Achieving microfocus of the 13.5-NM flash beam for exploring matter under extreme conditions by Nelson, A, Lee, R, Toleikis, S, Bajt, S, Fäustlin, R, Chapman, H, Krzywinski, J, Chalupsky, J, Juha, L, Hajkova, V, Nagler, B, Vinko, S, Whitcher, T, Wark, J, Dzelzainis, T, Riley, D, Saksl, K, Khorsand, A, Sobierajski, R, Jurek, M, Andreasson, J, Timneanu, N, Hadju, J, Fajardo, M, Tschentscher, T