At the heart of the KDTLI there are the three gratings forming the interferometer.
- The first (material) grating prepares the spatial coherence of the afore incoherent matter-waves of the molecules.
- The second grating, a standing light wave, is realized by reflecting a laser beam on a mirror and overlapping it with the back-reflected beam. According to the Kapitza-Dirac effect the phase of the matter-wave is periodically modulated by the laser’s electrical field. Here, the diffraction of the coherent matter-waves is taking place.
- At the third grating an interference pattern is formed according to the Talbot-Lau effect. This material grating acts as a mask which is shifted during an interference scan and which, thereby, scans the interference image.