Scanner, scanning system and scanning method

Abstract

The invention provides a scanner, a scanning system and a scanning method, and the scanner comprises a plurality of liquid crystal polarization gratings and a plurality of adjustment platforms. More than or equal to multiple liquid crystal polarization gratings; the liquid crystal polarization gratings are sequentially arranged in the light source transmission direction, and the center points of the liquid crystal polarization gratings are located on the same straight line. Each liquid crystal polarization grating is arranged corresponding to one adjusting platform; the adjusting platform is configured to adjust the rotating speed and the rotating direction of the corresponding liquid crystal polarization grating; the scanner is configured to switch scanning modes by adjusting the rotating speeds and / or the rotating directions of the liquid crystal polarization gratings. According to the invention, the scanner comprises three or more than three liquid crystal polarization gratings, so that a larger view field can be obtained, and the scanner has the potential of large-view-field scanning and three-dimensional imaging. In addition, by adjusting the directions of the liquid crystal polarization gratings, view field coverage of different shapes is achieved, the view field coverage range better conforming to practical application can be obtained, and the flexibility of the view field coverage range is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser scanning, in particular to a scanner, a scanning system and a scanning method. BACKGROUND

[0002] The concept of liquid crystal polarization grating originated from polarization holography proposed in the early 1970s. It is found that the polarization grating can be designed to diffract incident light to a single diffraction order with high efficiency, which makes it naturally suitable for beam steering. Currently, liquid crystal polarization gratings with high efficiency, large area and achromaticity have been realized, which provides a unique opportunity for building high-throughput, wide bandwidth and ultra-compact beam scanning systems based on liquid crystal polarization gratings. A Rayleigh liquid crystal polarization grating has been proposed by rotating two liquid crystal polarization gratings coaxially, which can realize continuous beam scanning. Since the planes of the two liquid crystal polarization gratings are thin and the distance between them is very small, this scheme significantly improves the aspect ratio of the device compared to the Rayleigh prism, and completely eliminates the beam offset problem. The Rayleigh liquid crystal polarization grating is greatly reduced in thickness and weight, and has unique advantages in application scenarios that require large-angle and large-aperture scanning.

[0003] Although the Rayleigh liquid crystal polarization grating as a planar device scanning technology has greatly reduced the thickness and weight, it has the problem of insufficient scanning flexibility in adaptive scale three-dimensional imaging applications. By using a double pair of Rayleigh prism combination, a large field of view and high resolution beam scanning can be achieved, but this scheme inevitably increases the volume and weight of the laser radar system. In addition, by inversely deducing the prism rotation from the beam pointing, an adaptive scale three-dimensional imaging design can be achieved. This scheme can break through the limitations of scanning flexibility and field of view coverage, but it needs to introduce additional motion control time cost. Therefore, the current Rayleigh liquid crystal polarization grating beam scanner is difficult to achieve large field of view coverage due to the limitations of structure and scanning efficiency. SUMMARY

[0004] Therefore, the purpose of the embodiments of the present application is to provide a scanner, a scanning system and a scanning method, which can obtain a larger field of view scanning range and three-dimensional imaging potential.

[0005] In a first aspect, the embodiments of the present application provide a scanner, comprising: a plurality of liquid crystal polarization gratings and a plurality of adjustment platforms; wherein the number of liquid crystal polarization gratings is greater than or equal to three; the plurality of liquid crystal polarization gratings are arranged in sequence along the transmission direction of the light source, and the center points of the plurality of liquid crystal polarization gratings are on the same straight line; each liquid crystal polarization grating is arranged correspondingly to an adjustment platform; the adjustment platform is configured to adjust the rotation speed and rotation direction of the corresponding liquid crystal polarization grating; wherein the scanner is configured to switch the scanning mode by adjusting the rotation speed and / or rotation direction of the plurality of liquid crystal polarization gratings.

[0006] In the implementation process, by setting three or more liquid crystal polarization gratings in the scanner, a larger field of view can be obtained, and the scanner has the potential of large field of view scanning and three-dimensional imaging. In addition, by adjusting the directions of the plurality of liquid crystal polarization gratings, different shapes of field of view coverage can be achieved, and a field of view coverage range more suitable for actual application can be obtained, thereby improving the flexibility of the field of view coverage range of the scanner.

[0007] In one embodiment, further comprising: a 1 / 4 wave plate and a linear polarizer; the linear polarizer, the 1 / 4 wave plate and the plurality of liquid crystal polarization gratings are sequentially arranged along the transmission direction of the light source; wherein the linear polarizer is configured to convert incident light into linearly polarized light; the 1 / 4 wave plate is configured to convert the linearly polarized light into circularly polarized light; and the plurality of liquid crystal polarization gratings are configured to scan the circularly polarized light to form corresponding scanning trajectories.

[0008] In the implementation process, by setting a linear polarizer and a 1 / 4 wave plate before the plurality of liquid crystal polarization gratings, the linear polarizer and the 1 / 4 wave plate can convert the incident light into the circularly polarized light required by the liquid crystal polarization grating, thereby reducing the requirements of the scanner on the light source and increasing the application scenarios of the scanner.

[0009] In one embodiment, the plurality of liquid crystal polarization gratings have the same working wavelength, grating period and size.

[0010] In the implementation process, by setting the plurality of liquid crystal polarization gratings to have the same working wavelength, grating period and size, the influence of these parameters on the calculation of the scanning trajectory can be reduced, and the difficulty of the scanning trajectory calculation can be reduced.

