Laser diffraction determination of the crystalline structure of an electrorheological fluid.

The electric-field-induced structures of small glass spheres in silicone oil produce laser diffraction patterns which verify, for the first time, the body-centered-tetragonal lattice structure predicted by theory. By n mechanism totally unlike that of conventionnl x-ray scattering, the incident laser beam propagates through the lattice of close-packed spheres via stable optic modes along regular arrays of transparent spheres, and then produces diffraction patterns after exiting from the lattice