EP3669208A1

EP3669208A1 - Scanning unit and method for scanning light

Info

Publication number: EP3669208A1
Application number: EP18765801.8A
Authority: EP
Inventors: Florian Petit; Mathias Müller
Original assignee: Blickfeld GmbH
Current assignee: Blickfeld GmbH
Priority date: 2017-08-17
Filing date: 2018-08-16
Publication date: 2020-06-24
Also published as: DE102017118776A1; DE102017118776B4; US20200218063A1; WO2019034210A1

Abstract

A scanning unit (100) for scanning light comprises a deflection element (110) with a mirrored surface (111) and at least one support element (121, 122) which extends on the plane defined by the mirrored surface (111) and which is designed to elastically couple the deflection element (110) to a fixed structure. The deflection element (110) is self-supporting, relative to the fixed structure (350), through a continuous angle of at least 200° of the extent of the mirrored surface (111). The scanning unit has at least one additional support element (131, 132) extending with an offset to the plane (901) defined by the at least one support element (121, 122), in order to elastically couple the deflection element (110) to the fixed structure (350). The scanning unit has a controller in order to control at least one actuator which can resonantly excite a torsion mode of the at least one support element (121, 122, 131, 132) and of the at least one additional support element (121, 122, 131, 132). Preferably, the at least one support element (121, 122) and the deflection element (110) are integrally formed and the at least one support element (121, 122) and the at least one additional support element (131, 132) are not integrally formed. Preferably, both the at least one support element (121, 122) and the at least one additional support element (131, 132) are designed as bar-type torsion springs. Preferably, the at least one support element (121, 122) and the at least one additional support element (131, 132) are interconnected by bonding at their respective contact surfaces (160) in an end region (141-1, 141-2) facing the fixed structure. Preferably, the actuator is provided at one end of the at least one support element (121, 122), facing the fixed structure, and comprises one or more piezoelectric bending actuators. The invention further relates to a method for producing a scanning unit (100).

Description

Scan unit and method for scanning light

TECHNICAL AREA

Various examples relate to a scanning unit for scanning light by means of a deflecting element. In various examples, at least one support element, which is configured to elastically couple the deflection element to a fixed structure, extends in a plane defined by a mirror surface of the deflection element.

BACKGROUND

The distance measurement of objects is desirable in various fields of technology. For example, in the context of autonomous driving applications, it may be desirable to detect objects around vehicles and, in particular, to determine a distance to the objects.

One technique for measuring the distance of objects is the so-called LIDAR technology (light detection and ranging, sometimes also LADAR). In doing so, e.g. pulsed laser light emitted from an emitter. The objects in the environment reflect the laser light. These reflections can then be measured. By determining the transit time of the laser light, a distance to the objects can be determined. In order to detect the objects in the environment spatially resolved, it may be possible to scan the laser light. Depending on the beam angle of the laser light different objects in the environment can be detected.

Various techniques are known to scan the light. For example, microelectromechanical (MEMS) techniques may be used. In this case, a micromirror is released in a frame structure, e.g. by reactive ion milling of silicon. See, e.g. EP 2 201 421 B1.

However, such techniques often have the disadvantage that the scan angle is comparatively limited. This means that the deflection of the light is comparatively limited. In addition, the production can be complicated. The scan module may also require a relatively large amount of space due to the frame structure. JP 2015-99270 A discloses a technique in which two torsion springs extend in a plane defined by a mirror surface. Such a structure has the disadvantage that the bending stiffness for bending perpendicular to this plane is a comparatively low.

SUMMARY

Therefore, there is a need for improved techniques to scan light. In particular, there is a need for such techniques that overcome or mitigate at least some of the above disadvantages.

This object is solved by the features of the independent claims. The dependent claims define embodiments. A scanning unit for scanning light comprises a deflecting element. The deflecting element comprises a mirror surface. The scanning unit also includes at least one support element. The at least one support member extends away from a periphery of the mirror surface. The at least one support element is arranged to elastically couple the deflection element with a fixed structure. The deflecting element is formed free-standing with respect to the fixed structure along a continuous circumferential angle of at least 200 ° of a circumference of the mirror surface.

In other words, therefore, the coupling of the deflecting element with the fixed structure can be restricted to a comparatively small area. In particular, a 2-point coupling on opposite sides, for example as described in US 2014 0300 942 A1, can be avoided. This makes the scan unit more compact and easier to manufacture. In addition, larger scan angles are possible. A LIDAR system could include such a scanning unit.

A method of operating a scanning unit to scan light includes driving at least one actuator. This is done for the resonant deflection of at least one support element. The at least one support element extends in a plane defined by a mirror surface of a deflection element. The deflecting element is formed free-standing with respect to the fixed structure along a continuous circumferential angle of at least 200 ° of a circumference of the mirror surface. A method for manufacturing a scanning unit for scanning light comprises: in a first etching process of a first wafer, producing a deflection element and at least one support element that extends away from the deflection element, in the first wafer; in a second etching process of a second wafer, producing at least one further support element in the second wafer; Bonding the first wafer to the second wafer; and cropping the deflection element, the at least one support element and the at least one further support element. The features and features set out above, which are described below, can be used not only in the corresponding combinations explicitly set out, but also in other combinations or isolated, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic plan view of a scanning unit according to various examples.

FIG. 2 is a schematic perspective view of the scanning unit according to the example of FIG. 1.

FIG. 3 schematically illustrates the deflection of a deflection element, a scanning unit by a torsion of four support elements of a scanning unit according to various examples. FIG. 4 is a schematic perspective view of a scanning unit according to various examples, wherein the mirror surface of the corresponding deflecting element has a recess in which a plurality of supporting elements are arranged.

FIG. 5 is a schematic perspective view of the scanning unit according to the example of FIG. 4th

FIG. FIG. 6 is a schematic plan view with a sectional view of the scanning unit according to the example of FIGS. 4 and 5.

