Lidar device, lidar front end, lidar system, and method for performing lidar measurements

Abstract

The present invention relates to a LIDAR device (10) comprising a light generation and detection portion (1) configured to generate a plurality of spatially separated light signals and configured to detect the plurality of spatially separated light signals; and an optical coupler (2) that interacts with the light generating and detecting section (1) and is configured to be optically coupled to a plurality of optical waveguides (31) that transmit optical signals generated by the light generating and detecting section (1) to the light LIDAR front end (20) and optical signals from the light LIDAR front end (20) to the light generating and detecting section (1). The invention also relates to a LIDAR front end, a LIDAR system and a method for performing a LIDAR measurement.

Description

[0001] The invention relates to a LIDAR device as claimed in claim 1, a LIDAR front end as claimed in claim 11, a LIDAR system as claimed in claim 13 and a method for performing LIDAR measurements as claimed in claim 16.

[0002] LIDAR systems are used in multiple technology areas, such as autonomous driving, robotics, and end-user devices (e.g., mobile phones). In particular, coherent LiDAR systems, such as frequency modulated continuous wave (FMCW) LiDAR, are becoming increasingly popular. However, a common challenge facing LIDAR systems is spatial resolution. For example, coherent scanning LiDAR systems can suffer from an inherent trade-off between resolution and frame rate. More specifically, higher resolution requires more pixels per frame, while each pixel requires a certain measurement time. Therefore, the frame rate can be reduced to increase the resolution, and vice versa. To this day, this remains a major challenge in deploying coherent scanning LiDAR in high-dynamic applications such as advanced driver assistance systems (ADAS).

[0003] It is therefore an object of the present invention to improve the performance of LIDAR systems.

[0004] According to the present invention, in a first aspect, a LIDAR device is provided, the LIDAR device comprising:

[0005] - a light generation and detection portion configured to generate a plurality of spatially separated light signals (which are to be transmitted to the object) and configured to detect a plurality of spatially separated light signals (which are received from the object); and

[0006] - an optical coupler that interacts with the light generation and detection part and is configured to optically couple to a plurality of optical waveguides that transmit optical signals generated by the light generation and detection part to the optical LIDAR front end, and transmit optical signals from the optical LIDAR front end to the light generation and detection part.

[0007] The LIDAR device can be part of a spatial division multiplexing LIDAR system, which - in addition to the LIDAR device itself - includes a plurality of optical waveguides and a LIDAR front end for transmitting the optical signal generated by the LIDAR device to the target object. For example, the LIDAR front end includes a corresponding scanning mechanism, which will be discussed further below. More specifically, the LIDAR device can be placed at a certain distance from the LIDAR front end and connected to the LIDAR front end via a plurality of optical waveguides. The plurality of optical waveguides can be formed by a plurality of independent optical fibers (i.e., optical fiber bundles) and / or at least one multi-core optical fiber.

[0008] The optical coupler of the LIDAR device may include multiple outputs, each of which is to be assigned to one of the optical waveguides. More specifically, the outputs of the optical coupler can be assigned (e.g., coupled) to the optical waveguides in a one-to-one relationship, that is, each of the outputs is assigned to a different optical fiber. More specifically, the coupler of the LIDAR device is configured to adapt the light output geometry of the light generation and detection portion to the geometry of multiple optical waveguides (e.g., multi-core optical fibers or optical fiber bundles). For example, the coupler of the LIDAR device is a multi-core fiber coupler.

[0009] According to another embodiment, the light generation and detection portion comprises a single light emitter, wherein the light generation and detection portion is configured to generate spatially separated light signals using light generated by the single light emitter (eg, using a beam splitter).

[0010] However, the light generation and detection portion may include a plurality of light emitters, wherein the light generation and detection portion is configured to generate each of the spatially separated optical signals using light generated by one of the light emitters. For example, the emitters are assigned to the optical waveguides in a one-to-one relationship, i.e., each of the emitters is assigned to a different optical fiber.

[0011] Furthermore, the light generation and detection portion of the LIDAR device may include a plurality of detectors for detecting light signals transmitted from the LIDAR front end via the optical waveguide.

