MEMS scanning device suspension system that enables high frequency and a high mechanical tilt angle for large mirrors

Abstract

A microelectromechanical system (MEMS) device (300), comprising: an oscillator structure (20) designed to oscillate about a rotational axis (13); a frame (40) which is rotationally fixed, the frame comprising a frame recess (41) within which the oscillator structure (20) is suspended; and a suspension arrangement (30) which is mechanically coupled to and between the oscillator structure and the frame, wherein the suspension arrangement is configured to suspend the oscillator structure within the frame recess, the suspension arrangement including: a central support beam (31) extending longitudinally along the axis of rotation, wherein the central support beam is mechanically coupled to and between the oscillator structure and the frame; a first outer support beam (32) which is mechanically coupled to the oscillator structure and is offset laterally from the central support beam in a first direction orthogonal to the axis of rotation; at least a first inner support beam (33) that is directly coupled to and between the central support beam and the first outer support beam; a second outer support beam (33) which is mechanically coupled to the oscillator structure and is laterally offset from the central support beam in a second direction orthogonal to the axis of rotation, the second direction being opposite to the first direction; and at least a second inner support beam that is directly coupled to and between the central support beam and the second outer support beam, wherein the suspension arrangement further comprises an oscillator structure interface (30b) which mechanically couples the central support beam, the first outer support beam and the second outer support beam to the oscillator structure.

Description

BACKGROUND

[0001] Light Detection and Ranging (LIDAR) is a long-range sensing technique that uses light in the form of a pulsed laser to measure distances (variable distances) to one or more objects within a field of view. Specifically, a microelectromechanical system (MEMS) mirror is used to scan light across the field of view. Arrays of photodetectors receive reflections from objects illuminated by the light, and the time it takes for these reflections to reach different sensors in the photodetector array is determined. This is also known as time-of-flight (TOF) measurement. LIDAR systems create depth and distance measurements by mapping the distance to objects based on these time-of-flight calculations. Thus, the time-of-flight calculations can generate distance and depth mappings that can be used to create images.

[0002] A LiDAR scanning system can comprise one or more scanning mirrors and a corresponding circuit arrangement for scanning different fields of view in horizontal and / or vertical directions. MEMS mirrors, operating at a specific resonant frequency, can be affected by various systematic and non-systematic error sources. For example, a scanning mirror can be a non-linear oscillator with a relationship between angular amplitude and frequency.

[0003] Current, small-scale MEMS scanning devices (e.g., oscillating structures such as MEMS mirrors) exhibit limitations in the achievable (maximum) angular range and field of view, for example, in a LiDAR application. For instance, a MEMS mirror can oscillate around a scanning axis by + / -θmax, where θmax represents the maximum tilt angle of the MEMS mirror and + / -θmax the maximum angular range of the oscillation. The maximum angular range defines the field of view, which is a scanning plane onto which the transmitted light is projected. Two opposite edges of the field of view correspond to +θmax and -θmax, respectively. A neutral position of the MEMS mirror is at 0°.

[0004] A MEMS scanning device, such as a mirror, can be circular or elliptical, and its size is defined by its longest diameter. In the case of an elliptical mirror, the longest diameter corresponds to the length of the major axis, which can extend perpendicular to the scanning axis. A crucial parameter of a MEMS scanning device is the limited dynamic deformation it can tolerate, which scales with the thickness of the mirror body. For example, thinner, lighter plates result in increased dynamic deformation for a given frequency, causing distortion in the transmitted and / or received light beams. Therefore, there is limited scope for reducing inertia, as this will also affect dynamic deformation.Scaling up the MEMS scanning device to increase the mirror size results in high inertia, which must be compensated for by high-stiffness suspensions to maintain an oscillation operating frequency above 2 kHz. An operating frequency above 2 kHz enables high update rates and also avoids sensitivity to vibrations in automotive applications. A high update rate is essential for scanning a high-speed environment and capturing rapidly changing scenery data. A scanning device that is robust against vibrations is crucial, as vibrations will interfere with the scanning operation, leading to measurement inaccuracies and the inability to meet safety requirements in the automotive industry (e.g., for safety controls and autonomous driving).

[0005] However, high-stiffness suspensions limit the mechanical angle of the scanning device because an increase in mechanical stress level scales with the increase in stiffness. For a silicon-based MEMS device, a safe mechanical stress limit might be on the order of 1–2 gigapascals (GPa). However, this safe mechanical stress limit can vary based on manufacturing processes, quality, and design parameters, and may be higher than 2 GPa. Thus, high-stiffness suspensions pose a problem when limiting the maximum oscillation angle range due to the requirement to remain within the limits of a safe mechanical stress limit (e.g., 2 GPa or less).For example, due to the design limitations mentioned above, it may be difficult for a MEMS scanning device with a longest diameter of 5 millimeters (mm) or more to achieve a maximum tilt angle of 10° or more. Since the maximum oscillation angle range is limited, the field size is also limited.

[0006] Therefore, an improved MEMS oscillating structure, such as a MEMS mirror that has a large mirror diameter (≥5mm) and a large maximum mechanical tilt angle (≥10°) while operating and maintaining resonance at a high frequency (≥2kHz), may be desirable.

[0007] Publication US 2014 / 0355090A1 (D1) discloses a light deflector comprising a mounting section and a movable section. The movable section includes a mirror section for deflecting light by oscillating about a predetermined pivot axis, a torsion bar fixed to the mounting section whose axis serves as the pivot axis, and a support body that carries the mirror section and is attached to the torsion bar. The support body has a hole section through which the axis passes. A mass for setting a resonant frequency is arranged in the hole section.

[0008] Publication CN 2 04 116 713 U (D2) describes a two-dimensional scanning micromirror for an electrostatic MEM system. This essentially consists of a silicon substrate, fixed and movable comb teeth, a microlens group, and a support beam group. The disclosed structure aims to solve problems such as mirror bending caused by residual stress, as well as complex and costly fabrication, by providing a simplified device structure and a simplified machining process. SUMMARY

[0009] There is a need to provide an improved concept for a microelectromechanical system (MEMS) device.

[0010] Such a need can be met by the subject matter of one or more of the claims.

[0011] One or more embodiments provide a microelectromechanical system (MEMS) device comprising an oscillator structure configured to oscillate about a rotational axis; a frame that is rotationally fixed, the frame comprising a frame recess within which the oscillator structure is suspended; and a suspension arrangement that is mechanically coupled to and between the oscillator structure and the frame, the suspension arrangement being configured to suspend the oscillator structure within the frame recess.The suspension arrangement comprises a central support beam extending longitudinally along the axis of rotation, wherein the central support beam is mechanically coupled to and between the oscillator structure and the frame; a first outer support beam is mechanically coupled to the oscillator structure and is offset laterally from the central support beam in a first direction orthogonal to the axis of rotation; at least a first inner support beam is directly coupled to and between the central support beams and the first outer support beams; a second outer support beam is mechanically coupled to the oscillator structure and is offset laterally from the central support beam in a second direction orthogonal to the axis of rotation, the second direction being opposite the first direction; and at least a second inner support beam is directly coupled to and between the central support beam and the second outer support beam.

[0012] One or more embodiments provide an oscillator system comprising an oscillator structure configured to oscillate about a rotational axis at a resonant frequency of at least 2 kHz with a maximum displacement angle of at least 10°, the oscillator structure having a main surface having a dimension of at least 5 millimeters; a frame that is rotationally fixed, the frame comprising a frame recess within which the oscillator structure is suspended;and a suspension arrangement mechanically coupled to and between the oscillator structure and the frame, wherein the suspension arrangement is configured to suspend the oscillator structure within the frame recess. The suspension arrangement comprises a central support beam extending longitudinally along the axis of rotation, wherein the central support beam is mechanically coupled to and between the oscillator structure and the frame, the central support beam wrapping around the axis of rotation when the oscillator structure oscillates and exhibits a mechanical stress level of 3 GPa or less, while the oscillator structure oscillates around the axis of rotation at a resonant frequency of at least 2 kHz with a maximum displacement angle of at least 10°; a first outer support beam is mechanically coupled to the oscillator structure and is offset laterally from the central support beam in a first direction orthogonal to the axis of rotation;at least one first inner support beam is directly coupled to and between the central support beam and the first outer support beam; a second outer support beam is mechanically coupled to the oscillator structure and is offset laterally from the central support beam in a second direction orthogonal to the axis of rotation, the second direction being opposite to the first direction; and at least one second inner support beam is directly coupled to and between the central support beam and the second outer support beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Examples of implementation are described herein with reference to the accompanying drawings. Fig. Figure 1 is a schematic diagram of a LIDAR scanning system according to one or more embodiments; Fig. Figure 2 is a schematic block diagram of the LIDAR scanning system according to one or more embodiments; Fig. Figure 3 shows a schematic view of an example of a MEMS device according to one or more embodiments; Fig. 4A-4G represent various suspension arrangements that are implemented in a MEMS device according to one or more embodiments; and Fig. 4H shows a comparison example. DETAILED DESCRIPTION

[0014] Details are provided below to offer a more comprehensive explanation of the exemplary embodiments. However, it is obvious to those skilled in the field that embodiments can be implemented without these specific details. In other cases, known structures and devices are shown in block diagram form or in a schematic view, rather than in detail, to avoid obscuring the embodiments. Furthermore, features of the various embodiments described herein may be combined unless specifically stated otherwise.

