A method for debugging a laser beam scanning system

Abstract

This application belongs to the field of optical system technology, specifically relating to a method for debugging a laser beam scanning system. The method includes the following steps: controlling a laser source to generate incident laser light, causing the incident laser light to pass sequentially through a first lens and a second lens included in the laser beam scanning system before being projected onto a target surface to form a pattern; adjusting the size of the aperture of the first lens to form a zero-order pattern on the target surface; adjusting the size of the aperture of the first lens to form a non-zero-order pattern on the target surface; adjusting the position of the second lens according to the zero-order and non-zero-order patterns until the preset conditions for completing the debugging of the laser beam scanning system are met; wherein, the preset conditions include the center point of the zero-order pattern coinciding with the center point of the non-zero-order pattern. This method can achieve online adjustment of the bright spot laser beam scanning system 100, with a high degree of automation; furthermore, it has high adjustment accuracy, eliminating the influence of the inconsistency between the actual optical axis and the physical center line caused by lens processing.

Description

Technical Field

[0001] This application belongs to the field of optical system technology, specifically relating to a debugging method for a laser beam scanning system. Background Technology

[0002] During the installation, commissioning, or use of an optical system, it is necessary to adjust the optical components to ensure their optical axes are coaxial. In existing technologies, the following two methods are mainly used to solve the problem of optical axis alignment in optical systems:

[0003] Method 1: Adjust the position of the optical components manually. By observing the zero-order and non-zero-order patterns projected by the optical system, the centers of the two are considered to roughly coincide, indicating that the adjustment is in place. This method relies entirely on experience and has a large margin of error.

[0004] Method 2: Using mechanical means, such as mounting several optical elements separately inside a sleeve, and then using a mechanical structure to make the sleeve coaxial, thereby ensuring the optical axis alignment of the lens. This method does not take into account that in actual manufacturing, there is a certain error between the actual optical axis of the optical element and the physical center line of the lens, therefore it cannot guarantee optical axis alignment. Summary of the Invention

[0005] This application provides a method for debugging a laser beam scanning system, which can solve the technical problem of large debugging errors in laser beam scanning systems.

[0006] This application provides a method for debugging a laser beam scanning system, including the following steps:

[0007] The laser source is controlled to generate incident laser light, which is then projected onto the target surface to form a pattern after passing through the first lens and the second lens contained in the laser beam scanning system.

[0008] Adjust the size of the aperture of the first lens to form a zero-order pattern on the target surface;

[0009] Adjust the size of the aperture of the first lens to form a non-zero order pattern on the target surface;

[0010] Adjust the position of the second lens according to the zero-order pattern and the non-zero-order pattern until the preset conditions for the laser beam scanning system to complete the debugging are met;

[0011] The preset conditions include the center point of the zero-order pattern coinciding with the center point of the non-zero-order pattern.

[0012] According to the embodiment of the first aspect of this application, adjusting the position of the second lens until the preset conditions for the laser beam scanning system to complete debugging are met includes the following steps:

[0013] Obtain the zero-order pattern and calculate the center of the zero-order pattern;

[0014] Obtain the non-zero order pattern and calculate the center of the non-zero order pattern;

[0015] Adjust the position of the second lens according to the center of the zero-order pattern and the center of the non-zero-order pattern until the center of the zero-order pattern coincides with the center of the non-zero-order pattern.

[0016] According to any of the foregoing embodiments of the first aspect of this application, the first lens is a planar microlens array used to modulate the incident laser and generate an array point source located at the front focal plane of the second lens.

[0017] Obtaining a zero-order pattern and calculating its center includes the following steps:

[0018] Obtain the zero-level pattern;

[0019] Extract the outer contour of the zero-order pattern and calculate the center coordinates based on the outer contour of the zero-order image;

[0020] Extract the region of maximum brightness of the zero-order pattern, fit the region of maximum brightness into a circle and determine the coordinates of its center.

[0021] The average of the center coordinates and the circle center coordinates is taken as the center of the zero-order pattern.

