Low power diode lasers are a well established technology, used extensively in products such as DVD players, computer optical drives, fiberoptic telecommunications and even laser pointers. The reason for this success is that diode lasers offer a combination of high electrical efficiency, long maintenance-free lifetimes, small size, and short wavelength that far surpasses any other laser technology. While these commonly encountered low power diode lasers typically only provide a few milliwatts of output, diode laser systems are available with power levels in th e multi-kilowatt range. These types of diode lasers are currently employed in a number of different materials processing applications . The basic construction and operation of these systems is described here.