Ultra high axial resolution (UHR) was demonstrated early in the development of optical coherence tomography (OCT), but has not yet reached clinical practice. We present the combination of supercontinuum light source and line field (LF-) OCT as a technical and economical route to get UHR-OCT into clinic and other OCT application areas. We directly compare images of a human donor cornea taken with low and high resolution current generation clinical OCT systems with UHR-LF-OCT. These images highlight the massive information increase of UHR-OCT. Application to pharmaceutical pellets, and the functionality and imaging performance of different imaging spectrograph choices for LF- OCT are also demonstrated.
The multiple layer paint systems on modern cars serve two end purposes, they firstly protect against corrosion and
secondly give the desired visual appearance. To ensure consistent corrosion protection and appearance, suitable Quality
Assurance (QA) measures on the final product are required. Various (layer thickness and consistency, layer composition,
flake statistics, surface profile and layer dryness) parameters are of importance, each with specific techniques that can
measure one or some of them but no technique that can measure all or most of them. Optical Coherence Tomography
(OCT) is a 3D imaging technique with micrometre resolution. Since 2016, OCT measurements of layer thickness and
consistency, layer composition fingerprint and flake statistics have been reported. In this paper we demonstrate two more
novel applications of OCT to automotive paints. Firstly, we use OCT to quantify unwanted surface texture, which leads
to an “orange peel” visual defect. This was done by measuring the surface profiles of automotive paints, with an unoptimised
precision of 37 nm over lateral range of 7 mm, to quantify texture of less than 500 nm. Secondly, we
demonstrate that OCT can measure how dry a coating layer is by measuring how fast it is still shrinking quasiinstantaneously,
using Fourier phase sensitivity.
A Fourier domain (FD) optical coherence tomography (OCT) system is shown to be capable of profilometry with two
orders of magnitude better accuracy than the axial imaging resolution of the system. High precision OCT profilometry
not only achieves similar accuracy as commercial white light interferometry based profilometers but is also capable of
profilometry on complex subsurface structures with multiple interfaces of low reflectance. An accuracy of 55nm was
achieved with a ThorLabs SROCT on a lab bench without special
anti-vibration devices. This technique has the potential
for a range of applications, such as high precision refractive index measurements and simultaneous dynamic monitoring
of the interface structure of a drying varnish and the substrate.