Reluctance actuator, fast steering mirror and method

Abstract

The invention relates to a reluctance actuator (8), to a fast steering mirror (i.e. a controllable high-speed mirror) having a reluctance actuator of this type, and to a method for carrying out lifting / tilting movements of a movable element of a reluctance actuator. The reluctance actuator (8) comprises a magnetizable core (1), a coil (2) which is designed to generate a magnetic flux in the core, and a movable element (3) for lifting / tilting movements. In addition, the reluctance actuator has a permanent magnet (9) as a component, which moves relative to a ferromagnetic component of the reluctance actuator in the event of a specific deflection of the movable element, such that one of the components dips into an opening of the respective other component.

Description

[0001] RELUCTANCE ACTUATOR, FAST STEERING MIRROR AND METHOD

[0002] The invention relates to a reluctance actuator, a fast steering mirror (i.e. a steerable high-speed mirror) with such a reluctance actuator, and a method for performing lifting / tilting movements of a movable element of a reluctance actuator.

[0003] Reluctance actuators and their use in fast steering mirrors (FSMs) of the type in question have been known in practice for years. Fast steering mirrors are optomechatronic tip / tilt systems with many applications, which can be mainly divided into pointing and scanning. Pointing applications include tasks such as stabilizing optical systems in free-space optical communication, acquiring optical signals and tracking objects, and aligning laser or light beams to a target. Scanning applications are even more widespread, including laser scanning, material processing, optical scanning lithography, confocal microscopy, and inline metrology.

[0004] The drive technology significantly determines the performance of FSMs in terms of range and bandwidth. FSMs are typically driven by piezoelectric actuators for high-bandwidth, but limited-range applications, or Lorentz actuators for long-range, but limited-bandwidth applications. In recent years, hybrid reluctance actuators (HRAs) have been shown to exhibit the highest range-bandwidth product at angular ranges below 120 mrad (see E. Csencsics and G. Schitter, “Exploring the Pareto Fronts of Actuation Technologies for High Performance Mechatronic Systems,” IEEE / ASME Transactions on Mechatronics, vol. 26, no. 2, pp. 1053–1063, 2021). An example of a compact hybrid reluctance actuator is given, for instance, in DE 102017 202 182 A1. In a conventional HRA, a permanent magnet can be used to generate a magnetic bias flux.The bias flux is introduced into the working air gap between the yoke and the moving element. The coil flux increases or decreases the magnetic flux in the working air gap. This actuator design leads to a non-linear relationship between torque and current, especially at large deflection angles. In the conventional HRA, the working air gaps for the magnetic pre-magnetization flux of the permanent magnet are arranged in parallel. The deflection of the rotor disproportionately increases or decreases the distribution of the magnetic pre-magnetization flux at the increasing or decreasing air gap. This effect significantly contributes to the non-linearity of conventional HRAs, which is a major limitation at large deflection angles. This results in the following limitations:

[0005] A magnetic bias flux introduces a negative stiffness into the system behavior. This negative stiffness is typically compensated by a bending device to maintain the stability of the open-loop control system. However, the nonlinearities cause the negative stiffness to vary depending on the mirror deflection, leading to an unstable open-loop system. In the worst case, the mirror snaps into the yoke at either maximum or minimum deflection. Furthermore, for energy-efficient scanning applications, FSMs are operated at their resonant frequency. The varying negative stiffness of HRA technology shifts the resonance depending on the offset position and the scanning amplitude, resulting in reduced efficiency at desired constant scanning frequencies.Furthermore, the performance of FSMs, specifically the torque-current ratio, depends on the angular deflection of the mirror, which is undesirable for many applications. The nonlinear system dynamics also significantly increase the complexity and development time of the motion control system.

[0006] These disadvantages prevent or complicate the use of HRA technology in FSMs where particularly linear dynamics are desired. The present invention therefore aims to design and further develop a reluctance actuator of the type mentioned above in such a way as to improve the linearity of the reluctance actuator.

