Scanning mirror with biaxial universal joint structure

Abstract

A dual axis MEMS mirror assembly is disclosed. The assembly has a mirror and two arms, each having a rotational degree of motion and a translational degree of freedom. Each arm is hingedly connected to opposite ends of the mirror. And a first pair of actuators connected to opposite ends of the first arm. And a second pair of actuators connected to opposite ends of the second arm. The mirror is rotated about a first axis by the first arm and the second arm when the first pair of actuators and the second pair of actuators are rotated in the same angular direction to translate the arms at the translational degree of freedom. The mirror is rotated about a second axis by the first arm and the second arm when the first pair of actuators and the second pair of actuators are rotated in opposite angular directions to move the arms at the rotational degree of motion.

Description

[0001] Cross-referencing related applications This application claims the benefit and priority of U.S. Patent Application No. 18 / 477,316, filed on September 28, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure generally relates to MEMS structures. More specifically, aspects of this disclosure relate to a MEMS scanning mirror assembly with biaxial, in-plane actuators to allow the mirror to have multiple tilt angles. Background Technology

[0003] Micro-electromechanical systems (MEMS) are miniature devices that combine electronic components and physically moving parts. Typical MEMS devices are fabricated on one or more silicon wafers using integrated circuit processes. This fabrication process forms the physically moving parts by creating different materials that can be deposited onto and etched away from the substrate wafer.

[0004] MEMS have numerous applications, such as in microphones, sensors, accelerometers, and LiDAR (light detection and ranging) systems. MEMS fabrication is inherently two-dimensional, forming physical structures on a substrate. Custom offsets of such structures add another dimension to the topology and functionality of MEMS. However, offset structures are often defined / limited by the size of external tools and / or assembly precision in the manufacturing process. High specific strength, well-defined surfaces, and other features are desired in such structures. However, fabricating structures with these characteristics using existing manufacturing techniques is a challenge.

[0005] Scanning mirrors play a crucial role in a wide range of optical applications, from barcode scanners to complex optical detection and ranging systems. These mirrors are used to guide light beams to a specific field of view or change the direction of beam propagation. The accuracy of the scanning process (primarily determined by factors such as scanning angle, beam diameter, and frequency) is a key characteristic of these mirrors.

[0006] Figure 1 illustrates a prior art MEMS-based mirror system 10. The mirror system 10 includes a circular mirror 12 mounted on a support post 14. One end of the support post 14 is connected to the bottom of the mirror 12. The other end of the support post 14 is connected to a movable plate 16. A set of four electrostatic actuators 20, 22, 24, and 26 are rotatable on their respective flexible members 30 and 32. Thus, actuator 20 can be rotated by electrostatic forces on the flexible members 30 and 32. Actuators 20, 22, 24, and 26 are each connected to an end of a support plate flexible member 40, which is perpendicular to the axis defined by the flexible members 30 and 32. The opposite end of the support plate flexible member 40 is connected to a vertical plate flexible member 42, which contacts the edge of the movable plate 16. When electrostatic actuators 20, 22, 24, and 26 rotate about the axis between flexible members 30 and 32, plate flexible member 42 is used to pull movable plate 16 toward or away from the reference surface. The length of column 14 is used to create an offset between the center of mass and the center of rotation of mirror 12.

[0007] Plate flexible elements 40 and 42 serve as bending springs, facilitating the transmission of rotational motion of actuators 20, 22, 24, and 26 to plate 16. This, in turn, tilts mirror 12 via column 14. The specific layout and function of these flexible elements serving as springs illustrate conventional methods for transmitting rotational motion in scanning mirror design.

[0008] However, existing scanning mirror designs, such as those shown in Figure 1, often have limitations. These limitations include increased production costs and compromised durability, primarily as a result of the physical configuration and structural complexity involved in their assembly. For example, as shown in Figure 1, it is common to mount a large-diameter mirror on top of a smaller gimbal pivot plate. This arrangement results in an offset between the center of mass of mirror 12 and its center of rotation.

[0009] This displacement of the center of mass presents significant challenges. The most important of these is the induction of undesirable vibration modes. When mirror 12 is in operation, these vibration modes exert mechanical stress on mirror 12 and its supporting structure. Over time, this accumulated stress shortens the lifespan of the mirror assembly, affecting its durability. Furthermore, this displacement introduces a risk of impact fracture. The unbalanced weight distribution leads to increased sensitivity to impacts, potentially causing mirror 12 to fracture upon movement or a sudden change in orientation.

[0010] Another significant problem associated with vibrations caused by offset is the degradation of image stability. Vibrations can lead to undesirable deviations during positioning mirror 12, which in turn disrupts the stability of the reflected image. This disturbance results in a significant degradation in image quality, limiting the overall performance and reliability of systems that rely on scanning mirrors.

[0011] Given these shortcomings, an improved MEMS scanning mirror design is clearly needed to mitigate these challenges. Specifically, a design is required that allows the gimbal's center of mass to coincide with or nearly coincide with its center of rotation. A MEMS mirror assembly that can be manufactured to accommodate precision actuators is also required. Summary of the Invention

[0012] The terms "examples" and similar terms are intended to broadly refer to the entire subject matter of this disclosure and the following claims. Expressions containing these terms should be understood as not limiting the subject matter described herein, nor limiting the meaning or scope of the following claims. The embodiments of this disclosure as covered herein are defined by the following claims, and not by the content of this invention. The summary of this invention provides a high-level overview of various aspects of this disclosure and introduces some concepts further described in the detailed description below. The summary of this invention is not intended to identify key or essential features of the claimed subject matter; nor is it intended to be used alone to determine the scope of the claimed subject matter. The subject matter should be understood with reference to the corresponding portions, all or any of the accompanying drawings, and each claim of the complete specification of this disclosure.

[0013] One disclosed example is a MEMS mirror assembly including a mirror, a first arm, and a second arm, each arm having a rotational degree of motion, each arm being hinged to opposite ends of the mirror. A first pair of actuators, connected to opposite ends of the first arm, causes the first arm to move with the rotational degree of motion when the first pair of actuators rotates in opposite directions. A second pair of actuators, connected to opposite ends of the second arm, causes the second arm to move with the rotational degree of motion when the second pair of actuators rotates in opposite directions, the mirror rotating about a first axis via the first and second arms.

[0014] In another disclosed embodiment of the example mirror assembly, the first arm has a translational degree of freedom, and the first pair of actuators causes the first arm to translate with the translational degree of freedom when the actuators rotate in the same direction, and the mirror rotates about a second axis via the first arm when one of the first pair of actuators rotates in the same direction. In another disclosed embodiment, the second arm has a translational degree of freedom, and the second pair of actuators causes the second arm to translate with the translational degree of freedom when the pair of actuators rotates in the opposite direction to the first pair of actuators. In another disclosed embodiment, the example assembly includes a circular frame having a rotating beam connected to the mirror, the circular frame being hinged to the first arm and the second arm. In another disclosed embodiment, the mirror is rotatable within the circular frame by resonant motion generated by the oscillating rotation of the first pair of actuators and the second pair of actuators. In another disclosed embodiment, each actuator rotates by applying one of an electrostatic force, an electromagnetic force, or a piezoelectric force. In another disclosed embodiment, each actuator includes a rotor and a stator. In another disclosed embodiment, the rotor includes a plurality of fingers that can be inserted into a plurality of slots in the stator. In another disclosed embodiment, the rotor and stator each include interleaved comb-like structures, wherein the rotor and stator are rotatably connected to each other by a hinged structure. In another disclosed embodiment, the comb-like structures and the hinged structures are made of polysilicon. In another disclosed embodiment, the stator includes four plates, including two lower plates and two upper plates, the lower plates having extending fingers and the upper plates having slot arrays; the rotor includes four plates, including two lower plates and two upper plates, the two lower plates having extending fingers and aligned with the two upper plates of the stator having slot arrays and aligned with the two lower plates of the stator having extending fingers. By supplying power to one lower plate of the stator, the rotor rotates in a first direction; and by supplying power to the other lower plate of the stator, the rotor rotates in a second direction opposite to the first direction. In another disclosed embodiment, the mirror's rotation about the second axis has a greater angular degree of freedom than its rotation about the first axis. In another disclosed embodiment, the hinge connecting the first and second arms to the actuators is made of monocrystalline silicon. In another disclosed embodiment, the example assembly also includes a rectangular frame that provides hinged support for the first pair of actuators and the second pair of actuators. In another disclosed embodiment, the example assembly also includes a torsion bar that connects the first arm to the frame.

