which system <NUM> receives focused light <NUM> (e.g., aperture 320a). Because the transmit path of emitted light <NUM> and the receive path of focused light <NUM> are co-aligned (e.g., both paths are from the point-of-view of aperture 320a), system <NUM> may be less susceptible to the effects of parallax than the arrangement of system <NUM> and emitter <NUM> of device <NUM> (which are associated with physically separate lenses <NUM> and <NUM>). For instance, data from a LIDAR device that includes system <NUM> could be used to generate a representation of the scene (e.g., point cloud) that is less susceptible to errors related to parallax.

It is noted that the sizes, positions, orientations, and shapes of the components and features of system <NUM> shown are not necessarily to scale, but are illustrated as shown only for convenience in description. It is also noted that system <NUM> may include fewer or more components than those shown, and one or more of the components shown could be arranged differently, physically combined, and/or physically divided into separate components.

In a first implementation which is retained here as being useful for understanding the invention, the relative arrangement of array <NUM>, aperture 320a, and waveguide <NUM> can vary. In a first example, opaque material <NUM> (and thus aperture 320a) can be alternatively disposed between array <NUM> and waveguide <NUM>. For instance, waveguide <NUM> can be positioned adjacent to an opposite side of opaque material <NUM>, while still transmitting emitted light <NUM> along a path that overlaps the propagation path of focused light <NUM> transmitted through aperture 320a. In a second example, array <NUM> can be alternatively disposed between waveguide <NUM> and opaque material <NUM>. For instance, array <NUM> may include an aperture (e.g., cavity, etc.) through which emitted light <NUM> propagates toward aperture 320a (and lens <NUM>).

In a second implementation which is retained here as being useful for understanding the invention, array <NUM> can be replaced by a single light detector instead of a plurality of light detectors.

In a third implementation which is retained here as being useful for understanding the invention, a distance between waveguide <NUM> and aperture 320a can vary. In one example, waveguide <NUM> can be disposed along (e.g., in contact with, etc.) opaque material <NUM>. For instance, side 350c may be substantially coplanar with or proximal to aperture 320a. However, in other examples (as shown), waveguide <NUM> can be positioned at a distance (e.g., gap, etc.) from opaque material <NUM> (and aperture 320a).

In a fourth implementation which is retained here as being useful for understanding the invention, system <NUM> could optionally include an actuator that moves lens <NUM>, opaque material <NUM>, and/or waveguide <NUM> to achieve a particular optical configuration (e.g., focus configuration, etc.) while scanning the scene. More generally, optical characteristics of system <NUM> can be adjusted according to various applications of system <NUM>.

In a fifth implementation which is retained here as being useful for understanding the invention, the position and/or orientation of aperture 320a can vary. In one example, aperture 320a can be disposed along the focal plane of lens <NUM>. In another example, aperture 320a can be disposed parallel to the focal plane of lens <NUM> but at a different distance to lens <NUM> than the distance between the focal plane and lens <NUM>. In yet another example, aperture 320a can be arranged at an offset orientation relative to the focal plane of lens <NUM>. For instance, system <NUM> can rotate (e.g., via an actuator) opaque material <NUM> (and/or waveguide <NUM>) to adjust the entry angle of light <NUM> and/or <NUM> into aperture 320a. By doing so, for instance, a controller (e.g., controller <NUM>) can further control optical characteristics of system <NUM> depending on various factors such as lens characteristics of lens <NUM>, environment of system <NUM> (e.g., to reduce noise / interference arriving from a particular region of the scanned scene, etc.), among other factors.

In a sixth implementation which is retained here as being useful for understanding the invention, waveguide <NUM> can alternatively have a cylindrical shape or any other shape. Additionally, in some examples, waveguide <NUM> can be implemented as a rigid structure (e.g., slab waveguide) or as a flexible structure (e.g., optical fiber).

