Microelectromechanical mirror, method for manufacturing a microelectromechanical mirror, method for operating a microelectromechanical mirror, projection device, and use of a microelectromechanical mirror

Abstract

A microelectromechanical microscope (1) includes: a mirror element (2) and at least one adjustment element (7) designed to adjust at least one resonant frequency of the mirror element (2). Furthermore, a method for manufacturing a microelectromechanical microscope, a method for operating a microelectromechanical microscope, a projection device, and an application of a microelectromechanical microscope are also provided.

Description

Micro-electromechanical microscope, method for manufacturing micro-electromechanical microscope, method for operating micro-electromechanical microscope, projection device, and use of micro-electromechanical microscope The present invention provides a micro-electromechanical mirror, a method for manufacturing the micro-electromechanical mirror, an operating method for the micro-electromechanical mirror, a projection device and uses of the micro-electromechanical mirror. MEMS mirrors are used, for example, in laser projectors to precisely deflect laser beams in order to display static or dynamic images. For example, laser projectors are used in the automotive sector to project information onto the road, in HUD (head-up display) systems for matrix lighting, or in LIDAR applications (light detection and ranging). These applications particularly require a high depth of field, which laser projectors can provide. Laser projectors are also used as hologram projectors, VR glasses (virtual reality) or AR glasses (augmented reality). Here, the deflected laser beam is coupled into a waveguide lens. The direction of the laser beam, not its position, determines the position of the image point for the observer, so no additional optical elements are required. Impact-resistant and cost-effective laser projectors offer advantages, particularly in the automotive sector and in mobile applications such as VR or AR glasses. For example, a laser projector features a microelectromechanical mirror that rotates in two directions and deflects a time-modulated laser beam to create an image in the far field. The projected image always remains in focus for the viewer, without requiring one eye to adjust. At least one object of certain embodiments is to provide a microelectromechanical mirror whose vibration characteristics can be adjusted, in particular during operation or at the end of the manufacturing process. At least one further object of certain embodiments is to provide a method for manufacturing such a microelectromechanical mirror. At least one further object of certain embodiments is to provide a method for operating such a microelectromechanical mirror. At least one further object of certain embodiments is to provide a projection device comprising such a microelectromechanical mirror. At least one further object of certain embodiments is to provide a use of such a microelectromechanical mirror. These objects are achieved by a microelectromechanical mirror, a method for producing a microelectromechanical mirror, a method for operating a microelectromechanical mirror, a projection device, and a use of a microelectromechanical mirror according to the independent claims. Optimized embodiments and developments of the microelectromechanical mirror, the method for producing a microelectromechanical mirror, the method for operating a microelectromechanical mirror, the projection device, and the use of a microelectromechanical mirror are described in the dependent claims and further illustrated in the following description and figures. According to at least one embodiment, a microelectromechanical mirror comprises a mirror element. In particular, the mirror element has a main extension plane. For example, when the main extension plane is viewed from above, the mirror element has a circular, elliptical, oval, square, rectangular, or polygonal shape. The mirror element includes a substrate with a reflective layer. For example, the substrate is made of silicon, diamond, cubic boron nitride (BN), silicon nitride (SiN), or boron, or consists of at least one of these materials. For example, the reflective layer includes or consists of a metal. In particular, the reflective layer system is designed to at least partially reflect and / or redirect electromagnetic radiation between the infrared and ultraviolet ranges. For example, the reflective layer may have a reflectivity of at least 90% or at least 99% for electromagnetic radiation between the infrared and ultraviolet ranges. In particular, the reflective layer system extends in a plane that corresponds to or is parallel to the main extension plane of the mirror element. Here and hereinafter, the main extension plane is defined relative to the rest position of the mirror element. In particular, the mirror element is movably mounted. For example, the mirror element can be at least partially rotated about at least two rotation axes. For example, the two rotation axes are perpendicular to each other. For example, during operation of the microelectromechanical mirror, the mirror element performs rotational vibrations about each of the at least two rotation axes. In particular, for each rotational vibration, the mirror element has a corresponding resonant frequency. According to at least one further embodiment, the micro-electromechanical mirror has at least one adjustment element configured to adjust at least one resonant frequency of the mirror element. For example, the rotational vibration of the mirror element around a first rotation axis has a first resonant frequency. For example, the rotational vibration of the mirror element around a second rotation axis has a second resonant frequency. In particular, the first resonant frequency and / or the second resonant frequency correspond to the resonant frequencies of different vibration modes of the mirror element. For example, these vibration modes are resonantly excited during operation. Preferably, the first resonant frequency and the second resonant frequency are different from each other. The adjustment element is configured, for example, to adjust or set the first resonant frequency and / or the second resonant frequency. For example, the adjustment element is configured to adjust the frequency ratio between the first resonant frequency and the second resonant frequency. For example, the first resonant frequency and / or the second resonant frequency can be increased or decreased by up to 1% or up to 10% via the adjustment element. Adjusting the frequency ratio can, for example, alter the refresh rate and / or image resolution of images generated during operation of the micro-electromechanical mirror. For example, the adjustment element can independently adjust the moments of inertia of the mirror elements about their respective rotation axes. As an alternative or additional measure, the adjustment element can, for example, adjust the stiffness of a spring element by which the mirror elements are suspended and / or mounted. Thus, the adjustment element can adjust at least one resonant frequency and / or the resonant frequency ratio of the vibration modes of the mirror elements. For example, these resonant frequencies lie in the range of 0.5 kHz to 100 kHz (inclusive). According to a preferred embodiment, the micro-electromechanical mirror comprises: - mirror elements, and - At least one tuning element for tuning at least one resonant frequency of the mirror element. The basic concept of the MEMS mirror described herein is the ability to adjust the resonant frequency of at least one vibration mode of the mirror element, at least within a certain range, particularly during operation and / or at the end of the manufacturing process. For example, the MEMS mirror is designed for image projection using Lissajous scanning. In this process, a laser beam is deflected during operation of the MEMS mirror so that it creates a Lissajous pattern on the projection surface. By temporally modulating the laser beam and combining it with Lissajous scanning, an image can be generated on the projection surface. In the Lissajous scanning method, the density of the scanning pattern and the image refresh rate are particularly sensitive to the resonant frequency of the mirror element. The resonant frequency can, for example, be decomposed into the product of the image refresh rate and the number of vibration periods of the scanning pattern. The image refresh rate is determined in particular by the greatest common divisor of the resonant frequencies of the two orthogonal rotation axes. For example, Lissajous patterns with high image refresh rates have fewer vibrations, which at the same time limits the achievable image resolution and / or image quality, and vice versa. For example, a frequency pair with resonant frequencies of 27 kHz and 5.5 kHz for the rotation axes would result in an image refresh rate of approximately 1 kHz, but an image resolution of only approximately 27×5.5 pixels. In contrast, a 10 Hz increase in the slow axis frequency would result in an image refresh rate of 30 Hz and an image resolution of 900×167 pixels. Due to the high mechanical quality factor, the vibration mode resonances of the mirror elements have a low bandwidth, for example, only a few hertz. Therefore, the choice of operating frequency, i.e., the resonant frequency of the mirror elements, is particularly limited at large fields of view (FOV). The MEMS mirror described in this article allows for adjustment of the resonant frequency ratio, thus enabling targeted setting of the image refresh rate and image resolution without restricting the FOV. Furthermore, the resonant frequency ratio can be fine-tuned during the operation of the MEMS mirror, thereby extending