[0007] According to the invention, the aforementioned problem is solved by the features of claim 1. The reluctance actuator in question comprises a magnetizable core, a coil configured to generate a magnetic flux in the core, and a movable element for lifting / tilting movements. Furthermore, the reluctance actuator includes a permanent magnet as a component which, at a certain deflection of the movable element relative to a ferromagnetic component of the reluctance actuator, moves such that one of the components engages an opening in the other. For the sake of simplicity, this is referred to here as a permanent magnet. In particular, two permanent magnets can be provided for each desired degree of freedom of the reluctance actuator, of which, depending on the deflection of the movable element in the respective degree of freedom, either neither or one of the two permanent magnets of that degree of freedom engages the opening of the movable element.

[0008] In accordance with the invention, it has first been recognized that the linearity of a reluctance actuator can be improved by modifications to its design, so that it can be referred to as a hardware-linearized reluctance actuator. This is achieved, for example, by additionally arranging a permanent magnet on or at the pole shoes of the stator yoke, or at the ends of the movable element, to influence the pre-magnetization flux. Corresponding to these permanent magnets, openings are provided in the movable element or on the pole shoes of the reluctance actuator, into which the respective permanent magnet can be inserted, or the permanent magnet forms an opening into which the ferromagnetic component can be inserted.When the permanent magnet or ferromagnetic component is immersed in the opening, the portion of the permanent magnet that protrudes into the opening is magnetically short-circuited. This causes the effective length, and therefore the force, of the permanent magnet to change depending on the immersion depth. This results in a homogeneous magnetic field, regardless of the deflection of the moving element, especially at the minimum and maximum deflection angles. This significantly improves the linearity of the reluctance actuator. Furthermore, the immersion reduces magnetic leakage.

[0009] In this context, lifting / tilting movements are rotational movements of the moving element around a center of rotation. The center of rotation can be either an axis of rotation or a pivot point. A first component is positioned at a distance from the center of rotation on the moving element. Due to the electromotive force, the first component is attracted to a second component on the stator. Because of the forced guidance provided by the center of rotation, it simultaneously performs a tilting movement around the center of rotation. If, for example, a mirror is mounted on the moving element, this lifting / tilting movement can direct light in different directions.

[0010] The permanent magnet moves relative to the opening due to the movement of the movable element. Various configurations are possible. For example, the permanent magnet can be located on a stator yoke of the reluctance actuator, and the ferromagnetic component can be formed by or attached to the movable element. Alternatively, the permanent magnet can be located on the movable element, and the ferromagnetic element can be located on the stator yoke.

[0011] Furthermore, various implementations are possible regarding the opening. The opening can be formed by the ferromagnetic component, and the permanent magnet can be inserted into the opening of the ferromagnetic component at a specific deflection of the moving element. Alternatively, the opening can be formed by the permanent magnet itself, and the ferromagnetic component can be inserted into the opening of the permanent magnet at a specific deflection of the moving element. In particular, the proposed arrangement ensures that the permanent magnet is at least partially magnetically short-circuited upon insertion, thus reducing its effective length. Consequently, the effective length of the permanent magnet, and therefore the magnetic premagnetization flux, varies depending on the deflection of the moving element.This, in turn, allows the effective length of the permanent magnet to be altered by immersion in such a way that the magnetic premagnetization flux at the working air gaps of the reluctance actuator is at least approximately linear to the displacement of the moving element. This improves the linearity of the reluctance actuator. In contrast, with conventional hybrid reluctance actuators, the permanent magnet flux is constant with the displacement.

[0012] The permanent magnet, or as described above, the permanent magnets, or the ferromagnetic component(s) are inserted into openings in the element. These openings can, for example, laterally enclose the permanent magnet or the ferromagnetic component. In other words, the opening can be annular or otherwise enclosing. This achieves the greatest possible short-circuit effect.

[0013] Alternatively, the opening of the moving element can be fork-shaped, meaning it does not completely enclose the permanent magnet or ferromagnetic component laterally. This allows for a more compact design of the reluctance actuator.

[0014] As previously explained, the permanent magnet or the opening is located, for example, on a pole shoe of the reluctance actuator's stator. This allows, in particular, the magnetic pre-magnetization flux at the working air gap to be designed to be linear, or at least more linear, with respect to the deflection of the moving element at different deflections, thus improving linearity. For example, the pole shoe on which the respective component is mounted can be chamfered. This results in a further significant improvement in linearity. In particular, the chamfer of the pole shoe can be adapted to a maximum deflection of the moving element.

