A large-angle projection method and system of multiple MEMS scanners and medium

Abstract

The application discloses a large-angle projection method and system of multiple MEMS galvanometer scanners, and a medium, wherein a high-speed photoelectric converter is placed between adjacent projection units; a galvanometer is driven to vibrate, and a laser is driven to emit point laser; the point laser emitted by the laser sequentially passes through a collimating lens and a linear prism, and is then incident to a surface of the galvanometer, and is reflected to a scanning object surface through the galvanometer, so that a periodic grating pattern is formed; the time delay of the driving signals of multiple lasers is adjusted, and the high-speed photoelectric converter is combined, so that the projection boundaries of two adjacent galvanometers are aligned; the time delay of the driving signals of the multiple lasers is adjusted, so that the phases projected by the multiple projection units are continuously coded; a camera is triggered to acquire the grating pattern; and three-dimensional information of the scanning object is generated based on the grating pattern; the application has the advantage of a larger FOV than a single MEMS galvanometer projection scheme, a projection scheme with a large depth of field and a large projection angle is obtained, and a low-cost scheme can be provided for a large-view-field three-dimensional scanning.

Description

Technical Field

[0001] This invention relates to the field of optical components and systems, and is applied to structured light 3D scanning and MEMS galvanometer grating projection. In particular, it relates to a method, system, and medium for large-angle projection using multiple MEMS galvanometers. Background Technology

[0002] MEMS galvanometers are tiny, drivable mirrors fabricated using Micro-Electro-Mechanical Systems (MEMS) technology, typically with a mirror diameter of only a few millimeters. Compared to traditional optical scanning mirrors, they offer advantages such as lighter weight, smaller size, ease of mass production, and lower manufacturing costs.

[0003] Currently, MEMS used for projecting structured light coded stripes have limited scanning field of view (FOV) due to the influence of optical aperture, and cannot cover the camera's FOV. To achieve a large-angle FOV, the following methods are typically used:

[0004] Method 1: Increase the FOV of MEMS galvanometer scanning by using an optical beam expander lens, but this will cause problems such as reduced signal-to-noise ratio and energy loss, ultimately resulting in a decrease in scanning accuracy that is proportional to the increase in FOV by the optical beam expander lens.

[0005] Method 2 involves stitching together the fields of view of multiple 3D scanners, with the final 3D data being externally registered and stitched. However, this method places extremely high demands on the system's computing power, especially in scenarios requiring high point cloud density. Point cloud registration becomes a performance bottleneck, affecting the scanning frame rate, and registration accuracy also impacts the scanning results. Besides the above issues, using a combination of multiple MEMS sensors presents the following technical challenges: 1) Each MEMS galvanometer projects a grating pattern, requiring the patterns projected by adjacent MEMS galvanometers to be aligned at their boundaries, without overlap or gaps; 2) The patterns projected by multiple MEMS galvanometers suffer from repetitive encoding. Summary of the Invention

[0006] The main objective of this invention is to address the shortcomings and technical difficulties of existing MEMS galvanometer projection technology by proposing a large-angle projection method, system, and medium using multiple MEMS galvanometers. This method increases the scanning field of view (FOV) while maintaining high scanning accuracy.

[0007] To achieve the above objectives, one technical solution adopted by the present invention is to provide a large-angle projection method for multiple MEMS galvanometers, comprising the following steps:

[0008] The steps include configuring the projection unit, which comprises a laser, a collimating lens, a line prism, and a galvanometer; and placing a high-speed photoelectric converter between adjacent projection units.

[0009] Initialization startup steps: drive the galvanometer to vibrate, and drive the laser to emit point laser light;

[0010] Grating pattern generation steps: The point laser emitted by the laser is sequentially passed through the collimating lens and the line prism and then incident on the surface of the galvanometer. The laser is reflected by the galvanometer onto the surface of the object to be scanned in three dimensions to form a periodic grating pattern.

