Deflection device for an optoelectronic sensor of a motor vehicle with at least two electro-optical deflection units, optoelectronic sensor, driver assistance system, motor vehicle and method

Abstract

Deflection device (13) for an optoelectronic sensor (5) of a motor vehicle (1), comprising at least two electro-optical deflection units (14), each designed to deflect light beams (16, 16') into predetermined deflection angles (α, α'), wherein the at least two electro-optical deflection units (14) each have an entry area (15) for coupling in the light beams (16, 16') and an exit area (18) for coupling out the deflected light beams (16, 16'), characterized in that the deflection device (13) comprises an optical element (21) which is connected to the respective exit areas (18) of the at least two electro-optical deflection units (14) and which is designed to direct the light beams (16, 16') deflected by the at least two electro-optical deflection units (14) into a predetermined detection area (29a, 29b). lead.

Description

[0001] The present invention relates to a deflection device for an electro-optical sensor of a motor vehicle, comprising at least two electro-optical deflection units, each designed to deflect light beams to predetermined deflection angles, wherein the at least two electro-optical deflection units each have an entry region for coupling the light beams and an exit region for coupling the deflected light beams out. Furthermore, the present invention relates to an optoelectronic sensor. The present invention also relates to a driver assistance system. Finally, the present invention relates to a motor vehicle. Finally, the present invention relates to a method for operating a deflection device for an optoelectronic sensor of a motor vehicle.

[0002] The focus here is on optoelectronic sensors for motor vehicles. Such optoelectronic sensors can, for example, be designed as lidar sensors (Lidar - Light Detection and Ranging). These optoelectronic sensors are installed in motor vehicles to detect the vehicle's surroundings while driving or operating. The optoelectronic sensor is, in particular, a scanning optical measuring device that can detect objects or obstacles in the vehicle's vicinity. For example, the optoelectronic sensor can determine the distance between the vehicle and the object based on the travel time of a light pulse, or according to the so-called time-of-flight principle.An optoelectronic sensor typically comprises a transmitter, which may include a laser diode, for example, that emits an optical signal in the form of a light pulse or beam. Furthermore, the optoelectronic sensor includes a corresponding receiver, which may include at least one photodiode, for example, that receives the light beam reflected by the object as a signal.

[0003] The optoelectronic sensor emits light beams within a predetermined detection range. To deflect the light beams or laser light within this range, the transmitter incorporates a deflection device. Various deflection devices are known in the prior art. For example, deflection devices comprising deflection mirrors or an array of micromirrors are used. The present case focuses on deflection devices that incorporate an electro-optical deflection unit. These electro-optical deflection units, which have no moving mechanical parts, can deflect the light beams in two spatial directions with high angular resolution and a high sampling rate.

[0004] These electro-optical deflection units can, for example, include an optical fiber in which the light rays are guided by total internal reflection at interfaces. Furthermore, elements can be provided to control the angle of incidence at which the light ray is coupled into the optical fiber and / or the angle of exit at which the light ray emerges from the optical fiber. These elements can, for example, include liquid crystals whose refractive index can be changed under the influence of an electric field. Such a deflection unit is described, for example, in US Patent 8,995,038 B1.

[0005] Furthermore, WO 2014 / 200 581 A2 describes a lidar system in which a laser beam is deflected in different spatial directions by means of an electro-optical deflection unit. In particular, the electro-optical deflection unit is designed as a so-called steerable electro-evanesent optical reflector (SEEOR). A polarization grating can also be arranged at the output of the deflection unit to improve the beam quality.

[0006] Furthermore, US 2008 / 0 285 010 A1 shows an object detector that emits laser light from a projection device as detection waves.

[0007] US 2014 / 0 240 691 A1 shows a laser radar system and a method for taking an image of an object.

[0008] Furthermore, DE 44 11 994 A1 describes a method for evaluating traffic situations in road or rail traffic. The traffic scene is continuously scanned line by line, and the movement of the vehicles creates a three-dimensional representation of the traffic scene. The scanning is performed in two lines. The speed of the vehicles is determined by correlating the two lines, and this is used to correct the third dimension of the representation.

[0009] US Patent 8,995,038 B1 discloses an optical time-delay control device. The device may include an optically transparent solid medium for receiving the light beam.

