EP4702381A1 - Optical arrangement, lidar system comprising the optical arrangement and method for operating the lidar system - Google Patents

Abstract

The application relates to an optical arrangement (3) comprising a mounting sup- port (4) and a first and a second light deflecting surface (SF1, SF2). The mounting support (4) is pivotably mounted for the first and second light deflecting surfaces (SF1, SF2) to perform a pivoting movement, wherein the first light deflecting surface (SF1) is arranged such that a light beam (LB) which is incident from a first direction (D1) is deflectable by the first light deflecting surface (SF1) in the direction of a target area (6) during the pivoting movement. The second light deflecting surface (SF2) is arranged such that the light beam (LB) being reflected from the target area (6) is deflectable by the second light deflecting surface (SF2) in a second direction (D2) during the pivoting movement. The application further relates to a use of the optical arrangement (3), a lidar system (5) comprising the optical arrangement (3) and a method for operating a lidar system (5).

Description

OPTICAL ARRANGEMENT, LIDAR SYSTEM COMPRISING THE OPTICAL ARRANGEMENT AND METHOD FOR OPERATING THE LIDAR SYSTEM

Field

The present disclosure relates to the field of optical light deflecting arrangements for lidar systems and to lidar systems in particular for vehicles.

Background

Modern vehicles (cars, vans, trucks, motorcycles, etc.) may comprise a large number of sensor systems whose data are used for driver information and/or are made available to driver assistance systems. The sensor systems may detect the vehicle's environment and other road users within their target area, also called detection area. Based on the data collected, a model of the vehicle's environment may be generated, and the system may react to changes in this vehicle environment. The sensor systems may also detect the distance to objects in the vehicle's environment and relative speed of the objects to the vehicle.

An important sensor principle for the detection of the environment of e. g. vehicles is the lidar technology (lidar: Light Detection and Ranging). A lidar system comprises an optical transmission device and an optical reception device. The transmission device can emit a light beam as an optical transmit signal. In a lidar system, the light used can be laser light in the ultraviolet, visual or infrared range. The optical reception device can receive the emitted light beam as an optical reception signal after reflection from an object in the target area of the lidar system. The object may for example be part of the environment of the vehicle and/or another road user.

Using the emitted light beam, the received light beam can be evaluated by the control unit of the lidar system according to e. g. a time-of-flight method and the spatial position and distance of the objects in the target area on which the reflection occurred can be determined. In addition, it is possible to determine a relative velocity and/or other properties. Reflection or reflected light is understood to mean any light that is reflected back and should also include, in particular, light that is reflected back by scattering or absorption emission.

Lidar systems may comprise an optical light deflecting arrangement, which is configured to direct or steer the emitted and/or received light beams. The light deflection may for example be effected using one or more mirrors. In scanning lidar systems the optical light deflecting arrangement may serve to direct the light beam sequentially over the entire field of view of the target area.

In US2021255323A1 a lidar system is described in which a mirror element is arranged between an optical transmission device and an optical reception device. The mirror element is pivotably mounted about a pivoting axis. The pivoting axis intersects the mirror surfaces of the mirror element, at which the transmitted and received light beams are deflected.

In DE102019134192A1 a lidar system is described which comprises a mirror element with hexagonal base surfaces and six side surfaces formed as mirror surfaces. The mirror element has a central pivotal axis parallel to the side surfaces. The mirror surfaces realize two different target areas by means of two different transmission and reception devices assigned to each other.

Summary

An optical arrangement comprises a mounting support and a first and a second light deflecting surface. The mounting support is pivotably mounted allowing the first and second light deflecting surfaces to perform a pivoting movement. The first light deflecting surface is arranged such that a light beam which is incident from a first direction is deflectable by the first light deflecting surface in the direction of a target area during the pivoting movement. The second light deflecting surface is arranged such that the light beam being reflected from the target area is deflectable by the second light deflecting surface in a second direction during the pivoting movement.

The light deflecting surfaces may in particular be mirror surfaces. The optical arrangement may in particular be suitable to be used in a lidar system.