FIG. 7 schematically illustrates a scanning unit according to various examples. FIG. 8 schematically illustrates a scanner having two scan units according to various examples.

FIG. 9 schematically illustrates a scanner having two scan units according to various examples.

FIG. 10 schematically illustrates a scanner with two scan units according to various examples. FIG. 1 1 schematically illustrates a LIDAR system according to various examples. FIG. 12 schematically illustrates a LIDAR system according to various examples. FIG. 13 is a flowchart of an example method.

FIG. 14 is a flowchart of an example method.

DETAILED DESCRIPTION OF EMBODIMENTS

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in detail in conjunction with the drawings.

Hereinafter, the present invention will be described with reference to preferred embodiments with reference to the drawings. In the figures, like reference characters designate the same or similar elements. The figures are schematic representations of various embodiments of the invention. Elements shown in the figures are not necessarily drawn to scale. Rather, the various elements shown in the figures are reproduced in such a way that their function and general purpose will be understood by those skilled in the art. Connections and couplings between functional units and elements illustrated in the figures may also be implemented as an indirect connection or coupling. Functional units can be implemented as hardware, software or a combination of hardware and software. Hereinafter, various techniques for scanning light will be described. For example, the techniques described below may enable 1-D or 2-D scanning of light. Scanning may refer to repeated emission of the light at different angles of radiation. For this purpose, the light can be deflected by a deflecting element of a scanner once or several times.

The deflecting element may be formed for example by a mirror. The deflector could also include a prism instead of the mirror. A mirror surface can be provided.

The scanning may indicate the repeated scanning of different points in the environment by means of the light. For this purpose, different emission angles can be implemented sequentially. The sequence of radiation angles may be determined by a superposition figure when e.g. two degrees of freedom of movement temporally and optionally spatially superimposed to be used for scanning. For example, For example, the amount of different points in the environment and / or the amount of different radiation angles may define a scan area. Larger scan areas correspond to larger scan angles. In various examples, the scanning of light by the temporal superposition and optionally a local superposition of two movements corresponding to different degrees of freedom of at least one support element can take place. Then a 2-D scan area is obtained. Sometimes the overlay figure is also referred to as a Lissajous figure. The overlay figure can describe a sequence with which different radiation angles are converted by the elastic, reversible movement of at least one support element.

In various examples, it is possible to scan laser light. In this case, for example, coherent or incoherent laser light can be used. It would be possible to use polarized or unpolarized laser light. For example, it would be possible for the laser light to be pulsed. For example, short laser pulses with pulse widths in the range of femtoseconds or picoseconds or nanoseconds can be used. For example, a pulse duration can be in the range of 0.5-3 nanoseconds. The laser light may have a wavelength in the range of 700-1800 nm, for example, in particular 1550 nm or 950 nm. For the sake of simplicity, reference will now be made primarily to laser light; however, the various examples described herein may also be used to scan light from other light sources, for example broadband light sources or RGB light sources. RGB light sources herein generally refer to light sources in the visible spectrum, the color space being due to interference several different colors - for example, red, green, blue or cyan, magenta, yellow, black - is covered.

In various examples, at least one support element will be used to scan light having a shape and / or material induced elasticity. Therefore, the at least one support element could also be referred to as a spring element or elastic suspension. The support element has a movable end. Then at least one degree of freedom of movement of the at least one support element can be excited, for example a torsion and / or a transverse deflection. In this context, the support element is also referred to as a torsion spring element or flexure spring element (English, flexure spring element). In a torsion spring element, the natural frequency of the torsional mode is lower than the eigenmode of the bending mode; and in a bending spring element, the natural frequency of the bending mode is lower than the natural frequency of the tapping spring. By such an excitation of a movement, a deflection element, which is connected to the movable end of the at least one support elements, are moved or deflected.

For example, it would be possible to use more than a single support element, e.g. two or three or four support elements. These may optionally be arranged symmetrically with respect to each other.

Each of the at least one support member may be straight between the movable end and an opposite end to which the respective support member is connected to an actuator, i. in the rest position have no or no significant curvature.

The at least one support element may e.g. have a length between the two ends, e.g. in the range of 2 mm to 15 mm, for example in the range of 3 mm to 10 mm or for example in the range of 5 mm to 7 mm.

In some examples, it would be possible for the at least one support element to be produced by means of MEMS techniques, ie to be produced by means of suitable lithographic process steps, for example by etching from a wafer. For example, reactive ion milling could be used to release from the wafer. A silicon on insulator (SOI) wafer could be used. As a result, for example, the dimensions of the at least one support element could be defined perpendicular to the length when the insulator of the SOI wafer is used as an etch stop. For example, the movable end of at least its support member could be moved in one or two dimensions, with temporal and spatial superposition of two degrees of freedom of movement. One or more actuators can be used for this purpose. For example, it would be possible that the movable end is tilted relative to a fixing of the at least one support element; this results in a curvature of the at least one support element. This may correspond to a first degree of freedom of the movement; this can be referred to as transversal mode (or sometimes as wiggle mode or flexure mode). Alternatively or additionally, it would be possible for the movable end to be rotated along a longitudinal axis of the support element (torsion mode). This may correspond to a second degree of freedom of movement. By moving the movable end can be achieved that the deflecting element is deflected and thus laser light is emitted at different angles. This allows an environment to be scanned with the laser light. Depending on the strength of the movement of the movable end or the deflection of the deflecting element, scan areas of different sizes can be implemented.

In each of the various examples described herein, it is possible to excite the torsional mode alternatively or in addition to the transverse mode, i. a temporal and spatial superimposition of the torsional mode and the transverse mode would be possible. This temporal and local overlay can also be suppressed. For example, In some examples, the torsional mode can be specifically excited and transversal modes can be damped; the actuator can be set up accordingly, e.g. by using a control loop. In other examples, other degrees of freedom of motion could also be implemented.