[0010] Furthermore, WO 2014 / 200 581 A2 describes a non-mechanical device for controlling a light beam, comprising one or more polarization gratings (PGs).

[0011] When such electro-optical deflection units are used in lidar sensors for motor vehicles, their detection range is limited in both horizontal and vertical directions. To reliably detect objects with the lidar sensor, a higher angular resolution and a higher sampling rate are also desirable.

[0012] The object of the present invention is to provide a deflection device of the type mentioned above, by means of which an optoelectronic sensor for a motor vehicle can be operated more efficiently and in accordance with requirements.

[0013] This problem is solved according to the invention by a deflection device, by an electro-optical sensor, by a driver assistance system, by a motor vehicle, and by a method with the features according to the respective independent claims. Advantageous embodiments of the present invention are the subject of the dependent claims.

[0014] According to one embodiment, a deflection device for an optoelectronic sensor of a motor vehicle comprises at least two electro-optical deflection units. These at least two electro-optical deflection units are preferably designed to deflect light beams at predetermined angles. In particular, each of the at least two electro-optical deflection units has an entry region for coupling the light beams in and an exit region for coupling the deflected light beams out. Furthermore, the deflection device preferably includes an optical element, which is preferably connected to the respective exit regions of the at least two electro-optical deflection units. The optical element is also preferably designed to guide the light beams deflected by the at least two electro-optical deflection units into a predetermined detection area.

[0015] A deflection device according to the invention for an optoelectronic sensor of a motor vehicle comprises at least two electro-optical deflection units, each designed to deflect light beams into predetermined deflection angles, wherein the at least two electro-optical deflection units each have an entry region for coupling the light beams in and an exit region for coupling out the deflected light beams. Furthermore, the deflection device comprises an optical element connected to the respective exit regions of the at least two electro-optical deflection units and designed to guide the light beams deflected by the at least two electro-optical deflection units into a predetermined detection area.

[0016] The deflection device can be used in an optoelectronic sensor for a motor vehicle. Such an optoelectronic sensor can be configured as a lidar sensor, and in particular as a scanning lidar sensor. Preferably, the deflection device can be used in a transmitter of the optoelectronic sensor. The deflection device deflects light beams or light pulses emitted by light sources of the transmitter. Such a light source can be a laser light source, for example, a laser diode. The deflection device comprises at least two electro-optical deflection units, which can also be referred to as electro-optical deflectors. The at least two electro-optical deflection units are preferably identical in design. Each electro-optical deflection unit has an entry area through which the light beams can be fed to it.The deflected light rays can then be emitted from the exit area of ​​the electro-optical deflection unit. Furthermore, each electro-optical deflection unit can, for example, include an element whose refractive index changes depending on an applied electric field. This allows the light rays emitted by the light sources to be deflected accordingly. In particular, the electro-optical deflection unit can be controlled such that the light rays are deflected sequentially to predetermined angles. This allows the light rays to be deflected within a predetermined angular range.

[0017] According to a key aspect of the present invention, the deflection device comprises an optical element arranged at the exit points of at least two electro-optical deflection units. This optical element allows the light rays deflected by the respective electro-optical deflection units to be deflected or guided again. The optical element refractes and / or reflects the light rays deflected by the electro-optical deflection units. It also guides the light rays deflected by each electro-optical deflection unit into a predetermined detection area. The deflection device can comprise a first electro-optical deflection unit and a second electro-optical deflection unit.The optical element allows the light beams from the first electro-optical deflection unit to be guided into a first detection area, and the light beams from the second electro-optical deflection unit to be guided into a second detection area. Objects can then be detected within these areas. The detection areas can be defined according to the application of the optoelectronic sensor. This allows the optoelectronic sensor to be operated more efficiently and reliably.

[0018] According to one embodiment, the optical element is designed such that the respective detection areas differ from one another. If the deflection device comprises a first electro-optical deflection unit and a second electro-optical deflection unit, the first detection area, into which the light beams of the first electro-optical deflection unit are guided, can differ from the second detection area, into which the light beams of the second electro-optical deflection unit are guided. For example, the first and second detection areas can be adjacent to each other. This makes it possible, for example, to reliably detect objects using the optoelectronic sensor.

