Optical scanning system, lidar and vehicle

Abstract

The application provides an optical scanning system, which comprises a polarization converter, a polarization beam splitter, a phase delay element and a scanning element. The polarization converter receives first light with a first polarization state and second light with a second polarization state, and is configured to convert the polarization state of the first light into the second polarization state and to emit the first light and the second light together as third light with the second polarization state. The polarization beam splitter receives and reflects the third light. The phase delay element is configured to receive the third light and emit fourth light with a third polarization state. The scanning element is configured to receive the fourth light and emit fifth light with a fourth polarization state towards the phase delay element, and is further configured to change the emission angle of the fifth light. The fifth light emitted from the scanning element is converted into scanning light with the first polarization state by the phase delay element, and the polarization beam splitter is configured to transmit and emit the scanning light. The application further provides a laser radar using the optical scanning system and a vehicle.

Description

Technical Field

[0001] This application relates to the field of autonomous driving, and more particularly to an optical scanning system, a lidar, and a vehicle. Background Technology

[0002] LiDAR has broad application prospects in remote sensing and autonomous driving. LiDAR, in terms of its components, includes a transmitting system, a scanning system, a receiving system, and a processing system. The scanning system includes scanning elements. The laser beam is emitted from the transmitting system into free space, and the scanning elements adjust the direction of the laser beam's emission into free space. Current technology typically uses a conventional beam splitter in the scanning system to ensure that the incident light and the emitted scanning light are on the same optical axis. A conventional beam splitter has a reflectivity and transmittance of 50% for unpolarized light, so each time the light passes through the beam splitter, it incurs a 50% energy loss (50% transmission, 50% reflection). The light emitted from the transmitting system needs to pass through the conventional beam splitter twice, each time incurring a 50% energy loss. This means that the light suffers a total energy loss of 75% in two passes through the beam splitter, thus reducing the luminous efficiency of the emitted light. Summary of the Invention

[0003] The first aspect of this application provides an optical scanning system, comprising: A polarizer receives a first light having a first polarization state and a second light having a second polarization state, the first polarization state being different from the second polarization state. The polarizer is used to convert the polarization state of the first light to the second polarization state and emit it together with the second light as a third light having the second polarization state. A polarizing beam splitter receives and reflects the third light; A phase delay element, located on the reflecting side of the polarizing beam splitter, is used to receive the third light and emit a fourth light with a third polarization state, the third polarization state being different from the first polarization state and the second polarization state; A scanning element is used to receive the fourth light and emit a fifth light with a fourth polarization state toward the phase delay element, the fourth polarization state being different from the first polarization state and the second polarization state. The scanning element is also used to change the emission angle of the fifth light. The fifth light emitted from the scanning element is converted into scanning light with a first polarization state by the phase delay element, and the polarization beam splitter located on the light-emitting side of the phase delay element is used to transmit and emit the scanning light.

[0004] The optical scanning system provided in this application uses a polarizer to obtain light with a specific polarization state. Light with a specific polarization state can be transmitted or reflected from a polarizing beam splitter, which avoids the problem of low reflectivity and transmittance of polarizing beam splitters for unpolarized light. This helps to reduce light loss in the optical scanning system, improve light utilization, and enhance the scanning performance of the optical scanning system.

[0005] In one embodiment, the polarizer includes a half-wave plate and a polarizing dielectric film. The polarizing dielectric film reflects the second light and transmits the first light. The second light is emitted after reflection. The half-wave plate is used to receive the first light transmitted from the polarizing dielectric film and convert the polarization state of the first light into the second polarization state before emitting it.

[0006] In one embodiment, the optical scanning system further includes a collimating lens disposed on the light-emitting side of the light source for receiving and collimating the first light and the second light emitted from the light source.

[0007] In one embodiment, the optical scanning system further includes a focusing lens disposed on the light-emitting side of the polarizer, for receiving the third light emitted from the polarizer and focusing the third light onto the polarizing beam splitter.

[0008] In one embodiment, the scanning element is any one of a micromirror, an optical phased array chip, or a digital micromirror device.

