Laser structuring is rapidly developing manufacturing technique for broad spectrum of industrial branches, e.g.
aerospace, power engineering, tool- and mould making, and automotive. It enables to prepare work pieces and products
with very fine micro structures achieving a far better degree of details than conventional structuring techniques like
etching or eroding. However, the state of art in laser structuring shows a crucial deficit. Used systems contain no
metrology setup to detect the shape geometry (depth and length) and contour accuracy during the process. Therefore, an
innovative in-line metrology technique based on low coherence interferometry for laser structuring systems has been
investigated and described in the paper. In this contribution we present our results in the research of wideband and highpower light sources for the proposed low-coherence interferometric measurement system. The system can be
incorporated into a structuring workplace equipped with a Q-switched ytterbium-doped fiber laser at 1064 nm for
material processing. In the paper we focus on two wideband sources for such a measurement system. The first source is
based on a superluminescent diode and the second one is based on an amplified spontaneous emission in a double-clad
ytterbium-doped fiber. An example of results measured with the proposed in-line metrology system is presented.
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.
The low-coherence interferometry is already an established technique for the high-resolution characterization of surface
profiles. Its application in many industrial areas is however partially limited due to undesired effects in the interference
pattern caused by different surface's roughness and form properties. The appearance of speckles in rough surfaces or the
batwing-effect in high-precision topographies are examples of undesired influences. Another important limiting factor is
the size and robustness of the metrological set-ups. The measurement of small cavities or the integration in production
machines are therefore still a challenge.
In this work the application of a fiber-optical low-coherence interferometer for the characterization of different surface
profiles, as well as miniaturized and / or hard accessible features is presented. Focus will be given on the measurement of
optical "uncooperative" surfaces, as rough and / or curved surfaces, for example in small cavities, using the analysis of
the speckle phenomena.