Multi-spot 3D printing FTheta field mirror distortion correction method

Abstract

This invention relates to a method for correcting FTheta field lens distortion in multi-spot 3D printing, belonging to the field of 3D printing. It includes the following steps: establishing a relationship function between the beam deflection angle during printing and the distance between the average coordinates of all spots on the printing surface and the perpendicular position of the laser beam, based on the optical path system; determining the beam deflection angle at a distance *r* between the average coordinates of the spots and the perpendicular position of the laser beam, based on the relationship function, and calculating the maximum angle between multiple lasers under distortion conditions; adjusting the beam deflection angle by rotating the galvanometer during printing, while simultaneously adjusting the optical path system to ensure that the maximum angle between multiple lasers always matches the calculated result, thus achieving FTheta field lens distortion correction. This method can print multiple identical patterns even if the FTheta field lens has distortion.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing, specifically relating to a method for correcting distortion of FTheta field lenses in multi-spot 3D printing. Background Technology

[0002] Laser 3D printing uses a single laser beam, reflected by a galvanometer module, to scan and print patterns layer by layer on a printing surface. Depending on the printing material, there are currently several types, including SLA, SLS, and SLM. In 3D printing, SLA, SLS, and SLM use a galvanometer to reflect a single laser beam, scanning and printing an image on a two-dimensional working plane. Compared to traditional subtractive manufacturing techniques, 3D printing is an advanced additive manufacturing technology for rapidly producing parts.

[0003] In the application field of 3D printing, products suitable for mass production are usually small-sized parts arranged in an array, such as small parts in metal 3D printed 3C products. These parts are small in size and numerous, and hundreds of identical parts are usually printed at one time to meet the requirements of mass production. Therefore, many multi-spot 3D printing devices have emerged for printing multiple identical parts at one time. Due to the large number of lasers, an FTheta field lens is required to focus multiple lasers simultaneously. For example, the applicant's earlier application (application publication number CN120396347A) discloses a multi-spot batch 3D printing device and method, including at least one galvanometer scanning unit. Each galvanometer scanning unit is equipped with a laser beam splitting unit. The laser beam splitting unit is used to split a laser beam into multiple laser beams to form a laser matrix, and adjust the spacing between adjacent laser beams in the laser matrix. The galvanometer scanning unit is used to reflect the laser matrix onto the printing surface, and by adjusting the reflection angle of the galvanometer scanning unit, the laser matrix is ​​focused by the FTheta field lens and projected onto the printing surface for scanning, thus batch printing multiple parts.

[0004] To print identical parts from multiple light spots at different scanning angles, the distortion of the FTheta field lens needs to be zero. In this case, the distortion-related function of the FTheta field lens can be expressed as: ,in, g (γ) is a function related to the distortion of a flat-field lens. f Let F be the focal length of the FTheta field lens. It can be seen that when the FTheta field lens is a distortion-free FTheta lens, the angle between the multiple laser beams after beam splitting is always fixed. Therefore, the spacing between the light spots imaged on the printing surface is also fixed.

[0005] However, in actual FTheta field lens design, some distortion always exists. Many FTheta field lenses only correct the image field and do not perform further correction and optimization for lens distortion. In this case, the relationship between the laser beam deflection angle and the coordinate position of the laser spot on the printing surface is no longer strictly linear. When multiple laser beams print different images at different laser deflection angles, the distance between the multiple laser points changes, and the patterns printed by different laser points will also be distorted, no longer strictly identical. Summary of the Invention

[0006] The purpose of this invention is to provide a method for correcting the distortion of FTheta field lenses in multi-spot 3D printing, so as to solve the problem of deformation when printing images at different positions using multiple lasers when FTheta field lenses have distortion.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] This invention relates to a method for correcting distortion in multi-spot 3D printed FTheta field lenses, which includes the following steps:

[0009] S1. Based on the optical path system, establish the distance between the average value of the beam deflection angle with respect to the coordinates of all light spots on the printing surface and the position perpendicular to the laser beam during the printing process. r Relational functions;

[0010] S2. Determine the distance between the average value of the spot coordinates and the perpendicular position of the laser beam based on the relationship function. r The beam deflection angle at the time of distortion is calculated, and the maximum angle between multiple lasers under the distortion condition is calculated.

[0011] S3. During the printing process, the rotating galvanometer adjusts the beam deflection angle, and at the same time, the optical path system is adjusted so that the maximum angle between multiple lasers always matches the calculation result of S2, thereby achieving FTheta field mirror distortion correction.

[0012] Preferably, the formula for calculating the maximum angle between multiple lasers under distortion conditions in step S2 is as follows:

[0013]

[0014] in, This represents the maximum angle between multiple lasers under distorted conditions. This represents the maximum angle between multiple lasers under distortion-free conditions. This represents the distance between the average coordinates of all light spots during the printing process and the position perpendicular to the laser beam. The focal length of the FTheta field lens. The deflection angle of the galvanometer;

[0015] The deflection angle of the galvanometer The distance between the average coordinates of all light spots on the printing surface and the perpendicular position of the laser beam, based on the beam deflection angle. r The relational function is obtained, and it is expressed as:

[0016] .

