In this paper the design of a Time-Domain Full-Field OCT (TD-FF-OCT) setup for non-contact volumetric layer thickness measurement is presented and quantified in terms of achievable accuracy and performance. The capabilities of the instrument regarding its measuring accuracy are verified using foil thickness standards of different strength. Afterwards, a technical application of measuring a thin and rough varnish coated PET foil (foil thickness tfoil ≈ 150 μm, rough varnish layer thickness tvarnish ≈ 10 μm) is carried out. Since the device is designed to conduct areal measurements, the thickness can be accurately determined over several measurement points. The results are compared with results achieved by applying an alternative but destructive and more time-consuming measuring method (evaluation of microscopic images of respective foil slices produced by using a microtome). Finally, the achievements are summarized and identified optimization potential is highlighted.
To further improve the technology of 3D µ-printing, we show a promising deep learning approach for correcting aberrations of the most prominent point spread functions in (STED-inspired) multi-photon lithography.
Moreover, detailed forecasts of 3D printed structures are of high interest. Therefore, an analytical method predicting deformations due to, e.g. proximity or shrinkage effects is presented. These predictions can be used as pre-compensations to achieve a maximum match between target and actual structures from the beginning.
As third topic, we discuss the recently presented continuous frequency band chirp material measure for calibration utilization with regard to its different evaluation routines.
To experimentally determine the transfer behavior and the resolution limits of areal surface topography measuring instruments, numerous approaches have been suggested with the two most common ones being based on either rectangular (type ASG material measure) or sinusoidal (chirp material measure) test geometries, imaging various spatial frequencies. Each of the methods carries individual advantages and disadvantages. Here, we describe the design of a varied chirp material measure which provides sufficient amplitudes throughout a broad range of spatial frequencies. For its evaluation, two different approaches based on either geometrical fitting or a direct analysis in the frequency domain are described and compared with each other. The material measure provides a steady spectrum in the spatial frequency domain that can be evaluated with both approaches. Their advantages and disadvantages are composed to derive information for a reliable implementation that leads to a standardized evaluation routine with small uncertainty. The examination of the two methods results in an evaluation with a high statistical reliability that allows an unambiguous determination of the spatial transfer behavior.
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