Laser radar system with polarization device

Abstract

A laser radar system with a polarization device is characterized by comprising an emitter and a receiver, the emitter is used for emitting polarized laser; and the receiver is used for receiving a specific reflection signal of the polarized laser. According to the utility model, the signal-to-noise ratio of a received signal of the laser radar in an outdoor sun illumination environment is effectively improved, and the measurable distance is increased under the condition that the light source power and the calculation precision are kept unchanged.

Description

Technical Field

[0001] The utility model relates to the technical field of lidar, and specifically, to a lidar system with a polarization device. Background Art

[0002] A lidar is a radar system that detects the position, speed and other characteristic quantities of a target by emitting laser beams. Its working principle is to emit a detection signal (laser beam) to the target, and then compare the received signal (target echo) reflected from the target with the emitted signal. After appropriate processing, relevant information about the target can be obtained, such as parameters of the target distance, azimuth, altitude, speed, attitude, shape, etc. Obtaining high-precision data from a moving platform through lidar has been widely used in the field of autonomous driving.

[0003] Most of the usage scenarios of lidar systems applied to the field of autonomous driving are located outdoors. A part of the near-infrared band in sunlight overlaps with the wavelength of the light source of the lidar. Therefore, in addition to receiving the signal emitted by the laser light source and reflected by an object, the receiving sensor will also receive the light emitted by sunlight and reflected and scattered by an object. Compared with the light emitted by the lidar light source, the light emitted by sunlight and reflected and scattered by an object and reaching the sensor is noise, and the noise affects the working distance and calculation accuracy of the lidar. When the noise becomes larger, the signal-to-noise ratio of the signal becomes smaller, the calculation accuracy becomes worse, and the measurable distance corresponding to the lidar becomes smaller.

[0004] The disclosure of the above background art content is only used to assist in understanding the inventive concept and technical solution of the utility model, and it does not necessarily belong to the prior art of this patent application. Without clear evidence indicating that the above content was publicly available on the filing date of this patent application, the above background art should not be used to evaluate the novelty and inventiveness of this application. Summary of the Utility Model

[0005] Therefore, the utility model proposes a lidar system with a polarization device, which uses a laser with polarization characteristics as the emission light source, and cooperates with a receiving end with a polarization device to form a lidar system, effectively improving the signal-to-noise ratio of the received signal of the lidar in an outdoor sunlight environment, and increasing the measurable distance while keeping the light source power and calculation accuracy unchanged.

[0006] The utility model provides a lidar system with a polarization device, which is characterized by comprising: a transmitter and a receiver;

[0007] The transmitter is used for emitting polarized laser;

[0008] The receiver is used for receiving a specific reflection signal of the polarized laser.

[0009] Optionally, in the lidar system with a polarization device, the transmitter includes:

[0010] A light source for emitting laser light;

[0011] A first polarizer located on the optical path of the light source;

[0012] A random phase plate located between the light source and the first polarizer;

[0013] A reflecting mirror on the same side of the first polarizer as the light source for reflecting the laser light.

[0014] Optionally, in the lidar system with a polarization device, the first polarizer is connected to the reflecting mirror to reflect more laser light.

[0015] Optionally, in the lidar system with a polarization device, the transmitter further includes: a transmitting lens for projecting the laser light.

[0016] Optionally, in the lidar system with a polarization device, the transmitter further includes:

[0017] A first quarter-wave plate located on the optical path of the laser light for changing the polarization state of the laser light;

[0018] A transmitting lens for projecting the laser light; the laser light passes through the first polarizer and the first quarter-wave plate in sequence and then is projected by the transmitting lens.

[0019] Optionally, in the lidar system with a polarization device, the receiver includes:

[0020] A second polarizer for filtering the reflected signal;

[0021] A sensor for receiving the filtered reflected signal.

[0022] Optionally, in the lidar system with a polarization device, the receiver further includes:

[0023] A second quarter-wave plate located on the optical path of the reflected signal for changing the polarization state of the reflected signal.

