A detection device, a detector, a laser radar and a terminal device

Abstract

A kind of detection device, detector, laser radar and terminal equipment, it can be applied to automatic driving, intelligent driving or surveying and mapping etc.Field.Detection device can be applied to laser radar or terminal equipment (such as vehicle, smart home device or intelligent transportation equipment etc.), detection device includes: emitting module is used to emit first light beam;First lens group is used to receive echo signal from the detection area for first light beam, and echo signal is converged to first polarization state conversion component;First polarization state conversion component is used to propagate echo signal from first lens group to detection module, and the polarization state of echo signal reflected by detection module is converted to realize the absorption of reflected echo signal;Detection module is used to convert received echo signal into electrical signal, and electrical signal is used to determine the information of target in detection area.Can avoid that the echo signal reflected by detection module enters detection module again, so that the optical crosstalk of echo signal reflected by detection module can be avoided.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to a detection device, detector, lidar, and terminal equipment. Background Technology

[0002] LiDAR (Light Detection and Ranging) is a detection device that uses laser beams to detect the position, velocity, and other characteristics of a target. The working principle of LiDAR is to emit a detection signal towards the target, then compare and process the echo signal reflected back from the target with the detection signal to obtain information about the target, such as its distance, azimuth, velocity, attitude, and even shape. This allows for the detection, tracking, and identification of the target.

[0003] Because the detectors in lidar have a certain reflectivity, they may reflect the received echo signals. The echo signals reflected by the detector will re-enter the detector, which will cause optical crosstalk to the actual echo signal. For example, it may form a crosstalk image, which will cause the detector to detect false targets. Summary of the Invention

[0004] This application provides a detection device, detector, lidar, and terminal equipment to minimize optical crosstalk caused by the echo signal reflected from the detection module.

[0005] In a first aspect, this application provides a detection device, which may include a transmitting module, a receiving module, and a detection module. The receiving module includes a first lens group and a first polarization state conversion component. The transmitting module is used to emit a first light beam. The first lens group is used to receive echo signals from a detection area directed at the first light beam and to converge the echo signals to the first polarization state conversion component. The first polarization state conversion component is used to propagate the echo signals from the first lens group to the detection module and to convert the polarization state of the echo signals reflected by the detection module to achieve absorption of the reflected echo signals. The detection module is used to convert the received echo signals into electrical signals, which are used to determine information about a target in the detection area.

[0006] Based on the aforementioned detection device, the first polarization state conversion component can convert the polarization state of the echo signal reflected by the detection module to absorb the echo signal reflected by the detection module. In this way, the echo signal reflected by the detection module will not re-enter the detection module, thereby preventing optical crosstalk between the echo signal reflected by the detection module and the echo signal from the detection area.

[0007] The following examples illustrate the structures of six possible first polarization state conversion components.

[0008] Structure 1: The first polarization state conversion component includes a first polarizer and a second quarter-wave plate.

[0009] Based on this structure, the function of the first polarization state conversion component can be realized through a simple structure.

[0010] In one possible implementation, the polarization state of the echo signal from the first lens group is either first linearly polarized light or first circularly polarized light. Based on the above structure, the first polarizer allows the echo signal from the first lens group with the polarization state of first linearly polarized light to pass through. In other words, the first polarizer allows a portion of the echo signal of first circularly polarized light (i.e., the portion of the echo signal with the polarization state of first linearly polarized light) or the echo signal with the polarization state of first linearly polarized light to pass through. The second quarter-wave plate is used to convert the echo signal with the polarization state of first linearly polarized light that passes through the first polarizer into an echo signal with the polarization state of second circularly polarized light. The second quarter-wave plate is also used to convert the echo signal with the polarization state of second circularly polarized light reflected by the detection module into an echo signal with the polarization state of second linearly polarized light. The first polarizer is also used to absorb the echo signal with the polarization state of second linearly polarized light.

[0011] Further, optionally, the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer is 45±0.2°.

[0012] By setting the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer to 45±0.2°, the effect of the first polarization state conversion component in absorbing the echo signal reflected by the detection module can be improved.

[0013] Structure 2, the first polarization state conversion component includes a first quarter wave plate, a first polarizer, and a second quarter wave plate.

[0014] Based on this second structure, crosstalk suppression can be achieved twice, which can further improve crosstalk isolation and thus help to further improve the detection device's ability to identify targets.

[0015] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above-described structure two, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. The first polarizer passes the echo signal with the first linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the first linearly polarized light polarization state that passes through the first polarizer into an echo signal with the second circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the second circularly polarized light polarization state reflected by the detection module into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0016] Further, optionally, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°, and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°. This helps to improve the absorption effect of the first polarization state conversion component on the echo signal reflected by the detection module.

[0017] Structure 3, the first polarization state conversion component includes a first polarizer, a second half-wave plate and a second quarter-wave plate.

[0018] Based on this structure, by combining the second 1 / 2 waveplate and the second 1 / 4 waveplate, dispersion can be eliminated, thus enabling the detection device to effectively suppress crosstalk even when the wavelength drifts at high or low temperatures.

[0019] In one possible implementation, the polarization state of the echo signal from the first lens group is first linearly polarized light. Based on the above structure three, the first polarizer is used to transmit the echo signal with the first linearly polarized light polarization state from the first lens group. The second half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second half-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0020] Furthermore, optionally, the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the first polarizer is 45 ± 0.2°. This helps to improve the absorption effect of the first polarization state conversion component on the echo signal reflected by the detection module.

[0021] Structure four, the first polarization state conversion component also includes a first quarter wave plate, a first polarizer, a second half wave plate and a second quarter wave plate.

[0022] Based on this structure, crosstalk suppression can be achieved twice, which can further improve crosstalk isolation and thus help to further improve the detection device's ability to identify targets. Moreover, by combining the second 1 / 2 waveplate and the second 1 / 4 waveplate, dispersion can be eliminated, so that the detection device can also have a good effect of suppressing crosstalk when the wavelength drifts at high or low temperatures.

[0023] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above structure four, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first polarizer is used to transmit the echo signal with the first linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state to an echo signal with the second linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state to an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second half-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0024] Further, optionally, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°, and the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the first polarizer is 45±0.5°. This helps to improve the absorption effect of the first polarization state conversion component on the echo signal reflected by the detection module.

[0025] Structure 5, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, and a second quarter wave plate.

[0026] Based on this structure, the first 1 / 4 wave plate and the second 1 / 4 wave plate can achieve the effect of suppressing crosstalk twice, which can further improve the crosstalk isolation and thus help to further improve the detection device's ability to identify targets. Moreover, the combination of the first 1 / 4 wave plate and the first 1 / 2 wave plate can eliminate dispersion, so that the detection device can also have a good effect of suppressing crosstalk when the wavelength drifts at high or low temperatures.

[0027] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light; a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. A second polarizer is used to transmit the echo signal with the second linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second polarizer is also used to absorb the echo signal with the first linearly polarized light polarization state.

[0028] Further, optionally, the angle between the equivalent optical axes of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45±0.5°, and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the second polarizer is 45±0.5°. This helps to improve the absorption effect of the first polarization state conversion component on the echo signal reflected by the detection module.

[0029] Structure 6, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, a second half wave plate and a second quarter wave plate.

[0030] Based on this structure, the first quarter-wave plate and the second quarter-wave plate can achieve the effect of suppressing crosstalk twice, which can further improve the crosstalk isolation and thus help to further improve the detection device's ability to identify targets. Moreover, the combination of the first quarter-wave plate, the first half-wave plate, the second half-wave plate and the second quarter-wave plate can effectively eliminate dispersion, so that the detection device can also have a good effect of suppressing crosstalk when the wavelength drifts at high or low temperatures.

[0031] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above structure six, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. A second polarizer is used to transmit the echo signal with the second linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first linearly polarized light polarization state. A second quarter-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second circularly polarized light polarization state reflected by the detection module into an echo signal with the second linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first linearly polarized light polarization state. The second polarizer is also used to absorb the echo signal of light with the polarization state of first linear polarization.

[0032] Further, optionally, the angle between the equivalent optical axes of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45±0.5°, and the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the second polarizer is also 45±0.5°. This helps to improve the absorption effect of the first polarization state conversion component on the echo signal reflected by the detection module.

[0033] In one possible implementation, the transmitting module may include a light source module and a second polarization state conversion component; the light source module is used to emit a first beam of light with a first linear polarization state; the second polarization state conversion component is used to convert the first beam of light with a first linear polarization state into a first beam of light with a first circular polarization state.

[0034] Furthermore, optionally, the second polarization state conversion component includes a third quarter-wave plate.

[0035] When the first polarization state conversion component is structure two as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module as linearly polarized light is parallel to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as linearly polarized light is orthogonal to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is orthogonal to the optical axis of the third quarter-wave plate. This allows the echo signal to pass through the first polarizer as much as possible, helping to improve the reception rate of the echo signal and thus increasing the utilization rate of the echo signal.

[0036] When the first polarization state conversion component is structure four as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module as linearly polarized light is parallel to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as linearly polarized light is orthogonal to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is orthogonal to the optical axis of the third quarter-wave plate. This allows the echo signal to pass through the first polarizer as much as possible, helping to improve the reception rate of the echo signal and thus increasing the utilization rate of the echo signal.

[0037] When the first polarization state conversion component is structure five as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module as linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the optical axis of the third quarter-wave plate. This allows the echo signal to pass through the second polarizer as much as possible, helping to improve the reception rate of the echo signal and thus increasing the utilization rate of the echo signal.