[0019] In an alternative embodiment, the optical element is designed such that the respective detection areas overlap, at least partially. It is possible that the detection areas are identical. In this case, the light rays deflected by the at least two electro-optical deflection units are guided to the same detection area. This allows for particularly precise scanning of this detection area. The optical element can also be designed such that the detection areas only partially overlap.

[0020] Preferably, the respective electro-optical deflection units are designed to deflect the light beams in such a way that the optical element guides the light beams successively to predetermined emission angles within the respective detection area. Light beams or light pulses can be emitted from the light source and then deflected sequentially by the respective electro-optical deflection unit. The deflected light beams are then further deflected or guided by the optical element. Thus, corresponding areas within the detection area can be illuminated or scanned successively with the guided light beams. The emission angles to which the light beams are deflected can be defined by the design and / or shape of the optical element. These emission angles, in turn, define the areas illuminated by the light beams.The areas are also determined by the control of the respective electro-optical deflection unit and, in particular, by its deflection angle. Thus, the respective detection areas can be scanned.

[0021] Furthermore, it is advantageous if the respective transmission angles are predefined such that the optical element guides the respective light beams into areas arranged along a predetermined path. As already explained, the light beams can illuminate areas within the respective detection zones sequentially. A path can be defined along which these areas are arranged. This path can, for example, run linearly or meanderingly through the respective detection zone. For instance, different paths can be defined for the respective light beams of the different electro-optical deflection units. In this way, the different detection zones can be provided. The paths can also be determined so that they run within an identical or overlapping detection zone.

[0022] In another embodiment, the optical element is designed such that the respective detection areas overlap in some sections, and the respective trajectories are offset from one another. The electro-optical deflection units can, for example, be arranged one above the other or side by side. In particular, the electro-optical deflection units can have a lateral offset from one another. This can also result in an offset in the trajectories. This offset can be taken into account when determining or defining the detection area. It can also be provided that this offset is considered when evaluating the reflected light rays. Usually, however, this offset of the trajectories is so small that it can be neglected. Defining the trajectories enables reliable operation of the optoelectronic sensor.

[0023] Furthermore, it is advantageous if the areas of the respective light beams are arranged alternately with each other. If the detection areas overlap at least partially or predominantly, the respective trajectories can also be similar. As explained previously, these trajectories can have a lateral offset from each other. In particular, it is intended that the areas along the trajectories are predefined. If the deflection device has the first and the second electro-optical deflection unit, the areas assigned to the first and the second electro-optical deflection unit can be arranged alternately with each other along these trajectories. This means that along the trajectories, one area is illuminated by the light beams of the first electro-optical deflection unit, the adjacent area is illuminated by the light beams of the second electro-optical deflection unit, and so on.This allows the detection area to be scanned within a short period of time.

[0024] The path of the light beam can also be defined in a specific direction, along which the respective areas are illuminated. For example, the path can run from a first point to a second point. The first electro-optical deflection unit can illuminate the areas in the direction from the first point to the second point, while the second electro-optical deflection unit can illuminate the areas in the direction from the second point to the first point. This ensures that individual areas within the detection range are not illuminated simultaneously by the light beams from the two electro-optical deflection units. In this way, the radiation energy emitted within the detection range is distributed. This increases the safety of living beings during the operation of the optoelectronic sensor.

[0025] Preferably, the optical element has a coupling surface for each of the at least two electro-optical deflection units for coupling the deflected beams. The optical element can be connected to the respective electro-optical deflection units at the coupling surfaces. For example, the optical element can be bonded to the electro-optical deflection units using a material-bonded adhesive. A translucent adhesive can be used for this purpose. The material-bonded connection allows the electro-optical deflection units and the optical element to be mechanically and optically aligned relative to each other. A coating, and in particular an anti-reflective coating, can be applied to the respective coupling surfaces. This reduces losses during the transition of the light beams from the respective electro-optical deflection unit to the optical element.

[0026] Furthermore, it is advantageous if the optical element has a coupling surface for each of the at least two electro-optical deflection units for coupling out the light rays. The light rays deflected by the respective electro-optical deflection unit are first coupled into the optical element, and then the light rays transition from the optical element into the air. The shape and design of the optical element allow the respective light rays to be guided accordingly. The respective coupling surfaces can, in particular, be concave. Thus, it is possible, for example, for the light rays deflected by the respective electro-optical deflection unit within an angle of 100° to be deflected by the optical element within an angle of 150°.Consequently, the detection range of the optical sensor can be increased in a simple and reliable way.

