VEHICLE WINDOW FOR RADAR ENVIRONMENT DETECTION AND METHOD FOR MANUFACTURING THE SAME

Description

[0001] The invention relates to a vehicle windshield for improved radar environment detection and a method for its production. The invention particularly relates to windshields designed for use with a radar sensor that employs a plurality of distributed radar transmitting and receiving sensors.

[0002] In the area of ​​passive safety systems in motor vehicles, as well as for autonomous driving at levels 4 and 5, the ability to distinguish between road users is of particular importance for both the protection of the occupants and the protection of other road users. This requires reliable environmental detection. To guarantee this, the vehicle's surroundings must be recorded with the highest possible resolution in all three spatial dimensions. Modern camera and LIDAR systems are capable of ensuring this environmental detection, but their quality is affected or even fails completely in poor visibility conditions such as fog, snow, or in the dark. Radar sensors, on the other hand, are not subject to these limitations; however, to achieve high-resolution three-dimensional imaging, they must be arranged in an array with a large number of sensors.

[0003] Furthermore, the individual sensors in such an array must be synchronized with regard to their transmission and reception times. Such synchronization is technically extremely demanding. Therefore, it is advantageous for the individual radar sensors to be as small, simple, flexible, fault-tolerant, robust, and inexpensive as possible. To achieve this, as little electronics as possible should be installed on the radar sensor itself, and digital data processing should be carried out centrally within a central control unit.

[0004] It is known from the state of the art to use radar systems behind a windshield that transmit and receive radar waves through the windshield.

[0005] EP 2 808 698 A2 shows such a system, in which the windshield has a metallization layer to block infrared radiation from entering the vehicle interior. Since this metallization layer blocks radar radiation, the metallization layer has a recess in front of the radar system.

[0006] DE 10 2017 103 083 A1 describes an electromagnetic coupler that couples antenna signals for a broadband antenna positioned between glass layers of a vehicle's windshield. The coupler comprises a first coplanar waveguide (CPW) formed on one side of one glass layer and a second CPW formed on the other glass layer, wherein the first and second CPWs are mirror or near-mirror images of each other, rotated by 180°. Both the first and second CPWs comprise a conductive plane in which distant portions of the plane define a wide CPW portion and a narrow CPW portion that are electrically coupled to each other, and wherein the remaining portions of the conductive plane are grounded planes, and wherein the electromagnetic signals are coupled through the glass layer between wide CPW portions.

[0007] WO 2010 / 042 483 A1 describes an integrated radar-camera sensor comprising a camera sensor component and a radar sensor component, both housed in a common single-module housing. The sensor module also includes processing circuitry for processing the radar sensor and camera outputs. The sensor module is located behind the windshield of a vehicle and may include glare and / or EMI shields.

[0008] In order to achieve high resolution in both azimuth and elevation, a large number of sensors are necessary. Arranging and operating these in a motor vehicle in such a way that the desired high resolution can also be achieved for imaging or image processing methods has not yet been satisfactorily achieved in known vehicles. The technical problem is to enable the arrangement of a plurality of sensors and, in particular, operation of a plurality of radar sensors in vehicles with improved transmission and reception properties. This problem is solved according to the invention with the aid of a vehicle window according to claim 1 and a method for producing a vehicle window according to claim 9. Advantageous embodiments arise from the subclaims.

[0009] The invention is based on the idea of ​​designing the vehicle window with a plurality of radar waveguides via which radar radiation or radar waves are transmitted more effectively through the vehicle window when sending and receiving from and to radar sensors. The radar waveguides are implemented via refractive index variations in the window body of the vehicle window. It is generally known that electromagnetic radiation or electromagnetic waves propagating in a first medium having a first refractive index are completely or almost completely reflected at an interface to a second medium having a lower refractive index than the first medium and at an angle to the interface that exceeds a predetermined angle when measured against a surface normal to the interface.

