Laser marking system and method for marking curved surfaces

Abstract

The present invention aims to provide a laser marking system and a method for marking on a curved surface. An optical component is configured to project a laser beam onto a curved surface in order to apply a marking. The optical component includes a beam manipulation optical system configured to determine a variable position where the projected laser beam intersects the curved surface. A beam controller is configured to control the beam manipulation optical system based on a control algorithm. The control algorithm is configured to receive an input image containing a set of two-dimensional input coordinates representing the nodes of the marking when they are intended to appear on the curved surface, receive a curvature map representing the three-dimensional curvature of the curved surface, calculate a set of two-dimensional output coordinates based on the set of two-dimensional input coordinates and the curvature map, and control the position of the laser beam based on the set of two-dimensional output coordinates.

Claims

1. A laser marking system for marking curved surfaces, The optical component is configured to project a laser beam onto the curved surface in order to apply the marking, The optical component includes a beam manipulation optical system configured to determine a variable position where the projected laser beam intersects the curved surface. Furthermore, it includes a beam controller configured to control the beam manipulation optical system based on a control algorithm, The control algorithm described above is: An input image is received that includes a two-dimensional set of input coordinates representing the nodes of the marking when intended to appear on the curved surface. The curvature map representing the three-dimensional curvature of the aforementioned surface has been completed. A set of two-dimensional output coordinates is calculated based on the set of two-dimensional input coordinates and the curvature map, and in the calculation, the set of two-dimensional output coordinates is fitted to the set of input coordinates to compensate for the distortion of the relative distance between the nodes in the projection of the laser beam onto the curved surface, and A laser marking system configured to control the position of the laser beam based on the aforementioned two-dimensional set of output coordinates.

2. One pair of output coordinates within the aforementioned set of output coordinates is, Determine a pair of input coordinates corresponding to a pair of nodes that are the nearest neighbors in the input image for the given set of input coordinates, Based on the pair of input coordinates, the Euclidean distance of the straight line segment along the plane of the input image between the pair of nodes is determined, Determining a pair of projected coordinates based on the calculated projection of the pair of input coordinates onto the curvature map, according to the projection of the laser beam onto the curved surface by the optical component via the beam manipulation optical system, Determining the geodesic length of the curved line segment between the pair of projected coordinates along the manifold of the surface map, The system according to claim 1, which is calculated by fitting the pair of output coordinates to the pair of input coordinates such that the difference between the geodesic length of the curved line segment along the manifold of the curvature map and the Euclidean distance of the straight line segment along the plane of the input image is minimized.

3. The system according to claim 1 or 2, wherein each input coordinate within the set of input coordinates is part of at least one pair of input coordinates and is adapted to the corresponding pair of output coordinates.

4. The system according to any one of claims 1 to 3, wherein the set of output coordinates is adapted to the set of input coordinates to minimize the overall distortion between the respective lengths of the curved line segments related to the respective lengths of the straight line segments.

5. The system according to claim 2 or any claim dependent thereon, wherein one of the geodesic length and the Euclidean distance is scaled by an overall scaling parameter which is the same for all output coordinate calculations.

6. The system according to any one of claims 1 to 5, wherein the three-dimensional curvature of the curved surface is mapped using a parameterized line segment such as a spline.

7. The system according to any one of claims 1 to 6, wherein the curvature map is a non-uniform rational B spline, i.e., a NURBS (Non-Uniform Rational Basis Splines), surface.

8. The system according to any one of claims 1 to 7, comprising a scanner configured to scan the three-dimensional curvature of the curved surface in order to determine the curvature map.

9. The system according to any one of claims 1 to 8, wherein the scanner is configured to scan a scanning beam on the curved surface and to determine the three-dimensional curvature based on the scanning beam.

10. The system according to any one of claims 1 to 9, wherein the scanning beam is scanned using the same beam manipulation optical system used to project the laser beam onto the curved surface, and the scanning beam is scanned on the curved surface to determine the curvature map before applying the markings on the curved surface based on the determined curvature map.

11. The system according to any one of claims 1 to 10, wherein the optical component includes a focusing optical system configured to focus the laser beam onto the curved surface, the focusing optical system includes at least one spherical optical element configured to introduce spherical aberration into the focused beam, the spherical aberration configured to maximize the length of the focal region of the focused beam such that the focal region coincides with the curved surface at each position of the focused beam determined by the beam manipulation optical system.

12. The focusing optical system according to any one of claims 1 to 11, comprising at least a first optical element having at least one spherical surface for introducing a first set of spherical aberrations into the beam, and a second optical element having at least one spherical surface for introducing a second set of spherical aberrations into the beam, wherein the second optical element is positioned at a distance from the first optical element and is adjusted so that the different sets of spherical aberrations interfere with each other to maximize the length of the focal region.

13. A method for marking curved surfaces, The system includes projecting a laser beam onto the curved surface in order to apply the marking using an optical component, The optical component includes a beam manipulation optical system configured to determine a variable position where the projected laser beam intersects the curved surface. Furthermore, the system includes controlling the beam manipulation optical system based on a control algorithm using a beam controller. The control algorithm described above is: An input image is received that includes a two-dimensional set of input coordinates representing the nodes of the marking when intended to appear on the curved surface. The curvature map representing the three-dimensional curvature of the aforementioned surface has been completed. A set of two-dimensional output coordinates is calculated based on the set of two-dimensional input coordinates and the curvature map, and in the calculation, the set of two-dimensional output coordinates is fitted to the set of input coordinates to compensate for the distortion of the relative distance between the nodes in the projection of the laser beam onto the curved surface, and A method for marking a curved surface, configured to control the position of the laser beam based on the two-dimensional set of output coordinates.

14. A computer-readable non-temporary recording medium that records instructions including a control algorithm, wherein the control algorithm, when executed by the beam controller in the system or method described in any one of claims 1 to 13, is configured to be used by the beam controller. An input image is received that includes a two-dimensional set of input coordinates representing the nodes of the marking when intended to appear on the curved surface. The system receives a curvature map representing the three-dimensional curvature of the aforementioned curved surface. A set of two-dimensional output coordinates is calculated based on the set of two-dimensional input coordinates and the curvature map, and in the calculation, the set of two-dimensional output coordinates is adapted to the set of input coordinates to compensate for the distortion of the relative distance between the nodes in the projection of the laser beam onto the curved surface, and A computer-readable non-temporary recording medium that controls the position of the laser beam based on the aforementioned two-dimensional set of output coordinates.

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