Precision Control of Mirror-Grating Phasing for a Large Aperture Pulse Compressor

Tiled-grating compressors of ultra-short pulse multi-petawatt lasers are currently the only viable way how to meet beam size requirements and stay within the damage threshold of the largest available gratings. Recently, a method how to double the effective aperture of compressor gratings by phasing them with perpendicularly positioned mirrors has been proposed, providing simplification to the traditional grating-grating tiling scheme by reducing the number of alignment degrees of freedom. The drawback of the method lies in tighter requirements on adjustment precision and stability of the system making the alignment and monitoring a challenging task. Here we propose and analyze different approaches to precision control of mirror-grating phasing and present a comparative experimental verification of the alignment systems on a small-scale test bench.