In a seventh implementation which is retained here as being useful for understanding the invention, waveguide <NUM> may have a curved shape or other type of shape instead of the vertical rectangular configuration shown in <FIG> and <FIG>. Thus, in this implementation, array <NUM> and emitter <NUM> can be physically separated in a variety of ways, and waveguide <NUM> can guide emitted light <NUM> to output mirror <NUM> in any path (not necessarily a vertical or linear path as shown).

In an eighth implementation which is retained here as being useful for understanding the invention, system <NUM> may alternatively omit input mirror <NUM>. For instance, emitter <NUM> can be arranged to emit light <NUM> toward waveguide <NUM> at a suitable angle of entry so that it reflects off sides 350c, 350d, etc., without the presence of input mirror <NUM>.

In a ninth implementation which is retained here as being useful for understanding the invention, waveguide <NUM> can be alternatively implemented without tilting side 350a. For example, side 350a can be at a same (e.g., perpendicular, etc.) angle relative to sides 350c and 350d. With this arrangement for instance, emitter <NUM> can emit light <NUM> into side 350a (which might not be obstructed by mirror <NUM>).

In a tenth implementation which is retained here as being useful for understanding the invention, system <NUM> may include multiple output mirrors (between sides 350a and 350b of waveguide <NUM>) instead of the single output mirror <NUM> shown, multiple apertures instead of the single aperture 320a shown, and multiple light detector arrays instead of the single array <NUM> shown. For example, a first output mirror may reflect a first portion of guided light <NUM> out of waveguide <NUM> toward a first aperture, and a remaining portion of the guided light may continue propagating inside the waveguide toward a second output mirror. The second output mirror may then reflect a second portion of the guided light out of the waveguide toward a second aperture, and so on. Thus, in this example, system <NUM> may provide multiple co-aligned transmit/receive channels using a single waveguide.

In an eleventh implementation which is retained here as being useful for understanding the invention, mirrors <NUM>, <NUM> can be alternatively implemented as one or more optical elements (e.g., lenses, prisms, waveguides, etc.) configured to redirect light <NUM> emitted from emitter <NUM> into waveguide <NUM> (and/or toward aperture 320a). For example, mirror <NUM> and/or <NUM> can be implemented as total internal reflection (TIR) mirrors (e.g., prisms, etc.) or another optical element assembly disposed near sides 350a, 350b, etc., to direct light <NUM> into waveguide <NUM> and/or out of waveguide <NUM> toward aperture 320a.

In a twelfth implementation which is retained here as being useful for understanding the invention, mirrors <NUM>, <NUM> can be omitted from system <NUM>, and waveguide <NUM> can instead be configured to perform the functions described above for mirrors <NUM>, <NUM>. For example, sides 350a and 350b of waveguide <NUM> can be implemented as TIR mirrors that reflect light <NUM> into or out of waveguide <NUM>. For instance, tilting angle <NUM> (shown in <FIG>) can be selected such that light <NUM> arrives from emitter <NUM> at side 350a at less than the critical angle (e.g., associated with the refractive indexes of waveguide <NUM> and its surrounding medium). Alternatively or additionally, for instance, emitter <NUM> can be arranged to transmit light <NUM> toward side 350a (and/or side 350d) at less than the critical angle, such that light <NUM> may then be internally reflected inside waveguide <NUM> toward side 350b. Similarly, tilting angle <NUM> can be selected such that the guided light inside waveguide <NUM> is reflected by side 350b toward side 350c at greater than the critical angle (e.g., so that light <NUM> can then exit waveguide <NUM> at side 350c after reflecting off side 350b). Thus, in this example, waveguide <NUM> and mirrors <NUM>, <NUM> can be implemented as a single physical structure (e.g., without using reflective materials).

