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P. Drobniak:
"Measurement of the state of polarisation of partially linear polarised infrared radiation by means of nematic liquid crystals";
Supervisor: G. Liedl, G. Humenberger; Institut für Fertigungstechnik und Hochleistungslasertechnik, 2016; final examination: 2016-11-16.

There is an increasing need for laser machining processes quality assessment and understanding. For this purpose, the idea of this Master's Thesis is to use the infrared radiation of the heated laser machined material in order to compute the tilt angle of its radiating surface. What makes the project interesting is the use of electrically driven nematic liquid crystals so that the whole electro-optical assembly is autonomous without any rotating component. In a first stage, some basics of optics are introduced such as polarisation of light or Stokes vector of a partially polarised light beam. In second phase, the optical assembly engineered for experimentation is presented. Then the setup is tested on linear polarised infrared radiation. Subsequently, the precision of the results is discussed and several sources of inaccuracy are investigated. Finally, some hints are given for a further study of the topic and ideas of enhancements to the setup are formulated.

laser material processing, polarisation