MEASURING DEVICE AND METHOD FOR PERFORMING MEASUREMENTS ON A WORKPIECE AS WELL AS MACHINING SYSTEM AND WELDING METHOD

The invention relates to a measuring device (10) for performing measurements on a workpiece (12) which are used to prepare and/or assess a weld seam (16) produced by a welding device (14) and having an initial portion (18) and/or an end portion (20). The measuring device (10) comprises a measuring unit (22) comprising an optical coherence tomograph (24) including a sample beam source (26) for producing a sample beam (28) as well as a sample head (30) via which the sample beam (28) can be outcoupled, wherein the sample beam (28) can be selectively focused on different measuring positions (32, 34) relative to a current machining position (36) along the weld seam (16), so that, with respect to a machining direction (38), a leading beam and/or a trailing beam of a current measuring position (32, 34) are adjustable relative to the current machining position (36). The measuring device (10) further comprises a fastening unit (40) which is configured to attach at least the sample head (30) to the welding device (14) in such a way that the sample head (30) is moved along with the welding device (14) when the welding device (14) is moving relative to the workpiece (12). In addition, the measuring device (10) comprises a control unit (42) which is configured to dynamically adjust the leading beam and/or the trailing beam during machining along the weld seam (16) such that the leading beam increases along the initial portion (18) and/or that the trailing beam decreases along the end portion (20). The invention further relates to a machining system (66), a method for performing measurements on a workpiece (12), and a method for machining a workpiece (12).