Fig. 3

Experiment on the focused EUV OAM with high degree of freedom, a prior to focus, b near focus, c after focus, d Correlation coefficient curve between the (a)-(c) and a series of theoretical diffractograms from minus 40 \(\mu\)m to plus 40 \(\mu\)m derived from the focal plane, the red line, green line and blue lines correspond to the correlation coefficients curves in (a), (b) and (c), respectively. f Recovered phase map corresponds to the square block diagram in (e). g Diagonal intensity distribution of experimental results versus the theory