LiDAR sensor

Abstract

The present invention relates to a lidar sensor, comprising: an optical transmission unit for emitting a scanning beam in its optical axis direction; an optical reception unit for receiving a reflected scanning beam after the scanning beam is reflected in the surrounding environment of the lidar sensor, the optical reception unit having a main reception direction oriented along its optical axis; deflection optics including a first mirror and a second mirror, the optical axis of the optical transmission unit being oriented to the first mirror and the optical axis of the optical reception unit being oriented to the second mirror, the optical transmission unit and the optical reception unit being arranged on a first side of the deflection optics in the optical path of the lidar sensor; a scanning unit arranged in the optical path on a second side of the deflection optics and configured to deflect the scanning beam reflected by the deflection optics in different directions to sample the surrounding environment of the lidar sensor by means of the scanning beam and deflect the reflected scanning beam back onto the deflection optics.

Description

Technical Field

[0001] The present invention relates to a lidar sensor having an optical transmission unit, an optical reception unit, and a scanning unit. Background Art

[0002] So far in the automotive field, there are basically lidar sensors designed for driver assistance systems. These lidar sensors usually have a forward-oriented field of view. Although these lidar sensors have a large horizontal field of view, the operating range decreases significantly as the distance from the central axis increases.

[0003] When using lidar sensors for autonomous driving, systems with active rotors are used in test vehicles. These systems naturally have a very large horizontal opening angle and a constant operating range over this opening angle. However, this system has several disadvantages for series use in vehicles. Thus, part of the electronics rotates while another part is stationary. This requires significantly more electronics, including energy and data transmission between the stator and the rotor. This results in increased costs and a shortened service life. In addition, due to the vibrations caused by the vehicle, the requirements for the stability of the lidar sensor lead to heavy rotor structures. Therefore, large bearings and very powerful motors are required. Furthermore, the electronics of the rotor can only be cooled through the air in the lidar sensor. Thus, with a given maximum temperature of the electronic components, the allowable housing temperature of the lidar sensor is mostly very low. However, with high power consumption, the requirements for vehicle cooling are very high. In addition, the lidar sensor is very large in structure. This makes it difficult to integrate into the vehicle.

[0004] In addition, in such a lidar sensor with an active rotor, the starting point of the sampling system is on the sensor central axis. Therefore, if the lidar sensor is to be used on a vehicle, a large area around the lidar sensor on the vehicle body must be kept free. Summary of the Invention

[0005] The lidar sensor according to the present invention includes an optical transmission unit, an optical reception unit, a deflecting optical device, and a scanning unit. The optical transmission unit is arranged to emit a scanning beam in the direction of the optical axis of the optical transmission unit. The optical reception unit is arranged to receive the reflected scanning beam after the scanning beam has been reflected in the surroundings of the lidar sensor, wherein the optical reception unit has a main reception direction oriented along the optical axis of the optical reception unit. The deflecting optical device includes a first mirror surface and a second mirror surface, wherein the optical axis of the optical transmission unit is oriented onto the first mirror surface, and the optical axis of the optical reception unit is oriented onto the second mirror surface, wherein the optical transmission unit together with the optical reception unit is arranged on a common first side of the deflecting optical device in the optical path of the lidar sensor. The scanning unit is arranged on a second side of the deflecting optical device in the optical path of the lidar sensor and is arranged to deflect the scanning beam reflected by the deflecting optical device into different directions in order to sample the surroundings of the lidar sensor with the scanning beam and deflect the reflected scanning beam back into the deflecting optical device.

[0006] The optical transmission unit is in particular a laser by which the scanning beam is emitted. Here, the optical axis of the optical transmission unit is the direction defining the central propagation direction of the scanning beam. The optical reception unit is an optical sensor which is in particular arranged to receive light of the following wavelength: the light of this wavelength is emitted by the optical transmission unit. The optical reception unit has a main reception direction oriented along the optical axis of the optical reception unit. This means that the optical reception unit can be oriented in a defined direction in order to detect light incident from this direction. This direction is the main reception direction. The optical axis of the optical reception unit corresponds to this main reception direction in terms of orientation. If the optical transmission unit and / or the optical reception unit includes a lens arranged in front of the active transmission or reception area of the optical transmission unit or the optical reception unit, the optical axis of the optical transmission unit or the optical reception unit corresponds to the optical axis of the lens arranged in front of it.

[0007] After the scanning beam has been scattered in the surroundings of the lidar sensor, a reflected scanning beam is generated by the scanning beam. Thus, the reflected scanning beam is the reflected part of the scanning beam.