[0024] Optionally, in the lidar system with a polarization device, the second polarizer is located between the second quarter-wave plate and the sensor.

[0025] Optionally, in the lidar system with a polarization device, it is characterized in that the polarization state of the polarized laser is the same as or perpendicular to the polarization state of the specific reflection signal.

[0026] Optionally, in the lidar system with a polarization device, it is characterized in that the number of the receivers is twice the number of the transmitters.

[0027] Compared with the prior art, the present utility model has the following beneficial effects:

[0028] The present utility model uses a laser with polarization characteristics as the emission light source, and is combined with a receiving end with a polarization device to form a lidar system, effectively improving the signal-to-noise ratio of the received signal of the lidar in the outdoor sunlight environment, increasing the measurable distance while keeping the light source power and calculation accuracy unchanged, and can be applied to vehicles, service robots, drones and other fields related to the field of autonomous driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings. By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present utility model will become more obvious:

[0030] Figure 1 It is a schematic structural diagram of a lidar system with a polarization device in an embodiment of the present utility model;

[0031] Figure 2 It is a schematic structural diagram of a transmitter in an embodiment of the present utility model;

[0032] Figure 3 It is a schematic structural diagram of another transmitter in an embodiment of the present utility model;

[0033] Figure 4 It is a schematic structural diagram of a receiver in an embodiment of the present utility model;

[0034] Figure 5 It is a schematic structural diagram of another receiver in an embodiment of the present utility model.

[0035] 1 - Transmitter;

[0036] 2 - Receiver;

[0037] 3 - Light source;

[0038] 4 - First polarizer;

[0039] 5 - Random phase plate;

[0040] 6 - Reflective mirror;

[0041] 7 - Emission lens;

[0042] 8 - First quarter - wave plate;

[0043] 9 - Second polarizer;

[0044] 10 - Sensor;

[0045] 11 - Second quarter - wave plate; Detailed implementation manners

[0046] The following will describe the present utility model in detail with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present utility model, but do not limit the present utility model in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made. These all belong to the protection scope of the present utility model.

[0047] The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and above - mentioned drawings of the present utility model are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances, so that the embodiments of the present utility model described here, for example, can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0048] A lidar system with polarization devices provided by an embodiment of the present utility model aims to solve the problems existing in the prior art.

[0049] The following will describe in detail the technical solutions of the present utility model and how the technical solutions of the present application solve the above - mentioned technical problems with specific embodiments. These several specific embodiments below can be combined with each other, and for the same or similar concepts or processes, they may not be repeated in some embodiments. The following will describe the embodiments of the present utility model with reference to the drawings.

[0050] The lidar system described in this utility model includes a transmitter and a receiver. The transmitter emits light with significant polarization characteristics. This polarization characteristic can be inherent in the laser light source itself, or a set of polarization devices can be added to a laser light source without polarization characteristics to endow it with polarization characteristics. The receiver includes a receiving sensor and a set of polarization devices. The polarization device is located outside the receiving sensor. Before the optical signal enters the receiving sensor, it passes through the polarization device, and only signals that conform to specific polarization characteristics can enter the receiving sensor.

[0051] The transmitter emits light with polarization characteristics, including but not limited to linear polarization and circular polarization. When the laser light source in the transmitter itself has polarization characteristics, its polarization characteristics can be maintained without adding additional polarization devices, or additional polarization devices can be added to change its polarization characteristics. When the laser light source does not have polarization characteristics, a set of polarization devices can be added at the output end of the laser light source so that the laser emitted by the transmitter has polarization characteristics.