<FIG>, which is retained as being useful for understanding the invention, illustrates a first cross-section view of a system <NUM> that includes multiple waveguides <NUM>, <NUM>, <NUM>, <NUM>. For purposes of illustration, <FIG> shows x-y-z axes, where the z-axis extends through the page. System <NUM> may be similar to systems <NUM>, <NUM>, and/or <NUM>, and can be used with device <NUM> instead of or in addition to system <NUM> and transmitter <NUM>. For example, the side of waveguide <NUM> along the surface of the page may be similar to side 350c of waveguide <NUM>.

As shown, system <NUM> includes a plurality of waveguides <NUM>, <NUM>, <NUM>, <NUM>, each of which may be similar to waveguide <NUM>; a plurality of input mirrors <NUM>, <NUM>, <NUM>, <NUM>, each of which may be similar to mirror <NUM>; and a plurality of output mirrors <NUM>, <NUM>, <NUM>, <NUM>, each of which may be similar to output mirror <NUM>.

<FIG> illustrates a second cross-section view of system <NUM>, where the z-axis also extends through the page. As shown in <FIG>, system <NUM> also includes an opaque material <NUM>, which may be similar to opaque material <NUM> of system <NUM>; and a transmitter <NUM> that includes one or more light sources similar to light source <NUM>.

Transmitter <NUM> may be configured to emit light (in the direction of the z-axis) toward waveguides <NUM>, <NUM>, <NUM>, <NUM>. As shown in <FIG> for example, emitted light <NUM> from the transmitter may be projected onto waveguide <NUM> at a location (shaded region) that overlaps input mirror <NUM>, similarly to, respectively, emitted light <NUM>, waveguide <NUM>, and input mirror <NUM>. To that end, transmitter <NUM> may include one or more light sources (e.g., laser bars, LEDs, diode lasers, etc.).

In a first implementation which is retained here as being useful for understanding the invention, transmitter <NUM> may comprise a single light source that transmits light for all the waveguides <NUM>, <NUM>, <NUM>, and <NUM>. For example, system <NUM> may include one or more optical elements (not shown), such as lens, mirrors, beam splitters, etc., that split and direct respective portions of the light emitted by the single light source toward waveguides <NUM> (e.g., as light <NUM>), <NUM>, <NUM>, and <NUM>. With this arrangement, for example, a single light source can be used to drive multiple transmit channels of system <NUM> (e.g., where each transmit channel is associated with a location of a corresponding output mirror).

In a second implementation which is retained here as being useful for understanding the invention, a given light source in transmitter <NUM> can be used to drive fewer or more than four waveguides. For example, transmitter <NUM> may include a first light source that emits light <NUM> toward input mirror <NUM>, and a second light source that emits light (e.g., split into three separate light beams, etc.) for receipt at input mirrors <NUM>, <NUM>, and <NUM>.

In a third implementation which is retained here as being useful for understanding the invention, transmitter <NUM> may include a separate light source for driving each waveguide. For example, a first light source may emit light <NUM> toward mirror <NUM>, a second light source may emit light toward mirror <NUM>, a third light source may emit light toward mirror <NUM>, and a fourth light source may emit light toward mirror <NUM>.

Regardless of the number of light sources in transmitter <NUM>, emitted light beams from the transmitter may then be guided into separate transmit paths (associated with the positions of the output mirrors) toward an environment of system <NUM>.

For example, light beam <NUM> could be transmitted into a given surface of waveguide <NUM> (e.g., similar to side 350c of waveguide <NUM>, etc.), as illustrated by the shaded region in <FIG>. Waveguide <NUM> may then guide light <NUM> toward one or more output mirrors arranged along a guiding direction of waveguide <NUM>. For example, output mirror <NUM> may reflect a portion 404a of guided light <NUM> out of the page (e.g., in the direction of the z-axis), and through the given surface of waveguide <NUM> toward the scene. Thus, light portion 404a may define a first transmit channel (e.g., LIDAR transmit channel, etc.) that is associated with the transmit path described above.