[0038] When the first polarization state conversion component is structure six as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module as linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the optical axis of the third quarter-wave plate. This allows the echo signal to pass through the second polarizer as much as possible, helping to improve the reception rate of the echo signal and thus increasing the utilization rate of the echo signal.

[0039] In another possible implementation, the emission module may include a light source module and a second polarization state conversion component; the light source module is used to emit a first beam with a second linear polarization state; the second polarization state conversion component is used to convert the first beam with the second linear polarization state into a first beam with the first circular polarization state.

[0040] Further, optionally, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate. The third half-wave plate is used to convert the first beam with a second linear polarization state into a first beam with a first linear polarization state; the third quarter-wave plate is used to convert the first beam with a first linear polarization state into a first beam with a first circular polarization state.

[0041] Adding a third half-wave plate to the second polarization state conversion component can further eliminate dispersion.

[0042] When the first polarization state conversion component is structure two as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is parallel to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are parallel to the optical axis of the first quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is orthogonal to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are orthogonal to the optical axis of the first quarter-wave plate.

[0043] When the first polarization state conversion component is structure four as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is parallel to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are parallel to the optical axis of the first quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is orthogonal to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are orthogonal to the optical axis of the first quarter-wave plate.

[0044] When the first polarization state conversion component is structure five as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate.

[0045] When the first polarization state conversion component is structure six as described above, the angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°. Further, optionally, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module, which is polarized as linearly polarized light, is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate.

[0046] In one possible implementation, the first polarization state conversion component is located on the detection module.

[0047] By placing the polarization state conversion component on the detection module, the assembly of the detection device can be simplified.

[0048] Secondly, this application provides a detector that may include a detection module and a first polarization state conversion component. The first polarization state conversion component is used to receive an echo signal from a detection region corresponding to a first beam emitted by a transmitting module, and to propagate the echo signal to the detection module. The detection module is used to convert the received echo signal into an electrical signal, which is used to determine information about a target in the detection region. The first polarization state conversion component is also used to convert the polarization state of the echo signal reflected by the detection module to achieve absorption of the echo signal reflected by the detection module.

[0049] The following examples illustrate six possible structures for the first polarization state conversion component.

[0050] Structure 1: The first polarization state conversion component includes a first polarizer and a second quarter-wave plate.

[0051] Based on this structure, the function of the first polarization state conversion component can be realized through a simple structure.

[0052] In one possible implementation, the polarization state of the echo signal from the first lens group is either first linearly polarized light or first circularly polarized light. Based on the above structure, the first polarizer allows the echo signal from the first lens group with the polarization state of first linearly polarized light to pass through. In other words, the first polarizer allows a portion of the echo signal of first circularly polarized light (i.e., the portion of the echo signal with the polarization state of first linearly polarized light) or the echo signal with the polarization state of first linearly polarized light to pass through. The second quarter-wave plate is used to convert the echo signal with the polarization state of first linearly polarized light that passes through the first polarizer into an echo signal with the polarization state of second circularly polarized light. The second quarter-wave plate is also used to convert the echo signal with the polarization state of second circularly polarized light reflected by the detection module into an echo signal with the polarization state of second linearly polarized light. The first polarizer is also used to absorb the echo signal with the polarization state of second linearly polarized light.

[0053] Further, optionally, the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer is 45±0.2°.

[0054] Structure 2, the first polarization state conversion component includes a first quarter wave plate, a first polarizer, and a second quarter wave plate.

[0055] Based on this second structure, crosstalk suppression can be achieved twice, thereby further improving crosstalk isolation.

[0056] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above-described structure two, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. The first polarizer passes the echo signal with the first linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the first linearly polarized light polarization state that passes through the first polarizer into an echo signal with the second circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the second circularly polarized light polarization state reflected by the detection module into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0057] Further, optionally, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°, and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°.

[0058] Structure 3, the first polarization state conversion component includes a first polarizer, a second half-wave plate and a second quarter-wave plate.

[0059] Based on this structure, by combining the second 1 / 2 waveplate and the second 1 / 4 waveplate, dispersion can be eliminated, thus enabling the detection device to effectively suppress crosstalk even when the wavelength drifts at high or low temperatures.

[0060] In one possible implementation, the polarization state of the echo signal from the first lens group is first linearly polarized light. Based on the above structure three, the first polarizer is used to transmit the echo signal with the first linearly polarized light polarization state from the first lens group. The second half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second half-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0061] Further, optionally, the angle between the equivalent optical axis of the second quarter wave plate and the second half wave plate and the polarization direction of the first polarizer is 45±0.2°.

[0062] Structure four, the first polarization state conversion component also includes a first quarter wave plate, a first polarizer, a second half wave plate and a second quarter wave plate.

[0063] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above structure four, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first polarizer is used to transmit the echo signal with the first linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state to an echo signal with the second linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state to an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second half-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. The first polarizer is also used to absorb the echo signal with the second linearly polarized light polarization state.

[0064] Further, optionally, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45±0.5°, and the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the first polarizer is 45±0.5°.

[0065] Structure 5, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, and a second quarter wave plate.

[0066] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light; a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. A second polarizer is used to transmit the echo signal with the second linearly polarized light polarization state. A second quarter-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first circularly polarized light polarization state. The second quarter-wave plate is also used to convert the echo signal with the first circularly polarized light polarization state reflected by the detection module into an echo signal with the first linearly polarized light polarization state. The second polarizer is also used to absorb the echo signal with the first linearly polarized light polarization state.

[0067] Further, optionally, the angle between the equivalent optical axis of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45±0.5°, and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the second polarizer is 45±0.5°.

[0068] Structure 6, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, a second half wave plate and a second quarter wave plate.

[0069] In one possible implementation, the polarization state of the echo signal from the first lens group is first circularly polarized light. Based on the above structure six, a first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from first circularly polarized light to first linearly polarized light. A first half-wave plate is used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second linearly polarized light polarization state. A second polarizer is used to transmit the echo signal with the second linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first linearly polarized light polarization state. A second quarter-wave plate is also used to convert the echo signal with the first linearly polarized light polarization state into an echo signal with the second circularly polarized light polarization state reflected by the detection module into an echo signal with the second linearly polarized light polarization state. A second half-wave plate is used to convert the echo signal with the second linearly polarized light polarization state into an echo signal with the first linearly polarized light polarization state. The second polarizer is also used to absorb the echo signal of light with the polarization state of first linear polarization.

[0070] Further, optionally, the angle between the equivalent optical axis of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45±0.5°, and the angle between the equivalent optical axis of the second quarter-wave plate and the second half-wave plate and the polarization direction of the second polarizer is 45±0.5°.

[0071] Thirdly, this application provides a lidar, including the detection device described in the first aspect or any one of the first aspects.

[0072] Fourthly, this application provides a terminal device, including the detection device described in the first aspect or any one of the first aspects.

[0073] In one possible implementation, the terminal device can be a smartphone, vehicle, smart home device, smart manufacturing equipment, robot, drone, smart transportation equipment, or surveying equipment.

[0074] Fifthly, this application provides a lidar, including the detector described in the second aspect or any one of the second aspects above.

[0075] Sixthly, this application provides a terminal device including the detector described in the second aspect or any one of the second aspects.

[0076] In one possible implementation, the terminal device can be a smartphone, vehicle, smart home device, smart manufacturing equipment, robot, drone, smart transportation equipment, or surveying equipment.

[0077] The technical effects that can be achieved by any of the second to sixth aspects mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0078] Figure 1 This application provides a schematic diagram of an application scenario for a lidar.

[0079] Figure 2 A schematic diagram of the structure of a detection device provided in this application;

[0080] Figure 3 This is a schematic diagram of the structure of a first polarization state conversion component provided in this application;

[0081] Figure 4a This application provides a schematic diagram of the propagation optical path in a first polarization state conversion component;

[0082] Figure 4b Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0083] Figure 5 A schematic diagram of the structure of yet another first polarization state conversion component provided in this application;

[0084] Figure 6 Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0085] Figure 7 A schematic diagram of the structure of yet another first polarization state conversion component provided in this application;

[0086] Figure 8 Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0087] Figure 9 A schematic diagram of the structure of yet another first polarization state conversion component provided in this application;

[0088] Figure 10 Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0089] Figure 11 A schematic diagram of the structure of yet another first polarization state conversion component provided in this application;

[0090] Figure 12 Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0091] Figure 13 A schematic diagram of the structure of yet another first polarization state conversion component provided in this application;

[0092] Figure 14 Another schematic diagram of the propagation optical path in the first polarization state conversion component provided in this application;

[0093] Figure 15 This application provides a schematic diagram of the structure of a first lens group;

[0094] Figure 16a A schematic diagram of the propagation optical path of a transmitting module provided in this application;

[0095] Figure 16b A schematic diagram of the propagation optical path of another transmitting module provided in this application;

[0096] Figure 17 This application provides a schematic diagram of the structure of a second lens group;

[0097] Figure 18 This application provides a schematic diagram illustrating the positional relationship between a detection module and a first polarization state conversion component.

[0098] Figure 19a A schematic diagram of the structure of a scanner provided in this application;

[0099] Figure 19b A schematic diagram of the structure of a scanner provided in this application;

[0100] Figure 20 This is a schematic diagram of the structure of a detector provided in this application. Detailed Implementation

[0101] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0102] The following provides explanations for some of the terms used in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0103] I. Linear polarized light

[0104] Linearly polarized light is also called linearly polarized light or plane-polarized light. Light whose electric vector lies within a defined plane along its propagation direction is called plane-polarized light. Because the trajectory of the electric vector endpoints is a straight line, it is called linearly polarized light. The plane formed by the direction of the light vector and the direction of light propagation is called the plane of vibration. The plane of vibration of linearly polarized light is fixed and does not deflect.