[0012] For example, the light generating and detecting parts of the LIDAR device are formed as a photonic integrated circuit (PIC), ie as an integrated device comprising, for example, an emitter and / or a detector.

[0013] Furthermore, the light generation and detection section may include a plurality of subsections (e.g., functional blocks), wherein each of the subsections includes one of the light emitters and / or one of the detectors mentioned above. Each of the subsections may include other components such as other optical elements (e.g., circulators). The subsections (including their components, such as emitters, detectors, and / or at least one other component such as a circulator) may be formed by a PIC (wherein the PIC may implement all or at least some of the subsections).

[0014] According to another embodiment, the light generation and detection part is configured to generate and / or detect the light signal using a coherent light modulation and / or detection scheme. The coherent light modulation and / or detection scheme may be based on a frequency modulated continuous wave. Therefore, at least one of the light emitters of the light generation and detection part may be formed by a frequency modulated continuous wave laser.

[0015] The LIDAR device may also include an electronic circuit configured to process (e.g., pre-equalize) an electrical signal to be provided to the emitter of the light generation and detection part, and / or configured to receive and process an electrical signal from the detector of the light generation and detection part, the electrical signal representing the signal to be optically transmitted (e.g., data) and the optical signal received by the light generation and detection part, respectively. The electronic circuit may include a digital signal processing (DSP) unit or processor configured to process the electrical signal to be provided to the emitter and / or the electrical signal received from the detector, for example, in a manner that eliminates or at least mitigates crosstalk between spatially separated optical signals (i.e., between different spatially separated LIDAR channels). For example, the electronic circuit uses a MIMO (multiple input multiple output) scheme for processing the signal to be provided to the emitter and / or for processing the signal received from the detector. Specifically, the detector signals originating from the received adjacent optical signals (pixels) are jointly processed with the help of a MIMO algorithm. MIMO algorithms, for example, take into account crosstalk components (eg, all possible crosstalk components) of spatially separated optical signals (ie, optical channels).

[0016] Furthermore, the LIDAR device may be implemented by a common module, for example, comprising a light generating and detecting part and an electronic circuit. For example, the light generating and detecting part (which may be formed as a PIC as described above) and the electronic circuit are arranged in a common housing.

[0017] In a second aspect, the present invention relates to a LIDAR front end configured to transmit an optical signal generated by a LIDAR device as described above to an object, wherein the LIDAR front end comprises an optical front end coupler configured to optically couple to a plurality of optical waveguides for transmitting the optical signal generated by the LIDAR device and transmitting the optical signal from the LIDAR front end (i.e. the object) back to the LIDAR device. The LIDAR front end may be a passive device.

[0018] The LIDAR front end may include a scanning mechanism that is configured to send an optical signal received via an optical waveguide and a front end coupler to an object. In addition, the scanning mechanism may be configured to send light (optical signal) received from an object, particularly light reflected at the object, to the LIDAR device (via a front end coupler and an optical waveguide).

[0019] In addition, the front-end coupler can include PICs and / or micro-optics (or other beam forming optics) to collimate and / or redirect optical signals received from the plurality of optical waveguides. For example, the scanning mechanism includes at least one reflective element (e.g., a mirror). The at least one reflective element can be moved in such a way that it can redirect incident light to a plurality of directions to scan the object.

[0020] In a third aspect, the present invention relates to a LIDAR system comprising a plurality of optical waveguides and at least one of the LIDAR device and the LIDAR front end as described above, wherein an optical coupler of the LIDAR device is optically coupled to the plurality of optical waveguides (e.g., optically coupled to one end of an optical fiber) and / or an optical front end coupler of the LIDAR front end is optically coupled to the plurality of optical waveguides (e.g., optically coupled to the other end of the optical fiber).

[0021] The plurality of optical waveguides may be formed by at least one multi-core optical fiber (MCF). Specifically, each of the plurality of cores of the MCF is combined with a cladding material at least partially surrounding the core to form an optical waveguide.

[0022] According to another solution, the plurality of optical waveguides may be formed by a plurality of independent optical fibers (ie, an optical fiber bundle). It is also conceivable to use both multi-core optical fibers and a plurality of independent optical fibers to realize the plurality of optical waveguides of the LIDAR system.