[0027] It is specifically designed that the output surface comprises a plurality of segments, with each of the predetermined transmission angles assigned to a segment. As already explained, the light beams are deflected to the predetermined angles by the electro-optical deflection unit. For each deflection angle, the corresponding light beam is guided to a predetermined transmission angle. Furthermore, it is advantageous if the respective segments are designed as freeform lenses, microstructured surface areas, and / or diffractive optical elements. In particular, it is intended that the respective segments are manufactured using a microtechnical process.

[0028] In a further embodiment, the at least two electro-optical deflection units each have an optical fiber for guiding the light rays by total internal reflection at the interfaces of the optical fiber and an element for influencing the angle of incidence of the light rays entering the optical fiber and / or the angle of emergence of the light rays exiting the optical fiber. Within the electro-optical deflection unit, the respective light rays can be guided in the optical fiber. The element allows the angle of incidence at which the light rays enter the optical fiber and / or the angle of emergence of the light rays from the optical fiber to be changed. The element can, in particular, be configured such that its refractive index changes depending on an electric field applied to it. For example, the element can comprise a liquid crystal.In particular, it is planned that the electro-optical deflection units are each designed as a so-called Steerable Electro-Evanescent Optical Reflector (SEEOR).

[0029] An optoelectronic sensor according to the invention for a motor vehicle comprises a deflection device according to the invention. It is particularly provided that the optoelectronic sensor is designed as a scanning lidar sensor. The optoelectronic sensor can have a transmitter which includes the deflection device. Furthermore, the transmitter can include a corresponding light source, which is preferably designed as a laser diode. The optoelectronic sensor can also include a receiver, which, for example, includes a photodiode. In addition, the optoelectronic sensor can have a corresponding computing unit by means of which the emission of the light pulses can be controlled. Furthermore, the distance to the object can be determined with the computing unit based on the transit time. The deflection device and, in particular, the electro-optical deflection units can also be controlled with the aid of the computing unit.

[0030] A driver assistance system according to the invention comprises an optoelectronic sensor according to the invention. For example, the optoelectronic sensor can be used to determine the distance to an object or obstacle in the vicinity of the motor vehicle. Based on this distance, the driver assistance system can then issue a warning to the driver or intervene in the longitudinal and / or lateral control of the motor vehicle.

[0031] A motor vehicle according to the invention comprises a driver assistance system according to the invention. The motor vehicle is in particular designed as a passenger car. The motor vehicle can also be designed as a truck or a commercial vehicle.

[0032] A method according to the invention serves to operate a deflection device for an optoelectronic sensor of a motor vehicle. In this method, at least two electro-optical deflection units deflect light beams to predetermined deflection angles, each having an entry region into which the light beams are coupled and an exit region for coupling out the deflected light beams. Furthermore, the light beams deflected by the at least two electro-optical deflection units are guided by an optical element of the deflection device into a predetermined detection area, the optical element being connected to the respective exit regions of the at least two electro-optical deflection units.

[0033] The preferred embodiments and their advantages presented with reference to the deflection device according to the invention apply accordingly to the optoelectronic sensor according to the invention, the driver assistance system according to the invention, the motor vehicle according to the invention and the method according to the invention.

[0034] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the description of the figures and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments that are not explicitly shown and explained in the figures, but which can be derived and generated from the explained embodiments by separate combinations of features, are also to be considered as encompassed and disclosed by the invention.

[0035] Embodiments and combinations of features that do not exhibit all the features of an originally formulated independent claim are also considered disclosed. Furthermore, embodiments and combinations of features, particularly those described above, that go beyond or deviate from the combinations of features described in the cross-references of the claims are also considered disclosed.

[0036] The invention will now be explained in more detail with reference to preferred embodiments and the accompanying drawings.

[0037] This shows: Fig. 1 a motor vehicle according to an embodiment of the present invention, which has a driver assistance system with an optoelectronic sensor; Fig. 2 a deflection device according to an embodiment of the invention in a cutaway side view; Fig. 3 a top surface of an optical element of the deflection device according to Fig. 2; Fig. 4 a bottom side of the optical element of the deflection device according to Fig. 2; Fig. 5 a detailed view of a coupling surface of the optical element; Fig. 6 different configurations of detection areas of the deflection device; and Fig. 7 areas to which the light rays are directed by the deflecting device.

