ABSTRACT
Scientists and engineers have advanced the field of lasers by not only incorporating these tools into useful systems but also by developing myriad assortments of new laser sources. Lasers can be found operating at power levels ranging from nanowatts to terawatts, at wavelengths from the microwave to the X-ray spectral region, and with pulse durations ranging from femtoseconds to continuous wave. The special properties of the laser make it an indispensable tool for applications from lighting to medical and military applications. The key concepts associated with the field of lasers and important characteristics are introduced in this entry.