The pivoting movement of the light deflecting surfaces allows steering the light beam of the lidar System such that a scanning lidar system may be realized. Such lidar systems may operate at long range. Such long-range lidar systems may for example be able to operate with a detection distance of from about 10 m to up to 200 m to 2000 m. The pivoting optical arrangement enables the use of large lens arrangements such that enough light back- reflected from a distant object of the target area can be captured. The described optical arrangement has the further advantage that the optical arrangement can be placed in between an optical transmission device and an optical reception device. The optical transmission device and the optical reception device may for example be comprised in a lidar system. The optical transmission device and the optical reception device may be placed opposite each other on opposing sides of the optical arrangement. This has the further advantage that the packaging size, in particular the packaging height, of the lidar system can be reduced because the transmission device and the reception device can be placed in one line.

The target area of the lidar system is the area range in which objects can be detected by the lidar system. The target area is located in the surrounding area of the lidar system. In the case of a lidar system installed in a vehicle, the target area is located in the surrounding area of the vehicle and can be used, for example, to monitor a close-range or long-range area in the front, rear or blind spot area of the vehicle. A far range lidar system can be designed, for example, for monitoring a far field at distances of, in particular, between about 10 m and about 200 m to up to 2000 m. A close range can be designed, for example, for monitoring a near field at distances of up to about 10 m. In this way, the lidar system can be adapted for use in conjunction with a vehicle to monitor the road for objects.

The optical arrangement is a spatial arrangement of light deflecting surfaces, in particular mirrors. The light deflecting surfaces are held by and are mounted on the mounting support. The optical arrangement therefore comprises a mounting support with light deflecting surfaces arranged on it. The light deflecting surfaces have the property that they can reflect and deflect optical beams. This effect can be achieved in particular by coating surfaces with an optical reflecting material.

In an embodiment of the optical arrangement, the pivoting movement is limited to a swivelling movement such that the deflection direction of the first light deflecting surface is different from the second direction and the incident direction of the second deflecting surface is different from the first direction. In an embodiment of the optical arrangement, the first light deflecting surface is associated with light incident from the first direction and the second light deflecting surface is associated with light deflected in the second direction.

In an embodiment of the optical arrangement, the pivoting movement is common to the first and second light deflecting surface. In this embodiment, the light deflecting surfaces may be fixedly mounted on the mounting support and may perform the same pivoting movement as the mounting support. The pivoting movement of the light deflecting surfaces may then have the same pivoting axis. The pivoting axis of the first and second surface may in particular be the same as the pivoting axis of the mounting support.

In an embodiment of the optical arrangement, the angle between the first light deflecting surface and the first direction changes with the pivoting movement. The pivoting axis of the first light deflecting surface may in particular be transverse to the first direction.

In an embodiment of the optical arrangement, the angle between the second light deflecting surface and the second direction changes with the pivoting movement. The pivoting axis of the second light deflecting surface may in particular be transverse to the second direction.

In an embodiment of the optical arrangement, the pivoting axis is parallel to the first light deflecting surface and to the second light deflecting surface. The pivoting axis does not transverse the light deflecting surfaces, but the light deflecting surfaces rotate around the pivoting axis. This embodiment has the advantage that the light beam being deflected by the first light deflecting surface can perform a scanning movement, thereby scanning a region, e. g. the target area.

The deflection of the beam into the target area and the deflection of the reflected light beam out of the target area can be controlled by a suitable arrangement of the light deflecting surfaces on the mounting structure. In particular, a scanning of the target area by the emitted light beam can be realized by the pivotal movement of the optical arrangement. When scanning the target area, the transmitted light beam is directed by deflection on the first mirror surface stepwise at intervals to different points or areas of the target area such that the entire target area can be scanned thereby. In the same way, the deflection of the light beam reflected from the target area and the subsequent reception of the receiving light beam by the receiving device can be realized by the pivotal movement. In an embodiment of the optical arrangement, the first light deflecting surface and/or the second light deflecting surface comprises a planar surface. Planar light deflecting surfaces may simplify evaluation of the transmitted light beam and the received light beam, for example.

In an embodiment of the optical arrangement, the first light deflecting surface and the second light deflecting surface are adjacent to each other. This may further simplify the evaluation of the light beams for e. g. object detection.