[0009] In one embodiment, the third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

[0010] In one embodiment, the first polarization state is a horizontal polarization state, the second polarization state is a vertical polarization state, the third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

[0011] In one embodiment, the first polarization state is a vertical polarization state, the second polarization state is a horizontal polarization state, the third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

[0012] A second aspect of this application provides a lidar, comprising: A laser emitting system for emitting a laser, the laser comprising a first light having a first polarization state and a second light having a second polarization state; The optical scanning system described in any of the above embodiments is used to receive the first light and the second light, and convert the first light and the second light into scanning light and emit it to the target to be tested; A laser receiving system is used to receive the reflected light from the target under test and obtain information about the target under test based on the reflected light.

[0013] The lidar provided in this application embodiment, by employing the optical scanning system as described in the first aspect, helps to reduce light loss in the lidar, improves light utilization, and enables the lidar to effectively emit the first light to the target to be measured, thereby improving the overall detection performance of the lidar.

[0014] A third aspect of this application provides a vehicle, comprising: The subject; and The lidar described in any of the above embodiments is mounted on the main body.

[0015] The vehicle provided in this application embodiment has the lidar described in the second aspect, and therefore also has the same beneficial effects, which will not be elaborated here. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an optical scanning system according to an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the structure of a polarizer according to an embodiment of this application.

[0018] Figure 3 This is a schematic diagram of the structure of a polarizer according to other embodiments of this application.

[0019] Figure 4 This is a schematic diagram of the structure of a lidar according to an embodiment of this application.

[0020] Figure 5 This is a schematic diagram of a lidar module according to an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of a vehicle module according to an embodiment of this application.

[0022] Explanation of key component symbols: Optical scanning system 100 Polarizer 1 Sub-polarizing prism 10 Half-wave plate 11 Polarizing dielectric film 13 Polarizing beam splitter 2 Right-angle prism 20 Polarizing spectral splitting dielectric film 21 Phase delay element 3 Scanning element 4 Collimating lens 5 Focusing lens 6 LiDAR 300 Laser Emission System 301 Laser receiving system 303 Light-collecting lens 303a Light sensor 303b Transimpedance amplifier 303c Analog-to-digital converter 303d Target to be tested 303e Vehicle 400 Ontology 401 First Light L1 Second Light L2 Third Light L3 Fourth Light L4 Fifth Light L5 Scanning Light LS Backhaul L6 The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0025] To further illustrate the technical means and effects adopted by this application in achieving its intended purpose, the following detailed description of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0026] Please refer to the following: Figure 1 and Figure 2The optical scanning system 100 of this application embodiment includes a polarizer 1, a polarizing beam splitter 2, a phase retardation element 3, and a scanning element 4. The polarizer 1 receives a first light L1 having a first polarization state and a second light L2 having a second polarization state, the first polarization state being different from the second polarization state. The polarizer 1 converts the polarization state of the first light L1 to the second polarization state, and together with the second light L2, emits it as a third light L3 having the second polarization state. The polarizing beam splitter 2 receives and reflects the third light L3. The phase retardation element 3 is located on the reflecting side of the polarizing beam splitter 2, and receives the third light L3 and emits a fourth light L4 having the third polarization state, different from the first and second polarization states. The scanning element 4 receives the fourth light L4 and emits a fifth light L5 having the fourth polarization state towards the phase retardation element 3, the fourth polarization state being different from the first and second polarization states. The scanning element 4 also changes the emission angle of the fifth light L5. The fifth light L5 emitted from the scanning element 4 is converted into scanning light LS with a first polarization state by the phase delay element 3. The polarization beam splitter 2 located on the light-emitting side of the phase delay element 3 is used to transmit and emit the scanning light LS.

[0027] The optical scanning system 100 provided in this application embodiment obtains light with a specific polarization state by using a polarizer 1. Light with a specific polarization state can be transmitted or reflected from a polarizing beam splitter 2, which avoids the problem that the polarizing beam splitter 2 has low reflectivity and transmittance for unpolarized light. This helps to reduce light loss in the optical scanning system 100, improves light utilization, and enhances the scanning performance of the optical scanning system 100.

