Fig. 2

Thon ring patterns of images of an amorphous carbon sample taken with an HFPP operated under case A, B, C conditions and corresponding phase shift profiles \(\varphi_{\text{PP}} \left( q \right)\). a Case A (small ZOB diameter ~ 100 nm, unheated HFPP) with experimental Thon ring pattern and PCTF fit after 30 s of HFPP illumination. Fit parameters are \(\varphi_{\text{PP}} \left( 0 \right) = \left( {2.76 \pm 0.06} \right) \pi\) and \(\Delta f = \left( { - 9.63 \pm 0.12} \right)\) µm. Minima and maxima of the experimental Thon ring pattern marked by red and green lines do not show distinct deviations between experimental data and fit. b Case B (small ZOB, HFPP temperature 200 °C) with experimental Thon ring pattern and PCTF fit after 150 s of illumination (upper graph) with \(\varphi_{\text{PP}} \left( 0 \right) = \left( { - 0.82 \pm 0.05} \right) \pi\) and \(\Delta f = \left( { - 0.65 \pm 0.13} \right)\) µm. Pronounced differences occur for minima and maxima of the experimental Thon ring pattern and the PCTF fit at small \(q\). The extended phase shift profile \(\varphi_{\text{PP}} \left( q \right)\) (lower graph) was calculated as the difference between the argument of the fitted PCTF and the experimental Thon ring pattern. c Case C (large ZOB ~ 250 nm, unheated HFPP) with experimental Thon ring pattern and PCTF fit (upper graph) after 150 s of illumination with \(\varphi_{\text{PP}} \left( 0 \right) = \left( { - 3.55 \pm 0.11} \right) \pi\) and \(\Delta f = \left( { - 1.73 \pm 0.03} \right)\) µm. Pronounced differences occur for minima and maxima of the experimental Thon ring pattern and PCTF at small \(q\). The extended phase shift profile \(\varphi_{\text{PP}} \left( q \right)\) (lower graph) was calculated as the difference between the argument of the fitted PCTF and the experimental Thon ring pattern