[0015] Furthermore, equivalent or identical elements, or elements with equivalent or identical functionality, are designated by equivalent or identical reference symbols in the following description. Since the same reference symbols are given to identical or functionally equivalent elements in the figures, repeated descriptions for elements provided with the same reference symbols can be omitted. Thus, descriptions provided for elements with the same or similar reference symbols are mutually interchangeable.

[0016] In this regard, directional terminology, such as "upper", "lower", "below", "above", "front", "behind", "rear", "leading", "following", etc., can be used with respect to the orientation of the figures being described. Since parts of the embodiments can be positioned in a number of different orientations, directional terminology is used for the sake of clarity. It is understood that other embodiments can be used and structural or logical modifications can be made without deviating from the scope of protection defined by the claims. The following detailed description should therefore not be taken in a restrictive sense.Directional terminology used in the claims can help in defining the spatial or positional relationship of one element to another element or feature without being restricted to a particular orientation.

[0017] It should be noted that when an element is described as "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or intermediate elements may be present. Conversely, when an element is described as "directly" "connected" or "coupled" to another element, no intermediate elements are present. Other expressions used to describe the relationship between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0018] In embodiments described herein or shown in the drawings, any direct electrical connection or coupling, i.e., any connection or coupling without any additional intervening elements, may also be implemented by an indirect connection or coupling, i.e., a connection or coupling with one or more intervening elements, or vice versa, as long as the general purpose of the connection or coupling, for example, the transmission of a certain type of signal or the transmission of a certain type of information, is essentially maintained. Features of different embodiments may be combined to form further embodiments. For example, variations or modifications described with respect to one embodiment may also be applicable to other embodiments unless otherwise specified.

[0019] In the present disclosure, expressions including ordinal numbers, such as "first," "second," and / or the like, may modify various elements. However, such elements are not limited by the preceding expressions. For example, the preceding expressions do not restrict the sequence and / or importance of the elements. The preceding expressions are used only for the purpose of distinguishing one element from the others. For example, a first box and a second box denote different boxes, although both are boxes. As another example, a first element could be referred to as a second element, and similarly, a second element could also be referred to as a first element, without departing from the scope of protection of the present disclosure.

[0020] One or more aspects of the present disclosure may be implemented as a non-volatile, computer-readable recording medium containing a program embodying methods / algorithms for instructing the processor to execute those methods / algorithms. Thus, a non-volatile, computer-readable recording medium may contain electronically readable control signals that cooperate with (or are capable of cooperating with) a programmable computer system such that the respective methods / algorithms are executed. The non-volatile, computer-readable recording medium may, for example, be a CD-ROM, DVD, Blu-ray Disc, RAM, ROM, PROM, EPROM, EEPROM, FLASH memory, or other electronic memory device.

[0021] Each of the elements of this disclosure can be configured by implementing dedicated hardware or a software program on a memory that controls a processor to perform the functions of any of the components or combinations thereof. Any of the components can be implemented as a central processing unit (CPU) or another processor that reads or executes a software program from a recording medium, such as a hard disk or a semiconductor memory device.For example, instructions can be executed by one or more processors, such as one or more CPUs, digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or any other equivalent integrated or discrete logic circuit arrangement.

[0022] Accordingly, as used herein, the term "processor" refers to any of the preceding structures or any other structure suitable for implementing the techniques described herein. A controller comprising hardware may also execute one or more of the techniques of this disclosure. A controller comprising one or more processors may use electrical signals and digital algorithms to perform its receptive, analytical, and control functions, which may further include corrective functions. Such hardware, software, or firmware may be implemented within the same device or within separate devices to support the various techniques described in this disclosure.

[0023] Examples relate to optical sensors and optical sensor systems, and to obtaining information via optical sensors and optical sensor systems. A sensor can refer to a component that converts a physical quantity to be measured into an electrical signal, for example, a current signal or a voltage signal. The physical quantity can be, for example, electromagnetic radiation such as visible light, infrared (IR) radiation, or another type of illumination signal, or it can be a current or a voltage, but this is not limited to it. For example, an image sensor can be a silicon chip inside a camera that converts photons of light coming from a lens into voltages. The larger the active area of ​​the sensor, the more light can be collected to create an image.

[0024] A sensor device, as used herein, can refer to a device that includes a sensor and other components, for example, a bias circuit arrangement, an analog-to-digital converter, or a filter. A sensor device can be integrated on a single chip, although in other embodiments, multiple chips or even off-chip components may be used to implement a sensor device.

[0025] In light detection and ranging (LIDAR) systems, a light source emits light pulses into a field of view, and the light is reflected by one or more objects through backscattering. Specifically, LIDAR is a time-of-flight (TOF) direct system, where the light pulses (e.g., laser beams of infrared light) are emitted into the field of view, and a pixel array detects and measures the reflected beams. For example, an array of photodetectors receives reflections from objects illuminated by the light.

[0026] Differences in return times for each light pulse across multiple pixels of the pixel array can then be used to create digital 3D representations of an environment or to generate other sensor data. For example, the light source can emit a single light pulse, and a time-to-digital converter (TDC) electrically coupled to the pixel array can count from the time the light pulse is emitted, which corresponds to a start signal, until the time the reflected light pulse is received at the receiver (i.e., the pixel array), which corresponds to a stop signal. The "travel time" of the light pulse is then translated into a distance.

[0027] In another example, an analog-to-digital converter (ADC) for pulse detection and time-of-flight (ToF) measurement can be electrically coupled to the pixel array (e.g., indirectly coupled via intervening elements). For instance, an ADC can be used to estimate the time interval between start and stop signals using a suitable algorithm. For example, an ADC can be used to detect an analog electrical signal from one or more photodiodes to estimate the time interval between a start signal (i.e., corresponding to the timing of a transmitted light pulse) and a stop signal (i.e., corresponding to the timing of an analog electrical signal being received by the ADC) using a suitable algorithm.

[0028] A scanning method, such as oscillating horizontal scanning (e.g., from left to right and right to left of a field of view) or oscillating vertical scanning (e.g., from bottom to top and top to bottom of a field of view), can illuminate a scene in a continuous scanning manner. Each firing of the laser beam by the light sources can result in a scanning line within the "field of view." By emitting successive light pulses in different scanning directions, an area referred to as the field of view can be scanned, and objects within this area can be detected and imaged. Thus, the field of view represents a scanning plane with a center point of projection. Raster scanning could also be used.

[0029] Fig. Figure 1 is a schematic diagram of a LIDAR scanning system 100 according to one or more embodiments. The LIDAR scanning system 100 is an optical scanning device comprising a transmitter, including an illumination unit 10, a transmitter optic 11 and a one-dimensional (1D) microelectromechanical system (MEMS) mirror 12, and a receiver, comprising a second optical component 14 and a photodetector array 15.

[0030] The illumination unit 10 comprises several light sources (e.g., laser diodes or light-emitting diodes) arranged linearly in a single-line formation and configured to transmit light used for scanning an object. The light emitted by the light sources is typically infrared light, although light of a different wavelength can also be used. As in the embodiment of Fig. As can be seen in Figure 1, the shape of the light emitted by the light sources is spread in a direction perpendicular to the transmission direction to form a light beam with an elongated shape perpendicular to the transmission. The illumination light transmitted from the light sources is directed towards the transmitter optics 11, which are designed to focus each laser onto a one-dimensional MEMS mirror 12. The transmitter optics 11 can be, for example, a lens or a prism.

[0031] Upon reflection by the MEMS mirror 12, the light from the light sources is vertically aligned to form a one-dimensional vertical scanning line (SL) of infrared light, or a vertical line of infrared light, for each emitted laser pulse. Each light source of the illumination unit 10 contributes to a different vertical region of the vertical scanning line SL. Thus, the light sources can be activated and deactivated simultaneously to obtain a multi-segmented light pulse, with each segment corresponding to a specific light source. However, each vertical region or segment of the vertical scanning line SL can also be independently active or inactive by switching a corresponding light source of the illumination unit 10 on or off. Therefore, a partial or complete vertical scanning line SL of light from the system 100 can be projected into the field of view.

[0032] Accordingly, the transmitter of system 100 is an optical arrangement designed to generate laser beams based on the laser pulses, wherein the laser beams have an elongated shape extending in a direction perpendicular to a transmission direction of the laser beams.

[0033] Additionally, although three laser sources are shown, it should be noted that the number of laser sources is not limited to this. For example, the vertical scanning line SL can be generated by a single laser source, two laser sources, or more than three laser sources.

[0034] The MEMS mirror 12 is a mechanical moving mirror (i.e., a MEMS micromirror) that is monolithically mounted on a semiconductor chip (see Fig. 3) is integrated. The MEMS mirror 12 according to this embodiment is suspended by a mechanical suspension system that enables high frequency and a large maximum mechanical tilt angle for large mirrors. As described in more detail below, the MEMS device comprises a microframe, the mechanical suspension system, and a mirror body, which are monolithically integrated into a one-piece integral structure, thereby forming a MEMS semiconductor chip. A reflective material can be deposited onto the silicon-based mirror body to form a reflective surface of the MEMS mirror 12.

[0035] In this example, the MEMS mirror 12 is configured to rotate about a single axis (i.e., a scanning axis) and can be described as having only one degree of freedom for motion. Because of this single axis of rotation, the MEMS mirror 12 is referred to as a 1D MEMS mirror.

[0036] To make a MEMS scanning mirror robust against vibrations, the mirror should have low inertia, i.e., a lightweight and rigid mirror body. Additionally, the mirror should exhibit high stiffness in its suspension for all degrees of freedom (DOF) of the mirror body.

