阅读说明：本技术 光转向镜组件 (Light turning mirror assembly ) 是由 王佑民 周勤 于 2018-12-11 设计创作，主要内容包括：本申请披露了用于光转向的方法和系统。在一个示例中,一种装置包括：一个光源；一个接收器；一个微机电系统(MEMS)和一个控制器。微机电系统包括：第一旋转镜阵列,用于接收和反射来自光源的光束；第二旋转镜,用于接收由第一旋转镜阵列反射的光束。控制器被配置为分别旋转第一旋转镜阵列和第二旋转镜,设置光路与第一尺寸相关的第一角度,以及设置光路与正交于第一尺寸的第二尺寸相关的第二角度,以执行以下至少一项：沿光路反射来自光源的光,或将沿光路传播的输入光反射到接收器。(Methods and systems for light turning are disclosed. In one example, an apparatus comprises: a light source; a receiver; a micro-electro-mechanical system (MEMS) and a controller. The micro-electro-mechanical system comprises: a first array of rotating mirrors for receiving and reflecting light beams from the light source; a second rotating mirror for receiving the light beams reflected by the first rotating mirror array. The controller is configured to rotate the first and second rotating mirrors, respectively, set a first angle of the optical path relative to a first dimension, and set a second angle of the optical path relative to a second dimension orthogonal to the first dimension, to perform at least one of: light from a light source is reflected along an optical path or input light propagating along the optical path is reflected to a receiver.)

1. An apparatus comprising a light detection and ranging (LiDAR) module, the LiDAR module comprising:

a light source;

a receiver; and

a semiconductor integrated circuit including a micro-electro-mechanical system (MEMS) and a controller,

wherein the micro-electromechanical system comprises:

a first array of rotating mirrors for receiving and reflecting light beams from the light source;

a second rotating mirror for receiving the light beams reflected by the first rotating mirror array;

a first driver array configured to rotate each rotating mirror of the first array of rotating mirrors; and

a second driver configured to rotate the second rotating mirror;

and

wherein the controller is configured to control the first driver array to rotate the first rotating mirror array to set a first angle at which the optical path is associated with a first dimension, and to control the second driver to rotate the second rotating mirror to set a second angle at which the optical path is associated with a second dimension orthogonal to the first dimension, to at least one of: reflecting light from the light source along the optical path or reflecting input light propagating along the optical path to the receiver.

2. The apparatus of claim 1, wherein the light source is a laser diode.

3. The apparatus of claim 1, wherein the light comprises a first light signal; and

wherein the controller is configured to:

controlling the light source to emit the light comprising the first light signal at a first time;

controlling the first and second driver arrays to output the light comprising the first light signal along the optical path toward an object;

controlling the first and second driver arrays to select the input light, the input light comprising a second optical signal propagating from the object along the optical path;

the receiver receives the second optical signal at a second time; and

determining a position of the object relative to the apparatus based on a difference between the first and second times, the first and second angles.

4. The apparatus of claim 1, wherein the first rotating mirror array and the second rotating mirror are formed on a surface of a semiconductor substrate of the semiconductor integrated circuit.

5. The apparatus of claim 4, further comprising a third mirror facing the first and second rotating mirror arrays, the third mirror configured to reflect the light reflected by the first rotating mirror array to the second rotating mirror.

6. The apparatus of claim 5, wherein the third mirror is separated from the surface of the semiconductor substrate by a first distance;

wherein the first rotating mirror array and the second rotating mirror are separated by a second distance; and

wherein the first distance and the second distance are set based on an angle of incidence of the light from the light source with respect to the first rotating mirror.

7. The apparatus of claim 1, further comprising a collimator lens between the light source and the first turning mirror,

wherein the collimator lens has a predetermined aperture.

8. The apparatus of claim 7, wherein each rotating mirror of the first array of rotating mirrors and the second rotating mirror are substantially equal in size to the aperture.

9. The apparatus of claim 1, wherein the first array of rotating mirrors is formed on a first surface of a first semiconductor substrate of the semiconductor integrated circuit;

wherein the second rotating mirror is formed on a second surface of a second semiconductor substrate of the semiconductor integrated circuit; and

wherein the first surface faces the second surface.

10. The apparatus of claim 1, wherein the mass of each rotating mirror of the first array of rotating mirrors is less than the mass of the second rotating mirror;

wherein the controller is configured to adjust a first angle of rotation of each rotating mirror of the first array of rotating mirrors at a first frequency; and

wherein the controller is configured to adjust a second angle of rotation of the second rotating mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotating mirror.

11. The apparatus of claim 10, wherein each driver of the first driver array and the second driver comprise a rotary driver; and

wherein the controller is configured to adjust the first and second angles of rotation based on adjusting a first torque provided by each driver of the first driver array and a second torque provided by the second driver, respectively.

12. The apparatus of claim 11, wherein each driver of the first driver array and the second driver comprise at least one of: comb drives, piezoelectric devices, or electromagnetic devices.

13. The apparatus of claim 1, further comprising motion sensors, each motion sensor coupled with each rotating mirror of the first array of rotating mirrors and the second rotating mirror and configured to measure an angle of rotation of each rotating mirror of the first array of rotating mirrors and the second rotating mirror;

wherein the controller is configured to:

receiving data from the motion sensor; and

determining a signal of each driver of the first and second rotating mirrors based on the data such that each rotating mirror of the first rotating mirror array and the second rotating mirror rotate at a first target angle and a second target angle, respectively.

14. A method, comprising:

determining a first angle and a second angle of an optical path, the optical path being one of a projection path for output light or an input path for input light, the first angle being associated with a first dimension, the second angle being associated with a second dimension orthogonal to the first dimension;

controlling a first driver array to rotate a first rotating micro-mirror array of a micro-electromechanical system (MEMS) to set the first angle;

controlling a second driver to rotate a second rotating mirror of the microelectromechanical system to set the second angle;

projecting a light beam comprising a light signal using a light source to a mirror assembly comprising a first array of rotating mirrors and a second rotating mirror; and

performing at least one of the following using the first rotating mirror array and the second rotating mirror when the first rotating mirror array sets the first angle and the second rotating mirror sets the second angle: reflecting the output light from the light source to the object along the projection path or reflecting the input light propagating along the input path to a receiver.

15. The method of claim 14, further comprising:

controlling the light source to emit the output light comprising a first light signal at a first time;

controlling the first driver array and the second driver to output the output light including the first optical signal toward an object along the optical path;

controlling the first and second driver arrays to select the input light, the input light comprising a second optical signal propagating from the object along the optical path;

receiving, by the receiver, the second optical signal at a second time; and

determining a position of the object based on a difference between the first time and the second time, the first angle and the second angle.

16. The method of claim 14, further comprising:

adjusting a first rotation angle of each rotating mirror of the first array of rotating mirrors at a first frequency; and

adjusting a second angle of rotation of the second rotating mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotating mirror.

