Light scattering measurement and modeling of surfaces, thin film coatings, and materials

Motivation

The tremendous development of micro- and nanotechnologies has resulted in novel challenges for surface measurement techniques. This is especially true for a sensitive, efficient and functional assessment of surfaces with anisotropic micro- and nanostructures. Such structures can be deliberately produced, e.  g. for gratings. In the opposite case, e.  g. in ultraprecision surface finish processes like diamond turning, undesirable structures occur as deviations from the intended supersmooth surface.

The structural properties of optical surfaces and thin film coatings influence their optical properties, desired or unwanted. Very often, losses through roughness-induced scattering are to be minimized. In other applications, defined surface structures are used to achieve certain scattering properties. The capabilities of Fraunhofer IOF with respect to light scattering comprise the measurement and modeling of light scattering at various wavelengths from the EUV to the visible and the IR spectral regions. Different models are employed depending on the application such as the Rayleigh-Rice theory for optical surfaces, multilayer vector scattering theories for thin film coatings, and the new Generalized Harvey-Shack theory for structured surfaces.

 

Our work

With the scatter techniques developed at the Fraunhofer IOF in Jena, the required measurements of anisotropic structures have become possible.