[0037] To achieve a lightweight and rigid mirror body, the mirror body can have a relatively thin mirror and a thicker reinforcing structure. The mirror body can be rotatably mounted within a mirror frame around an axis of rotation that extends into a plane defined by the mirror frame. The axis of rotation can extend to the first and second opposing end sections of the mirror body. The mirror body can have a reflective surface on a first primary surface and, opposite the first primary surface, a second primary surface provided by the reinforcing structure.

[0038] To achieve a high-stiffness suspension, the mirror body can be supported in the mirror frame using central support beams 31 extending along the axis of rotation, outer support beams 32 arranged symmetrically on opposite sides of the central support beam 31, and inner support beams 33 coupled directly to the central support beam 31 and directly to a corresponding outer support beam 32, as shown in Fig. 3 shown.

[0039] In general, the central support beam 31 allows for a high mechanical tilting angle, while the mechanical stress in the central support beam 31 itself is kept relatively low. The length, width, and thickness of the central support beam 31 can be adjusted to achieve the desired stress level and rotational or torsional stiffness about a rotational axis 13 (i.e., a scanning axis). The inner support beams 33 can provide support to the outer support beam 32. The inner support beams 33 contribute a small amount to the rotational or torsional stiffness about the rotational axis 13 but are primarily used to increase stiffness for unwanted movements (i.e., other rotational and translational movements different from the rotational movement about the rotational axis 13).

[0040] For example, if the rotation axis 13 extends along a Y-axis, as in Fig. As shown in Figure 3, the central support beam 31 provides the primary contribution to the rotational or torsional stiffness about an axis of rotation 13, while the inner support beams 33 provide a small contribution to the rotational or torsional stiffness about the axis of rotation 13. Additionally, the inner support beams 33 provide stiffness against unwanted rotational movements about the X-axis and the Z-axis, as well as stiffness against unwanted translational movements in the X- and Z-directions.

[0041] The design of the suspension arrangement allows for high stiffness (torsional / rotational motion) for operation around the target axis to overcome the high inertia imposed by the size of the mirror 12, thus enabling high-resonance frequency operation (≥2 kHz). Meanwhile, the mechanical stress level is limited to or below 3 GPa for large maximum mechanical tilt angles of 10° to 15°, and perhaps preferably to or below 2 GPa, depending on the target maximum mechanical tilt angle. Reducing the thickness of the mirror body, and thus reducing inertia, is also limited by acceptable dynamic deformation, which allows for acceptable scanning operations of transmitted and received light beams. However, the safe mechanical stress limit for a silicon-based MEMS device can vary based on processing methods, quality, and design parameters, and may be higher than 3 GPa.A lower mechanical stress limit helps ensure that the suspension assembly does not fail during operation. It therefore plays a crucial role in the overall system design constraints. However, the lower the mechanical stress limit, the more difficult it becomes to achieve larger tilt angles for large mirrors at high resonant frequencies while still remaining within the desired mechanical stress limit. Thus, the suspension assembly design can be such that a maximum mechanical tilt angle of up to 11.5° is achieved while limiting the mechanical stress level to or below 2 GPa, and a maximum mechanical tilt angle of up to 15° is achieved while limiting the mechanical stress level to or below 3 GPa.

[0042] The suspension arrangement is further designed to suppress higher unwanted modes (other translational and rotational modes that have significantly higher frequencies than the desired operating modes).

[0043] The low inertia and high suspension stiffness of the mirror body can result in high resonant frequencies and good dynamic performance. These properties can also make the component, when operated at the resonant frequency around the main axis of rotation, very fast. During normal operation, i.e., at resonance, accelerations of typically 10,000 G can be achieved at the mirror ends. This can make any external vibrations negligible.

[0044] The MEMS mirror 12 exhibits nonlinear behavior, possibly due to the stiffness of the suspension structure, such that the oscillation frequency of the mirror increases in a nonlinear manner with an increase in the oscillation amplitude (i.e., deflection angle amplitude θ).

[0045] The MEMS mirror 12 can be arranged in a chip package 27 for protection of the mirror, which is located in Fig. Figure 2 shows that the MEMS mirror 12 can, for example, be hermetically sealed in a chip package at low pressure (i.e., at a pressure below atmospheric pressure). This low pressure can provide a low-attenuation environment in which the MEMS mirror 12 operates.

[0046] Possible packages can include or differ in one or more of the following variations: different substrates (e.g., metal (leadframe), ceramic, organic (similar to printed circuit board (PCB) material)) and different optical lids or covers (e.g., optical material made of glass, silicon, sapphire, etc.). Furthermore, the optical lids or covers can be cavity-forming caps, integrated into a frame (e.g., a metal frame), or mounted on a pre-formed cavity or a ceramic cavity.

[0047] One or more methods (e.g., adhesive bonding, gluing, soldering, welding, and the like) or one or more different materials (e.g., silicone, glass solder, AuSn, and the like) can be used to bond one or more elements together (e.g., connecting cap or lid to substrate). It should be noted that bonding methods may be interchangeable across different embodiments disclosed herein.

[0048] Alternatively, a wafer-level approach can be used, such that a hollow lid can be attached directly to the MEMS chip (or even at the wafer level before singulation). If the lid attachment leaves the electrical contact pads exposed, the chip / lid attached underneath can be further processed into a package using forming or casting processes.

[0049] The MEMS mirror 12 is a mechanical moving mirror (i.e., a MEMS micromirror) mounted on a semiconductor chip (see Fig. 3) is integrated. The MEMS mirror 12 comprises a silicon-based mirror body onto which a reflective material is deposited. The MEMS mirror 12 according to this embodiment is configured to rotate about a single scanning axis and can be described as having only one degree of freedom for scanning. In contrast to 2D MEMS mirrors (2D MEMS scanning devices), in the 1D MEMS mirror the single scanning axis is attached to a non-rotating substrate and thus maintains its spatial orientation during the oscillation of the MEMS mirror. Thus, a 1D oscillating MEMS mirror is inherently more robust to vibrations and shocks than 2D MEMS mirror solutions. Because of this single scanning rotation axis, the MEMS mirror 12 is referred to as a 1D MEMS mirror or a 1D MEMS scanning device.While exemplary embodiments describe the use of 1D oscillating MEMS mirrors, the suspension system described herein can also be extended to 2D MEMS mirrors. In this case, suspension systems are used for each axis of a 2D MEMS mirror.

[0050] The MEMS mirror 12 itself is a nonlinear resonator (i.e., a resonant MEMS mirror) configured to oscillate side-to-side around a single scanning axis 13 at a resonant frequency such that the light reflected from the MEMS mirror 12 (i.e., the vertical scanning line of light) oscillates backward and forward in a horizontal scanning direction. A scanning period, or oscillation period, is defined, for example, by a complete oscillation from a first edge of the field of view (e.g., left side) to a second edge of the field of view (e.g., right side) and then back to the first edge. One mirror period of the MEMS mirror 12 corresponds to one scanning period.

[0051] Thus, the field of view is scanned horizontally by the vertical light beam by changing the angle θ of the MEMS mirror 12 on its scanning axis 13. For example, the MEMS mirror 12 can be configured to oscillate at a resonant frequency of 2 kHz between + / -11.25 degrees to deflect the light over 22.5 degrees. Additional transmission optics can be provided to double the angular range that constitutes the scanning area of ​​the field of view. The field of view can then be scanned line by line by rotating the MEMS mirror 12 through its degree of movement. Such a sequence through the degree of movement (e.g., from -11.25 degrees to +11.25 degrees) is referred to as a single scan or scan cycle. Multiple scans can be used to generate distance and depth mappings, as well as 3D images, by a processing unit.

[0052] While the transmission mirror is described in the context of a MEMS mirror, it should be noted that other 1D mirrors can also be used. Additionally, the resonant frequency of the rotation is not limited to 2 kHz and ±11.25 degrees, as required by the application. Thus, a one-dimensional scanning mirror is designed to oscillate around a single scanning axis and direct the laser beams in different directions within a field of view. Therefore, a transmission technique involves transferring the light beams into the field of view from a transmission mirror oscillating around a single scanning axis, so that the light beams are projected into the field of view as a vertical scanning line SL, which moves horizontally across the field of view while the transmission mirror oscillates around the single scanning axis.

[0053] After striking one or more objects, the transmitted vertical beam of light is backscattered as a reflected vertical line back towards the LIDAR scanning system 100, where the second optical component 14 (e.g., a lens or prism) receives the reflected light. The second optical component 14 directs the reflected light onto the photodetector array 15, which receives the reflected light as a receiving line (RL) and is configured to generate electrical measurement signals. These electrical measurement signals can be used to generate a 3D image of the environment and / or other object data based on the reflected light (e.g., by time-of-flight calculations and processing).

[0054] The receiving line is shown as a vertical light slit extending along one of the pixel columns in a longitudinal direction. The receiving line has three regions corresponding to the vertical scan line SL, which is shown in Fig. Figure 1 shows that, since the vertical scanning line SL moves horizontally across the field of view, the vertical light slit RL incident on the 2D photodetector array 15 also moves horizontally across the 2D photodetector array 15. The reflected light beam RL moves from a first edge of the photodetector array 15 to a second edge of the photodetector array 15, while the receiving direction of the reflected light beam RL changes. The receiving direction of the reflected light beam RL corresponds to a transmission direction of the scanning line SL.

