Thin Films and Surfaces @ ALPS

High Temperature Ellipsometry

Measuring the dielectric constants of metals in the liquid state by high-temperature ellipsometry is a challenging but important task, because information on optical properties of metals in their liquid state is missing.


Laser-cutting is today widely used in industrial applications. To improve the cutting performance, e.g. the quality of the cutting edge, it is necessary to understand the interaction between the laser light and the material to be cut at the cutting front. Because at the cutting front the material is in the liquid state, the interaction is dependent on the refractive index and the absorption coefficient in the liquid state. To asses this information a custom-made ellipsometer for temperatures up to 2000K has been built.


Our experimental setup allowed us to investigate the refractive index and the absorption coefficient of different metals (e.g. Au and Ag) from room temperature up to the melting point and to compare the experimental values with different theoretical models.


refraction index of liquid gold

liquid aluminum drop

In addition to the custom made ellipsometer used for this study ALPS also owns a spectrometric ellipsometer.

project team

A group of people from different ALPS research groups has collaborated for this project:

  • Dr. Marc Schmid
  • Martin Muralt 
  • Prof. Dr. Beat Neuenschwander 
  • Prof. Dr. Patrick Schwaller