Purpose: Demonstrate diffraction (well, actually interference) by a grating.
Description: Several different gratings can be readily mounted into the laser beam to study the effect of grating spacing: (1) 570 slits per mm, (2) 13,400 slits per inch, and (3) a triple grating with 2400 slits per inch, 7500 slits per inch, and 15,000 slits per inch. The patterns from the three slits of the triple grating are shown above.