[0038] In the figures, identical and functionally equivalent elements are given the same reference symbols.

[0039] Fig. Figure 1 shows a top view of a motor vehicle 1 according to an embodiment of the present invention. The motor vehicle 1 is configured as a passenger car. The motor vehicle 1 includes a driver assistance system 2, which serves to assist the driver of the motor vehicle 1 in driving the motor vehicle 1. For example, the driver assistance system 2 can detect an object 3 located in the vicinity 4 of the motor vehicle 1. If the object 3 is detected, the driver assistance system 2 can issue a warning to the driver. Furthermore, the driver assistance system 2 can intervene in the steering, the braking system, and / or the drive motor to avoid a collision with the object 3.

[0040] To detect object 3, the driver assistance system 2 includes an optoelectronic sensor 5. The optoelectronic sensor 5 can be configured as a lidar sensor. Preferably, the optoelectronic sensor 5 is configured as a scanning lidar sensor. The optoelectronic sensor 5 includes a transmitter 6, by means of which light beams or light pulses can be emitted as a transmission signal. This is illustrated here by arrow 8. The light pulses can be emitted by the transmitter 6 in a predetermined range 12. For example, the light pulses can be emitted in a predetermined horizontal angular range. The optoelectronic sensor 5 also includes a receiver 7, by means of which the light pulses reflected by object 3 can be received again. This is illustrated here by arrow 9.

[0041] Furthermore, the optoelectronic sensor 5 includes a computing unit 10, which can be, for example, a microcontroller, a digital signal processor, or an FPGA. The computing unit 10 can control the transmitter 6 to emit the light pulses. In addition, the computing unit 10 can evaluate signals for the receiver 7, which are generated by the receiver 7 based on the received light pulses. Finally, the driver assistance system 2 includes an electronic control unit 11, which can output corresponding control signals depending on the object 3 detected by the optoelectronic sensor 5.

[0042] Fig. Figure 2 shows a deflection device 13, which is part of the transmitter 6 of the optoelectronic sensor 5. The deflection device 13 comprises at least one electro-optical deflection unit 14. In the present embodiment, the deflection device 13 comprises two electro-optical deflection units 14, which are connected to each other and arranged one above the other. Each of the electro-optical deflection units 14 has an entry area 18 for coupling in a light beam 16, 16'. A coating 24, which can be designed as an anti-reflective coating, is provided at the entry area 18. A first light beam 16 is supplied to the upper electro-optical deflection unit 14 and a second light beam 16' to the lower electro-optical deflection unit 14. These light beams 16, 16' can each be provided by a light source or a laser diode, respectively.

[0043] Furthermore, each electro-optical deflection unit 14 comprises an optical fiber 17 through which the respective light rays 16, 16' are guided. The respective light rays 16, 16' are guided by total internal reflection at interfaces of the optical fiber 17. The respective light ray 16, 16' exits the electro-optical deflection unit 14 at an exit region 18. In addition, each electro-optical deflection unit 14 comprises an element 19 by which the angle of incidence, at which the light ray 16, 16' enters the optical fiber 17, and the angle of exit, at which the light ray 16, 16' exits the optical fiber 17, can be influenced. The electro-optical deflection units 14 also comprise an electrode 20 by means of which an electric field acting on the element 19 can be influenced. The refractive index of element 19 can be influenced by the electric field.Thus, the angle of incidence and the angle of reflection can also be influenced. By adjusting the angle of incidence and / or the angle of reflection, a deflection angle α, α', at which the respective light beam 16, 16' exits the electro-optical deflection unit 14, can be influenced.

[0044] Furthermore, the deflection device 13 comprises an optical element 21. The optical element 21 is connected to the respective exit regions 18. The optical element 21 has a first coupling surface 22a, which is connected to the exit region 18 of the upper electro-optical deflection unit 14, and a second coupling surface 22b, which is connected to the exit region 18 of the lower electro-optical deflection unit 14. The optical element 21 has a coating 23 on each of the coupling surfaces 22a and 22b. This coating 23 can, in particular, be designed as an antireflection coating.