its service life. The resonant frequency of the mirror element may be affected by the temperature of the MEMS mirror, the precision of the MEMS mirror manufacturing process, the deposition of dust particles on the mirror element, the surrounding medium of the mirror element, aging effects of the MEMS mirror, the influence of the ambient air pressure, and / or the installation of the MEMS mirror. For example, by adjusting at least one resonant frequency of the mirror element using an adjustment element at the end of the manufacturing process and / or during operation of the MEMS mirror, optimal image quality can be achieved while maintaining a constant maximum deflection angle of the mirror element. According to at least one further embodiment, the microelectromechanical mirror includes a drive element that surrounds the mirror element and is connected to the mirror element via a first spring element. For example, the mirror element is connected to the drive element via two first spring elements. For example, the drive element is a piezoelectric drive ring. The mirror element is preferably located in the center of the drive element. In particular, in the static state, the drive element completely surrounds the main extension plane of the mirror element. The drive element is particularly designed to deflect the mirror element from its rest position during operation of the micro-electromechanical mirror. In this case, the mirror element is preferably twisted relative to the drive element. For example, mechanical stresses generated in the drive element transmit bending and / or torque moments to the mirror element via the first spring element. The drive element comprises, for example, a substrate on which a piezoelectric layer is applied at least in certain areas. The substrate is made, for example, of silicon, diamond, cubic boron nitride (BN), silicon nitride (SiN), or boron, or consists of at least one of these materials. The piezoelectric layer is preferably arranged parallel to the main extension plane of the mirror element. The piezoelectric layer is, for example, located between the first electrode and the second electrode. The piezoelectric layer may comprise one or more piezoelectric materials. For example, the piezoelectric layer comprises a piezoelectric material such as lead zirconate titanate (PZT), aluminum nitride (AlN), or bismuth barium ferrite titanate (BFO-BT), or consists of one of these materials. By applying a voltage to the electrodes, the piezoelectric layer generates mechanical stresses in the drive element. These mechanical stresses are used to excite vibration modes of the mirror element during operation of the microelectromechanical mirror, thereby causing the mirror element to deviate from its rest position. According to at least one further embodiment, the microelectromechanical mirror comprises a frame that is connected to the drive element via second spring elements. For example, the frame is connected to the drive element via two second spring elements. The frame completely surrounds the drive element in the main extension plane of the mirror element. The frame particularly comprises a substrate that may be made of silicon, diamond, cubic boron nitride (BN), silicon nitride (SiN), or boron, or consist of one of these materials. According to at least one further embodiment of the micro-electromechanical mirror, at least one spring element is designed as a torsion spring element. For example, the first spring element and / or the second spring element are each designed as a torsion spring element. Features of the torsion spring elements are described below. Features of at least one or all of the torsion spring elements may apply to at least one or all of the spring elements. The torsion spring element particularly comprises or consists of a torsion beam. For example, the torsion spring element comprises a substrate that may be made of silicon, diamond, cubic boron nitride (BN), silicon nitride (SiN), or boron, or consist of one of these materials. The torsion spring element has an elongated beam-like shape and a rotational axis that particularly corresponds to the longitudinal direction of the torsion spring element. During operation, a torsional torque acts on the torsion spring element relative to the rotational axis, causing the torsion spring element to twist about its rotational axis. In this case, a restoring torsional torque is particularly generated in the torsion spring element. The rotational axes of the first spring elements are preferably aligned with a common first rotational axis. In other words, the first spring elements have a common first rotational axis about which they rotate during operation. In particular, the mirror element can rotate about the first rotational axis relative to the drive element within at least a first angular range. For example, two first spring elements may be positioned on opposite sides of the mirror element. The rotational axes of the second spring elements are preferably aligned with a common second rotational axis. In other words, the second spring elements have a common second rotational axis about which they rotate during operation. For example, the drive element and the mirror element can rotate relative to the frame about the second rotational axis within at least a second angular range. For example, the two second spring elements are positioned on opposite sides of the drive element. The second rotation axis is arranged, for example, transversely or orthogonally to the first rotation axis. In the case where the piezoelectric drive ring and the mirror element are connected by a torsional suspension as described in detail below, the first rotation axis and the second rotation axis can optionally be the same or parallel to each other. For example, the electrodes of the driver element have different independent control regions. The rotation axis of each mirror element is associated with a different control region. By applying voltage to the corresponding control region, the mirror element can be independently excited to rotate and vibrate around the corresponding rotation axis. The mirror element, drive element, frame, first spring element, and second spring element are, for example, integrally formed components. In other words, the mirror element, drive element, frame, and first and second spring elements are integrally formed or formed from a common substrate. For example, the substrate is a single crystal. During the manufacture of the micro-electromechanical mirror, the common substrate structure allows the structures of the aforementioned components to be formed within the common substrate. According to at least one further embodiment of the micro-electromechanical mirror, a torsional suspension is provided between the drive element and the mirror element, the suspension surrounding the mirror element. The torsional suspension is directly connected to the drive element via a first spring element and directly connected to the mirror element via a third spring element. For example, the torsional suspension is connected to the mirror element via two third spring elements. The third spring elements are each designed as a torsional spring element in the manner described above. The rotation axes of the third spring elements are preferably aligned along a common third rotation axis. In other words, the third spring elements have a common third rotation axis about which they are twisted during operation. For example, the mirror element can rotate about the third rotation axis relative to the drive element within at least a third angle. For example, two third spring elements can be positioned on opposite sides of the mirror element. In particular, the third rotation axis is aligned transversely or perpendicularly to the first rotation axis, while the second rotation axis is, for example, parallel to or co-ordinate with the first rotation axis. According to at least one further embodiment of the micro-electromechanical mirror, the drive element or the torsion suspension has an elongated shape with a major axis and a minor axis perpendicular to the major axis. In particular, the drive element or the torsion suspension is elliptical. For example, the diameter of the drive element or the torsion suspension in the direction of the major axis is at least 5%, preferably at least 20%, and particularly preferably at least 40% larger than the diameter in the direction of the minor axis. For example, the long axis of the drive element is parallel to the first rotation axis and / or perpendicular to the second rotation axis. For example, the long axis of the torsional suspension is parallel to the third rotation axis and / or perpendicular to the first rotation axis. Due to the elongated shape of the drive element or the torsional suspension, the mirror element advantageously executes a rotational vibration mode with particularly low anharmonicity in the long axis direction. According to at least one further embodiment of the micro-electromechanical mirror, the adjustment element comprises a structure on the rear side of the mirror element. In particular, the rear side of the mirror element is the side opposite the reflective layer. In other words, the rear side is opposite the front side of the mirror element, which is designed to reflect light during the intended operation of the micro-electromechanical mirror. For example, this structure ensures that the thickness of the substrate of the mirror element along the main extension plane does not remain constant, while the reflective layer has a flat surface. In this context, thickness specifically refers to the spatial extension of the substrate in a direction perpendicular to the main extension plane of the mirror element. For example, the structure has a cross structure arranged parallel to the rotation axis of the