Probe Window Contamination and Reflectance

Abstract

In practical metrology, especially in industrial environments, the measurement conditions are usually hostile. If we consider for instance the quality assessment of process liquids in process industry such as paper mill the contamination of the probing face of prism reflectometer is a drawback. In other words different constituents of the liquid can be adsorbed on the probe face. This in turn causes change in the reflectance signal either because of the change of the complex refractive index or because of light scattering in the vicinity of interface between the liquid and the probe face. In this chapter we briefly describe simple models that may be used for evaluation of the growth of contamination on the probe window. Then we are talking about adsorption. In addition we consider a totally contaminated layer and related depth profiling.