[0045] The respective light rays 16, 16', which are coupled out from the electro-optic deflection units 14, are coupled into the optical element 21. The light ray 16 from the upper electro-optic deflection unit 14 is reflected at a first reflective surface 25a and a second reflective surface 25b of the optical element 21. The optical element 21 may have a corresponding coating on the reflective surfaces 25a, 25b. After reflection at the reflective surfaces 25a, 25b, the light ray 16 exits the optical element 21 at a first output coupling surface 26a. This results in a transmission angle β, at which the light ray 16 is deflected. The light ray 16' from the lower electro-optic deflection unit 14 is refracted within the optical element 21 and exits the optical element 21 at a second output coupling surface 26b. The light beam 16' is also deflected at a predetermined transmission angle β'.Overall, the light rays 16 and 16' can be guided or deflected independently of each other by means of the optical element 21. Furthermore, a coating 27 is applied to each of the output coupling surfaces 26a, 26b of the optical element 21 to reduce losses during the output of the light rays 16, 16'.

[0046] Fig. Figure 3 shows the optical element 21 from Fig. 2 from a top side. Here, the first coupling surface 22a, which is rectangular, can be seen. This coupling surface 22a can be arranged at the corresponding exit region 18 of the upper electro-optical deflection unit 14. In particular, the optical element 21 can be bonded to the corresponding exit region 18 at the coupling surface 22a.

[0047] Fig. Figure 4 shows the optical element 21 from a bottom view. The second coupling surface 22, which is also rectangular, can be seen here. This coupling surface 22b can also be positioned at the corresponding exit area 18 of the lower electro-optical deflection unit 14 and, in particular, connected to it by a material bond. Furthermore, the first output coupling surface 26a and the second output coupling surface 26b are visible.

[0048] Fig. Figure 5 shows a detailed view of one of the output surfaces 26a, 26b. Both output surfaces 26a, 26b are concave. Furthermore, the output surfaces 26a, 26b have a plurality of segments 28. Each segment 28 is assigned a discrete emission angle β, β', at which the respective light beams 16, 16' are emitted. The respective segments 28 can be provided, for example, by a microtechnical manufacturing process. The segments 28 can be designed as freeform lenses or as diffractive optics. In this case, the segments 28 are designed as microstructured prismatic surfaces.

[0049] Using the optical element 21, the light rays 16, 16' can each be guided into a detection area 29a, 29b. A first detection area 29a is assigned to the upper electro-optical deflection unit 14, and a second detection area 29b is assigned to the lower electro-optical deflection unit 14. Fig. Figure 6 shows different detection areas 29a and 29b of the deflection device 13. On the left is a detection area 29, which is provided solely by an electro-optical deflection unit 14. In comparison, to the right of this detection area 29 are detection areas 29a and 29b, which can be scanned using the optical element 21. Detection areas 29a and 29b are identical. It can be seen that the detection area 29a and 29b can be enlarged by using the optical element 21. Furthermore, examples are shown where the detection areas 29a and 29b partially overlap or where they are different from each other.

[0050] Fig.Figure 7 shows different areas 32a, 32b, which are illuminated by the deflection device 13. This applies to the case where the detection areas 29a and 29b are identical or at least partially overlap. Within the detection areas 29a, 29b, areas 32a, 32b are defined, which are to be illuminated sequentially by the light beams 16, 16'. The first area 32a is assigned to the light beams 16 of the upper electro-optical deflection unit 14, and the second area 32b is assigned to the light beams 16' of the lower electro-optical deflection unit 14. In this case, the areas 32a, 32b run along trajectories 30a, 30b. The trajectories 30a, 30b have an offset 31 from each other. This offset 31 is due to the fact that the electro-optical deflection units 14 are arranged one above the other or with an offset from each other.

[0051] The areas 32a and 32b, to which different electro-optical deflection units 14 are assigned, are arranged alternately along the trajectories 30a and 30b. This allows a common detection area 29a and 29b, or an overlapping detection area 29a and 29b, to be scanned within a short time. Furthermore, different directions are specified for scanning with the light beams 16 and 16'. The light beams 16, originating from the upper electro-optical deflection unit, are guided from the upper left to the lower right along the trajectory 30a. The light beams 16', originating from the lower electro-optical deflection unit 14, are guided from the lower right to the upper left along the trajectory 30b. This prevents individual areas from being illuminated simultaneously by both light beams 16 and 16'. Thus, the radiant power introduced into the area can be reduced, thereby increasing safety.

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