A laser scanning device and a projection imaging apparatus

Abstract

The present disclosure provides a laser scanning device and a projection imaging device, which realizes real-time compensation of the outgoing direction of the scanning beam by adding a hardware level distortion correction component and its control module after the reflection of the galvanometer. In the nonlinear distortion area such as the pillow-shaped distortion and the tilt distortion generated by the galvanometer scanning, the distortion correction component can accurately adjust the beam deflection angle according to the pre-calibrated correction parameter sequence, effectively restore the geometric shape of the scanning pattern, significantly improve the linearity of the point cloud distribution and the overall imaging accuracy, and complete the distortion correction of the full field of view without sacrificing the field of view angle or the resolution, thereby ensuring a wider effective imaging area and more delicate image details. By integrating a special distortion correction component in the optical path, the dependence on the upper image processing algorithm is reduced, the demand for high-performance controllers and complex software operations of the entire system is reduced, and better cost effectiveness and engineering implementation are achieved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of laser scanning technology, and in particular, to a laser scanning device and a projection imaging equipment. BACKGROUND

[0002] A laser scanning device is a device that uses a laser beam to measure, identify or image. When the laser scanning device is used as an imaging device, it can emit a laser beam for imaging, control the direction of the laser beam (i.e. scanning) through a certain mechanism, and image on the imaging surface by using the mechanism of human visual persistence. However, when the laser scanning device images, the distribution of the laser point cloud has nonlinear distortion, such as pillow-shaped distortion and tilt distortion, which causes the scanned pattern to deform.

[0003] Generally, the distortion compensation scheme of the scanned pattern uses a software algorithm to encode the laser sequence of the laser scanning device, emits the laser when the laser scanning is in an area with smaller distortion, and stops emitting the laser when the laser scanning is in an area with larger distortion, so that the image is presented in an area with smaller distortion. However, this way sacrifices part of the field of view and resolution of the laser scanning device. If the same display parameters are to be achieved, the laser scanning device with distortion compensation has higher hardware requirements than the laser scanning device without distortion compensation. SUMMARY

[0004] Embodiments of the present disclosure provide at least a laser scanning device and a projection imaging equipment to solve the problem of loss of field of view and resolution in distortion compensation in the prior art.

[0005] In a first aspect, an embodiment of the present disclosure provides a laser scanning device, comprising a laser emitter, a galvanometer assembly, a distortion correction assembly, and a correction control module;

[0006] The laser emitter is configured to emit a first laser beam;

[0007] The galvanometer assembly is configured to vibrate according to a vibration frequency corresponding to a scanning path, and reflect the first laser beam during the vibration to obtain a second laser beam;

[0008] The distortion correction assembly is configured to correct the emission direction of the second laser beam to obtain an emission beam;

[0009] The correction control module is configured to control the deflection angle of the deflection of the second laser beam by the distortion correction assembly according to a correction parameter sequence corresponding to the scanning path.

[0010] In an optional embodiment, the correction parameter sequence is determined according to the following steps:

[0011] acquire an actual scanning image of the laser scanning device when the distortion correction component is in an initial state, and an ideal scanning image corresponding to the actual scanning image;

[0012] determine second scanning points corresponding to the first scanning points in the ideal scanning image respectively;

[0013] determine a distortion compensation ratio corresponding to the first scanning point based on position information of the first scanning point in an image coordinate system and position information of the second scanning point corresponding to the first scanning point in the image coordinate system; the image coordinate system is a polar coordinate system; a pole of the image coordinate system coincides with a center point of the actual scanning image and the ideal scanning image;

[0014] determine the sequence of correction parameters based on scanning time sequence information of the first scanning point in the scanning path and the distortion compensation ratio corresponding to the first scanning point.

[0015] In an optional implementation, the determination of the second scanning points corresponding to the first scanning points in the ideal scanning image respectively includes:

[0016] for any polar axis in the image coordinate system, sort the first scanning points located on the polar axis according to polar radii of the first scanning points, and sort the third scanning points located on the polar axis according to polar radii of the third scanning points;

[0017] determine the second scanning points corresponding to the first scanning points from the third scanning points based on the sorting orders of the first scanning points and the third scanning points.