[0017] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0018] The multi-spot 3D printing FTheta field lens distortion correction method of the present invention calculates the maximum angle between multiple lasers under different beam deflection angles during the printing process, and adjusts the optical path system when rotating the galvanometer to adjust the beam deflection angle so that the maximum angle between multiple lasers always matches the calculation result, thereby realizing FTheta field lens distortion correction. Even if there is distortion in the FTheta field lens, multiple identical patterns can be printed by multiple lasers. Attached Figure Description

[0019] Figure 1 The flowchart of the multi-spot 3D printing FTheta field lens distortion correction method involved in this invention is shown below;

[0020] Figure 2 This is a schematic diagram of the multi-spot batch 3D printing device in the embodiment;

[0021] Figure 3 This is a schematic diagram of FTheta field lens distortion correction in the embodiment. Detailed Implementation

[0022] To further understand the content of the present invention, the present invention will be described in detail with reference to the embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0023] This invention relates to a method for distortion correction using an FTheta field lens in multi-spot 3D printing, applicable to any multi-spot 3D printing system employing an FTheta field lens for focusing. This embodiment uses, for example... Figure 2 Taking the optical path system shown as an example, the method involved in this invention will be described in detail. The optical path system includes a concave lens group 1, a beam splitter 2, a convex lens group 3, a galvanometer scanning unit 5, and an FTheta field mirror 6 arranged sequentially. The concave lens group 1 is used to diffuse the laser beam. The beam splitter 2 is used to split the diffused laser beam into multiple laser beams to form a laser matrix. After splitting, the angle difference between the two laser beams with the largest angular deviation is... α The beam-splitter prism 2 moves back and forth along the laser beam propagation direction, adjusting the angle between adjacent laser beams in the laser matrix. The two laser beams with the largest deviation after being split by the beam-splitter prism 2 have the largest angle difference. αThe angle produced by the same beam splitter 2 is related to the parameters of beam splitter 2. α It is a constant variable; by moving the beam splitter 2 along the beam direction, it can be adjusted. β Multiple angles. The laser beam diffused by the concave lens group is collimated using the convex lens group 3. After collimation, the maximum angle between the laser beams is reduced to... β The distance between each laser is adjusted; the galvanometer scanning unit 5 reflects the laser matrix to the FTheta field lens 6, which then focuses it and projects it onto the printing surface.

[0024] See attached document Figure 1 As shown, the multi-spot 3D printing FTheta field lens distortion correction method includes the following steps:

[0025] S1. Establishing the beam deflection angle during printing based on the optical path system. The distance between the average coordinates of all light spots on the printing surface and the position perpendicular to the laser beam. r The relation function differs for different optical path systems and can be expressed as: Assuming the FTheta field lens has no distortion, then: ,in, f is the focal length of the FTheta field lens.

[0026] S2. Determine the distance between the average value of the spot coordinates and the perpendicular position of the laser beam based on the relationship function. r Beam deflection angle at time γ At this point, the galvanometer needs to be deflected by an angle. γ for: , for The inverse function of the laser and the formula for calculating the maximum angle between multiple lasers under distortion conditions are as follows:

[0027] ,

[0028] in, This represents the maximum angle between multiple lasers under distorted conditions. This represents the maximum angle between multiple lasers under distortion-free conditions. This represents the distance between the average coordinates of all light spots during the printing process and the position perpendicular to the laser beam. The focal length of the FTheta field lens. The angle of deflection of the galvanometer is denoted as θ.

[0029] S3. During the printing process, the rotating galvanometer adjusts the beam deflection angle, and simultaneously adjusts the optical path system to ensure that the maximum angle between multiple lasers always matches the calculation result in S2, thus achieving FTheta field mirror distortion correction. Figure 3As shown, for the optical path system involved in this embodiment, the beam splitter needs to be moved a certain distance to change the angle of the emitted beam. Assume the moving distance is Δ. L Then its expression satisfies:

[0030] ,

[0031] in, d 0 represents the diameter of the laser beam before it diffuses through concave lens group 1. D This represents the beam diameter of each laser beam after splitting. α The angle between adjacent laser beams after beam splitting. L 1. To adjust the distance between the concave lens group 1 and the beam splitter 2, L 2 is for adjusting the beam splitter 2 and the convex lens group 3.

[0032] The present invention has been described in detail above with reference to the embodiments, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for correcting distortion in multi-spot 3D-printed FTheta field lenses, characterized in that: It includes the following steps: S1. Based on the optical path system, establish a function relating the beam deflection angle during printing to the average value of the coordinates of all light spots on the printing surface and the distance r between the vertical position of the laser beam; S2. Determine the beam deflection angle when the average value of the spot coordinates is at a distance r from the vertical position of the laser beam based on the relational function, and calculate the maximum angle between multiple lasers under the distortion condition; S3. During the printing process, the rotating galvanometer adjusts the beam deflection angle, and at the same time, the optical path system is adjusted so that the maximum angle between multiple lasers always matches the calculation result of S2, thereby achieving FTheta field mirror distortion correction.

2. The multi-spot 3D printing FTheta field lens distortion correction method according to claim 1, characterized in that: The formula for calculating the maximum angle between multiple lasers under distortion conditions in S2 is as follows: in, This represents the maximum angle between multiple lasers under distorted conditions. This represents the maximum angle between multiple lasers under distortion-free conditions. This represents the distance between the average coordinates of all light spots during the printing process and the position perpendicular to the laser beam. The focal length of the FTheta field lens. The deflection angle of the galvanometer; The deflection angle of the galvanometer The relationship between the beam deflection angle and the average coordinates of all light spots on the printing surface and the distance r between the laser beam's perpendicular position is obtained through a function, which is expressed as: 。

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