The first light deflecting surface and the second light deflecting surface may be arranged in an angle with respect to each other, the size of the angle being between around 60° and around 120°, preferably around 90°. This may further simplify the evaluation of the light beams. The angle between the light deflecting surfaces may in particular be 90°. This angle does not need to be exactly 90°. The first direction may be aligned with the second direction, but does not need to be aligned with it. This relaxes the requirements on the mechanical preciseness of the optical arrangement and may reduce assembling cost.

In an embodiment the optical arrangement may comprise a drive device with which the pivoting movement can be driven.

In embodiments of the optical arrangement, the first and second light deflecting surface are of different size. Since the first surface is assigned to deflect light from the first direction and the second mirror is assigned to deflect light to the second direction, each surface has a fixedly assigned function. The size of the surfaces therefore does not need to be equal, but may be adapted to the assigned purpose. This may reduce the total weight of the optical arrangement and the required torque of the drive device of the optical arrangement may be reduced.

In some embodiments, the second light deflecting surface is larger than the first light deflecting surface. The extension of the second light deflecting surface in a circumferential direction of the pivotal movement may larger than the extension of the first light deflecting surface in this direction. In embodiments where the first direction corresponds to the sending direction of the transmitted light beam, the first light deflecting surface is assigned to the transmission device. Normally, the transmission device needs a smaller size of deflecting surface than the reception device. Thus, the first surface may be designed to be smaller than the second surface, which may be arranged to collect the reflected light from the target area. In embodiments of the optical arrangement, the first direction and the second direction are longitudinal to each other. The first direction and the second direction may in particular be the same direction. This means that the transmission device and reception device are aligned against each other in such a way that the respective transmitted and received light beams are parallel to each other. In other embodiments, the transmission device and the reception device may be inclined with respect to each other.

The optical arrangement described above may be used in a lidar system. The lidar system in particular a scanning lidar system, wherein the optical arrangement is arranged such that the light beam is directed to scan a target area of the lidar system.

The lidar system comprises an optical transmission device configured to transmit a light beam in a first direction, an optical reception device configured to receive the light beam from a second direction and the optical arrangement as described before.

In embodiments of the lidar system, the first light deflecting surface is assigned to deflect the light beam transmitted by the transmission device and the second light deflecting surface is assigned to deflect the light beam to be received by the reception device. This embodiment has the additional advantage that a multi-shot setup can be applied, which may further increase the true positive detection rate of the lidar system. In a multi-shot lidar system, the emitted light beam comprises a sequence of pulses, the so-called "shots".

In embodiments of the lidar system, the transmission device and the reception device are arranged on opposing sides of the optical arrangement. This allows for a further reduction of the packaging space of the lidar system.

In embodiments of the lidar system, the transmission device and the reception device are configured to inter-operate to monitor the target area using the light beam transmitted by the transmission device.

In embodiments of the lidar system, the target area is scannable by the light beam deflected by the first light deflecting surface.

The lidar system may comprise a control unit configured to control the transmission of the light beam by the transmission device, the reception of the light beam by the reception device, the pivotal movement of the optical arrangement, the control unit being further configured to evaluate the transmitted and received light beam. The evaluation of the received light beam using the associated transmitted light beam can for example be performed via a time-of-flight measurement. It may comprise an object recognition. The evaluation can then take into account the position of the light deflecting surface by which the respective transmitted light beam was deflected and the position of the light deflecting surface by which the received light beam was deflected.

In an embodiment the lidar system comprises an optical transmission device, an optical reception device and an optical arrangement comprising a mounting support and a first and a second light deflecting surface, wherein the mounting support is pivotably mounted for the first and second light deflecting surfaces to perform a pivoting movement.

A method for operating such a lidar system comprises:

• The transmission device transmitting a light beam in a first direction.

• The first light deflecting surface deflecting the light beam in the direction of a target area.

• The second light deflecting surface deflecting the light beam reflected from the target area in the second direction.

• The reception device receiving the light beam.

The pivotal movement of the optical arrangement causes the light beam deflected by the first light deflecting surface to perform a scan of the target area. The pivotal movement is performed such that the incident direction of the second light deflecting surface is different from the first direction during the pivotal movement.

Brief description of the figures

Embodiments will now be described with reference to the attached drawing figures by way of example only. Like reference numerals are used to refer to like elements throughout. The illustrated structures and devices are not necessarily drawn to scale.