[0018] In an optional implementation, the first scanning points are scanning points located at edges of the actual scanning image.

[0019] The determination of the sequence of correction parameters based on the scanning time sequence information of the first scanning point in the scanning path and the distortion compensation ratio corresponding to the first scanning point includes:

[0020] divide the actual scanning image into a plurality of correction regions with the center point of the actual scanning image as a starting point, so that there is a first scanning point in each correction region;

[0021] for any correction region, determine correction parameters corresponding to scanning points located in the correction region based on the distortion compensation ratio corresponding to the first scanning point;

[0022] Based on the scanning timing information of each scanning point under the scanning path, and the correction parameters corresponding to each scanning point, the sequence of correction parameters is determined.

[0023] In one optional embodiment, the distortion correction assembly includes a first zoom lens and a second zoom lens;

[0024] The first zoom lens is used to refract the parallel second laser beam into a converging or diverging third laser beam;

[0025] The second zoom lens is used to refract the third laser beam into a parallel outgoing beam;

[0026] The correction control module is used to control the focal length of the first zoom lens and the second zoom lens according to the correction parameter sequence corresponding to the scanning path.

[0027] In one optional embodiment, the sum of the first focal length of the first zoom lens and the second focal length of the second zoom lens is equal to the distance between the first zoom lens and the second zoom lens.

[0028] In one optional embodiment, the first zoom lens and the second zoom lens are positive lenses; or, the first zoom lens is a negative lens and the second zoom lens is a positive lens.

[0029] In one optional implementation, the distortion correction component is located at the very end of the optical path inside the laser scanning device.

[0030] In one optional implementation, the correction control module is a field-programmable gate array (FPGA).

[0031] Secondly, embodiments of this disclosure also provide a projection imaging device, including a laser scanning device as described in the first aspect above, or in any possible implementation of the first aspect.

[0032] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this disclosure.

[0033] The laser scanning device and projection imaging equipment provided in this disclosure achieve real-time compensation for the emission direction of the scanning beam by adding a hardware-level distortion correction component and its control module after the galvanometer reflection. In nonlinear distortion regions such as pincushion distortion and tilt distortion generated by galvanometer scanning, the distortion correction component can precisely adjust the beam deflection angle according to a pre-calibrated correction parameter sequence, effectively restoring the geometry of the scanned pattern and significantly improving the linearity of the point cloud distribution and the overall imaging accuracy. Unlike the traditional "skip-fire" distortion compensation that uses software algorithms to selectively emit lasers in certain areas, this device does not require pausing emission in high distortion regions, thus completing distortion correction across the entire field of view without sacrificing the field of view or resolution, ensuring a wider effective imaging area and finer image details. By integrating a dedicated distortion correction component into the optical path, the dependence on upper-level image processing algorithms is reduced, lowering the overall system's requirements for high-performance controllers and complex software calculations, resulting in better cost-effectiveness and engineering feasibility.

[0034] To make the above-mentioned objects, features and advantages of this disclosure more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this disclosure and, together with the specification, serve to explain the technical solutions of this disclosure. It should be understood that the following drawings only show some embodiments of this disclosure and should not be considered as limiting the scope. Those skilled in the art can obtain other related drawings based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of a laser scanning apparatus provided in some embodiments of this disclosure is shown;

[0037] Figure 2 A schematic diagram of a distortion correction component provided in some embodiments of this disclosure is shown;

[0038] Figure 3 One of the schematic diagrams showing the imaging effect provided by some embodiments of this disclosure is illustrated;

[0039] Figure 4 A second schematic diagram illustrating the imaging effects provided by some embodiments of this disclosure is shown;

[0040] Figure 5 A schematic diagram of another laser scanning apparatus provided by some embodiments of this disclosure is shown;

[0041] Figure 6 A flowchart illustrating a step for determining a focal length sequence provided by some embodiments of this disclosure is shown;

[0042] Figure 7 This illustration shows one of the schematic diagrams of scan points provided in some embodiments of this disclosure;

