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

B. Dromey, C. Bellei, D.C. Carroll, R.J. Clarke, J.S. Green, S. Kar, S. Kneip, K. Markey, P. McKenna

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


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.
Original languageEnglish
Pages (from-to)243-248
Number of pages5
JournalLaser and Particle Beams
Issue number2
Publication statusPublished - Jun 2009


  • harmonic generation
  • intense laser interaction


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