[0055] The photodetector array 15 can be any of a number of photodetector types, including avalanche photodiodes (APDs), single-photon avalanche diodes (SPADs), photocells, and / or other photodiode devices. Imaging sensors, such as charge-coupled devices (CCDs), can also be the photodetectors. In the examples provided herein, the photodetector array 15 is a two-dimensional (2D) APD array comprising an array of APD pixels. In other embodiments, the photodetector array 15 can be a 1D array comprising a single column of photodiodes. The activation of the photodiodes can be synchronized with light pulses emitted by the illumination unit 10. Alternatively, a single photodetector call per pixel can be used, as opposed to an array.For example, a single photodetector call / pixel can be used in the case of a 2x1D scanning transmitter in a coaxial LIDAR architecture.

[0056] The photodetector array 15 receives reflected light pulses as the receiving line RL and generates electrical signals in response. Since the time of transmission of each light pulse from the illumination unit 10 is known, and since the light travels at a known speed, a time-of-flight calculation using the electrical signals can determine the distance of objects from the photodetector array 15. A depth mapping function can graphically represent the distance information.

[0057] In one example, a microcontroller triggers a laser pulse from each of the light sources of the illumination unit 10 for each distance scan and also starts a timer in an integrated circuit (IC) of a time-to-digital converter (TDC). The laser pulse is propagated through the transmission optics, reflected by the target field, and detected by an APD of the APD array 15. The APD emits a short electrical pulse, which is then amplified by an electrical signal amplifier. A comparator IC detects the pulse and sends a digital signal to the TDC to stop the timer. The TDC uses a clock frequency to calibrate each measurement. The TDC sends the serial data of the time difference between the digital start and stop signals to the microcontroller, which filters out any erroneous readings, averages multiple time measurements, and calculates the distance to the target at that specific field position.By emitting successive light pulses in different directions, produced by the MEMS mirror, an area (i.e., a field of view) can be scanned, a three-dimensional image can be generated, and objects within the area can be detected.

[0058] Alternatively, instead of using the TDC approach, ADCs can be used for signal detection and ToF measurement. For example, any ADC can be used to detect an analog electrical signal from one or more photodiodes in order to estimate a time interval between a start signal (i.e., corresponding to the timing of a transmitted light pulse) and a stop signal (i.e., corresponding to the timing of receiving an analog electrical signal at an ADC) using a suitable algorithm.

[0059] It is noted that the previously described horizontal scanning system 100 can also be used for vertical scanning. In this case, the scanning arrangement is configured such that the scanning direction is rotated by 90°, so that the scanning line SL and the receiving line RL move in a vertical direction (i.e., from top to bottom or from bottom to top). As such, the scanning line is a horizontal scanning line SL projected into the field of view and moves vertically across the field of view as the transmission mirror oscillates around the single scanning axis. Furthermore, as the horizontal scanning line SL moves vertically across the field of view, the horizontal light slit RL incident on the 2D photodetector array 15 also moves vertically across the 2D photodetector array 15.

[0060] Fig. Figure 2 is a schematic block diagram of the LIDAR scanning system 200 according to one or more embodiments. In particular, it shows Fig. 2 additional features of the LIDAR scanning system 200, including exemplary processing and control system components, such as a MEMS driver, a receiver circuit and a system controller.

[0061] The LiDAR scanning system 200 comprises a transmitter unit 21, responsible for one emitter path of the system 200, and a receiver unit 22, responsible for one receiver path of the system 200. The system also includes a control unit 23, configured to control components of the transmitter unit 21 and the receiver unit 22, and to receive raw data from the receiver unit 22 and perform processing on it (e.g., via digital signal processing) to generate object data (e.g., point cloud data). Thus, the control unit 23 includes at least a processor and / or a processor circuit arrangement for data processing, as well as a control circuit arrangement, such as a microcontroller, configured to generate control signals. The LiDAR scanning system 200 may also include a temperature sensor 26.

[0062] The receiver unit 22 comprises the photodetector array 15 and a receiver circuit 24. The receiver circuit 24 can include one or more circuit arrangements or sub-circuit arrangements for receiving and / or processing information. The receiver circuit 24 can receive the analog electrical signals from the APD diodes of the photodetector array 15 and transmit the electrical signals as raw analog or raw digital data to the control unit 23. To transmit the raw data as digital data, the receiver circuit 24 can include an analog-to-digital converter (ADC) and a field-programmable gate array (FPGA). The receiver circuit 24 can also receive trigger control signals from the control unit 23, which trigger the activation of one or more APD diodes. The receiver circuit 24 can also receive gain setting control signals for controlling the gain of one or more APD diodes.

[0063] The transmitter unit 21 comprises the illumination unit 10, the MEMS mirror 12, and a MEMS driver 25, which is configured to drive the MEMS mirror 12. Specifically, the MEMS driver 25 actuates and detects the rotational position of the mirror and provides position information (e.g., tilt angle or degree of rotation about the axis of rotation) of the mirror to the control unit 23. Based on this position information, the laser sources of the illumination unit 10 are triggered by the control unit 23, and the photodiodes (e.g., APD diodes) are activated to detect and thus measure a reflected light signal. Therefore, higher accuracy in the position detection of the MEMS mirror leads to more accurate and precise control of other components of the LiDAR system.

[0064] The MEMS driver 25 can also measure and record an image frequency and currents using a change in capacitance in a comb drive rotor and stator of an actuator structure used to drive the MEMS mirror 12. The actuator structure of the MEMS mirror 12 further includes the suspension structure discussed above. Thus, the MEMS driver 25 can further include a measurement circuit configured to measure one or more characteristics of the MEMS mirror 12 described herein. The MEMS driver 25 can further include a processing circuit arrangement comprising at least one processor (e.g., an analog signal processing circuit arrangement and / or a digital signal processing circuit arrangement) configured to process measurement information from the measurement circuit to evaluate the mechanical health of the MEMS mirror 12 and / or the condition of the chip package.

[0065] Additionally or alternatively, the control unit 23 can receive measurement information from the measurement circuit of the MEMS driver 25 and process it. Thus, the control unit 23 can further comprise a processing circuit arrangement, including at least one processor (e.g., an analog signal processing circuit arrangement and / or a digital signal processing circuit arrangement) configured to process measurement information from the measurement circuit in order to assess the mechanical health of the MEMS mirror 12 and / or the condition of the chip package.

[0066] By detecting the rotational position of the MEMS mirror 12 about its rotational axis 13, the MEMS driver 25 can detect zero-crossing events of the MEMS mirror 12. A zero-crossing event occurs when the MEMS mirror 12 has a rotational angle of 0° about its rotational axis 13. Specifically, it is the moment when the MEMS mirror 12 is parallel to the frame or in a neutral position. The neutral position can also be referred to as the rest position (e.g., when the MEMS mirror 12 comes to a standstill after the driving force is switched off). Since the MEMS mirror 12 oscillates between two rotational directions, backward and forward (clockwise and counterclockwise), a zero-crossing event occurs twice during a sampling period—once when the mirror oscillates in the first rotational direction and once when the mirror oscillates in the second rotational direction.It is also noted that angle crossing events can be used at a different predefined angle instead of a zero crossing event.

[0067] The MEMS driver 25 can send the position information to the control unit 23, which can then use this information to control the triggering of the laser pulses of the illumination unit 10 and the activation of the photodiodes of the photodetector array 15. The control unit can also use the position information as feedback, enabling it to maintain stable operation of the MEMS mirror 12 via control signals provided to the MEMS driver 25, and also to maintain synchronization with other MEMS mirrors.

[0068] The MEMS mirror 12 includes an actuator structure used to drive the mirror. The actuator structure comprises toothed finger electrodes made of toothed mirror combs and frame combs, to which a drive voltage (e.g., an actuation signal or a drive signal) is applied by the MEMS driver 25. The drive voltage can be described as a high voltage (HV). The drive voltage applied to the finger structure creates a corresponding capacitance. The drive voltage across the finger structure generates a driving force between the toothed mirror comb electrodes and the frame comb electrodes, which in turn generates a torque on the mirror body 20 about the axis of rotation. The drive voltage can be switched on and off or toggled between an on and off state, resulting in an oscillating driving force.The oscillating driving force causes the mirror to oscillate backward and forward on its axis of rotation between two extremes. Depending on the configuration, this actuation can be regulated or adjusted by modifying the drive voltage off-time, the voltage level of the drive voltage, or the duty cycle.

[0069] In other embodiments, an electromagnetic actuator can be used to drive the MEMS mirror 12. With an electromagnetic actuator, a drive current (i.e., an actuation or drive signal) can be used to generate the oscillating drive force. Thus, it is noted that drive voltage and drive current can be used interchangeably here to denote an actuation signal or a drive signal, and both can be generally referred to as a drive force.

[0070] As the mirror oscillates, the capacitance or charge between the finger electrodes changes according to the mirror's rotational position. The MEMS driver 25 is configured to measure the capacitance or charge between the toothed finger electrodes and to determine the rotational or angular position of the MEMS mirror 12 from this measurement. By monitoring the capacitance or charge, the MEMS driver 25 can detect zero-crossing events and their timing, and can determine the displacement or tilt angle of the MEMS mirror 12 at any given moment. The MEMS driver 25 can also use the measured capacitance to determine a mirror frequency and record the information in a memory on the MEMS driver 25 or on the control unit 23.

[0071] The position of the MEMS mirror 12 is determined using a detector designed to measure capacitance or charge. For example, when the MEMS mirror moves, the geometry of the finger structure changes, resulting in a change in the capacitance geometry. As the capacitance geometry changes, the capacitance itself changes. Thus, a specific capacitance directly corresponds to a specific displacement position (e.g., a tilt angle) of the MEMS mirror. By sensing the capacitance of the finger structure, the MEMS driver 25 can monitor and track the mirror's oscillations and determine a specific position of the MEMS mirror, including its zero crossing.

