Researchers rely on Newton's interference for new experiment

The FEL pulse from the left passes through a hole in a multilayer-coated detector mirror. The "dusty mirror" consists of particles on a 20-nm-thick silicon nitride membrane backed by a multlayer-coated plane mirror. This returns the direct beam back through the hole in the detector mirror, which reflects the diffracted light onto a CCD detector. The prompt diffraction (blue, the reference wave) and delayed diffraction (red, the object wave) interfere to generate the hologram on the CCD detector.