Similarly, a second transmit channel of system <NUM> may be associated with a transmit path defined by waveguide <NUM> and output mirror <NUM>; a third transmit channel associated with a transmit path defined by waveguide <NUM> and output mirror <NUM>; and a fourth transmit channel may be associated with a transmit path defined by waveguide <NUM> and mirror <NUM>. With this arrangement for instance, system <NUM> may emit a pattern of light beams, arranged according to locations of the output mirrors, toward a scene.

In some examples, a single waveguide can be used to define multiple transmit channels of system <NUM>. As shown in <FIG> for example, another portion 404b of light <NUM> guided inside waveguide <NUM> may be transmitted out of waveguide <NUM> at a different location (shaded region) than the location from which portion 404a is transmitted out of waveguide <NUM>. For instance, system <NUM> may include another tilted output mirror (not shown) that reflects light portion 404b out of waveguide <NUM> at the position shown in <FIG>. A remaining portion 404a of the guided light <NUM> may then continue propagating toward mirror <NUM> and then reflect out of waveguide <NUM> in line with the discussion above.

Returning now to <FIG>, opaque material <NUM> may define a plurality of apertures, exemplified by apertures 420a, 420b, 420c, 420d, and 420e, each of which may be similar to aperture 320a. For example, aperture 420a may be aligned (e.g., adjacent, overlapping, etc.) with output mirror <NUM> similarly to, respectively, aperture 320a and output mirror <NUM>. For example, aperture 420a may overlap output mirror <NUM> in the direction of the z-axis to receive light 404a reflected by output mirror <NUM> out of waveguide <NUM>. Similarly, aperture 420b can be aligned with output mirror <NUM>, aperture 420c could be aligned with output mirror <NUM>, and aperture 420d could be aligned with an output mirror <NUM>. Thus, each aperture may be associated with a position of a respective transmit channel.

Additionally, in some examples, light from the scene (e.g., propagating into the page in <FIG>) may be focused onto opaque material <NUM>, similarly to light <NUM> that is focused onto opaque material <NUM>. In these examples, system <NUM> may thus provide multiple receive channels associated with respective portions of the focused light projected on opaque material <NUM> at the respective positions of apertures 420a, 420b, 420c, 420d, etc..

For example, a first portion of the focused light transmitted through aperture 420a could be intercepted by a first light detector associated with a first receive channel, a second portion of the focused light transmitted through aperture 420b could be intercepted by a second light detector associated with a second receive channel, a third portion of the focused light transmitted through aperture 420c could be intercepted by a third light detector associated with a third receive channel, and a fourth portion of the focused light transmitted through aperture 420d could be intercepted by a fourth light detector associated with a fourth receive channel.

With this arrangement, each transmit channel may be associated with a transmit path that is spatially co-aligned (through a respective aperture) with a receive path associated with a corresponding receive channel. Thus, system <NUM> can mitigate the effects of parallax by providing pairs of co-aligned transmit/receive channels defined by the locations of apertures 420a, 420b, 420c, 420d, etc..

<FIG> illustrates a third cross section view of system <NUM>, in which the z-axis is also pointing out of the page. For example, one or more of the components of system <NUM> shown in <FIG> may be positioned above or below (e.g., in the direction of the z-axis) one or more of the components shown in <FIG>.

As shown in <FIG>, system <NUM> also includes a support structure <NUM> that mounts a plurality of receivers, exemplified by receivers <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Further, as shown, system <NUM> also includes one or more light shields <NUM>.

Each of receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc., may include one or more light detectors. Additionally, each receiver may be arranged to intercept focused light transmitted through a respective aperture of opaque material <NUM> (shown in <FIG>). For example, receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be arranged to intercept focused light that is transmitted, respectively, through apertures 420a, 420b, 420c, 420d, 420e (shown in <FIG>). In one implementation, receivers <NUM>, <NUM>, <NUM>, <NUM> may be positioned to overlap (e.g., in the direction of the z-axis), respectively, output mirrors <NUM>, <NUM>, <NUM>, <NUM>. In some examples, each of receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc., may include a respective array of light detectors connected in parallel to one another (e.g., SiPM, MPCC, etc.), similarly to the light detectors in any of the arrays <NUM>, <NUM>, or <NUM>. In other examples, each receiver may include a single light detector.