[0011] In one embodiment, the scanning mode includes: a step mode; in the case that one of the plurality of liquid crystal polarization gratings is at a step position and the other liquid crystal polarization gratings rotate independently, the scanning mode is switched to the step mode; wherein the step position is a preset fixed position; wherein, in the case that the scanning mode is the step mode, the liquid crystal polarization grating at the step position is configured to adjust the beam scanning center, and the independently rotating liquid crystal polarization gratings are configured to generate corresponding scanning trajectories.

[0012] In the implementation process, by setting one liquid crystal polarization grating at a step position and the other liquid crystal polarization gratings rotating independently, the scanning mode is switched to the step mode, and then the angle combination of the independently rotating liquid crystal polarization gratings is adjusted to realize the adjustment of the beam scanning trajectory, thereby increasing the types of beam scanning trajectories that the scanner can generate and increasing the application scenarios of the scanner.

[0013] In one embodiment, the scanning mode comprises: a uniform rotation mode; in a case where the plurality of liquid crystal polarization gratings independently rotate at corresponding rotation speeds and phases, the scanning mode switches to the uniform rotation mode; wherein, in a case where the scanning mode is the uniform rotation mode, the plurality of liquid crystal polarization gratings are configured to generate corresponding scanning trajectories by adjusting the rotation speeds and the phases.

[0014] In the above implementation process, by setting the plurality of liquid crystal polarization gratings to independently rotate at corresponding rotation speeds and phases, the scanning mode is switched to the uniform rotation mode, so that the plurality of liquid crystal polarization gratings can generate stable and controllable beam scanning modes, thereby adapting to various three-dimensional imaging requirements and increasing the application scenarios of the scanner.

[0015] In a second aspect, the embodiments of the present application also provide a scanning system, comprising: a laser and the scanner in the first aspect or any one of the embodiments of the first aspect; the laser and the scanner are sequentially arranged along a light source transmission direction; wherein the laser is configured to emit a light source, and the scanner is configured to scan the light source and form a corresponding scanning trajectory.

[0016] In the above implementation process, by setting the scanning system to include a laser and a scanner, and the scanner can be connected to different lasers as an independent module, a plurality of scanning systems are formed, thereby realizing three-dimensional imaging, expanding the field of view, and flexible sampling, and the performance of the scanning system can be improved, and the application scenarios of the scanning system can be increased.

[0017] In a third aspect, the embodiments of the present application also provide a scanning method, applied to the scanner in the first aspect or any one of the embodiments of the first aspect, the method comprising: determining working parameters of a plurality of liquid crystal polarization gratings in the scanner according to a current application scenario of the scanner; calculating a scanning trajectory according to the working parameters and a corresponding direction cosine vector relationship; in a case where the scanning trajectory does not meet the requirements of the current application scenario, adjusting the working parameters of the plurality of liquid crystal polarization gratings, and recalculating the scanning trajectory according to the adjusted working parameters and the corresponding direction cosine vector relationship, until the scanning trajectory meets the requirements of the current scenario.

[0018] In the above implementation process, when the scanner is used, the working parameters of the scanner are adjusted, the scanning trajectory is determined based on the working parameters of the scanner, and it is judged whether the scanning trajectory meets the requirements of the current application scenario based on the scanning trajectory, the working parameters of the scanner are adjusted until the scanning trajectory meets the requirements of the current application scenario. By adjusting the working parameters of the scanner in this way, the scanning trajectory scanned by the scanner can meet the current scenario, and the scanning accuracy of the scanner can be improved.

[0019] In one embodiment, the scanning mode of the scanner comprises a step mode; the working parameters comprise a phase and a rotation speed; in the step mode, the adjusting the working parameters of the plurality of liquid crystal polarization gratings comprises: adjusting the phase of the liquid crystal polarization grating at a step position; wherein the phase of the liquid crystal polarization grating at the step position is configured to maintain a scanning field of view and / or adjust a beam scanning center; adjusting the phase and the rotation speed of the independently rotating liquid crystal polarization grating; wherein the phase and the rotation speed of the independently rotating liquid crystal polarization grating are configured to adjust a scanning trajectory.

[0020] In the above implementation process, in the step mode, by adjusting the phase of the liquid crystal polarization grating at the step position and adjusting the phase and the rotation speed of the independently rotating liquid crystal polarization grating, the adjustment of the beam scanning center and the scanning trajectory can be realized, and then a scanning trajectory meeting the requirements is obtained, thereby increasing the application scenarios of the scanner and improving the accuracy of the scanning trajectory.

[0021] In one embodiment, the scanning mode of the scanner comprises a uniform rotation mode; the working parameters comprise a phase and a rotation speed; in the uniform rotation mode, the adjusting the working parameters of the plurality of liquid crystal polarization gratings comprises: adjusting the phase and the rotation speed of the plurality of independently rotating liquid crystal polarization gratings; wherein the phase and the rotation speed of the plurality of independently rotating liquid crystal polarization gratings are configured to adjust a scanning trajectory.

[0022] In the above implementation process, in the uniform rotation mode, by adjusting the phase and the rotation speed of the plurality of independently rotating liquid crystal polarization gratings, the adjustment of the scanning trajectory can be realized, and then a scanning trajectory meeting the requirements is obtained, thereby increasing the application scenarios of the scanner and improving the sampling capability of the scanner.

[0023] In one embodiment, the working parameters further comprise a deflection; the adjusting the working parameters of the plurality of liquid crystal polarization gratings further comprises: adjusting the deflection of the plurality of liquid crystal polarization gratings; wherein the deflection of the plurality of liquid crystal polarization gratings is configured to adjust the shape of a scanning trajectory.