[0043] Figure 8 This is a second schematic diagram of scan points provided in some embodiments of the present disclosure;

[0044] Figure 9 A schematic diagram of a projection imaging apparatus provided in some embodiments of the present disclosure is shown. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. The components of the embodiments of this disclosure described and shown herein can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this disclosure is not intended to limit the scope of the claimed disclosure, but merely represents selected embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0046] Research has revealed that laser scanning devices produce distorted images. Typically, distortion compensation schemes employ software algorithms to encode the laser sequence, firing the laser when it reaches areas of low distortion and stopping firing when it reaches areas of high distortion, thus ensuring the image is displayed within the less distorted region. However, this method sacrifices some of the laser scanning device's field of view and resolution. To achieve the same display parameters, laser scanning devices with distortion compensation have higher hardware requirements than those without.

[0047] Based on the above research, this disclosure provides a laser scanning device and a projection imaging device. By adding a hardware-level distortion correction component and its control module after the galvanometer reflection, real-time compensation for the emission direction of the scanning beam is achieved. In nonlinear distortion regions such as pincushion distortion and tilt distortion generated by galvanometer scanning, the distortion correction component can precisely adjust the beam deflection angle according to a pre-calibrated correction parameter sequence, effectively restoring the geometry of the scanned pattern and significantly improving the linearity of the point cloud distribution and the overall imaging accuracy. Unlike the traditional "skip-fire" distortion compensation that uses software algorithms to selectively emit lasers in certain areas, this device does not require pausing emission in high distortion regions. Therefore, it can complete distortion correction across the entire field of view without sacrificing the field of view or resolution, ensuring a wider effective imaging area and finer image details. By integrating a dedicated distortion correction component into the optical path, the dependence on upper-level image processing algorithms is reduced, lowering the overall system's requirements for high-performance controllers and complex software calculations, resulting in better cost-effectiveness and engineering feasibility.

[0048] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure below should be considered as the inventor's contribution to this disclosure.

[0049] It should be noted that similar labels 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.

[0050] See Figure 1 The diagram shown is a schematic of a laser scanning device provided in an embodiment of this disclosure. The device includes a laser emitter 10, a galvanometer assembly 20, a distortion correction assembly 30, and a correction control module 40.

[0051] The laser emitter 10 is used to emit a first laser beam;

[0052] The galvanometer assembly 20 is used to vibrate according to the vibration frequency corresponding to the scanning path, and to reflect the first laser beam during the vibration process to obtain the second laser beam.

[0053] The distortion correction component 30 is used to correct the emission direction of the second laser beam to obtain the emitted beam.

[0054] The correction control module is used to control the deflection angle of the distortion correction component when deflecting the second laser beam according to the correction parameter sequence corresponding to the scanning path.

[0055] The laser emitter 10 described above can be used to emit a first laser beam, i.e., the initial laser light. The laser emitter 10 can be a laser diode, a solid-state laser, a semiconductor-pumped laser, a fiber laser, etc. Its output wavelength can include red light (approximately 650 nm), green light (approximately 532 nm), blue light (approximately 450 nm), etc. The laser emitter 10 can be controlled by a control signal to output laser beams of different colors. For example, the laser emitter 10 can include an RGB three-color laser tube and an optical path for collimation and beam combining.

[0056] The galvanometer assembly 20 can control the oscillation of one or two mirrors in the horizontal and / or vertical directions via electromagnetic drive, thereby controlling the laser direction. In one possible implementation, the galvanometer assembly 20 can be a biaxial galvanometer for achieving two-dimensional planar scanning.

[0057] The first laser beam emitted by the laser emitter 10 is reflected by the galvanometer assembly 20 to form a second laser beam, the direction of which changes with the vibration of the galvanometer assembly 20, forming a scanning trajectory. The galvanometer assembly 20 can control the scanning mode of the laser beam. For example, the scanning mode may include Lissajous scanning, raster scanning, spiral scanning, and linear scanning.

