Surface profile characterization using low NA fibre optic sensors based on low-coherence interferometry

The overall effort in the high-technological industrial sector to increase die efficiency of products, as well as its life time, leads to the development of highly optimized parts, i.e. consumer goods. An example is the manufacture of complex surfaces with special structures and roughness values. Due to either a sensible surface or to a structure witii a very complex surface, the usage of non-contact measurement solutions for a product functional evaluation is demanded. This paper presents a robust optical solution for surface characterization based on optical fibres and white light interferometry, which features a high degree of miniaturization and accuracy in the range of a few nanometers. The experiments will make use of a special fibre optical sensor construction, using a GRIN (gradient index) fibre for the light beam focusing. In contrast to previous investigations this fibre optical probes have a significant diameter reduction. At the end the measurement results are going to be evaluated based on the ISO-Standards and compared to the tactile and to the previous high-NA probe results.