[0024] In the above implementation process, when adjusting the scanning trajectory, by adding the deflection parameter of the liquid crystal deflection grating, the shape adjustment of the scanning trajectory can be realized, thereby increasing the diversity of the scanning trajectory and thereby increasing the application scenarios of the scanner.

[0025] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following embodiments are specifically described below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 A structural schematic diagram of a scanner provided by the embodiments of the present application is shown in the figure. Figure 2 A structural schematic diagram of a scanner provided by the embodiments of the present application is shown in the figure. Figure 3 A structural schematic diagram of a scanning system provided by the embodiments of the present application is shown in the figure. Figure 4 A flowchart of a scanning method provided by the embodiments of the present application is shown in the figure. Figure 5 In the case that the initial phases of the liquid crystal polarization gratings in the scanner are respectively set to 0° and 90°, corresponding scanning trajectory schematic diagrams are shown in the figures. Figure 6 In the case that the initial phases of the liquid crystal polarization gratings in the scanner are respectively set to 0° and 90°, corresponding scanning trajectory schematic diagrams are shown in the figures. Figure 7 In the case that the initial phases of the liquid crystal polarization gratings in the scanner are respectively set to 0° and 90°, corresponding scanning trajectory schematic diagrams are shown in the figures.

[0028] BRIEF DESCRIPTION OF DRAWINGS: 100-Scanner, 110-Liquid crystal polarization grating, 120-1 / 4 wave plate, 130-linear polarizer, 200-laser. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application.

[0030] It should be noted that: similar labels and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. Meanwhile, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing description, and cannot be understood as indicating or implying relative importance.

[0031] Three-dimensional imaging technology is attracting attention due to its wide application in emerging fields such as autonomous driving and robots, which usually need to rely on visual sensors or lidar to perceive the surrounding environment. Compared with visual sensors which are susceptible to environmental light interference, lidar systems have inherent advantages in detection sensitivity and ranging accuracy, and are widely used in autonomous driving, aerospace, national defense and security, etc.

[0032] In a scanning lidar system, the laser beam needs to be directed to the target position by an optical scanner for ranging, so as to realize three-dimensional imaging within the field of view. Mechanical beam scanners using turntables, galvanometers or polygon mirrors are attracting attention due to their simple principle and mature technology in early scanning lidar systems.

[0033] However, such traditional scanners need to rotate or vibrate as a whole to achieve large field of view beam scanning, resulting in large physical size, high rotational inertia, and low cost performance. Micro-electromechanical system beam scanners can significantly reduce the size of all moving parts through micro-mirror fabrication processes, but they face problems such as increased mechanical fatigue and vibration sensitivity, and are limited by the limited aperture size, making it difficult to achieve a good balance between scanning range and scanning rate. In addition, to achieve two-dimensional scanning, two-axis galvanometers and polygon mirrors are the most widely used scanning mechanisms. However, such devices use off-axis structural design, which often leads to increased system volume and introduces additional errors and structural complexity. As a potential on-axis solution, the Rayleigh prism has the advantages of compact structure, low power consumption, high precision, fast scanning and strong vibration resistance, and can replace traditional off-axis solutions and be suitable for portable and mobile systems. However, due to the structural characteristics of the large volume of the prism, its actual application often faces problems such as limited deflection angle and insufficient scalability.

[0034] Therefore, the present application provides a scanner, by setting three or more liquid crystal polarization gratings in the scanner, a larger field of view can be obtained, and the potential of large field of view scanning and three-dimensional imaging is achieved. In addition, by adjusting the direction of the plurality of liquid crystal polarization gratings, different shapes of field of view coverage can be achieved, and a field of view coverage range more suitable for actual application can be obtained, improving the flexibility of the field of view coverage range of the scanner.

[0035] In order to facilitate the understanding of the present application, first, a scanner disclosed in the present application is introduced in detail.

[0036] As shown in Figure 1 , it is a schematic diagram of the scanner 100, which includes a plurality of liquid crystal polarization gratings 110 and a plurality of adjustment platforms.

[0037] The liquid crystal polarization grating 110 is greater than or equal to three. For example, the liquid crystal polarization grating 110 is three, four, ten, etc. The number of liquid crystal polarization gratings 110 can be adjusted according to actual conditions.

[0038] The plurality of liquid crystal polarization gratings 110 are sequentially arranged along the light source transmission direction, and the center points of the plurality of liquid crystal polarization gratings 110 are on the same straight line. Each liquid crystal polarization grating 110 is arranged in correspondence with an adjustment platform.

[0039] It should be understood that the liquid crystal polarization grating 110 is an optical element that uses the special arrangement of liquid crystal molecules to modulate the polarization state of light waves, thereby achieving precise control of the direction, phase or intensity of light.

[0040] The adjustment platform is configured to adjust the rotation speed and rotation direction of the corresponding liquid crystal polarization grating 110.

[0041] The scanner 100 is configured to switch the scanning mode by adjusting the rotation speed and / or rotation direction of the plurality of liquid crystal polarization gratings 110.

[0042] It can be understood that the adjustment platform can make the plurality of liquid crystal polarization gratings 110 rotate at different speeds in the same direction or in the opposite direction, thereby obtaining scanning trajectories of different shapes such as spiral lines, petal shapes, etc. with different field of view ranges, angular resolutions and sampling density distributions. In addition, by controlling the rotation speed of the plurality of liquid crystal polarization gratings 110, the switching of scanning modes such as step-by-step motion or uniform rotation mode can be realized.

