Lidar device

Abstract

The present invention relates to a lidar device for detecting the surroundings of a vehicle, wherein the lidar device comprises a laser light source (12) and a first optical head (18) with an optical transmitter and receiver unit (48) for emitting the laser light and for receiving laser light reflected from the surroundings. A detector (14) is provided for converting received laser light into electrical signals. According to the invention, the lidar device further comprises at least one additional optical head (22) with an optical transmitting and receiving unit (48) for emitting the laser light into the environment and for receiving laser light that has been reflected from the environment, wherein optical connections (16, 20) are provided to guide the laser light emitted by the laser light source (12) first to the first optical head (18) and from there to the additional optical head (22).

Description

[0001] The present invention relates to a lidar device according to the preamble of claim 1.

[0002] A lidar device of this type is used to detect the surroundings of a vehicle. Such a lidar device includes a laser light source designed to emit laser light. An optical head is provided with an optical transmitter and receiver unit for transmitting the laser light into the surroundings and for receiving laser light reflected from the surroundings. A lidar device of this type also includes a detector designed to convert received laser light into electrical signals.

[0003] In known lidar devices, both the laser and the detector are integrated into the optical head. These optical heads typically have a two-dimensional scanning capability, allowing scanning in both horizontal and vertical directions. When more than one optical head is used, their installation positions are usually chosen so that their coverage areas essentially complement each other, achieving as close to 360° coverage around the vehicle as possible.

[0004] The size of conventional optical heads for lidar devices is comparatively large, as the laser, detector, and scanning unit must all be accommodated. The necessary electronics are also housed within the optical head. Due to these components, such a conventional optical head generates a relatively large amount of heat, typically 20 to 30 watts. This results in significant heating of the installation space. However, such an optical head can only operate up to a maximum temperature, which cannot be raised arbitrarily. The maximum operating temperature depends on the temperature-dependent efficiency of the laser, the temperature-dependent noise of the detectors, and the maximum permissible operating temperatures of the semiconductor components used. These factors limit the available installation positions and necessitate sophisticated thermal management of the installation space and the components.

[0005] In known systems, data preprocessing is also integrated into the lidar head, and the generated data volumes can exceed the capacity of existing data lines. Electrical data lines therefore represent a limiting factor and require elaborate shielding measures.

[0006] It is therefore the object of the present invention to create a lidar device in which these problems are solved.

[0007] This problem is solved by a lidar device according to the characterizing feature of claim 1.

[0008] According to the invention, the lidar device has at least one further optical head with an optical transmitting and receiving unit for emitting laser light into the environment and for receiving laser light reflected from the environment. Optical connections are provided to guide the laser light emitted by the laser light source first to the first optical head and from there to the further optical head.

[0009] Preferably, the optical connections installed between the laser light source and the detector will be designed as fiber optic connections or as waveguide structures on a photonic chip.

[0010] A lidar device according to the invention offers the advantage that only one laser light source is required, which can also be of a modular design. In contrast, no laser light source needs to be provided in the individual optical heads, since each optical head receives laser light emitted by the preceding optical head. Various optical heads are therefore optically connected in series, forming a serial chain. Such a chain is often referred to as a "daisy chain" and includes upstream (arranged before a specific head) and downstream (arranged after a specific head) optical heads. The first advantage of such a daisy chain is the simplicity of its construction, and another is the easy scalability of the lidar device. Thus, depending on the number of optical heads required, an additional optical head can easily be added to an existing lidar device.

[0011] By using a central laser light source, the installation space required for an optical head can be reduced. This reduction in required installation space results not only from the elimination of laser light sources in the optical heads. Because less heat is generated in the optical heads, less space is needed for heat dissipation.

[0012] Further preferred embodiments of the present invention are set forth in the dependent claims.

[0013] In a first preferred embodiment of a lidar device according to the invention, the optical connections or further optical connections are provided to direct laser light received from the first optical head to the detector and to direct laser light received from the further optical head to the first optical head and from there to the detector.