[0008] The deflection optical device includes one or more optical elements that are suitable for influencing the direction of the emitted scanning beam and the received reflected scanning beam. Thus, the deflection optical device has a first mirror surface and a second mirror surface. The first mirror surface is preferably the surface of the first mirror, and the second mirror surface is preferably the surface of the second mirror. However, optionally, the first mirror surface and the second mirror surface are different portions of a common mirror surface of a single mirror. The optical transmitting unit together with the optical receiving unit is arranged on a common first side of the deflection optical device in the optical path of the lidar sensor. This means that the optical transmitting unit and the optical receiving unit are directed onto the deflection optical device from the common side. Here, the optical path is either an optical transmitting path or an optical receiving path. The optical path is in particular a combination of the optical transmitting path and the optical receiving path. Here, the common side is defined by the following common direction: the scanning beam impinges on the deflection optical device from this common direction, and the reflected scanning beam is projected in this common direction onto the optical receiving unit. The optical path of the lidar sensor is the connection between the optical transmitting unit and the optical receiving unit through the deflection optical device and the scanning unit up to the point where the scanning beam exits the lidar sensor and the reflected scanning beam enters the lidar sensor at this point.

[0009] The scanning unit is arranged on a second side of the deflection optical device in the optical path of the lidar sensor. This means that the scanning beam is projected from the optical transmitting unit through the first mirror surface of the deflection optical device onto the scanning unit. In the opposite way, the reflected scanning beam is projected from the scanning unit onto the second mirror surface of the deflection optical device and reflected from there onto the optical receiving unit. The scanning unit is in particular a rotating mirror system or an oscillating mirror.

[0010] Since the optical transmitting unit and the optical receiving unit are directed onto the deflection optical device from the same direction, it may occur that the light emitted as a scanning beam by the optical transmitting unit is directly reflected into the optical receiving unit, whereby the optical receiving unit is blind (geblendet) within a certain time range. Therefore, it is advantageous if the optical receiving unit is a receiving unit with a particularly short regeneration time, in particular a SPAD-based receiver. In this way, the transmitting path and the receiving path of the lidar sensor can be interleaved with each other in a particularly compact manner. Thus, a particularly compact lidar sensor is achieved. In addition, a particularly compact system is achieved by the arrangement according to the invention of the optical transmitting unit and the optical receiving unit relative to the scanning unit, because the base surface of such a lidar sensor Particularly small. Thus, the optical axes of the optical transmitting unit and the optical receiving unit are not directly directed onto the scanning unit. Therefore, the scanning unit can be arranged beside the optical transmitting unit and the optical receiving unit, and the scanning beam or the reflected scanning beam is deflected onto the scanning unit by the deflection optics.

[0011] By means of the deflection optics, the optical paths of the outgoing scanning beam and the reflected scanning beam are deflected such that if one follows the optical axis of the optical transmitting unit starting from the transmitting unit, the scanning beam is deflected onto the scanning unit in a defined direction. Correspondingly, if the reflected scanning beam is reflected from the scanning unit in a defined direction onto the deflection optics, the reflected scanning beam is deflected onto the optical axis of the optical receiving unit by the deflection optics.

[0012] Thus, a lidar sensor with a particularly large horizontal field of view is achieved. Here, the field of view is the range in the surroundings of the lidar sensor that is sampled by the scanning beam of the lidar sensor. The scanning beam of the lidar sensor passes through the field of view in the horizontal direction because the scanning beam moves in this direction starting from the scanning unit. Thus, the horizontal direction is in particular the direction perpendicular to the axis of rotation of the scanning unit. The optical transmitting unit and the optical receiving unit can be arranged due to the deflection optics such that the optical transmitting unit and the optical receiving unit do not limit the field of view, and thus the horizontal field of view is particularly large. Thus, a particularly large field of view can be achieved, wherein an almost constant operating distance can be achieved with a relatively large vertical field of view.

[0013] To date, lidar sensors with rotating mirrors have not been suitable for designs with a constant operating distance because in the prior art the optical transmitting and receiving areas had to be strictly separated since the receiver (or rather the amplifier electronics) had a long recovery time and the transmit / receive coupling in the sensor led to a large dead zone in the near field of the sensor. With the lidar sensor according to the invention, a large operating distance is ensured, wherein not only a large transmit aperture can be achieved to meet the requirements and limitations of laser class 1, but also a large receive aperture can be achieved to receive as much light as possible from the target. Here, it is avoided that the structural space required for the transmit and receive areas becomes unnecessarily large structurally due to the large vertical field of view, since a large amount of space has been required to date to separate the transmit and receive areas.

[0014] Preferred embodiments show preferred expansions of the invention.

[0015] Preferably, the optical axis of the optical transmitting unit is parallel to the optical axis of the optical receiving unit. This means that the optical transmitting unit and the optical receiving unit are oriented in the same direction, whereby a particularly compact construction of the lidar sensor can be achieved.

[0016] Also advantageous is that the angle of incidence between the optical axis of the optical transmission unit and the optical axis of the first mirror is equal to 45° or less than 45°, and / or the angle of incidence between the optical axis of the optical reception unit and the optical axis of the second mirror is equal to 45° or less than 45°. In particular, when the angle of incidence is less than 45°, the scanning unit can be arranged to overlap to a large extent with the optical transmission unit and / or the optical reception unit. Thereby, the structural space required in the housing of the lidar sensor is reduced. This particularly applies to the case where the angle of incidence between the optical axis of the optical transmission unit and the optical axis of the first mirror is less than 45°, and at the same time the angle of incidence between the optical axis of the optical reception unit and the optical axis of the second mirror is less than 45°, and at the same time the optical axes of the optical transmission unit and the optical reception unit are parallel to each other. Here, the angle of incidence is the angle formed between a vertical line located on one of the mirrors and the optical axis oriented on that mirror.