[0052] When the laser light source does not have polarization characteristics, by adding a polarizer with a specific polarization direction, the laser emitted by the transmitter can have polarization in a specific direction, that is, linear polarization characteristics, and the polarization device is a polarizer; or by adding a polarizer and a quarter-wave plate, the laser initially emitted by the transmitter can have circular polarization characteristics, and the polarization device is a polarizer and a quarter-wave plate. When the light emitted by the laser light source has linear polarization characteristics, a quarter-wave plate can be added to make the output light source have circular polarization characteristics, and the polarization device is a quarter-wave plate.

[0053] The receiver receives the optical signal returned from the light source emitted by the object to be measured, and sets the polarization device added in front of the sensor according to the polarization characteristics of the light emitted by the transmitter. If the light emitted by the transmitting device is linearly polarized light, the polarization device is a polarizer with a specific polarization direction. If the light emitted by the transmitting device is circularly polarized light, the polarization device is a quarter-wave plate and a polarizer.

[0054] When the lidar system is used outdoors, especially in a sunlight environment, ambient light or sunlight emission, reflection, and scattering by objects will enter the receiving sensor of the lidar system. All the light that does not enter the receiving sensor after being reflected by the object from the lidar light source will become noise outside the required detection signal. Most of the light in the environment is unpolarized light. When the ambient light enters the lidar receiving device, part of the energy will be filtered out through the polarization device, and the signal-to-noise ratio of the light reflected back by the object from the emitted laser light source will increase. Then, when the light source power and signal-to-noise ratio remain unchanged, the measurable distance will increase accordingly.

[0055] The following calculates the signal-to-noise ratio of the received signal before and after adding a polarization device at the receiver. The laser emitted by the transmitter of the lidar system measures an object at a distance d. The signal intensity returned to the receiving device of the lidar system is S, and the noise signal reaching the receiving device is N. When there is no polarization device at the receiver, the signal intensity received by the receiving sensor is S, and the noise intensity received by the receiving sensor is N. Then the signal-to-noise ratio of the returned signal is

[0056] SNR = S / N (1)

[0057] When measuring the object at the same distance d, when the receiver is equipped with a polarization device, the characteristics of the polarization device are determined by the polarization characteristics of the lidar light source that emits and returns. The signal returned by the transmitted light source through the measured object passes through the polarization device with almost no loss. Since the composition of the ambient light is mainly non-polarized light, the remaining energy of the non-polarized light after passing through the polarization device can be calculated as one-half. It can be calculated that the signal intensity received by the receiving sensor is S, and the noise intensity received by the receiving sensor is N / 2. Then the signal-to-noise ratio of the returned signal is

[0058] SNR' = S / (N / 2) = 2 * S / N (2)

[0059] SNR' = 2 * SNR (3)

[0060] It can be seen from (3) that without considering the loss of the returned signal through the polarization device, the signal-to-noise ratio of the received signal of the lidar system receiver with the polarization device added when measuring an object at the same distance is twice that without the addition. Considering changing the measured object distance of the lidar system with the receiving sensing device added with a polarization device to d1, so that the signal-to-noise ratio of the received signal of the receiving sensor is the same as that of the receiving sensor without the polarization device added when measuring the distance d, then there is

[0061] S1 = S * (d / d1) 4 (4)

[0062] SNR1 = S1 / (N / 2) (5)

[0063] SNR1 = SNR (6)

[0064] Taking (1) to (6) into comprehensive consideration, we get

[0065] d1 ≈ 1.189 * d (7)

[0066] It can be obtained from (7) that when keeping the signal-to-noise ratio of the lidar receiving sensor the same, the system measurement object distance can be increased by about 18.9% after adding the polarization device to the receiving device compared with without adding the polarization device.

[0067] The following further describes the present utility model in conjunction with the accompanying drawings.

[0068] Figure 1 This is a schematic structural diagram of a lidar system with a polarization device in an embodiment of the present invention. As Figure 1 shown, a lidar system with a polarization device in an embodiment of the present invention includes:

[0069] The transmitter 1 is used to emit polarized laser light.