[0023] Therefore, the LIDAR system can combine the parallelization of multiple transmitters and receivers (e.g., subunits of the above-mentioned LIDAR device) with space division multiplexing (SDM) through a common scanning unit to increase the capacity of the LIDAR system. More specifically, the use of a multi-core optical fiber or an optical fiber bundle to connect the LIDAR device and the LIDAR front end can allow for a more flexible arrangement of the components of the LIDAR system. This may be beneficial for applications where the LIDAR front end needs to be lightweight and far away from the nearest power source (e.g., in a vehicle such as a car). For example, the LIDAR device can be arranged at a considerable distance from the LIDAR front end. Specifically, all optical signals can be sent through one optical fiber component (e.g., a multi-core optical fiber or an optical fiber bundle), which acts as an interface between the (e.g., passive) optical LIDAR front end and the processing unit (LIDAR device).

[0024] In addition, adaptive field of view (FOV) management of the scanning mechanism can be used to further increase the frame rate. This can include scanning parts of the scene that contain relevant information (such as moving objects) at a higher resolution and scanning less relevant areas in a coarser manner. In order to identify these scenes (i.e., areas of interest), intelligent algorithms or deep learning algorithms (such as convolutional neural networks) can be used.

[0025] Therefore, the LIDAR system according to the present invention can provide at least one of the following: i) improving the frame rate and resolution of scanning LiDAR by using space division multiplexing; ii) achieving miniaturization and optical integration (e.g., using PIC), using multi-core optical fiber or fiber bundles and special optical couplers (e.g., MCF couplers) to allow the optical LIDAR front end to be separated from the processing unit (LIDAR device); and iii) advanced digital signal processing with crosstalk suppression and adaptive field of view management for FMCW LiDAR (e.g., using deep learning algorithms). The SDM LiDAR system according to the present invention can be applied in highly dynamic sensing scenarios, such as advanced driver assistance systems, infrastructure traffic monitoring, industrial robotics, or even end-user applications.

[0026] The present invention also relates to a method for performing LIDAR measurements, in particular a method for performing LIDAR measurements using the LIDAR system described above, the method comprising:

[0027] - generating and / or detecting a plurality of spatially separated optical signals;

[0028] - transmitting the generated spatially separated optical signals to the object via a plurality of optical waveguides and / or receiving the spatially separated optical signals from the object via a plurality of optical waveguides.

[0029] Features of the embodiments described above in connection with a LIDAR system may similarly be used to modify the method described above.

[0030] The embodiments of the present invention will be described below with reference to the accompanying drawings. The accompanying drawings show:

[0031] Figure 1 schematically illustrates a LIDAR system according to an embodiment of the present invention; and

[0032] Figure 2 The optical signal generated by the LIDAR system according to the present invention is shown.

[0033] Figure 1 The LIDAR system 100 shown in FIG. 1 comprises a LIDAR device 10 and a LIDAR front end 20. The LIDAR device 10 and the LIDAR front end 20 are optically coupled to each other via a multi-core optical fiber MCF 30, and a plurality of cores 31 of the MCF 30 implement a plurality of spatially separated optical waveguides.

[0034] More specifically, the LIDAR device 10 includes a light generation and detection part 1, which in turn has a plurality of sub-parts in the form of LIDAR blocks 11. Each of the LIDAR blocks 11 includes at least one light emitter (e.g., an FMCW laser) and at least one detector (e.g., a photodiode). With the aid of the emitters and detectors of different LIDAR blocks 11, the light generation and detection part 1 is capable of generating and detecting a plurality of spatially separated light signals. Alternatively, the independent emitters of at least some of the different LIDAR blocks may be replaced by a single universal emitter, wherein the output of the single emitter is divided into a plurality of spatially separated light signals. In addition, in the case of coherent detection, a portion of the light output of the universal emitter may be used as a reference signal supplied to the LIDAR block 11. The LIDAR block 11 may be formed by a universal module 50, for example, the LIDAR block 11 may be arranged on a universal substrate. For example, at least some of the LIDAR blocks 11 are implemented by photonic integrated circuits (PICs). Furthermore, each of the LIDAR blocks 11 may include additional optical components, such as at least one circulator. Furthermore, the LIDAR blocks 11 may provide optical inputs and optical outputs, such that the LIDAR device 10 is equipped with multiple independent optical inputs and multiple independent optical outputs.

