
Proceedings Paper
Optical coherence and beamspread in ultrafast-laser pulsetrain-burst hole drillingFormat | Member Price | Non-Member Price |
---|---|---|
$17.00 | $21.00 |
Paper Abstract
Pulsetrain-burst machining has been shown to have advantages over single-pulse laser processing of materials
and biological tissues. Ultrafast lasers are often able to drill holes in brittle and other difficult materials without
cracking or swelling the target material, as is sometimes the case for nanosecond-pulse ablation; further,
pulsetrain-bursts of ultrafast pulses are able to recondition the material during processing for instance, making
brittle materials more ductile and striking advantages can result. In the work we report, we have investigated
hole-drilling characteristics in metal and glass, using a Nd:glass pulsetrain-burst laser (1054 nm) delivering 1-10
ps pulses at 133 MHz, with trains 3-15 μs long. We show that as the beam propagates down the channel being
drilled, the beam loses transverse coherence, and that this affects the etch-rate and characteristics of channel shape:
as the original Gaussian beam travels into the channel, new boundary conditions are imposed on the
propagating beam principally the boundary conditions of a cylindrical channel, and also the effects of plasma
generated at the walls as the aluminum is ablated. As a result, the beam will decompose over the dispersive
waveguide modes, and this will affect the transverse coherence of the beam as it propagates, ultimately limiting
the maximum depth that laser-etching can reach.
To measure transverse beam coherence, we use a Youngs two-slit interference setup. By measuring the fringe
visibility for various slit separations, we can extract the transverse coherence as a function of displacement across
the beam. However, this requires many data runs for different slit separations. Our solution to this problem
is a novel approach to transverse coherence measurements: a modified Michelson interferometer. Flipping the
beam left-right on one arm, we can interfere the beam with its own mirror-image and characterise the transverse
coherence across the beam in a single shot.
Paper Details
Date Published: 8 September 2006
PDF: 12 pages
Proc. SPIE 6343, Photonics North 2006, 63432A (8 September 2006); doi: 10.1117/12.707967
Published in SPIE Proceedings Vol. 6343:
Photonics North 2006
Pierre Mathieu, Editor(s)
PDF: 12 pages
Proc. SPIE 6343, Photonics North 2006, 63432A (8 September 2006); doi: 10.1117/12.707967
Show Author Affiliations
Jesse Dean, Univ. of Toronto (Canada)
Paul Forrester, Univ. of Toronto (Canada)
Martin Bercx, Univ. of Toronto (Canada)
David Graper, Univ. of Toronto (Canada)
Paul Forrester, Univ. of Toronto (Canada)
Martin Bercx, Univ. of Toronto (Canada)
David Graper, Univ. of Toronto (Canada)
Luke McKinney, Univ. of Toronto (Canada)
Felix Frank, Univ. of Toronto (Canada)
Marc Nantel, Univ. of Toronto (Canada)
Ontario Ctrs. of Excellence Inc. (Canada)
Robin Marjoribanks, Univ. of Toronto (Canada)
Felix Frank, Univ. of Toronto (Canada)
Marc Nantel, Univ. of Toronto (Canada)
Ontario Ctrs. of Excellence Inc. (Canada)
Robin Marjoribanks, Univ. of Toronto (Canada)
Published in SPIE Proceedings Vol. 6343:
Photonics North 2006
Pierre Mathieu, Editor(s)
© SPIE. Terms of Use
