A look into the nanoscale

A visible light laser beam (i) is focused onto the sample (iii) and acts as the excitation pulse. A soft X-ray pulse (ii) is focused to the same location but at a continuously variable delay. The X-ray pulse diffracts from the sample, carrying information about the transient sample structure to the CCD detector (v) in the form of a coherent diffraction pattern. A mirror (iv) separates the direct beam from the diffracted light: the direct FEL beam (vi) passes straight through a hole in the mirror and is not detected in the CCD image.