Fig. 1 schematically illustrates a lidar system with an optical arrangement.

Fig. 2 schematically illustrates a vehicle with the lidar system. Detailed Description

Figure 1 schematically illustrates a lidar system 5 with an optical transmission device 1, an optical reception device 2 and an optical arrangement 3. The optical arrangement 3 is arranged between the transmission device 1 and the reception device 2. The optical arrangement 3 comprises a mounting support 4, a first light deflecting surface SF1 and a second light deflecting surface SF2. The light deflecting surfaces SF1, SF2 are for example mirror surfaces. The light deflecting surfaces SF1, SF2 are fixedly mounted to the mounting support 4. The optical arrangement 3 essentially has the shape of a folded plane, where the light deflecting portions project outwards. The angle between the first plane SF1 and the second plane SF2 is around 90°. The optical arrangement 3 is pivotably mounted about a pivoting axis A.

The optical arrangement 3 shown in figure 1 can swivel about its pivoting axis A, i.e. can perform a pivotal back and forth movement about its pivoting axis A. The pivoting direction is reversed at respective reversal points, which at the same time correspond to the maximum amplitude of the swivelling movement. A possible swivelling movement is indicated by an arrow in Figure 1.

The pivoting axis A is arranged in between the first light deflecting surface SF1 and the second light deflecting surface SF2. The pivoting axis A is parallel to at least one and preferably both of the two light deflecting surfaces SF1, SF2. This allows for the angle between the first direction DI and the first surface SF1 to change with the swivelling movement. The swivelling movement thus creates the scanning movement of the light beam LB in the target area 6. The described placement of the pivoting axis also allows for the angle between the second direction D2 and the second surface SF2 to change with the swivelling movement. The swivelling movement thus enables the reception of the scanning light beam LB reflected from the target area 6. The pivoting axis A may be arranged at a central position between the light deflecting surfaces SF1, SF2.

The transmission device 1 is configured and arranged in such a way that it transmits a light beam LB in a first direction DI. The transmitted light beam LB is then deflected by the first mirror surface SF1 in the direction of a target area 6 of the lidar system 5. The light beam LB is then reflected back from the target area 6 by for example an object 0. The light beam LB reflected from the target area 6 is deflected by the second surface SF2 in a second direction D2, the direction of the reception device 2. The reflected light beam LB which has been deflected in the second direction D2 by the second light deflecting surface SF2 is then received by the reception device 2.

The transmission device 1 transmits the transmitted light beam LB in the first direction DI. The reception device 2 receives the received light beam LB from the second direction D2. In the example shown in figure 1, the transmission device 1 and the reception device 2 are arranged relative to each other such that that they are in one optical axis and that the first direction DI and the second direction D2 are the same direction.

Preferably, the transmission device 1 comprises a laser for transmitting the transmitted light beam LB. The transmission device 1 may also comprise a plurality of lasers arranged, for example, in the form of an array, and then transmit a plurality of transmitted light beams LB. Preferably, the optical reception device 2 comprises an opto-electronic detector, for example a point sensor, line sensor or area sensor, in particular an avalanche photodiode, a photodiode cell, a CCD sensor, an active pixel sensor, for example a CMOS sensor or the like. With the opto-electronic detector, optical signals, in particular laser signals, can be received and converted into electrical signals. The electrical signals can be further processed, for example, by a control unit 7 of the lidar system 5.

Optionally, the optical transmission device 1 and/or the optical reception device 2 can have at least one optical component for changing a beam characteristic of the transmitted and/or received light beam LB. The optical component, for example an optical lens or an optical lens array, can be used to change the beam characteristic of optical signals. For example, optical signals can be dispersed or concentrated by an optical lens. In the optical transmission device 1, the transmitted light beam LB may be dispersed, i.e. expanded, by the optical component, for example the lens, in at least one direction. By means of such an expanded light beam LB, a larger area of the target area 6 can then be targeted by the light beam LB. At the optical reception device 2, the reflected beam LB incident from the target area 6 may be captured by the optical component, for example the lens, and focused on the corresponding opto-electronic detector.

For example, the transmission device 1 may comprise a diverging lens which scatters, i.e. expands, the transmitted light beam LB in at least one direction perpendicular to the first direction DI. Similarly, the received light beam LB may have a certain width in a direction perpendicular to the second direction D2. The received light beam LB can be bundled over this width, for example by a converging lens, and focused onto the opto-electronic detector.