Accordingly, in some examples, system <NUM> includes a plurality of light detectors (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) that are arranged according to an arrangement of a plurality of output mirrors (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.).

Support Structure <NUM> may include a solid structure that has material characteristics suitable for supporting receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. In one example, support structure <NUM> may include a printed circuit board (PCB) to which the light detectors of receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc., are mounted.

Light shield(s) <NUM> may comprise one or more light absorbing materials (e.g., black carbon, black chrome, black plastic, etc.) arranged around receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. In some examples, light shield(s) <NUM> may prevent (or reduce) light from external sources (e.g., ambient light, etc.) from reaching receivers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. Alternatively or additionally, in some examples, light shield(s) <NUM> may prevent or reduce cross-talk between receive channels associated with receivers <NUM>, <NUM>, <NUM>, <NUM>. Thus, light shield(s) <NUM> may be configured to optically separate receivers <NUM>, <NUM>, <NUM>, <NUM>, etc., from one another. In the example shown, light shield(s) <NUM> may be shaped in a honeycomb structure configuration, where each cell of the honeycomb structure shields light detectors of a first receiver (e.g., receiver <NUM>) from light propagating toward light detectors in a second adjacent receiver (e.g., receiver <NUM>). Other shapes and/or arrangements of light shield(s) <NUM> (e.g., rectangular-shaped cells, other shapes of cells, etc.) are possible.

<FIG> illustrates a fourth cross-section view of system <NUM>, where the y-axis is pointing through of the page. As shown in <FIG>, system <NUM> also includes a lens <NUM>, a light filter <NUM>, a substrate <NUM>, and an output mirror <NUM>. As shown in <FIG>, waveguide <NUM> may be at a first distance to lens <NUM>, and receivers <NUM>, <NUM> may be at a second (greater) distance to lens <NUM>.

Lens <NUM> may be similar to lens <NUM>. For example, lens <NUM> may focus light <NUM> toward opaque material <NUM> similarly to, respectively, lens <NUM>, focused light <NUM>, and opaque material <NUM>. Respective portions of focused light <NUM> may then be transmitted, respectively, through apertures 420a, 420b, 420c, 420d, 420e, etc. (shown in <FIG>). As shown in <FIG> for example, a first portion 402a of focused light <NUM> may be transmitted through aperture 420a toward waveguide <NUM> and receiver <NUM>. Similarly, a second portion 402b of focused light <NUM> may be transmitted through aperture 420e toward waveguide <NUM> and receiver <NUM>.

Additionally, as noted above, each aperture may also correspond to a position from which a transmitted light beam was received by lens <NUM>. Thus, lens <NUM> may direct each transmitted light beam propagating from a particular aperture to the same region of the scene from which lens <NUM> focuses received light into that same particular aperture. For example, transmitted light beam 404a may be directed by lens <NUM> to a first region of the scene according to the location of aperture 420a. A reflected portion of transmitted light beam 404a that returns back to lens <NUM> from the same first region may thus be focused by lens <NUM> into the same aperture 420a (i.e., as part of the first focused light portion 402a), for receipt by light detector <NUM>. Similarly, a reflected portion of the second transmitted light beam 404b may be focused by lens <NUM> toward aperture 420e and light detector <NUM> as part of the second focused portion 402b.

Accordingly, in some examples, system <NUM> may be configured to emit a plurality of transmitted light beams (e.g., 404a, 404b) to illuminate a scene. In these examples, the plurality of light beams may be spatially arranged based on a physical arrangement of the plurality of mirrors (e.g., <NUM>, <NUM>, etc.).