[0105] II. Circular Polarizing Light

[0106] Circularly polarized light is also called circularly polarized light. Light whose rotating electric vector endpoint traces a circular trajectory is called circularly polarized light, a special case of elliptically polarized light. When the propagation directions are the same, the vibration directions are perpendicular to each other, and the phase difference is constant... Two plane-polarized lights, when superimposed, can synthesize circularly polarized light with a regularly changing electric vector. The magnitude of the electric vector of the circularly polarized light remains constant, while its direction changes uniformly with time. The phase difference is... The light is left-handed circularly polarized, with a phase difference of . It is right-handed circularly polarized light.

[0107] III. Elliptically polarized light

[0108] Elliptically polarized light refers to the trajectory traced by the electric or optical vector of light on a plane perpendicular to the direction of propagation. When two mutually perpendicular vibrations act simultaneously on a point, if they have the same frequency and a fixed phase difference, the trajectory of the combined vibration at that point is generally elliptical.

[0109] During the propagation of light, the electric vector at every point in space rotates about the ray as an axis, and the endpoints of the electric vector trace an elliptical trajectory. This type of light is called elliptically polarized light. Looking towards the ray, light with a clockwise rotating electric vector is called right-handed elliptically polarized light, and light with a counter-clockwise rotating electric vector is called left-handed elliptically polarized light. The rotating electric vector in elliptically polarized light is the result of the synthesis of two electric vectors with the same frequency, perpendicular vibration directions, and a fixed phase difference.

[0110] IV. 1 / 4 wave plate

[0111] A quarter-wave plate, also known as a quarter-retarder plate, is used to transmit light normally incident through a wave. The phase difference between the outgoing ordinary (o) and extraordinary (e) rays is equal to one-quarter of the wavelength. In an optical path, a quarter-wave plate is commonly used to convert linearly polarized light into circularly or elliptically polarized light, or vice versa. For example, when linearly polarized light is incident perpendicularly to a quarter-wave plate, and the polarization of the light forms an angle θ with the optical axis of the quarter-wave plate (perpendicular to the natural split plane), the emitted light is elliptically polarized. When θ = 45°, the emitted light is circularly polarized.

[0112] When light propagates in a uniaxial crystal and undergoes birefringence, one of the two refracted beams always obeys the ordinary law of refraction. This beam is called the ordinary light (o-ray) or simply the o-ray. The polarized light that is perpendicular to the vibration direction of the o-ray is called the extraordinary light (e-ray).

[0113] V. Half-wave plate

[0114] A half-wave plate, also known as a 1 / 2-wave plate, is a birefringent crystal of a certain thickness. When normally incident light passes through it, the phase difference between the ordinary and extraordinary rays that emerge is equal to half the wavelength. In an optical path, a half-wave plate is used to change the direction of polarized light. When plane-polarized light passes through a half-wave plate, the outgoing light remains plane-polarized, but the plane of polarization has rotated by a certain angle. For example, when P-polarized light is incident perpendicularly on a half-wave plate, it emerges as S-polarized light. When circularly polarized or elliptically polarized light is incident on a half-wave plate, the outgoing light remains circularly or elliptically polarized, but with the opposite polarization direction.

[0115] VI. Polarizing Film

[0116] A polarizer, also known as a sheet polarizer, is a type of optical filter. Polarizers are used to absorb or reflect light with one polarization direction and transmit light with another orthogonally polarized direction. The transmittance of light is directly related to its polarization state. Polarizers are generally classified into absorptive polarizers and reflective polarizers (RP). Absorptive polarizers strongly absorb one of the orthogonally polarized components of incident linearly polarized light, while absorbing the other component less strongly. In other words, an absorptive polarizer strongly absorbs linearly polarized light in a certain direction and transmits light with a polarization direction perpendicular to the direction of strong absorption. A reflective polarizer transmits linearly polarized light in a certain direction and reflects light with a polarization direction perpendicular to the direction of transmission. Absorptive polarizers can be, for example, dichroic polarizers, while reflective polarizers can be, for example, birefringent polarizing beam splitters.

[0117] It should be noted that when linearly polarized light is incident on a polarizer, the outgoing light is still linearly polarized; when circularly polarized or elliptically polarized light is incident on a polarizer, the outgoing light is linearly polarized.

[0118] VII. Polarization Direction

[0119] The polarization direction is also called the polarization direction. This is because there is a certain characteristic direction in the polarizer, called the polarization direction. The polarizer only allows vibrations parallel to the polarization direction to pass through, while absorbing or reflecting light that vibrates perpendicular to that direction.

[0120] 8. Optical Axis

[0121] The optical axis of a 1 / 2 wave plate or a 1 / 4 wave plate refers to the direction of the e-ray vector.

[0122] 9. Zero-order waveplate

[0123] Waveplates can be classified into multi-order waveplates, true zero-order waveplates, and composite waveplates according to their structure. Multi-order waveplates refer to waveplates where, in addition to a delay smaller than one wavelength, the optical path also undergoes several full-wavelength delays (also called orders). True zero-order waveplates have low wavelength sensitivity to delay, high temperature stability, and a large effective receiving angle.

[0124] 10. Optical crosstalk

[0125] Optical crosstalk refers to stray light interfering with the received normal light.

[0126] XI. Gluing

[0127] Gluing, also known as bonding, overlapping, or lamination, refers to the process of joining surfaces that have been coated with glue or allowed to dry properly together.

[0128] Based on the above, such as Figure 1 The diagram shown illustrates an application scenario of a lidar provided in this application. This lidar emits a laser beam in a specific direction. If a target exists within a certain distance along the emission direction of the laser beam, the target can reflect the received laser beam back to the lidar (called an echo signal). Based on the echo signal, the lidar can determine information about the target, such as the distance to the target, the target's speed, the target's attitude, or a point cloud map. It should be understood that this example uses a lidar deployed at the front of a vehicle. This lidar can sense a fan-shaped area as shown in the dashed box; this fan-shaped area can be referred to as the lidar's detection area.

[0129] This application scenario could include autonomous driving, automatic driving, assisted driving, intelligent driving, and connected vehicles. In this scenario, LiDAR can be installed on vehicles (such as autonomous vehicles, intelligent vehicles, electric vehicles, and digital vehicles) as automotive LiDAR (e.g., automotive FMCW LiDAR). Automotive LiDAR can acquire measurement information such as the vehicle's latitude and longitude, speed, orientation, and distance to surrounding objects in real time or periodically. This measurement information, combined with advanced driving assistance systems (ADAS), enables assisted driving or autonomous driving. For example, latitude and longitude can be used to determine the vehicle's position, speed and orientation can be used to determine the vehicle's direction and destination over a future period, or the distance to surrounding objects can be used to determine the number and density of obstacles around the vehicle. Automotive LiDAR can also perform mapping functions. Alternatively, LiDAR can also be installed on drones as airborne LiDAR (e.g., airborne FMCW LiDAR). Alternatively, lidar can be installed on roadside traffic equipment (such as roadside units (RSUs)) as roadside traffic lidar, thereby enabling intelligent vehicle-road cooperation.

[0130] It should be noted that the above application scenarios are merely examples, and the LiDAR provided in this application can also be applied in a variety of other scenarios, not limited to those listed above. For example, LiDAR can also be applied to terminal devices or components installed in terminal devices. Terminal devices can be, for example, smartphones, smart home devices, smart manufacturing equipment, robots, drones, or smart transportation equipment (such as automated guided vehicles (AGVs) or unmanned vehicles). Furthermore, LiDAR can also be installed on the sides or rear of a vehicle, and this application does not limit this to these locations.

[0131] In lidar, the detector typically performs photoelectric conversion on the received echo signal and determines the target information based on the converted electrical signal. However, because the detector has a certain reflectivity (such as a single-photon avalanche diode, SPAD), it may reflect a portion of the received echo signal. This reflected echo signal can then be reflected by the lens (or lens group) in the lidar, thus re-entering the detector and forming a crosstalk image; or it can reflect back to the target, forming a false target crosstalk image.

[0132] In view of this, this application proposes a detection device. This detection device can be used to minimize optical crosstalk caused by the echo signal reflected by the detection module.

[0133] The following is in conjunction with the appendix Figure 2 To be continued Figure 19b This application will provide a detailed description of the detection device proposed in this application.

[0134] Based on the above, such as Figure 2The diagram shown is a schematic representation of a detection device provided in this application. The detection device may include a transmitting module 201, a receiving module 202, and a detection module 203. The receiving module includes a first lens group 2021 and a first polarization state conversion component 2022. The transmitting module 201 can be used to emit a first light beam. Specifically, the transmitting module 201 can emit a first light beam towards a detection area. The first lens group 2021 is used to receive echo signals from the detection area related to the first light beam and converge the received echo signals to the first polarization state conversion component 2022. The first polarization state conversion component 2022 is used to propagate the echo signals from the first lens group 2021 to the detection module 203, and to convert the polarization state of the echo signals reflected by the detection module 203 to achieve absorption of the echo signals reflected by the detection module. Alternatively, the first polarization state conversion component 2022 can be understood as follows: it propagates the echo signal from the first lens group 2021 to the detection module 203 and converts the polarization state of the echo signal reflected by the detection module 203. The polarization-converted echo signal can be absorbed by the first polarization state conversion component 2022. The detection module 203 converts the received echo signal (i.e., the echo optical signal) into an electrical signal, which can be used to determine information about the target in the detection area.

