Abstract: An online monitoring and adaptive control during laser material processing is necessary for quality assessment and a relatively new way consists in using the information given by the inclination of the keyhole. In this project an existing electro-optical device is tested and improved in order to measure the polarisation state of the infrared light by means of nematic liquid crystals which is emitted by a thermal emitter that simulates a heated workpiece . The main improvement which has been carried out is the unification of various functions in one LabVIEW program with the goal of making a more compact setup and a fully automated process for the later transfer of the device onto a robot used for laser welding. Moreover a description about all the components of the device is given and also a checking of these has been performed. Finally some recommendations for further studies related to improving the LabVIEW program and enhancing the setup are given.