"Confocal microscopy of colloids"
V. Prasad, D. Semwogerere, and Eric R. Weeks, J. Phys.: Cond. Mat. 19, 113102 (2007).

Colloids have increasingly been used to characterize or mimic many aspects of atomic and molecular systems. With confocal microscopy these colloidal particles can be tracked spatially in three dimensions with great precision over large time scales. This review discusses equilibrium phases such as crystals and liquids, and non-equilibrium phases such as glasses and gels. The phases that form depend strongly on the type of particle interaction that dominates. Hard-sphere like colloids are the simplest, and interactions such as the attractive depletion force and electrostatic repulsion result in more nontrivial phases which can better model molecular materials. Furthermore, shearing or otherwise externally forcing these colloids while under microscopic observation helps connect the microscopic particle dynamics to the macroscopic flow behavior. Finally, directions of future research in this field are discussed.