[0014] This embodiment of the invention offers the advantage that the detector can also be arranged as a single detector or as a detector module in a central unit, thus eliminating the need for a separate detector in each optical head. This also offers the advantage of further reducing the required installation space for the optical heads. Furthermore, since signal transmission between the laser light source and the detector on the one hand, and the optical heads on the other, is optical, the electromagnetic compatibility (EMC) requirements are less critical than in known lidar devices, where received laser light is converted into high-frequency electrical signals within the optical heads and then transmitted to a central unit via electrical lines.

[0015] In a further preferred embodiment of the present invention, the lidar device comprises a plurality, e.g., n, of optical heads connected in a chain. n is a natural number > 1 and can, for example, serve to number the number of optical heads used. Optical connections are provided to transmit laser light to be emitted by an optical head (e.g., n) from an upstream optical head (e.g., n-1).

[0016] These or optionally further optical connections can be provided to transmit laser light received from downstream optical heads (>n) to a head. This offers the advantage that the emitted laser light can be sequentially passed from one optical head to the subsequent optical heads. Conversely, each optical head can receive laser light from downstream optical heads and forward it towards the detector. This sequential connection of the various optical heads represents the "chain-like" arrangement in the sense of a daisy chain.

[0017] In a further preferred embodiment of the present invention, the lidar device comprises a master unit which includes the laser light source and the detector. Providing such a master unit offers the advantage that the laser light source and detector can be arranged centrally in the vehicle and thus not in one of the optical heads, which reduces the installation space required for arranging the optical heads.

[0018] Such a master unit can employ a planning unit designed to assign a transmit and / or receive schedule to each optical head. This offers the advantage that the master unit can coordinate when an optical head emits laser light into the environment. Furthermore, the master unit can control when an optical head receives laser light reflected from the environment and when an evaluation should take place. For example, it can be stipulated that only one optical head emits laser light into the environment at any given time. If several optical heads are to emit laser light into the environment simultaneously, it can be stipulated that only those optical heads whose detection ranges do not overlap emit laser light. This prevents mutual interference.Therefore, a time-division multiplexing method can be implemented, and the master unit can control which optical heads emit laser light into the environment during which time slices. A corresponding transmission and / or reception schedule can further stipulate that while only one optical head, or at least not all optical heads, are emitting laser light, other optical heads may still receive laser light reflected from the environment, and not just those optical heads that are emitting laser light.

[0019] Preferably, either the master unit or each optical head has a delay line designed to store a portion of the laser light emitted by the laser light source and make it available to the detector for performing a heterodyne process. Such a delay line can be an optical storage element, such as an optical storage ring.

[0020] Heterodyne detection methods are known from telecommunications and optics for the detection and analysis of signals. Waves of an unknown frequency are detected by mixing them with waves of a reference frequency. Here, the electric field of a received signal is mixed with the electric field of a local oscillator. This mixing is based on a non-linear product of the input signals, such that at least part of the output signal is proportional to the square of the input signals. Essentially, mixing products with sum and difference frequencies are determined. The amplitude of the downmixed signal is larger than the amplitude of the original signal itself, since a large amplitude of the local oscillator also results in a large "difference frequency amplitude."

[0021] In such a method according to the present invention, the optical signal reflected and received from the environment is mixed with a stored portion of the laser light. Optical mixing of the stored and reflected laser light takes place on a detector. Since both portions are temporally coherent (the coherence length of the laser must be sufficiently large to meet this condition), the electric fields—provided the polarization directions allow this—of the light from the local oscillator and the light from the reflection of the environment interfere, so that the corresponding signal of the difference frequency of the two optical interference partners is detected on the detector.The heterodyne mixing frequencies (signal frequency plus oscillator frequency and signal frequency minus oscillator frequency) allow for improved detection because, firstly, the signal is downmixed to lower frequencies, which can be detected with standard electronic components without significant effort. Secondly, the detectable amplitude is the product of the field amplitude of the reflected light and the field amplitude of the stored light. Unlike the amplitude of the reflected light, which is determined by extrinsic factors, the amplitude of the stored light can be chosen to be arbitrarily large during system design. This selectable gain factor thus allows for the generation of a stably detectable signal.The other frequency components, such as the oscillation frequency of the two electric fields of the light rays, as well as the sum frequency, are also present, but are in a frequency range that the electronics cannot follow.

