This volume describes the theory and practical implementation of three techniques for the generation of blue-green light: nonlinear frequency conversion of infrared lasers, upconversion lasers, and wide bandgap semiconductor diode lasers. In addition, it looks at the various applications that have driven the development of compact sources of blue-green light, and reflects on the recent application of these lasers in high-density data storage, color displays, reprographics, and biomedical technology.