17. The method of claim 16, further comprising:

receiving information indicative of the first angle of rotation of each rotating mirror of the first array of rotating mirrors and information indicative of the second angle of rotation of the second rotating mirror from a motion sensor;

adjusting a first control signal to the first driver array based on a difference between the first angle of rotation and a first target angle of rotation; and

adjusting a second control signal to the second driver based on a difference between the second rotation angle and a second target rotation angle.

18. A non-transitory computer-readable medium storing instructions that, when executed by a hardware processor, cause the hardware processor to:

determining a first angle and a second angle of the optical path, the optical path being one of a projection path for outputting light or an input path for inputting light, the first angle being associated with a first dimension, the second angle being associated with a second dimension orthogonal to the first dimension;

control a first driver array to rotate a first rotating mirror array of a microelectromechanical system (MEMS) to be disposed at the first angle;

controlling a second driver to rotate a second rotating mirror of the microelectromechanical system to set the second angle;

projecting a light beam comprising a light signal using a light source to a mirror assembly comprising a first array of rotating mirrors and a second rotating mirror; and

when the first rotating mirror array sets the first angle and the second rotating mirror sets the second angle, performing at least one of the following using the first rotating mirror array and the second rotating mirror: reflecting the output light from the light source to the object along the projection path or reflecting the input light propagating along the input path to a receiver.

19. The non-transitory computer-readable medium of claim 18, further including instructions that, when executed by the hardware processor, cause the hardware processor to:

controlling the light source to emit the output light comprising a first light signal at a first time;

controlling the first driver array and the second driver to output the output light including the first optical signal toward an object along the optical path;

controlling the first and second driver arrays to select the input light, the input light comprising a second optical signal propagating from the object along the optical path;

receiving, by the receiver, the second optical signal at a second time; and

determining a position of the object based on a difference between the first time and the second time, the first angle and the second angle.

20. The non-transitory computer-readable medium of claim 18, further including instructions that, when executed by the hardware processor, cause the hardware processor to:

adjusting a first rotation angle of each rotating mirror of the first array of rotating mirrors at a first frequency; and

adjusting a second angle of rotation of the second rotating mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotating mirror.

Background

Light steering generally involves the projection of light in a predetermined direction to facilitate, for example, the detection and ranging of objects, the illumination and scanning of objects, and the like. Light steering may be used in many different application areas, e.g. autonomous vehicles, medical diagnostic devices, etc.

Light steering may be performed in the transmission and reception of light. For example, the light redirecting system may include an array of micromirrors to control the direction of projection of light to detect/image an object. In addition, the light redirecting receiver may also include an array of micro-mirrors to select the direction of incident light to be detected by the receiver to avoid detecting other unwanted signals. The micromirror array may comprise an array of micromirror assemblies, wherein each micromirror assembly comprises a micromirror and a driver. In the micromirror assembly, the micromirror may be coupled to the substrate by a coupling structure (e.g., torsion bars, springs, etc.) to form a pivot, and the actuator may rotate the micromirror about the pivot. Each micromirror may be rotated through a rotation angle to reflect (and turn) light from the light source toward a target direction. The actuator can rotate each micromirror to provide a first range of projection angles along a vertical axis and a second range of projection angles along a horizontal axis. The first and second ranges of projection angles may determine a two-dimensional field of view (FOV) in which light is projected to detect/scan an object. The FOV may also determine the direction of incident light reflected by an object, as detected by the receiver.

The mirror assembly may dominate various performance metrics of the light steering system, such as accuracy, drive power, FOV, dispersion angle, reliability, and the like. It would be desirable to provide a mirror assembly that improves these performance metrics.

Disclosure of Invention

In some embodiments, an apparatus includes a light detection and ranging (LiDAR) module. The LiDAR module includes: a light source, a receiver, and a semiconductor integrated circuit including a micro-electromechanical system (MEMS) and a controller. The micro-electro-mechanical system comprises: a first array of rotating mirrors for receiving and reflecting light beams from the light source; a second rotating mirror for receiving the light beams reflected by the first rotating mirror array; a first driver array configured to rotate the first rotating mirror array; and a second driver configured to rotate the second rotating mirror. The controller is configured to control the first driver array to rotate a first angle associated with a first dimension of the first rotating mirror array setting optical path and to control the second driver to rotate a second angle associated with a second dimension of the second rotating mirror setting optical path orthogonal to the first dimension to perform at least one of: light from a light source is transmitted along an optical path, or input light propagating along the optical path is transmitted to a receiver. In some aspects, the light source is a laser diode.

In some aspects, the light comprises a first optical signal. The controller is configured to: controlling a light source to emit light comprising a first light signal at a first time; controlling the first driver array and the second driver to output light comprising a first light signal along the optical path towards the object; controlling the first driver array and the second driver to select input light, the input light comprising a second optical signal propagating from the object along the optical path; receiving, by the receiver, a second optical signal at a second time; and determining a position of the object relative to the device based on the difference between the first and second times, the first and second angles.

In some aspects, the first rotating mirror array and the second rotating mirror are formed on a surface of a semiconductor substrate of a semiconductor integrated circuit. The apparatus may further include a third mirror facing the first rotating mirror array and the second rotating mirror, and configured to reflect light reflected from the first rotating mirror array to the second rotating mirror. In some aspects, the third mirror is separated from the surface of the semiconductor substrate by a first distance. The first rotating mirror array and the second rotating mirror are separated by a second distance. The first distance and the second distance are set based on an incident angle of light from the light source with respect to the first rotating mirror.

In some aspects, the apparatus further comprises a collimator lens positioned between the light source and the first turning mirror. The collimator lens has a predetermined aperture. In some aspects, each rotating mirror in the first array of rotating mirrors and the second rotating mirror has a size substantially equal to the aperture.

In some aspects, a first array of rotating mirrors is formed on a first surface of a first semiconductor substrate of a semiconductor integrated circuit. The second rotating mirror is formed on a second surface of a second semiconductor substrate of the semiconductor integrated circuit. The first surface faces the second surface.

In some aspects, the mass of each rotating mirror of the first array of rotating mirrors is less than the mass of the second rotating mirror. The controller is configured to adjust a first rotation angle of each rotating mirror of the first array of rotating mirrors at a first frequency. The controller is further configured to adjust a second angle of rotation of the second rotating mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to the natural frequency of the second rotating mirror.

In some aspects, each driver in the first driver array and the second driver comprise a rotary driver. The controller is configured to adjust the first and second rotation angles based on adjusting a first torque provided by each driver of the first driver array and a second torque provided by the second driver, respectively.

In some aspects, each driver in the first driver array and the second driver comprises at least one of: comb drives, piezoelectric devices, or electromagnetic devices.