For example, the deflection element may comprise a prism or a mirror. For example, the mirror could be implemented by a wafer, such as a silicon wafer, or a glass substrate. For example, the mirror could have a thickness in the range of 0.05 μm - 0.1 mm. For example, the mirror could have a thickness of 25 μηη or 50 μηη. For example, the mirror could have a thickness in the range of 25 μηη to 75 μηη. For example, the mirror could be square, rectangular or circular. For example, the mirror could have a diameter of 3 mm to 12 mm, or in particular 8 mm. The mirror has a mirror surface. The opposite back can be structured, eg with ribs or other stiffening structures. In general, such techniques can be used to scan light in a wide variety of applications. Examples include endoscopes and RGB projectors and printers and laser scanning microscopes. In various examples, LIDAR techniques can be used. The LIDAR techniques can be used to perform a spatially resolved distance measurement of objects in the environment. For example, the LIDAR technique may include transit time measurements of the laser light between the mirror, the object, and a detector. In general, such techniques can be used to scan light in a wide variety of applications. Examples include endoscopes and RGB projectors and printers. In various examples, LIDAR techniques can be used. The LIDAR techniques can be used to perform a spatially resolved distance measurement of objects in the environment. For example, the LIDAR technique may include transit time measurements of the laser light. In connection with a LIDAR technique, it may be possible to use the scanning unit both for emitting laser light and for detecting laser light. This means that the detector aperture can also be defined via the deflecting element of the scanning unit. Such techniques are sometimes referred to as spatial filtering. Spatial filtering may allow a particularly high signal-to-noise ratio to be achieved because light is selectively collected from the direction in which the laser light is also emitted becomes. This avoids collecting background radiation from other areas where no signal is expected. Due to the high signal-to-noise ratio, particularly long ranges can be achieved.

Various examples are based on the finding that it can often be desirable to use comparatively large mirrors in order to use a large detector aperture in conjunction with the spatial filtering and thus to obtain a particularly high signal-to-noise ratio. At the same time, however, it may be desirable to also implement a particularly large scan angle - for example greater than ± 80 °. This may obviate the use of imaging optics in the emitted beam path downstream of the post-scanner optics, making the system simple and compact. Furthermore, various examples are based on the knowledge that it may be desirable to provide scanning units that are particularly easy to manufacture-in particular with a high degree of automation, for example by wafer structuring by means of lithographic processes. Various examples further underlie the finding that it may often be desirable to use comparatively large mirrors to emit laser light along a low divergence beam path without collimating optics between the mirror and the environment (ie, in a post-scanner array) need. A small divergence can be achieved in particular by the fact that a large transmission aperture - defined by the mirror - is available.

Such and other problems are solved by the techniques described herein.

FIG. 1 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 1 is a schematic plan view of the scanning unit 100. The scanning unit 100 comprises a deflection element 110 having a mirror surface 11 (in the illustration of FIG. 1, the mirror surface 11 1 lies in the plane of the drawing, i.e. the XY plane). The sides 1 12, 1 13, 1 14, 1 15 of the mirror surface 1 1 1 are shown in FIG. 1 also shown and form a periphery of the mirror surface 1 1 1.

While the mirror surface 1 1 1 in the example of FIG. 1 is formed rectangular, the mirror surface 1 1 1 in other examples could also have a different shape, such as elliptical or circular.

Typical side lengths 353 of the mirror surface 1 1 1 are in the range of 3 mm to 15 mm, optionally in the range of 5 mm to 10 mm. In the example of FIG. 1, the scanning unit 100 also comprises two support elements 121, 122. The support elements 121, 122 are each connected to the deflection element 110 at a movable end 321. At an end 322 opposite the movable end 321, the supporting elements 121, 122 can be connected to an actuator, for example with bending piezoactuators (not shown in FIG. At the end 322, the support elements 121, 122 - for example via the actuator - connected to a fixed structure 350. The fixed structure 350 defines the reference coordinate system against which a movement or deflection of the deflecting element 1 10 by elastic deformation of the support members 121, 122 for scanning light is possible. FIG. 1 illustrates the deflecting element 1 10 in a rest position. This means that there is no elastic deformation of the support elements 121, 122. For example, the corresponding actuator could be off. From FIG. 1 it can be seen that in the rest position the support elements 121, 122 are straight, between the ends 321 and 322. Corresponding central axes 182, 183 of the support elements 121, 122 are shown in FIG. 1 shown. The length 352 of the support members 121, 122 along the Y-axis is typically in the range of 3 mm - 15 mm. The width of the support elements 121, 122 along the X-axis is typically in the range of 50 μηη - 250 μηη. The support members 121, 122 may have a square cross-section. The support members 121, 122 may thus be rod-shaped and thus as torsion springs.

In FIG. 1, a torsion axis 181 is also shown. By twisting and rotation of the support elements 121, 122 along their central axis 182, 183 or with respect to the torsion axis 181 can cause a deflection or in particular a tilting of the deflecting element 1 10 and thus the mirror surface 1 1 1; the axis of rotation corresponds to the torsion axis 181 (in the example of FIG. 1, the mirror surface 11 would be tilted to the left of the torsion axis 181 into the drawing plane and to the right of the torsion axis 181 out of the plane of the drawing). This may make it possible to redirect laser light.

In the example of FIG. 1 it can be seen that the deflecting element 1 10 is formed along a large continuous peripheral angle 380 of almost 360 ° freestanding relative to the fixed structure 350. In general, the deflecting element along a continuous peripheral angle 380 of at least 200 ° of the circumference of the mirror surface 1 1 1 could be free-standing with respect to the fixed structure 350.