mirror element. For example, the structure is designed to vary the mass distribution of the mirror element relative to the mirror element's axis of rotation. In particular, the structure on the back side allows individual elements of the mirror element's moment of inertia tensor to be adjusted independently. Here, the elements of the inertia tensor, for example, determine the moment of inertia of the mirror element relative to different axes of rotation. For example, by adjusting the moment of inertia of the mirror element, its resonant frequency can be adjusted. For example, the structure allows the resonant frequency of the mirror element to be specifically adjusted during the manufacturing process. For example, arranging the structure on the back side of the mirror element can compensate for manufacturing tolerances in the resonant frequency of the mirror element. According to at least one further embodiment of the MEMS mirror, the structure is further configured to mechanically reinforce the mirror element. For example, the structuring reduces or prevents deformation of the mirror element surface during rotational vibration of the mirror element about at least one rotation axis. This advantageously reduces or prevents distortion of the projected image caused by deformation of the mirror element during operation of the MEMS mirror. According to at least one further embodiment of the micro-electromechanical mirror, the structure is arranged along at least one rotation axis of the mirror element. For example, by adding or removing material from the mirror element along a rotation axis, the moment of inertia of the mirror element relative to that rotation axis remains largely unchanged, while the moment of inertia and, therefore, the resonant frequency relative to an orthogonal axis may change. This advantageously allows the resonant frequencies of the mirror element to be adjusted independently of one another relative to different rotation axes. According to at least one further embodiment of the MEMS mirror, the tuning element comprises at least one substrate element that partially surrounds the mirror element and is directly connected to the mirror element via a predetermined breaking point. This predetermined breaking point allows the substrate element, or a portion thereof, to be easily removed after the MEMS mirror is manufactured, thereby allowing for simple adjustment of the mirror element's moment of inertia and, therefore, at least one resonant frequency. For example, the substrate element may have a well-defined mass. According to at least one further embodiment of the MEMS mirror, the adjustment element is designed to adjust at least one resonant frequency during a predetermined operation period of the MEMS mirror. This advantageously allows the image refresh rate and / or image resolution to be adjusted or adapted without limiting the maximum deflection of the mirror element. In particular, by adjusting at least one resonant frequency during the predetermined operation period, it is possible to compensate for the influence of environmental parameters on the resonant frequency, such as ambient temperature, as well as aging effects. According to at least one further embodiment, the micro-electromechanical mirror further comprises a carrier, wherein the frame is arranged on the carrier. The carrier comprises metal or is made of metal, in particular copper or aluminum, for example. According to at least one further embodiment of the MEMS mirror, the coefficient of thermal expansion of the carrier and the coefficient of thermal expansion of the frame differ from each other. Due to the different coefficients of thermal expansion, changes in the temperature of the MEMS mirror can induce mechanical stresses in the structure of the MEMS mirror. These mechanical stresses alter the restoring force of the spring element. Consequently, by changing the temperature, at least one resonant frequency of the mirror element can be adjusted. According to at least one further embodiment of the microelectromechanical mirror, the adjustment element comprises a heating element and / or a cooling element, which is arranged on the frame or the carrier. For example, the heating element comprises a temperature-dependent resistor, a heating wire, a heating coil, or a wire with a resistor directly attached to the frame or the carrier. The cooling element comprises, for example, a Peltier element. The heating element is, for example, a galvanized meander heating structure. The temperature-dependent resistor is, for example, a raised electrode of a PTC resistor (positive temperature coefficient) in thin-film technology. During operation of the heating element and / or the cooling element, the temperature of the microelectromechanical mirror can in particular be adjusted. Furthermore, the microelectromechanical mirror may also comprise a temperature sensor. According to at least one further embodiment of the micro-electromechanical mirror, the tuning element includes a piezoelectric tuning element configured to change the stiffness of at least one spring element. For example, the piezoelectric tuning element is configured to change the stiffness of at least one first spring element, a second spring element, and / or a third spring element. For example, by applying a voltage to the piezoelectric tuning element, a mechanical stress can be generated, thereby changing the stiffness of at least one spring element and, in turn, the resonant frequency of the corresponding vibration mode. In particular, the piezoelectric tuning element comprises a piezoelectric layer, which may consist of PZT, AlN or BFO-BT, or one of these materials, and is arranged between two electrodes. The piezoelectric tuning element is not specifically designed to excite a vibration mode of the mirror element. According to at least one further embodiment of the micro-electromechanical mirror, the piezoelectric tuning element is arranged on the frame, for example, with the piezoelectric active surface of the piezoelectric tuning element being oriented perpendicularly to the rotation axis of the second spring element. According to at least one further embodiment of the microelectromechanical mirror, the adjustment element comprises an electrode configuration of the driving element, wherein the electrode configuration is designed to mechanically excite a lateral length mode of the piezoelectric layer of the driving element, and the lateral length mode is excited to adjust the resonant frequency of the mirror element. For example, in a driving element, longitudinal length modes of the piezoelectric layer, particularly the d33 mode, are excited to induce rotational vibrations in the mirror element. In the longitudinal length mode, the mechanical stress in the piezoelectric layer is typically parallel to the direction of the applied voltage. In contrast, in the transverse length modes, particularly the d31 mode, the mechanical stress is perpendicular to the direction of the applied voltage to the piezoelectric layer. For example, the transverse length modes can alter the stiffness of the spring element, thereby changing the resonant frequency of the mirror element. For example, this electrode configuration includes comb-shaped electrodes or interdigitated electrodes. According to at least one further embodiment of the micro-electromechanical mirror, the adjustment element comprises a sealed housing in which at least the mirror element is arranged, wherein the sealed housing is designed to adjust at least one resonant frequency by varying the internal air pressure. For example, at least the mirror element, the drive element, and the spring element are arranged in the sealed housing. By adjusting the air pressure, the air resistance, i.e., the resistance experienced by the mirror element along the rotation axis during rotational oscillation, can be set. For example, several tuning elements described herein can be combined in one microelectromechanical mirror to achieve a larger or particularly large change in at least one resonant frequency. According to at least one further embodiment of the microelectromechanical mirror, the adjustment element is designed to adjust a frequency ratio between a first resonant frequency of rotational vibrations of the mirror element about a first rotational axis and a second resonant frequency of rotational vibrations about a second rotational axis during predetermined operation of the microelectromechanical mirror. According to at least one further embodiment of the micro-electro-mechanical mirror, the micro-electro-mechanical mirror is configured to set the resonant frequency of the first vibration mode and / or the second vibration mode by adjusting an electrical DC component applied to the first control region and / or the second control region of the drive element. According to at least one further embodiment of the micro-electromechanical mirror, the micro-electromechanical mirror is configured to cause the mirror element to enter a first vibration mode by applying a first electrical alternating current signal having a first frequency to a first control region of the driving element, and to cause the mirror element to enter a second vibration mode by applying a second electrical alternating current signal having a second frequency to a second control region of the driving element. According to at least one further embodiment of the MEMS mirror, the MEMS mirror is configured to adjust the resonant frequency of the first vibration mode and / or the second vibration mode by adjusting the temperature of the MEMS mirror. The mirror element is designed to adjust its temperature by at least partially absorbing the laser radiation. Furthermore, a method for manufacturing a microelectromechanical mirror is described in detail. This method is particularly suitable