In some aspects, the apparatus further includes motion sensors, each motion sensor coupled with each rotating mirror and the second rotating mirror of the first rotating mirror array and configured to measure an angle of rotation of each rotating mirror and the second rotating mirror of the first rotating mirror array. The controller is further configured to: receiving data from a motion sensor; and determining a signal for each driver of the first and second rotating mirrors based on the data such that each rotating mirror in the first array of rotating mirrors and the second rotating mirror rotate at the first and second target angles, respectively.

In some embodiments, a method is provided. The method further comprises the following steps: determining a first angle and a second angle of an optical path, the optical path being one of a projection path for output light or an input path for input light, the first angle being associated with a first dimension and the second angle being associated with a second dimension orthogonal to the first dimension; controlling a first driver array to rotate a first rotating micro-mirror array of a micro-electro-mechanical system (MEMS) to set a first angle; controlling a second driver to rotate a second rotating mirror of the microelectromechanical system to set a second angle; projecting a light beam comprising a light signal using a light source to a mirror assembly comprising a first array of rotating mirrors and a second rotating mirror; and setting the first rotating mirror array to a first angle and the second rotating mirror array to a second angle, and performing at least one of the following operations: output light from a light source is reflected along a projection path to an object, or input light propagating along an input path is reflected to a receiver.

In some aspects, the method further comprises: controlling a light source to emit output light comprising a first light signal at a first time; controlling the first driver array and the second driver to output light comprising the first optical signal along the optical path towards the object; controlling the first and second driver arrays to select input light, the input light comprising a second optical signal propagating from the object along the optical path; receiving, by the receiver, a second optical signal at a second time; the position of the object is then determined based on the difference between the first time and the second time, the first angle, and the second angle.

In some aspects, the method further comprises: adjusting a first rotation angle of each rotating mirror of the first array of rotating mirrors at a first frequency; the second angle of rotation of the second rotating mirror is adjusted at a second frequency, which is higher than the first frequency, the second frequency being substantially equal to the natural frequency of the second rotating mirror.

In some aspects, the method further comprises: receiving information indicative of a first angle of rotation of each rotating mirror of the first array of rotating mirrors and information indicative of a second angle of rotation of the second rotating mirror from the motion sensor; adjusting a first control signal to the first driver array based on a difference between the first rotation angle and the first target rotation angle; the second control signal to the second driver is then adjusted based on a difference between the second angle of rotation and the second target angle of rotation.

In some embodiments, a non-transitory computer-readable medium is provided. The computer instruction medium stores instructions that, when executed by the hardware processor, cause the hardware processor to: determining a first angle and a second angle of an optical path, the optical path being one of a projection path for outputting light or an input path for inputting light, the first angle being associated with a first dimension, the second angle being associated with a second dimension orthogonal to the first dimension; controlling a first driver array to rotate a first rotating micromirror array of a set of micro-electromechanical systems (MEMS) to set at a first angle; controlling a second driver to rotate a second rotating mirror of the microelectromechanical system to set at a second angle; projecting a light beam comprising a light signal using a light source to a mirror assembly comprising a first array of rotating mirrors and a second rotating mirror; when the first rotating mirror array is set to a first angle and the second rotating mirror array is set to a second angle, performing at least one of: output light from a light source is reflected along a projection path to an object, or input light propagating along an input path is reflected to a receiver.

In some aspects, the computer-readable medium further stores instructions that, when executed by the hardware processor, cause the hardware processor to control the light source to emit output light comprising a first light signal at a first time; controlling the first driver array and the second driver to output light comprising the first optical signal along the optical path towards the object; controlling the first driver array and the second driver to select input light, the input light comprising a second optical signal propagating from the object along the optical path; receiving, by the receiver, a second optical signal at a second time; and determining the position of the object based on the difference between the first and second times and the first and second angles.

In some aspects, the computer-readable medium further stores instructions that, when executed by the hardware processor, cause the hardware processor to: adjusting a first rotation angle of each rotating mirror of the first array of rotating mirrors at a first frequency; and adjusting a second angle of rotation of the second rotating mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to the natural frequency of the second rotating mirror.

Drawings

The detailed description refers to the accompanying drawings.

FIG. 1 illustrates an autonomous vehicle that utilizes aspects of some embodiments of the technology disclosed herein.

Fig. 2A and 2B illustrate examples of light turning systems according to some embodiments.

Fig. 3A-3E illustrate an example of a mirror assembly and its operation according to some embodiments.

Fig. 4 illustrates an example of operation of the mirror assembly of fig. 3A-3E to provide a two-dimensional field of view (FOV), in accordance with some embodiments.

Fig. 5A and 5B illustrate another example of a mirror assembly according to some embodiments.

Fig. 6 illustrates another example of a mirror assembly according to some embodiments.

Fig. 7 illustrates another example of a mirror assembly according to some embodiments.

Fig. 8 illustrates a flowchart of a method of operation of a mirror assembly according to some embodiments.

FIG. 9 illustrates an example computer system that can be used to implement the techniques disclosed herein.

Detailed Description

In the following description, various examples of mirror assemblies and light turning systems will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that some embodiments may be practiced or carried out without every detail disclosed. Furthermore, well-known features may be omitted or simplified in order not to obscure the novel features described herein.

Light turning can be found in different applications. For example, the light detection and ranging module of the vehicle may include a light steering system. A light steering system may be part of the transmitter to steer the light in different directions to detect obstacles around the vehicle and determine the distance between the obstacles and the vehicle, which may be used for autonomous driving. In addition, the receiver may also include a micro-mirror array to select the direction of incident light to be detected by the receiver to avoid detecting other unwanted signals. Furthermore, the headlamps of a manually driven vehicle may include a light steering system that may be controlled to focus light in a particular direction to improve the driver's field of view. In another example, an optical diagnostic device, such as an endoscope, may include a light-redirecting system to redirect light onto an object in different directions during sequential scans to obtain images of the object for diagnosis.

Light turning can be achieved by a micromirror array. The micromirror array may have an array of micromirror assemblies, wherein each micromirror assembly has a movable micromirror and a driver (or drivers). The micromirrors and drivers may be formed on a semiconductor substrate as a mems, so that the mems may be integrated with other circuits (e.g., controller, interface circuit, etc.) on the semiconductor substrate. In a micromirror assembly, the micromirror may be connected to a semiconductor substrate by a connecting structure (e.g., torsion bars, springs, etc.) to form a pivot. The actuator can pivot the micromirror, wherein the link structure deforms to accommodate the rotation. The micromirror array may receive an incident light beam, and each micromirror may rotate at a common rotation angle to project/steer the incident light beam in a target direction. Each micromirror is rotatable about two orthogonal axes to provide a first range of projection angles in a vertical direction and a second range of projection angles in a horizontal direction. The first and second ranges of projection angles may define a two-dimensional field of view (FOV) in which light is projected to detect/scan an object. The FOV may also determine the direction of incident light reflected by an object detected by the receiver.