This means in particular that only the side 1 14 of the deflecting element 1 10 is coupled to the fixed structure 350, d. H. the remaining pages 1 12, 1 13, 1 15 are freestanding. On the other pages 1 12, 1 13, 1 15 is no connection - for example, more elastic support elements - with the fixed structure 350. The remaining pages 1 12, 1 13, 1 15 are free from the environment.

By such a coupling of the deflecting element 110 with the fixed structure 350, it can be achieved that particularly large deflections of the deflecting element become possible. As a result, particularly large scan areas can be achieved. For example, scan angles of at least ± 45 °, optionally at least ± 80 °, optionally of at least ± 120 °, further optionally of at least ± 180 °. The mirror surface 1 1 1, for example, could have side lengths 353 in the range of 3 mm - 15 mm. The side lengths 353 may be in the range of 20% - 500% of the length of the support members 352. As a result, on the one hand large deflection of the deflecting element 1 10 can be achieved; At the same time, however, it can be achieved that the inert mass of the deflecting element 10 is not disproportionately large compared to the elasticity of the supporting elements.

In the example of FIG. 1, the deflecting element 1 10 and the support members 121, 122 integrally formed. For example, it would be possible for the support elements 121, 122 and the deflection element 1 10 to be released from a common wafer in a common lithography / etching process. In the region of the transition between the deflecting element 1 10 and the support members 121, 122 therefore there is no material transition or a material inhomogeneity; the corresponding region or the remaining regions can in particular be produced from a monocrystalline wafer.

Through such techniques, an integrated manufacturing can be achieved. In addition, the tolerance to tension in the region of the transition from the deflecting element 1 10 to the support members 121, 122 i. Be especially close to the end of 321. This allows large scan angles without damaging the material.

Also an end portion 141 - the e.g. can be configured to engage with an actuator - is integrally formed with the support members 121, 122 and the deflection element 1 10. In FIG. 1, the two support elements are arranged parallel to each other. In general, it would be possible for the central axes 182, 183 of the support members 121, 122 to enclose an angle no greater than 20 °, optionally not greater than 5 °, further optionally not greater than 1 °. Such an arrangement of the two support elements 121, 122, a parallel kinematics can be generated, which allows large scan angle. The deformation of the two support elements 121, 122 may correspond to each other.

The parallel kinematics is further promoted by the fact that the distance 351 between the central axes 182, 183 in the region of the movable end 321 is comparatively small. For example, the distance 351 could be much smaller than the length 352 of the support elements and also also much smaller than the circumferential length of the mirror surface 1 1 1. For example, it would be possible that this distance 351 is not greater than 40% of the circumferential length (i.e., the sum of the lengths of the sides 1 12-1 15), optionally not greater than 10%, further optionally not greater than 5%.

In addition to the parallel kinematics through the two support elements 121, 122, the robustness against external shock can also be promoted by using two support elements. This means - despite the large scanning angle - a high degree of robustness against shock can be achieved. In order to further promote this robustness and to reduce non-linear effects due to the anisotropic geometry, further support elements 121, 122 may also be provided. A corresponding example is shown in FIG. 2 shown.

FIG. 2 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 2 is a perspective view.

In the example of FIG. 2, the scanning unit 100 comprises a total of four support elements 121, 122, 131, 132. The support elements 121, 122 are in the Z direction, i. perpendicular to the mirror surface 1 1 1, offset from the support members 131, 132 arranged. In particular, the support elements 131, 132 are also offset from the plane defined by the mirror surface 1 1 1 level. The support members 131, 132 are in the rest position in the z-direction offset from the deflecting element 1 10. The support members 131, 132 are connected via an interface element 142 with the rear side of the deflecting element 1 10 and are therefore also adapted to the deflecting elastic with the Coupling fixed structure 350.

The various support elements 121, 122, 131, 132 or their central axes (not shown in FIG. 2 for reasons of clarity) are all parallel to one another. In general, however, the central axes of the support members 121, 122, 131, 132 could also include comparatively small angles, e.g. Angles that are not greater than 10 ° or greater than 5 ° at rest. As a result, the parallel kinematics of the support elements 121, 122, 131, 132 is promoted. From FIG. 2, it can be seen that the plane (plane 901, see also FIG. 3) in which the support elements 121, 122 are arranged offset relative to the plane in which the support elements 131, 132 are arranged (plane 902, cf. 3). These two levels are in the in FIG. 2, but could generally enclose an angle no greater than 5 ° with each other, optionally not greater than 1 °. Due to the substantially parallel arrangement of the XY planes, the parallel kinematics of the support elements 121, 122, 131, 132 can be conveyed.

In the example of FIG. 2, the support elements 121, 122, the end portion 141 -1, as well as the deflecting element 1 10 integrally formed with the mirror surface 1 1 1, ie exempt from the same wafer, so that gluing, etc. is unnecessary. The support elements 131, 132, the end portion 141 -2, and an interface element 142 are also integrally formed. The combined, one-piece part 131, 132, 141 -2, 142 is connected at contact surfaces 160 with the combined, one-piece part 141 -1, 121, 122, 110, eg by means of adhesive, wafer bonding, anodic bonding, fusion bonding, direct -Bonding, eutectic bonding, thermocompression bonding, adhesive bonding, etc. The bonding could be done, for example, at a time at which the parts 131, 132, 141 -2, 142 and 141 -1, 121, 122, 1 10 still are not released from the corresponding wafer; ie, two wafers, each carrying one of the two parts, eg in an array, could be brought into contact with each other to perform the bonding. Only then can the structures be released. By such a two-part production, the scanning unit 100 can be made particularly simple and robust. At the same time, 3-D structuring in the X-direction, Y-direction and Z-direction can produce a high degree of robustness against shock, high resonance frequencies and large scan angles. From FIG. 2 it can be seen that a thickness of the support elements 121, 122, 131, 132 perpendicular to the mirror surface 1 1 1 - ie in the Z direction - is smaller than a thickness of the deflecting element 1 10 in the z direction. This can promote a high elasticity of the support elements 121, 122, 131, 132 - while at the same time a deformation of the mirror surface 1 1 1 is reduced during movement. The thickness of the support elements 121, 122, 131, 132 in the z-direction may be defined by a suitable etch stop during the etching process for release from the wafer. For example, an insulator layer in an SOI wafer may be used as an etch stop.