[0015] Another disclosed example is a photodetector and ranging system comprising a beam source array having multiple beam sources emitting multiple beams. The system includes a MEMS mirror assembly comprising a mirror, a first arm, and a second arm. Each arm has a rotational degree of motion and is hinged to opposite ends of the mirror. A first pair of actuators is connected to the opposite ends of the first arm. When the first pair of actuators rotates in opposite directions, it moves the first arm by a rotational degree of motion. A second pair of actuators is connected to the opposite ends of the second arm. When the second pair of actuators rotates in opposite directions, it moves the second arm by a rotational degree of motion. The mirror rotates about a first axis via the first and second arms. The mirror intervenes to steer each of the multiple beams toward a target region. A controller is connected to the MEMS mirror assembly to control the first and second pairs of actuators to tilt the mirror about the first axis, thereby steering the multiple beams toward the target region in a raster scan pattern. Sensors detect the return of each of the multiple beams from the target region. The processor reconstructs distance data, which is obtained from each of a plurality of beams in a grating pattern in the target region.

[0016] In another disclosed embodiment of this example photodetector and ranging system, the first arm has a translational degree of freedom. The first pair of actuators, when rotated in the same direction, causes the first arm to translate with a translational degree of freedom. When one of the first pair of actuators rotates in the same direction, the mirror rotates about a second axis via the first arm. In another disclosed embodiment, each actuator rotates by applying one of an electrostatic force, an electromagnetic force, or a piezoelectric force. In another disclosed embodiment, the mirror assembly includes a rectangular frame that provides hinged support for the first pair of actuators and the second pair of actuators. The first pair of actuators and the second pair of actuators are located at opposite ends of the frame, and the mirror is mounted between the first pair of actuators and the second pair of actuators.

[0017] Another disclosed example is a MEMS mirror assembly comprising a mirror, a first arm, and a second arm. Each arm has rotational and translational degrees of freedom. Each arm is hinged to opposite ends of the mirror. A first pair of actuators is connected to the opposite ends of the first arm. When the actuators rotate in the same direction, the first pair of actuators causes the first arm to translate with translational degrees of freedom; when the actuators rotate in opposite directions, the first pair of actuators causes the first arm to move with rotational degrees of freedom. A second pair of actuators is connected to the opposite ends of the second arm. When the actuators rotate in the same direction, the second pair of actuators causes the second arm to translate with translational degrees of freedom; when the actuators rotate in opposite directions, the second pair of actuators causes the second arm to move with rotational degrees of freedom. When the first and second pairs of actuators rotate in the same direction, the mirror rotates about a first axis via the first and second arms. When the first and second pairs of actuators rotate in opposite directions, the mirror rotates about a second axis via the first and second arms. Attached Figure Description

[0018] This disclosure will be better understood from the following description of exemplary embodiments and with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a prior art MEMS scanning mirror; Figure 2A This is a top perspective view of an exemplary MEMS scanning mirror assembly and actuator; Figure 2B yes Figure 2A The top perspective view of the example MEMS scanning mirror assembly, with a cross-sectional view of an actuator; Figure 3A Show Figure 2A The mirror in the component is tilted in one direction; Figure 3B Show Figure 2A Mirror edge in structure Figure 3A The orientation is tilted, whereby the mirror tilts further due to resonance generated by the motion of the actuator; Figure 3C Show Figure 2A The mirror in the structure is tilted in another orientation; Figure 4A This is a perspective view of another example mirror assembly with different types of actuators; Figure 4B When the mirror is tilted on the y-axis, Figure 4A Side view of the example mirror assembly along line 4B–4B'; Figure 4C yes Figure 4A Side view of the example mirror assembly along line 4C–4C'; Figure 5A yes Figure 4A A 3D view of one of the actuators; Figure 5B yes Figure 4A A side view of one of the actuators; Figure 5C yes Figure 5A An exploded perspective view of one of the actuator components; Figure 5D yes Figure 4A A three-dimensional view of the bottom of one of the actuators; Figure 6A This is a three-dimensional diagram of a comb-type actuator used in conjunction with an example mirror component architecture; Figure 6B It is a three-dimensional view of the initial manufacturing of the mirror assembly with comb-shaped actuators; Figure 6C yes Figure 6A A three-dimensional view of the actuator used to tilt the mirror about the x-axis; Figure 7A yes Figure 6A A close-up sectional 3D view of the actuator; Figure 7B yes Figure 6A Another close-up sectional perspective view of the actuator; Figure 8A This is a perspective view of the first example hinge structure that can be incorporated into the example mirror assembly; Figure 8B yes Figure 8A A three-dimensional view of the hinged structure in a rotating state; Figure 8C This is a perspective view of a second example hinge structure that can be incorporated into the example mirror assembly; Figure 8D yes Figure 8C A three-dimensional view of the hinged structure in a rotating state; Figure 9A This is an example application of an example mirror component incorporated into a photodetector and ranging system; Figure 9B yes Figure 9A The field of view of the optical detector and the ranging system; and Figure 9C Showing through Figure 9A The light beam is deflected by the optical detector and the mirror in the ranging system.

[0019] This disclosure is susceptible to various modifications and alternatives. Some representative embodiments have been illustrated by way of example in the accompanying drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the specific forms disclosed. Rather, this disclosure is intended to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of the invention as defined by the appended claims. Detailed Implementation

[0020] This invention can be embodied in many different forms. Representative embodiments are shown in the accompanying drawings and will be described in detail herein. This disclosure is an example or illustration of the principles of this disclosure and is not intended to limit the broad aspects of this disclosure to the illustrated embodiments. Accordingly, elements and limitations disclosed but not expressly set forth in the claims, such as in the abstract, summary, and detailed description, should not be incorporated into the claims individually or collectively by implication, inference, or otherwise. For the purposes of this detailed description, unless expressly stated, the singular includes the plural and vice versa; and the word “comprising” means “unrestrictedly comprising”. Furthermore, approximate terms such as “about,” “almost,” “essentially,” “approximately,” and similar terms may be used herein to mean, for example, “in,” “close to,” or “almost in,” or “within 3–5%,” or “within acceptable manufacturing tolerances,” or any logical combination thereof.

[0021] This disclosure relates to a scanning mirror MEMS design with an optimized gimbal structure, which effectively addresses the cost, durability, scanning angle, beam diameter, and frequency issues that typically plague existing designs. An example scanning mirror assembly includes a frame that supports a central mirror. Each side of the frame has a pair of actuators and side arms located on opposite sides of the mirror. The actuators and side arms cooperate to allow the mirror to tilt about a single axis or two different axes.