[0043] Optionally, the scanning mode can include a step-by-step mode, a uniform rotation mode, etc. The scanning mode can be set according to actual conditions.

[0044] In an embodiment, the plurality of liquid crystal polarization gratings 110 rotate coaxially.

[0045] The maximum beam diffraction angle can be obtained by the plurality of liquid crystal polarization gratings 110. The maximum beam diffraction angle obtained by different numbers of liquid crystal polarization gratings is different.

[0046] The maximum beam diffraction angle is determined by the ratio of the working wavelength and the period of the liquid crystal polarization grating 110, that is: ; Wherein, is the maximum beam diffraction angle, is the working wavelength of the liquid crystal polarization grating 110, is the period of the liquid crystal polarization grating 110.

[0047] In an embodiment, the scanning time of the scanner 100 in the embodiment is characterized by the number of trajectory points, that is: ; wherein, is a scanning time, is a number of track points.

[0048] In the above implementation process, by setting the scanner 100 including three or more liquid crystal polarization gratings 110, a larger field of view can be obtained, and the potential of large field of view scanning and three-dimensional imaging is achieved. In addition, by adjusting the direction of the plurality of liquid crystal polarization gratings 110, the field of view coverage of different shapes is realized, and a field of view coverage range more in line with actual application can be obtained, and the flexibility of the field of view coverage range of the scanner 100 is improved.

[0049] In a possible implementation, as shown in Figure 2 the scanner 100 further includes a 1 / 4 wave plate 120 and a linear polarizer 130.

[0050] Wherein, the linear polarizer 130, the 1 / 4 wave plate 120 and the plurality of liquid crystal polarization gratings 110 are sequentially arranged along the light source transmission direction.

[0051] The linear polarizer 130 here is an optical element that can selectively transmit light of a specific vibration direction and convert natural light (non-polarized light) into linearly polarized light. Its core principle is based on the polarization phenomenon of light, and the selective transmission of light of a specific direction is realized through the internal structure (such as molecular arrangement, crystal structure or metal wire grid), while the light of other directions is blocked. The linear polarizer 130 is configured to convert incident light into linearly polarized light.

[0052] The 1 / 4 wave plate 120 described above is an optical element that uses the principle of birefringence to change the polarization state of light. Its core function is to realize the conversion between linearly polarized light and circularly polarized light. The 1 / 4 wave plate 120 is configured to convert linearly polarized light into circularly polarized light; In an embodiment, the principle of the 1 / 4 wave plate 120 converting linearly polarized light into circularly polarized light is that when a beam of linearly polarized light is incident on the fast axis / slow axis of the 1 / 4 wave plate 120 at an angle of 45°, its energy is evenly distributed to the fast and slow axes. The π / 2 phase difference introduced by the wave plate will make the vibration of one direction lead the other direction by one-fourth of a period, and the end of the synthesized electric field vector will form a spiral advancing track, that is, circularly polarized light.

[0053] The plurality of liquid crystal polarization gratings 110 described above are configured to scan circularly polarized light and form corresponding scanning tracks.

[0054] Wherein, the circularly polarized light emitted by the light source through the linear polarizer 130 and the 1 / 4 wave plate 120 is incident in the plurality of liquid crystal polarization gratings 110.

[0055] In the implementation process, the linear polarizer 130 and the 1 / 4 wave plate 120 are arranged in front of the plurality of liquid crystal polarization gratings 110, so that the linear polarizer 130 and the 1 / 4 wave plate 120 can convert the incident light into circularly polarized light required by the liquid crystal polarization grating 110, thereby reducing the requirement of the light source for the scanner 100 and increasing the application scenarios of the scanner 100.

[0056] In a possible implementation, the plurality of liquid crystal polarization gratings 110 have the same working wavelength, grating period, and size.

[0057] It should be understood that, by arranging the plurality of liquid crystal polarization gratings 110 to have the same working wavelength, grating period, and size, the performance of the plurality of liquid crystal polarization gratings 110 can be substantially consistent, thereby reducing the influence of the working wavelength, grating period, and size on the scanning trajectory calculation and reducing the difficulty of the scanning trajectory calculation.

[0058] In another embodiment, one or more of the working wavelength, grating period, and size of the plurality of liquid crystal polarization gratings 110 are different. The working wavelength, grating period, and size of the liquid crystal polarization grating 110 can be set according to actual conditions.

[0059] In the implementation process, by arranging the plurality of liquid crystal polarization gratings 110 to have the same working wavelength, grating period, and size, the influence of these parameters on the scanning trajectory calculation can be reduced, and the difficulty of the scanning trajectory calculation can be reduced.

[0060] In a possible implementation, when one of the plurality of liquid crystal polarization gratings 110 is in a stepping position and the other liquid crystal polarization gratings 110 are independently rotated, the scanning mode is switched to a stepping mode.

[0061] The stepping position herein is a preset fixed position. The liquid crystal polarization grating 110 in the stepping position is fixed at the stepping position.

[0062] When the scanning mode is the stepping mode, the liquid crystal polarization grating 110 in the stepping position is configured to adjust the scanning center of the light beam, and the independently rotated liquid crystal polarization gratings 110 are configured to generate corresponding scanning trajectories.

