Device for testing and / or adjusting and / or calibrating at least one imaging system

Abstract

The invention relates to a device for testing and / or adjusting and / or calibrating at least one imaging system, in particular a lidar system, wherein the imaging system is associated with at least one radiation-emitting unit, wherein a detection field can be formed by means of the emitted radiation, wherein the device has at least one radiation direction unit for directing the radiation onto an entry area of ​​a kaleidoscope, wherein the radiation direction unit has at least one controllable radiation-reflecting element, wherein the kaleidoscope has mutually facing reflective surfaces that deflect the radiation within the kaleidoscope depending on a certain entry angle of the radiation into the kaleidoscope.wherein the device comprises at least one reflection device adjoining an exit region of the radiation from the kaleidoscope for reflecting the radiation exiting the kaleidoscope, the reflection device comprising a controllable display. The invention further relates to a method for testing and / or adjusting and / or calibrating at least one imaging system, in particular a lidar system.

Description

[0001] The invention relates to a device for testing, adjusting, and / or calibrating at least one imaging system, in particular a lidar system, wherein the imaging system is associated with at least one radiation-emitting unit and wherein a detection field can be formed by means of the emitted radiation. Furthermore, the invention relates to a method for testing an imaging system, in particular a lidar system, using a device according to the invention.

[0002] Imaging systems of the type mentioned above, particularly lidar (light detection and ranging) systems, are used, for example, for optical distance and speed measurement, remote sensing of atmospheric parameters, and in a variety of other applications. Imaging systems can be active or passive. Passive imaging systems may, for example, consist of a radiation receiver. Active imaging systems may, for example, consist of a radiation emitter (i.e., a radiation-emitting unit) and a radiation receiver. Imaging systems can also include, for example, spotlights, flashlights, structured light scanners, time-of-flight cameras, or similar devices. The radiation can be, for example, coherent or incoherent light.A radiation-emitting unit can be, for example, a laser, a light source, or other radiation sources. For instance, radiation can be used to scan a three-dimensional space. The space that can be scanned by the imaging system is called the field of view. Imaging systems, especially lidar systems, are used, for example, in the control and navigation of autonomous vehicles. Precise adjustment, calibration, and testing of imaging systems are essential to enable accurate lidar measurements. Extensive test fields, such as those simulating the real-world conditions of an autonomous vehicle, can be used for end-of-line testing of imaging systems. This sometimes requires large test fields and setups.This results in a high testing effort, meaning it is not suitable for mass production, i.e., for checking every manufactured imaging system.

[0003] From DE 10 2023 110 329 A1, a device for testing and / or adjusting and / or calibrating at least one imaging system, in particular a lidar system, is known, wherein at least one radiation-emitting unit is assigned to the imaging system, wherein a detection field can be formed by means of the emitted radiation, wherein the device has at least one focusing device for focusing the detection field formed by the radiation, wherein the focusing device has at least one optical element positioned at a certain angle to the imaging system for focusing the detection field, wherein the device has at least one radiation direction unit downstream of the focusing device for directing the radiation onto an entrance area of ​​a kaleidoscope, wherein the kaleidoscope has mutually facing reflective surfaces.which deflect the radiation within the kaleidoscope depending on a specific angle of entry of the radiation into the kaleidoscope, and wherein the device comprises at least one measuring device connected to an exit region of the radiation from the kaleidoscope for detecting the radiation exiting the kaleidoscope. The described method can be used to simulate three-dimensional environments for testing the imaging method. A temporal dependency of the depicted environments, i.e., a dynamic scene to simulate, for example, approaching vehicles, is not provided for in the application.

[0004] The invention is based on the objective of proposing a device and a method for testing and adjusting an imaging system, wherein the experimental setup has compact dimensions and wherein the representation of time-dependent three-dimensional processes is possible.

[0005] This problem is solved by a device having the features of claim 1 and by a method having the features of claim 8. Further developments and advantageous embodiments are specified in the dependent claims.