[0022] Figure 2A A top perspective view of an exemplary MEMS scanning mirror assembly 100 is shown, which allows a central circular scanning mirror 110 to tilt in either of two axial orientations. The assembly 100 includes a rectangular frame 112 that supports the mirror 110 and other actuator components that allow the mirror 110 to tilt. The assembly 100 includes four actuators 120, 122, 124, and 126 mounted on the frame 112. Actuators 120 and 122 are connected to a side arm 130 at one end of the frame 112. Both side arms 130 and 132 have a rectangular shape. Actuators 124 and 126 are connected to opposite side arms 132 at opposite ends of the frame 112. The mirror 110 is located between actuators 120 and 122 and actuators 124 and 126. As will be explained, actuators 120, 122, 124 and 126, as well as side arms 130 and 132, allow the scanning mirror 110 to tilt in both axial orientations.

[0023] In this example, actuator 120 has a side parallel to frame 112. One side of the rotor plate member of actuator 120 is connected to frame 112 via hinge 134. The opposite side of the rotor plate member of actuator 120 is connected to arm 130 via another hinge 136. The opposite side of side arm 130 is connected to one side of rotor plate member of actuator 122 via hinge 138. The opposite side of actuator 122 is parallel to frame 112. Hinge 140 connects the opposite side of rotor plate member of actuator 122 to frame 112.

[0024] Similarly, in this example, actuator 124 has a side parallel to frame 112. One side of the rotor plate member of actuator 124 is connected to frame 112 via hinge 142. The opposite side of the rotor plate member of actuator 124 is connected to arm 132 via another hinge 144. The opposite side of side arm 132 is connected to one side of rotor plate member of actuator 126 via hinge 148. The opposite side of actuator 126 is parallel to frame 112. Hinge 146 connects the opposite side of rotor plate member of actuator 126 to frame 112. Components such as mirror 110, actuators 120, 122, 124 and 126, and side arms 130 and 132 are fabricated on the substrate forming frame 112. Components are fabricated using semiconductor processes such as epitaxial growth of crystal layers, etching, and photolithography.

[0025] Mirror 110 is supported by a circular mirror frame 150, which rests within an open space 152 defined by frame 112. Mirror 110 is also connected to the arm 154 of frame 150 by a pair of torsion beams 156 and 158. As will be explained, the circular frame 150 supporting mirror 110 can be tilted about the x-axis or y-axis by actuators 120, 122, 124, and 126. Furthermore, torsion beams 156 and 158 allow mirror 110 to rotate relative to circular frame 150 on the axis defined by torsion beams 156 and 158. Torsion beams 156 and 158 allow mirror 110 to be excited at a resonant frequency and to rotate at a larger angle than that could be provided statically by actuators 120, 122, 124, and 126.

[0026] One side of arm 130 is parallel to frame 112. This side of arm 130 is connected to frame 112 via a rotating beam 162. The opposite side of arm 130 is connected to mirror frame 150 via hinge connection 164. One end of rotating beam 162 is connected to frame 112 via hinge 166. The opposite end of rotating beam 162 is connected to side arm 130 via hinge 168.

[0027] Similarly, one side of arm 132 is parallel to frame 112. This side of arm 132 is connected to frame 112 via a rotating beam 172. The opposite side of arm 132 is connected to mirror frame 150 via hinge connection 174. One end of rotating beam 172 is connected to frame 112 via hinge 176. The opposite end of rotating beam 172 is connected to side arm 130 via hinge 178. In this example, rotating beams 162 and 172 allow side arms 130 and 132 to rotate and thus move the rotor plate of one of the connected actuators away from the stator plate. Rotating beams 162 and 172 are optional if a different type of actuator capable of rotating the rotor both toward and away from the stator is used. For such different types of actuators, rotating beams 162 and 172 can be excluded from assembly 100.

[0028] In this example, actuators 120, 122, 124, and 126 can be any suitable MEMS fabrication actuator. Actuators 120, 122, 124, and 126 can be rotated by a suitable power source. Figure 2B This is a perspective view of component 100, with a cross-sectional view of actuator 124. In this example, each actuator 120, 122, 124 and 126 has a rotor plate member 210 having a slot 212 that allows the rotor plate member 210 to rotate relative to a stator plate 220, the stator plate 220 having a series of fingers 222 that are aligned with the slot 212 of the rotor plate member 210.

[0029] In this example, actuators 120, 122, 124, and 126 are electrostatically driven actuators. Therefore, based on the polarity of the electrical signal applied to stator plate member 220, the fingers of rotor plate member can be attracted to the slots, causing rotor plate member 210 to rotate toward stator plate 220. This, in turn, causes arm 132, hinged to the edge of rotor plate member 210 via hinge 144, to rotate about rotation beam 172. Rotor plate member 210 can physically rotate away from stator plate member 220 via hinged connection 144 to side arm 132. Therefore, if side arm 132 is rotated by applying an electrical signal and pressing down on rotor plate 210 relative to actuator 126 via hinge 148, side arm 132 will rotate and pull rotor plate member 210 of actuator 124 away from stator plate member 220.

[0030] Other variations of electrostatic MEMS actuators may be used, as will be described below. It should also be understood that other types of actuators with different actuations can be used. For example, an electromagnetically driven MEMS actuator has a magnet and a coil. Energizing the coil will repel or attract the magnet, thereby moving the actuator. Another example type of MEMS actuator is a piezoelectrically driven actuator comprising a crystalline bending beam. In this type of piezoelectric actuator, an electrical drive signal is applied to one of the bending beams, causing the beam to deform and thus moving the other beam.

[0031] Therefore, the scanning mirror assembly 100 comprises four parts, each serving as an actuator (such as actuators 120, 122, 124, and 126). These actuators have rotor plate members connected on both sides by structures that act as hinges, which are optimized to allow only one rotational degree of freedom. This configuration restricts unwanted motion, focusing on the rotational operation required by the scanning mirror 110.

[0032] Figure 2A The degrees of freedom of mirror 110 in mirror assembly 100 are also shown. Dashed line 180 represents the x-axis and dashed line 182 represents the y-axis relative to mirror assembly 100. Line 184 represents dimension w, dashed line 186 represents dimension w2, and dashed line 188 represents dimension l. The distance between the two hinges 164 and 174, parallel to the y-axis 182, is defined as the length w2 represented by line 186. The distance “l” as shown by line 188 represents the distance between the two hinge points of an actuator (such as actuator 124) (one connected to frame 112, such as hinge 142; and the other connected to a side arm, such as hinge 144 connected to side arm 132). The distance “w” as shown by line 184 represents the distance between the hinge point and the center of rotation about x-axis 180 (hinge 144, which is between side arm 132 and actuator 124). The ratio of “w” to “l” effectively provides motion amplification for mirror 110. Assuming that the mirrored actuator 126 moves in the same and opposite directions as the actuator 124, the arm 132 connected to the actuator 124 pivots at a ratio close to l / w as the rotor plate component of the actuator (such as actuator 124) rotates.

[0033] Furthermore, arm 132 has a width of 2 × “w” and rotates about the center of mirror 110 along the x-axis 180. In a mirror arrangement about the y-axis 182 located at the center of mirror 110, two actuators 124 and 126, together with arm 132, are on one side of y-axis 182, and two other actuators 120 and 122 are on the other side of y-axis 182. Arm 132 includes hinges 174, 176, and 178 that rotate parallel to y-axis 182. Similarly, hinges 164, 166, and 168 also rotate parallel to y-axis 182. Side arms 130 and 132 each have rotational degrees of motion and translational degrees of freedom.