In some embodiments, each micromirror assembly may comprise a single micromirror. A single micromirror may be coupled with a pair of actuators on a frame of a gimbal structure and rotatable about a first axis. The frame of the gimbal structure is also coupled to the semiconductor substrate and is rotatable about a second axis orthogonal to the first axis. The first pair of actuators may rotate the mirror relative to the frame about a first axis to turn the light along a first dimension, and the second pair of actuators may rotate the frame about a second axis to turn the light along a second dimension. Different combinations of rotation angles about the first and second axes may provide a two-dimensional FOV in which light is projected to detect/scan an object. The FOV may also determine the direction of incident light reflected by an object detected by the receiver.

While such an arrangement allows the projection of light to form a two-dimensional FOV, there may be a number of potential disadvantages. First, having a single mirror to provide light steering may require relatively high driving forces to achieve the target FOV and target dispersion, which may reduce reliability. More specifically, to reduce dispersion, the size of the mirror may be matched to the width of the beam from the light source, thereby increasing the mass and inertia of the mirror. Therefore, a greater driving force (e.g., torque) is required to rotate the mirror to achieve the target FOV. The torque required is typically in the order of microns N-m. Subjecting the actuator to a large driving force, especially for mems actuators, reduces the lifetime and reliability of the actuator. Furthermore, when the light-turning system relies on only a single mirror to turn the light, the reliability of the MEMS actuator may be further reduced, which may be a single point of failure.

Conceptual overview of some embodiments

Examples of the present application relate to a light redirecting system that may address the above-mentioned issues. Various embodiments of the light turning system may include at least two mirrors for performing light turning, such as the mirrors shown and described below with respect to fig. 3A-3E, 5A, 6, and 7. A light redirecting system may be used as part of the emitter to control the direction of projection of the output light. The light redirecting system may also be used as part of a receiver to select the direction of input light to be detected by the receiver. The light redirecting system may also be used in a coaxial configuration such that the light redirecting system can project output light to a location and detect light reflected from the location.

In some embodiments, a light turning system may include a light source, a first turning mirror, a second turning mirror, and a receiver. The first and second rotating mirrors may determine an output projection path of light emitted by the light source or select an input path of input light to be received by the receiver. The first and second rotating mirrors may rotate at different angles associated with a first dimension and associated with a second dimension orthogonal to the first dimension, respectively, to steer the output projection path or the input path to form a two-dimensional FOV.

The light turning system may further include a first driver configured to rotate the first turning mirror about a first axis; a second driver configured to rotate the second rotating mirror about a second axis orthogonal to the first axis; and a controller coupled to the first driver and the second driver. The controller may control the first and second drivers to apply first and second torques to rotate the first and second rotating mirrors along the first and second axes, respectively. The controller may control the first and second drivers to steer the output projection path or the input path at different angles relative to the first dimension and relative to the second dimension according to a sequence of motions, such as those shown and described below with reference to fig. 4 and 5B, to create a two-dimensional FOV.

In some embodiments, the first rotating mirror and the second rotating mirror may be disposed on the same surface of the semiconductor substrate, as shown in fig. 3A. The light redirecting system can also include a fixed third mirror stacked on top of and facing the surface of the semiconductor substrate. As shown in fig. 3B, light from a light source or input light from the environment may be reflected by a first rotating mirror, which may set a first angle at which an output projection path of the light is associated with a first dimension (e.g., x-axis or y-axis). The light reflected by the first rotating mirror may reach a third mirror, which may reflect the light to the second rotating mirror. The second turning mirror may set an angle of the output projection path or the input path relative to a second dimension (e.g., the z-axis of fig. 4D). By rotating the first and second rotating mirrors to form the FOV, different values of the first and second angles may be obtained.

In some embodiments, as shown in FIG. 3A, the light turning system may include a first mirror array and a single second turning mirror that is rotatable about a second axis. The first mirror array includes first rotating mirrors, each rotating mirror of the array being rotatable about a first axis. In some embodiments, as shown in fig. 5A, the light turning system may further include a single first turning mirror and a second turning mirror array, each turning mirror in the second turning mirror array being rotatable about a second axis. In some embodiments, as shown in fig. 6, the light turning system may further include a first rotating mirror array and a second rotating mirror array. The first rotating mirror array may rotate about a first axis. Also, the second rotating mirror array may rotate about a second axis.

In some embodiments, the first turning mirror and the second turning mirror may be disposed on two different semiconductor substrates, as shown and described below in fig. 7. The first rotating mirror may be disposed on a first surface of the first semiconductor and the second rotating mirror may be disposed on a second surface of the second semiconductor, the first surface facing the second surface. Light from the light source may be reflected by a first rotating mirror, which may set a first angle at which the output projection path or the input path is associated with a first dimension (e.g., x-axis or y-axis). The light reflected by the first rotating mirror may reach a second rotating mirror, which may rotate about a second axis to set a second angle at which the output projection path or the input path is associated with a second dimension (e.g., the z-axis).

In contrast to arrangements in which a light turning system provides two angular ranges of projection or input to form the FOV using a single mirror with two axes of rotation, some embodiments of the present application may use first and second (or first and second) turning mirrors, each with a single but orthogonal axis of rotation, to provide two angular ranges forming the FOV. Such an arrangement may improve reliability (especially where the mirror is a mems device) and accuracy, and may reduce drive power while providing the same or better FOV and dispersion. First, by using two mirrors to provide two angular ranges to provide the same FOV as a single mirror, some mirrors can be smaller than a single mirror, and their rotation requires less driving force than a single mirror. The drive of the two different mirrors can also be optimized independently to further reduce the total drive force. The reduction in driving force can also reduce the load on the actuator and extend the life of the actuator. Also, since the mirrors are smaller, embodiments of the present application may provide a larger FOV than a single mirror embodiment in response to the same driving force. The mirrors in embodiments of the present application may be configured to provide the same mirror surface area and to provide the same dispersion as a single mirror. In addition, where at least two mirrors participate in the light turning, the likelihood of any mirror becoming a single source of failure may be reduced, which may further improve reliability. All of this may improve the robustness and performance of the light redirecting system over conventional implementations.

