Multi-lidar detection system based on single laser light source

Abstract

The present invention discloses a multi-laser radar detection system based on a single laser light source, comprising a laser light source, an adjustable optical beam splitter, an external light source laser radar, and a controller; the light source emitted by the laser light source is coupled to the adjustable optical beam splitter or waveguide coupler through an optical fiber, and then connected to multiple external light source laser radars through an optical fiber, the external light source laser radar is provided with a photodetector, which converts the detected reflected light signal into an electrical signal and feeds it back to the controller through an electrical signal transmission line; the controller obtains the detection result based on the pulse signal of the laser light source and the feedback electrical signal of the external light source laser radar. The present invention can dynamically adjust the output optical power of each laser, thereby achieving the adjustment of the detection distance and detection sensitivity of each laser radar. The photoelectric detection module is integrated in the laser radar with an external laser light source to avoid coupling loss. The laser radar with an external laser light source and signal processing can reduce the cost of a single laser radar.

Description

Technical Field

[0001] The present invention belongs to the field of laser radar, and relates to a laser radar based on a single laser light source, an adjustable beam splitter, and multiple external light sources, to realize a system for multi-laser radar detection. Background Art

[0002] A multi-lidar detection system, comprised of multiple independent lidars, provides a more comprehensive understanding of the surrounding environment, avoiding the blind spots of a single lidar. Multi-lidar detection systems are widely used in areas such as unmanned vehicles, surveying and mapping, and surveillance.

[0003] Currently, one approach to implementing a multi-lidar system is to combine multiple independent single-line or multi-line lidars into a multi-lidar detection system. This system is expensive and has high maintenance costs. In particular, if a lidar fails, the entire lidar system must be replaced. Furthermore, it is not possible to dynamically adjust the detection range or sensitivity by adjusting the output power of each lidar. Another approach is to implement a multi-lidar system using a single light source and detector. However, this system lacks a power-adjustable beam splitter, making it impossible to dynamically adjust the output power of each lidar. Furthermore, in this system, light is coupled from space into an optical fiber and then transmitted to the optical detector, increasing the coupling loss from the spatial light to the optical fiber. Furthermore, the optical signals from different lidars, converted into optical signals using a single photodetector, are prone to crosstalk, limiting the practical application of this approach. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a multi-lidar detection system based on a single laser light source, through an adjustable optical beam splitter, multiple laser radars with external light sources, and a controller to uniformly process the electrical signals of multiple laser radars, thereby realizing an easy-to-maintain and highly adjustable multi-lidar detection system.

[0005] The specific technical solution adopted in the present invention is:

[0006] A multi-laser radar detection system based on a single laser light source includes a laser light source, an adjustable optical beam splitter, an external light source laser radar, and a controller; the light source emitted by the laser light source is coupled to the adjustable optical beam splitter or waveguide coupler through an optical fiber, and then connected to multiple external light source laser radars through optical fibers. The external light source laser radars are provided with photoelectric detectors, which convert the detected reflected light signals into electrical signals and feed them back to the controller via electrical signal transmission lines; the controller obtains detection results based on the pulse signal of the laser light source and the feedback electrical signal of the external light source laser radar.

[0007] The adjustable optical beam splitter adopts a cascaded one-to-two Mach-Zehnder interference structure based on waveguides. By applying different voltages to the metal ground electrode and source electrode on the two-arm Mach-Zehnder waveguide, the refractive index of the two arms is adjusted, thereby adjusting the optical power of the two output ports. By continuously increasing the number of cascade layers, the number of output ports can be increased.

[0008] The adjustable optical beam splitter is a 1×N adjustable optical beam splitter, and the optical power of each port is P1, P2, P3, ..., P i , P i+1 ,…,P N , where the splitting ratio of the two arms of the i-th Mach-Zehnder is: Pi / (P i+1 +P i+2 +…+P N ); Different voltages are applied to each Mach-Zehnder arm to achieve the corresponding splitting ratio, so that the optical power of each port meets the requirements.

[0009] The laser radar with an external laser light source includes a fiber optic collimating lens, a reflector, a rotating platform, a converging lens and a photoelectric detector; the laser light source is coupled in through the optical fiber, collimated into parallel light by the fiber optic collimating lens, passes through the center of the rotating platform, and then is incident on the reflector above at 45 degrees to the x-axis. The reflector is fixed in a sleeve that penetrates the center of the converging lens. The laser reflected by the reflector is emitted from the center of the converging lens. After the laser is irradiated on the object to be detected, the reflected light of the laser passes through the converging lens and is focused on the photoelectric detector.