[0135] Based on the aforementioned detection device, the first polarization state conversion component can convert the polarization state of the echo signal reflected by the detection module to absorb the reflected echo signal. In this way, the echo signal reflected by the detection module will not re-enter the detection module, thus avoiding optical crosstalk between the reflected echo signal and the echo signal from the detection area. This helps improve the detection accuracy and target identification capability of the detection device. Especially when the detection device is applied to the field of high-intensity light detection, the echo signal reflected by the detection module is very strong. If the echo signal reflected by the detection module re-enters the detection module, it will severely affect the detection module's ability to detect echo signals from the detection area.

[0136] Here, the target information may include, for example, the target's distance information, the target's depth image, and / or the target's point cloud map.

[0137] It should be noted that the echo signal for the first beam mentioned above refers to the echo signal obtained by the target reflecting the first beam. The polarization state of the echo signal for the first beam is the same as the polarization state of the first beam directed towards the detection area, and the polarization state of the echo signal from the first lens group is the same as the polarization state of the echo signal for the first beam.

[0138] It should also be noted that the first polarization state conversion component can also convert the polarization state of the echo signal from the first lens group and propagate the polarization-converted echo signal to the detection module, as described below. Figure 4a , Figure 4b , Figure 6 , Figure 7 , Figure 8 or Figure 14 The details of the previous section will not be repeated here. It can also be understood that the polarization state of the echo signal from the first lens group is different from the polarization state of the echo signal propagated to the detection module by the first polarization state conversion component. In other words, the first polarization state conversion component can be used to convert the polarization state of the echo signal from the first lens group and propagate the polarization-converted echo signal to the detection module. Alternatively, the first polarization state conversion component can be used to convert the polarization state of the echo signal from the first lens group, but the polarization state of the echo signal propagated to the detection module by the first polarization state conversion component is the same as the polarization state of the echo signal from the first lens group, as described below. Figure 10 or Figure 12 The details of this introduction will not be repeated here. It can also be understood that the first polarization state conversion component does not change the polarization state of the echo signal from the first lens group. Furthermore, the polarization state of the echo signal propagating to the detection module is the same as the polarization state of the echo signal reflected by the detection module.

[0139] It should also be noted that most of the echo signal propagating to the detection module is converted into an electrical signal by the detection module, and a small portion is reflected by the detection module (i.e., the echo signal reflected by the detection module). In other words, the echo signal reflected by the detection module is a part of the echo signal it receives.

[0140] The following is about Figure 2 Each functional component and structure shown is described in detail to provide an exemplary implementation scheme. For ease of explanation, the transmitting module 201, receiving module 202, detection module 203, first lens group 2021, and first polarization state conversion component 2022 are not labeled in the following text.

[0141] In the following description, for ease of explanation, we will use the following examples: a first polarizer allows first linearly polarized light to pass through while absorbing second linearly polarized light; a second polarizer allows second linearly polarized light to pass through while absorbing first linearly polarized light. The accompanying drawings illustrate examples where the first linearly polarized light is P-polarized, the second linearly polarized light is S-polarized, the first circularly polarized light is left-handed, and the second circularly polarized light is right-handed. Furthermore, unless otherwise specified, the propagation optical path of the echo signal in the first polarization state conversion component includes the propagation optical path of the echo signal from the first lens group and the propagation optical path of the echo signal reflected by the detection module in the first polarization state conversion component.

[0142] I. First Polarization State Conversion Component

[0143] In the following description, the various structures included in the first polarization state conversion component refer to the direction along the principal optical axis of the first lens group, from the target side to the detection module.

[0144] The following examples illustrate the structures of six first polarization state conversion components.

[0145] Structure 1: The first polarization state conversion component includes a first polarizer and a second quarter-wave plate.

[0146] like Figure 3 The diagram shown is a structural schematic of a first polarization state conversion component provided in this application. The first polarization state conversion component sequentially includes a first polarizer and a second quarter-wave plate. Based on this structure, the function of the first polarization state conversion component can be achieved with a simple structure. Exemplarily, the first polarizer and the second quarter-wave plate can be glued together.

[0147] In one possible implementation, the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer (or the polarization direction of the first polarizer) is 45° ± 0.2°. Alternatively, this can be understood as the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer being 45°, with a permissible deviation of ±0.2°.

[0148] Based on the different polarization states of the echo signal from the first lens group, the process of the first polarization state conversion component absorbing the reflected echo signal is described below in different cases.

[0149] In scenario A, the polarization state of the echo signal from the first lens group can be the first linearly polarized light.

[0150] Based on scenario A, the propagation optical path of the echo signal in the first polarization state conversion component can be seen as follows: Figure 4a Specifically: the echo signal of the first linearly polarized light passes through the first polarizer and propagates to the second quarter-wave plate; the echo signal of the first linearly polarized light is converted into an echo signal of the second circularly polarized light after passing through the second quarter-wave plate and propagates to the detection module; the echo signal of the second circularly polarized light is reflected by the detection module to the second quarter-wave plate; the second quarter-wave plate is also used to convert the echo signal of the second circularly polarized light reflected by the detection module into an echo signal of the second linearly polarized light and propagates to the first polarizer; the echo signal of the second linearly polarized light is absorbed after passing through the first polarizer, that is, the echo signal of the second linearly polarized light is cut off by the first polarizer.

[0151] In scenario B, the polarization state of the echo signal from the first lens group can be the first circularly polarized light.

[0152] Based on scenario B, the propagation optical path of the echo signal in the first polarization state conversion component can be seen as follows: Figure 4b Specifically: the first polarizer allows the echo signal with the polarization state of first linear polarization from the echo signal with the polarization state of first circular polarization to pass through. That is, the first polarizer allows a portion of the echo signal with the polarization state of first circular polarization (i.e., the echo signal with the polarization state of first linear polarization) to pass through. In other words, the echo signal with the polarization state of first circular polarization is converted into an echo signal with the polarization state of first linear polarization after passing through the first polarizer, meaning that the echo signal with the polarization state of first linear polarization can propagate to the second quarter-wave plate. The echo signal with the polarization state of first linear polarization is converted into an echo signal with the polarization state of second circular polarization after passing through the second quarter-wave plate, and the echo signal with the polarization state of second circular polarization is reflected by the detection module to the second quarter-wave plate. The second quarter-wave plate is also used to convert the echo signal with the polarization state of second circular polarization into an echo signal with the polarization state of second linear polarization and propagate it to the first polarizer. The echo signal with the polarization state of second linear polarization is absorbed after passing through the first polarizer.

[0153] Structure 2, the first polarization state conversion component includes a first quarter wave plate, a first polarizer, and a second quarter wave plate.

[0154] like Figure 5 The diagram shown is a structural schematic of another first polarization state conversion component provided in this application. The first polarization state conversion component sequentially includes a first quarter-wave plate, a first polarizer, and a second quarter-wave plate. Exemplarily, the first quarter-wave plate is glued to one side of the first polarizer, and the other side of the first polarizer is glued to the second quarter-wave plate.

[0155] In one possible implementation, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°, and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0156] Based on the above Figure 5 The first polarization state conversion component shown receives echo signals from the first lens group that are circularly polarized. The propagation optical path of the echo signal in the first polarization state conversion component can be found in [reference needed]. Figure 6Specifically: the echo signal of the first circularly polarized light is converted into the first linearly polarized light after passing through the first quarter-wave plate and propagates to the first polarizer; the echo signal of the first linearly polarized light passes through the first polarizer and propagates to the second quarter-wave plate; the echo signal of the first linearly polarized light is converted into the second circularly polarized light after passing through the second quarter-wave plate and propagates to the detection module; the echo signal of the second circularly polarized light is reflected by the detection module to the second quarter-wave plate; the second quarter-wave plate is also used to convert the echo signal of the second circularly polarized light reflected by the detection module into the second linearly polarized light, and propagates to the first polarizer; the echo signal of the second linearly polarized light is absorbed after passing through the first polarizer.

[0157] Based on the above structure two, through Figure 6 In the optical path shown, if the echo signal reflected back from the detection module is mostly blocked after passing through the second quarter-wave plate due to misalignment of the first quarter-wave plate, the first polarizer, and the second quarter-wave plate, a small portion of the first linearly polarized light may still pass through the first polarizer. This first linearly polarized light, after passing through the first polarizer, passes through the first quarter-wave plate again and is reflected back by the target. After passing through the first quarter-wave plate again, its polarization state is converted to second linearly polarized light, which can then be absorbed again by the first polarizer. Therefore, the first polarization state conversion component based on the above-described structure two has a two-stage suppression effect on the echo signal reflected from the detection module, resulting in high crosstalk isolation and thus helping to further improve the accuracy of target identification by the detection device.

[0158] Structure 3, the first polarization state conversion component includes a first polarizer, a second half-wave plate and a second quarter-wave plate.

[0159] like Figure 7 The diagram shown illustrates the structure of another first polarization state conversion component provided in this application. This first polarization state conversion component sequentially includes a first polarizer, a second half-wave plate, and a second quarter-wave plate. Based on this structure, the combination of the second half-wave plate and the second quarter-wave plate can eliminate dispersion, thereby enabling the detection device to effectively suppress crosstalk even when wavelength drift occurs at high or low temperatures. Exemplarily, the first polarizer is bonded to one side of the second half-wave plate, and the other side of the second half-wave plate is bonded to the second quarter-wave plate.