Exemplary System Environment for some embodiments

FIG. 1 illustrates an autonomous vehicle 100 in which the disclosed technology may be implemented. The autonomous vehicle 100 includes a LiDAR module 102. The LiDAR module 102 allows the autonomous vehicle 100 to perform object detection and ranging in the surrounding environment. Based on the results of object detection and ranging, the autonomous vehicle 100 may move to avoid collision with an object. The LiDAR module 102 may include a light-turning system 104 and a receiver 106. The light steering system 104 may project one or more light signals 108 in different directions at different times in any suitable scanning mode, and the receiver 106 may monitor the light signal 110 generated by the object reflecting the light signal 108. The optical signals 108 and 110 may include, for example, optical pulses, Frequency Modulated Continuous Wave (FMCW) signals, Amplitude Modulated Continuous Wave (AMCW) signals, and the like. The LiDAR module 102, based on the receipt of the light signal 110, may detect an object and may perform a ranging determination (e.g., a distance of the object) based on the time difference between the light signals 108 and 110. For example, as shown in FIG. 1, the LiDAR module 102 may transmit an optical signal 108 in a direction directly in front of the autonomous vehicle 100 at time T1 and receive an optical signal 110 reflected by an object 112 (e.g., another vehicle) at time T2. Based on receipt of the light signal 110, the LiDAR module 102 may determine that the object 112 is directly in front of the autonomous vehicle 100. Further, based on the time difference between T1 and T2, the LiDAR module 102 may also determine the distance 114 between the autonomous vehicle 100 and the object 112. Based on the detection and ranging of the object 112 by the LiDAR module 102, the autonomous vehicle 100 may adjust its speed (e.g., decelerate or stop) to avoid a collision with the object 112.

FIGS. 2A and 2B illustrate examples of internal components of a LiDAR module 102. The LiDAR module 102 includes a transmitter 202, a receiver 204, a LiDAR controller 206, the LiDAR controller 206 controlling the operation of the transmitter 202 and the receiver 204. The transmitter 202 includes a light source 208 and a collimator lens 210, while the receiver 204 includes a lens 214 and a photodetector 216. The LiDAR module 102 also includes a mirror assembly 212 and a beam splitter 213. In the LiDAR module 102, the transmitter 202 and receiver 204 may be configured as a coaxial system to share a mirror assembly 212 to perform light steering operations, with the beam splitter 213 configured to reflect incident light reflected by the mirror assembly 212 to the receiver 204.

Fig. 2A illustrates a light projection operation. To project light, the LiDAR controller 206 may control a light source 208 (e.g., a pulsed laser diode, a source of FMCW signals, AMCW signals, etc.) to emit the optical signal 108 as part of the beam of light 218. The light beam 218 may be dispersed as it exits the light source 208 and may be converted to a collimated light beam 218 by the collimator lens 210.

The collimated light beam 218 may be incident on a mirror assembly 212, and the mirror assembly 212 may reflect and turn the light beam along an output projection path 219 toward the object 112. Mirror assembly 212 may include one or more rotating mirrors. Fig. 2A shows the mirror assembly 212 having one mirror, but as described below, in some embodiments the mirror assembly 212 may include at least two mirrors.

The light beam 218 may be dispersed as it exits the surface of the mirror assembly 212. The light beam 218 may form a divergence angle with respect to the projection path 219 over the length and width of the mirror surface. The divergence angle of the beam 218 can be given by the following equation:

in equation 1, α is the dispersion angle, λ is the wavelength of the beam 218, and D is the length (or width) of the mirror, the beam 218 may be along the length (L) of the mirror with respect to the projection path219 at a divergent angle α_LDispersed and at a dispersion angle α relative to the projected path 219 along the width (W) of the mirror_WAnd (4) dispersing. It is desirable to reduce the divergence angle to focus the beam power on the projection path 219 to improve the resolution of object detection, ranging, and imaging. To reduce the dispersion angle, the length and width D of the mirror can be increased to match the aperture 220.

Mirror assembly 212 also includes one or more drives (not shown in fig. 2A) to rotate the rotating mirror. The drive may rotate the rotating mirror about a first axis 222 and may rotate the rotating mirror along a second axis 226. As described in more detail below, rotation about the first axis 222 may change a first angle 224 at which the output projected path 219 is associated with a first dimension (e.g., the x-axis), while rotation about the second axis 226 may change a second angle 228 at which the output projected path 219 is associated with a second dimension (e.g., the z-axis). The LiDAR controller 206 may control the drives to produce different combinations of angles of rotation about the first axis 222 and the second axis 226 such that the motion of the output projected path 219 may follow the scan pattern 232. The range of motion 234 of output projection path 219 along the x-axis and the range of motion 238 of output projection path 219 along the z-axis may determine the FOV. An object in the FOV, such as object 112, may receive and reflect collimated light beam 218 to form a reflected light signal, which may be received by receiver 204.

Fig. 2B shows the light detection operation. The LiDAR controller 206 may select the incident light direction 239 to detect incident light by the receiver 204. This selection may be based on the rotation angle of a rotating mirror that sets mirror assembly 212 such that only light beam 220 propagating along light direction 239 is reflected to beam splitter 213, and beam splitter 213 may then divert light beam 220 to photodetector 216 through collimator lens 214. With such an arrangement, the receiver 204 may selectively receive signals related to ranging/imaging of the object 112, such as the optical signal 110 generated by reflection of the object 112 on the straight beam 218, and no other signals. Thus, the impact of environmental interference on the range/imaging of the object may be reduced and system performance may be improved.

Examples of mirror assemblies

Fig. 3A-3E illustrate an example of a mirror assembly 300 according to an embodiment of the present application. Mirror assembly 300 may be part of light turning system 202. Fig. 3A shows a top view of mirror assembly 300, fig. 3B shows a perspective view of mirror assembly 300, and fig. 3C shows a side view of mirror assembly 300. As shown in fig. 3A, mirror assembly 300 may include a first rotating mirror array 302, a second rotating mirror 304, and a fixed mirror 306. The total mirror surface area of first rotating mirror array 302 is the same as the mirror surface areas of second rotating mirror 304 and fixed mirror 306. First rotating mirror array 302 and second rotating mirror 304 may be micro-electromechanical system devices implemented on surface 308 of semiconductor substrate 310. The fixed mirror 306 may be located above the semiconductor substrate 310. In some embodiments, the fixed mirror 306 may be included in the same integrated circuit package as the semiconductor substrate 310 to form an integrated circuit. In some embodiments, the fixed mirror 306 may also be located outside of the integrated circuit package housing the semiconductor substrate 310.

Referring to fig. 3B and 3C, in one configuration, first rotating mirror array 302 may receive collimated light beams 218 from collimator lens 210, reflect light beams 218 toward fixed mirror 306, and fixed mirror 306 may reflect light beams 218 toward second rotating mirror 304. Second turning mirror 304 may reflect light beam 218 received from fixed mirror 306 as an output along output projection path 219. In another configuration (not shown), second turning mirror 304 may receive collimated light beam 218 from collimator lens 210 and reflect light beam 218 toward fixed mirror 306, which fixed mirror 306 may reflect light beam 218 toward first turning mirror array 302. The first rotating mirror array 302 may reflect the light beam 218 as an output along an output projection path 219. Where mirror assembly 300 is part of a receiver, first rotating mirror array 302 and second rotating mirror 304 may also select incident light direction 239 for receiver 204 similar to selecting the direction of output projection path 219. As described in further detail below, first and second rotating mirrors 302 and 304 change the angle of output projection path 219 with respect to the x-axis and z-axis, respectively, to form a two-dimensional FOV.