[0010] The laser radar with an external light source includes a scanning laser radar and a single-point laser radar.

[0011] The controller controls the output optical power of each port of the adjustable optical beam splitter through the ground electrode and the source electrode, thereby realizing real-time dynamic configuration.

[0012] The present invention has the following beneficial effects:

[0013] 1. The present invention can dynamically adjust the output optical power of each laser through an adjustable optical beam splitter, thereby realizing the adjustment of the detection distance and detection sensitivity of each laser radar in a multi-laser radar system.

[0014] 2. The photoelectric detection module in the present invention is integrated on a laser radar with an external laser light source, thus avoiding the coupling loss of the spatial light knife optical fiber.

[0015] 3. The present invention can provide the laser radar with a light source with more stable power output, more stable wavelength and longer life through an independent laser light source; and the laser radar with an external laser light source and signal processing can reduce the cost of a single laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural block diagram of the multi-laser radar system based on a single laser light source of the present invention.

[0017] Figure 2 This is a structural block diagram of an adjustable optical beam splitter of the present invention.

[0018] Figure 3 This is a laser radar with a rotating external light source according to the present invention.

[0019] Figure 4 This is a laser radar with a non-rotating external light source according to the present invention.

[0020] Figure 5 This is a structural block diagram of another adjustable optical beam splitter of the present invention.

[0021] In the figure: laser light source 1, controller 2, adjustable optical beam splitter 3, laser radar with external light source 4, optical waveguide 5, ground electrode 6, source electrode 7, fiber collimating lens 8, rotating platform 9, photodetector 10, light reflector 11, sleeve 12, and converging lens 13. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Multi-lidar detection system, such as Figure 1 As shown. The light source emitted by the laser light source 1 is coupled to the adjustable optical beam splitter 3 through the optical fiber, and then connected to multiple external light source laser radars 4 through the optical fiber. The reflected light signal detected by it is detected by the built-in photodetector 11 ( Figure 3 、 4 ) and then converted into an electrical signal through the electrical signal transmission line and transmitted to the controller 2. The controller 2 calculates the detection distance of the external laser radar 4 based on the pulse signal to the laser light source 1 and the feedback electrical signal from the external laser radar 4.

[0024] Adjustable beam splitter 3, such as Figure 2 As shown, a cascaded one-to-two Mach-Zehnder interferometer structure based on waveguide 5 can be used. Waveguide 5 can be implemented using a variety of materials, such as silicon dioxide waveguides, silicon waveguides on insulating substrates, indium gallium arsenide waveguides on indium phosphide platforms, and lithium niobate thin film waveguides. By applying different voltages to the metal ground electrode 6 and source electrode 7 on the two arms of the Mach-Zehnder waveguide, the refractive index of the two arms can be adjusted, thereby adjusting the optical power of the two output ports. Figure 2 The figure shows a one-to-four tunable optical beam splitter. The number of output ports can be increased by continuously increasing the number of cascade layers. For example, if one more layer is added, that is, Figure 2A Mach-Zehnder interferometer is added on the lower right side to realize a one-to-five tunable optical beam splitter.

[0025] Figure 2 For this 1×N tunable optical splitter, if the optical power of each port is P1, P2, P3, ..., P i , P i+1 ,…,P N Then for the i-th Mach-Zehnder, the splitting ratio of its two arms is: Pi / (P i+1 +P i+2 +…+P N By analogy, the splitting ratio of each Mach-Zehnder can be calculated. Therefore, different voltages can be applied to the two arms of each Mach-Zehnder to achieve the corresponding splitting ratio, thereby ensuring that the optical power at each port meets the requirements.

[0026] Laser radar 3 with external light source, such as Figure 3 As shown, the laser light source is coupled in via an optical fiber. The optical fiber light is collimated into parallel light by a fiber collimating lens 8, passes through the center of a rotating chassis 9, and then is incident on a reflector 11 positioned 45 degrees above the x-axis. The reflector is fixed in a sleeve 12 that penetrates the center of a converging lens 13. The laser light, reflected by the reflector 11, is emitted from the center of the converging lens 13. After the laser light irradiates the object to be detected, the reflected light passes through the converging lens 13 and is focused onto the photodetector 10. The electrical signal detected by the photodetector is transmitted to the controller 2 for calculating the distance to the detected object.