[0070] Specifically, the main function of the transmitter 1 is to emit polarized laser light. Compared with ordinary laser light, polarized laser light has a specific vibration direction, which enables it to produce unique reflection characteristics when interacting with the target object. The transmitter emits a laser beam with specific polarization characteristics by precisely controlling the polarization state of the laser, and these laser beams are then directed to the target area.

[0071] In some embodiments, the transmitter 1 is composed of a pump source, a gain medium, and a resonator. Among them, the pump source is the core part of the laser, responsible for providing energy to excite the gain medium to emit light. The gain medium is located inside the laser, which may be a gas mixture, a solid crystal rod, or a glass fiber, etc. It contains atoms that can convert the energy of the excitation light into laser light. The excited medium is located between the mirrors at both ends of the resonator, and one of the mirrors is a semi-transparent and semi-reflective mirror, enabling a specific radiation light to form a laser beam and emit out.

[0072] The receiver 2 is used to receive the specific reflection signal of the polarized laser light.

[0073] Specifically, the receiver 2 is an important component responsible for receiving the polarized laser reflection signal. When the emitted polarized laser light encounters the target object, part of the laser light will be reflected back to form a reflection signal. The information about the target object, such as distance, shape, material, etc., is carried in these reflection signals. The receiver can filter out the reflection signals that match the polarization state of the emitted laser light through specific polarization devices, thereby achieving precise detection and identification of the target object.

[0074] In some embodiments, the detector in the receiver works based on the photoelectric effect, converting the received optical signal into an electrical signal. In vehicle-mounted lidar, semiconductor detectors such as PIN-PD and APD are common choices. The PIN-PD has a simple structure and a fast response speed, but its sensitivity is limited; while the APD can trigger an avalanche effect through a reverse voltage, thereby multiplying the current and improving the sensitivity.

[0075] This lidar system with polarization devices has many advantages. First, due to the characteristics of polarized laser, the system can more accurately identify target objects in complex environments, reducing the possibility of false alarms and missed detections. Second, by analyzing the polarization state of the reflected signal, the system can also obtain more information about the target object, further improving the detection accuracy and reliability. In addition, this system also has high anti-interference ability and can work stably in various harsh environments.

[0076] In practical applications, this lidar system with polarization devices can be widely used in fields such as autonomous driving, robot navigation, and security monitoring. For example, in autonomous vehicles, the system can use polarized lidar to accurately sense the surrounding environment and achieve safe and reliable autonomous driving functions. In terms of robot navigation, the system can help robots more accurately identify obstacles and paths and achieve autonomous navigation and obstacle avoidance functions. In the field of security monitoring, the system can be used to achieve precise identification and tracking of specific targets, improving the efficiency and accuracy of monitoring.

[0077] In some embodiments, the polarization state of the polarized laser is the same as or perpendicular to the polarization state of the specific reflected signal. When the polarization state of the polarized laser is the same as the polarization state of the specific reflected signal, it can better filter out the influence of stray light, thereby greatly improving the signal-to-noise ratio and making the data quality higher.

[0078] In some embodiments, the number of receivers is twice the number of transmitters. For example, if the number of transmitters is 1 and the number of receivers is 2. Then the two receivers have two different working modes to obtain different data. In the first working mode, the two receivers are exposed simultaneously for information acquisition. At this time, the information obtained by the two receivers is the same, so the two receivers can form a binocular system, and the depth map can be calculated using the parallax principle. By fusing the depth map with the TOF depth received by the receiver, more accurate depth data can be obtained, or different data can be used at different detection distances based on the different measurement ranges of binocular and TOF technologies, thereby increasing the measurement range of the lidar system. In the second working mode, the two receivers are exposed with a certain time delay, so that the signals received by different receivers are different, which can be used to detect target objects at different distances and improve the data accuracy of the target object.

[0079] Figure 2 This is a schematic structural diagram of a transmitter in an embodiment of the present invention. As Figure 2 shown, a transmitter in an embodiment of the present invention includes:

[0080] A light source 3 for emitting laser light.