[0006] The invention relates to a device for testing and / or adjusting and / or calibrating at least one imaging system, in particular a lidar system, wherein the imaging system is associated with at least one radiation-emitting unit, wherein a detection field can be formed by means of the emitted radiation, wherein the device has at least one radiation direction unit for directing the radiation onto an entry area of ​​a kaleidoscope, wherein the radiation direction unit has at least one controllable radiation-reflecting element, wherein the kaleidoscope has mutually facing reflective surfaces that deflect the radiation within the kaleidoscope depending on a certain entry angle of the radiation into the kaleidoscope.wherein the device comprises at least one reflection device adjoining an exit region of the radiation from the kaleidoscope for reflecting the radiation exiting the kaleidoscope, wherein the reflection device comprises a controllable display.

[0007] The device can include at least one test mount from which the imaging system under test can be received. The test mount can be adapted to the type of system under test, particularly the imaging system, and can be interchangeable, allowing the device to test different systems. However, the device can also be placed in front of a system under test without a test mount. For testing a passive imaging system, the device can include a radiation-emitting unit, such as a laser or a similar radiation source. The emitted radiation can be used to test the passive imaging system under investigation. In the case of an active imaging system, the imaging system itself incorporates the radiation-emitting unit.The device has at least one focusing device designed to focus the detection field formed by the radiation emitted by the imaging system.

[0008] For example, the field of view can be formed by scanning an area in the X and Y directions using the radiation-emitting unit of the imaging system. The field of view can also be formed by radiation received from a specific area. In this case, it could be laser radiation. The radiation could also be infrared radiation, coherent or incoherent light, or similar. The focusing device allows the field of view to be focused, particularly in the X and Y directions, thus reducing its size. The field of view is therefore focused on a smaller area. This makes it possible to examine a larger field of view of the system under test in a compact space. The focusing in the horizontal and vertical planes can be performed independently of each other, particularly sequentially.For this purpose, the focusing device incorporates optical elements, such as lenses, parabolic mirrors, or metamaterial-based surfaces. Malleable mirrors, reflectors, or curved surfaces can also be used. Downstream of the focusing device in the beam path is a beam directional unit, which guides, and in particular aligns, the radiation exiting the focusing device. The beam directional unit directs the radiation forming the focused field of view onto the entrance area of ​​a kaleidoscope. The beam directional unit is a controllable radiation-reflecting element, allowing the radiation to be directed at various angles onto the entrance area of ​​the kaleidoscope.In particular, the radiation-reflecting element can comprise a multitude of controllable individual reflecting elements, allowing, for example, the independent guidance of beam segments. The angle of incidence of each individual element can be controlled for this purpose. The radiation-reflecting element can also be an LCOS (Liquid Crystal on Silicon), in which the reflectivity of the individual pixels of the LCOS is controllable. Thus, different angles of entry into the kaleidoscope can be selected for different beam segments. The kaleidoscope has mutually facing reflective surfaces, through which the path of the emitted radiation within the kaleidoscope can be lengthened by reflections at these surfaces. The length of the radiation path within the kaleidoscope depends on the angle of entry of the radiation into the kaleidoscope.In particular, a kaleidoscope can be formed by a two-dimensional polygonal, for example triangular or quadrilateral, imaginary base that is stretched along the third dimension. The kaleidoscope thus has a polygonal cross-section. The inward-facing inner surfaces of the resulting lateral surfaces are reflective, and the end faces may be open. A cavity is formed between the lateral surfaces. The kaleidoscope can also be formed in space by a geometric solid called a prism, that is, a polygon formed by translating a planar polygon in a line not lying in that plane. In this case, the geometric solid is defined solely by the lateral surfaces.The smaller the angle between the imaginary base of the kaleidoscope and the incoming radiation, the more reflections occur inside the kaleidoscope, and the longer the radiation path becomes—that is, the length of the path traveled within the kaleidoscope. The angle at which the radiation enters the kaleidoscope determines the length of the radiation path within the kaleidoscope. The radiation path length can therefore be set by the radiation direction unit. By using the kaleidoscope, different path lengths of the radiation emitted by the system under test can be examined in a small space. The device has at least one reflection device at an exit point of the radiation from the kaleidoscope, which reflects the radiation exiting the kaleidoscope back for further analysis.Retroreflectors, and in particular an array of multiple retroreflectors, can be used to reflect the radiation. These retroreflectors can be, for example, lens reflectors such as cat's-eye and Lüneburg lenses, or angle reflectors, or similar devices. A controllable display is associated with the reflection device. The display is positioned in the radiation path. The display is transparent, and the grayscale level of each pixel can be controlled. For example, a control unit, such as a processing unit or similar device, can be used to control the radiation-reflecting element, specifically each controllable individual element or the reflectivity of each pixel of the display, via data connections, so that time-dependent, i.e., dynamic, three-dimensional scenes can be displayed.To evaluate the radiation detected by the measuring device, an evaluation unit, in particular a computer or similar device, may be provided. The evaluated data can be used for testing and / or adjusting and / or calibrating the imaging system.