[0015] Furthermore, the pole shoe, on which one of the components (i.e., the permanent magnet or the opening) is located, can have a rounded shape. This reduces crosstalk, particularly in reluctance actuators with multiple desired degrees of freedom.

[0016] To improve the efficiency of the reluctance actuator, a ferromagnetic structure, such as a ferromagnetic layer, can be arranged on the permanent magnet.

[0017] The permanent magnet or ferromagnetic component can, for example, have a cube-shaped or cuboid shape in cross-section.

[0018] The reluctance actuator according to the invention can, for example, be configured as a reluctance actuator with a desired degree of freedom. In particular, the movable element can be movable in a single desired rotational degree of freedom. Reluctance actuators with a desired degree of freedom have many applications.

[0019] Besides applications with a single desired degree of freedom, there are also applications that require movement in two degrees of freedom. For example, the moving element can be movable in (exactly) two desired rotational degrees of freedom. The movement of the moving element in these two desired degrees of freedom can be controlled, for example, by means of coupled magnetic circuits or by means of two decoupled magnetic circuits. Reluctance actuators with two desired degrees of freedom can also be used, in particular, in fast steering mirrors.

[0020] To prevent the moving element from performing unwanted movements, the degrees of freedom of the reluctance actuator can be restricted. For example, movement of the moving element along unwanted degrees of freedom can be restricted by means of at least one bending element, at least one mechanical bearing, or at least one magnetic bearing.

[0021] To further improve positioning precision, the reluctance actuator can also include a control circuit and one (or more) position sensors to determine the current displacement of the moving element. The control circuit is designed to regulate the displacement of the moving element based on sensor data from the position sensor(s). The position, and thus the displacement, of the moving element can be determined via the position sensor(s). This ensures precise positioning of the moving element. This positioning can then be used, for example, within a control loop implemented by the control circuit, to regulate the displacement of the moving element to a desired value.

[0022] Another aspect of the present invention relates to a fast steering mirror with the reluctance actuator according to the invention. A reflective element of the fast steering mirror (such as a mirror) is arranged on the movable element of the reluctance actuator. FSMs particularly benefit from the improved linearity of the reluctance actuator according to the invention. Furthermore, this allows for the realization of FSMs with a high bandwidth.

[0023] Another aspect of the present invention relates to a method for performing lifting / tilting movements of a movable element of the reluctance actuator according to the invention. The method is characterized in particular by the fact that the movable element is moved by controlling an excitation current for the coil such that the permanent magnet is moved relative to a ferromagnetic component of the reluctance actuator such that one of the components enters an opening of the other component.

[0024] The presented reluctance actuator can be used, for example, in optical free-space communication, for laser scanning, as part of a high-resolution surface scanner, in lithography, in material processing, in additive manufacturing, in confocal microscopy, inline metrology, and / or for the alignment of laser or light beams.

[0025] There are now various ways to advantageously elaborate and further develop the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the claims subordinate to claim 1 and, on the other hand, to the following explanation of preferred embodiments of the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows

[0026] Fig. 1 shows the operating principle of a compact Fast Steering Mirror with a hybrid reluctance actuator;

[0027] Fig. 2 shows a diagram of the torque of a hybrid

[0028] Reluctance actuator of a fast steering mirror;

[0029] Fig. 3 shows an embodiment of a hardware-industrialized

[0030] Hybrid reluctance actuator;

[0031] Fig. 4 shows a diagram of the torque of the hardware linearized hybrid reluctance actuator;

[0032] Figures 5a to 5d illustrate the detailed principle of hardware linearized HRA technology for two exemplary deflection angles;

[0033] Fig. 6 shows a schematic representation of a device according to the invention.

[0034] Reluctance actuator with two degrees of freedom;

[0035] Fig. 7 shows a CAD model of a lift / tilt FSM with the hardware-industrialized HRA technology according to the invention; Fig. 8 shows an embodiment of a hardware-industrialized

[0036] Hybrid reluctance actuator in which the permanent magnet is arranged on the moving element and immerses itself in an opening or recess in the stator; and

[0037] Fig. 9 shows an embodiment of a hardware-industrialized

[0038] Hybrid reluctance actuator with a position sensor and a control circuit.

