Focusing XFEL pulses with mirrors

In Japan, a research team led by Professor K. Yamauchi (Osaka University) and Professor T. Ishikawa (Riken, Harima, Japan) has recently succeeded in focusing ultra short X-ray laser pulses from the SPring-8 Angstrom Compact free electron LAser (SACLA). With reflective optics comprising elliptically figured mirrors with nm accuracy to preserve a coherent wavefront, they have obtained a focused small beam of 0.95 × 1.20 μm² at 10 keV. The estimated achievable power density at the sample position is 6 × 10¹⁷ W/cm². For more information, see the paper, "Focusing of X-ray free-electron laser pulses with reflective optics", H. Yumoto et al., Nature Photonics, 7, 43 (2013).