[0022] In a further preferred embodiment of the present invention, each optical head has an optical amplifier designed to amplify the emitted laser light transmitted to the subsequent optical head before transmission. This embodiment of the present invention also offers the particular advantage of scalability of the lidar device. For example, if several optical heads need to be added to a lidar device, they can be connected to the chain of existing optical heads without having to change the central laser light source. By providing optical amplifiers in the optical heads, downstream optical heads always have sufficient laser light available for emission into the environment without having to change the central laser light source.

[0023] Preferably, each optical head (n) includes an optical combiner designed to combine light received by the optical head (n) with light received by subsequent or downstream optical heads (>n). This offers the advantage that only one optical connection between the optical heads is required to transmit the received laser light from each head back towards the centrally located detector. This eliminates the need to establish a separate optical connection from each optical head to the detector.

[0024] Accordingly, in a further preferred embodiment of the present invention, each optical head (n) has a splitter which is designed to direct emitted light proportionally to a transmitting unit of the optical head (n) and to the subsequent or following optical heads (>n). This embodiment of the present invention also offers the advantage of a chain-like arrangement of the optical heads, so that a separate optical connection does not have to be established from the central laser light source to each optical head in order to supply these optical heads with emitted laser light.

[0025] Preferably, each optical head has a variable optical delay generator designed to control the timing of the laser light transmitted to the next optical head. This offers the advantage that, for example, the timing of the laser light transmission to a subsequent optical head can be controlled according to a transmission and / or reception schedule.

[0026] In a particularly preferred embodiment of the present invention, the lidar device is configured to emit laser light with a first linear polarization direction. Detection is performed with laser light of a second linear polarization direction, wherein the first and second polarization directions are perpendicular to each other. Because the emission and detection of laser light are performed with different polarization directions, the daisy chain configuration of this embodiment of the present invention can be simplified such that only one optical connection needs to be established between the optical heads, through which the emitted and detected laser light travel in two different directions and independently of each other.To create the basic condition for stored light and reflected light to interfere during reception, the polarizations are aligned with each other before detection.

[0027] Preferably, at least one or all optical connections between the laser light source and the detector are designed as fiber optic connections and optionally as polarization-maintaining fiber optic connections or, preferably, as polarization-maintaining waveguide structures on a photonic chip. The provision of polarization-maintaining fiber optic connections or polarization-maintaining waveguide structures enables the separate transmission of laser light with different polarization directions to the optical heads and from there back to the detector.

[0028] Accordingly, preferably only one optical connection needs to be provided between the laser light source and the first optical head and between the further optical heads in order to guide emitted and received laser light of the two linear polarization directions perpendicular to each other.

[0029] In each optical head (n), a polarization splitter is preferably provided to direct emitted laser light with the first linear polarization direction to the subsequent optical head (n+1). The polarization splitter is further designed to direct laser light received from the subsequent optical heads (>n) with the second linear polarization direction towards the detector. The provision of such a polarization splitter thus offers the advantage that emitted laser light, which has the first linear polarization direction and is directed to subsequent optical heads, is separated from "returning" laser light, which was received by the subsequent optical heads and is to be directed towards the detector.

[0030] In a further preferred embodiment of such a lidar device, the master unit has a delay line, and a polarization rotator is provided between the laser light source and this delay line to rotate the first linear polarization direction of the emitted laser light into the direction of the second linear polarization direction. The delay line is arranged between the polarization rotator and the detector. Such an arrangement offers the advantage that laser light emitted in the delay line, now with the second linear polarization direction, can be temporarily stored before being fed to the detector, where it can be mixed with received laser light of the same second linear polarization direction to perform a heterodyne method.

[0031] The invention is explained in more detail below using the attached figures as examples.

[0032] This shows: Fig. 1 a first embodiment of a lidar device according to the invention with two optical heads; Fig. 2 an alternative design; and Fig. 3 a further embodiment of a lidar device according to the invention.

[0033] Fig. Figure 1 shows a lidar device according to the present invention. The lidar device can be used in the same way as the one described in Figure 1. Fig. 2 and Fig. 3 must be installed in a vehicle.