The diverter could have a backside structuring, i. on the opposite side of the mirror surface 1 1 1, for. Have lamellas or rib structure (not shown in FIG. 2). This reduces the inertial mass of the deflecting element 10 and thus increases the resonance frequency; On the other hand, a deformation of the mirror surface 1 1 1 is avoided during movement.

FIG. FIG. 3 illustrates aspects relating to a torsional mode 501, with which a deflection of the deflecting element 110 is made possible. In the example of FIG. 3 are support members 121, 122 and 131, 132 provided, according to the example of FIG. 2 (in this case, the idle state is shown by the solid line in FIG. 3 and the deflected state by the dashed line). The support members 121, 122, 131, 132 are arranged symmetrically with respect to the torsion axis 181; therefore non-linear effects are avoided. As a result, large deflections 502 are possible, for example, up to 180 °. This allows for large scan angles. FIG. 3 also illustrates aspects relating to the arrangement of the support elements 121, 122 and 131, 132. The support elements 121, 122 extend in the rest position in the plane 901. In this plane, the mirror surface 1 1 1 extends, see. FIG. 2. The support members 131, 132 extend in contrast in the plane 902, wherein the plane 902 is parallel but offset from the plane 901.

In addition, the support members 121, 131 extend in the rest position in the plane 905; and the support elements 122, 132 extend in the rest position in the plane 906. The planes 905, 906 are parallel to each other but offset.

It would generally be possible for more than two support elements 121, 122, 131, 132 to be provided per level 901, 902.

FIG. 4 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 4 is a perspective view.

While in the example of FIG. 4 four support members 121, 122, 131, 132 are present, it would also be possible in other examples, that a smaller or larger number of support elements is present.

The example of FIG. 4 basically corresponds to the example of FIG. 2. In the example of FIG. 4, the deflection unit 1 10 and in particular the mirror surface 1 1 1, however, a recess 1 19. For example, it would be possible for the support members 121, 122 to extend generally along at least 40% of their length 352 in the indentation 1 19 extend, further optionally along at least 60% of their length, further optionally along at least 80% of their length.

The pure torsion 501 about the torsion axis 181 avoids a collision between the support elements 121, 122, 131, 132 and the insides of the recess 19 (see FIG.

In the scenario of FIG. 4, the depth 355 of the recess 1 19 dimensioned such that the indentation 1 19 starting from the side 1 14 towards a center of the mirror surface 1 1 1 and also over the center of the mirror surface 1 1 1 out to the side of 1 13 extends. In this way, a particularly compact construction of the scanning unit 100 can be made possible. In general, it would be possible for the recess 19 to have a depth 355, which is not less than 20% of the respective side lengths of the sides 1 12, 1 15, to which the indentation 1 19 extends in parallel, is optionally not less than 50%, further optionally not less than 70%. With a circular mirror surface, the depth 355 of the recess 1 19 can not be less than 20% (or optionally 50% or further optionally 70%) of a diameter of the mirror surface 1 1 1.

FIG. FIG. 5 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 5 is a perspective view. The scanning unit 100 according to the example of FIG. 5 corresponds to the scanning unit according to the example of FIG. 4. In FIG. 5 is a rear perspective view.

In FIG. 5, in particular, the back 1 16 of the deflecting element 1 10 is shown. From FIG. 5 it can be seen that the deflecting element 1 10 has a back-side structuring. In particular, 1 16 ribs are provided on the back. The ribs increase the rigidity of the deflecting element 1 10 and thus avoid deformation of the mirror surface 1 1 1 during movement. On the other hand, by providing the back side patterning, the inertial mass of the deflecting member 110 is reduced, so that the resonance frequency of the torsional mode 501 is comparatively large. This can enable high scanning frequencies and thus ultimately high refresh rates of a LIDAR measurement.

In FIG. 5, the recess 1 19 19 is shown.

FIG. 6 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 6 is a plan view (left in FIG.6) and a sectional view taken along the axis A-A (right side in FIG.6). The scanning unit 100 according to the example of FIG. 6 corresponds to the scanning unit 100 according to the examples of FIGS. 4 and 5.

In particular, it can be seen in the sectional view that the support element 121 is formed integrally with the deflection element 110; while the support member 131 is not formed integrally with the deflecting element 1 10. This means, for example, that the support element 121 and the support element 131 are not produced from the same wafer, but are glued to one another, for example, or are connected to one another by a wafer bonding process. In FIG. 6, the contact surfaces 160 are shown. FIG. FIG. 7 illustrates aspects relating to a scanning unit 100 according to various examples. FIG. 7 is a schematic view. In particular, FIG. 7 Aspects with respect to the fixed structure 350, which defines a free space 351, in which the deflecting element 1 1 1 at deflection 502 - for example by exciting the torsion 501 by means of a suitable actuator - can move. In the example of FIG. 7, the deflecting element 10 is shown in the idle state (solid line in FIG. 7) and in the deflected state (dashed line in FIG. From FIG. 7 it can be seen that the free space 351 is formed in order to allow comparatively large deflections 502 of the deflecting element 110. As a result, large deflection angle 510 of light 361 can be made possible. For example, the free space 351 could be formed to allow a deflection of the deflecting element 110 of at least ± 45 °, optionally to allow at least ± 80 °, further optionally of at least ± 120 °, further optionally of at least ± 180 °. This may be possible in particular with side lengths 353 in the range of 3 mm - 15 mm.