[0028] Please refer to the following: Figure 1 and Figure 2 The polarizer 1 includes multiple sub-polarizing prisms 10, multiple half-wave plates 11, and a polarizing dielectric film 13. The multiple sub-polarizing prisms 10 are bonded together by a material, and the polarizing dielectric film 13 is disposed at the junction of two adjacent sub-polarizing prisms 10. The material can be glass glue or water-soluble adhesive, and this application is not limited thereto. Each half-wave plate 11 is spaced apart on the light-emitting side surface of the polarizer 1. The half-wave plates 11 can be bonded to the light-emitting side surface of the polarizer 1 using glass glue or water-soluble adhesive. When the polarizer 1 receives a first light L1 and a second light L2, the polarizing dielectric film 13 transmits the first light L1 and reflects the second light L2. The second light L2 reflected from the polarizing dielectric film 13 exits from the sub-polarizing prisms 10. The first light L1 transmitted from the polarizing dielectric film 13 is incident on the half-wave plate 11. The half-wave plate 11 is used to receive the first light L1 transmitted from the polarizing dielectric film 13 and convert the polarization state of the first light L1 into a second polarization state before it is emitted.

[0029] In this embodiment, if the first light L1 is horizontally linearly polarized light with a horizontal polarization state, then the second light L2 is vertically linearly polarized light with a vertical polarization state. When both horizontally and vertically polarized light are incident on the polarizer 1, the vertically polarized light is reflected directly from the sub-polarizing prism 10 after reflection by the polarizing dielectric film 13. The horizontally polarized light is transmitted from the polarizing dielectric film 13 to the half-wave plate 11, which converts the horizontally polarized light into the vertically polarized light before it is emitted; that is, the polarization state of the first light L1 is converted to the second polarization state. The first light L1 and the second light L2 together are emitted as the third light L3 with a vertical polarization state. Please refer to [link to previous text]. Figure 3 In other embodiments, if the first light L1 is vertically linearly polarized light and the first polarization state is vertically polarized, then the second light L2 is horizontally linearly polarized light and the second polarization state is horizontally polarized. When both horizontally and vertically linearly polarized light are incident on the polarizer 1, the horizontally linearly polarized light is reflected directly from the sub-polarizing prism 10 after reflection by the polarizing medium film 13. The vertically linearly polarized light is transmitted from the polarizing medium film 13 to the half-wave plate 11, which converts the vertically linearly polarized light into the horizontally linearly polarized light before it is emitted, i.e., the polarization state of the first light L1 is converted to the second polarization state. The first light L1 and the second light L2 together are emitted as a third light L3 with a horizontal polarization state.

[0030] The polarizing beam splitter 2 is formed by cementing the inclined surfaces of two right-angle prisms 20 together. A polarizing beam-splitting medium film 21 is coated on the inclined surface at the connection point of the right-angle prisms 20. When light is incident at a Brewster angle, the polarizing beam splitter 2 has a transmittance of approximately 1 for horizontally linearly polarized light and a transmittance of less than 1 for vertically linearly polarized light, but a reflectance of approximately 1 for vertically linearly polarized light. In this embodiment, if the first polarization state is horizontal and the second polarization state is vertical, then when a third light L3 with the second polarization state is incident on the polarizing beam splitter 2, the third light L3 is reflected from the polarizing beam-splitting medium film 21 to the phase retardation element 3. When a scanning light LS with the first polarization state is incident on the polarizing beam splitter 2 at a Brewster angle, the scanning light LS is transmitted from the polarizing beam-splitting medium film 21 and exits the polarizing beam splitter 2. In other embodiments, the polarizing beam splitter 2 may also have a transmittance of approximately 1 for vertically linearly polarized light, a transmittance of approximately 0 for horizontally linearly polarized light, and a reflectance of approximately 1; this application does not impose any limitations on this.