[0022] According to any of the foregoing embodiments of the first aspect of this application, the second lens is a planar secondary phase lens, used to modulate the light from the array point source and generate a multi-beam array output beam.

[0023] Obtaining a non-zero order pattern and calculating its center includes the following steps:

[0024] Obtain non-zero level patterns;

[0025] Extract the position and outer contour of each bright spot in the non-zero order pattern, and calculate the center coordinates of each bright spot based on its position and outer contour.

[0026] The mean of the center coordinates of all bright spots is taken as the center of the non-zero order pattern.

[0027] According to any of the foregoing embodiments of the first aspect of this application, the preset condition also includes that the roundness of each bright spot in the non-zero level pattern is consistent.

[0028] According to any of the foregoing embodiments of the first aspect of this application, adjusting the position of the second lens until the preset conditions for the laser beam scanning system to complete debugging are met, further includes the following steps:

[0029] Calculate the roundness of each bright spot in the non-zero order pattern.

[0030] Adjust the position of the second lens until the roundness of each bright spot in the non-zero order pattern is consistent.

[0031] According to any of the foregoing embodiments of the first aspect of this application, calculating the roundness of each bright spot in a non-zero order pattern includes the following steps:

[0032] Calculate the area F of the bright spot based on its outer contour;

[0033] Calculate the centroid of the bright spot based on its location and the grayscale value within the bright spot area;

[0034] Calculate the maximum or average distance L between the centroid of the bright spot and the outer contour;

[0035] Calculate the roundness Q of the bright spot, where, .

[0036] According to any of the foregoing embodiments of the first aspect of this application, the centroid coordinates of the bright spot are: , , ,in, , Let x and y be the x and y coordinates of the i-th pixel within the bright spot region. This represents the grayscale value of that pixel. It is a positive integer greater than 1.

[0037] According to any of the foregoing embodiments of the first aspect of this application, the second lens is a planar secondary phase lens, used to modulate the light from the array point source and generate a multi-beam array output beam.

[0038] Obtaining a non-zero order pattern and calculating its center includes the following steps:

[0039] Obtain non-zero level patterns;

[0040] Extract the position and outer contour of each bright spot in the non-zero order pattern;

[0041] Calculate the area of ​​each bright spot based on its outer contour;

[0042] The centroid of each bright spot is calculated based on its location and the grayscale value within the bright spot area;

[0043] The center of the non-zero order pattern is calculated using the area and centroid of each bright spot. , Let x be the x-coordinate of the center of the non-zero order pattern. Let be the ordinate of the center of the non-zero order pattern, where

[0044] ,

[0045] ,

[0046] in, Let be the area of ​​the j-th bright spot in the non-zero order pattern. Let x be the x-coordinate of the centroid of the j-th bright spot in the non-zero order pattern. Let be the ordinate of the centroid of the j-th bright spot in the non-zero order pattern. It is a positive integer greater than 1.

[0047] According to any of the foregoing embodiments of the first aspect of this application, wherein...

[0048] ,

[0049] ,

[0050] in, , Let x and y be the x and y coordinates of the i-th pixel within the bright spot region. This represents the grayscale value of that pixel. It is a positive integer greater than 1.

[0051] The laser beam scanning system debugging method of this application embodiment obtains a zero-order pattern that reflects the optical axis position of the first lens and a non-zero-order pattern that reflects the optical axis position of the second lens, and adjusts the position of the second lens according to the zero-order pattern and the non-zero-order pattern. This enables online adjustment of the bright spot laser beam scanning system 100, which has a high degree of automation. Furthermore, the adjustment accuracy is high, eliminating the influence of the inconsistency between the actual optical axis and the physical center line caused by lens processing. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of the laser beam scanning system debugging system provided in the embodiments of this application;

[0053] Figure 2 This is a schematic diagram of a zero-level pattern provided in an embodiment of this application;

[0054] Figure 3 This is a schematic diagram of a non-zero level pattern provided in an embodiment of this application. Detailed Implementation

[0055] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0056] The laser beam scanning system 100 includes multiple optical elements. One type of optical element is a diffractive optical element that causes incident light to diffract, enabling the incident parallel laser beam to converge into a lattice beam. Another type of optical element changes the exit angle of the lattice beam emanating from the diffractive optical element to achieve beam scanning covering a large field of view. The optical axes of these two types of optical elements need to be parallel. Based on this, this application embodiment provides a method for adjusting the bright spot laser beam scanning system 100.

