Determining a focus position of a high-energy beam

Patent metadata

Field	Value
Publication number	US-10399185-B2
Application number	US-201514952184-A
Country	US
Kind code	B2
Filing date	Nov 25, 2015
Priority date	May 29, 2013
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

An apparatus includes a focusing element arranged to focus a high-energy beam on a workpiece, an image detector for recording at least one image of an area to be monitored on the surface of the workpiece and/or the reference contour; imaging optics arranged to (a) receive process radiation radiation through the focusing element, from an area of the workpiece and/or the reference contour to be monitored, in the form of a first monitoring beam that is non-coaxial with the high-energy beam between the workpiece and the imaging optics and (b) redirect the first monitoring beam to the image detector to provide the at least one image of the area to be monitored and/or the reference contour; and an evaluation device operable to determine the focus position of the high-energy beam based on the at least one recorded image.

First claim

What is claimed is:

1. An apparatus for determining a focus position of a high-energy beam along a propagating direction of the high-energy beam relative to a workpiece or relative to a reference contour of the apparatus, comprising:
a focusing lens arranged to focus the high-energy beam on the workpiece;
an image detector for recording at least one image of an area to be monitored on the surface of the workpiece, of the reference contour, or of both the workpiece and the reference contour;
imaging optics comprising at least one additional lens, the imaging optics being arranged to (a) receive monitoring radiation that is emitted from or reflected from the workpiece and passes through the focusing lens from the area to be monitored, (b) derive a first monitoring beam from a first outer portion of the monitoring radiation that is non-coaxial with and excludes a center portion of the monitoring radiation, and (c) redirect the first monitoring beam to the image detector to provide the at least one image of the area to be monitored; and
a programmable evaluation device operable to determine the focus position of the high-energy beam based on the at least one recorded image.

2. The apparatus according to claim 1 , wherein the programmable evaluation device is operable to determine the focus position of the high-energy beam based on a position of the reference contour in the at least one recorded image.

3. An apparatus according to claim 1 , wherein the imaging optics are arranged to (d) derive at least one additional monitoring beam from a third portion of the monitoring radiation, and (e) redirect the first monitoring beam and the at least one additional monitoring beam to the image detector to provide at least two images of the area to be monitored, and wherein
the programmable evaluation device is operable to determine the focus position of the high-energy beam based on a comparison of the at least two recorded images.

4. The apparatus according to claim 1 , further comprising a light source operable to illuminate an upper side of the workpiece in the area to be monitored.

5. The apparatus according to claim 1 , wherein the area to be monitored is delimited by the reference contour.

6. The apparatus according to claim 3 , wherein the programmable evaluation device is operable to determine the focus position relative to the workpiece.

7. The apparatus according to claim 3 , wherein the imaging optics comprise at least two imaging optical elements, each imaging optical element being arranged to derive a corresponding monitoring beam from the monitoring radiation.

8. The apparatus according to claim 7 , wherein the imaging optical elements comprise cylinder lenses.

9. The apparatus according to claim 7 , wherein the imaging optical elements are arranged in a lens array.

10. The imaging apparatus according to claim 3 , wherein the imaging optics comprise a deflector with at least two beam deflection areas, each beam deflection area being arranged to derive a corresponding monitoring beam from the monitoring radiation.

11. The apparatus according to claim 10 , wherein the deflector comprises at least one deflection prism.

12. The apparatus according to claim 3 , wherein the imaging optics comprise an optical component arranged to receive the monitoring radiation from the area to be monitored and operable to form the first monitoring beam and the at least one additional monitoring beam.

13. The apparatus according to claim 12 , wherein the optical component is operable to form the first monitoring beam and the at least one additional monitoring beam at different times.

14. The apparatus according to claim 13 , wherein the optical component comprises at least one aperture arranged to form the first monitoring beam and the at least one additional monitoring beam.

15. The apparatus according to claim 3 , wherein the imaging optics are arranged to redirect the first monitoring beam and the at least one additional monitoring beam to the image detector to provide at least three images of the area to be monitored.

16. The apparatus according to claim 1 , wherein the imaging optics comprise an imaging optical element arranged to derive at least one additional monitoring beam from the center portion of the monitoring radiation, and to redirect the at least one additional monitoring beam to the image detector to provide at least one additional image of the area to be monitored.

17. The apparatus according to claim 16 , wherein the programmable evaluation device is operable to compare the at least one additional image obtained from the at least one additional monitoring beam with the at least one image obtained from the first monitoring beam.

18. The apparatus according to claim 1 , further comprising a laser processing nozzle having a nozzle opening arranged to allow passage of the high-energy beam to the workpiece, wherein the imaging optics are arranged to receive the monitoring radiation from the nozzle opening.

19. The apparatus according to claim 18 , wherein an inner nozzle contour of the laser processing nozzle forms the reference contour.

20. The apparatus according to claim 1 , wherein the image detector comprises a camera.

21. The apparatus according to claim 3 , wherein the programmable evaluation device is operable to determine a distance between the reference contour and an upper side of the workpiece based on a comparison of the recorded images.

22. The apparatus according to claim 1 , further comprising: a mirror arranged to receive the high-energy beam; and a controller unit coupled to the mirror, wherein the controller unit is operable to alter the focus position of the high energy beam by adjusting a position of the mirror.

23. The apparatus according to claim 1 , further comprising: means for changing a focal point of the imaging optics.

24. A method for determining a focus position of a high-energy beam along a propagating direction of the high-energy beam relative to a workpiece or relative to a reference contour of the apparatus, the method comprising:
receiving, at imaging optics comprising at least one lens, monitoring radiation from an area of the workpiece, of the reference contour, or of both the workpiece and the reference contour to be monitored, the monitoring radiation passing through a focusing lens arranged to focus the high-energy beam on the workpiece;
deriving a first monitoring beam from a first outer portion of the monitoring radiation that is non-coaxial with and excludes a center portion of the monitoring radiation;
redirecting the first monitoring beam with the imaging optics to an image sensitive surface of an image detector;
generating, by the detector, at least one image of the area to be monitored responsive to the first monitoring beam being incident on the image sensitive surface of the image detector; and
determining the focus position of the high-energy beam from the at least one image.

25. The method according to claim 24 , wherein the focus position is determined based on a position of the reference contour in the at least one image.

26. The method according to claim 24 , further comprising:
deriving, at the imaging optics, at least one additional monitoring beam from a third portion of the monitoring radiation;
redirecting the at least one additional monitoring beam with the imaging optics to the image sensitive surface of the image detector;
generating at lea

Assignees

• Trumpf Werkzeugmaschinen Gmbh Co Kg

Inventors

• Regaard Boris

Classifications

• B23K26/0617

  and with spots spaced along the common axis · CPC title

• B23K26/046 Primary

  Automatically focusing the laser beam · CPC title

• B23K26/707 Primary

  for monitoring laser beam transmission optics · CPC title

• B23K26/0648

  comprising lenses · CPC title