[0017] Advantageously, the rotation axis of the scanning unit is arranged along the direction of the optical axis of the optical transmission unit, starting from the point where the optical axis in the optical transmission unit hits the first mirror, on the following side of the first mirror on which the optical transmission unit is also located; and / or the rotation axis of the scanning unit is arranged along the direction of the optical axis of the optical reception unit, starting from the point where the optical axis of the optical reception unit hits the second mirror, on the following side of the first mirror on which the optical reception unit is also arranged. In other words, this means that the rotation axis of the scanning unit is arranged such that the scanning beam starting from the optical transmission unit and the reflected scanning beam returning to the optical reception unit are both reflected at an acute angle on the corresponding mirror of the deflection optical device to hit the scanning unit. Depending on the distance between the deflection optical device and the scanning unit, the scanning unit can be moved along the optical axis in the lidar sensor to the side of the optical transmission unit or the optical reception unit. Thereby, the housing shape of the lidar sensor can be optimized to achieve as compact a lidar sensor as possible.

[0018] Furthermore, it is advantageous that the optical axis of the optical transmission unit and / or the optical axis of the optical reception unit is oriented parallel to the rotation plane of the scanning unit. Here, the rotation plane is the plane in which the field of view of the lidar sensor extends. Thus, the rotation plane is a plane perpendicular to the rotation axis of the scanning unit, where the scanning unit is in particular a rotating mirror system or a vibrating mirror system. Here, the optical axes of the optical transmission unit and the optical reception unit are generally arranged in different rotation planes of the scanning unit, and these rotation planes are parallel to each other. The rotation axis of the scanning unit is in particular perpendicular to the optical axis of the scanning unit and / or the optical axis of the reception unit.

[0019] Further preferably, the optical scanning unit is a line laser, wherein the laser line of the line laser is oriented parallel to the rotation axis of the scanning unit. This means that the scanning beam has a linear beam shape, wherein the scanning beam moves in a direction perpendicular to the orientation of the line shape of the scanning beam. Thus, it is possible to sample areas in the surroundings of the lidar sensor, wherein the movement of the scanning beam around the rotation axis of the scanning unit by the scanning unit is sufficient to detect points in multiple planes. Here, the reflection area of the scanning unit can be used jointly by the outgoing scanning beam and the reflected scanning beam. In other words, this means that the mirror of the scanning unit is fully illuminated by the optical transmitting unit, i.e., the linear scanning beam is also emitted onto the area of the scanning unit for steering the reflected scanning beam onto the deflection unit. Therefore, a particularly large mirror surface is used to deflect sufficient light back to the optical receiving unit.

[0020] Equally advantageous is that the optical transmission path and the optical reception path of the lidar sensor intersect each other between the scanning unit and the deflection optics. This means that it is advantageous for the path of the scanning beam to coincide with the path of the reflected scanning beam. In this way, a particularly compact structure of the lidar sensor can be achieved.

[0021] Furthermore, it is advantageous that the optical axis of the optical transmitting unit is offset from the optical axis of the optical receiving unit in the direction of the rotation axis of the scanning unit. In other words, this means that the optical axis of the optical transmitting unit and the optical axis of the optical receiving unit are arranged in different planes, both of which are perpendicular to the rotation axis of the scanning unit. Thus, the optical transmitting unit and the optical receiving unit are arranged in different planes of the lidar sensor. If the rotation axis is regarded as the vertical axis of the lidar sensor, the optical transmitting unit and the optical receiving unit are thus arranged one above the other in an overlapping manner. Thus, the base surface of the lidar sensor can be minimized. Alternatively, the optical transmitting unit and the optical receiving unit are arranged side by side in a common plane of the lidar sensor. In this way, the optical axis of the optical transmitting unit and the optical axis of the optical receiving unit are particularly arranged in a common plane perpendicular to the rotation axis of the scanning unit.

[0022] Furthermore, it is advantageous that the minimum distance between the optical axis of the optical transmitting unit and the axis of rotation of the scanning unit is not equal to the minimum distance between the optical axis of the optical receiving unit and the axis of rotation of the scanning unit. This means that, compared to the optical receiving unit, the optical transmitting unit is preferably arranged further away from or closer to the scanning unit. The optical transmitting unit and the optical receiving unit are preferably arranged one above the other in an overlapping manner. This means that, if the axis of rotation of the scanning unit is regarded as the vertical axis of the lidar sensor, the optical transmitting unit and the optical receiving unit are preferably offset diagonally from each other taking into account their optical axes. In particular when the optical transmitting unit and the optical receiving unit have a cylindrical structure (where the cylindrical shape has the respective optical axis as the cylinder axis), the optical transmitting unit and the optical receiving unit can be arranged particularly close to each other here, thereby minimizing the structural dimensions of the lidar sensor. The optical transmitting unit and the optical receiving unit are preferably arranged directly adjacent to each other.