[0010] In particular, a vehicle window for radar environment detection is thus created, which window body comprises a window body with an inner side and an outer side, wherein the window body comprises a plurality of radar waveguides for guiding radar radiation from the inner side to the outer side and / or vice versa, wherein the radar waveguides bring about waveguiding of radar radiation via refractive index variations.

[0011] A method for producing a vehicle window for radar environment detection comprising the steps of: producing or providing a window body having an inner side and an outer side, wherein a plurality of radar waveguides for guiding radar radiation from the inner side to the outer side and / or vice versa are formed in the window body, wherein the radar waveguides bring about waveguiding of radar radiation via refractive index variations

[0012] Radar waveguides can be formed in the vehicle window, which is preferably a windshield, via a refractive index variation in the material of the window body. This achieves very good integration into the vehicle window, which does not impair the mechanical stability of the vehicle window. Thus, in one embodiment, the refractive index variations of at least one of the plurality of radar waveguides are formed via a refractive index modulation in the material of the window body.

[0013] The formation of the radar waveguide via refractive index variations in the material of the disk body can already be achieved via local changes in the disk material during the manufacture of the disk body.

[0014] A particularly advantageous embodiment provides that the refractive index variations of at least one radar waveguide of the plurality of radar waveguides are formed via a refractive index modulation in the material of the disk body.

[0015] In one embodiment, one or more of the radar waveguides are created by applying refractive index modulations using nonlinear multiphoton processes. For this purpose, for example, a focus of a focused laser is moved within the volume of the material of the disk body. At the focus of the laser radiation, the refractive index of the material is locally altered due to nonlinear multiphoton processes. By moving the focus to different positions in the material, the refractive index in the material can be locally varied. Multiphoton processes are used to locally alter the density of the material and, as a result, the refractive index.

[0016] In this case, it is possible to create different spatial structures of the refractive index variations. This makes it possible for at least one radar waveguide or at least one other of the plurality of radar waveguides to have a horn antenna structure.

[0017] Preferably, all of the radar waveguides in the plurality of radar waveguides have a horn antenna structure. This significantly improves the emission of radar radiation via the individual optical waveguides. Furthermore, the waveguiding of reflected radar radiation, which is guided from the outside to the inside of the disk body, is also improved.

[0018] Other embodiments may include other structures that promote the emission of radar radiation or the reception and transmission of radar radiation to a sensor. As with a horn antenna-like structure, this can influence the radiation characteristics of the emitted radar radiation as well as the reception properties of a sensor coupled to the radar waveguide.

[0019] In order to also utilize the polarization of the emitted and received radar radiation for environmental detection, individual, several, or all of the radar waveguides are designed to promote the emission of radar waves or radar radiation exhibiting a specific polarization direction. The decisive factor here is the polarization direction of the emitted radiation at a distance from the outside of the windshield body, i.e., in the far field of the radar radiation. This can be linearly polarized radar radiation, whose polarization direction, at a distance from the vehicle windshield, indicates the polarization direction of the corresponding radar waveguide.

[0020] The polarization directions that can be assigned to individual radar waveguides must therefore be specified with respect to a coordinate system that is fixedly coupled to the body of the vehicle windscreen.

[0021] In addition to the preferential guidance of radar waves or radar radiation which has a linear polarization direction when exiting the outer side of the disc body, the guidance of circularly polarized radar waves or circularly polarized radar radiation or other polarized radar radiation can also be favored.

[0022] In order to be able to take into account a polarization of the radar radiation and its change during reflection when measuring the surroundings, one embodiment provides that a plurality of radar waveguides of the plurality of radar waveguides, each in pairs, promote a different polarization of the radar radiation emerging and / or entering an outer side of the vehicle window during the waveguiding.

[0023] This particularly preferably applies to adjacent radar waveguides of the plurality of radar waveguides. This means that, when a plurality of radar waveguides are arranged along a spatial direction, the adjacent radar waveguides in pairs promote radar waves or radar radiation of a different polarization direction in the waveguide. However, the condition that the plurality of radar waveguides each have a different polarization direction in pairs preferably applies to all radar waveguides of the plurality of radar waveguides, which means that they each promote a distinct polarization direction of the emitted or received radar radiation in the waveguide, wherein the distinct polarization directions are all different.

