Laser and Particle Beams

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Laser and Particle Beams (2009), 27:243-248 Cambridge University Press
Copyright © Cambridge University Press 2009

Research Article

Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions

B. Dromeya1, C. Belleia2, D.C. Carrolla3, R.J. Clarkea4, J.S. Greena2, S. Kara1, S. Kneipa2, K. Markeya1, S.R. Nagela2, L. Willingalea5, P. McKennaa3, D. Neelya4, Z. Najmudina2, K. Krushelnicka5, P.A. Norreysa4 and M. Zepfa1 c1

a1 Department of Physics and Astronomy, Queens University Belfast, Belfast, UK
a2 Blackett Laboratory, Imperial College London, London, UK
a3 SUPA, Department of Physics, University of Strathclyde, Glasgow, UK
a4 Central Laser Facility, STFC Rutherford Appleton Laboratory. Chilton, Didcot, Didcot, UK
a5 Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan
Article author query
dromey b [Google Scholar]
bellei c [Google Scholar]
carroll dc [Google Scholar]
clarke rj [Google Scholar]
green js [Google Scholar]
kar s [Google Scholar]
kneip s [Google Scholar]
markey k [Google Scholar]
nagel sr [Google Scholar]
willingale l [Google Scholar]
mckenna p [Google Scholar]
neely d [Google Scholar]
najmudin z [Google Scholar]
krushelnick k [Google Scholar]
norreys pa [Google Scholar]
zepf m [Google Scholar]


As the state of the art for high power laser systems increases from terawatt to petawatt level and beyond, a crucial parameter for routinely monitoring high intensity performance is laser spot size on a solid target during an intense interaction in the tight focus regime (<10 µm). Here we present a novel, simple technique for characterizing the spatial profile of such a laser focal spot by imaging the interaction region in third harmonic order (3ωlaser). Nearly linear intensity dependence of 3ωlaser generation for interactions >1019 Wcm−2 is demonstrated experimentally and shown to provide the basis for an effective focus diagnostic. Importantly, this technique is also shown to allow in-situ diagnosis of focal spot quality achieved after reflection from a double plasma mirror setup for very intense high contrast interactions (>1020 Wcm−2) an important application for the field of high laser contrast interaction science.

(Received November 15 2008)

(Accepted January 05 2009)

KeywordsHarmonic generation; Intense laser interaction


c1 Address correspondence and reprint requests to: Matthew Zepf, Department of Physics and Astronomy, Queens University Belfast, Belfast BT7 1NN, UK. E-mail: [email protected]