Sensors

The formation of periodic striations is a typical characteristic of metals laser cutting process.
The depth of these striations is not strongly influenced by laser power variation, while cutting speed is a very important parameter in determinination of cutting edges characteristcs.

By these considerations, a device has been realized by Centro Laser, based on the analysis of infrared emission coming from the cutting zone.
It is a self-learning based device, that calculates the frequency of infrared emission, correlates it to roughness frequence and set the working parameters in order to minimize the cutting edges roughness.

With this device it is possible to obtain roughness levels 30% lowest than the values obtained with non controlled processes.

Centro Laser developed a device, based on three electro-optical modules, to obtain online information on CO₂ laser steels welding.
These three modules collect infrared, ultraviolet and visibile emission.
Two visibile transitions in the visibile zone are used to calculated plasma electronic temperature.

The statistical analysis of the time series of these three values allows considerations about the process behaviour and the presence of defects on the weld bead.

Further information can be obtained by observing frequence distribution of the signals: a gaussian behaviour is generally an indication of good weld bead.

Finally, signals standard deviation gives information on the process, and allows to detect macroscopic defects in the weld seam.

To obtain the desired surface modification to a metal workpiece, it is necessary to furnish the exact energy amount needed to the request treatment.
Generally, a certain modification happens at a well defined temperature.
For this reason it is very important to perform surface processes at constant temperature.

Centro Laser developed a device that reads temperature on the process zone, by means of a dual wavelength pyrometer, and controls laser power in order to maintain it constant.

The correlation between temperature and laser power is obtained by a mathematical model based on Fourier equation.
The sensor has been installed and characterized on a CO₂ laser workstation for sintered steels surface treatment.

During paint removal process by excimer laser it is possible to observe the formation of a plasma due to the vaporization of the paint system.
The spectroscopical emission of this plasma changes as changes the nature of the material at the interaction zone.

On these basis Centro Laser developed a device detecting in realtime plasma emission in a well defined spectral zone, and regulates the working frequency of excimer laser in order to ensure the complete removing of the paint and to avoid substrate damages.

This device has been characterized for paint stripping on composite substrates for aerospace industry.

Tha aim of this activity is the development of a modular sensor for plastic cutting and weldng process.

During laser treatment of plastics, the temperature at the interaction zone is a very important parameter for process diagnostic.
In plastic welding, also the pressure gives information about the process.

Temperature is measured by means of a pyrometer, while pressure, determined by the volume increasing of the molten material, can be measured by piezoelectric sensors placed below the interaction zone.
These signals are then used to regulate laser power and optimize the process.