Plasma eyepieces for petawatt class lasers.

Focusing petawatt class laser beams to a variety of spot sizes for different applications is expensive in cost, labor, and space. In this paper, we propose a plasma lens to flexibly resize the laser beam by utilizing the self-focusing effect of laser in plasmas. Using a fixed conventional focusing system to focus the laser a short distance in front of the plasma, we can adjust the effective laser beam waist within a certain range, with the plasma lens acting as an adjustable eyepiece in a telescope. Such a setup is a powerful tool for laser wakefield accelerator experiments in state-of-the-art petawatt laser projects and allows for scanning focal spot parameters. [ABSTRACT FROM AUTHOR]