Light filter <NUM> may be similar to light filter <NUM>. For example, light filter <NUM> may include one or more devices configured to attenuate wavelengths of light <NUM> (e.g., other than wavelengths of emitted light <NUM>, etc.). In some examples, filter <NUM> may extend horizontally (through the page; along the direction of the y-axis) to similarly attenuate light propagating toward waveguides <NUM>, <NUM>, and <NUM> (shown in <FIG>).

As shown in <FIG>, filter <NUM> may be disposed between the receivers (e.g., <NUM>, <NUM>, etc.) and the waveguides (e.g., <NUM>, etc.) of system <NUM>. In another implementation, filter <NUM> may be alternatively disposed between the waveguides and the lens. In yet another implementation, substrate <NUM> can be formed from a material that has the light filtering characteristics of filter <NUM>. Thus, in this implementation, filter <NUM> and substrate <NUM> may be implemented as a single physical structure. In still another implementation, filter <NUM> can be implemented as multiple (e.g., smaller) filters that are each disposed between lens <NUM> and a respective one of the receivers. For instance, a first filter can be used to attenuate light propagating toward receiver <NUM>, and a second separate filter can be used to attenuate light propagating toward receiver <NUM>, etc. In one implementation, each one of the multiple filters can be disposed on a respective one of the receivers. For instance, a first filter can be formed on top of receiver <NUM>, a second filter can be formed on top of receiver <NUM>, and so on.

Substrate <NUM> can be formed from an (at least partially) transparent material configured to transmit at least some wavelengths of light (e.g., wavelengths of light <NUM>, etc.) through the substrate. In one implementation, substrate <NUM> may include a glass substrate (e.g., glass wafer). In some examples, substrate <NUM> may be transparent to visible light as well as to the wavelengths of light <NUM> (e.g., infrared light, etc.).

As shown, waveguide <NUM> has an input edge 450a and output edge 450b, which may be similar, respectively, to sides 350a and 350b of waveguide <NUM>. As shown in <FIG> for example, input edge 450a may be tilted in a first direction (e.g., counterclockwise about the y-axis) toward an output side of waveguide <NUM> (e.g., the side mounted to substrate <NUM>). As such, input mirror <NUM> can be deposited on the tilted input edge 450a to reflect light <NUM> (emitted by transmitter <NUM> toward input mirror <NUM>) back into waveguide <NUM> (e.g., toward output mirror <NUM>). Further, output edge 450b may be tilted in a second (opposite) direction (e.g., clockwise about the y-axis) toward the output side of waveguide <NUM>. As such, output mirror <NUM> can be deposited on output edge 450b to reflect guided light portion 404a out of waveguide <NUM> and through aperture 420a toward lens <NUM>.

As shown in <FIG>, waveguide <NUM> also has another output edge 450e that is tilted similarly to edge 450b toward the output side of waveguide <NUM>. As such, output mirror <NUM> can be disposed on output edge 450e to reflect guided light portion 404b out of waveguide <NUM> and toward aperture 420e. Thus, in some examples, waveguide <NUM> may be configured to guide emitted light <NUM> received from an emitter (e.g., transmitter <NUM>) toward a plurality of output mirrors (<NUM>, <NUM>).

To that end, in some examples, waveguide <NUM> may have a first cross-sectional size between input edge 450e and output edge 450e that is different (e.g., greater) than a second cross-sectional size of waveguide <NUM> between output edge 450e and 450b. Thus, after reaching an output edge (e.g., 450e) in the guiding direction of waveguide <NUM> (e.g., positive direction on the x-axis), a first portion 404b of the guided light may be transmitted out of the waveguide as a first transmitted light beam (404b), and a second portion of the guided light may continue to propagate (in a smaller-sized section of the waveguide) toward the next output mirror (e.g., <NUM>), that reflects (at least partially) the second portion of the guided light out of the waveguide as a second transmitted light beam (404a).

