Fig. 1. Experimental systems: scheme of the CDL system operated in Prague^{[15, 16]} and scheme of the LPP system operated at LLG in Göttingen^[17].

Fig. 2. LLG source at a wavelength of 13.5 nm: example of caustic (bottom) and dependence of ablation depth on the number of shots (top). Measurements on PMMA.

Fig. 3. CDL at a wavelength of 46.9 nm: caustic measurement wavelength 46.9 nm (below) and ablation measurement (top). The shape of the crater is almost the same along the line of the caustic. Looking at the image on the right it can be seen that the annular form is preserved although, on increasing the number of shots, its dimensions increase.

Fig. 4. CDL at a wavelength of 46.9 nm: eroded area on number of shots (100–200 shots, bottom; 10–100 shots, top).