[0009] In one embodiment of the invention, the radiation-reflecting element of the radiation direction unit is an arrangement of individual reflecting elements. The radiation-reflecting element can be a so-called digital micromirror device (DMD). This is an arrangement, i.e., an array or matrix, of individual reflecting elements whose angles of incidence can be individually controlled.

[0010] In one embodiment of the invention, the radiation-reflecting element of the radiation direction unit is an LCoS. An LCoS (Liquid Crystal on Silicon) is a display component consisting of a liquid crystal layer on a silicon substrate, which contains a multitude of pixels. This can, for example, be configured such that the reflectivity of each pixel can be individually controlled.

[0011] In one embodiment of the invention, the radiation direction unit is designed to rotate about at least one axis. By rotating the radiation-reflecting element about one, preferably several, axes, different angles of incidence to the kaleidoscope and thus different radiation path lengths within the kaleidoscope can be achieved.

[0012] In one embodiment of the invention, the reflection device comprises at least one retroreflector, and this retroreflector is associated with the controllable display. The radiation emitted from the kaleidoscope can be reflected back by the retroreflectors and, for example, detected by a radiation receiver of the imaging system. For reflecting the radiation, an arrangement of multiple retroreflectors can be provided. These retroreflectors can be, for example, lens reflectors, such as cat's-eye and Lüneburg lenses, or angle reflectors, or similar devices. A controllable display is associated with the reflection device. The display is positioned in the radiation path. The display is transparent, and the grayscale level of each pixel is controllable.Because the pixels can be controlled between transparent and opaque grayscale states, objects can be displayed. Thus, in conjunction with the control of the radiation direction unit, time-dependent, i.e., dynamic, three-dimensional scenes can be simulated on the display.

[0013] In one embodiment of the invention, the display is at least partially transparent and is arranged in the beam path of the radiation between the kaleidoscope and the retroreflector.

[0014] In one embodiment of the invention, the controllable display is configured to show different shades of gray, and the distribution of the shades on the display is controlled by means of a data stream. A detailed calibration map of the shades can be calculated. The data stream can be generated by a processing unit.