[0081] Specifically, the light source 1 is the core part of the polarization projector, responsible for emitting laser light, that is, light without a specific polarization direction. The laser light can be light rays in any wavelength band such as visible light, infrared light, ultraviolet light, etc.

[0082] The first polarizing plate 4 is located on the optical path of the light source.

[0083] Specifically, the first polarizing plate 4 is located on the optical path of the light source 3. Its function is to obtain linearly polarized light from the laser light. The first polarizing plate is usually composed of multiple layers of thin films, which contain materials that can absorb or reflect light with a specific polarization direction. The number of the first polarizing plates is one. In some embodiments, the first polarizing plate has only one transmission axis direction, and only the light waves vibrating along this direction can pass through. In some embodiments, the first polarizing plate has at least two transmission axis directions, and the polarization directions of the light rays emitted from different regions of the first polarizing plate are different. The polarization directions of different regions on the first polarizing plate can be perpendicular or at an angle of 45 degrees, 30 degrees, 15 degrees or any other arbitrary angle.

[0084] The random phase plate 5 is located between the light source and the first polarizing plate.

[0085] Specifically, a random phase plate (Random Phase Plate, RPP) is an optical element used to introduce random phase changes on the wavefront of a light beam. The surface of the random phase plate has an irregular structure, and these structures introduce random phase delays on the passing light beam. This phase delay causes the wavefront of the light beam to be distorted, thereby changing the propagation characteristics and focusing performance of the light beam. The design and manufacture of the random phase plate require precise control of its surface microstructure to ensure that the desired phase changes can be accurately introduced into the light beam.

[0086] The reflecting mirror 6 is on the same side of the first polarizing plate as the light source, and is used to reflect the laser light.

[0087] Specifically, the reflecting mirror 6 can change the direction of the light rays so that they propagate along the desired path. The reflecting mirror is used to reflect the laser light from the light source, enabling the light rays to be reflected and transmitted multiple times inside the polarization projector. Since the reflecting mirror usually has a high reflectivity, it can maximize the retention of the energy of the light rays. The reflecting mirror and the light source are on the same side of the first polarizing plate, and can reflect the laser light emitted by the light source back to the first polarizing plate and the random phase plate. After multiple reflections and polarization processes, ultimately more polarized light beams are emitted, improving the light output rate, and the light output rate can reach more than 90%.

[0088] In some embodiments, the reflecting mirror surface wraps the side of the first polarizer facing the light source. The reflecting mirror surface wraps the side of the first polarizer facing the light source, so that all the light rays on the light source side can only irradiate on the reflecting mirror surface, the light source and the first polarizer, thereby maximizing the reflection of the light rays. The reflecting mirror surface is arc-shaped, so that the laser irradiates on the first polarizer with the least number of reflections, thereby reducing light loss and improving the light output efficiency.

[0089] In some embodiments, the first polarizer completely covers the light path of the light source. The size of the first polarizer is large enough so that the laser light emitted from the light source irradiates directly on the first polarizer without reflection, thereby making the emitted laser light more uniform. Since the emission ratio is the highest when irradiating on the first polarizer for the first time, the uniformity of the laser light can be guaranteed in this embodiment.

[0090] In some embodiments, the first polarizer is connected to the reflecting mirror surface to reflect more laser light.

[0091] In some embodiments, the transmitter further includes:

[0092] An emission lens 7 for projecting the laser light.

[0093] Specifically, as a part of the transmitter, the function of the emission lens is to focus and project the modulated laser beam onto an external target. In this process, the design and quality of the emission lens directly affect the ranging accuracy and resolution of the lidar.

[0094] The emission lens is an important component of the transmitter. It is located behind the laser light source and the reflecting mirror surface and is adjacent to the first polarizer. Its main function is to focus and collimate the laser beam that has undergone polarization and phase modulation to ensure that the laser can be projected onto the target object with a certain beam divergence angle and energy density.