for manufacturing the microelectromechanical mirror described herein. All features of the microelectromechanical mirror also correspond to the method for manufacturing the microelectromechanical mirror, and vice versa. According to at least one method for manufacturing a microelectromechanical mirror, a mirror element is formed. For example, a mirror element, a drive element surrounding the mirror element, a frame surrounding the drive element, a first spring element connecting the mirror element to the drive element, and a second spring element connecting the drive element to the frame are formed. For example, the structure of the mirror element, the drive element, the frame, and the spring element is formed by structuring (e.g., etching) a common substrate. In addition, a reflective layer is applied to specific areas of the substrate to form the mirror element, and a piezoelectric layer is applied between two metal electrode layers of the drive element. According to at least one further method for producing a microelectromechanical mirror, at least one resonance frequency of the mirror element is adjusted by means of at least one adjustment element. According to a preferred embodiment, the method for manufacturing a micro-electromechanical mirror comprises the following steps: - forming mirror elements, and - Adjusting at least one resonance frequency of the mirror element by means of at least one adjustment element. According to at least one further method for producing a microelectromechanical mirror, the tuning element comprises a structure on the rear side of the mirror element, and the tuning of at least one resonance frequency is achieved by applying or at least partially removing the structure. For example, material on the back substrate of the mirror element can be removed by laser cutting, laser ablation, plasma etching, or mechanical hard machining to independently adjust the moment of inertia of the mirror element about different rotational axes. Furthermore, additional material can be added to the back of the mirror element by printing, or the structure can be filled with conductive adhesive or resin (e.g., filled epoxy) to independently adjust the moment of inertia of the mirror element about different rotational axes. According to at least one further method for manufacturing a micro-electromechanical mirror, the tuning element includes at least one substrate element that surrounds the mirror element at least partially and is directly connected to the mirror element via predetermined breaking points, and adjustment of at least one resonant frequency is achieved by removing the substrate element. For example, the tuning element includes a plurality of substrate elements that surround the mirror element at different locations and are directly connected to the mirror element via predetermined breaking points. According to at least one further method for producing a microelectromechanical mirror, the tuning element comprises an electrode arrangement of a drive element, and the tuning of the resonance frequency of the mirror element is achieved by mechanically exciting a lateral length mode of a piezoelectric layer of the drive element by means of the electrode arrangement. According to at least one further manufacturing method of the micro-electromechanical mirror, the driving element includes a first control region and a second control region, and the resonant frequency of the first vibration mode and / or the second vibration mode of the mirror element is adjusted by adjusting the DC component applied to the first control region and / or the second control region. Furthermore, a method for operating a microelectromechanical mirror is described in detail. The method for operating a microelectromechanical mirror is specifically designed for operating the microelectromechanical mirror described herein. Features disclosed for the microelectromechanical mirror are also applicable to the method for operating a microelectromechanical mirror, and vice versa. According to at least one further method of operating a micro-electro-mechanical mirror, the micro-electro-mechanical mirror comprises a mirror element and at least one adjustment element, wherein: - the mirror element is set to the first vibration mode and the second vibration mode, and The tuning element is designed to tune the resonance frequency of the first vibration mode and / or the second vibration mode. According to at least one further method of operating the micro-electro-mechanical mirror, the micro-electro-mechanical mirror further comprises a drive element, wherein: - setting the mirror element to a first vibration mode by applying a first alternating current signal of a first frequency to a first control region of the driver element, and - Setting the mirror element to a second vibration mode by applying a second AC signal of a second frequency to a second control region of the driver element. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the first vibration mode comprises a rotation of the mirror element about a first rotation axis. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the second vibration mode comprises a rotation of the mirror element about a second rotation axis, which is orthogonal or transverse to the first rotation axis. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the first vibration mode and the second vibration mode are excited resonantly. In other words, the oscillation frequency of the mirror element about the respective rotation axis corresponds to the resonant frequency of the corresponding vibration mode. According to at least one further embodiment of the method for operating a microelectromechanical mirror, the adjustment element comprises a heating element and / or a cooling element, and the resonant frequency of the first vibration mode and / or the second vibration mode is adjusted by adjusting the temperature of the microelectromechanical mirror. In particular, the microelectromechanical mirror comprises a carrier and a frame having different coefficients of thermal expansion. Thus, mechanical stresses are induced in the microelectromechanical mirror by temperature changes, which can lead to changes in the resonant frequency of the first and / or second vibration mode. For example, a preheating phase can occur before a predetermined operation of the microelectromechanical mirror, during which the resonant frequency is adjusted to a predetermined target frequency. According to at least one further embodiment of the method for operating a MEMS mirror, the MEMS mirror can also be dehumidified by adjusting its temperature. For example, the MEMS mirror may have a housing with a viewing window. In a humid environment, condensation may form on the viewing window. By heating the MEMS mirror, the condensation can be at least partially or completely removed. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the micro-electromechanical mirror further includes at least one spring element, the adjustment element including a piezoelectric adjustment element, and the stiffness of the at least one spring element is adjusted by applying a voltage to the piezoelectric adjustment element, thereby adjusting the resonant frequency of the first vibration mode and / or the second vibration mode. The at least one spring element may be, for example, at least one of the first, second, and / or third spring elements described above. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the resonant frequency of the first vibration mode and / or the second vibration mode is adjusted by adjusting a DC voltage component applied to the first control region and / or the second control region. This DC voltage component generates a mechanical preload in the first, second, and / or third spring elements. This mechanical preload changes, for example, the resonant frequency of the first and / or second vibration mode. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the adjustment element comprises a sealed housing in which at least the mirror element is arranged, and at least one resonance frequency is adjusted by changing the internal gas pressure. The sealed housing is particularly airtight. According to at least one further embodiment of the method for operating a microelectromechanical mirror, the tuning element includes an electrode arrangement of a drive element, wherein the electrode arrangement is configured to mechanically excite transverse length modes of a piezoelectric layer of the drive element, and the excitation of these transverse length modes adjusts at least one resonant frequency of the mirror element. For example, the transverse length modes can be used to adjust the stiffness of the first, second, and / or third spring elements. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the resonant frequency of the first vibration mode and / or the second vibration mode is adjusted by adjusting the temperature of the micro-electromechanical mirror, wherein the temperature is adjusted by at least partial absorption of the laser radiation by the mirror element. For example, the reflectivity of the mirror element and / or the power of the laser beam directed at the mirror element is adjusted such that a desired heating power is achieved by partial absorption of the laser radiation. According to at least one further embodiment of the method for operating a micro-electromechanical mirror, the frequency ratio between a first resonance frequency (fLA) of the mirror element (1) about a first rotation axis (LA) and a second resonance frequency (fSA) about a second rotation axis (SA) is adjusted by an adjustment element. Furthermore, a projection device is specified. The projection device particularly comprises the micro-electromechanical mirror described herein. All features of the micro-electromechanical mirror are also disclosed in the projection device, and vice versa. According to at least one further embodiment, the projection device comprises a laser light source and the micro-electromechanical mirror described herein. For example, the laser light source may comprise or consist of a semiconductor laser diode. As an alternative to the laser light source, the projection device may also comprise an incoherent light source, such as a light-emitting diode. During operation, the laser light source emits laser light, which is generated by stimulated emission. Compared to incoherent light generated by spontaneous emission, the laser light has, in particular, a higher coherence length, a smaller spectral bandwidth and / or a higher degree of polarization. The micro-electromechanical mirror is particularly designed to steer or deflect the laser light emitted by the laser light source. Furthermore, the use of a micro-electromechanical mirror is described in detail, in particular the micro-electromechanical mirror described herein. All features of a micro-electromechanical mirror are also disclosed in the use of a micro-electromechanical mirror, and vice versa. According to at least one embodiment, the MEMS mirror is used to project information onto a surface for use in heads-up displays, matrix lighting, LIDAR applications, holographic projectors, virtual reality (VR) glasses, or augmented reality (AR) glasses. Further advantageous embodiments and developments of the MEMS mirror, the method for producing the MEMS mirror, the method for operating the MEMS mirror, the projection device, and the use of the MEMS mirror are described in more detail below in conjunction with the figures. 1: Micro-electromechanical microscope 2: Mirror element 3: Driving components 4: First spring element 5: Framework 6: Second spring element 7: Adjustment components 8: Torsional suspension 9: Third spring element 10: Structure 11: Substrate components 12: Predetermined Breaking Point 13: Carrier 14: Heating element 15: Piezoelectric adjustment element 16: Sealed shell 21: Reflection layer 22: Lens suspension 31a, 31b: First control area 32a, 32b: Second control area 161:Glass Dome 200: Laser light source 201,201':Laser light 202: Beam Combiner 203: Lens control electronics 204:Sensor Electronics 205: Image processing electronic equipment 206: Laser control electronic equipment 1000: Projection device LA: Long axis SA: short axis fLA: Resonant frequency, major axis fSA: Resonant frequency, minor axis △T: Temperature change p: air pressure FIG. 1 shows a schematic perspective view of a micro-electromechanical mirror according to one embodiment. FIG. 2 shows a schematic top view of a micro-electromechanical mirror according to another embodiment. 3 to 6 are schematic perspective views showing micro-electromechanical mirrors according to other embodiments. 7 and 8 show a schematic cross-sectional view and a schematic perspective view of a micro-electromechanical mirror according to other embodiments. FIG9 is a schematic diagram showing the relationship between the resonance frequency and temperature of a micro-electromechanical mirror according to an embodiment. FIG. 10 shows a schematic top view of a micro-electromechanical mirror portion according to another embodiment. FIG11 shows a schematic diagram of a projection device according to an embodiment. 12A and 12B show the change in the resonant frequency of a mirror element of a MEMS mirror according to one embodiment as a function of gas pressure. Elements that are identical, similar, or have the same function are labeled with the same reference numerals in the figures. The elements and their relative sizes in the figures should not be considered to be drawn to scale. On the contrary, some elements may be exaggerated or reduced in size for better illustration and / or understanding. According to the embodiment shown in FIG1 , a microelectromechanical mirror 1 includes a mirror element 2 connected to a drive element 3 via two first spring elements 4. The drive element 3 is connected to a frame 5 via two second spring elements 6. The frame 5, the drive element 3, the mirror element 2, and the spring elements 4 and 6 are integrally formed on a common substrate (e.g., silicon), in particular by etching the common substrate. Furthermore, an adjustment element 7 serving as a heating element 14 is arranged on the frame 5. A reflective layer 21, for example made of metal, is applied to the mirror element 2. This reflective layer 21 is designed to at least partially reflect light in the visible spectral range. The mirror element 2 has a mirror suspension 22, which is directly connected to the first spring element 4. The mirror suspension 22 is particularly designed to reduce deformation of the mirror element 2 surface during operation of the micro-electromechanical mirror 1. The drive element 3 has an elongated elliptical ring shape with a minor axis SA and a major axis LA perpendicular to the minor axis SA. In the static state, the drive element 3 completely surrounds the main extension plane of the mirror element 2. The first spring element 4 is arranged on the opposite side of the mirror element 2 along the major axis LA, while the second spring element 6 is arranged on the opposite side of the drive element 3 along the minor axis SA. The first spring element 4 and the second spring element 6 are designed as torsion spring elements. A piezoelectric layer is applied to the substrate of the driver element 3. Made of materials such as PZT, AlN, or BFO-BT, it is placed between two metal electrode layers. At least one of the electrode layers is segmented, with first control regions 31a, 31b and second control regions 32a, 32b electrically isolated from each other. By applying an AC voltage to the first control regions 31a and 31b during operation of the micro-electromechanical mirror 1, a temporally periodic mechanical stress is generated in the piezoelectric layer, which resonantly excites a first vibration mode of the mirror element 2. The first vibration mode includes rotational vibration of the mirror element 2 about a first rotation axis, which corresponds to the long axis LA. By applying an AC voltage to the second control regions 32a and 32b during operation of the micro-electromechanical mirror 1, a temporally periodic mechanical stress is generated in the piezoelectric layer, which resonantly excites the second vibration mode of the mirror element 2. The second vibration mode includes rotational vibration of the mirror element 2 about a second rotation axis corresponding to the minor axis SA. The oscillation frequencies of the rotational vibrations of mirror element 2 about its minor axis SA and major axis LA correspond to the resonant frequencies of these two vibration modes and are different from each other. Therefore, during operation, the laser beam reflected by mirror element 2 produces, for example, a Lissajous pattern on the projection surface. The frequency ratio between the two vibration frequencies is preferably a rational ratio. Adjustment element 7 is designed to at least partially adjust at least one resonant frequency of mirror element 2 during operation of microelectromechanical mirror 1. To this end, frame 5 is arranged on a carrier 13 (not shown), wherein frame 5 and carrier 13 have different coefficients of thermal expansion. For example, carrier 13 includes or is made of metal. Adjustment element 7 is a heating element 14 in the form of a conductive channel applied to frame 5. By applying a voltage to heating element 14, the microelectromechanical mirror 1 is heated. Due to the different coefficients of thermal expansion of frame 5 and carrier 13, temperature changes induce mechanical stresses in the common substrate, for example, altering the stiffness of first spring element 4 and / or second spring element 6. Consequently, the resonant frequency of at least one vibration mode of mirror element 2 changes, and mirror element 2 undergoes rotational vibration about major axis LA and / or minor axis SA (see, for example, FIG. 9 ). Adjustment element 7 allows the image refresh rate and / or image resolution to be adjusted within a limited range during operation of the microelectromechanical mirror 1 without significantly limiting the maximum deflection angle of mirror element 2 relative to frame 5. Unlike the micro-electromechanical mirror 1 described in FIG1 , the micro-electromechanical mirror 1 in the embodiment shown in FIG2 additionally includes an elongated, elliptical torsion suspension 8 having a major axis LA and a minor axis SA and arranged between the mirror suspension 22 and the annular drive element 3. The torsion suspension 8 is directly connected to the drive element 3 via a first spring element 4 and directly connected to the mirror suspension 22 of the mirror element 2 via a third spring element 9. The first spring element 4 and the second spring element 6 are arranged along the minor axis SA, while the third spring element 9 is arranged along the major axis LA. The first spring element 4, the second spring element 6, and the third spring element 9 are each designed as a torsion spring element. The torsion suspension 9 helps reduce the anharmonic nature of the rotational vibration of the mirror element 2 about the major axis LA during operation. The adjustment element 7 comprises a substrate element 11 connected to a mirror suspension 22 via a predetermined breaking point 12. Thus, at the end of the manufacturing process of the microelectromechanical mirror 1, the resonant frequency of the mirror element 2 can be adjusted by at least partially removing the substrate element 11. This in particular changes the moment of inertia of the mirror element 2, thereby influencing the resonant frequency of the first and / or second vibration mode. FIG3 shows an embodiment of a MEMS mirror 1 in which, compared to