[0034] By manipulating these actuators 120, 122, 124, and 126, for example, if the rotor plate members of actuators 120 and 122 rotate in the same direction, such as upward, and the rotor plate members of actuators 124 and 126 rotate by an equal amount in the same direction, such as downward, arm 130 will translate upward and arm 132 will translate downward in the corresponding translational degrees of freedom. This results in mirror 110 rotating about the y-axis 182 with mirror frame 150 when hinges 164, 166, 168, 174, 176, and 178 rotate. These hinges 164, 166, 168, 174, 176, and 178 extend slightly during this movement. In the case of the simple electrostatic actuator in this example, only one set of actuators 120 and 122 or 124 and 126 moves downward by an electrical signal, thus limiting the degree of tilt of the mirror. If other types of actuators are used that allow the rotor plate to move both away from and toward the stator, a greater degree of tilting around the y-axis 182 can be achieved.

[0035] Hinged connections 134, 140, 142, and 146 from frame 112 to the respective actuators 120, 122, 124, and 126 each act as a pivot point for each of the respective actuators 120, 122, 124, and 126. A virtual pivot point exists along the x-axis 180. This virtual pivot point can be defined by optional rotation beams 162 and 172 included in example assembly 100. In assemblies without rotation beams 162 and 172, the pivot point is virtual because it is not physically defined. The motion amplification of mirror assembly 100 is set by a ratio of l / w for x-axis 180 and approximately l / w² for y-axis 182. The rotor plate components of actuators 120, 122, 124, and 126 are hinged such that: when the rotor plate components of actuators 120 and 126 move in the same and opposite directions as the rotor plate components of actuators 122 and 124, arms 130 and 132 rotate significantly along the x-axis 160; and when the rotor plate components of actuators 120 and 122 move in the same and opposite directions as the rotor plate components of actuators 124 and 126, arms 130 and 132 rotate less significantly along the y-axis 182. This is due to the length difference between dimensions “w” and “w2”.

[0036] The length difference can be used in two ways: 1) manipulating mirror 110 to rotate in a resonant mode along the y-axis 182 and allowing mirror 110 to extend beyond its stationary state defined by mirror frame 150; and 2) manipulating mirror 110 to rotate in a stationary state along the y-axis 182 by moving mirror frame 150 individually and stopping movement of rotating beams 156 and 158. The resonant mode allows mirror 110 to rotate relative to mirror frame 150 and can be activated in the opposite direction by successively moving the rotor plate members of actuators 120, 122, 124, and 126 to oscillate mirror frame 150, causing mirror 110 to rotate about rotating beams 156 and 158. The resonant mode can be controlled by selecting a resonant frequency for actuators with a desired Q factor to amplify the degree of movement of mirror 110 relative to frame 150.

[0037] One side of the rotor plate assembly of each actuator 120, 122, 124, and 126 is connected to frame 112, and the other side of the rotor plate assembly is connected to an arm (such as arm 132 with a width of twice the "w"). This arm is a hinged member connected to a mirror or a support mirror via a universal joint. When actuators 120, 122, 124, and 126 are in operation, they enable rotation from mirror frame 150 to cause the edge of the rotor plate assembly to move up and down. The rotor plate assembly of the other actuator on the opposite side also moves up and down, thus mirroring this movement about the axis of rotation. The operation of two actuators (such as actuators 120 and 122) with a 180-degree phase difference causes arm 130 to rotate about an axis parallel to x-axis 180.

[0038] A key advantage of the example mirror assembly 100 is its ability to independently tilt mirror 110 about the x and y axes by precisely controlling the angles of the rotor plate components of the four actuators 120, 122, 124, and 126, while keeping the center of mass of mirror 110 coincident with the center of rotation. This arrangement addresses vibration issues, shock breakage risks, and image stability problems associated with conventional scanning mirror designs. Mirror assembly 100 thus provides a highly improved, robust, and efficient solution for optical applications.

[0039] Figure 3A The image shows that by tilting actuators 124 and 126 downwards and optionally tilting actuators 120 and 122 upwards, mirror 110 is tilted relative to frame 150 along the y-axis 182. When using electrostatic actuators that only allow electrical signals to rotate the rotor plate assembly toward the stator plate, actuators 120 and 122 remain in a neutral position. If actuators 120 and 122 are of the type that would allow upward rotation of the rotor assembly, actuators 120 and 122 will... Figure 3A As shown, it slopes upwards.

[0040] Figure 3BThe mirror 110 is shown tilted relative to the frame 150 in resonant mode. In this example, the frame 150 is tilted about the y-axis 182 by tilting the rotor plate members of actuators 124 and 126 downwards while optionally tilting the rotor plate members of actuators 120 and 122 upwards. This causes the side arms 130 and 132 to translate along the z-axis, while the hinges 164 and 174 rotate, thus rotating the frame 150 about the x-axis 180. By tilting the rotor plate members of actuators 120 and 122 downwards and optionally tilting the rotor plate members of actuators 124 and 126 upwards, the frame 150 can rotate in the opposite direction about the y-axis 182. Through the resonant motion generated by the frame 150, the mirror 110 is further tilted relative to the frame 150 by the rotating beams 156 and 158. The mirror 110 can be tilted in this manner during resonant mode operation, as... Figure 3B As shown.

[0041] Figure 3C The diagram illustrates the rotation of mirror 110 about x-axis 180 when the rotor plate members of actuators 120 and 126 are tilted upwards and the rotor plate members of actuators 122 and 124 are tilted downwards. In this example, the electricity applied to actuators 122 and 124 causes the corresponding rotor plate members to move toward the stator plate members. This causes the corresponding arms 130 and 132 to rotate, thus pushing the rotor plate members of the corresponding actuators 120 and 126 upwards. Therefore, the first pair of actuators 120 and 122 rotate in opposite directions. The second pair of actuators 124 and 126 also rotate in opposite directions. This causes the side arms 130 and 132 to rotate both in x-axis 180 with their respective rotational degrees of freedom and thus rotate mirror 110 about x-axis 180. By applying electricity to tilt the rotor plate members of actuators 120 and 126 downwards, mirror 110 can rotate in opposite directions about x-axis 180. These rotating arms 130 and 132 cause the rotor plate components of the corresponding actuators 122 and 124 to tilt upwards. Of course, if the actuators 120, 122, 124 and 126 are of the type that allow the application of an electrical signal to cause the rotor to rotate relative to the stator, either upwards or downwards, electricity can be applied to all actuators 120, 122, 124 and 126 to tilt mirror 110.

[0042] Figure 4A A perspective view of a mirror assembly 400 operating similarly to assembly 100 in Figure 2 is shown. Figure 4B Show Figure 4A A cross-sectional view of mirror assembly 400 along line 4B–4B' shows mirror 410 tilted on the y-axis. Figure 4CA cross-sectional view along line 4C–4C' is shown on the actuators on the mirror assembly 400. The mirror assembly 400 allows tilting of the central circular scanning mirror 410. The assembly 400 includes a rectangular frame 412 that supports the mirror 410, the actuators, and the arm. The assembly 400 includes four actuators 420, 422, 424, and 426. Actuators 420 and 422 are connected to the side arm 430 via corresponding hinges on the sides of the arm 430. Actuators 424 and 426 are connected to the opposite side arm 432 via corresponding hinges on the sides of the arm 432.