[0057] Please see Figures 1 to 3 The debugging method for the bright spot laser beam scanning system 100 provided in this application embodiment includes the following steps:

[0058] S1. Control the laser source to generate incident laser S, so that the incident laser S passes through the first lens 110 and the second lens 120 included in the laser beam scanning system 100 in sequence, and then is projected onto the target surface P to form a pattern; wherein, the first lens 110 can diffract the incident laser S.

[0059] S2. Adjust the size of the light-transmitting aperture of the first lens 110 to form a light-transmitting aperture on the target surface P such as... Figure 2 The zero-order pattern shown;

[0060] S3. Adjust the size of the light-transmitting aperture of the first lens 110 to form a light-transmitting aperture on the target surface P such as... Figure 3 The non-zero level pattern shown;

[0061] S4. Adjust the position of the second lens 120 according to the zero-order pattern and the non-zero-order pattern until the preset conditions for the bright spot laser beam scanning system 100 to complete the debugging are met.

[0062] The preset conditions include the center point of the zero-order pattern coinciding with the center point of the non-zero-order pattern.

[0063] In this embodiment, the second lens 120 is mounted on a six-axis translation stage. The six-axis translation stage allows the second lens 120 to move in a plane parallel to the target surface P, and also allows the second lens 120 to rotate relative to its optical axis. This six-axis translation stage is connected to a computer, and the position of the second lens 120 is adjusted via commands issued by the computer. The computer acquires zero-order and non-zero-order patterns, and based on this information, issues commands to the six-axis translation stage to control the adjustment of the position of the second lens 120. Of course, the second lens 120 can be mounted on translation stages with different degrees of freedom according to different adjustment requirements. This embodiment uses the mounting of the second lens 120 on a six-axis translation stage as an example for explanation.

[0064] In this embodiment, the center of the zero-order pattern can reflect the optical axis position of the first lens 110, and the center of the non-zero-order pattern can reflect the optical axis position of the second lens 120. After the computer obtains the zero-order pattern and the non-zero-order pattern, it can issue a command to the six-axis displacement stage according to the positional relationship between the centers of the zero-order pattern and the non-zero-order pattern to adjust the position of the second lens 120 so that the centers of the zero-order pattern and the non-zero-order pattern coincide.

[0065] It should be noted that zero-order patterns and non-zero-order patterns may coexist. By adjusting the size of the aperture of the first lens 110, the brightness of the zero-order and non-zero-order patterns can be adjusted, so that the zero-order pattern is bright and the non-zero-order pattern is dim on the target surface P, and only the zero-order pattern is visible to the naked eye. Similarly, by adjusting the size of the aperture of the first lens 110, the zero-order pattern is dim and the non-zero-order pattern is bright on the target surface P, and only the non-zero-order pattern is visible to the naked eye. Of course, by adjusting the size of the aperture of the first lens 110, both zero-order and non-zero-order patterns visible to the naked eye can also be displayed on the target surface P.

[0066] The bright spot laser beam scanning system 100 debugging method provided in this application embodiment can realize online adjustment of the bright spot laser beam scanning system 100 with a high degree of automation; moreover, the adjustment accuracy is high, eliminating the influence of the inconsistency between the actual optical axis and the physical center line caused by lens processing.

[0067] In some embodiments, step S4 specifically includes the following steps:

[0068] S41. Obtain the zero-order pattern and calculate its center; the zero-order pattern can be obtained by taking a picture of the target surface P with a high-resolution camera; the camera is connected to a computer, and the computer can acquire the picture taken by the camera; the zero-order pattern is a geometric pattern, and its center can be calculated by a computer program.

[0069] S42. Obtain the non-zero order pattern and calculate the center of the non-zero order pattern; similarly, use a high-resolution camera to photograph the target surface P to obtain the non-zero order pattern; the non-zero order pattern is also a geometric pattern, and the center of the zero order pattern can be calculated by a computer program.

