Method and device for shaping radiation for laser processing

Patent metadata

Field	Value
Publication number	US-11440136-B2
Application number	US-201816491371-A
Country	US
Kind code	B2
Filing date	Mar 2, 2018
Priority date	Mar 7, 2017
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

A method and a laser assemblage are described for material processing, such that in a laser assemblage, a laser beam is focused onto a processing/imaging plane and the laser beam can be adapted in terms of its intensity distribution by way of at least one beam shaper. Provision is made in this context that in order to avoid uniformity defects in the processing/imaging plane, the laser beam is split by way of at least one beam splitter into at least two partial or individual beams, and the partial or individual beams are differently influenced, or each partial or individual beam is constituted from a laser source having a different wavelength, in such a way that after they are combined and focused onto the processing/imaging plane they form an output beam having an intensity profile, adjacent intensity maxima of the intensity profile differing in terms of their light properties. It is thereby possible to prevent the occurrence of obtrusive interference so that obtrusive speckle patterns are largely eliminated, with the result that beam shaping quality, in particular for laser processing processes, can be considerably improved.

First claim

What is claimed is:

1. A method for beam shaping in a laser processing process, comprising:
in a laser assemblage, focusing a laser beam onto a processing/imaging plane;
adapting an intensity distribution of the laser beam by way of at least one beam shaper; and
in order to avoid uniformity defects in the processing/imaging plane, splitting the laser beam by way of at least one beam splitter into at least two partial or individual beams, wherein one of the partial or individual beams are differently influenced and each partial or individual beam is constituted from a laser source having a different wavelength, in such a way that after the partial or individual beams are combined and focused onto the processing/imaging plane, the partial or individual beams form an output beam having an intensity profile, wherein adjacent intensity maxima of the intensity profile differ in terms of at least one or several light properties in order to exclude a formation of interference,
wherein the intensity profiles of the partial or individual beams are combined in the processing/imaging plane, forming the output beam as a regular pattern having repeating pattern fields in the form of a checkerboard pattern or a honeycomb pattern or a triangular pattern or a diamond pattern or another regular pattern; directly adjacent pattern fields each being associated with a different type of partial or individual beam; the different types of partial or individual beam differing in terms of at least one light property.

2. The method as recited in claim 1 , wherein the partial or individual beams are differently influenced, in terms of their phase and/or their intensity profiles and/or their wavelengths, by way of beam shapers and/or delay units and/or wavelength manipulators.

3. The method as recited in claim 2 , wherein by way of the beam shapers, the partial beams are sequentially modified at short time intervals using at least one phase and/or amplitude mask.

4. The method as recited in claim 3 , wherein different phase and/or amplitude masks are defined for laser processing as a function of a target beam profile.

5. The method as recited in claim 3 , wherein the partial beams are modified, each separately or together, using the phase and/or amplitude masks.

6. The method as recited in claim 1 , wherein the laser beam is split into at least two differently polarized partial beams; and the partial beams are each modified by way of beam shapers in terms of their intensity profiles; and after the differently polarized partial beams are combined, the intensity profiles of the two partial beams are superimposed on one another in the processing/imaging plane to yield the target beam profile, adjacent intensity maxima of the intensity profiles each having a different polarization.

7. The method as recited in claim 1 , wherein diffractive diffusers that are embodied as spatial light modulators are used for beam shaping.

8. The method as recited in claim 1 , wherein a pulsed or non-pulsed coherent light source is used.

9. The method as recited in claim 1 , wherein when pulsed lasers are used, the laser beam, after being split into at least two partial or individual beams having different intensity profiles for each partial beam, are time-delayed by way of the delay units differently for each partial or individual beam and, after they are combined and focused onto the processing/imaging plane, form an output beam having an intensity profile without superimposition in the processing/imaging plane at least in terms of time, such that in order to generate the different intensity profiles for each partial beam, the beam shaper can be combined with the beam splitter or can be placed after the delay units before a beam combining system.

10. The method as recited in claim 9 , wherein the minimum delay is selected to be longer than or equal to a pulse duration of the laser beam.

11. The method as recited in claim 9 , wherein no delay is selected for a first partial beam, a delay corresponding to at least the pulse duration of the laser beam is selected for a second partial beam, a delay corresponding to at least twice the pulse duration of the laser beam is selected for a third partial beam, and a delay corresponding to at least (n−1) times the pulse duration of the laser beam is selected for an n-th partial beam.

12. The method as recited in claim 1 , wherein the laser beam is split into n partial beams, of which at least one partial beam is varied in terms of a beam shape thereof using the beam shaper, and of which another partial beam or beams is/are combined, without beam shaping, with the at least one beam-shaped partial beam to yield an irradiation field on the workpiece that is to be processed in the processing/imaging plane, or the other partial beams are deliberately caused to interfere.

13. A method for beam shaping in a laser processing process, the method comprising:
in a laser assemblage, focusing a laser beam onto a processing/imaging plane;
adapting an intensity distribution of the laser beam by way of at least one beam shaper; and
in order to avoid uniformity defects in the processing/imaging plane, splitting the laser beam by way of at least one beam splitter into at least two partial or individual beams, wherein one of the partial or individual beams are differently influenced and each partial or individual beam is constituted from a laser source having a different wavelength, in such a way that after the partial or individual beams are combined and focused onto the processing/imaging plane, the partial or individual beams form an output beam having an intensity profile, wherein adjacent intensity maxima of the intensity profile differ in terms of at least one or several light properties in order to exclude a formation of interference, wherein the method is used in laser processing systems for laser ablation, laser drilling, laser marking, laser soldering and laser welding, laser cutting, laser sintering and hardfacing, laser cleaning, laser hardening, laser remelting, laser alloying and dispersing, or laser polishing.

14. An apparatus, comprising:
a computer unit;
a laser source; and
a beam shaper, wherein a laser beam from the laser source is focusable onto a processing/imaging plane, wherein the laser beam is adaptable in terms of an intensity distribution thereof by way of the beam shaper;
an arrangement for focusing a laser beam onto a processing/imaging plane;
an arrangement for adapting an intensity distribution of the laser beam by way of the beam shaper; and
in order to avoid uniformity defects in the processing/imaging plane, an arrangement for splitting the laser beam by way of at least one beam splitter into at least two partial or individual beams, wherein one of the partial or individual beams are differently influenced and each partial or individual beam is constituted from a second laser source having a different wavelength, in such a way that after the partial or individual beams are combined and focused onto the processing/imaging plane, the partial or individual beams form an output beam having an intensity profile, wherein adjacent intensity maxima of the intensity profile differ in terms of at least one or several light properties in order to exclude a formation of interference, wherein the laser beam is splittable by way of the at least one beam splitter into the partial or individual beams or each partial or individual beam is generatable from the laser source having a different wavelength, wherein by way of the beam shaper and/or delay units and/or wavelength manipulators that can be addressable by the computer unit, the partial or individual b

Assignees

• Bosch Gmbh Robert

Inventors

• Gauch Roland
• Mikhaylov Dmitriy
• Graf Tobias

Classifications

• H01S3/0085

  Modulating the output, i.e. the laser beam is modulated outside the laser cavity · CPC title

• B23K26/0608

  in the same heat affected zone [HAZ] (B23K26/0613, B23K26/0619 take precedence) · CPC title

• B23K26/0676

  into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations · CPC title

• G02B27/0944

  Diffractive optical elements, e.g. gratings, holograms (gratings per se G02B5/18; holograms used as optical elements per se G02B5/32) · CPC title

• H01S3/0071

  Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction · CPC title