Development of a FD-OCT for the inline process metrology in laser structuring systems

Laser structuring is a rapidly developing manufacturing technique with long-term technological impact on future economics and ecological challenges. Due to its high process flexibility, the laser structuring system permits the structuring of different work pieces (different forms and structure complexity) with the same machine configuration. A crucial fact is the process knowledge and its control. The state of the art in laser structuring has however a crucial deficit. Present structuring systems contain no metrology setup to detect the shape geometry and contour accuracy before, during or after the structuring process. Therefore no result feedback to the machine can be accomplished and consequently a process control based on the real machined surface is not possible. In order to close this technology gap and assure an automated and robust manufacture process, a metrological system needs to be integrated to the process. In this work the concept and the development of an adjustable optical coherence tomography measuring system based on the analysis of the frequency domain (FD-OCT) with sub-micrometer accuracy for the in process measurement in a laser structuring machine is described. Goal of the research presented here is the development of the measuring system, with special focus on the spectrometer development (optical and software) and machine integration (optical and mechanical), as well as the development of an innovative wideband source based on amplified spontaneous emission (ASE) in ytterbium-doped double-clad fiber.