[0015] A further aspect of the invention relates to a method for testing an imaging system, in particular a lidar system, by means of a device according to the invention as defined in one of the preceding claims, wherein the imaging system is assigned at least one radiation-emitting unit, wherein a detection field can be formed by means of the emitted radiation, wherein the length of the radiation path of the radiation forming the detection field is extended by means of at least one kaleidoscope, wherein the length of the radiation path is set by the angle of entry of the radiation into the kaleidoscope by means of a radiation direction unit, wherein the radiation is reflected after exiting the kaleidoscope by means of at least one reflection device.wherein a three-dimensional representation for testing the imaging system is generated by means of at least one controllable radiation-reflecting element of the radiation direction unit and by means of a controllable display of the reflection device. For example, by means of a control device, the radiation-reflecting element, in particular each controllable individual element or the reflectivity of each pixel, as well as the pixels of the display of the reflection device, can be controlled via data-conducting connections in such a way that time-dependent, i.e., dynamic three-dimensional situations can be simulated. The angles of inclination of the individual elements of a DMD or the reflectivity of the pixels of an LCOS of the radiation-reflecting element can be controlled individually.This allows, for example, different path lengths within the kaleidoscope to be set for different beams of radiation. The display of the reflection unit behind the kaleidoscope has a large number of pixels whose state can be controlled between transparent and grayscale. When a pixel is assigned a grayscale level, it can, for example, be detected by a lidar system as a distant object. The path length of the radiation to the object can be individually controlled by the angles of incidence of the individual elements or the reflectivity of the pixels of the radiation-reflecting element. By changing the angles of incidence or reflectivities of the radiation direction unit over time, the distance, i.e., the path length within the kaleidoscope, can be altered, enabling a temporally dynamic three-dimensional representation of a scene, such as a traffic situation.This makes it possible, for example, to simulate a vehicle braking or an approaching vehicle.

[0016] In one embodiment of the method, the pixels of a three-dimensional representation are displayed by the controllable radiation-reflecting element of the radiation direction unit and by means of the controllable display of the reflection device. Time-dependent representations, such as a traffic scene, can be simulated via a data stream for testing a lidar.

[0017] In a further development of the method, a three-dimensional representation is generated using a 3D engine, and a data stream is generated from the 3D engine to control the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device. Using a 3D engine such as Carla, Aurelion, Unreal, or Unity, three-dimensional representations, especially time-dependent representations, can be generated, which can be displayed for acquisition by the device under test using the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device.

[0018] In a further development of the process, individual frames of a three-dimensional representation are generated from the 3D engine and displayed using the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device. For example, a frame could be an arrangement of pixels that are displayed.

[0019] In a further development of the method, a sequence of individual frames of a three-dimensional representation is generated from the 3D engine and displayed using the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device. Several frames of a three-dimensional representation can be displayed in temporal sequence to simulate dynamic situations.

[0020] In a possible further development, the device includes at least one test holder for receiving the imaging system under test. The device includes at least one test holder from which the imaging system under test can be received; in particular, the test holder may have connecting means, such as clamps or corresponding mounting points for the imaging system, so that the imaging system is held firmly by the test holder. The test holder may be adapted to the type of system under test, especially the imaging system, and may be interchangeable, so that different systems can be tested with the device. In particular, the test holder includes a bearing for performing a translational or rotational movement.

[0021] In one possible embodiment, the test fixture comprises at least one clamping device that is arranged to be translationally movable, rotationally movable, or both translationally and rotationally movable relative to other components of the fixture. The translationally and rotationally movable arrangement ensures precise alignment of the system under test, particularly the lidar system, with, for example, the focusing device within the fixture. The test fixture may have a mechanical, electronic, and / or data-conducting interface to the system under test.

[0022] In a possible further development, at least one sensor is assigned to the test fixture, the focusing device, the beam direction unit, the kaleidoscope, and / or the measuring device, with which environmental influences on the device or its components can be determined. The sensor(s) can be designed, for example, to measure temperature, air pressure, vibration, or other environmental conditions, in order to incorporate the measured values ​​of these environmental conditions into, for example, the calibration or adjustment of the system under test.

[0023] In a possible further development, the focusing device comprises at least one reflective surface, a lens, or a metamaterial as an optical element. To focus the detection field formed by the radiation emitted by the system under test, the focusing device includes, for example, curved reflective surfaces that can focus the detection field independently in the horizontal and vertical planes. A similar effect can be achieved, for example, by using lenses or metamaterials. Deformable mirrors, especially controllable deformable mirrors, parabolic mirrors, or similar devices can also be provided.

[0024] In one possible embodiment, at least one reflective surface is a parabolic mirror. A parabolic mirror allows the radiation emitted by the system under test, forming the detection field, to be focused in both the horizontal and vertical planes.