[0058] During scanning, a laser scanning sequence can be generated based on the image to be displayed and the scanning path. The laser emitter 10 can then be controlled according to the laser scanning sequence to emit laser beams of corresponding colors at different times. In this embodiment, distortion correction does not require changes to the laser scanning sequence. Instead, the distortion correction component 30 directly adjusts the emission direction of the second laser beam, performing distortion correction at the hardware level.

[0059] The aforementioned distortion correction component 30 can correct the emission direction of the second laser beam, thereby reducing or offsetting the nonlinear distortion caused by galvanometer scanning. For example, the distortion correction component 30 may include a controllable liquid crystal modulator, an electro-optic modulator, a micro-motor driven mirror, a deformable reflective surface assembly, a variable lens array, etc.

[0060] In one possible implementation, the distortion correction component 30 includes a first zoom lens 31 and a second zoom lens 32; the first zoom lens 31 is used to refract the parallel second laser beam into a converging or diverging third laser beam; the second zoom lens 32 is used to refract the third laser beam into a parallel outgoing beam; the correction control module 40 is used to control the focal length of the first zoom lens 31 and the second zoom lens 32 according to the correction parameter sequence corresponding to the scanning path.

[0061] The correction control module 40 can adjust the focal length of the first zoom lens 31 and the second zoom lens 32 to control the degree of beam divergence or convergence, thereby achieving the purpose of correcting nonlinear distortion of laser scanning.

[0062] The correction control module 40 can be a device with certain computing capabilities, such as a processor, a field-programmable gate array (FPGA), a microcontroller, or a system-on-chip (SOC). It can issue control commands based on the correction parameter sequence corresponding to the scanning path to control the focal length of the first zoom lens 31 and the second zoom lens 32.

[0063] For example, the first zoom lens 31 described above may be a convex lens or a concave lens structure, or a combination of zoom lens groups with adjustable positions (such as a movable lens structure).

[0064] For example, the second zoom lens 32 can form an interleaved zoom combination with the first lens to achieve compensation at different incident angles through synchronous zoom, and its internal optical spacing or focal length can be adjusted by a servo motor or a micro actuator.

[0065] For example, the first zoom lens 31 and the second zoom lens 32 mentioned above can be motorized zoom lenses, liquid zoom lenses, liquid crystal zoom lenses, etc.

[0066] The first zoom lens 31 can refract the parallel second laser beam into a third laser beam with a certain divergence or convergence angle. That is, it performs primary adjustment of the divergence / convergence of the beam. The second zoom lens 32 refracts the third laser beam, which has been processed by the first lens, back into a parallel outgoing beam, thereby restoring the beam collimation and making it suitable for precise imaging.

[0067] In one possible implementation, the positions of the first zoom lens 31 and / or the second zoom lens 32 are adjustable, and the correction control module 40 adaptively adjusts the focal length and position according to the required deflection angle.

[0068] In one possible implementation, the positions of the first zoom lens 31 and / or the second zoom lens 32 are not adjustable, and the correction control module 40 can adjust the focal length according to the required deflection angle.

[0069] See Figure 2The diagram shown is a schematic of the distortion correction component 30 provided in an embodiment of this disclosure. In this embodiment, both the first zoom lens 31 and the second zoom lens are positive lenses (i.e., convex lenses). The second laser beam, reflected by the galvanometer assembly 20, enters the first zoom lens 31. The first zoom lens 31 converges the parallel second laser beam to a focal point. The second laser beam diverges again at the focal point and enters the second zoom lens 32, where it is rerefracted into a parallel outgoing beam.

[0070] In this embodiment, the sum of the first focal length of the first zoom lens 31 and the second focal length of the second zoom lens 32 is equal to the distance between the first zoom lens 31 and the second zoom lens 32. At this time, the first ratio is equal to the second ratio. The first ratio is the ratio between the tangent of the angle between the emitted beam and the optical axis and the tangent of the angle between the second laser beam and the optical axis; the second ratio is the ratio between the first focal length and the second focal length.

[0071] As can be seen from the above, when the distance between the first zoom lens 31 and the second zoom lens 32 remains unchanged, the angle between the emitted beam and the optical axis can be adjusted by adjusting the focal length of the first zoom lens 31 and the second zoom lens 32, thereby achieving the correction of distortion.