[0023] It is also advantageous that the lidar sensor has a cleaning unit which is provided for cleaning the viewing window of the lidar sensor, wherein the cleaning unit is arranged behind the deflection optics starting from the optical transmitting unit and the optical receiving unit. Since the scanning beam emitted from the optical transmitting unit does not strike this area (because the scanning beam has been deflected by the deflection optics beforehand), this area of the viewing window does not have to remain free in order to avoid an interruption of the scanning beam. Therefore, this area is particularly suitable for parking the cleaning unit when it is not required. The cleaning unit is in particular a wiper unit, for example in a windshield wiper.

[0024] Furthermore, it is advantageous that the lidar sensor has a housing with a viewing window, wherein the scanning beam is emitted through the viewing window into the surroundings of the lidar sensor, wherein the viewing window has a curved surface, and the axis of rotation of the scanning unit is arranged such that the rotation circumference of the scanning unit extends in the space located within the curved surface of the viewing window. Here, the space within the curved surface of the viewing window is the space generated between the viewing window and the straight line directly connecting two points of the viewing window to each other. Thus, the viewing window bends around the scanning unit, thereby enabling a further reduction of the structural space required in the housing of the lidar sensor.

[0025] It is also advantageous that the operating range of the lidar sensor is variable over its field of view, in particular the operating range of the lidar sensor is smaller in the lateral regions of the field of view than in the central region of the field of view. Here, the lateral regions are in particular the lateral regions in the horizontal direction of the field of view. In this way, it can be achieved that the lidar sensor can be implemented particularly compactly. Description of the Drawings

[0026] Embodiments of the present invention will be described in detail below with reference to the drawings. Shown in the drawings are:

[0027] Figure 1 Schematic diagram showing a lidar sensor according to an embodiment of the present invention

[0028] Figure 2 Schematic diagram showing the optical path of the scanning beam and the optical path of the reflected scanning beam in the lidar sensor according to the present invention

[0029] Figure 3 Schematic diagram showing the lidar sensor in a front view

[0030] Figure 4 Shows a lidar sensor according to another embodiment of the present invention Detailed implementation mode

[0031] Figure 1 Shows a lidar sensor 1 according to an embodiment of the present invention. Here, the lidar sensor 1 is shown in a top view mapping the XY plane. The lidar sensor 1 includes an optical transmission unit 2, an optical reception unit 5, a deflection optical device 8, and a scanning unit 11. The optical transmission unit 2, the optical reception unit 5, the deflection optical device 8, and the scanning unit 11 are arranged on the housing 15 of the lidar sensor. The side surface of the housing 15 has an observation window 14

[0032] The optical transmission unit 2 is configured to transmit a scanning beam 3 in the direction of the optical axis 4 of the optical transmission unit 2. In this embodiment, the optical transmission unit 2 is a line laser, wherein the laser line of the line laser is oriented parallel to the rotation axis 12 of the scanning unit 11 and is emitted as the scanning beam 3. This means that, in Figure 1 the illustration of the lidar sensor 1 shown in, the laser line generated by the optical transmission unit 2 is oriented along the vertical axis of the lidar sensor, and this vertical axis corresponds to the Z axis perpendicular to the drawing plane shown in Figure 1 In the embodiment described herein, the optical axis 4 of the optical transmission unit 2 is located at the center of the laser line emitted by the line laser. Therefore, the optical axis 4 of the optical transmission unit 2 is the main transmission direction of the optical transmission unit 2

[0033] The optical receiving unit 5 is arranged to receive the reflected scanning beam 6. The optical receiving unit 5 is preferably a SPAD-based sensor. Here, after the emitted scanning beam 3 has been reflected in the surroundings of the lidar sensor and has been projected back to the lidar sensor, the reflected scanning beam 6 is the reflected part of the emitted scanning beam. The optical receiving unit has a main receiving direction, which is oriented along the optical axis of the optical receiving unit. The optical receiving unit 5 is an optical sensor that converts the received optical signal (here the reflected scanning beam 6) into an electrical signal. The optical receiving unit 5 is, for example, a photoelectric sensor. The optical axis 7 of the optical receiving unit 5 corresponds to the main receiving direction of the optical receiving unit 5 in terms of its position. In this embodiment, a lens is arranged on the front side of the optical receiving unit. The lens is, for example, a convex lens or a concave lens. The optical axis 7 of the optical receiving unit 5 corresponds to the optical axis of the lens arranged at the input of the optical receiving unit 5.

