One of the basics of laser material processing is the exact knowlegde of the laser power availible at the work piece. Even in complex processing systems often significant differences betweeen the power at the laser's output window and the power at the work piece occur.Moreover the user gets information about the laser power independent of the display at the laser source:
The method is to direct the laser beam with a parabolic mirror into a cylindrical absorber. On its inner surface there is a highly absorbing coating. By this laser power will be absorbed more homogeneously on the surface and any leakage radiation is avoided. This system can be used for highestlaser powers and power densities.
With a high-precision measurement of temperature difference and flow rate of the coolant the power of the absorbed laser beam can be exactly determined.
All parts in the device which get in contact with the cooling water are made of copper or brass. So any corrosion in the coolant circuit because of different chemical potentials will be avoided. A pneumatic shutter is used to close the beam input aperture and to protect the entrance mirror of the PowerMonitor against dust.
For interfacing to a PC the built- in RS485-lnterface (PRIMES priority) is used. The picture shows the graphical user interface. You have the choice for maximum scale value, offset compensation and shutter open/closed. Additionally to the calculated and shown laser power, water input temperature as well as difference between input and outlet temperature and flow rate is displayed. 'Current value' or 'temporeal development' of laser power can be selected.