Measurement of laser absorptivity for operating parameters characteristic of laser drilling regime
TypeArticles dans des revues avec comité de lecture
Laser drilling in the percussion regime is commonly used in the aircraft industry to drill sub-millimetre holes in metallic targets. Characteristic laser intensities in the range of 10 MW cm−2 are typically employed for drilling metallic targets. With these intensities the temperature of the irradiated matter is above the vaporization temperature and the drilling process is led by hydrodynamic effects. Although the main physical processes involved are identified, this process is not correctly understood or completely controlled. A major characteristic coefficient of laser–matter interaction for this regime, which is the absorptivity of the laser on the irradiated surface, is still unknown, because of the perturbing effects due to laser beam geometrical trapping inside the drilled hole. So, by using time resolved experiments, this study deals with the direct measurement of the variation of the intrinsic absorption of aluminium, nickel and steel materials, as a function of the incident laser intensity up to 20 MW cm−2. We observe that for this incident intensity, the absorptivity can reach up to 80%. This very high and unexpected value is discussed by considering the microscopic behaviour of the heated matter near the vapour–liquid interface that undergoes possible Rayleigh–Taylor instability or volume absorption
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SCHNEIDER, Matthieu; BERTHE, Laurent; FABBRO, Rémy; MULLER, Maryse; NIVARD, Mariette (AIP, 2007)This article deals with the gas effect on percussion laser drilling in ms pulse duration range. On the one hand, the flow of assistance gas jet is investigated with and without a target using a strioscopy setup and Pitot’s ...
SCHNEIDER, Matthieu; BERTHE, Laurent; MULLER, Maryse; FABBRO, Rémy (AIP, 2010)This paper presents an original method for analyzing laser drilled holes. The so-called Direct Observation of Drilled hOle (DODO) method is introduced and its applications. The hole characterization that’s been made is ...
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MULLER, Maryse; EL-RABII, Hazem; FABBRO, Rémy (Springer, 2015)In this article, we report an investigation of laser-initiated ignition of pure iron rods, using optical pyrometry, video observations, and analysis of metallographic cross section of quenched burning liquid on copper ...
Temperature measurement of laser heated metals in highly oxidizing environment using 2D single-band and spectral pyrometry MULLER, Maryse; FABBRO, Rémy; EL-RABII, Hazem; HIRANO, Koji (Laser Institute of America, 2012)Calibration and validation of two temperature measurement techniques both using optical pyrometry, usable in the framework of the study of the heated metals in highly oxidizing environments and more generally during laser ...