[0034] The lidar device comprises a master unit 10, which includes a laser light source 12 and a detector 14. Laser light emitted by the laser light source 12 is transmitted via an optical link 16 to a first optical head 18, and from this first optical head 18 to a second optical head 22 via a further optical link 20. The two optical heads 18 and 22 are therefore connected sequentially, or in a daisy chain, with respect to the transmission of laser light emitted by the laser light source 12. Consequently, the optical heads 18 and 22, which act as slave 1 and slave 2 in such a master / slave configuration, do not contain their own laser light sources, thus reducing the installation space required for the optical heads 18 and 22 in a vehicle.

[0035] The second optical head 22 is similar or identical to the first head 18 and accordingly identical components which the second optical head 22 has are provided with the same reference numerals and to avoid repetition will not be discussed in more detail here.

[0036] After the laser light is supplied to the first optical head 18 via the first optical connection 16, it is guided within the first optical head 18 into an optical splitter 28, which splits the laser light into two components. A first component is guided via an optical connection 30 to an optical amplifier 32, by means of which the laser light can be amplified. The provision of such an optical amplifier 32 offers the advantage that a lidar device according to the invention can be scaled very easily depending on the application or vehicle. If further optical heads of the arrangement are to be added, Fig. If 1 is added, it is not necessarily necessary to replace the laser light source 12 in the master unit 10 with a more powerful laser light source, but by providing optical amplifiers 32 in the optical heads 18 and 22 and in any additional optical heads to be added (indicated by ...) it is always ensured that sufficient laser light power is available in the optical heads.

[0037] After passing through the optical amplifier 32, the laser light in the optical head 18 is fed via a further optical connection 34 to an optical delay generator 36. This optical delay generator 34 serves to control the timing of the forwarding of the laser light towards the second optical head 22. In this way, it can be determined at what time downstream optical heads receive emitted laser light for projection into the vehicle's surroundings.

[0038] The laser light from the optical delay generator 36 is directed into an optical interface 40. The optical connection 20 between the first optical head 18 and the second optical head 22, which serves to transmit the emitted laser light, is located between this optical interface 40 and the second optical head 22. A corresponding optical interface can also be provided on the second optical head 22. Such an optical interface 40 can have optical connectors to simplify connection with fiber optic cables.

[0039] Through the optical splitter 28 in the first optical head 18, a second portion of the emitted laser light is fed via an optical connection 46 to an optical transmitter and receiver unit 48 of the first optical head 18. The optical transmitter and receiver unit 48 is designed to transmit laser light emitted by the laser light source 12 into the vehicle's surroundings (not shown) and to collect laser light reflected from the surroundings (not shown) and direct it towards the detector 14 of the master unit 10. For this purpose, the optical transmitter and receiver unit 48 can include a corresponding scanning device by means of which a detection area of ​​the first optical head 18 can be scanned to obtain a lidar point cloud of the vehicle's surroundings.

[0040] Reflected laser light received by the optical transmitter and receiver unit 48 is fed to an optical combiner 44 via an optical connection 50. This optical combiner 44 is connected to the optical interface 40 via an optical connection 42 and also receives laser light from the environment via this optical connection 42 from the second optical head 22 through its optical transmitter and receiver unit 48. These light signals, which the optical combiner 44 receives via the optical connections 42 and 50, are combined by the optical combiner 44 and fed to the detector 14 of the master unit 10 via the optical connection 24.

[0041] The lidar device according to the Fig. The system is thus structured in a chain-like manner, firstly with regard to the transmission of emitted laser light from the master unit 10 to the first optical head 18 and from there to the second optical head 22, and correspondingly to further optical heads. Secondly, the chain-like arrangement of the optical heads 18 and 22 also includes the fact that laser light reflected from the environment and received by the optical heads 18 and 22 is returned to the master unit 10 via a second pathway of optical connections 26 and 24. Emitted and received laser light is thus "passed through" the chain of optical heads 18, 22, and subsequent ones via two separate paths.

[0042] For the detection of received laser light, the master unit 10 includes a detector 14 and a variable delay line 56. Light emitted by the laser light source 12 is fed to the variable delay line 56 via an optical connection 54. The laser light source 12 thus sends not only emitted laser light to the optical heads 18 and 22, but also an optical reference signal to the variable delay line 56. A variable delay line 56 means that the laser light can be forwarded to the detector 14 via an optical connection 58 with different time delays. Such a variable delay line 56 preferably also includes the capability to store laser light received from the laser light source 12 and preferably to release it to the detector 14 in portions.The variable delay line 56 serves in particular to carry out a heterodyne method for the detection of received laser light within the detector 14 by mixing laser light received from the optical heads 18 and 22 with the reference light from the variable delay line 56.