[0043] One side of arm 430 is parallel to frame 412. The opposite side of arm 430 is hinged to circular mirror frame 454. Similarly, one side of arm 432 is parallel to frame 412. The opposite side of arm 432 is hinged to mirror frame 454. Mirror 410 is supported by circular frame 454, which is supported within an open space 456 defined by frame 412. Mirror 410 is also connected to arm 458 of frame 454 by a pair of rotating beams 450 and 452.

[0044] Similar to Figure 2A The intermediate mirror assembly 100, actuators 420, 422, 424, and 426, are tiltable to move arms 430 and 432 to tilt mirror 410 in either the y-axis or x-axis. In this example, actuators 420, 422, 424, and 426 consist of interlocked rotors and stators supported by corresponding base structures 440, 442, 444, and 446. As will be explained below, both the rotor and stator have two lower finger plates that are interleaved with two corresponding upper slot plates. Each base structure 440, 442, 444, and 446 is connected to one of the corners of frame 412. Figure 4B This is a side view of assembly 400, showing actuator 420 tilted upwards and actuator 422 tilted downwards to tilt arm 430 and thus rotate mirror 410 and frame 454 along the y-axis. As explained above, actuators 424 and 426 similarly tilt to tilt arm 432 on the other side of assembly 400. Figure 2A In contrast to the intermediate actuators, the rotors of actuators 420, 422, 424 and 426 can be powered to rotate either toward or away from the stator.

[0045] Similar to Figure 2A In the mirror assembly 100, the upward tilting actuators 420 and 422 cause the arm 430 to move one end of the frame 454 upward, allowing the mirror 410 and the frame 454 to rotate along the y-axis. Simultaneously, the downward tilting actuators 424 and 426 cause the arm 432 to move the opposite end of the frame 454 downward.

[0046] Figure 5A It is an actuator (e.g.) Figure 4AA three-dimensional view of the actuator 420 in the image. Figure 5B yes Figure 4A Side view of actuator 420. Figure 5C This is an exploded perspective view of actuator 420. Figure 5D This is a bottom perspective view of actuator 420. The actuator in this example is balanced and includes a symmetrical rotor and stator structure.

[0047] The actuator 420 has a rotor 510 and a stator 512. The rotor 510 includes two lower square plates 520 and 522, each having an array of extending fingers 524. The rotor 510 also includes two upper square plates 530 and 532, each having an array of slots 534. The square plates 530 and 532 are arranged with the square plates 520 and 522 to form a grid arrangement. The plates 530 and 532 with slots 534 are positioned higher than the plates 520 and 522 with fingers 524. The rotor 510 is connected to two base pads 540 and 542 at the ends of corresponding rotating beams 544 and 546. The rotor 510 thus rotates about an axis between the two base pads 540 and 542. In this example, the actuator 420 does not have a side that rotates on the hinge connected to the frame, but instead supports the base pads 540 and 542 via the base structure 440 connected to the frame 412.

[0048] The stator 512 has two upper square plates 550 and 552, each having an array of slots 554 connected to the base structure 440. The stator 512 also includes two lower square plates 560 and 562, each having an array of extending fingers 564 connected to the base structure 440. The upper and lower square plates 550 and 552 are arranged in a grid pattern with the lower plates 560 and 562. The lower plates 560 and 562 are at the same height level as the lower plates 520 and 522 of the rotor 510. Conversely, the upper plates 550 and 552 are at a higher height level than the upper plates 530 and 532 of the rotor 510.

[0049] Therefore, the upper plates 530 and 532 of the rotor 510 are positioned above the lower plates 560 and 562 of the stator 512, respectively. In this arrangement, the extended fingers 564 of the lower plates 560 and 562 of the stator 512 are aligned with the slots 534 of the upper plates 530 and 532 of the rotor 510. Similarly, the upper plates 550 and 552 of the stator 512 are positioned above the lower plates 520 and 522 of the rotor 510. The extended fingers 524 of the lower plates 520 and 522 of the rotor 510 are aligned with the slots 554 of the upper square plates 550 and 552 of the stator 512.

[0050] Figure 5D A bottom perspective view of actuator 420 is shown, which has a base structure 440 supporting stator 512. Two gap regions 570 and 572 are formed in the base 420 below lower plates 520 and 522, respectively. Gap regions 570 and 572 allow plates 520 and 522 of rotor 510 to rotate into gap regions 570 and 572.

[0051] like Figure 5B As shown, the fingers and slots of the upper and lower plates of rotor 510 form capacitors with the fingers and slots of the upper and lower plates of stator 512. By applying an attractive force that draws the fingers 524 of lower plate 520 to the slots 554 of plate 550, rotor 510 can rotate along the axis formed by base pads 540 and 542. An attractive force can be generated by applying an electrical signal to upper plate 550. Similarly, by applying an electrical signal to lower plate 560, an attractive force draws the slots 534 of upper plate 530 to the fingers 564 of lower plate 560. By applying an attractive force to the fingers 524 of lower plate 522, rotor 510 can rotate in the opposite direction to move toward the slots 554 of upper plate 552. An attractive force can be generated by applying an electrical signal to upper plate 552. By applying an electrical signal to the lower plate 562, an attractive force is also applied to attract the groove 534 of the upper plate 532 toward the finger 564 of the lower plate 562.

[0052] When the fingers 524 of the lower plate 520 move away from the slot of the upper plate 550, the plate 520 rotates into the gap region 570. Simultaneously, the fingers 524 of the lower plate 522 rotate into the slot of the upper plate 552. When the actuator 420 rotates in the opposite direction, the fingers 524 of the lower plate 520 are attracted to the slot 554 of the upper plate 550. Simultaneously, the fingers 524 of the lower plate 522 move away from the slot of the upper plate 552. When the fingers 524 of the lower plate 522 move away from the slot of the upper plate 552, the plate 522 rotates into the gap region 572.

[0053] Actuator 420 is a balancing actuator that maintains the balance of all x-axis forces and generates a net zero x-force while providing a z-force that causes rotor 510 to rotate about a central axis defined by base pads 540 and 542. Since the plates of rotor 510 and stator 512 are symmetrical, their respective forces remain balanced and generate a net zero x-force when rotor 510 rotates in opposite directions.

[0054] Figure 6A Showing something similar to Figure 2AAnother example of a MEMS mirror assembly 600 is the mirror assembly 100, which uses different types of actuators to rotate the mirror 610 about the x-axis. Assembly 600 includes a rectangular frame 612 that supports the mirror 610, actuators, and side arms in an arrangement similar to that of assembly 100. Therefore, assembly 600 includes four actuators and two side arms, which allow the mirror 610 to tilt about the x-axis. Figure 6A Half of component 600 shown has actuators 620 and 622. Actuators 620 and 622 control the tilting of the side arm 630 connected to mirror 610. Similar to mirror assembly 100, another set of actuators is connected to the opposite side arm (not shown in the diagram). Figure 6A middle).

[0055] One side of the side arm 630 is parallel to the frame 612. The opposite side of the side arm 630 is connected to the mirror 610. The frame 612 includes an anchoring member 632, which is raised and locked in place by contact with latches 634 and 636 positioned below the anchoring member 632. Each of the latches 634 and 636 is connected to the frame 612 by a tether 638. The latches 634 and 636 can be moved to raise the anchoring member 632 to... Figure 6A The location shown.

