摘要
We investigate the spatial characteristics of high-order harmonic radiation generated in argon and observe cross-like patterns in the far field.An analytical model describing harmonics from an astigmatic driving beam reveals that these patterns result from the order and generation position-dependent divergence of harmonics.Even small amounts of driving field astigmatism may result in cross-like patterns,coming from the superposition of individual harmonics with spatial profiles elongated in different directions.By correcting the aberrations using a deformable mirror,we show that fine-tuning the driving wavefront is essential for optimal spatial quality of the harmonics.
基金
support from the Swedish Research Council(2013-8185,2021-04691,2017-04106,and 2021-05992)
the European Research Council(advanced grant QPAP,884900)
the Knut and Alice Wallenberg Foundation(KAW 2020.0111).