[0095] Through its optical design, the emission lens can precisely control and adjust the laser beam. It can focus the laser beam from a wider divergent state into a narrow beam, improving the energy density and penetration power of the laser. At the same time, the emission lens can also collimate the laser beam so that it is projected with more parallel light rays, reducing the diffusion and distortion of the beam during propagation.

[0096] The selection and design of the emission lens are crucial for the performance of the lidar system. Different application scenarios and detection requirements may require emission lenses with different focal lengths and different apertures. Therefore, in practical applications, it is necessary to select a suitable emission lens according to factors such as specific detection targets, detection distances, and environmental conditions, and perform precise installation and debugging to ensure that the laser beam can be accurately and efficiently projected onto the target object.

[0097] Figure 3 This is a schematic structural diagram of another transmitter in the embodiments of the present utility model. As Figure 3 shown, compared with the foregoing embodiments, another transmitter in the embodiments of the present utility model further includes:

[0098] A first quarter-wave plate 8, located on the optical path of the laser, for changing the polarization state of the laser.

[0099] Specifically, the first quarter-wave plate is located on the optical path of the laser and is an indispensable component in the transmitter. Its main function is to change the polarization state of the laser. By adjusting the angle when the laser passes through the first quarter-wave plate or the characteristics of the wave plate, the laser originally linearly polarized can be converted into elliptically polarized or circularly polarized, and even the polarization direction may be changed. This change in the polarization state helps to enhance the interaction between the laser and the target object, improve the intensity and stability of the reflected signal, and thus optimize the detection performance of the radar system.

[0100] A transmitting lens 7, for projecting the laser; the laser sequentially passes through the first polarizer and the first quarter-wave plate and then is projected by the transmitting lens.

[0101] After the laser beam passes through the first quarter-wave plate, it will encounter the transmitting lens. The transmitting lens is another core component of the transmitter, and its main function is to focus and project the laser beam. Through optical design and adjustment, the transmitting lens can ensure that the laser beam is projected onto the target object with a specific beam divergence angle and energy distribution. In this way, the laser beam can irradiate the target area more precisely, improving the accuracy and efficiency of detection.

[0102] In this process, the laser first passes through the screening of the first polarizer to ensure that only the laser with a specific polarization direction can pass. Then, it passes through the modulation of the random phase plate to increase the anti-interference ability of the laser. Next, the first quarter-wave plate further changes the polarization state of the laser to adapt to different detection requirements. Finally, the transmitting lens projects the processed laser beam to achieve the detection and measurement of the target object.

[0103] Figure 4 This is a schematic structural diagram of a receiver in the embodiments of the present utility model. As Figure 4 shown, a receiver in the embodiments of the present utility model includes:

[0104] A second polarizer 9, for filtering the reflected signal.

[0105] Specifically, the second polarizer is one of the key components in the receiver. It is located on the receiving optical path and its main function is to filter the reflected signal. Since the reflected signal after the interaction between the laser and the target object may contain light waves of various polarization states, and not all light waves carry useful information about the target object. Therefore, by setting a second polarizer that matches the transmitter, the receiver can selectively allow the reflected signal of a specific polarization state to pass through while blocking light waves of other polarization states. In this way, the receiver can effectively filter out interference signals, improve the signal-to-noise ratio of the received reflected signal, and thus enhance the detection performance of the system.

[0106] A sensor 10 for receiving the filtered reflected signal.

[0107] Specifically, the sensor is another core component of the receiver. It is responsible for receiving the reflected signal filtered by the second polarizer. The sensor usually uses a high-sensitivity photodetector, which can convert the optical signal into an electrical signal for subsequent processing and analysis. The performance of the sensor directly affects the receiving ability and accuracy of the receiver for the reflected signal. Therefore, in practical applications, it is necessary to select a suitable sensor type according to specific detection requirements and environmental conditions, and perform precise calibration and debugging to ensure that the receiver can accurately receive the reflected signal.

