© Eli Sidman, Technical Services Group, MIT.
The upper trace shows a close to perfect single-slit diffraction pattern created by passing red laser light through a narrow slit. Most of the light is in the center lobe, but four additional lobes are clearly visible on either side. The lower trace displays the effect of combining diffraction patterns that are from slits close together. The bead-like appearance arises from the periodic two-slit interference pattern that is superimposed on the individual one-slit diffraction patterns. (Unit: 5)