Laser oxygen cutting is a process used especially to cut metallic materials which consists to focus a laser beam on a metallic target in order to melt it and to trigger an exothermic reaction oxidation between melted metal and oxygen. The estimation of the temperature during this process is a key point to control the process and improve the efficiency. This temperature must be sufficient to maintain the oxidation reaction of the melt metal(Tm=1800K) but it must not exceed the dissociation temperature of iron and dioxygen estimated at 3660K [1]. The real-time measurement of the temperature provides a control of laser cutting process, and makes it optimizable. Measuring the temperature of a melted metallic surface needs to go through many technical difficulties such as:
High amplitude of the temperature scale. The temperature level is very high, it can reach more than 3000K,the measurement extends over a wide range (Tɛ[Tm;3660K]).
Real-time control process. The process health monitoring need to be done in real time to control the process in a better way.
Non-contact measurements. The process generates a lot of melt particles and the kerf and the cutting front edge can be unstable so it is necessary to make non-contact measurements sufficiently far from the cutting area to avoid damage to the measuring system the emission factor of the surface evolves strongly during the process and can significantly influence the temperature estimation.
To reach the goal, we have chosen the Short wavelength pyrometry technique by photon counting method for temperature measurement.
In this paper, we will describe the method and the device that we have set-up and discuss the different performances (working temperature range, signal-to-noise ratio, etc.). Particular attention will be given to the effect of the emission factor on the accuracy of the measurements. We also show the results obtained in the case of the laser oxygen cutting in order to understand the appearance striation and different cutting regime.