Method of Observing the Spot Where Full-Power Counter-Propagating Laser Pulses Collide in Plasma Media

A new observation method of providing a precise collision of two full-power counter-propagating laser pulses is proposed and demonstrated. The method is a combination of top-view imaging, side-view shadowgram, extra-ultraviolet (XUV) spectrograph, and returning pulse monitoring. This allows us to align two counter-propagating laser pulses at their colliding point in a real situation (full power laser operation in plasma). The achieved spatial resolution of the monitor in the plasma is 1.35 µm with the precision level of alignment better than 15 µm even when there is plasma present.