[0024] In order to improve the analysis of the radar waves or radar radiation emitted and radiated via the various radar waveguides and to achieve high environmental resolution, a temporal correlation between the emission times and reception times of the various radar waveguides is necessary. This means, for example, that the emission of the radar radiation must be synchronized over the various radar waveguides, i.e., coordinated in time. Particularly if the radar radiation emitted and received by the individual radar waveguides is generated and recorded by radar chips individually coupled to the individual radar waveguides, it is advantageous to know the distances between the radar waveguides and to be able to measure them regularly.

[0025] For this purpose, in one embodiment it is provided that the radar waveguides of at least one group of the plurality of radar waveguides are connected to one another directly or indirectly via calibration waveguides of the plurality of calibration waveguides.

[0026] A vehicle window thus advantageously comprises a plurality of calibration waveguides, wherein each of the calibration waveguides is designed to guide radar radiation due to total reflection at least between two radar waveguides connected by means of the corresponding calibration waveguide, wherein a part of the radar radiation entering one of the interconnected radar waveguides on the inside of the sliding body exits the other of the interconnected radar waveguides on the inside of the window body, or vice versa.

[0027] One embodiment of the invention provides that the adjacent radar waveguides of the at least one group of radar waveguides are each connected to a calibration waveguide.

[0028] Preferably, the calibration waveguides are configured such that, if a radar signal from the radar chip coupled to this radar waveguide is the only one transmitted via this radar waveguide, all other radar chips coupled to one of the radar waveguides in the group receive a "direct signal" via the calibration waveguides, against which these other radar chips can temporally synchronize the reflected received radar radiation. This means that the radar waveguides are all linked to one another with regard to the transmission of radar radiation.

[0029] In a preferred embodiment, the calibration waveguides are formed by guiding a focal point of a laser in the material of the sliding body to form refractive index variations by means of nonlinear multiphoton interaction.

[0030] It is also possible to create the calibration waveguides by locally modifying the material during the manufacturing of the disk body. For example, the material intended to guide the radar radiation is surrounded by material with a lower refractive index.

[0031] In still other embodiments, the calibration waveguides are formed by inserting polymer material into the disk body.

[0032] The radar waveguides can also be partially or completely formed using polymer material that is inserted into recesses in the disk body. One embodiment provides that at least some of the radar waveguides are formed using polymer material that is inserted into recesses in the disk body.

[0033] In particular, to minimize coupling and decoupling losses on an outer side of the disk body and possibly also to protect the optical waveguides, some embodiments provide for the radar waveguides of the plurality of radar waveguides to be covered on an outer side of the disk body by at least one antireflection layer, the layer thickness of which is an integer multiple of a quarter of the radar wavelength intended for the waveguide in the antireflection layer. The disk body is thus coated on the outer side, at least in the region of the radar waveguides, with a corresponding antireflection layer.

[0034] The anti-reflection coating is preferably refractive index-matched to minimize reflection of radar radiation upon exiting / entering the pane body. This means that the refractive index is matched to the wavelength of the radar radiation, i.e., a material with the required refractive index at the wavelength of the radar radiation is selected, or the refractive index of the anti-reflection coating material is adjusted to the wavelength of the radar radiation using material additives, so that transmission for the radar radiation is optimal. Thus, a coating is applied for the radar wavelength.

[0035] Other embodiments may provide for the anti-reflection coating to be or be formed in multiple layers in order to significantly favor the coupling and decoupling of radar radiation of a specific wavelength or wavelength range over other wavelengths or wavelength ranges. This minimizes reflections and thus significantly reduces coupling and decoupling losses. For this purpose, the refractive indices of the individual layers are preferably selected and determined using simulation calculations.

[0036] Other embodiments and / or further developments may provide that the material layer thicknesses of the layers are alternatively or additionally included in the simulation.