[0034] It should be noted that the optical axis 4 of the optical transmitting unit 2 and the optical axis 7 of the optical receiving unit 5 are both virtual axes and are not structural elements of the lidar sensor 1. The optical transmitting unit 2 and the optical receiving unit 5 are arranged such that the optical axis 4 of the optical transmitting unit 2 is parallel to the optical axis 7 of the optical receiving unit 5. Here, the optical transmitting unit 2 and the optical receiving unit 5 are arranged directly adjacent to each other. Here, in Figure 1 the illustrated figure shown, the optical axes 4, 7 are offset from each other in both the X direction and the Z direction.

[0035] The deflection optical device 8 has a first mirror surface 9 and a second mirror surface 10. Here, the first mirror surface 9 is the surface of the first mirror, and the second mirror surface 10 is the surface of the second mirror. This means that in this embodiment, the deflection optical device 8 has two separate mirrors, which have separate mirror surfaces 9, 10. In other embodiments, the lidar sensor 1 can be configured such that the first mirror surface 9 and the second mirror surface 10 are arranged on a common mirror.

[0036] The optical axis 4 of the optical transmitting unit 2 is directed onto the first mirror 9, and the optical axis 7 of the optical receiving unit 5 is directed onto the second mirror 10. This means that the optical transmitting path and the optical receiving path of the lidar sensor are deflected by the deflection optical device 8. Thus, the scanning beam 3 emitted by the optical transmitting unit 2 is reflected at the first mirror 9 and projected onto the scanning unit 11. In a corresponding manner, the received reflected scanning beam 6 from the scanning unit 11 is reflected at the second mirror 10 and projected onto the optical receiving unit 5. The optical transmitting unit 2 together with the optical receiving unit 5 is arranged on a common first side of the deflection optical device 8 in the optical path of the lidar sensor 1. Here, the optical path is the combination of the optical transmitting path and the optical receiving path. Since the optical transmitting unit 2 together with the optical receiving unit 5 is arranged on a common first side of the deflection optical device 8 in the optical path of the lidar sensor 1, the optical transmitting unit and the optical receiving unit look at the deflection optical device 8 from a common direction. This means that the optical axes 4, 7 of the optical transmitting unit 2 and the optical receiving unit 5 start from the respective optical units 2, 5 and then strike the deflection optical device 8 from a common direction. Here, in particular when the optical path of the scanning beam 3 and the optical path of the reflected scanning beam extend side by side between the deflection optical device 8 and the optical transmitting unit 2 or the optical receiving unit 5, i.e., both optical paths intersect a plane (the plane is either perpendicular to the optical axis 4 of the optical transmitting unit 2 or perpendicular to the optical axis 7 of the optical receiving unit 7), the common direction can be regarded as a common direction.

[0037] The scanning unit 11 is arranged in the optical path of the lidar sensor 1 and is here arranged on the second side of the deflection optical device 8. Thus, the optical path of the lidar sensor 1 starts at the optical transmitting unit 2 and the optical receiving unit 5, extends through the deflection optical device 8 to the scanning unit 11, and from there through the observation window 14 into the surroundings of the lidar sensor 1. In this embodiment, the scanning unit 11 is a rotating mirror system that includes two separate rotating mirrors, here the first rotating mirror 11a and the second rotating mirror 11b. The rotating mirrors 11a, 11b of the scanning unit 11 rotate about the rotation axis 12. Here, the rotating mirrors 11a, 11b are oriented parallel to the rotation axis 12. By rotating the rotating mirror system of the scanning unit 11, the scanning beam 3 is emitted in different directions, for example in the angular range from -60° to +60°, in order to detect a field of view of 120°. Depending on the position of the rotating mirrors 11a, 11b of the rotating mirror system of the scanning unit 11, the reflected scanning beam 6 is received from the same area (into which the scanning beam 3 is sent), so that the scanning beam 3 scatters at the object.

[0038] The first mirror and thus the first mirror surface 9 is arranged in front of the optical transmitting unit 2 such that an incident angle α of less than 45° is obtained between the optical axis 4 of the optical transmitting unit 2 and the first mirror surface 9. In an alternative embodiment, the incident angle α is equal to 45°. In a corresponding manner, the second mirror and the second mirror surface 10 are arranged in front of the optical receiving unit 5 such that an incident angle β of less than 45° is obtained between the optical axis 7 of the optical receiving unit 5 and the second mirror surface 10. In an alternative embodiment, the incident angle β is equal to 45°. Thus, from Figure 1 it can be seen that the scanning beam 3 and the reflected scanning beam 6 are deflected by the deflecting optical device 8 by an angle of less than 90°. This enables the scanning unit 11 to move in the direction of the optical axes 4, 7 in the direction of the optical transmitting unit 2 and / or the optical receiving unit 5. Thus, the mirror 14 can be moved closer (heranrücken) to the optical transmitting unit 2 and the optical receiving unit 5, thereby realizing a particularly compact lidar sensor 1. In other words, this means that the rotation axis 12 of the scanning unit is arranged along the optical axis 4 of the optical transmitting unit 2, starting from the point where the optical axis 4 of the optical transmitting unit 2 hits the first mirror surface 9, on the following side of the first mirror surface 9: The optical transmitting unit 2 is also located on this side. This also means that the rotation axis 12 of the scanning unit 11 is arranged along the optical axis 7 of the optical receiving unit 5, starting from the point where the optical axis 7 of the optical receiving unit 5 hits the second mirror surface 10, on the following side of the first mirror surface 10: The optical receiving unit is also arranged on this side.