[0063] Exemplarily, as shown in FIG. 2, if the liquid crystal polarization grating 110 is in the stepping position, the liquid crystal polarization grating 110 in the stepping position is fixed at the stepping position. Figure 1 Figure 1 ​LCPG1 in FIG. 1 as a steering element (i.e., in a step position), and LCPG2 and LCPG3 as two scanning elements (i.e., independently rotating), by fixing LCPG1 in the step position, the corresponding beam deflection vector can be uniquely determined. Meanwhile, LCPG2 and LCPG3 rotate at independent rotation speeds and initial phases, respectively. Under different angle combinations, the combined effect of the two beam deflection vectors of LCPG2 and LCPG3 generates a corresponding beam scanning trajectory in the local area of interest.

[0064] wherein the position of the local area of interest depends on the direction of the beam deflection vector, which can be adjusted by adjusting the step position of the liquid crystal polarization grating 110 in the step position.

[0065] In the above implementation process, by setting one liquid crystal polarization grating 110 in the step position and the other liquid crystal polarization gratings 110 independently rotating, the scanning mode is switched to the step mode, and then by adjusting the angle combination of the independently rotating liquid crystal polarization gratings 110, the adjustment of the beam scanning trajectory is realized, thereby increasing the types of beam scanning trajectories that the scanner 100 can generate, and increasing the application scenarios of the scanner 100.

[0066] In a possible implementation, in the case where the plurality of liquid crystal polarization gratings 110 independently rotate at corresponding rotation speeds and phases, the scanning mode is switched to the uniform rotation mode.

[0067] wherein in the case where the scanning mode is the uniform rotation mode, the plurality of liquid crystal polarization gratings 110 are configured to generate corresponding scanning trajectories by adjusting the rotation speeds and phases.

[0068] It should be understood that in the case where the plurality of liquid crystal polarization gratings 110 independently rotate at corresponding rotation speeds and phases, the plurality of liquid crystal polarization gratings 110 form corresponding time-varying rotation angles.

[0069] In the uniform rotation mode, the plurality of liquid crystal polarization gratings 110 respectively apply beam deflection vectors, and the final beam pointing direction of the plurality of liquid crystal polarization gratings 110 can be obtained by superimposing the beam deflection vectors of the plurality of liquid crystal polarization gratings 110.

[0070] In an embodiment, the effect of the beam deflection vector of the liquid crystal polarization grating 110 located behind is affected by the beam deflection vector of the liquid crystal polarization grating 110 in front. For example, Figure 6 the effect of the beam deflection vector of LCPG2 in FIG. 1 is affected by the beam deflection vector of LCPG1, and the effect of the beam deflection vector of LCPG3 is affected by the beam deflection vectors of LCPG1 and LCPG2.

[0071] The uniform rotation mode can enable the plurality of liquid crystal polarization gratings 110 in the scanner 100 to generate a stable and controllable light beam scanning mode, which can meet various three-dimensional imaging requirements of the laser radar.

[0072] In the implementation process, by setting the plurality of liquid crystal polarization gratings 110 to rotate independently at corresponding rotation speeds and phases, the scanning mode is switched to the uniform rotation mode, which can enable the plurality of liquid crystal polarization gratings 110 to generate a stable and controllable light beam scanning mode, thereby adapting to various three-dimensional imaging requirements and increasing the application scenarios of the scanner 100.

[0073] As shown in FIG. 1, Figure 3 is a schematic diagram of a scanning system, which includes a laser 200 and the scanner 100 in the above embodiment.

[0074] The laser 200 and the scanner 100 are sequentially arranged along a light source transmission direction.

[0075] The laser 200 is configured to emit a light source, and the scanner 100 is configured to scan the light source and form a corresponding scanning track. That is, the light source emitted by the laser 200 passes through the scanner 100 to form a corresponding scanning track.

[0076] The scanner 100 described above can be used as an independent module and connected with various types of lasers 200 to form various scanning systems.

[0077] The scanning system described above can realize three-dimensional imaging, extended field of view, flexible sampling and other functions according to direct detection or coherent detection principles.

[0078] In the implementation process, by setting the scanning system to include the laser 200 and the scanner 100, and the scanner 100 can be used as an independent module and connected with different lasers 200 to form various scanning systems, thereby realizing three-dimensional imaging, extended field of view, flexible sampling and other functions, the performance of the scanning system can be improved, and the application scenarios of the scanning system can be increased.

[0079] Please refer to Figure 4 is a flowchart of a scanning method provided by the embodiment of the present application. The specific process shown in Figure 4 will be described in detail below.

[0080] In step S201, the working parameters of the plurality of liquid crystal polarization gratings 110 in the scanner 100 are determined according to the current application scenario of the scanner 100.

[0081] The scanner 100 described above can be applied to various application scenarios, and the plurality of liquid crystal polarization gratings 110 in the scanner 100 can be provided with corresponding working parameters for each application scenario.

[0082] Optionally, the current application scenario of the scanner 100 can be determined directly through input information, can be determined according to a previous working mode of the scanner 100, or can be determined according to current information collected by an information collection device. The determination manner of the current application scenario can be selected according to actual conditions.

[0083] It should be understood that, in the case of determining the current application scenario of the scanner 100, the corresponding working parameter can be matched based on the current application scenario.

[0084] Optionally, the working parameter can include a rotating speed, a phase, a rotating speed ratio, a rotating direction, etc. The working parameter can be selected according to actual conditions.

[0085] In step S202, a scanning track is calculated according to the working parameter and a corresponding direction cosine vector relationship.

[0086] The direction cosine vector relationship refers to a cosine value of an angle between a vector and a coordinate system base vector.

[0087] In an embodiment, the scanning track can be calculated through the following formula: ; ; wherein, is an azimuth angle of the scanning track, , , are time-varying rotating angles of the respective liquid crystal polarization gratings 110, is a working wavelength of the liquid crystal polarization grating 110, is a period of the liquid crystal polarization grating 110, is an elevation angle of the scanning track.