[0043] The master unit 10 also includes a planning unit 52, which acts as an electronic control unit for the variable delay line 56 and the detector 14. The planning unit 52 is further configured to determine a transmission and reception schedule for the optical heads 18 and 22, taking into account the overall system or the entire lidar device, and in particular the number of optical heads 18, 22, etc., or slaves. Accordingly, it controls the optical heads 18 and 22, including, for example, the delay generators 36 and the optical scanning device within the optical transmit and receive units 48. Naturally, electrical connections between the planning unit 52 and these components are required for this purpose, but these connections are not shown in the figures for the sake of clarity.Alternatively, it may also be possible to transmit signals between planning unit 52 optically, using the existing optical connections for this purpose.

[0044] As already explained, in the Fig. Electrical connections are not shown; only the optical connections already described are shown. Optical connections 16, 20, 24, 26, 30, 34, 38, 40, 46, 50, 54, 58, 60, 62, 66, 70 of the Fig. 1 as well as the Fig. 2 and Fig. 3 are marked with triangular arrow symbols, which symbolically represent a propagation direction of the transmitted light. It should be noted that in the embodiments of the Fig. 1 and Fig. 2. The polarization direction of the emitted and transmitted laser light, as well as the polarization direction of the received laser light, plays no significant role and is accordingly not shown in the representations of the Fig. 1 and Fig. 2. This will not be addressed here.

[0045] The Fig. Figure 2 shows a connection to the lidar device of the Fig. 1. Alternative embodiment of the invention. The basic structure of the embodiment of the Fig. 2 is identical in many respects to the embodiment of Fig. 1, so that the same reference symbols were used for identical elements and their description referred to the description of the Fig. Reference is made to point 1. Therefore, the following discussion will focus on the Fig. 2 merely to the essential differences to the embodiment of the Fig. 1. Reference is made to.

[0046] A key difference between the two embodiments is the provision of delay lines 56 in the two optical heads 18 and 22 instead of in the master unit 10. The delay line 56 of the first optical head 18, for example, is connected to the optical splitter 28 via a further optical connection 60, so that the splitter divides the laser light, which it receives from the master unit 10 via the optical connection 16, into three components, with the two further components functioning as in the embodiment of Fig. 1 are transmitted via the optical connection 30 to the optical amplifier 32 or via the optical connection 46 to the optical transmitting and receiving unit 48.

[0047] In the optical delay line 56 (again an optical storage element or optical storage ring), laser light temporarily stored is fed via an optical connection 62 to the optical combiner 44, where it is combined with laser light received by the optical receiving units 48 of the optical heads 18 and 22 (and optionally other optical heads) and fed via the optical connection 24 to the detector 14 of the master unit 10. This enables the execution of a heterodyne detection method.

[0048] The essential difference between the embodiment of Fig. 1 and the Fig. 2 is therefore simply the relocation of delay line 56 of the Fig. 1 into the optical heads 18 and 22. A central planning unit 52 can be placed in the master unit 10 of the Fig. However, 2 will still be provided.

[0049] Another alternative embodiment of the present invention is described in the Fig. 3 schematically represented. The elements that are used in the embodiment of the Fig. 3, as provided and arranged in the preceding embodiments, are again provided with the same reference numerals and, to avoid repetition, reference is made to the description of the preceding figures.

[0050] The essential difference in the embodiment according to the Fig. 3 compared to the embodiments of the Fig. 1 and Fig. 2 is the fact that the transmission of laser light is carried out here taking polarization into account. It is assumed that the laser light source 12 of the master unit 10 of the Fig. 3 linearly polarized laser light is emitted.