The optical arrangement 3 is arranged and configured such that its swivelling movement enables the first light deflecting surface SF1 to deflect the light beam LB incident from the first direction DI towards the target area 6. The optical arrangement 3 is also arranged and configured such that its swivelling movement enables the second light deflecting surface SF2 to deflect the light beam LB incident from the target area 6 toward the second direction D2 to be received by the reception device 2. The first light deflecting surface SF1 is thus assigned to deflect the light beam LB emitted by the transmission device 1. The second light deflecting surface SF2 is thus assigned to deflect the light beam LB towards the reception device 2.

This assignment of surfaces SF1, SF2 to directions DI, D2 remains during the whole of the swivelling movement of the optical arrangement 3. This dedication of the surfaces SF1, SF2 to a certain type and purpose of light beam LB allows to configure the surfaces SF1, SF2 to be more adapted to their dedicated purpose. As for the reception device 2 more light may need to be captured to allow for a good reception, the second light deflecting surface SF2 can preferably be configured to be larger than the first light deflecting surface SF1. The second surface SF2 may be larger in a direction that is circumferential to the swivelling movement.

The first and second surface SF1, SF2 can thus be configured to be more adapted to their assigned purpose. This allows to save cost, weight and packaging size of the optical arrangement 3.

Figure 2 schematically shows a vehicle 10, for example a passenger car. A lidar system 5 is arranged in a front area of the vehicle 10. The lidar system 5 comprises the optical transmission device 1 and the optical reception device 2. The optical arrangement 3 is arranged between the transmission device 1 and the reception device 2. In the control unit 7, the transmitted and received light beams LB may be evaluated e. g. using time-of-flight measurements. The evaluation may serve to detect objects O in the target area 6. The control unit 7 can also be used to monitor and control the transmitting process in the transmission device 1, the receiving process in the reception device 2 and the pivotal movement of the optical arrangement 3. The target area 6 is located in front of the vehicle 10. Thus, in the example shown, an area in front of the vehicle 10 in the direction of travel can be monitored. It is also possible to arrange the lidar system 5 in other areas of the vehicle 10, for example in the rear area and/or in side areas. It is also possible to arrange several lidar systems 5 on the vehicle 10, in particular also in corner areas of the vehicle 10.

The lidar system 5 can be used to detect stationary or moving objects in the target area 6. Objects may in particular be vehicles, persons, animals, plants, obstacles, roadway unevenness, in particular potholes or stones, roadway boundaries, traffic signs, open spaces, in particular parking spaces, precipitation, or the like.

As described in connection with the preceding figure, it is possible to deflect the transmitted light beam LB by means of the optical arrangement 3 in such a way that it slides over the target area 6 as a light beam LB deflected by the first light deflecting surface SF1. The light beam LB thereby scans the target area 6, i.e. illuminates it step by step. The light beam LB is then reflected back by objects in the target area 6 and deflected by the second light deflecting surface SF2 of the optical arrangement 3 in the second direction D2 onto the reception device 2. Reception of the received light beam LB is then performed by the reception device 2.

The described lidar system 5 can be compactly designed with the transmission device 1 and the reception device 2 located in roughly one line on opposing sides of the optical arrangement 3. This means that installation space in the vehicle 10 may be reduced. At the same time, precise and efficient scanning of the target area 6 can be realized.

Claims

1. Optical arrangement (3) comprising a mounting support (4) and a first and a second light deflecting surface (SF1, SF2), wherein the mounting support (4) is pivotably mounted for the first and second light deflecting surfaces (SF1, SF2) to perform a pivoting movement, wherein the first light deflecting surface (SF1) is arranged such that a light beam (LB) which is incident from a first direction (DI) is deflectable by the first light deflecting surface (SF1) in the direction of a target area (6) during the pivoting movement, wherein the second light deflecting surface (SF2) is arranged such that the light beam (LB) being reflected from the target area (6) is deflectable by the second light deflecting surface (SF2) in a second direction (D2) during the pivoting movement.