[0011] Projection boundary alignment step: By adjusting the time delay of the drive signals of the multiple lasers and combining them with the high-speed photoelectric converter, the projection boundaries of two adjacent galvanometers are aligned;

[0012] Phase continuity encoding step: By adjusting the time delay of the drive signals of the multiple lasers, the phase of the projection unit is continuously encoded;

[0013] Steps for capturing grating patterns: Trigger the camera to acquire the grating pattern;

[0014] 3D information generation steps: Generate 3D information of the object being 3D scanned based on the grating pattern.

[0015] As an improvement, the step of configuring the projection unit further includes: sequentially installing and positioning the laser, the collimating lens, the linear prism, and the galvanometer; placing the high-speed photoelectric converter on the symmetrical line between every two adjacent galvanometers, with the high-speed photoelectric converter located near the bottom of the projection range of the galvanometer.

[0016] As an improved solution, the initialization startup step further includes: sequentially inputting continuously encoded sine or binary codes into the galvanometer via a drive circuit board to drive the galvanometer to vibrate at the operating frequency; sending the drive signal of the laser to all lasers, and the light intensity of the lasers changes in brightness under the adjustment of the drive signal.

[0017] As an improvement, the projection boundary alignment step further includes: determining the projection boundary of two adjacent galvanometers by a high-speed photoelectric converter between two adjacent galvanometers, and eliminating overlap and gaps by adjusting the time delay of the drive signal of each laser using the patterns projected by multiple galvanometers.

[0018] As an improved approach, determining the projection boundary of two adjacent galvanometers using a high-speed photoelectric converter between two adjacent galvanometers further includes: acquiring the pulse signal of the high-speed photoelectric converter, obtaining the pulse width based on the pulse signal, and adjusting the scanning angle of the galvanometer based on the pulse width to align the scanning boundary of the galvanometer with the high-speed photoelectric converter.

[0019] As an improvement, the phase continuous encoding step further includes: adjusting the phase of the periodic grating pattern projected by each of the lasers by adjusting the time delay of the driving signals of the multiple lasers, so that the phase of the pattern grating projected by the multiple projection units is continuously encoded while the period of the pattern grating projected by a single projection unit remains unchanged.

[0020] As an improvement, the grating pattern imaging step further includes: the driving circuit board outputs a synchronous trigger signal to the camera, and the camera captures the grating pattern according to the trigger signal.

[0021] As an improved approach, the three-dimensional information generation step further includes sending the grating pattern captured by the camera to a computing unit, wherein the computing unit obtains the three-dimensional information of the object being scanned based on the phase-shift imaging principle.

[0022] The present invention also provides a deflection angle detection system for MEMS optical engines, comprising: a housing and a camera, a computing unit, a driving circuit board and a projection unit disposed within the housing; the projection unit is composed of two MEMS, each of the MEMS comprising a laser, a collimating lens, a line prism and a galvanometer arranged in sequence, and a high-speed photoelectric converter is provided on the symmetrical line between two adjacent galvanometers;

[0023] The driving circuit board is used to drive the laser, the galvanometer, and the camera; the laser emits a point laser and passes it sequentially through the collimating lens and the line prism before entering the surface of the galvanometer, where it is reflected onto the surface of the object being scanned in three dimensions, forming a periodic grating pattern; the driving circuit board adjusts the time delay of the driving signals of the multiple lasers and, in conjunction with the high-speed photoelectric converter, aligns the projection boundaries of two adjacent galvanometers; the driving circuit board adjusts the time delay of the driving signals of the multiple lasers to continuously encode the phases projected by the multiple projection units; the camera acquires the grating pattern and sends it to the computing unit; the computing unit generates three-dimensional information of the object being scanned in three dimensions based on the grating pattern.

[0024] The present invention also provides a computer-readable storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the method.