[0072] One way to measure capacitance is to measure the current flowing through the finger electrode structure, convert the measured current into a voltage, and then further correlate the voltage with the capacitance and / or rotation angle θ. However, any method can be used to measure capacitance. A direction of rotation (e.g., positive or negative, left-to-right or right-to-left, clockwise or counterclockwise, etc.) is also detected by measuring a change in capacitance over time, with a positive or negative change indicating opposite directions of rotation. The MEMS driver 25 can also record the currents and voltages measured during capacitance measurement. Thus, increasing the accuracy of the mirror's position detection can improve the overall accuracy of the LiDAR system.

[0073] Since the mirror is driven at an oscillation frequency (e.g., ≥ 2 kHz), it will cross a zero position (i.e., 0°) at a given time when rotating in a first direction (e.g., from left to right or clockwise). Similarly, when rotating in a second direction (e.g., from right to left or counterclockwise), the mirror will cross the zero position at a given time. These instances of crossing the zero position can be referred to as zero-crossing events, occurring at zero-crossing times.

[0074] Fig. Figure 3 shows a schematic view of an example of a MEMS device 1 according to one or more embodiments. The MEMS device 300 can also be referred to as a MEMS semiconductor chip. Referring to Fig. 3. An example of a MEMS component 300, such as a MEMS scanning micromirror, will now be discussed.

[0075] The MEMS device 300 comprises a mirror body 20, a mirror frame 40, and two mechanical suspension assemblies 30 arranged at opposite ends of the mirror body 20 along the axis of rotation 13. The mirror frame 40, the mechanical suspension assemblies 30, and the mirror body 20 are monolithically integrated in a single-piece integral structure, thus forming a MEMS semiconductor chip. The mirror frame 40, the mechanical suspension assemblies 30, and the mirror body 20 are formed from a single block of semiconductor material (i.e., a semiconductor substrate) by etching and / or other semiconductor processing techniques.

[0076] The mirror body 20 comprises a mirror 12, which together form an oscillating structure. The mirror body 20 is arranged within the mirror frame 40. The frame 40 defines a plane, i.e., the (x, y)-plane in Fig. 3. In particular, the mirror frame 40 has an upper main surface 41 that defines a chip plane. The main surface 41 of the mirror frame 40 and a main surface of the mirror body 20, on which the mirror 12 is mounted, can be formed from the same substrate surface. A frame recess 42 is formed in the body of the mirror frame 40 (i.e., in the semiconductor substrate from the main surface 41) and separates the mirror frame 40 from the mirror body 20, so that the mirror body 20 can oscillate about the rotation axis 13 while the mirror frame 40 remains rotationally fixed. Similarly, the upper (main) surface of the suspension assemblies 30 is formed from the same substrate surface as the main surface 41 of the mirror frame 40 and a main surface of the mirror body 20.

[0077] The mirror body 20 is rotatable about an axis of rotation 13 extending in the plane defined by the frame 40. Each suspension assembly 30 comprises a frame interface 30a, coupled to and integrated with the mirror frame 40, and a mirror body interface 30b, coupled to and integrated with the mirror body 20. Each suspension assembly 30 further comprises support beams, which can also be called torsion beams, connected between the mirror body 20 and the frame 40 (i.e., extending from the frame support 30a to the mirror support 30b) along the axis of rotation 13. The mirror body interface 30b supports the mirror body 20 via the connection of the support beams to the frame 40. Thus, the mirror body interface 30b can also be referred to as a mirror support structure 30b. One of the support beams of each suspension arrangement 30 is collinear with the axis of rotation 13.This support beam can be referred to as a central support beam 31. The central support beams 31 connect parts of the mirror body 20 with parts of the frame 40 and allow the mirror body 20 to rotate about the axis of rotation 13.

[0078] Experts in the field will recognize that the shape of the mirror 12 can be any shape desired for a particular application, such as a circle, an ellipse, a square, a rectangle, or any other shape as required. The mirror can have a dimension D1 of at least 5 mm, which defines its largest dimension in the XY plane (i.e., in the chip plane defined by the main (top) chip surface). In contrast, the length of the suspension arrangement 30 can have a dimension D2. In this example, the length of dimension D2 can be 1.7 mm, but this dimension can be increased or decreased based on the application.

[0079] The mirror frame 40 additionally defines a frame recess 42 in which the mirror body 20 is arranged. The mirror frame 40 can also be structured to define further recesses in which other components, such as actuators and suspension assemblies, can be arranged. For example, a suspension assembly recess 43 is defined between the mirror frame 40 and each suspension assembly 30 to allow the suspension assembly to rotate or turn when the mirror body 20 rotates about the axis of rotation 13. Furthermore, recess sections or cavities are formed between the support beam structures of the suspension assemblies 30.

[0080] Torsional stiffness about the axis of rotation 13 can be adjusted using the suspension arrangements 30. The pair of central support beams 31 supports the mirror body 20 vertically within a cavity (i.e., the frame recess 42), i.e., perpendicular to a main surface 41 of the frame 40, at the axis of rotation 13, while providing high torsional stiffness about the target axis 13 for operation and with reduced mechanical stress. The suspension arrangement 30 also allows selective stiffness tuning using the inner support beams 33, which behave like springs. The inner support beams 33 can be used to fine-tune the torsional stiffness about the target axis 13 by adjusting their thickness or number.The inner support beams 33 further increase the stiffness against the undesired translational and rotational modes and enable good mode separation, whereby the operating frequency of the first mode around the rotational axis 13 is then much lower than all other undesired modes.

[0081] For example, the inner support beams 33 can establish a flexible coupling between the central support beam 31 and the mirror body 20. As a result, the inner support beams 33 exhibit relatively low torsional / rotational stiffness with respect to the direction of rotation about the axis of rotation 13. The inner support beams 33 exhibit relatively high stiffness in the other rotational and translational directions.

[0082] The natural frequency of the mirror body 20 can be essentially determined by the central support beams 31. The natural frequency, as defined herein, is the undamped frequency of the mirror body 20 (i.e., the mirror 12) about its axis of rotation 13. The inner support beams 33 can define the out-of-plane rocking, the vertical-mode stiffness for the corresponding dynamic modes, and the corresponding resonant frequencies. The torsional stiffness about the axis of rotation 13 can be decoupled from the out-of-plane rocking and the vertical-mode stiffness such that the out-of-plane rocking and vertical-mode frequencies can be adjusted to desired values, such as higher values, without affecting the torsional-mode stiffness and the resonant frequency.As defined herein, the Y-axis is along the rotation axis 13, the X-axis is perpendicular to the Y-axis on the mirror plane when the mirror 12 is at rest, and the Z-axis is perpendicular to and extending out of the mirror plane when the mirror 12 is at rest. The X-, Y-, and Z-axes are axes of a three-dimensional Cartesian coordinate system.

[0083] The suspension arrangements are designed to enable a MEMS scanning device to meet the following requirements: a large mirror diameter (≥5 mm), a large mechanical tilt angle (≥10°), and a high resonant frequency (≥2 kHz). Specifically, the central support beams 31 wrap around the axis of rotation 13 when the mirror body oscillates and exhibits a mechanical stress level of 3 GPa or less, while the mirror body 20 oscillates around the axis of rotation 13 at a resonant frequency of at least 2 kHz with a maximum deflection angle of at least 10°. In particular, the central support beams 31 exhibit a mechanical stress level of 2 GPa or less with a maximum deflection angle of the mirror body 20 up to 11.5°, and the central support beams 31 exhibit a mechanical stress level of 3 GPa or less with a maximum deflection angle of the mirror body 20 up to 15°.In some arrangements of the suspension arrangements, the central support beams 31 can have a mechanical stress level of 1GPa or less, with a maximum deflection angle of the mirror body 20 up to 11°.

[0084] As each of the central support beams 31 winds, one side of each suspension assembly 30 dips into the frame recess 43 while the other side rises out of the frame recess 43. The two sides oscillate in and out of the frame recess 43 as the mirror body 20 oscillates about the axis of rotation 13. The resonant frequency for the rotation of the mirror 12 about the axis of rotation 13 can be defined primarily by the inertia of the mirror body 20 and the stiffness of the suspension assemblies 30, which can be defined by the bending stiffness of the central support beams 31 and the inner support beams 33, and by the torsional and translational stiffness of the inner support beams 33. The bending stiffness of the central support beams 31 can be defined by their length, width, and, in particular, their thickness.The combined stiffness of the central support beams 31 and the inner support beams 33 in the X-direction prevents movement of the mirror body 20 perpendicular to the axis of rotation 13 (in the X-direction) during operation. Likewise, the combined stiffness in the Z-direction of the central support beams 31 and the inner support beams 33 prevents movement of the mirror body 20 perpendicular to the axis of rotation 13 (in the Z-direction) during operation.

[0085] The central support beams 31 can have a rectangular cross-section as a rectangular prism perpendicular to the axis of rotation 13, wherein the long axis of the rectangle is parallel to the axis of rotation 13 and a short axis is perpendicular to the axis of rotation 13.

[0086] The MEMS device 300 can also include actuator structures 50, which are provided and integrated with a semiconductor substrate. The actuator structures can be an extension of the suspension assemblies 30 and are located in an extension of the suspension assembly recess 43. The actuator structure 50 receives drive signals from the MEMS driver 25 and provides torque to drive the mirror body 20 about the axis of rotation 13. In one example, the actuator structures 50 can be comb drives comprising mirror combs attached to the mirror body 20, which are nested with frame combs attached to the frame 40. Applying a potential difference between the nested mirror combs and frame combs generates a driving force between the mirror combs and the frame combs, which produces a torque on the mirror body 20 about the axis of rotation 13.An oscillating electrical potential can be applied to drive the mirror element at its natural frequency.