[0037] Embodiments in which at least one group of radar waveguides of the plurality of radar waveguides is arranged at equal distances from one another have proven particularly advantageous. Preferably, the radar waveguides of this at least one group are arranged along a straight line.

[0038] In order to visually conceal the radar chips coupled to the radar waveguides from human observation when viewing the vehicle window, particularly from the outside, some embodiments provide for the window body to be opaque in the visible wavelength range in the region of the plurality of radar waveguides by means of a print in the visible wavelength range. In such embodiments, the plurality of radar waveguides is thus advantageously arranged in a black print area of ​​the window body.

[0039] The invention will be explained in more detail below with reference to a drawing in which: Fig. 1 is a schematic front view of a vehicle with radar-based environment detection; and Fig. 2 is a sectional view through a vehicle window with two magnified sections, one of which shows a radar waveguide on an outer side of the vehicle window and the other on an inner side of the vehicle window.

[0040] In Fig. 1A front view of a vehicle 1 is shown schematically. The vehicle comprises an environment detection system 5. This environment detection system 5 comprises at least one radar device 30. In the embodiment shown, the radar device 30 has a plurality of radar chips 31-1 to 31-n, each of which can generate and detect radar radiation. In a preferred embodiment, the radar signals detected by the individual radar chips 31-1 to 31-n are evaluated in a central evaluation device 33. For this purpose, the individual radar chips 31-1 to 31-n are coupled to the central evaluation device 33 via information lines 34-1 to 34-n. The central evaluation device 33 makes environment data 35 available to other devices 7 of the vehicle 1. For example, this can be done in the form of a pictorial representation.The environmental data may include information about the positions of objects relative to the vehicle 1, their relative speed to the vehicle, relative speeds to other objects in the environment 2 of the vehicle 1, a relative acceleration relative to the vehicle 1 and / or relative to other objects in the environment 2. However, the environmental data 35 may also include information about positions in the environment 2 of the vehicle at which no objects are detected, i.e., which are free.

[0041] In Fig. 1The information lines 34-1 to 34-n are partially drawn outside the vehicle contour. However, it will be understood by those skilled in the art that the information lines 34-1 to 34-n are naturally formed inside the vehicle. Likewise, the central evaluation device 33, the additional devices 7, and communication connections 8, which are designed, for example, as a vehicle bus 9, are only shown schematically. The devices 7 can be any devices of the vehicle 1 that evaluate and / or use environmental data, for example, driver assistance systems, control devices for autonomous driving, etc.

[0042] The suffixes "-1, -2, -i, -m, -k,... -n" are intended to distinguish objects of the same type, where n, i, k, m are each natural numbers.

[0043] The radar chips 31-1 to 31-n can be equipped with or without an antenna. These are arranged inside the vehicle 1, i.e., behind a vehicle window 10. In the present example, the vehicle window 10 is a windshield 11 of the vehicle 1 embodied as a motor vehicle 3. In the example shown, the radar chips 31-1 to 31-n are arranged on an upper edge 13, preferably in the region of a black print 12. The black print 12 is opaque in the visible wavelength range, so that the radar chips 31-1 to 31-n arranged behind the windshield 11, when viewed from the outside, are not or almost not perceptible to a human observer. The black print 12 is preferably designed such that it does not adversely affect the propagation of radar waves or radar radiation.

[0044] In order to minimize attenuation losses of the radar radiation generated and emitted by the radar chips 31-1 to 31-n, as well as the reflected radar radiation 100', at the vehicle window, the vehicle window is configured with a plurality of radar waveguides 41-1 to 41-n. In the illustrated embodiment, there is exactly one radar waveguide 41-1 to 41-n for each radar chip 31-1 to 31-n. In other embodiments, the number of radar waveguides 41 of a vehicle window 10 can be greater than the number of radar chips 31 arranged behind the vehicle window 10.

