High precision dynamic multi-interface profilometry with optical coherence tomography

Optical coherence tomography (OCT) has mostly been used for high-speed volume imaging but its profilometry potentials have not been fully exploited. This paper demonstrates high precision (as good as ~50 nm) multi-interface profilometry using a Fourier domain OCT system without special antivibration devices. The precision is up to 2 orders of magnitude better than the depth resolution of the OCT. Detailed analysis of the precision achieved for different surfaces is presented. The multi-interface profiles are obtained as a by-product of the tomography data. OCT has the advantage in speed and sensitivity at detecting rough and internal interfaces versus conventional optical profilometry. An application of the technique to the dynamic monitoring of varnish drying on paintlike substrates is demonstrated, which provides a better understanding of the formation of surface roughness. The technique has potential benefits in the fields of art conservation, coatings technology, and soft matter physics.