The three gratings

At the heart of the KDTLI there are the three gratings forming the interferometer.

  1. The first (material) grating prepares the spatial coherence of the afore incoherent matter-waves of the molecules.
  2. 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.
  3. 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.