[0160] In one possible implementation, the angle between the equivalent optical axis of the second quarter-wave plate and the second half-wave plate and the polarization direction of the first polarizer is 45 ± 0.2°.

[0161] Based on the above Figure 7The first polarization state conversion component shown receives echo signals from the first lens group that are linearly polarized. The propagation optical path of the echo signal in the first polarization state conversion component can be found in [reference needed]. Figure 8 Specifically: the echo signal of the first linearly polarized light passes through the first polarizer and propagates to the second half-wave plate; the echo signal of the first linearly polarized light is converted into an echo signal of the second linearly polarized light after passing through the second half-wave plate and propagates to the second quarter-wave plate; the echo signal of the second linearly polarized light is converted into an echo signal of the first circularly polarized light after passing through the second quarter-wave plate and propagates to the detection module; the echo signal of the first circularly polarized light is reflected by the detection module to the second quarter-wave plate; the second quarter-wave plate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into an echo signal of the first linearly polarized light and propagates to the second half-wave plate; the echo signal of the first linearly polarized light is converted into an echo signal of the second linearly polarized light after passing through the second half-wave plate and propagates to the first polarizer; the echo signal of the second linearly polarized light is absorbed after passing through the first polarizer.

[0162] Structure four, the first polarization state conversion component includes a first quarter wave plate, a first polarizer, a second half wave plate and a second quarter wave plate.

[0163] like Figure 9 The diagram shown is a structural schematic of another first polarization state conversion component provided in this application. The first polarization state conversion component sequentially includes a first quarter-wave plate, a first polarizer, a second half-wave plate, and a second quarter-wave plate. Exemplarily, the first quarter-wave plate is glued to one side of the first polarizer, the other side of the first polarizer is glued to one side of the second half-wave plate, and the other side of the second half-wave plate is glued to the second quarter-wave plate.

[0164] In one possible implementation, the angle between the optical axis of the first quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°; and the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0165] Based on the above Figure 9 The first polarization state conversion component shown receives echo signals from the first lens group that are circularly polarized. The propagation optical path of the echo signal in the first polarization state conversion component can be found in [reference needed]. Figure 10Specifically: the echo signal of the first circularly polarized light is converted into an echo signal of the first linearly polarized light after passing through the first quarter-wave plate, and propagates to the first polarizer; the echo signal of the first linearly polarized light passes through the first polarizer and propagates to the second half-wave plate; the echo signal of the first linearly polarized light is converted into an echo signal of the second linearly polarized light after passing through the second half-wave plate, and propagates to the second quarter-wave plate; the echo signal of the second linearly polarized light is converted into an echo signal of the first circularly polarized light after passing through the second quarter-wave plate, and propagates to the detection module; the echo signal of the first circularly polarized light... The wave signal is reflected by the detection module to the second quarter-wave plate; the echo signal with the first circular polarization state is converted into the echo signal with the first linear polarization state after passing through the second quarter-wave plate again. That is, the second quarter-wave plate is also used to convert the echo signal with the first circular polarization state reflected by the detection module into the echo signal with the first linear polarization state, and propagate it to the second half-wave plate; the echo signal with the first linear polarization state is converted into the echo signal with the second linear polarization state after passing through the second half-wave plate, and propagates to the first polarizer; the echo signal with the second linear polarization state is absorbed after passing through the first polarizer.

[0166] Based on the above structure four, through Figure 10 In the optical path shown, if the echo signal reflected back from the detection module is blocked by the second quarter-wave plate due to misalignment of the first quarter-wave plate, the first polarizer, the second half-wave plate, and the second quarter-wave plate, a small portion of the first linearly polarized light may still pass through the first polarizer. This first linearly polarized light then passes through the first quarter-wave plate again and is reflected back by the target. After passing through the first quarter-wave plate again, its polarization state is converted to second linearly polarized light, which can then be absorbed again by the first polarizer. Therefore, the first polarization state conversion component based on the above-described structure four has a double suppression effect on the echo signal reflected from the detection module, resulting in high crosstalk isolation and thus helping to further improve the accuracy of target identification by the detection device. Furthermore, the combination of the second half-wave plate and the second quarter-wave plate can eliminate dispersion, allowing the detection device to effectively suppress crosstalk even when wavelength drift occurs at high or low temperatures.

[0167] Structure 5, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, and a second quarter wave plate.

[0168] like Figure 11The diagram shown is a structural schematic of another first polarization state conversion component provided in this application. The first polarization state conversion component sequentially includes a first quarter-wave plate, a first half-wave plate, a second polarizer, and a second quarter-wave plate. Exemplarily, one side of the first quarter-wave plate and the first half-wave plate are glued together, the other side of the first half-wave plate is glued together with one side of the second polarizer, and the other side of the second polarizer is glued together with the second quarter-wave plate.

[0169] It should be noted that the angle between the polarization direction of the first polarizer and the polarization direction of the second polarizer is 90 degrees.

[0170] In one possible implementation, the angle between the equivalent optical axes of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°; and the angle between the optical axis of the second quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0171] Based on the above Figure 11 The first polarization state conversion component shown receives echo signals from the first lens group that are circularly polarized. The propagation optical path of the echo signal in the first polarization state conversion component can be found in [reference needed]. Figure 12 Specifically: the echo signal of the first circularly polarized light is converted into the first linearly polarized light after passing through the first quarter waveplate and propagates to the first half waveplate; the echo signal of the first linearly polarized light is converted into the second linearly polarized light after passing through the first half waveplate and propagates to the second polarizer; the echo signal of the second linearly polarized light passes through the second polarizer and propagates to the second quarter waveplate; the echo signal of the second linearly polarized light is converted into the first circularly polarized light after passing through the second quarter waveplate and propagates to the detection module; the second quarter waveplate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into the first linearly polarized light and propagates to the second polarizer; the echo signal of the first linearly polarized light is absorbed after passing through the second polarizer.

[0172] Based on the above structure five, through Figure 12In the optical path shown, if the echo signal reflected back from the detection module is blocked by the second quarter-wave plate due to misalignment of the first quarter-wave plate, the first half-wave plate, the second polarizer, and the second quarter-wave plate, a small portion of the second linearly polarized light may still pass through the second polarizer. This second linearly polarized light then passes through the first half-wave plate and the first quarter-wave plate again before being reflected back by the target. After passing through the first half-wave plate and the first quarter-wave plate again, its polarization state is converted to first linearly polarized light, which can then be absorbed again by the second polarizer. Therefore, the first polarization state conversion component based on the above structure five has a double suppression effect on the echo signal reflected from the detection module, resulting in high crosstalk isolation and thus helping to further improve the accuracy of target identification by the detection device. Furthermore, the combination of the first half-wave plate and the first quarter-wave plate can eliminate dispersion, allowing the detection device to effectively suppress crosstalk even when wavelength drift occurs at high or low temperatures.

[0173] Structure 6, the first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, a second half wave plate and a second quarter wave plate.

[0174] like Figure 13 The diagram shown is a structural schematic of another first polarization state conversion component provided in this application. The first polarization state conversion component sequentially includes a first quarter wave plate, a first half wave plate, a second polarizer, a second half wave plate, and a second quarter wave plate.

[0175] In one possible implementation, the angle between the equivalent optical axes of the first quarter-wave plate and the first half-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°; and the angle between the equivalent optical axes of the second quarter-wave plate and the second half-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0176] Based on the above Figure 13 The first polarization state conversion component shown receives echo signals from the first lens group that are circularly polarized. The propagation optical path of the echo signal in the first polarization state conversion component can be found in [reference needed]. Figure 14Specifically: the echo signal of light with a first circular polarization state is converted into an echo signal of light with a first linear polarization state after passing through the first quarter waveplate, and propagates to the first half waveplate; the echo signal of light with a first linear polarization state is converted into an echo signal of light with a second linear polarization state after passing through the first half waveplate, and propagates to the second polarizer; the echo signal of light with a second linear polarization state passes through the second polarizer and propagates to the second half waveplate; the echo signal of light with a second linear polarization state is converted into an echo signal of light with a first linear polarization state after passing through the second half waveplate, and propagates to the second quarter waveplate; the echo signal of light with a first linear polarization state is converted into an echo signal of light with a first linear polarization state after passing through the second half waveplate, and propagates to the second quarter waveplate; the echo signal of light with a first linear polarization state is converted into an echo signal of light with a first linear polarization state after passing through the second half waveplate, and propagates to the second half waveplate; the echo signal of light with a first linear polarization state is converted into an echo signal of light with a first linear polarization state after passing through the first ... second linear polarization state after passing through the second half waveplate, and propagates to the second half waveplate; the echo signal of light with a first linear polarization The echo signal of the polarized light is converted into an echo signal with a second circular polarization state after passing through the second quarter waveplate, and the echo signal with a second circular polarization state propagates through the detection module; the second quarter waveplate is also used to convert the echo signal with a second circular polarization state reflected by the detection module into an echo signal with a second linear polarization state, and propagates the echo signal with a second linear polarization state through the second half waveplate; the echo signal with a second linear polarization state is converted into an echo signal with a first linear polarization state after passing through the second half waveplate; the echo signal with a first linear polarization state is absorbed after passing through the second polarizer.

[0177] It should be noted that the first and second polarizers mentioned above can be absorption-type polarizers.

[0178] It should also be noted that, unless otherwise specified, in the description of the propagation optical path of the first polarization state conversion component of the above six structures, the polarization state of the first beam refers to the polarization state of the first beam entering the detection area.

[0179] The first polarization state conversion components of the above-mentioned structures help to improve the flexibility of receiver module design.

