Optical fiducial generation for galvanometric scanner calibration

Patent metadata

Field	Value
Publication number	US-11173548-B2
Application number	US-201815945550-A
Country	US
Kind code	B2
Filing date	Apr 4, 2018
Priority date	Apr 4, 2017
Publication date	Nov 16, 2021
Grant date	Nov 16, 2021

Abstract

An apparatus includes an optical source situated to produce a fiducial source beam, and an optical fiducial pattern generator situated to produce with the fiducial source beam at least one transient optical fiducial on a laser processing target that is in a field of view of a laser scanner situated to scan a laser processing beam across the laser processing target, so that a positioning of the laser processing beam on the laser processing target becomes adjustable relative to the at least one transient optical fiducial.

First claim

We claim:

1. An apparatus, comprising:
an optical source situated to produce a fiducial source beam; and
an optical fiducial pattern generator situated to produce with the fiducial source beam at least one transient optical fiducial on a laser processing target made of powder material that is in a field of view of a laser scanner situated to scan a laser processing beam across the laser processing target, wherein the optical fiducial pattern generator is configured to couple to the laser scanner so that a positioning of the laser processing beam on the laser processing target with the laser scanner becomes adjustable relative to the positioning of the at least one transient optical fiducial in the field of view of the laser scanner.

2. The apparatus of claim 1 , wherein the powder material of the laser processing target is situated to diffusely reflect the at least one transient optical fiducial.

3. The apparatus of claim 2 , wherein the powder material forms a first layer that is selectively processed with the laser processing beam and additional powder material is deposited to form one or more subsequent layers, wherein the at least one transient optical fiducial is produced at the first layer and at least one of the one or more subsequent layers to provide an in-situ calibration of the scanning of the laser processing beam.

4. The apparatus of claim 1 , further comprising an optical detector optically coupled to the laser processing target through the laser scanner, wherein the optical coupling through the laser scanner is to a subfield field of view of the field of view based on a scan position of one or more scan optics of the laser scanner, wherein the optical detector is situated to detect the at least one transient optical fiducial in the subfield.

5. The apparatus of claim 4 , wherein the optical fiducial pattern generator is configured to couple to the laser scanner with the laser scanner being configured to direct the laser processing beam to a predetermined position in the subfield field of view for different scan positions of the one or more scan optics.

6. The apparatus of claim 4 , wherein the optical detector includes one or more of a camera, photodiode, CMOS detector, and CCD detector.

7. The apparatus of claim 4 , wherein the optical detector is situated to detect the at least one transient optical fiducial while the laser processing beam is unpowered or at a non-processing power.

8. The apparatus of claim 4 , further comprising a controller coupled to the optical detector and configured to couple to the laser scanner, wherein the controller is configured to compare the detected position of the at least one transient optical fiducial to a position of the laser processing beam, to update a scan error correction table based on the comparison, and to scan the laser processing beam according to the updated scan error correction table.

9. The apparatus of claim 8 , further comprising the laser scanner.

10. The apparatus of claim 9 , further comprising a laser processing beam source situated to generate the laser processing beam and to direct the laser processing beam to the laser scanner.

11. The apparatus of claim 1 , wherein the at least one transient optical fiducial has an annular shape and the adjustment of the positioning of the laser processing beam relative to the at least one transient optical fiducial is based on a detection of the annular shape.

12. The apparatus of claim 1 , wherein the at least one transient optical fiducial has a wavelength that is spaced apart from a wavelength of the laser processing beam.

13. The apparatus of claim 1 , wherein the fiducial pattern generator includes a diffractive optical element situated to diffract the fiducial source beam into a diffracted beam to produce the at least one transient optical fiducial.

14. The apparatus of claim 13 , wherein the at least one transient optical fiducial includes a plurality of the transient optical fiducials that are spaced apart in a predetermined fiducial pattern in the field of view of the laser scanner.

15. The apparatus of claim 14 , wherein the laser scanner is situated to direct the laser processing beam to different subfields of the field of view that are associated with the positions of the respective transient optical fiducials.

16. The apparatus of claim 13 , further comprising an optical detector situated to detect a zero-order portion of the diffracted beam that is reflected by the laser processing target or a surface adjacent to the laser processing target.

17. The apparatus of claim 1 , wherein the optical source and optical fiducial pattern generator are configured to provide a spatial separation from the laser scanner and a laser processing beam source situated to generate the laser processing beam, wherein the spatial separation is configured to thermally isolate[s] the optical source and optical fiducial pattern generator from the laser scanner and laser processing beam source that reduces a position error of the at least one transient optical fiducial at the laser processing target.

18. The apparatus of claim 1 , wherein the fiducial pattern generator includes a spatial light modulator situated to modulate the fiducial source beam to produce a modulated beam so that the at least one transient optical fiducial is dynamically positionable across the laser processing target.

19. The apparatus of claim 18 , wherein the spatial light modulator includes one or more of a digital micro-mirror device, liquid crystal on silicon device, acousto-optic beam deflector, and electro-optic beam deflector.

20. The apparatus of claim 18 , wherein the at least one transient optical fiducial is dynamically positionable as the laser processing beam is scanned across the laser processing target so that a scan position of the laser processing beam can follow the dynamic position of the at least one transient optical fiducial.

Assignees

• Nlight Inc

Inventors

• Small Jay
• Martinsen Robert J

Classifications

• G02B27/32 Primary

  Fiducial marks and measuring scales within the optical system · CPC title

• B22F12/90

  Means for process control, e.g. cameras or sensors · CPC title

• B22F12/49

  Scanners · CPC title

• B22F12/44

  characterised by the configuration of the radiation means · CPC title

• B22F10/31

  Calibration of process steps or apparatus settings, e.g. before or during manufacturing · CPC title