30 October 2001 Microhole drilling using reshaped pulsed Gaussian laser beams
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With the aim of reducing the heat-affected zone to improve edge quality, we present results of drilling microholes using reshaped pulsed Gaussian laser beams. A diode-pumped, high repetition rate, nanosecond pulse duration 3rd harmonic Nd:YAG laser was reshaped such that the intensity gradient in the outer region of the focussed laser beam profile is increased. Compared to focussed Gaussian laser beams, such hard-edged intensity distributions produce smaller heat-affected zones. As a result there is less associated collateral damage, debris, remelt produced by the near-ablation threshold fluences. Specially designed spherically-aberrating Galilean telescopes are used to reshape the primary Gaussian laser beam into a quasi-tophat distribution at the mask plane. Gaussian illumination propagation simulations using Monte-Carlo ray tracing calculations compare well with measurements of reshaped distributions made with a beam profiler. Drilling trials in polymers and silicon nitride demonstrated improved edge quality, reduced debris and wall roughness and a significant reduction in the energy density required for drilling microholes of high aspect ratio.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dimitris Karnakis, Dimitris Karnakis, Jim Fieret, Jim Fieret, Phil T. Rumsby, Phil T. Rumsby, Malcolm C. Gower, Malcolm C. Gower, } "Microhole drilling using reshaped pulsed Gaussian laser beams", Proc. SPIE 4443, Laser Beam Shaping II, (30 October 2001); doi: 10.1117/12.446744; https://doi.org/10.1117/12.446744


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