[0039] The optical axis 4 of the optical transmitting unit 2 and the optical axis 7 of the optical receiving unit 5 are oriented parallel to the rotation plane of the scanning unit 11. The rotation plane of the scanning unit 11 is perpendicular to the rotation axis 12 of the scanning unit 11 and corresponds to a plane parallel to the XY plane in Figure 1 . The scanning unit 11 and the optical transmitting unit 2 are arranged in the same plane along the vertical axis and thus along the rotation axis 12 of the lidar sensor 1 in the lidar sensor 1. The scanning unit 11 and the optical receiving unit 5 are arranged in the same plane along the vertical axis and thus along the rotation axis 12 of the lidar sensor 1 in the lidar sensor 1. Here, the optical transmitting unit 2 is located above the optical receiving unit 5 along the rotation axis 12, and the scanning unit 11 is located next to the optical scanning unit 2 and the optical receiving unit 5.

[0040] The optical transmission path and the optical reception path of the lidar sensor 1 are at least staggered from each other between the scanning unit 11 and the deflecting optical device 8. This means that the emitted scanning beam 3 and the received scanning beam 6 pass through a common spatial region of the lidar sensor 1 between the scanning unit 11 and the deflecting optical device 8. For this, reference is made to Figure 2 .

[0041] Figure 2 is a schematic diagram of the optical path of the lidar sensor 1. The optical path of the lidar sensor 1 is clarified herein, from which it can be seen that the optical transmission path and the optical reception path of the lidar sensor 1 are interleaved with each other. It can be seen that the scanning beam 3 is projected from the optical transmission unit 2 onto the first mirror 9 and from there onto the scanning unit 11, in particular onto one of the rotating mirrors 11a, 11b of the scanning unit 11. The scanning beam 3 is emitted from the scanning unit 11 into the surroundings of the lidar sensor 1 through the observation window 14.

[0042] It can also be seen that the reflected scanning beam 6 is projected from the scanning unit 11 onto the second mirror 10 and from there onto the optical reception unit 5. Here, it can be seen that the scanning beam 3 and the reflected scanning beam 6 use the same area of the mirrors of the rotating mirror system of the scanning unit 11. Between the deflection optical device 8 and the scanning unit 11, the scanning beam 3 and the reflected scanning beam 6 pass through the same area within the lidar sensor 1. Therefore, the optical transmission path (i.e., the area through which the scanning beam 3 passes) and the optical reception path (i.e., the area through which the reflected scanning beam 6 passes) are interleaved with each other.

[0043] It should be noted that both the optical transmission path (i.e., the path followed by the scanning beam 3) and the optical reception path (i.e., the path followed by the reflected scanning beam 6) can include other optical elements, especially lenses. Therefore, in Figure 1 , for example, the first lens 17 and the second lens 18 are arranged in the optical transmission path. Here, the first lens 17 is arranged between the deflection optical device 8 and the optical transmission unit 2, while the second lens 18 is arranged between the deflection optical device 8 and the scanning unit 11. It should be noted that in other embodiments, for example, only the second lens 18 is arranged in the lidar sensor 1, as shown in Figure 2 . The optical transmission unit 2 and the optical reception unit 5 can also include other lenses, as shown in Figure 2 , in Figure 2 , the optical reception unit 5 includes a condenser lens or a receiving objective lens 19. Here, one or more lenses can be arranged in front of or behind the deflection optical device 8 in the optical path of the lidar sensor 1 and thus either in the optical transmission path or in the optical reception path.

[0044] Figure 2Shows the interleaving of the transmission area and the reception area. There is a reception hole in the plane of the second lens 18 and in the second mirror (also called the reception steering mirror) located below it. From this plane up to the front window glass, the area with the maximum vertical incidence angle remains idle. Due to the interleaving, only the area from the lower edge of the optical reception unit 5 to the upper edge of the optical transmission unit 2 is significantly relevant. In a system with paths to be separated, the transmitter must be moved upwards further so that the lower edge of the transmitter on the front window glass is above the upper edge of the receiver on the front window glass.

[0045] In Figure 3 it is shown in detail again the arrangement of the optical transmission unit 2 relative to the optical reception unit 5. Here, Figure 3 a second view shows from Figure 1 the known lidar sensor 1, where the XZ plane is mapped. The optical axis 4 of the optical transmission unit 2 is offset relative to the optical axis 7 of the optical reception unit 5 in the direction of the rotation axis 12 of the scanning unit 11. Thus, in Figure 3 the optical transmission unit 2 is arranged above the optical reception unit 5, where both the optical transmission unit 2 and the optical reception unit 5 are arranged beside the scanning unit 11.

