Two-Dimensional Light Diffraction from an EPROM Chip

In introductory physics classes, a laser pointer and a compact disc are all the items required to illustrate diffraction of light in a single dimension. If a two-dimensional diffraction pattern is desired, double axis diffraction grating material is available or a CCD sensor can be extracted from an unused electronics device. This article presents an alternative to the above methods for obtaining a two-dimensional diffraction pattern. The advantages of this method are that no disassembly is required, the spacing in each axis is different, and many students are better able to understand how crystal-lography works when using objects instead of slits.