[0039] Fig. 1 shows the operating principle of a compact FSM with a hybrid reluctance actuator (HRA). Fig. 1 shows an HRA with a core 1 containing a permanent magnet and coils 2 for generating a coil flux. The HRA also includes a movable element 3. Between the movable element and the pole pieces of the core, a left working air gap 4a, a right working air gap 4b, and a further air gap 4c, which is not a working air gap, are visible. Fig. 1 also shows a coil flux 5 and a premagnetization flux 6. The arrow 7 above the movable element 3 indicates the net torque. The permanent magnet introduces the magnetic premagnetization flux 6 into the left and right working air gaps 4a and 4b, and the coil flux 5 increases or decreases the magnetic flux in the working air gaps 4a and 4b.This actuator design results in a non-linear relationship between torque, current, and the deflection angle of the moving element, particularly at the deflection limits, as shown in Fig. 2. Fig. 2 shows a graph of the resulting torque as a function of the deflection angle. Here, the non-linearities of conventional technology are evident. The deflection of the moving element disproportionately increases or decreases the distribution of the magnetic premagnetization flux across the increasing or decreasing air gap. This effect causes the non-linearity of conventional HRAs, which is a limitation at large deflection angles.

[0040] The invention lies in the construction of a hybrid reluctance actuator for a fast steering mirror with a redesigned magnetic circuit that reduces or minimizes the nonlinearities of conventional hybrid reluctance actuators. Through relative movement between a permanent magnet and a ferromagnetic component, for example, by immersing permanent magnets in a ferromagnetic movable element or by immersing a ferromagnetic component in an opening formed by the permanent magnet, the effective length of the permanent magnets is varied depending on the deflection angle and is reduced, in particular, with decreasing working air gap length. This mechanism increases the linearity of the FSM over a wide operating range. Furthermore, the design reduces magnetic leakage flux, resulting in an improved current-torque ratio.

[0041] In contrast to conventional reluctance actuators, in the present invention a magnetic premagnetization flux is introduced into the magnetic circuit by a relative movement between the permanent magnet and the ferromagnetic component, for example by immersing the permanent magnet in the ferromagnetic mover, as shown schematically for a one-degree-of-freedom FSM in Fig. 3.

[0042] Fig. 3 shows an embodiment of a hardware-intearized hybrid reluctance actuator 8 with one degree of freedom, comprising a magnetizable kem 1, actuator coils 2 on the stator yoke arms of the kem 1 configured to generate a magnetic flux in the kem, and a ferromagnetic movable element 3, also configured as a yoke. The actuator coils can be reduced to one coil per degree of freedom or be (or remain) divided into multiple parts.

[0043] In contrast to a conventional HRA, the HRA according to the invention of Fig. 3 comprises permanent magnets 9 arranged on the pole shoes 10 of the stator and immersed in openings 11 of the movable element 3. Alternatively, the permanent magnet(s) can be arranged on the movable element, as shown in Fig. 8. Furthermore, it is possible that the ferromagnetic component, rather than the permanent magnet, immerses in the permanent magnet. For example, the permanent magnets (or the immersed ferromagnetic component) can have a cubic or cuboid cross-section. This can result, for example, in a cylindrical shape where the height equals the diameter (cubic cross-section) or where the height does not equal the diameter (cuboid cross-section). Additionally, a ferromagnetic component (not shown) can be located at the top (i.e.,in the direction of a mirror that is arranged on the moving element) on the permanent magnet, further increasing the efficiency of the reluctance actuator, and thus of the FSM.

[0044] In the embodiments shown in Figures 3, 5c, 5d, 6, 7, 8, and 9, the pole shoes 10 are chamfered, meaning that one side facing the moving element is not perpendicular to the axis of the core leg, but is tilted by at least 1° (or at least 2°, or at least 3°, or at least 4°). Chamfered (or inclined) ferromagnetic yokes at the working air gaps improve the linearity of the actuator technology. In Figure 3, the stator yoke 10 (i.e., the pole shoe) is chamfered by the maximum deflection angle of the moving element 3 to maintain a homogeneous magnetic field at large deflection angles. Thus, the angle can be adapted to a maximum or minimum deflection of the moving element 3. This further contributes significantly to linearization.