[0088] By converting a combination of the elevation angle of the scanning track and the azimuth angle of the scanning track into a combination of a horizontal scanning angle and a vertical scanning angle, a specific scanning track can be obtained: ; wherein, is the horizontal scanning angle, is the vertical scanning angle.

[0089] It can be understood that the scanning trajectory is analyzed by the diffraction of the circularly polarized light through the plurality of liquid crystal polarization gratings 110. Under normal incidence, the diffraction angle of a single liquid crystal polarization grating 110 is determined only by the grating period and the wavelength, following the grating equation. However, for a plurality of liquid crystal polarization gratings 110 with different relative orientations, the diffraction is more complex due to the nonlinearity of the angular relationship. Therefore, the diffraction process can be analyzed by introducing a direction cosine space, in which the diffraction can be represented as a simple linear vector. The circularly polarized light after the linear polarizer 130 and the 1 / 4 wave plate 120 is diffracted through the plurality of liquid crystal polarization gratings 110 in turn. The direction of the final diffracted light beam can be represented by the superposition of the diffraction vectors of the plurality of liquid crystal polarization gratings 110. Finally, the azimuth angle and the elevation angle of the outgoing light beam are obtained according to the direction cosine vector relationship, thereby obtaining the scanning trajectory.

[0090] Step S203, in the case that the scanning trajectory does not meet the requirements of the current application scenario, adjusting the working parameters of the plurality of liquid crystal polarization gratings 110, and recalculating the scanning trajectory according to the adjusted working parameters and the corresponding direction cosine vector relationship until the scanning trajectory meets the requirements of the current scenario.

[0091] It should be understood that after the scanning trajectory is calculated based on step S202, it can be further determined whether the scanning trajectory meets the requirements of the current application scenario based on the scanning field of view, angular resolution, sampling density, etc. of the scanning trajectory. If the scanning trajectory does not meet the requirements of the current application scenario, the working parameters of the liquid crystal polarization grating 110 are adjusted, and the scanning trajectory is recalculated based on the adjusted working parameters and the corresponding direction cosine vector relationship. It is then determined whether the scanning trajectory meets the requirements of the current application scenario. If it does not, the above steps are continued until the scanning trajectory meets the requirements of the current scenario. If it is determined that the scanning trajectory meets the requirements of the current scenario, the scanner 100 does not need to be adjusted.

[0092] The angular resolution here refers to the minimum angular interval between two objects that can be distinguished by the scanning system, which mainly depends on the beam pointing resolution of the scanner 100, which is related to the rotation resolution of the liquid crystal polarization grating 110. By changing the rotation angles of the plurality of liquid crystal polarization gratings 110 and making them have an offset equal to the rotation resolution, the beam pointing resolution can be inferred from the change in beam deflection angle.

[0093] The sampling density refers to the statistical quantity of beam scanning points in each unit field of view in the horizontal or vertical direction, which can be used to characterize the ability of the scanning system to collect detailed information in three-dimensional space. Since the scanner 100 allows the liquid crystal polarization grating 110 to rotate with different motion laws to produce any desired scanning mode. Thus, the scanning system in which the scanner 100 is located can select the best sampling strategy that meets various three-dimensional imaging applications.

[0094] The scanning mode of the scanner 100 can include a step mode, a uniform rotation mode, and the like.

[0095] It can be understood that the scanner 100 can adopt different adjustment manners when adjusting the working parameters of the liquid crystal polarization grating 110 in different scanning modes.

[0096] In the implementation process, when the scanner 100 is used, the working parameters of the scanner 100 are adjusted, the scanning track is determined based on the working parameters of the scanner 100, and it is determined whether the scanning track meets the requirements of the current application scenario based on the scanning track. The working parameters of the scanner 100 are adjusted until the scanning track meets the requirements of the current application scenario. The working parameters of the scanner 100 are adjusted in this repeated adjustment and determination manner, and the scanning is performed in this manner. The scanning track scanned by the scanner 100 can meet the current scenario, and the scanning accuracy of the scanner 100 is improved.

[0097] In a possible implementation, in the step mode, the working parameters of the plurality of liquid crystal polarization gratings 110 are adjusted, including: adjusting the phase of the liquid crystal polarization grating 110 at the step position; and adjusting the phase and rotation speed of the independently rotating liquid crystal polarization grating 110.

[0098] The phase of the liquid crystal polarization grating 110 at the step position is configured to maintain the scanning field of view and / or adjust the scanning center of the light beam.

[0099] The scanning field of view here refers to the spatial range that can be covered by the scanning system. The liquid crystal polarization grating 110 can adjust the required field of view range covered by the light beam in the scanning process by dynamically adjusting the phase configuration.

[0100] It should be understood that by setting the liquid crystal polarization grating 110 to correspond to a certain phase matching at the step position, it can be ensured that even if the light beam is at different deflection angles, the scanning range can be maintained, thereby maintaining a wide and uniform scanning field of view and avoiding performance degradation.

[0101] The scanning center of the light beam is the reference point of the scanning of the light beam. By changing the phase configuration of the liquid crystal polarization grating 110, the direction of the diffracted light can be adjusted, and thus the scanning center of the light beam can be moved.