[0031] The phase delay element 3 can be fabricated using thin film directional stretching or birefringent materials, and is attached to the surface of the reflecting side of the polarizing beam splitter. The phase delay element 3 is used to adjust the polarization state of the third light L3. In this embodiment, the phase delay element 3 is a quarter-wave plate; in other embodiments, it can also be a half-wave plate, and this application is not limited thereto. The phase delay element 3 is used to receive the third light L3 emitted from the polarizing beam splitter 2 or the fifth light L5 emitted from the scanning element 4. The phase delay element 3 can convert the third light L3 into a fourth light L4 and the fifth light L5 into a scanning light LS. In this embodiment, when the first polarization state is horizontal and the second polarization state is vertical, the phase delay element 3 converts the vertically linearly polarized light into left-handed circularly polarized light, that is, at this time, the third light L3 is converted into the fourth light L4, and the third polarization state is circularly polarized. The phase delay element 3 converts the right-handed circularly polarized light into horizontally linearly polarized light. That is, at this time, the fifth light L5 is converted into the scanning light LS, and the fourth polarization state is circularly polarized. In other embodiments, the first polarization state is vertically polarized, the second polarization state is horizontally polarized, and the phase delay element 3 converts the horizontally linearly polarized light into right-handed circularly polarized light. That is, the third light L3 is converted into the fourth light L4, and the third polarization state is circularly polarized. The phase delay element 3 also converts left-handed circularly polarized light into vertically linearly polarized light. That is, the fifth light L5 is converted into the scanning light LS, and the fourth polarization state is circularly polarized.

[0032] The scanning element 4 can be any one of a micromirror, an optical phased array chip, or a digital micromirror device, and the specific choice can be made according to the specific needs of use; this application does not impose any restrictions. When the scanning element 4 is a micromirror, the micromirror can be deflected by a rocker arm (not shown) to achieve multi-angle scanning of the fifth light L5. When the scanning element 4 is an optical phased array chip, the optical phased array chip has multiple grating structures (not shown) to control the deflection to achieve multi-angle scanning of the fifth light L5. When the scanning element 4 is a digital micromirror device, a motor (not shown) is located below the digital micromirror device to control the deflection to achieve multi-angle scanning of the fifth light L5. The scanning element is used to receive the fourth light L4 and emit the fifth light L5 with the fourth polarization state towards the phase delay element 3. Please refer to [further details omitted]. Figure 1 The optical scanning system 100 also includes a collimating lens 5 and a focusing lens 6. The collimating lens 5 is disposed on the light-emitting side of the light source and is used to receive and collimate the first light L1 and the second light L2 emitted from the light source. The focusing lens 6 is disposed on the light-emitting side of the polarizer 1 and is used to receive the third light L3 emitted from the polarizer 1 and focus the third light L3 to the polarizing beam splitter 2.

[0033] Please refer to the following: Figure 4 and Figure 5The lidar 300 of this application embodiment includes a laser emitting system 301, an optical scanning system 100 of any of the above embodiments, and a laser receiving system 303. The laser emitting system 301 emits a first light L1 having a first polarization state and a second light L2 having a second polarization state. The laser emitting system 301 can be any of a liquid laser emitting system, a gas laser emitting system, and a solid-state laser emitting system (fiber, semiconductor, all-solid-state, hybrid), and this application is not limited thereto. The optical scanning system 100 receives the first light L1 and the second light L2, and converts the first light L1 and the second light L2 into the scanning light LS, which is then emitted to the target 303e. The lidar 300 receiving system receives the return light L6 reflected from the target 303e and obtains information about the target 303e based on the return light L6. The laser receiving system 303 includes a light-receiving lens 303a and a photosensor 303b. The light-receiving lens 303a is used to focus the return light L6. By setting the light-receiving lens 303a, the light reception rate of the lidar 300 can be improved. The material of the light-receiving lens 303a is either glass or resin, and this application is not limited thereto. The photosensor 303b is used to receive the return light L6 emitted from the light-receiving lens 303a and convert the return light L6 into an electrical signal.

[0034] The laser receiving system 303 may further include a transimpedance amplifier 303c and an analog-to-digital converter 303d. The electrical signal passes through the transimpedance amplifier 303c, which receives and amplifies the electrical signal transmitted from the photosensor 303b. Finally, the electrical signal passes through the analog-to-digital converter 303d, which converts the continuous analog signal into a discrete digital signal, thereby facilitating signal processing and data conversion, and enabling computer control and calculation.