[0070] S43. Based on the center of the zero-order pattern and the center of the non-zero-order pattern, issue a command to the six-axis displacement stage to adjust the position of the second lens 120 until the center of the zero-order pattern coincides with the center of the non-zero-order pattern. For example, when the distance between the center of the non-zero-order pattern and the center of the zero-order pattern is less than 0.01 pixel units, it can be considered that the center of the zero-order pattern coincides with the center of the non-zero-order pattern.

[0071] In some embodiments, the first lens 110 is a planar microlens array used to modulate the incident laser S and generate an array point source located at the front focal plane of the second lens 120. The above step S41 specifically includes the following steps:

[0072] S411. Obtain the zero-order pattern; specifically, the zero-order pattern captured by the camera can be obtained via computer.

[0073] S412. Extract the outer contour of the zero-level pattern and calculate the center coordinates based on the outer contour of the zero-level image. Specifically, the outer contour of the zero-level image can be extracted using image processing algorithms, and the center coordinates of the outer contour can be calculated based on the outer contour.

[0074] S413. Extract the region of maximum brightness of the zero-order pattern, fit the region of maximum brightness into a circle and find its center coordinates; In the zero-order pattern, since the laser beam at the center has not undergone any modulation and divergence, a region of maximum brightness is formed at the center of the pattern. The center of this region corresponds to the optical axis of the planar microlens array. Therefore, the center of this region can be used to characterize the optical axis position of the planar microlens array.

[0075] S414. Take the average of the center coordinates and the circle center coordinates as the center of the zero-order pattern. Since the center coordinates obtained in step S412 and the circle center coordinates obtained in step S413 can both characterize the optical axis position of the planar microlens array, taking the average of the center coordinates of the outer contour and the circle center coordinates of the region with the maximum brightness can improve the calculation accuracy of the optical axis position of the planar microlens array.

[0076] In some embodiments, the second lens 120 is a planar secondary phase lens, used to modulate the light from the array of point sources generated by the planar microlens array and generate multiple array-emitted beams. When the planar secondary phase lens and the planar microlens array are functionally matched, the planar microlens array can achieve arbitrary wavefront modulation and generate point sources that perfectly match the planar secondary phase lens, thereby effectively suppressing the RMS of the emitted beam. The planar secondary phase lens can convert the translational symmetry of the point source into the rotational symmetry of the emitted beam, thereby achieving beam scanning with a large field of view. Furthermore, the number and diameter of the emitted beams can be determined by the number and period of the planar microlenses. Based on this, step S42 specifically includes the following steps:

[0077] S421. Obtain a non-zero order pattern; similarly, obtain the non-zero order pattern captured by the camera using a computer; through the action of a planar secondary phase lens, the non-zero order pattern contains an array of bright spots composed of a series of bright spots;

[0078] S422. Extract the position and outer contour of each bright spot in the non-zero level pattern, and calculate the center coordinates of each bright spot based on the position and outer contour. Specifically, the position of the bright spot can be obtained through image processing algorithms, the outer contour of the bright spot can be extracted, and the center coordinates of the outer contour can be calculated based on the position and outer contour of the bright spot.

[0079] S423. Take the average of the center coordinates of all bright spots as the center of the non-zero order pattern.

[0080] Of course, other methods can also be used to calculate the center of the non-zero order pattern. In some embodiments, as an alternative method, step S42 above specifically includes the following steps:

[0081] S424. Obtain a non-zero level pattern; similarly, acquire the non-zero level pattern captured by the camera using a computer. The non-zero level pattern contains an array of bright spots; each bright spot region contains several pixels.

[0082] S425. Extract the position and outer contour of each bright spot in the non-zero level pattern; specifically, the position of the bright spot and the outer contour of the bright spot can be obtained through image processing algorithms.

[0083] S426. Calculate the area of ​​each bright spot based on the outer contour; specifically, the area of ​​each bright spot can be obtained by calculating the number of pixels within the outer contour area.

