Contents

17 August 1990
Vol 249, Issue 4970

About The Cover

Schematic representation of how matter can be organized in optical standing waves formed by interfering laser beams. Here five beams force the microscopic spheres into a quasi-crystalline lattice. The red spots in the background indicate the fivefold diffraction pattern obtained from a separate probe laser. See page 749. [Illustration courtesy of M. Burns and J. Scarpetti, Rowland Institute]