[0102] Exemplarily, as shown in FIG. 2, the scanning center of the light beam is adjusted by changing the phase configuration of the liquid crystal polarization grating 110. Figure 5 Figure 5 ​The left and right two figures respectively are the cases that the initial phases of the liquid crystal polarization gratings 110 in the stepping position are respectively set to 0° and 90°, the rotation speed ratio of the two independently rotating liquid crystal polarization gratings 110 is set to 1.02:1.03, the center positions of the scanning fields of view are respectively (15.16°,-0.26°) and (-6.51°,13°), and the sampling density distribution is adjusted by changing the initial phase of the liquid crystal polarization grating 110 in the stepping position while keeping the scanning field of view and the angular resolution unchanged.

[0103] The phases and rotation speeds of the independently rotating liquid crystal polarization gratings 110 are configured to adjust the scanning trajectory.

[0104] In an embodiment, when the phase signs of the plurality of liquid crystal polarization gratings 110 are consistent (i.e., the plurality of liquid crystal polarization gratings 110 rotate in the same direction), spiral scanning can be achieved. When the phase signs of the liquid crystal polarization grating 110 in the stepping position and the other liquid crystal polarization gratings 110 are inconsistent (i.e., the liquid crystal polarization grating 110 in the stepping position and the other liquid crystal polarization gratings 110 rotate in opposite directions), petal-shaped scanning can be achieved.

[0105] In the above implementation process, in the stepping mode, by adjusting the phase of the liquid crystal polarization grating 110 in the stepping position and adjusting the phases and rotation speeds of the independently rotating liquid crystal polarization gratings 110, the adjustment of the beam scanning center and the scanning trajectory can be achieved, and then the scanning trajectory meeting the requirements is obtained, which increases the application scenarios of the scanner 100 and improves the accuracy of the scanning trajectory.

[0106] In a possible implementation, in the uniform rotation mode, the working parameters of the plurality of liquid crystal polarization gratings 110 are adjusted, including adjusting the phases and rotation speeds of the independently rotating plurality of liquid crystal polarization gratings 110.

[0107] The phases and rotation speeds of the independently rotating plurality of liquid crystal polarization gratings 110 are configured to adjust the scanning trajectory.

[0108] It can be understood that, in the scanning process of the scanner 100, by controlling the plurality of liquid crystal polarization gratings 110 to rotate in the same direction or in opposite directions at different speeds, scanning trajectories with different field of view ranges, angular resolutions, and sampling density distributions, such as spiral lines and petal shapes, can be obtained. In addition, by controlling the plurality of liquid crystal polarization gratings 110 to select different rotation speeds, the switching between the stepping motion and the uniform rotation mode can be achieved.

[0109] Exemplarily, as shown in FIG. 6, the liquid crystal polarization grating 110 in the stepping position is rotated in the same direction as the other liquid crystal polarization gratings 110, and the liquid crystal polarization grating 110 in the stepping position is rotated in the opposite direction as the other liquid crystal polarization gratings 110. Figure 6As shown, the left figure selects multiple liquid crystal polarization gratings 110 with initial phases of (0°, 0°, 0°) and rotation speeds of (1, 1.01, 1.02), while the right figure selects multiple liquid crystal polarization gratings 110 with initial phases of (0°, 0°, 0°) and rotation speeds of (1, 1.02, 1.04). When multiple liquid crystal polarization gratings 110 rotate in the same direction but at different speeds, the beam scanning pattern exhibits a spiral shape. Specifically, increasing the difference in rotation speed of the liquid crystal polarization gratings 110 leads to a shorter scanning cycle and a sparser scanning pattern (e.g., ...). Figure 6 (As shown in the scanning trajectory in the right figure), thereby reducing the sampling capability of the lidar system across the entire field of view.

[0110] For example, such as Figure 7 As shown in the figure, the left image selects multiple liquid crystal polarization gratings 110 with initial phases of (0°, 180°, 0°) and rotation speeds of (1, -1, 1.02). The right image selects multiple liquid crystal polarization gratings 110 with initial phases of (0°, 180°, 0°) and rotation speeds of (1, -1.01, 10.99). Thanks to the additional degrees of freedom, the three-tiered liquid crystal polarization grating scanner 100 can flexibly control the beam scanning mode by simultaneously changing the rotation speed, rotation direction, or initial phase of multiple liquid crystal polarization gratings 110, generating scanning patterns of various modes. The uniform rotation mode enables multiple liquid crystal polarization gratings 110 to produce a stable and controllable beam scanning mode, which can adapt to various three-dimensional imaging requirements of the scanning system.

[0111] In the above implementation process, in the uniform rotation mode, by adjusting the phase and rotation speed of the multiple independently rotating liquid crystal polarization gratings 110, the scanning trajectory can be adjusted, thereby obtaining a scanning trajectory that meets the requirements. This increases the application scenarios of the scanner 100 and improves the sampling capability of the scanner 100.

[0112] In one possible implementation, adjusting the operating parameters of the plurality of liquid crystal polarization gratings 110 further includes adjusting the orientation of the plurality of liquid crystal polarization gratings 110.

[0113] The orientation of the multiple liquid crystal polarization gratings 110 is configured to adjust the shape of the scanning trajectory.

[0114] Optionally, if the phase signs of the multiple liquid crystal polarization gratings 110 are consistent (i.e., the multiple liquid crystal polarization gratings 110 rotate in the same direction), a spiral scanning trajectory can be formed. If the phase signs of the liquid crystal polarization grating 110 in the step position are inconsistent with those of the other liquid crystal polarization gratings 110 (i.e., the liquid crystal polarization grating 110 in the step position rotates in opposite directions), a petal-shaped scanning trajectory can be formed. If the phase signs of one of the independently rotating liquid crystal polarization gratings 110 are inconsistent with those of the liquid crystal polarization grating 110 in the step position and the other independently rotating liquid crystal deflection gratings (i.e., one of the independently rotating liquid crystal polarization gratings 110 rotates in opposite directions with those of the liquid crystal polarization grating 110 in the step position and the other independently rotating liquid crystal deflection gratings), an elliptical scanning trajectory can be formed.