[0025] In one possible embodiment, the reflective surfaces of the focusing device are aligned with each other such that they act on the detection field formed by the emitted radiation in different planes, in particular at least one reflective surface is assigned to a horizontal axis of the detection field and at least one reflective surface to a vertical axis of the detection field. For example, by means of two reflective surfaces, which may be at least partially semi-cylindrically concave, the detection field can be focused, for instance, by a first reflective surface in the horizontal plane and by a second reflective surface in the vertical plane.Due to the decoupled horizontal and vertical focusing, the requirements for the optical elements are reduced compared to, for example, focusing by a single optical element, such as a parabolic mirror. Here, the radiation, after exiting the system under test, is first directed onto one reflective surface and then reflected from there onto the second reflective surface.

[0026] In one possible embodiment, the reflective surfaces of the focusing device are each focusing and, at least in sections, substantially cylindrical in shape, and rotated relative to each other by 90° to align the incident radiation. The reflective surfaces of the focusing device can be formed by focusing, particularly concave, substantially cylindrical, and especially hollow cylindrical, bodies. The lateral surface sections of the reflective surface are rotated relative to each other by 90° in their longitudinal extent. One reflective surface focuses the detection field in the horizontal plane, and the other reflective surface then focuses it in the vertical plane. Thus, the dimensions of the detection field are focused independently.

[0027] In one possible embodiment, the bundling device has an internal calibration device, in particular an automatically adjusting self-calibration. The calibration device ensures precise alignment and adjustment of the bundling device.

[0028] In a possible further development, the radiation directional unit comprises at least one mirror, at least one scanning mechanism, and at least one control unit. The scanning mechanism enables the radiation directional unit to direct the radiation exiting the focusing device at different angles onto the entrance area of ​​the kaleidoscope. This allows for different path lengths of the radiation within the kaleidoscope. For this purpose, the control mirror of the radiation directional unit is pivoted around at least one axis by the scanning mechanism. The scanning mechanism can be implemented, for example, using piezoelectric actuators, servo motors, or similar devices. The control mirror of the radiation directional unit can be constructed, for example, from a layered structure of dielectric material or other layered arrangements to optimize performance for different angles of incidence and wavelengths.Furthermore, the control mirror can be constructed from metamaterials. The scan speed at which the control mirror is swiveled must be lower than that of the internal scanner of the system under test, in particular the laser scanner of a lidar system under test, with which the detection field is scanned by the imaging system.

[0029] In one possible embodiment, the radiation direction unit is rotatable about at least one axis. By rotating the control mirror, different angles of incidence to the kaleidoscope and thus different radiation path lengths within the kaleidoscope can be achieved.

[0030] In one possible embodiment, the radiation directional unit acts as an aperture between the focusing device and the kaleidoscope. This aperture effect can be achieved by the size of the control mirror, for example, by preventing peripheral regions of the radiation exiting the focusing device from being directed by the control mirror into the kaleidoscope.

[0031] In one possible embodiment, the kaleidoscope has a polygon as its imaginary base. Lateral surfaces adjoin the sides of this imaginary base. These lateral surfaces together enclose a cavity, at least partially. The lateral surfaces have reflective surfaces, and these reflective surfaces are located on the inward-facing inner surfaces of the lateral surfaces. A kaleidoscope can be formed by an imaginary two-dimensional base, which may be a polygon, stretched along the third dimension. For example, the base can be triangular or quadrilateral, so the kaleidoscope has a triangular or quadrilateral cross-section. The inward-facing inner surfaces of the lateral surfaces created by the stretching are reflective. A cavity is formed between the lateral surfaces, and the end faces of the kaleidoscope may be open.

[0032] In a possible advanced version, the focusing device, the radiation direction unit, and / or the kaleidoscope feature alignment markings. These alignment markings enable precise alignment of the various components to achieve accurate beam path control.

[0033] In one possible embodiment, the measuring device has at least one retroreflector. The retroreflector allows the radiation emitted from the kaleidoscope to be reflected back and, for example, detected by a radiation receiver of the imaging system. This enables the testing of various parameters and functions of the system under test.