[0045] In Fig. 2A schematic sectional view through a vehicle window 10 is shown. The vehicle window 10 comprises a window body 50. A plurality of radar waveguides 41-1 to 41-n are formed in the window body 50. These are preferably arranged at equal spacing. The spacing between adjacent radar waveguides 41-i, 41-i+1 preferably corresponds to an integer multiple of the wavelength of the radar radiation used in the material of the window body.

[0046] Each of the waveguides 41 is coupled to one of the radar chips 31 on an inner side 17 of the vehicle window 10. The coupling is effected such that the radar radiation 100 generated by the radar chip 31 is coupled into the corresponding radar waveguide with as little loss and attenuation as possible. The radar radiation 100 is guided by the radar waveguide 31 through the window body 50 of the vehicle window 10 and radiated on an outer side 18 of the vehicle window 10 into the surroundings 2 of the vehicle 1. Part of the emitted radar radiation 100 is reflected by objects (not shown) in the surroundings 2 of the vehicle 1.The reflected radar radiation 100' strikes the vehicle window 10 again and is at least partially coupled, with as little loss as possible, into the radar waveguide 41 and guided by this radar waveguide 41 through the vehicle window 10 to the inner side 17 and coupled out there, so that the reflected radar radiation 100' can be detected by the radar chip 31, which is coupled to the corresponding radar waveguide 41.

[0047] It is understood that the wheel radiation guided through one of the radar waveguides 31-i of the plurality of radar waveguides 31-1 to 31-n to the outer side 18 of the vehicle window and radiated there, after being reflected, is guided not only by the radar waveguide 41-i, but generally also by the other radar waveguides 41-k (k≠i) through the vehicle window 50 to the radar chips 31-k correspondingly coupled thereto.

[0048] The following briefly explains how radar wave transmission occurs in a volume of material that is transparent to the corresponding wavelength range. Both glass and most transparent plastics are transparent not only in the visible wavelength range, but also in the radar wavelength range.

[0049] A material is transparent to radiation in volume if geometric imaging is possible through the volume of the material with the radiation. In particular, there is no scattering of radiation within the volume of the material, which would lead to a diffuse impression of the material, for example, with radiation in the visible wavelength range.

[0050] At an interface between a first material with a first refractive index n 1 and a second material with a refractive index n 2 , where the first refractive index n 1 is greater than the second refractive index n 2 , total internal reflection of the radiation propagating in the first material occurs at shallow angles of incidence. This property of total internal reflection can be exploited to form waveguides. This property, known from the visible wavelength range, also exists in the radar wavelength range. A radar waveguide is therefore a waveguide that is capable of guiding electromagnetic waves or electromagnetic radiation in the radar wavelength range that propagates in the material due to reflections from refractive index variations.

[0051] This is shown as an example in an enlarged section A of an exit area of ​​one of the radar waveguides 41-1 on the outer side 18 of the vehicle window 1.

[0052] A radar beam 101 of radar radiation 100, propagating in the material 39 of the radar waveguide 41-1 with a refractive index n 1 , strikes the material 59 of the disk body 50 with the refractive index n 2 at a shallow angle. The radar beam 100 is reflected at the interface between the material 39 of the radar waveguide 41-1 and the material 59 of the disk body 50. This causes waveguiding of the radar beam 101, and thus of the radar radiation 100, in the radar waveguide 31-1. The refractive index n 2 ' is smaller than the refractive index n 1 .

[0053] The waveguiding of the radar radiation 100, which is generated in one of the radar chips 31, through the vehicle window 10 thus occurs by coupling the radar radiation 100 into the associated radar waveguide 41 on the inner side 17 of the vehicle window 10. In the material 39 of the radar waveguide 41, the radar radiation 100 is reflected at an interface with the material 59 of the window body 50 and thus guided through the vehicle window 10 with low loss. On the outer side 18 of the vehicle window 10, the radar radiation 100 exits the radar waveguide 41 and is radiated into the surroundings 2 of the vehicle 1.Radar radiation 100' reflected there by objects (not shown) is coupled in the opposite direction on the outer side 18 of the vehicle window 2 into the radar waveguide 41, guided via reflections at the interface to the material 59 of the window body 50 and coupled out of the radar waveguide 41 on the inner side 17 of the vehicle window 10 and guided to the radar chip 31 for detecting the reflected radar radiation 100'.

