16 February 2012 Direct investigation of the ablation rate evolution during laser drilling of high-aspect-ratio micro-holes
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Proceedings Volume 8243, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XVII; 82430S (2012); doi: 10.1117/12.905758
Event: SPIE LASE, 2012, San Francisco, California, United States
Abstract
The recent development of ultrafast laser ablation technology in precision micromachining has dramatically increased the demand for reliable and real-time detection systems to characterize the material removal process. In particular, the laser percussion drilling of metals is lacking of non-invasive techniques able to monitor into the depth the spatial- and time-dependent evolution all through the ablation process. To understand the physical interaction between bulk material and high-energy light beam, accurate in-situ measurements of process parameters such as the penetration depth and the removal rate are crucial. We report on direct real time measurements of the ablation front displacement and the removal rate during ultrafast laser percussion drilling of metals by implementing a contactless sensing technique based on optical feedback interferometry. High aspect ratio micro-holes were drilled onto steel plates with different thermal properties (AISI 1095 and AISI 301) and Aluminum samples using 120-ps/110-kHz pulses delivered by a microchip laser fiber amplifier. Percussion drilling experiments have been performed by coaxially aligning the diode laser probe beam with the ablating laser. The displacement of the penetration front was instantaneously measured during the process with a resolution of 0.41 μm by analyzing the sawtooth-like induced modulation of the interferometric signal out of the detector system.
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Francesco P. Mezzapesa, Teresa Sibillano, Lorenzo L. Columbo, Francesca Di Niso, Antonio Ancona, Maurizio Dabbicco, Francesco De Lucia, Pietro M. Lugarà, Gaetano Scamarcio, "Direct investigation of the ablation rate evolution during laser drilling of high-aspect-ratio micro-holes", Proc. SPIE 8243, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XVII, 82430S (16 February 2012); doi: 10.1117/12.905758; https://doi.org/10.1117/12.905758
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KEYWORDS
Laser ablation

Laser drilling

Aluminum

Metals

Interferometry

Semiconductor lasers

Sensors

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