Method for automatable or automated determination of the focal position of a laser beam generated by an exposure device
A method for automatable or automated determination of the focal position of a laser beam ( 2 ) including the following steps: —arranging a substrate ( 10 ) in a first exposure position (z 1 ), and exposing the substrate ( 10 ) with at least one exposure vector ( 13 ) in the first exposure position (z 1 ), —moving the substrate ( 10 ) into several other exposure positions, in which the substrate ( 10 ) is respectively arranged in another certain z-axis position (z n ) relative to the reference point ( 11 ), and respectively exposing the substrate ( 10 ) with at least one exposure vector ( 13 ) in the respective other exposure positions (z n ), —optically evaluating the exposure pattern ( 12 ) by detecting different contrast sections in the exposure pattern ( 12 ) that can be optically detected, —determining the focal position of the laser beam ( 2 ) based on the detected optical contrast sections.
1. A method for automated determination of a focal position of a laser beam generated by an exposure device of an apparatus for additive manufacturing of three-dimensional objects, wherein the apparatus comprises an x-axis horizontally oriented, a y-axis horizontally oriented, and a z-axis vertically oriented, the method comprising:
exposing the substrate with at least one exposure vector while in a first exposure position on the z-axis to form a first exposure pattern;
exposing the substrate with at least one exposure vector while in a second exposure position on the z-axis to form a second exposure pattern;
optically evaluating an optical contrast between the first exposure and the second exposure; and,
determining the focal position of the laser beam based at least in part on the optical evaluation.
2. The method of claim 1 , wherein the optical contrast comprises a difference in darkness.
3. The method of claim 1 , wherein the optical contrast comprises a difference in color.
4. The method of claim 1 , further comprising:
exposing the substrate with at least one exposure vector while in a plurality of different positions on the z-axis to form a plurality of exposure patterns;
optically evaluating the optical contrast between at least some of the plurality of exposure patterns; and,
determining the focal position of the laser beam base at least in part on the optical evaluation.
5. The method of claim 1 , wherein at least one of the first exposure pattern and the second exposure pattern comprises an optically detectable geometric assignment feature assigned to a certain exposure position.
6. The method of claim 5 , where the at least one of the first exposure pattern and the second exposure pattern comprises a tooth-shaped or pinnacle-shaped exposure pattern, and wherein the optically detectable geometric assignment feature comprises a tip of the tooth-shaped or pinnacle-shaped exposure pattern.
7. The method of claim 5 , wherein the optically detectable geometric assignment feature comprises a line protecting beyond the rest of the exposure pattern.
8. The method of claim 1 , wherein a distance between the first exposure position and the second exposure position is from 0.5 mm to 1 mm.
9. The method of claim 1 , wherein a distance on the z-axis between the first exposure position and the second exposure position is at least 0.1 mm.
10. The method of claim 9 , wherein a distance on the z-axis between the first exposure position and the second exposure position is from 0.5 mm to 1 mm.
11. The method of claim 1 , wherein the exposure vector used in the first exposure position and the exposure vector used in the second exposure position are parallel.
12. The method of claim 1 , wherein the exposure vector used in the first exposure position and the exposure vector used in the second exposure position are displaced by an offset of 0.1 mm to 1 mm.
13. The method of claim 12 , wherein the offset is about 0.2 mm.
14. The of claim 1 , further comprising adjusting the exposure device based determining the focal position of the laser beam.
15. The method of claim 1 , wherein the substrate is arranged on a carrying element movably supported along the z-axis.
16. An apparatus for additive manufacturing three-dimensional objects, wherein the apparatus comprises an x-axis horizontally oriented, a y-axis horizontally oriented, and a z-axis vertically oriented, the apparatus comprising:
an exposure device configured to generate a laser beam; and,
a control device for generating one or more control commands, the control commands comprising:
exposing a substrate with at least one exposure vector while in a first exposure position on the z-axis to form a first exposure pattern;
exposing the substrate with at least one exposure vector while in a second exposure position on the z-axis to form a second exposure pattern;
optically evaluating an optical contrast between the first exposure and the second exposure; and,
determining a focal position of the laser beam based at least in part on the optical evaluation.
17. The apparatus of claim 16 , further comprising a detection and determination device for optically evaluating the optical contrast.
18. The apparatus of claim 16 , further comprising a carrying element for supporting the substrate, wherein the carrying element is moveable along the z-axis.
19. The apparatus of claim 16 , wherein the control commands further comprise moving the carrying element along the z-axis.
20. The apparatus of claim 16 , wherein the substrate is arranged on a carrying element movably supported along the z-axis.