[0046] At the same time, the minimum distance between the optical axis 4 of the optical transmission unit 2 and the rotation axis 12 of the scanning unit 11 is not equal to the minimum distance between the optical axis 7 of the optical reception unit 5 and the rotation axis 12 of the scanning unit 11. In other words, this means that the optical transmission unit 2 is farther from the scanning unit 11 than the optical reception unit 5. Therefore, the optical transmission unit 2 and the optical reception unit 5 are arranged offset from each other in the XZ plane of the lidar sensor 1. In this way, the structural space in the housing 15 of the lidar sensor 1 can be optimally utilized, because especially when the optical transmission unit and the optical reception unit 5 have a cylindrical shape or at least a substantially cylindrical shape, the total structural height required is less than the combined height of the optical transmission unit 2 plus the height of the optical reception unit 5.

[0047] Therefore, Figure 3 a front view of the lidar sensor 1 is shown. By using a steering mirror (i.e., the second mirror) on the reception side, the lens system can be placed very close to the reception hole without disturbing the relatively large reception objective 19. The laser can be arranged laterally above the reception objective 19, enabling the optimization of both the structural width and the structural height.

[0048] The lidar sensor 1 optionally has a cleaning unit 13 which is arranged for cleaning the observation window 14 of the lidar sensor 1, wherein the cleaning unit 13 is arranged behind the deflection optics 8 on the basis of the optical transmission unit 2 and the optical reception unit 5. Since the emitted scanning beam 3 is deflected by the deflection optics 8, a dead zone appears behind the deflection unit 8 from the perspective of the optical transmission unit 2, and the scanning beam 3 does not pass through this dead zone during the scanning process. Therefore, it is advantageous that: in this area, the cleaning unit 13, in particular the wiper unit, has a parking position, and when the cleaning unit is not required, the cleaning unit can be placed in this parking position.

[0049] Optionally, the operating range of the lidar sensor 1 is variable over its field of view. Here, the operating range of the lidar sensor 1 is smaller in the lateral regions of the field of view than in the central region of the field of view. The lateral regions are in particular the lateral regions in the horizontal direction of the field of view.

[0050] Figure 4 A lidar sensor 1 according to another embodiment of the present invention is shown. The said another embodiment of the present invention basically corresponds to the previously described embodiment of the present invention. Here, as also in the previous embodiment, the lidar sensor 1 has a housing 15 with an observation window 14. The scanning beam 3 is emitted through the observation window 14 into the surroundings of the lidar sensor 1. However, here, the observation window 14 is shaped such that it has a curved surface which is curved in the direction of the rotation axis 12 of the scanning unit 11. Here, the rotation axis 12 is not necessarily the center of the curved surface. The scanning unit 11 and the observation window 14 are arranged relative to each other such that the rotation circumference 16 of the scanning unit 11 extends in the space located within the curved surface of the observation window 14. Thus, it can be seen that the line connecting the outer ends of the observation window 14 intersects the rotation circumference 16 of the scanning unit 11.

[0051] The lidar sensor 1 according to the present invention utilizes the short recovery time of the SPAD-based integrated receiver so as to stagger the transmission path and the reception path. Thereby, space is significantly saved. Additionally, the holes are made rectangular and have a small width. The transmission holes and the reception holes have the same width.

[0052] In order to optimize the width of the mirrors of the scanning unit 11, the main optical axis is rotated by an angle relative to the Y-axis of the lidar sensor 1. The widths of the rotating mirrors 11a, 11b are the hole width / sin (angle of incidence). The angle of incidence is defined by the maximum horizontal scanning angle and the rotation of the main axis.

[0053] For the rotation of the main axis and to minimize the width of the lidar sensor 1, the optical axes 4, 7 of the transmitting and receiving units 2, 5 are designed in the X-axis direction. They are redirected to the optical main axis by means of one fixed steering mirror each from the optical transmitting / receiving units 2, 5.

[0054] To optimize the height of the transmitting aperture, the last (scattering) lens and the steering mirror of the receiver (i.e., the second mirror) are in line. Optionally, a common steering mirror can also be used for the transmitter and the receiver. However, this would result in a relatively large spacing between the transmitting area and the receiving area. Therefore, the optical transmitting unit 2 is placed slightly laterally to the central axis of the optical receiving unit 5.

[0055] To interfere as little as possible with the beam path in the direction of the front window glass and thus also in the direction of the observation window 14, the angle sensor for the mirror of the scanning unit 11 is placed very close to the housing wall. To optimize the height of the lidar sensor 1, a slightly reduced operating range in the corners (large horizontal and vertical opening angles) can be accepted.

[0056] The arrangement of the transmitting and receiving steering mirrors (i.e., the first and second mirrors of the deflection optics 8) results in an area of the front window glass that is not within the field of view of the lidar sensor 1. The wiper can be parked in this area, and an optional heating device for the window glass can also be switched on in this area.