[0025] The beneficial effects of this invention are:

[0026] The large-angle projection method of multiple MEMS galvanometers described in this invention can achieve alignment of projection boundaries of multiple MEMS galvanometers; the continuous encoding method of multiple MEMS galvanometers can meet the requirement that the projection pattern (phase resolution) is not repeated; the requirement that the FOV of the MEMS galvanometers covers the FOV of the camera can be achieved; the multiple MEMS galvanometers expand the scanning angle, avoiding the higher cost of stitching multiple scanners due to insufficient coverage of the scanner field of view and the computational cost of stitching the point cloud obtained from multiple scanners;

[0027] The large-angle projection system of the multi-MEMS galvanometer described in this invention expands the scanning angle by combining multiple MEMS galvanometers, uses PD sensors to align the projection boundaries of two adjacent MEMS galvanometers, and employs a method of continuous encoding of multiple MEMS galvanometers to ensure that the projection pattern (phase resolution) does not repeat. It has the advantage of a larger FOV than the single MEMS galvanometer projection scheme, resulting in a projection scheme with a large depth of field and a large projection angle, which can provide a low-cost solution for large field-of-view 3D scanning.

[0028] The computer-readable storage medium described in this invention has the advantage of a larger FOV than a single MEMS galvanometer projection scheme, while maintaining high scanning accuracy. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the projection unit in the large-angle projection method of multiple MEMS galvanometers described in Embodiment 1 of the present invention;

[0031] Figure 2 This is an effect diagram of the phase continuity encoding step in the large-angle projection method of multiple MEMS galvanometers described in Embodiment 1 of the present invention;

[0032] Figure 3 These are comparison diagrams of the effects of Embodiment 1 of the present invention and the prior art;

[0033] Figure 4 This is an architecture diagram of the large-angle projection system with multiple MEMS galvanometers described in Embodiment 2 of the present invention;

[0034] The components in the attached diagram are labeled as follows:

[0035] 1. Laser; 2. Collimating lens; 3. Linear prism; 4. High-speed photoelectric converter; 5. Galvanometer; 6. Housing; 7. Camera; 8. Computing unit; 9. Driver circuit board; 10. Projection unit. Detailed Implementation

[0036] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0037] In the description of this invention, it should be noted that the embodiments described in this invention are only some embodiments of this invention, not all embodiments; based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example 1

[0038] A method for large-angle projection using multiple MEMS galvanometers includes the following steps:

[0039] The configuration step of the projection unit 10 is as follows: the projection unit 10 is composed of two MEMS components. The MEMS includes multiple MEMS mirrors on a single silicon chip or multiple MEMS mirrors on a silicon chip. The MEMS includes a laser 1, a collimating lens 2, a line prism 3, and a galvanometer 5. The laser 1, the collimating lens 2, the line prism 3, and the galvanometer 5 are sequentially installed and positioned. The high-speed photoelectric converter 4 is placed on the symmetrical line between every two adjacent galvanometers 5, and the high-speed photoelectric converter 4 is located near the bottom of the projection range of the galvanometer 5.

[0040] Initialization startup steps: The continuously encoded sine or binary code is sequentially input into the galvanometer 5 through the drive circuit board 9, driving the galvanometer 5 to vibrate at the working frequency; the drive signal of the laser 1 is sent to all lasers 1, and the light intensity of the laser 1 changes from bright to dark under the adjustment of the drive signal;

[0041] Grating pattern generation steps: The point laser emitted by the laser 1 passes sequentially through the collimating lens 2 and the line prism 3 and then enters the surface of the galvanometer 5. The laser is reflected by the galvanometer 5 onto the surface of the object being scanned in three dimensions to form a periodic grating pattern.

[0042] Projection boundary alignment step: The boundary projected by two adjacent galvanometers 5 is determined by the high-speed photoelectric converter 4 between the two adjacent galvanometers 5. By adjusting the time delay of the driving signal of each laser 1, the patterns projected by multiple galvanometers 5 are used to eliminate overlap and gaps.

[0043] As an improved solution, the step of determining the boundary of the projection of two adjacent galvanometers 5 by using a high-speed photoelectric converter 4 between them further includes: when the light emitted from the left galvanometer passes through the high-speed photoelectric converter 4, the high-speed photoelectric converter 4 generates a pulse signal; the longer the illumination time, the wider the pulse width. The detection circuit of the high-speed photoelectric converter 4 determines the pulse width by counting, and adjusts the scanning angle of the galvanometer so that its right scanning boundary just triggers the shortest pulse width of the high-speed photoelectric converter 4, thus aligning the right side of the galvanometer scanning angle with the position of the high-speed photoelectric converter 4; the same method is used to align the left side of the scanning angle of the other galvanometer with the position of the high-speed photoelectric converter 4; after the above adjustments, the scanning boundaries of the two galvanometers 5 are aligned.