Such a large clearance 351 is achieved, in particular, by the fact that the fixed structure 350 is not formed in one piece with the deflection element 110. In particular, the fixed structure 350 does not form an integrally fabricated frame, as e.g. in the context of conventional MEMS techniques is the case. Therefore, in the techniques described herein, it is not necessary to expose the clearance 351 in a wafer, for example, by etching processes; Rather, the free space 351 may be formed by suitably dimensioning a housing defined by the fixed structure 350.

FIG. Figure 7 also illustrates aspects related to redirecting light. In the example of FIG. 7, the light 361 strikes the mirror surface 1 1 1 in the rest position of the deflecting element 1 10. This means that the light 361 propagates from a light source 360 - for example a laser - to the mirror surface 11 1 1 along a beam path which is aligned in the Z direction. However, sliding angles of incidence would also be possible, i. Beam paths that are tilted with respect to the Z direction.

In FIG. 7 shows the corresponding deflection angle 510 which is achieved on the basis of the deflection 502 of the mirror surface 11 (in FIG. 7 the mirror surface is perpendicular to the plane of the drawing in the rest position and is rotated into the drawing plane with increasing deflection 502).

FIG. 8 illustrates aspects relating to a scanner 90. The scanner 90 includes a first scan unit 100-1 and a second scan unit 100-2. The two scanning units 100-1, 100-2 may be designed in accordance with the examples discussed above (in FIG. 8, the scanning units 100-1, 100-2 are shown only schematically). From FIG. 8 it can be seen that the laser light 361 is first deflected starting from the laser light source 360 through the mirror surface 1 1 1 of the scanning unit 100-1 and is then deflected by the mirror surface 11 of the scanning unit 100-2. This allows a 2-D superimposed deflection of the laser light 361 done so that the laser light 361 2-D can be scanned. A corresponding overlay figure is obtained which defines the scan area.

In FIG. 8, the shortest distance 380 between the circumference of the mirror surface 11 of the scanning unit 100-1 and the circumference of the mirror surface 11 of the scanning unit 100-2 is also shown. The mirror surface 1 1 1 of the scanning unit 100-1 is in the example of FIG. 8 tilted by 45 ° with respect to the mirror surface 1 1 1 of the scanning unit 100-2. By such an arrangement, a comparatively short distance 380 can be achieved; This allows high integration of the scanner 90. The distance 380 must be large enough dimensioned so that no deflection occurs at deflection 501 of the deflecting elements 1 10.

FIGs. 9 and 10 also illustrate aspects related to a scanner 90. In the examples of FIGS. 9 and 10, the distance 380 between the peripheries of the mirror surfaces 1 1 1 of the two scanning units 100-1, 100-2 compared to the example of FIG. 8 be further reduced. In the examples of FIGS. 9 and 10, this is made possible by the sliding angle of incidence of the light 361.

In the example of FIG. 9 have the planes defined by the mirror surfaces 1 1 1 of the scanning units 100-1, 100-2 at an angle of 90 ° to each other. In the example of FIG. 10, the planes defined by the mirror surfaces 11 of the scanning units 100-1, 100-2 have an angle of 0 ° to one another, that is, they are aligned with one another. In general, these planes could also be slightly tilted, ie, for example, have an angle that is not greater than 5 °. In the example of FIG. 10, another deflecting element 220 with a further mirror surface (hidden in the view of FIG. 10 and facing the mirror surfaces 11 1 of the scanning units 100 - 1, 100 - 2) is used. The deflecting element 220 is not deflected together with the deflecting elements 110 of the scanning units 100-1, 100-2, ie is stationary with respect to the fixed structure 350. The mirror surface of the deflecting element 220 is parallel to the mirror surfaces 11 1 of the scanning units 100-1 However, 100-2 could generally include a small angle of, for example, not more than 5 ° with the mirror surfaces 1 1 1. In FIGS. 8-10, the circumferences of the mirror surfaces 1 1 1 of the two scanning units 100-1, 100-2 can generally have a distance 380 from one another which is less than 25% of the circumferential length of the circumference of the mirror surfaces 11, preferably less than 10%. , continue optionally less than 2%. Such short distances 380 may allow for a small sizing of the scanner 90 and thus flexible deployment in a variety of applications. Typically, by means of the implementation according to FIG. 10, the shortest distances 380 are achieved.

FIG. 1 1 illustrates aspects related to a LIDAR system 80. The LIDAR system 80 includes a scanner 90 that may be configured, for example, according to the various implementations described herein. The scanner 90 may include one or two or more scan units (not shown in FIG. 11).

The LIDAR system 80 also includes a light source 360. For example, the light source 360 could be formed as a laser diode that emits pulsed laser light 361 in the infrared region with a pulse length in the nanosecond range. The light 361 of the light source 360 can then impinge on one or more mirror surfaces 1 1 1 of the scanner 90. Depending on the orientation of the deflecting element (s), the light 361 is deflected at different angles 510. The light emitted by the light source 361 is often referred to as a primary light. This implements different scanning angles.

The primary light may then hit an environment object of the LIDAR system 80. That such reflected primary light is called secondary light. The secondary light may be detected by a detector 82 of the LIDAR system 80. Based on a transit time - which can be determined as a time offset between the emission of the primary light by the light source 81 and the detection of the secondary light by the detector 82 -, by means of a controller 4001, a distance between the light source 361 and the detector 82 and the surrounding object be determined.

In some examples, the emitter aperture may be equal to the detector aperture. This means that the same scanner 90 can be used to scan the detector aperture. For example, the same deflecting elements can be used to emit primary light and to detect secondary light. Then, a beam splitter may be provided to separate primary and secondary light. Such techniques can make it possible to achieve a particularly high sensitivity. This is because the detector aperture can be aligned and confined to the direction from which the secondary light arrives. Ambient light is reduced by the spatial filtering, because the detector aperture can be made smaller. In addition, in addition to this distance measurement, a lateral position of the environment object can also be determined, for example by the controller 4001. This can be done by monitoring the position or orientation of the one or more deflection elements of the scanner 90. In this case, the position or orientation of the one or more deflection elements at the moment of the impact of the light 361 correspond to a deflection angle 510; From this it is possible to draw conclusions about the lateral position of the environment object.