the MEMS mirror 1 depicted in FIG2 , the adjustment element 7 includes a structure 10 on the back side of the mirror element 2. This structure 10 is produced, for example, by etching, laser ablation, or mechanical hard machining of the common substrate, or by printing or adding additional material to the common substrate. This structure 10 is also designed to mechanically stabilize the mirror element 2 and reduce deformation of the reflective front side of the mirror element 2 during operation of the MEMS mirror 1. The structure 10 includes a ring-shaped structure similar to a dam, which is arranged at the edge of the mirror element 2, and a cross-shaped structure 10, which is composed of two beams arranged along the short axis SA and the long axis LA. The structure 10 may also include other and / or more elements, such as straight or curved rib-like elements, which can be at least one selected from other rings, ellipses, circles or ellipse segments, or straight beams. For example, the straight beams form a lattice structure or other geometric shape, such as a rectangle. By adjusting the thickness of the structure 10 in a direction perpendicular to the main extension plane of the mirror element 2, in particular, the mass distribution and the moment of inertia of the mirror element 2 can be at least partially adjusted, thereby changing the resonant frequency of the mirror element 2. For example, the resonant frequency of the rotational vibration mode about the major axis LA is 35.321 kHz without the structure 10 and is 31.227 kHz with the structure 10. For example, the resonant frequency of the rotational vibration mode about the minor axis SA is 18.518 kHz without the structure 10 and is 17.995 kHz with the structure 10. Compared to the MEMS mirror 1 depicted in FIG3 , in the embodiment of the MEMS mirror 1 shown in FIG4 , the cross-shaped structure 10 is at least partially removed along the minor axis SA at the end of the manufacturing process, for example, by laser ablation. This changes the moment of inertia of the mirror element 2 and the resonant frequency of its rotational vibration relative to the major axis LA, while the moment of inertia and resonant frequency of the mirror element 2's rotational vibration relative to the minor axis SA remain approximately unchanged. By partially removing the structure along the minor axis SA, the resonant frequency of the rotational vibration mode about the major axis LA shifts to, for example, 31.407 kHz, while the resonant frequency of the rotational vibration mode about the minor axis SA remains approximately 18.003 kHz. Compared to the MEMS mirror 1 in FIG4 , in the embodiment of the MEMS mirror 1 shown in FIG5 , the cross-shaped structure 10 is at least partially removed along the long axis LA at the end of the manufacturing process, for example, by laser ablation. This allows the resonant frequency of the mirror element 2 to be adjusted relative to the short axis SA. For example, by partially removing the structure along the long axis LA, the resonant frequency of the rotational vibration mode about the short axis SA is shifted to, for example, 18.037 kHz, while the resonant frequency of the rotational vibration mode about the long axis LA remains virtually unchanged at approximately 31.265 kHz. Compared to the MEMS mirror 1 in FIG5 , in the embodiment of the MEMS mirror 1 shown in FIG6 , the cross-shaped structure 10 is at least partially removed along the major axis LA and the minor axis SA at the end of the manufacturing process, for example, by laser ablation. This allows the resonant frequency of the mirror element 2 to be adjusted independently with respect to the minor axis SA and the major axis LA. By partially removing the structure along the major axis LA and the minor axis SA, the resonant frequencies of the rotational vibration modes along the minor axis SA and the major axis LA are shifted, for example, to 18.045 kHz and 31.446 kHz, respectively. The micro-electromechanical mirror 1 according to the embodiment shown in FIG7 includes, in addition to the micro-electromechanical mirror 1 described in FIG1 , a sealed housing 16 consisting of a carrier 13, a frame 5 and a glass dome 161. Therefore, at the end of the manufacturing process or during operation of the micro-electromechanical mirror 1, the air pressure in the housing 16 can be adjusted, which in particular changes the air resistance of the mirror element 2 during its rotational vibration during operation. For example, the air pressure in the housing 16 can be set at 10 -7 Atm to 2 atm (inclusive). This allows at least partial adjustment of the resonant frequency of the mirror element 2. For example, with a pressure change of 1 atm, the resonant frequency changes by approximately 0.05% to 0.2%, in particular by approximately 0.1%. Compared with the MEMS mirror 1 described in FIG. 7 , in the MEMS mirror 1 of the embodiment shown in FIG. 8 , the sealed housing 16 is formed by the carrier 13 and the glass dome 161 , ie, the frame 5 is completely disposed in the sealed housing 16 . Figure 9 shows the changes in the resonant frequencies fLA and fSA of the rotational vibration of the mirror element 2 of the MEMS mirror 1 depicted in Figure 2 about the major axis LA and the minor axis SA as a function of the temperature change ΔT of the MEMS mirror 1. In particular, the resonant frequency fLA of the vibration mode about the major axis LA increases by approximately 0.2%, or 60 Hz, with a temperature increase of 50 K, while the resonant frequency fSA of the vibration mode about the minor axis SA is almost independent of temperature. FIG10 shows an embodiment of a micro-electromechanical mirror 1 in which, compared to the micro-electromechanical mirror 1 depicted in FIG1 , the adjustment element 7 comprises a piezoelectric adjustment element 15 applied to the frame 5 . The piezoelectric adjustment element 15 comprises a piezoelectric layer made of PZT, AlN, or BFO-BT, which is embedded between two metal electrode layers. The piezoelectric adjustment element 15 is arranged adjacent to the second spring element 6 and perpendicular to the minor axis SA. Applying a voltage to the piezoelectric adjustment element 15 generates mechanical stress, which in particular changes the stiffness of the second spring element 6. This allows the resonant frequency of the rotational vibration mode of the mirror element 2 about the minor axis SA to be adjusted during operation of the micro-electromechanical mirror 1. 11 shows a schematic diagram of a projection device 1000 according to an embodiment, which includes a MEMS mirror 1 according to the aforementioned embodiment. In addition, the projection device 1000 is further equipped with a laser light source 200 that emits laser light 201 during operation. For example, the laser light source 200 can be a so-called RGB light source capable of emitting red, green, and blue laser light. To this end, the laser light source 200 may include three correspondingly modulatable laser diodes or laser diode groups. The laser beams can be combined in a beam combiner 202, so that the combined laser beam 201' can be illuminated by the microelectromechanical mirror 1 and reflected by it to the desired image area. The laser light source 200 can be controlled, for example, by laser control electronics 206 to temporally modulate the amplitude of the laser beams 201 and 201'. The MEMS mirror 1 can be controlled via the lens control electronics 203, for example, to generate a desired Lissajous pattern that can be used to scan a desired image area. Furthermore, sensor electronics 204 can be provided to detect the position and / or frequency of the mirror element 2 of the MEMS mirror 1, preferably in real time. Image processing electronics 205 can also be present, for example, to control the overall image display. This may particularly involve converting image or film information into control signals for the laser light source 200 and the MEMS mirror 1, including time synchronization between the position of the mirror element 2 and the amplitude of the laser light 201, 201'. FIG12A shows the resonant frequency fSA of a vibration mode of the mirror element 2 of the micro-electromechanical mirror 1 according to the embodiment of FIG1 , wherein the mirror element 2 performs rotational vibration about the minor axis SA. The resonant frequency fSA is shown as a function of the air pressure p. The air pressure p represents the pressure of the ambient air during operation of the mirror element 2. In particular, the resonant frequency fSA decreases by approximately 0.1% for an increase in the air pressure p by 1 bar. FIG12B shows the resonant frequency fLA of the vibration mode of the mirror element 2 of the micro-electromechanical mirror 1 according to the embodiment of FIG1 , wherein the mirror element 2 performs rotational vibration about the major axis LA. The resonant frequency fLA is shown as a function of the air pressure p. The air pressure p represents the pressure of the ambient air in which the mirror element 2 operates. In particular, when the air pressure p increases by 1 bar, the resonant frequency fLA decreases by approximately 0.1%. The invention is not limited to the description based on the exemplary embodiments. On the contrary, the invention covers every new feature and any combination of features, in particular including any combination of features in the patent claims, even if this feature or combination itself is not explicitly mentioned in the patent claims or the exemplary embodiments. 1: Micro-electromechanical microscope 2: Mirror element 3: Driving components 4: First spring element 5: Framework 6: Second spring element 7: Adjustment components 14: Heating element 21: Reflection layer 22: Lens suspension 31a, 31b: First control area 32a, 32b: Second control area LA: Long axis SA: short axis