[0108] Figure 5 This is a schematic structural diagram of another receiver in the embodiment of the present invention. As Figure 5 shown, compared with the previous embodiment, another receiver in the embodiment of the present invention further includes:

[0109] A second quarter-wave plate 11, located on the optical path of the reflected signal, for changing the polarization state of the reflected signal.

[0110] Specifically, the second quarter-wave plate is placed on the optical path of the reflected signal, and its main function is to change the polarization state of the reflected signal. Similar to the first quarter-wave plate in the transmitter, the second quarter-wave plate adjusts the polarization state of the passing reflected signal through its specific optical properties. The second quarter-wave plate is located on the optical path of the reflected signal, and it changes the polarization state of the reflected signal by introducing a fixed phase difference (usually π / 2). This change helps to further analyze the reflected signal, so as to extract more information about the target object.

[0111] This change in polarization state has several key benefits. First, it helps to further enhance the sensitivity of the receiver to reflected signals of a specific polarization state, thereby filtering out more interference signals and improving the signal-to-noise ratio. Second, by adjusting the polarization state of the reflected signal, the second quarter-wave plate can help the receiver better match the polarization state of the transmitter, thus optimizing the performance of the entire system. Finally, for some complex targets or environments, changing the polarization state of the reflected signal may help to reveal more target features or environmental information.

[0112] In practical applications, the selection and design of the second quarter-wave plate need to be based on specific detection requirements and environmental conditions. For example, factors such as the reflection characteristics of the target object, the interference of ambient light, and the sensitivity of the receiver need to be considered. By precisely controlling and adjusting the parameters of the second quarter-wave plate, an accurate change in the polarization state of the reflected signal can be achieved, thereby optimizing the performance of the receiver.

[0113] In some embodiments, the second polarizer is located between the second quarter-wave plate and the sensor. The combination of the second quarter-wave plate and the second polarizer can change the polarization state of the information received by the receiver, thereby changing the received information, which is beneficial to improving the signal-to-noise ratio and is beneficial to changing the information content.

[0114] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0115] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A laser radar system with a polarization device, characterized in that: include: Transmitters and receivers; The transmitter is used to emit polarized laser light; The receiver is used to receive a specific reflected signal of the polarized laser; The transmitter comprises: A light source for emitting laser light; A first polarizer, located on the light path of the light source; A random phase plate, located between the light source and the first polarizer; A reflective mirror surface, located on the same side of the first polarizer as the light source, for reflecting the laser; The polarization state of the polarized laser light is the same as or perpendicular to the polarization state of the specific reflected signal.

2. A laser radar system with a polarization device according to claim 1, characterized in that: The first polarizer is connected to the reflective mirror to reflect more laser light.

3. A laser radar system with a polarization device according to claim 1, characterized in that: The transmitter also includes a transmitting lens for projecting the laser.

4. A laser radar system with a polarization device according to claim 1, characterized in that: The transmitter also includes: A first quarter wave plate, located on the optical path of the laser, and used to change the polarization state of the laser; An emitting lens is used to project the laser; the laser passes through the first polarizer and the first quarter-wave plate in sequence and is then projected through the emitting lens.

5. The laser radar system with a polarization device according to claim 1, characterized in that: The receiver includes: A second polarizer, used for filtering the reflected signal; The sensor is used to receive the filtered reflection signal.

6. A laser radar system with a polarization device according to claim 5, characterized in that: The receiver also includes: The second quarter wave plate is located on the optical path of the reflected signal and is used to change the polarization state of the reflected signal.

7. A laser radar system with a polarization device according to claim 6, characterized in that: The second polarizer is located between the second quarter wave plate and the sensor.

8. The laser radar system with a polarization device according to claim 1, characterized in that: The number of the receivers is twice the number of the transmitters.

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