Patent Application
20220019034
A conventional Light Detection and Ranging (lidar) system may utilize a light-emitting transmitter (e.g., a laser diode) to emit light pulses into an environment. Emitted light pulses that interact with (e.g., reflect from) objects in the environment can be received by a receiver (e.g., a photodetector) of the lidar system. Range information about the objects in the environment can be determined based on a time difference between an initial time when a light pulse is emitted and a subsequent time when the reflected light pulse is received.
The present disclosure generally relates to light detection and ranging (lidar) systems, which may be configured to obtain information about an environment. Such lidar devices may be implemented in vehicles, such as autonomous and semi-autonomous automobiles, trucks, motorcycles, and other types of vehicles that can navigate and move within their respective environments.
In a first aspect, a transmitter module is provided. The transmitter module includes a light-emitter die and a plurality of light-emitter devices coupled to the light-emitter die. Each light-emitter of the plurality of light-emitter devices is configured to emit light from a respective emitter surface. The transmitter module also includes a cylindrical lens optically coupled to the plurality of light-emitter devices and arranged along an axis. The light-emitter die is disposed such that the respective emitter surfaces of the plurality of light-emitter devices form a non-zero yaw angle with respect to the axis.
In a second aspect, a method is provided. The method includes providing a light-emitter die that includes a plurality of light-emitter devices. Each light-emitter of the plurality of light-emitter devices is configured to emit light from a respective emitter surface. The method also includes providing a substrate, a cylindrical lens coupled to the substrate and arranged along an axis, a spacer, and a plurality of optical waveguides. The method additionally includes coupling the light-emitter die to the substrate and the spacer such that the respective emitter surfaces of the plurality of light-emitter devices form a non-zero yaw angle with respect to the axis. Each optical waveguide of the plurality of optical waveguides is optically coupled by way of the cylindrical lens to at least one light-emitter device of the plurality of light-emitter devices.
Other aspects, embodiments, and implementations will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings.
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 being an “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or features. Other embodiments can be utilized, and other changes can be made, without departing from the scope of the subject matter presented herein.
Thus, the example embodiments described herein are not meant to be limiting. Aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.
Further, unless context suggests otherwise, the features illustrated in each of the figures may be used in combination with one another. Thus, the figures should be generally viewed as component aspects of one or more overall embodiments, with the understanding that not all illustrated features are necessary for each embodiment.
A transmitter (TX) module of a lidar system could include one or more light sources (e.g., laser bars) arranged on a light source substrate. The light sources could be disposed so as to emit light (e.g., light pulses) toward an optical element, such as a fast axis collimation (FAC) lens. Light interacting with the FAC lens could be optically coupled to one or more light guiding elements (e.g., optical waveguides).
In such scenarios, optical back-reflections and other effects can lead to non-deterministic fluctuations in the power and/or spectral wavelength outputted by the TX module. For example, the laser pulse power can vary by over 50%, and laser pulse spectral center could vary by 5 nm (out of 905 nm) or more from pulse to pulse. In some scenarios, fluctuations could be based on environmental factors such as temperature, humidity, physical shock, and/or vibration. In other scenarios, other phenomena could cause variations in the characteristics of optical pulses. Such spurious fluctuations could be difficult to compensate for and/or could lead to incorrect determinations of object range and/or object reflectance. When the lidar system is used in an autonomous vehicle, for example, compensating for such fluctuations and/or determinations of object range and/or reflectance can have broader impact implications on overall cost, complexity, and/or performance.
Example embodiments described herein could improve performance of the TX module by reducing variance in pulse power and more closely control the spectral center of the laser pulses. In some embodiments, methods and systems could include tilting the laser die with respect to a fast axis collimation lens. In such embodiments, tilting the laser die could include rotating it in a yaw direction (e.g., about an axis perpendicular to a major surface of the substrate).
Additionally or alternatively, some embodiments may include coating one or more of the optical elements of the transmitter module with an optical coating. For example, the fast axis collimation lens could be coated with a single- or multi-layer coating with a uniform thickness anti-reflective coating around the cylindrically-shaped optical fiber. In some embodiments, the purpose of the coating is to reduce the amount of reflected light from the surface of the cylindrically-shaped optical fiber.
The transmitter module 100 includes a light-emitter die 110.
The transmitter module 100 also includes a plurality of light-emitter devices 112, which could be coupled to the light-emitter die 110. Each light-emitter of the plurality of light-emitter devices 112 is configured to emit light from a respective emitter surface 114.