[0087] In other examples, actuation methods can include electromagnetic actuation and piezoelectric actuators. With electromagnetic actuation, the micromirror can be immersed in a magnetic field, and an alternating electric current through conductive paths can generate the oscillating torque around the axis of rotation 13. Piezoelectric actuators can be integrated into the leaf springs, or the leaf springs can be made of piezoelectric material to generate alternating beam bending forces in response to an electrical signal and thus produce the oscillating torque.

[0088] The MEMS mirror 12 exhibits nonlinear behavior due to torsional stiffness about the rotation axis 13, caused by the suspension arrangements 30, such that the oscillation frequency of the mirror 12 increases nonlinearly with an increase in the oscillation amplitude θ (i.e., displacement angle amplitude). Thus, stiffening the central support beams 31 during rotation of the mirror causes the MEMS mirror 12 to become more nonlinear.

[0089] Fig. Figures 4A-4H represent different suspension arrangements 30 that are implemented in a MEMS device 300 according to one or more embodiments. Each of the suspension arrangements 30 that are implemented in Fig. As shown in Figures 4A-4H, the system comprises a frame interface 30a, which is coupled to and integrated with the mirror frame 40, and a mirror body interface 30b (i.e., a mirror support structure), which is coupled to and integrated with the mirror body 20. Additionally, each of the suspension assemblies 30 comprises a central support beam 31 extending along the axis of rotation, two outer support beams 32 arranged on opposite sides of the central support beam 31, and inner support beams 33 that are directly coupled to the central support beam 31 and directly to a corresponding outer support beam 3.

[0090] It is noted that the central support beam 31 can be directly coupled to and integrated with the mirror frame 40, as shown in Fig. Figure 4G shows that the corresponding longitudinal end of the central support beam 31 represents the frame interface 30a. The thickness and / or width of the central support beam 31 provides high torsional / rotational stiffness about the axis of rotation 13 to overcome the high inertia of the mirror body 20, which reaches or exceeds 5 mm, thus enabling operation at a high resonant frequency (≥2 kHz). The uniform thickness (i.e., in the Z dimension) and / or width (i.e., in the X dimension) of the central support beam 31 also limits the mechanical stress level to 3 GPa or less, and preferably to 2.5 GPa or less, and even more preferably to 2 GPa or less, for large mechanical tilt angles of 10° to 15° or greater. For example, the thickness of the central support beam 31 can be in the range of 10-100µm and the width of the central support beam 31 can be in the range of 20µm-500µm.In particular, the central support beam 31 has a mechanical stress level of 2GPa or less with a maximum deflection angle of the mirror body 20 up to 11.5°, and the central support beam 31 has a mechanical stress level of 3GPa or less with a maximum deflection angle of the mirror body 20 up to 15°.

[0091] Furthermore, it is noted that each of the suspension arrangements 30 comprises at least two inner support beams 33 extending from the central support beam 31 in opposite directions towards different outer support beams 32. The thickness and width dimensions of the inner support beams 33 are smaller than the thickness and width dimensions of the central support beam 31, possibly by a considerable amount. For example, the thickness of the inner support beams 33 can be in the range of 10–100 µm, and the width of the inner support beams 33 can be in the range of 10–40 µm, and can be configured to be in the range of 2% to 60% of the thickness of the central support beam 31.

[0092] Together, the inner support beams 33 can form a spring-like network that provides a low degree of torsional / rotational stiffness about the axis of rotation 13 and a high degree of stiffness in other (i.e., at least one) rotational and / or translational directions. Alternative names for the inner support beams 33 include: spring support beams, network support beams, angled support beams, and / or brace support beams.

[0093] The outer support beams 32 provide a structure for connecting the inner support beams 33 to the mirror body interface 30b and / or to the mirror body 20.

[0094] Referring to Fig. A suspension arrangement 30A is provided at 4A. A longitudinal dimension of the central support beam 31 extends along the axis of rotation 13 between the mirror frame 40 and the mirror body 20. In this example, the central support beam 31 is directly integrated and coupled with the frame interface 30a and the mirror body interface 30b. However, it is conceivable that the central support beam 31 is directly integrated and coupled with the mirror frame 40 and the mirror body 20.

[0095] The outer support beams 32 each have a longitudinal dimension extending parallel to the axis of rotation 13 and are connected at one end to the mirror body interface 30b. However, it is conceivable that the outer support beams 32 are directly integrated and coupled to the mirror body 20.

[0096] The suspension arrangement 30a further comprises two pairs of angled inner support beams 33a, 33b, 33c and 33d, which are arranged symmetrically with respect to the central support beam 31 and the axis of rotation 13. The angled inner support beams 33a, 33b, 33c and 33d branch off from the central support beam 31 at a predefined angle. The angled inner support beam 33a is parallel to 33c and the angled inner support beam 33b is parallel to 33d.

[0097] The first pair of angled inner support beams 33a and 33b are symmetrically connected to the central support beam 31 at their connection points 35 and symmetrically connected to their corresponding outer support beam 32 at their connection points 36. Thus, the first pair of angled inner support beams 33a and 33b form a symmetrical V-shape, with their connection points 35 having a smaller lateral distance D3 from the mirror frame 40 in a direction parallel to the axis of rotation 13 than the lateral distance D4 of their respective connection points 36. In other words, the angle formed between each angled inner support beam and the central support beam is greater than 0° and less than 90°. Thus, the opening of the “V” points towards the mirror body 20, whereas the vertex of the “V” points towards the mirror frame 40, and it can be said that the angled inner support beams 33 are angled towards the mirror body 20.

[0098] Similarly, the second pair of angled inner support beams 33c and 33d is symmetrically connected to the central support beam 31 at their connection points 35 and symmetrically connected to their corresponding outer support beam 32 at their connection points 36. Like the first pair, the second pair of angled inner support beams 33c and 33d forms a symmetrical V-shape, and it can be said that the angled inner support beams 33 are angled towards the mirror body 20.

[0099] The angled inner support beams 33a, 33b, 33c and 33d can also be arranged such that the connection points 36 of the first pair 33a and 33b are aligned with the connection points 35 of the second pair 33c and 33d in a direction perpendicular to the axis of rotation 13.

[0100] The cavities 34, comprising cavities 34a, 34b, 34c, and 34d, are formed between the respective support structures of the suspension arrangement 30 and are defined by the area between these support structures. The cavities 34 allow the angled inner support beams 33a, 33b, 33c, and 33d to rotate about the axis of rotation 13 when the mirror body 20 oscillates about the axis of rotation 13.

[0101] The angled inner support beams 33 behave like a set of springs connecting the central support beam 31 to the mirror body 20 via the outer support beams 32, which are spaced laterally from the axis of rotation 13, in a direction perpendicular to the axis of rotation 13. In some designs, only the first or second pair of angled inner support beams may be present. In other designs, one or more additional pairs of angled inner support beams may be added. In this way, the torsional / rotational stiffness with respect to the direction of rotation of the mirror body 20 about the axis of rotation 13 can be fine-tuned. In other words, each pair of angled inner support beams can add to the torsional / rotational stiffness provided by the central support beam 31 with respect to the direction of rotation of the mirror body 20 about the axis of rotation 13.Additionally, the number of pairs of angled inner support beams adjusts the stiffness of the suspension arrangement 30 with regard to the undesired modes and movements of the mirror body 20.

[0102] Fig. 4B represents a suspension arrangement 30B similar to that in Fig. The suspension arrangement 30A shown in Figure 4A is identical, except that the suspension arrangement 30B includes additional pairs of angled inner support beams arranged symmetrically with respect to the central support beam 31 and the axis of rotation 13. The number of angled inner support beams is increased, resulting in a denser mesh and higher stiffness for undesired modes and movements, although this has a small or negligible effect on the stiffness during a desired rotational movement about the axis of rotation 13.

[0103] Fig. 4C represents a suspension arrangement 30C similar to that in Fig. The suspension arrangement 30A shown in Figure 4A is identical, except that the angled inner support beams 33 are arranged asymmetrically with respect to the central support beam 31 and the axis of rotation 13. Here, the connection points 35a, 35b, 35c, and 35d are nested along the direction of the axis of rotation 13 such that they are located at different lateral distances from the mirror frame 40 (or the mirror body 20) along the axis of rotation 13. Similarly, the connection points 36, 36b, 36c, and 36d are nested and located at different lateral distances from the mirror frame 40 (or the mirror body 20) along the axis of rotation 13. Here, stiffness with respect to rotation about the desired axis is similar in both symmetrical and asymmetrical cases, whereas stiffness for undesired modes and undesired movements is adapted or fine-tuned by varying the symmetry or asymmetry (e.g.for higher mode frequencies).

[0104] Fig. 4D represents a suspension arrangement 30D comprising orthogonal inner support beams 33, where orthogonal means orthogonal to the central support beam 31 and the axis of rotation 13. The orthogonal inner support beams 33 are arranged symmetrically with respect to the central support beam 31 and the axis of rotation 13 such that each pair of orthogonal inner support beams 33 is symmetrically connected to the central support beam 31 at their connection points 35 and symmetrically connected to their corresponding outer support beams 32 at their connection points 36. In this case, all connection points 35 and 36 of a pair of orthogonal inner support beams 33 have the same lateral distance from the mirror frame 40 (or the mirror body 20). Together, the inner support beams 33 form a spring-like network.

