Wireless Optical Communication Systems addresses the problem of designing efficient signalling and provides a link between the areas of communication theory and modem design for amplitude constrained linear optical intensity channel. Topics include historical perspective, channel impairments, amplitude constraints and the characteristics of popular optoelectronic components. A variety of wireless optical channel topologies are presented along with a survey and analysis of present day signalling techniques employed for these channels. The author provides a unifying framework for signalling design which allows the channel constraints to be represented geometrically and permits the use of modem design principles from electrical channels. Modulation schemes are designed using the formalism of lattice codes and a design process for signalling sets is specified.