[0072] In one possible implementation, the first zoom lens 31 is a negative lens (i.e., a concave lens), and the second zoom lens is a positive lens. In this way, the first zoom lens 31 does not form an actual focal point, and the third laser beam will not be focused between the two zoom lenses. Compared to embodiments where both the first zoom lens 31 and the second zoom lens 32 are positive lenses, the two zoom lenses can be arranged closer together, the distance between the first zoom lens 31 and the second zoom lens 32 is shorter, resulting in a shorter overall system length, making it suitable for space-constrained applications.

[0073] In one possible implementation, the distortion correction component 30 may be located at the very end of the optical path inside the laser scanning device to reduce the impact of the distortion correction component 30 on other components in the optical path.

[0074] When the correction control module 40 controls the deflection angle of the second laser beam, it can determine the control parameters required at each time point based on the correction parameter sequence, and then send control commands for the corresponding control parameters.

[0075] The aforementioned sequence of correction parameters refers to a set of ordered control parameters corresponding to the scanning path of the laser beam. These parameters are used to dynamically adjust the operating state of the distortion correction component, thereby achieving real-time compensation for optical path distortions generated during the scanning process. These control parameters can be arranged sequentially, with each parameter corresponding to a specific scanning state or angle, such as a specific moment, a specific galvanometer angle, or a specific spatial position.

[0076] Correction parameters can refer to control values ​​related to the optical system. For example, they may include the focal length adjustment value of the zoom lens, the relative position adjustment amount of the lens group, the correction coefficient of the deflection angle, and the control electrical signal voltage value.

[0077] This correction parameter sequence can be obtained through offline calibration or generated through preset modeling calculations. For example, the system can scan a standard graphic and record the actual deviation at the factory, and generate the corresponding correction parameters accordingly. During the scanning process, the control module will sequentially retrieve the corresponding correction values ​​from the correction parameter sequence according to the scanning progress and apply them to the distortion correction component to ensure that each scan point is correctly corrected to the target position.

[0078] In one possible implementation, the sequence of correction parameters can be determined through the following steps:

[0079] Acquire the actual scan image of the laser scanning device with the distortion correction component in its initial state, and the ideal scan image corresponding to the actual scan image;

[0080] Determine the second scan points corresponding to the multiple first scan points in the actual scan image in the ideal scan image;

[0081] Based on the position information of the first scan point in the image coordinate system and the position information of the second scan point corresponding to the first scan point in the image coordinate system, the distortion compensation ratio corresponding to the first scan point is determined; the image coordinate system is a polar coordinate system; the pole of the image coordinate system coincides with the center point of the actual scan image and the ideal scan image;

[0082] Based on the scanning timing information of the first scanning point under the scanning path, and the distortion compensation ratio corresponding to the first scanning point, the correction parameter sequence is determined.

[0083] In this embodiment, the first scan point can be a scan point in the actual scanned image, i.e., the distorted position; the second scan point can be the position corresponding to the first scan point in the ideal scanned image. The position of each scan point can be defined by its polar radius and polar angle. In this embodiment, the scanning method can be a Lissajous scanning method.

[0084] During image acquisition, the actual scanned image can be obtained when the distortion correction component is not involved (i.e., in its initial state), along with the corresponding ideal scanned image (e.g., computer-generated or corrected template). Then, the corresponding second scanned points in the ideal image for multiple first scanned points in the actual image can be determined, establishing a one-to-one mapping.

[0085] After obtaining the mapping relationship, the distortion compensation ratio can be calculated. For example, the polar diameter ratio between the first scan point and the corresponding second scan point can be calculated, which indicates the degree of "scaling" or "expansion" that the scan point needs to be performed in the current direction.

[0086] Then, the correction parameter sequence can be generated by combining the scanning timing information. The scanning path is temporal and periodic. For example, the Lissajous scanning method is a scanning method that uses two orthogonal sinusoidal drive signals to control the scanning mirror, thereby generating a Lissajous curve. The distortion compensation ratio of each scanning point can be correlated with its scanning sequence time point to form the final "correction parameter sequence" used to drive the distortion correction component.