[0105] It is understood that the orthogonal inner support beams 33 are aligned with respect to the central support beam 31 and the axis of rotation 13 in Fig. 4C in a similar way to in Fig. 4C shown, can be arranged asymmetrically, so that the connection points 35 are offset along the axis of rotation 13.

[0106] Fig. 4E represents a suspension arrangement 30E comprising orthogonal inner support beams 33 and inclined outer support beams 32. As described similarly with reference to suspension arrangement 30D, the orthogonal inner support beams 33 are arranged symmetrically with respect to the central support beam 31 and the axis of rotation 13. However, in suspension arrangements 30A-30D, the outer support beams 32 extend parallel to the axis of rotation 13 and the central support beam 31. In the case of suspension arrangement 30E, the inclined outer support beams 32 extend at an oblique angle that is neither parallel nor perpendicular to the axis of rotation 13. In this case, both outer support beams 32 have two ends 32a and 32b, with a lateral distance between the central support beam 31 and the end 32b being less than a lateral distance between the central support beam 31 and the end 32a.Accordingly, the length of the inclined outer support beams 32 increases as they move further away from the mirror body 20 and closer to the mirror frame 40. Having the outer support beams at an angle allows the length of the inner support beams to be adjusted independently. This can be useful for adjusting the stiffness / stress for each beam independently. This principle can also be applied to designs in the [reference to be added]. Fig. 4B and Fig. The arrangements shown in 4C can be applied.

[0107] It is understood that the orthogonal inner support beams 33 are aligned with respect to the central support beam 31 and the axis of rotation 13 in Fig. 4C in a similar way to in Fig. 4C shown, can be arranged asymmetrically, so that the connection points 35 are offset along the axis of rotation 13.

[0108] Fig. Figure 4F represents a suspension arrangement 30F, which is similar to the suspension arrangement 30A, but shows a more detailed implementation of the mirror body interface 30b (i.e., the mirror support structure). The mirror body interface 30b has a central section 37 that is directly coupled to the mirror body 20. The dimension of this central section 37 perpendicular to the axis of rotation 13 is greater than the width of the central support beam 31 in the same direction (i.e., in the X-direction), while their respective thicknesses in the Z-direction can be equal. The remaining section of the mirror body surface 30b comprises a support structure 38 that extends longitudinally in a direction perpendicular to the axis of rotation 13 (e.g., the support structure 38 extends longitudinally in the X-direction). Each opposite end of the support structure is coupled to one of the outer support beams 32.The outer support beams 32 are designed as lever arms extending from the mirror body interface 30b and connected to the central support 31 via the inner support beams 33. The structure of the mirror body interface 30b, as shown, can be applied to any of the embodiments described herein.

[0109] Fig. 4G represents another suspension arrangement 30G implemented in a MEMS device according to one or more embodiments. The suspension arrangement 30G is similar to the suspension arrangement 30A, except that, firstly, the central support beam 31 is directly coupled and integrated with the mirror frame 40 at the frame interface 30a, and secondly, it includes an additional series of outer support beams 42 and inner support beams 43 (i.e., 43a-43d) that define additional cavities 44 (i.e., 44a-44d).

[0110] The additional outer support beams 42 are arranged symmetrically on opposite sides of the central support beam 31 at a greater distance than the outer support beams 32. The additional outer support beams 42 extend longitudinally from the mirror body interface 30b parallel to the axis of rotation 13 and extend partially towards the frame 40. Thus, the additional outer support beams 42 are designed as lever arms extending from the mirror body interface 30b and connected to their respective additional outer support beams 42 via their respective additional inner support beams 43. The length of the additional outer support beams 42 (i.e., their longitudinal dimension) in the direction parallel to the axis of rotation 13 can be less than the length of the outer support beams 32, as shown. Alternatively, the length of the additional outer support beams 42 can be equal to or greater than the length of the outer support beams 32.

[0111] Changing the length of the additional outer support beams 42 can allow the additional inner support beams 43 to be angled either towards the mirror body 20, angled away from the mirror body 20, or to extend orthogonally to the axis of rotation (i.e., orthogonally to the central support beam 31, the outer support beams 32, and the additional outer support beams 42).

[0112] The additional inner support beams 43 couple the additional outer support beam 42 to their respective outer support beams 32 and indirectly couple the additional outer support beam 42 to the central support beam 31. Thus, the additional outer support beams 42 oscillate into and out of the suspension arrangement recess 43 like the outer support beams 32 when the mirror body 20 oscillates.

[0113] It is noted that the additional outer support beams 42 and the additional inner support beams 43 can be configured and have properties according to any of the arrangements provided herein with respect to the outer support beams 32 and the inner support beams 33. Thus, the additional inner support beams 43a and 43c can be symmetrical or asymmetrical, with the additional inner support beams 43b and 43d. Additionally, the additional inner support beams 43 can be angled away from the mirror body 20, while the inner support beams 33 can be angled towards the mirror body 20, or vice versa. Furthermore, although the additional outer support beams 42 are shown to be parallel to the axis of rotation 13, they can instead extend obliquely, as similarly shown in Fig. 4E described with regard to the outer support beams 32.

[0114] The additional internal support beams 43 can be used to fine-tune the torsional stiffness about the target axis 13 by adjusting their thickness or number. These additional internal support beams further increase the stiffness against the undesired translational and rotational modes and enable good mode separation, with the operating frequency of the first mode about the rotational axis 13 then being much lower than all other undesired modes.

[0115] Fig. 4H represents another suspension arrangement 30H implemented in a MEMS device according to one or more embodiments. The suspension arrangement 30H is similar to the suspension arrangement 30A, except that the arrangement is inverted. Thus, the outer support beams 32 extend partially from the frame 40 (i.e., from the frame interface 30a) toward the mirror body 20, and the inner support beams 33 are angled toward the frame 40 (i.e., angled away from the mirror body 20). Additionally, the central support beam 31 is directly coupled to and integrated with the mirror body 20 at the mirror body interface 30b.

[0116] It is pointed out that any of the variations that are in Fig. The 4B-4G components can also be inverted in a similar way. Therefore, the 30H suspension arrangement can be adapted to any of these variants.

[0117] According to the suspension arrangements 30A-30H, high stiffness for the desired rotational movement about the axis of rotation 13 is achieved by correctly dimensioning the central support beam 31. Additionally, internal support beams, including further internal support beams, provide Fig. 4G, a smaller contribution to the stiffness with respect to the rotational movement about the rotational axis 13, which allows a separate design tuning (geometry and number of springs) for an optimization of mechanical stress, mode separation (stiffness) and nonlinearity of the MEMS mirror 12 (i.e. the oscillation frequency of the mirror increases nonlinearly with an increase in the oscillation amplitude (i.e. the deflection angle amplitude θ)).

[0118] Stiffness and tension can be adjusted by modifying the dimensions and geometry of the central support beam 31, the outer support beams 32, and the inner support beams 33. A suitable design of the central support beam 31 also allows for tuning the suspension system nonlinearity (the nonlinear relationship between applied force and the resulting mechanical tilt angle). A nonlinear spring system can be advantageous in some applications where the angle can be controlled by adjusting the frequency.

[0119] In addition, the 30A-30H suspension arrangements have a compact structure and do not require a thin torsion bar, which in some cases can impair reliability.

[0120] Although the embodiments described herein relate to a MEMS device with a mirror, it should be noted that other implementations may include optical devices other than MEMS mirror devices, including other nonlinear, oscillating structures, including those not related to LIDAR. It is obvious to the person skilled in the art that other components performing the same functions may be appropriately employed. It should be noted that other embodiments may be used and structural or logical modifications may be made without departing from the scope of protection of this disclosure. It should be mentioned that features described with reference to a particular figure may be combined with features of other figures, even those not explicitly mentioned.Such modifications of the general concept according to the invention are to be covered by the attached claims and their legal equivalents.

[0121] Furthermore, the following claims are hereby included in the detailed description, where each claim may stand alone as a separate exemplary embodiment. While each claim may stand alone as a separate exemplary embodiment, it should be noted that—although a dependent claim may refer in the claims to a specific combination with one or more other claims—other exemplary examples may also include a combination of the dependent claim with the subject matter of any other dependent or independent claim. Such combinations are proposed herein unless it is stated that a particular combination is not intended. Furthermore, features of a claim for any other independent claim are also to be included, even if that claim is not directly dependent on the independent claim.

[0122] Additionally, although some aspects have been described in the context of a device, it is evident that these aspects also represent a description of the corresponding process, wherein a block or device corresponds to a process step or a feature of a process step. Analogously, aspects described in the context of a process step also represent a description of a corresponding block, element, or feature of a corresponding device. For example, the techniques described in this disclosure can be implemented, at least partially, in hardware, software, firmware, or any combination thereof, comprising any combination of a computing system, an integrated circuit, and a computer program on a non-volatile, computer-readable recording medium.For example, various aspects of the described techniques can be implemented within one or more processors, comprising one or more microprocessors, DSPs, ASICs, or any other equivalent integrated or discrete logic circuit arrangement, as well as any combinations of such components.

[0123] Furthermore, it is understood that the disclosure of several steps or functions disclosed in the description or claims should not be interpreted as being in a specific order. Therefore, the disclosure of several steps or functions does not restrict them to a specific order unless these steps or functions are not interchangeable for technical reasons. Furthermore, in some embodiments, a single step may comprise several sub-steps or may be divided into several sub-steps. Such sub-steps may be included and form part of the disclosure of that single step unless they are explicitly excluded.