In some examples, substrate <NUM> may provide a platform for optically coupling (e.g., aligning, etc.) one or more components of system <NUM>. For example, as shown, an output surface of waveguide <NUM> (e.g., similar to side 350c of waveguide <NUM>) may be mounted on a first side of substrate <NUM>. Further, as shown, transmitter <NUM> may be mounted on a second side of substrate <NUM> opposite to the first side. Additionally, as shown, opaque material <NUM> can be mounted on the second side of the substrate.

In one example, substrate <NUM> may be transparent to visible light. With this arrangement, in some scenarios, aligning transmitter <NUM> with mirror <NUM> can be performed more efficiently (e.g., because mirror <NUM> is viewable through substrate <NUM>, etc.), than if transmitter <NUM> was instead adjacent to edge 450a of waveguide <NUM>.

In another example, substrate <NUM> may include alignment marks (e.g., etched markings or cavities, etc.) on each side of the substrate. Such alignment marks can be accurately positioned (e.g., using a mask, etc.) during manufacture of substrate <NUM>. In turn, the various components mounted to substrate <NUM> can be more accurately aligned by using such alignment marks. For example, a robotic tool can be used to deposit waveguides <NUM>, <NUM>, <NUM>, <NUM>, etc., onto the first side of substrate <NUM> can use the alignment marks to accurately deposit the material of waveguide <NUM>. Similarly, the alignment marks can be used to more accurately place opaque material <NUM> and transmitter <NUM> on the second side of substrate <NUM>.

In one example, opaque material <NUM> may define a grid of apertures along a focal plane of lens <NUM>. In some examples, each aperture in opaque material <NUM> may transmit light for a respective transmit/receive channel associated with a respective portion of the FOV of lens <NUM> that is viewable through the respective aperture. In one implementation, opaque material <NUM> may comprise four rows of <NUM> apertures, where each row of horizontally (e.g., along y-axis) adjacent apertures is separated by a vertical offset (e.g., along z-axis) from another row of apertures. In this implementation, system <NUM> could thus provide <NUM> * <NUM> = <NUM> receive channels, and <NUM> co-aligned transmit channels. In other implementations, system <NUM> may include a different number of transmit/receive channels (and thus a different number of associated apertures).

In one example, system <NUM> may include <NUM> waveguides (arranged similarly to waveguides <NUM>, <NUM>, <NUM>, <NUM>), and each waveguide may guide light that is divided into <NUM> transmitted light beams in a <NUM> x <NUM> grid arrangement (e.g., to drive <NUM> transmit/receive channels of system <NUM> that are spatially arranged as two rows of four apertures each). Other examples are possible.

In some implementations, system <NUM> can be rotated about an axis while scanning a surrounding environment using the plurality of co-aligned transmit/receive channels. Referring back to <FIG> for example, system <NUM> can be mounted on a rotating platform, similar to platform <NUM>, that rotates about an axis (e.g., using actuator <NUM>, etc.) while system <NUM> is transmitting light pulses and detecting reflections thereof (via apertures 420a, 420b, 420c, 420d, etc.). In this example, a controller (e.g., controller <NUM>) or other computer system can receive LIDAR data collected using the co-aligned transmit / receive channels of system <NUM>, and then process the LIDAR data to generate a 3D representation of the environment of system <NUM>. In one implementation, system <NUM> can be employed in a vehicle, and the 3D representation may be used to facilitate various operations of the vehicle (e.g., detect and/or identify objects around the vehicle, facilitate autonomous navigation of the vehicle in the environment, display the 3D representation to a user of the vehicle via a display, etc.).