FIG. 12 illustrates aspects of a LIDAR system 80. The LIDAR system 80 includes a controller 4001 that could be implemented, for example, as a microprocessor or application specific integrated circuit (ASIC). The controller 4001 could also be implemented as a Field Programmable Array (FPGA). The controller 4001 is configured to output control signals to a driver 4002. For example, the control signals could be output in digital or analog form. These control signals can be set up to excite the torsional mode of the support elements of the scanner 90 and, for example, to dampen one or more transverse modes of the support elements.

The driver 4002 is in turn configured to generate one or more voltage signals and output them to corresponding electrical contacts of the one or more actuators for driving a resonant motion of the support members. Typical amplitudes of the voltage signals range from 50V to 250V. Examples of actuators include magnets, interdigital electrostatic comb structures, and bending piezoactuators.

The actuators 310, 320 are in turn coupled to the scanner 90. As a result, one or more deflecting elements of the scanner 90 are deflected. Thereby, the surrounding area of the scanner 90 can be scanned with light 361. The actuators are configured according to various examples to resonantly excite the torsional mode of the support elements of the scanner 90.

In FIG. 12 is further shown as having a coupling between the controller 4001 and a sensor 662. The sensor is arranged to monitor the deflection of the deflecting element or the deflecting elements. The controller 4001 may be configured to drive the actuator or actuators 310, 320 based on the signal from the sensor 662. By such techniques, the deflection 501 may be monitored by the controller 4001. If needed, the controller 4001 can control the Adjust driver 4002 to reduce drift between a desired deflection and an observed deflection.

For example, it would be possible for a closed-loop control to be implemented. For example, the control loop could include the desired amplitude of the movement as a reference variable. For example, the control loop could include the actual amplitude of the movement as a controlled variable. In this case, the actual amplitude of the movement could be determined based on the signal of the sensor 662. In particular, by means of the control loop, the torsional mode can be specifically stimulated in a resonant manner and the transverse mode can be specifically damped.

FIG. 13 is a flowchart of an example method. For example, the method of FIG. 13 are executed by the controller 4001 of the LIDAR system 80. In block 5001, at least one actuator is actuated in order to resonantly deflect at least one support element, which extends in a plane defined by a mirror surface of a deflecting element, with respect to a fixed structure. For example, a torsion could be excited, e.g. resonant. In this case, the deflecting element is formed free-standing with respect to the fixed structure along a continuous circumferential angle of at least 200 ° of a circumference of the mirror surface.

FIG. 14 is a flowchart of an example method. FIG. Figure 14 illustrates aspects relating to the fabrication of a scanning unit. For example, according to the method of FIG. 14, a scanning unit, as described in connection with FIGS. has been described.

First, in block 501 1, a first wafer is processed in a first etching process. In the first etching process, a deflecting element and at least one supporting element are produced in the first wafer. The at least one support element extends away from the deflection element. For example, the at least one support element could extend away from a circumference of the deflection element. For example, the at least one support element could extend in a plane with the deflection element; For example, the at least one support element could extend in a plane defined by a mirror surface of the deflection element (wherein mirroring of the mirror surface, for example by depositing gold or aluminum, can only take place below). Then, in block 5012, a second wafer is processed in a second etching process. In the second etching process, at least one further support element is produced in the second wafer. The at least one further support element may be designed to be complementary to the support element in the first wafer. Corresponding techniques are, for example, above with respect to FIGS. 4-6 described.

Then in block 5013 the bonding of the first wafer to the second wafer takes place. For example, in the context of the at least one support element of block 501 1 and the at least one further support element of block 5012, suitable contact surfaces may be defined at the ends of the support elements that allow bonding (see FIG. 2, as well as 142 with 1 19). For example, anodic bonding etc. would be possible.

Then, in the example of FIG. 14 in block 5014 the cropping of the scanning unit defined in this way. In other examples, the cropping could also occur before block 5013.

In summary, techniques have been described above in which one or more support elements are mounted on one side of a mirror surface. Characterized a parallel kinematics is promoted in the elastic actuation of the corresponding deflection. If one or more support elements are mounted only on one side of the mirror surface, on the one hand, the area consumption of the structure on the wafer increases. Due to the one-sided suspension, however, the deflecting element can be mounted in the scanner on only one side and does not require a stiff holding frame. This allows the deflector to be suspended freely, which simplifies the suspension and allows large movements.

Of course, the features of the previously described embodiments and aspects of the invention may be combined. In particular, the features may be used not only in the described combinations but also in other combinations or per se, without departing from the scope of the invention.

For example, techniques using multiple support members have been described above. In some examples, however, only a single support element could be used. Furthermore, various techniques have been described above relating to the movement of scanning units in conjunction with LIDAR measurements. Appropriate However, techniques can also be used in other applications, eg for projectors or laser scanning microscopes, etc.

Claims

A scanning unit (100, 100-1, 100-2) for scanning light (361) comprising:

- A deflecting element (1 10) with a mirror surface (1 1 1),

at least one support element (121, 122) extending away from a circumference of the

Mirror surface (1 1 1) extends in a plane (901) and is adapted to the

Deflecting element (1 10) to be elastically coupled to a fixed structure (350), wherein the mirror surface (1 1 1) also extends in the plane (901),

at least one further support element (131, 132) which extends offset to the plane (901) defined by the at least one support element (121, 122) and which is adapted to elastically engage the deflection element (110) with the fixed structure (350 ), and

- A controller (4001) which is adapted to control at least one actuator (310, 320) to a torsional mode of the at least one support member (121, 122, 131, 132) and the at least one further support member (121, 122, 131 , 132) resonantly stimulate,

wherein the deflecting element (110) along a continuous peripheral angle (380) of at least 200 ° of a circumference of the mirror surface (1 1 1) free-standing with respect to the fixed structure (350) is formed.