[0054] In order to reduce reflection losses when the radar radiation 100 exits the radar waveguide 41, the vehicle window 2 preferably has an anti-reflection coating 70 on the outer side 18. The material 79 of the anti-reflection coating 70 is preferably adapted in terms of refractive index to the wavelength of the emitted radar radiation 100 in the anti-reflection coating 70.

[0055] A layer thickness 72 of the anti-reflection layer 70 corresponds to an integer multiple of a quarter of the wavelength λ of the radar radiation in the material 79 of the anti-reflection layer 70. If the layer thickness 72 is designated by s, the following applies: s = m λ / 4, where m is a natural number.

[0056] The anti-reflection layer 70 can also be formed in multiple layers, in which case the individual layers each have a layer thickness that corresponds to an integer multiple of a quarter of the wavelength of the radar radiation in the material of the corresponding layer.

[0057] In the simple embodiment of a radar waveguide 41, as simplified in Figure 2and in particular the enlarged section A, it is assumed that the radar waveguide has a cylindrical shape. However, it is preferred that the optical waveguide 41 has a more complex structure, for example that of a horn antenna. This means that the refractive index variations between the material of the radar waveguide and the material of the disk body represent more complex geometric structures in the volume of the disk body. This makes it possible to influence a radiation direction and beam characteristic of the emitted radar radiation 100. It is also possible to influence a polarization direction of the emitted radar radiation.

[0058] In the illustrated embodiment in Figure 2a direction 45-i of polarization for each of the radar waveguides 41-i of the plurality of radar waveguides is schematically indicated, under which direction the radar radiation 100 emerges from the respective radar waveguide 41-i on the outer side 18 of the vehicle window 10.

[0059] The polarization directions 45-1 to 45-n of the individual radar waveguides 41-1 to 41-n change gradually along the linear arrangement of the radar waveguides. The angular difference in the polarization directions between adjacent radar waveguides 41-i and 41-i+1 is thus constant. The polarization directions are shown here in the plane of the drawing, although they refer to a plane perpendicular to it.

[0060] If the radar waveguides 41 are designed in such a way that they influence the polarization direction of the guided radar radiation 100, polarimetric measurements can be carried out.

[0061] In order to facilitate and / or enable the evaluation of the individual radar signals detected from the reflected radar radiation 100' with a high resolution, calibration waveguides 81, 81-1 to 81-m are preferably formed on the inner side 17 of the vehicle window 10 between the radar waveguides 41. For reasons of clarity, Fig. 2 only one calibration waveguide 81 is shown. However, a calibration waveguide is formed between each adjacent radar waveguide, as shown in the enlarged section B. Each radar waveguide that has two adjacent radar waveguides is coupled to each of these two with its own calibration waveguide, thus a total of two or more.

[0062] Magnified section B shows two adjacent radar waveguides 41-i, 41-i+1, as well as their coupled radar chips 31-i, 31-i+1. The calibration waveguide 81-i is configured to guide a portion 100" of the radar radiation 100 coupled into the radar waveguide 41-i from the inner side 17 of the vehicle window 10 to the adjacent radar waveguide 41-i+1, so that at least a portion of this radar radiation 100" guided through the calibration waveguide can be detected by the radar chip 31-i+1.

[0063] Preferably, each of the radar waveguides 41-i is coupled to its immediately adjacent radar waveguides 41-i-1, 41-i+1 via calibration waveguides 81-i-1 and 81-i. This enables synchronization and calibration between the individual radar chips 31.

[0064] The radar waveguides 41 and the calibration waveguides 81 can be integrated into the vehicle window 10 in different ways.