[0035] The lidar 300 provided in this application embodiment, by employing the optical scanning system 100 of any of the above embodiments, is beneficial to reducing light loss in the lidar 300 and improving light utilization. The lidar 300 can more effectively emit scanning light LS to the target 303e to be measured, which is beneficial to improving the overall detection performance of the lidar 300.

[0036] Please see Figure 6The vehicle 400 in this embodiment includes a body 401 and a lidar 300 from any of the above embodiments, the lidar 300 being mounted on the body 401. The vehicle provided in this embodiment can be any of an electric vehicle, a gasoline vehicle, a diesel vehicle, or a hybrid vehicle; this application does not impose any limitation. The body 401 may further include a positioning system (not shown) and a control system (not shown). The positioning system is used to obtain information about the autonomous vehicle 400 by connecting to a satellite navigation system. The control system is used to adjust the speed and steering angle of the vehicle 400 in real time based on the information provided by the lidar 300 regarding the target.

[0037] The vehicle 400 provided in this application embodiment, by employing the lidar 300 described in any of the above embodiments, is beneficial to reducing light loss in the lidar 300, improving the energy utilization rate of the vehicle 400, enhancing the overall detection performance of the vehicle 400, increasing safety during driving, and thus extending the service life of the vehicle 400.

[0038] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. An optical scanning system, characterized by comprising: include: A polarizer receives a first light having a first polarization state and a second light having a second polarization state, the first polarization state being different from the second polarization state. The polarizer is used to convert the polarization state of the first light to the second polarization state and emit it together with the second light as a third light having the second polarization state. A polarizing beam splitter receives and reflects the third light; A phase delay element, located on the reflecting side of the polarizing beam splitter, is used to receive the third light and emit a fourth light with a third polarization state, the third polarization state being different from the first polarization state and the second polarization state; A scanning element is used to receive the fourth light and emit a fifth light with a fourth polarization state toward the phase delay element, the fourth polarization state being different from the first polarization state and the second polarization state. The scanning element is also used to change the emission angle of the fifth light. The fifth light emitted from the scanning element is converted into scanning light with a first polarization state by the phase delay element, and the polarization beam splitter located on the light-emitting side of the phase delay element is used to transmit and emit the scanning light.

2. The optical scanning system of claim 1, wherein The polarizer includes a half-wave plate and a polarizing dielectric film. The polarizing dielectric film reflects the second light and transmits the first light. The second light is emitted after reflection. The half-wave plate is used to receive the first light transmitted from the polarizing dielectric film and convert the polarization state of the first light into the second polarization state before emitting it.

3. The optical scanning system of claim 1, wherein The optical scanning system further includes a collimating lens, which is disposed on the light-emitting side of the light source and is used to receive and collimate the first light and the second light emitted from the light source.

4. The optical scanning system of claim 1, wherein The optical scanning system also includes a focusing lens, which is disposed on the light-emitting side of the polarizer and is used to receive the third light emitted from the polarizer and to focus and transmit the third light to the polarizing beam splitter.

5. The optical scanning system of claim 1, wherein The scanning element is any one of a micromirror, an optical phased array chip, or a digital micromirror device.

6. The optical scanning system of claim 1, wherein The third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

7. An optical scanning system as claimed in any one of claims 1 to 6, characterized in that The first polarization state is a horizontal polarization state, the second polarization state is a vertical polarization state, the third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

8. An optical scanning system as claimed in any one of claims 1 to 6, characterized in that The first polarization state is a vertical polarization state, the second polarization state is a horizontal polarization state, the third polarization state is a circular polarization state, and the fourth polarization state is a circular polarization state.

9. A lidar, comprising: include: A laser emitting system for emitting a laser, the laser comprising a first light having a first polarization state and a second light having a second polarization state; The optical scanning system according to any one of claims 1-8 is used to receive the first light and the second light, and convert the first light and the second light into the scanning light and emit it to the target to be tested; A laser receiving system is used to receive the reflected light from the target under test and obtain information about the target under test based on the reflected light.

10. A vehicle characterized by comprising: include: The subject; and The lidar as described in claim 9 is mounted on the main body.

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