As described above, the total mirror surface area of first rotating mirror array 302 is the same as the mirror surface areas of second rotating mirror 304 and fixed mirror 306. Further, each dimension (e.g., length and width) of the mirror surface area provided by each of the first rotating mirror array 302, the second rotating mirror 304, and the fixed mirror 306 may match the aperture 220 of the collimator lens 210. With this arrangement, each of first rotating mirror array 302, second rotating mirror 304, and fixed mirror 306 may receive and reflect a substantial portion of collimated light beam 218.

Further, as shown in FIG. 3C, the spacing between fixed mirror 306 and (including surface 308 of first rotating mirror array 302 and second rotating mirror 304, denoted as d1, and the spacing between the center points of first rotating mirror array 302 and second rotating mirror 304, d2, may be related to the angle of incidence θ of collimated light beam 218 with respect to the z-axis, as follows:

in equation 2, the ratio between half of d2 (the distance between the center points of first rotating mirror array 302 and second rotating mirror 304) and half of d1 (the distance between fixed mirror 306 and surface 308) may be determined by applying a tangent function to the angle of incidence θ of collimated light beam 218.

Referring again to FIG. 3A, each rotating mirror in the array of first rotating mirrors 302 (e.g., first rotating mirror 302a) may rotate about a first axis 314, while second rotating mirror 304 may rotate about a second axis 316 that is orthogonal to first axis 314. Each rotating mirror in the array of first rotating mirrors 302 and second rotating mirror 304 is coupled to a pair of rotating actuators, such as comb actuators, piezoelectric devices, electromagnetic devices, and the like, to rotate the mirrors. For example, first turning mirror 302a is coupled with turning drivers 322a and 322b, and second turning mirror 304 is coupled with turning drivers 324a and 324 b. Each of first rotating mirror 302a (and the remaining rotating mirrors of first rotating mirror array 302) and second rotating mirror 304 may independently move output projection path 219 along the x-axis and z-axis, respectively, to form the FOV.

Fig. 3D shows an example of setting the angle of the output projection path 219 with respect to the x-axis based on the rotational movement of the first rotating mirror 302 a. Fig. 3D shows a side view of rotating mirror 302a having first axis 314, fixed mirror 306, and second rotating mirror 304. The first axis 314 is aligned with the y-axis. The dotted line shows the direction of the first rotating mirror 302a before rotation and the normal vector 330 of the first rotating mirror 302a, and the solid line shows the direction of the first rotating mirror 302a after counterclockwise rotation and the normal vector 330. As first turning mirror 302a rotates counter-clockwise, normal vector 330 of first turning mirror 302a also rotates counter-clockwise, and the angle of incidence 332 of collimated light beam 218 relative to rotating normal vector 330 decreases. Since the reflected angle 334 of the collimated beam 218 is equal to the incident angle 332, the reflected beam 218 also rotates counterclockwise and strikes the fixed mirror 306 at an increased angle 336. Light beam 218 is also reflected at the same angle 336 from fixed mirror 306 toward second rotating mirror 304. second rotating mirror 304 may reflect light beam 218 along either output projection path 219 or input path 239, where input path 239 also forms an angle 336 with the x-axis. Each rotating mirror in first rotating mirror array 302 may be controlled to rotate in the same direction (clockwise or counterclockwise) by the same angle about first axis 314, such that the arrays may collectively position output projection path 219 of collimated light beam 218 or incident light direction 239 to form angle 336 relative to the x-axis.

Fig. 3E illustrates an example of outputting the motion of the projection path 219 based on the rotational motion of the second rotating mirror 304. FIG. 3E is a side view of second turning mirror 304, where second axis 316 points out of the paper. The dashed lines show the direction of second turning mirror 304 and normal vector 340 of second turning mirror 304 before rotation, while the solid lines show the direction of second turning mirror 304 and normal vector 340 after counterclockwise rotation. As second turning mirror 304 is rotated counter-clockwise, normal vector 340 of second turning mirror 304 is also rotated counter-clockwise, and the angle of incidence 342 of collimated light beam 218 relative to rotated normal vector 340 decreases. Since the reflected angle 344 of the collimated light beam 218 is equal to the incident angle 342, the output projection path 219 of the reflected light beam 218 moves along the z-axis a distance d4, as indicated by the arrow. In conjunction with the rotation of first rotating mirror 302a, output projection path 219 may be moved along the x-axis and z-axis to form a two-dimensional FOV. It will be appreciated that incident light direction 239 may also be adjusted in a similar manner to output projection path 219 based on rotational movement of second turning mirror 304.

Fig. 4 illustrates an example operation of mirror assembly 300 to provide a two-dimensional FOV. The top diagram of fig. 4 shows a sequence 400 of movements of the angles of the output projection path 219 provided by the rotation of the first rotating mirror array 302 and the second rotating mirror 304. As shown in FIG. 4, the LiDAR controller 206 may control rotation drives 324a and 324b to rotate the second rotating mirror 304 to set different angles of the output projection path 219 relative to the z-axis, e.g., the angles represented by point 402 and point 404, within a first angular range 406. The LiDAR controller 206 may also control the rotational drives (e.g., rotational drives 322a and 322b) of the first rotating mirror array 302 to set different angles of the output projection path 219 relative to the x-axis, e.g., the angles represented by point 412 and point 414, to provide a second angular range 416, which may determine the FOV.

The bottom diagram of fig. 4 shows a sequence of control signals 430 with respect to time to generate a sequence of movements 400 of the output projected path 219. In some embodiments, the motion sequence 400 may be provided to the LiDAR controller 206, and the LiDAR controller 206 may generate a control signal sequence 430 based on the motion sequence 400. Control signal sequence 430 includes a first dimension control signal sequence 432, 434, 436, etc. of control signals for a rotation driver of second rotating mirror 304 to change an angle of output projection path 219 (or incident light direction 239) relative to a first dimension (e.g., z-axis). The control signal sequence 430 further includes a second size control signal between the two first size control signal sequences. For example, there is a second size control signal 440 between the first size control signal sequences 432 and 434. Further, a second size control signal 442 is present between the first size control signal sequences 434 and 436. The second dimension control signal is applied to a rotation driver of first rotating mirror array 302 to change the angle at which output projection path 219 (or incident light direction 239) is related to the second dimension (e.g., x-axis).