[0087] In one possible implementation, the second scan points corresponding to the plurality of first scan points in the actual scan image in the ideal scan image can be determined according to the following steps:

[0088] For any polar axis in the image coordinate system, sort the first scanning points located on the polar axis according to the polar diameter of each first scanning point located on the polar axis in the actual scanned image; and sort the third scanning points located on the polar axis according to the polar diameter of each third scanning point located on the polar axis in the ideal scanned image.

[0089] Based on the sorting order of the first scan point and the third scan point, the second scan point corresponding to the first scan point is determined from the third scan point.

[0090] Thus, this embodiment does not require feature point extraction or geometric registration; it achieves point correspondence only through coordinate sorting, which is simple to calculate, stable in matching, and highly adaptable.

[0091] In one possible implementation, the first scan point is a scan point located at the edge of the actual scanned image. Determining the correction parameter sequence based on the scan timing information of the first scan point along the scan path and the distortion compensation ratio corresponding to the first scan point includes:

[0092] Starting from the center point of the actual scanned image, the actual scanned image is divided into multiple correction regions, such that a first scan point exists in each correction region;

[0093] For any correction region, based on the distortion compensation ratio corresponding to the first scan point, the correction parameters corresponding to each scan point within the correction region are determined;

[0094] Based on the scanning timing information of each scanning point under the scanning path, and the correction parameters corresponding to each scanning point, the sequence of correction parameters is determined.

[0095] In this implementation, since the actual distortion is most severe at the image edges, error data from the edge regions are preferentially selected. Typically, the degree of distortion varies across different polar angle ranges. The actual scanned image can be divided into multiple correction regions, each containing a first scan point. This first scan point is used as the representative point of the correction region. Correction parameters for each scan point within the correction region are generated using the correction parameters of this first scan point. Finally, based on the scanning timing information along the scanning path, a timing mapping is performed, arranging the correction parameters according to the scanning timing sequence. This constructs a time-series sequence of correction parameters for the correction control module 40 to access.

[0096] When using the distortion compensation ratio corresponding to the first scan point to determine the correction parameters corresponding to each scan point within the correction area, the compensation ratio of the edge can be used as the representative value of the area, and the correction parameters corresponding to the first scan point can be directly used as the correction parameters of each scan point within the correction area, thereby reducing the frequency of change of the correction parameters and reducing imaging blur caused by rapid changes in the lens focal length in the distortion correction component 30.

[0097] Alternatively, linear interpolation or weighted interpolation can be performed based on the distances of other points in the region to the center or edge to generate correction parameters for each point in the region, reducing the amount of computation required to determine the correction parameters.

[0098] See Figure 3 as well as Figure 4 , Figure 3 One of the schematic diagrams showing the imaging effect provided by some embodiments of this disclosure is illustrated; Figure 4 This is a second schematic diagram showing the imaging effect provided by some embodiments of the present disclosure. Figure 3 and Figure 4 In the diagram, the solid-lined rectangle represents the imaging effect of the laser scanning device provided in this embodiment, the dashed-lined rectangle represents the imaging effect using software algorithm distortion compensation in related technologies, and the curved area represents the imaging effect without distortion compensation in related technologies. Figure 3 The area enclosed by the curve represents the imaging effect achieved when the normal direction and the laser incident direction are parallel in the static state of the galvanometer. Figure 4 The portion enclosed by the curve represents the imaging effect resulting from non-parallel scanning. It is evident that the laser scanning device provided in this embodiment can significantly improve the field of view and resolution.

[0099] This disclosure provides a laser scanning device that achieves real-time compensation for the emission direction of the scanning beam by adding a hardware-level distortion correction component and its control module after the galvanometer reflection. In nonlinear distortion regions such as pincushion distortion and tilt distortion generated by galvanometer scanning, the distortion correction component can precisely adjust the beam deflection angle according to a pre-calibrated correction parameter sequence, effectively restoring the geometry of the scanned pattern and significantly improving the linearity of the point cloud distribution and overall imaging accuracy. Unlike traditional "skip-fire" distortion compensation that uses software algorithms to selectively emit lasers in certain areas, this device does not require pausing emission in high-distortion regions, thus achieving full-field distortion correction without sacrificing the field of view or resolution, ensuring a wider effective imaging area and finer image details. By integrating a dedicated distortion correction component into the optical path, the reliance on upper-level image processing algorithms is reduced, lowering the overall system's requirements for high-performance controllers and complex software computations, resulting in better cost-effectiveness and engineering feasibility.