The transmitter module 100 additionally includes a cylindrical lens 130 optically coupled to the plurality of light-emitter devices 112 and arranged along an axis 134. In such scenarios, the light-emitter die 110 could be disposed such that the respective emitter surfaces of the plurality of light-emitter devices 112 form a non-zero yaw angle 140 with respect to the axis 134.
In various embodiments, the cylindrical lens 130 includes an optical fiber lens configured as a fast axis collimation lens for light emitted from the light-emitter devices 112.
The non-zero yaw angle 140 could be any angle other than zero degrees. For example, the non-zero yaw angle 140 could be between 0.25 degrees and 3 degrees. It will be understood that other non-zero yaw angles are possible and contemplated. It will also be understood that negative angle values are possible and contemplated.
In various embodiments, the transmitter module 100 could additionally include a plurality of optical waveguides 150. Each optical waveguide of the plurality of optical waveguides 150 could be optically coupled to at least one respective light-emitter device of the plurality of light-emitter devices 112 by way of the cylindrical lens 130.
In some embodiments, the transmitter module 100 could additionally include a substrate 160 and a spacer 164. In such scenarios, the spacer 164, the cylindrical lens 130, and the plurality of optical waveguides 150 could be directly coupled to the substrate 160.
In various embodiments, each optical waveguide of the plurality of optical waveguides 150 could be configured to guide light by total internal reflection along a direction substantially parallel to a surface of the substrate 160. In such scenarios, the axis 134 could be parallel to a surface of the substrate 160.
Additionally or alternatively, the spacer 164 could include an optical fiber spacer.
In some embodiments, the transmitter module 100 could further include a light-emitter substrate 120. In such scenarios, the light-emitter die 110 could be coupled to the light-emitter substrate 120.
In example embodiments, the plurality of light-emitter devices 112 could include between 4 and 10 light-emitter devices that are each coupled to the light-emitter die 110.
In various embodiments, a surface of the cylindrical lens 130 could be coated with a coating 132. For example, the coating 132 could be a single- or multi-layer anti-reflective coating.
Each light-emitter device of the plurality of light-emitter devices 112 could include a laser bar configured to emit infrared light. In such scenarios, the infrared light could include light having a wavelength of about 905 nanometers (e.g., between 900 and 910 nanometers). It will be understood that light-emitter devices configured to emit light having other infrared wavelengths (e.g., 700 nanometers to 1 millimeter) are possible and contemplated.
In some embodiments, the transmitter module 100 could additionally include a plurality of further light-emitter die each having a respective plurality of light-emitter devices. In such scenarios, the transmitter module 100 could include a total of 10 to 20 light-emitter die.
It will be understood that
As illustrated in
In such a scenario, as illustrated, each light-emitter substrate could be rotated at a similar yaw angle with respect to, for example, the cylindrical lens 130. In some embodiments, it will be understood that the respective light-emitter substrates and, by extension, the corresponding light-emitter die could be disposed at different yaw angles from one another, within the scope of the present disclosure. That is, light-emitter substrate 120a and light-emitter die 110a could be disposed at a +1.0 degree yaw angle while light-emitter substrate 120b and light-emitter die 110b could be disposed at a +0.8 degree yaw angle. Other yaw angle differences, ranges, and/or variations are possible and contemplated.
The vehicle 500 may include one or more sensor systems 502, 504, 506, 508, and 510. In some embodiments, sensor systems 502, 504, 506, 508, and 510 could include transmitter module(s) 100 as illustrated and described in relation to
While the one or more sensor systems 502, 504, 506, 508, and 510 are illustrated on certain locations on vehicle 500, it will be understood that more or fewer sensor systems could be utilized with vehicle 500. Furthermore, the locations of such sensor systems could be adjusted, modified, or otherwise changed as compared to the locations of the sensor systems illustrated in
In some embodiments, sensor systems 502, 504, 506, 508, and 510 could include a plurality of light-emitter devices arranged over a range of angles with respect to a given plane (e.g., the x-y plane) and/or arranged so as to emit light toward different directions within an environment of the vehicle 500. For example, one or more of the sensor systems 502, 504, 506, 508, and 510 may be configured to rotate about an axis (e.g., the z-axis) perpendicular to the given plane so as to illuminate an environment around the vehicle 500 with light pulses. Based on detecting various aspects of reflected light pulses (e.g., the elapsed time of flight, polarization, intensity, etc.), information about the environment may be determined.