[0056] In this example, actuators 620 and 622 are comb-type actuators, which can be manufactured using processes that allow for precisely defined features. Each actuator 620 and 622 includes a lower stator 640 and an upper rotor 642. The stator 640 has a series of fine combs 644 adjacent to corresponding combs 646 of the upper rotor 642. The lower stator 640 is connected to the upper rotor 642 via a hinge member 648, which allows the upper rotor 642 to rotate relative to the lower stator 640.

[0057] Figure 7A This is a close-up perspective view of the stator 640 and rotor 642 of the example actuator 622. Figure 7B This is a close-up cross-sectional perspective view of the comb-like structures of the stator 640 and rotor 642 of actuator 622. Electrostatics are applied to the comb-like structures 644 of the stator 640, causing the rotor 642 to rotate about the hinge 648. This creates an attractive force on the comb-like structures 646 of the rotor 642, causing the rotor 642 to rotate into the stator 640.

[0058] Return to Figure 6A The side arm 630 is connected to the anchoring member 632 via a rotating beam 650. The opposite end of the side arm 630 is connected to the mirror 610. The side arm 630 includes a hinge member 652 connected to the actuator 620 and a hinge member 654 connected to the actuator 622.

[0059] Figure 6A The mirror assembly 600 is shown in an offset deployment state. The offset deployment state lifts the mirror 610, side arm 630, and rotating beam 650 from the frame 612 by the thickness of the frame 612, which in this example has a nominal thickness of 100 μm. Hinges 652 and 654 are angled between the actuators 620 and 622 and the side arm 630 to allow offset. Similarly, the corresponding rotor 642 is angled relative to the stator 640 and the hinged member 648 at equal but opposite angles.

[0060] In this example, stator 640 and rotor 642 are fabricated using a polysilicon trench-filling and oxide etching process to form relatively fine features of the combs 644 and 646 of the respective stator 640 and rotor 642. Hinged member 648 is fabricated from the same polysilicon layer as the trench filler. Hinged members 652 and 654 are fabricated from a single-crystal material during the fabrication process.

[0061] like Figure 6B As shown, after initial fabrication, actuators 620 and 622, mirror 610, side arm 630, anchoring member 632, and latches 634 and 636 are positioned at the same plane and height as frame 612. The various components are fabricated from a single substrate, and through etching, deposited polycrystalline silicon and single-crystal materials.

[0062] Latches 634 and 636 are connected to tether 638. After the initial manufacturing of the components from frame 612, latches 634 and 636, they can be positioned using a positioning tool located below mirror 610. Figure 6B Moving these components to the indicated positions, the positioning tool lifts mirror 610 and thus lifts the connected side arm 630, beam 650, and anchor member 632. This allows the use of a second positioning tool to move latches 634 and 636 together, and thus swing latches 634 and 636 below anchor member 632. These tools move anchor member 632 upward and hold the latches in place. Figure 6A The upward position is shown. Each tether 638 has a ratchet surface 670 that interacts with a corresponding ratchet surface 672 etched into the frame 612. Therefore, the tether 638 and the attached latches 634 and 636 can move toward each other; however, the interaction between the ratchet surfaces 670 and 672 prevents the tether 638 from moving in opposite directions. When the latches 634 and 636 are in the upward position... Figure 6A When they reach the final position shown, they are held in place by interlocking ratchet surfaces 670 and 672.

[0063] When the anchoring member 632 is lifted via latches 634 and 636, the anchoring member 632 also raises the side arm 630 and the attached mirror 610 via beam 650. The raising of the side arm 630 causes the rotors 642 of actuators 620 and 622 to rotate angularly about hinge 648. Adhesive or other suitable connecting mechanisms are used to hold the anchoring member 632 in place relative to latches 634 and 636. Thus, the anchoring member is positioned vertically offset and unaffected by impacts or vibrations on frame 612. The same anchor, actuator, latch, and beam on the other side of mirror 610 are operated in a similar manner to raise mirror 610.

[0064] Similar to the previous mirror assembly, actuators 620 and 622 can be tilted in opposite rotational motions to move side arm 630, combined with two identical actuators and side arms (not shown) on the other side of the assembly to tilt mirror 610 along the x-axis.

[0065] Figure 6C The diagram illustrates how the rotor 642 of actuator 620 moves toward the stator 640 of actuator 620 to induce a tilt angle of mirror 610 along the x-axis. Correspondingly, the rotor 642 of actuator 622 moves away from the stator 640 of actuator 622. The movement of the rotors 642 of actuators 620 and 622 causes a torsion of the rotating beam 650 via the side arm 630. Actuators 620 and 622 thus move the side arm 630 via hinged structures 652 and 654. Hinges 652 and 654 both twist to allow the movement of the side arm 630. Similar to the operation of the components in Figure 2, the other two actuators and side arms on opposite sides of mirror 610 move similarly.

[0066] To tilt mirror 610 at another angle along the x-axis, the rotor 642 of actuator 622 moves away from the stator 640 of actuator 620, while simultaneously moving towards the stator 640 of actuator 622. This causes the rotating beam 650 to move along the x-axis from the stator 640 of actuator 622. Figure 6C The example twists in the opposite direction. The actuator and side arm on the other side of mirror 610 are actuated in a similar manner.

[0067] By keeping the center of the mirror at the center of rotation, the example mirror assembly allows for the deployment of relatively large mirrors without imbalance. The larger mirror supported by the example mirror assembly allows for a larger beam diameter in the light detector and ranging (LiDAR) system, which allows the beam to diverge at a smaller angle.

[0068] Figure 8A Such as in Figure 2A A perspective view of a first example hinge connector 800 that connects actuators 120 and 122 to hinge connectors 134 and 136 of side arm 130. Figure 8BThis is a perspective view of a rotating hinged connector 800. The hinged connector 800 includes a transverse member 810 with connecting members 812 and 814 at opposite ends. A center member 820 is formed at the center of the transverse member 810, on the side opposite to the connecting members 812 and 814. The hinged connector 800 thus has a rotational component defined by the transverse member 810 acting as a torsion beam, and a horizontal component defined by the transverse member 810 acting as a transverse beam. Figure 8B The lateral member 810 shown is therefore flexible. This is important because the connector 800 needs to allow some movement in the horizontal direction.

[0069] Figure 8C This is a perspective view of a second example hinged connector 850 that can be incorporated into a mirror assembly (e.g., mirror assembly 100 or 600). The hinged connector 850 includes a center plate 860, preferably made of polysilicon. The center plate 860 has a hole 862 formed therethrough, which allows flexibility and provides an etched hole for removing an oxide layer from beneath the polysilicon during manufacturing. The center plate 860 has two lateral members 864 and 866 extending laterally from opposite edges. A silicon dioxide layer 868 is provided between the plate 860 and the lateral members 864 and 866. The silicon dioxide layer 868 forms a connection between the lower monocrystalline silicon of the lateral members 864 and 866 and the upper polycrystalline silicon of the center plate 860. In this example, the polysilicon layer 860 is approximately 2.5 μm thick and the silicon dioxide layer 868 is approximately 2 μm thick. The monocrystalline silicon lateral members 864 and 866 are 500 μm thick. Therefore, the hinge connector 850 is very rigid in the horizontal direction and has only slightly reduced rigidity in the vertical direction. Figure 8D The rotation of transverse members 864 and 866 about a hinge is shown, the hinge being defined by a perforated area of ​​a center plate 860.

