Development of a coupled thermo-optical process optimisation routine for plastic lenses in laser applications

For high power laser applications, the use of plastic lenses is difficult to realise due to the high temperature dependence of the optical properties, the low temperature resistance and high thermal expansion. For this reason, the IKV in cooperation with the Chair of Technol ogy of Optical Systems (TOS), RWTH Aachen, Germany, developed a design routine that couples thermo and optical process optimisation in order to increase the effective design of plastic optics for laser applications and reduce cost-intensive tool iterations. Therefore, this contribution presents the coupled thermo-optical process optimisation routine and pro vides a practical validation of the developed method. The results of the characterisation of the required optical properties in this system will be also introduced. To validate the effectiveness of the coupled routine, a planar-convex lens, which usually requires very high geometrical accuracy in practical applications, is used as an exemplary geometry. After the process optimisation and simulation, the deformed geometry was very close to the desired lens geometry in thermally unloaded state, with an average difference between the two geometries of 0.36 µm, compared to 0.04 mm prior to optimisation.