Compression grating alignment by far-field monitoring

Abstract

Slight non-parallelism of the gratings in the compressor of a chirped-pulse amplification laser system produces angular chirp which results in a significant reduction of the focused intensity due to elongation of the pulse duration and enlargement of the focal spot. The effect of three-dimensional relative misalignment angles between two gratings on the far-field pattern of the pulses propagating through them is investigated by ray tracing. The far-field pattern provides two-dimensional information of the uncompensated angular dispersion directly. A simple and intuitive alignment procedure to achieve parallelism of the compression gratings by far-field monitoring is demonstrated experimentally, while the alignment precision is found to be the same as the methods proposed previously.