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

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • B. Dromey
  • C. Bellei
  • D. C. Carroll
  • R. J. Clarke
  • J. S. Green
  • S. Kar
  • S. Kneip
  • K. Markey
  • S. R. Nagel
  • L. Willingale
  • P. McKenna
  • D. Neely
  • Z. Najmudin
  • K. Krushelnick
  • P. A. Norreys
  • M. Zepf
<mark>Journal publication date</mark>06/2009
<mark>Journal</mark>Laser and Particle Beams
Issue number2
Number of pages6
Pages (from-to)243-248
Publication StatusPublished
<mark>Original language</mark>English


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 mu m). 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 (3 omega(laser)). Nearly linear intensity dependence of 3 omega(laser) generation for interactions > 10(19) 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 (> 10(20) Wcm(-2)) an important application for the field of high laser contrast interaction science.