[0100] See Figure 5 The diagram shown is a schematic of another laser scanning device provided in an embodiment of this disclosure. The device includes a field-programmable gate array (FPGA), a laser driver board, a digital-to-analog converter (DAC), a laser, a galvanometer, two zoom lenses, and two zoom lens driver boards.

[0101] The FPGA can apply corresponding digital signals to the laser driver board and DAC module based on the time-sequential laser output color information sequence and galvanometer driving voltage sequence generated by image encoding. The laser driver board controls the current flowing through the three-color lasers according to the digital signals from the FPGA, thereby achieving different color outputs. The DAC module receives the digital signals from the FPGA, outputs the corresponding voltage, and drives the galvanometer to vibrate and achieve scanning.

[0102] The FPGA outputs a digital signal to the zoom lens driver board based on the focal length encoding sequence, thereby controlling the electric field distribution on the zoom lens and changing the focal length of the zoom lens. This corrects the angle between the outgoing light and the optical axis, and thus corrects the distortion.

[0103] See Figure 6 , Figure 7 , Figure 6 This is a flowchart illustrating the determination of a focal length sequence provided in some embodiments of this disclosure. Figure 7 This is one of the schematic diagrams of scan points provided in some embodiments of this disclosure.

[0104] Figure 6The steps for determining the correction parameter sequence include: encoding the ideal scanning pattern and the actual scanning pattern to obtain two sets of pixel indices based on time order; given the spatial size of a pixel, the pixel position can be obtained based on the pixel index; establishing a polar coordinate system on the plane containing the scanning pattern with the pattern center as the origin; discretizing the angular coordinates; and statistically analyzing the two sets of pixel indices falling into each set of angular coordinate intervals (i.e., ...). The pixel index is used; for each angular coordinate interval, two sets of pixel indices are sorted according to the radius coordinates, and a mapping is established between the two sets of pixel indices, that is, the mapping is performed sequentially from the small radius coordinate to the large radius coordinate, as shown in the figure. Figure 7 Taking three points as an example, namely a, b, and c are points in the ideal scanning pattern, and A, B, and C are points in the actual scanning pattern, we obtain the mappings A→a, B→b, and C→c. For each mapping, we calculate the scaling ratios S1=Oa / OA, S2=Ob / OB, and S3=Oc / OC, and organize all the calculated scaling ratios into a sequence according to the initial encoding time order. Given the distance L between the two sets of zoom lenses, taking the example that both sets of zoom lenses are positive lenses, corresponding to the aforementioned scaling ratio sequence, taking S1 as an example, we obtain the focal length of lens 1 (i.e., the first zoom lens 31) as (S1*L) / (1+S1) and the focal length of lens 2 (i.e., the second zoom lens 32) as L / (1+S1), thus obtaining the focal length sequence of lens 1 and lens 2 according to the initial encoding time order.

[0105] See Figure 8 , Figure 8 This is a second schematic diagram of scanning points provided in some embodiments of this disclosure. Figure 8 In the diagram, scanning point d represents the scanning point at the edge of the ideal scanning pattern, and D represents the scanning point at the edge of the actual scanning pattern. The angular coordinate range is... The focal length of each scanning point in this angular coordinate interval can be determined based on Od / OD.

[0106] Based on the same inventive concept, this disclosure also provides a projection imaging device. See also Figure 9 This is a projection imaging device provided in an embodiment of the present disclosure, which includes the laser scanning device in any of the above embodiments.

[0107] In one possible implementation, the projection imaging device can be a vehicle-mounted head-up display (HUD) system, an augmented reality (AR) or mixed reality (MR) system, a portable laser projector, a medical image-assisted system, a laser light demonstration and stage display system, etc.

