US 12,480,757 B2
Method for distance measurement by means of OCT and associated computer program product
Martin Stambke, Dunningen (DE); and Jan-Patrick Hermani, Markgroeningen (DE)
Assigned to TRUMPF LASER GMBH, Schramberg (DE)
Filed by TRUMPF Laser GmbH, Schramberg (DE)
Filed on Jun. 1, 2022, as Appl. No. 17/829,379.
Application 17/829,379 is a continuation of application No. PCT/EP2020/084161, filed on Dec. 1, 2020.
Claims priority of application No. 10 2019 132 619.2 (DE), filed on Dec. 2, 2019.
Prior Publication US 2022/0290973 A1, Sep. 15, 2022
Int. Cl. G01B 11/02 (2006.01); A61B 3/10 (2006.01); A61B 5/00 (2006.01); B23K 26/03 (2006.01); G01B 9/0209 (2022.01); G01B 9/02091 (2022.01); G01B 11/06 (2006.01)
CPC G01B 11/026 (2013.01) [B23K 26/032 (2013.01); G01B 9/02091 (2013.01); G01B 11/0608 (2013.01); G01B 9/0209 (2013.01); G01B 11/0675 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for distance measurement using an optical coherence tomography apparatus, the method comprising:
(a) measuring a focus distance between a z-focus position of a processing laser beam and a reference surface, the processing laser beam being directed onto the reference surface via a laser processing optical unit,
directing a measurement beam onto the reference surface, and measuring a reference distance between a reference arm mirror of the coherence tomography apparatus and the reference surface using the measurement beam, the measurement beam being directed onto a same point of the reference surface as the processing beam or onto a point of the reference surface next to an impingement point of the processing beam;
(b) directing the measurement beam onto a workpiece surface, and measuring a workpiece distance between the reference arm mirror and the workpiece surface using the measurement beam, and
(c) determining the distance between workpiece surface and the z-focus position based on the reference distance and the workpiece distance and the measured focus distance.