[0084] S427. Calculate the centroid of each bright spot based on its position and the grayscale value of each pixel within the bright spot area; the centroid of the bright spot represents the center position of the corresponding beam; the centroid of the bright spot is the brightest position of the bright spot;

[0085] S428. Calculate the center of the non-zero order pattern using the area and centroid of each bright spot. , Let x be the x-coordinate of the center of the non-zero order pattern. Let be the ordinate of the center of the non-zero order pattern. and It can be obtained using the following formula:

[0086] (1)

[0087] (2)

[0088] in, Let be the area of ​​the j-th bright spot in the non-zero order pattern. Let x be the x-coordinate of the centroid of the j-th bright spot in the non-zero order pattern. Let be the ordinate of the centroid of the j-th bright spot in the non-zero order pattern. It is a positive integer greater than 1. Where, and It can be obtained using the following formula:

[0089] (3)

[0090] (4)

[0091] in, , Let x and y be the x and y coordinates of the i-th pixel within the bright spot region. This represents the grayscale value of that pixel. It is a positive integer greater than 1.

[0092] In some embodiments, the preset condition also includes that the roundness of each bright spot in the non-zero order pattern is consistent. If the optical axis of the planar secondary phase lens is not parallel to the optical axis of the planar microlens array, then in the non-zero order pattern imaged on the target surface P, the shape of some bright spots will not be round. Therefore, the roundness of the bright spots in the non-zero order pattern can be made consistent by adjusting the secondary phase lens, thereby achieving the purpose of making the optical axis of the planar secondary phase lens parallel to the optical axis of the planar microlens array.

[0093] In some embodiments, step S4 above further includes the step:

[0094] S44. Obtain the non-zero order pattern and calculate the roundness of each bright spot in the non-zero order pattern. By calculating the roundness, it can be determined whether the optical axis of the planar secondary phase lens is parallel to the optical axis of the planar microlens array. For example, it can be set that if the roundness difference of the bright spots is greater than 0.01 pixels, it is determined that the optical axis of the planar secondary phase lens is not parallel to the optical axis of the planar microlens array; if the roundness difference of the bright spots is less than or equal to 0.01 pixels, it is determined that the optical axis of the planar secondary phase lens is parallel to the optical axis of the planar microlens array.

[0095] S45. Adjust the position of the second lens 120 until the roundness of each bright spot in the non-zero order pattern is consistent. For example, rotate the second lens 120 relative to its own optical axis until the roundness difference of the bright spots in the non-zero order pattern is less than 0.01 pixels.

[0096] In the above embodiments, steps S42 and S43 mainly involve moving the second lens 120 parallel to the target surface P in a plane, while steps S44 and S45 mainly involve rotating the second lens 120 relative to its own optical axis. In some embodiments, steps S42, S43, S44, and S45 can be executed cyclically until the center of the zero-order pattern coincides with the center of the non-zero-order pattern, and the roundness of each bright spot in the non-zero-order pattern is consistent. Alternatively, steps S44, S45, S42, and S43 can be executed cyclically until the center of the zero-order pattern coincides with the center of the non-zero-order pattern, and the roundness of each bright spot in the non-zero-order pattern is consistent.

[0097] In some embodiments, step S44 specifically includes the following steps:

[0098] S441. Calculate the area F of the bright spot based on its outer contour; similarly, obtain the area of ​​the bright spot by calculating the number of pixels within its outer contour.

[0099] S442. Calculate the centroid of the bright spot based on its location and the grayscale values ​​of each pixel within the bright spot region (outer contour region of the bright spot); the centroid coordinates of the bright spot are... , , ,in, , Let x and y be the x and y coordinates of the i-th pixel within the bright spot region. This represents the grayscale value of that pixel. It is a positive integer greater than 1;

[0100] S443. Calculate the maximum or average distance L between the centroid of the bright spot and the outer contour;