[0045] The permanent magnets 9 are arranged in Figures 3, 5a to 7, and 9 such that they engage in openings 11 of the movable element 3 at certain deflection angles of the movable element. In Figure 3, the movable element 3 has annular openings 11 that laterally enclose the respective permanent magnet. However, non-enclosing openings, such as fork-shaped openings, are also conceivable. Thus, the permanent magnet can be either partially or completely enclosed (laterly) by the ferromagnetic movable element in order to magnetically short-circuit an upper part of it.

[0046] The presented mechanism partially magnetically short-circuits the permanent magnet 9, resulting in improved linearity of the torque acting on the ferromagnetic movable element 3, as shown by the FEM simulation results in Fig. 4. Fig. 4 shows a diagram of a resulting torque as a function of the deflection angle for the HRA 8 of Fig. 3. The simulation results in Fig. 4 demonstrate the improved linearity based on the torque acting on the ferromagnetic movable element.

[0047] Figures 5a to 5d illustrate the detailed principle of the hardware linearized HRA technology for two exemplary deflection angles, with Figures 5a and 5b showing an embodiment without beveled pole shoes 10 and Figures 5c and 5d showing an embodiment with beveled pole shoes 10. Figures 5a to 5d show a partial view of an HRA 8 in which the permanent magnet 9, arranged on the pole shoe 10, is inserted into the opening 11 of the movable element. Figures 5a to 5d also show the coil flux 5, the magnetic bias flux 6, and, except in Figure 5a, the short-circuited magnetic flux 12. The physical length IPM of the permanent magnet 9 and the effective length left of the permanent magnet 9 are also shown.To avoid the nonlinearities of conventional HRAs caused by the unevenly distributed magnetic bias flux 6 of the permanent magnet, it is advantageous to ensure a linear magnetic bias flux independent of the deflection of the mover.

[0048] In Figures 5a and 5c, the working air gap of the reluctance actuator, and thus of the FSM, is near its maximum, resulting in higher magnetic resistance compared to the horizontal position of the magnet. To make the magnetic premagnetization flux linear with respect to the displacement, the effective length of the permanent magnet is increased. In Figures 5b and 5d, the working air gap is near its minimum, resulting in lower magnetic resistance compared to the horizontal position of the actuator. To make the magnetic premagnetization flux linear with respect to the displacement, the effective permanent magnet length is reduced by short-circuiting the upper part of the permanent magnet. The novel HRA design ensures that the effective length of the permanent magnet can be adjusted according to the length / size of the working air gap by means of a hardware design change, resulting in improved linearity of the HRA technology.Additionally, the current design, in which the permanent magnets are immersed in the openings, reduces the leakage flux of the permanent magnet, further improving the actuator's efficiency. To make the reluctance actuator more compact, a fork-like design of the moving element is also possible, so that the permanent magnet is only partially enclosed.

[0049] Many pointing and scanning applications for FSMs require two degrees of freedom. The reluctance actuator according to the invention can therefore be implemented with two degrees of freedom, whereby two actuators with one degree of freedom can be combined orthogonally. The invention can thus be used for reluctance actuators and FSMs with one or two degrees of freedom. Reluctance actuators and FSMs with two degrees of freedom can be implemented with coupled magnetic circuits or with two decoupled HRAs with one degree of freedom. The resulting FSM design with a displacement range of ±4° and a target positioning bandwidth of >1 kHz is shown in Figures 6 and 7. Figure 6 shows a schematic representation of the reluctance actuator with two degrees of freedom, and Figure 7 shows a CAD model of a lift / tilt FSM with the hardware-integrated HRA technology according to the invention.Figure 6 shows, in particular, a reluctance actuator with four pole legs 10, each of which is fitted with a permanent magnet 9. Accordingly, the movable element 3 has four openings into which the respective permanent magnets 9 can be inserted. Each pole leg is also assigned an actuator coil 2. A common core 1 is used. Figure 6 also clearly shows that the pole shoes 10 are chamfered. Furthermore, rounded pole surfaces are used to reduce or minimize crosstalk between the degrees of freedom of the lift / tilt reluctance actuator. A round shape of the ferromagnetic yokes at the working air gaps reduces crosstalk in reluctance actuators and FSMs with two degrees of freedom. Figure 7 shows the integration of the two-degrees-of-freedom reluctance actuator into an FSM. In addition to the features shown in Figure 6, the following features are also shown:In addition to the six known components, the mirror 13 and a tilting / lifting bending element 14, which is arranged externally, are also shown here. Alternatively, a rod-shaped bending element in the center or a disc-shaped bending element parallel to the movable element, or a combination of both, can be used. The tilting / lifting bending element 14 compensates for the negative stiffness to stabilize the mirror position and limits the mirror movement (and thus the movement of the movable element 3) to the desired two rotational degrees of freedom. Alternatively or additionally, a mechanical bearing or a magnetic bearing can be used for this purpose. The desired (and undesired) degrees of freedom can thus be defined by means of bending elements, mechanical bearings, or magnetic bearings.

