Figure 1.

Illustration of the split-and-delay concept with the X-ray Photon Correlation Spectroscopy technique. A single LCLS X-ray pulse is split into two equal intensity pulses using the hard X-ray split-and-delay unit. The pulse paths are recombined and propagate collinearly in the sample direction. The summed speckle pattern from the two pulses is collected by a 2D detector. Contrast of the speckle pattern is analysed as a function of delay time τ.