2. scanning unit (100, 100-1, 100-2) according to claim 1,

wherein the at least one support element (121, 122) comprises a first support element (121, 122) and a second support element (121, 122),

wherein the at least one further support element (131, 132) is another first

Support member (131, 132) and a further second support member (131, 132).

3. scanning unit according to claim 2,

wherein the first support element (121, 122) and the first further support element (131, 132) lie in a first plane (905),

wherein the second support element (121, 122) and the further second support element (131, 122)

132) lie in a second plane (906),

wherein the first plane (905) and the second plane (906) enclose an angle of not greater than 5 ° with each other, optionally not greater than 1 °. 4. scanning unit (100, 100-1, 100-2) according to claim 2 or 3,

wherein an end (321) of the first support element (121, 122) adjoining the deflection element (110) and an end (321) adjacent to the deflection element (110) of the second support member (121, 122) have a distance (351) to each other, which are not greater than 40% of the length of the circumference of the mirror surface (1 1 1).

5. scanning unit (100, 100-1, 100-2) according to one of the preceding claims,

wherein the at least one further support element (131, 132) in another

Plane (902) which is parallel to the plane (901) defined by the at least one support element (121, 122).

6. Scan unit according to one of the preceding claims,

wherein the at least one support element (121, 122) and the deflection element (1 10) are integrally formed,

wherein the at least one support element (121, 122) and the at least one further support element (131, 132) are not formed in one piece. 7. Scan unit according to one of the preceding claims,

wherein a central axis (182) of the first support element (121, 131) and a central axis (183) of the second support element (122, 132) in the state of rest enclose an angle which is not greater than 20 °, optionally not greater than 5 °, further optional is not greater than 1 °.

8. Scan unit according to one of the preceding claims,

wherein a length (352) of each of the at least one support member (121, 122) or each of the at least one further support member (131, 132) is in the range of 3 mm to 15 mm, and / or

wherein a width of each of the at least one support member (121, 122) or each of the at least one further support member (131, 132) is in the range of 50 μηη to 250 μηη.

9. Scan unit according to one of the preceding claims,

wherein a cross section of each of the at least one support member (121, 122) and / or each of the at least one further support member (131, 132) is square.

10. Scan unit according to one of the preceding claims,

wherein the at least one support element (121, 122) and the at least one further support element (131, 132) are each formed as rod-shaped torsion springs. 1 1. Scan unit according to one of the preceding claims,

wherein the at least one actuator (310, 320) on one of the fixed structure

facing the end of the at least one support element (121, 122) is arranged and one or more Biegepiezoaktuatoren comprises. 12. Scan unit according to one of the preceding claims,

wherein the at least one support element (121, 122) and the at least one further support element (131, 132) are arranged parallel to one another.

13. Scan unit according to one of the preceding claims,

wherein the at least one support element (121, 122) and the at least one further

Supporting element (131, 132) in each case in one of the fixed structure (350) facing end portion (141 -1, 141 -2) are connected to one another at a contact surface (160) by means of bonding.

14. Scan unit according to one of the preceding claims,

wherein the at least one further support element (131, 132) via a

Interface element (142) with one of the mirror surface (1 1 1) opposite the rear side of the deflecting element (142) is connected.

15. Scan unit according to one of the preceding claims,

wherein a thickness of the at least one support element (121, 122) perpendicular to

Mirror surface (1 1 1) is smaller than a thickness of the deflecting element (1 10) perpendicular to the mirror surface (1 1 1).

16. scanning unit (100, 100-1, 100-2) according to one of the preceding claims,

wherein the mirror surface (1 1 1) has a recess (1 19),

wherein the at least one support element (121, 122) extends at least partially in the recess (1 19),

wherein the at least one support member (121, 122) optionally extends along at least 40% of its length (352) in the recess (1 19), further optionally along at least 60% of its length (352), further optionally along at least 80% of its length (352).

17. A scanning unit (100, 100-1, 100-2) according to any one of the preceding claims, further comprising:

the fixed structure (350) defining a clearance (351) in which the

Deflecting element (1 10) is arranged,

wherein the free space (351) is formed to a deflection (502) of the

Deflection element by torsion (501) of the at least one support element (121, 122) of at least ± 45 ° to allow, optionally of at least ± 80 °, further optionally of at least ± 180 °.

Scan unit (100, 100-1, 100-2) according to one of the preceding pages

wherein the periphery of the mirror surface (1 1 1) has a plurality of sides (1 12-1 15), wherein only one of the plurality of sides (1 14) is coupled to the fixed structure (350).

19. A method of operating a scan unit (100, 100-1, 100-2) to scan light (361), the method comprising:

- Controlling of at least one actuator to at least one support element (121, 122) extending in a by a mirror surface (1 1 1) of a deflecting (1 10) defined plane (901), with respect to a fixed structure (350) with a Resonant to deflect torsional mode, and further to deflect at least one further support member (131, 132) which extends offset to the plane (901) with the torsional mode resonant with respect to the fixed structure (350),

20. A method of manufacturing a scanning unit (100, 100-1, 100-2) for scanning light (361), the method comprising:

in a first etching process of a first wafer: producing a deflecting element and at least one supporting element (121, 122) extending away from the deflecting element, in the first wafer,

in a second etching process of a second wafer: producing at least one further support element (131, 132), in the second wafer,

Bonding the first wafer to the second wafer, and

- Existence of the deflecting element, the at least one support element (121, 122) and the at least one further support element (131, 132).