[0051] The optical connections of Fig. The transmitted laser light is marked with corresponding symbols regarding its polarization. A linear polarization perpendicular to the image plane is represented by a dot, and a linear polarization within the image plane by a double arrow. One of these two polarization directions can be polarization along a high-speed axis of an optical fiber that forms the respective optical connection. The other (perpendicular) linear polarization direction can be transmitted along the low-speed axis of such an optical fiber. The two depicted linear polarization directions (dot and double arrow) are thus two mutually perpendicular linear polarization directions of the corresponding transmitted laser light.

[0052] A first advantage of such an embodiment of the invention according to the invention is the Fig. 3 results from the fact that light with two different linear polarization directions can be guided through an optical connection in two directions without the corresponding components influencing each other. For example, in contrast to the embodiments of the Fig. 1 and Fig. 2 only one optical connection 16 is provided, which now transmits the emitted and received laser light in both directions. This simplifies the construction of the lidar device according to the Fig. 3.

[0053] In such an embodiment of a lidar device according to the invention, it must be taken into account that, for the execution of a heterodyne method in the detector 14 of the master unit 10, only those light signals can be mixed together which are coherent to each other and which have the same polarization state. The coherence is, as in the embodiments of the Fig. 1 and Fig. 2 in the design according to the Fig. 3 is ensured by the corresponding coherence length of the laser light emitted by the laser light source 12. However, the agreement of the polarization states, and thus the alignment of this linear polarization in the present case, must be ensured in the embodiment of the Fig. 3. This is ensured separately. For this purpose, polarization splitters 68 are provided in the various optical heads 18 and 22 (and optionally in further optical heads), and a polarization splitter 72 is also arranged in the master unit 10. In principle, in the embodiment of the Fig. 3 As in the embodiments of the preceding figures, the laser light emitted by the laser light source 12 is guided to the optical splitter 28 of the first optical head 18 without manipulation of the linear polarization direction and from there via the optical interface 40 to the second optical head 22. The emitted laser light is radiated into the environment via the optical transmitting and receiving units 48 with this polarization direction, in the illustrated case aligned parallel to the image plane.

[0054] To ensure the subsequent separation of emitted and received laser light in the optical connections 20 and 16, which also handle the return of received laser light towards the master unit 10, a polarization rotator 64 is provided in each of the optical heads. This polarization rotator 64 rotates the polarization direction of received laser light by 90°, i.e., in the illustrated case, aligning it so that it is perpendicular to the image plane. Accordingly, in the respective combiner 44 of the optical heads 18 and 22, received laser light with a polarization direction perpendicular to the image plane is combined. In contrast, for example, to the embodiment of Fig.1. The optical combiner 44 does not forward the combined received light signals to the master unit 10 via a separate optical connection, but instead feeds them into the optical splitter 28 via an optical connection 74. Therefore, the transmission and return of laser light between the master unit 10 and the first optical head 18, and between the second optical head 22 and the first optical head 18, is carried out using only a single optical connection.

[0055] The separation of emitted and received laser light is therefore made possible by rotating the polarization direction of the received laser light.

[0056] In the master unit 10, it must be ensured that the received laser light, with its now rotated polarization direction, can be mixed with a reference signal from the delay line 56, also with the same polarization direction, in order to enable the execution of a heterodyne process. For this purpose, the master unit 10 includes an additional polarization rotator 76, which is arranged between the laser light source 12 and the variable delay line 56 via the optical connection 54 and 56. The polarization rotator 76 is designed to manipulate the portion of the emitted laser light that is to be temporarily stored in the delay line 56 by also rotating the linear polarization of the emitted laser light by 90°. After leaving the polarization rotator 76 and before being stored in the delay line 56, the light is now oriented perpendicular to the image plane and no longer parallel as it is within the optical connection 54.By providing a polarization rotator 76 in the master unit 10 and the corresponding polarization rotators 64 in the optical heads 18 and 22, the polarization direction of received laser light is rotated by 90° and also that of the temporarily stored reference signal, thus making a heterodyne method possible. Reference symbol list 10 Master Unit 12 Laser light source 14 Detector 16 optical connection 18 first optical head 20 optical connection 22 second optical head 24 optical connections 26 optical connection 28 splinters 30 optical connections 32 amplifiers 34 optical connection 36 delay Generator 38 optical connection 40 optical interface 42 optical connection 44 Combiners 46 optical connection 48 optical transmitting and receiving units 50 optical connection 52 Planning Unit 54 optical connection 56 delay line 58 optical connection 60 optical connection 62 optical connection 64 Polarization rotator 66 optical connection 68 polarization splinters 70 optical connection 72 polarization splinters 74 optical connection 76 Polarization rotator