Each of the series of control signals 432, 434, 436, etc. may cause the rotational drive of second rotating mirror 304 to generate a torque force to increase the angle of rotation of second rotating mirror 304 about second axis 316. For example, first size control signal 432a may correspond to point 402 and first size control signal 432b may correspond to point 404. Each of the first series of dimension control signals 432, 434, and 436 may cause the angle of the output projection path 219 (or incident light direction 239) with respect to the z-axis to be through the first angular range 406 by controlling the angle of rotation of the second rotating mirror. At the end of the first angular range 406, a second size control signal may be provided to change the angle of projection path 219 (or incident light direction 239) relative to the x-axis before the next sequence of first size control signals begins. For example, the first size control signal 432n corresponds to the point 412 at the end of the first angular range 406. Following the first size control signal 432b is a second size control signal 440, which second size control signal 440b may rotate first rotating mirror array 302 to move output projection path 219 (or incident light direction 239) along the x-axis from point 412 to point 414. After second size control signal 440, first size control signal sequence 434 begins and first size control signal 434a may rotate second rotating mirror 304 to move the angle of output projection path 219 (or incident light direction 239) with respect to the z-axis from the angle represented by point 414 to the angle represented by point 418 while the angle with respect to the x-axis remains constant.

In some embodiments, the first size control signal and the second size control signal may be independently optimized to reduce the total driving force and power. For example, a first size control signal may be provided to the rotary drive at a higher frequency near the natural frequency of second rotary mirror 304 to cause harmonic resonance of the mirror. Such an arrangement allows for the use of less torque to rotate the second rotating mirror 304, which is advantageous because the second rotating mirror 304 may be the largest mirror within the mirror assembly 300 and have a substantial mass and inertia. On the other hand, a second size control signal may be provided to the rotary driver at a relatively low frequency to operate each of the rotating mirrors in the first rotating mirror array 302 as a quasi-static load. The torque required to rotate the mirrors of the first rotating mirror array 302 is relatively low, since the mirrors are small and have a small mass and inertia. In some embodiments, the first size control signal may be in the form of a high frequency sine wave signal, a Pulse Width Modulated (PWM) signal, or the like, and the second size control signal may be in the form of a low frequency sawtooth signal.

In some embodiments, in addition to the motion sequence 400, a feedback mechanism may also be provided to the LiDAR controller 206 to generate a sequence of control signals 430. The feedback mechanism includes a set of sensors (e.g., capacitive sensors) for measuring the actual angle of rotation of the rotary drive. Based on monitoring the actual angle of rotation of the rotary drive, the feedback mechanism LiDAR controller 206 can adjust the first and second dimensional control signals provided to the rotary drive to improve the accuracy of the light turning operation. This adjustment may be performed to compensate for, for example, uncertainty and mismatch in mirror mass, drive strength of the rotary drive, and the like.

As an example, the LiDAR controller 206 may perform the adjustment of the first size control signal and the second size control signal in a calibration order. The LiDAR controller 206 may store a set of initial settings (e.g., voltages, currents, etc.) for the first size and second size control signals based on the expected mass of a set of mirrors and the drive strength of the rotary drive. During a calibration process, the LiDAR controller 206 may provide different first and second size control signals to create different angles of rotation at the rotary drive. When providing the first and second dimension control signals, the LiDAR controller 206 may monitor the actual angle of rotation of the rotary drive, compare the actual angle of rotation to a target angle of rotation to determine a difference, and adjust the first and second dimension control signals to account for the difference. For example, each rotating mirror in the first array of rotating mirrors 302 should rotate at the same angle of rotation. The LiDAR controller 206 may measure the actual angle of rotation of each rotating mirror in the first array of rotating mirrors 302 using a capacitive sensor and determine the deviation of each actual angle from the target angle of rotation of each rotating mirror. The LiDAR controller 206 may adjust the second dimension control signal of the rotation driver (e.g., rotation drivers 322a and 322b) of each rotating mirror based on the offset to ensure that each rotating mirror rotates at the same target angle of rotation.

Mirror assembly 300 may provide the same or better FOV and dispersion performance than a single mirror assembly, while reducing drive force and power, and improving reliability. First, each rotating mirror in the first array of rotating mirrors 302 is much smaller than a single mirror with comparable length and width and dispersion properties, even if the mirrors are driven as quasi-static loads. Thus, each rotating mirror in the first array of rotating mirrors 302 requires substantially less torque to provide the same FOV as a single mirror assembly. Further, although the mirror surface area of the second rotating mirror 304 is similar to that of a single mirror arrangement, by driving the second rotating mirror 304 at a frequency close to the natural frequency to cause harmonic resonance, the torque required to rotate the second rotating mirror 304 can be greatly reduced. Such an arrangement may substantially reduce the torque required to achieve the target FOV. The reduction in torque also relieves the rotary drive of its burden and extends its useful life. In addition, since at least two mirrors participate in the turning of light, the probability of any one mirror becoming a single source of failure can be reduced, which can further improve reliability.

Fig. 5A shows another example of a mirror assembly 500 according to an embodiment of the present application. Mirror assembly 500 may be part of light turning system 202. As shown in fig. 5A, the mirror assembly 500 may include a first rotating mirror 502, a second rotating mirror array 504, and a fixed mirror 306. Each of first rotating mirror 502, second rotating mirror array 504, and fixed mirror 306 may have substantially the same mirror surface area and may be sized to match aperture 220 of lens 210, as in the other examples described above. The first and second rotating mirrors 502, 504 may be MEMS devices implemented on a surface 508 of a semiconductor substrate 510. The fixed mirror 306 may be located above the semiconductor substrate 510. The first rotating mirror 502 may receive the collimated light beam 218 from the lens 210, reflecting the collimated light beam 218 toward the fixed mirror 306, which may in turn reflect the collimated light beam 218 toward the second rotating mirror array 504. The second rotating mirror array 504 may reflect the collimated light beams 218 received from the fixed mirror 306 as output along an output projection path 219. First rotating mirror 502 may rotate about a first axis 514, and each rotating mirror in second rotating mirror array 504 may rotate about a second axis 516 that is orthogonal to first axis 514. Just like the first rotating mirror array 302 of FIG. 3A, the rotation of the first rotating mirror 502 can be set to the angle of the output projection path 219 (or incident light direction 239) with respect to the x-axis, while the rotation of the second rotating mirror array 504 can be set to the angle of the output projection path 219 with respect to the z-axis (or incident light direction 239).

First rotating mirror 502 and second rotating mirror array 504 may independently vary the angle of output projection path 219 (or incident light direction 239) with respect to the x-axis and z-axis, respectively, to form a two-dimensional FOV. The rotation of first rotating mirror 502 and second rotating mirror array 504 may be controlled based on motion sequence 550 of FIG. 5B. The first rotating mirror 502 can be controlled by a first size control signal to move the output projection path 219 (or incident light direction 239) along the x-axis over a range of motion 552, while the second rotating mirror array 504 can be controlled by a second size control signal to move the projection path along the z-axis over a range of motion 554. Similar to the configuration depicted in FIG. 4, the first size control signal may be provided at a relatively high frequency near the natural frequency of the first turning mirror 502 to cause harmonic resonance; however, the second size control signal may be provided at a lower frequency to drive each of the second rotating mirrors of the second rotating mirror array 504 as a quasi-static load.