[0057] The lidar sensor from the previously described embodiment has, for example, the following characteristics:

[0058] Horizontal visible range: 120°

[0059] Vertical visible range 21°

[0060] Horizontal divergence <+-0.1°

[0061] Aperture width 16 mm

[0062] Rotation of the optical main axis: 6°

[0063] Aperture height (transmitter) 34 mm

[0064] Aperture height (receiver) 28 mm

[0065] Spacing between the upper edge of the receiving aperture and the lower edge of the transmitting aperture 2 mm

[0066] Front window glass height (optically transparent area) 94 mm

[0067] In addition to the above written disclosure, reference is also explicitly made to Figures 1 to 4 the disclosure of.

Claims

1. A lidar sensor (1), the lidar sensor comprising: An optical transmitting unit (2), which is arranged to emit a scanning beam (3) in a direction along an optical axis (4) of the optical transmitting unit (2). An optical receiving unit (5), which is arranged to receive a reflected scanning beam (6) after the scanning beam (3) has been reflected in the surroundings of the lidar sensor (1), wherein the optical receiving unit (5) has a main receiving direction oriented along an optical axis (7) of the optical receiving unit (5). A deflecting optical device (8), which includes a first mirror (9) and a second mirror (10), wherein the optical axis (4) of the optical transmitting unit (2) is oriented onto the first mirror (9), and the optical axis (7) of the optical receiving unit (5) is oriented onto the second mirror (10), wherein the optical transmitting unit (2) together with the optical receiving unit (5) is arranged on a common first side of the deflecting optical device (8) in an optical path of the lidar sensor (1). A scanning unit (11), which is arranged on a second side of the deflecting optical device (8) in the optical path of the lidar sensor (1), and which is arranged to deflect the scanning beam (3) reflected by the deflecting optical device (8) into different directions in order to sample the surroundings of the lidar sensor (1) by means of the scanning beam (3), and to deflect the reflected scanning beam (6) back onto the deflecting optical device (8). Wherein the scanning unit includes a first rotating mirror and a second rotating mirror, each rotating mirror rotating about a rotation axis, wherein the first rotating mirror and the second rotating mirror are oriented parallel to the rotation axis, and wherein a width of the rotating mirror is a hole width / sin(angle of incidence), wherein the angle of incidence is defined by a maximum horizontal scanning angle and a rotation of the rotation axis.

2. The lidar sensor (1) according to claim 1, characterized in that, The optical axis (4) of the optical transmitting unit (2) is parallel to the optical axis (7) of the optical receiving unit (5).

3. The lidar sensor (1) according to any one of the above claims, characterized in that, An angle of incidence (α) between the optical axis (4) of the optical transmitting unit (2) and an optical axis of the first mirror (9) is equal to 45 degrees or less than 45 degrees, and / or an angle of incidence (β) between the optical axis (7) of the optical receiving unit (5) and an optical axis of the second mirror (10) is equal to 45 degrees or less than 45 degrees.

4. The lidar sensor (1) according to any one of the above claims, characterized in that, The optical axis (4) of the optical transmitting unit (2) and / or the optical axis (7) of the optical receiving unit (5) is oriented parallel to a rotation plane of the scanning unit (11).

5. The lidar sensor (1) according to any one of the above claims, characterized in that, The optical transmitting unit (2) is a line laser, wherein a laser line of the line laser is oriented parallel to a rotation axis (12) of the scanning unit (11).

6. The lidar sensor (1) according to any one of the above claims, characterized in that, A transmission path and a reception path of the lidar sensor (1) are interleaved with each other between the scanning unit (11) and the deflecting optical device (8).

7. The lidar sensor (1) according to any one of the above claims, characterized in that, The optical axis (4) of the optical transmitting unit (2) is offset relative to the optical axis (7) of the optical receiving unit (5) in the direction of the axis of rotation (12) of the scanning unit (11).

8. The lidar sensor (1) according to any one of the above claims, characterized in that, The minimum distance between the optical axis (4) of the optical transmitting unit (2) and the axis of rotation (12) of the scanning unit (11) is not equal to the minimum distance between the optical axis (7) of the optical receiving unit (5) and the axis of rotation (12) of the scanning unit (11).

9. The lidar sensor (1) according to any one of the above claims, characterized in that, The lidar sensor (1) has a cleaning unit (13) which is arranged to clean the viewing window (14) of the lidar sensor (1), wherein the cleaning unit (13) is arranged behind the deflection optics (8) on the basis of the optical transmitting unit (2) and the optical receiving unit (5).

10. The lidar sensor (1) according to any one of the above claims, characterized in that, The lidar sensor (1) has a housing (15) which has a viewing window (14), wherein the scanning beam is emitted through the viewing window into the surroundings of the lidar sensor (1), wherein the viewing window (14) has a curved surface, and the axis of rotation (12) of the scanning unit (11) is arranged such that the rotation circumference (16) of the scanning unit (11) extends in a space located within the curved surface of the viewing window (14).

11. The lidar sensor (1) according to any one of the above claims, characterized in that, The operating range of the lidar sensor (1) is variable over the field of view of the lidar sensor, in particular, the operating range of the lidar sensor (1) is smaller in the lateral regions of the field of view than in the central region of the field of view.

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