[0035] The LIDAR device 10 also includes an optical coupler 2 that interacts with the LIDAR block 11 and optically couples them to the MCF 30. More specifically, the optical coupler 2 is configured and coupled to the LIDAR block 11 in such a manner that spatially separated optical signals generated by the transmitter of the LIDAR block 11 are coupled to the optical waveguide (i.e., the optical fiber core 31) of the MCF 30. The LIDAR block 11 can be coupled to the optical fiber core 31 via the optical coupler 2 one-to-one.

[0036] Therefore, the spatially separated optical signals generated by the LIDAR block 11 are transmitted to the LIDAR front end 20 via the MCF 30. Conversely, the optical signals output by the LIDAR front end 20 are transmitted to the detector of the LIDAR block 11 by means of the MCF 30. It should be noted that, as already described above, an optical fiber bundle may be used instead of a multi-core optical fiber.

[0037] In addition, the LIDAR device 10 may include an electronic circuit configured to provide a control signal to the transmitter of the LIDAR block 11 and / or configured to receive and process an electrical signal from the detector of the LIDAR block 11. For example, the electronic circuit includes a digital signal processor, DSP3. DSP3 can be configured to process signals to be provided to the transmitter and / or signals received from the detector, thereby mitigating crosstalk between spatially separated optical signals (i.e., between different spatially separated LIDAR channels). For example, DSP3 adopts a MIMO scheme, which processes received spatially adjacent optical signals, i.e., optical signals from adjacent pixels. Therefore, the LIDAR device 10 can be a processing unit that is configured to generate and receive spatially separated optical signals and is also capable of electronically processing electrical signals supplied to the transmitter and received from the detector. Therefore, MCF30 acts as an interface between the LIDAR processing unit (LIDAR device 10) and the (e.g., passive) LIDAR front end.

[0038] The optical front end 20 includes an optical front end coupler 21, which is optically coupled to the MCF 30, for example, by means of a plurality of optical elements 211 assigned to the optical fiber core 31 of the MCF 30. The optical elements 211 are configured to collimate and redirect light received from the optical fiber core 31 of the MCF. The optical front end coupler 21 can be formed as a PIC.

[0039] Furthermore, the optical front end 20 includes a scanning mechanism 22 configured to transmit an optical signal received via the MCF 30 and the front end coupler 21 to an object to be investigated (not shown). The scanning mechanism 22 may include a single movable mirror or a plurality of movable mirrors.

[0040] The light received from the scanned object returns through the same path and can be passed from the circulator of the LIDAR block to the corresponding detector. In addition, the distance information (eg, pixel distance information) can be obtained by digital signal processing (eg, implemented by DSP3).

[0041] Figure 2 An example of the light output generated by the LIDAR system of the present invention is shown. The light output includes a plurality of spatially separated light signals OS that move together to a plurality of different scanning positions P. The spatially separated light signals OS are generated by the LIDAR device (e.g., Figure 1 The LIDAR block 11 shown in FIG. 1 is generated by a plurality of waveguides (e.g., Figure 1The optical signals OS are outputted from the MCF 30 in the system. For example, each core of the MCF projects a light spot, i.e., a pixel or sub-pixel. The spatially separated optical signals OS are moved to a plurality of scanning positions P by means of a scanning mechanism of the LIDAR front end of the system. Therefore, the optical signals OS arrive at different scanning positions P at subsequent time points. Figure 2 The joint demonstration in is for illustrative purposes only. Thus, a (e.g., passive) increase in resolution of a given factor given by the number of optical waveguides (e.g., number of MCF cores) between the LIDAR device and the LIDAR front end can be achieved, independent of the frame rate.

[0042] It is important to note that there may be gaps between the light signals OS (e.g., the light spots, "pixels") generated by the light signals. However, the gaps may be small or non-existent. Thus, the spatial separation of the light signals generated by the LIDAR device of the LIDAR system may also be related to the distance between the centers of the light signals.