[0044] Phase continuity encoding step: By adjusting the time delay of the driving signals of the multiple lasers 1, the phase of the periodic grating pattern projected by each laser 1 is adjusted, so that the phase of the pattern grating projected by a single projection unit remains unchanged, while the phase of the multiple projection units is continuously encoded; the number of periods of the projected stripes can be 2. n It can also be other period numbers; see Figure 2 As shown, taking a 64-period Gray code pattern as an example: the left galvanometer projects stripes numbered [0, 63], the right galvanometer projects stripes numbered [64, 127]...An projects stripes numbered [64*(n-1), 64*n-1].

[0045] Grating pattern imaging steps: The driving circuit board 9 outputs a synchronous trigger signal to the camera 7, and the camera 7 captures the grating pattern according to the trigger signal;

[0046] 3D information generation steps: The grating pattern captured by the camera 7 is sent to the computing unit 8. The computing unit 8 obtains the 3D information of the 3D scanned object according to the phase-shift imaging principle. See Figure 3 The left side of the figure shows the projection of a single MEMS galvanometer, while the right side shows the projection obtained in this embodiment, which greatly improves the 3D scanning range. Example 2

[0047] This embodiment is based on the same inventive concept as the large-angle projection method for multiple MEMS galvanometers described in Embodiment 1, and provides a large-angle projection system for multiple MEMS galvanometers, such as... Figure 4As shown, it includes: a housing 6 and a camera 7, a computing unit 8, a driving circuit board 9, and a projection unit 10 disposed within the housing 6; the projection unit 10 is composed of two MEMS components, each of which includes multiple MEMS mirror assemblies on a single silicon chip and multiple MEMS mirror silicon chip assemblies. Each MEMS includes a laser 1, a collimating lens 2, a line prism 3 (Powell prism), and a mirror 5 arranged sequentially, with a high-speed photodetector 4 (PD) positioned on the symmetrical line between two adjacent mirrors;

[0048] The driving circuit board 9 is used to drive the laser 1, the galvanometer 5, and the camera 7; the laser 1 is used to emit point laser light, which passes sequentially through the collimating lens 2 and the line prism 3 before being incident on the surface of the galvanometer 5, and is reflected by the galvanometer 5 onto the surface of the object being scanned in three dimensions, forming a periodic grating pattern; the driving circuit board 9 is used to adjust the time delay of the driving signals of the multiple lasers 1, and in conjunction with the high-speed photoelectric converter 4, to align the projection boundaries of two adjacent galvanometers 5; the driving circuit board 9 is used to adjust the time delay of the driving signals of the multiple lasers 1, so that the phases projected by the multiple projection units 10 are continuously encoded; the camera 7 is used to acquire the grating pattern and send it to the computing unit 8; the computing unit 8 is used to generate three-dimensional information of the object being scanned in three dimensions based on the grating pattern. Example 3

[0049] This embodiment provides a computer-readable storage medium, including:

[0050] The storage medium is used to store computer software instructions for implementing the large-angle projection method of a multi-MEMS galvanometer as described in Embodiment 1 above. It includes a program for executing the large-angle projection method. Specifically, the executable program can be built into the large-angle projection system described in Embodiment 2. In this way, the large-angle projection system can implement the large-angle projection method described in Embodiment 1 by executing the built-in executable program.

[0051] Furthermore, the computer-readable storage medium in this embodiment can be any combination of one or more readable storage media, wherein the readable storage medium includes an electrical, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof.