[0180] II. First Lens Group

[0181] In one possible implementation, the first lens assembly is used to receive the echo signal from the detection region for the first beam and to converge the echo signal to the first polarization state conversion assembly.

[0182] Exemplarily, the first lens group can be a single spherical lens, multiple spherical lenses, a single aspherical lens, or multiple aspherical lenses, etc. The single lens can be a concave-convex lens; the multiple spherical lenses can be a combination of convex and concave lenses, a combination of concave lenses, or a combination of convex lenses. Since convex and concave lenses have various shapes, for example, convex lenses include biconvex lenses, plano-convex lenses, and concave-convex lenses; concave lenses include biconcave lenses, plano-concave lenses, and concave-convex lenses. The specific shape of the convex and concave lenses is not limited here; any single lens or combination of multiple lenses that can transmit the echo signal from the detection area to the detection module as much as possible is applicable to this application. Further, optionally, the first lens group can also be used to collect as much echo signal as possible after the target reflects the first beam, thereby improving the detection range and sensitivity of the detection device. Therefore, when the aperture of the first lens group facing the detection area is large, more echo signals can be received.

[0183] like Figure 15 The diagram shown is a schematic representation of a first lens group provided in this application. The first lens group may include a concave-convex lens. The concave surface of the concave-convex lens faces the detection area to receive, as much as possible, the echo signal from the detection area for the first beam.

[0184] It should be noted that any structure of the detection module can be used to propagate the echo signal; the first lens group is just one possible example.

[0185] III. Launch Module

[0186] In one possible implementation, the transmitting module is used to emit a first beam into the detection region. Further, optionally, the polarization state of the first beam incident on the detection module can be either linearly polarized or circularly polarized. The following describes different cases based on the polarization state of the first beam emitted by the transmitting module.

[0187] In scenario 1, the polarization state of the first beam emitted by the transmitting module into the detection area is first linearly polarized light.

[0188] Based on scenario 1, the transmitting module may include a light source module, which is used to emit a first beam of light with a first linear polarization state and direct the first beam of light with a first linear polarization state toward the detection area.

[0189] In scenario 2, the polarization state of the first beam emitted by the transmitting module into the detection area is the first circularly polarized light.

[0190] Based on scenario 2, the structures of three possible transmission modules are illustrated below as examples.

[0191] Structure 1, the transmitting module includes a light source module and a second polarization state conversion component, wherein the second polarization state conversion component includes a third 1 / 4 wave plate.

[0192] In one possible implementation, the light source module is used to emit a first beam with a first linearly polarized state; a third quarter-wave plate is used to convert the first beam with the first linearly polarized state into a first beam with the first circularly polarized state. The propagation optical path of the emission module based on this structure can be found in [reference needed]. Figure 16a The light source module emits a first beam of light with a first linear polarization state and propagates to the third 1 / 4 wave plate; the first beam of light with a first linear polarization state is converted into a first beam of light with a first circular polarization state after passing through the third 1 / 4 wave plate.

[0193] Structure 2, the transmitting module includes a light source module and a second polarization state conversion component, wherein the second polarization state conversion component includes a third 1 / 2 wave plate and a third 1 / 4 wave plate.

[0194] In one possible implementation, the light source module is used to emit a first beam with a second linearly polarized state; a third half-wave plate is used to convert the first beam with the second linearly polarized state into a first beam with the first linearly polarized state; and a third quarter-wave plate is used to convert the first beam with the first linearly polarized state into a first beam with the first circularly polarized state. The propagation optical path of the emission module based on this structure can be found in [reference needed]. Figure 16b The light source module is used to emit a first beam with a second linear polarization state and propagate it to the third half-wave plate. The first beam with a second linear polarization state is converted into a first beam with a first linear polarization state after passing through the third half-wave plate. The first beam with a first linear polarization state is converted into a first beam with a first circular polarization state after passing through the third quarter-wave plate.

[0195] Structure 3, the emitting module includes a light source module.

[0196] In one possible implementation, the light source module is used to emit a first beam of light with a first circular polarization state and to direct the first beam of light with the first circular polarization state into the detection area.

[0197] It should be noted that the aforementioned light source module can be a distributed feedback (DFB) laser or a distributed bragg reflector (DBR) laser. The wavelength range of the first beam emitted by the light source module can be in the 1550nm band, or in the 905nm band, or in the 940nm band. It should be understood that, typically, the polarization state of the beam emitted by the light source module is linearly polarized.

[0198] Further, optionally, the transmitting module may also include a second lens group, which may be a single lens or multiple lenses. The lens may be a simple spherical lens or an aspherical lens, such as a concave lens or a convex lens. A single lens may be a convex lens; the lens group may be a combination of convex and concave lenses, a combination of concave lenses, or a combination of convex lenses. Since convex and concave lenses have various shapes, for example, convex lenses include biconvex lenses, plano-convex lenses, and concave-convex lenses; concave lenses include biconcave lenses, plano-concave lenses, and concave-convex lenses. The specific shape of the convex and concave lenses is not limited here; any single lens or combination of multiple lenses that can transmit the first beam from the light source module to the detection area as much as possible is applicable to this application. Further, optionally, since the divergence angle of the first beam from the light source module may be relatively large, and there may be beams with poor astigmatism, the transmitting module may also collimate and shape the first beam, thereby reducing the divergence angle of the first beam emitted to the detection area and allowing more of the first beam to illuminate the detection area.

[0199] like Figure 17 The diagram shown is a structural schematic of a second lens group provided in this application. The second lens group uses three lenses as an example: a concave-convex lens 1, a concave-convex lens 2, and a biconvex lens 3, in sequence. Specifically, the surface of the concave-convex lens 1 facing the light source module is concave, and the surface facing the concave-convex lens 2 is convex; the surface of the concave-convex lens 2 facing the concave-convex lens 1 is convex, and the surface facing the biconvex lens 3 is concave.

[0200] Based on the possible structures of the transmitting module and the receiving module described above, the following are exemplary examples of possible combinations of the transmitting module and the receiving module.

[0201] In scenario 1, the transmitting module is structure 1 as described in scenario 2 above. Based on the different structures of the receiving module, there are five possible scenarios as follows.

[0202] In scenario 1.1, the transmitting module is structure 1 in scenario 2 above, and the receiving module is structure one above.

[0203] Here, the second polarization state conversion component includes a third quarter-wave plate, and the first polarization state conversion component includes a first polarizer and a second quarter-wave plate. The angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0204] In scenario 1.2, the transmitting module is structure 1 as described in scenario 2 above, and the receiving module is structure 2 as described above.

[0205] Here, the second polarization state conversion component includes a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first polarizer, and a second quarter-wave plate. The angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0206] Further, optionally, the polarization direction of the first beam of linearly polarized light emitted by the light source module is parallel to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam of linearly polarized light emitted by the light source module is orthogonal to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is orthogonal to the optical axis of the third quarter-wave plate.

[0207] In scenario 1.3, the transmitting module is structure 1 as described in scenario 2 above, and the receiving module is structure 4 as described above.

[0208] Here, the second polarization state conversion component includes a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first polarizer, a second half-wave plate, and a second quarter-wave plate. The angle between the optical axis of the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0209] Further, optionally, the polarization direction of the first beam of linearly polarized light emitted by the light source module is parallel to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam of linearly polarized light emitted by the light source module is orthogonal to the polarization direction of the first polarizer, and the optical axis of the first quarter-wave plate is orthogonal to the optical axis of the third quarter-wave plate.

[0210] In scenario 1.4, the transmitting module is structure 1 as described in scenario 2 above, and the receiving module is structure 5 as described above.

[0211] Here, the second polarization state conversion component includes a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first half-wave plate, a second polarizer, and a second quarter-wave plate. The angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0212] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the optical axis of the third quarter-wave plate.

[0213] In scenario 1.5, the transmitting module is structure 1 as described in scenario 2 above, and the receiving module is structure 6 as described above.

[0214] Here, the second polarization state conversion component includes a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first half-wave plate, a second polarizer, a second half-wave plate, and a second quarter-wave plate. The angle between the optical axis of the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0215] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the optical axis of the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the optical axis of the third quarter-wave plate.

[0216] Scenario 2: The transmitting module is structure 2 as described in Scenario 2 above. Based on the different structures of the receiving module, there are also five possible scenarios as follows.

[0217] In scenario 2.1, the transmitting module is structure 2 as described in scenario 2 above, and the receiving module is structure 1 as described above.

[0218] Here, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate, and the first polarization state conversion component includes a first polarizer and a second quarter-wave plate. The angle between the equivalent optical axis of the third half-wave plate and the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0219] In scenario 2.2, the transmitting module is structure 2 as described in scenario 2 above, and the receiving module is structure 2 as described above.

[0220] Here, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first polarizer, and a second quarter-wave plate. The angle between the equivalent optical axis of the third half-wave plate and the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0221] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are parallel to the optical axis of the first quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are orthogonal to the optical axis of the first quarter-wave plate.

[0222] In scenario 2.3, the transmitting module is structure 2 as described in scenario 2 above, and the receiving module is structure 4 as described above.

[0223] Here, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first polarizer, a second half-wave plate, and a second quarter-wave plate. The angle between the equivalent optical axis of the third half-wave plate and the third quarter-wave plate and the polarization direction of the first polarizer is 45 ± 0.5°.

[0224] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are parallel to the optical axis of the first quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the first polarizer, and the equivalent optical axes of the third half-wave plate and the third quarter-wave plate are orthogonal to the optical axis of the first quarter-wave plate.