[0101] S444. Calculate the roundness Q of the bright spot, where,

Claims

1. A method for debugging a laser beam scanning system, characterized in that, Including the following steps: The laser source is controlled to generate incident laser light, which is then projected onto the target surface to form a pattern after passing through the first lens and the second lens contained in the laser beam scanning system. The first lens is a planar microlens array, used to modulate the incident laser and generate an array point source located at the front focal plane of the second lens; Adjust the size of the light-transmitting aperture of the first lens to form a zero-order pattern on the target surface; Adjust the size of the aperture of the first lens to form a non-zero order pattern on the target surface; Obtain the zero-level pattern; Extract the outer contour of the zero-order pattern, and calculate the center coordinates based on the outer contour of the zero-order image; Extract the region of maximum brightness of the zero-level pattern, fit the region of maximum brightness into a circle and determine the coordinates of its center. The average of the center coordinates and the circle center coordinates is taken as the center of the zero-order pattern; Obtain the non-zero order pattern and calculate the center of the non-zero order pattern; Adjust the position of the second lens according to the center of the zero-order pattern and the center of the non-zero-order pattern until the preset conditions for the laser beam scanning system to complete the debugging are met; The preset conditions include the center point of the zero-level pattern coinciding with the center point of the non-zero-level pattern.

2. The laser beam scanning system debugging method according to claim 1, characterized in that, The second lens is a planar secondary phase lens, used to modulate the light from the array point source and generate multiple array output beams. The steps of obtaining the non-zero order pattern and calculating the center of the non-zero order pattern include: Obtain the non-zero level pattern; Extract the position and outer contour of each bright spot in the non-zero order pattern, and calculate the center coordinates of each bright spot based on its position and outer contour. The mean of the center coordinates of all bright spots is taken as the center of the non-zero order pattern.

3. The laser beam scanning system debugging method according to claim 2, characterized in that: The preset conditions also include that the roundness of each bright spot in the non-zero level pattern is consistent.

4. The laser beam scanning system debugging method according to claim 3, characterized in that, The step of adjusting the position of the second lens until the preset conditions for the laser beam scanning system to complete debugging are met also includes the following steps: Calculate the roundness of each bright spot in the non-zero order pattern. Adjust the position of the second lens until the roundness of each bright spot in the non-zero order pattern is consistent.

5. The laser beam scanning system debugging method according to claim 4, characterized in that, The calculation of the roundness of each bright spot in the non-zero order pattern includes the following steps: Calculate the area F of the bright spot based on its outer contour; Calculate the centroid of the bright spot based on its location and the grayscale value within the bright spot area; Calculate the maximum or average distance L between the centroid of the bright spot and the outer contour; Calculate the roundness Q of the bright spot, where, 6. The debugging method for the laser beam scanning system according to claim 5, characterized in that, The centroid coordinates of the bright spot are (C x C y ), Where, x i y i Let x and y be the x and y coordinates of the i-th pixel within the bright spot region, and value be... i h is the grayscale value of the pixel, where h is a positive integer greater than 1.

7. The debugging method for the laser beam scanning system according to claim 1, characterized in that, The second lens is a planar secondary phase lens, used to modulate the light from the array point source and generate multiple array output beams. The steps of obtaining the non-zero order pattern and calculating the center of the non-zero order pattern include: Obtain the non-zero level pattern; Extract the position and outer contour of each bright spot in the non-zero order pattern; The area of ​​each bright spot is calculated based on the external contour. The centroid of each bright spot is calculated based on its location and the grayscale value within the bright spot area; The center (C) of the non-zero order pattern is calculated using the area and centroid of each bright spot. X C Y ), C X Let C be the x-coordinate of the center of the non-zero order pattern. Y Let be the ordinate of the center of the non-zero order pattern, where Among them, F j Let C be the area of ​​the j-th bright spot in the non-zero order pattern. xj Let C be the x-coordinate of the centroid of the j-th bright spot in the non-zero order pattern. yj Let be the ordinate of the centroid of the j-th bright spot in the non-zero order pattern, where k is a positive integer greater than 1.

8. The laser beam scanning system debugging method according to claim 7, characterized in that, in, Where, x i y i Let x and y be the x and y coordinates of the i-th pixel within the bright spot region, and value be... i h is the grayscale value of the pixel, where h is a positive integer greater than 1.

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