In an example embodiment, sensor systems 502, 504, 506, 508, and 510 may be configured to provide respective point cloud information that may relate to physical objects within the environment of the vehicle 500. While vehicle 500 and sensor systems 502, 504, 506, 508, and 510 are illustrated as including certain features, it will be understood that other types of sensor systems are contemplated within the scope of the present disclosure.
Lidar systems with single or multiple light-emitter devices are also contemplated. For example, light pulses emitted by one or more laser diodes may be controllably directed about an environment of the system. The angle of emission of the light pulses may be adjusted by a scanning device such as, for instance, a mechanical scanning mirror and/or a rotational motor. For example, the scanning devices could 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 light pulses towards a spinning prism mirror, which may cause the light pulses to be emitted into the environment based on an angle of the prism mirror angle when interacting with each light pulse. Additionally or alternatively, scanning optics and/or other types of electro-opto-mechanical devices are possible to scan the light pulses about the environment. While
Block 602 includes providing a light-emitter die (e.g., light-emitter die 110). In some embodiments, the light-emitter die could include a plurality of light-emitter devices (e.g., light-emitter devices 112). In various embodiments, each light-emitter of the plurality of light-emitter devices could be configured to emit light from a respective emitter surface (e.g., emitter surface(s) 114).
Block 604 includes providing a substrate (e.g., substrate 160). Additionally, a cylindrical lens (e.g., cylindrical lens 130) could be provided. The cylindrical lens may be coupled to the substrate and could be arranged along an axis (e.g., axis 134). Block 604 could additionally or alternatively include providing a spacer (e.g., spacer 164) and a plurality of optical waveguides (e.g., optical waveguides 150).
Block 606 could include coupling the light-emitter die to the substrate and the spacer such that the respective emitter surfaces of the plurality of light-emitter devices form a non-zero yaw angle (e.g., non-zero yaw angle 140) with respect to the axis. In some embodiments, each optical waveguide of the plurality of optical waveguides could be optically coupled by way of the cylindrical lens to at least one light-emitter device of the plurality of light-emitter devices.
In various embodiments, coupling the light-emitter die to the substrate and the spacer could include, for example, using a pick-and-place tool to position the light-emitter die with respect to the substrate based on one or more reference features. As an example, the reference features could be formed in photoresist on the substrate, the light-emitter die, or another surface. Additionally or alternatively, the reference features could be formed by etched structures present on one or more of the substrate, the light-emitter die, or another surface.
In some embodiments, the light-emitter die could be coupled to a light-emitter substrate (e.g., light-emitter substrate 120). In such scenarios, coupling the light-emitter die to the substrate and the spacer could include applying a cureable adhesive material (e.g., a thermoset epoxy) to at least one of the substrate or the light-emitter substrate. In such scenarios, method 600 could include curing the adhesive material so as to fix the respective emitter surfaces of the plurality of light-emitter devices at the yaw angle with respect to the axis.
Additionally or alternatively, coupling the light-emitter die to the substrate and the spacer could include positioning the light-emitter die using a computer vision technique.
In some embodiments, method 600 could include coating the cylindrical lens with a single- or multi-layer anti-reflective coating (e.g., coating 132). In some embodiments, the coating 132 could be applied by way of e-beam deposition or other thin-film deposition techniques.
In some embodiments, systems and methods could include reducing power fluctuations in an optical system (e.g., a lidar system). For example, methods could include positioning, or adjusting a position of, a light-emitter die at an angle (e.g., a yaw direction) relative to a fast axis collimation lens. In such scenarios, positioning the light-emitter die could be performed once, periodically, and/or dynamically.
The particular arrangements shown in the Figures should not be viewed as limiting. It should be understood that other embodiments may include more or less of each element shown in a given Figure. Further, some of the illustrated elements may be combined or omitted. Yet further, an illustrative embodiment may include elements that are not illustrated in the Figures.
A step or block that represents a processing of information can correspond to circuitry that can be configured to perform the specific logical functions of a herein-described method or technique. Alternatively or additionally, a step or block that represents a processing of information can correspond to a module, a segment, or a portion of program code (including related data). The program code can include one or more instructions executable by a processor for implementing specific logical functions or actions in the method or technique. The program code and/or related data can be stored on any type of computer readable medium such as a storage device including a disk, hard drive, or other storage medium.
The computer readable medium can also include non-transitory computer readable media such as computer-readable media that store data for short periods of time like register memory, processor cache, and random access memory (RAM). The computer readable media can also include non-transitory computer readable media that store program code and/or data for longer periods of time. Thus, the computer readable media may include 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 can also be any other volatile or non-volatile storage systems. A computer readable medium can be considered a computer readable storage medium, for example, or 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.
