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Quality control of microchemical products is based on the inspection of surface topography, film thickness and other optical constants. Especially for lab-on-chip applications, there is a strong demand for concurrent metrology and passive layer thickness observation. Chromatic confocal microscopy is a common method to reconstruct surface topographies, while thin film reflectometry is a technique for measuring film thicknesses. In this work, we present a combination of these two established techniques, simultaneously determining topography and film thickness. The proposed spectrometric measuring system captures confocal and thin film signals from a given sample. The extracted signals are analyzed according to a given model by a least-squares estimator in order to extract the parameters of interest. Finally, the sample's film thickness and topography are locally determined at the same time and with high precision. By scanning the sample surface laterally, both the surface topography and its film thickness can be reconstructed. The presented measurements performed at a test object exhibit excellent performance of the method.

Instantaneous measurement of optical or geometrical parameters of thin layers is an ambitious aim in many industrial applications. These layers have a variety of use-cases, such as optical bandpassing, dielectric permittivity, or lubrication. Mostly, these layers are in motion due to the production process. In order to observe process parameters, the motion usually has to be disrupted. Thus, the increase of production time due to control purposes is an undesirable drawback of this otherwise suitable technique. In this publication, we present a solution to this particular drawback of most production process monitoring systems exemplarily for film thickness measurement. We show the realization of a measurement principle which has, to our knowledge, never been published before in this application. Therefore, we exploit the advantages of the combination of a linear variable filter with a complementary metal oxide semiconductor sensor array. By an apt readout sequence, this measurement system is able to measure transmission spectra while the target is in motion. We show that this measurement system is able to measure film thicknesses of objects in the range of several 100 nm thickness at up to a velocity of 4 m/s. A reproducibility below 2 nm was acquired.

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