[0070] Figure 8A – Figure 8B The first example hinge 800 is made solely of monocrystalline silicon and etched in the same manner as the rotating beam, so the hinge in the example mirror assembly can be fabricated with other monocrystalline silicon structures. Unlike conventional hinges that have only one degree of freedom and are rigid in the other five, the example hinge 800 is rigid in four of the six degrees of freedom. Because the tilt actuators of the example assembly separate from each other during rotation, the example hinge 800 allows this separation, as without it the hinge would be unable to move due to insufficient degrees of freedom.

[0071] Figure 8C – Figure 8DThe second example hinge 850 is formed using, for example, the polysilicon deposition process used in component 600 and can be manufactured with other parts of component 600. Hinge 850 also has two degrees of freedom and four degrees of rigidity. The example hinge 850 is particularly rigid in the lateral direction, which helps to prevent the actuator fingers from moving in the lateral direction and allows them to move only in the vertical direction when they rotate.

[0072] Figure 9A An example forward-looking light detector and ranging (LiDAR) system 900 is shown, mounted on a vehicle 910, and can be used in applications such as autonomous driving on highways and in cities. The light detector and ranging system 900 projects light with a field of view (FOV) onto a target area 922, shown by dashed lines 920. In this example, for the example light detector and ranging system 900, the horizontal field of view (FOV) varies from 60 to 120 degrees and the vertical field of view varies from 20 to 30 degrees. In this example, for the example light detector and ranging system 900, the nominal range is 200 meters. In this example, various light sources emit light beams, which are reflected from mirrors (e.g., mirrors in the example mirror assembly). Due to the mirrors, the light beams can be reflected to the target at different angles. The light beams reflected back from the target are detected by a detector capable of timing the time-of-flight of the light pulses. The light detector and ranging system 900 includes a processor 912 that determines the time taken for the light beam to propagate and return from the target to determine the distance to the target, and combines it with the angle data of the mirror to create a 3D point cloud for target recognition.

[0073] At a distance of 200m, the round-trip flight time of the beam between system 900 and the target area is 1.3 microseconds (usec). This means that for each beam, the photodetector and ranging system 900 can have 0.75 megapixels / second. The beam transmitter must wait until the previous pulse returns before sending another pulse. Even faster, each beam will generate multiple pulses with the possibility of mutual interference, as objects at close range can appear and arrive at the receiver before the previous pulse. Assuming a frame rate of 20 frames / second, the maximum number of pixels per laser per frame is 37,500 pixels per frame per laser. A typical requirement for a forward-looking photodetector and ranging system is 0.1 degree resolution. If the field of view is 120x20 degrees with 0.1 degree resolution, there are 240,000 pixels per frame. Given that the maximum number of pixels per laser per frame is 37,500 due to the time-of-flight limitation, at least 7 lasers or beams must be used to cover the field of view at this resolution.

[0074] The typical grating scan excitation of the field of view of the photodetector and ranging system 900 has a horizontal scan as one scan, followed by a step along the vertical position, and then repeats the return horizontal scan across the field of view. An additional beam allows multiple horizontal scans to be performed simultaneously. Figure 9B Showing the image Figure 9A The target area 922 is a raster scan pattern. In this example, the target area 922 is divided into a series of horizontal scan areas 930 and a series of vertical positions 932. The beam emitter 950 emits a series of beams in raster pattern between the horizontal scan areas 930 at the vertical positions 932.

[0075] Figure 9C A scan of some of the seven beams from example system 900 is shown. In this example, four beams 942, 944, 946, and 948 are generated from beam source array 950 having beam sources 952, 954, 956, and 958. Beams 942, 944, 946, and 948 are directed toward mirror 960, which can deflect beams 942, 944, 946, and 948 to different horizontal regions 962. Mirror 960 is tilted at different angles by activating actuators of mirror assembly 962 (similar to those discussed above). Controller 970 activates the actuators of mirror assembly 962 to tilt mirror 960 to guide each beam array at different angles. Controller 970 thus controls the actuators to tilt the mirror to guide beams 942, 944, 946, and 948 across the field of view in a raster pattern.

[0076] The required vertical angular movement of mirror 960 depends on the number of light beams reflected through mirror 960. Since the number of light beams in the photodetector and ranging system 900 is determined by the speed of light and pixel requirements, the mirror can be designed such that the required vertical angular movement is less than the required horizontal angular movement. As explained above, the example components can therefore be oriented such that the mirror has a longer angular movement along the x-axis to satisfy the horizontal angular movement requirement, while the y-axis can satisfy a shorter vertical angular movement requirement.

[0077] A resonant sinusoidal scan with vertical stepping can be used. However, the pixel density decreases at the center of the field of view, which is undesirable. Conversely, a triangular waveform produces a uniform pixel density covering the field of view. In this case, it is advantageous to move the mirror along both axes in a quasi-static manner and abandon the resonant mode. This can be achieved by using a low-angle movement axis as the vertical scan and a large-angle movement axis as the horizontal scan.

[0078] While the disclosed embodiments have been illustrated and described with respect to one or more implementations, equivalent variations and modifications will be conceived or known by those skilled in the art upon reading and understanding this specification and the accompanying drawings. Furthermore, although a particular feature of the invention may have been disclosed with respect to only one of a few implementations, such feature, if desired and advantageous for a given or particular application, may be combined with one or more other features of other implementations.

[0079] As used herein, the terms “component,” “module,” “system,” etc., generally refer to a computer-related entity, or hardware (e.g., circuitry), a combination of hardware and software, software, or an entity associated with an operating device having one or more specific functions. For example, a component can be, but is not limited to, a process running on a processor (e.g., a digital signal processor), a processor, an object, an executable program, an execution thread, a program, and / or a computer. As illustrated, an application running on a controller and the controller itself can both be components. One or more components may reside in a process and / or an execution thread, and components may be located on a single computer and / or distributed among two or more computers. Furthermore, a “device” can take the form of specially designed hardware, general-purpose hardware specialized by executing software thereon to enable the hardware to perform specific functions, software stored on a computer-readable medium, or a combination of the above.

[0080] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, wherever “comprising,” “including,” “having,” “with,” or variations thereof are used in the detailed description and / or claims, they are intended to indicate an open meaning in a manner similar to the term “comprising.”

[0081] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. Furthermore, terms such as those defined in general dictionaries shall be interpreted as having the same meaning as in the relevant technical context, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0082] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limiting descriptions. While the invention has been illustrated and described with respect to one or more embodiments, those skilled in the art will conceive of or become aware of equivalent changes and modifications upon reading and understanding this specification and the accompanying drawings. Furthermore, although a particular feature of the invention may have been disclosed only with respect to one of several embodiments, that feature may still be combined with one or more other features in other embodiments, depending on the needs and advantages of any given or specific application. Therefore, the breadth and scope of the invention should not be limited to any of the embodiments described above. Rather, the scope of the invention should be defined by the following claims and their equivalents.

Claims

1. A MEMS mirror assembly, comprising: mirror; The first arm and the second arm each have a degree of rotational motion, and each arm is hinged to the opposite ends of the mirror; The first pair of actuators is connected to opposite ends of the first arm. When the first pair of actuators rotates in opposite directions, the first pair of actuators causes the first arm to move with the rotational motion. as well as The second pair of actuators is connected to the opposite ends of the second arm. When the second pair of actuators rotates in opposite directions, the second pair of actuators causes the second arm to move with the rotational motion, wherein the mirror rotates about a first axis via the first arm and the second arm.

2. The mirror assembly according to claim 1, wherein, The first arm has translational degrees of freedom, and wherein, when the first pair of actuators rotate in the same direction, the first pair of actuators causes the first arm to translate with the translational degrees of freedom, and wherein, when the first pair of actuators rotate in the same direction, the mirror rotates about a second axis via the first arm.