[0124] Exemplary embodiment 1 is a microelectromechanical system (MEMS) device comprising an oscillator structure configured to oscillate about an axis of rotation; a frame that is rotationally fixed, the frame comprising a frame recess within which the oscillator structure is suspended; and a suspension arrangement that is mechanically coupled to and between the oscillator structure and the frame, wherein the suspension arrangement is configured to suspend the oscillator structure within the frame recess, the suspension arrangement comprising a central support beam extending longitudinally along the axis of rotation, the central support beam being mechanically coupled to and between the oscillator structure and the frame; and a first outer support beam that is mechanically coupled to the oscillator structure and offset laterally from the central support beam in a first direction orthogonal to the axis of rotation.at least one first inner support beam directly coupled to and between the central support beam and the first outer support beam; a second outer support beam mechanically coupled to the oscillator structure and offset laterally from the central support beam in a second direction orthogonal to the axis of rotation, the second direction being opposite to the first direction; and at least one second inner support beam directly coupled to and between the central support beam and the second outer support beam.

[0125] In embodiment 2, in the component according to embodiment 1, the oscillator structure, the frame and the suspension arrangement form a one-piece integral construction made of a semiconductor material.

[0126] In embodiment 3, in the component according to embodiment 2, the oscillator structure, the frame and the suspension arrangement jointly use a common main surface.

[0127] In embodiment 4, in the component according to one of embodiments 1 to 3, the suspension arrangement further comprises an oscillator structure interface that mechanically couples the central support beam, the first outer support beam and the second outer support beam to the oscillator structure.

[0128] In embodiment 5, in the component according to embodiment 4, the first outer support beam and the second outer support beam both extend from the oscillator structure interface partially in the direction of the frame parallel to the axis of rotation.

[0129] In embodiment 6, in the component according to embodiment 4 or 5, the first outer support beam and the second outer support beam both extend obliquely from the oscillator structure interface partially towards the frame.

[0130] In embodiment 7, in the component according to one of embodiments 1 to 6, each of the at least one first inner support beam extends obliquely from the central support beam to the first outer support beam, and each of the at least one second inner support beam extends obliquely from the central support beam to the second outer support beam.

[0131] In embodiment 8, in the component according to embodiment 7, each of the at least one first inner support beam has a first connection point with the central support beam and a second connection point with the first outer support beam, wherein each first connection point has a first corresponding lateral distance from the frame and each second connection point has a second corresponding lateral distance from the frame that is greater than the first corresponding lateral distance, and each of the at least one second inner support beam has a third connection point with the central support beam and a fourth connection point with the second outer support beam, wherein each third connection point has a third corresponding lateral distance from the frame, and each fourth connection point has a fourth corresponding lateral distance from the frame.which is greater than the third corresponding lateral distance.

[0132] In embodiment 9, in the component according to embodiment 7 or 8, the at least one first inner support beam is symmetrical to the at least one second inner support beam about the axis of rotation.

[0133] In embodiment 10, in the component according to embodiment 9, each of the at least one first inner support beam is aligned with a different one of the at least one second inner support beam to form an inner support beam, with each inner support beam pair forming a V-shape.

[0134] In embodiment 11, in the component according to one of embodiments 7 to 10, the at least one first inner support beam is asymmetrical to the at least one second inner support beam about the axis of rotation.

[0135] In embodiment 12, in the component according to one of embodiments 1 to 11, each of the at least one first inner support beam extends orthogonally from the central support beam to the first outer support beam in the first direction, and each of the at least one second inner support beam extends orthogonally from the central support beam to the second outer support beam in the second direction.

[0136] In embodiment 13, in the component according to embodiment 12, the at least one first inner support beam is symmetrical to the at least one second inner support beam about the axis of rotation.

[0137] In embodiment 14, in the component according to embodiment 12 or 13, the at least one first inner support beam is asymmetrical to the at least one second inner support beam about the axis of rotation.

[0138] In embodiment 15, in the component according to one of embodiments 1 to 14, the central support beam, the first outer support beam and the at least one first inner support beam define at least one first cavity between them, and the central support beam, the second outer support beam and the at least one second inner support beam define at least one second cavity between them.

[0139] In embodiment 16, in the component according to one of embodiments 1 to 15, the at least one first inner support beam comprises a plurality of first inner support beams, each being directly coupled to and between the central support beam and the first outer support beam, and the at least one second inner support beam comprises a plurality of second inner support beams, each being directly coupled to and between the central support beam and the second outer support beam.

[0140] In embodiment 17, in the component according to any one of embodiments 1 to 16, the MEMS component further comprises a driver configured to drive an oscillation of the oscillator structure about the axis of rotation, wherein the oscillator structure comprises a main surface having a dimension of at least 5 millimeters, the main surface being arranged opposite the frame recess, and wherein the suspension arrangement enables the driver to drive the oscillation at a resonant frequency of at least 2 kHz with a maximum deflection angle of at least 10°, while limiting a mechanical stress level of the central support beam to 3 GPa or less.

[0141] In embodiment 18, in the component according to embodiment 17, the dimension is a diameter or a length of the main surface of the oscillator structure.

[0142] In embodiment 19, in the component according to any one of embodiments 1 to 18, the MEMS component further comprises a driver configured to drive an oscillation of the oscillator structure about the axis of rotation, wherein the oscillator structure comprises a main surface having a dimension of at least 5 millimeters, the main surface being arranged opposite the frame recess, and wherein the central support beam has a thickness dimension and a width dimension providing a rotational stiffness in a direction of rotation of the oscillation about the axis of rotation sufficient to enable the driver to drive the oscillation at a resonant frequency of at least 2 kHz with a maximum deflection angle of at least 10°, while limiting a mechanical stress level of the central support beam to 3 GPa or less.

[0143] In embodiment 20, in the component according to one of embodiments 1 to 19, the MEMS component further comprises: a driver configured to drive an oscillation of the oscillator structure about the axis of rotation, wherein the oscillator structure comprises a main surface having a dimension of at least 5 millimeters, the main surface being arranged opposite the frame recess, and wherein the central support beam has a thickness dimension and a width dimension providing a rotational stiffness in a direction of rotation of the oscillation about the axis of rotation sufficient to enable the driver to drive the oscillation at a resonant frequency of at least 2 kHz with a maximum deflection angle of at least 10°, while limiting a mechanical stress level of the central support beam to 2 GPa or less.

[0144] In embodiment 21, in the component according to one of embodiments 1 to 20, the suspension arrangement further comprises a frame structure interface that mechanically couples the central support beam, the first outer support beam and the second outer support beam to the frame.

[0145] In embodiment 22, in the component according to embodiment 21, the first outer support beam and the second outer support beam both extend from the frame structure interface partially in the direction of the oscillator structure parallel to the axis of rotation.

[0146] In embodiment 23, in the component according to embodiment 21 or 22, the first outer support beam and the second outer support beam both extend obliquely from the frame structure interface partially towards the oscillator structure.

[0147] In embodiment 24, in the component according to one of embodiments 1 to 23, the suspension arrangement further comprises a first additional outer support beam which is mechanically coupled to the oscillator structure and is laterally offset from the central support beam and from the first outer support beam in the first direction, wherein the first additional outer support beam is further spaced apart from the central support beam as the first outer support beam in the first direction; at least one first additional inner support beam which is directly coupled to and between the first additional outer support beam and the first outer support beam;a second additional outer support beam, which is mechanically coupled to the oscillator structure and offset laterally from the central support beam and from the second outer support beam in the second direction, wherein the second additional outer support beam is further spaced from the central support beam as well as from the second outer support beam in the second direction; and at least one second additional inner support beam, which is directly coupled to and between the second additional outer support beam and the second outer support beam.

[0148] Exemplary embodiment 25 is an oscillator system comprising an oscillator structure configured to oscillate about a rotational axis at a resonant frequency of at least 2 kHz with a maximum displacement angle of at least 10°, wherein the oscillator structure has a main surface having a dimension of at least 5 millimeters; a frame that is rotationally fixed, the frame comprising a frame recess within which the oscillator structure is suspended;and a suspension arrangement mechanically coupled to and between the oscillator structure and the frame, wherein the suspension arrangement is configured to suspend the oscillator structure within the frame recess, the suspension arrangement comprising: a central support beam extending longitudinally along the axis of rotation, wherein the central support beam is mechanically coupled to and between the oscillator structure and the frame, wherein the central support beam wraps around the axis of rotation when the oscillator structure oscillates, and exhibits a mechanical stress level of 3 GPa or less while the oscillator structure oscillates around the axis of rotation at the resonant frequency of at least 2 kHz with the maximum displacement angle of at least 10°;a first outer support beam mechanically coupled to the oscillator structure and offset laterally from the central support beam in a first direction orthogonal to the axis of rotation; at least a first inner support beam directly coupled to and between the central support beam and the first outer support beam; a second outer support beam mechanically coupled to the oscillator structure and offset laterally from the central support beam in a second direction orthogonal to the axis of rotation, the second direction being opposite to the first direction; and at least a second inner support beam directly coupled to and between the central support beam and the second outer support beam.

[0149] In embodiment 26, in the system according to embodiment 25, the oscillator structure is a microelectromechanical system (MEMS) mirror and the main surface is a reflective surface.

[0150] In embodiment 27, in the system according to embodiment 25 or 26, the central support beam wraps around the axis of rotation when the oscillator structure oscillates and has a mechanical stress level of 2 GPa or less, while the oscillator structure oscillates around the axis of rotation at a resonant frequency of at least 2 kHz with a maximum deflection angle of at least 10°.

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