[0065] In one embodiment, recesses are first formed in the vehicle window, for example, through-openings for the radar waveguides. These are then filled with a material having a higher refractive index n 1 relative to the refractive index n 2 of the vehicle window material. A suitable material for this purpose is, for example, a polymer material that is inserted into recesses in the glass pane body 50 of the vehicle window 10.

[0066] The calibration waveguides 81 can also be manufactured in this way by filling recesses in the window body 50 of the vehicle window 10 with polymer material.

[0067] The production of the radar waveguides 41 and / or the calibration waveguides 81 using nonlinear multiphoton processes has proven particularly advantageous and flexible. Focused laser radiation can be used to locally change the density of transparent materials and, as a result, the refractive index at the focus of the laser radiation. By guiding the focus of the laser radiation through the volume of the disk body, complex refractive index variations can be introduced into the disk body, allowing both radar waveguides 41 and calibration waveguides 81 to be formed in this way. The properties of the radar waveguides 41 can be influenced in a variety of ways. For example, the radar waveguides 41 can be given a horn antenna structure and / or their polarization properties can be adjusted and influenced.

[0068] A particular advantage is that radar waveguides or calibration waveguides can be integrated into pre-fabricated vehicle windows with high precision. Any complex refractive index variation can be realized.

[0069] By inserting material, in particular polymer material, into recesses of the disc body, the radar waveguides can be formed with horn antenna structures and / or the polarization properties of the radar waveguides can be adjusted if the recesses are suitably shaped.

[0070] Furthermore, it is possible to locally vary the refractive index properties during the manufacture of the disk body, thereby forming the radar waveguides or calibration waveguides directly during the manufacture of the disk body. To this end, the material in which radar waveguides are desired is surrounded by material with a lower refractive index.

[0071] The anti-reflection layer 70, which can be formed in one or more layers, is preferably applied over the entire surface of an outer side of the pane body 50. To avoid light refraction at the anti-reflection layer in the visible wavelength range, the refractive index of the anti-reflection layer 70 is adapted to the material 59 of the pane body 50. A multi-layer anti-reflection layer has a combination of layers of different materials and thus different refractive indices in order to generate phase jumps at the interfaces or transitions and thereby optimize transmission for the radar wavelength or for a wavelength range around the radar wavelength and, if necessary, for an angular range of the emission of the radar radiation at the radar wavelength. The layer sequence is preferably determined by means of simulation calculations.

[0072] With a radar device 30 that uses radar chips 31 in combination with radar waveguides 41, which are integrated with high precision into a vehicle window 10, resolutions of the surroundings 2 of the vehicle 1 can be achieved that are comparable to those of a LiDAR (Light Detection and Ranging) system.

[0073] Particularly high resolutions can be achieved if the radar waveguides are connected to calibration waveguides for temporal synchronization and calibration.

[0074] In the embodiment described here, the radar waveguides are formed along the upper edge 13 of the vehicle window 10, which is designed as a windshield 11. Additionally or alternatively, the radar waveguides can also be formed on a right side edge 14, a left side edge 15, and / or a lower edge 16 of the vehicle window. Radar waveguides, and in this case, calibration waveguides, can also be formed at other positions.

[0075] Particularly preferably, the vehicle window 2 is printed with an opaque color, for example a black color, in an area in which the radar waveguides 41 are formed in order to conceal the radar chips 31 coupled to the radar waveguides 41.

[0076] In the described embodiment, the vehicle window 10 is a windshield 11. However, the vehicle window can also be any other window of the vehicle, for example a rear window, a side window, etc. In such a case, the radar waveguides are formed, for example, adjacent to an A-pillar, B-pillar, C-pillar and / or an upper or lower edge of the window.

[0077] The radar chips coupled to the plurality of radar waveguides may belong to one or more radar devices.