[0034] In one possible embodiment, the measuring device has at least one optical detection element. This optical detection element could be, for example, a photodiode, a photosensor, or similar device. These multiple optical detection elements, which could be arranged in a grid, for example, can be used to verify the shape of the detection field.

[0035] In one possible embodiment, the device includes at least one evaluation unit for analyzing the radiation detected by the measuring device. The evaluation unit can be, for example, a computing unit such as a processing core or similar. The evaluation unit can analyze the detected radiation; in particular, it can analyze various parameters of the imaging system and the radiation emitted by the imaging system.

[0036] A method for testing, adjusting, and / or calibrating at least one imaging system, in particular a lidar system, wherein the system is associated with at least one radiation-emitting unit, wherein a detection field can be formed by means of the emitted radiation, wherein the length of the radiation path of the radiation forming the detection field is extended, and wherein the extension of the radiation path can be described by at least one iterated function. In particular, the method is designed to be carried out with the apparatus of the preceding claims. The method is intended for testing, adjusting, and / or calibrating an imaging system, such as a spotlight, a flash unit, a structured light scanner, a time-of-flight camera, a lidar system, or the like.An active imaging system can be configured to emit radiation, for example, coherent or incoherent light, by means of a radiation-emitting unit. For testing a passive imaging system, the device can include a radiation-emitting unit, for example, a laser or a similar radiation source. The emitted radiation can be used to test the passive imaging system under investigation. In an active imaging system, the imaging system itself includes the radiation-emitting unit. The emitted radiation forms a detection field. A device according to the invention, which includes a focusing device, can focus the radiation forming the detection field. The focusing device allows the detection field to be reduced, particularly in the X and Y directions.The detection field is thus focused onto a smaller area. This makes it possible to examine a potentially larger detection field of the system under test within a compact space. After focusing, the radiation forming the focused detection field is directed, for example, by a radiation directional unit. To be able to examine different radiation path lengths of the emitted radiation, the radiation path of the radiation emitted, for example, by the system under test, is extended within a small space. It is intended that the extension of the beam path can be described by at least one iterated function. An iterated function is a function obtained by combining another function with itself a certain number of times.Starting with an initial function, the result of applying a specific function is fed back into the function, and this process is repeated accordingly. For example, the number of iterations can be used to describe the lengthening of the radiation path due to reflections, especially multiple reflections, of the radiation at reflected surfaces. This radiation path lengthening based on iterated functions enables the investigation of the emitted radiation for the system under test at different radiation path lengths within a small space.

[0037] In a possible further development, the detection field formed by the emitted radiation is focused by means of at least one focusing device. To focus the detection field formed by the radiation emitted by the system under test, the focusing device may, for example, have curved reflective surfaces that can focus the detection field independently in the horizontal and vertical planes. A similar effect can be achieved, for example, by using lenses or metamaterials. Deformable mirrors, in particular controllable deformable mirrors or parabolic mirrors, may also be used.

[0038] In a possible further development, the focusing of the detection field by the focusing device occurs sequentially in different planes. In particular, focusing along a horizontal axis of the detection field and along a vertical axis of the detection field is performed independently of each other. For example, one reflective surface can be assigned to a horizontal axis of the detection field and another to a vertical axis. With two reflective surfaces, which can be at least partially hollow and concave, the detection field can be focused, for example, by a first reflective surface in the horizontal plane and by a second reflective surface in the vertical plane. The decoupled horizontal and vertical focusing reduces the requirements for the optical elements, for example, by eliminating the need for focusing by a single optical element.After exiting the system under test, the radiation is first directed onto one reflective surface and then reflected from this surface onto the second reflective surface in order to achieve focusing first in a horizontal and then in a vertical plane.

