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Proceedings Paper

Microhole drilling using reshaped pulsed Gaussian laser beams
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Paper Abstract

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.

Paper Details

Date Published: 30 October 2001
PDF: 9 pages
Proc. SPIE 4443, Laser Beam Shaping II, (30 October 2001); doi: 10.1117/12.446744
Show Author Affiliations
Dimitris Karnakis, Exitech Ltd. (United Kingdom)
Jim Fieret, Exitech Ltd. (United Kingdom)
Phil T. Rumsby, Exitech Ltd. (United Kingdom)
Malcolm C. Gower, Exitech Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 4443:
Laser Beam Shaping II
Fred M. Dickey; Scott C. Holswade; David L. Shealy, Editor(s)

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