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4.3
Measuring principle
The device determines the laser power in the power measuring unit according to the calorimetric principle.
For this purpose the absorber of the power measuring unit is irradiated with the laser for a defined time.
Using the known absorber mass and the specific heat capacity of the absorber material, the introduced
energy can be calculated by the measured temperature increase. The measured exposure time can then be
used to calculate the power.
The beam geometry and the power density distribution are measured by the camera-based beam analysis
unit using a CCD sensor. The measurement of beam parameters require an external z-axis.
The measurement data is transmitted to the system control via a PROFIBUS
The beam coming from the laser is transmitted through the beam entrance to deflection mirror 1 and from
there to a beam splitter.
The lagest part of the beam enters an absorber which is part of the power measurement unit.
The attenuated beam reaches the beam analysis unit (CCD sensor) via deflecting mirror 2.
The power measuring unit is used to determine the power and the beam analysis unit is used to measure the
beam position and geometry, the caustic and the power density distribution.
Absorber
Fig. 4.2:
Beam path inside FPM
Please note that the measuring plane in the FPM is below the entrance plane, depending on the
magnification and the configuration. (see chapter 17 „Technical Data" on page 85).
12
Measuring Position
CCD-Sensor
Shutter
Deflection
Mirror 2
Beam Splitter
FocusParameterMonitor FPM
or PROFINET
®
Beam Entrance
Entrance level
Measurement level
Protective Window
Deflection Mirror 1
Revision 06 EN 02/2023
interface.
®
Cartridge
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