The method of patterned photoactivation is a natural fit for the study of neuronal dendritic integration. Photoactivatable molecules that influence a wide range of extracellular and intracellular neurophysiological functions are available. The choice of photosensitive molecules depends on the research question and will influence the design of the experimental apparatus. This article describes an acousto-optical deflector (AOD)-based system for rapid ultraviolet (UV) photolysis in arbitrary spatial and temporal patterns. Some basics of caged neurotransmitters and the theory of operation of AODs are covered, as are descriptions for implementing the system.