[0052] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware, or by a program instructing related hardware to implement the program, which can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0054] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for large-angle projection using multiple MEMS galvanometers, characterized in that, Includes the following steps: The steps include configuring the projection unit, which comprises a laser, a collimating lens, a line prism, and a galvanometer; and placing a high-speed photoelectric converter between adjacent projection units. Initialization startup steps: drive the galvanometer to vibrate, and drive the laser to emit point laser light; Grating pattern generation steps: The point laser emitted by the laser is sequentially passed through the collimating lens and the line prism and then incident on the surface of the galvanometer. The laser is reflected by the galvanometer onto the surface of the object to be scanned in three dimensions to form a periodic grating pattern. Projection boundary alignment step: By adjusting the time delay of the drive signals of the multiple lasers and combining them with the high-speed photoelectric converter, the projection boundaries of two adjacent galvanometers are aligned; Phase continuity encoding step: By adjusting the time delay of the drive signals of the multiple lasers, the phases projected by the multiple projection units are continuously encoded; Steps for capturing grating patterns: Trigger the camera to acquire the grating pattern; 3D information generation steps: Generate 3D information of the scanned object based on the grating pattern; The step of configuring the projection unit further includes: sequentially installing and positioning the laser, the collimating lens, the linear prism, and the galvanometer; placing the high-speed photoelectric converter on the symmetrical line between every two adjacent galvanometers, and the high-speed photoelectric converter being located near the bottom of the projection range of the galvanometer; The initialization startup step further includes: sequentially inputting continuously encoded sine or binary codes into the galvanometer via a drive circuit board, driving the galvanometer to vibrate at the working frequency; sending the drive signal of the laser to all lasers, and the light intensity of the laser changes in brightness under the adjustment of the drive signal. The projection boundary alignment step further includes: determining the projection boundary of two adjacent galvanometers through a high-speed photoelectric converter between two adjacent galvanometers, and eliminating overlap and gaps in the patterns projected by the multiple galvanometers by adjusting the time delay of the driving signals of their respective lasers; The step of determining the projection boundary of two adjacent galvanometers by using a high-speed photoelectric converter between two adjacent galvanometers further includes: acquiring the pulse signal of the high-speed photoelectric converter, obtaining the pulse width based on the pulse signal, and adjusting the scanning angle of the galvanometer based on the pulse width so that the scanning boundary of the galvanometer is aligned with the high-speed photoelectric converter.

2. The large-angle projection method of multiple MEMS galvanometers according to claim 1, characterized in that: The phase continuity encoding step further includes: adjusting the phase of the periodic grating pattern projected by each of the lasers by adjusting the time delay of the driving signals of the multiple lasers, so that the phase of the pattern grating projected by the multiple projection units is continuously encoded while the period of the pattern grating projected by a single projection unit remains unchanged.

3. The large-angle projection method of multiple MEMS galvanometers according to claim 2, characterized in that: The grating pattern capturing step further includes: the driving circuit board outputs a synchronous trigger signal to the camera, and the camera captures the grating pattern according to the trigger signal.

4. The large-angle projection method of multiple MEMS galvanometers according to claim 3, characterized in that: The three-dimensional information generation step further includes sending the grating pattern captured by the camera to the computing unit, and the computing unit obtaining the three-dimensional information of the three-dimensional scanned object according to the phase-shift imaging principle.

5. A large-angle projection system based on multiple MEMS galvanometers, employing the large-angle projection method of multiple MEMS galvanometers as described in any one of claims 1-4, characterized in that, The system includes: a housing and a camera, computing unit, driving circuit board and projection unit disposed inside the housing; the projection unit is composed of two MEMS, each of the MEMS including a laser, a collimating lens, a line prism and a galvanometer arranged in sequence, and a high-speed photoelectric converter is provided on the symmetrical line between two adjacent galvanometers; The driving circuit board is used to drive the laser, the galvanometer, and the camera; the laser emits a point laser and passes it sequentially through the collimating lens and the line prism before entering the surface of the galvanometer, where it is reflected onto the surface of the object being scanned in three dimensions, forming a periodic grating pattern; the driving circuit board adjusts the time delay of the driving signals of the multiple lasers and, in conjunction with the high-speed photoelectric converter, aligns the projection boundaries of two adjacent galvanometers; the driving circuit board adjusts the time delay of the driving signals of the multiple lasers to continuously encode the phases projected by the multiple projection units; the camera acquires the grating pattern and sends it to the computing unit; the computing unit generates three-dimensional information of the object being scanned in three dimensions based on the grating pattern.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the method according to any one of claims 1 to 4.

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