[0027] The output optical power of each port of the adjustable optical beam splitter is controlled by controller 2 via ground electrode 9 and source electrode 10. The specific distribution of optical power at each output port can be dynamically configured by the user in controller 2. For example, in a scenario involving an unmanned vehicle, when the vehicle is driving forward, most of the laser's optical power can be allocated to the vehicle's forward-facing LiDAR, while a small amount of optical power can be allocated to the rear-facing LiDAR, thereby improving the detection range and sensitivity of the forward-facing LiDAR. When the vehicle is reversing, most of the optical power can be allocated to the rear-facing LiDAR, thereby improving the detection range and sensitivity of the rear-facing LiDAR.

[0028] The laser radar with external light source can be Figure 3 The mid-scan laser radar may also be one without the rotating mechanism 9, such as Figure 4 Single-point laser radar.

[0029] Adjustable beam splitter 3, can also be used Figure 5This is achieved using the waveguide coupler shown. Controller 2 controls the optical power intensity at each output port by adjusting the voltages at ground electrode 6 and source electrode 7 on either side of the waveguide coupler. Cascading waveguide couplers can also implement a 1 / 2-way tunable optical beam splitter. Other types of tunable optical beam splitters are also possible, even ones where the power ratio at each output port can be independently and arbitrarily adjusted (as long as energy conservation is satisfied).

[0030] Controller 2 switches laser light source 1 on and off, recording the time of laser emission. Each external laser radar 4 illuminates the object under test with laser light. The reflected light passes through the internal photodetector 10, is converted into an electrical signal, and fed back to controller 2 along with the current position of the laser radar. Based on the time difference between the emitted and reflected laser light, controller 2 calculates the distance between each laser radar 4 and the object under test.

[0031] The embodiments described above may be further combined or replaced, and the embodiments are merely descriptions of preferred embodiments of the present invention and do not limit the concept and scope of the present invention. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention are within the scope of protection of the present invention. The scope of protection of the present invention is given by the appended claims and any equivalents thereof.

Claims

1. A multi-laser radar detection system based on a single laser light source, characterized in that: It includes a laser light source, an adjustable optical beam splitter, an external light source laser radar, and a controller; the light emitted by the laser light source is coupled to the adjustable optical beam splitter or waveguide coupler through an optical fiber, and then connected to multiple external light source laser radars through optical fibers. The external light source laser radar is equipped with a photodetector, which converts the detected reflected light signal into an electrical signal and feeds it back to the controller through an electrical signal transmission line; the controller obtains the detection result based on the pulse signal of the laser light source and the feedback electrical signal of the external light source laser radar; The adjustable optical beam splitter adopts a cascaded one-to-two Mach-Zehnder interference structure based on waveguides. By applying different voltages to the metal ground electrode and source electrode on the two arms of the Mach-Zehnder waveguide, the refractive index of the two arms is adjusted, thereby adjusting the optical power of the two output ports. By continuously increasing the number of cascade layers, the number of output ports can be increased. The adjustable optical beam splitter is a 1×N adjustable optical beam splitter, and the optical power of each port is P1, P2, P3, ..., P i , P i+1 ,…,P N , where the splitting ratio of the two arms of the i-th Mach-Zehnder is: Pi / (P i+1 +P i+2 +…+P N ); Apply different voltages to each Mach-Zehnder arm to achieve the corresponding splitting ratio, so that the optical power of each port meets the requirements; The external light source laser radar includes a fiber optic collimating lens, a reflector, a rotating platform, a converging lens and a photoelectric detector; The laser light source is coupled in through the optical fiber, collimated into parallel light by the optical fiber collimating lens, passes through the center of the rotating platform, and then enters the reflector above at a 45-degree angle to the x-axis. The reflector is fixed in a sleeve that penetrates the center of the converging lens. The laser light reflected by the reflector is emitted from the center of the converging lens. After the laser hits the object to be detected, the reflected light of the laser passes through the converging lens and is focused onto the photodetector. The controller controls the output optical power of each port of the adjustable optical beam splitter through the ground electrode and the source electrode, thereby realizing real-time dynamic configuration; The multi-lidar detection system based on a single laser light source is applied to an unmanned vehicle. When the unmanned vehicle is driving forward, most of the optical power of the laser light source is allocated to the external light source lidar facing forward, and a small part of the optical power is allocated to the external light source lidar facing backward, thereby improving the detection distance and sensitivity of the forward lidar; when the unmanned vehicle is reversing, most of the optical power is allocated to the external light source lidar facing backward, thereby improving the detection distance and sensitivity of the external light source lidar facing backward.

2. The multi-laser radar detection system based on a single laser light source according to claim 1, characterized in that: The external light source laser radar includes a scanning type laser radar and a single-point laser radar.

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