3. The mirror assembly according to claim 2, wherein, The second arm has translational degrees of freedom, and wherein, when the second pair of actuators rotates in the opposite direction to the first pair of actuators, the second pair of actuators causes the second arm to translate with the translational degrees of freedom.

4. The mirror assembly of claim 3, further comprising a circular frame having a rotating beam connected to the mirror, the circular frame being hinged to the first arm and the second arm.

5. The mirror assembly according to claim 4, wherein, The mirror is rotatable within the circular frame by resonant motion, which is generated by the oscillating rotation of the first pair of actuators and the second pair of actuators.

6. The mirror assembly according to any one of claims 1–5, wherein, Each of the actuators rotates by applying one of electrostatic force, electromagnetic force, or piezoelectric force.

7. The mirror assembly according to any one of claims 1–6, wherein, Each of the actuators includes a rotor and a stator.

8. The mirror assembly according to claim 7, wherein, The rotor includes a plurality of finger-like elements that can be inserted into a plurality of slots in the stator.

9. The mirror assembly according to claim 7, wherein, The rotor and stator each include comb-like structures that are interlaced with each other, and wherein the rotor and stator are rotatably connected to each other via a hinged structure.

10. The mirror assembly according to claim 7, wherein, The comb-like structure and the hinge structure are made of polycrystalline silicon.

11. The mirror assembly according to claim 7, wherein, The stator includes four plates, two lower plates and two upper plates, the lower plates having extended fingers and the upper plates having slot arrays. The rotor includes four plates, two lower plates and two upper plates, the two lower plates having extended fingers and aligned with the two upper plates of the stator having the slot arrays, and the two upper plates having slot arrays and aligned with the two lower plates of the stator having extended fingers. The rotor rotates in a first direction by supplying power to one lower plate of the stator, and rotates in a second direction opposite to the first direction by supplying power to the other lower plate of the stator.

12. The mirror assembly according to any one of claims 2–11, wherein, The mirror has a greater degree of angular freedom in its rotation about the second axis than it has in its rotation about the first axis.

13. The mirror assembly according to any one of claims 1–12, wherein, The hinge connecting the first and second arms to the actuator is made of monocrystalline silicon.

14. The mirror assembly according to any one of claims 1–13, the mirror assembly further comprising a rectangular frame providing hinged support for the first pair of actuators and the second pair of actuators.

15. The mirror assembly of claim 13, further comprising a torsion bar connecting the first arm to the frame.

16. A photodetector and ranging system, comprising: A beam source array having multiple beam sources that emit multiple beams; MEMS mirror assembly includes: mirror; The first arm and the second arm each have a degree of rotational motion, and each arm is hinged to the opposite ends of the mirror; A first pair of actuators, connected to opposite ends of the first arm, causes the first arm to move with the stated rotational motion when the first pair of actuators rotates in opposite directions; and The second pair of actuators, connected to opposite ends of the second arm, causes the second arm to move with the rotational motion when the second pair of actuators rotates in opposite directions, wherein the mirror rotates about a first axis via the first and second arms, and wherein the mirror intervenes to steer each of the plurality of beams toward the target region. A controller, connected to the MEMS mirror assembly, controls the first pair of actuators and the second pair of actuators to tilt the mirror about the first axis so that the plurality of beams are directed toward the target region in a grating scan pattern; Sensors, the sensors being used to detect the return of each of the plurality of beams from the target region; and A processor for reconstructing distance data obtained from each of the plurality of light beams in a grating pattern in the target region.

17. The photodetector and ranging system according to claim 16, wherein, The first arm has translational degrees of freedom, and wherein, when the first pair of actuators rotate in the same direction, the first pair of actuators causes the first arm to translate with the translational degrees of freedom, and wherein, when the first pair of actuators rotate in the same direction, the mirror rotates about a second axis via the first arm.

18. The photodetector and ranging system according to any one of claims 16-17, wherein, Each of the actuators rotates by applying one of electrostatic force, electromagnetic force, or piezoelectric force.

19. The photodetector and ranging system according to any one of claims 16–18, wherein, The mirror assembly includes a rectangular frame that provides hinged support for the first pair of actuators and the second pair of actuators, wherein the first pair of actuators and the second pair of actuators are located at opposite ends of the frame, and the mirror is mounted between the first pair of actuators and the second pair of actuators.

20. A MEMS mirror assembly, comprising: mirror; The first arm and the second arm each have rotational motion and translational degrees of freedom, and each arm is hinged to the opposite ends of the mirror; The first pair of actuators is connected to opposite ends of the first arm. When the first pair of actuators rotates in the same direction, the first pair of actuators causes the first arm to move with the translational degree of freedom, and when the first pair of actuators rotates in opposite directions, the first pair of actuators causes the first arm to rotate with the rotational degree of freedom. as well as A second pair of actuators, connected to opposite ends of the second arm, causes the second arm to move with the translational degree of freedom when the second pair of actuators rotates in the same direction, and causes the second arm to rotate with the rotational degree of freedom when the second pair of actuators rotates in opposite directions, wherein the mirror rotates about a first axis via the first and second arms when the first and second pairs of actuators rotate in the same direction, and wherein the mirror rotates about a second axis via the first and second arms when the first and second pairs of actuators rotate in opposite directions.

21. The mirror assembly of claim 20, further comprising a circular frame having a rotating beam connected to the mirror, the circular frame being hinged to the first arm and the second arm.

22. The mirror assembly according to claim 21, wherein, The mirror is rotatable within the circular frame by resonant motion, which is generated by the oscillating rotation of the first pair of actuators and the second pair of actuators.

23. The mirror assembly according to any one of claims 20–22, wherein, Each of the actuators rotates by applying one of electrostatic force, electromagnetic force, or piezoelectric force.

24. The mirror assembly according to any one of claims 20–23, wherein, Each of the actuators includes a rotor and a stator.

25. The mirror assembly of claim 24, wherein, The rotor includes a plurality of finger-like elements that can be inserted into a plurality of slots in the stator.

26. The mirror assembly of claim 24, wherein, The rotor and stator each include comb-like structures that are interlaced with each other, and wherein the rotor and stator are rotatably connected to each other via a hinged structure.

27. The mirror assembly of claim 24, wherein, The comb-like structure and the hinge structure are made of polycrystalline silicon.

28. The mirror assembly of claim 24, wherein, The stator includes four plates, two lower plates and two upper plates, the lower plates having extended fingers and the upper plates having slot arrays. The rotor includes four plates, two lower plates and two upper plates, the two lower plates having extended fingers and aligned with the two upper plates of the stator having slot arrays, and the two upper plates having slot arrays and aligned with the two lower plates of the stator having extended fingers. The rotor rotates in a first direction by supplying power to one of the lower plates of the stator, and rotates in a second direction opposite to the first direction by supplying power to the other lower plate of the stator.

29. The mirror assembly according to any one of claims 20–28, wherein, The mirror has a greater degree of angular freedom in its rotation about the second axis than it has in its rotation about the first axis.

30. The mirror assembly according to any one of claims 20–29, wherein, The hinge connecting the first and second arms to the actuator is made of monocrystalline silicon.

31. The mirror assembly according to any one of claims 20–30, the mirror assembly further comprising a rectangular frame providing hinged support for the first pair of actuators and the second pair of actuators.

32. The mirror assembly of claim 30, further comprising a torsion bar connecting the first arm to the frame.

Images