Claims

1. A microelectromechanical microscope (1), comprising: The system comprises a mirror element (2), a drive element (3) surrounding the mirror element (2) and connected to the mirror element (2) via a first spring element (4), a frame (5) surrounding the drive element (3) and connected to the drive element (3) via a second spring element (6), a carrier (13) on which the frame (5) is mounted, and at least one adjustment element (7) for adjusting at least one resonant frequency of the mirror element (2), wherein the coefficient of thermal expansion of the carrier (13) is different from that of the frame (5), and the adjustment element (7) includes a heating element (14) and / or a cooling element, which are arranged on the frame (5) or the carrier (13).

2. The microelectromechanical microscope (1) as described in claim 1, wherein, At least one spring element (4, 6) is a torsion spring element.

3. The microelectromechanical microscope (1) as described in claim 1, wherein, A torsional suspension (8) is arranged between the drive element (3) and the mirror element (2), the torsional suspension (8) surrounds the mirror element (2), and the torsional suspension (8) is directly connected to the drive element (3) through the first spring element (4) and directly connected to the mirror element (2) through the third spring element (9).

4. The microelectromechanical microscope (1) as described in claim 1, wherein, The drive element (3) or torsion suspension (8) has an elongated shape with a long axis (LA) and a short axis (SA) perpendicular to the long axis (LA).

5. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) includes a structure (10) on the back side of the mirror element (2).

6. The microelectromechanical microscope (1) as described in claim 5, wherein, The structure (10) is configured to mechanically reinforce the mirror element (2).

7. The microelectromechanical microscope (1) as described in claim 5, wherein, The structure (10) is arranged on at least one rotation axis (LA, SA) of the mirror element (2).

8. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) includes at least one substrate element (11) which at least partially surrounds the mirror element (2) and is directly connected to the mirror element (2) through a predetermined break point (12).

9. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) is configured to adjust at least one resonant frequency during a predetermined operation of the microelectromechanical microscope (1).

10. The microelectromechanical microscope (1) as claimed in claim 1, wherein, The adjusting element (7) includes a piezoelectric adjusting element (15) configured to change the stiffness of at least one spring element (4, 6, 9).

11. The microelectromechanical microscope (1) as described in claim 10, wherein, The piezoelectric adjustment element (15) is arranged on the frame (5).

12. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) includes an electrode configuration of the drive element (3), and the electrode configuration is configured to mechanically excite the lateral length mode of the piezoelectric layer in the drive element (3), wherein the lateral length mode is excited to adjust the resonant frequency of the mirror element (2).

13. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) includes a sealed housing (16) in which at least the mirror element (2) is disposed, and the sealed housing (16) is configured to adjust at least one resonant frequency by changing the air pressure (p) inside the sealed housing (16).

14. The microelectromechanical microscope (1) as described in claim 1, wherein, The adjustment element (7) is configured to adjust the frequency ratio between the first resonant frequency (fLA) and the second resonant frequency (fSA) during a predetermined operation of the microelectromechanical microscope (1), the first resonant frequency (fLA) and the second resonant frequency (fSA) corresponding to the rotational vibration of the mirror element (2) around the first rotation axis (LA) and the second rotation axis (SA), respectively.

15. The microelectromechanical microscope (1) as described in claim 1, wherein, The microelectromechanical microscope (1) is configured to adjust the resonant frequency of the first vibration mode and / or the second vibration mode by adjusting the DC component applied to the first control region (31a / 31b) and / or the second control region (32a / 32b) of the drive element (3).

16. The microelectromechanical microscope (1) as claimed in claim 1, wherein, The microelectromechanical microscope (1) is configured to cause the mirror element (2) to enter a first vibration mode by applying a first AC signal with a first frequency to the first control area (31a, 31b) of the drive element (3), and to cause the mirror element (2) to enter a second vibration mode by applying a second AC signal with a second frequency to the second control area (32a, 32b) of the drive element (3).

17. The microelectromechanical microscope (1) as described in claim 1, wherein, The microelectromechanical microscope (1) is configured to adjust the resonant frequency of a first vibration mode and / or a second vibration mode by adjusting the temperature of the microelectromechanical microscope (1), wherein the mirror element (2) is configured to set the temperature by at least partially absorbing laser radiation.