2. Optical arrangement according to claim 1, wherein the pivoting movement is limited to a swivelling movement such that the deflection direction of the first light deflecting surface (SF1) is different from the second direction (D2) and the incident direction of the second deflecting surface is different from the first direction (DI).

3. Optical arrangement according to claim 1 or 2, wherein the first light deflecting surface (SF1) is associated with light incident from the first direction (DI) and the second light deflecting surface (SF2) is associated with light deflected in the second direction (D2).

4. Optical arrangement according to one of the preceding claims, wherein the pivoting movement is common to the first and second light deflecting surface (SF1, SF2).

5. Optical arrangement according to one of the preceding claims, wherein the angle between the first light deflecting surface (SF1) and the first direction (DI) changes with the pivoting movement.

6. Optical arrangement according to one of the preceding claims, wherein the angle between the second light deflecting surface (SF2) and the second direction (D2) changes with the pivoting movement.

7. Optical arrangement according to one of the preceding claims, wherein the first light deflecting surface (SF1) and/or the second light deflecting surface (SF2) comprises a planar surface.

8. Optical arrangement according to claim 7, wherein the first light deflecting surface (SF1) and the second light deflecting surface (SF2) are adjacent to each other.

9. Optical arrangement according to claim 7 or 8, wherein the first light deflecting surface (SF1) and the second light deflecting surface (SF2) are arranged in an angle with respect to each other, the size of the angle being between around 60° and around 120°, preferably around 90°.

10. Optical arrangement according to one of the preceding claims, wherein the second light deflecting surface (SF2) is larger than the first light deflecting surface (SF2).

11. Optical arrangement according to claim 10, wherein the extension of the second light deflecting surface (SF2) in a circumferential direction of the pivotal movement is larger than the extension of the first light deflecting surface (SF1) in this direction.

12. Optical arrangement according to one of the preceding claims, wherein the first direction (DI) and the second direction (D2) are longitudinal to each other.

13. Use of the optical arrangement of one of the previous claims in a lidar system (5), in particular a scanning lidar system (5).

14. Lidar system (5) comprising an optical transmission device (1) configured to transmit a light beam (LB) in a first direction (DI), an optical reception device (2) configured to receive the light beam (LB) from a second direction (D2) and the optical arrangement (3) according to of one of claims 1 to 12.

15. Lidar system according to claim 14, wherein the first light deflecting surface (SF1) is assigned to deflect the light beam (LB) transmitted by the transmission device (1) and the second light deflecting surface (SF2) is assigned to deflect the light beam to be received by the reception device (2).

16. Lidar system according to claim 14 or 15, wherein the transmission device (1) and the reception device (2) are arranged on opposing sides of the optical arrangement (3).

17. Lidar system according to one of claims 14 to 16, wherein the transmission device (1) and the reception device (2) are configured to inter-op- erate to monitor the target area (6) using the light beam (LB) transmitted by the transmission device (1).

18. Lidar system according to one of claims 14 to 17, wherein the target area (6) is scannable by the light beam (LB) deflected by the first light deflecting surface (SF1).

19. Lidar system according to one of claims 14 to 18, further comprising a control unit (7) configured to control the transmission of the light beam (LB) by the transmission device (1), the reception of the light beam (LB) by the reception device (2), the pivotal movement of the optical arrangement (3), the control unit (7) being further configured to evaluate the transmitted and received light beam (LB).

20. Method for operating a lidar system (5) comprising an optical transmission device (1), an optical reception device (2) and an optical arrangement (3) comprising a mounting support (4) and a first and a second light deflecting surface (SF1, SF2), wherein the mounting support (4) is pivotably mounted for the first and second light deflecting surfaces (SF1, SF2) to perform a pivoting movement, the method comprising the transmission device (1) transmitting a light beam (LB) in a first direction (DI), the first light deflecting surface (SF1) deflecting the light beam (LB) in the direction of a target area (6), the second light deflecting surface (SF2) deflecting the light beam (LB) reflected from the target area (6) in the second direction (D2), the reception device (2) receiving the light beam (LB), wherein the pivotal movement causes the light beam (LB) deflected by the first light deflecting surface (SF1) to perform a scan of the target area (6) and wherein the pivotal movement is performed such that the incident direction of the second light deflecting surface (SF2) is different from the first direction (DI) during the pivotal movement.