[0108] Finally, it should be noted that the above-described embodiments are merely specific implementations of this disclosure, used to illustrate the technical solutions of this disclosure, and not to limit it. The protection scope of this disclosure is not limited thereto. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this disclosure. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure, and should all be covered within the protection scope of this disclosure. Therefore, the protection scope of this disclosure should be determined by the protection scope of the claims.

Claims

1. A laser scanning device, characterized in that, Includes a laser emitter, a galvanometer assembly, a distortion correction assembly, and a correction control module; The laser emitter is used to emit a first laser beam; The galvanometer assembly is used to vibrate according to the vibration frequency corresponding to the scanning path, and to reflect the first laser beam during the vibration process to obtain the second laser beam. The distortion correction component is used to correct the emission direction of the second laser beam to obtain the emitted beam; The correction control module is used to control the deflection angle of the distortion correction component when deflecting the second laser beam according to the correction parameter sequence corresponding to the scanning path; The sequence of correction parameters is determined according to the following steps: Acquire the actual scan image of the laser scanning device with the distortion correction component in its initial state, and the ideal scan image corresponding to the actual scan image; Determine the second scan points corresponding to the multiple first scan points in the actual scan image in the ideal scan image; Based on the position information of the first scan point in the image coordinate system and the position information of the second scan point corresponding to the first scan point in the image coordinate system, the distortion compensation ratio corresponding to the first scan point is determined; the image coordinate system is a polar coordinate system; the pole of the image coordinate system coincides with the center point of the actual scan image and the ideal scan image; Based on the scanning timing information of the first scanning point under the scanning path, and the distortion compensation ratio corresponding to the first scanning point, the correction parameter sequence is determined; The first scan point is a scan point located at the edge of the actual scanned image; The step of determining the correction parameter sequence based on the scanning timing information of the first scan point under the scanning path and the distortion compensation ratio corresponding to the first scan point includes: Starting from the center point of the actual scanned image, the actual scanned image is divided into multiple correction regions, such that a first scan point exists in each correction region; For any correction region, based on the distortion compensation ratio corresponding to the first scan point, the correction parameters corresponding to each scan point within the correction region are determined; the correction parameters include the correction coefficient for the deflection angle. Based on the scanning timing information of each scanning point under the scanning path, and the correction parameters corresponding to each scanning point, the sequence of correction parameters is determined.

2. The laser scanning device according to claim 1, characterized in that, The step of determining the second scan points corresponding to the multiple first scan points in the actual scan image in the ideal scan image includes: For any polar axis in the image coordinate system, sort the first scanning points located on the polar axis according to the polar diameter of each first scanning point located on the polar axis in the actual scanned image; and sort the third scanning points located on the polar axis according to the polar diameter of each third scanning point located on the polar axis in the ideal scanned image. Based on the sorting order of the first scan point and the third scan point, the second scan point corresponding to the first scan point is determined from the third scan point.

3. The laser scanning device according to claim 1 or 2, characterized in that, The distortion correction assembly includes a first zoom lens and a second zoom lens; The first zoom lens is used to refract the parallel second laser beam into a converging or diverging third laser beam; The second zoom lens is used to refract the third laser beam into a parallel outgoing beam; The correction control module is used to control the focal length of the first zoom lens and the second zoom lens according to the correction parameter sequence corresponding to the scanning path.

4. The laser scanning device according to claim 3, characterized in that, The sum of the first focal length of the first zoom lens and the second focal length of the second zoom lens is equal to the distance between the first zoom lens and the second zoom lens.

5. The laser scanning device according to claim 3, characterized in that, The first zoom lens and the second zoom lens are positive lenses; or, the first zoom lens is a negative lens and the second zoom lens is a positive lens.

6. The laser scanning device according to claim 3, characterized in that, The distortion correction component is located at the very end of the optical path inside the laser scanning device.

7. The laser scanning device according to claim 1, characterized in that, The correction control module is a field-programmable gate array (FPGA).

8. A projection imaging device, characterized in that, Includes the laser scanning device as described in any one of claims 1 to 7.

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