Claims

1. A LIDAR device (10), comprising: - An optical generation and detection section (1), which is configured to generate a plurality of spatially separated optical signals and is configured to detect a plurality of spatially separated optical signals; and - An optical coupler (2), which interacts with the optical generation and detection section (1) and is configured to optically couple to a plurality of optical waveguides (31), and the plurality of optical waveguides (31) transmit the optical signals generated by the optical generation and detection section (1) to the optical LIDAR front end (20), and transmit the optical signals from the optical LIDAR front end (20) to the optical generation and detection section (1).

2. The LIDAR device according to claim 1, wherein, the optical coupler (2) includes a plurality of outputs, and each of the outputs is to be assigned to one of the optical waveguides (31).

3. The LIDAR device according to claim 1 or 2, wherein, the optical generation and detection section (1) includes a single optical transmitter and is configured to generate the spatially separated optical signals using the light generated by the single optical transmitter.

4. The LIDAR device according to claim 1 or 2, wherein, the optical generation and detection section (1) includes a plurality of optical transmitters and is configured to generate each of the spatially separated optical signals using the light generated by one of the optical transmitters.

5. The LIDAR device according to any one of the preceding claims, wherein, the optical generation and detection section (1) includes a plurality of detectors for detecting the optical signals transmitted from the LIDAR front end (20) via the optical waveguides (31).

6. The LIDAR device according to claim 4 or 5, wherein, the optical generation and detection section (1) includes a plurality of sub - sections (11), and each of the sub - sections (11) includes one of the optical transmitters and / or one of the detectors.

7. The LIDAR device according to any one of the preceding claims, wherein, the optical generation and detection section (1) is at least partially formed by a photonic integrated circuit.

8. The LIDAR device according to any one of the preceding claims, wherein, the optical generation and detection section (1) is configured to generate and / or detect the optical signals using a coherent optical modulation and / or detection scheme.

9. The LIDAR device according to any one of the preceding claims, wherein, the optical generation and detection section (1) includes at least one frequency - modulated continuous - wave laser.

10. The LIDAR device according to any one of the preceding claims, further comprising an electronic circuit, the electronic circuit being configured to process the electrical signals to be provided to the transmitters of the optical generation and detection section, and / or being configured to receive and process the electrical signals from the detectors of the optical generation and detection section, wherein, the electronic circuit employs a MIMO scheme for processing the signals to be provided to the transmitters and / or for processing the signals received from the detectors.

11. A LIDAR front end (20) configured to transmit an optical signal generated by the LIDAR device (10) according to any one of claims 1 to 10 to an object and receive the optical signal, wherein, the LIDAR front end (20) includes an optical front end coupler (21) configured to optically couple to a plurality of optical waveguides (31) for transmitting the optical signal generated by the LIDAR device (10) and transmit the optical signal from the LIDAR front end (20) to the LIDAR device (10).

12. The LIDAR front end according to claim 11, including a scanning mechanism (22) configured to transmit the optical signal received via the optical waveguide (31) and the optical front end coupler (21) to the object.

13. A LIDAR system (100), comprising: a plurality of optical waveguides (31), and at least one of the LIDAR device (10) according to any one of claims 1 to 10 and the LIDAR front end (20) according to claim 11 or 12, wherein the optical coupler (2) of the LIDAR device (10) is optically coupled to the plurality of optical waveguides (31) and / or the optical front end coupler (21) of the LIDAR front end (20) is optically coupled to the plurality of optical waveguides (31).

14. The LIDAR system according to claim 13, wherein, the plurality of optical waveguides (31) are formed by at least one multi-core optical fiber (30).

15. The LIDAR system according to claim 13, wherein, the plurality of optical waveguides are formed by a plurality of independent optical fibers.

16. A method for performing LIDAR measurement, particularly a method for performing LIDAR measurement using the LIDAR system (100) according to any one of claims 13 to 15, the method comprising: - generating and / or detecting a plurality of spatially separated optical signals; - transmitting the generated spatially separated optical signals to an object via a plurality of optical waveguides (31), and / or receiving the spatially separated optical signals from the object via the plurality of optical waveguides (31).

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