[0115] The above embodiments only show a partial implementation of the shape adjustment of the scanning trajectory. The shape adjustment method of the scanning trajectory can be set according to the actual situation.

[0116] In the above implementation process, when adjusting the scanning trajectory, the shape of the scanning trajectory can be adjusted by adding the turning parameters of the liquid crystal deflection grating, thereby increasing the diversity of the scanning trajectory and increasing the application scenarios of the scanner 100.

[0117] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0118] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A scanner characterized by, Comprise: A plurality of liquid crystal polarization gratings and a plurality of adjustment platforms; wherein the liquid crystal polarization grating is greater than or equal to three; A plurality of the liquid crystal polarization gratings are sequentially arranged along the light source transmission direction, and the center points of a plurality of the liquid crystal polarization gratings are on the same straight line; Each of the liquid crystal polarization gratings is correspondingly arranged with one of the adjustment platforms; the adjustment platform is configured to adjust the rotation speed and rotation direction of the corresponding liquid crystal polarization grating; Wherein, the scanner is configured to switch the scanning mode by adjusting the rotation speed and / or rotation direction of a plurality of the liquid crystal polarization gratings.

2. The scanner of claim 1, wherein, Also include: 1 / 4 wave plate and linear polarizer; The linear polarizer, the 1 / 4 wave plate and a plurality of the liquid crystal polarization gratings are sequentially arranged along the light source transmission direction; Wherein, the linear polarizer is configured to convert incident light into linearly polarized light; the 1 / 4 wave plate is configured to convert the linearly polarized light into circularly polarized light; a plurality of the liquid crystal polarization gratings are configured to scan the circularly polarized light to form a corresponding scanning trajectory.

3. The scanner of claim 1 or 2, wherein, Wherein, A plurality of the liquid crystal polarization gratings have the same working wavelength, grating period and size.

4. The scanner of claim 1 or 2, wherein, The scanning mode includes: step mode; In the case that one of the liquid crystal polarization gratings in a plurality of the liquid crystal polarization gratings is in a step position and the other liquid crystal polarization gratings rotate independently, the scanning mode is switched to step mode; wherein the step position is a pre-set fixed position; Wherein, in the case that the scanning mode is step mode, the liquid crystal polarization grating in the step position is configured to adjust the beam scanning center, and the independently rotating liquid crystal polarization gratings are configured to generate a corresponding scanning trajectory.

5. The scanner of claim 1 or 2, wherein, The scanning mode includes: uniform rotation mode; In the case that a plurality of the liquid crystal polarization gratings rotate independently at corresponding rotation speeds and phases, the scanning mode is switched to uniform rotation mode; Wherein, in the case that the scanning mode is uniform rotation mode, a plurality of the liquid crystal polarization gratings are configured to generate a corresponding scanning trajectory by adjusting the rotation speed and the phase.

6. A scanning system characterized by, Comprise: Laser and scanner of any one of claims 1-5; The laser and the scanner are sequentially arranged along the light source transmission direction; Wherein, the laser is configured to emit light source, and the scanner is configured to scan the light source and form a corresponding scanning trajectory.

7. A scanning method characterized by, Applied to the scanner of any one of claims 1-6, the method comprises: According to the current application scenario of the scanner, the working parameters of a plurality of liquid crystal polarization gratings in the scanner are determined; According to the working parameters and the corresponding direction cosine vector relationship, the scanning trajectory is calculated; In the case that the scanning trajectory does not meet the requirements of the current application scenario, the working parameters of a plurality of the liquid crystal polarization gratings are adjusted, and the scanning trajectory is recalculated according to the adjusted working parameters and the corresponding direction cosine vector relationship until the scanning trajectory meets the requirements of the current scenario.

8. The method of claim 7, wherein, Wherein, The scanning mode of the scanner includes step mode; the working parameters include phase and rotation speed; In the step mode, the working parameters of a plurality of the liquid crystal polarization gratings are adjusted, including: adjusting the phase of the liquid crystal polarization grating in the step position; wherein the phase of the liquid crystal polarization grating in the step position is configured to maintain the scan field of view and / or adjust the beam scanning center; adjusting the phase and rotation speed of the independently rotating liquid crystal polarization grating; wherein the phase and rotation speed of the independently rotating liquid crystal polarization grating are configured to adjust the scan trajectory.

9. The method of claim 7, wherein, wherein, the scan mode of the scanner comprises a uniform rotation mode; the working parameters comprise phase and rotation speed; in the uniform rotation mode, the adjusting the working parameters of the plurality of liquid crystal polarization gratings comprises: adjusting the phase and rotation speed of the independently rotating plurality of liquid crystal polarization gratings; wherein the phase and rotation speed of the independently rotating plurality of liquid crystal polarization gratings are configured to adjust the scan trajectory.

10. The method according to claim 8 or 9, characterized in that, wherein, the working parameters further comprise turning direction; the adjusting the working parameters of the plurality of liquid crystal polarization gratings further comprises: adjusting the turning direction of the plurality of liquid crystal polarization gratings; wherein the turning direction of the plurality of liquid crystal polarization gratings is configured to adjust the shape of the scan trajectory.

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