Single Slit or Pinhole Diffraction

PIRA 6C10.10

Mount a laser on the optics bench along with the slide with variable width thin slits to show diffraction of light as shown in the picture at far left.  Project the image of the slits on a distant screen or smooth light-colored wall.  For wider slits, use the beam expander as shown in the picture at near left.  Circular diffraction patterns can be achieved from laser light passed through a pinhole in aluminum foil mounted on a slide.  The room must be made very dark for the diffraction patterns to be clearly visible.