Alignment of a multigrating mosaic compressor in a PW-class CPA-laser

The coherent adding (tiling) of gratings is a promising alternative to large single gratings for highest-power CPA lasers. However, in order to obtain both temporally and spatially undistorted beam profiles it is necessary to align the mosaic gratings accurately to less than λ/20 with respect to one another. This paper is aimed at a thorough description of the alignment procedure, which uses both spatial and temporal properties of the laser beam to detect grating misalignments. The main emphasis lies within the analysis of the k -space, which becomes accessible by focussing the compressed laser-pulse or a monochromatic alignment laser, respectively. We present the effect of grating misalignments on both focal area and near field by propagating continuous-wave, monochromatic laser light through a misaligned tiled grating compressor.