[0078] In the case of tilted and / or curved vehicle windscreens, the directions along which the radar radiation is guided in the radar waveguides may differ from the local surface normals of the vehicle windscreen on the inside and / or outside of the vehicle windscreen. This means that in such a case, the radar waveguides are not oriented perpendicular to the vehicle windscreen. List of reference symbols

[0079] 1Vehicle 2Environment 3Motor vehicle 5Environment detection system 7Devices 8Communication connections 9Vehicle bus 10Vehicle window 11Windshield 12Black print 13Top edge 14Right side edge 15Left side edge 16Lower edge 17Inside 18Outside 30Radar device 31, 31-1 to 31-nRadar chips 33Central evaluation device 34-1 to 34-nInformation lines 35Environment data 39Radar waveguide material 41, 41-1 to 41-nRadar waveguide 45- 1 to 45-nPolarization directions 50Window body 59Window body material 70Antireflection coating 72Layer thickness 79Antireflection coating material 81Calibration waveguide 100Radar radiation 100' reflected radar radiation 100" part of the coupled radar radiation 101 radar beam

Claims

1. Vehicle window (10) for radar environment detection, comprising: a window body (50) having an inner side (17) and an outer side (18), characterized in that the window body (50) comprises a plurality of radar waveguides (41, 41-1 to 41-n) for guiding radar radiation from the inner side (17) to the outer side (18) and / or vice versa, the radar waveguides (41, 41-1 to 41-n) bringing about waveguiding of radar radiation (100) via refractive index variations.

2. Vehicle window (10) according to claim 1, characterized in that the refractive index variations of at least one radar waveguide (41, 41-1 to 41-n) of the plurality of radar waveguides (41, 41-1 to 41-n) are formed via refractive index modulations in the material (59) of the window body (50).

3. Vehicle window (10) according to claim 2, characterized in that the refractive index modulations are formed by means of nonlinear multiphoton processes.

4. Vehicle window (10) according to any of the preceding claims, characterized in that the at least one radar waveguide (41, 41-1 to 41-n) or at least another one of the plurality of radar waveguides (41, 41-1 to 41-n) has a horn antenna structure.

5. Vehicle window (10) according to any of the preceding claims, characterized in that a majority of radar waveguides (41, 41-1 to 41-n) of the plurality of radar waveguides (41, 41-1 to 41-n) each in pairs promote a different polarization of the radar radiation emerging from and / or entering an outer side of the vehicle window (10) during the waveguiding.

6. Vehicle window (10) according to any of the preceding claims, characterized by a plurality of calibration waveguides, each of the calibration waveguides being designed to guide radar radiation due to total reflection at least between two radar waveguides (41, 41-1 to 41-n) connected by means of the corresponding calibration waveguide, a portion of the radar radiation that enters one of the interconnected radar waveguides (41, 41-1 to 41-n) on the inner side of the window body emerging from the other of the interconnected radar waveguides (41, 41-1 to 41-n) on the inner side of the window body (50) or vice versa.

7. Vehicle window (10) according to any of the preceding claims, characterized in that at least some of the radar waveguides (41, 41-1 to 41-n) are formed by means of polymer material which is inserted into recesses of the window body (50).

8. Vehicle window (10) according to any of the preceding claims, characterized in that the radar waveguides (41, 41-1 to 41-n) of the plurality of radar waveguides (41, 41-1 to 41-n) are covered on an outer side of the window body (50) by at least one anti-reflection layer, the layer thickness of which is an integer multiple of a quarter of the radar wavelength provided for the waveguide in the anti-reflection layer.

9. Method for producing a vehicle window (10) for radar environment detection, comprising the steps of: producing or providing a window body (50) having an inner side and an outer side, wherein a plurality of radar waveguides (41, 41-1 to 41-n) for guiding radar radiation from the inner side to the outer side and / or vice versa are formed in the window body (50), wherein the radar waveguides (41, 41-1 to 41-n) bring about waveguiding of radar radiation via refractive index variations.

10. Method according to claim 9, characterized in that refractive index modulations are formed by means of non-linear multiphoton processes in a material (59) of the window body (50) by moving a focus of a focused laser in the volume of the material of the window body (50).

11. Method according to one of claims 9 or 10, characterized in that calibration waveguides are formed between the reflection waveguides.