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.
- harmonic generation
- intense laser interaction
Dromey, B., Bellei, C., Carroll, D. C., Clarke, R. J., Green, J. S., Kar, S., ... McKenna, P. (2009). Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions. Laser and Particle Beams, 27(2), 243-248. https://doi.org/10.1017/S0263034609000329