[0050] In the examples shown in Figures 3, 5a to 7, and 9, embodiments are depicted in which the permanent magnet 9 is arranged on the stator yoke and extends into an opening in the moving element. However, alternative arrangements are also possible. For example, the permanent magnet can be located on the moving element and extend into an opening in the stator yoke (bore, slot, etc.). Figure 8 shows an embodiment in which the permanent magnet is arranged on the moving element and extends into an opening or recess in the stator.

[0051] In another alternative embodiment, the permanent magnet can be designed as a ring magnet, and the yoke (stator or movable element) can be rod-shaped and immersed in the ring magnet. The ring magnet can be mounted on the stator yoke or the movable element. The crucial factor is the relative movement and thus the relative immersion, which leads to a change in the effective length. The precise location of the permanent magnet or ferromagnetic yoke is of secondary importance.

[0052] The proposed hardware-integrated FSM combines the advantageous higher performance of HRA with improved system linearity, thereby making HRA technology applicable to a wider range of applications. The present invention relates to a system that improves the linearity of hybrid reluctance actuators for fast steering mirrors by immersing a premagnetizing flux permanent magnet in the ferromagnetic moving element, such that the effective length of the permanent magnet is adapted to the length of the working air gap and the associated mirror deflection. A current flow in the actuator coils changes the magnetic flux in the working air gaps, which are used to control the mirror position.

[0053] The reluctance actuator or the FSM with the reluctance actuator can be controlled by means of a control circuit. Thus, the reluctance actuator or the FSM can include this control circuit 15, as shown in Fig. 9. The control circuit 15 can be configured to control the deflection of the movable element of the reluctance actuator or the mirror of the FSM by controlling the current flowing through the coil or coils. Position sensors 16 can be integrated into the FSM (e.g., in the reluctance actuator or outside the reluctance actuator) to control the mirror position. In particular, the control circuit can be configured to control the deflection of the movable element based on sensor data from the position sensor.Thus, the control circuit 15 can be configured to regulate the deflection of the moving element, and therefore of the mirror, based on sensor data from the position sensor(s) 16, in order to achieve a desired deflection of the moving element or the mirror.

[0054] Figure 9 shows an embodiment of a hardware-integrated hybrid reluctance actuator with a position sensor 16, which serves to detect the displacement of the moving element and, in conjunction with a control circuit 15, to provide control signals. In this example, the position sensor 16 is designed as a flat sensor, i.e., (at least) one sensor element is arranged in a flat substrate, for example, a printed circuit board or an LTCC (low-temperature cofired ceramic) ceramic. In this example, two sensor elements (not shown) measure the distances d1 and d2 to the moving element in a differential arrangement, from which the displacement can be determined.

[0055] Regarding further advantageous embodiments of the device according to the invention, reference is made to the general part of the description and to the attached claims to avoid repetition.

[0056] Finally, it should be expressly pointed out that the exemplary embodiments of the device according to the invention described above serve only to discuss the claimed teaching, but do not limit it to these exemplary embodiments.

