PURPOSE: Two dimensional diffraction patterns with crystal symmetries.

DESCRIPTION: These optical crystals consist of simple arrays of various shaped diffraction centers arranged with several two dimensional symmetries. Diffraction by such a crystal produces a pattern with the symmetry of the scattering slide. Winner of the 1973 AAPT apparatus competition.

SUGGESTIONS:

REFERENCES: (PIRA 6D20.57)

EQUIPMENT: Laser cart with optical crystals.

SETUP TIME: None.