In some examples, the mirror assembly may include two rotating mirror arrays to perform light turning along a first dimension (e.g., x-axis) and a second dimension (e.g., z-axis). Fig. 6 shows an example of a mirror assembly 600 that includes the first rotating mirror array 302 of fig. 3A and the second rotating mirror array 504 of fig. 5A on a surface 608 of a semiconductor substrate 610. Mirror assembly 600 also includes a fixed mirror 306 positioned over semiconductor substrate 610. First rotating mirror array 302 is rotatable about a first axis 314, and second rotating mirror array 504 is rotatable about a second axis 516 orthogonal to first axis 314. First rotating mirror array 302 and second rotating mirror array 504 may independently vary the angle of output projection path 219 with respect to the x-axis and z-axis, respectively, to form a two-dimensional FOV, as described above.

Fig. 7 shows another example of a mirror assembly 700 according to an embodiment of the present application. Mirror assembly 700 may be part of light turning system 202. The top view of fig. 7 shows a top view of mirror assembly 700, while the bottom view of fig. 7 shows a perspective view of mirror assembly 700. As shown in fig. 7, mirror assembly 700 may include a first rotating mirror array 302, a second rotating mirror 704, and an optional mirror 706, which may be fixed or rotatable. The first turning mirror array 302 and the mirror 706 may be implemented as a surface 708 of a first semiconductor substrate 710, while the second turning mirror 704 may be implemented on a second semiconductor substrate (not shown in fig. 7) and directed toward the first turning mirror array 302 and the mirror 706. Each of first turning mirror array 302, second turning mirror 704, and mirror 706 may have substantially the same mirror surface area with each dimension matching aperture 220 of lens 210, as described in other examples above. First turning mirror array 302 may receive collimated light beam 218 (or reflected light beam 220) and reflect light toward second turning mirror 704, and second turning mirror 704 may reflect light from first turning mirror array 302 toward mirror 706. The mirror 706 can reflect light received from the second turning mirror 704 as output along the output projection path 219. Mirror 706 may also reflect input light toward second turning mirror 704, and only light traveling along incident light direction 239 will be reflected to first turning mirror array 302. The first rotating mirror array 302 is rotatable about a first axis 314, while the second rotating mirror 704 is rotatable about a second axis 724 that is orthogonal to the first axis 314. The rotation of each rotating mirror of first rotating mirror array 302 may be set to the angle of output projection path 219 (or incident light direction 239) relative to the x-axis, while the rotation of second rotating mirror 704 may be set to the angle of output projection path 219 (or incident light direction 239) relative to the z-axis. The mirror 706 may be fixed or may be rotatable to allow further adjustment of the direction of the output projection path 219 (or incident light direction 239).

Fig. 8 shows a simplified flow diagram of a method 800 for performing a light turning operation using a mirror assembly, such as mirror assemblies 300, 500, 600, and 700 of fig. 3A-7. The mirror assembly includes a first rotating mirror array (e.g., first rotating mirror array 302, second rotating mirror array 504, etc.) and a second rotating mirror (e.g., second rotating mirror 304, first rotating mirror 502, second rotating mirror 704, etc.). The first array of rotating mirrors and the second rotating mirror may be part of a micro-electromechanical system. The method 800 may be performed by a controller, such as the LiDAR controller 206.

At operation 802, a controller determines a first angle and a second angle of an optical path, the optical path being one of a projection path for output light or an input path for input light, the first angle being associated with a first dimension, the second angle being associated with a second dimension orthogonal to the first dimension. The first angle may be set within the angular range 416 of fig. 4 according to the scanning pattern (e.g., the motion sequence 400). The second angle may be set within the angular range 406 of fig. 4 according to the scanning pattern (e.g., the motion sequence 400).

At operation 804, the controller controls the first driver array to rotate a first rotating mirror array of the microelectromechanical system to set a first angle. The controller may control the first driver array to apply a torque to each of the rotating mirrors of the first rotating mirror array as a quasi-static load.

At operation 806, the controller controls a second driver of the microelectromechanical system to rotate the second rotating mirror to set a second angle. The controller may control the second driver to apply a torque to the second rotating mirror to cause harmonic resonance of the mirror to reduce the required torque.

At operation 808, the controller performs at least one of the following using the first rotating mirror array and the second rotating mirror by setting the first rotating mirror array to a first angle and the second rotating mirror to a second angle: output light from a light source is reflected along a projection path onto an object, or input light propagating along an input path is reflected to a receiver. For example, the controller may control the light source to project a light beam including a light signal to the mirror assembly. The light source may include a pulsed laser diode, an FMCW signal source, an AMCW signal source, or the like. The controller may also direct an input optical signal reflected by a distant object to the receiver using the first and second rotating mirrors, without directing optical signals received in other directions to the receiver.

Computer system

Any computer system mentioned herein may utilize any suitable number of subsystems. An example of such a subsystem is shown in fig. 9 in computer system 10. In some embodiments, the computer system comprises a single computer device, wherein the subsystems may be components of the computer device. In other embodiments, a computer system may include multiple computer devices, each being a subsystem, with internal components. Computer systems may include desktop and laptop computers, tablets, mobile phones, and other mobile devices. In some embodiments, cloud infrastructures (e.g., amazon web Services), Graphics Processing Units (GPUs), and the like, may implement the disclosed techniques, including the techniques described in fig. 1-8. For example, the computer system 10 may implement the functionality of the LiDAR controller 206 and perform the operations of the method 800.

The subsystems shown in fig. 9 are interconnected by a system bus 75. Additional subsystems such as a printer 74, keyboard 78, storage 79, monitor 76, and coupling to a display adapter 82, among others, are shown. Peripheral devices and input/output (I/O) devices connected to I/O controller 71 may be connected to the computer system by any number of means known in the art, such as input/output (I/O) ports 77 (e.g., USB,). For example, I/O port 77 or external interface 81 (e.g., Ethernet, Wi-Fi, etc.) may be used to connect computer system 10 to a wide area network, such as the Internet, a mouse input device, or a scanner. The interconnection via system bus 75 allows central processor 73 to communicate with each subsystem and to control the execution of at least two instructions from system memory 72 or storage device 79 (e.g., a fixed magnetic disk such as a hard drive or optical disk), as well as the exchange of information between subsystems. System memory 72 and/or storage device 79 may embody a computer-integrated medium. Another subsystem is a data collection device 85 such as a camera, microphone, accelerometer, etc. Any of the data mentioned herein may beFor output from one component to another and possibly to a user.

The computer system may include at least two identical components or subsystems, e.g., connected together through an external interface 81 or an internal interface. In some embodiments, computer systems, subsystems, or devices may communicate over a network. In this case, one computer may be considered a client and another computer may be considered a server, where each computer may be considered part of the same computer system. A client and server may each comprise multiple systems, subsystems, or components.