[0225] In scenario 2.4, the transmitting module is structure 2 as described in scenario 2 above, and the receiving module is structure 5 as described above.

[0226] Here, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first half-wave plate, a second polarizer, and a second quarter-wave plate. The angle between the equivalent optical axis of the third half-wave plate and the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0227] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate.

[0228] In scenario 2.5, the transmitting module is structure 2 as described in scenario 2 above, and the receiving module is structure 6 as described above.

[0229] Here, the second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate, and the first polarization state conversion component includes a first quarter-wave plate, a first half-wave plate, a second polarizer, a second half-wave plate, and a second quarter-wave plate. The angle between the equivalent optical axis of the third half-wave plate and the third quarter-wave plate and the polarization direction of the second polarizer is 45 ± 0.5°.

[0230] Further, optionally, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is parallel to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are parallel to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate; or, the polarization direction of the first beam emitted by the light source module as the first linearly polarized light is orthogonal to the polarization direction of the second polarizer, and the equivalent optical axes of the first quarter-wave plate and the first half-wave plate are orthogonal to the equivalent optical axes of the third half-wave plate and the third quarter-wave plate.

[0231] It should be noted that when the transmitting module is structure 1 or structure 2 in the above-mentioned case 2, the polarization state of the first beam of light emitted by the transmitting module into the detection area is the first circularly polarized light. Therefore, the receiving module can be case B, structure 2, structure 4, structure 5 and structure 6 in the above-mentioned structure 1.

[0232] It should also be noted that the transmitting module can be scenario 1 as described above, and the receiving module can be structure 3 as described above; or, the transmitting module can be structure 3 in scenario 2 as described above, and the receiving module can be scenario B, structure 2, structure 4, structure 5 or structure 6 in structure 1 as described above; these will not be repeated here.

[0233] The materials of the first quarter-wave plate, second quarter-wave plate, third quarter-wave plate, first polarizer, and second polarizer mentioned above can be plastic or glass. The first quarter-wave plate, second quarter-wave plate, and third quarter-wave plate are usually zero-order quarter-wave plates, which helps to achieve better suppression of large-angle echo signals reflected by the detection module.

[0234] IV. Detection Module

[0235] In one possible implementation, the detection module can be used to perform photoelectric conversion on the received echo signal to obtain an electrical signal, which is used to determine information about the target in the detection area. Furthermore, the detection module can also be used to reflect a portion of the received echo signal. Alternatively, the detection module can be used to receive the echo signal from the first polarization state conversion component, perform photoelectric conversion on most of the received echo signal, and reflect a small portion.

[0236] For example, the detection module can be a photodetector (PD), SPAD, P-type semiconductor-intrinsic-N-type semiconductor (positive intrinsic negative, PIN) photodiode (also known as a PIN junction diode), or avalanche photodiode (APD); the detector array can be a SPAD array, a PIN photodiode array, or an APD array, etc. Among them, SPAD is a photodetector avalanche diode with single-photon detection capability. It has high sensitivity, and is triggered when a single photon is detected. After triggering, it typically takes about 10 ns to recover to the initial state, so it is widely used in lidar.

[0237] In one possible implementation, the first polarization state conversion component may be located on the detection module. For example, the first polarization state conversion component may be glued to the protective glass of the detection module, see [reference needed]. Figure 18 This facilitates the fabrication and assembly of the detection device. Alternatively, the first polarization state conversion component can replace the protective glass on the detection module; for example, the first polarization state conversion component can be glued to the detection module. This contributes to the miniaturization of the detection device. It should be noted that the structure of the first polarization state conversion component can be found in the aforementioned description and will not be repeated here.

[0238] In one possible implementation, the detection device may also include a scanning module, which will be described in detail below.

[0239] V. Scanning Module

[0240] In one possible implementation, the scanning module can be used to change the propagation direction of the first beam from the transmitting module to direct the first beam to different positions within the detection area, thereby achieving scanning of the detection area. For example, the scanning module can be used to direct the first beam from the transmitting module to the detection area at different scanning angles to achieve scanning of the detection area.

[0241] In one possible implementation, the scanning module can be a scanner, such as a reflective scanner. Reflective scanners include, but are not limited to, mechanical rotating mirrors or microelectromechanical system (MEMS) mirrors. Reflective scanners change the scanning angle through mechanical rotation, thereby enabling the scanner to scan the detection area in different directions. Optionally, the scanner can operate in a continuous mode or a step-by-step mode; this application does not limit this.

[0242] For example, the detection device can preset multiple scanning angles, and the scanning module can direct the first beam from the transmitting module toward the detection area at each of the multiple different scanning angles. Figure 19a The diagram shown is a structural schematic of a scanner provided in this application. This scanner can change its scanning angle in two dimensions (horizontal and vertical directions), which can also be understood as placing the scanner at different scanning angles. Further, optionally, the processing module can control the scanner to rotate in the two dimensions, placing the scanner at different scanning angles and directing the first beam from the transmitting module toward the detection area. For example, the processing module can control the scanner to rotate first horizontally and then vertically, or first vertically and then horizontally, or rotate both vertically and horizontally together, or rotate alternately in the horizontal and vertical directions, thereby achieving scanning of the detection area.

[0243] like Figure 19b The diagram shown is a structural schematic of another scanner provided in this application. This scanner can change its scanning angle in a one-dimensional direction (horizontal direction), allowing the scanner to operate at different scanning angles. The one-dimensional scanner further simplifies the size of the detection device and helps simplify the processing module's control over the scanner's complexity.

[0244] In another possible implementation, the scanning module's function can also be achieved through an optical phased array (OPA). The OPA works by adjusting the phase relationship between the light waves radiated from each phased array unit (such as an optical phase shifter), ensuring they are in phase in a set direction. This results in mutually reinforcing interference, producing a high-intensity beam in that direction. In other directions, the light waves emitted from the phased array units do not meet the condition of being in phase, and their interference cancels each other out, thus the radiation intensity approaches zero. Under the control of the processing module, each phased array unit can scan one or more high-intensity laser beams according to a designed direction.

[0245] It should be understood that the detection device typically consists of two isolated optical paths (i.e., a transmitting optical path and a receiving optical path), which do not affect each other. For example, the echo signal of the first beam may not pass through this scanning module.

[0246] It should be noted that the detection device may also include other modules, such as a processing module, which can be used to receive electrical signals from the detection module and determine the target information based on the received electrical signals.

[0247] Based on the structure and functional principles of the detection device described above, this application can also provide a lidar. This lidar may include the detection device in any of the above embodiments. Further, optionally, the lidar may also include a processing module, which can be used to receive electrical signals from the detection device and determine target information based on the received electrical signals.

[0248] Based on the structure and functional principles of the detection device described above, this application can also provide a terminal device, which may include the detection device in any of the above embodiments. Further, optionally, the terminal device may also include a processor, which can be used to receive electrical signals from the detection device and determine target information based on the received electrical signals.

[0249] Furthermore, optionally, the processor can also plan the driving path of the terminal device based on the determined target information, such as avoiding obstacles in the driving path. Of course, the terminal device may also include other components, such as memory and wireless communication devices.

[0250] For example, the terminal device may include vehicles (such as driverless cars, smart cars, electric cars, digital cars, etc.), robots, surveying equipment, drones, smart home devices, smart manufacturing equipment, or smart transportation equipment (such as automated guided vehicles (AGVs) or unmanned transport vehicles, etc.).

[0251] like Figure 20 The diagram shows a schematic representation of a detector provided in this application. The detector may include a detection module 2001 and a first polarization state conversion component 2002. The first polarization state conversion component 2002 is used to receive an echo signal from the detection area corresponding to a first beam emitted by the transmitting module, and to propagate the echo signal back to the detection module. Here, the echo signal corresponding to the first beam emitted by the transmitting module is the aforementioned echo signal for the first beam. The detection module 2001 is used to convert the received echo signal into an electrical signal, which is used to determine information about a target in the detection area. The first polarization state conversion component 2002 is also used to convert the polarization state of the echo signal reflected by the detection module to achieve absorption of the echo signal reflected by the detection module.

[0252] Based on the aforementioned detector, the first polarization state conversion component can convert the polarization state of the echo signal reflected by the detection module to absorb the echo signal reflected by the detection module. In this way, the echo signal reflected by the detection module will not re-enter the detection module, thus helping to avoid optical crosstalk between the echo signal reflected by the detection module and the echo signal from the detection area.

[0253] For possible implementations of the detection module 2001, please refer to the aforementioned description of the detection module 203. For possible implementations of the first polarization state conversion component 2002, please refer to the aforementioned description of the first polarization state conversion component 2022. These details will not be repeated here.

[0254] In one possible implementation, the first polarization state conversion component 2002 may be located on the detection module 2001. For example, the first polarization state conversion component 2002 may be bonded to the protective glass of the detection module 2001; or, the first polarization state conversion component 2002 may replace the protective glass on the detection module 2001.

[0255] Based on the structure and functional principles of the detector described above, this application can also provide a lidar, which may include the detector in any of the above embodiments. Further, optionally, the lidar may also include a processor, which can be used to receive electrical signals from the detector and determine target information based on the received electrical signals.

[0256] Based on the structure and functional principles of the detector described above, this application can also provide a terminal device, which may include the detector in any of the above embodiments. Further, optionally, the terminal device may also include a processor. The processor in the terminal device can be used to receive electrical signals from the detector and determine target information based on the electrical signals.