[0057] Reference symbol list

[0058] 1 core

[0059] 2 coils

[0060] 3 Movable element a, 4b Working air gap

[0061] 4c air gap

[0062] 5 Coil flux

[0063] 6. Premagnetization flux

[0064] 7 Net moment

[0065] 8 Reluctance actuator

[0066] 9 permanent magnet

[0067] 10 pole shoe

[0068] 11 Opening

[0069] 12 Short-circuited magnetic flux

[0070] 13 mirrors

[0071] 14 Lift / Tilt Bending Element

[0072] 15 Control circuit

[0073] 16 Position sensor

Claims

Claims 1. Reluctance actuator comprising: a magnetizable core, a coil configured to generate a magnetic flux in the core, and a movable element for lifting / tilting movements, characterized in that the reluctance actuator includes a permanent magnet as a component which, at a certain deflection of the movable element, moves relative to a ferromagnetic component of the reluctance actuator, such that one of the components enters an opening of the other component.

2. Reluctance actuator according to claim 1, characterized in that the permanent magnet is arranged on a stator yoke of the reluctance actuator and the ferromagnetic component is formed by the movable element or is arranged on the movable element.

3. Reluctance actuator according to claim 1, characterized in that the The permanent magnet is arranged on the moving element and the ferromagnetic element is arranged on the stator yoke.

4. Reluctance actuator according to one of claims 1 to 3, characterized in that the opening is formed by the ferromagnetic component and the permanent magnet dips into the opening of the ferromagnetic component at a certain deflection of the movable element.

5. Reluctance actuator according to one of claims 1 to 3, characterized in that the opening is formed by the permanent magnet and the ferromagnetic component dips into the opening of the permanent magnet at a certain deflection of the movable element.

6. Reluctance actuator according to one of claims 1 to 5, characterized in that the permanent magnet is at least partially magnetically short-circuited by immersion, thereby reducing the effective length of the permanent magnet.

7. Reluctance actuator according to one of claims 1 to 6, characterized in that by immersing the permanent magnet an effective length of the permanent magnet is changed such that a magnetic premagnetization flux at the working air gaps of the reluctance actuator is at least approximately linearly dependent on a deflection of the movable element.

8. Reluctance actuator according to one of claims 1 to 7, characterized in that the opening is an annular opening or an otherwise enclosing opening.

9. Reluctance actuator according to one of claims 1 to 8, characterized in that the opening is a fork-shaped opening.

10. Reluctance actuator according to one of claims 1 to 9, characterized in that a pole shoe on which one of the components is arranged is chamfered.

11. Reluctance actuator according to claim 10, characterized in that an inclination of the pole shoe is adapted to a maximum deflection of the movable element.

12. Reluctance actuator according to one of claims 10 or 11, characterized in that the pole shoe on which one of the components is arranged has a rounded shape.

13. Reluctance actuator according to one of claims 1 to 12, characterized in that a ferromagnetic structure is arranged on the permanent magnet.

14. Reluctance actuator according to one of claims 1 to 13, characterized in that the permanent magnet or the ferromagnetic component has a cube-shaped or cuboid shape in cross-section.

15. Reluctance actuator according to one of claims 1 to 14, further comprising a control circuit and a position sensor for determining a current deflection of the movable element, wherein the control circuit is configured to control the deflection of the movable element based on sensor data from the position sensor. Reluctance actuator according to one of claims 1 to 15, characterized in that the movable element is in a desired position The rotational degree of freedom is movable. Reluctance actuator according to one of claims 1 to 16, characterized in that the movable element can be configured in two desired positions. is movable in rotational degrees of freedom, whereby the movement of the movable Elements are controlled in the two desired degrees of freedom by means of coupled magnetic circuits or by means of two decoupled magnetic circuits.

18. Reluctance actuator according to one of claims 1 to 17, characterized in that a movement of the movable element along undesired degrees of freedom is restricted by means of at least one bending element, by means of at least one mechanical bearing or by means of at least one magnetic bearing.

19. Fast Steering Mirror comprising the reluctance actuator according to any one of claims 1 to 18, wherein a reflective element of the Fast Steering Mirror is arranged on the movable element of the reluctance actuator.

20. Method for performing lifting / tilting movements of a movable element of a reluctance actuator, wherein the reluctance actuator has a magnetizable core, a coil for generating a magnetic flux is formed in the core, and comprises a movable element for lifting / tilting movements, characterized in that the reluctance actuator has at least one permanent magnet as a component and the movable element is moved by means of control of an excitation current for the coil such that the permanent magnet is moved relative to a ferromagnetic component of the reluctance actuator such that one of the components plunges into an opening of the other component.

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