Device for measuring the polarisation of a laser beam having a high continuous wave power

摘要

During material processing (machining) with high-power lasers, it is important to know the polarisation properties of the laser beam as well as the radiated power. In the case of the high powers which are normal in this field of application, the known devices are largely incapable of polarisation measurement. The device according to the invention makes use of the fact that the reflection of a metal surface is heavily dependent on the polarisation direction of the radiation when said radiation is incident virtually tangentially. Metal surfaces of different design are thus placed in a laser beam such that the reflection of this beam on them takes place virtually tangentially and such that the portion of radiation thus reflected strikes a receiver. The overall arrangement is designed such that it can be rotated about the beam axis. A change of polarisation direction and polarisation intensity can be measured during rapid rotation about this axis. If a plurality of receiver elements are used, the spatial structure of the intensity and polarisation of a laser beam can also be determined.