Claims

[1] Lidar device for detecting the surroundings of a vehicle, wherein the lidar device comprises: a laser light source (12) designed to emit laser light, a first optical head (18) with an optical transmitting and receiving unit (48) for emitting laser light into the environment and for receiving laser light reflected from the environment, and a detector (14) designed to convert received laser light into electrical signals, characterized by , that: the lidar device also exhibits the following: at least one further optical head (22) with an optical transmitting and receiving unit (48) for emitting the laser light into the environment and for receiving laser light that has been reflected from the environment, wherein optical connections (16, 20) are provided to guide the laser light emitted by the laser light source (12) first to the first optical head (18) and from this to the further optical head (22). [2] Lidar device according to claim 1, characterized by , that the optical links (16, 20) or further optical links (24, 26) are intended to, to direct the laser light received from the first optical head (18) to the detector (14), and to direct the laser light received from the second optical head (22) to the first optical head (18) and from there to the detector (14). [3] Lidar device according to any of the preceding claims, characterized by, that the lidar device includes a plurality of optical heads (18, 22) which are connected in a chain, and optical connections (16, 20) are provided to transmit laser light to be emitted to an optical head from an upstream optical head, and optionally further optical connections are provided to transmit laser light received from downstream optical heads to an optical head. [4] Lidar device according to any of the preceding claims, characterized by , that the lidar device has a master unit (10) which includes the laser light source (12) and the detector (14). [5] Lidar device according to claim 4, characterized by , that the master unit (10) has a planning unit (52) which is designed to assign a transmit and / or receive schedule to each optical head (18, 22). [6] Lidar device according to claim 4 or 5, characterized by, that the master unit (10) or each optical head (18, 22) has a delay line (56) which is designed to store a portion of the laser light emitted by the laser light source (12) and to make it available to the detector (14) for the execution of a dedicated heterodyne process. [7] Lidar device according to any of the preceding claims, characterized by , that each optical head (18, 22) has an optical amplifier (32) which is designed to amplify emitted laser light which is transmitted to the subsequent optical head prior to transmission. [8] Lidar device according to any of the preceding claims, characterized by , that each optical head (18, 22) has an optical combiner (44) designed to combine light received from that optical head (18) with light received from at least one downstream optical head (22). [9] Lidar device according to any of the preceding claims, characterized by , that each optical head (18) has a splitter (28) which is designed to direct emitted light proportionally to an optical transmitting unit (48) of this optical head and to at least one downstream optical head (22). [10] Lidar device according to any of the preceding claims, characterized by , that each optical head (18) has a variable optical delay generator (36) which is designed to control the timing of the transmission of emitted laser light to the downstream optical head (22). [11] Lidar device according to any of the preceding claims, characterized by, that the lidar device is designed to emit laser light with light of a first linear polarization direction and to detect with laser light of a second linear polarization direction, wherein the first and the second polarization directions are perpendicular to each other. [12] Lidar device according to any of the preceding claims, characterized by , that at least one or all of the optical connections provided between the laser light source (12) and the detector (14) are designed as fiber optic connections and optionally as polarization-preserving fiber optic connections or as preferably polarization-preserving waveguide structures on a photonic chip. [13] Lidar device according to one of claims 11 to 12, characterized by, that an optical connection (16, 20) is provided between the laser light source (12) and the first optical head (18) and between the further optical heads (22) in order to guide emitted and received laser light of the two linear polarization directions. [14] Lidar device according to any one of claims 11 to 13, characterized by , that in each optical head (18, 22) a polarization splitter (68) is provided to direct emitted laser light with the first linear polarization direction to the respective downstream optical head, and laser light received from the downstream optical heads with the second linear polarization direction towards the detector. [15] Lidar device according to one of claims 11 to 14 and according to claim 4, characterized by, that the master unit (10) has the delay line (56), and a polarization rotator (76) is provided between the laser light source (12) and the detector (14) to rotate the first linear polarization direction of the emitted laser light into the second linear polarization direction.

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