18. A method for manufacturing a microelectromechanical microscope (1), comprising the following steps: forming a mirror element (2); forming a driving element (3) surrounding the mirror element (2) and connected to the mirror element (2) via a first spring element (4); forming a frame (5) surrounding the driving element (3) and connected to the driving element (3) via a second spring element (6); forming a carrier (13), wherein the frame (5) is placed on the carrier (13), wherein the coefficient of thermal expansion of the carrier (13) is different from the coefficient of thermal expansion of the frame (5); and adjusting at least one resonant frequency of the mirror element (2) by at least one adjusting element (7), wherein, The adjustment element (7) includes a heating element (14) and / or a cooling element, which are arranged on the frame (5) or the carrier (13).

19. A method for manufacturing a microelectromechanical microscope (1) as described in claim 18, wherein, The adjustment element (7) includes a structure (10) on the back of the mirror element (2), and adjusts at least one resonant frequency by applying or at least partially removing the structure (10).

20. A method for manufacturing a microelectromechanical microscope (1) as described in claim 18, wherein, The adjustment element (7) includes at least one substrate element (11) that at least partially surrounds the mirror element (2) and is directly connected to the mirror element (2) through a predetermined break point (12), and at least one resonant frequency is adjusted by removing the substrate element (11).

21. A method for manufacturing a microelectromechanical microscope (1) as described in claim 18, wherein, The adjustment element (7) includes the electrode configuration of the drive element (3) and the resonant frequency of the mirror element (2) by mechanically exciting the lateral length mode of the piezoelectric layer of the drive element (3).

22. A method for manufacturing a microelectromechanical microscope (1) as described in claim 18, wherein, The driving element (3) includes a first control region (31a, 31b) and a second control region (32a, 32b), and adjusts the resonant frequency of the first vibration mode and / or the second vibration mode of the mirror element (2) by adjusting the DC component of the electric current applied to the first control region (31a, 31b) and / or the second control region (32a, 32b).

23. A method for operating a microelectromechanical microscope (1), the microelectromechanical microscope (1) comprising a mirror element (2), a driving element (3), a frame (5), a carrier (13), and at least one adjusting element (7), wherein, The drive element (3) surrounds the mirror element (2) and is connected to the mirror element (2) via a first spring element (4). The frame (5) surrounds the drive element (3) and is connected to the drive element (3) via a second spring element (6). The frame (5) is placed on the carrier (13), wherein the coefficient of thermal expansion of the carrier (13) is different from the coefficient of thermal expansion of the frame (5). The adjustment element (7) includes a heating element (14) and / or a cooling element, which are arranged on the frame (5) or the carrier (13). The mirror element (2) is set to a first vibration mode and a second vibration mode. The adjustment element (7) is configured to adjust the resonant frequency of the first vibration mode and / or the second vibration mode.

24. The method of operating the microelectromechanical microscope (1) as described in claim 23, wherein, The microelectromechanical microscope (1) also includes a driving element (3), the mirror element (2) enters the first vibration mode by a first AC signal with a first frequency applied to the first control area (31a, 31b) of the driving element (3), and the mirror element (2) enters the second vibration mode by a second AC signal with a second frequency applied to the second control area (32a, 32b) of the driving element (3).

25. The method of operating the microelectromechanical microscope (1) as described in claim 23, wherein, The first vibration mode includes the rotation of the mirror element (2) around a first rotation axis, the second vibration mode includes the rotation of the mirror element (2) around a second rotation axis orthogonal to the first rotation axis, and the first vibration mode and the second vibration mode are resonantly excited.

26. The method of operating the microelectromechanical microscope (1) as described in claim 23, wherein, The adjustment element (7) includes a heating element (14) and / or a cooling element, and adjusts the resonant frequency of the first vibration mode and / or the second vibration mode by adjusting the temperature of the microelectromechanical microscope (1).

27. The operating method of the microelectromechanical microscope (1) as described in claim 26, wherein, The microelectromechanical microscope (1) dehumidifies by adjusting the temperature.

28. The method of operating the microelectromechanical microscope (1) as described in claim 23, wherein, The microelectromechanical microscope (1) also includes at least one spring element (4, 6, 9), the adjustment element (7) includes a piezoelectric adjustment element (15), and the stiffness of the at least one spring element (4, 6, 9) is changed by applying a voltage to the piezoelectric adjustment element (15) to adjust the resonant frequency of the first vibration mode and / or the second vibration mode.

29. The method of operating the microelectromechanical microscope (1) as described in claim 24, wherein, The resonant frequencies of the first vibration mode and / or the second vibration mode are adjusted by adjusting the DC components of the electrical current applied to the first control region (31a, 31b) and / or the second control region (32a, 32b).

30. The method of operating the microelectromechanical microscope (1) as described in claim 23, wherein, The adjustment element (7) includes a sealed housing (16) containing at least the mirror element (2), and adjusts at least one resonant frequency by changing the air pressure (p) inside the sealed housing (16).

31. The method of operating the microelectromechanical microscope (1) as described in claim 24, wherein, The adjustment element (7) includes an electrode configuration of the drive element (3), and the electrode configuration is further designed to mechanically excite the lateral length mode of the piezoelectric layer of the drive element (3), wherein the lateral length mode is excited to adjust at least one resonant frequency of the mirror element (2).

32. The operating method of the microelectromechanical microscope (1) as described in claim 23, wherein, The resonant frequency of the first vibration mode and / or the second vibration mode is adjusted by adjusting the temperature of the microelectromechanical microscope (1), wherein the temperature is set by at least partially absorbing the laser radiation of the mirror element (2).

33. The operating method of the microelectromechanical microscope (1) as described in claim 23, wherein, The adjustment element (7) is configured to adjust the frequency ratio between the first resonant frequency (fLA) of the mirror element (2) around the first rotation axis (LA) and the second resonant frequency (fSA) around the second rotation axis (SA).

34. A projection device (1000) comprising a laser light source (200) and a microelectromechanical microscope (1) according to claim 1.

35. An application of the microelectromechanical microscope (1) according to claim 1, including projecting information onto a surface for use in head-up displays, matrix lighting, LiDAR applications, holographic projectors, virtual reality (VR) glasses, or augmented reality (AR) glasses.

36. A microelectromechanical microscope (1), comprising: The mirror element (2), the driving element (3) surrounding the mirror element (2) and connected to the mirror element (2) via a first spring element (4), and at least one adjusting element (7) adjusting at least one resonant frequency of the mirror element (2), wherein the adjusting element (7) includes an electrode configuration of the driving element (3), and the electrode configuration is further designed to mechanically excite the lateral length pattern of the piezoelectric layer of the driving element (3), wherein the resonant frequency of the mirror element (2) is adjusted by exciting the lateral length pattern.

37. A microelectromechanical microscope (1), comprising: A mirror element (2), at least one adjustment element (7) including a structure (10) on the back of the mirror element (2) and configured to adjust at least one resonant frequency of the mirror element (2), wherein the structure (10) has a cross-shaped structure that is arranged parallel to the rotation axis of the mirror element (2).

Images