Nonlinear optical techniques are now recognized as the most efficient means available to generate laser radiation at wavelengths that are presently inaccessible via conventional sources. This technology uses nonlinear optical crystals for the frequency conversion of laser light. The book contains the most complete and up to date reference material on properties of nonlinear optical crystals, describes their applications, both traditional and specific, and provides the main mathematical formulas necessary for the calculation of the frequency conversion process. It is a vital source of information for scientists and engineers dealing with modern applications of nonlinear optical crystals in quantum electronics, optoelectronics and laser physics.