[0039] In a possible further development, the length of the radiation path forming the detection field is extended by means of at least one kaleidoscope, and the length of the radiation path is adjusted by the angle of incidence of the radiation into the kaleidoscope. A radiation direction unit directs the radiation forming the focused detection field onto the entrance area of ​​a kaleidoscope. The kaleidoscope has mutually facing reflective surfaces, through which the radiation path of the emitted radiation within the kaleidoscope can be extended by reflections at these surfaces. The length of the radiation path within the kaleidoscope depends on the angle of incidence of the radiation. In particular, a kaleidoscope can be formed by a two-dimensional polygonal, for example, triangular or quadrilateral, imaginary base that is stretched along the third dimension.The inward-facing inner surfaces of the kaleidoscope's lateral surfaces, created by the stretching process, are reflective. A cavity exists between these surfaces. The smaller the angle between the kaleidoscope's imaginary base and the incoming radiation, the more reflections occur inside the kaleidoscope, and the longer the radiation path becomes—that is, the length of the path traveled within the kaleidoscope. Therefore, the angle at which the radiation enters the kaleidoscope determines the length of the radiation path within the kaleidoscope. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 110 329 A1

[0003]

Claims

[1] Device for testing and / or adjusting and / or calibrating at least one imaging system, in particular a lidar system, wherein at least one radiation-emitting unit is associated with the imaging system, wherein a detection field can be formed by means of the emitted radiation, wherein the device has at least one radiation directional unit for directing the radiation onto an entrance area of ​​a kaleidoscope, wherein the radiation direction unit has at least one controllable radiation-reflecting element, wherein the kaleidoscope has mutually facing reflective surfaces that deflect the radiation within the kaleidoscope depending on a certain angle of entry of the radiation into the kaleidoscope, wherein the device has at least one reflection device adjoining an exit area of ​​the radiation from the kaleidoscope for reflecting the radiation exiting the kaleidoscope, the reflection device includes a controllable display. [2] Device according to claim 1, characterized by , that the radiation-reflecting element of the radiation direction unit is an arrangement of reflective individual elements. [3] Device according to claim 1, characterized by , that the radiation-reflecting element of the radiation direction unit is an LCoS. [4] Device according to any one of claims 1 to 3, characterized by that the radiation direction unit is designed to be rotatable about at least one axis. [5] Device according to any one of claims 1 to 4, characterized bythat the reflection device has at least one retroreflector and that the at least one retroreflector is assigned to the controllable display. [6] Device according to any one of claims 1 to 5, characterized by that the controllable display is at least partially transparent and that the controllable display is arranged in the beam path of the radiation between the kaleidoscope and the retroreflector. [7] Device according to any one of claims 1 to 6, characterized by , that the controllable display has pixels for displaying different shades of gray and that the distribution of the shades of gray on the display is controlled by means of a data stream. [8] Method for testing an imaging system, in particular a lidar system, using a device according to one of the preceding claims, wherein the imaging system is associated with at least one radiation-emitting unit, wherein a detection field can be formed by means of the emitted radiation, wherein the length of the radiation path of the radiation forming the detection field is extended by means of at least one kaleidoscope, wherein the length of the radiation path is set by the angle of entry of the radiation into the kaleidoscope by means of a radiation direction unit, wherein the radiation is reflected after exiting the kaleidoscope by means of at least one reflection device, wherein a three-dimensional representation for testing the imaging system is generated by means of at least one controllable radiation-reflecting element of the radiation direction unit and by means of a controllable display of the reflection device. [9] Method according to claim 8, wherein the pixels of a three-dimensional representation are displayed by the controllable radiation-reflecting element of the radiation direction unit and by means of the controllable display of the reflection device. [10] Method according to claim 8 or 9, characterized by , that a three-dimensional representation is generated using a 3D engine and that a data stream is generated from the 3D engine to control the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device. [11] Method according to claim 10, characterized by , that individual frames of the three-dimensional representation are generated from the 3D engine and displayed using the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device. [12] Method according to claim 10, characterized by, that a sequence of individual frames of a three-dimensional representation is generated from the 3D engine and is displayed using the radiation-reflecting element of the radiation direction unit and the controllable display of the reflection device.