It is noted that the various sizes, shapes, and positions (e.g., distance between adj acent waveguides, etc.) shown in <FIG> for the various components of system <NUM> are not necessarily to scale but are illustrated as shown only for convenience in description. For example, although waveguides <NUM>, <NUM>, <NUM>, <NUM> are shown in <FIG> to extend in a linear direction (e.g., along the direction of the x-axis), one or more waveguides may alternatively be implemented to extend in a curved path or a path having any different type of shape.

In some examples, one or more of the waveguides shown in <FIG> may alternatively extend in a lengthwise direction from an input side to an intermediate location, and then split into multiple branches (e.g., elongate members, etc.), where each branch includes one or more output edges and extends in a different direction than other branch(es) of the waveguide. Other examples are possible.

<FIG> is a flowchart of a method <NUM> which is retained here as an example which is useful for understanding the invention. Method <NUM> presents an example of a method that could be used with systems <NUM>, <NUM>, <NUM>, <NUM>, and/or device <NUM>, for example. Method <NUM> may include one or more operations, functions, or actions as illustrated by one or more of blocks <NUM>-<NUM>. Although the blocks are illustrated in a sequential order, these blocks may in some instances be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

In addition, for method <NUM> and other processes and methods disclosed herein, the flowchart shows functionality and operation of one possible implementation. In this regard, each block may represent a module, a segment, a portion of a manufacturing or operation process, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium, for example, such as a storage device including a disk or hard drive. The computer readable medium may include a non-transitory computer readable medium, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium may also include non-transitory media, such as secondary or persistent long term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or nonvolatile storage systems. The computer readable medium may be considered a computer readable storage medium, for example, or a tangible storage device. In addition, for method <NUM> and other processes and methods disclosed herein, each block in <FIG> may represent circuitry that is wired to perform the specific logical functions in the process.

At block <NUM>, method <NUM> involves emitting (e.g., via transmitter / emitter <NUM>) light (e.g., <NUM>) toward a first end (e.g., edge 450a) of a waveguide (e.g., <NUM>). At block <NUM>, method <NUM> involves guiding, inside the waveguide, the emitted light toward a second end (e.g., edge 450b) of the waveguide.

At block <NUM>, method <NUM> involves reflecting (e.g., via output mirror <NUM>) a first portion (e.g., 404a) of the guided light toward an output surface (e.g., surface of waveguide <NUM> mounted on substrate <NUM>, output side 350c of waveguide <NUM>, etc.) of the waveguide. In some examples, the first light portion (e.g., 404a) may be transmitted toward a scene as a first transmitted light beam. For example, light portion 404a may be directed by lens <NUM> toward the scene as the first transmitted light beam.

At block <NUM>, method <NUM> involves reflecting (e.g., via output mirror <NUM>) a second portion (e.g., 404b) of the guided light toward the output surface of the waveguide as a second transmitted light beam. Referring back to <FIG> for example, lens <NUM> may receive the first light portion 404a from a first position of aperture 420a, and the second light portion 404b from a second position of aperture 420e. In turn, lens <NUM> may transmit the first light beam 404a toward a first region of the scene, and may transmit the second light beam 404b toward a second region of the scene.

Claim 1:
A light detection and ranging (LIDAR) device (<NUM>) comprising:
a plurality of mirrors including a first mirror (<NUM>) and a second mirror (<NUM>), wherein the LIDAR device is configured to transmit a plurality of light beams (404a, 404b) to illuminate a scene, wherein the plurality of transmitted light beams includes a first transmitted light beam and a second transmitted light beam, and wherein the plurality of transmitted light beams is arranged spatially based on a physical arrangement of the plurality of mirrors;
a light emitter (<NUM>); and
a waveguide (<NUM>) configured to guide emitted light from the light emitter toward the plurality of mirrors, wherein the first mirror (<NUM>) is configured to reflect a first portion of the light toward an output side of the waveguide as the first transmitted light beam (404b), and wherein the second mirror (<NUM>) is configured to reflect a second portion of the light toward the output side of the waveguide as the second transmitted light beam (404a).