[0257] Furthermore, optionally, the processor can also plan the driving path of the terminal device based on the determined target information, such as avoiding obstacles in the driving path. Of course, the terminal device may also include other components, such as memory and wireless communication devices.

[0258] For example, the terminal device may include vehicles (such as driverless cars, smart cars, electric cars, digital cars, etc.), robots, surveying equipment, drones, smart home devices, smart manufacturing equipment, or smart transportation equipment (such as automated guided vehicles (AGVs) or unmanned transport vehicles, etc.).

[0259] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0260] In this application, "uniform" does not refer to absolute uniformity; a certain degree of error is permissible. "Vertical" does not refer to absolute verticality; a certain degree of error is permissible. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects are in an "or" relationship. In the formulas of this application, the character " / " indicates that the preceding and following related objects are in a "division" relationship. For example, "1 / 2" and "1 / 4" mentioned above. Additionally, in this application, the term "exemplarily" is used to indicate an example, illustration, or explanation. Any embodiment or design scheme described as an "example" in this application should not be construed as superior or more advantageous than other embodiments or design schemes. Alternatively, it can be understood that the use of the term "example" is intended to present concepts in a specific manner and does not constitute a limitation on this application.

[0261] It is understood that the various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and inherent logic. Terms such as "first," "second," and similar expressions are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0262] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely illustrative examples of the solutions defined by the appended claims and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application.

[0263] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of the invention. Therefore, if these modifications and variations of the embodiments of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A detection device, characterized in that, It includes a transmitting module, a receiving module, and a detection module, wherein the receiving module includes a first lens group and a first polarization state conversion component; The transmitting module is used to transmit the first beam; The first lens group is used to receive the echo signal from the detection area for the first beam and to converge the echo signal to the first polarization state conversion component; The first polarization state conversion component is used to propagate the echo signal from the first lens group to the detection module, and to convert the polarization state of the echo signal reflected by the detection module to achieve absorption of the reflected echo signal; The detection module is used to convert the received echo signal into an electrical signal, and the electrical signal is used to determine the information of the target in the detection area; The first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer and a second quarter wave plate, which are arranged sequentially between the first lens group and the detection module. The polarization state of the echo signal from the first lens group is first circularly polarized light; The first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from the first circularly polarized light to the first linearly polarized light; The first half-wave plate is used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second linearly polarized light. The second polarizer is used to transmit the echo signal of light whose polarization state is second linearly polarized. The second quarter-wave plate is used to convert the echo signal of the second linearly polarized light into the echo signal of the first circularly polarized light. The second quarter-wave plate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into an echo signal of the first linearly polarized light. The second polarizer is also used to absorb the echo signal of the first linearly polarized light.

2. The detection device as described in claim 1, characterized in that, The first polarization state conversion component also includes a second half-wave plate.

3. The detection device as described in claim 2, characterized in that, The polarization state of the echo signal from the first lens group is first circularly polarized light; The first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from the first circularly polarized light to the first linearly polarized light; The first half-wave plate is used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second linearly polarized light. The second polarizer is used to transmit the echo signal whose polarization state is second linearly polarized light; The second half-wave plate is used to convert the echo signal with the polarization state of second linearly polarized light into an echo signal with the polarization state of first linearly polarized light. The second quarter-wave plate is also used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second circularly polarized light. The second quarter-wave plate is also used to convert the echo signal of the second circularly polarized light reflected by the detection module into an echo signal of the second linearly polarized light. The second half-wave plate is used to convert the echo signal with the polarization state of second linearly polarized light into an echo signal with the polarization state of first linearly polarized light. The second polarizer is also used to absorb the echo signal of the first linearly polarized light.

4. A detection device, characterized in that, It includes a transmitting module, a receiving module, and a detection module, wherein the receiving module includes a first lens group and a first polarization state conversion component; The transmitting module is used to transmit the first beam; The first lens group is used to receive the echo signal from the detection area for the first beam and to converge the echo signal to the first polarization state conversion component; The first polarization state conversion component is used to propagate the echo signal from the first lens group to the detection module, and to convert the polarization state of the echo signal reflected by the detection module to achieve absorption of the reflected echo signal; The detection module is used to convert the received echo signal into an electrical signal, and the electrical signal is used to determine the information of the target in the detection area; The first polarization state conversion component includes a first quarter-wave plate, a first polarizer, a second half-wave plate, and a second quarter-wave plate. The first quarter-wave plate, the first polarizer, the second half-wave plate, and the second quarter-wave plate are arranged sequentially between the first lens group and the detection module. The polarization state of the echo signal from the first lens group is first circularly polarized light; The first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from the first circularly polarized light to the first linearly polarized light; The first polarizer is used to transmit the echo signal whose polarization state is first linearly polarized light; The second half-wave plate is used to convert the echo signal with the first linear polarization state into the echo signal with the second linear polarization state. The second quarter-wave plate is used to convert the echo signal with the polarization state of second linearly polarized light into an echo signal with the polarization state of first circularly polarized light. The second quarter-wave plate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into an echo signal of the first linearly polarized light. The second half-wave plate is also used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second linearly polarized light. The first polarizer is also used to absorb the echo signal of the second linearly polarized light.

5. The detection device according to any one of claims 1 to 4, characterized in that, The emission module includes a light source module and a second polarization state conversion component; The light source module is used to emit a first beam of light with a first linear polarization state; The second polarization state conversion component is used to convert the first beam with a first linear polarization state into a first beam with a first circular polarization state.

6. The detection device as described in claim 5, characterized in that, The second polarization state conversion component includes a third quarter-wave plate.

7. The detection device according to any one of claims 1 to 4, characterized in that, The emission module includes a light source module and a second polarization state conversion component; The light source module is used to emit a first beam of light with a second linear polarization state. The second polarization state conversion component is used to convert the first beam with a second linear polarization state into a first beam with a first circular polarization state.

8. The detection device as described in claim 7, characterized in that, The second polarization state conversion component includes a third half-wave plate and a third quarter-wave plate; The third half-wave plate is used to convert the first beam with the second linear polarization state into a first beam with the first linear polarization state. The third quarter-wave plate is used to convert the first beam with the polarization state of first linearly polarized light into a first beam with the polarization state of first circularly polarized light.

9. The detection device according to any one of claims 1 to 4, characterized in that, The first polarization state conversion component is located on the detection module.

10. A detector, characterized in that, Includes a detection module and a first polarization state conversion component; The first polarization state conversion component is used to receive an echo signal from the detection area corresponding to the first beam emitted by the transmitting module, and to propagate the echo signal to the detection module; The detection module is used to convert the received echo signal into an electrical signal, and the electrical signal is used to determine the information of the target in the detection area; The first polarization state conversion component is further configured to convert the polarization state of the echo signal reflected by the detection module in order to absorb the echo signal reflected by the detection module; The first polarization state conversion component includes a first quarter wave plate, a first half wave plate, a second polarizer, and a second quarter wave plate. The first quarter wave plate, the first half wave plate, the second polarizer, and the second quarter wave plate are arranged sequentially between the first lens group and the detection module. The polarization state of the echo signal from the first lens group is first circularly polarized light; The first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from the first circularly polarized light to the first linearly polarized light; The first half-wave plate is used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second linearly polarized light. The second polarizer is used to transmit the echo signal whose polarization state is second linearly polarized light; The second quarter-wave plate is used to convert the echo signal of the second linearly polarized light into the echo signal of the first circularly polarized light. The second quarter-wave plate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into an echo signal of the first linearly polarized light. The second polarizer is also used to absorb the echo signal of the first linearly polarized light.

11. A detector, characterized in that, Includes a detection module and a first polarization state conversion component; The first polarization state conversion component is used to receive an echo signal from the detection area corresponding to the first beam emitted by the transmitting module, and to propagate the echo signal to the detection module; The detection module is used to convert the received echo signal into an electrical signal, and the electrical signal is used to determine the information of the target in the detection area; The first polarization state conversion component is further configured to convert the polarization state of the echo signal reflected by the detection module in order to absorb the echo signal reflected by the detection module; The first polarization state conversion component includes a first quarter wave plate, a first polarizer, a second half wave plate, and a second quarter wave plate. The first quarter wave plate, the first polarizer, the second half wave plate, and the second quarter wave plate are arranged sequentially between the first lens group and the detection module. The polarization state of the echo signal from the first lens group is first circularly polarized light; The first quarter-wave plate is used to convert the polarization state of the echo signal from the first lens group from the first circularly polarized light to the first linearly polarized light; The first polarizer is used to transmit the echo signal whose polarization state is first linearly polarized light; The second half-wave plate is used to convert the echo signal with the first linear polarization state into the echo signal with the second linear polarization state. The second quarter-wave plate is used to convert the echo signal with the polarization state of second linearly polarized light into an echo signal with the polarization state of first circularly polarized light. The second quarter-wave plate is also used to convert the echo signal of the first circularly polarized light reflected by the detection module into an echo signal of the first linearly polarized light. The second half-wave plate is also used to convert the echo signal with the polarization state of first linearly polarized light into an echo signal with the polarization state of second linearly polarized light. The first polarizer is also used to absorb the echo signal of the second linearly polarized light.

12. A lidar, characterized in that, It includes the detection device as described in any one of claims 1 to 9; or, it includes the detector as described in claim 10 or 11.

13. A terminal device, characterized in that, It includes the detection device as described in any one of claims 1 to 9; or, it includes the detector as described in claim 10 or 11.

14. The terminal device as described in claim 13, characterized in that, The terminal device includes any one of the following: Smartphones, smart home devices, smart manufacturing equipment, or smart transportation equipment.

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